Sumitomo Rubber Industries Limited

The Goodyear & Tire Rubber Company

Kei Kohara

Masaya Tsunoda

Hiroshi Ito

Takashi Tanaka

Naoki Sugiyama

Sakae Okubo

Izumi Saiwaki

Nobumitsu Iio

Masashi Yaguchi

Takeshi Imakita

The present invention provides an innerliner rubber composition having an excellent balance of sheet processability and air retention properties, and a pneumatic tire including the rubber composition. The present invention relates to an innerliner rubber composition, containing a rubber component; a mixture of a fatty acid metal salt and a fatty acid amide; an oil; and a C5 petroleum resin, the rubber component including, based on 100% by mass thereof, at least 70% by mass of a butyl-based rubber, the mixture being present in an amount of 0.8 to 3.2 parts by mass per 100 parts by mass of the rubber component, the mixture, the oil, and the C5 petroleum resin being present in a combined amount of 6.0 to 16.0 parts by mass per 100 parts by mass of the rubber component.

Rubber composition for inner liner and pneumatic tire

A pneumatic tirecomprises a carcasscomprising at least one carcass plyA extending between bead portionsvia sidewall portionsand a tread portion. The carcass plyA comprises strip-shaped ply pieceslonger in a tire radial direction than in a tire circumferential direction arranged circumferentially. Each of the ply piecescomprises a plurality of carcass cordsarranged in parallel in the tire radial direction and at least partly overlapping each other with the ply piecescircumferentially adjacent. At least one of the carcass cordsarranged in at least one of side edge portionsin the tire circumferential direction of each of the ply pieceshaving a diameter (Ce) smaller than a diameter (Cc) of at least one of the carcass cordsarranged in a center portionof each of the ply pieces

Pneumatic tire with carcass ply comprising plurality of partly overlapping strip-shaped ply pieces

In an inner mold method, a pull-out force of extracting inner mold segments from a vulcanized tire is reduced. A rigid inner moldis provided with an annular inner mold bodyhaving a tire molding surface S. A rigid coreis put into a vulcanization mold B for each green tire T formed on the tire molding surface S, whereby the green tire T is vulcanization-molded between the vulcanization mold B and the inner mold body. The inner mold bodycomprises a plurality of inner mold segmentsdivided in the circumferential direction. A coating layerhaving rubber release property is formed on the tire molding surface S.

Rigid inner mold for forming tire, and method of manufacturing tire using the same

A pneumatic tire to reduce separation of a carcass ply from inner and outer core pieces () and improve steering stability. A radially inner end portion of the carcass ply is held between the inner and outer core pieces () without turning-up around a bead core. The inner and outer core pieces () are made of helical body of bead cord () helically winding around a tire axis. In the inner core piece (), the final twisting direction of the bead cord () is the same as the winding direction around the tire axis of the bead cord () in side view from axial outward of the tire. In the outer core piece (), the final twisting direction of the bead cord () is opposite to the winding direction of the bead cord ().

Pneumatic tire having twisted bead cords

The present invention increases tire formation precision and is a tire manufacturing method, which comprises a step Sfor forming a green tire on the outer surface of a rigid inner mold and a vulcanization step Sfor vulcanizing the green tire. The rigid inner mold comprises: an inner mold body, which is obtained from multiple segments; a core, which substantially binds the various segments; and an outer diameter adjusting means for changing the outer diameter of the core by changing the temperature of the core. Moreover. the rigid inner mold performs changes such that by expansion of the outer diameter of the core, the various segments move outward in the radial direction of the tire and gaps between the segments are enlarged, while by reducing the outer diameter of the core, the various segments move inward in the radial direction of the tire and the level differences R on the outer surface between adjacent segments increase. The vulcanization step Scomprises an adjustment steps Sfor adjusting the outer diameter of the core using the outer diameter adjustment means so that the gaps G and the level differences R are within a previously established range.

Tire manufacturing method

Provided is a pneumatic tire which is configured so as to prevent carcass cords from biting into an inner liner, thereby improving the durability performance of the tire. A pneumatic tire () is provided with a carcass () which comprises, a carcass ply () extending from a tread () through side walls () to the bead cores () of bead sections (), the bead cores () each including an inner core () and an outer core (). The carcass, ply () is sandwiched between the inner cores () and the outer cores (). Each of an inner core () and an outer core () includes a bead cord () which is wound at least one turn in the circumferential direction of the tire. Each of the bead cords () includes an outermost layer () formed by twisting filaments () together. In at least one bead section, the outermost layer () of the bead cord () of each of the inner core () and the outer core () is twisted in the direction which allows the carcass ply () to easily move to the outside in the radial direction of the tire from between the inner core () and the outer core ().

Pneumatic tire

Provided is a rigid core for tire formation that limits the rubber stuck between inner mold segments in an inner mold segment while minimizing the occurrence of unevenness in the radial direction between inner mold segments that is caused by thermal expansion. A core main bodyis divided into: a first inner mold segmentA in which both circumferential end surfacesAs are inclined radially inward in a direction in which the circumferential width increases; a second inner mold segmentB that is arranged in an alternating manner with the inner mold segmentA and in which both circumferential end surfacesBs are inclined radially inward in a direction in which the circumferential width decreases; and a butting memberthat is arranged between the first inner mold segmentA and the second inner mold segmentB. Young's modulus Ea of the butting memberis smaller than Young's modulus Eb of the first and second inner mold segmentsA andB.

A core main body comprises first core segments having a small circumferential width and having both circumferential end surfaces as first butting surfaces, and second core segments having a large circumferential width and having both circumferential end surfaces as second butting surfaces, the core main body is formed into an annular shape by butting the circumferentially adjacent first and second butting surfaces against each other. The first butting surface comprises a parallel surface portion being parallel with a center plane in the circumferential width of the first core segment connected to radially outside of an outwardly inclined surface portion inclined so that the circumferential width increases toward the inside in a radial direction.

Rigid core for forming tire

Provided is a rigid core for forming a tire, configured so that the intrusion of rubber into a gap between core segments is prevented and so that the lowering of roundness of a core body s prevented. The core body comprises a plurality of circumferentially divided core segments. Both circumferential end surfaces of each of the core segments are used as mating surfaces, and the mating surfaces adjacent to each other in the circumferential direction are abutted against each other to form the core body. At least one of the mating surfaces adjacent to each other in the circumferential direction is formed as a stepped mating surface comprising a bordering surface region extending along an outer circumferential edge of the mating surface, and a recessed surface region surrounded by the bordering surface region and recessed in a step shape from the bordering surface region so that only the bordering surface region contacts with the adjacent mating surface.

A rigid core for forming a tire is configured so that the non-uniformity of the amount of thermal expansion of the core body is reduced to improve the quality of the tire. The core body comprises divided core pieces () divided inward and outward in a tire radial direction at a tire radial position (P) including a maximum width position (P) of the tire forming surface. Outward divided core pieces () disposed outward in the tire radial direction than the maximum width position (P) and inward divided core pieces () disposed inward in the tire radial direction than the maximum width position (P) are respectively formed of metal materials different from each other in coefficient of thermal expansion. The coefficient of thermal expansion of the inward divided core piece () is higher than a coefficient of thermal expansion of the outward divided core piece ().

A tire vulcanization mold comprises a mold body having an inner surface for molding a tire outer surface and at least one vent passage for the escape of gas in the mold during vulcanization, the vent passage with an inlet end and an outlet end, the inlet end being opened on the inner surface of the mold body, the outlet end communicating with an exterior of the mold body, wherein the vent passage communicates with the inner surface of the mold body at an angle of not less than 60 degrees, and less than 90 degrees with respect to a normal line perpendicular to the inner surface at the inlet end.

Growing community of inventors

Kobe, Japan

Kei Kohara