Polyisobutylene Adhesive with Multifunctional Crosslinker for Low Haze
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Solution Overview
Problem
Existing adhesive compositions face challenges in achieving a balance between adhesion, transparency, and mechanical properties, particularly in pressure-sensitive adhesives where crosslinking can lead to increased haze and reduced flexibility.
Innovation Solution
The adhesive composition incorporates a polyisobutylene polymer component combined with up to 30 wt.% of an aliphatic multifunctional component featuring ethylenically unsaturated groups, which ensures compatibility and allows for crosslinking without excessive haze, maintaining transparency and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinking is performed to improve adhesion and mechanical properties, then storage modulus and adhesion are improved, but haze increases and transparency is reduced
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking system by selecting specific multifunctional components with controlled molecular weights and functional group densities. This allows crosslinking to proceed while maintaining optical clarity by preventing excessive haze formation through careful parameter selection of the crosslinking agents.
Solution Approach 2:
The patent creates a composite adhesive system combining polyisobutylene polymer with aliphatic multifunctional components containing ethylenically unsaturated groups. This composite approach enables simultaneous achievement of crosslinked adhesion strength and optical transparency by leveraging the complementary properties of the polymer matrix and the multifunctional crosslinking agents.
2Strength
If crosslinking density is increased to improve mechanical properties, then storage modulus is improved, but flexibility and elongation are reduced
Solution Approach 1:
The patent optimizes the molecular weight parameters of the multifunctional components, specifically selecting components with molecular weights in certain ranges to achieve balanced crosslinking. This parameter control allows the adhesive to develop sufficient storage modulus while retaining flexibility and elongation properties.
Solution Approach 2:
The patent applies partial crosslinking rather than complete crosslinking by controlling the amount and reactivity of multifunctional components. This partial action approach provides enough crosslinking to improve storage modulus while leaving sufficient uncrosslinked polymer chains to maintain flexibility and elongation.
3Illumination intensity
If compatibility of multifunctional component is increased to reduce haze, then transparency is improved, but adhesion and mechanical properties may be reduced
Solution Approach 1:
The patent adjusts the chemical composition parameters of the multifunctional components, including functional group type ((meth)acryl or vinyl ether) and hydrocarbon chain structure, to achieve optimal compatibility with polyisobutylene. This parameter optimization ensures both transparency through reduced haze and adequate adhesion through proper chemical compatibility.
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 achieves a haze of less than 3% in a 20-micron thick crosslinked adhesive, maintaining adequate adhesion and flexibility, while also providing a broad range of desirable characteristics such as improved storage modulus and creep compliance.
Implementation Method 1
crosslinked adhesive composition
Implementation Method 2
at least two ethylenically unsaturated groups selected from (meth)acryl or vinyl ether
Data Source
AI summary
An adhesive composition is described comprising a polyisobutylene polymer component; and up to 30 wt.-% of at least one aliphatic multifunctional component comprising at least two ethylenically unsaturated groups selected from (meth)acryl or vinyl ether. The monomer comprises a hydrocarbon moiety with greater than 12 contiguous carbon atoms. When the hydrocarbon moiety is branched, the hydrocarbon moiety comprises side chains with at least two carbon atoms. The aliphatic multifunctional component is sufficiently compatible such that crosslinked adhesive composition at a thickness of 20 microns has a haze of less than 3%. Also described are adhesive articles.