1. Introduction to gypsum:
Gypsum plaster, also known as plaster of paris, is a building material widely used as a coating for walls and ceilings. It is a versatile material known for its ease of use, excellent fire resistance and good sound insulation properties. Gypsum plaster is usually made by heating gypsum, a naturally occurring mineral, to remove the moisture and then grinding it into a fine powder.
2. Understand Hydroxypropyl Methylcellulose (HPMC):
HPMC is a cellulose ether derived from natural polymers, primarily cellulose. It is synthesized through the chemical modification of cellulose, in which hydroxypropyl and methyl groups are introduced into the cellulose backbone. This modification gives HPMC unique properties, making it suitable for a variety of applications in areas such as construction, pharmaceuticals, food and personal care products.
3. The role of HPMC in gypsum:
HPMC has a variety of uses in gypsum formulations:
Water Retention: HPMC acts as a water retaining agent, preventing the water in the gypsum mixture from evaporating quickly. This extended processability allows for better spreadability and adhesion to the substrate.
Improved Workability: The presence of HPMC increases the consistency and workability of gypsum plaster, promoting smooth application and reducing the likelihood of cracking or shrinkage.
Enhanced Adhesion: HPMC enhances the adhesion of gypsum plaster to a variety of substrates, including concrete, masonry and drywall, ensuring a long-lasting, durable finish.
Reduced Sagging: By imparting thixotropic properties to the stucco mix, HPMC helps prevent the material from sagging or collapsing during vertical or overhead construction.
4. Properties of HPMC related to gypsum plaster:
Viscosity: HPMC helps increase the viscosity of the gypsum mixture, affecting its flow characteristics and ease of application.
Film Formation: After drying, HPMC forms a thin film on the stucco surface, giving the finished coating strength and durability.
pH Stability: HPMC is stable over a wide pH range, ensuring compatibility with plaster and other additives commonly used in construction.
Thermal Stability: HPMC is thermally stable, making it suitable for use in gypsum formulations that are subject to high temperatures during manufacturing or application.
5. Benefits of using HPMC in plaster:
Improved workability: HPMC enhances the workability of plaster, making it easier to apply and achieve the desired surface finish.
Enhanced properties: The addition of HPMC improves the overall properties of gypsum plaster, including adhesion, water retention and crack resistance.
Versatility: HPMC can be used in various types of gypsum plaster formulations, including primers, topcoats and decorative plasters.
Compatibility: HPMC is compatible with other additives and admixtures commonly used in gypsum formulations, allowing the mixture to be customized to specific project requirements.
6. Application methods and precautions:
Dosage: The appropriate amount of HPMC in a gypsum formulation depends on factors such as required performance, application conditions and specific project requirements. Typically, the dosage range is 0.1% to 0.5% by weight of the plaster mix.
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Mixing Procedure: HPMC should be added gradually to the gypsum mixture while mixing to ensure even dispersion and avoid clumping. Overmixing should be avoided to prevent excessive air entrainment.
Curing Conditions: Proper curing conditions, including temperature and humidity control, are critical to optimizing the performance of gypsum containing HPMC. Adequate curing promotes hydration of the plaster and the development of strength in the stucco coating.
Compatibility Testing: Before incorporating HPMC into gypsum formulations, compatibility testing should be performed to evaluate its interaction with other additives and admixtures. This helps avoid potential problems such as phase separation or loss of performance.
7. Conclusion:
Hydroxypropyl methylcellulose (HPMC) is a valuable additive in gypsum formulations and offers many benefits such as improved workability, enhanced adhesion and reduced shrinkage. By understanding the role of HPMC and its properties, construction professionals can effectively utilize this additive to optimize the performance and durability of gypsum stucco coatings. When using HPMC in gypsum formulations, correct dosage, mixing procedures and curing conditions are key considerations to achieve the desired results.
Hydroxypropyl Methyl Cellulose (HPMC) is a non-ionic cellulose ether made from natural polymer material cellulose through a series of etherification. It is a white powder that swells in cold water into a clear or slightly turbid colloidal solution. It has the characteristics of thickening, dispersion, emulsification, film formation, suspension, adsorption, surface activity, moisture retention and protective colloid.
1.Tile adhesive
As a functional decorative material, ceramic tile has been widely used worldwide, the ceramic tiles have different shapes and sizes, and the unit weight and density are also varied. And how to stick this durable material has always been a concern. The appearance of tile adhesive guarantees the reliable bonding effect to a certain extent.
Tile adhesive is the compound used to stick the tiles to the wall or floor. It is ready-mixed and specially formulated from OPC, selected fine sand, and additives to improve its essential properties for laying tiles.
HPMC can ensure the smooth construction of different types of tiles on various substrates, even if the ambient temperature is relatively high. It can also offer the tile adhesive a long enough open time for adjustment.
HPMC can improve tile adhesive by the following aspects:
2.Gypsum Plasters
Gypsum-based plaster is an interior plastering material made of gypsum hemihydrate, cellulose ethers, lightweight aggregates, retarders and other auxiliary materials. Gypsum-based plaster is characterized by energy efficiency, environmental friendliness and fire resistance.
HPMC can provide the following improvements for gypsum plasters:
3.Self-leveling
The self-leveling compound is a chemical mixture used to smooth uneven concrete or wooden floors with a flat and self-compacting function. Its ability to level and self-seal is crucial to achieving a smooth and seamless floor.
A quality self-leveling product should have the appropriate operating performance and can maintain its leveling performance and self-healing ability, which require the compound to ensure both its uniformity and stability during the construction. And secondly, it must have a certain strength, including the bearing capacity and the binding force to the base surface. These are the basis for the normal application of floor materials. In the realization of self-leveling properties, special low viscosity HPMC product play an important role.
4.Masonry mortar
The autoclaved aerated concrete(AAC) block laying mortar is a light porous silicate product made by using silicon material (sand, fly ash, silicon-containing tailings, etc.) and calcium material (lime, cement) as their main raw materials, adding aerating agent (aluminum powder), and through the technological processes of material preparation, stirring, casting, precuring, cutting, steaming, and curing. Because it contains many uniform and fine air holes after it is aerated, it is called aerated concrete block laying mortar.
As a new type of wall material, the aerated block has the advantages of lightweight and good thermal insulation performance. But at the same time, its water absorption rate is relatively large, and the water absorption is slow, and the drying speed is also slow. The traditional mortar construction is prone to poor adhesion between the masonry and the hollow wall cracking, even large areas of shedding and other problems appeared, thus an excellent performance of aerated concrete plastering mortar composite admixture came into being.
The composite admixture mixed with HPMC products greatly improves the workability of the mortar, improves the water retention, toughness, and bonding strength of the mortar, and reduces the shrinkage of the mortar, which solved the problems caused by traditional mortars.
5.Detergent
A special grade of Cellulose ether(HPMC) is used in detergents to stabilize emulsions and suspended particles and is used for thickening and rheological modification of systems with high surfactant content. The thickener product is supplied in a low-viscosity liquid, easy to pour and pump. It is incredibly convenient for batch use and automatic metering devices.
High viscosity HPMC is very well suited to thicken washing up liquids as they normally form a clear solution, have a good level of compatibility with ionic tensides, and can easily be incorporated into the washing up liquid, due to their delayed solubility. Good storage stability will also be achieved.
When HPMC is used in detergent, its dosage should be determined according to the customer’s design. The recommended addition amount is 0.5%-4.0% of the total formula. It can also be used in conjunction with other types of thickeners according to different requirements to achieve the formulation design’s viscosity and rheological properties.
With years of experience in the related industry and customer needs, Meikai has successfully developed various cellulose ether products under the brand MikaZone™.
Feel free to contact with MikaZone team.
Are you interested in learning more about HPMC for gypsum? Contact us today to secure an expert consultation!