Polypropylene Coated Article Mono-Material Sealing
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Solution Overview
Problem
Polypropylene-based coated articles face challenges in achieving high sealing properties and recycling due to the need for multi-material solutions, which complicates recycling and compromises on mechanical and sealing properties.
Innovation Solution
A polypropylene-based coated article with a specific polypropylene composition in its second coating layer, characterized by a melt flow rate, melting temperature, and molecular weight distribution, along with a metallocene catalyst-produced polypropylene homopolymer or ethylene propylene random copolymer, ensuring improved sealing behavior and mono-material composition for easier recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-material solutions are used to achieve acceptable sealing properties and mechanical properties, then sealing properties are improved, but recycling becomes much more challenging
Solution Approach 1:
The patent applies homogeneity by making the entire coated article consisting of polypropylene only - the substrate layer, first coating layer, and second coating layer are all polypropylene-based. This mono-material composition enables easy recycling while the specific formulation of the second coating layer (with controlled MFR2, Tm, and MWD) ensures excellent sealing properties, thus resolving the contradiction between sealing performance and recyclability.
2Reliability
If polypropylene composition with specific MFR2, Tm, and MWD is used in the second coating layer, then hot tack force is improved and hot tack temperature is lowered, but the composition becomes more specific and harder to manufacture
Solution Approach 1:
The patent applies parameter changes by precisely controlling three key parameters of the polypropylene in the second coating layer: MFR2 (melt flow rate at 230°C) between 10-40 g/10min, Tm (melting temperature) between 149-162°C, and MWD (molecular weight distribution) between 2.4-4.5. By optimizing these parameters, the patent achieves superior sealing properties with hot tack force improvement and reduced hot tack temperature, while keeping the parameters within achievable manufacturing ranges.
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 enhances hot tack force and lowers hot tack temperature, providing superior sealing properties while enabling recycling as a mono-material solution, simplifying the recycling process and maintaining acceptable mechanical properties.
Implementation Method 1
The coating composition is extruded in a first step whereby the flux of molten polymeric material passes through a flat die to obtain a film
Implementation Method 2
Upon cooling, the polymer adheres to its support
Data Source
AI summary
The present invention relates to a coated article comprising at least a substrate layer (SL), a first coating layer (CL1) and a second coating layer (CL2), wherein CL2 comprises a polypropylene composition comprising (A) a polypropylene homopolymer having a melt flow rate MFR2 (230° C./2.16 kg) measured according to ISO 1133 in the range from 10 to 40 g/10 min; a melting temperature Tm as determined by DSC according to ISO 11357 in the range from 149 to 162° C.; and a molecular weight distribution MWD in the range from 2.4 to 4.5 as determined by GPC; and/or (B) an ethylene propylene random copolymer having a melt flow rate MFR2 (230° C./2.16 kg) measured according to ISO 1133 in the range from 4 to 40 g/10 min; a melting temperature Tm as determined by DSC according to ISO 11357 in the range from 115 to 145° C.; and a number of 2,1 and 3,1 regio defects in the range from 0.01 to 1.2 mol-% as measured by 13C NMR; and wherein SL and CL1 are polypropylene-based layers. Furthermore, the present invention refers to a process for manufacturing the coated article and to its use. Another aspect of the present invention relates to a process for recycling the coated article to obtain a recycled polypropylene and to the use of said recycled polypropylene.