Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
1998-03-17
2001-05-15
Ball, Michael W. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C524S307000, C524S524000
Reexamination Certificate
active
06230773
ABSTRACT:
FIELD
This invention relates to a tire and more particularly to a pneumatic tire designed for optional use without internal air pressure.
BACKGROUND
Tire constructions have been suggested for pneumatic tires which are designed to be run without internal pneumatic pressure, other than ambient atmospheric pressure.
For example, tires have been suggested which have special sidewall inserts designed to improve sidewall stiffness, thereby reducing, or inhibiting, the tire's tendency to go flat without internal air pressure. (see, for example, U.S. Pat. No. 5,368,082). Also, tires have been suggested which have additional plies, such as tires having a total of three plies in their sidewalls, to enhance, or substantially maintain, the tire's performance when running without internal air pressure. (see, for example, U.S. Pat. Nos., 5,427,166 and 5,511,599).
For this invention, it is desired to provide a tire with inserts in its sidewall portion(s) which have enhanced stiffness related properties.
In the description of this invention, the term “phr” where used, relates to parts by weight of specified material, or ingredient, per 100 parts by weight rubber, in a rubber based composition. Such term is well known to those having skill in such art.
Such terms as “compound” or “rubber compound” or “rubber composition” are used interchangeably. The term “compounding ingredient” refers to ingredients, usually including the elastomers themselves, that are blended to form a rubber compound. Such terms are well known to those having skill in such art.
In the description of this invention, the viscoelastic properties E′ and Tangent (Tan.) delta values art determined by a Rheovibron instrument at 11 hz at a one tenth percent strain. A Rheovibron instrument from the Tmass company is used. It is understood that use of a Rheovibron instrument and such method of measurement of E′ and Tan.Delta is understood by one having skill in the art. The E′ and Tan.Delta values are to be determined at 60° C.
The term “runflat” tire, where used, relates to a pneumatic tire which is designed to run without internal air pressure, under ambient conditions, for limited periods of time and speeds.
SUMMARY AND PRACTICE OF THE INVENTION
In accordance with this invention, a tire is provided comprised of a toroidally-shaped carcass and an outer, circumferential tread designed to be ground-contacting, wherein said carcass is comprised of two spaced apart inextensible bead portions, two spaced apart sidewalls each individually extending radially inward from and connecting said tread to said bead potions, and at least one cord reinforced ply extending from bead to bead and through the sidewalls; an improvement in which a substantially crescent shaped rubber insert is juxtapositioned to and axially inward of at least one of said carcass plies in each of said sidewalls or the tire; wherein the rubber composition of said insert has a Shore A hardness at 100° C. in a range of about 65 to about 85, a 100 percent Modulus in a range of about 3.5 to about 10 MPa, a Hot Rebound at 100° C. in a range of about 60 to about 80, an E′ value in a range of about 2 to about 20 MPa at 60° C. and a Tan.Delta value at 60° C. in a range of about 0.03 to about 0.15; and wherein said rubber composition of said insert is comprised of, based on 100 parts by weight rubber, (A) at least one diene-based elastomer, (B) about 30 to about 100 phr of particulate reinforcement as carbon black and, optionally, silica, and (C) about 0.5 to about 10 phr of at least one of dithiodipropionic acid, benzoic acid and salicylic acid.
Preferably, the material (C) is 3,3′ dithiodipropionic acid, although it is understood that it may exist in a 2,2′ isomeric form.
It is to be appreciated that the insert is sulfur co-cured with the tire assembly of said tread and carcass as a whole.
Preferably, the insert(s) have a maximum thickness at a location about midway between the bead portions and the tread in the sidewall region of the tire.
In one aspect of the invention, said dithiodipropionic acid, benzoic acid and/or salicylic acid are added by either (i) adding in-situ with ingredients for the said rubber composition or (ii) with the rubber composition as a composite of carbon black and/or silica pre-treated with at least one of said acids such as, for example, by organic solvent deposition or melt dispersion methods. For example, at least one of said acids may be adsorbed, absorbed, coated or melted, such as, for example, melt-spraying of molten material, onto the surface of said carbon black and/or silica filler.
By blending one or more of said acids, preferably the dithiodipropionic acid, in-situ with ingredients of the rubber composition, it is meant that it is added to and mixed with the rubber composition as an individual ingredient.
By pre-blending one or more of such acids, preferably the dithiodipropionic acid, with at least a portion of the carbon black and/or silica it is meant that it is pre mixed with the carbon black and/or silica prior to form a composite thereof and such composite is added to and mixed with ingredients for the rubber composition as an individual ingredient.
By mixing with ingredients for the rubber composition, it is meant that one or more of the said acids, or said composite, as the case may be, is blended with the elastomer(s) as well as conventional compounding ingredients used for the rubber composition for the insert, conventionally in an internal rubber mixer. It is preferred the said acid, preferably the dithiodipropionic acid, or said composite, as the case may be, is mixed with the compounding ingredients in the absence of curatives such as sulfur and vulcanization accelerators, and that such curatives are subsequently blended with the rubber composition after said acid or composite addition.
Alternatively, although not generally preferred, a portion of or all of the acid, or composite, may be added to the rubber composition with the curatives.
The dithiodipropionic acid may typically be characterized by having a melting point in the range of about 153 to about 159° C. Such melting point can conveniently be determined by a differential scanning calorimeter (DSC) at a heating rate of 10° C. per minute.
It is considered herein that the utilization of the said acids, particularly the 3,3′-dithiodipropionic acid, for the rubber filler composition is significant in order to enhance the stiffness of the sulfur vulcanized rubber composition of the insert as well as to endeavor to substantially maintain a relatively low hysteresis.
In the practice of this invention, a significant function of the rubber composition based fillers in the sidewall portion of the tire is to stiffen/support the sidewall structure when the tire is operated without inflation pressure.
The rubber composition based inserts are elastomeric in nature having a substantially crescent cross-sectional shape and material properties selected to enhance inflated ride performance while promoting the tire's run-flat durability. The inserts, if desired, may also be individually reinforced with cords or short fibers. Thus, one or more of such inserts may be so-reinforced.
The shape of the fillers is described as being substantially crescent in shape. This is intended to also include an entrunkated crescent shape, particularly where the entrunkated portion of the crescent shaped filler is juxtapositioned to the tire's bead portion.
In further practice of the invention, said tire carcass may have from one to three plies comprised of a first axially inner ply and optionally one or two additional plies as a second ply and third ply, respectively, each additional ply positioned sequentially axially outward from said first ply in the sidewall region of the tire.
Accordingly, in accordance with this invention said tire contains one ply in its carcass wherein said insert is juxtapositioned to and axially inward of said ply in the sidewall region of the tire.
In further accordance with this invention, said tire contains, in it
McQuate Raymond Dean
Sandstrom Paul Harry
Sinsky Mark Samuel
Ball Michael W.
Musser Barbara J.
The Goodyear Tire & Rubber Company
Young, Jr. Henry C
LandOfFree
Tire with sidewall carcass reinforcement does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tire with sidewall carcass reinforcement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tire with sidewall carcass reinforcement will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2477981