Epoxy Copolymer PSA with Bulky Side Chains
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Solution Overview
Problem
Pressure sensitive adhesive (PSA) compositions face challenges in achieving adequate cross-linking without premature viscosity increase, making them difficult to handle during production, transport, and storage, while also requiring high solids content and minimal solvent usage for environmental advantages.
Innovation Solution
A copolymer composition formed by co-polymerization of a first monomer with an epoxy group, a second monomer without an epoxy group, and a third monomer with a bulky side chain, maintaining a specific molar ratio between the epoxy-containing and bulky side-chain monomers, which allows for controlled cross-linking and stability, enabling higher solids content and reduced solvent usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cross-linking is achieved during production, transport or storage, then the final strength of the PSA is improved, but the viscosity increases making it harder or impossible to handle
Solution Approach 1:
The patent incorporates a cross-linkable copolymer with epoxy groups and bulky side chains that remains stable during storage but enables cross-linking at the desired moment through controlled conditions (temperature, catalyst, UV light), allowing the PSA to maintain handleability during production while achieving strength enhancement when needed
Solution Approach 2:
The patent utilizes changes in temperature, pH, or other parameters to trigger cross-linking at the desired moment. The copolymer composition is designed to remain stable under storage conditions but undergoes cross-linking when specific parameters are changed (e.g., temperature increase, catalyst addition), thus resolving the contradiction between maintaining stability and achieving cross-linking
2Productivity
If higher solids content is used to reduce solvent, then environmental advantages are achieved and processing speed increases, but premature cross-linking occurs making the PSA unstable during storage
Solution Approach 1:
The patent creates a composite copolymer system combining monomers with epoxy groups, bulky side chains, and other functional groups. This composite molecular structure provides both high solids content for environmental benefits and controlled cross-linking characteristics, preventing premature cross-linking while enabling fast processing when conditions are right
Solution Approach 2:
The bulky side chains act as spatial intermediaries that prevent premature cross-linking by physically separating epoxy groups, while still allowing cross-linking to occur when triggered by specific conditions. This intermediary structure enables the PSA to maintain stability during storage even at high solids content
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 solution provides a stable PSA with excellent cross-linking properties, increased shelf-life, and environmental benefits, allowing for faster processing and improved handling characteristics by maintaining stability during storage and enabling efficient cross-linking at desired moments.
Implementation Method 1
adequate cross-linking can be achieved because the final strength of the PSA is correlated with its molecular weight
Data Source
AI summary
The present invention relates to a pressure sensitive adhesive composition comprising a copolymer having cross-linkable epoxy groups as well as a solvent. The copolymer is made up of one or more first, second and third monomers, wherein the first monomer possesses an epoxy group and third monomer has a bulky side chain. Surprisingly, the third monomer provides for stability without affecting the ability of the copolymer to form cross-links. The invention also relates to a method of preparing the pressure sensitive adhesive composition and to a method of its use.