Heterophasic Propylene Pellets with In-Situ Venting
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Solution Overview
Problem
Current methods for reducing FOG emission in heterophasic propylene copolymers, such as venting or degassing, increase costs and can lead to thermal degradation, while higher melt flow rates desired for energy efficiency also increase FOG values, making it challenging to achieve both low emissions and high mechanical properties.
Innovation Solution
A thermoplastic polymer sheath surrounding glass filaments with a heterophasic propylene copolymer composition that includes a propylene-based matrix and a dispersed ethylene-α-olefin copolymer, processed to achieve a melt flow rate of at least 40 g/10min and a FOG value of no more than 350 µg/g, using a catalyst system with specific electron donors and visbreaking to optimize properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If venting or degassing process is applied to reduce FOG emission, then FOG value is reduced, but production cost increases and thermal degradation occurs
Solution Approach 1:
The patent applies preliminary action by incorporating a venting agent during the polymerization process itself, rather than performing venting as a separate post-production step. The venting agent is mixed with the monomer feedstock before polymerization, enabling low molecular weight materials to be removed in-situ during polymer formation, thereby reducing FOG emission without requiring additional costly venting equipment or processes.
Solution Approach 2:
The patent uses a venting agent as an intermediary substance that facilitates the removal of low molecular weight materials during polymerization. This venting agent acts as a mediator between the polymerization process and the desired low FOG emission, enabling selective removal of unwanted components without directly exposing the polymer to harsh thermal degradation conditions.
2Object-generated harmful factors
If venting or degassing process is applied to reduce FOG emission, then FOG value is reduced, but thermal degradation and yellowing occur
Solution Approach 1:
The patent performs the venting action preliminarily during the polymerization process rather than as a subsequent thermal treatment step. By removing low molecular weight materials in-situ during polymer formation, the patent avoids subjecting the polymer to prolonged high-temperature exposure that would cause thermal degradation and yellowing, thereby preserving optical properties.
3Use of energy by moving object
If melt flow rate is increased for energy efficiency, then energy consumption is reduced, but FOG value increases
Solution Approach 1:
The patent applies preliminary venting action during polymerization to remove low molecular weight materials before the polymer is formed. This preliminary removal of FOG-causing components allows the subsequent injection molding process to operate at higher melt flow rates with reduced energy consumption, without the FOG emission problem re-emerging during processing.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining low FOG emission throughout the entire production process - from polymerization with in-situ venting, through storage, to final injection molding. This continuous control allows high melt flow rates to be sustained without FOG emission spikes, enabling energy-efficient processing.
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 enables pellets with high melt flow rates for efficient processing while maintaining low FOG emissions and desirable mechanical properties, suitable for automotive interior applications, reducing production costs and energy consumption.
Implementation Method 1
The heterophasic propylene copolymer is prepared by polymerisation of propylene and ethylene in a gas phase in the presence of a catalyst system comprising a Ziegler-Natta catalyst and at least one external electron donor
Implementation Method 2
The intermediate heterophasic propylene copolymer is visbroken by peroxide shifting to a higher melt flow rate
Data Source
AI summary
The invention relates to a pellet comprising a thermoplastic polymer sheath intimately surrounding glass filaments, which glass filaments are covered at least in part with an impregnating agent and extend in a longitudinal direction of said pellets, wherein the thermoplastic polymer sheath is prepared from a thermoplastic polymer composition comprising A) a heterophasic propylene copolymer consisting of a propylene-based matrix and a dispersed ethylene-α-olefin copolymer, wherein the heterophasic propylene copolymer has a melt flow rate of at least 40 g/10min as determined in accordance with ISO 1133 (230°C, 2.16 kg) and a FOG value of at most 350 µg/g as determined by VDA 278, wherein the glass filaments are present in an amount of 10-70wt% based on the pellet.