Views: 0 Author: Site Editor Publish Time: 2025-11-20 Origin: Site
CMC/HPMC construction chemical powder is our best-selling product, inexpensive and high-quality. It can be used as a chemical additive in construction. Shijiazhuang Cellulose Co., Ltd., a cellulose manufacturer from China, can provide you with ample supply.
I. The Core Role of Pregelatinized Starch
Pregelatinized starch plays several key roles in mortar and putty powder:
1. Core Binding and Anti-dusting: Pregelatinized starch primarily functions as a binder in putty powder, effectively preventing dusting and powdering after the putty layer dries. When dissolved in water, it forms a three-dimensional network structure, tightly binding filler particles together.
2. Improved Application Texture: Appropriate addition significantly improves the smoothness of putty application, making it easier and less labor-intensive. Through synergistic effects with other additives (such as hydroxypropyl methylcellulose (HPMC), it can optimize application performance.
3. Auxiliary Thickening and Water Retention: Pregelatinized starch solutions have excellent thickening effects, which helps improve the suspension and stability of the putty slurry, preventing excessively rapid sedimentation and separation of solid materials. It also has a certain water retention effect, delaying moisture evaporation and providing better conditions for the bonding reaction.
4. Improved anti-slip properties: Pregelatinized starch helps improve the anti-slip properties (anti-sagging) of materials, making it less likely for putty to sag when applied to vertical walls, and making it easier to level thicker coatings.
II. Formulation and Mixing in Application
1. Sample Formulation:
Interior Wall Putty: Approximately 5-6 kg of pregelatinized starch and about 3 kg of hydroxypropyl methylcellulose (HPMC) can be added to about 1000 kg of heavy calcium carbonate (double-flying powder). (If using carboxymethyl cellulose (CMC), the dosage is approximately 8-10 kg.)
Exterior Wall Putty: In addition to aggregates such as stone powder and heavy calcium carbonate, cement is usually added. The amount of pregelatinized starch added can also be referenced at a ratio of 5-6 kg/ton, used in conjunction with cellulose ethers (such as HPMC).
Ordinary Mortar: In products such as thermal insulation mortar and plastering mortar, pregelatinized starch can also be used as a binder and water-retaining thickener, helping to improve workability.
2. Key Mixing Points:
Must be thoroughly dry-mixed: Pregelatinized starch must first be thoroughly mixed with other dry powder materials (such as heavy calcium carbonate, cement, cellulose ethers, etc.). This is the foundation for ensuring stable performance.
Add water and stir: After the dry powder is evenly mixed, add water according to the specified ratio and stir. Pregelatinized starch will swell rapidly when it comes into contact with water, and its viscosity will gradually become apparent.
III. Key Points of Use and Common Issues
In practical applications, the following key points require special attention:
1. Control the Addition Amount: More pregelatinized starch is not necessarily better. Excessive addition may result in an overly hard putty that is difficult to sand; insufficient addition will lead to insufficient adhesion and easy powdering. It is essential to determine the optimal ratio through experimentation.
2. Pay Attention to Raw Material Selection: Pregelatinized starch produced from different raw materials (such as corn and cassava) has different properties. For example, corn pregelatinized starch usually has stronger adhesion and is more suitable for putty powder; while cassava pregelatinized starch, although it may have higher viscosity, usually has weaker adhesion. It is recommended to choose the appropriate type based on product requirements.
3. Pay Attention to Water Resistance Limitations: Ordinary pregelatinized starch-based putty generally has poor water resistance and is mainly used in dry interior wall environments. If used for exterior walls or damp areas (such as kitchens and bathrooms), it is necessary to consider using cement-based or special putty with added water-resistant adhesives.
4. Pay attention to moisture-proof storage: Pre-gelatinized starch is highly hygroscopic and must be stored in a sealed container in a cool, dry place to prevent clumping and affecting its performance.
5. Formula compatibility: Pre-gelatinized starch is often used in combination with cellulose ethers (such as HPMC), which provide a good moisture-retention environment, allowing the starch to hydrate more fully and synergistically improving the final strength. When adjusting the formula, the interactions between various raw materials must be considered.
IV. Optimization Suggestions
Finally, here are some optimization suggestions to help you better utilize pregelatinized starch:
1. Always conduct preliminary testing: Due to differences in raw material sources, auxiliary material properties, and regional environments, it is essential to conduct small-scale trials before large-scale production to determine the optimal formula.
2. Pay attention to application feel: For better application smoothness, consider some specially modified pregelatinized starch products on the market, which may contain ingredients that improve thixotropy.
