Water-Soluble Siloxane Defoamer for Concrete Mixtures
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Solution Overview
Problem
Existing defoamers used in building-product mixtures, such as concrete and mortar, often separate into phases when combined with superplasticizers, leading to air entrapment and reduced mechanical strength and weatherability, and there is a lack of water-soluble siloxane-based defoamers that are miscible with superplasticizers.
Innovation Solution
The use of water-soluble siloxanes with at least two different polyalkoxylene moieties that are compatible with superplasticizers, such as polycarboxylate ethers and sulphonates, to form stable compositions that prevent phase separation and enhance defoaming performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional defoamers are used in building-product mixtures with superplasticizers, then defoaming action is provided, but phase separation occurs between the polar superplasticizer and the apolar defoamer
Solution Approach 1:
The patent changes the chemical parameters of the defoamer by introducing polyalkoxylene moieties (ether groups) into the siloxane structure. This modification transforms the defoamer from being purely apolar to having amphiphilic character, enabling it to remain miscible with polar superplasticizers while maintaining defoaming effectiveness.
Solution Approach 2:
The patent creates a composite molecular structure combining siloxane units with polyalkoxylene chains. This composite approach allows the defoamer to exhibit both the defoaming properties of siloxanes and the water-solubility/miscibility of polyether compounds, preventing phase separation.
2Reliability
If water-insoluble defoamers are used, then defoaming performance is achieved, but uniform distribution in aqueous systems is prevented
Solution Approach 1:
The patent modifies the solubility parameters of the defoamer by incorporating hydrophilic polyalkoxylene groups. This change enables the defoamer to dissolve uniformly in aqueous building-product mixtures while retaining its air-removing capability.
3Ease of operation
If superplasticizers are added to building-product mixtures, then flowability and workability are improved, but air entrapment increases
Solution Approach 1:
The patent applies preliminary anti-action by adding the defoamer composition to the building-product mixture to counteract the air-entraining effect of superplasticizers. The defoamer prevents foam formation and air bubble stabilization that would otherwise occur with superplasticizer addition.
Data Source
AI summary
The present application relates to compositions comprising at least one siloxane and at least one superplasticizer based on polycarboxylate ethers or sulphonates of lignin, melamine or naphthalene or of resins thereof, and to the use of such compositions as or in building-product mixtures or building products, especially mortar mixtures or concrete mixtures. Preferably the siloxane is a branched siloxane containing at least one âTâ unit and containing at least two different polyoxyalkylene moieties.