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Polymer-based optically variable devices

A polymer and device technology, used in optical components, instruments, thin material processing, etc., can solve problems such as random changes in color

Active Publication Date: 2014-03-05
SIGMA LAB OF ARIZONA LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Despite repeated experiments to produce structures with spacer liners of precise uniform thickness by vapor deposition, the random variation in color remains an unresolved problem in the prior art

Method used

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  • Polymer-based optically variable devices
  • Polymer-based optically variable devices
  • Polymer-based optically variable devices

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] Example 1. This example demonstrates that substrates with significant levels of microroughness, when leveled with a leveling layer, can produce OVDs without significant color change. Optically variable devices were formed on a 1-mil (ie, 1 / 1000th of an inch) thick, 60-inch wide PET film substrate with a haze of 5% or greater and a gloss of 90% or less. PET film was first coated at a speed of 2.5 m / s with a 0.6 micron thick layer of leveling polymer obtained by depositing propoxylated (2) neopentyl glycol diacrylate on the PE film The monomer is then cured with an electron beam curtain to form. A layer of aluminum was then deposited across the PET mesh on a leveling layer with a uniform optical density of 0.35 and a uniform emissivity of 0.5. A thin layer of aluminum is then coated with a spacer liner composed of the same polymer as the leveling layer at a web speed of 0.6 m / s to 1.2 m / s. The spacer liner is then coated with a relatively opaque layer of aluminum. Exa...

Embodiment 2

[0043] Example 2. The conditions of Example 2 were repeated, except that a layer of chromium was coated with a uniform optical density of 0.4 across the width of the film, and an emissivity of 0.65 with a variation of less than + / - 0.06 across a width of 30" 30" wide, 2-mil thick PET film with less than 1% haze and >95% gloss. At constant velocity, PET maintained at room temperature and moving at a speed of 0.6m / s-1.2m / s A monomer formulation consisting of 5% beta carboxyethyl acrylate, 45% Zonyl TM / TA-N, 5% hexanediol diacrylate and 45% tripropylene glycol diacrylate was flashed on the web. An electron beam curtain close to the monomer deposition station polymerizes the monomer layer so that the time between deposition and curing is less than 2 seconds. By depositing a polymer layer followed by an opaque aluminum layer, a series of OVD devices were produced and showed The following color shifts:

[0044] dark blue with little or no transfer;

[0045] Light green transfers ...

Embodiment 3

[0054] Example 3. Optically variable devices were formed on a 12 micron thick PET substrate with less than 1% haze and greater than 95% gloss. A stainless steel layer was deposited on a PET substrate with an average emissivity of 0.66 and an optical density OD=0.5. Across the deposition area, the emissivity varies by less than 0.05. Using, a monomer formulation consisting of 95 parts propoxylated neopentyl glycol diacrylate and 5 parts acidic acrylate oligomer was designed to reduce the heat sensitivity of the monomer and provide metal adhesion. The monomer was condensed on the SS substrate at a web velocity of 5 m / s. The condensed monomer layer was e-beam cured within 2 seconds of deposition and a relatively opaque aluminum layer. Using an optical interferometer with two sensing heads across the polymer mesh, the color is measured and the layer thickness of the polymer is controlled. The thickness of the deposited polymer layer was varied, forming a color shift pattern, a...

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Abstract

A polymer-based optically- variable device for security applications has a high degree of color uniformity over the device area. The uniformity of thickness of the structure used in such devices is optimized by controlling previously neglected process parameters such as the temperature distribution of the deposition nozzle (32), the substrate (10) and the deposition drum (38), their emissivities, the micro-roughness of the substrate, and the rate of monomer re-evaporation. Re-evaporation is minimized by initiating radiation-curing within two seconds of monomer deposition. The equipment is carefully monitored to eliminate all sources of emissivity non-homogeneities, such as surface blemishes in the surface areas exposed to the substrate (10). Substrates with haziness less than 5% and gloss greater than 90% are preferred. As a result, a maximum thickness variation of less than 5% over the transmissive layer (14) of the optically variable device is found to ensure that no appreciable color- shift variation is visible to the naked eye.

Description

technical field [0001] The present invention relates generally to optically variable devices (OVDs), and in particular to vacuum deposited polymer-based multilayer OVD structures. Background technique [0002] Optically variable devices have become ever more popular as a tool for providing cryptographic security against counterfeiting, counterfeiting and / or converting documents and products. Matching the appropriate cryptographic security features to their intended function, methods of determining the authenticity of the cryptographic security features, and introducing effective anti-counterfeiting protection to the OVD itself are all faced in the process of designing and implementing OVDs for specific cryptographic security applications important question. OVDs can be used as stand-alone features or can be combined with more conventional printed note varieties, resulting in devices that are extremely difficult to reproduce using photocopying or scanning techniques. [000...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G03H1/00
CPCB29D11/0074Y10T428/24942
Inventor A·雅利兹G·古德伊尔
Owner SIGMA LAB OF ARIZONA LLC
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