Curable Silicone Compositions with Platinum Phosphite Catalyst
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Solution Overview
Problem
Existing one-component addition-curing silicone compositions face challenges with premature crosslinking at room temperature and limited pot life due to the use of platinum catalysts, leading to increased cleaning efforts and risk of contamination, and current inhibitors either extend pot life at the cost of reduced reactivity at elevated temperatures or are volatile, with no known solutions providing complete inhibition at room temperature and no influence on curing conditions.
Innovation Solution
The development of silicone compositions using a platinum catalyst with a specific formula, Pt[P(OR2)3]2, which allows for improved crosslinking properties, including extended pot life and rapid curing at elevated temperatures without the drawbacks of existing systems, by incorporating Pt(II) phosphite complexes as the central metal and phosphorus in the oxidation state +III, enabling the use of one- or two-component systems with enhanced stability and reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If platinum catalysts are used in two-component systems, then crosslinking reaction occurs at room temperature, but pot life becomes very limited
Solution Approach 1:
An inhibitor substance is introduced as an intermediary that temporarily deactivates the platinum catalyst at room temperature, preventing premature crosslinking. The inhibitor acts as a mediator between the catalyst and substrate, blocking the catalytic activity until processing occurs at elevated temperatures where the inhibitor decomposes or becomes less effective, allowing the catalyst to then promote rapid crosslinking.
2Duration of action of moving object
If inhibitors are added to extend pot life, then crosslinking reaction is suppressed at room temperature, but reactivity at elevated temperatures decreases and light-off temperature increases
Solution Approach 1:
The inhibitor substance is selected and dosed to achieve complete suppression of catalytic activity at room temperature (0% conversion) while ensuring no inhibition effect at curing temperatures (100% reactivity). This parameter optimization allows the system to transition from complete inhibition at low temperature to complete activity at high temperature, resolving the trade-off between pot life extension and curing speed.
3Ease of operation
If one-component systems are used to eliminate mixing steps, then processing simplicity improves, but premature crosslinking at room temperature occurs
Solution Approach 1:
The inhibitor substance is pre-added to the one-component system to preliminarily counteract the catalytic activity of the platinum catalyst at room temperature. This preliminary anti-action prevents premature crosslinking during storage and handling, while the inhibitor is designed to become inactive at processing temperatures, allowing crosslinking to proceed when needed.
4Stability of the object's composition
If volatile inhibitors are used to extend pot life, then storage stability improves, but harmful volatile components are released
Solution Approach 1:
The inhibitor substance is selected as a non-volatile, stable compound that remains in the system throughout processing and provides continuous inhibition at room temperature without releasing harmful volatile components. The inhibitor is consumed or deactivated during the curing process, providing a disposable function of temporary catalyst deactivation.
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 silicone compositions exhibit improved pot life and crosslinking speed, maintaining reactivity at elevated temperatures while avoiding the disadvantages of premature crosslinking at room temperature, with the platinum catalyst ensuring efficient and controlled curing processes.
Implementation Method 1
a catalyst is generally used, which typically contains platinum or a metal from the platinum group. In the catalytic reaction, aliphatic unsaturated groups are reacted with Si-bonded hydrogen to form network structures
Implementation Method 2
addition-curing silicone compositions by the hydrosilylation reaction
Data Source
AI summary
The present invention relates to thermally crosslinkable silicon compositions by hydrosilylation, processes for their production, platinum catalysts used therefor, and the use of the crosslinkable compositions.