Two-Component Silicone Composition With Long Mixer Open Time
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing two-component silicone compositions face challenges with short pot life and mixer open time, leading to premature curing and increased cycle times, and require high catalyst concentrations that affect processability and mechanical properties.
Innovation Solution
A two-component silicone composition using a specific catalyst with two thiolate ligands and organosilanes as crosslinkers, allowing for long pot life and mixer open time, with adjustable mixing ratios and low VOC contamination, and achieving rapid curing after the end of the pot life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high catalyst concentration is used to achieve rapid curing, then curing speed is improved, but mixer open time is reduced and premature curing occurs
Solution Approach 1:
A silane-modified catalyst is used as an intermediary substance that carries the catalytic activity but requires interaction with water (from the polydiorganosiloxane component) to activate. This mediator approach allows the catalyst to remain dormant during storage and mixing, preventing premature curing while enabling rapid curing once the composition is applied and exposed to moisture.
Solution Approach 2:
The invention changes the chemical state of the catalyst by modifying it with silane groups, transforming it from a traditionally active catalyst to a water-activated catalyst. This parameter change in catalyst structure allows decoupling of curing speed from immediate reactivity, enabling long mixer open time while maintaining rapid curing capability when activated by water.
2Loss of time
If catalyst concentration is decreased to extend mixer open time, then mixer open time is improved, but curing time increases and pot life is extended
Solution Approach 1:
The silane-modified catalyst acts as a water-activated intermediary that remains inactive during storage and mixing but rapidly activates upon contact with water from the polydiorganosiloxane component. This allows the system to achieve both extended mixer open time (due to low initial activity) and rapid curing (due to high activated activity once water is present).
Solution Approach 2:
The catalyst is pre-modified with silane groups during manufacturing, but the actual catalytic action is postponed until the composition is applied and water is introduced. This preliminary preparation of the catalyst structure enables delayed activation, resolving the contradiction between extended open time and rapid curing.
3Productivity
If static mixer is used to mix components, then mixing efficiency is improved, but local overconcentration of catalyst occurs causing premature curing
Solution Approach 1:
The silane-modified catalyst serves as a water-activated intermediary that prevents direct, uncontrolled interaction between catalyst and polydiorganosiloxane during mixing. The catalyst remains dormant until water from the polydiorganosiloxane component is introduced, eliminating local overconcentration issues in the static mixer while maintaining efficient mixing.
Solution Approach 2:
The catalyst is pre-modified with silane groups that prevent premature catalytic activity. This preliminary protective measure counteracts the potential harmful effect of local catalyst overconcentration in the static mixer, allowing efficient mixing without risking premature curing.
4Stability of the object's composition
If 1:1 weight ratio of polydiorganosiloxane to catalyst-containing component is used, then composition balance is improved, but mixer open time is significantly reduced
Solution Approach 1:
The silane-modified catalyst acts as a water-activated intermediary that prevents immediate reaction upon mixing. Even at 1:1 weight ratio, the catalyst remains dormant during the mixing process and only activates after water exposure during application, thereby maintaining composition balance while preserving extended mixer open time.
Solution Approach 2:
The catalyst's chemical parameters are changed through silane modification, transforming it from a immediately active catalyst to a water-activated system. This parameter change allows the system to tolerate 1:1 composition ratios without suffering from significantly reduced mixer open time, as the catalyst activity is delayed until application.
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 composition provides unusually good storage stability, reduced phase separation, and excellent adhesion to various substrates, with pot lives of up to 30 minutes and mixer open times of 7-8 minutes, while curing 80% in 4 hours post-application.
Implementation Method 1
a catalyst and a crosslinker for the crosslinking of polydiorganosiloxanes
Implementation Method 2
at least one catalyst K for the crosslinking of polydiorganosiloxanes
Implementation Method 3
all organosilanes V preferably have the same hydrolyzable alkoxysilane groups
Data Source
AI summary
A two-component silicone composition including a component (A) including at least one hydroxyl-terminated polydiorganosiloxane (P); preferably at least one filler; between 0.05% and 5.0% by weight of emulsified water, based on component (A); and a component (B) including at least one noncondensable polydiorganosiloxane (W) as a plasticizer; at least one organosilane (V) as a crosslinker; at least one catalyst (K) for the crosslinking of polydiorganosiloxanes; wherein all organosilanes (V) preferably have the same hydrolyzable alkoxysilane groups, preferably methoxysilane groups; and catalyst (K) is a tin complex having two mercaptide ligands of formula (V), where ligands (L1) are each independently alkyl mercaptides coordinated via sulfur, especially C6 to C16 alkyl mercaptides, where ligands (L1) optionally have methyldialkoxysilane groups, preferably methyldimethoxysilane groups, and ligands (L2) are each independently alkyl ligands, especially C6 to C14 alkyl ligands; and component (B) contains less than 5% by weight of carbon black based on component (B).