Polypropylene Multilayer Laminate With Recyclable Hot-Melt Adhesive
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Solution Overview
Problem
Existing multilayer articles are difficult to recycle due to issues of yield, technical feasibility, and performance, resulting in recycled materials with unsatisfactory mechanical and physicochemical properties.
Innovation Solution
A multilayer system comprising layers of polypropylene bonded by a hot-melt pressure-sensitive adhesive composition, consisting of specific copolymers and nonhydrogenated tackifying resins, enabling mechanical recycling and producing recycled articles with improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multilayer articles are made from different materials to achieve specific properties, then the functional performance is improved, but the recyclability deteriorates
Solution Approach 1:
The patent uses polypropylene as the base material for all layers (outer layers and adhesive layers), creating a homogeneous material composition throughout the multilayer structure. This allows the entire article to be recycled as a single polymer type, eliminating the recyclability problems associated with mixed-material laminates while maintaining the functional benefits of the multilayer design.
Solution Approach 2:
The patent creates a composite multilayer structure where polypropylene layers are bonded with a polypropylene-based hot-melt adhesive containing specific copolymers (ethylene-vinyl acetate and ethylene-acrylic acid). This composite approach provides enhanced functional properties (barrier, mechanical, sealing) while maintaining recyclability because all components are compatible polypropylene-based materials that can be processed together.
2Strength
If traditional hot-melt adhesives are used in multilayer systems, then the bonding performance is improved, but the mechanical properties of recycled articles deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters of the hot-melt adhesive by incorporating specific copolymers (ethylene-vinyl acetate with 15-30% vinyl acetate and ethylene-acrylic acid with 10-20% acrylic acid) alongside polypropylene. These compositional changes enable the adhesive to maintain strong bonding performance while being fully compatible with polypropylene recycling processes, thus preserving mechanical properties in recycled articles.
Solution Approach 2:
The patent designs the adhesive system to be fully recoverable with the polypropylene base material during recycling. The specific copolymer composition allows the adhesive to be discarded as a contaminant in traditional systems but is instead recovered together with the polypropylene layers, maintaining the integrity and mechanical properties of the recycled material.
3Reliability
If multilayer articles are designed for single-use, then the functional requirements are met, but environmental sustainability deteriorates
Solution Approach 1:
By making the entire multilayer structure homogeneous (all polypropylene-based), the patent enables the article to be recycled multiple times without degradation, transforming it from a single-use product to a reusable/recyclable material source, thereby improving environmental sustainability while maintaining functional performance.
Solution Approach 2:
The patent enables the recovery of the entire multilayer structure as a valuable recycled material rather than discarding it as waste. The homogeneous polypropylene composition allows complete recovery and reuse, converting the article from a single-use disposable item into a sustainable material cycle component.
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 system allows for the production of recycled articles with enhanced breaking force, impact strength, and elongation at break, overcoming the limitations of traditional recycling methods.
Implementation Method 1
an adhesive layer Ad consisting of a hot-melt pressure-sensitive adhesive composition CA
Implementation Method 2
i) from 40% to 80% by weight of at least one copolymer A comprising more than 80% by weight of units derived from but-1-ene; ii) optionally at least one copolymer T comprising more than 50% by weight of units derived from propylene
Implementation Method 3
at least one nonhydrogenated tackifying resin obtained by polymerization, or copolymerization with an aromatic hydrocarbon, of mixtures of unsaturated aliphatic hydrocarbons having from 4 to 6 carbon atoms
Data Source
AI summary
The present invention relates to a multilayer system F1 comprising: a layer C1 comprising at least one polypropylene, an adhesive layer Ad made up of a hot-melt self-adhesive composition CA, and a layer C2 comprising at least one polypropylene, said multilayer system F1 comprising at least 80% by weight of polypropylene or a mixture of polypropylenes relative to the total weight of said system. The invention also relates to the use of said system F1 for producing a recycled item.