Study Of The Modification Of Kaolin And Its Application In NR

Our country is rich in kaolin, but the efficient use of kaolin resources and newmaterials development further be strengthened. Currently, kaolin mainly used as thefiller of paper, paint and ceramic mainly in the use of kaolin as paper, paint, ceramicfiller material, the modifier of cement and the filler of rubber. China’s tire market ishuge, but kaolin rarely used in this field. Only a small amount used in an airtight layerthat there is lower requirements for mechanical properties.Because kaolin is aninorganic hydrophilic material, poor compatibility with rubber and poor dispersion inrubber, resulting in the mechanical properties of the rubber decrease.Throughactivation of kaolin and reducing the particle size of kaolin to improve the amount ofkaolin in the tire industry. In this thesis, the sub-nanometer kaolin was modified by dryand wet modification processes with boric acid ester coupling agent, and studied theapplication of modified kaolin in NR. Kaolin is provided by Beihai Kaolin Co., Ltd.In this paper, five kinds of borate ester coupling agent were selected to modifykaolin by dry modification process as reinforcing filler of steel radial truck tire tread.Study the effects of species and dosage of boric acid ester coupling agent on tiretread’s processing performance, curing characteristics and mechanical properties. Theresults showed that, the effective activation index of SB-1was the highest. Tread’s processingperformance and dynamic performance were the best when the quantity of SB-1was2.0%. Theprocessing performance and the processing security of the rubber was improved, the energyconsumption was reduced when using the modified kaolin replace silica. The compression heat andhysteresis loss of of vulcanizates reduced, the tensile strength remained unchanged, but abrasionresistance and tear resistance decreased.In this paper, research focused on the application of carbon black/silica replacedby the dry modified kaolin with SB-1in the natural rubber composites, and theinfluence of anti-wear agent SPE-100on the properties of the composite materials. The results showed that mixing energy consumption and dumping temperature ofcompounds gradually reduced besides process ability improved with the contentmodified kaolin replaced carbon black increased. The mechanical properties ofvulcanizates gradually decreased accompanied by improving of aging resistance withdynamic compression heat reduced. As the substituted amount of modified kaolinreplaced silica in the tread formula increased, mixing energy consumption and abrasiveresistance of NR decreased but the safety in processing enhanced. The rate ofproduction and aging resistance improved. Dynamic compression heat decreased androlling resistance of tread rubber lower. Anti-wear agent was added to improve themechanical properties of rubber material and processing properties as well as theabrasion resistance of vulcanizates, but not affected compression fatigue temperaturerise. When the modified kaolin and anti-wear agent ratio reached10:2, the physicalproperties of vulcanizates were relatively best. The dispersion of modified kaolin inNR got better with the ratio increased.In this paper, the same kaolin was modified respectively by the laboratory andmodification apparatus used in large-scale industrial production，then they replacedsilica respectively filled into the tread.Comparison of the three modified kaolin filledrubber, processing properties, curing properties, mechanical properties and agingresistance of vulcanizates showed no significant differences. This verified thefeasibility of the modified kaolin prepared in laboratory to expand production.In this paper, wet modified kaolin filled in tread, the influence of modified timeon the modification effect of kaolin was studied. The dumping temperature and mixingenergy consumption significantly reduced, the scorch time extend, tc90basicallyunchanged, elongation at break increased, compression heat reduced, abrasionresistance declined after modified kaolin replaced the silica. The vulcanizate filledwith kaolin which modified for ten minutes had the highest tensile strength, the highesttear strength and the lowest compression heat. The relatively optimal time of wetmodified kaolin is10min. With the extension of the modified time, the physicalproperties of vulcanizates tend to be deteriorated.