DE4433054C1 - Process for hot imprinting substrates - Google Patents

Abstract

The hot imprinting process involves passing the substrate and imprinting foil with colour layer opposite each other through an imprinting unit with heater, printing head (16) and counter-pressure drum (12). For preheating, the substrate and foil are pushed onto the surface (20) of the counter-pressure drum. The printing head alternately prints one line in the circumferential direction over the drum surface concentric with it. Then the printing head is pushed forward to print another line across the circumferential direction and parallel to the drum surface.

Description

The invention relates to a method and an apparatus for Printing on a substrate by hot stamping, in which the substrate and an embossing film provided with a colored body layer with the Colored body layer of the surface of the substrate to be printed are led through an embossing station on the opposite side, in which the substrate and the embossing foil between heat a printhead and a counter pressure element under transfer of colored bodies are pressed together on the substrate and min preheated the stamping foil before reaching the stamping station as well as the embossing power point or character successively in series is applied below.  

Among the various processes for printing substrates, Hot stamping is particularly notable for labels, that there are prints of durability well above average leads. Substrates printed by hot stamping therefore enjoy a high esteem by the industry. This high permanent Activity of the print is also given when the substrate z. B. as Roughly treat the label after its manufacture lungs will be exposed. This rough treatment comes along Labels on pieces of textile are particularly common if they have been chosen or dry cleaned. For labels for textile pieces there are not only special requirements for the print, but also to the substrate: this should not only be the same be as permanent as possible, but also sympathetic feel. Textile fabrics are durable and, provided they are uncoated are easy to grip and are therefore often used as a substrate for labels ten used for textile pieces.

The information printed on the respective substrates are extremely diverse. For labels for textiles pieces can do this e.g. B. in addition to the legally required Care instructions also trade names, sizes, serial numbers or Be control numbers. The latter are often used for every textile piece and thus assigned individually for each label, so that in in such cases, each label with an individual print is provided. The frequent change of imprints requires a flexi bles printing process with which without changing the print matrix zen different substrates every time the print is changed print cleanly. It is particularly important to note that the Substrates do not always have a smooth surface, such as this. B. is the case with paper or plastic films, but also rough or can be heavily textured, e.g. B. in the case of uncoated Textile fabric or leather.

From the European patent specification 0 179 977 a method and  a device for printing a substrate by hot stamping known. The method described there allows instead of one rigid pressure matrix a computer controlled needle to use printhead because of the heat needed to transfer Dyes from a ribbon-shaped stamping foil on the same ribbon-shaped substrate is necessary, not from the needle printhead in the Colored body layer is introduced on the carrier film, but by Heating elements on which the stamping foil with the colored body layer is passed before it passes the wire printhead. While During printing, the needle print head moves across the direction of travel of stamping foil and substrate. It can happen that the Dot matrix print head due to incorrect programming over the page margin the stamping foil and the substrate is led out and itself then moving back from outside the stamping foil over the stamping foil with its shooting needles on the textile fabric of the substrate and / or hooked onto the carrier film, so that the Bend the needles and the needle print head is damaged. Such Damage to printheads is in the process and the device occurred in practice according to EP 0 179 977 and have due to the the cost of the damage associated with the damage Process and the device limited.

Furthermore, one is from the German utility model G 88 14 238.8 Printing device for printing forms known in which the Forms to be printed in a swiveling holding device can be held and both the holding device with the Pressure abutment as well as the print head on a swivel frame are attached and are therefore pivotable.

Furthermore, from the UK patent application 20 47 170 is a print direction for tickets and the like, where the tickets are a rotatable cylinder and a printhead in parallel can be moved to the longitudinal axis of rotation by turning the Cylinders and moving the print head the entire ticket area to be able to print.

The invention is therefore based on the object, a method and to create a device of the type mentioned, the the risk of damage reduce the print head as much as possible.

The problem is solved with a method of the beginning mentioned type in that the substrate and the stamping foil for preheating zen and embossing on a cylindrical, heated surface of the counter be pushed forward and that the print head alternie rend for sequential embossing in the circumferential direction via the cylin shaped surface and transverse for the transition to a new embossing line  is advanced to the circumferential direction. The apparatus solution exists in a device in which the back pressure element as a heated Drum is formed on which the substrate and the stamping foil during preheating and embossing, for which Printhead a two-axis guide is provided on the one hand along a circular path over the drum and on the other hand parallel is directed to the direction of the drum axis over the drum circumference and in which a drive for the print head is provided, this while embossing an embossing line along the circular path and then to the beginning of a new embossing line parallel to the drum axis pushes.

An advantage of the invention over the prior art is in that the embossing along the longitudinal direction of the embossing film and of the substrate happens so that the print head never shoots with eating needles can hit the edge of the foil. also only a straight guide for the printhead must be provided to to equip the printhead with two lines of freedom for the movement ten since the second movement is a circular movement around the longitudinal axis of the Is drum that easily made possible with the help of ordinary radial bearings can be light.

In the method according to the invention the feed is from Substrate and stamping foil advantageously on and over the zylin deriform surface in the circumferential direction to this surface.

In addition, a method according to the invention is preferred in which the substrate and the stamping foil gradually over the cylinder area and the embossing force during the Movement breaks of substrate and stamping foil is applied.

In a preferred embodiment of the invention direction, the drum is divided into a plurality of sectors  and each sector is equipped with a separately controllable heater continuous

It is also advantageous if the drum in the axial direction is divided into several heating sections, each heated separately are cash.

Further advantages result if the drum peripheral surface in within a wrap angle, in the substrate and stamping foil rest on it, circumferentially in a preheating and a Printing zone for substrate and stamping foil is divided.

In the preferred embodiment of the device is the drum rotatably mounted.

Furthermore, a device is preferred in which the circular path guide tion for the printhead from a rotatable around the axis of the drum Writing carriage is formed, the drum in the axial direction overlaps and parallel to the drum axis a slide guide for has the printhead.

Finally, a device is preferred in which the diameter the drum is chosen so that the circumferential length of the printing zone to be processed equal to or larger than the largest in the circumferential direction en label is.

Further advantages of the method and the device according to the invention are described below with reference to the attached figures explained. These show:

Fig. 1 is a perspective, schematic representation of the preferred embodiment;

Fig. 2 is diagram for relative movement of the print head to substrate in the prior art;

FIG. 3 is diagram for relative movement of the print head substrate according to the invention;

Fig. 4 side view of an embodiment of the inventive device;

Fig. 5 supervision of a label printer, which includes the device according to the Invention.

In its embodiment according to FIG. 1, the device has a drum 12 and a holder and a guide 14 for a print head 16 . From the drum longitudinal axis 18 an upper Schwen arm 22 a and a lower pivot arm 22 b of the guide 14 , each of which is long enough to protrude beyond the drum circumference. Between the swivel arms 22 a, 22 b there is a straight guide 24 running parallel to the drum longitudinal axis 18 and to the drum peripheral surface 20 as part of the guide 14 .

The guide 14 is pivotally mounted about the drum longitudinal axis 18 so that the print head 16 can perform a circular movement along a parallel surface to the drum peripheral surface 20 . The straight guide 24 lies opposite the cylindrical drum peripheral surface 20 and enables the print head 16 to move vertically parallel to the drum longitudinal axis 18 on the parallel surface to the drum peripheral surface 20 .

Substrate 26 and embossing foil 28 wrap a part of the cylindrical drum peripheral surface 20 in the circumferential direction. The substrate 26 lies directly on the drum peripheral surface 20 , while the embossing foil 28 lies with its colored body layer on the substrate 26 . The wrap angle within which the substrate 26 and the embossing film 28 lie on the drum peripheral surface 20 is approximately 300 ° in FIG. 1. The area of the drum circumferential surface 20 within the wrap angle is divided in the circumferential direction in each case approximately half into a preheating zone 30 and a printing zone 32 lying in the swiveling range of the print head 16 . The drum peripheral surface 20 is heated at least in the area within the wrap angle. The heater is located inside the drum 12 . In individual cases it can be advantageous if individual sectors and / or longitudinal sections of the drum 12 can be heated separately, so that any heating profiles can be set and adapted to the stamping foil or substrate material to be processed.

The wrap angle and the division of the area lying within the looping region of the drum peripheral surface 20 into a preheating and a printing zone depend largely on the size of the labels that are to be provided with a print using the device. The radius of the drum 12 and the pivoting angle of the guide 14 for the print head 16 are expediently chosen so that the length of the print zone 32 in the circumferential direction is not shorter than the largest label to be processed in the circumferential direction.

For printing (embossing) of the substrate 26 , the substrate 26 and the embossing film 28 are gradually guided over the cylindrical drum circumferential surface 20 . The part lengths of the substrate 26 and the embossing film 28 transported during a transport step appropriately correspond to an integer multiple of the elongation of a label in the circumferential direction and are not greater than the length of the printing zone 32 in the circumferential direction of the drum 12 . In order to simplify the transport of substrate 26 and embossing film 28 along the drum circumferential surface 20 , the drum 12 can be rotatably mounted about its longitudinal axis 18 .

After each transport step of the substrate 26 and the embossing foil 28 at least those are partial length of the substrate 26 and the Prägefo lie 28 which are located in the region of the preheating zone 30 on the peripheral surface of the drum 12, preheated, while those partial lengths of the substrate 26 and the embossing foil 28, which wrap around the printing zone 32 of the drum 12 , participate in the printing process (embossing process). Here, the print head 16 of the guide 14 within an angle, for example, corresponding to half the wrap angle, in a circular movement around the cylindrical drum circumferential surface 20 , and thus parallel to the longitudinal direction of substrate 26 and stamping foil 28 , is pivoted back and forth. Only during this pivoting movement, the needles of the print head 16 are shot depending on the desired imprint on the embossing foil 28 . As a result of the pressure that a needle of the print head 16 exerts on the ink body layer facing the substrate 26 when it hits the embossing film 28 , the dye is transferred from the embossing film 28 to the substrate 26 in the region in which pressure is acting. A print line is created during a swivel movement. When the print head 16 has reached one of the two end positions of its swiveling movement, it is offset parallel to the longitudinal axis 18 of the drum by the height of a print line. The next print line is then applied to the substrate during a further swiveling movement. The pivoting of the print head 16 and the displacement of the print head 16 by one print line are alternately repeated until the entire surface of the substrate 26 located within the print zone 32 is printed.

The area of the substrate 26 located within the printing zone 32 may correspond to one or more of the future labels. When the printing of a partial length of the substrate 26 has been completed, the substrate 26 and the embossing film 28 are transported forward by a further partial length in a further step. Those partial lengths of substrate 26 and embossing film 28 , which were located in the preheating zone 30 before the transport step, are after this step in the printing zone 32 and are processed there by the print head 16 in the manner described.

How the movement of the print head relative to the substrate 26 or the embossing film 28 in the method according to the invention differs from that in the method according to the prior art can be seen from a comparison of FIGS. 2 (prior art) and 3 (present invention) ). In both figures, the substrate 26 is shown in the form of a continuous band 40 with side edges 42 . The future labels in each case correspond to regions 44 of the same size on the belt 40 , the boundaries of which are represented by dashed lines 46 in the sketch. An arrow 48 indicates the transport direction of the belt 40 in its longitudinal direction. The movement of the print head 16 relative to the ribbon 40 during the actual embossing process, that is to say with needles being fired, is identified by the narrow arrows 50 .

In the conventional method ( Fig. 2), the side edges 42 of the tape 40 are also the side edges of the future labels if the labels of the edges of a rectangle label are chosen such that a line of text on that label extends from one side to the other while the label the top and bottom edges are the edges parallel to the text line. Within the meaning of this definition, the areas 44 representing the labels are arranged one below the other in the longitudinal direction of the band 40 . The movement of the printhead 16 during the actual embossing process, during which its needles are repeatedly shot from a housing of the printhead 16 onto the embossing foil 28 , takes place along a line of text, that is to say transversely to the side edges of the areas 44 and thus simultaneously to the Side edges 42 of the band 40 , as indicated by the arrows 50 . If the printhead 16 is moved beyond a side edge 42 as a result of a misprogramming or other error in the embossing process, its needles, when they are currently moving on the drum peripheral surface 20, can get caught on the edge of the substrate or the stamping foil and consequently bend so that the print head 16 is damaged.

In the method according to the invention ( FIG. 3), the areas 44 corresponding to the labels are arranged next to one another in the sense of the above definition, that is to say side edge to side edge on the belt 40 . The side edges 42 of the tape 40 later give the top or bottom edges of the labels. In the method according to the invention, the printhead 16 is moved transversely to the side edges of the labels during embossing, ie with shooting needles, but in relation to the band 40 this is a longitudinal movement. Since the side edges of the labels are only the imaginary dashed lines 46, which are not yet physically present during the printing process, there is no risk of the needles of the printhead 16 becoming caught and the printhead 16 being damaged as a result. As can be seen in Fig. 3, the print head can be moved in a longitudinal movement over several labels. At the end of each longitudinal movement, the print head 16 stops and, with the needles protected and therefore protected, is displaced by one print line transversely to the longitudinal direction of the band 40 . This is indicated by the dashed arrows 52 .

The details of this embodiment can be seen from the side view of the device according to FIG. 1 shown in FIG. 4. The central element of this device is the drum 12 with its vertically running longitudinal axis 18 . The drum 12 is mounted on a base plate 60 . Above the drum 12, the upper arm goes from the drum longitudinal axis 18 in horizontal he direction 22 a of which is longer than the drum radius, and thus projects laterally beyond the drum peripheral surface. Below the drum 12 and below the base plate 60 goes from the drum axis 18 of the lower arm 22 b, which is stronger and longer than the upper arm 22 a.

Outside the drum circumferential surface, the upper swivel arm 22 a and the lower swivel arm 22 b are connected to one another by two round rods 62 parallel to one another and to the drum longitudinal axis 18 and to the drum circumferential surface 20 . These round bars 62 form the straight guide 24 for a carriage 64 on which the print head 16 is attached.

The printhead 16 can be moved in the vertical direction parallel to the longitudinal axis 18 of the drum along the straight guide 24 . For this purpose, the carriage 64 is connected to a toothed belt 66 . The toothed belt 66 is guided on the one hand around a loose toothed roller 68 attached to the upper swivel arm 22 a, and on the other hand around a toothed wheel 70 on the shaft of a motor 72 for the vertical drive. The motor 72 is attached to the strong lower swing arm 22 b.

The complete guide 14 for the print head 16 , consisting of the upper swivel arm 22 a, the two, the straight guide 24 forming, parallel rods 62 , the carriage 64 with the print head 16 , the sprocket 68 , the gear 70 , the between gear 70 and sprocket 68 ver current timing belt 66, the motor 72 and the lower arm 22 b, surrounds the drum 12 and to the drum longitudinal axis 18 pivots and driven. The swivel drive takes place via a large gear 74 fastened to the lower swivel arm 22 b, the axis of which is aligned with the longitudinal drum 18 . This large gear 74 is driven by a second toothed belt 76 by a small gear 78 which is attached to the axis of a motor 80 for the pivot drive. The complete swivel drive, consisting of the large gear 74 , the second toothed belt 76 , the small gear 78 and the motor 80 , is located like the lower swivel arm 22 b of the guide 14 below the base plate 60 .

The essential elements of the device according to the invention described on the basis of the schematic illustration in FIG. 1 and with the aid of the side view in FIG. 4 are parts of a label printer as shown in the top view in FIG. 5. In this Dar position, the guide 14 is shown with the print head 16 in both possible end positions of its pivoting movement about the drum 12 . The item numbers 16 and 22 a denote the print head and the upper swivel arm in one end position, while the posi tion numbers 16 'and 22 a' denote the print head and the upper swivel arm in the other end position.

The base plate 60 , on which the drum 12 is fastened, has an opening in the pivoting region of the guide 14 , through which the lower part of the guide 14 is passed, so that the guide 14 engages around the drum 12 and its pivoting movement about the longitudinal axis 18 of the drum can run freely. In addition to the drum 12 and the guide 14 with the print head 16 , there are also a supply spool 90 for the substrate 26 , a dispensing spool 92 for the stamping foil 28 and a take-up spool 94 for the stamping foil 28 after stamping, some guides 96 , a pre-roll axis 98 and a material brake 100 , a detector 102 , a cutting device 104 for separating the individual NEN labels from the tape-shaped substrate 26 and a label stacker 106 are provided on the base plate 60 .

Starting from its supply spool 64 , the band-shaped substrate 26 is first guided over the pre-roll axis 98 , also called a dancer roll. Their task is to prevent large tensile forces in the substrate, which would occur if the substrate supply and the supply roll 90 were accelerated suddenly due to their inertia. For this purpose, the pre-roll axis 98 is pivotally mounted in a known manner around the center of the supply roll 90 and is provided with a spring.

Furthermore, the band-shaped substrate 26 is guided over a deflection roller 96 with a material brake 100 , which ensures that the band-shaped substrate 26 lies tightly around the drum 12 under slight tension. Between the material brake 100 and the drum 12 , the strip-shaped substrate 26 also passes a detector 102 , the functions of which are to detect adhesive spots in the strip-shaped substrate 26 and the end of the strip. With the aid of corresponding signals from the detector 102 , a control of the label printer ensures that the tape-shaped substrate 26 is not printed in the area of the adhesive areas, so as to prevent damage to the print head 16 as a result of material thickening in the area of these adhesive areas. In the case of the tape end, the detector 102 emits a signal which leads to the label printer being switched off.

The strip-shaped substrate 26 is guided from the detector 102 to the drum 12 and wraps around this drum 12 by approximately 240 °. The tape-shaped substrate 26 is then guided further to a cutting device 104 , in which the labels are separated by separating them from the tape-shaped substrate 26 as sections. The separated labels are stacked in the label stacker 106 .

A supply of the stamping foil 28 is located on the dispensing spool 92 . From there, the embossing film 28 is guided over three guides 96 to the drum 12 so that it rests with its colored body layer on the bandför-shaped substrate 26 and also wraps around the drum 12 , approximately in an angular range of 210 °. In the swivel range of the guide 14 with the print head 16 , both the ribbon-shaped substrate 26 and the embossing foil 28 lie on one another on the circumferential surface of the drum. The embossing foil 26 is guided from the drum 12 via four guides 96 to a take-up reel 94 . The take-up spool 94 receives the embossing film 28 after a part of the ink body layer has been transferred from the embossing film 28 to the band-shaped substrate 26 during the printing process.

Claims (10)

1. A method for printing a substrate by hot stamping, in which the substrate and a pre-film provided with a colored body layer are guided together with the colored body layer opposite the surface of the substrate to be printed by an embossing station in which the substrate and the stamping film act under heat be pressed together between a printhead and a counter-pressure element with the transfer of color bodies to the substrate and at least the stamping foil is preheated before reaching the stamping station and the stamping force is applied serially point by point or character by character, characterized in that the substrate and the stamping foil for heating and Embossing on a heated lateral surface of a zylinderför shaped counter-pressure element are advanced, and that the print head alternately for sequential embossing a line in the circumferential direction concentrically to the water and for the Transition to a new line across the circumferential direction and parallel to the lateral surface is advanced. 2. The method according to claim 1, characterized in that the feed of substrate and stamping foil runs in the circumferential direction on the lateral surface. 3. The method according to any one of claims 1 or 2, characterized in that the substrate and the embossing foil step be advanced over the surface and the embossing force applied during the pauses in movement of the substrate and stamping foil becomes. 4. Device for printing on a substrate ( 26 ) by hot stamping, with a stamping station having a print head ( 16 ) for the point or character application of a stamping force and a counterpressure element, with a device for preheating at least the stamping foil ( 28 ), characterized in that that the counter-pressure element is designed as a heated, cylindrical drum ( 12 ), on the outer surface ( 20 ) of which the substrate ( 26 ) and the stamping foil ( 28 ) lie during preheating and embossing,
that a guide (14) is provided for the print head (16) by means of on the one hand along a concentric to the envelope surface (20) circular path over the outer surface (20) and on the other hand parallel to the longitudinal axis (18) of the drum (12) over the outer surface ( 20 ) is feasible,
and that a drive for the print head ( 16 ) is provided, the sen during the embossing of a line along the circular path and then to the beginning of a new line parallel to the longitudinal axis ( 18 ) of the drum ( 12 ). 5. The device according to claim 4, characterized in that the drum ( 12 ) divided into a plurality of sectors and each sector is equipped with a separately controllable heater. 6. Device according to one of claims 4 or 5, characterized in that the drum ( 12 ) in the direction of the longitudinal axis ( 18 ) is divided into several heating sections, each of which can be heated separately. 7. Device according to one of claims 4 to 6, characterized in that the outer surface ( 20 ) within one of the sector, in the substrate ( 26 ) and stamping foil ( 28 ) on the drum mel ( 12 ) lie in the circumferential direction in a preheating zone ( 30 ) and a pressure zone ( 32 ) for substrate ( 26 ) and stamping foil ( 28 ) is divided. 8. Device according to one of claims 4 to 7, characterized in that the drum ( 12 ) is rotatably mounted. 9. Device according to one of claims 4 to 8, characterized in that the guide ( 14 ) for the print head ( 16 ) is formed by a about the longitudinal axis ( 18 ) of the drum ( 12 ) rotatable writing carriage which the drum ( 12 ) overlaps in the axial direction and guiding the print head (16) parallel to the longitudinal axis (18) of the drum (12) has a slide guide for the print head (16). 10. Device according to one of claims 7 to 9, characterized in that the diameter of the drum ( 12 ) is selected so that the circumferential length of the printing zone ( 32 ) is equal to or larger than a label to be processed largest in the circumferential direction.