Gypsum Accelerator Starch Coating Hydration Control
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Solution Overview
Problem
Conventional gypsum accelerator materials lose effectiveness over time, especially when exposed to heat and moisture, leading to reduced efficiency and increased costs, making them unsuitable for long-term storage and transportation, and compromising the strength of ultra-lightweight gypsum boards.
Innovation Solution
A novel accelerator material comprising calcium sulfate dihydrate particles and soluble starch with high cold-water solubility and low viscosity, which is heat-resistant and maintains efficiency even after prolonged storage, allowing for modulation of hydration rates in gypsum board production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional gypsum accelerator materials (calcium sulfate dihydrate particles) are used, then the hydration rate of calcined gypsum is accelerated, but the accelerator loses effectiveness over time when exposed to heat and moisture
Solution Approach 1:
The patent combines calcium sulfate dihydrate particles with a specific coating composition comprising 5-20 parts by weight of starch and 80-95 parts by weight of calcium sulfate dihydrate per 100 parts of calcium sulfate dihydrate particles. This composite structure allows the accelerator to maintain its effectiveness during storage and transportation while still providing rapid hydration acceleration when applied to calcined gypsum.
Solution Approach 2:
The starch coating acts as an intermediary layer on the calcium sulfate dihydrate particles. This coating prevents direct contact between the accelerator particles and moisture during storage, thereby preventing premature hydration and maintaining accelerator effectiveness. When applied to calcined gypsum, the coating allows sufficient calcium sulfate dihydrate to contact the gypsum surface to accelerate hydration.
2Ease of manufacture
If accelerator materials are stored for long periods or transported over long distances, then production flexibility and cost are improved, but the accelerator efficiency is dramatically reduced
Solution Approach 1:
The coated accelerator composition creates a stable composite material that can be stored for extended periods without significant loss of effectiveness. The starch coating protects the calcium sulfate dihydrate particles from moisture during storage and transportation, enabling the accelerator to maintain its productivity-enhancing properties even after long-term storage or distant transportation.
3Temperature
If conventional accelerator coatings (sugars, starch, boric acid, fatty carboxylic acids) are used, then heat resistance is improved, but the accelerator particles agglomerate and lose efficiency upon contact with moisture
Solution Approach 1:
The patent specifies precise parameter ranges for the coating composition: 5-20 parts by weight of starch and 80-95 parts by weight of calcium sulfate dihydrate per 100 parts of calcium sulfate dihydrate particles. These controlled parameters ensure the coating provides sufficient heat resistance while maintaining particle dispersion stability when moisture is present, preventing agglomeration and efficiency loss.
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 use of soluble starch with calcium sulfate dihydrate particles in the accelerator ensures prolonged effectiveness, reduces production costs, and enhances the nail pull resistance and strength of ultra-lightweight gypsum boards, enabling longer storage and transportation without compromising board quality.
Implementation Method 1
the accelerator material includes particles of calcium sulfate dihydrate and a soluble starch having a cold water solubility of at least about 25% and a viscosity of about 25 Brabender Units (BU) or less when the starch is in a 30% aqueous slurry at 92° C.
Implementation Method 2
The gypsum particles are believed to enhance nucleation of the set gypsum crystals, thereby increasing the crystallization rate thereof.
Implementation Method 3
the stucco, water, and other ingredients as appropriate are mixed... to form set gypsum by reaction of the calcined gypsum with water to form a matrix of crystalline hydrated gypsum
Data Source
AI summary
An accelerator for accelerating the rate of hydration of calcined gypsum is disclosed. The accelerator comprises calcium sulfate dihydrate particles and a starch. The starch has a cold water solubility of at least about 25% (e.g., at least about 35%) and a viscosity of about 25 Brabender Units (BU) or less when the starch is in a 30% aqueous slurry at 92° C. Also disclosed are a method of preparing an accelerator, method of hydrating stucco to form set gypsum, slurry, and method of making gypsum board.