Polypropylene-Plastomer Blend Sealing Initiation Temperature
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Solution Overview
Problem
Polypropylene films used in packaging face challenges with high sealing initiation temperatures, which hinder fast packaging processes and energy efficiency, especially in high-speed packaging lines and when handling temperature-sensitive goods.
Innovation Solution
A polypropylene-plastomer blend with 80-93 wt.% polypropylene and 7-20 wt.% ethylene-based plastomer, where the polypropylene is a propylene random copolymer without an elastomeric phase and the ethylene-based plastomer is a copolymer of ethylene and 1-octene, is developed to reduce sealing initiation temperatures, improving film sealability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polypropylene films are used for packaging, then good optical properties and processability are achieved, but sealing initiation temperature is too high for fast packaging
Solution Approach 1:
The patent changes the compositional parameters of the film by incorporating ethylene-based plastomer (7-20 wt.%) with specific properties (density 0.860-0.920 g/cm³, melting point -50°C to 100°C) into the polypropylene matrix. This parameter change lowers the sealing initiation temperature from typical polypropylene levels (around 160-170°C) to below 150°C, enabling faster packaging while maintaining film integrity
Solution Approach 2:
The patent creates a composite material system combining polypropylene random copolymer with ethylene-based plastomer. The plastomer acts as a sealing promoter phase dispersed in the polypropylene matrix, providing low-temperature sealing capability while the polypropylene continuous phase maintains the film's mechanical and optical properties. This composite approach resolves the contradiction between high sealing temperature and fast packaging requirements
2Strength
If high sealing temperatures are used, then sealing strength is improved, but energy consumption increases and temperature-sensitive goods are damaged
Solution Approach 1:
The patent changes the thermal parameters of the film material by incorporating plastomer with low melting point (-50°C to 100°C). This enables sealing to occur at lower temperatures (below 150°C) while achieving adequate sealing strength, thereby reducing energy consumption and preventing damage to temperature-sensitive packaged goods
3Illumination intensity
If polypropylene films are used, then good optical properties are achieved, but sealing behaviour needs improvement
Solution Approach 1:
The patent creates a composite where ethylene-based plastomer is dispersed in the polypropylene matrix. The plastomer forms discrete low-melting-point domains that provide improved sealing behavior, while the polypropylene continuous phase maintains the film's excellent optical properties (gloss, transparency, surface smoothness). This composite structure allows simultaneous achievement of good optics and reliable sealing
Solution Approach 2:
The patent applies local quality by concentrating the sealing functionality in specific plastomer domains dispersed throughout the polypropylene matrix. The plastomer-rich regions provide low-temperature sealing capability, while the surrounding polypropylene matrix maintains overall film integrity and optical properties. This localized functional differentiation resolves the contradiction between optical quality and sealing reliability
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 blend achieves a significant reduction in sealing initiation temperature, enabling faster and more energy-efficient packaging processes while maintaining excellent optical and mechanical properties, suitable for high-speed packaging lines and temperature-sensitive goods.
Implementation Method 1
the ethylene based plastomer has a melting point of -50° C. to 100° C.
Implementation Method 2
a low heat sealing initiation temperature is of advantage
Data Source
AI summary
The present invention relates to a polymer blend and the film of the polymer blend or the film layers of the polymer blend as a surface layer or coating. More particularly, the invention relates to a polymer blend which may be extruded as such or extruded onto one or both sides of packaging film to give a sealing surface(s) which exhibits surprisingly heat sealability suitable for form-fill-and-seal-packaging. The present invention also relates the use of ethylene based plastomer to reduce sealability of films comprising polypropylene.