Polypropylene Composition for Low Sealing Initiation Temperature
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Solution Overview
Problem
Current polypropylene films for packaging face challenges in achieving a balance of low sealing initiation temperature (SIT), high hot-tack strength, and improved optical properties, while also needing to withstand steam sterilization, which existing solutions fail to adequately address.
Innovation Solution
A polypropylene composition comprising a blend of a propylene terpolymer and an ethylene-based plastomer, with specific comonomer content and processing conditions, optimized for low SIT, high hot-tack, and improved optical properties, including the use of a Ziegler-Natta catalyst for propylene terpolymer production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a low seal initiation temperature is used to support high speed packaging, then sealing speed and efficiency are improved, but hot-tack strength deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the comonomer content (ethylene 0.3-4.0 wt%, C4-C10 alpha-olefin 4.0-16.0 wt%) and molecular weight distribution (MFR 0.5-20.0 g/10 min) of the propylene terpolymer to achieve optimal balance between low SIT and high hot-tack strength
Solution Approach 2:
The patent uses composite materials by creating a terpolymer structure combining propylene with two different comonomers (ethylene and C4-C10 alpha-olefin), where each comonomer contributes different properties: ethylene provides low SIT while the C4-C10 alpha-olefin enhances hot-tack strength and optical properties
2Reliability
If multiple components are used in a monolayer film to improve sealing properties, then sealing performance is improved, but optical properties (haze) deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the specific composition ranges of comonomers and molecular weight parameters to achieve both good sealing performance and low haze in a monolayer structure
Solution Approach 2:
The patent applies local quality by creating a terpolymer with localized comonomer distribution, where ethylene units provide sealing initiation properties while C4-C10 alpha-olefin units contribute to optical clarity, with each comonomer type distributed throughout the polymer matrix
3Reliability
If polymer components are blended to improve sealing properties, then sealing performance is improved, but inhomogeneity increases
Solution Approach 1:
The patent applies merging by combining two different copolymerization reactions into a single terpolymer structure, where propylene polymerizes with both ethylene and C4-C10 alpha-olefin comonomers simultaneously, creating a homogeneous single-phase material with combined functionality
Solution Approach 2:
The patent applies parameter changes by controlling the comonomer content ranges and molecular weight distribution to ensure homogeneous mixing and compatibility of the different monomer units within the terpolymer chain
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 composition achieves a combination of low sealing initiation temperature, high hot-tack strength, and beneficial optical properties, enabling effective sterilization and improved packaging performance.
Implementation Method 1
the propylene terpolymer (a) is obtainable, preferably obtained, in the presence of a Ziegler-Natta catalyst
Data Source
AI summary
New polypropylene composition which combines low sealing initiation temperature (SIT), high hot-tack and good optical properties, like low haze and its use.