Powder Polymer Systems for Standard and High Quality Ceramic Adhesives

1. Introduction to Ceramic Tile Systems

The most efficient use of ceramic tiles depends on careful planning, correct material selection, preparation work, application skills and proper use. Ceramic flooring systems, which vary according to their areas of application, are listed in Table 1. These can be divided into four main groups and other special systems (for example, wood or metal surfaces). I. Simple Wall Tiles: Simple systems where standard adhesive is used between the substrate and tile for low mechanical load dry indoor environments (for example, C1TE according to EN 12004). II. Underfloor Heating Systems: Heating is integrated into the flooring structure. Temperature variations and traffic loads require higher quality adhesive (for example, C2ES1 according to EN 12004). III. Waterproof Systems: Integrated waterproofing membranes are used for wet conditions (minimum C2 according to EN 12004). IV. Drainage Systems: Ceramic adhesives are suitable for terraces with integrated drainage membranes (minimum C2 according to EN 12004). For wood surfaces, special adhesives classified as P1 or P2 are used (according to ISO 13007-1). For flexible surfaces on wood or metal substrates (for example, ship decks), flexible adhesives are required (C2ES2 according to EN 12004). Generally, C1, C2, S1 and S2 classes are designed with certain adjustments in binder systems (cement and polymer). E and F classes are rarely combined because the corresponding formulation principles contradict each other. T class can be formulated with various viscosity modifier products.

2. Polymer/Cement Ratio Concept

Regarding polymer dosage in dry mortar formulations, weight percentages are generally used in the industry. Except for special mortars such as flexible tile adhesives or flexible cement waterproofing membranes, typical polymer dosages are only at 2-3% levels. Thus, 3% polymer and 30% cement by weight are typical dosages for these two components, resulting in a 0.1 polymer/cement weight ratio. However, when considering the microstructure of such a mortar, volume percentages of the components are important. Taking densities into account (approximately 1 g/ml for polymer, approximately 3 g/ml for cement and cement hydrates), the volumetric polymer/cement ratio is determined as 0.3. Respectively, when considering the specific surface area of latex and cement with Blaine values of 6,000 and 4,500 cm2/g, the polymer/cement ratio rises to 1.33. These calculations demonstrate why a relatively low 3% polymer by weight can double the strength properties, which are clearly related to the specific surface area of the polymer binder.

3. Flexibility Concept

Flexibility, also called "horizontal deformation" or "transverse deformation", is measured by the flexural strength mechanism. In concrete technology, it is known that flexural strength increases with the compressive strength of the material. This is because cementitious materials have much higher compressive strength compared to their tensile strength, and in flexural mode the upper part of the specimen is compressed and only the lower part is under tension. Therefore, the high compressive strength of the upper part determines the bulk flexural behavior of the mortar beam. From a mechanical perspective, strong polymers with a high glass transition temperature have a higher elastic modulus and are therefore closer to the mechanical properties of the cement G 36 matrix. Therefore, in many cases strong polymers perform better in terms of both strength and deformation properties such as compressibility and flexibility.

4. A New Powder Polymer for Flexible Formulations; ELOTEX® FX1000

The characteristics of ELOTEX® FX1000, a new addition to the ELOTEX® portfolio of redispersible polymer powders, and other powder polymer product groups are listed in Table 2. ELOTEX® FX1000 is a redispersible polymer powder (RPP) prepared to high quality standards that enables formulation of C1 and C2 group products. In addition, it is specially designed for flexible adhesives that can also be deformed in the quality range of S1 and S2 flexible mortars (see Table 1). The ELOTEX® ceramic adhesive product portfolio used at FX1000 approximately 4.0% polymer levels by weight can achieve C2S1 quality in products with high mechanical strength and mechanical compatibility properties with solidified mineral binder matrix. The resulting new product will have excellent fresh mortar rheology as well as a higher open time value (see Figure 2).

Figure 2 (a). Horizontal deformation as a function of polymer dosage and (b) adhesive strength.

High standard product formulations in the C2S2 segment require polymer content in the 10% range by weight. However, these usage levels can lead to unstable rheology over time and bubbled mortar surfaces (see Figure 3b). ELOTEX® FX1000, on the other hand, has been designed as a polymer that behaves rheologically neutral in high pH and high ionic strength environments as a result of all R&D accumulated knowledge aimed at solving these problems. Furthermore, ELOTEX® provides compatibility with EMICODE EC1PLUS at high modification levels. In conclusion, in the case of ELOTEX® MP2100 and ELOTEX® FX1000, superior processing properties throughout the pot life mean that FX1000 provides dry mortar manufacturers with maximum options for developing economically and technically efficient and high-performance premium C2S1 and C2S2 formulations. In addition, it is possible to achieve improved open time and stable rheology throughout pot life with this product group of the ELOTEX family.

Acknowledgements

We thank Stefan Studer and Srdan Kisin for laboratory work and Markus Gassner for technical support.

Industrial Standards

EN 12004-1 (2017): Adhesives for ceramic tiles – Part 1: Requirements, assessment and verification of constancy of performance, classification and marking. EN 12004-2 (2017): Adhesives for ceramic tiles – Part 2: Test methods. ISO 13007-1 (2014): Ceramic tiles — Grouts and adhesives — Part 1: Terms, definitions and specifications for adhesives.

Dr. Yasemin İlhan

  Sales and Marketing Manager Reaksiyon Kimya