Propylene Block Copolymer Catalyst Pore Control
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Solution Overview
Problem
Propylene block copolymers tend to adhere to the inner wall of polymerizers and each other during storage, especially when produced with high rubber content, which affects their flowability and processing efficiency.
Innovation Solution
A propylene block copolymer with an evaluated flowability value of 40% or less is achieved by using a solid titanium catalyst component with a specific pore distribution index, combined with a high ethylene unit content in the rubber component, and a two-step polymerization process involving a crystalline propylene polymer and rubber components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a propylene block copolymer is produced with high rubber content to improve impact resistance, then impact resistance is improved, but adhesion to the inner wall of polymerizer increases and flowability deteriorates
Solution Approach 1:
The patent changes the pore size distribution parameters of the solid titanium catalyst component, specifically setting the pore diameter to 0.003 to 0.01 μm and controlling the pore volume to 0.03 to 0.15 mL/g. These parameter changes in the catalyst structure enable high rubber content incorporation while maintaining low adhesion and good flowability, resolving the contradiction between impact resistance and flowability
Solution Approach 2:
The patent creates a composite catalyst system combining solid titanium catalyst component with specific pore characteristics and magnesium compound support. This composite structure enables simultaneous achievement of high rubber content (for impact resistance) and controlled adhesion (for flowability), as the composite catalyst controls polymer morphology and surface properties
2Strength
If a propylene block copolymer is produced with high rubber content to improve impact resistance, then impact resistance is improved, but adhesion to polymerizer wall increases
Solution Approach 1:
The patent changes the pore size parameters of the catalyst to 0.003 to 0.01 μm and pore volume to 0.03 to 0.15 mL/g, which controls the polymerization process to produce particles with reduced surface adhesion properties. This enables high rubber content while suppressing wall adhesion
Solution Approach 2:
The patent converts the potential harm of high rubber content (which increases adhesion) into a benefit by using the rubber component to modify particle surface properties through the controlled catalyst system. The rubber content of 5-50 mass% is optimized to reduce surface energy and adhesion while maintaining impact resistance
3Productivity
If the pore volume of the solid titanium catalyst component is increased to enhance polymerization activity, then productivity is improved, but particle size distribution widens causing aggregation
Solution Approach 1:
The patent optimizes the pore volume parameter to a specific range of 0.03 to 0.15 mL/g and pore diameter to 0.003 to 0.01 μm. These parameter changes balance polymerization activity (productivity) with particle size control, preventing aggregation while maintaining high productivity
Solution Approach 2:
The patent creates local quality differences in the catalyst pore structure, with specific pore sizes (0.003 to 0.01 μm) distributed throughout the catalyst particles. This local pore structure control ensures uniform monomer diffusion and polymer growth, maintaining narrow particle size distribution even at high polymerization rates
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 solution effectively suppresses adhesion to polymerizer walls and enhances flowability, allowing for easier processing and production of propylene block copolymers with improved flow characteristics and impact resistance.
Implementation Method 1
a first polymerization step of preparing a crystalline propylene (co)polymer by polymerizing propylene and an optional α-olefin in the presence of a solid titanium catalyst component
Implementation Method 2
a second polymerization step of polymerizing the crystalline propylene (co)polymer prepared in the first polymerization step and a raw material of a polymer selected from the group consisting of rubber components
Data Source
AI summary
The purpose of the present invention is to provide a propylene-based block copolymer, the deposition thereof on the inner wall of the polymerization vessel having been sufficiently inhibited. The propylene-based block copolymer of the present invention has a flowability evaluation value of 40% or less, the value being calculated with the following equation wherein X (sec) is the number of seconds over which 100 g of the copolymer having ordinary temperature falls from a stainless-steel funnel having an inner diameter of 11.9 mm and Y (sec) is the number of seconds over which 100 g of the copolymer which has been held at 80° C. for 24 hours under a load of 10 kg falls from the funnel having an inner diameter of 11.9 mm.Flowability evaluation value (%)={(Y/X)−1}×100.