Bismuth and Amine Catalyst System for Polyurethane Crosslinking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalytic compositions for polyurethane binders in composite propellants do not allow for rapid crosslinking at room temperature, which is necessary for industrial logistics and production rates, and increasing catalyst content leads to adverse impacts on mechanical properties and chemical incompatibilities.
Innovation Solution
A catalytic composition comprising a bismuth organic salt catalyst, a basic tertiary amine catalyst, and an unblocked difunctional aliphatic isocyanate is used for room-temperature crosslinking, allowing synergistic effects and modulation of crosslinking kinetics without significant increases in catalyst content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalytic compositions (DBTDL or TPB) are used for polyurethane crosslinking, then crosslinking can proceed at elevated temperatures (40-65°C), but the process requires excessively long cooking times (7-20 days) and does not achieve sufficiently rapid crosslinking compatible with room temperature and industrial logistics constraints
Solution Approach 1:
The patent changes the chemical parameters of the catalytic system by replacing conventional catalysts (DBTDL, TPB) with a new composition based on bismuth organic salt and a specific tertiary amine catalyst. This parameter change enables the crosslinking reaction to proceed rapidly at room temperature (20-25°C) without requiring extended cooking times, thus resolving the contradiction between crosslinking speed and cooking time.
Solution Approach 2:
The patent employs a composite catalytic system combining bismuth organic salt and a tertiary amine catalyst in specific proportions. This composite catalyst formulation synergistically accelerates the crosslinking reaction at room temperature, achieving rapid curing compatible with industrial logistics while eliminating the need for prolonged elevated temperature treatment.
2Productivity
If catalyst content is increased to accelerate crosslinking, then crosslinking speed improves, but mechanical properties deteriorate and chemical incompatibilities arise with ammonium perchlorate
Solution Approach 1:
The patent optimizes the concentration parameters of the catalytic system, using bismuth organic salt at 0.01-0.1 wt% and tertiary amine catalyst at 0.1-1.0 wt% of the total formulation. This precise parameter optimization achieves rapid room-temperature crosslinking while maintaining mechanical properties and chemical compatibility with ammonium perchlorate, avoiding the detrimental effects of excessive catalyst content.
Solution Approach 2:
The patent selects bismuth organic salt as the catalyst, which offers sufficient catalytic activity at very low concentrations (0.01-0.1 wt%), minimizing the amount of catalyst needed. This approach avoids the accumulation of large catalyst quantities that would compromise mechanical properties and chemical compatibility, while still achieving the desired rapid crosslinking speed.
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
Achieves crosslinking kinetics at room temperature comparable to higher temperatures, reducing toxicity and maintaining mechanical properties by using a mixed catalytic system that minimizes amine catalyst impact and avoids chemical incompatibilities.
Implementation Method 1
The invention relates to a catalytic composition for the room-temperature crosslinking of polyurethane binders... comprising: a bismuth organic salt catalyst; a basic tertiary amine catalyst
Implementation Method 2
The urethane function results from the condensation reaction between a mobile hydrogen compound of the alcohol type R-OH and an isocyanate R'-N=C=O... These reactions are generally exothermic
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to the crosslinking of polyurethane binders and concerns a catalytic composition for room-temperature crosslinking of polyurethane binders. According to the invention, the catalytic composition comprises: a. A bismuth organic salt catalyst, preferably bismuth neodecanoate; b. A basic tertiary amine catalyst, preferably DMP30; c. An unblocked difunctional aliphatic isocyanate, preferably IPDI.