Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
2001-02-01
2003-05-13
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209180
Reexamination Certificate
active
06561244
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a tire having a rubber tread of a lug and groove configuration and of a co-extruded cap/base construction; wherein the tread cap is of a rubber composition which contains carbon black and is thereby of a black color; wherein a visible surface of at least one groove is of a rubber composition exclusive of carbon black and is of a non-black color and wherein said visible non-black colored rubber composition is a rubber layer which underlies said tread cap. Said visible non-black colored rubber is exclusive of any appreciable portion of, and preferably exclusive of, the surface of said tread lugs intended to be ground-contacting. In one aspect of the invention, said non-black colored rubber composition contains an amorphous precipitated silica reinforcement, preferably a pre-hydrophobated precipitated silica. In another aspect of the invention, said non-black colored rubber composition, and alternately, carbon black containing black colored rubber compositions adjoining said non-black colored rubber composition, is comprised a blend of at least one diene based elastomer and a brominated copolymer of isobutylene and p-methylstyrene together with an organo phosphite.
BACKGROUND OF THE INVENTION
Tires are typically provided with treads which contain carbon black reinforcement and which are therefore black in color.
Most tires have a rubber tread of a lug and groove configuration. Many tires are of a co-extruded cap/base construction, wherein the tread cap is an outer rubber layer which contains the lug and groove configuration for which the outer surfaces of the lugs are designed to be ground-contacting, and wherein the tread base is integral with and underlies the tread cap and is not normally intended to be ground-contacting. Such cap/base tire construction and such tread lug and groove configuration are well known to those having skill in such art.
It is appreciated that, for some tire treads, the tread lugs are in a form of individual lugs and may also be in a form of circumferential ribs. For the purposes of this invention tread lugs and ribs are referred to herein as tread lugs unless otherwise indicated.
Historically, it has sometimes been desirable to provide a tire with a tread of which at least a portion is of a non-black color so that the resulting tread is of a multiplicity of colors, namely black and at least one non-black color.
However, a significant disadvantage of tire treads having a non-black colored outer tread lug surface designed to be ground-contacting is:
(A) a tendency of such non-black colored tread lug surfaces to leave colored markings on the road over which they travel, which can conflict with and confuse colored road markings intended to aid or control vehicular traffic patterns and
(B) a tendency of the such non-black colored tread lug surfaces to become discolored, particularly unevenly discolored, as the outer surface of the tread lugs travel over, or are parked on, oily ground surfaces such as, for example, asphalt roads.
However, it sometimes still remains desirable to provide a tire with a tread of which at least a portion of the visible tread surface has a color which contrasts with the primary black color of the tire tread.
For purposes of this invention, it is intended to provide a black-colored tread of lug and groove configuration which is further configured with at least a portion of the visible surface of at least one of said tread grooves is of a non-black color, preferably a color which contrasts with black, and is of an integral rubber composition which is not carbon black reinforced, namely a rubber composition which is co-extruded with and co-vulcanized with the remainder of the tire tread and is therefore integral therewith.
Thus it is desired that the visible portion of the tire tread is of at least two different visible colors, namely black and at least one additional non-black color which is positioned as a visible portion of least one of said tread grooves and is essentially exclusive of the outer surface of any lug associated with, or a part of, said groove, which is intended to be ground-contacting.
In particular, for the purposes of this invention, such non-black colored, visible groove surface is reinforced with a particulate synthetic amorphous silica and is exclusive of carbon black. Preferably it is also exclusive of any appreciable amount of white colored titanium dioxide pigment.
Accordingly, for this invention, it is desired to provide a black-colored, carbon black reinforced tire tread with at least portion of the visible tread surface being of an integral, non-black colored rubber composition designed to have minimal, in any, contact with the road therefore having minimal, if any, effect upon the wear and traction characteristics of the tire tread. This is accomplished by substantially limiting the non-black colored component of the black-colored tire tread to one or more of the grooves of a tire tread having a lug and groove configuration.
Historically, for a tire tread of cap/base construction which is composed of lugs and grooves, it has previously been proposed to provide such a tread where a portion of the underlying tread base rubber composition extends through the tread cap and is exposed at the surface of the bottom of the tread grooves with a purpose of retarding, or preventing, rubber cracking at the bottom of the tread grooves. For example, see U.S. Pat. No. 5,397,616. However, a visibly multicolored tire tread is not seen to be contemplated.
Also, historically, a typical example of a component of a tire having a color which contrasts with the conventional black color of the tire is a tire sidewall in which a portion of the rubber is white in color resulting from a blend of rubber and titanium dioxide pigment in the absence of, or exclusive of, particulate carbon black reinforcement. Indeed, tires with white colored portions of their sidewalls are well known.
However, for tire treads, it is also appreciated that coloring pigments such as titanium dioxide, by itself, do not provide significant rubber reinforcement equivalent to rubber reinforcing carbon black. Therefore, such white colored tire components are conventionally limited to rubber compositions which do not need such a high degree of reinforcement such as for example, outer, visible, portions of tire sidewalls.
It is also appreciated that many non-black colored rubber compositions for tire components, particularly white sidewall components have a tendency to discolor as a result of various discoloring chemicals which may be contained in various rubber compositions which are adjacent to the colored rubber composition. Accordingly, it is a common practice to substitute non-discoloring chemicals for discoloring chemicals in such adjacent rubber compositions such as for example, non-discoloring antidegradants and non-discoloring rubber processing oils. Such practice is well known in the tire white sidewall art.
A coupling agent is often used for silica-containing rubber compositions to aid in enabling the silica to reinforce the rubber composition. Widely used coupling agents for such purpose are comprised of a moiety (e.g. an alkoxysilane moiety) which is reactive with hydroxyl groups (e.g. silanol groups) on the surface of the silica and another moiety (e.g. a polysulfide moiety) which is interactive with unsaturated elastomers which contain carbon-to-carbon double bonds in their elastomer backbone. Such silica coupling agent activity is believed to be well known to those skilled in such art.
However, if it is contemplated that a saturated elastomer be used, which inherently does not have carbon-to-carbon double bonds in its backbone, such as a halogenated (e.g. brominated) copolymer of isobutylene and p-methyl styrene, such elastomer does not inherently respond to sulfur bonding or crosslinking in the manner of unsaturated diene-based elastomers.
Accordingly, coupling agents for the silica which rely upon an interaction with diene-based elastomers which contain carbon-to-carbon double bonds uns
Balogh George Frank
Sandstrom Paul Harry
Zanzig David John
Maki Steven D.
The Goodyear Tire & Rubber Company
Young, Jr. Henry C.
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