Study Of The Methods To Reduce The Calcium Carbonate Oil Absorption Value

Oil-absorption value is an important parameter of calcium carbonate. Adding lower oil-absorption value calcium carbonate in plastic can decrease the dose of plasticizer, so the plastic cost is also decreased, the mechanics capability of the plastic product are improved. Crystal controlling and organic modifying were used to lower the oil-absorption value. Introducing ground calcium carbonate into precipitated calcium carbonate is the universal method which reduces the oil absorption value in industry. But the edge angles and the smooth surfaces of the ground calcium carbonate reduce the mechanics capability of PVC. Chemical precipitation was used to modify ground calcium carbonate, the surface configuration was improved, and the mechanics capability which used in plastic is greatly improved.The optimum crystal controlling agent sodium acetate was selected by experiment. Used the crystal controlling agent sodium acetate, the lowest oil-absorption calcium carbonate was prepared by"aging-recarbonate"method, it was crude slurry aged for two days, and then carbonated at 20 degree centigrade to the pH value to 9, then continued to aging for two days, recarbonated the slurry pH value to 7, the lowest oil-absorption value is 70ml/100gCaCO₃.The modification of organic compound to reduce the oil-absorption of calcium carbonate, optimistic process of stearic acid and flax oil are confirmed by single factor experiment. The stearic acid modification process condition is that the temperature is 85℃, the dose of stearic acid is 2.5% of the weight of calcium carbonate, reaction time is 55⁶0 minutes, the dose of sodium hydroxide is 10% of the weight of stearic acid. The flax oil modification process condition is that the dose of flax oil is 15% of the weight of calcium carbonate, the dose of sodium hydroxide is 2.5 of the weight of flax oil, the temperature is 25℃, the reaction time is 1 hour. The activity rate of calcium carbonate above 99% and the oil-absorption value below 45ml/100gCaCO3 can be obtained via all those process above.using chemical precipitation process modified ground calcium carbonate. The mechanics capability used in plastic products is greatly improved. The optimistic process condition is that using 10 ml acetate acid-sodium acetate solution activates the ground calcium carbonate, and then adding in 1L lime milk of the concentration of 34g/L. Carbonating the slurry at 20℃ obtained the end product, the product capability can compare beauty with precipitation calcium carbonate.