Adhesive Articles with Cushion and Shell Layers
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Solution Overview
Problem
Pressure-sensitive adhesives face challenges in achieving a balance of properties such as peel adhesion strength, tack, and shear resistance, often requiring trade-offs between these characteristics, especially at varying temperatures and peel rates, which is problematic in applications like automotive and electronics bonding where high temperature resistance and low tack are desired.
Innovation Solution
The development of adhesive articles comprising a flexible backing with a cushion layer and a continuous shell layer, where the cushion layer has an acrylate pressure-sensitive adhesive with a Fox Tg of up to -30°C and a shell layer with a Tg of -20°C to +50°C, providing a unique balance of properties through specific monomeric unit compositions and thickness ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the shear resistance of the adhesive is increased, then the ability to hold loads for extended time is improved, but the tack and peel adhesion strength are reduced
Solution Approach 1:
The adhesive is divided into two distinct layers: a first layer with high shear resistance properties and a second layer with high tack and peel adhesion properties. This segmentation allows each layer to independently provide its specialized function without compromising the other, resolving the contradiction between shear resistance and adhesion strength.
Solution Approach 2:
The invention uses a composite structure combining two different adhesive materials with complementary properties. The first adhesive layer provides shear resistance while the second adhesive layer provides tack and peel adhesion, creating a composite system that achieves both properties simultaneously.
2Force
If the adhesive is optimized for good tack and peel at room temperature, then the bonding performance at moderate conditions is improved, but the peel adhesion strength at low peel rates and high temperature is poor
Solution Approach 1:
Different layers of the adhesive are assigned different functional qualities: the first layer is optimized for shear resistance and high-temperature stability, while the second layer is optimized for tack and peel adhesion at room temperature. This local differentiation of properties allows the adhesive to perform well across multiple conditions.
Solution Approach 2:
The composite adhesive structure combines two adhesives with different temperature-dependent properties. The first adhesive maintains stability at high temperatures while the second adhesive provides optimal performance at room temperature, achieving reliable performance across the full temperature range.
3Temperature
If the adhesive provides high temperature lifting resistance, then the thermal stability is improved, but the tack is reduced
Solution Approach 1:
The adhesive system is segmented into two layers where the first layer contains the high-temperature resistant adhesive and the second layer contains the high-tack adhesive. This segmentation allows the tack function to be provided by the second layer without compromising the thermal stability provided by the first layer.
Solution Approach 2:
The composite adhesive combines a thermally stable adhesive with a high-tack adhesive in separate layers. The first adhesive layer provides temperature stability and lifting resistance, while the second adhesive layer provides the necessary tack, achieving both properties simultaneously.
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
These adhesive articles demonstrate enhanced adhesion performance at room temperature and high temperatures, with improved peel strength and tack, particularly at low peel rates, without the need for foams, enabling thinner constructions and better performance on low-energy surfaces.
Implementation Method 1
a first cushion layer permanently bonded to a first surface of the flexible backing
Data Source
Figure 1~2
AI summary
An adhesive article including: a flexible backing; a first cushion layer permanently bonded to a first surface of the flexible backing, wherein the first cushion layer: has an average thickness of at least 10 micrometers; and includes an acrylate pressure-sensitive adhesive having a Fox Tg of up to -30°C, wherein the acrylate pressure-sensitive adhesive includes a (meth)acrylate copolymer; and a first continuous shell layer adjacent the first cushion layer, wherein: the first continuous shell layer has an average thickness of up to 25 micrometers; the ratio of the first cushion layer average thickness to the first shell layer average thickness is at least 2:1; the first continuous shell layer includes an adhesive having a Fox Tg of -20°C to +50°C; and the first continuous shell layer adhesive includes a copolymer having a weight average molecular weight of at least 100,000 Daltons.