High-Viscosity Organopolysiloxane Emulsion via Polyaddition
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Solution Overview
Problem
Current methods for preparing highly viscous organopolysiloxanes are limited by slow and incomplete condensation reactions, high temperatures, and the need for metal catalysts, which result in unstable products and restricted viscosity levels, making it difficult to achieve emulsions with viscosities above 50,000 mPa·s at 25° C.
Innovation Solution
A process involving the reaction of siloxanes with Si—C-bonded radicals and silanes in a dispersion medium, preferably water, in the presence of emulsifiers, without metal catalysts, to produce stable highly viscous organopolysiloxanes with viscosities up to 50,000,000 mPa·s at 25° C., using specific monovalent and alkyl radicals, and optionally substituted hydrocarbon groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If condensation reactions are used to prepare highly viscous polysiloxanes, then viscosity increases, but the reaction proceeds slowly and incompletely
Solution Approach 1:
The patent changes the reaction parameters by using polyaddition reactions instead of condensation reactions, allowing the process to proceed at lower temperatures (below 100°C) while achieving complete conversion and high viscosity products without the slow and incomplete reaction characteristics of traditional condensation methods
2Productivity
If relatively high temperatures are used to achieve acceptable conversion rates, then reaction completeness improves, but product stability deteriorates
Solution Approach 1:
The patent changes the thermal parameters by conducting polyaddition reactions at moderate temperatures below 100°C, which maintains product stability while achieving complete conversion through the inherent reactivity of the silane and siloxane components, eliminating the need for high-temperature processing
3Productivity
If metal catalysts are used to accelerate polyaddition reactions, then reaction rate increases, but product stability and purity deteriorate
Solution Approach 1:
The patent extracts and eliminates metal catalysts from the polyaddition process by utilizing uncatalysed spontaneous polyaddition reactions between silane and siloxane components, which proceed at acceptable rates without introducing metal contaminants that would compromise product stability and purity
Solution Approach 2:
The patent enables the reaction system to self-catalyze the polyaddition process through the inherent reactivity of the silane and siloxane functional groups, eliminating the need for external metal catalysts while maintaining efficient reaction progression and product quality
4Ease of operation
If mechanical emulsification is used for highly viscous organopolysiloxanes, then emulsion formation is achieved, but viscosity is limited to below 50,000 mPa·s
Solution Approach 1:
The patent performs preliminary polyaddition reactions to synthesize highly viscous organopolysiloxanes with viscosities exceeding 50,000 mPa·s before emulsification, then incorporates these pre-formed high-viscosity materials into emulsion systems where they serve as functional additives rather than requiring emulsification of the base polymer
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 process allows for the preparation of stable, highly viscous organopolysiloxanes with increased viscosity, exceeding previous limitations, and avoids the use of metal catalysts, achieving viscosities suitable for industrial applications while maintaining product stability across moderate thermal conditions.
Implementation Method 1
highly viscous organopolysiloxanes are obtained by polyaddition reactions
Implementation Method 2
a standard method is to prepare silanol-functional highly viscous polysiloxanes from low-viscosity hydrolysates of the chlorosilanes, usually dimethyldichlorosilane, by condensing them to form water
Implementation Method 3
The invention further relates to emulsions of highly viscous organopolysiloxanes
Implementation Method 4
in the presence of emulsifiers
Data Source
AI summary
Emulsions of highly viscous organopolysiloxanes are prepared by reacting organopolysiloxanes having at least one Si—OH group with alkoxysilanes bearing a group BReSi(OR3)3-e wherein R is a hydrocarbon radical and B is a radical —CR22—Y where Y is halogen, monosubstituted O or S or substituted N or P, the reaction taking place as a dispersion in water, optionally in the presence of an emulsifier.