first. First understand what is redispersible polymer powder.
Dispersible polymer powders are powdered polymers formed from polymer emulsions through the correct spray drying process (and the selection of suitable additives). The dry polymer powder turns into an emulsion when it encounters water, and can be dehydrated again during the coagulation and hardening process of the mortar, so that the polymer particles form a polymer body structure in the mortar, which is similar to the action process of the polymer emulsion, which can improve the cement mortar. sexual effect. Emulsion dry powder modified mortar is called dry powder mortar (also known as dry mixed mortar, dry mixed mortar). Since dry powder does not need to consider emulsion formulation and stability like polymer emulsions, a small amount of admixture can make the mortar achieve the desired properties, and it has the advantages of easier packaging, storage, transportation and supply than emulsions, antifreeze and no mold growth, The problem of living bacteria, and the advantage that it can be made into a one-component product with ready-mix packaging such as cement and sand, and can be used after adding water.
When applying, mix and pack sand, cement, emulsion dry powder and other auxiliary additives in advance, and only need to add a certain amount of water during on-site construction to make dry powder mortar with better performance. The core of the production of dry emulsion powder is that the polymer particles after redispersion of the latex powder show a particle size or particle size dispersion similar to that of the original emulsion polymer particles. A certain amount of protective colloid such as polyvinyl alcohol should be added to the emulsion, so that the latex powder can be re-dispersed into an emulsion when it contacts with water. Only with good dispersibility can the latex powder achieve the best effect. . The dispersible polymer powder is usually white powder. Its ingredients include:
Polymer resin: It is located in the core part of the rubber powder particles, and it is also the main component of the redispersible polymer powder.
Additive (internal): together with the resin, it plays the role of modifying the resin. Additives (external): Additional materials are added to further expand the performance of the dispersible polymer powder.
Protective colloid: a layer of hydrophilic material wrapped on the surface of redispersible latex powder particles, the protective colloid of most redispersible latex powder is polyvinyl alcohol.
Anti-caking agent: fine mineral filler, mainly used to prevent the rubber powder from caking during storage and transportation and to facilitate the flow of rubber powder (dumped from paper bags or tankers.)
How to identify the quality of redispersible latex powder?
Method 1, ash method
Take a certain amount of redispersible latex powder, place it in a metal container after weighing, heat it up to about 500 degrees, after sintering at a high temperature of 500 degrees, cool it to room temperature, and weigh again. Light weight and good quality.
Method two, dissolution method
Take a certain amount of redispersible latex powder and dissolve it in 5 times the mass of water, stir well and let it stand for 5 minutes before observing. In principle, the less inclusions that settle into the bottom layer, the better the quality of the redispersible polymer powder. This method is simple and easy to do.
Method three, film forming method
Take a certain quality of redispersible latex powder, dissolve it in 2 times the water, stir it evenly, let it stand for 2 minutes, stir it again, pour the solution on a flat clean glass, and place the glass in a ventilated shaded place. Remove when fully dry. Observe the removed polymer film. High transparency and good quality. Then pull moderately, with good elasticity and good quality. The film was then cut into strips, immersed in water, and observed after 1 day, the quality of the film was less dissolved in water. This method is more objective
Post time: Oct-27-2022