Study On The Modification Of Coal Series Kaolin And Its Application In Rubber

The reserves of coal series kaolin are much richer than other kaolin in China,it has a unique resource advantage in China.The coal series kaolin is mainly piled up and abandoned with the mining of coal mines,and the utilization rate of raw materials is low,resulting in waste of resources.At present,the main application of kaolin is in ceramics,paper and so on,but it is relatively less in rubber filling.In this paper,through the study of different types of kaolin on rubber reinforcement and the comparison between different fillers to find the advantages and disadvantages of coal series kaolin.To find the best modifier,dosage and time of coal series kaolin by dry modification to improve the reinforcing effect of rubber.And explore the application effect of coal series kaolin in the air tight layer of tire and the sealing strip of passenger car.In this paper,three kinds of coal series kaolin,three kinds of domestic kaolin and two kinds of foreign kaolin are selected to explore the influence of them on the reinforcement performance of SBR,and the comparison experiment with other common rubber fillers is carried out.The results show that G90 has the best mechanical reinforcement performance in coal series kaolin,which is equivalent to BHK and strong micropowder in Beihai kaolin of domestic products,but has some disadvantages compared with snobrite75.In contrast experiments of different fillers,kaolin G90 of coal measures is only inferior to carbon black and silica,and is much better than calcium carbonate,garnet,barium sulfate and calcite.But the elongation at break of coal kaolin rubber is higher than that of carbon black vulcanizate.It is better than silica in resilience,compression set and compression heat generation.In the modification experiments of kaolin in coal series,silane coupling agent KH550 in 5 different modifiers has the best modification effect on kaolin.However,the activation index can not effectively evaluate the reinforcing effect of kaolin on rubber.Therefore,the method of sedimentation volume and Zeta potential is adopted for pre evaluation.The optimum dosage of KH550 is 4% and the modification time is 1 min.It was determined by infrared spectrum that the modifier was bound to coal series kaolin in the form of chemical bond.The improvement of the binding and compatibility between the modified kaolin and the rubber was observed by SEM.The Payne effect of NBR filled with modified coal series kaolin decreased,the dispersion property of filler became better,the comprehensive mechanical property was t he best,the tensile strength could be increased to 13.7MPa,about 89% increase.The abrasion resistance of the compound is improved,and the abrasion volume is reduced by about 18%.In the application experiment of the formula of tire air tight layer,the effects of the ratio of CM and BIIR and the amount of coal kaolin on the properties of air tight layer compound were studied.With the increase of CM ratio,the curing time becomes shorter,the maximum torque MH increases,and the decomposition temperatur e increases.But the physical and mechanical properties,heat-resistant aging performance,air tightness performance are decreased.Therefore,the proportion of CM in combination should not be too high,and the proportion of BIIR/CM is 90/10.On this basis,the addition of a small amount of coal series kaolin,with the increase of the amount of coal series kaolin,has no significant impact on the properties of Mooney,vulcanization,physical and mechanical properties.However,it can improve the air tightness.When 6 parts of kaolin is added,the air tightness is the best,but when it is more than 6 parts,the air permeability coefficient increases abruptly.In the formula of passenger car sealing strip,coal kaolin with equal mass and equal volume was used to replace carbon black,The maximum equivalent mass substitution of coal kaolin for carbon black is 50-55 phr.The increase of substitution will lead to the decrease of physical and mechanical properties and aging properties,which can not satisfied with the standard of passenger car sealing strip.When the substitution quantity is 50 phr,the economic cost per ton of rubber can be reduced by 537 yuan.After substituting in the way of equal volume substitution.Different from equal quality substitution,the elongation at break increases with the increase of coal series kaolin substitution,and the change trend of other properties is the same as that of equal quality substitution.The standard of sealing strip for passenger cars can be satisfied when the amount of carbon black to be replaced is between 40 and 50 phr.When 53.6 parts of coal kaolin is used to replace 40 parts of carbon black,the economic cost per ton of rubber material can be saved about 356 yuan.