Liquid Crystal Polyester Twin-Screw Extruder Temperature Control
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Solution Overview
Problem
Liquid crystal polyesters are susceptible to hydrolysis by water or basic components during the melt-kneading process with fillers, leading to reduced heat resistance and productivity issues due to gas generation, which can cause 'shoot up' phenomena and decreased product extrusion.
Innovation Solution
A method involving a twin-screw extruder with specific temperature control and screw configurations to minimize hydrolysis, using a first addition port for non-fibrous fillers like talc or mica and a second port for fibrous fillers, with vents to manage volatile components, ensuring resin temperatures within defined ranges to prevent hydrolysis and maintain heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If liquid crystal polyester is melt-kneaded with filler using an extruder, then the filler can be incorporated into the resin composition, but hydrolysis of the liquid crystal polyester occurs due to water and basic components in the filler, leading to deterioration of heat resistance
Solution Approach 1:
The addition port is divided into a first addition port for non-fibrous fillers and a second addition port for fibrous fillers. This segmentation allows different types of fillers to be added at appropriate positions, preventing hydrolysis while maintaining filler incorporation capability.
Solution Approach 2:
The liquid crystal polyester is pre-kneaded in the kneading portion upstream of the first addition port before the filler is added. This preliminary kneading ensures the resin is properly prepared and temperature-controlled before filler addition, preventing hydrolysis during the subsequent mixing process.
2Ease of manufacture
If liquid crystal polyester is hydrolyzed during melt-kneading, then filler can be mixed with the resin, but volatile components are generated causing gas to flow into the hopper and blow up the resin, delaying supply and decreasing productivity
Solution Approach 1:
The harmful volatile components generated during hydrolysis are extracted and removed from the system through the vent port, preventing them from accumulating in the hopper and causing shoot-up phenomena that would delay resin supply.
Solution Approach 2:
The vent port acts as an intermediary pathway to safely discharge volatile components from the extruder barrel, preventing them from interfering with the resin supply mechanism in the hopper and maintaining continuous productivity.
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
This method effectively suppresses hydrolysis and maintains the heat resistance of liquid crystal polyester compositions, improving productivity by stabilizing the extrusion process and preventing resin blow-up.
Implementation Method 1
a resin temperature of the liquid crystal polyester after being kneaded in the kneading portion provided nearest to the first addition port on the upstream side thereof satisfying formula (1) shown below: FT−100(° C.)≦T1≦FT+20(° C.)
Implementation Method 2
liquid crystal polyesters which exhibit excellent melt flowability
Implementation Method 3
as a result of the hydrolysis of the liquid crystal polyester, volatile components (gas) are generated
Data Source
AI summary
A method of producing a liquid crystal polyester composition, the twin-screw extruder including a cylinder having a supply port for supplying the liquid crystal polyester, a first addition port for adding the filler other than fibrous fillers and a second addition port for adding a fibrous filler which are provided downstream of the supply port, and a screw provided with kneading portions on the upstream side and downstream side of the first addition port, a resin temperature (T1) of the liquid crystal polyester after kneading in the nearest upstream kneading portion satisfying formula (1), and a resin temperature (T2) of the liquid crystal polyester after kneading in the nearest downstream kneading portion satisfying formula (2):FT−100(° C.)≦T1≦FT+20(° C.) (1)FT−100(° C.)≦T2≦FT+30(° C.) (2)wherein FT represents the flow starting temperature of the liquid crystal polyester.