Copolymer with Pendent UV Absorbing Group for PSA
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Solution Overview
Problem
Conventional ultraviolet absorbers (UVAs) in pressure-sensitive adhesives (PSAs) face issues with migration and agglomeration, leading to optical defects and reduced compatibility, which affects their protective efficacy against ultraviolet light.
Innovation Solution
Development of copolymers with a first divalent unit having a pendent ultraviolet absorbing group, a second divalent unit with a pendent alkyl group, and a third divalent unit with a pendent tertiary amine, which are surprisingly compatible with PSAs, preventing migration and maintaining transparency and UV protection even under accelerated exposure and harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ultraviolet absorbers (UVAs) are dispersed into pressure-sensitive adhesives (PSAs), then UV protection is provided, but the UVAs can be lost due to volatilization or migration to the surface
Solution Approach 1:
The patent combines the UVA functionality with the PSA polymer structure by incorporating ultraviolet-absorbing groups directly into the copolymer backbone. This merging of the UVA and PSA into a single integrated molecule eliminates the interface between separate components, preventing migration and volatilization while maintaining UV protection.
Solution Approach 2:
The invention creates a composite copolymer structure that integrates multiple functional units: a first divalent unit with ultraviolet-absorbing groups, a second divalent unit providing adhesive properties, and a third divalent unit enhancing compatibility. This composite structure at the molecular level ensures the UVA remains embedded within the PSA matrix.
2Reliability
If UVAs are incorporated into PSAs, then UV protection is achieved, but optical defects occur due to agglomeration
Solution Approach 1:
The patent distributes ultraviolet-absorbing groups locally throughout the copolymer chain rather than concentrating them in discrete aggregates. Each repeating unit contains integrated UVA functionality, ensuring uniform local protection without the formation of large agglomerates that cause optical defects.
Solution Approach 2:
The copolymer combines three different divalent units in specific ratios to create a homogeneous composite material at the molecular level. This composite structure prevents phase separation and agglomeration while maintaining both UV absorption and adhesive properties.
3Reliability
If copolymers with ultraviolet-absorbing groups are used, then UV protection and compatibility are improved, but the copolymer structure becomes more complex
Solution Approach 1:
The patent segments the copolymer into three distinct but simple divalent unit types, each performing a specific function: UV absorption, adhesion, and compatibility enhancement. This segmentation allows for modular design and simplifies the synthesis process while achieving multiple functions simultaneously.
Solution Approach 2:
The copolymer structure is designed with multi-functionality, where the same three-divalent-unit framework can be adapted to provide UV protection, adhesion, and compatibility across different PSA applications. The universal structure reduces overall system complexity despite the multifunctional requirements.
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 copolymers provide superior compatibility and optical clarity in PSA formulations, effectively protecting against UV light without migrating, ensuring durability and performance in various applications.
Implementation Method 1
a first divalent unit having a pendent ultraviolet absorbing group
Data Source
AI summary
A copolymer that includes first divalent units having a pendent ultraviolet absorbing group, second divalent units represented by formula (I):, and third divalent units represented by formula (II):. Each R1 is independently hydrogen or methyl; R2 is a straight-chain or branched alkyl having from 1 to 20 carbon atoms; V is O or NH; W is alkylene having from 1 to 10 carbon atoms; and each R' is independently alkyl having from 1 to 6 carbon atoms. Compositions including the copolymer, for example, pressure sensitive adhesive compositions are disclosed. Articles including the compositions are disclosed. For example, an assembly including a barrier film and the pressure sensitive adhesive composition is also disclosed.