Radiation-Curable Adhesive for Laminated Security Documents

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for producing laminated security documents, such as bank cards and credit cards, face challenges in applying decorative layers with high resolution and stability during the laminating process, as they are prone to degradation under heat and pressure, and require additional steps that increase thermal and pressure loading.

Innovation Solution

A method involving a radiation-curable adhesive layer applied selectively to a laminating film and a transfer film, allowing for the precise placement and stabilization of decorative layers, which are then cured and peeled off to create a laminated body with enhanced inter-layer adhesion and protection against environmental influences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If decorative layers are applied to laminating films using conventional methods, then the laminated body achieves visual appeal, but the decorative layers degrade under heat and pressure during the laminating process

Engineering Contradiction:

Improvestability of decorative layerVSAvoiddegradation under heat and pressure

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The radiation-curable adhesive is applied and cured in advance before the laminating process. This preliminary curing creates a stable, crosslinked adhesive layer that is resistant to heat and pressure, preventing degradation of the decorative layer during subsequent laminating operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The adhesive undergoes a chemical parameter change through radiation curing, transforming from a liquid or soft state to a crosslinked, thermally stable network. This parameter change enables the adhesive to withstand the heat and pressure conditions of the laminating process without degrading the decorative layer.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If conventional adhesive methods are used to bond decorative layers, then the bonding process is simple, but additional thermal and pressure loading increases during the laminating process

Engineering Contradiction:

Improvecomplexity of adhesive applicationVSAvoidthermal loading during lamination

Core Design Contradiction:

Device complexityVSTemperature

Solution Approach 1:

The conventional thermal-mechanical bonding process is replaced with radiation curing (UV or electron beam). This substitution eliminates the need for additional heat and pressure during adhesive bonding, as the radiation energy directly initiates polymerization at ambient conditions, thereby reducing thermal loading on the decorative layer.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If decorative layers are fully bonded across the entire surface, then inter-layer adhesion is maximized, but resolution and precision of decorative patterns are reduced

Engineering Contradiction:

Improveinter-layer adhesionVSAvoidresolution of decorative pattern

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The adhesive layer exhibits local quality variations through selective radiation curing. Areas requiring high adhesion are fully cured, while areas requiring high resolution or transparency remain uncured. This local differentiation enables both strong bonding where needed and precise decorative patterns where required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The adhesive application is segmented into cured and uncured regions. The cured segments provide structural adhesion, while the uncured segments preserve decorative details and allow for selective bonding. This segmentation resolves the conflict between overall adhesion strength and local pattern resolution.

Inventive Principle:

Principle #1Segmentation

4Strength

If the adhesive layer is made thicker to ensure complete coverage and bonding, then adhesion is improved, but optical quality and resolution of the laminated body deteriorate

Engineering Contradiction:

Improveadhesion strengthVSAvoidoptical quality

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The adhesive achieves adequate bonding strength not through increased thickness but through parameter change via radiation curing. The crosslinking reaction dramatically increases the adhesive's cohesive and adhesive strength, allowing thin layers to provide sufficient bonding while maintaining optical clarity and resolution.

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 method enables the production of laminated bodies with improved optical quality and resistance to forgery attempts by stabilizing decorative layers and maintaining low thermal and pressure loads during the laminating process, while allowing for high-resolution and secure bonding between layers.

Implementation Method 1

printing a radiation-curable adhesive on the first surface of the first laminating film and/or the first surface of the decorative ply... at least partially curing the radiation-curable adhesive layer

Methodology Applied

Scientific EffectRadiation-curable adhesive curing: Photopolymerisation

Data Source

PatentUS11780257B2Method for producing a laminated body and a laminating film and laminated body and laminating film

Publication Date: 2023.10.10 OVD KINEGRAM AG

AI summary

A method for producing a laminated body and a laminating inlay, as well as a laminated body, a laminating inlay and a security document, in particular in the form of a bank card, identity card or credit card, with such a laminated body.