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EP-3950372-B1 - OPTICAL ANTI-COUNTERFEITING ELEMENT AND CORRESPONDING MANUFACTURING METHODS

EP3950372B1EP 3950372 B1EP3950372 B1EP 3950372B1EP-3950372-B1

Inventors

  • HU, CHUNHUA
  • ZHU, JUN
  • ZHANG, WEIWEI
  • SUN, KAI

Dates

Publication Date
20260506
Application Date
20200327

Claims (14)

  1. An optical anti-counterfeiting element, wherein the optical anti-counterfeiting element comprises: an undulating structure layer (2) provided with a first area (A), a second area (B) and a third area (C); wherein the first area (A) has a first microstructure; the second area (B) has a second microstructure; the third area (C) is an unstructured flat area; a specific volume of the second microstructure is greater than a specific volume of the first microstructure; the first area (A) and the third area (C) are respectively provided with a reflecting layer (31), a dielectric layer (32) and an absorbing layer (33) which are overlapped, and the second area (B) is not provided with the reflecting layer (31); and a surface morphology of one side, far away from the undulating structure layer (2), of the dielectric layer (32) of the first area (A) is significantly different from a surface morphology of the undulating structure layer (2); characterized in that the first microstructure is one of a periodic structure or an aperiodic structure, or a combination of the periodic structure or the aperiodic structure; and a cross section structure of the first microstructure along an extension direction is one of a sinusoidal structure, a rectangular grating structure, a half round structure and a blazed grating structure, or a structure formed by combining at least any two of the sinusoidal structure, the rectangular grating structure, the half round structure and the blazed grating structure.
  2. The optical anti-counterfeiting element as claimed in claim 1, wherein a range of the specific volume of the first microstructure is greater than 0.05 µm 3 /µm 2 and smaller than 0.5 µm 3 /µm 2 .
  3. The optical anti-counterfeiting element as claimed in claim 2, wherein the range of the specific volume of the first microstructure is greater than 0.1 µm 3 /µm 2 and smaller than 0.3 µm 3 /µm 2 .
  4. The optical anti-counterfeiting element as claimed in claim 1, wherein the second microstructure is one of a periodic structure and an aperiodic structure, or a combination of the periodic structure and the aperiodic structure; and a cross section structure of the second microstructure along an extension direction is one of a sinusoidal structure, a rectangular grating structure, a half round structure, a trapezoidal structure and a blazed grating structure, or a structure formed by combining at least any two of the sinusoidal structure, the rectangular grating structure, the half round structure, the trapezoidal structure and the blazed grating structure.
  5. The optical anti-counterfeiting element as claimed in claim 1, wherein a range of the specific volume of the second microstructure is greater than 0.1 µm 3 /µm 2 and smaller than 1 µm 3 /µm 2 .
  6. The optical anti-counterfeiting element as claimed in claim 5, wherein the range of the specific volume of the second microstructure is greater than 0.2 µm 3 /µm 2 and smaller than 0.5 µm 3 /µm 2 .
  7. The optical anti-counterfeiting element as claimed in claim 1, wherein a material of the reflecting layer (31) comprises one of aluminum, silver, copper, tin, chromium, nickel and titanium, or an alloy formed by combining at least any two of aluminum, silver, copper, tin, chromium, nickel and titanium; the dielectric layer (32) is formed through printing; a main resin of the dielectric layer (32) comprises one of polyurethane, acrylic acid and polyester, or a polymer formed by combining at least any two of polyurethane, acrylic acid and polyester; and the material of the absorbing layer (33) comprises one of nickel, chromium, aluminum, silver, copper, tin and titanium, or an alloy formed by combining at least any two of nickel, chromium, aluminum, silver, copper, tin and titanium.
  8. The optical anti-counterfeiting element as claimed in claim 1, wherein the reflecting layer (31) is adjacent to the undulating structure layer (2), the second area (B) is not provided with a dielectric layer (32) and an absorbing layer (33).
  9. The optical anti-counterfeiting element as claimed in claim 1, wherein the absorbing layer (33) is adjacent to the undulating structure layer (2).
  10. The optical anti-counterfeiting element as claimed in claim 1, wherein the second area (B) is provided with the dielectric layer (32) and the absorbing layer (33).
  11. A manufacturing method of an optical anti-counterfeiting element, the optical anti-counterfeiting element as claimed in any one of claims 1 to 8, the manufacturing method comprising: S1), forming an undulating structure layer (2), wherein the undulating structure layer (2) comprises a first area (A), a second area (B) and a third area (C), the first area (A) has a first microstructure, the second area (B) has a second microstructure, a specific volume of the second microstructure is greater than a specific volume of the first microstructure, and characterized in that the third area (C) is an unstructured flat area; S2), sequentially forming a reflecting layer (31), a dielectric layer (32) and an absorbing layer (33) on the undulating structure layer (2), wherein the reflecting layer (31) is formed through vapor deposition, the dielectric layer (32) is formed through printing, and the absorbing layer (33) is formed through vapor deposition; and S3), putting the semi-finished product in S2) in a corrosive atmosphere capable of reacting with a material of the reflecting layer (31) until the reflecting layer (31) of the second area (B) is completely or partially removed, wherein S3) further comprises the following sub-step, in the process that the reflecting layer (31) of the second area (B) is completely or partially removed: completely or partially removing the dielectric layer (32) and the absorbing layer (33) of the second area (B).
  12. A manufacturing method of an optical anti-counterfeiting element, the optical anti-counterfeiting element as claimed in any one of claims 1 to 7 and 9 and 10, the manufacturing method comprising: S1), forming an undulating structure layer (2), wherein the undulating structure layer (2) comprises a first area (A), a second area (B) and a third area (C), the first area (A) has a first microstructure, the second area (B) has a second microstructure, a specific volume of the second microstructure is greater than a specific volume of the first microstructure, and characterized in that the third area (C) is an unstructured flat area; S2), sequentially forming an absorbing layer (33), a dielectric layer (32) and a reflecting layer (31) on the undulating structure layer (2), wherein the reflecting layer (31) is formed through vapor deposition, the dielectric layer (32) is formed through printing, and the absorbing layer (33) is formed through vapor deposition; S3), after the reflecting layer (31) is formed, applying a printing process in a different thickness mode to form a protection layer (5), and the different thickness mode is that the minimum thickness of the protection layer (5) of the first area (A) is significantly greater than the minimum thickness of the protection layer (5) of the second area (B); and S4), putting the semi-finished product in S3) in a corrosive atmosphere capable of reacting with a material of the reflecting layer (31) for permeability improvement until the reflecting layer (31) of the second area (B) is completely or partially removed.
  13. The manufacturing method as claimed in claim 12, wherein S4) further comprises the following sub-step, in the process that the reflecting layer (31) of the second area (B) is completely or partially removed: removing the reflecting layer (31) of the second area (B), and removing neither the dielectric layer (32) nor the absorbing layer (33).
  14. The manufacturing method as claimed in any of claim 11-13, further comprising: continuously applying an inorganic or organic plating layer, or continuously applying a coating layer, so that other optical anti-counterfeiting functions or auxiliary functions are realized.

Description

Technical Field The present invention relates to the field of optical anti-counterfeiting technology, in particular to an optical anti-counterfeiting element and manufacturing methods of the optical anti-counterfeiting element. Background In order to prevent counterfeiting generated by means of scanning, copying and the like, an optical anti-counterfeiting technology is widely adopted in various high-safety or high-added-value printed matters such as banknotes, credit cards, passports, securities and product packages, and a very good effect is achieved. In various optical anti-counterfeiting technologies, optical effects such as diffraction and non-diffraction formed by a microstructure are widely applied due to good compatibility with image design and obvious dynamic effect. In order to increase the brightness of images, the microstructure optical anti-counterfeiting technology generally adopts a metal reflecting layer, such as aluminum. The optical anti-counterfeiting technology, namely holographic technology, which is the most widely applied to optical films at present is an optical technology developed by utilizing a diffraction effect formed by the microstructure. The holographic technology is adopted for anti-counterfeiting threads of the 5th set of 5-yuan, 10-yuan, 20-yuan, 50-yuan and 100-yuan RMB (1999 edition), and when the RMB face is shaken, a shiny holographic face digital image may be observed. In addition, a multi-layer interference optically variable technology is increasingly paid attention by people due to the fact that the multi-layer interference optically variable technology has a strong optical color-changing effect under different observation viewing angles. The multi-layer interference optically variable technology generally adopts a vapor deposition method to realize evaporation of a reflecting layer, a dielectric layer and an absorbing layer. The reflecting layer, the dielectric layer and the absorbing layer form a basic unit of an interference optically variable plating layer. The material of the reflecting layer is generally thick and high in reflectivity, and the material of the absorbing layer is generally thin and has the feature of being semi-transparent. The dielectric layer is a transparent material, and if the thickness meets a certain condition, light rays may interfere in a Fabry-Perot cavity formed by the reflecting layer and the absorbing layer which are parallel to each other. Observed from one side of the absorbing layer, the interference optically variable plating layer shows different colors at different angles. The multi-layer interference optically variable technology is adopted for security threads of the 5th set of 100-yuan RMB (2015 edition), and magenta color is shown in front view observation and green color is shown in inclined observation. If holography, non-diffraction and other optical microstructure anti-counterfeiting technologies and the multi-layer interference optically variable technology are integrated into the same product, the dynamic effect shown by holography and non-diffraction and the optically variable effect shown by multi-layer plating layer may be effectively exerted, and then the anti-counterfeiting effect may be enhanced to a certain extent. However, if the multi-layer interference plating layer is directly evaporated on the optical microstructure, the optical effect shown by the optical microstructure and the interference optically variable effect are weakened mutually. The patent application CN 200980104829.3 (published as CN101952128A) provides a preparation method of an optical anti-counterfeiting product integrating multi-layer interference optically variable feature and high-brightness reflecting microstructure (including a diffraction microstructure and a non-diffraction microstructure) optical feature through a local printing hollowing process, that is, part of area has the multi-layer interference optically variable feature, part of area has the high-brightness reflecting microstructure optical feature, and other areas have a hollowing effect. However, the precision of a local hollowed-out area in this patent application depends on the precision of printing, which is generally 100 µm or above, so that the application in high-end anti-counterfeiting optical products is limited to a certain extent. Therefore, the manufacturing of an optical anti-counterfeiting element which has mutually independent optical microstructure (such as holography and non-diffraction) anti-counterfeiting feature and multi-layer interference optically variable optical feature, has a hollowed-out area high in precision relative to an image area of the optical microstructure, and even may be used for zero-error positioning is of great significance for researching feature positioning of the optical anti-counterfeiting element. CN106891637A discloses an optical anti-counterfeiting member and a preparation method thereof. The method comprises following steps