Branched Polypropylene Polymerization via Local Supercritical Particle Conditions
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Solution Overview
Problem
Current processes for manufacturing branched polypropylene often require high temperatures and pressures, leading to inferior products with high misinsertions and economic inefficiencies, as well as difficulties in achieving high melting points and controlled supercritical conditions within the polymer particles.
Innovation Solution
A process that polymerizes propylene under non-supercritical conditions in a reaction vessel at pressures above 45.4 bar and temperatures below 90°C, using a metallocene catalyst system with a surface area not exceeding 350 m2/g and a pore volume below 3.50 cm3/g, which creates supercritical conditions within the growing polymer particle, optimizing branching and reducing catalyst fragmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperatures and pressures are used to manufacture branched polypropylene, then the polymerization reaction proceeds efficiently, but the product quality deteriorates with high misinsertions and inferior properties
Solution Approach 1:
The patent changes the temperature and pressure parameters from conventional high values to moderate ranges (70-90°C and 45-60 bar), which resolves the contradiction by maintaining adequate reaction efficiency while significantly reducing misinsertions and improving product quality
Solution Approach 2:
The patent creates local supercritical conditions within the growing polymer particle while maintaining moderate bulk conditions, allowing efficient polymerization at the particle level without subjecting the entire system to harsh conditions that cause misinsertions
2Shape
If high temperatures are used to enable vinyl-terminated chain ends and long-chain branching, then branching is achieved, but misinsertions increase and product quality deteriorates
Solution Approach 1:
The patent uses moderate temperatures (70-90°C) combined with specific catalyst systems to achieve long-chain branching without the high temperatures that cause misinsertions, thereby resolving the contradiction between achieving desired polymer structure and maintaining product quality
Solution Approach 2:
The patent employs metallocene catalysts as intermediaries that enable long-chain branching formation at moderate temperatures, avoiding the need for high temperatures that would otherwise be required to achieve vinyl-terminated chain ends
3Productivity
If supercritical conditions are applied in the reaction vessel, then polymerization efficiency is improved, but the process becomes economically inefficient and product melting points decrease
Solution Approach 1:
The patent creates supercritical conditions locally within the growing polymer particle rather than throughout the entire reaction vessel, achieving efficient polymerization where needed while avoiding the economic inefficiencies of maintaining supercritical conditions system-wide
Solution Approach 2:
The patent shifts the supercritical condition achievement from a bulk system approach to a particle-level phenomenon, creating overheating and supercritical states within individual polymer particles while maintaining moderate bulk temperature and pressure conditions
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
This approach enables the production of branched polypropylene with a branching index of less than 1.00 and low pore volume, achieving efficient and reproducible results while avoiding the drawbacks of high-temperature, high-pressure processes, such as reduced misinsertions and improved melting points.
Implementation Method 1
polymerizing propylene and optionally another comonomer under non-supercritical conditions in a reaction vessel
Implementation Method 2
selecting process conditions in such a way that an overheating in the growing polypropylene particle and/or on the particle's surface occurs, generating supercritical conditions in said growing particle and/or on said particle's surface
Data Source
AI summary
A process for manufacturing a branched polypropylene, said branched polypropylene having a branching index g′ of less than 1.00, the process comprising the step of polymerizing propylene and optionally one or more other comonomers under non-supercritical conditions in a reaction vessel, wherein:c. the pressure during the polymerization of propylene and optionally one or more other comonomers in said reaction vessel is at least 45.4 bar;d. the temperature during the polymerization of propylene and optionally one or more other comonomers in said reaction vessel is below 90° C.; andc. the polymerization of propylene and optionally one or more other comonomers is conducted in said reaction vessel in the presence of a catalyst system having a surface area of not more than 350 m2/g, measured according to ISO 9277, and said catalyst system comprises a metallocene catalyst having zirconium as the transition metal.