Electrostatic Dissipative TPU via High Molecular Weight Additives
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Solution Overview
Problem
Conventional electrostatic dissipative (ESD) additives for thermoplastic urethanes (TPUs) face issues such as thermal instability, poor miscibility with polymers, surface degradation, and unacceptably high levels of extractable ions, which affect the moldability and electrical conductivity of plastics, making them unsuitable for various applications.
Innovation Solution
A composition of electrostatic dissipative thermoplastic polyurethane (ESD-TPU) is developed by reacting a polyester polyol intermediate with a diisocyanate and a chain extender, optionally incorporating a metal-containing salt, to achieve improved ESD properties and physical properties, including low surface and volume resistivity, and reduced extractable anions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ESD additives are incorporated into polymer during processing, then ESD properties are improved, but thermal stability deteriorates due to high processing temperatures damaging the additives
Solution Approach 1:
The patent changes the molecular weight parameter of the ESD additive from conventional low molecular weight to high molecular weight (average molecular weight of at least 10,000), which fundamentally alters the thermal stability and migration characteristics of the additive, allowing it to withstand processing temperatures without degradation
Solution Approach 2:
The patent creates a composite system by combining high molecular weight ESD additive with specific base polymers (polyester, polyamide, polyolefin, or elastomer) at controlled ratios (0.1-10 parts per 100 parts polymer), achieving a balanced composite material that provides both ESD functionality and thermal stability
2Stability of the object's composition
If high molecular weight ESD additives are used, then thermal stability and miscibility are improved, but extractable anion levels increase to unacceptable levels
Solution Approach 1:
The patent changes the chemical composition parameters of the high molecular weight ESD additive by selecting specific types (polyethylene oxide, polypropylene oxide, epichlorohydrin polymers, glycidyl ether polymers) and controlling their molecular weight and structure, which reduces extractable anion content to acceptable levels while maintaining thermal stability
Solution Approach 2:
The patent applies different ESD additive types and concentrations to different applications based on the specific requirements for extractable anion levels, allowing optimization of local properties for specific end uses
3Reliability
If conventional ESD agents are used, then ESD capability is achieved, but surface degradation occurs due to migration and deposition on mold surfaces
Solution Approach 1:
The patent changes the molecular weight parameter to high molecular weight (at least 10,000), which significantly reduces the mobility and migration tendency of the ESD additive, preventing surface deposition and maintaining mold surface finish quality
Solution Approach 2:
Instead of using low molecular weight additives that migrate to the surface, the patent inverts the approach by using high molecular weight additives that remain embedded in the bulk polymer matrix, achieving ESD functionality without surface degradation
4Reliability
If cationic or anionic ESD agents are used, then ESD properties are improved, but plastic degradation occurs particularly in PVC
Solution Approach 1:
The patent changes the chemical nature parameter of the ESD additive by selecting non-ionic high molecular weight polymers (polyethylene oxide, polypropylene oxide, etc.) that do not exhibit cationic or anionic characteristics, thereby eliminating the degradation mechanism while maintaining ESD functionality
Solution Approach 2:
The patent uses high molecular weight polymers that are inherently stable and do not degrade the base polymer, replacing the short-lived conventional ESD agents that cause degradation through ionic reactions
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 ESD-TPU composition exhibits enhanced ESD properties comparable to polyether TPU and improved physical properties similar to polyester TPU, with reduced extractable anions and improved stability, making it suitable for diverse applications including electronics and clean room materials.
Implementation Method 1
reacting (a) at least one polyester polyol intermediate with (b) at least one diisocyanate and (c) at least one chain extender
Implementation Method 2
compositions of electrostatic dissipative thermoplastic polyurethane (ESD-TPU)... improved ESD properties... low surface and volume resistivity
Data Source
AI summary
The present invention relates to an electrostatic dissipative thermoplastic polyurethane composition made by reacting (a) at least one polyester polyol intermediate with (b) at least one diisocyanate and (c) at least one chain extender. The polyester polyol intermediate, may be derived from at least one dialkylene glycol and at least one dicarboxylic acid, or an ester or anhydride thereof. The invention further provides for methods of making said thermoplastic polyurethane composition, polymer blends containing said thermoplastic and polymer articles made from said thermoplastic.