Multi-layer Color Image Articles with Blocking Layers

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Solution Overview

Problem

Existing methods for forming color images in articles are limited in durability and resistance to scratches, stains, and tampering, especially when the images are not on the surface but within internal layers, as they often require protective lamination and can be prone to damage from external factors.

Innovation Solution

Multi-layer articles comprising thermally activatable layers with light-to-heat convertor compositions and color-changing compounds, where the layers have distinct absorption thresholds and are protected by blocking layers, allowing for internal image formation that is resistant to damage and tampering without external lamination, using techniques such as selective light exposure to activate the layers and change their reflective characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If color images are formed on the surface of articles, then image visibility is good, but the images are prone to scratches, stains, and tampering

Engineering Contradiction:
Improveimage durabilityVSAvoidscratch and stain resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent moves the color image formation from the surface (2D) to internal layers (3D depth dimension). Multiple thermally activatable layers are positioned at different depths within the article, with blocking layers strategically placed to prevent external access while allowing optical activation from specific directions, thereby protecting images from surface damage

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If protective lamination is applied to protect internal images, then image protection is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveimage protectionVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates the protective function directly into the multi-layer structure itself. The blocking layers (reflective or absorptive) are incorporated as integral parts of the layer stack, combining image formation and protection functions into a single unified structure, eliminating the need for separate protective lamination layers

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If multiple thermally activatable layers are used for color images, then image quality and durability are improved, but selective activation becomes more difficult

Engineering Contradiction:
Improveimage durabilityVSAvoidselective activation
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent assigns different spectral characteristics to different layers. Each thermally activatable layer contains compounds with specific absorption thresholds, allowing selective activation by controlling the wavelength and intensity of incident light. Blocking layers with specific optical properties further enable precise spatial and spectral control over which layers are activated

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

Blocking layers serve as intermediary elements between the light source and the thermally activatable layers. These blocking layers (reflective or absorptive) mediate the optical energy distribution, preventing unwanted activation of certain layers while allowing activation of others, thereby enabling selective image formation in the multi-layer structure

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution enables the creation of durable, scratch-resistant, and tamper-proof color images within internal layers of articles, maintaining structural integrity and preventing unwanted activation, thus enhancing the longevity and security of the images.

Implementation Method 1

The first light to heat convertor composition absorbs light of a write wavelength and the first activatable layer has a first absorption threshold for activation

Methodology Applied
Scientific EffectLight to heat conversion: Absorption (EM radiation)

Implementation Method 2

The first blocking layer is disposed between the first and second internal thermally activatable layers and is adapted to at least partially block light of the write wavelength

Methodology Applied
Scientific EffectLight blocking: Absorption (EM radiation)

Implementation Method 3

the first thermally activatable layer comprises a first light to heat convertor composition and a first color changing compound

Methodology Applied
Scientific EffectThermal color change: Thermochromism

Data Source

PatentEP2588317B1Multi-layer articles capable of forming color images and methods of forming color images
Publication Date: 2020.03.18 3M INNOVATIVE PROPERTIES CO
  • EP2588317B1 patent drawingFigure 1~4
  • EP2588317B1 patent drawingFigure 5~6
  • EP2588317B1 patent drawing

AI summary

Multi-layer articles are described that are capable of forming color images. The articles may contain at least two layers, a thermally activatable layer and a blocking layer, or at least three layers with two thermally activatable layers and a blocking layer between. The thermally activatable layers absorb light of a write wavelength and have an absorption threshold for activation. The blocking layer blocks light of the write wavelength at certain incident angles or polarization states and permits light of the write wavelength and certain incident angles or polarization states to pass through. The thermally activatable layers may be layers with a light to heat convertor composition and a color changing compound or they may be a group of layers arranged to change its reflective characteristic upon exposure to light while maintaining the structural integrity of the group of layers