Biodegradable Polyester-Polyurethane Adhesive Formulation
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Solution Overview
Problem
Conventional pressure-sensitive adhesives (PSAs) face challenges in achieving high cohesion and adhesion while being biodegradable, particularly in applications requiring easy and residue-free detachability, especially under hot and humid conditions, and they often require waiting for chemical reactions to solidify before use in continuous coating operations.
Innovation Solution
A pressure-sensitive, biodegradable chemical reaction product is developed using aliphatic polyester polyols, dual hydroxyl-functionalized chain extenders, and aliphatic diisocyanates, with a specific isocyanate-to-hydroxyl group ratio, allowing for chemical crosslinking to create a PSA with high viscosity for immediate use and easy detachment without residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional pressure-sensitive adhesives are used to achieve high cohesion and adhesion, then bonding strength is improved, but biodegradability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by using aliphatic polyester polyols with specific hydroxyl functionalities (2-4) and controlling the isocyanate-to-hydroxyl ratio (0.4-1.0), creating a biodegradable PSA that maintains high cohesion and adhesion through optimized molecular structure rather than conventional non-biodegradable polymers
Solution Approach 2:
The invention creates a composite chemical structure by reacting polyester polyols with chain extenders and diisocyanates to form a polyurethane-based PSA with integrated crosslinking capability, combining the biodegradability of polyester with the adhesive performance of polyurethane systems
2Strength
If chemical crosslinking is performed to improve cohesion, then bonding strength is improved, but processing time increases due to waiting for solidification
Solution Approach 1:
The patent incorporates crosslinking agents and catalysts into the adhesive formulation during manufacturing, enabling crosslinking reactions to proceed rapidly under application conditions (temperature, humidity) without requiring extended waiting periods for solidification before the adhesive becomes functional
Solution Approach 2:
The adhesive system transitions dynamically from a liquid or semi-liquid state during application to a crosslinked gel state during service, with the crosslinking rate controlled by environmental conditions and formulation parameters, allowing rapid transition that minimizes processing time while achieving high cohesion
3Strength
If high viscosity is achieved to improve adhesion, then surface stickiness is improved, but ease of application deteriorates due to difficulty in coating
Solution Approach 1:
The patent optimizes the molecular weight and hydroxyl functionality distribution of the polyester polyols to achieve a balanced viscosity range that provides sufficient surface stickiness for adhesion while remaining fluid enough for continuous coating operations, avoiding the need for extreme viscosity modifications
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 PSAs with high cohesion and adhesion, maintaining performance after storage under harsh conditions, and enabling continuous coating operations without waiting for solidification, ensuring biodegradability and easy detachment without residue.
Implementation Method 1
chemical crosslinking to create a PSA with high viscosity
Implementation Method 2
The proportional viscous flow is necessary for the achievement of adhesion. Only the viscous components, brought about by macromolecules with relatively high mobility, permit effective wetting and effective flow onto the substrate where bonding is to take place.
Implementation Method 3
PSAs generally at room temperature have a permanent inherent stickiness, thus having a certain viscosity and tack, and so they wet the surface of the respective substrate even under low applied pressure.
Implementation Method 4
The proportional elastic forces of resilience are necessary for the attainment of cohesion. They are brought about, for example, by very long-chain macromolecules with a high degree of coiling, and also by physically or chemically crosslinked macromolecules, and they permit the transmission of the forces that act on an adhesive bond.
Implementation Method 5
biodegradable polyester-polyurethane
Data Source
AI summary
A biodegradable, pressure sensitive adhesive based on the chemical reaction product ofone or more aliphatic polyester polyols having a hydroxyl functionality of between >2 and <4;one or more aliphatic polyester-polyols having a hydroxyl functionality of between >1 and ≤2;one or more chain extenders having dual hydroxyl functionalities and having a molecular weight of ≤200 g/mo; and,one or more aliphatic diisocyanates;characterized in that the ratio of the total number of isocyanate groups to the total number of hydroxyl groups in the materials used to form the reaction product is between ≥0.4 and <1.0, and preferably is between ≥0.6 and ≤0.9.