Polyester Compositions With Crosslinkable Pendent Groups
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Solution Overview
Problem
Conventional polyester-based pressure-sensitive adhesives exhibit poor shear strength due to inadequate crosslinking, often requiring low molecular weight monomer additives and lacking efficient radical-based addition or propagation reactions.
Innovation Solution
Incorporating crosslinkable pendent groups with reactive unsaturated carbon-carbon bonds, such as alkenes or alkynes, into the polyester structure, allowing for efficient crosslinking via actinic radiation or heat, thereby enhancing adhesive performance without the need for additional monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyester-based pressure-sensitive adhesives are crosslinked using multifunctional isocyanate crosslinker in solution phase, then crosslinking is achieved, but shear strength remains poor
Solution Approach 1:
The patent changes the chemical structure parameter of the polyester by incorporating crosslinkable pendent groups (vinyl, allyl, acrylate, or methacrylate groups) directly into the polyester chains. This structural modification enables the polyester to undergo efficient radical-based crosslinking when exposed to actinic radiation or heat, transforming the crosslinking mechanism from isocyanate-based solution phase crosslinking to radical-based crosslinking, thereby achieving both crosslinking and improved shear strength
Solution Approach 2:
The patent replaces the chemical crosslinking mechanism (isocyanate crosslinker) with a radiation-induced or heat-induced radical crosslinking mechanism. By substituting the chemical crosslinking approach with physical energy input (actinic radiation or heat), the patent achieves more efficient crosslinking that directly improves shear strength and adhesive performance
2Stability of the object's composition
If low molecular weight monomer additives are used to achieve crosslinking, then crosslinking is enabled, but adhesive performance deteriorates
Solution Approach 1:
The patent extracts and eliminates the need for low molecular weight monomer additives by incorporating crosslinkable pendent groups directly into the polyester chains. This removal of extraneous additives maintains the purity and performance of the adhesive while still enabling crosslinking functionality through the built-in reactive groups
Solution Approach 2:
The polyester chains serve multiple functions: they provide the adhesive base polymer structure and simultaneously contain the crosslinkable pendent groups that enable crosslinking. This multi-functionality eliminates the need for separate monomer additives, maintaining adhesive performance while achieving crosslinking capability
3Reliability
If crosslinkable pendent groups with reactive unsaturated carbon-carbon bonds are incorporated into polyester structure, then efficient crosslinking is achieved, but molecular structure complexity increases
Solution Approach 1:
The patent applies local quality by incorporating crosslinkable pendent groups at specific locations along the polyester chains rather than throughout the entire molecular structure. The pendent groups are attached to the polyester backbone at discrete points, providing localized reactivity for crosslinking while maintaining the overall simplicity of the polyester structure. This localized approach enables efficient crosslinking without requiring complex molecular architecture
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 resulting polyesters demonstrate improved shear modulus and adhesion properties post-curing, maintaining adequate adhesion without plasticizers or tackifiers, with enhanced glass transition temperatures and molecular weights, resulting in robust and efficient adhesive compositions.
Implementation Method 1
The polyesters may be crosslinkable by the application of actinic radiation (e.g., ultraviolet radiation or electron beam radiation) and/or may be crosslinkable by the application of heat (thermal-induced crosslinking).
Implementation Method 2
The polyesters may be crosslinkable by the application of actinic radiation (e.g., ultraviolet radiation or electron beam radiation) and/or may be crosslinkable by the application of heat (thermal-induced crosslinking).
Data Source
Figure 1
AI summary
A polyester including at least one crosslinkable moiety is described. Each crosslinkable moiety includes at least one crosslinkable pendent group. A ratio of a total number of the at least one crosslinkable pendent groups to a total number of ester groups in the polyester may be in a range of 0.0001 to 0.5.