The Roles of Adhesive Powder and Cellulose in Tile Adhesive
Release Time:
2022-05-14
Source:
Latex powder—when added in the wet-mix state, it improves the consistency and smoothness of the system; its polymeric characteristics significantly enhance the cohesion of the wet mix, thereby substantially improving workability. Upon drying, it provides strong adhesion to smooth, dense surface layers and enhances interfacial bonding between sand, aggregate, and air voids. With an appropriate dosage, it can form a rich, film-forming layer at the interface, imparting a degree of flexibility to the tile adhesive, reducing its elastic modulus, and effectively dissipating thermal deformation stresses caused by water absorption. In the event of subsequent water exposure, it also offers waterproofing, thermal buffering, and mitigation of stress arising from differential material deformation (with tile deformation coefficient of 6 × 10⁻⁶/°C and cement concrete deformation coefficient of 10 × 10⁻⁶/°C), thus enhancing weather resistance. Hydroxypropyl methylcellulose (HPMC)—provides excellent water retention and workability for fresh mortar mixes, playing a particularly critical role in ensuring adequate wetting of the substrate. By facilitating the smooth progression of hydration reactions, it prevents excessive water absorption by the substrate and reduces moisture evaporation from the surface layer. Moreover, its air-entraining properties (1900 g/L for standard mortar, 1400 g/L for PO400 sand, and 600 g/L for HPMC) lower the unit weight of the tile adhesive, leading to material savings and a reduction in the elastic modulus of the hardened mortar matrix.
The Roles of Adhesive Powder and Cellulose in Tile Adhesive
Latex powder—when used in the wet-mix state, it enhances the consistency and smoothness of the system; its polymeric characteristics significantly improve the cohesion of the wet mix, thereby substantially contributing to workability. Upon drying, it provides strong adhesion to smooth, dense surface layers and improves interfacial bonding between sand, aggregate, and air voids. With an appropriate dosage, it can form a rich film at the interface, imparting a degree of flexibility to tile adhesive, reducing its elastic modulus, and effectively dissipating thermal deformation stresses caused by water absorption. In the event of subsequent water exposure, it also offers waterproofing, thermal buffering, and mitigation of stress arising from differential material deformation (tile deformation coefficient: 6 × 10⁻⁶/°C; cement concrete deformation coefficient: 10 × 10⁻⁶/°C), thus enhancing weather resistance. Hydroxypropyl methylcellulose (HPMC)—provides excellent water retention and workability for fresh mortar mixes, playing a particularly critical role in ensuring adequate wetting of the substrate. By facilitating the smooth progression of hydration reactions, it prevents excessive water absorption by the substrate and reduces moisture evaporation from the surface layer. Moreover, its air-entraining properties (1900 g/L for standard mortar, 1400 g/L for PO400 sand, and 600 g/L for HPMC) lower the unit weight of the tile adhesive, resulting in material savings and a reduction in the elastic modulus of the hardened mortar matrix.
Redispersible latex powder for tile adhesives is an environmentally friendly, energy-efficient, high-quality, multi-purpose powdered construction material and an indispensable functional additive for dry-mix mortars. It enhances mortar performance by increasing strength, improving bond strength to various substrates, and boosting flexibility, workability, compressive strength, flexural strength, wear resistance, toughness, adhesion, water retention, and ease of application. Redispersible latex powder for tile adhesives boasts exceptionally robust performance, characterized by high bonding capacity and unique properties, making its applications extremely broad. Hydroxypropyl methylcellulose provides initial functions such as water retention, thickening, and enhanced workability, while redispersible latex powder contributes later-stage strength, thereby ensuring structural integrity and excellent resistance to acids and alkalis. In fresh mortar, this additive extends the working time and adjustment period, improves water retention to support cement hydration, enhances slump resistance (thanks to specially modified latex powder), and improves overall workability—making it easier to apply to substrates and to press tiles firmly into the adhesive. In hardened mortar, it exhibits excellent adhesion to a wide range of substrates, including concrete, plaster, wood, existing tiles, and PVC, while maintaining outstanding deformation capacity under diverse climatic conditions.
2022.5.6 group
The addition of redispersible latex powder to tile adhesives significantly enhances the performance of cement-based tile adhesives, markedly improving their bond strength, water resistance, and aging resistance. Currently, a wide variety of redispersible latex powders are available on the market for tile adhesives, including acrylic redispersible latex powder, styrene–acrylic latex powder, and vinyl acetate–ethylene copolymer latex powder. In general, vinyl acetate–ethylene copolymer latex powder is the most commonly used type in commercial tile adhesives.
(1) As the cement content increases, the initial strength of the redispersible latex powder in tile adhesive also increases; concurrently, both the tensile bond strength after water immersion and the tensile bond strength after thermal aging increase as well. Considering that the performance of the redispersible latex powder in tile adhesive meets the relevant standard requirements, the cement content should be no less than 35%.
(2) As the dosage of redispersible latex powder in tile adhesive increases, both the tensile bond strength of the adhesive after water immersion and that after thermal aging increase; however, the increase in tensile bond strength after thermal aging is more pronounced.
Due to their excellent decorative and functional properties—such as durability, water resistance, and ease of cleaning—ceramic tiles are widely used in a variety of applications, including wall coverings, flooring, ceilings, and swimming pools, and can be employed both indoors and outdoors. The traditional method for installing ceramic tiles is the thick-bed mortar technique: a layer of ordinary mortar is first applied to the back of the tile, after which the tile is pressed firmly onto the substrate, with the mortar layer typically ranging from 10 to 30 mm in thickness. Although this method is well suited for application on uneven substrates, it has several drawbacks: low tiling efficiency, high demands on the skill level of the installer, increased risk of tile detachment due to the limited flexibility of the mortar, and difficulty in maintaining strict quality control over the mortar at the job site. Furthermore, this technique is only appropriate for high-water-absorption tiles; prior to installation, such tiles must be soaked in water to achieve adequate bond strength.
Currently, the thin-set method is widely used in Europe for tile installation. This involves applying a polymer-modified tile adhesive to the substrate using a notched trowel to create a uniform mortar bed with raised ridges, after which the tiles are pressed firmly into place and slightly rotated. The mortar bed typically has a thickness of 2 to 4 mm. Thanks to the modifying effects of cellulose ethers and redispersible latex powders, this type of tile adhesive exhibits excellent bond strength on various substrate types and on facing materials such as fully vitrified tiles with extremely low water absorption, while also offering good flexibility to accommodate stresses caused by temperature differentials and other factors. In addition, it demonstrates superior resistance to sagging and provides a sufficiently long open time, which greatly accelerates installation when working with thin-bed applications, makes the process easier to handle, and eliminates the need to pre-wet the tiles in water. This construction method is simple to execute and facilitates effective on-site quality control.
