Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1995-03-14
1996-12-24
Cain, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524322, 524496, C08K 300
Patent
active
055874177
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a rubber composition for a tire tread, and particularly, it relates to a rubber composition for a tire tread suitable for a pneumatic tire for heavy load having excellent wear resistance.
BACKGROUND ART
Heretofore, as a filler for a rubber having a high reinforcing effect, a carbon black of an ISAF class is well known. However, in the pneumatic tire for heavy load in recent years, the carbon black which can improve wear resistance has been desired in accordance with demands of improved case durability, resource saving and good mileage.
Thus, the carbon black which can be used as the filler in the rubber composition for the tread of the tire for heavy load has also changed from the ISAF class to an SAF class.
By the way, in order to improve the wear resistance of rubber products such as the tires, it is already known that a high structure carbon black having a fine particle diameter is suitable.
The diameter of the fine particles of the carbon black can be determined by measuring the particles in an electron micrograph, but the thus measured particle diameter is an average value and in fact, it has a certain distribution.
Alternatively, the particle diameter can also be calculated by measuring the surface area of the carbon black, and for this measurement, an N.sub.2 SA method for determining from the amount of an adsorbed nitrogen gas and an iodine adsorption method (an IA method) are simple. These methods have been routinely employed in a quality control of a maker, an acceptance test of a user, and the like.
In measuring the surface area, a point to which much attention should be paid is whether a value obtained by the measurement principle denotes a whole surface area or an external surface area.
It is considered that small pores are present on the surfaces of the carbon black, and the whole surface area also includes the surface area in the pores, but the external surface area does not include the surface area in the pores. When the carbon black is kneaded as a reinforcing agent with a rubber, such giant molecules as in the rubber cannot get into the pores, and for this reason, the surface of the pores cannot be effectively utilized in practice.
Therefore, the external surface area of the carbon black is also called a rubber effective surface area sometimes. In order to determine this rubber effective surface area, there is used a surface area calculated from an amount of adsorbed cetyltriammonium bromide (CTAB) having a large molecular weight. This is called a CTAB method surface area. This CTAB method surface area has a unit of m.sup.2 /g, and it can be measured in accordance with ASTM D-3765-89.
On the other hand, the particles of the carbon black are not present singly but integrally like bunches of grapes, as seen from an electron microscope. This is called a structure. This structure can be classified into two kinds, and one is established by the mutual fusion of the particles, i.e., a chemical bond and the other is established by a physical bond such as a van der Waal force. The former non-destructive structure morphology is called a primary structure, and the latter deformable and destructive structure morphology is called a secondary structure. The structure can usually be evaluated by an absorption value of dibutyl phthalate (DBP). This principle is based on a phenomenon that the carbon black having high entanglement properties among the particles can absorb a larger amount of an oil.
A 24M4DBP absorption value is a value obtained by repeating a compression operation at a pressure of 24,000 psi four times and then measuring a DBP absorption value in accordance with ASTM D-3493, and this absorption value is an index for evaluating the skeleton structure properties of the carbon black mainly comprising the primary structure, used in measuring the DBP absorption value, on the basis of the non-destructive real structure morphology (the primary structure) to the exclusion of the DBP absorption value by the deformable and destructive structure mo
REFERENCES:
patent: 4895911 (1990-01-01), Mowdood et al.
"Carbon Blacks"; Cabot Corporation (1989).
Hashimoto Takatsugu
Kanou Kazuhiko
Nakane Shinsuke
Bridgestone Corporation
Cain Edward J.
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