Redispersible polymer powders (RDP) are complex mixtures of polymers and additives that are widely used in construction materials, especially in the production of dry-mix mortars. These powders play a vital role in improving the performance and characteristics of various construction materials such as tile adhesives, grouts, self-leveling compounds and cementitious plasters.
The key components:
Polymer base:
Ethylene vinyl acetate (EVA): EVA copolymer is commonly used in RDP due to its excellent film-forming properties, adhesion, and flexibility. The vinyl acetate content in the copolymer can be adjusted to change the properties of the polymer.
Vinyl Acetate vs. Ethylene Carbonate: Depending on the specific requirements of the application, manufacturers may use ethylene carbonate instead of vinyl acetate. Ethylene carbonate has improved water resistance and adhesion in humid conditions.
Acrylics: Acrylic polymers, including pure acrylics or copolymers, are utilized for their exceptional weather resistance, durability, and versatility. They are known for providing excellent adhesion to a variety of substrates.
Protective colloid:
Hydroxypropyl methylcellulose (HPMC): HPMC is a protective colloid commonly used in RDP. It improves the redispersibility of polymer particles and enhances the overall properties of the powder.
Polyvinyl alcohol (PVA): PVA is another protective colloid that aids in the stability and dispersion of polymer particles. It also plays a role in controlling the viscosity of the powder.
Plasticizer:
Dibutyl Phthalate (DBP): DBP is an example of a plasticizer that is often added to RDP to improve flexibility and processability. It helps lower the glass transition temperature of the polymer, making it more elastic.
filler:
Calcium Carbonate: Fillers such as calcium carbonate can be added to enhance the bulk of powders and provide a cost-effective way to adjust properties such as texture, porosity and opacity.
Stabilizers and antioxidants:
Stabilizers: These are used to prevent degradation of the polymer during storage and processing.
Antioxidants: Antioxidants protect the polymer from oxidative degradation, ensuring the longevity of RDP.
Functions of each component:
Polymer base: Provides film-forming properties, adhesion, flexibility and mechanical strength to the final product.
Protective colloid: Enhance the redispersibility, stability and dispersion of polymer particles.
Plasticizer: Improves flexibility and processability.
Fillers: Adjust properties such as texture, porosity, and opacity.
Stabilizers and antioxidants: Prevent polymer degradation during storage and processing.
in conclusion:
Redispersible polymer powder (RDP) is a versatile and important ingredient in modern building materials. Its chemical composition, including polymers such as EVA or acrylic resins, protective colloids, plasticizers, fillers, stabilizers and antioxidants, is carefully formulated to meet the specific requirements of each application. The combination of these components helps improve powder redispersibility, bond strength, flexibility and overall performance in dry mix mortar formulations.
Post time: Dec-18-2023