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EP-4735259-A1 - APPLICATION SYSTEM, METHOD FOR PRODUCING A TRANSFER ROLLER AND APPLICATION PROCESS

EP4735259A1EP 4735259 A1EP4735259 A1EP 4735259A1EP-4735259-A1

Abstract

The invention relates to a system for an intermittent process for applying a transfer layer of a transfer film onto a substrate, the system being designed to prevent friction produced between the roller outer surface of a transfer roller and a transfer film rear side of the transfer film during the application process from creating a potential difference which is greater than the breakdown voltage of the transfer film, the roller outer surface of the transfer roller and/or the surrounding gas phase. The invention also relates to a process for producing the transfer roller, and to an application method.

Inventors

  • SCHINDLER, ULRICH
  • HOPFENSITZ, RALPH

Assignees

  • LEONHARD KURZ Stiftung & Co. KG

Dates

Publication Date
20260506
Application Date
20240627

Claims (20)

  1. 1. System (1) for a timed application process of a transfer layer (11) to a substrate (7), comprising a transfer roller (2) and a counter-pressure roller (3), and a transfer film (10), wherein the transfer roller (2) has an outer roller surface (4) and the transfer roller (2) and the counter-pressure roller (3) form a roller gap (5), wherein the transfer film (10) has a carrier layer (12) and a transfer layer (11) that can be detached from the carrier layer (12), and the transfer film back side (121) is formed by the carrier layer (12) and the transfer film front side by the transfer layer (11), wherein the transfer film back side (121) is in contact with the outer roller surface (4) of the transfer roller (2) and the transfer film front side is in contact with the substrate (7) in the roller gap (5), wherein the transfer layer (11) has at least is applied to the substrate (7) in regions, characterized in that the system is designed in such a way that the friction between the outer surface (4) of the transfer roller (2) and the back of the transfer film (121) during the application process prevents a potential difference being generated which is greater than the breakdown voltage of the transfer film (10), the outer surface (4) of the transfer roller (2) and/or the surrounding gas phase.
  2. 2. System (1) according to claim 1, characterized in that the outer roller surface (4) of the transfer roller (2) is conductive or dissipative.
  3. 3. System (1) according to claim 1, characterized in that the Fermi level of the roller outer surface (4) of the transfer roller (2) and the transfer film back side (121) are adapted to each other.
  4. 4. System (1) according to one of the preceding claims, characterized in that the outer roller surface (4) of the transfer roller (2) is formed by a functional layer (6), in particular wherein the functional layer (6) has a layer thickness selected from the range from 5 nm to 500 pm, preferably from 10 nm to 200 nm, more preferably from 30 nm to 55 nm.
  5. 5. System (1) according to claim 1 or one of claims 3 to 4, characterized in that the outer roller surface (4) of the transfer roller (2), in particular the functional layer (6), is formed from the same polymer as the carrier layer (12).
  6. 6. System (1) according to claim 1 or one of claims 3 to 5, characterized in that the polymer of the roller outer surface (4) of the transfer roller (2), in particular of the functional layer (6), and of the carrier layer (12) is selected from the group consisting of PFP, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene terephthalate, polycarbonate, polybutylene terephthalate, polylactide, cellulose diacetate, cellulose triacetate, BO-PET, starch blends, acrylonitrile-butadiene-styrene copolymer, cellophane, polymethyl methacrylate or copolymers and/or blends thereof.
  7. 7. System (1) according to claim 1 or one of claims 3 to 6, characterized in that the outer roller surface (4) of the transfer roller (2), in particular the functional layer (6), is formed from components which have a dielectric strength selected from a range from 5 kV/mm to 800 kV/mm, preferably from 100 kV/mm to 350 kV/mm, more preferably from 150 kV/mm to 300 kV/mm, in particular measured under normal climate and preferably on cleaned surfaces.
  8. 8. System (1) according to one of claims 1, 2 or 4, characterized in that the outer roller surface (4) of the transfer roller (2), in particular the functional layer (6), is designed such that the charge generated by friction is removed.
  9. 9. System (1) according to one of claims 1, 2, 4 or 8, characterized in that the outer roller surface (4) of the transfer roller (2), in particular the functional layer (6), has a surface resistance R n in the range from 0.001 Q/n to 5000 Q/n, preferably from 0.01 Q/n to 500 Q/n, more preferably from 0.1 Q/n to 1 Q/n, in particular measured with the 2-point method (2PP) and/or the 4-point method (4PP) and/or the Hall effect method and/or the Van der Pauw method and/or the contactless eddy current method.
  10. 10. System (1) according to one of claims 1, 2, 4 or 8 to 9, characterized in that that the outer roller surface (4) of the transfer roller (2), in particular the functional layer (6), has conductive components, in particular that the outer roller surface (4) of the transfer roller (2), in particular the functional layer (6), has metals selected from the group consisting of iron, nickel, titanium, chromium, molybdenum, manganese, tantalum, copper, gold, silver, aluminum or mixtures and alloys thereof, and/or conductive carbon modifications, in particular selected from the group consisting of graphene, fullerenes, carbon nanotubes, graphite, carbon black or combinations thereof, and/or conductive polymers.
  11. 11. System (1) according to one of claims 1, 2, 4 or 8 to 10, characterized in that the outer roller surface (4) of the transfer roller (2), in particular the functional layer (6), consists entirely of metal or has a binding agent.
  12. 12. System (1) according to one of claims 4 to 11, characterized in that the functional layer (6) is single-layered or multi-layered.
  13. 13. System (1) according to one of the preceding claims, characterized in that the outer roller surface (4) of the transfer roller (2) does not have any rubber, in particular soft rubber or hard rubber.
  14. 14. System (1) according to one of the preceding claims, characterized in that the transfer roller (2) has a rubber layer (9) comprising rubber, in particular soft rubber or hard rubber, wherein the Rubber layer (9) is preferably formed from a printing blanket, a cover or a coating.
  15. 15. System (1) according to claim 14, characterized in that the rubber layer (9), in particular the printing blanket, the cover or the coating, is multi-layered and has at least one fabric layer.
  16. 16. System (1) according to one of claims 15 or 16, characterized in that the rubber layer, in particular the printing blanket, the cover or the coating, comprises the components rubber, in particular soft rubber or hard rubber, fabric and gas.
  17. 17. System (1) according to one of claims 15 to 17, characterized in that the rubber layer (9), in particular the printing blanket, has a tensioning aid (13), in particular in the form of two metal strips.
  18. 18. System (1) according to one of the preceding claims, characterized in that the amount of the maximum number of revolutions of the transfer roller (2) of a point arranged on the outer surface of the roller is in the range from 500 revolutions/h to 30,000 revolutions/h, preferably from 5,000 revolutions/h to 24,000 revolutions/h, more preferably from 15,000 revolutions/h to 18,000 revolutions/h, in particular with respect to the center of the roller.
  19. 19. System (1) according to one of the preceding claims, characterized in that the carrier layer (12) consists of a component selected from the group consisting of PFP, polyethylene, polypropylene, polyvinyl chloride, polycarbonate, polybutylene terephthalate, polylactide, cellulose diacetate, cellulose triacetate, BO-PET, starch blends, polystyrene, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer, cellophane, polymethyl methacrylate, or copolymers and/or blends thereof.
  20. 20. System (1) according to one of the preceding claims, characterized in that the carrier layer (12) has a layer thickness in the range from 4 pm to 5000 pm, preferably from 6 pm to 250 pm, more preferably from 9 pm to 23 pm.

Description

LEONHARD KURZ Stiftung & Co. KG, Schwabacher Str. 482, 90763 Fürth System for application, method for producing a transfer roller and application method The invention relates to a system for application, a method for producing a transfer roller and an application method. It is known to arrange transfer foils at least partially on a substrate by application processes in which the substrate and transfer foil are pressed together between two rollers in the roller gap. When using transfer foils in application processes with foil timing, it is possible that tree-shaped defects and/or bubble formation can occur on the surface of the decorated substrate or the applied transfer layer. This relevant error can be explained by the fact that when two different plastic surfaces come into contact and rub against each other, for example the outer surface of a transfer roller and the back of the transfer film, which have different Fermi levels, these two surfaces become charged. During the application step, an electrostatic charge is generated that is induced by friction between the outer surface of the roller and the back of the transfer film. This electrostatic charge can be understood as a potential difference between the two surfaces. This rubbing leads to an electrostatic charge and an electrical potential difference between the two surfaces after they are separated from each other. This leads to an uncontrolled charging and the potential difference is measurable as an electrical voltage. The surface with the lower Fermi level represents the electron donor and the surface with the higher Fermi level represents the electron acceptor. The outer surface of the roller and the back of the transfer film are thus charged after the contacting, rubbing and spacing steps. The potential difference increases over the course of the process. After a sufficiently high potential difference, an uncontrolled discharge finally takes place, which can lead to the error pattern described above in the application process, in particular the application step of the process. The risk of inducing a potential difference is increased, particularly with transfer rollers with soft outer roller surfaces, since the contact area between the surfaces is larger. There is therefore a need to avoid the error described above in a clocked application process. It is now the object of the invention to provide a system that enables a timed application process in which the error pattern described above is avoided. Furthermore, it is the object of the invention to provide a method for producing an improved transfer roller and an improved application process. The object is achieved by a system for a timed application process of a transfer layer to a substrate, in particular by a system according to one of claims 1 to 21, comprising a transfer roller and a counter-pressure roller, and a transfer film, wherein the transfer roller has an outer roller surface and the transfer roller and the Counterpressure roller forming a roller gap, wherein the transfer film has a carrier layer and a transfer layer that can be detached from the carrier layer, and the back of the transfer film is formed by the carrier layer and the front of the transfer film is formed by the transfer layer, wherein the back of the transfer film is in contact with the outer surface of the transfer roller and the front of the transfer film is in contact with the substrate in the roller gap, wherein the transfer layer is applied to the substrate at least in some areas, wherein the system is designed in such a way that it is avoided that the friction between the outer surface of the roller and the back of the transfer film during the application process creates a potential difference that is greater than the breakdown voltage of the transfer film, the outer surface of the transfer roller and/or the surrounding gas phase. Furthermore, the object is achieved by a method for producing a transfer roller with an outer roller surface according to one of claims 1 to 21, preferably by a method for producing a transfer roller according to claims 22 to 43, the method comprising the following steps, in particular in the order a), b), c), d) or a), c), b), d): a) providing a transfer roller, b) arranging a rubber layer on the transfer roller, c) arranging a functional layer on the rubber layer, d) obtaining a transfer roller, wherein the functional layer forms the outer roller surface of the transfer roller. The object is further achieved by a method, in particular by a method according to one of claims 44 to 47, for the synchronized application of a transfer layer to a substrate, in particular by means of a system according to one of claims 1 to 21, wherein a transfer roller with an outer roller surface and a counter-pressure roller form a roller gap, wherein the transfer film, which has a carrier layer and a carrier layer removable transfer layer is fed along the transfer roller into the roller gap, wherein th