Alternating Carboxyl-Nitrogen PSA Layers for Thick Adhesive Clarity
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Solution Overview
Problem
There is a challenge in producing thick pressure sensitive adhesive (PSA) assemblies with an overall caliper of at least 2000 µm using conventional manufacturing methods, as existing techniques often require complex and costly pretreatment processes, which can hinder the production of clear PSA assemblies with desired adhesion characteristics.
Innovation Solution
A multilayer pressure sensitive adhesive assembly is created by superimposing a plurality of PSA layers, where the first layer comprises a polymeric material derived from a carboxyl group-containing (co)polymerizable material and the second layer comprises a nitrogen-containing (co)polymerizable material, arranged in a strictly alternating series, allowing for high peel forces and shear resistance without the need for primer compositions or surface pretreatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional manufacturing methods (hotmelt- or solvent-based techniques) are used to produce thick PSA assemblies, then production complexity is reduced, but the adhesion characteristics and clarity of the PSA assembly deteriorate
Solution Approach 1:
The PSA assembly is divided into multiple discrete layers (first PSA layer, intermediate layer, second PSA layer) with distinct functions. The first and second PSA layers provide adhesion, while the intermediate layer provides structural support and optical clarity. This segmentation allows each layer to be optimized independently for its specific function, achieving both good adhesion characteristics and manufacturing feasibility.
Solution Approach 2:
The invention uses a composite structure combining different polymeric materials in specific layers. The first PSA layer uses a polymer with Tg of -50°C to -20°C for initial adhesion, while the second PSA layer uses a polymer with Tg of -40°C to -10°C for enhanced adhesion at elevated temperatures. This composite approach allows the thick assembly to maintain both manufacturability and superior adhesion performance.
2Length of stationary object
If thick PSA assemblies (caliper ≥ 2000 µm) are produced using conventional methods, then adhesive thickness is sufficient for conformability, but manufacturing cost and process complexity increase due to required pretreatment
Solution Approach 1:
The adhesive layers are pre-formed with controlled thickness and properties before final assembly. The first and second PSA layers are manufactured as separate entities with predetermined calipers and polymer compositions, allowing them to be laminated together without requiring complex pretreatment processes. This preliminary preparation simplifies the overall manufacturing while ensuring the thick assembly meets performance requirements.
Solution Approach 2:
The invention controls the glass transition temperature (Tg) parameters of the polymers in different layers to achieve the desired balance between thickness and performance. By selecting polymers with specific Tg ranges for each layer, the assembly achieves adequate conformability at thick dimensions while maintaining manufacturing simplicity and avoiding complex pretreatment requirements.
3Illumination intensity
If clear thick PSA assemblies are produced, then optical transparency is improved, but adhesion performance on various surfaces deteriorates without primer compositions
Solution Approach 1:
Different layers are assigned different optical and adhesive properties tailored to their specific functions. The intermediate layer is designed with high optical clarity for transparency, while the first and second PSA layers are formulated with specific polymer compositions and Tg values to provide superior adhesion performance on various surfaces. This local optimization allows the clear thick assembly to achieve both transparency and strong adhesion without requiring primer compositions.
Solution Approach 2:
The multilayer composite structure combines materials with complementary properties: the intermediate layer provides optical clarity, while the outer PSA layers provide adhesion. This composite approach enables the assembly to be transparent and thick while maintaining excellent adhesion performance across different substrates without needing additional primer layers or compositions.
4Reliability
If multiple PSA layers are laminated to achieve thick assembly, then adhesion characteristics improve, but delamination risk increases
Solution Approach 1:
The invention carefully selects and controls the glass transition temperature (Tg) parameters of the polymers in each layer to ensure compatibility and prevent delamination. The first PSA layer uses a polymer with Tg of -50°C to -20°C, while the second PSA layer uses a polymer with Tg of -40°C to -10°C. These controlled parameter differences create optimal interlayer bonding while maintaining individual layer integrity, preventing delamination even in the thick multilayer assembly.
Solution Approach 2:
The multilayer composite structure is designed with specific material combinations and thickness ratios that enhance interlayer bonding. The intermediate layer acts as a bonding interface between the first and second PSA layers, creating a stable composite structure that resists delamination. This composite design ensures layer stability while maintaining the enhanced adhesion characteristics provided by the multiple PSA layers.
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 multilayer PSA assembly achieves a stable and cost-effective solution with excellent adhesion characteristics, providing high peel forces and shear resistance on various surfaces, including low, medium, and high surface energy substrates, while preventing delamination and polymerization gradients, and can be manufactured using conventional lamination techniques.
Implementation Method 1
a first PSA layer comprising a first polymeric material comprising the reaction product of a first (co)polymerizable material comprising a carboxyl group-containing (co)monomer, and a second PSA layer comprising a second polymeric material comprising the reaction product of a second (co)polymerizable material comprising a nitrogen-containing (co)monomer
Implementation Method 2
providing high peel forces and shear resistance on various surfaces, including low, medium, and high surface energy substrates
Implementation Method 3
The multilayer pressure sensitive adhesive assembly can be manufactured using conventional lamination techniques
Data Source
AI summary
The present disclosure is directed to a multilayer pressure sensitive adhesive (PSA) assembly having an overall calliper of at least 2000 µm and comprising a plurality of superimposed pressure sensitive adhesive (PSA) layers, wherein the PSA assembly comprises at least a first PSA layer comprising a first polymeric material comprising the reaction product of a first (co)polymerizable material comprising a carboxyl group-containing (co)monomer, wherein the PSA assembly further comprises at least a second PSA layer comprising a second polymeric material comprising the reaction product of a second (co)polymerizable material comprising a nitrogen-containing (co)monomer, and wherein the plurality of superimposed PSA layers is arranged such that the first PSA layer(s) and the second PSA layer(s) are adjacently superimposed in a strictly alternating series. The present disclosure is also directed to a method of manufacturing such a multilayer PSA assembly. In a preferred embodiment the carboxyl group-containing (co)monomer is selected from the group consisting of methacrylic acid, acrylic acid, and any combinations, mixtures or salts thereof, and the the nitrogen group-containing (co)monomer is selected from the group consisting of N-vinyl-caprolactam, N-vinyl-2-pyrrolidone, acryloyl morpholine, and N,N-dialkyl acrylamides, and any combinations, mixtures or salts thereof.