Chromium Catalyst Ethylene Copolymer Fragmentation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing chromium catalyzed ethylene copolymers in gas phase polymerization struggle to achieve a balance between high Environmental Stress Crack Resistance (ESCR), Creep behavior, and melt index while avoiding production issues like fines and temperature upsets, particularly in fluidized bed gas phase processes.
Innovation Solution
A chromium catalyzed ethylene copolymer powder is developed with a superior particle fragmentation coefficient (m) by using an activated supported chromium oxide catalyst in a fluidized bed gas phase process, where the fluidization gas velocity is controlled during the initial thermal treatment, maintaining low velocities until 200°C and then increasing, and subsequent thermal treatments are performed to achieve desired morphological properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional gas phase polymerization with supported chromium oxide catalyst is used, then high productivity is achieved, but production problems such as fines and temperature upsets occur
Solution Approach 1:
The invention changes the particle size parameter of the supported chromium oxide catalyst to a specific range (D50: 40-140 μm, preferably 60-100 μm) and controls the comonomer content (0.1-5 mol%) to optimize the fragmentation coefficient. These parameter changes resolve the contradiction by maintaining high productivity while eliminating production instability issues like fines and temperature upsets through proper catalyst and composition selection.
2Reliability
If high ESCR and Creep behavior are achieved, then pipe application suitability is improved, but melt index control becomes difficult
Solution Approach 1:
The invention adjusts the comonomer content parameter within a specific range (0.1-5 mol%) to simultaneously achieve high ESCR and Creep behavior while maintaining controllable melt index. This parameter optimization resolves the contradiction by finding the optimal composition window that satisfies both mechanical property requirements and processing specifications.
3Shape
If spherical morphology is achieved, then flow properties are improved, but catalyst activity may be reduced
Solution Approach 1:
The invention optimizes the catalyst particle size parameter (D50: 40-140 μm) and comonomer content (0.1-5 mol%) to achieve a spherical morphology with a fragmentation coefficient of at least 0.29. This resolves the contradiction by selecting parameters that promote spherical particle formation while maintaining high catalyst activity through proper pore structure and surface area control.
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 process results in a polymer powder with improved morphological properties, including spherical and spheroidal morphology, high ESCR, and Creep behavior, while maintaining high catalyst activity and avoiding fragmentation problems, suitable for pipe applications.
Implementation Method 1
a chromium catalysed ethylene copolymer powder which is obtainable by a process for the co-polymerisation of ethylene with an alpha-olefin, in particular the gas phase polymerisation of ethylene with an alpha-olefin, with the aid of a supported chromium oxide based catalyst
Implementation Method 2
in a fluidised bed gas phase process, where the fluidization gas velocity is controlled during the initial thermal treatment
Data Source
AI summary
The present invention relates to a chromium catalyzed ethylene copolymer powder exhibiting a superior fragmentation coefficient.