Biodegradable Polyurethane Adhesive for Composite Films
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Solution Overview
Problem
Current degradable composite films for flexible packaging face challenges in achieving both stability and rapid biological disintegration, with existing adhesives failing to balance the need for a stable bond while promoting film disintegration in biologically active environments.
Innovation Solution
The use of an aqueous polyurethane dispersion adhesive composed of at least 60% diisocyanate, polyester diol, and bifunctional carboxylic acid, where the polyester diol is composed of at least 80% aliphatic dicarboxylic acid and aliphatic diol, ensuring biodegradability and effective bonding of biologically disintegrable substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a stable adhesive is used to bond composite films, then bonding strength is improved, but biological disintegrability deteriorates
Solution Approach 1:
The adhesive composition is modified by specifying precise parameter ranges: polyurethane content of 30-70 wt%, polyester diol composed of at least 80% aliphatic dicarboxylic acid and aliphatic diol, and controlled molecular weight. These parameter changes enable the adhesive to achieve both stable bonding and biodegradability by optimizing the chemical structure for dual functionality.
Solution Approach 2:
The adhesive itself is formulated as a composite material system combining polyurethane with specific polyester diols and bifunctional carboxylic acids. This composite adhesive structure allows different components to contribute differently: polyurethane provides bonding strength while the aliphatic polyester components provide biodegradability, resolving the contradiction between stability and disintegrability.
2Reliability
If degradable materials are used for composite films, then biological disintegrability is improved, but bonding stability deteriorates
Solution Approach 1:
The adhesive formulation uses controlled parameter changes including polyurethane content (30-70 wt%), specific polyester diol composition (at least 80% aliphatic), and molecular weight ranges. These parameters are optimized to ensure the adhesive maintains bonding stability during service but degrades reliably in composting conditions.
Solution Approach 2:
The adhesive is designed as a temporary bond that is intended to last during the product's service life but then degrade completely in the composting environment. The aliphatic polyester components are selected specifically for their biodegradability, allowing the adhesive to fulfill its bonding function temporarily before being discarded in the composting process.
3Ease of manufacture
If conventional adhesives are used for composite films, then ease of manufacture is improved, but biodegradability deteriorates
Solution Approach 1:
The adhesive formulation specifies clear parameter ranges that guide manufacturing: polyurethane content of 30-70 wt%, polyester diol with at least 80% aliphatic components, and controlled molecular weight. These defined parameters make the manufacturing process straightforward while ensuring biodegradability, eliminating the need for complex formulations.
Solution Approach 2:
The adhesive uses homogeneous aliphatic polyester diols composed of at least 80% aliphatic dicarboxylic acid and aliphatic diol, providing consistent biodegradable performance. This homogeneity in material composition simplifies manufacturing compared to complex blends, while the aliphatic structure ensures reliable biodegradability.
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 solution provides composite films with enhanced biodegradability, meeting the requirement of disintegrating to less than 10% of the original weight after 12 weeks of composting and achieving high strength in bonding, while maintaining safety and non-toxicity of degradation products.
Implementation Method 1
at least a first substrate is bonded to at least one second substrate using the polyurethane dispersion adhesive
Implementation Method 2
The trigger for degradation can be microbiological, hydrolytic or oxidative degradation at a specific point in the main chain of a polymer
Implementation Method 3
The trigger for degradation can be microbiological, hydrolytic or oxidative degradation at a specific point in the main chain of a polymer
Implementation Method 4
The trigger for degradation can be microbiological, hydrolytic or oxidative degradation at a specific point in the main chain of a polymer
Data Source
AI summary
The invention relates to the use of an aqueous polyurethane dispersion adhesive for producing biologically disintegratable composite films, wherein at least two substrates are glued to each other using the polyurethane dispersion adhesive, wherein at least one of the substrates is a biologically disintegratable polymer film. The polyurethane is made up to at least 60 wt % of diisocyanates, polyesterdiols, and at least one bifunctional carboxylic acid selected from dihydroxycarboxylic acid and diaminocarboxylic acid.