Curable Composition Low Modulus High Elongation Sealing
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Solution Overview
Problem
Existing curable compositions for building sealing materials face challenges in achieving low viscosity, low modulus, and high elongation while maintaining workability and weather resistance, often resulting in reduced performance due to increased viscosity and surface stickiness issues.
Innovation Solution
A curable composition comprising a combination of organic polymers with specific reactive silyl group content and molecular weight ratios, specifically using a polyoxyalkylene polymer with at least 1.4 reactive silyl groups per molecule and another with less than 1 reactive silyl group per molecule, along with a phthalic acid ester plasticizer, to optimize the ratio of moles and molecular weights for improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number of silyl groups in each molecule of the reactive silyl group-containing organic polymer is reduced to achieve low modulus and high elongation, then the physical properties of the cured product improve, but the residual tack (surface stickiness) worsens
Solution Approach 1:
The patent applies parameter changes by precisely controlling the number of silyl groups per molecule within a specific range (0.95-1.05) and adjusting the molecular weight to a specific range (5,000-15,000). This optimized parameter combination allows the cured product to achieve both low modulus/high elongation and reduced residual tack, resolving the contradiction between physical properties and surface quality
Solution Approach 2:
The patent creates a composite system by combining the reactive silyl group-containing organic polymer with specific additives including silane coupling agents, fillers, and plasticizers. This composite approach allows the polymer matrix to achieve optimal mechanical properties while the additives help control surface characteristics and reduce residual tack
2Strength
If the molecular weight of the organic polymer is increased to maintain low modulus and high elongation, then the physical properties improve, but the viscosity of the curable composition increases causing poor workability
Solution Approach 1:
The patent optimizes the molecular weight parameter to a specific range (5,000-15,000) which is high enough to provide the desired low modulus and high elongation properties, but not so high as to cause excessive viscosity. This precise parameter control resolves the contradiction between mechanical properties and workability
Solution Approach 2:
The patent introduces silane coupling agents and other additives as intermediaries that modify the relationship between polymer molecular weight and viscosity. These additives allow the system to maintain higher molecular weights for better mechanical properties while keeping the curable composition sufficiently fluid for good workability
3Strength
If the amount of plasticizer is increased to achieve low modulus and high elongation, then the physical properties of the cured product improve, but the weather resistance reduces
Solution Approach 1:
The patent optimizes the plasticizer content to a specific range that provides sufficient flexibility for low modulus and high elongation, while avoiding excessive plasticizer that would compromise weather resistance. This balanced parameter selection resolves the contradiction between mechanical properties and durability
Solution Approach 2:
The patent uses a composite approach by combining moderate amounts of weather-resistant plasticizers with silane coupling agents and UV stabilizers. This composite system allows the plasticizer to provide the necessary flexibility while the other components protect against weathering, resolving the contradiction between mechanical properties and weather resistance
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 solution achieves a curable composition with low viscosity, low modulus, and high elongation, suitable for building sealing materials, while maintaining good workability and weather resistance, effectively addressing the limitations of previous compositions.
Implementation Method 1
it is cross-linked by siloxane bond formation involving hydrolysis or other reactions of the reactive silyl group
Implementation Method 2
siloxane bond formation involving hydrolysis or other reactions of the reactive silyl group
Data Source
AI summary
Provided is a curable composition that has low modulus, high elongation and low viscosity, and can be used for building sealing materials. This curable composition includes: an organic polymer (A) containing on average at least 1.4 reactive silyl groups per molecule; and an organic polymer (B) containing on average less than one reactive silyl group per molecule, wherein the number average molecular weight of component (B) is lower than the number average molecular weight of component (A) by at least 3,000, and the ratio (y)/(x) of the number of moles (y) of organic polymers containing only one reactive silyl group per molecule among components (A) and (B) to the number of moles (x) of organic polymers containing at least 2 reactive silyl groups per molecule among components (A) and (B) is not more than 5.