Polysiloxane Hardener Mixture for Coatings
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Solution Overview
Problem
Current hardener compositions for room temperature-curing coatings often suffer from phase separation during storage, leading to inhomogeneity and reduced storage stability, which complicates their use and application.
Innovation Solution
A hardener mixture comprising 10-60% polysiloxane, 40-90% amino-functional alkoxysilane, and 1-10% guanidine compound, which remains homogeneous during storage and prevents skin formation when exposed to atmospheric moisture, allowing for the use of leftover mixtures even after the container has been opened.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If hardener compositions contain silicone polymers as extenders, then rheological stabilization is achieved, but phase separation occurs during storage
Solution Approach 1:
The patent changes the chemical parameters of the polysiloxane component by introducing specific functional groups (vinyl, trimethylsilyl, or hydroxyl) and controlling the molecular weight and alkoxy content. This parameter optimization improves compatibility with amino-functional alkoxysilane, preventing phase separation while maintaining rheological stabilization.
Solution Approach 2:
The patent creates a composite hardener composition by combining specifically selected polysiloxane components with amino-functional alkoxysilane and catalyst. This composite approach ensures mutual compatibility between components, achieving both rheological stability and storage stability without phase separation.
2Reliability
If amino-functional alkoxysilanes are used as crosslinkers, then adhesion and crosslinking properties are improved, but moisture absorption occurs affecting storage
Solution Approach 1:
The patent introduces a specifically selected polysiloxane component as an intermediary substance that modifies the interaction between amino-functional alkoxysilane and atmospheric moisture. This polysiloxane acts as a buffer, controlling the hydrolysis rate and preventing excessive moisture absorption during storage while maintaining crosslinking reliability.
Solution Approach 2:
The patent optimizes the alkoxy content and molecular weight of the polysiloxane to control the overall moisture sensitivity of the hardener composition. By adjusting these parameters, the composition maintains sufficient reactivity for crosslinking while reducing unwanted moisture absorption during storage.
3Productivity
If hardener compositions are formulated with high concentrations of crosslinkers and adhesion promoters, then curing performance is improved, but phase separation is exacerbated
Solution Approach 1:
The patent optimizes the concentration ratios and molecular characteristics of all components to achieve high curing efficiency while maintaining homogeneity. Specifically, it selects polysiloxane with appropriate viscosity and functional group content that is compatible with high concentrations of amino-functional alkoxysilane, preventing phase separation even at elevated crosslinker levels.
Solution Approach 2:
The patent develops a multi-component composite system where polysiloxane, amino-functional alkoxysilane, and catalyst work synergistically. This composite formulation allows high concentrations of reactive components to be used together without causing phase separation, as the polysiloxane matrix provides compatibility and stabilization.
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 hardener mixture maintains stability and prevents phase separation, ensuring consistent performance and extended storage life without the need for additional chemical reactions, allowing for efficient curing and application of coatings.
Implementation Method 1
In the presence of atmospheric moisture or through the addition of water, the alkoxy substituents of the trialkoxysilane are first hydrolyzed, forming the corresponding silanols
Implementation Method 2
These silanol groups can then react with hydroxyl groups on the surface of the material to be modified, releasing water, and crosslink via further silanol groups to form siloxane units
Implementation Method 3
Catalysts are often used to accelerate such crosslinking reactions
Data Source
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AI summary
The invention relates to a hardener mixture for room temperature curing coatings comprising (A) 10-60 wt.%, preferably 20-60 wt.%, particularly preferably 30-50 wt.% of a polysiloxane, (B) 40-90 wt.%, preferably 40-80 wt.%, particularly preferably 40-70 wt.% of an amino-functional alkoxysilane and (C) 1-10 wt.%, preferably 2-7 wt.%, particularly preferably 3-5 wt.% of a guanidine compound, wherein the quantities of components (A), (B) and (C) add up to 100 wt.% and refer to the hardener mixture.