Polyether Carrier Fluid Stabilizes Catalyst Package
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Solution Overview
Problem
Two-part moisture cure organopolysiloxane compositions face issues with phase separation during storage, which affects the stability and usability of the catalyst package, leading to reduced productivity and safety concerns due to flammable catalysts, and fast curing rates that limit tooling time and adhesion development.
Innovation Solution
A two-part moisture curing silicone composition using a carrier fluid of linear or branched polyethers with specific terminal groups, combined with non-dipodal aminosilanes, tin-based catalysts, and fillers, to create a shelf-stable continuous phase that prevents phase separation and maintains adhesion and cure speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional carrier fluids (trimethylsiloxy-terminated polydimethylsiloxane) are used in catalyst packages, then the catalyst package can be formulated, but phase separation occurs during storage reducing stability
Solution Approach 1:
The patent changes the chemical parameters of the carrier fluid by using polyether carrier fluids with specific molecular weights (200-750,000 g/mol) and viscosity ranges (5-50,000 mPa·s) instead of conventional polydimethylsiloxane carrier fluids. This parameter change prevents phase separation while maintaining catalyst package stability during storage.
Solution Approach 2:
The patent creates a composite catalyst package system by combining polyether carrier fluids with specific aminosilanes (non-dipodal structures), tin catalysts, and fillers. This composite formulation ensures compatibility between all components, preventing phase separation while maintaining functionality.
2Productivity
If tin catalyst and aminosilane levels are increased to achieve faster bulk durometer build, then substrates can be moved sooner, but tooling time and tack-free time are reduced
Solution Approach 1:
The patent optimizes the concentration parameters of catalysts and aminosilanes within specific ranges (0.01-3 wt% tin catalyst, 5-25 wt% aminosilane) rather than simply increasing them. This allows achieving fast bulk durometer build while maintaining adequate tooling time through precise parameter control.
Solution Approach 2:
The polyether carrier fluid acts as an intermediary that modulates the interaction between tin catalyst and aminosilane, enabling controlled cure kinetics. This intermediary effect allows the system to achieve fast bulk durometer build without excessively reducing tooling time.
3Reliability
If high concentrations of primary amine and tin catalyst are used in catalyst package, then adequate curing functionality is achieved, but random chain scission of carrier fluid occurs reducing viscosity and increasing particle settling
Solution Approach 1:
The patent changes the chemical structure parameters of the carrier fluid from polydimethylsiloxane to polyether structures with specific molecular weights and viscosities. These parameter changes make the carrier fluid resistant to chain scission by high concentrations of catalysts and aminosilanes, maintaining viscosity stability.
Solution Approach 2:
The patent selects polyether carrier fluids that are inherently more resistant to degradation by catalysts compared to conventional carrier fluids. This selection criterion ensures the carrier fluid maintains its properties throughout the catalyst package shelf life without requiring additional protective measures.
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 solution provides improved storage stability, faster bulk durometer build, and maintained adhesion properties without sacrificing cure speed, reducing the need for additional catalysts or aminosilanes, thus enhancing productivity and safety.
Implementation Method 1
the catalyst package, despite comprising amino silane(s), alkoxy silane(s), tin catalyst(s) and optionally reinforcing filler(s) and/or extending filler(s) in a carrier fluid, undergoes minimal phase separation during storage, by utilizing a silane end-capped polyether as the carrier fluid, enabling the catalyst package to be stored and function as a shelf stable continuous phase
Implementation Method 2
Condensation curable organosiloxane compositions, which cure to elastomeric solids
Implementation Method 3
Two-part moisture cure organopolysiloxane compositions
Implementation Method 4
a second part (catalyst or cure package) containing an alkyl-terminated diorganopolysiloxane, tin based catalyst, cross-linker and aminosilane
Implementation Method 5
curing proceeds via a bulk cure mechanism wherein the composition will cure simultaneously throughout the material bulk
Data Source
AI summary
A two-part moisture cure organopolysiloxane composition comprising a base part and a catalyst package part is provided. The catalyst package part undergoes minimal phase separation during storage despite comprising amino silane(s), alkoxy silane(s), and tin catalyst(s) and optionally reinforcing filler(s) and/or extending filler(s). This is given by the utilization of one or more linear or branched polyethers as a carrier fluid thereby enabling the catalyst package part to function as a shelf stable continuous phase.