Biodegradable Polymer Blend Surface Energy
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Solution Overview
Problem
Bio-plastic films with low surface energies face challenges in bonding with water-based inks and adhesives, requiring additional pre-treatments like corona discharge or chemical priming, and additives like long chain fatty acid esters reduce surface energy, affecting printability and adhesion in applications such as multilayer laminates and metallization.
Innovation Solution
A thermoplastic biodegradable polymer blend comprising 10-60% starch, 40-90% carrier polymers, and 0-0.5% process aids, which significantly reduces or eliminates additives to increase surface energy to at least 40 mNm^-1, enabling enhanced printability and adhesion without pre-treatments using water-borne or hot-melt inks and adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If long chain fatty acid esters and amides are added as lubricants to improve processability, then processing performance is improved, but surface energy is reduced
Solution Approach 1:
The patent changes the concentration parameter of lubricants from typical levels (1% or higher) to reduced levels (0.1-1000 ppm), which fundamentally alters the balance between processability and surface energy. This parameter change allows the material to maintain adequate processability while preserving sufficient surface energy for printing and adhesion.
Solution Approach 2:
The patent introduces internal lubricants (fatty acid groups within the polymer structure itself) as an intermediary mechanism that provides lubrication without requiring external additive lubricants. This internal lubrication system maintains processability while avoiding the surface energy reduction caused by traditional external lubricant additives.
2Reliability
If pre-treatment methods like corona discharge or chemical priming are applied to increase surface energy, then printability and adhesion are improved, but device complexity and cost increase
Solution Approach 1:
The patent enables the bio-plastic material to self-provide the necessary surface energy characteristics through its inherent molecular structure (internal lubricants with fatty acid groups). This self-service approach eliminates the need for external pre-treatment equipment and processes, as the material naturally possesses the required surface properties for printing and adhesion.
Solution Approach 2:
The desired surface energy characteristics are built into the material formulation during manufacturing, before the actual printing or adhesion processes. The internal lubricants are incorporated into the polymer structure in advance, ensuring the material arrives at the printing stage with the necessary surface properties already established, eliminating the need for preliminary surface treatment steps.
3Productivity
If high levels of lubricants are used to ensure smooth processing, then processing performance is improved, but bonding with water-based inks and adhesives deteriorates
Solution Approach 1:
The patent dramatically changes the lubricant concentration parameter from high levels (1%+) to trace levels (0.1-1000 ppm), which is sufficient for processing but insufficient to compromise bonding. This parameter change resolves the contradiction by finding the optimal concentration point that satisfies both processing and bonding requirements.
Solution Approach 2:
The patent uses internal lubricants embedded in the polymer structure as an intermediary that provides just enough lubrication for processing without creating a surface layer that would interfere with bonding. These internal lubricants act as a mediator between the bulk material (needing lubrication) and the surface (needing adhesion), providing processability while maintaining bonding capability.
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 blend achieves improved surface energy, allowing for easier and more durable surface decoration, printing, and adhesion without pre-treatments, and is suitable for various thermoplastic processes, including film blowing, casting, and injection molding, while maintaining biodegradability and compostability.
Implementation Method 1
the polymer blend has a surface energy after processing of at least 40 mNm−1
Data Source
AI summary
A thermoplastic, biodegradable polymer blend having a high surface energy and good adhesion without the need for pretreatment, is made up of starch in the range 10% to 60% by weight of the polymer blend, at least one further carrier polymers in the range 40% to 90% by weight of the polymer blend and one or more process aids in the range 0% to 0.5% by weight of the polymer blend. The polymer blends typically have a surface energy after processing of at least 40 mN/m.