Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Reexamination Certificate
1998-06-18
2001-09-25
Knable, Geoffrey L. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
C152S548000, C152S552000
Reexamination Certificate
active
06293327
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a pneumatic tubeless tire without an innerliner. Further, the present invention relates to a pneumatic tubeless tire without an innerliner particularly with superior durability of its bead portion.
BACKGROUND
Hitherto, with respect to a pneumatic tubeless tire, a low air permeable rubber such as butyl rubber has been employed for an innerliner to maintain air pressure of the tire.
FIG. 4
is a cross-sectional view of around a topping rubber layer for casecords of a conventional typical pneumatic tire. In
FIG. 4
, numeral
1
represents a topping rubber layer wherein casecords
4
are arranged usually in a line. On the portion inside from the casecord
4
, there is an innerliner
9
comprising butyl rubber or the like for maintaining air pressure of the tire, and on the portion outside from the the casecord
4
, there is provided a sidewall layer
10
. The innerliner occupies about 10% by weight of tire members constituting the tire and prevents the weight of the tire from decreasing.
On the other hand, in view of necessity for low fuel consumption, a lightweight tire is required and simplicity in the tire producing processes is also required. And, it is proposed that the topping rubber layer
1
is made of a rubber composition obtained by blending low air permeable butyl rubber and brominated isobutyl/p-methylstyrene copolymer and to leave out the innerliner
9
(refer to JP-A-55665/1994, JP-A-156007/1994 and JP-A-157648/1996).
Since a highly saturated rubber such as butyl rubber or the like is inferior in adhesion property to a diene rubber which is highly unsaturated rubber, adhesion between the topping rubber layer and other tire members such as the sidewall which contains a diene rubber as a main component is inferior and adhesion to casecords is also inferior, so that the tire to be obtained has a problem in its durability.
For example, in JP-A-157648/1996, there is disclosed, for balancing adhesion properties to casecords and low air permeability, that brominated isomonoolefin/p-alkylstyrene copolymer as a highly saturated rubber is employed for a rubber composition constituting the topping rubber layer.
To obtain such an effect, however, a blending amount of the above-mentioned copolymer must be not less than 50 parts by weight in practice and, therefore, there is a problem that adhesion to other tire members containing a diene rubber as a main component is inferior.
On the other hand, from the viewpoint of further improving durability of tire, for example, in JP-A-113007/1996 and JP-A-157648/1996, there is disclosed that a thickness of a carcass is adjusted to the specific thickness for improving durability of the rolled-up end portion around a bead portion. When the thickness of carcass itself is increased, however, the weight of the whole tire is also increased as a result.
Further, in conventional tires, since an amine antioxidant is used in general, there is a problem that resistance to flexing fatigue of the rubber composition is lowered with lapse of time.
As described above, any lightweight pneumatic tubeless tire without an innerliner having a topping rubber layer, which has a low air permeability and sufficient adhesion to both of the other tire members containing a diene rubber as a main component and casecords, has not been obtained.
An object of the present invention is to provide a lightweight pneumatic tubeless tire without an innerliner in which adhesion properties of the topping rubber layer to casecords and other tire members containing a diene rubber as a main component and durability are both excellent.
Another object of the present invention is to provide a pneumatic tire without an innerliner having a particularly excellent durability around its bead portion.
SUMMARY OF THE INVENTION
The present invention relates to an improvement of a pneumatic tubeless tire having no innerliner and having a topping rubber layer which includes aligned casecords therein; the improvement comprising that a rubber composition for the topping rubber layer contains no plasticizer and comprises 100 parts (part by weight, hereinafter the same) of a rubber component consisting essentially of 50 to 90% (% by weight, hereinafter the same) of a diene rubber and 50 to 10% of brominated isobutylene/p-methylstyrene copolymer, and 1 to 10 parts of a tackifier.
Further, the present invention relates to an improvement of a pneumatic tubeless tire having no innerliner and having a topping rubber layer which includes aligned casecords therein; the improvement comprising that the topping rubber layer comprises an inner rubber layer provided on the inside from the aligned casecords and an outer rubber layer provided on the outside from the aligned casecords, and that a rubber composition for the inner rubber layer contains no plasticizer and comprises 100 parts of a rubber component consisting essentially of 50 to 90% of a diene rubber and 50 to 10% of brominated isobutylene/p-methylstyrene copolymer and 1 to 10 parts of a tackifier.
Further, the present invention relates to an improvement of a pneumatic tubeless tire having no innerliner and having a topping rubber layer which includes aligned casecords, wherein an end portion of said topping rubber layer is rolled up around a bead portion and the rolled-up topping rubber layer is overlapped with the remaining topping rubber layer; the improvement comprising, that a rubber composition for the topping rubber layer contains an amine-ketone antioxidant but contains no plasticizer and comprises 100 parts of a rubber component consisting essentially of 50 to 90% of a diene rubber and 50 to 10% of a halogenated butyl rubber or brominated isobutylene/p-methylstyrene copolymer and 1 to 10 parts of a tackifier, and that, after vulcanization, a minimum distance between the aligned casecords in the remaining topping rubber layer and the aligned casecords in the rolled-up topping rubber layer is not less than 0.1 mm.
In that case, preferably, the topping rubber layer comprises an inner rubber layer on the inside from the aligned casecords and an outer rubber layer provided on the outside from the aligned casecords, and the inside rubber layer contains an amine-ketone antioxidant but contains no plasticizer and comprises 100 parts of a rubber component consisting essentially of 50 to 90% of a diene rubber and 50 to 10% of a halogenated butyl rubber or brominated isobutylene/p-methylstyrene copolymer and 1 to 10 parts of a tackifier.
REFERENCES:
patent: 4279284 (1981-07-01), Spadone
patent: 5484005 (1996-01-01), Morehart et al.
patent: 5580513 (1996-12-01), Patitsas et al.
patent: 5688343 (1997-11-01), Minami et al.
patent: 5879485 (1999-03-01), Sakamoto et al.
patent: 0475733A (1992-03-01), None
patent: 0604834A (1994-07-01), None
patent: 0705717A (1996-04-01), None
patent: 0711642A (1996-05-01), None
patent: 6-156007 (1994-06-01), None
patent: 8-157648 (1996-06-01), None
patent: WO 9201744A (1992-02-01), None
English Abstract for JP 08-157,648, Patent Abstracts of Japan, Jun. 18, 1996.
Kuroda Yutaka
Minagawa Yasuhisa
Muraoka Kiyoshige
Birch & Stewart Kolasch & Birch, LLP
Knable Geoffrey L.
Sumitomo Rubber Industries Ltd.
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