Diketo-Blocked Polyurethane Catalyst System
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Solution Overview
Problem
Current polyurethane systems for artificial leather face challenges such as limited robustness, toxicity concerns from catalysts, and difficulties in producing thick layers without defects or solvent residues, with existing catalysts either being too reactive at room temperature or requiring complex mixing systems.
Innovation Solution
A catalyst system comprising a metal-based catalyst and a diketo compound with a melting point of ≥15° C., which suppresses reactivity at room temperature and activates at elevated temperatures, allowing for the production of robust and flexible polyurethane layers without the need for complex mixing systems and minimizing toxic residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a metal-based catalyst is used to accelerate polyurethane reaction, then reaction speed increases, but the mixture becomes too reactive at room temperature requiring complex mixing systems
Solution Approach 1:
The catalyst is pre-blocked by forming a complex with diketo compound before the polyurethane reaction. This preliminary action suppresses the catalyst's activity at room temperature, allowing simple mixing systems to be used without risk of premature reaction. The blocking is reversed in situ at reaction temperature, eliminating the need for complex mixing systems while maintaining high productivity.
Solution Approach 2:
The invention changes the physical state parameter of the catalyst system by using diketo compounds with melting points of 15-50°C. These compounds transition from solid blocked form at room temperature to liquid active form at reaction temperature (70-100°C), enabling simple mixing at ambient conditions while achieving rapid reaction when heated.
2Ease of operation
If liquid diketo compounds like acetylacetone are used as catalyst blockers, then reactivity is suppressed at room temperature, but toxic residues remain in the finished product
Solution Approach 1:
The invention replaces persistent toxic blockers (acetylacetone) with solid diketo compounds that decompose completely at reaction temperatures. The blocked catalysts based on metals like bismuth, zinc, or calcium combined with diketo compounds decompose after catalyzing the reaction, leaving no toxic residues in the finished product while maintaining ease of operation during processing.
3Productivity
If the catalyst is activated at room temperature for rapid reaction, then productivity increases, but processing time is reduced requiring complex mixing systems
Solution Approach 1:
The catalyst system exhibits periodic activation: inactive (blocked) form during mixing and processing at room temperature, then activated form when heated to reaction temperature. This periodic action allows sufficient processing time during the inactive phase while achieving rapid reaction and high productivity during the activated phase, eliminating the need for complex mixing systems.
4Object-generated harmful factors
If solid diketo compounds with high melting points are used, then toxic residues are minimized, but reactivity activation temperature is too high
Solution Approach 1:
The invention optimizes the melting point parameter of diketo compounds to the specific range of 15-50°C. This parameter change ensures that the compounds remain solid at room temperature (minimizing toxic residues) but melt and activate the catalyst at moderate reaction temperatures of 70-100°C, avoiding excessively high activation temperatures while maintaining low toxicity.
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
This solution provides a long processing time at room temperature while ensuring rapid reaction at elevated temperatures, enabling the production of thick, defect-free polyurethane layers with improved mechanical stability and reduced toxicity, suitable for use in artificial leather applications.
Implementation Method 1
a catalyst system comprising a metal-based catalyst based on a salt or an organometallic compound and a diketo compound having a melting point of ≥15° C.
Implementation Method 2
a diketo compound having a melting point of ≥15° C., which suppresses reactivity at room temperature and activates at elevated temperatures
Data Source
AI summary
The present invention relates to reactive compounds for the production of polyurethane layers, said compounds comprising an isocyanate component composed of at least one polyfunctional isocyanate, an oligomer of a polyfunctional isocyanate or an isocyanate prepolymer, a polyol component composed of at least one polyol, and a catalyst system comprising a metal-based catalyst based on a salt or an organometallic compound and a diketo compound having a melting point of ≥15° C. The catalyst system has the characteristic feature of low toxicity and very low reactivity under processing conditions, but can be activated by increasing the temperature, with the result that polyurethanes that have reacted as far as possible can be formed in a short time. The present invention further relates to methods for producing such polyurethane layers, to polyurethane layers produced from the reactive compounds, and to composite structures that comprise such polyurethane layers. In addition, the present invention relates to the use of the specified catalyst systems for the reaction of polyols and polyisocyanates.