Development Of Silicate Functional Fillers

Synthetic Silicate have been widely used in construction,medicine,beauty,paint,water treatment and other industries,but in the paper industry are rare.It has the advantage and potential as a functional filler for papermaking because of excellent optical properties and controllable particle structure.Firstly,the synthesis technology of magnesium aluminum silicate was studied,including the ratio of raw materials,feeding sequence,reaction time,pH of the system,reaction temperature,stirring speed,concentration of the reaction.The results showed that the particle morphology of synthetic magnesium aluminum silicate was mainly affected by the proportion and the order of addition of raw materials and the pH of the system,the particle size of synthetic magnesium aluminum silicate was mainly depended on the stirring speed.Therefore,the optimized synthesis conditions of magnesium aluminum silicate were adding sodium silicate solution to aluminum sulfate and magnesium sulfate solution(aluminum-silicon ratio of 1:6,magnesium-aluminum ratio of 4:25),and the system pH of 10.5-11.5,the reaction temperature at 50?,the reaction concentration of 0.20 mol/L,the stirring speed of 1200rpm,and the reaction time of 120min.The primary particles of the synthetic magnesium aluminum silicate based on the above conditions were in the shape of complete spheres.the aggregates had satisfactory structure and well-developed pores.Next,the properties of the magnesium aluminum silicate filler and fillings pulp were analyzed.The results showed that the whiteness of the synthetic magnesium aluminum silicate filler was 96.3%ISO.Compared with the conventional filler GCC,PCC and similar fillers,the median particle size(12.9?m),oil absorption value(183.87g/100g,)and sedimentation volume(6.9mL/g)were the largest,and the abrasion(4.3g/m2)was the smallest;the synthetic aluminum magnesium silicate filtration time was 31.5s/500g and one-way retention rate was 41.5%.Then,the properties of the magnesium aluminum silicate in paper fillings were analyzed.The results showed that the bulk increased by 13.9%and 5.1%,and the tensile index decreased by 9.0%and 2.8%,the print-through value(yellow)decreases by 19.5%and 16.6%,and the print-through value(black)decreases by 31.7%and 20.6%compared with the PCC and GCC(ash content 17%),compared with the similar filler the bulk and opacity were similar,the value(yellow)and the value(black)of print-through was decreases by 6.9%and 6.1%.When the ratio of synthetic magnesium aluminum silicate and GCC was 1:3,the bulk and opacity was 10.9%,1.3%higher than GCC.the value(yellow)and the value(black)of print-through were 12.1%and 16.3%less than the similar filler and GCC.