Farnesene-Based Pressure Sensitive Adhesive for High Temperature
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Solution Overview
Problem
Conventional pressure sensitive adhesives (PSAs) lack sufficient strength and integrity at high temperatures, particularly above 204°C, and often experience a loss of cohesive strength and shear adhesion when exposed to radiation curing, especially in systems formulated with polymers containing propylene.
Innovation Solution
A curable pressure sensitive adhesive composition comprising a farnesene-based pre-polymer and a (meth)acrylate, combined with a photo-initiator, which forms a polymer upon exposure to actinic radiation, providing a secure bond suitable for high temperature applications up to about 260°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If radiation curing is used to crosslink the polymeric component, then cohesive strength is increased, but peel and shear values are reduced and tack is lost
Solution Approach 1:
The patent changes the chemical parameters of the adhesive system by using a pre-polymer with specific functional groups (Formula I) that control the crosslinking reaction. By adjusting the molecular weight, functional group density, and composition of the pre-polymer and monomer mixture, the patent achieves a balance between cohesive strength and adhesive properties after curing.
Solution Approach 2:
The patent creates a composite adhesive system combining a pre-polymer (Formula I) with a functional (meth)acrylate monomer. This composite formulation allows the system to exhibit both the cohesive strength needed for high-temperature performance and the adhesive properties needed for bonding, resolving the contradiction between strength and ease of manufacture.
2Ease of operation
If conventional PSAs are used, then ease of application is maintained, but shear failure temperature is insufficient for high temperature applications
Solution Approach 1:
The patent applies the adhesive in an uncured, printable state that maintains ease of application properties. The preliminary action of applying the adhesive before curing allows it to be printed, positioned, and bonded under normal conditions, after which curing provides the high-temperature resistance.
Solution Approach 2:
The patent utilizes a phase transition approach where the adhesive transitions from a soft, printable state (before curing) to a rigid, heat-resistant state (after curing). This allows the material to exhibit different properties at different stages of the process, achieving both ease of application and high-temperature performance.
3Ease of manufacture
If propylene-containing polymers are used in PSA systems, then certain processing advantages are achieved, but radiation curing leads to loss of cohesive strength and shear adhesion
Solution Approach 1:
The patent extracts the problematic propylene-containing polymer from the adhesive system and replaces it with a pre-polymer (Formula I) that does not contain propylene. This extraction eliminates the interference with radiation curing while maintaining the desired processing advantages and adhesive properties.
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 significant increase in shear failure temperature and maintains acceptable peel and tack properties, ensuring the adhesive remains effective and functional in high temperature environments.
Implementation Method 1
exposing the curable composition to actinic radiation to polymerize at least a portion of the composition
Data Source
AI summary
Pressure sensitive adhesives having high shear failure temperatures are made by reacting a curable pressure sensitive adhesive composition comprising: a. a pre-polymer having a structure according to Formula (I) R1—[Polymer]—R2. wherein the [Polymer] is a linear or branched polymer backbone derived from the reaction of farnesene and at least one other monomer: and R1 is a (C1-C12) alkyl group or R2. and R2 comprises a (meth)acrylate group having a structure according to Formula (II), wherein Z is selected from the group consisting of hydrogen and methyl: b. at least one functional (meth)acry late monomer: and c. at least one photo-initiator.