Polyolefin Pipe Composition Low-Temperature Impact
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Solution Overview
Problem
Polypropylene-based pipe systems face an insufficient balance between hydraulic pressure resistance and impact resistance, particularly at low temperatures, making them difficult to handle and install during cold seasons, and existing compositions with high impact resistance have low hydraulic pressure resistance, unsuitable for high-pressure fluid transport.
Innovation Solution
A polyolefin composition comprising a copolymer of propylene and 1-hexene with a low content of recurring units derived from hexene-1, combined with a heterophasic polypropylene composition, optimized for a balance of mechanical properties, including high hydraulic pressure resistance and impact strength at low temperatures, achieved through specific polymerization processes and catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polypropylene is used to improve hydraulic pressure resistance, then durability is improved, but impact resistance deteriorates especially at low temperature
Solution Approach 1:
The patent uses a composite material system consisting of propylene homopolymer (providing hydraulic pressure resistance) and propylene-ethylene copolymer (providing impact resistance), creating a multi-phase polyolefin composition that combines the advantages of both materials to resolve the contradiction between pressure resistance and impact resistance
Solution Approach 2:
The patent optimizes the ethylene content parameter in the copolymer component (specifically 5-15 wt% ethylene units) and the proportion of homopolymer to copolymer (85-95% homopolymer, 5-15% copolymer) to achieve the optimal balance between hydraulic pressure resistance and impact resistance, particularly at low temperatures
2Strength
If heterophasic polypropylene composition is used to improve impact resistance, then workability is improved, but hydraulic pressure resistance deteriorates
Solution Approach 1:
The patent precisely controls the ethylene content parameter (5-15 wt%) and the copolymer proportion (5-15% of total composition) to maintain sufficient impact resistance while preserving high hydraulic pressure resistance, overcoming the limitation of conventional heterophasic compositions
3Strength
If copolymer with high hexene content is used to improve impact resistance, then low temperature workability is improved, but hydraulic pressure resistance deteriorates
Solution Approach 1:
The patent extracts only the necessary amount of copolymer component (5-15% propylene-ethylene copolymer with controlled ethylene content) to provide sufficient impact resistance and low-temperature workability, while removing excess copolymer that would compromise hydraulic pressure resistance, achieving an optimized balance
Data Source
AI summary
A polyolefin composition comprising (percent by weight): A) from 7% to 19%; of a copolymer of propylene and 1 -hexenewherein said copolymer contains less than 1 % of recurring units derived from hexene-1; B) from 81% to 93% of a heterophasic polypropylene composition comprising: Bl) from 86% to 95% of a propylene homopolymer, said propylene polymer being insoluble in xylene at room temperature in an amount over 85% having a polydispersity Index ranging from 3 to 10; and a Melt Index from 0.5 to 10 dg/min; B2) from 5% to 14% of a copolymer of ethylene and propylene having an ethylene derived units content ranging from 50% to 65%; said polymeric composition having a Melt Index from 0.05 to 10 dg/min.