Covert Pigment Encapsulation for Identification Document Stability

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Solution Overview

Problem

Identification documents printed with typical covert pigments, such as UV pigments, often fail to perform well under extreme test conditions like surface abrasion, temperature, and humidity, leading to issues like dye migration and instability under UV light exposure, which are critical for compliance with standards like NCITS 322.

Innovation Solution

A covert material comprising a covert pigment encapsulated in a binder, such as cellulose acetate butyrate or polyester, is developed to improve stability, with specific formulations and particle sizes optimized for use in toners and inks to enhance performance under severe service conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If typical covert pigments are used in identification documents, then the documents can be printed with covert information, but the covert pigments fail under extreme test conditions like surface abrasion, temperature, and humidity

Engineering Contradiction:
Improvestability of covert pigmentVSAvoiddye migration and instability under UV light exposure
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary substance (binder or encapsulating material) that mediates between the covert pigment and the environmental stressors. The binder chemically or physically binds the pigment particles, preventing direct interaction with moisture, heat, and abrasion, thereby resolving the contradiction between printability and stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite material system consisting of covert pigment particles embedded in a binder matrix. This composite structure combines the covert optical properties of the pigment with the protective and stabilizing properties of the binder, achieving both functionality and durability under extreme conditions.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If covert pigments are printed directly on substrates, then the printing process is simple, but the pigments show poor performance under NCITS 322 test conditions

Engineering Contradiction:
Improveprinting process simplicityVSAvoidperformance under severe service conditions
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-coating the substrate with a binder layer or pre-encapsulating the pigment particles before printing. This preliminary preparation ensures that when the covert pigment is applied, it is already protected and bonded, maintaining printing simplicity while ensuring subsequent durability under NCITS 322 conditions.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If encapsulated covert pigment particles are used, then stability under heat and humidity improves, but the particle size and formulation must be optimized

Engineering Contradiction:
Improvestability under heat and humidityVSAvoidparticle size optimization
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent systematically varies key parameters including particle size, binder composition, pigment concentration, and encapsulation thickness to optimize performance. By controlling these parameters within specific ranges, the patent achieves both enhanced stability under heat and humidity and compatibility with standard printing processes.

Inventive Principle:
Principle #35Parameter changes

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

The improved covert material demonstrates better stability and performance under NCITS 322-type conditions, including resistance to heat, humidity, and light exposure, ensuring the longevity and authenticity of identification documents.

Implementation Method 1

a binder encapsulating the covert pigment into a particle

Methodology Applied
Scientific EffectEncapsulation:

Implementation Method 2

covert pigments or dyes such as materials that fluoresce under certain types of illumination

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS8002190B2Stability of covert pigments
Publication Date: 2011.08.23 IDEMIA CIVIL IDENTITY NA LLC

AI summary

A covert material for printing onto a printing medium is provided, the covert material comprising a covert pigment and a binder encapsulating the covert pigment into a particle, where the binder comprises at least one of cellulose acetate butyrate (CAB), butyral vinyl acetate, acetyl butyrate, and acetate butyrate. Alternatively, the binder comprises at least one of polyester, polyolefin, acetyl butyrate, acetate butyrate, polystyrene copolymer, and polystyrene-polyvinylpyridine. The covert material can comprise additional components, such as ethyl acetate and/or n-propyl acetate. In one embodiment, the covert pigment comprises about 0.5-5% of the covert material. In one embodiment, the binder comprises about 5-30% of the covert material. In one advantageous embodiment, the covert pigment comprises at least 2% of the covert material and the binder comprises about 20-25% of the covert material. The covert material can further comprise at least one of a colorant, a surface additive, and a magnetic particle. The covert material can be part of a toner or ink. In at least some embodiments, the particle can have many different sizes, including sizes greater than 1 micron, greater than 5 microns, and greater than 20 microns. In one embodiment, the covert printing material is constructed and arranged to be printed using a printer having a predetermined resolution, wherein the particle has a size that is substantially the same as the size of a single pixel or dot printed using the predetermined resolution. The covert material can be constructed and arranged to satisfy a predetermined number of the NCITS 322 tests.