Thermoplastic Polyurethane Composite Adhesion
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Solution Overview
Problem
Thermoplastic polyurethanes (TPUs) have high melting and processing points, making them difficult to work with, and they do not adhere well to rubbers, requiring the use of tie-layers with pre-compounded vulcanization additives, which can lead to premature vulcanization during extrusion.
Innovation Solution
A thermoplastic polyurethane formed from a polybutadiene diol, polyester diol, and isocyanate component with a specific molecular weight and melting point range, allowing for a composite article with a tie layer that includes a vulcanizing additive, extruded at temperatures below 130°C to prevent premature vulcanization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If vulcanization additives are pre-compounded into the TPU, then adhesion to rubber is improved, but premature vulcanization occurs during extrusion
Solution Approach 1:
The patent changes the processing temperature parameter by maintaining extrusion temperature below 130°C, which prevents premature vulcanization of the TPU while still allowing the tie layer to adhere to the rubber substrate. This temperature control enables the TPU to remain in a stable, non-vulcanized state during processing despite the presence of vulcanization additives.
Solution Approach 2:
The patent applies preliminary action by pre-compounding the tie layer with vulcanization additives and adhering it to the rubber substrate before the main TPU extrusion process. This sequence allows the tie layer to be prepared and positioned in advance, ensuring proper adhesion readiness while the main TPU is extruded at controlled temperatures that prevent unwanted vulcanization reactions.
2Ease of manufacture
If TPU is processed at high temperature, then processing flow is improved, but vulcanization reactions initiate prematurely
Solution Approach 1:
The patent modifies the temperature parameter by implementing a two-stage temperature approach: extrusion is performed below 130°C to prevent vulcanization, followed by a separate heating stage at higher temperatures (130-180°C) to achieve proper TPU processing flow and final product formation. This parameter change resolves the contradiction by decoupling the vulcanization prevention requirement from the processing flow requirement.
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 enables the formation of a composite article with improved adhesion between TPU and rubber, preventing premature vulcanization and allowing for effective curing and vulcanization, enhancing the usability of TPUs in various applications.
Implementation Method 1
extruding the second thermoplastic polyurethane at a temperature of less than 130° C.
Implementation Method 2
heating the combination of the first thermoplastic polyurethane, the second thermoplastic polyurethane, and the rubber at a temperature of greater than or equal to 130° C. to cure the first and second thermoplastic polyurethanes, vulcanize the rubber
Data Source
AI summary
A thermoplastic polyurethane is the reaction product of a polybutadiene diol, a polyester diol, and a isocyanate component. The polybutadiene diol has a weight average molecular weight (Mw) of from 200 to 20,000 g/mol. The polyester diol has a melting point of from 40 to 90° C. The reactants allow the thermoplastic polyurethane itself to have a melt flow index measured at 120° C. and 22.6 kg of from 0.1 to 200 grams, per 10 minutes as measured according to ASTM 1238. The thermoplastic polyurethane also has a melting point of from 50 to 300° C. The thermoplastic polyurethane is used to form a composite article.