Polypropylene Composition Hot-Tack Force Recyclability
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Solution Overview
Problem
Existing polyolefin compositions for heat-sealable films and hot-melt adhesives require multiple components, including butene as a comonomer, which complicates recycling and reduces recyclability while compromising hot-tack properties.
Innovation Solution
A polypropylene composition comprising 55.0 to 90.0 wt% of a crystalline propylene random copolymer and 10.0 to 45.0 wt% of an amorphous propylene copolymer, with a specific comonomer distribution and melt flow rate, which simplifies the composition and enhances recyclability while maintaining good hot-tack properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple components including butene comonomer are used in polyolefin composition, then hot-tack properties are achieved, but composition complexity increases and recyclability deteriorates
Solution Approach 1:
The invention extracts and removes the butene comonomer component from the polyolefin composition while maintaining hot-tack properties through the use of propylene copolymers with controlled comonomer content and specific melt flow rates, thereby simplifying the composition and improving recyclability
Solution Approach 2:
The invention changes the parameters of the propylene copolymer components, specifically controlling the comonomer content (5-25% for crystalline, 30-50% for amorphous) and melt flow rate (0.1-15 g/10min for crystalline, optimized for amorphous), to achieve the desired hot-tack properties without requiring butene comonomer
2Reliability
If multiple components including butene comonomer are used in polyolefin composition, then hot-tack properties are achieved, but recyclability deteriorates
Solution Approach 1:
The invention extracts and removes the butene comonomer from the composition, using only propylene and common comonomers (ethylene, C4-C8 alpha-olefins) that are easier to recycle, while maintaining hot-tack properties through optimized copolymer blends
Solution Approach 2:
The invention uses homogeneous propylene copolymer components with controlled composition and structure, avoiding the need for multiple different polyolefin types and comonomers, which simplifies the recycling process and improves recyclability
3Strength
If crystalline and amorphous propylene copolymers are blended with optimized comonomer distribution, then hot-tack force is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention changes the comonomer sequence distribution parameters, specifically controlling the isolated to block comonomer sequences ratio (I(E)) to be between 20-50%, which optimizes the hot-tack force while maintaining manufacturability through standard polymerization processes
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 polypropylene composition achieves improved recyclability and maintains strong hot-tack properties, suitable for heat-sealable films and hot-melt adhesive applications, by using a combination of crystalline and amorphous propylene copolymers with optimized comonomer distribution and melt flow rates.
Implementation Method 1
Hot-tack is the bonding strength measurable while the polymer in the heat sealed portion of a film is in a semi-molten/solidifying state
Implementation Method 2
the polymer in the heat sealed portion of a film is in a semi-molten/solidifying state
Implementation Method 3
The hot-tack is generally an important factor to improve the efficiency of a packaging production process... the heat sealing, while still in the semi-molten/solidifying state, must be able to withstand the weight of a product introduced in the package and generally also to withstand a pressure of air
Data Source
AI summary
The invention relates to a polypropylene composition comprising a crystalline propylene random copolymer and an amorphous propylene copolymer having improved hot-tack force and adhesion properties, to a process for the manufacture thereof, to the use thereof in the manufacture of adhesives and hot tack films and to articles comprising the polypropylene composition, as well as to a process for producing such article.