Propylene Copolymer Composition Broad Sealing Window
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polypropylene materials often face a trade-off between end properties like sealing strength and processability, with traditional sealing processes requiring narrow temperature control and high temperatures, which are costly and inefficient, and also require low extractables and high hot tack strength.
Innovation Solution
A propylene copolymer composition comprising two fractions: a high molecular weight fraction with low comonomer content and a low molecular weight fraction with high comonomer content, optimized for broad sealing windows, low heat sealing initiation temperatures, and high melting points, achieved through a specific molecular weight distribution and crystalline fraction composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional polypropylene sealing processes are used, then sealing strength can be achieved, but the sealing window is narrow requiring critical temperature control
Solution Approach 1:
The patent changes the molecular weight distribution parameters by combining high molecular weight fraction (≥300,000 g/mol) with low molecular weight fraction (≤100,000 g/mol), creating a bimodal distribution that broadens the sealing window from traditional narrow ranges to at least 15°C, reducing temperature control criticality while maintaining seal strength
Solution Approach 2:
The patent creates a composite polymer system by blending two polypropylene fractions with distinct molecular weight characteristics, where the high molecular weight fraction provides structural integrity and the low molecular weight fraction enhances processability and sealing behavior, achieving both reliability and ease of operation
2Reliability
If high temperature sealing is used, then sealing strength is improved, but energy consumption increases and article exposure to high temperature occurs
Solution Approach 1:
The patent changes the thermal parameters by utilizing the low molecular weight fraction to enable sealing initiation at lower temperatures (reducing the sealing window start temperature by at least 15°C compared to traditional processes), thereby reducing energy consumption while maintaining effective sealing through the optimized molecular weight distribution
3Reliability
If polypropylene with high hot tack strength is used, then sealing reliability is improved, but extractables content may increase
Solution Approach 1:
The patent applies local quality by having different molecular weight fractions perform different functions: the high molecular weight fraction maintains structural integrity and low extractables, while the low molecular weight fraction specifically enhances hot tack strength and sealing properties, with each fraction optimized for its local function within the composite system
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 propylene copolymer composition provides a broad sealing window, low hexane and xylene solubles, high hot tack strength, and high melting temperature, enabling efficient and cost-effective sealing at lower temperatures while maintaining material integrity.
Implementation Method 1
the film or film (sealing) layer becomes partly molten
Implementation Method 2
a broad sealing window would be appreciated to allow the sealing operation to take place at rather low temperature
Implementation Method 3
at least 20.0 wt-%. of a crystalline fraction having a lamella thickness of at least 5.7 nm, preferably of 5.7 to 7.4 nm, and (b) at least 10.0 wt-%. of a crystalline fraction having a lamella thickness of below than 3.0 nm
Data Source
AI summary
Propylene copolymer composition (P) comprising (a) at least 2.5 wt.-% of units derivable from C5 to C12 α-olefins, (b) at least 20.0 wt-%. of a crystalline fraction having a lamella thickness of more than 5.70 nm, and (c) at least 10.0 wt-%. of a crystalline fraction having a lamella thickness of below than 3.0 nm, said crystalline fractions are determined by the stepwise isothermal segregation technique (SIST).