Acryl-Urethane PSA for Low-Temp Adhesion and High-Temp Retention
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Solution Overview
Problem
Conventional pressure sensitive adhesives face challenges in maintaining adhesiveness at low temperatures while ensuring a strong retaining force at high temperatures, as there is a correlation between glass transition temperature and shear storage elastic modulus, making it difficult to achieve both properties simultaneously.
Innovation Solution
A pressure sensitive adhesive composition containing an acryl-based base polymer with an acryl-based segment and a urethane-based segment, where the urethane-based segment is incorporated in a specific ratio to lower the glass transition temperature and increase the storage elastic modulus, allowing for both low-temperature adhesiveness and high-temperature retaining force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the glass transition temperature of the pressure sensitive adhesive is lowered to improve adhesiveness at low temperature, then the storage elastic modulus decreases, leading to reduction of the adhesion retaining force at high temperature
Solution Approach 1:
The patent uses a composite polymer system comprising a first polymer (acryl-based with high glass transition temperature for high-temperature strength) and a second polymer (urethane-based with low glass transition temperature for low-temperature adhesiveness). This composite structure allows the adhesive to exhibit both high storage elastic modulus for heat resistance and low glass transition temperature for cold-temperature bonding, resolving the contradiction between maintaining strength at high temperatures and achieving adhesiveness at low temperatures.
Solution Approach 2:
The patent changes the glass transition temperature parameter of the pressure sensitive adhesive by incorporating a second polymer with a glass transition temperature of -50°C or lower into the acryl-based polymer system. This parameter modification enables the adhesive to maintain flexibility and adhesiveness at low temperatures while the crosslinked structure preserves the storage elastic modulus for high-temperature retaining force.
2Strength
If the cohesiveness of the pressure sensitive adhesive is enhanced to increase shear storage elastic modulus, then the viscidity is reduced, so that adhesive strength in a low-temperature environment may be insufficient
Solution Approach 1:
The patent creates a composite system where the first polymer (acryl-based) provides the crosslinked structure for high shear storage elastic modulus, while the second polymer (urethane-based with low glass transition temperature) maintains adequate viscidity for low-temperature adhesive strength. The synergistic combination allows both cohesiveness and low-temperature performance to be achieved simultaneously.
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 adhesive achieves reliable adhesion over a wide temperature range with improved adhesiveness at low temperatures and retaining force at high temperatures, addressing the limitations of conventional adhesives.
Implementation Method 1
properties such as a glass transition temperature can be easily adjusted by changing the types and copolymerization ratios of constituent monomers
Implementation Method 2
adhesive properties etc. can be adjusted with the cohesive force increased by introducing a crosslinked structure into a base polymer
Data Source
AI summary
A pressure sensitive adhesive includes an acryl-based base polymer. The acryl-based base polymer contains an acryl-based segment and a urethane-based segment. In the acryl-based base polymer, the content of the urethane-based segment is 3 to 20 parts by weight based on 100 parts by weight of the acryl-based segment. A pressure sensitive adhesive sheet can be obtained by applying a pressure sensitive adhesive composition on a substrate in a layer form. The pressure sensitive adhesive composition may be curable and may include a polymerization initiator. In formation of the pressure sensitive adhesive sheet, the curable pressure sensitive adhesive composition may be, as necessary.