Abstract:
The invention relates to a device for the application of fluid materials to a surface of a sheet-form material, comprising an application roller, with a roller body and a jacket surface, which, by means of at least partial contact with the sheet-form material, transfers the fluid materials leading to the sheet-form material. The invention further comprises an application doctor blade, with a pre-dosing channel for the supply of fluid materials leading thereto and which at least partly coats the application roller with fluid material. A flow of a medium is provided in at least one region adjacent to the jacket surface, which is directed from the longitudinal mid-axis of the application roller to the outside.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a device for the application of fluid materials to a surface of a sheet-form material, with an application roller which has a roller body with an outer surface which when at least partially abutting on the sheet-form material transfers the fluid material to the sheet-form material. 
     TECHNICAL FIELD 
     Numerous apparatuses are already known for the application of fluid materials to a surface of a sheet-form material. Each of these apparatuses requires a special adaptation to the respective materials to be applied and to the circumstances as regards the properties of the sheet-form material, processing temperature, speed and the amount of the material to be applied and also the kind of the material to be applied. 
     In laminating at least two sheet-form materials it is necessary that a defined amount of fluid materials, particularly adhesive, is applied to at least a first layer of the sheet-form material, so that this layer is applied to at least a further layer of a sheet-form material and remains on this at least one layer of the sheet-form material due to a resulting adhesive bond. The sheet-form material can be, for example, very thin polymer foils or carrier layers, which are extremely sensitive to tensions. Furthermore, a further layer can be laminated, for example, onto a layer with visual information. For this, it is necessary that a uniform bonding between the layers is made possible, so that the information can be recognized and examined. 
     The use of fluid materials, particularly adhesives, which are taken up by an application roller from a supply region and transferred to the sheet-form material, is necessary for the lamination of layers. In this process of applying the fluid material to the sheet-form material, particularly in the case of adhesives, a soiling of the application roller and its bearing regions occurs. The functional ability or the rotation of the application roller can thereby be worsened or even stopped, which can result in an uneven application of the fluid material to the sheet-form material, or an application of the fluid material to the sheet-form material is rendered impossible. 
     SUMMARY OF THE INVENTION 
     The invention therefore has as its object to provide an apparatus for the application of fluid materials to the surface of a sheet-form material, which makes possible a uniform application of a set thickness of a film during a very long duration of operation. 
     This object is attained with a metering doctor to which a pre-metering channel leads for provision of the fluid material and at least partially wets the application roller with fluid material. A flow of a medium directed substantially outward from a longitudinal mid-axis of the application roller is provided at least in a region bordering on the outer surface of the application roller. 
     By the use of a medium which at least partially flows radially outward in the edge region of the roller body of the application roller, it is made possible that the fluid material, seen in the axial direction, does not leave the outside surface of the roller body at least in the direction of the bearing regions of the application roller, so that a penetration of the fluid material to the bearing regions of the application roller is prevented. By the bounding of the outside surface by means of a fluid medium, a defined application width of the fluid material on the surface of the sheet-form material can be given, which can be adjusted to the requirements for the further processing of the sheet-form material onto a further layer of a sheet-form material, particularly when the sheet-form material is wider than the outside surface of the application roller. 
     The air flowing out in the edge region of the roller body of the application roller forms a seal of the bearing region, which furthermore makes it possible for the application roller to be used both for a so-called flying coating, in which the application roller works solely against a sheet tension of the sheet-form material, and also for a coating with the use of a counterpressure roller. 
     According to an advantageous embodiment of the invention, it is provided that at least one axial bore is provided at least at one end of the application roller, and cross bores branch off therefrom, preferably in the edge region of the outside surface. The medium, preferably under pressure, can thereby be supplied in a simple manner to the edge region of the outside surface, so that a lateral sealing of the application roller relative to the respective bearing is made possible. 
     According to a further advantageous embodiment of the invention, it is provided that a receiving member is provided at each end of the roller body and forms with the edge region of the roller body a gap leading outward. Sealing of the bearing regions and limitation of the outside surface of the roller body as application surface is thus made possible. It is advantageously provided that the receiving member at least partially covers the cross bore. A guide channel or gap for the medium can thus be formed by a receiving member in a simple manner, and is constituted as far as the outside surface of the roller body. 
     According to a further advantageous embodiment of the invention, it is provided that the receiving member is constituted as a bearing and has a bearing section for receiving the application roller. Thereby on the one hand, the number of components is reduced, and also, on the other hand, simple and rapid mounting is made possible. 
     According to a further advantageous embodiment of the invention, it is provided that the end face of the roller body and the surface of the receiving member arranged complementary thereto form a gap which is directed at right angles to the longitudinal axis of the application roller or at an angle in the direction of the edge region of the sheet-form material or of the bearing regions. A fluid material possibly overflowing over the edge region of the outside surface of the roller body can thereby be guided away laterally outward, without the set coating thickness of the fluid material on the sheet-form material being adversely affected. 
     According to a further advantageous embodiment of the invention, it is provided that the gap between the end face of the roller body and the receiving member is adjustable. The sealing can thereby take into account the respective case of application and the sensitivities of the fluid material and of the sheet-form materials. The flow speed of the medium which flows outward through the gap can advantageously be likewise adjustable. 
     According to a further advantageous embodiment of the invention, it is provided that a UV crosslinking-active adhesive is provided. In particular, this embodiment is of particular advantage with these adhesives which immediately harden or polymerize when subjected to shear. 
     According to a further advantageous embodiment of the invention, it is provided that compressed air us used as the medium. A cost-favorable embodiment can thereby be given, since the surrounding air can be compressed and used. It can alternatively be provided that special gases or liquid media or the like are used in order to effect a sealing of the bearing regions. 
     According to a further advantageous embodiment of the invention, it is provided that the application roller is received by adjustable bearings. It is thereby made possible for the amount of the fluid material taken up from a metering region of the application roller to be adjustable. The bearings can also serve as an additional possibility of adjustment to the metering doctor. Furthermore, changes due to the use of the application roller and possibly of the bearings can be adjusted for. 
     According to a further advantageous embodiment of the invention, it is provided that the rotation speed of the application roller is equal to or smaller than the sheet speed of the sheet-form material. Thereby a more uniform and thinner film of a fluid material can be applied. In this mode of operation, it can advantageously be provided that the sheet-form material abuts the application roller under tension, which can be adjusted by means of a guide roller before and after the application roller in the sheet forwarding direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A particularly preferred embodiment of the invention is shown in the following description and the accompanying drawings, in which: 
     FIG. 1 shows a schematic side view of the apparatus according to the invention; 
     FIG. 2 shows a schematic enlarged partial view, partially in cross section, of the apparatus according to the invention according to FIG. 1; 
     FIG. 3 shows a schematic enlarged sectional diagram of a top plan view according to FIG. 2; 
     FIG. 4 shows a schematic detail diagram of an application roller and its bearing arrangement; 
     FIG. 5 shows a detail view of the application roller in cross section; and 
     FIG. 6 shows an excerpt from a schematic enlarged side view of the apparatus according to FIG. 1 in an alternative mode of operation for the application of the fluid material to a surface of the sheet-form material. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A side view of an apparatus  11  for the application of a fluid material to a surface of a sheet-form material  12  is shown in FIG.  1 . The material  12  is drawn from a supply roll  13  and guided over guide rollers  16 ,  17 ,  18  to an application roller  19  for applying the fluid material to the sheet-form material  12 . 
     The sheet-form material  12  coated with fluid material is deflected by means of a transport roller  21  and supplied to a foil or a film  23 , in order to form a composite  24 . The foil  23  is forwarded by a roller  26  to the apparatus  11 , guide rollers  27 ,  28  being provided before and after the apparatus  11  and causing the foil  23  to wrap around the roller  26 . 
     FIG. 1 shows, for example, a processing station in a plant consisting of plural stations. The operational process described hereinafter, in which the apparatus  11  undertakes an operational step, represents a case of application for this embodiment example. 
     For the production of documents which are secure against forgery, a photopolymer film with holograms is for example used. These photopolymer foils are delivered with protective layers on both sides. For further processing into a document which is secure against forgery, it is necessary for the protective layers to be removed and for subsequent carrier layers to be applied. In a first operation cycle, a delaminating apparatus (not shown) which removes the protective layer can be provided, for example on the roller  26 . A carrier layer is then applied as a sheet-form material  12  to the photopolymer foil by the apparatus  11  according to the invention. A hardening device is provided following the apparatus  11  and produces a composite  24  between the applied carrier layer and the photopolymer foil, a UV crosslinking-active adhesive being provided, preferably as a fluid material. In a second operating cycle, which follows the first operation cycle just described, the process can be repeated for the second side. Because of the high processing speeds and quality requirements, it is necessary that the carrier layer has a fluid material applied to one surface, uniformly and with constant film thickness, so that in the further processing a bubble-free and continuously crosslinked composite due to the adhesive results between the applied carrier layer and the photopolymer film. 
     The apparatus  11  for applying fluid materials to the surface of a sheet-form material  12  can be used for further cases of application which are similar to, or deviate from, the case of application described hereinabove. Here foils a few micrometers thin, or also thick foils, of plastic or other materials, can be likewise treated and processed. 
     A fluid material is stored in a dispenser  31 . When a UV crosslinking-active adhesive is processed, a light-protected dispenser  31  is preferably used. The fluid material is supplied from this dispenser  31  by static pressure by means of a housing section  32  to a pre-metering channel  33  of an application head  34 . This is shown in detail in a partial sectional view of the apparatus  11  according to FIG.  2 . The fluid material is supplied via the pre-metering channel  33  to a metering doctor  36 , which is preferably constituted as a metering bar. This metering doctor  36  is adjustable by means of a setting mechanism  37  so that the transverse profile is thereby adjustable along the metering doctor  36 . The metering doctor  36  is furthermore rotatably mounted. In a position of a break-off edge facing toward the application roller  19  as shown in the drawing, the gap is zero. The size of the gap can be adjusted with an anticlockwise rotation of the metering doctor  36 , the gap size increasing with an increasing degree of rotation. The amount of the fluid material to be taken up by the application roller  19  can thereby be determined. The metering doctor  36  is provided with metering pockets  40  extending at least over the length of the outside surface  59  of the roller body  58 . The metering pockets could be provided in they form of a recess. The application roller  19  is provided in an upper section of the application head  34 , a segment region  38  being arranged outside the application head  34 . The sheet-form material  12 , which is constituted as a carrier layer according to the embodiment example described above, is guided past this segment region  38  which stands out with respect to the application head  34 . The guide roller  18  and the transport roller  2 I are positioned with respect to the application roller  19  so that the sheet-form material  12  abuts the application roller  19  with at least slight tension. The transport roller  2 I can be adjusted in its position with respect to the application roller  19  by means of an adjusting mechanism  39  shown in detail in FIG.  6 . The arrangement with respect to the roller  26 , also respectively the distance or pressure, can likewise be adjusted by means of this adjusting mechanism  39 . 
     The apparatus  11  can be mounted on a housing of the equipment by means of the elements identified with the reference numeral  41 . The housing section  32  and also the application roller  19  and transport roller  21  connected to it can be moved away from the roller  26  in a simple and rapid manner by means of two shafts  42  (FIG. 2) projecting into the housing section  32 , in order to clean or newly insert the parts, or to feed in new sheet-form material. 
     A schematic top plan view according to FIG. 2 is shown in partial cross section in FIG.  3 . The roller  21  is constituted wider than the roller  26  for the application case described by way of example. The relationships with respect to the width of the rollers  21  and  26  and also their diameter can be selected specifically for an application. This likewise holds for the relationships of the application roller  19  and of the metering doctor  36 . 
     The application roller  19  is shown in detail in FIG.  4 . This application roller  19  is rotatably driven. For example, a drive shaft  43  is provided which engages a coupling  44  which is constituted as a roller-mounted shaft. A spigot connection  45  is provided on the end remote from the drive shaft  43 , and transmits the rotation of the drive shaft  43  to the application roller  19 . For this purpose, a U-shaped recess is provided on a connecting piece  46  of the application roller  19 , with a bolt  47  engaging in it and equalizing axial tolerances between the coupling  44  and the application roller  19 . 
     The application roller  19 , shown in complete cross section in FIG. 5, has a left-hand and a right-hand bearing region  48 ,  49 . These shaft sections are of crowned form and are rotatably mounted in a receiving member  51 ,  52  which can be installed on the housing section  32 . The crowned form can provide an axial compensation between the left and right receiving members. Even with a small displacement of the mutually opposite receiving bores of the holding elements, a smooth-running rotation of the roller without jamming can be given. The application roller  19  is constituted as a hollow shaft and has a through bore  53  situated in the longitudinal mid-axis  55  and connected on one side to two axial bores  54 . In the region of the bearing region  49 , the through bore  53  is closed, sealed to medium, by a threaded pin  56  or the like. The application roller  19  has a roller body  58  with an outside surface  59  by means of which the fluid material is transferred to a surface of the sheet-form material  12 . End faces  61 ,  62  are provided in the transition region between the bearing regions  48 ,  49  and the roller body  58 , and form with the receiving members  51 ,  52  a gap  63 . Complementary sections  66 ,  67  of the receiving member  51 ,  52  are provided in the region of the end faces  61 ,  62 , and extend over the whole periphery. 
     In the housing section  32 , a counter-bearing  69  is provided at the end of the application roller  19  opposite the drive shaft  43 , making a supply of the medium possible via connections  71  into the axial bores  54 . The medium, preferably under pressure, reaches the through bore  53  via the axial bores, and from there passes outward via cross bores  82 ,  83  branching therefrom. The medium is deflected by the receiving member  51 ,  52  covering the openings  84  of the cross bores  82 ,  83 , and is conducted outward by means of the gap  63 . A leakproof or nearly sealing connection is produced by the bearing regions  48 ,  49  and the receiving members  51 ,  52 , so that medium emerging from the cross bores  82 ,  83  is positively guided outward by the gap  63 . 
     In a preferred embodiment of the invention, it is provided that air is used as the medium, and is preferably conducted outward under pressure through the gap  63 . Likewise, gaseous, liquid, or gel-form media or the like can be used, depending on the case of application. 
     Sealing-off of the bearing regions  48 ,  49  can be attained by blowing air in, the air flowing at least partially radially outward through the gap  63 . This is particularly advantageous with the use of UV crosslinking-active adhesives, which would harden in a short time when exposed to shear stress, as is the case when the adhesive enters the bearing regions  48 ,  49 . Stoppage of the application roller or impairment of its operation can thus be counteracted. 
     The gap  63  is arranged at an angle due to the side surfaces  61 ,  62  and the complementary sections  66 ,  67  of the receiving members  51 ,  52 , so that the direction of blowing out faces outward with respect to the outer surface  59 . The fluid material coming out over the edge region of the outer surface  59  can thereby be blown off, so that this does not accumulate in the region of the gap  63 . 
     The design of the gap  63 , as regards width and also direction, can take place optionally; the alignment in FIG. 4 is solely by way of example. The gap  63  can be constituted constant or nozzle-shaped toward the outer surface  59 , so that a kind of venturi effect can arise in the outermost edge region between the outer surface  59  of the roller body  58  and the sections  66  and  67  of the receiving members  51 ,  52 . It can furthermore be provided that instead of a complete, radial outflow of the medium, an at least partial and/or swirled outflow is provided. It can furthermore be provided that the constitution of the gap  63  is provided by inserts which can be installed on the end faces  61 ,  62  and communicate with the receiving portions  51 ,  52 . It can likewise be provided that the receiving members  51 ,  52  have interfaces to receive inserts, which are interchangeable. The size, the kind, and also the length of the gap can be selectively varied and adapted specifically to the application in dependence on the case of application. This can be made possible, for example, by ring segments which can be fixed on and interchanged. The application roller  19  furthermore has an adjustable mounting, which makes it possible for both an adjustment as regards the axial spacing from the metering doctor  36  and also an axially parallel adjustment. 
     The application roller  19  is made of a material which is resistant to the fluid material. For example, stainless steel or bronze or the like can be provided. The structure or surface of the outer surface  59  can be implemented specifically for the application. The use of compressed air for sealing the gap  63  between the outer surface  59  of the application roller  19  and a receiving member  51 ,  52  adjoining thereto can for example begin at 0.1 bar and rise to one or more bar. 
     In the case described hereinabove of use of the embodiment example, the width of the outer surface  59  is constituted smaller than the width of the strip material  12 . An overflow of the fluid material at the side regions of the sheet  12  of material can be trapped by this itself, so that clean processing is made possible. The sheet-form material  12  applied to the foil  23  has, as a composite  24  in the end state, a sheet width which is smaller than the width of the outer surface  59 , so that a composite  24  is created which has a bond completely over its width. 
     FIG. 6 shows an adjusting mechanism by means of which the position of the transport roller  61  can be adjusted relative to the housing section  32 . A wedge  92  is moved up and down in a slot by means of an adjusting screw  91 , and is connected to a spring-loaded bolt  93 . The bolt  93  can be inserted to a greater or lesser extent into the housing section  32  by changing the wedge position. The position of the transport roller  21  relative to the application roller  19  and to the roller  26  can thereby be adjusted, as is shown by dashed lines and as this reproduces the position according to FIGS. 1 and 2. With this arrangement, by means of the sheet tension, a more or less heavy abutment of the sheet-form material  12  on the application roller  19  is attained. A more or less strong sheet tension can be produced, in dependence on the strength of the sheet-form material  12 . The application roller  19  has a speed of rotation which is equal to, or smaller than, the sheet speed of the sheet-form material  12 . An application against the sheet tension can thereby take place, so that a so-called flying coating is achieved. 
     It can alternatively be provided that the transport roller  21  is arranged in a position which abuts on the application roller  19 , as shown in FIG.  6 . The pressing pressure of the roller  21  can by adjustable relative to the application roller  19  by means of the adjustment mechanism  39 . The position of the transport roller  21  relative to the roller  26  can also be set at the same time. The adjustment mechanism  39  has a bearing element  94  by means of which the two above-described positions of the transport roller  21  can be set.