Propylene Terpolymer Pipes Low-Temperature Impact
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Solution Overview
Problem
Small diameter pipes require materials with high impact resistance at low temperatures to prevent brittleness, while maintaining efficiency and minimizing material usage.
Innovation Solution
A polyolefin composition comprising a propylene/ethylene/1-hexene terpolymer and a heterophasic propylene ethylene copolymer with specific weight percentages and properties, including a terpolymer with 1-hexene and ethylene units, and a copolymer with 1-butene or 1-octene units, optimized for high impact resistance and melt flow rate, combined with an inorganic filler agent for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the wall thickness of small diameter pipes is reduced to minimize material usage and improve feed efficiency, then the internal diameter increases and material consumption decreases, but the pipe becomes brittle and loses impact resistance
Solution Approach 1:
The patent applies composite materials by combining a propylene/ethylene/1-hexene terpolymer with a heterophasic propylene/ethylene copolymer in specific weight ratios (85-99.5% terpolymer and 0.5-15% copolymer). This composite composition provides both the reduced density needed for thin-walled pipes and the impact resistance required for reliability, resolving the contradiction between material usage and impact resistance.
Solution Approach 2:
The patent changes the chemical composition parameters of the polymer material by controlling the ethylene content (0.5-10 wt%) and 1-hexene content (1.0-5.0 wt%) in the terpolymer, as well as the composition of the copolymer component. These parameter changes enable the material to achieve both low density for thin walls and high impact resistance, simultaneously improving material usage efficiency and reliability.
2Reliability
If a heterophasic propylene ethylene copolymer with high elastomeric content is used to improve impact resistance, then impact properties improve, but the melt flow rate increases excessively making processing difficult
Solution Approach 1:
The patent precisely controls the parameters of the copolymer component, specifying that it should contain 15-60 wt% of 1-butene or 1-octene derived units and have a MFR between 0.5-35.0 g/10min. By limiting the copolymer content to 0.5-15% in the final composition, the patent achieves improved impact properties while keeping the overall MFR of the composition within the manageable range of 0.2-4.0 g/10min, thus resolving the contradiction between impact properties and ease of manufacture.
Solution Approach 2:
The patent applies local quality by using a heterophasic copolymer structure where different phases with different properties are distributed within the material. The elastomeric phase provides impact resistance locally, while the crystalline propylene phase maintains structural integrity and controls overall flow characteristics, enabling both improved impact properties and manageable processing.
3Reliability
If the ethylene content in the terpolymer is increased to improve flexibility and impact resistance, then low temperature performance improves, but the melting temperature decreases and structural integrity may be compromised
Solution Approach 1:
The patent optimizes the ethylene content parameter within a specific range of 0.5-10 wt% in the terpolymer structure. This controlled ethylene incorporation improves low-temperature flexibility and impact resistance while maintaining the melting temperature within the acceptable range of 130-145°C. The balanced parameter selection resolves the contradiction between low temperature performance and melting temperature.
Data Source
AI summary
1. A polyolefin composition comprising: A) from 85.0 wt% to 99.5 wt%; A terpolymer containing propylene, ethylene and 1- hexene wherein: (i) the content of 1-hexene derived units ranges from 1.0 wt% to 5.0%; (ii) the content of ethylene derived units is comprised between 0.5 wt% and 10.0 wt% (iii) the melting temperature ranges from 130° C to 145° C; B) from 0.5 wt% to 15 wt%; of a ethylene copolymer with a comonomer selected from 1-butene, 1-hexene and 1-Octene containing from 10 wt% to 50 wt% of 1-butene derived units aid copolymer having a MFR (measured at 190°C 2.16 kg of load) comprised between 0.5 g/10 min; wherein the resulting polyolefin composition has an melt flow rate (230°C/5 kg.. ISO 133) ranging from 0.2 g/10min to 4.0 g/10min; the sum A+B being 100.