JP2012071722A5 - - Google Patents

Description

The physical property index determined by the above formula (1) increases as E * decreases and tan δ increases. A low E * indicates that the adhesion of the ground contact portion S to the road surface is high. On the other hand, a high tan δ indicates a large energy loss during braking after the contact between the ground contact portion S and the road surface. The value of the measurement temperature of 0 ° C. is related to the characteristics of the situation where the ground contact portion S is difficult to adhere to the road surface. From these findings, the inventors have a value of tan δ (0 ° C.) of 0.375 or more, a value of E * (0 ° C.) of 40 [MPa] or less, and tan δ (0 ° C.) and E *. (0 ° C.) properties index determined above following formula (1) from the value of the case where 9.375 [MPa ^-1] or more, an excellent braking performance on wet road revealed that exerted.
Further, the physical property index obtained from the above equation (1) from the values of tan δ (20 ° C.) and E * (20 ° C.) relates to the characteristics in the situation where the ground contact portion S is relatively close to the road surface. From these findings, the inventors have a value of tan δ (20 ° C.) of 0.170 or more, a value of E * (20 ° C.) of 18 [MPa] or less, and tan δ (20 ° C.) and E *. properties index determined above following formula (1) from the value of (20 ° C.) is when it is 9.444 [MPa ^-1] above, revealed that excellent braking performance on a dry road are exhibited.
In addition, the RRC index correlates with the loss tangent tan δ, which is an index of the elastic modulus of the contact surface, and it is known that the RRC index decreases as tan δ (60 ° C.) decreases. In this regard, it has been clarified that fuel efficiency can be reduced when the value of tan δ (60 ° C.) is 0.14 or less. And with this fuel efficiency reduction, it was clarified that excellent high-speed turning performance can be obtained when the value of E * (60 ° C.) is 8 [MPa] or more.

* 1 SIR (Standard Indonesian Rubber)
* 2 “Nipol (registered trademark) 1712” manufactured by Nippon Zeon Co., Ltd.
* 3 “Nipol (registered trademark) NS116” manufactured by Nippon Zeon Co., Ltd.
* 4 "Nipol (registered trademark) NS616" manufactured by Nippon Zeon Co., Ltd.
* 5 “Nipol (registered trademark) BR1220” manufactured by Nippon Zeon Co., Ltd.
* 6 “Seast KH” manufactured by Tokai Carbon Co., Ltd.
* 7 "Zeosil (registered trademark) 115GR" manufactured by Rhodia
* 8 “Agilon 400G-D” manufactured by PPG Industries.
* 9 "Si-75" manufactured by Evonic-Degussa
* 10 Three types of zinc oxide * 11 “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 12 “NOCRACK 224” manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 13 microcrystalline wax * 14 Struktol Company of America, Ltd., "S tr uktol (registered trademark) EF44"
* 15 “Noxeller CZ-G” manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 16 “Noxeller NS-P” manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 17 “Noxeller D” manufactured by Ouchi Shinsei Chemical Co., Ltd.

[Correlation between material properties and tire performance]
The correlation between the material physical properties (tan δ, E *, WET physical property index, DRY physical property index) and tire performance scores (WET braking performance, DRY braking performance, high-speed turning performance, RRC index) shown in Table 1 is shown in FIG. This is shown in the chart of FIG. 2 to 5 are plotted values A of Comparative Example 1, B is a value of Comparative Example 2, C is a value of Comparative Example 3, D is a value of Example 1, and E is an implementation. The value of Example 2, F is the value of Example 3, and G is the value of Example 4.

FIG. 3 is a chart showing the correlation between the DRY physical property index (1000 × tan δ (20 ° C.) / E * (20 ° C.)) and the DRY braking performance. As shown in FIG. 3, the DRY physical property index and the DRY braking performance show a very strong correlation. From the plots of Comparative Examples 1 to 3 and Examples 1 to 4, an approximate curve of R2 = 0.9158 was obtained. From this approximate curve, it has been clarified that when the DRY physical property index is 9.444 [MPa ⁻¹ ] or more, the DRY braking performance target value of 4.0 or more is satisfied. Moreover, based on the value of the DRY physical property index of Comparative Examples 2 and 3 (Plots B and C) and Examples 1 to 4 (Plots D to G) in which the DRY braking performance becomes the target value 4.0 or more, a more preferable value E * (20 ° C.) is 18 [MPa] or less and tan δ (20 ° C.) is 0.170 or more.

[Example 3]
The tire composition of Example 3 had a composition containing 80 parts by weight of silica with respect to 100 parts by weight of a polymer part including 20 parts by weight of natural rubber, 65 parts by weight of S-SBR, and 15 parts by weight of BR. This S-SBR is a non-oil-extended styrene / butadiene rubber, and is also a terminal-modified polymer for blending with silica.
Otherwise, the silane coupling agent (6.4 by weight part), zinc oxide (3 parts), stearic acid (1 part by weight), naphthenic oil (20 parts by weight), 2 types of anti-aging agent (respectively 3. 5 parts by weight and 2 parts by weight), microcrystalline wax (2 parts by weight), zinc fatty acid (3 parts by weight), sulfur (1.7 parts by weight), two types of vulcanization accelerators (2.2 parts by weight and 0.7 parts by weight). The content is a value relative to 100 parts by weight of the polymer part.
As shown in Table 1, in the tire composition of Example 3, all of the WET braking test, the DRY braking test, the high-speed turning test, and the RRC index satisfy the target values. Since the tire composition of Example 3 uses natural rubber to reduce the amount of S-SBR used, the cost of the polymer can be reduced. In addition, the composition is designed to reduce the cost of the polymer by adding the silane coupling agent and increasing the amount of silica, and the tire performance meets the target value.