Polyurethane Catalyst Composition for Demold Time Control
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Solution Overview
Problem
Polyurethane manufacturers face challenges in achieving cost efficiency and producing complex parts due to rapid viscosity increase and long demold times, which are influenced by catalyst selection, and there is a need for catalysts that delay reaction initiation without significantly extending demold time.
Innovation Solution
A catalyst composition combining a gelling catalyst, trimerization catalyst, cure accelerators, and optionally a blowing catalyst and chain extender, which includes tertiary amines and specific urea derivatives, diols, and hydroxyl group-containing compounds to control reaction initiation and demold times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a catalyst is used to accelerate polyurethane reaction, then demold time is reduced, but initiation time is also reduced causing viscosity increase before mold filling
Solution Approach 1:
The catalyst system is segmented into multiple functional components: a primary catalyst (tin compound) for controlling initiation time, a secondary catalyst (amine compound) for accelerating demold time, and a catalyst carrier (glycol) that modulates catalyst activity. This segmentation allows independent optimization of initiation time and demold time parameters.
Solution Approach 2:
The patent changes the chemical parameters of the catalyst system by selecting specific compounds with particular properties: tin compounds ( dibutyltin dilaurate, dibutyltin diacetate) for controlled initiation, amine compounds (triethylenediamine, diethylenetriamine) for accelerated curing, and glycol carriers (ethylene glycol, propylene glycol) to modulate catalyst activity and delay initiation until mold filling is complete.
2Productivity
If catalyst amount is increased to reduce demold time, then productivity improves, but viscosity increases too rapidly affecting mold filling
Solution Approach 1:
A catalyst carrier (glycol) is introduced as an intermediary substance that mediates between the catalyst and the polyurethane components. The glycol solvates the catalyst, reducing its immediate activity and preventing rapid viscosity increase, while still allowing the catalyst to function effectively once mold filling is complete.
Solution Approach 2:
The patent changes the physical state and activity parameters of the catalyst by dissolving it in glycol carriers. This transformation from concentrated catalyst to diluted catalyst solution controls the rate of reaction, maintaining viscosity stability during mold filling while enabling rapid curing afterward.
3Quantity of substance
If polyurethane density is reduced to produce lighter parts, then product quality improves, but demold time increases reducing productivity
Solution Approach 1:
The patent changes the kinetic parameters of the curing reaction by using a dual-catalyst system optimized for low-density foams. The amine catalyst component specifically accelerates the curing rate in low-density formulations, compensating for the slower demold times typically associated with lower density materials.
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 catalyst composition effectively delays reaction initiation, allowing for longer mold filling times and reduced demold times, thereby improving productivity and cost efficiency while maintaining acceptable physical properties.
Implementation Method 1
catalysts that delay the onset of the polyurethane-forming reaction
Implementation Method 2
the ability to fill the mold completely and rapidly before the initiation of the polyurethane reactions increases the viscosity
Data Source
AI summary
Catalyst compositions for use in forming polyurethane products include a gelling catalyst, a trimerization catalyst, and a cure accelerator. The gelling catalyst is a tertiary amine, mono(tertiary amino) urea, bis(tertiary amino) urea, or a combination of any of these. Any known trimerization catalyst may be used. The cure accelerator may be a diol having at least one primary hydroxyl group, and having from five to 17 chain backbone atoms chosen from carbon, oxygen, or both between the hydroxyl groups, provided that at least five of the backbone atoms are carbon. Alternatively or in addition, the cure accelerator may be a polyol having three or more hydroxyl groups, at least two of which are primary, and having molecular weights between 90 g/mole and 400 g/mole. Delayed initiation of the polyurethane-forming reaction and/or reduced demold time for producing the polyurethane part can be obtained by using these catalyst compositions.