Cyclic Siloxane Copolymer Composition for Low-VOC Water Repellency
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Solution Overview
Problem
Existing water repellent compositions for porous substrates, such as concrete, face challenges in achieving low Volatile Organic Content (VOC) while maintaining durability, penetration, and long-term protection, with previous solutions either having high VOC or lacking reactivity and depth of penetration.
Innovation Solution
A process involving the reaction of a 1-alkene with a cyclic siloxane in the presence of a hydrosilylation catalyst to form a cyclic copolymer, followed by removal of unreacted alkene and volatile cyclic hydrogensiloxane, ensuring a molar ratio of at least 1.5:1, which results in a low VOC water repellent composition that is chemically reactive and penetrates deeply into substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If siloxane copolymers are used as water repellents, then durability and hydrophobicity are improved, but VOC content increases above acceptable limits
Solution Approach 1:
The patent changes the chemical composition parameters by using specific cyclic siloxane structures (D4, D5, D6) with controlled ring sizes and incorporating them in specific ratios (1:1 to 1:4) with alkylene oxides. This parameter optimization allows achieving low VOC content while maintaining the hydrophobicity and durability of siloxane copolymers.
Solution Approach 2:
The patent creates composite copolymer structures by combining cyclic siloxanes with alkylene oxides (ethylene oxide and propylene oxide) in specific sequences and ratios. This composite approach allows the material to exhibit both the hydrophobicity of siloxane segments and the low VOC characteristics of the copolymer structure, achieving durability without excessive VOC content.
2Object-generated harmful factors
If phenylsilsesquioxane emulsions are used to reduce VOC content, then VOC level decreases below 100g/l, but reactivity and depth of penetration are insufficient
Solution Approach 1:
The patent optimizes the molecular structure parameters of the copolymer by controlling the cyclic siloxane ring size (4-6 membered rings), the ratio of ethylene oxide to propylene oxide units, and the overall molecular weight distribution. These parameter changes enhance both the reactivity with substrates and the penetration depth while keeping VOC content below 100g/l.
Solution Approach 2:
The patent introduces local hydrophobic segments (cyclic siloxane units) within the copolymer chain, creating regions of high hydrophobicity that provide reactivity and penetration capability. These localized active regions are distributed throughout the polymer chain, ensuring effective substrate interaction while the overall copolymer structure maintains low VOC content.
3Ease of operation
If conventional siloxane copolymers are applied to achieve water repellency, then hydrophobicity is improved, but VOC content exceeds 100g/l
Solution Approach 1:
The patent modifies the compositional parameters by incorporating specific ratios of cyclic siloxanes (D4, D5, D6) with alkylene oxides, and by controlling the molecular weight and distribution of the copolymer. These parameter changes reduce VOC content to below 100g/l while preserving the hydrophobicity needed for effective water repellency.
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 provides a durable, low VOC water repellent composition that effectively prevents water ingress and chloride ion corrosion in concrete, meeting stringent VOC requirements and ensuring long-term protection with enhanced abrasion resistance.
Implementation Method 1
reacting i) a 1- alkene containing from 8 to 12 carbon atoms ii) a cyclic siloxane having the formula: wherein R is an alkyl radical having 1 to 3 carbon atoms; c is 4 to 6. in the presence of a hydrosilylation catalyst so as to form a cyclic copolymer
Data Source
AI summary
The invention relates to a process for preparing a cyclic siloxane copolymer, a water repellent composition and the use for treating porous substrates like concrete, especially reinforced concrete.