TECHNICAL FIELD

The present invention relates to a sealant tire, and particularly to a sealant tire having noise reducing properties.

BACKGROUND ART

Tire cavity resonance, which is one source of road noise of vehicles, is resonance of the air inside the tire and thus lies in a low frequency range and can be very annoying in some vehicles. However, since it is resonance of the air inside the tire, such noise is very difficult to control by modifying vehicle bodies or tires. To solve this problem, for example, the following methods have been proposed and used in practice in which a sound-absorbing material is mounted inside a tire, or a Helmholtz type absorber is formed on or attached to a wheel. Further, the method of mounting a sound-absorbing material inside a tire may be carried out in practice by fixing a sound-absorbing material on the tread portion of a tire using an adhesive or fixing it using a resin belt.

In recent years, in addition to conventional run-flat tires and emergency puncture repair kits, sealant tires in which a puncture sealing layer is already placed inside the tire tread have been practically used as alternatives to spare tires carried on vehicles.

Moreover, various methods have been disclosed in which a sound-absorbing material and a sealant tire are combined to fix the sound-absorbing material inside the tire through a sealant layer (Patent Literature 1). However, these methods are all insufficient in terms of performance, processability, or other properties. Further, for practical use, the mass productivity needs to be improved.

CITATION LIST

Patent Literature

Patent Literature 1: JP 2011-20479 A

SUMMARY OF INVENTION

Technical Problem

The present invention aims to provide a sealant tire with excellent noise reducing properties and high productivity.

Solution to Problem

That is, the present invention relates to a sealant tire including a porous sound-absorbing material attached to the inner side of an innerliner through a sealant layer, the sealant layer containing 1 to 30 parts by weight of an inorganic filler per 100 parts by weight of butyl rubber.

The inorganic filler is preferably at least one selected from the group consisting of carbon black, silica, calcium carbonate, calcium silicate, magnesium oxide, aluminum oxide, barium sulfate, talc, and mica.

The porous sound-absorbing material preferably has a cross sectional area of 0.4% to 15% of a cross sectional area of a cavity of the tire mounted on a rim.

The porous sound-absorbing material preferably has a specific gravity of 0.005 to 0.06.

The porous sound-absorbing material is preferably a polyurethane sponge.

The porous sound-absorbing material preferably has a substantially constant width and a substantially constant cross-sectional shape.

The porous sound-absorbing material is preferably discontinuous.

The porous sound-absorbing material preferably has one discontinuity.

The discontinuous ends of the sponge are preferably overlapped.

The gap length between the discontinuous ends of the porous sound-absorbing material is preferably 80 mm or less.

Preferably, the porous sound-absorbing material has two discontinuities, and the ratio of the circumferential length of the shorter porous sound-absorbing material is 3% or less of the circumferential length of the longer porous sound-absorbing material.

The circumferential end face of the porous sound-absorbing material is preferably substantially perpendicular to the inner surface of a tread of the tire.

The circumferential end face of the porous sound-absorbing material preferably makes an angle of 10° to 80° with the inner surface of a tread of the tire.

Preferably, one or two taper angles relative to the inner surface of a tread of the tire are formed in the discontinuous end of the porous sound-absorbing material.

The difference in width between the porous sound-absorbing material and the sealant layer is preferably 1 to 40 mm.

The sealant layer preferably further contains, per 100 parts by weight of the butyl rubber, 100 to 400 parts by weight of polybutene and 1 to 10 parts by weight of a cross-linking agent.

The polybutene preferably has a number average molecular weight of 1,000 to 4,000.

The sealant layer preferably has a thickness of 1 to 4 mm.

The present invention also relates to a method for producing the above-described sealant tire, the method including:

a step of vulcanizing a tire;

a step of spirally extruding a sealant material;

a step of crosslinking; and

a step of attaching a porous sound-absorbing material.

Preferably, in the step of attaching a porous sound-absorbing material, a sponge of required size is mounted on a holder to attach the sponge to the tire.

Preferably, in the step of attaching a porous sound-absorbing material, a sound-absorbing material having a length in the tire circumferential direction which is required for processing two or more tires is loaded inside the tire and cut before attaching the sound-absorbing material.

Preferably, in the step of attaching a porous sound-absorbing material, a porous sound-absorbing material is continuously introduced and attached inside the tire through an opening of the tire to continuously attach the porous sound-absorbing material to the tire without changeover.

Preferably, the porous sound-absorbing material has been previously cut into a predetermined size in the tire width direction.

Advantageous Effects of Invention

The sealant tire provided by the present invention includes a porous sound-absorbing material attached to the inner side of an innerliner through a sealant layer, and the sealant layer contains 1 to 30 parts by weight of an inorganic filler per 100 parts by weight of butyl rubber. Therefore, the sealant tire has excellent noise reducing properties and high productivity.

