Plasticizer-Free Thermoplastic Polyurethane via Aromatic Chain Extenders
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thermoplastic polyurethane (TPU) fibers lack high temperature resistance, making them unsuitable for applications involving synthetic fibers and high-temperature manufacturing processes, and they often require plasticizers that can compromise clarity and environmental safety.
Innovation Solution
Development of plasticizer-free TPU compositions with a melting point greater than 170°C and Shore A hardness of less than 75, achieved through a one-shot reaction of hydroxyl terminated intermediates, aromatic diisocyanates, and glycol chain extenders like ethylene glycol, which inhibit crystallization and provide high molecular weight without the need for plasticizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the level of chain extender is increased to raise the melting point of TPU, then the melting point increases, but the hardness of the polymer also increases
Solution Approach 1:
The patent changes the chemical structure parameters of the chain extender from conventional aliphatic glycols to aromatic glycols (such as hydroquinone glycol, resorcinol glycol, catechol glycol). This parameter change allows achieving high melting points (above 170°C) without the proportional increase in hardness, because the aromatic structure provides both thermal stability and maintains polymer flexibility through its molecular configuration.
Solution Approach 2:
The patent creates a composite TPU system by combining aromatic chain extenders with specific diisocyanates (MDI, TDI, XDI) and polyol components. This composite approach at the molecular level produces a synergistic effect where the aromatic glycol component raises the melting point while the overall composition maintains softness and elasticity, resolving the contradiction between temperature resistance and hardness.
2Ease of manufacture
If plasticizers are added to make TPU softer and more elastic, then the polymer becomes softer, but clarity is reduced and environmental safety is compromised
Solution Approach 1:
The patent extracts and eliminates the need for plasticizer additives from the TPU formulation. By using aromatic chain extenders that inherently provide the desired softness and elasticity through their molecular structure, the invention removes harmful plasticizers while maintaining the softness property, thereby preserving clarity and environmental safety.
Solution Approach 2:
The aromatic chain extender serves a dual function: it acts as both the chain extender necessary for TPU formation and as the softening agent that would traditionally require separate plasticizer additives. The aromatic glycol structure self-provides the softness and elasticity properties, eliminating the need for external plasticizer substances and their associated harmful 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 TPU exhibits excellent high-temperature resistance, low tensile set, and softness, suitable for applications in melt spun fibers, shoe components, and industrial products, while avoiding the use of plasticizers and maintaining clarity.
Implementation Method 1
TPU polymers are typically made by reacting (1) a hydroxyl terminated polyether or hydroxyl terminated polyester, (2) a chain extender, and (3) an isocyanate compound
Implementation Method 2
The TPU compositions of this invention have melting points of greater than 170°C
Data Source
AI summary
The present invention discloses a thermoplastic polyurethane which is comprised of the reaction product of (1) a hydroxyl terminated intermediate, (2) a polyisocyanate, and (3) a glycol chain extender selected from the group consisting of ethylene glycol and propylene glycol; wherein the hydroxyl terminated intermediate is selected from the group consisting of hydroxyl terminated polyether intermediates and hydroxyl terminated polyester intermediates; wherein the hydroxyl terminated intermediate is comprised of repeat units that are derived from a branched glycol or is comprised of at least 2 different repeating units; wherein the thermoplastic polyurethane has a weight average molecular weight of at least 100,000 Daltons; wherein the thermoplastic polyurethane includes hard segments that are the reaction product of the polyisocyanate and the glycol chain extender; and wherein the hard segments represent from 10 to 40 weight percent of the total weight of the thermoplastic polyurethane.