Silane-Crosslinking Curable Compositions with Mixed Terminal Groups
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing adhesives and sealants face challenges in achieving a balance between high strength and elasticity, with isocyanate-free compositions requiring improved curing times, elasticity, and extensibility while avoiding residual tackiness.
Innovation Solution
Silane-crosslinking compositions utilizing polymers with two different dialkoxysilyl terminal groups, differing in aliphatic hydrocarbon bridges, which react to form curable compositions with enhanced elasticity, strength, and moderate curing times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crosslinking density is increased to achieve higher adhesive strength, then the strength is improved, but the elasticity decreases
Solution Approach 1:
The patent changes the chemical parameters of the silane groups (specifically using a mixture of dimethoxysilyl and diethoxysilyl groups with different hydrocarbon chain lengths) to optimize both strength and elasticity. The shorter hydrocarbon chain (K1) provides higher reactivity and crosslinking density for strength, while the longer hydrocarbon chain (K2) provides flexibility and elasticity, resolving the contradiction between these two properties.
Solution Approach 2:
The patent creates a composite system by combining polymers with different terminal silane groups (both dimethoxysilyl and diethoxysilyl) in a single composition. This composite approach allows the different silane types to contribute differently to the crosslinked network, with some providing strength and others providing elasticity, thereby achieving both properties simultaneously.
2Stability of the object's composition
If plasticizers are added to restore elasticity, then the elasticity is improved, but the plasticizer migration occurs and strength is impaired
Solution Approach 1:
Instead of adding plasticizers to restore elasticity, the patent changes the fundamental chemical parameters of the crosslinking system by using silane groups with different hydrocarbon chain lengths. This approach achieves elasticity through the molecular structure itself rather than through additive plasticizers, eliminating the problem of plasticizer migration while maintaining both strength and elasticity.
3Stability of the object's composition
If α-silane based dimethoxy compounds are used to achieve good elasticity, then the elasticity is improved, but the processing time becomes very short
Solution Approach 1:
The patent modifies the reactivity parameters of the silane system by introducing diethoxysilyl groups with longer hydrocarbon chains (K2) alongside the dimethoxysilyl groups. The diethoxysilyl groups with longer hydrocarbon chains provide a slower, more controlled reaction rate, which extends the processing time while the dimethoxysilyl groups maintain the elasticity, thus resolving the contradiction between elasticity and processing time.
4Ease of manufacture
If hydrosilylation process is used to manufacture mixed systems, then the composition is formed, but the reaction time is long and residual tackiness remains
Solution Approach 1:
The patent changes the hydrolyzable group parameters from the traditional hydrosilylation approach to using alkoxysilyl groups (dimethoxysilyl and diethoxysilyl) that can react directly with water or hydroxyl groups. This parameter change enables faster reaction kinetics while maintaining complete reaction of terminal groups, eliminating residual tackiness and reducing reaction time compared to conventional hydrosilylation processes.
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 compositions exhibit high elasticity, strength, and extensibility with adequate setting times, overcoming the limitations of previous isocyanate-free binding agents by providing improved processing and performance characteristics.
Implementation Method 1
silane-crosslinking curable compositions... polymers having at least two terminal groups of the following formulas (I) and (II)... X, Y, mutually independently, denote a hydroxy group or a hydrolyzable group
Implementation Method 2
In the presence of atmospheric moisture these alkoxysilane-terminated polymers are capable, even at room temperature, of condensing with one another with cleavage of the alkoxy groups
Data Source
AI summary
The present invention relates to silane-crosslinking curable compositions encompassing a polymer P having at least two terminal groups of the following formulas (I) and (II) -Am-K1—SiR1XY (I), -Am-K2—SiR2XY (II), and/or two polymers P1 and P2, polymer P1 having terminal groups of the following formula (I) -Am-K1—SiR1XY (I), and polymer P2 having terminal groups of the following formula (II) -Am-K2—SiR2XY (II), in which A denotes a divalent bonding group, K1, K2, mutually independently, denote a divalent aliphatic hydrocarbon group that has a main chain of 1 to 6 carbon atoms, the hydrocarbon groups K1, K2 being different, X, Y mutually independently denote a hydroxy group or a hydrolyzable group, R1, R2 mutually independently denote a hydrocarbon residue having 1 to 20 carbon atoms, and m assumes the values 0 or 1.