Starch ether, as a modified starch, is widely used in gypsum adhesive to enhance its bonding properties, construction properties and final mechanical properties. Gypsum adhesive is a common building material used to bond and paste gypsum boards, decorative materials, etc. Adding starch ether to gypsum adhesive can significantly improve its processing and use performance.

(1) Characteristics of starch ether

Starch ether is a water-soluble polymer compound formed by chemical modification of natural starch. Common starch ethers include hydroxypropyl starch ether, carboxymethyl starch ether, ethylated starch ether, etc. These modified starches retain the basic skeleton of natural starch in structure, but improve solubility, rheology and stability by introducing ether groups or other functional groups.

Characteristics include:
Good thickening property: Starch ether has strong thickening ability and can effectively increase the viscosity of gypsum adhesive, thereby improving construction properties.
Water retention: It can provide a certain water retention capacity in the adhesive, prolong the operation time, and avoid cracking caused by excessive water loss.
Adhesion: Enhances the adhesion between gypsum adhesive and substrate, improving the bonding effect.
Flexible modification: The properties such as dissolution rate and viscosity characteristics can be customized by changing the chemical structure of starch.

(2) Mechanism of action of starch ether in gypsum adhesive

1. Thickening effect
After starch ether is dissolved in water, the polymer chain formed can capture and fix a large number of water molecules, thereby increasing the viscosity of the adhesive system. This thickening effect not only helps to improve the construction performance of gypsum adhesive, but also can prevent sagging to a certain extent, ensuring the uniformity and stability of the coating layer.

2. Water retention effect
The water retention property of starch ether allows gypsum adhesive to maintain appropriate moisture during construction, avoiding the problem of cracking caused by rapid evaporation of moisture. At the same time, good water retention property helps the curing process of gypsum adhesive, making the finished product more durable.

3. Improved construction performance
Through thickening and water retention, starch ether can significantly improve the construction performance of gypsum adhesive, such as increasing working time (opening time) and adjustment time, so that construction personnel can have more time to make adjustments and corrections. In addition, starch ether can improve the fluidity of coating, making it smoother and easier to apply, and reduce the occurrence of defects such as bubbles and sand holes.

4. Enhanced bonding performance
The presence of starch ether increases the intermolecular force between the adhesive and the substrate, thereby enhancing the bonding strength. This is particularly important for applications that require higher adhesion, such as gypsum board pasting and joint filling.

(3) Application effect of starch ether

1. Increase the viscosity of gypsum adhesive
Starch ether can significantly increase the viscosity of gypsum adhesive, thereby improving its construction performance. Appropriate viscosity can reduce sagging, improve the convenience of operation and the uniformity of coating.

2. Extended operation time
Through good water retention properties, starch ether can extend the operation time of gypsum adhesive, allowing construction workers to perform construction operations more calmly. Extended operation time can reduce the rework rate during construction and improve work efficiency.

3. Increased bonding strength
The addition of starch ether increases the final bonding strength of the adhesive, making the bonding effect more durable and stable. This is of great significance for high-load application scenarios, such as the fixing and joint filling of gypsum boards.

4. Improved fluidity and construction performance
The good rheological properties of starch ethers make gypsum adhesives have better fluidity and construction performance, which is easy to apply and smooth, reducing the difficulty and defects in construction.

(4) How to use starch ethers

1. Ratio requirements
The amount of starch ether added to gypsum adhesives is usually small, generally between 0.1% and 0.5% (mass fraction). The specific amount needs to be adjusted according to the formula, use environment and performance requirements of the gypsum adhesive. Excessive addition may cause excessive viscosity and affect construction operations.

2. Timing of addition
Starch ethers are usually added during the preparation of gypsum adhesives. They are usually added before mixing other powder materials or during the mixing process to ensure that they can be fully dissolved and evenly dispersed.

3. Mixing method
Starch ethers can be evenly mixed with other powder materials by mechanical stirring. In order to avoid agglomeration or caking, it is recommended to add gradually and stir thoroughly. For large-scale production, dedicated mixing equipment can be used to improve mixing uniformity and production efficiency.

(5) Use cases and precautions

Use cases
Gypsum board joint filler: By adding starch ether, the water retention performance of the filler is improved, cracking is avoided, and the bonding strength of the joint is enhanced.
Gypsum adhesive: Used for bonding gypsum boards and other building materials to improve construction performance and bonding strength.
Gypsum leveling material: Used for leveling construction of walls or floors to improve the leveling and adhesion of the coating.

Precautions
Dosage control: Reasonably control the amount of starch ether to avoid excessive viscosity or poor adhesive performance due to excessive dosage.
Environmental conditions: In high humidity or low temperature environments, the performance of starch ether may be affected to a certain extent, and the formula needs to be adjusted according to actual conditions.
Compatibility: Pay attention to compatibility with other additives to avoid adverse reactions.

The application of starch ether in gypsum adhesives, with its good thickening, water retention and improved construction performance characteristics, significantly improves the bonding performance and construction convenience of gypsum adhesives. Through reasonable use and proportioning, the overall performance of gypsum adhesive can be effectively improved to meet the needs of different construction projects. In the future, with the advancement of technology and changes in market demand, the application of starch ether in gypsum adhesive will continue to develop and play a greater role.