The Preparation Of Clay/Silica Filler And Its Application In Tire Tread Compounds

With the development of car industry, demands for high-performance tires have increased year after year. High-performance tire tread with good wet-skid resistance, excellent wear resistance, low rolling loss, perfect cut resistance properties and flex-fatigue properties could provide cars with high speed, energy savings, safety and comfortablity. So the development of new filler with low heat build-up and independent of petroleum resource is an urgent task. Silica, a kind of high reinforcement and low heat build-up filler, is gradually popular in rubber industry, but it still shows relatively poor abrasive resistance. Low contents of nano-dispersed clay in the vulcanized rubber can improve various kinds of properties of vulcanized rubber significantly, such as modulus, tear strength and flex-fatigue properties. Combination of silica and clay in rubber materials will assemble their advantages. In this research, a new spray drying method was applied to get exfoliated clay/silica filler. SSBR/BR/silica/clay nanocomposites were prepared by filling silica and clay in rubber. Some of properties of composites were discussed. Detailed researches are as following: 1. In the first part, micro-clay particles were filled in the SSBR/BR tread, replacing the same quality of silica. The amount of fillers stays the same. The ratio of clay/silica were 0/50,2/48,3/47,5/45. The results showed that flex cracking properties improved significantly after adding a small amount of clay. Rolling resistance, heat build-up and abrasive resistance were inferior to the composites reinforced with pure silica.2. The nano-clay/silica compound fillers were prepared by spray drying process. The process parameters of spray drying were investigated. The results showed that the best process parameters of spray drying was spray temperature 190℃, feed rate 40%, atomization switch 50, and spray volume 400 ml/h. The morphological of clay/silica filler had been characterized by TEM and XRD. The results revealed that clay was exfoliated into nanoscale layers.3. The micro-clay and nano-clay/silica compound filler were incorporated into SSBR/BR tread, replacing silica partially. The effects of two kinds of clay on the composites were discussed. The curing time of composites filled with nano-clay/silica was prolonged, while micro-clay had no effect on the curing time. The composites filled with nano-clay have better mechanical properties, wet skid friction, flex-fatigue life and cut-chip resistance than the composites filled with silica only. Wet skid friction, flex-fatigue life and cut-chip resistance were increased 6%,100%and 36% respectively, while heat build-up properties and abrasive resistance were reduced.4. The same quality of compound filler was filled in SSBR/BR tread, replacing part of silica. The ratios of nano-clay/silica were 0/50,1/49,2/48, 3/47,5/45. Filler distribution was measured by transmission electron microscopy (TEM). The results indicated that clay was exfoliated to layers of nano scale and dispersed randomly in the matrix. As the content of clay increased, mechanical properties of composites increased before 3 phr loading and then decreased. Wet skid friction, especially flex cracking properties improved significantly with the adding of nano-clay. Rolling resistance, heat build-up and abrasive resistance were decreased relative to the composite with pure silica.5. Nano-clay/silica fillers were prepared by spray drying method, and the KH550 was used to modify the nano-clay/silica filler. The test results of TEM and XRD indicated that Silica and KH550 both have inserted into the clay layers. The incorporation of KH550 improved the dispersion of filler in rubber matrix and the interfacial strength between filler and rubber. Compared with the composites filled by silica, the tensile strength and tear strength of composites containing the filler modified by KH550 were increased by 12% and 8%, and cutting resistance, wet skid resistance and fatigue cracking performance were increased 80%,8% and 200% respectively. Heat build-up performance, wear resistance and the stress at 300% decreased by 10%,6%, and 9%, respectively.