Silane-Functional Polymer Composition for Low-Viscosity Fast Curing
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Solution Overview
Problem
Existing polymers containing silane groups require dilution with plasticizers or solvents to be handled efficiently at room temperature, and they have limitations in curing rate, strength, extensibility, and thermal stability, especially when used for sealing porous substrates or bonding plastics.
Innovation Solution
A polymer containing silane groups is produced by reacting a polymer with isocyanate groups, formed at an NCO/OH ratio of at least 3/1, with a majority of unconverted monomeric diisocyanate removed, and then reacted with amino-, mercapto-, or hydroxysilane in a stoichiometric ratio of at least 1/1, resulting in a low viscosity, high strength, and fast curing composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymers containing silane groups are prepared from polymers containing isocyanate groups with NCO/OH ratio of about 2/1, then mechanical properties such as strength and extensibility are improved, but viscosity becomes high requiring dilution with plasticizers
Solution Approach 1:
The patent changes the NCO/OH ratio parameter from the conventional 2/1 to at least 3/1, which fundamentally alters the polymer structure to reduce secondary constituents and chain-extension, thereby achieving low viscosity without plasticizers while maintaining mechanical properties
Solution Approach 2:
The patent extracts and removes the harmful secondary constituents (monomeric diisocyanate and chain-extended polymers) by adjusting the synthesis parameters, eliminating the need for plasticizer dilution and achieving both low viscosity and good mechanical properties
2Ease of operation
If polymers containing silane groups are diluted with plasticizers to improve flow properties, then handling efficiency is improved, but freedom in formulation is limited and substrate damage risk increases
Solution Approach 1:
By changing the NCO/OH ratio to at least 3/1, the patent achieves inherently low viscosity polymers that require no plasticizer dilution, thereby restoring complete formulation freedom and enabling use with sensitive substrates
Solution Approach 2:
The patent eliminates the need for plasticizers (temporary additives that may migrate and cause damage), using instead a fundamentally redesigned polymer structure that provides both processability and long-term stability without harmful constituents
3Strength
If polymers containing silane groups are prepared with conventional methods, then good mechanical properties are achieved, but curing rate and thermal stability are insufficient
Solution Approach 1:
The patent changes multiple parameters simultaneously: NCO/OH ratio (to at least 3/1), stoichiometric ratio of silane to isocyanate (at least 1/1), and removal of unconverted diisocyanate. These changes produce a polymer with optimized molecular structure that achieves both mechanical strength and superior thermal stability
Solution Approach 2:
The patent creates a composite molecular structure by reacting the modified isocyanate polymer with amino-/hydroxysilane in controlled ratios, producing a silane-functional polymer that combines the mechanical properties of polyether polyol with the thermal stability and crosslinking capability of silane groups
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 resulting polymer enables efficient handling without plasticizers or solvents, with rapid curing, high strength, and improved thermal stability, suitable for producing storage-stable sealants, adhesives, or coatings with enhanced extensibility.
Implementation Method 1
the polymer containing isocyanate groups... with an amino-, mercapto- or hydroxysilane... in a stoichiometric ratio of at least 1/1 in relation to the isocyanate groups
Implementation Method 2
moisture-curing adhesives, sealants or coatings
Implementation Method 3
moisture-curing adhesives, sealants or coatings
Data Source
AI summary
A silane group-containing polymer obtained from reacting (i) an isocyanate group-containing polymer having an NCO content in the range of 0.3 to 4% by weight and a monomeric diisocyanate content of at most 0.3 wt. % obtained from the reaction of at least one monomeric diisocyanate with at least one polyether polyol in a molar NCO/OH ratio of at least 3/1 and subsequent removal of a major part of the unreacted monomeric diisocyanates by means of a suitable separation process, (ii) with at least one amino-, mercapto- or hydroxysilane in a stoichiometric ratio of at least 1 mole of amino-, mercapto- or hydroxysilane per mole equivalent of isocyanate groups.