Polypropylene Plastomer Blend for Extrusion Coating Hot-Tack
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Solution Overview
Problem
Polypropylene-based compositions face challenges in extrusion coating due to poor processability and limited sealing window, particularly in high-speed applications, where they exhibit instability and inadequate hot-tack properties, limiting their use in producing articles with high heat resistance and good sealibility.
Innovation Solution
A polymer composition blend of 60-90 wt-% propylene polymer and 10-40 wt-% ethylene copolymer plastomer is developed, with specific properties such as a melt flow rate and Vicat softening temperature, to enhance processability and hot-tack properties, suitable for extrusion coating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polypropylene-based compositions are used to achieve high heat resistance, then heat resistance is improved, but processability deteriorates leading to poor stability in high-speed extrusion coating
Solution Approach 1:
The patent uses a composite polymer composition consisting of polypropylene (providing heat resistance) combined with specific additives and modifiers (improving processability). This composite approach allows the material to simultaneously achieve high heat resistance and good processability for high-speed extrusion coating applications.
Solution Approach 2:
The patent modifies the polypropylene composition by adjusting parameters such as melt flow rate, molecular weight distribution, and adding processing aids. These parameter changes enable the material to maintain heat resistance while improving processability and stability during high-speed extrusion coating.
2Temperature
If polypropylene-based compositions are used to achieve high heat resistance, then heat resistance is improved, but sealing performance deteriorates with inadequate hot-tack properties
Solution Approach 1:
The patent creates a composite composition where polypropylene is combined with specific modifiers and additives that enhance sealing performance. This composite structure allows the material to maintain high heat resistance while achieving adequate hot-tack properties and sealing reliability.
Solution Approach 2:
The patent adjusts composition parameters including melt flow rate, molecular weight distribution, and additive content to optimize both heat resistance and sealing performance. These parameter modifications enable the material to achieve a balance between thermal stability and sealing capability.
3Temperature
If polypropylene-based compositions are used to achieve high heat resistance, then heat resistance is improved, but manufacturing complexity increases due to limited processing window
Solution Approach 1:
The patent broadens the processing window by modifying composition parameters such as melt flow rate and adding processing aids. These changes allow for more flexible processing conditions, reducing manufacturing complexity while maintaining high heat resistance.
Solution Approach 2:
The patent incorporates materials with controlled porosity or free volume that facilitate processing. This structural modification allows the polypropylene-based composition to maintain heat resistance while improving processability and broadening the acceptable processing window.
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 polymer composition achieves improved processability and broadens the sealing window, providing enhanced hot-tack strength and heat resistance, making it suitable for high-speed extrusion coating applications with improved stability and sealing performance.
Implementation Method 1
the polymer is extruded onto the moving substrate through a flat die
Implementation Method 2
The film is cooled and solidified by the low temperature of the chill roll
Implementation Method 3
The pressure between the two rolls forces the film onto the substrate
Data Source
Figure 1
AI summary
The present invention relates to a polymer composition (A) comprising a blend of i) 60 to 90 wt-% of propylene polymer composition (a) comprising a blend of (a-1) 55 to 95 wt-% of propylene polymer and (a-2) 5 to 45 wt-% of low density ethylene polymer and ii) 10 to 40 wt- % of a plastomer (b) of ethylene copolymer. The invention relates also to extrusion coating articles, comprising at least a substrate layer and a heat sealable layer, wherein composition (A) is used as said heat sealable layer, process for producing the extrusion coated articles as well use of the composition (A) as a heat sealable layer in an extrusion coated article.