Recycled Polypropylene Composition for Packaging
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Solution Overview
Problem
There is a lack of satisfactory recycled polypropylene copolymers (copoPP) that match the performance qualities of polypropylene homopolymers (hPP) in terms of transparency, impact strength, and wear resistance, which are essential for packaging materials.
Innovation Solution
A thermoplastic composition comprising recycled homopolypropylene (hPP) with a melt flow index greater than 20 g/10 min, combined with a mixture of olefins including a propylene/C2 or C4-10 α-olefin copolymer and a homogeneous ethylene/C4-10 α-olefin copolymer, in specific weight ratios, to achieve performance qualities equivalent to polypropylene copolymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recycled homopolypropylene (hPP) is used for packaging materials, then environmental sustainability is improved through recycling, but mechanical properties and transparency deteriorate compared to polypropylene copolymers
Solution Approach 1:
The patent creates a composite material system by combining recycled hPP with a specific mixture of olefins (propylene/C2 or C4-10 α-olefin copolymer and homogeneous linear or branched ethylene/C4-10 α-olefin copolymer). This composite approach allows the recycled hPP to maintain its environmental sustainability while the added olefin mixture restores and enhances mechanical properties and transparency to match polypropylene copolymer performance.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the composition ratios of the olefin mixture (from 2% to approximately 25% by weight relative to total composition) and the ratio of second copolymer to first copolymer (between 0.1 and 0.4). These parameter adjustments optimize the balance between maintaining recyclability and achieving target mechanical properties and transparency.
2Strength
If polypropylene copolymers are used to achieve good mechanical qualities and transparency, then performance is improved, but environmental sustainability worsens due to difficulty in recycling
Solution Approach 1:
The patent converts the typically harmful effect of polymer blending (which can reduce recyclability) into a benefit by using a carefully designed olefin mixture that is compatible with hPP recycling streams. The specific copolymer combination restores mechanical properties and transparency while maintaining the ability to be processed and recycled as polypropylene materials, thus converting the complexity of copolymer formulation into a sustainable solution.
3Ease of manufacture
If recycled hPP with high melt flow index is used, then processability is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent applies parameter changes by selecting recycled hPP with a specific melt flow index range (greater than 20 g/10 min at 230°C under 2.16 kg load) and compensating for the resulting mechanical strength reduction through the addition of the olefin mixture. The controlled composition of first and second copolymers in specific ratios restores mechanical strength while maintaining the high processability enabled by the high MFI hPP base material.
Data Source
AI summary
Title Thermoplastic composition based on recycled polypropylene The present invention relates to a thermoplastic composition comprising at least: (a) a recycled homopolypropylene, hPP, having a specific melt flow index and (b) from 2% to 25% by weight, with respect to the total weight of the composition, of a specific mixture of olefins. It is additionally targeted at a process for the preparation of a moulded article starting from such a composition.