I. Product Overview

Redispersible Polymer Powder (RDP) is a white, free-flowing thermoplastic resin powder produced by spray drying polymer emulsions. When mixed with water, it rapidly redisperses to form a stable polymer emulsion, restoring its original binding and film-forming properties.

The main component of RDP is Vinyl Acetate-Ethylene (VAE) copolymer, with polyvinyl alcohol as a protective colloid, along with appropriate amounts of anti-caking agents and functional additives. The product complies with national standard GB/T 29594-2013 and industry standard JC/T 2189-2024.

II. Product Classification

2.1 Classification by Polymer Composition

Based on polymer composition, RDP is primarily classified into the following types:

Other modified products include Ethylene-Vinyl Chloride-Vinyl Laurate terpolymers and Vinyl Acetate-Ethylene-Vinyl Ester of Versatic Acid copolymers.

2.2 Classification by Glass Transition Temperature

Based on Glass Transition Temperature (Tg), RDP can be classified as:

• Rigid Type (High Tg): Tg approx. 12°C, suitable for systems requiring high hardness

• Medium Flexible Type: Tg approx. 3°C, balancing rigidity and flexibility

• High Flexible Type: Tg approx. -8°C, suitable for high flexibility requirements

• High Flexible + Waterproof Type: Tg approx. -11°C, combining flexibility and hydrophobic properties

III. Physical and Chemical Properties

3.1 General Technical Specifications

Typical technical specifications for RDP are as follows:

3.2 Thermal Properties

Products with different glass transition temperatures suit different applications: low Tg products offer better flexibility for high-flexibility systems; high Tg products offer higher hardness for rigid systems.

IV. Core Mechanism of Action

4.1 Role in Wet Mortar

When RDP is added to mortar and mixed with water, the powder particles rapidly disperse in water, providing the following benefits:

• Improved Workability: Enhances smoothness and spreadability

• Better Flow Properties: Makes mortar easier to spread and level

• Increased Thixotropy and Sag Resistance: Prevents sagging during vertical application

• Enhanced Cohesion: Strengthens internal particle bonding

• Extended Open Time: Provides longer working window for application

• Improved Water Retention: Reduces rapid water evaporation, ensuring adequate cement hydration

4.2 Role After Mortar Hardening

As water evaporates and cement hydrates, the powder particles coalesce to form a continuous polymer film within the mortar, providing the following enhancements:

• Increased Tensile Strength: Enhances the mortar's tensile capacity

• Higher Flexural Strength: Improves resistance under bending loads

• Reduced Elastic Modulus: Makes the mortar more flexible

• Increased Deformability: Accommodates thermal expansion and contraction of the substrate

• Enhanced Abrasion Resistance: Improves surface durability

• Higher Cohesive Strength: Strengthens internal material bonding

• Reduced Carbonation Depth: Delays carbon dioxide ingress, protecting reinforcement

• Reduced Water Absorption: Some powder types can impart water-repellent properties

4.3 Modification Mechanism

The modification effect of RDP on cement mortar operates at both micro and macro levels:

• Polymer particles form a continuous film structure within cement pores, enhancing interfacial bonding

• Formation of interpenetrating network structures with cement hydration products, improving overall mortar performance

• Reduction of compressive-to-flexural strength ratio, enhancing flexibility

V. Main Application Areas

5.1 External Wall Insulation Systems

In external wall insulation systems, RDP is primarily used in:

• Adhesive Mortar: Forms reliable bonding with insulation materials such as EPS boards and mineral wool

• Base Coat Mortar: Forms a crack-resistant protective layer, improving impact resistance

5.2 Tile Adhesives and Grouts

RDP significantly improves the bond strength and flexibility of tile adhesives, suitable for thin-bed adhesives and grouts.

5.3 Self-Leveling Mortar

In self-leveling mortar, RDP improves flowability, increases abrasion resistance, and enhances bond strength to the substrate.

5.4 Repair Mortar

Suitable for concrete crack repair and tunnel lining restoration, improving bond strength, flexural strength, and workability.

5.5 Other Applications

• Interior and exterior flexible putties

• Dry-mix coatings

• Powder paints

• Adhesives for thermal insulation materials

VI. Dosage Recommendations

Based on mortar type and performance requirements, recommended RDP dosages are as follows:

Note: The above are reference ranges. Specific dosage should be determined through testing based on raw material characteristics, equipment conditions, and performance targets.

VII. Storage and Handling Precautions

7.1 Storage Conditions

• Store in a cool, dry place, avoiding high temperature and humidity

• After opening, use as much as possible in one go; otherwise, reseal the bag to prevent moisture absorption

• Avoid stacking pallets too high to prevent prolonged excessive pressure on bags, which may cause caking

7.2 Handling and Application Precautions

• Mix thoroughly with other dry powders before adding water

• After adding water and mixing, allow the mortar to rest for 5 minutes to let the powder fully dissolve and disperse, then mix again before use

• Avoid excessive pressure and shear forces during mixing or conveying processes to prevent agglomeration of thermoplastic resin particles

• Adjust water content based on ambient temperature and humidity