Cross-linked Amylopectin Starch for Cement Mortar Open Time
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Solution Overview
Problem
Existing starch-based additives for building materials extend the adhesive open time but delay setting, making it challenging to balance improved processing properties with reduced setting time while maintaining slip resistance and thickening effects.
Innovation Solution
A cold water-soluble, cross-linked starch derivative from amylopectin-rich starch, modified by hydroxypropylation with a degree of substitution of 0.1 to 0.8 and cross-linking at a specific molar ratio, is used to inhibit premature skin formation and achieve a short setting time while maintaining extended adhesive open time and slip resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If starch-based additives are added to extend adhesive open time, then slip resistance and workability are improved, but setting time is delayed
Solution Approach 1:
The patent applies parameter changes by carefully controlling the degree of substitution (DS) of the starch derivative between 0.05 and 0.2, and the cross-linking degree between 0.1 and 1.0. This optimization allows the additive to extend open time while minimizing setting delay, resolving the contradiction through precise parameter adjustment rather than qualitative change
Solution Approach 2:
The patent uses composite materials by combining starch derivatives with cross-linking agents to create a modified starch product with enhanced properties. This composite approach allows the material to simultaneously provide thickening, slip resistance, and extended open time while reducing setting delay compared to unmodified starch
2Ease of operation
If starch ethers are used to improve workability and slip resistance, then processing properties are enhanced, but setting behavior deteriorates
Solution Approach 1:
The patent resolves this contradiction through parameter changes by optimizing the degree of substitution and cross-linking degree within specific ranges. This allows the starch derivative to maintain excellent workability and slip resistance while achieving superior setting behavior compared to conventional starch ethers
Solution Approach 2:
The patent employs a starch derivative that acts as a temporary additive during the mixing and application process, then rapidly degrades or reacts to allow setting. This short-lived additive approach provides the needed workability enhancement without permanently interfering with the setting process
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
This approach allows for improved processing properties of cement mortars and adhesives with a short setting delay, maintaining adhesive open time, slip resistance, and thickening effect, unlike previous solutions that required a trade-off between these properties.
Implementation Method 1
the addition of water-soluble or water-swellable additives based on selected natural product derivatives and/or synthetic polymer compounds is known
Implementation Method 2
a 5% aqueous Brookfield viscosity of the pure starch derivative of 2000-7000 mPas at 100 rpm and 20°C
Implementation Method 3
amylopectin-rich starch with an amylopectin content of greater than 85%
Implementation Method 4
improves stability and processing properties and increases thickening
Implementation Method 5
increased slip resistance
Data Source
AI summary
The present invention relates to a construction material composition, comprising a cross-linked starch derivative of a starch that is rich in amylopectin and has an amylopectin content greater than 85%.