KR-102964301-B1 - Uses of nanoparticles to tune the refractive index of layers in a polymer matrix to optimize micro-optical (MO) focus

Abstract

The security device comprises one or more arrays of image icons (110a, 110b, 615, 715), one or more arrays of refractive image icon focusing elements (120, 605, 705), and a sealing layer (127, 600, 1005) comprising an organic resin and nanoparticles. Additionally, one or more arrays of refractive image icon focusing elements are placed over one or more arrays of image icons, so that a portion of one or more arrays of refractive image icon focusing elements forms a composite image of a portion of one or more arrays of image icons. Additionally, one or more arrays of refractive image icon focusing elements are in contact with the sealing layer along non-planar boundaries.

Inventors

• 겟텐스, 낸시, 제이.
• 고스넬, 조나단 디.

Assignees

• 크레인 앤 코, 인크

Dates

Publication Date

20260513

Application Date

20200520

Priority Date

20190520

Claims (20)

1. Array of one or more image icons (110a, 110b, 615, 715); One or more arrays of refractive image icon focusing elements (120, 605, 705); and Sealing layer (127, 600, 1005) comprising organic resin and nanoparticles Includes, Here, one or more arrays of the refractive image icon focusing elements are placed on one or more arrays of the image icon, and thus a part of the one or more arrays of the refractive image icon focusing elements forms a composite image of a part of the one or more arrays of the image icon. Here, one or more arrays of the aforementioned refractive image icon focusing elements are in contact with a sealing layer along a non-planar boundary, and A security device comprising nanoparticles included in the sealing layer that are dispersed throughout the sealing layer and affect the geometric structure of the refractive image icon focusing element.
2. A security device according to claim 1, wherein the nanoparticle comprises one or more of aluminum oxide, zirconium dioxide, titanium dioxide, zinc sulfide, or zinc telluride.
3. A security device according to claim 1, wherein the organic resin comprises an acrylate monomer.
4. A security device according to claim 1, wherein the organic resin comprises an acrylate oligomer.
5. A security device according to claim 1, wherein the organic resin comprises one or more of phenoxybenzyl acrylate, o-phenylphenoxyethyl acrylate, phenylthioethyl acrylate, bis-phenylthioethyl acrylate, cumyl phenoxyethyl acrylate, biphenylmethyl acrylate, bisphenol a epoxy acrylate, fluorene-type acrylate, brominated acrylate, halogenated acrylate, or melamine acrylate.
6. A security device according to claim 1, wherein the organic resin comprises one or more of isodecyl acrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyester tetraacrylate, trimethylolpropane triacrylate, or hexanediol diacrylate.
7. A security device according to claim 1, wherein the organic resin does not include a polarizing element.
8. A security device according to claim 1, wherein the sealing layer has a refractive index of 1.5 or higher.
9. A security device according to claim 1, wherein the sealing layer has a refractive index of 1.6 or higher.
10. A security device according to claim 1, wherein one or more arrays of the refractive image icon focusing elements have a diameter greater than 30 micrometers.
11. A security device according to claim 1, further comprising a spacer layer (115, 610, 710, 1015) disposed between an array of refractive image icon focusing elements and an array of image icons, wherein the spacer layer comprises nanoparticles.
12. A security device according to claim 1, further comprising a spacer layer integrated with an array of refractive image icon focusing elements.
13. A security device according to claim 1, further comprising two or more arrays of refractive image icon clustering elements in contact along one or more non-planar boundaries.
14. A security device according to claim 1, wherein the security device has a thickness of 50 micrometers or less.
15. A security device according to claim 1, further comprising a machine-readable security device (Mr-SD) (620, 720).
16. One or more arrays of image icons (110a, 110b, 615, 715); and It comprises a layer of one or more arrays (120, 605, 705) of refractive image icon focusing elements, wherein one or more arrays of refractive image icon focusing elements comprise a mixture of organic resin and nanoparticles, and Here, one or more arrays of the refractive image icon focusing elements are placed on one or more arrays of the image icon, and thus a part of the one or more arrays of the refractive image icon focusing elements forms a composite image of a part of the one or more arrays of the image icon. Here, the mixture of the organic resin and nanoparticles has a refractive index greater than 1.5, and A security device in which the nanoparticles are dispersed throughout the entire layer of one or more arrays of the refractive image icon focusing elements and affect the geometric structure of the refractive image icon focusing elements.
17. A security device according to claim 16, wherein the organic resin has a refractive index of less than 1.5.
18. A security device according to claim 16, wherein the nanoparticle comprises one or more of aluminum oxide, zirconium dioxide, titanium dioxide, zinc sulfide, or zinc telluride.
19. A security device in which the organic resin in Clause 16 comprises an acrylate monomer.
20. A security document (101) including the security device of paragraph 1.

Description

Uses of nanoparticles to tune the refractive index of layers in a polymer matrix to optimize micro-optical (MO) focus Technology field The present disclosure relates to improving the performance of security devices, such as micro-optical strips, attached to or otherwise included in security documents to provide a counterfeit-resistant indicator of authenticity. More specifically, the present disclosure relates to the use of nanoparticles for tuning the refractive index of a polymer matrix (sometimes called "goo") used to form one or more layers of a micro-optical security device to optimize micro-optical ("MO") focus without limitation. background In many cases, the challenge in designing and manufacturing some micro-optical security devices involves resolving the trade-off between realizing the desired characteristics of the final product against the opportunities and constraints imposed by, for example, available manufacturing technologies and physical laws. For example, manufacturers of security documents (e.g., banknotes, checks, and other documents presenting the need for a reliable indicator of truthfulness) desire a micro-optical security device that is thin, durable, forgery-resistant, and visually appealing. At the same time, the properties of the materials used, in combination with the physical laws used to construct the micro-optical security device, can impose constraints on the performance characteristics of the final product. As one non-limiting example, a lens made of a material with a low refractive index will be thicker than a lens of equivalent focal length made of a material with a high refractive index. As another non-limiting example, the interaction between light waves and the constituent material of the lens can cause chromatic aberration, thereby causing the focal length of the lens to vary at different wavelengths of light. In light of the above, tuning the physical properties (e.g., component thickness and refractive index) of a material for manufacturing a micro-optical security device presents untapped opportunities to transcend limitations regarding the realization of a larger set of desirable end-product characteristics (e.g., overall thickness, contamination resistance) within the constraints imposed by the operation of physical laws on the selected material. summation The present disclosure illustrates, without limitation, embodiments of a system and method using nanoparticles to tune the refractive index of a polymer matrix to optimize micro-optical ("MO") focus, as well as embodiments of a micro-optical system using a low RI material in one or more constituent layers of the system. In a first embodiment, the security device comprises one or more arrays of image icons, one or more arrays of refractive image icon focusing elements, and a sealing layer. Furthermore, one or more arrays of refractive image icon focusing elements are positioned over one or more arrays of image icons, so that a portion of one or more arrays of refractive image icon focusing elements projects a composite image of a portion of one or more arrays of image icons. Furthermore, one or more arrays of refractive image icon focusing elements are in contact with the sealing layer along non-planar boundaries. Additionally, at least one of one or more arrays of refractive image icon focusing elements and the sealing layer comprises a mixture of an organic resin and nanoparticles having a first refractive index. In a second embodiment, the security device comprises one or more arrays of image icons and one or more arrays of refractive image icon focusing elements, wherein one or more arrays of refractive image icon focusing elements comprise a mixture of organic resin and nanoparticles. One or more arrays of refractive image icon focusing elements are placed over one or more arrays of image icons, so that a portion of one or more arrays of refractive image icon focusing elements projects a composite image of a portion of one or more arrays of image icons. The mixture of organic resin and nanoparticles has a refractive index greater than 1.5. In a third embodiment, the security document comprises a substrate and a security device. The security device comprises one or more arrays of image icons, one or more arrays of refractive image icon focusing elements, and a sealing layer. Furthermore, one or more arrays of refractive image icon focusing elements are positioned over one or more arrays of image icons, so that a portion of one or more arrays of refractive image icon focusing elements projects a composite image of a portion of one or more arrays of image icons. Furthermore, one or more arrays of refractive image icon focusing elements are in contact with the sealing layer along non-planar boundaries. Additionally, at least one of one or more arrays of refractive image icon focusing elements and the sealing layer comprises a mixture of an organic resin and nanoparticles having a first refractive index. In a fou