Biodegradable Polyester Shrink Films
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Solution Overview
Problem
Conventional polyolefin-based shrink films are thick, costly, and require high processing temperatures, leading to high energy consumption and potential damage to packaged products, while also having suboptimal shrink properties for packaging applications.
Innovation Solution
The development of thin shrink films using biodegradable aliphatic-aromatic polyesters with specific compositions and processing techniques, such as varying the blow-up ratio during extrusion, to achieve excellent shrink properties and reduced processing temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyolefin-based shrink films are used, then good shrink properties are achieved, but the film thickness must be relatively high (30-200 μm) to exert necessary retaining forces
Solution Approach 1:
The patent uses composite materials by blending polyolefin with biodegradable polyester (from 20-90 wt% aliphatic-aromatic polyester and 10-80 wt% other polymers like polylactic acid or aliphatic polyesters). This composite structure allows the film to achieve sufficient retaining forces at reduced thickness while maintaining shrink properties, as the combined material system provides both mechanical strength and functional performance.
2Strength
If polyolefin-based shrink films are used, then adequate retention forces are achieved, but materials costs and transport costs increase due to higher thickness and weight
Solution Approach 1:
The composite polymer system (polyolefin blended with biodegradable polyester and other polymers) provides optimized material efficiency. The synergistic combination allows achieving required retention forces with less total material quantity, reducing both material costs and transport costs associated with film weight.
Solution Approach 2:
The patent changes material composition parameters by incorporating biodegradable polyester in specific proportions (20-90 wt%) and adjusting the blend ratio of different polymers. This parameter optimization enables reduced film thickness and material quantity while maintaining or improving retention forces, thereby reducing overall material consumption and associated costs.
3Ease of manufacture
If conventional polyolefin shrink films are processed, then shrinkage is achieved, but high processing temperatures (180°C and higher) are required leading to high energy costs
Solution Approach 1:
The patent changes the thermal processing parameter by utilizing biodegradable polyester and blended polymers that enable shrinkage at lower temperatures than conventional polyolefins. The specific polymer composition (including aliphatic-aromatic polyester and other biodegradable polymers) has lower melting and softening points, allowing shrink wrapping to be performed at reduced temperatures, thereby significantly reducing energy costs while maintaining ease of manufacture.
4Ease of manufacture
If high processing temperatures are used for polyolefin shrink films, then shrinkage is achieved, but adverse consequences occur for the products to be packed
Solution Approach 1:
The patent changes the processing temperature parameter by using biodegradable polyester and blended polymer systems that exhibit shrinkage behavior at lower temperatures. This temperature reduction eliminates or minimizes thermal damage to temperature-sensitive packaged products while preserving the ease of manufacture through simplified shrink wrapping processes. The lower processing temperature becomes a beneficial parameter that protects products from heat-related adverse effects.
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 resulting films exhibit superior shrink properties with reduced thickness, lower processing temperatures, and improved retention forces on packed products, while being more cost-effective and environmentally friendly.
Implementation Method 1
The melt is discharged from the annular blown-film die, the film bubble is drawn out with continuous widening until the final bubble diameter, and the desired thickness of the film, is reached, and is subjected to intensive cooling by means of a cooling ring
Implementation Method 2
The shrinkage values for fine-gauge shrink films are preferably greater than 60% longitudinally, in particular from 70 to 80%, and smaller than 40% transversely, in particular from 20 to 30%. These shrink properties are determined to a considerable extent via the orientation introduced into, and frozen into, the material during extrusion of the film
Implementation Method 3
The high processing temperatures lead to high energy costs and can also have adverse consequences for the products to be packed. The resulting films exhibit superior shrink properties with reduced thickness, lower processing temperatures, and improved retention forces on packed products
Data Source
AI summary
The present invention relates to a process for producing shrink films comprising:A) from 20 to 90% by weight of a biodegradable, aliphatic-aromatic polyester andB) from 10 to 80% by weight of one or more polymers selected from the group consisting of: polylactic acid, polypropylene carbonate, polycaprolactone, polyhydroxyalkanoate, chitosan, gluten, and one or more aliphatic/aromatic polyesters, such as polybutylene succinate, polybutylene succinate adipate, or polybutylene succinate sebacate, or polybutylene terephthalate-co-adipate; andC) from 0 to 2% by weight of a compatibilizer,where a blow-up ratio smaller than or equal to 4:1 is selected.