Security Film Patch Laminate for Durable Window Sealing

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Solution Overview

Problem

Existing hot stamping foil technologies for security patches in banknotes and valuable documents are inadequate in terms of durability, crease resistance, abrasion resistance, and adhesion, particularly when applied over windows or transparent areas, and often result in delamination and residue issues.

Innovation Solution

A method involving electrostatic charging or corona treatment to bond a first plastic film to a carrier substrate, applying optically/machine-readable security features, a protective layer, and a heat-activated adhesive to produce foil patches that can be easily die-cut and applied to documents, ensuring stability and residue-free removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hot stamping foil technology is used for foil patches, then the patches can be applied to security documents, but the durability, crease resistance, and abrasion resistance are insufficient

Engineering Contradiction:
ImprovedurabilityVSAvoidcrease resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent employs a composite structure consisting of a carrier substrate, a plastic film layer, and a security feature layer. This multi-layer composite construction provides enhanced durability, crease resistance, and abrasion resistance compared to traditional hot stamping foils, while maintaining the ability to be applied to security documents.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent uses a flexible plastic film (such as PET or PP) as the carrier substrate, which provides the necessary mechanical strength and flexibility. This thin film structure ensures the foil patch can withstand circulation conditions including creasing and abrasion while remaining adaptable to the document surface.

Inventive Principle:
Principle #30Flexible shells and thin films

2Strength

If permanently adhesive adhesives are used for bonding foil patches to document substrate, then the bond is firm, but release agents are needed for removal from carrier tape which negatively impacts adhesion and printing ink adhesion

Engineering Contradiction:
Improvebond strengthVSAvoidadhesion impairment
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the adhesive function from the carrier substrate system by applying adhesive only to the foil patch itself, not to the carrier tape. This allows the foil patch to be firmly bonded to the document substrate while eliminating the need for release agents on the carrier tape, thus avoiding adhesion impairment and printing ink adhesion issues.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The adhesive is applied locally only to the areas where bonding is required (the foil patch surface), rather than uniformly across the entire carrier substrate. This localized adhesive application ensures strong bonding to the document while maintaining compatibility with printing processes.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If coextruded film is used with one layer as carrier substrate and another as security feature layer, then both layers are prone to delamination

Engineering Contradiction:
Improvefilm integrationVSAvoidlayer adhesion
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent segments the structure into distinct functional layers: a carrier substrate (web-shaped substrate), a plastic film layer, and a security feature layer. These separate layers are bonded through controlled adhesion mechanisms, preventing the delamination issues that occur in coextruded films where layers are inherently unstable together.

Inventive Principle:
Principle #1Segmentation

4Ease of operation

If UV embossed varnish layer is used as release layer, then the carrier substrate can be detached, but the optically effective layer is unprotected against external influences

Engineering Contradiction:
Improvecarrier removalVSAvoidexternal influence exposure
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent adds a protective dimension by placing a protective layer over the optically effective security feature layer. This creates a multi-dimensional protection system where the carrier substrate can still be removed for application, but the security features are protected from external influences during circulation and use.

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

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 enhances durability and counterfeit protection by integrating secure, optically variable security features that can seal windows in documents, improving circulation suitability and ease of application on existing equipment.

Implementation Method 1

a first, web-shaped plastic film is applied to a web-shaped carrier substrate, wherein the first plastic film is bonded to the carrier substrate by means of prior electrostatic charging

Methodology Applied
Scientific EffectElectrostatic charging: Electrostatics

Implementation Method 2

a first, web-shaped plastic film is applied to a web-shaped carrier substrate, wherein the first plastic film is bonded to the carrier substrate by means of prior corona treatment

Methodology Applied
Scientific EffectCorona treatment: Corona Discharge

Implementation Method 3

a releaseable coating containing a UV-crosslinking release layer

Methodology Applied
Scientific EffectUV-crosslinking: Photopolymerisation

Data Source

PatentEP4681935A1Sheet material for security elements in the form of film patches
Publication Date: 2026.01.21 HUECK FOLIEN GMBH & CO KG
  • EP4681935A1 patent drawingFigure 1~2
  • EP4681935A1 patent drawingFigure 3~4
  • EP4681935A1 patent drawingFigure 5~6

AI summary

Method for producing film material for security elements in the form of film patches (4), comprising the following steps to be carried out in the order mentioned: - Applying a first plastic film (1), which is web-shaped, to a web-shaped carrier substrate (3), wherein the first plastic film (1) is bonded to the carrier substrate (3) by means of prior electrostatic charging, prior corona treatment or by means of a release coating containing a UV-crosslinking release layer (5), - Applying at least one security feature (7), which is optically detectable and/or machine-readable, to the first plastic film (1), - Applying a second plastic film (2), which is web-shaped, or a protective lacquer layer (9) to the at least one security feature (7), - Applying an adhesive layer (10), in particular heat-activated, to the second plastic film (2) or to the protective lacquer layer (9).