Effect Of Modified Talc On White Pitch

It is inevitable that broke will be produced during coating paper production in paper mill, white pitch issue due to the recycling use of coating wasted paper will affect not only the paper machine operation, but also variety physical indexes of paper. Nowadays there have many methods to control white pitch, but there exists no effective and convenient one. This paper use modified talc which clad talc to cationic starch to handle white pitch issue.This paper analyses characteristics of white pitch, finds advantages and disadvantages of common used white pitch control agents through experimental analysis, also reviews the optimum process conditions and micro synthesis mechanism of modified talc. Research shows that:1. The research of white pitch indicates:the top influence factor is pulp concentration, then next are pH, shear stress and temperature. As the pulp consistency rises, amounts of white pitch content basic a straight line growth. pH is another important influence factor, there will have more stickies, when pH keep low. Shear stress and temperature can also influence white pitch, more stickies will be produced at strong shear stress or a high temperature.2. The research of white pitch control agent indicates:The optimal ratio of talc is10%, while not on strong shearing stress; the optimal ratio of aluminum sulfate is0.4%, pH is between4.0and5.0; The optimal ratio of PEI is0.02%; The optimal conditions of amylase are: time:60min, pH:7.4, temperature:50℃, dosage of enzyme:400mg/L. Coating wasted paper through dealing with amylase can have a better coating layer. The best ratio of coating wasted paper amount is10%.3. The research of single factor indicates:The optimal conditions of modified talc are agitation speed with600r/min, time for20min, temperature on90℃, concentration ratio with2.5%, and10%cationic starch.4.The research of effect with modified talc on white pitch indicates:When the dosage of modified talc is10%, turbidity of the filtrate decreases62.5%, Zeta is clearly on the rise, with dosage less than20%; paper strength and the paper ash also increase with talc dosage rise. Compare with unmodified talc, modified talc has better treatment results.5. IR、SEM and diameter of modified talc indicates:Cationic starch can clad on the surface of, and the head face has more adsorption capacity than the cleavage plane. Comparison of electron micrograph talc with modified one show that modified one has smaller particle size, rougher surface and more uniform size distribution.