Silane-Capped Curable Compositions Balancing Adhesion and Storage Stability
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Solution Overview
Problem
Existing curable compositions based on polyorganosiloxanes suffer from poor adhesion to certain substrates and inadequate storage stability, particularly in the presence of curing catalysts and adhesion promoters.
Innovation Solution
The use of curable compositions comprising polyorganosiloxanes endcapped with specific silane groups, such as hydroxycarboxylic acid esters or amides, combined with a nitrogen-containing adhesion promoter, provides excellent storage stability and good adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional adhesion promoters are used to improve adhesion to substrates, then adhesion properties are enhanced, but storage stability deteriorates
Solution Approach 1:
The adhesion promoter is pre-reacted with the polyorganosiloxane during polymerization to form a modified polymer with integrated adhesion promoter groups. This preliminary action ensures the adhesion promoter is already incorporated into the polymer structure before storage or application, eliminating the need for separate adhesion promoter addition that would compromise storage stability.
Solution Approach 2:
The invention merges the adhesion promoter function with the polymer backbone by covalently bonding adhesion promoter groups to the polyorganosiloxane chains. This combining creates a unified structure where the adhesion promoter and polymer are inseparable, ensuring both stable storage and effective adhesion without the complications of separate components.
2Productivity
If curing catalysts are added to accelerate curing, then curing speed is improved, but storage stability deteriorates
Solution Approach 1:
The invention uses a two-component system where the polyorganosiloxane contains integrated adhesion promoter groups and crosslinking functionality, acting as an intermediary that eliminates the need for separate curing catalysts. The polymer itself contains all necessary functional groups to cure without additional catalysts, thereby maintaining storage stability while achieving acceptable curing speeds under ambient conditions.
Solution Approach 2:
The invention extracts the curing catalyst from the formulation entirely, relying instead on the inherent reactivity of the silane groups and atmospheric moisture to drive the curing reaction. This removal of the catalyst component eliminates the storage stability issues associated with catalyst-polymer interactions while still enabling curing.
3Adaptability or versatility
If multiple functional groups are incorporated to enhance adhesion profile, then adhesion to various substrates is improved, but formulation complexity increases
Solution Approach 1:
The invention incorporates multiple types of adhesion promoter groups (such as amino, epoxy, carboxyl, or hydroxyl groups) directly onto the polyorganosiloxane backbone, creating a universal adhesive that can bond to multiple substrate types including metals, plastics, glass, and ceramics. This multi-functional polymer eliminates the need for separate adhesion promoters for different substrates, simplifying the overall formulation while maintaining broad adhesion versatility.
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 combination ensures high storage stability and reliable curing at room temperature, even in the presence of atmospheric moisture, while maintaining good adhesion to various substrates.
Implementation Method 1
In the presence of atmospheric moisture these alkoxysilane-terminated polymers are able to condense with elimination of the alkoxy groups
Implementation Method 2
these can be differentiated into acidic, basic, and neutral crosslinkers based on the type of leaving groups released during hydrolysis
Data Source
AI summary
The invention relates to curable compositions based on curable polymers containing a special capped adhesion promoter, and optionally a curing catalyst. These compositions have improved adhesion properties and excellent storage stability. The invention also relates to the uses thereof.