Wholly Aromatic Liquid-Crystalline Polyester Resin Synthesis
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Solution Overview
Problem
Wholly aromatic liquid crystalline polyester resins often contain unreacted monomers and byproducts, leading to gassing and carbonization issues during injection molding and extrusion due to insufficient condensation polymerization.
Innovation Solution
A method involving condensation polymerization of monomers followed by controlled internal pressure reduction in the reaction vessel to remove byproducts and unreacted monomers, with a pressure reduction rate of 17-20 torr/min and temperature range of 350-400°C, ensuring complete polymerization and preventing gassing and carbonization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If condensation polymerization is performed to synthesize wholly aromatic liquid crystalline polyester resin, then the resin achieves high heat resistance and high flowability, but unreacted monomers and byproducts remain causing gassing and carbonization during injection molding
Solution Approach 1:
The patent applies preliminary action by conducting a pre-polymerization step before the main condensation polymerization. This preliminary action converts highly reactive monomers into less reactive prepolymers, which then undergo further polymerization under reduced pressure. This two-stage approach allows complete removal of byproducts and unreacted monomers, preventing gassing and carbonization while maintaining the resin's high heat resistance and flowability.
2Object-generated harmful factors
If pressure reduction is applied to remove byproducts and unreacted monomers, then gassing and carbonization are prevented, but the polymerization efficiency and productivity decrease
Solution Approach 1:
The patent divides the polymerization process into two stages: a preliminary condensation polymerization stage at atmospheric pressure to form prepolymers, followed by a vacuum polymerization stage to complete the reaction and remove byproducts. This preliminary action allows the system to achieve high polymerization efficiency in the first stage without pressure reduction, then removes harmful substances in the second stage, thus maintaining overall productivity while preventing gassing and carbonization.
3Object-generated harmful factors
If complete condensation polymerization is achieved to eliminate unreacted monomers, then gassing is prevented, but the synthesis time and process complexity increase
Solution Approach 1:
The patent employs a two-stage polymerization process where the preliminary stage at atmospheric pressure rapidly converts monomers to prepolymers, reducing the burden on the subsequent vacuum stage. This preliminary action significantly shortens the total synthesis time compared to performing complete polymerization under vacuum from the beginning, while still achieving complete removal of unreacted monomers and prevention of gassing.
Solution Approach 2:
The patent segments the polymerization process into two distinct stages: (1) condensation polymerization at atmospheric pressure to form prepolymers, and (2) vacuum polymerization to complete the reaction and remove byproducts. This segmentation allows each stage to be optimized independently, reducing overall synthesis time while ensuring complete elimination of unreacted monomers and prevention of gassing.
4Strength
If high molecular weight polymer is produced through extended polymerization, then tensile strength and viscosity increase, but the risk of gassing and carbonization increases due to residual monomers
Solution Approach 1:
The patent uses preliminary condensation polymerization to convert reactive monomers into prepolymers before the main polymerization stage. This preliminary action reduces the concentration of unreacted monomers that could cause gassing and carbonization, allowing the subsequent extended polymerization to achieve high molecular weight and improved tensile strength and viscosity without the associated risks.
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 method results in a wholly aromatic liquid crystalline polyester resin with high degree of polymerization, preventing gassing and carbonization during post-processing, and enhancing melt viscosity and tensile strength.
Implementation Method 1
synthesizing a wholly aromatic liquid crystalline polyester prepolymer by condensation polymerization of at least two different monomers
Implementation Method 2
reducing an internal pressure of a reaction vessel containing the synthesized prepolymer to thereby remove a byproduct and unreacted monomers
Data Source
AI summary
Disclosed are a production method for a wholly aromatic liquid crystalline polyester resin, a wholly aromatic liquid crystalline polyester resin produced using the method, and a compound of the wholly aromatic liquid crystalline polyester resin. The disclosed production method for a wholly aromatic liquid crystalline polyester resin comprises the steps of synthesizing a wholly aromatic liquid crystalline polyester resin by synthesizing a wholly aromatic liquid crystalline polyester prepolymer by a condensation polymerization of a monomer and then reducing the pressure inside a reaction vessel containing the synthesized prepolymer at a predetermined internal pressure reduction rate of the reaction vessel.