Polypropylene Composition Stiffness Gel Reduction
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Solution Overview
Problem
Current polypropylene homopolymers and propylene-ethylene copolymers used in tape production lack sufficient stiffness and have high gel counts, making it difficult to produce thinner tapes without compromising mechanical properties, as they tend to break prematurely due to stress concentrations from defects.
Innovation Solution
A polypropylene composition with a high propylene homopolymer or propylene-ethylene copolymer content, low ethylene content, specific molecular weight ranges, and optimized molecular weight distribution, which reduces gel content and increases stiffness, allowing for the production of thinner tapes with maintained mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If thinner tapes are produced using current polypropylene homopolymers or propylene-ethylene copolymers, then material usage is reduced, but the tapes lack sufficient stiffness and break prematurely due to high gel counts
Solution Approach 1:
The patent changes the molecular weight parameters of the polypropylene homopolymer or propylene-ethylene copolymer by specifying precise ranges (Mw/Mn ratio between 8.0-13.0, Mz/Mn ratio between 20-50, melt flow rate between 0.70-2.4 g/10min at 230°C). These parameter changes result in a composition with lower gel count and higher stiffness, enabling thinner tapes to maintain mechanical strength.
2Loss of substance
If thinner tapes are produced using current polypropylene homopolymers or propylene-ethylene copolymers, then material usage is reduced, but the tapes break prematurely due to stress concentrations from defects
Solution Approach 1:
The patent optimizes the molecular weight distribution parameters (Mw/Mn ratio between 8.0-13.0, Mz/Mn ratio between 20-50) to reduce gel content and eliminate stress concentrations from defects, thereby preventing early breakage of thinner tapes while maintaining reliability.
3Ease of manufacture
If current polypropylene homopolymers or propylene-ethylene copolymers are used, then the materials are readily available, but they do not provide sufficient stiffness for thinner tape applications
Solution Approach 1:
The patent specifies precise molecular weight parameters (Mw/Mn ratio between 8.0-13.0, Mz/Mn ratio between 20-50, melt flow rate between 0.70-2.4 g/10min at 230°C) that can be achieved through controlled polymerization processes, resulting in a composition with enhanced stiffness while maintaining ease of manufacture.
Data Source
AI summary
The invention relates to a polypropylene composition comprising a propylene homopolymer or propylene-ethylene copolymer having an ethylene content of at most 1.0 wt% based on the propylene-ethylene copolymer, wherein the amount of propylene homopolymer or propylene-ethylene copolymer is at least 98wt%, for example at least 98.5wt%, preferably at least 99wt%, more preferably at least 99.5, for example at least 99.75wt% based on the polypropylene composition, wherein the polypropylene composition has a melt flow rate in the range of 0.70 to 2.4 dg/min as measured according to IS01 133 (2.16 kg/230°C), an Mw/Mn in the range from 7.0 to 13.0, wherein Mw stands for the weight average molecular weight and Mn stands for the number average weight, an Mz/Mn is in the range from 20 to 50, wherein Mz stands for the z-average molecular weight and wherein Mw, Mn and Mz are measured according to ASTM D6474-12.