Thin Adhesive Layer Bonding for Flexible Substrates

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Solution Overview

Problem

Existing methods for adhesively bonding flexible substrates often require excessive adhesive, leading to issues like delamination, cracks, and visible shortcomings, as they struggle to achieve full-coverage bonding while maintaining flexibility and avoiding thick adhesive layers.

Innovation Solution

A method involving the application of an adhesive at a coating weight of less than 2 g/m² on one substrate, followed by heating the second thermoplastic substrate to a softened state and immediate pressure bonding, ensuring rapid and full-coverage adhesive bonding with minimal adhesive usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thick adhesive layer is used to ensure full-coverage bonding, then bonding reliability is improved, but flexibility is worsened and visual properties deteriorate

Engineering Contradiction:
Improvebonding reliabilityVSAvoidflexibility
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the physical-chemical parameters of the adhesive system by using reactive adhesives with specific molecular structures that achieve high bond strength at minimal thickness. The adhesive formulation parameters (composition, reactivity, viscosity) are optimized to enable effective bonding with layers less than 2 g/m², resolving the contradiction between reliability and flexibility.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs extremely thin adhesive films (less than 2 g/m²) that maintain flexibility while providing sufficient bonding. The thin film structure itself becomes the solution, where the adhesive layer is so thin it behaves more like a flexible membrane than a traditional thick adhesive layer, simultaneously achieving reliability and flexibility.

Inventive Principle:
Principle #30Flexible shells and thin films

2Reliability

If adhesive is applied in large quantities to cover rough surfaces, then full-coverage bonding is improved, but adhesive usage increases and flexibility is reduced

Engineering Contradiction:
Improvefull-coverage bondingVSAvoidadhesive usage
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies preliminary thermal activation to the thermoplastic substrate before adhesive bonding. By heating the thermoplastic surface to its softening temperature range, the surface becomes more receptive to adhesive bonding, allowing effective full-coverage bonding with significantly reduced adhesive quantities. The preliminary heating action prepares the surface to maximize adhesive efficiency.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the temperature parameter of the thermoplastic substrate to enhance adhesive bonding efficiency. By controlling the substrate temperature within its softening range, the bonding process achieves full coverage with minimal adhesive, transforming the thermal state of the substrate to optimize bonding conditions and reduce material consumption.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If thermoplastic substrates are heated to softened state for bonding, then bonding speed is improved, but energy consumption increases

Engineering Contradiction:
Improvebonding speedVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies heating locally and selectively to the bonding zones of the thermoplastic substrates rather than heating entire substrates or using continuous high-energy heating. This localized thermal activation concentrates energy only where needed for bonding, improving bonding speed while minimizing overall energy consumption through spatial selectivity.

Inventive Principle:
Principle #3Local quality

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 achieves strong, flexible composite substrates with a thin adhesive layer, preventing delamination and maintaining visual properties, while minimizing stress on the substrates and reducing adhesive usage, resulting in high-strength, stable, and visually appealing bonded substrates.

Implementation Method 1

heating the second substrate to a softened state

Methodology Applied
Scientific EffectThermal softening: Heating

Implementation Method 2

adhesively bonding flexible substrates

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10934458B2Adhesion method using thin adhesive layers
Publication Date: 2021.03.02 HENKEL KGAA

AI summary

The invention relates to a method for adhering flexible substrates, the connecting adhesive layer being formed in a thin manner. The invention further relates to a composite substrate, wherein the two substrates are connected by a thin flexible adhesive layer.