Liquid Crystalline Polyester Film Adhesion via Terminal Ratio Control
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Solution Overview
Problem
The adhesive strength between a liquid crystalline polyester film and a second metal layer is reduced due to insufficient melting of the liquid crystalline polyester during lamination, which is attributed to solid phase polymerization occurring during heat-treatment, causing an endothermic peak temperature increase detected by differential scanning calorimetry.
Innovation Solution
A liquid crystalline polyester powder with a molar ratio of acyl group terminal/hydroxyl group terminal of 10 or less, a flow starting temperature of 240° C. or lower, and a weight average molecular weight of 20000 or less is developed, incorporating a naphthalene structure and produced through specific acylation and ester exchange reactions, to prevent temperature increase in the endothermic peak after solid phase polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat-treatment is applied to obtain liquid crystalline polyester film, then solid phase polymerization progresses, but the endothermic peak temperature increases causing insufficient melting during lamination
Solution Approach 1:
The invention changes the chemical composition parameters of the liquid crystalline polyester by controlling the molar ratio of acyl group terminal to hydroxyl group terminal to be 10 or less. This parameter change prevents excessive solid phase polymerization during heat-treatment, thereby maintaining the endothermic peak temperature at an appropriate level for good adhesion during lamination
Solution Approach 2:
The invention performs preliminary control of the terminal group ratio during the polyester synthesis stage. By controlling the molar ratio of acyl group terminal/hydroxyl group terminal to be 10 or less before heat-treatment, the polymerization behavior during subsequent heating is predetermined, preventing excessive temperature increase in the endothermic peak
2Strength
If solid phase polymerization occurs during heat-treatment, then molecular weight increases, but melting temperature increases reducing adhesive strength
Solution Approach 1:
The invention optimizes the terminal group ratio parameter (acyl group terminal/hydroxyl group terminal ≤ 10) to balance molecular weight development and melting temperature. This allows sufficient molecular weight for mechanical strength while preventing excessive melting temperature increase that would harm adhesion
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 ensures that the liquid crystalline polyester film can be easily melted during lamination, enhancing the adhesive strength between the film and the second metal layer, while maintaining excellent dielectric properties and thermal stability.
Implementation Method 1
solid phase polymerization of the liquid crystalline polyester contained in the liquid crystalline polyester powder can progress
Implementation Method 2
the temperature of the endothermic peak detected by differential scanning calorimetry of the liquid crystalline polyester
Implementation Method 3
the liquid crystalline polyester film 10 can be heated to melt the liquid crystalline polyester, and the liquid crystalline polyester film 10 and the second metal layer 15 can be bonded together
Data Source
AI summary
A liquid crystalline polyester powder comprising a liquid crystalline polyester wherein the liquid crystalline polyester has a molar ratio of acyl group terminal/hydroxyl group terminal, as analyzed by 1H-NMR, is 10 or less.