Redispersible emulsion powder is that the high polymer emulsions after spray drying, and subsequent processing, become a powdery thermal plastic resin. Usually the powder is white, but a few contain other colors. It is mainly used in construction, especially in the increase of cohesive strength, cohesion force, and flexibility to dry mixing mortar, showing the good performance.

 

Production of redispersible polymer powder is mainly divided into two steps: The first step is the production of the polymer emulsion through emulsion polymerization; the second step is spray- drying the mixture prepared by the polymer emulsion to obtain the polymer powder.

 

Drying process: The polymer emulsions prepared are delivered into a spray- drier by a screw pump for drying , the inlet temperature of dryer generally to be 100 ~ 200ºC, at the outlet generally to be 60 ~ 80 ºC. Since spray- drying occurs within a few seconds , then the distribution of the particles are "frozen" , and the protective colloid as the spacer particles play a role in isolation , thereby preventing the polymer particles from irreversible coalescence.  In order to prevent redispersible powder from “caking” during transportation and storage, the anti-caking agent must be added in the spray drying process or later.

 

 For urea resin adhesive, its bonding strength is high, temperature resistance; water resistance and corrosion resistance are good. In addition, because the resin itself is transparent or milky white, the made-up shaving board and fiberboard with medium density show beautiful colors, and the made-up plywood would not produce pollution, so use in the wood products do not affect the appearance. Urea resin powder is made of liquid resin through spray drying, it is an one-component adhesive powder, with such excellent performances as water resistant, mildew proof, anti-yellowing, strong adhesion, anti-aging, capable cold or hot pressing, not easy to deformation, convenient use, long period of storage etc..  Suitable for bending wood, skinning, assembling, thin wood veneer, edging, particleboard, bonded between medium density fiberboards, which is an ideal adhesive for assembling furniture, wood gluing etc.

Drying process: The resin emulsions prepared are delivered into a high-speed centrifugal atomizer by a screw pump, and are atomized into a large number of small droplets with uniform size. Contacting with the hot air in the drying tower, water is quickly evaporated, and then water vapor and powders enter into the cloth bag dust remover. Water vapor passes through a filter bag into the induced draft fan for emptying, the dry powders which fall down at the bottom of the bag dust remover due to pressure drop, are concentrated into the small bags for material receiving through the rotary valve and the air conveying pipes. and then through the sieve vibrating to a stock bin, finally removing iron to automatic packing machine for receiving. In order to prevent redispersible powder from “caking” during transportation and storage, the anti-caking agent must be added with a screw feeder in the spray drying process.