Preparation of redispersible latex powder
Weigh a certain amount of acrylate emulsion, adjust the pH value to 9.0 with 2.5% (mass percent) NaOH dilute solution, and then add 25% of the emulsion mass silica sol. After stirring evenly, the feed liquid is passed into the centrifugal spray drying tower under the guidance of the peristaltic pump . In the atomizer, the rotation speed of the rotating disk is 21000 r/min, the inlet temperature is 120 °C, the outlet temperature is 80 °C, and the feed rate is Spray drying is carried out under the condition of 60 g/min. After the latex powder is formed, it is separated by a cyclone separator. The powder is collected in a stainless steel barrel storage tank at the outlet of the tower. After filtering through a 200-mesh filter, it is sealed in a bag and stored in a dry box. .
Effect of Drying Pretreatment on Latex Powder
To prepare redispersible latex powder with good performance, in addition to the characteristics of latex particles, pretreatment is often required, such as adding a certain amount of protective colloid and drying aids. Carboxyl groups and carboxylic acid ions have a great influence on the dispersibility of latex powder and the stability , and the degree of ionization is closely related to the pH value of the emulsion. Therefore, it is necessary to investigate the influence of pH value on the properties of latex powder in detail. At the same time, the effect of the amount of protective colloid polyvinyl alcohol (PVA) and drying aid silica sol on the properties of latex powder was investigated .
Effect of Drying Temperature on Latex Powder
During the spray drying process, process parameters such as drying inlet and outlet temperature and atomizer speed have important influence on the appearance . Keep the feed flow rate and atomizing disk speed constant, change the inlet and outlet , and discuss the influence of the inlet and outlet temperature on the appearance and performance of latex powder.
Influence of rotating speed of atomizing turntable on latex powder
Maintain a certain feed flow rate and air inlet temperature of the drying tower, change the rotation speed of the atomization disc, and discuss the influence of the rotation speed of the atomization disc on the appearance and performance of the latex powder.
Viscosity determination
Use a DV-2+Pro digital viscometer to measure the viscosity of the emulsion, and the measurement conditions are 25°C and 120 rpm.
