Selective Plasma Pretreatment for Adhesive Bonding

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Solution Overview

Problem

Existing methods for bonding adhesive layers to surfaces often result in uniform cohesive failure, which limits the maximum achievable separation force, and there is a need for techniques that can enhance separation forces beyond what is possible with homogeneous surface pretreatment.

Innovation Solution

A method involving partial and structured pretreatment of one or both surfaces with techniques like plasma or primer application, creating inhomogeneous patterns that increase the fracture surface area when the bond is broken, thereby enhancing separation forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If homogeneous surface pretreatment is applied across the entire bonding surface, then consistent bonding is achieved, but the separation force is limited by uniform cohesive failure

Engineering Contradiction:
Improvebond consistencyVSAvoidseparation force
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The patent applies local quality by creating distinct zones on the bonding surface: pretreated areas that promote cohesive failure with high separation forces, and untreated areas that promote adhesive failure. This spatial variation in surface properties allows different failure modes in different locations, ultimately increasing the overall separation force when the bond is opened.

Inventive Principle:
Principle #3Local quality

2Strength

If partial pretreatment is applied to create inhomogeneous structure, then the fracture surface area increases and separation force increases, but the bonding process becomes more complex

Engineering Contradiction:
Improveseparation forceVSAvoidpretreatment process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent segments the bonding surface into pretreated and untreated areas, creating a structured inhomogeneity that controls failure modes. This segmentation allows the bond to fail in different ways across different zones, enlarging the effective fracture surface area and increasing separation forces without requiring complex multi-step processes.

Inventive Principle:
Principle #1Segmentation

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 achieves higher separation forces by creating an enlarged fracture surface, with the bond breaking cohesively over pretreated areas and adhesively over untreated areas, resulting in a greater force required to separate the adhesive from the surface compared to uniform failure.

Implementation Method 1

the first adhesive layer surface and/or the first component surface are partially pretreated over a specific area

Methodology Applied
Scientific EffectPlasma: Plasma

Implementation Method 2

Over the pretreated areas of the bonding surface, the bond preferably fails cohesively, i.e., it fails along the adhesive layer because the separation forces between the first adhesive layer surface and the first component surface are increased

Methodology Applied
Scientific EffectSurface activation:

Data Source

PatentEP3423538B1Increasing the pull-off force by selective plasma pretreatment
Publication Date: 2023.06.21 TESA SE
  • EP3423538B1 patent drawingFigure 1a~1b
  • EP3423538B1 patent drawingFigure 2~3
  • EP3423538B1 patent drawingFigure 4a~4b

AI summary

The invention relates to a method for adhesively bonding an adhesive mass layer (3) to a first joint part (4) in that a first surface (3a) of the adhesive mass layer (3) is applied to a first joint-part surface (4a) and the first surface (3a) of the adhesive mass layer (3) and/or the first joint-part surface (4a) is pretreated over part of the area thereof and a separating force in the pretreated regions (6) between the first joint-part surface (4a) and the first surface (3a) of the adhesive mass layer (3) is thereby increased and, when the adhesive mass layer (3) is pulled off of the first joint-part surface (4a), the adhesive mass layer (3) cohesively separates in the pretreated regions (6) and the first surface (3a) of the adhesive mass layer (3) adhesively separates from the first joint-part surface (4a) in untreated regions (7).