Oriented Plastic Support Adhesion Primer for Liquid Crystal Security Elements

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Solution Overview

Problem

Current methods for incorporating liquid crystals into security elements for secure documents are complex, costly, and limit artistic and security enhancements, with issues related to adhesion and layout flexibility, as well as increased material loss and manufacturing complexity.

Innovation Solution

A method involving an oriented plastic support with a primary adhesion layer applied before or after stretching, allowing for improved adhesion and deposition of liquid crystals by printing, which enhances optical effects and reduces material waste, using a polyacrylic adhesion primer and cholesteric liquid crystals, and optionally a dark background for increased visibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid crystals are applied by transfer process, then adhesion is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:
ImproveadhesionVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

An adhesion promoter layer is applied to the substrate before the liquid crystal layer is deposited. This preliminary action ensures proper adhesion of the liquid crystals to the substrate, eliminating the need for complex transfer processes while maintaining reliable bonding between layers.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If liquid crystals are placed in demetallized areas, then security is reinforced, but material cost increases and aesthetic quality deteriorates

Engineering Contradiction:
ImprovesecurityVSAvoidmaterial cost
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

Liquid crystals are selectively deposited only in specific areas of the substrate using printing techniques, rather than being applied universally. This allows security features to be concentrated where most needed while reducing overall material consumption and avoiding aesthetic issues in areas where liquid crystals are not required.

Inventive Principle:
Principle #3Local quality

3Reliability

If liquid crystals are applied by transfer process, then adhesion is achieved, but material loss increases

Engineering Contradiction:
ImproveadhesionVSAvoidmaterial loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The adhesion promoter function is extracted from the transfer process itself and implemented as a separate preparatory layer on the substrate. This eliminates the need for transfer operations that generate material loss, while still providing the necessary adhesion promotion for liquid crystal attachment.

Inventive Principle:
Principle #2Taking out (Extraction)

4Manufacturing precision

If liquid crystals are oriented by stretching support after liquid crystal deposition, then orientation is achieved, but adhesion deteriorates

Engineering Contradiction:
ImproveorientationVSAvoidadhesion
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The adhesion promoter layer is applied to the substrate before the liquid crystal layer is deposited and oriented. This preliminary adhesion preparation ensures that the liquid crystals remain properly bonded to the substrate throughout the stretching and orientation processes, preventing adhesion deterioration that would occur if orientation were performed first.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method improves adhesion and aesthetic possibilities for liquid crystals on security elements, providing richer optical effects without increasing costs, while maintaining transparency and enhancing the visibility of goniochromatic effects over a wider angular range.

Implementation Method 1

a primary adhesion being deposited before or after stretching the support at least in one direction

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

said stretching making it possible to bring the support to the oriented state

Methodology Applied
Scientific EffectMechanical deformation: Deformation

Implementation Method 3

the liquid crystals being deposited by printing on this adhesion primer

Methodology Applied
Scientific EffectPrinting deposition: Deposition (physical)

Implementation Method 4

Liquid crystals, particularly cholesteric ones, are widely used in security elements for their goniochromatic properties

Methodology Applied
Scientific EffectGoniochromatic effect: Cholesteric Liquid Crystal

Data Source

PatentEP3523136B1Method for producing a security element
Publication Date: 2020.09.30 OBERTHUR FIDUCIAIRE SAS
  • EP3523136B1 patent drawingFigure 1~6
  • EP3523136B1 patent drawingFigure 7~9

AI summary

The invention relates to a method for producing a security element comprising a support made from oriented plastic and at least one layer of liquid crystals borne and oriented by the support, an adhesion primer being deposited before or after the support is stretched in at least one direction, said stretching bringing the support to the oriented state and the liquid crystals being deposited by means of printing on the adhesion primer.