Thermoplastic Polyurethane Chain Extender Mixture for Efflorescence Control
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Solution Overview
Problem
Aliphatic thermoplastic polyurethanes based on hexamethylene diisocyanate have a high tendency towards efflorescence, which limits their application in sectors requiring reduced deposit formation, especially in automobile interiors and high-insolation areas, where good mechanical and thermal properties are valuable but efflorescence is undesirable.
Innovation Solution
A thermoplastic polyurethane composition using a mixture of 60 to 85 mol % 1,6-hexanediol as the main chain extender and 15 to 40 mol % 1,3-propanediol as the co-chain extender, combined with an aliphatic diisocyanate and reactive compounds, significantly reduces the tendency towards efflorescence and deposit formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aliphatic thermoplastic polyurethanes based on hexamethylene diisocyanate are used, then good mechanical and thermal properties are achieved, but high tendency toward efflorescence and deposit formation occurs
Solution Approach 1:
The patent changes the chemical composition parameters of the chain extenders by using a specific mixture of 1,6-hexanediol (60-85 mol%) and 1,3-propanediol (15-40 mol%), replacing conventional single-chain extenders. This parameter change in composition resolves the contradiction by reducing efflorescence tendency while preserving the mechanical and thermal properties provided by the aliphatic diisocyanate base polymer.
2Strength
If conventional chain extenders are used in HDI-based TPUs, then mechanical properties are maintained, but deposit formation on moldings increases
Solution Approach 1:
The patent applies composite material principle by creating a composite chain extender system that combines two different diols (1,6-hexanediol and 1,3-propanediol) in specific proportions. This composite approach leverages the complementary properties of both components: 1,6-hexanediol provides mechanical strength while 1,3-propanediol reduces efflorescence and deposit formation, achieving both goals simultaneously.
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 specific combination of alkanediols effectively inhibits efflorescence of low-molecular-weight constituents, thereby reducing deposit formation on moldings, making the thermoplastic polyurethanes suitable for applications in automobile interiors and other sectors exposed to high insolation.
Implementation Method 1
thermoplastic polyurethane, obtainable via reaction of the following components A, B, C, and, if appropriate, D and E (a) at least one aliphatic, organic diisocyanate, as component A, (b) at least one compound which is reactive toward component A
Data Source
AI summary
A thermoplastic polyurethane is obtainable via reaction of the following components A, B, C, and, if appropriate, D and E(e) at least one aliphatic, organic diisocyanate, as component A,(f) at least one compound which is reactive toward component A and which has a weight-average molar mass of from 500 to 10 000 g/mol, as component B,(g) a mixture composed of alkanediols as chain extenders, comprising from 60 to 85 mol % of 1,6-hexanediol as main chain extender C1 and from 15 to 40 mol % of 1,3-propanediol as co-chain extender C2, as component C,(h) at least one catalyst, as component D,(i) conventional additives as component E.