Polyethylene Pipe Composition for High ESCR Drip Irrigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Drip irrigation pipes made from conventional polyethylene materials lack sufficient mechanical properties, particularly environmental stress cracking resistance (ESCR), which is critical for their durability and performance in water transportation.
Innovation Solution
A polyethylene composition produced using a specific catalyst system involving a solid catalyst component prepared by contacting a dehydrated support with magnesium compounds and modifying compounds, followed by treatment with a titanium halide compound, resulting in polyethylene with high molecular weight and density, enhancing mechanical properties like melt stretching force and ESCR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyethylene materials (LLDPE, LDPE) are used for drip irrigation pipes, then the pipes can be manufactured with typical thin-walled design and standard processing, but the environmental stress cracking resistance (ESCR) and mechanical properties are insufficient
Solution Approach 1:
The patent changes the molecular weight distribution parameters of polyethylene by using a specific catalyst system (solid catalyst component prepared by contacting dehydrated support with magnesium compound and modifying compound, then treating with titanium halide compound). This produces polyethylene with MWD of 3.6-5.5 and high Mz+1 (≥720,000 g/mol), which simultaneously improves both ESCR and mechanical strength without changing the basic material type
Solution Approach 2:
The patent creates a composite catalyst system combining solid catalyst component (with specific surface area 5-500 m²/g) and titanium halide compound. This composite catalytic system produces polyethylene with optimized molecular structure that achieves both high ESCR (≥1500 hours) and improved mechanical properties, resolving the contradiction between reliability and strength
2Reliability
If polyethylene with high molecular weight is produced to improve ESCR, then the environmental stress cracking resistance increases, but the processability and manufacturing ease may deteriorate
Solution Approach 1:
The patent optimizes the molecular weight distribution parameters by controlling the catalyst system and polymerization conditions. The resulting polyethylene has MWD of 3.6-5.5 and Mz+1 of at least 720,000 g/mol, which provides high ESCR while maintaining good processability through controlled melt behavior and rheological properties
Solution Approach 2:
The patent creates a dynamic molecular weight distribution with multiple peaks or a broad distribution (Mw/Mn of 3.6-5.5), which allows the material to exhibit different mechanical behaviors at different stress levels and processing conditions. This dynamic structure enables both high ESCR under service conditions and adequate processability during manufacturing
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 resulting polyethylene composition exhibits improved mechanical properties, including high melt stretching force, melt stretching stress, and significantly increased Environmental Stress-Cracking Resistance (ESCR), making it suitable for producing durable drip irrigation pipes.
Implementation Method 1
contacting a dehydrated support having hydroxyl groups with a magnesium compound having the general formula MgR1
Implementation Method 2
polyethylene produced in the presence of a solid catalyst component and a co-catalyst
Data Source
AI summary
The invention relates to a pipe comprising polyethylene or a polyethylene composition comprising polyethylene and carbon black, wherein the polyethylene is produced in the presence of a solid catalyst component and a co-catalyst, wherein the solid catalyst component is prepared by a process comprising the steps of: (a) contacting a dehydrated support having hydroxyl groups with a magnesium compound having the general formula MgR1R2, wherein R1 and R2 are the same or different and are independently selected from the group comprising an alkyl group, alkenyl group, alkadienyl group, aryl group, alkaryl group, alkenylaryl group and alkadienylaryl group; (b) contacting the product obtained in step (a) with modifying compounds (A), (B) and (C), wherein: (A) is at least one compound selected from the group consisting of carboxylic acid, carboxylic acid ester, ketone, acyl halide, aldehyde and alcohol; (B) is a compound having the general formula R11f(R12O)gSiXh, wherein f, g and h are each integers from 0 to 4 and the sum of f, g and h is equal to 4 with a proviso that when h is equal to 4 then modifying compound (A) is not an alcohol, Si is a silicon atom, O is an oxygen atom, X is a halide atom and R11 and R12 are the same or different and are independently selected from the group comprising an alkyl group, alkenyl group, alkadienyl group, aryl group, alkaryl group, alkenylaryl group and alkadienylaryl group; (C) is a compound having the general formula (R13O)4M, wherein M is a titanium atom, a zirconium atom or a vanadium atom, O is an oxygen atom and R13 is selected from the group comprising an alkyl group, alkenyl group, alkadienyl group, aryl group, alkaryl group, alkenylaryl group and alkadienylaryl group; and (c) contacting the product obtained in step (b) with a titanium halide compound having the general formula TiX4, wherein Ti is a titanium atom and X is a halide atom, whereby the polyethylene has a molecular weight Mz+1 of at least 720,000 g/mol and less than 2,500,000 g/mol.