JP6758088B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Conventionally, various pneumatic tires having a tread rubber including a tread surface rubber layer located on the outermost surface of the tread and a tread inner rubber layer located inside the tread surface rubber layer in the tire radial direction have been proposed. (For example, Patent Document 1). In such a pneumatic tire, generally, the tread surface rubber layer is a rubber layer having a relatively high modulus, and the rubber layer inside the tread is a rubber layer having a relatively low modulus. The input from the road surface to the tire is absorbed by the tread inner rubber layer having a relatively low modulus, for example, hysteresis loss is suppressed and the rolling resistance performance of the tire is improved.

Japanese Unexamined Patent Publication No. 2014-162242

By the way, in the above-mentioned pneumatic tire, the rigidity (land rigidity) of the tire against the lateral force generated when the vehicle turns is not sufficient due to the relatively low modulus of the rubber layer inside the tread. In some cases, the stability was not sufficient.
However, if it is simply attempted to increase the rigidity of the tire when the vehicle is turning, the wet performance, which is the running performance when traveling on a wet road surface, may not be sufficient in some cases. Specifically, when the rigidity of the entire tread becomes high, when the tire touches the road surface, it is difficult for the tread rubber surface to sufficiently follow the unevenness of the road surface on a micro scale, and it is difficult to obtain a high actual contact area. It has been found that there is a tendency and therefore it may be difficult to achieve sufficiently high wet performance.

Therefore, an object of the present invention is to provide a pneumatic tire capable of sufficiently improving wet performance while increasing the rigidity when the vehicle turns.

The pneumatic tire of the present invention is a pneumatic tire including a tread surface rubber layer located on the outermost surface of the tread and a tread inner rubber layer located inside the tread surface rubber layer in the tire radial direction. And
The 100% modulus of the inner tread rubber layer is greater than the 100% modulus of the tread surface rubber layer.
The tan δ of the rubber composition forming the tread surface rubber layer at 0 ° C. is 0.5 or less.
The difference between tan δ at 30 ° C. and tan δ at 60 ° C. of the rubber composition is 0.070 or less.
The rubber composition is characterized by having a kinematic strain of 1% and a storage elastic modulus at 0 ° C. of 20 MPa or less.
According to the pneumatic tire of the present invention, the wet performance can be sufficiently improved while increasing the rigidity when the vehicle turns.

In the present invention, "100% modulus" means that a dumbbell-shaped No. 3 sample is prepared in accordance with JIS K6251 and subjected to a tensile test under the conditions of room temperature of 23 ° C. and speed of 500 ± 25 mm / min. It is the measured tensile stress at 100% elongation. Further, in the present invention, the tread rubber means a rubber that does not include a member such as a belt arbitrarily included in the tread portion.

Here, in the pneumatic tire of the present invention, the rubber composition comprises a rubber component (A) containing 50% by mass or more of at least one isoprene-based rubber selected from the group consisting of natural rubber and synthetic isoprene rubber. Containing a thermoplastic resin (B) and a filler (C) containing 70% by mass or more of silica,
In the rubber composition, the blending amount of the thermoplastic resin (B) is preferably 5 to 40 parts by mass with respect to 100 parts by mass of the rubber component (A).
According to this configuration, the wet performance of the land area can be further improved.

Further, in the pneumatic tire of the present invention, the tread tread is partitioned by a tread ground contact end and a circumferential main groove continuously extending in the tire circumferential direction, or is adjacent to each other and continuously in the tire circumferential direction. It is preferable to provide at least one rib-shaped land portion, which is partitioned by two extending circumferential main grooves.
According to this configuration, the wet performance can be further improved while increasing the rigidity of the land portion in the tire circumferential direction.

In the present invention, the "rib-shaped land portion" is provided with a groove in which both ends open in the circumferential main groove forming the land portion and the tread ground contact end, and the opening width to the tread tread is more than 1.5 mm. Refers to the land area that is not installed. In other words, the ribbed land portion refers to a land portion that is not provided with a groove that crosses the land portion.

Further, in the pneumatic tire of the present invention, both ends of the ribbed land portion are provided on both the tread ground contact end and the circumferential main groove, or on both of the two circumferential main grooves. The ribbed land portion is not provided with an opening sipe at both ends to open, and one end thereof is one of the tread ground contact end and the circumferential main groove, or two circumferential main grooves. It is preferable that one of the tires is provided with an opening sipe at one end, and the other end is terminated within the ribbed land portion.
According to this configuration, the wet performance can be further improved while maintaining the circumferential rigidity of the land portion.

In the present invention, the term "sipe" refers to a no-load state in which a tire is attached to a rim and an internal pressure of 30 kPa, which is a pressure sufficient to maintain the shape of the tire, is applied (hereinafter, "a tire is attached to the rim and the tire is used". A "no-load state" in which an internal pressure of 30 kPa, which is a pressure for maintaining the shape, is applied is also referred to as a "low-pressure no-load state"), and the opening width to the tread tread is 1.5 mm or less. Further, the “groove” means a groove having an opening width to the tread tread of more than 1.5 mm in a low pressure and no load state.
The above "rim" is an industrial standard that is effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) JATMA YEAR BOOK, and in Europe, ETRTO (The European Tire and). STANDARDS MANUAL of Rim Technical Organization), YEAR BOOK of TRA (The Tire and Rim Association, Inc.) in the United States, etc. Rim, TRA's YEAR BOOK refers to Tire Rim) (ie, the "rim" above includes sizes that may be included in the industry standards in the future in addition to the current size. As an example, the size described as "FUTURE DEVELOPMENTS" in the STANDARDS MANUAL 2013 edition of ETRTO can be mentioned.) However, if the size is not described in the above industrial standard, the bead width of the tire A rim with a corresponding width.
Hereinafter, unless otherwise specified, the dimensions and the like of each element of the tread tread shall be measured on the developed view of the tread tread under a low pressure and no load state.

Further, in the pneumatic tire of the present invention, the one-end opening sipe extends from the other end in the tire circumferential direction to a circumferential sipe portion and extends from the circumferential sipe portion in the tire width direction to the circumferential main groove or tread. It is preferable to provide a width direction sipe portion that opens to the ground end.
According to this configuration, the wet performance can be effectively improved while maintaining the circumferential rigidity of the land portion.

Further, in the pneumatic tire of the present invention, it is preferable that the rib-shaped land portion is provided with both-end closed sipes having both ends terminated in the rib-shaped land portion.
According to this configuration, the wet performance can be improved more effectively while maintaining the circumferential rigidity of the land portion.

According to the present invention, it is possible to provide a pneumatic tire capable of sufficiently improving wet performance while increasing the rigidity when the vehicle turns.

It is a tire width direction schematic sectional view of the pneumatic tire which concerns on 1st Embodiment of this invention. It is a developed view which shows the tread pattern of the pneumatic tire shown in FIG. It is a figure for demonstrating the wet performance of (a) a wide radial tire, and (b) is a figure for demonstrating the wet performance of a narrow radial tire. It is a developed view which shows the tread pattern of the pneumatic tire which concerns on 2nd Embodiment of this invention. It is a developed view which shows the tread pattern of the pneumatic tire which concerns on 3rd Embodiment of this invention. It is a tire width direction schematic cross-sectional view of the tire width direction half of the pneumatic tire which concerns on 4th Embodiment of this invention. It is a schematic plan view which shows the 1st example of a belt structure. It is a schematic plan view which shows the 2nd example of a belt structure. It is a schematic plan view which shows the 3rd example of a belt structure. It is a tire width direction schematic cross-sectional view of the tire width direction half of the pneumatic tire which concerns on 5th Embodiment of this invention. FIG. 5 is a schematic partial cross-sectional view in the tire width direction of a half portion of the pneumatic tire according to the sixth embodiment of the present invention.

Hereinafter, a pneumatic tire (hereinafter, also simply referred to as “tire”) according to the first embodiment of the present invention will be described in detail with reference to the drawings. The following description and drawings are examples for explaining the tire according to the present invention, and the present invention is not limited to the described and illustrated forms.

As shown in FIG. 1, the pneumatic tire 1 of the first embodiment has, for example, a carcass 22 composed of a carcass ply having a radial arrangement code straddling a pair of bead portions 21 in a toroidal shape, and a tire radius of the carcass 22. It is provided with at least a tread rubber 23 provided on the outer side of the direction.
More specifically, the tread portion 24, a pair of sidewall portions 25 extending inward in the tire radial direction continuously to the side portions of the tread portion 24, and continuous to the inner end of each sidewall portion 25 in the tire radial direction. In addition to being provided with a bead portion 21, a carcass 22 made of one or more carcass plies extending from one bead portion 21 to the other bead portion 21 in a toroidal manner to reinforce each of the above portions is provided. A bead core is embedded in the bead portion 21. Further, as a reinforcing member of the bead portion 21, a rubber chafer is provided on the outer surface of the bead portion 21, and a belt 26 composed of one or more belt layers is provided on the crown portion of the carcass 22. Further, a tread rubber 23 is provided on the outer side of the crown portion of the carcass 22 in the tire radial direction.

Further, in the tire 1, as shown in FIG. 1, the tread rubber 23 includes a tread surface rubber layer 23a located on the outermost surface of the tread and a tread inner rubber located inside the tread surface rubber layer 23a in the tire radial direction. Layer 23b and the like. Further, the 100% modulus of the tread inner rubber layer 23b is larger than the 100% modulus of the tread surface rubber layer 23a. In the tire 1 of the present embodiment, the number of rubber layers constituting the tread rubber 23 can be three or more, in other words, a plurality of tread inner rubber layers 23b can be provided.

The tan δ at 0 ° C. of the rubber composition forming the tread surface rubber layer 23a of the tread rubber 23 of the tire 1 of the present invention is 0.5 or less, and the tan δ at 30 ° C. and the tan δ at 60 ° C. of the rubber composition. The difference from the tread is 0.070 or less, the dynamic strain of the rubber composition is 1%, and the storage elastic modulus at 0 ° C. is 20 MPa or less. Further, the rubber composition contains a rubber component (A) containing 50% by mass or more of at least one isoprene-based rubber selected from the group consisting of natural rubber and synthetic isoprene rubber, a thermoplastic resin (B), and silica. The filler (C) containing 70% by mass or more is contained, and the blending amount of the thermoplastic resin (B) in the rubber composition is 5 to 40 parts by mass with respect to 100 parts by mass of the rubber component (A). be able to.

Here, the action and effect of the tire 1 of the present invention will be described.
In the present invention, by making the 100% modulus of the tread inner rubber layer 23b larger than the 100% modulus of the tread surface rubber layer 23a, the tread inner rubber layer 23b having a relatively large modulus exerts a lateral force when the vehicle turns. Even if it occurs, it can be countered, so that the rigidity of the tire 1 when the vehicle turns can be sufficiently increased. On the other hand, when the modulus of the rubber layer 23b inside the tread is increased, the rigidity of the entire tread is increased, and therefore, there is room for improvement in the wet performance, which is the running performance when traveling on a wet road surface. Specifically, since the rigidity of the entire tread is high, it is difficult for the tread rubber surface to sufficiently follow the unevenness of the road surface when the tire touches the road surface, and the actual contact area when the tire touches the road surface. Tend to decrease. That is, on a micro scale, there is a part on the tread surface that is separated from the road surface, and even if the area of the tread tread T is the same, the actual contact area tends to be relatively low, and the wet performance is as expected. It was found that there may be no significant improvement in.
In the present invention, the rubber composition forming the tread surface rubber layer 23a of the tread rubber 23 has a dynamic modulus of 1% and a storage elastic modulus (E') at 0 ° C. of 20 MPa or less, whereby the rubber composition at a low temperature is formed. Since the flexibility of the tread rubber is improved and the ground contact performance of the tread rubber is improved, the tread surface can be brought into contact with the road surface on a micro scale, and the substantial contact area can be increased. Therefore, according to this pneumatic tire, it is possible to improve the wet performance while increasing the rigidity when the vehicle turns.

Further, the fuel consumption performance of the tire is related to the loss tangent (tan δ). In this pneumatic tire, by setting the tan δ at 0 ° C. to 0.5 or less, the fuel consumption of the tire to which the rubber composition is applied at a low temperature. Performance is improved.
Further, by relatively lowering tan δ at 60 ° C., the fuel efficiency performance of the tire to which the rubber composition is applied during normal running is improved.
Further, by setting the difference between tan δ at 30 ° C. and tan δ at 60 ° C. to 0.070 or less, the temperature dependence of tan δ becomes small, and the fuel consumption of the tire to which the rubber composition is applied over a wide temperature range. It is possible to improve the performance.
The friction coefficient (μ) on a wet road surface is proportional to the product of the rigidity of the tread rubber, the amount of deformation of the tread rubber, and the loss tangent (tan δ), but this tire has a loss tangent (tan δ) at a low temperature. ) Can be compensated for by increasing the amount of deformation of the tread rubber while ensuring the rigidity of the tread rubber, so that the friction coefficient (μ) on a wet road surface can be sufficiently maintained. Therefore, this tire has a low loss tangent (tan δ) at a low temperature, has high fuel efficiency at a low temperature, and has a high coefficient of friction (μ) on a wet road surface, thereby ensuring sufficient wet performance. be able to.

Further, as in this embodiment, the rubber composition forming the tread surface rubber layer 23a is a rubber component containing 50% by mass or more of at least one isoprene-based rubber selected from the group consisting of natural rubber and synthetic isoprene rubber. The rubber component (A), the thermoplastic resin (B), and the filler (C) containing 70% by mass or more of silica are contained, and the compounding amount of the thermoplastic resin (B) in the rubber composition is the rubber component ( A) It is preferably 5 to 40 parts by mass with respect to 100 parts by mass.
Since the tread surface rubber layer 23a is formed from the rubber composition having the above composition, it is possible to improve the followability of the tread surface to the road surface, increase the actual contact area with respect to the road surface, and further improve the wet performance. .. Specifically, in the rubber composition of the tread surface rubber layer 23a, by blending a predetermined amount of the thermoplastic resin (B), the decrease in elastic modulus in the low strain region is suppressed, and the elastic modulus in the high strain region is suppressed. The elastic modulus can be reduced. Therefore, in the tread surface rubber layer 23a, the deformed volume of the tread rubber in the vicinity of the contact patch with the road surface having a large strain during running is increased, and the rubber composition is lowered in elasticity to bring the tread surface to the road surface on a micro scale. It can be brought into contact, and the substantial contact area can be further increased. On the other hand, the rigidity of the tread rubber can be ensured because the distortion during running is small in the portion far from the contact patch with the road surface. Therefore, by forming the tread surface rubber layer 23a from the above rubber composition, the wet performance on a micro scale can be further improved.

Further, by setting the content of the isoprene-based rubber in the rubber component (A) to 50% by mass or more, the loss tangent (tan δ) at a low temperature, particularly at 0 ° C. can be effectively reduced, and 0 ° C. The tan δ in the above can be 0.5 or less. Further, by setting the content of silica in the filler (C) to be blended to 70% by mass or more, tan δ at 60 ° C. can be effectively reduced.
The loss tangent (tan δ) at 0 ° C., 30 ° C. and 60 ° C. and the storage elastic modulus (E') at 0 ° C. were measured by vulcanizing the rubber composition at 145 ° C. for 33 minutes. The vulcanized rubber can be measured using a spectrometer under the conditions of an initial strain of 2%, a dynamic strain of 1%, and a frequency of 52 Hz.

Here, the tread rubber having the above-mentioned physical properties and rubber composition of the tire according to the first embodiment of the present invention will be described below.

[Tread rubber]
In the tread rubber, the 100% modulus of the inner tread rubber layer is larger than the 100% modulus of the tread surface rubber layer. Further, in the present embodiment, from the viewpoint of optimizing the rigidity of the tread when the vehicle turns, the 100% modulus of the rubber layer inside the tread is 1.05 to 2.50 times that of the 100% modulus of the rubber layer on the surface of the tread. It is preferably 1.10 to 2.00 times, more preferably.
The 100% modulus of the tread surface rubber layer is preferably 1.1 to 4.0 MPa, more preferably 1.6 to 2.4 MPa. The 100% modulus of the inner rubber layer of the tread is preferably 1.15 to 10 MPa, more preferably 1.2 to 8.0 MPa. Further, the 100% modulus of each rubber layer can have the above relationship by arbitrarily adjusting the rubber component (A) and the additive component (B), or by a known method.

The thickness of the tread surface rubber layer is the maximum thickness in the region of 15% or less of the tread width from the tire equatorial plane to the outside in both tire width directions in the cross-sectional view in the tire width direction. It is preferable that the thickness is 0.1 to 0.9 times the thickness of the tread rubber at the measured position. While increasing the rigidity of the tread when turning the vehicle, it is possible to prevent the rigidity of the entire tire from becoming too low. The thickness of the tread rubber and the tread surface rubber layer means the length measured along the tire radial direction.
From the same viewpoint, the thickness of the tread surface rubber layer is more preferably 0.5 to 0.9 times the thickness of the tread rubber, and even more preferably 0.7 to 0.8 times. Is.

When the tread rubber has three or more rubber layers (when there are a plurality of tread inner rubber layers), the magnitude relationship of 100% modulus of each tread inner rubber layer other than the tread surface rubber layer is arbitrary. be able to. Further, in such a case, it is sufficient that the 100% modulus of at least one tread inner rubber layer is 100% greater than the tread surface rubber layer, and preferably all the tread inner rubber layers are larger than the tread surface rubber layer.

[Tread surface rubber layer]
The tread surface rubber layer has a tan δ at 0 ° C. of 0.5 or less, a difference between tan δ at 30 ° C. and tan δ at 60 ° C. of 0.070 or less, a dynamic strain of 1%, and a storage elastic modulus at 0 ° C. It is formed from a rubber composition having a pressure of 20 MPa or less. Further, in this embodiment, the rubber composition contains a rubber component (A) containing 50% by mass or more of at least one isoprene-based rubber selected from the group consisting of natural rubber and synthetic isoprene rubber, and a thermoplastic resin ( In the rubber composition containing B) and a filler (C) containing 70% by mass or more of silica, the blending amount of the thermoplastic resin (B) is 5 to 5 with respect to 100 parts by mass of the rubber component (A). It is 40 parts by mass.

Here, the rubber composition of the tread surface rubber layer 23a has a tan δ at 0 ° C. of preferably 0.45 or less, more preferably 0.4 or less, from the viewpoint of improving fuel efficiency at low temperatures. The lower limit of tan δ at 0 ° C. is not particularly limited, but tan δ at 0 ° C. is usually 0.15 or more. If the tan δ of the rubber composition at 0 ° C. exceeds 0.5, the fuel efficiency of the tire at a low temperature cannot be sufficiently improved.

Further, the rubber composition preferably has a tan δ at 30 ° C. of 0.4 or less, more preferably 0.35 or less, and usually 0.1 or more. Further, the rubber composition preferably has a tan δ at 60 ° C. of 0.35 or less, more preferably 0.3 or less, and usually 0.05 or more. In this case, the fuel efficiency of the tire can be improved over a wide temperature range.

Further, in the rubber composition, the difference between tan δ at 30 ° C. and tan δ at 60 ° C. is preferably 0.060 or less, more preferably 0.055 or less, and even more, from the viewpoint of reducing the temperature dependence of fuel efficiency performance. It is preferably 0.050 or less. The lower limit of the difference between tan δ at 30 ° C. and tan δ at 60 ° C. is not particularly limited, and the difference may be 0. If the difference between tan δ at 30 ° C. and tan δ at 60 ° C. of the rubber composition exceeds 0.070, the temperature dependence of the fuel efficiency performance of the tire cannot be sufficiently reduced.

Further, in the rubber composition, the difference between tan δ at 0 ° C. and tan δ at 30 ° C. is preferably 0.30 or less, preferably 0.14, from the viewpoint of improving wet performance and reducing the temperature dependence of fuel efficiency performance. It is more preferably ~ 0.30, still more preferably 0.15 to 0.25, and particularly preferably 0.16 to 0.20 or less.

Further, in the rubber composition, the difference between tan δ at 0 ° C. and tan δ at 60 ° C. is preferably 0.35 or less, more preferably 0.24 or less, from the viewpoint of reducing the temperature dependence of fuel efficiency performance. Even more preferably, it is 0.23 or less, and the difference may be 0.

Further, from the viewpoint of wet performance, the rubber composition has a kinematic strain of 1% and a storage elastic modulus (E') at 0 ° C. of preferably 18 MPa or less, more preferably 16 MPa or less, and preferably 3 MPa or more. Is 5 MPa or more. When the kinetic strain is 1% and the storage elastic modulus at 0 ° C. is 20 MPa or less, the flexibility of the rubber composition at low temperature is high, and by applying the rubber composition to the tread rubber of a tire, the ground contact performance of the tread rubber Can be improved and the wet performance of the tire can be improved.

Further, from the viewpoint of wet performance, the rubber composition preferably has a tensile strength (Tb) of 20 MPa or more, more preferably 23 MPa or more. When a rubber composition having a tensile strength of 20 MPa or more is used for the tread rubber, the rigidity of the tread rubber as a whole can be improved.
The tensile strength (Tb) shall be measured in accordance with JIS K6251-1993 with respect to the vulcanized rubber obtained by vulcanizing the rubber composition at 145 ° C. for 33 minutes.

[Rubber component (A)]
The rubber component (A) of the rubber composition is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass of at least one isoprene-based rubber selected from the group consisting of natural rubber and synthetic isoprene rubber. The above can be included. The upper limit of the content of isoprene-based rubber in the rubber component (A) is not particularly limited, and the total amount of the rubber component (A) may be isoprene-based rubber. When the content of isoprene-based rubber in the rubber component (A) is 50% by mass or more, the loss tangent (tan δ) of the rubber composition at low temperature becomes small, and the rubber composition is applied to the tread rubber of the tire. This makes it possible to improve the fuel efficiency of the tire at low temperatures.

Here, as the rubber component (A), in addition to natural rubber (NR) and synthetic isoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), and styrene-isoprene copolymer It may contain a synthetic diene rubber such as rubber (SIR), or may contain other synthetic rubber. These rubber components (A) may be used alone or as a blend of two or more.

[Thermoplastic resin (B)]
The rubber composition can include a thermoplastic resin (B). By blending the thermoplastic resin (B) with the rubber composition, it is possible to reduce the elastic modulus in the high strain region while suppressing the decrease in the elastic modulus in the low strain region.

The blending amount of the thermoplastic resin (B) is 5 to 40 parts by mass, preferably 8 to 30 parts by mass, and more preferably 10 to 20 parts by mass with respect to 100 parts by mass of the rubber component (A). .. When the blending amount of the thermoplastic resin (B) is 5 parts by mass or more with respect to 100 parts by mass of the rubber component (A), the elastic modulus of the rubber composition in the high strain region can be lowered, and 40. If it is less than a part by mass, the decrease in elastic modulus of the rubber composition in the low strain region can be suppressed.

As the thermoplastic resin (B), in view of wet performance, C ₅ resins, C ₉ resins, C ₅ -C ₉ resins, dicyclopentadiene resins, rosin resins, alkylphenol resins or terpene phenol resins are preferred, These thermoplastic resins (B) may be used alone or in combination of two or more.

Here, the C ₅ series resin refers to a C ₅ series synthetic petroleum resin, and the C ₅ series resin includes, for example, a C ₅ fraction obtained by thermal decomposition of naphtha in the petrochemical industry, such as AlCl ₃ or Examples thereof include an aliphatic petroleum resin obtained by polymerization using a Friedelcraft type catalyst such as BF ₃ . The C ₅ distillate usually contains olefin hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and 2-methyl. Diolefin hydrocarbons such as -1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene and 3-methyl-1,2-butadiene are included. Incidentally, examples of the C ₅ resin may be commercially available products, for example, is manufactured by Exxon Mobil Corporation aliphatic petroleum resin "Escorez (registered trademark) 1000 Series", aliphatic manufactured by Nippon Zeon Co., Ltd. Among the petroleum resins "Quinton (registered trademark) 100 series", "A100, B170, M100, R100" and the like can be mentioned.

The C ₉ resins, for example, by thermal cracking of petroleum chemical industry naphtha, ethylene, vinyl toluene, and alkyl styrene, indene major monomer is C ₉ fraction by-produced together with the petrochemical basic raw materials such as ethylene and propylene It is a resin obtained by polymerizing an aromatic having 9 carbon atoms. Here, specific examples of the C ₉ fraction obtained by thermal decomposition of naphtha, vinyl toluene, alpha-methyl styrene, beta-methyl styrene, .gamma.-methyl styrene, o- methyl styrene, p- methyl styrene, vinyl toluene , Inden, etc. The C _9- based resin, together with the C ₉ fraction, is a C ₈ fraction such as styrene, a C ₁₀ fraction such as methyl indene, 1,3-dimethylstyrene, etc., and further, naphthalene, vinyl naphthalene, vinyl anthracene, p. -Tert-Butylstyrene or the like is also used as a raw material, and these C _{8 to} C ₁₀ fractions and the like are obtained as a mixture by copolymerization with, for example, a Friedelcraft type catalyst. Further, the C _9- based resin may be a modified petroleum resin modified with a compound having a hydroxyl group, an unsaturated carboxylic acid compound, or the like. Commercially available products can be used as the C _9- based resin. For example, as the unmodified C _9- based petroleum resin, the trade names are "Neopolymer L-90", "Neopolymer 120", and "Neopolymer". 130 ”,“ Neopolymer 140 ”(manufactured by JX Nikko Nisseki Energy Co., Ltd.) and the like can be mentioned.

Wherein A C ₅ -C ₉ resins, refers to C ₅ -C ₉ based synthetic petroleum resins, examples of the C ₅ -C ₉ resins, for example, a C ₅ -C ₁₁ fraction derived from petroleum, AlCl ₃ Examples thereof include solid polymers obtained by polymerization using a Friedelcraft catalyst such as BF ₃ and BF ₃ , and more specifically, copolymers containing styrene, vinyltoluene, α-methylstyrene, inden and the like as main components. And so on. As the C _5- C ₉ series resin, a resin having a small amount of C ₉ or more components is preferable from the viewpoint of compatibility with the rubber component (A). Here, "there are few components of C ₉ or more" means that the components of C ₉ or more in the total amount of the resin are less than 50% by mass, preferably 40% by mass or less. Is in the C ₅ -C ₉ resins, it is possible to use a commercially available product, for example, trade name "Quinton (registered trademark) G100B" (manufactured by Nippon Zeon Co., Ltd.), trade name "ECR213" (ExxonMobil Chemical (Manufactured by the company) and the like.

The dicyclopentadiene resin is a petroleum resin produced by using dicyclopentadiene as a main raw material, which is obtained by dimerizing cyclopentadiene. As the dicyclopentadiene resin, a commercially available product can be used. For example, among the trade names "Quinton (registered trademark) 1000 series", which is an alicyclic petroleum resin manufactured by Nippon Zeon Corporation, "1105, 1325, 1340 ”and the like.

The rosin resin is a residue remaining after collecting balsams such as pine resin, which is the sap of a plant of the pine family, and distilling terepine essential oil, and contains rosinic acid (abietic acid, palastolic acid, isopimalic acid, etc.). Natural resins as the main component, modified resins obtained by modifying them, and processing them by hydrogenation, etc., and hydrogenated resins. Examples thereof include natural resin rosins, their polymerized rosins and partially hydrogenated rosins; glycerin ester rosins, their partially hydrogenated rosins and fully hydrogenated rosins and polymerized rosins; pentaerythritol ester rosins, their partially hydrogenated rosins and polymerized rosins. .. Examples of natural resin rosins include raw pine resin, gum rosin contained in tall oil, tall oil rosin, and wood rosin. Commercially available products can be used as the rosin resin, for example, the product name "Neotol 105" (manufactured by Harima Kasei Co., Ltd.), the product name "SN Tuck 754" (manufactured by Sannopco Co., Ltd.), and the product name "Lime Resin". No. 1 ”,“ Pencel A ”and“ Pencel AD ”(manufactured by Arakawa Chemical Co., Ltd.), product names“ Polypale ”and“ Pentalin C ”(manufactured by Eastman Chemical Co., Ltd.), product name“ Hyrosin (registered trademark) S "(Manufactured by Taisha Matsu Seiyu Co., Ltd.) and the like.

The alkylphenol resin is obtained by a condensation reaction of alkylphenol and formaldehyde under a catalyst. As the alkylphenol resin, a commercially available product can be used, for example, the product name "Hitanol 1502P" (manufactured by Hitachi Kasei Co., Ltd.), the product name "Tackiroll 201" (manufactured by Taoka Chemical Industry Co., Ltd.), and the product name "Tackiroll". 250-I "(brominated alkylphenol formaldehyde resin with 4% bromide rate, manufactured by Taoka Chemical Industry Co., Ltd.), product name" Tackiroll 250-III "(brominated alkylphenol formaldehyde resin, manufactured by Taoka Chemical Industry Co., Ltd.), product name Examples thereof include "R7521P", "SP1068", "R7510PJ", "R7572P" and "R7578P" (manufactured by SI GROUP, Inc.), and a product name "R7510PJ" (manufactured by SI Group INC.).

The terpene phenolic resin can be obtained by reacting terpenes with various phenols using a Friedel-Crafts type catalyst, or by further condensing with formalin. The raw material terpenes are not particularly limited, and monoterpene hydrocarbons such as α-pinene and limonene are preferable, those containing α-pinene are more preferable, and α-pinene is particularly preferable. As the terpenphenol resin, commercially available products can be used, for example, trade names "Tamanor 803L", "Tamanor 901" (manufactured by Arakawa Chemical Industry Co., Ltd.), trade names "YS Polystar U" series, "YS Polystar". Examples thereof include the "T" series, the "YS Polystar S" series, the "YS Polystar G" series, the "YS Polystar N" series, the "YS Polystar K" series, and the "YS Polystar TH" series (manufactured by Yasuhara Chemical Co., Ltd.).

[Filler (C)]
The rubber composition contains a filler (C), and the filler (C) can contain silica in an amount of 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. The upper limit of the ratio of silica in the filler (C) is not particularly limited, and the total amount of the filler (C) may be silica. When the ratio of silica in the filler (C) is 70% by mass or more, the tan δ of the rubber composition at 60 ° C. is effectively reduced, and the fuel efficiency performance of the tire to which the rubber composition is applied during normal running is improved. Effectively improve.

The silica is not particularly limited, and examples thereof include wet silica (hydrous silicic acid), dry silica (silicic anhydride), calcium silicate, aluminum silicate, and the like, and among these, wet silica is preferable. These silicas may be used alone or in combination of two or more.

In the rubber composition, the blending amount of the silica is preferably in the range of 40 to 70 parts by mass, more preferably in the range of 45 to 60 parts by mass with respect to 100 parts by mass of the rubber component. When the blending amount of silica is 40 parts by mass or more with respect to 100 parts by mass of the rubber component, the tan δ of the rubber composition at 60 ° C. is effectively reduced, and the fuel consumption of the tire to which the rubber composition is applied during normal running. The performance is effectively improved, and if it is 70 parts by mass or less, the flexibility of the rubber composition is high, and by applying the rubber composition to the tread rubber of the tire, the deformed volume of the tread rubber becomes large. Therefore, the wet performance of the tire can be further improved.

In the rubber composition, the filler (C) preferably further contains carbon black, and the blending amount of the carbon black is preferably in the range of 1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The range of 3 to 8 parts by mass is more preferable. By blending 1 part by mass or more of carbon black, the rigidity of the rubber composition is improved, and by blending 10 parts by mass or less, an increase in loss tangent (tan δ) can be suppressed. Therefore, the rubber composition is used as a tire tread. By applying it to rubber, it is possible to achieve both fuel efficiency and wet performance of tires at a high level.

The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. Of these, ISAF and SAF grade carbon blacks are preferable from the viewpoint of improving the wet performance of the tire. These carbon blacks may be used alone or in combination of two or more.

Further, the carbon black preferably further contains carbon black having a nitrogen adsorption specific surface area of 110 m ² / g or more and carbon black having a nitrogen adsorption specific surface area of 80 m ² / g or less. By containing carbon black having a nitrogen adsorption specific surface area of 110 m ² / g or more, wet performance can be ensured at a high level, and carbon black having a nitrogen adsorption specific surface area of 80 m ² / g or less can be contained at the same time. Therefore, the elastic modulus of the tire can be secured, and the steering stability can be improved.

Further, the filler (C) may contain aluminum hydroxide, alumina, clay, calcium carbonate and the like in addition to the above-mentioned silica and carbon black.
In the rubber composition, the blending amount of the filler (C) is preferably 30 to 100 parts by mass, more preferably 40 to 80 parts by mass with respect to 100 parts by mass of the rubber component. If the blending amount of the filler (C) in the rubber composition is within the above range, the rubber composition can be applied to the tread rubber of the tire to further improve the fuel efficiency and wet performance of the tire in a low temperature environment. Can be improved.

[Softener (D)]
From the viewpoint of workability and workability, the rubber composition can further contain the softening agent (D), and the blending amount of the softening agent (D) is 1 to 5 with respect to 100 parts by mass of the rubber component. The range of parts by mass is preferable, and the range of 1.5 to 3 parts by mass is more preferable. By blending 1 part by mass or more of the softening agent (D), kneading of the rubber composition becomes easy, and by blending 5 parts by mass or less of the softening agent (D), a decrease in rigidity of the rubber composition is suppressed. it can.

Here, examples of the softening agent (D) include mineral oil derived from minerals, aromatic oil derived from petroleum, paraffin oil, naphthenic oil, palm oil derived from natural products, and the like. Among these, wet tires. From the viewpoint of performance, mineral-derived softeners and petroleum-derived softeners are preferable.

[Silane Coupling Agent (E)]
The rubber composition is preferably further blended with a silane cup rig agent in order to improve the blending effect of the silica. The silane coupling agent is not particularly limited, and for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, and bis (3-triethoxysilylpropyl) ) Disulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercapto Propyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N, N-dimethyl Thiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropylbenzolyltetrasulfide, 3-triethoxy Cyrilpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyl dimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyltetra Examples thereof include sulfide and dimethoxymethylsilylpropylbenzothiazolyltetrasulfide. These silane coupling agents may be used alone or in combination of two or more.
The blending amount of the silane coupling agent is preferably in the range of 2 to 20 parts by mass, more preferably in the range of 5 to 15 parts by mass with respect to 100 parts by mass of the silica. When the blending amount of the silane coupling agent is 2 parts by mass or more with respect to 100 parts by mass of silica, the blending effect of silica is sufficiently improved, and the blending amount of the silane coupling agent is relative to 100 parts by mass of silica. If it is 20 parts by mass or less, the possibility of gelation of the rubber component is low.

[Other ingredients]
The rubber composition preferably further contains a fatty acid metal salt in addition to the components (A) to (E) described above. Examples of the metal used for the fatty acid metal salt include Zn, K, Ca, Na, Mg, Co, Ni, Ba, Fe, Al, Cu, Mn and the like, and Zn is preferable. On the other hand, examples of the fatty acid used in the fatty acid metal salt include fatty acids having a saturated or unsaturated linear, branched or cyclic structure having 4 to 30 carbon atoms, or a mixture thereof, and among these, 10 carbon atoms. Saturated or unsaturated linear fatty acids of ~ 22 are preferred. Examples of the saturated linear fatty acid having 10 to 22 carbon atoms include lauric acid, myristic acid, palmitic acid, stearic acid and the like, and examples of the unsaturated linear fatty acid having 10 to 22 carbon atoms include oleic acid and linoleic acid. , Linoleic acid, arachidonic acid and the like. The fatty acid metal salt may be used alone or in combination of two or more.
The content of the fatty acid metal salt is preferably in the range of 0.1 to 10 parts by mass, more preferably in the range of 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component (A).

In addition, the rubber composition further comprises a compounding agent commonly used in the rubber industry, such as stearic acid, an antioxidant, zinc oxide (zinc oxide), a vulcanization accelerator, a vulcanization accelerator aid, and vulcanization. Agents and the like can be appropriately selected within a range that does not impair the object of the present invention, and blended within a range of normal content. Commercially available products can be preferably used as these compounding agents. The rubber composition is prepared by blending a known method, for example, the rubber component (A) with a thermoplastic resin (B), a filler (C), and various compounding agents appropriately selected as necessary. Then, it can be produced by kneading, heating, extrusion, or the like. However, from the viewpoint of reducing the kinematic strain of the rubber composition at 1% and the storage elastic modulus at 0 ° C., it is preferable not to blend a thermosetting resin such as a novolak type, a resor type phenol resin, or a resorcin resin.

Examples of the vulcanizing agent include sulfur and the like.
The content of the vulcanizing agent is preferably in the range of 0.1 to 10.0 parts by mass as the sulfur content with respect to 100 parts by mass of the rubber component (A), and further in the range of 1.0 to 4.0 parts by mass. preferable. If the content of the vulcanizing agent is 0.1 parts by mass or more as the sulfur content, the breaking strength and abrasion resistance of the vulcanized rubber can be ensured, and if it is 10.0 parts by mass or less, the rubber elasticity is increased. It can be secured sufficiently. In particular, by setting the content of the vulcanizing agent to 4.0 parts by mass or less as the sulfur content, the wet performance of the tire can be further improved, which is preferable from the viewpoint of enhancing the effect of the present invention.

The vulcanization accelerator is not particularly limited, and for example, 2-mercaptobenzothiazole (M), dibenzothiazil disulfide (DM), N-cyclohexyl-2-benzothiazylsulfenamide ( Examples thereof include thiazole-based vulcanization accelerators such as CZ) and guanidine-based vulcanization accelerators such as 1,3-diphenylguanidine (DPG). As described above, the rubber composition of the present invention preferably contains three types of vulcanization accelerators.
The content of the vulcanization accelerator is preferably in the range of 0.1 to 5.0 parts by mass, more preferably in the range of 0.2 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component (A). ..

[Manufacturing method of rubber composition]
Next, one embodiment of the method for producing a rubber composition will be described in detail.
The method for producing this rubber composition is the above-mentioned method for producing a rubber composition, which comprises the above-mentioned natural rubber and synthetic isoprene rubber, except for a vulcanization-based compounding agent containing a vulcanizing agent and a vulcanization accelerator. The rubber component (A) containing 50% by mass or more of at least one isoprene-based rubber selected from the above, the thermoplastic resin (B), and the filler (C) containing 70% by mass or more of the silica are 150 to It is characterized by including a step of kneading at 165 ° C.
By excluding the vulcanization-based compounding agent and kneading at 150 to 165 ° C., the compounding agent other than the vulcanization-based compounding agent is uniformly dispersed in the rubber component (A) while avoiding early vulcanization (scorch). The compounding effect of each compounding agent can be sufficiently exhibited, and the difference between tan δ at 30 ° C. and tan δ at 60 ° C. of the rubber composition can be reduced while effectively reducing tan δ at 0 ° C. of the rubber composition. It can be effectively reduced.
The tan δ of the rubber composition, the difference in tan δ at each temperature, the storage elastic modulus (E'), and the tensile strength (Tb) are the above-mentioned kneading temperature, as well as the type and blend ratio of the rubber component (A). It can also be changed by adjusting the type and blending amount of the thermoplastic resin (B), the silica content in the filler (C), the type of silica, and the like, and also by adjusting the kind and amount of other blending agents.

Further, in the method for producing a rubber composition, after kneading at 150 to 165 ° C., kneading may be further performed at another temperature of less than 150 ° C.
Further, in the method for producing this rubber composition, a compounding agent other than the vulcanization-based compounding agent is sufficiently and uniformly dispersed in the rubber component (A), and then the vulcanization-based compounding including the vulcanization agent and the vulcanization accelerator is added. It is preferable to add the agent and knead at a temperature at which early vulcanization (scorch) can be prevented, for example, 90 to 120 ° C.
In the method for producing this rubber composition, kneading at each temperature is not limited to the kneading time, and should be appropriately set in consideration of the size of the kneading device, the volume of the raw material, the type and state of the raw material, and the like. Can be done.

As for the method of using the tread surface rubber layer formed from the rubber composition for the tread rubber, a known method can be adopted. For example, it can be produced by molding a raw tire using the tread surface rubber layer formed from the above-mentioned rubber composition at least on a portion of the tread rubber located on the tread rubber surface and vulcanizing the raw tire according to a conventional method. ..

[Rubber layer inside tread]
As described above, the rubber composition of the tread inner rubber layer of the tread rubber of the present embodiment is not particularly limited as long as it is larger than the 100% modulus of the rubber composition of the tread surface rubber layer, but is as follows, for example. be able to.
The rubber composition of the inner rubber layer of the tread can be, for example, phr (number of parts by mass per 100 parts by mass of rubber component) natural rubber (NR): butadiene rubber (BR) = 50 phr: 50 phr to 90 phr: 10 phr. Further, the rubber composition of the inner rubber layer of the tread preferably contains 30 to 60 phr of carbon black, and further, the rubber composition of the rubber composition of the tread surface does not contain the thermoplastic resin (B) contained in the rubber composition for rolling resistance. More preferable from the viewpoint. The rubber composition of the rubber layer inside the tread can be the same as the rubber composition of the rubber layer on the surface of the tread.
Further, the 100% modulus of the rubber layer inside the tread can be made larger than the 100% modulus of the rubber layer on the surface of the tread by a known method or adjustment of a vulcanizing agent or the like.

[Tread pattern]
The tire 1 of the first embodiment may include the above-mentioned tread rubber 23 and have the following tread pattern described with reference to FIG.
In the tire 1 of the present invention, if the above tread rubber 23 is provided, an arbitrary tread pattern, that is, a full lug pattern in which a lug groove is provided over the entire circumference of the tire 1, and a groove extending in the tire circumferential direction And a block pattern consisting of a plurality of blocks formed by grooves extending in the tire width direction, and a rib pattern having a rib-shaped land portion formed by grooves extending in the tire circumferential direction as shown in FIG. Can also be done.

As shown in FIG. 2, the tire 1 of the first embodiment includes at least one rib-shaped land portion 3 on the tread tread T. Specifically, the rib-shaped land portion 3 is formed by a tread ground contact end E and a circumferential main groove 4 continuously extending in the tire circumferential direction, or is adjacent to each other and continuously in the tire circumferential direction. A partition is formed by two extending circumferential main grooves 4. In the illustrated example, the tread tread T is provided with two circumferential main grooves 4, whereby the tread ground contact end E and one circumferential main groove 4 are provided on the shoulder side on the outer side in the tire width direction. A pair of rib-shaped land portions (hereinafter, also referred to as shoulder rib-shaped land portions) 3s is formed as a section, and one rib is formed by two peripheral main grooves 4 on the center side inside in the tire width direction. A tread (hereinafter, also referred to as a center rib tread) 3s is formed as a section. Further, in FIG. 2, the circumferential main groove 4 shows an extending form extending linearly along the tire circumferential direction, but the circumferential main groove 4 is long as it extends continuously in the tire circumferential direction. Often, for example, it can be in a zigzag shape, a wavy shape, or the like.

Further, in this embodiment, the rib-shaped land portion 3 is not provided with both-end opening sipes that cross the rib-shaped land portion 3. Specifically, in the rib-shaped land portion 3, both ends of the rib-shaped land portion 3 are open at both ends of the tread ground contact end E and the circumferential main groove 4, or both of the two circumferential main grooves 4. Is not provided. In this embodiment, the rib-shaped land portion 3 can be provided with any groove or sipe unless it is a groove or sipe that crosses the land portion. Further, when a plurality of rib-shaped land portions 3 are present, it is preferable that all the rib-shaped land portions 3 are not provided with open-ended sipes as shown in the illustrated example, but at least one rib-shaped land portion 3 is provided. It is also possible to prevent both ends from being provided with sipes.
Further, the rib-shaped land portion 3 is provided with a one-end opening sipe 5 having one end opened in the circumferential main groove 4 or the tread ground contact end E and the other end ending in the rib-shaped land portion 3. .. Specifically, one end of the one-end opening sipe 5 is opened to either one of the two circumferential main grooves 4 or to either the tread ground contact end E and the circumferential main groove 4. There is.

Further, in the first embodiment, the one-sided opening sipe 5c arranged on the rib-shaped land portion 3 and, in the illustrated example, the center rib-shaped land portion 3c, is formed from the other end of the one-sided opening sipe 5c in the tire circumferential direction. Preferably, a circumferential sipe portion 5c1 extending at an inclination angle of 30 ° or less with respect to the tire circumferential direction and 30 ° or less with respect to the tire width direction from the circumferential sipe portion 5c1 in the tire width direction, preferably in the tire width direction. It is provided with a width direction sipe portion 5c2 that extends at an inclination angle of 1 and opens into a circumferential main groove 4. The opening of the widthwise sipe portion 5c2 of the one-sided opening sipe 5c to the circumferential main groove 4 is one end of the one-sided opening sipe 5c. Further, when the one-end opening sipe 5c is arranged in the shoulder rib-shaped land portion 3s, the width direction sipe portion can be opened in the circumferential main groove or the tread ground contact end E.

Further, a plurality of one-end opening sipes 5 are provided in each tire circumferential direction, and each one-end opening sipe 5 is provided in each half of the land portion on both sides in the width direction with respect to the center line in the width direction of the rib-shaped land portion 3. They are arranged side by side in the tire circumferential direction with a pitch length L of a predetermined length. Further, in the center rib-shaped land portion 3c, the one-end opening sipes 5c of each row can be displaced from each other in the tire circumferential direction and can be point-symmetrical. The pitch length L may not change in the tire circumferential direction and may be constant, or may change in the tire circumferential direction and may not be constant. In the example shown in FIG. 2, the patterns P1 to P3 are obtained by changing the pitch length L of the one-end opening sipe 5c on the tire circumference. The patterns P1 to P3 of FIG. 2 have relatively long pitch lengths in order, and the tread patterns shown in FIG. 2 are repeatedly provided with patterns P1 to P3 on the tire circumference. In the example of FIG. 2, three types of patterns in which the pitch length L is changed are shown, but it is optional to use two types or four or more types of patterns. Further, although the patterns P1 to P3 are repeatedly provided in order, the order of pattern arrangement is arbitrary. For example, after only one pattern is repeatedly arranged a plurality of times, another pattern may be arranged once or a plurality of times. ..

Both ends of the rib-shaped land portion 3 are terminated in the rib-shaped land portion 3, and the rib-shaped land portion 3 does not open directly or indirectly to the circumferential main groove 4 or the tread ground contact end E (via another sipe or groove). A sipe 6 with both ends closed is provided so as not to communicate with the main groove 4 in the circumferential direction and the ground contact end E of the tread. In the illustrated example, in the center rib-shaped land portion 3c, the sipe 6c with both ends closed is a circular sipe, that is, a small circular hole in the tread tread T view, with respect to the circumferential sipe portion 5c1 of the one-end opening sipe 5c. The rib-shaped land portion 3c is arranged outside in the width direction. Further, in the shoulder rib-shaped land portion 3s, the sipe with both ends closed 6s is arranged as a circular sipe and a curved sipe in the tread tread T view.

Here, the action and effect of the tread pattern of the first embodiment will be described.
Since the tire 1 of the first embodiment includes the rib-shaped land portion 3 in which the groove crossing the land portion 3 is not arranged, the land portion rigidity (circumferential shear rigidity) of the tire 1 in the circumferential direction is increased. The frictional force of the tire 1 against the road surface is further increased, and therefore the wet performance can be further improved.

Further, in this embodiment, since the rib-shaped land portion 3 is not provided with the opening sipes at both ends that cross the rib-shaped land portion 3, the circumferential rigidity of the rib-shaped land portion 3 is maintained in a high state. Therefore, high wet performance can be achieved.
Further, in this embodiment, since the rib-shaped land portion 3 is provided with the opening sipe 5 at one end, the tire 1 is placed on a wet road surface while maintaining the circumferential rigidity of the rib-shaped land portion 3 in a high state. In the grounded state, the one-end opening sipe 5 can remove the water film between the road surface and the tire 1 to increase the actual ground contact area between the tread tread T and the road surface. As a result, the wet performance can be improved more sufficiently.

Further, when the one-sided opening sipe 5c is configured to include the circumferential sipe portion 5c1 and the widthwise sipe portion 5c2 as arranged in the center rib-shaped land portion 3c in this embodiment, the circumferential sipe The portion 5c1 effectively reduces the compression rigidity (rigidity in the tire radial direction) of the tread while maintaining the circumferential rigidity of the rib-shaped land portion 3 to increase the actual ground contact area, and also increases the actual ground contact area, and also causes the circumferential main groove 4 and the like. As described above, the widthwise sipe portion 5c2 that opens to the tire can remove the water film that may form between the tire and the road surface, and therefore the wet performance can be further sufficiently improved.

Further, in this embodiment, since the rib-shaped land portion 3 is provided with sipe 6 with both ends closed, the compression rigidity is prevented from being lowered, for example, in the circumferential direction due to the opening of the sipe end to the circumferential main groove 4 and the like. Can be reduced. Therefore, the actual ground contact area is increased, and the wet performance can be further improved.

In the illustrated example, from the viewpoint of cornering performance, only the rib-shaped land portion 3 formed by the two circumferential main grooves 4, here the center rib-shaped land portion 3c, the circumferential sipe portion 5c1 and the width sipe. One end opening sipe 5c having a portion 5c2 is provided, but one end opening sipe 5 including a circumferential sipe portion 5c1 and a width direction sipe portion 5c2 is provided on the shoulder rib-shaped land portion 3s together with the center rib-shaped land portion 3c. Alternatively, it can be arranged only on the shoulder rib-shaped land portion 3s.

Further, in this embodiment, the one-end opening sipe 5c arranged in the center rib-shaped land portion 3c is arranged with a predetermined pitch length L (mm) measured along the tire circumferential direction, and the land portion 3c is arranged. Land width W (mm), tire width direction sipe component total length Ws (mm) of one-end opening sipe 5c in the land portion 3c arranged within the range of one pitch length L (mm), and pitch. The relationship between the length L (mm) and the total tire circumferential sipe component length Ls (mm) of the one-end opening sipe 5c in the land portion 3c arranged within the range of one pitch length L (mm)
0.4W ≤ Ws ≤ 1.2W and 0.6L ≤ Ls ≤ 3L
It is preferable to satisfy.
According to this configuration, it is possible to reduce the compressive rigidity and improve the actual road contact area while suppressing the decrease in the circumferential shear rigidity and maintaining the adhesion limit, so that the wet performance can be improved. Specifically, the drainage property is improved by increasing the total tire width direction sipe component length Ws (mm) within the range of one pitch length L (mm) to 0.4 times or more the land width W (mm). It can be improved, and by making it 1.2 times or less of the land width W (mm), it is possible to suppress a decrease in the circumferential shear rigidity. Further, the compression rigidity is sufficiently reduced by making the total tire circumferential sipe component length Ls (mm) within the range of one pitch length L (mm) 0.6 times or more the pitch length L (mm). By setting the pitch length to 3 times or less of the pitch length L (mm), the cornering power can be sufficiently maintained, and therefore, the deterioration of the steering stability performance can be suppressed. By having the tread rubber 4 as described above, the cornering power becomes larger and the steering stability performance is improved as compared with the tire having the normal tread rubber, but the steering stability performance is good, so the tire circumferential sipe component. Even if Ls is increased, deterioration of steering stability performance can be suppressed.
In the example of FIG. 2, the pitch length L of the one-end opening sipe 5c is changed on the tire circumference, but at least the center rib-shaped land portion 3c is arranged with the pitch length L (mm). The one-end opening sipe 5c satisfies 0.4W ≦ Ws ≦ 1.2W and 0.6L ≦ Ls ≦ 3L in all the patterns P1 to P3.

Here, the "pitch length L" refers to the tire from one end of the one-sided opening sipe in the tire circumferential direction to the corresponding one-sided opening sipe and the corresponding one-sided opening sipe in the tire circumferential direction. The length on the development view measured along the circumferential direction. Further, the "land portion width W" means a length measured along the tire width direction of the land portion. Further, "the total tire width direction sipe component total length Ws of the one-end opening sipe in the land portion arranged within the range of one pitch length L" is defined as "the total length Ws of the tire width direction sipe component in the land portion arranged within the range of one pitch length L". It is the length measured along the tire width direction by projecting the one-end opening sipe in the tire circumferential direction, and when the one-end opening sipe in the range is projected in the tire circumferential direction, for example, there are a plurality of one-end opening sipes. If there is an overlapping part in the projected one-sided opening sipe due to bending of the one-sided opening sipe, etc., the length of the overlapped part is added by the overlapping amount. Further, "the total tire circumferential sipe component length Ls of the one-end opening sipe in the land portion arranged within the range of one pitch length L" is defined as "the total length Ls of the tire circumferential sipe component arranged within the range of one pitch length L" in the land portion arranged within the range of one pitch length L. It is the length measured along the tire circumferential direction by projecting the one-sided opening sipe in the tire width direction, and when there is an overlapping part in the projected one-sided opening sipe as in "tire width direction sipe component total length Ws". Refers to the length obtained by adding the overlapping parts by the amount of duplication.

Further, in this embodiment, in the center rib-shaped land portion 3c in which the one-end opening sipe 5c is arranged, at least one both-end closed sipe 6c is arranged within the range of one pitch length L (mm). It is preferable that the opening area S (mm ² ) of the double-ended closed sipe 6c to the tread tread is within the range of 0.1 ≦ S ≦ 4. Further, more preferably, the sipe 6c with both ends closed is a small hole.
According to this configuration, as described above, the compressive rigidity can be reduced while maintaining the circumferential shear rigidity, so that the wettability can be further improved. Further, in the center rib-shaped land portion 3c, a block-shaped portion surrounded by, for example, one-end closed sipe 5c is formed in the land portion 3c only by arranging the one-end closed sipe 5c. By arranging it in the block-shaped portion, the compressive rigidity can be uniformly reduced.
When a plurality of both-end closed sipe 6c are arranged within a range of one pitch length L (mm), the average value of the plurality of both-end closed sipe 6c is used.
Further, in the example of FIG. 2, in the patterns P1 and P2, two sipe (small holes) 6c with both ends closed are arranged within the range of one pitch length L (mm), whereas the pattern In P3, three sipe 6c with both ends closed are arranged within a range of one pitch length L (mm).

Further, in this embodiment, in the center rib-shaped land portion 3c in which the opening sipe 5c is arranged at one end, both ends arranged within the range of the pitch length L (mm) and one pitch length L (mm). The relationship with the number N (pieces) of the closed sipe 6c is preferably 0.1 ≦ N / L ≦ 0.3.
According to this configuration, the wet performance can be further improved. Specifically, by setting N / Lc (pieces / mm) to 0.1 or more, the compressive rigidity can be sufficiently reduced, and N / Lc (pieces / mm) is set to 0.3 or less. Therefore, it is possible to prevent a decrease in the area of the center rib-shaped land portion 3c, and it is possible to prevent a decrease in the cornering power.

By the way, in the tire 1 shown in FIG. 2, the tread tread T is provided with two circumferential main grooves 4 and three ribbed land portions 3, but the tread tread T is provided with three circumferential main grooves 4. The sipe of the present invention may be arranged by providing one or more of them so that all of the plurality of land portions formed by the three or more circumferential main grooves 4 and the tread ground contact end E are ribbed land portions 3. It is also possible to dispose the sipe of the present invention by using a rib-shaped land portion 3 as a part of the land portion of the plurality of land portions.
Further, in FIG. 2, both the one-end open sipe 5 and the two-end closed sipe 6 are arranged on each rib-shaped land portion 3, but only one of them may be arranged.

Further, in the present embodiment, it is preferable that each sipe is a sipe (two-dimensional sipe) extending linearly in the depth direction from the viewpoint of improving drainage, but it is bent in the depth direction, for example, in a zigzag shape. It can also be an extended sipe (three-dimensional sipe).
Further, in the present embodiment (first embodiment), as described above, it is preferable that the rib-shaped land portion 3 is not provided with both-end opening sipes, but as a modification of the first embodiment, the ribs In all or a part of the land portion 3, the rib-shaped land portion 3 may be provided with both-end opening sipes that bend and extend in a zigzag shape in the depth direction, for example.

Here, in this embodiment, the size of the tire is not particularly limited, but it is preferable to use it as a pneumatic tire for a passenger car having the following sizes.

When the tire is built into the rim and the internal pressure is 250 kPa or more and there is no load, if the cross-sectional width SW of the tire is less than 165 (mm), the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) When the ratio SW / OD is 0.26 or less and the cross-sectional width SW of the tire is 165 (mm) or more, the relationship between the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) is determined.
2.135 x SW + 282.3 ≤ OD
(Hereinafter, the tire size in this relationship is also referred to as a narrow width and large diameter size). Due to the above relationship, the tire has a narrow width and a large diameter shape, the rolling resistance performance of the tire can be improved (the rolling resistance value can be reduced), and the weight of the tire can be reduced.
Further, the internal pressure at the time of rolling of the tire is preferably 250 kPa or more, and more preferably 250 to 350 kPa. In a tire having a narrow width and a large diameter, the contact length tends to increase, but by setting the contact length to 250 kPa or more, the increase in the contact length can be suppressed, the amount of deformation of the tread rubber can be reduced, and the rolling resistance can be further reduced.
Further, from the viewpoint of reducing the rolling resistance value of the tire and reducing the weight of the tire, when the internal pressure at the time of rolling the tire is 250 kPa or more, the cross-sectional width SW (mm) and the outer diameter OD of the tire 1 ( mm) preferably satisfies the relationship of −0.0187 × SW ² + 9.15 × SW-380 ≦ OD.

The "cross-sectional width SW" and "outer diameter OD" of the tire are the cross-sectional widths specified in JIS D 4202-1994 in a no-load state in which the tire is mounted on the rim and the internal pressure is 250 kPa or more, respectively. The outer diameter.

Further, the pneumatic tire having the tread surface rubber layer formed from the predetermined rubber composition of the present embodiment can be manufactured by various manufacturing methods. The manufacturing method is not particularly limited, but for example, a tread portion having a tread rubber having a tread surface rubber layer and a tread portion other than the tread portion may be combined and smelted as a unit to obtain a product tire. Alternatively, it is also possible to manufacture a tread portion having a tread rubber having a tread surface rubber layer according to the present invention by a brewing step, and then combine the tread portions other than the tread portion to form a product tire. Further, after removing the tread portion of the used tire, the method of the present invention in which the tread portion including the tread rubber having the tread surface rubber layer is newly combined to obtain a product tire can be adopted.

Although the first embodiment of the present invention has been described above with reference to the drawings, the pneumatic tire of the present invention is not limited to the above example, and may be appropriately modified as described below. Can be done.

Specifically, the tire sizes of the pneumatic tires of the present invention include 105 / 50R16, 115 / 50R17, 125 / 55R20, 125 / 60R18, 125 / 65R19, 135 / 45R21, 135 / 55R20, 135 / 60R17, 135. / 60R18, 135 / 60R19, 135 / 65R19, 145 / 45R21, 145 / 55R20, 145 / 60R16, 145 / 60R17, 145 / 60R18, 145 / 60R19, 145 / 65R19, 155 / 45R18, 155 / 45R21, 155 / 55R18 , 155 / 55R19, 155 / 55R21, 155 / 60R17, 155 / 65R13, 155 / 65R18, 155 / 70R17, 155 / 70R19, 165 / 45R22, 165 / 55R16, 165 / 55R18, 165 / 55R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 45R23, 175 / 55R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 175 / 65R15, 185 / 45R22, 185 / 50R16 , 185 / 50R20, 185 / 55R19, 185 / 55R20, 185 / 60R17, 185 / 60R19, 185 / 60R20, 195 / 50R20, 195 / 55R20, 195 / 60R19, 195 / 65R17, 205 / 50R21, 205 / 55R16, 205 Examples include / 55R20, 205 / 60R16, 205 / 60R18, 215 / 50R21, 215 / 60R17, and 225 / 65R17.

Here, in the present invention, it is preferable to reduce the amount of grooves occupying the tread from the viewpoint of achieving both wet performance and other performance. Specifically, the groove volume ratio (groove volume V2 / tread rubber volume V1) is preferably 20% or less, and the negative ratio (ratio of the groove area to the tread tread area) is 20% or less. Is preferable. These values are lower than the standard values for pneumatic radial tires for passenger cars of conventional size.
In order to improve the wet performance, it is a general idea to increase the groove amount, but in the case of a pneumatic tire with a narrow width and a large diameter, the width W of the ground contact surface becomes narrow, so FIG. 3 (b) ), As shown in comparison with FIG. 3A, water is likely to be discharged in the tire width direction. Therefore, the wet performance is maintained even if the groove amount is reduced, and other performances such as cornering power can be improved by increasing the land rigidity.
The groove volume ratio is, for example, the tire diameter at the center position in the tire width direction and inside the tire width direction from both ends in the width direction of the maximum width belt layer having the maximum width in the tire width direction in the belt layer. When the volume of the tread rubber on the outermost side in the tire radial direction from the outermost reinforcing member (belt layer and belt reinforcing layer) in the direction is V1, and the total volume of the grooves formed on the tread tread is V2, the ratio is defined as V2 / V1. Will be done.

Here, in the present invention, when the vehicle mounting direction of the tire is specified, a negative rate is set between the half portion in the tire width direction between the vehicle mounting inside and the vehicle mounting outside with the tire equatorial plane CL as a boundary. A difference may be provided.

In the present invention, as shown in FIG. 4, a pattern may have a width direction groove 100 extending in the tire width direction from the vicinity of the tire equatorial plane CL to the tread ground contact end E. In this case, the circumferential main groove may be provided. Does not have to be included. According to the pattern in which the width direction groove 100 is the main body, the performance on snow can be particularly effectively exhibited.

In the present invention, various configurations can be adopted for the shoulder rib-shaped land portion classified by the outermost circumferential main groove in the tire width direction and the tread ground contact end E among the rib-shaped land portions. For example, in a tire in which a vehicle mounting direction is specified, the width of the shoulder rib-shaped land portion on the outside and inside of the vehicle mounting in the tire width direction can be changed. In consideration of steering stability, it is preferable that the width of the shoulder rib-shaped land portion on the outside of the vehicle mounted in the tire width direction is larger than the width of the shoulder rib-shaped land portion on the inside of the vehicle mounted in the tire width direction.

In the case of a narrow and large diameter pneumatic tire, from the viewpoint of suppressing buckling and improving cornering power, one end opening groove that extends from the circumferential main groove to the inside of the vehicle when the tire is mounted on the vehicle. It is preferable to provide.
Specifically, as shown in FIG. 5, at least one half of the tread tread T with the tire equatorial plane CL as a boundary is adjacent to the tread ground contact end E and in the tread width direction with the tread ground contact end E. Has a tread end side main groove 110 extending in the tread circumferential direction, separated by 25% or more of the tread width TW, and is partitioned by the tread end side main groove 110 and the tread ground contact end E. It is preferable that one of the land portions 111 adjacent to the portion has at least one one-end opening groove 112 extending from the tread ground contact end side main groove 110 in the tread width direction and staying in the adjacent land portion 111. The groove 113 in FIG. 5 is a shallow groove having a groove depth smaller than that of the main groove.
In the case of a narrow and large diameter pneumatic tire, the tread rubber is deformed and the belt is deformed due to the compressive stress on the outside of the vehicle and the tensile stress on the inside of the vehicle. , The ground plane rises.
Here, since there is one end opening groove 112 extending from the tread grounding end side main groove 110 in the tread width direction and staying in the land portion 111, the one end opening groove 112 is closed by compressive stress on the outside of the vehicle mounting in the land portion. Therefore, the deformation of the tread and the belt due to the compressive stress is suppressed as compared with the case where the one end opening groove 112 is not provided or the one end opening groove 112 does not extend to the outside of the vehicle mounting.
Further, since the opening groove 112 stays in the land portion, the rigidity against the tensile stress inside the vehicle mounting becomes higher than that in the case where the opening groove 112 extends to the inside of the vehicle mounting, which causes the tread and the tread. Deformation of the belt is suppressed.

In the case of a narrow and large diameter pneumatic tire, as shown in FIG. 6, in the tire width direction cross section, a straight line m1 passes through a point P on the tread surface on the tire equatorial plane CL and is parallel to the tire width direction. When the straight line passing through the ground contact end E'and parallel to the tire width direction is m2, the distance between the straight line m1 and the straight line m2 in the tire radial direction is reduced to a high _LCR, and the tread width of the tire is TW', the ratio is The L _CR / TW'is preferably 0.045 or less. By setting the ratio L _CR / TW'to the above range, the crown portion of the tire is flattened (flattened), the ground contact area is increased, the input (pressure) from the road surface is relaxed, and the tire radial direction is reached. It is possible to reduce the bending rate of the tire and improve the durability and wear resistance of the tire.
Here, the above-mentioned "ground contact end E'" means that the tire is mounted on the rim, the maximum air pressure specified for each vehicle to which the tire is mounted is filled, and the tire is placed vertically on the flat plate for each vehicle to which the tire is mounted. The points at both ends in the tire width direction on the contact surface with the flat plate when a weight corresponding to the specified maximum load is applied.

In the present invention, the tread rubber may be formed of a plurality of rubber layers different in the tire width direction. As the above-mentioned plurality of rubber layers, those having different tangent loss, modulus, hardness, glass transition temperature, material, and the like can be used.

The tire of the present invention preferably has an inclined belt layer composed of a rubberized layer of a cord extending inclined with respect to the tire circumferential direction, and in this case, the inclined belt layer may be only one layer. However, in a narrow-width, large-diameter passenger car tire, if there is only one inclined belt layer, the shape of the ground contact surface during turning is likely to be distorted, so the inclined belt layer extends in the direction in which the cords intersect each other between two or more layers. Is preferable. In the pneumatic tire of the present invention, a belt structure in which two belt layers form an inclined belt layer is most preferable.

In the present invention, the width of the maximum width inclined belt layer having the largest width in the tire width direction in the tire width direction is preferably 90% to 115% of the tread width TW, and 100% to 105% of the tread width TW. It is particularly preferable to have.

In the present invention, as the belt cord of the inclined belt layer, a metal cord, particularly a steel cord is most commonly used, but an organic fiber cord can also be used. The steel cord contains steel as a main component and can contain various trace substances such as carbon, manganese, silicon, phosphorus, sulfur, copper and chromium.

In the present invention, as the belt cord of the inclined belt layer, a monofilament cord or a cord obtained by twisting a plurality of filaments can be used. Various designs can be adopted for the twist structure, and various designs can be used for the cross-sectional structure, the twist pitch, the twist direction, and the distance between adjacent filaments. Further, a cord obtained by twisting filaments of different materials can be used, and the cross-sectional structure is not particularly limited, and various twisted structures such as single twist, layer twist, and double twist can be adopted.

In the present invention, the inclination angle of the belt cord of the inclined belt layer is preferably 10 ° or more with respect to the tire circumferential direction.

In the present invention, it is preferable that the inclination angle of the belt cord of the inclined belt layer is a high angle, specifically 35 ° or more with respect to the tire circumferential direction, and particularly in the range of 55 ° to 85 ° with respect to the tire circumferential direction. ..
This is because by setting the inclination angle to 35 ° or more, the rigidity in the tire width direction can be increased, and the steering stability performance particularly at the time of cornering can be improved. Further, it is possible to reduce the shear deformation of the interlayer rubber and improve the rolling resistance performance.

The tire of the present invention may have a circumferential belt composed of one or more circumferential belt layers on the outer side of the inclined belt layer in the tire radial direction.
When the inclination angles θ1 and θ2 of the belt cord of the inclined belt layer are 35 ° or more, the tire circumferential rigidity per unit width of the central region C including the tire equatorial plane CL is the other region. It is preferably higher than the tire circumferential rigidity per unit width.
FIG. 7 schematically shows an example of the belt structure, in which the circumferential belt layers 123 and 124 are laminated on the outer side of the inclined belt layers 121 and 122 in the tire radial direction, and the circumferential belt layer is formed in the central region C. 123 and 124 overlap each other in the tire radial direction.
For example, as shown in FIG. 7, by increasing the number of layers of the circumferential belt layer in the central region C more than the other regions, the tire circumferential rigidity per unit width of the central region C can be set as a unit of the other regions. It can be higher than the tire circumferential rigidity per width.
Most tires in which the belt cord of the inclined belt layer is inclined at 35 ° or more with respect to the tire circumferential direction are subjected to vibration modes such as primary, secondary and tertiary in the cross-sectional direction in the high frequency range of 400 Hz to 2 kHz. Since the tread tread has a shape that vibrates greatly uniformly, a loud radiated sound is generated. Therefore, if the tire circumferential rigidity of the central region of the tread in the tire width direction is locally increased, it becomes difficult for the central region of the tread in the tire width direction to expand in the tire circumferential direction, and the expansion of the tread tread in the tire circumferential direction is suppressed. As a result, the radiated sound can be reduced.
Further, as described above, in a tire having increased rigidity in the tire circumferential direction in the central region including the tire equatorial plane CL, the tread has a land portion continuous in the tire circumferential direction in at least the region including the tire equatorial plane CL on the tread tread. It is preferable to have. If the circumferential main groove is arranged on or near the tire equatorial surface CL, the rigidity of the tread in the region may decrease, and the ground contact length in the land portion that divides the circumferential main groove may become extremely short. Therefore, it is preferable to dispose a continuous land portion (rib-shaped land portion) in the tire circumferential direction over a certain region including the tire equatorial plane CL from the viewpoint of improving noise performance without reducing cornering power.

FIG. 8 schematically shows another example of the belt structure, in which one layer of the circumferential belt layer 133 is laminated on the outer side of the two layers of the inclined belt layers 131 and 132 in the tire radial direction.
In the present invention, as in the example shown in FIG. 8, when the inclination angle of the belt cord of the inclined belt layer is 35 ° or more, the inclined belt layer is inclined of two layers having different widths in the tire width direction. The inclination angle θ1 of the cord forming the widest inclined belt layer including at least the belt layer with respect to the tire circumferential direction and the inclination angle θ2 of the cord forming the narrowest inclined belt layer with respect to the tire circumferential direction are 35 ° ≦ θ1. It is preferable that ≦ 85 °, 10 ° ≦ θ2 ≦ 30 °, and θ1> θ2 are satisfied.
Many tires equipped with an inclined belt layer having a belt cord inclined at 35 ° or more with respect to the tire circumferential direction have vibration modes such as primary, secondary and tertiary in the cross-sectional direction in the high frequency range of 400 Hz to 2 kHz. Since the tread tread has a shape that vibrates greatly uniformly, a loud radiated sound is generated. Therefore, if the tire circumferential rigidity of the central region of the tread in the tire width direction is locally increased, it becomes difficult for the central region of the tread in the tire width direction to expand in the tire circumferential direction, and the expansion of the tread surface in the tire circumferential direction is suppressed. As a result, the radiated sound can be reduced.

FIG. 9 schematically shows another example of the belt structure, in which one layer of the circumferential belt layer 143 is laminated on the outer side of the two layers of the inclined belt layers 141 and 142 in the tire radial direction.
In a narrow-width, large-diameter passenger car tire, the circumferential belt layer preferably has high rigidity, and more specifically, it is composed of a rubberized cord layer extending in the tire circumferential direction, and the Young's modulus of the cord is Y ( GPa), the number of hits is n (lines / 50 mm), the circumferential belt layer is the m layer, and X = Y × n × m is defined, and 1500 ≧ X ≧ 750 is preferable. In a narrow-width, large-diameter passenger car tire, local deformation occurs in the tire circumferential direction with respect to the input when turning from the road surface, and the ground contact surface is substantially triangular, that is, in the circumferential direction depending on the position in the tire width direction. The shape tends to change greatly in the contact length. On the other hand, by using a highly rigid circumferential belt layer, the ring rigidity of the tire is improved and deformation in the tire circumferential direction is suppressed. Therefore, due to the incompressibility of the rubber, the tire width direction Deformation is also suppressed, and the ground contact shape is less likely to change. Furthermore, the improvement in ring rigidity promotes eccentric deformation, and at the same time, the rolling resistance is also improved. The effect of improving the rolling resistance is particularly wide in the narrow width and large diameter size pneumatic tire.

Further, when a highly rigid circumferential belt layer is used as described above, it is preferable that the inclination angle of the belt cord of the inclined belt layer with respect to the tire circumferential direction is a high angle, specifically 35 ° or more. When a highly rigid circumferential belt layer is used, the contact length may decrease depending on the tire due to the high rigidity in the tire circumferential direction. Therefore, by using a high-angle inclined belt layer, it is possible to reduce the out-of-plane bending rigidity in the tire circumferential direction, increase the elongation of the rubber in the tire circumferential direction when the tread is deformed, and suppress the decrease in the contact length. it can.

Further, in the present invention, a wavy cord may be used for the circumferential belt layer in order to increase the breaking strength. Similarly, a homologation cord (for example, elongation at break of 4.5 to 5.5%) may be used to increase the breaking strength.

Further, in the present invention, various materials can be adopted for the circumferential belt layer, and typical examples are rayon, nylon, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), aramid, and glass fiber. , Carbon fiber, steel, etc. can be adopted. Organic fiber cords are particularly preferred from the standpoint of weight reduction.

Here, in the present invention, the cord of the circumferential belt layer may be a monofilament cord, a cord in which a plurality of filaments are twisted, or a hybrid cord in which filaments of different materials are twisted.

Further, in the present invention, the number of driven belt layers in the circumferential direction can be in the range of 20 to 60/50 mm, but the number is not limited to this range.

Further, in the present invention, it is possible to have a distribution of rigidity, material, number of layers, driving density, etc. in the tire width direction, and for example, it is possible to increase the number of layers of the circumferential belt layer only at the end portion in the tire width direction. On the other hand, the number of layers of the circumferential belt layer can be increased only in the center portion.

Further, in the present invention, the circumferential belt layer can be designed to be wider or narrower than the inclined belt layer. For example, the width in the tire width direction may be 90% to 110% of the maximum width inclined belt layer having the largest width in the tire width direction among the inclined belt layers.

Here, it is particularly advantageous from the viewpoint of manufacturing that the circumferential belt layer is formed as a spiral layer.

In the present invention, it is also possible not to provide the circumferential belt layer.

In the present invention, various structures can be adopted for the carcass line. For example, in the tire radial direction, the maximum width position of the carcass can be brought closer to the bead portion side or the tread side. For example, the maximum width position of the carcass can be provided from the bead base portion to the outside in the tire radial direction in a range of 50% to 90% of the tire cross-sectional height.

Further, in the present invention, the carcass can also adopt various structures. For example, the number of carcass driven can be in the range of 20 to 60/50 mm, but the number is not limited to this.

Further, for example, the folded end of the carcass can be positioned inside the tire radial end of the bead filler, and the folded end of the carcass can be positioned in the tire radial direction with respect to the tire radial outer end of the bead filler or the maximum tire width position. It may be located on the outside, and in some cases, may extend to the inside in the tire width direction from the end in the tire width direction of the inclined belt layer. Further, when the carcass is composed of a plurality of carcass plies, the positions of the carcass folded ends in the tire radial direction can be different. Further, it is also possible to adopt a structure in which the carcass folded portion is not present in the first place and is sandwiched between a plurality of bead core members or wound around the bead core.

In a narrow width and large diameter pneumatic tire, it is preferable to make the tire side portion thinner. “Thinning the tire side portion” means that, for example, the tire width direction cross section S1 of the bead filler can be 1 times or more and 4 times or less the tire width direction cross section S2 of the bead core. Further, the ratio Ts / Tb of the gauge Ts of the sidewall portion in the maximum tire width portion and the bead width Tb at the center position in the tire radial direction of the bead core can be set to 15% or more and 40% or less. Further, the ratio Ts / Tc of the gauge Ts of the sidewall portion in the maximum width portion of the tire and the diameter Tc of the carcass cord can be 5 or more and 10 or less.
The gauge Ts is the total thickness of all members such as rubber, reinforcing member, and inner liner. Further, in the case of a structure in which the bead core is divided into a plurality of small bead cores by a carcass, the distance between the innermost end and the outermost end in the width direction of all the small bead cores is Tb.

In the present invention, the maximum tire width position can be provided from the bead base portion to the outside in the tire radial direction in a range of 50% to 90% with respect to the tire cross-sectional height.

The tire of the present invention may also have a structure having a rim guard.

The tire of the present invention may also have a structure without a bead filler.

In the present invention, the bead core can adopt various structures such as a circular cross section and a polygonal cross section. Further, in addition to the structure in which the carcass is wound around the bead core, the structure in which the carcass is sandwiched between a plurality of bead core members is also possible.

In the present invention, the bead portion may be further provided with a rubber layer, a cord layer, or the like for the purpose of reinforcement or the like. Such additional members can be provided at various positions with respect to the carcass and bead filler.

In the present invention, it is preferable to make the inner liner thicker from the viewpoint of reducing the noise inside the vehicle at 80 to 100 Hz. Specifically, it is preferably about 1.5 mm to 2.8 mm, which is thicker than usual (about 1.0 mm).
It has been found that the narrow width and large diameter pneumatic tires tend to deteriorate the noise inside the vehicle at 80 to 100 Hz, especially when the internal pressure is high. By making the inner liner thicker, the vibration damping property can be improved and the noise inside the vehicle at 80 to 100 Hz can be reduced. Since the loss contributing to the rolling resistance of the inner liner is smaller than that of other members such as the tread, the noise performance can be improved while minimizing the deterioration of the rolling resistance.

In the present invention, the inner liner can be formed by a rubber layer mainly composed of butyl rubber or a film layer containing resin as a main component.

In the present invention, in order to reduce the cavity resonance sound, a porous member may be arranged on the inner surface of the tire, or electrostatic flocking may be performed.

The tire of the present invention may also be provided with a sealant member on the inner surface of the tire to prevent air leakage during a puncture.

The pneumatic tire of the present invention can also be a side-reinforced run-flat tire having a crescent-shaped reinforcing rubber on the tire side portion.

When a side-reinforced run-flat tire is used for a narrow-width, large-diameter pneumatic tire, both run-flat durability and fuel efficiency can be achieved by a structure with a simplified side portion. This is because in the case of a narrow and large diameter pneumatic run-flat tire for passenger cars, the deformation of the side part and tread part is relatively small during run-flat running, while the deformation from the shoulder part to the buttress part is relatively small. It is based on the finding that the deformation becomes large. This deformation is in contrast to the conventional size, where the deformation is relatively large on the side portion.
Due to the deformation characteristic of such a narrow width and large diameter size, it is possible to sufficiently secure run-flat durability and further improve fuel efficiency even with a simplified structure.
As a specific simplification method, it is possible by satisfying at least one of the following conditions (i) to (iii).
FIG. 10 is a cross-sectional view in the tire width direction of the tire according to the third embodiment of the present invention when the tire of the present invention is a run-flat tire.
(I) As shown in FIG. 10, the folded end A of the carcass folded portion is located inside the tire maximum width position P in the tire radial direction. (Ii) The tire is incorporated into the rim, and a predetermined internal pressure is applied. The maximum tire radial length of the side reinforcing rubber 151 in the tire width direction cross section in the reference state as a load is set to H1, and the outermost point in the tire radial direction of the bead filler and the outermost point in the tire radial direction of the bead core are connected. When the length of the parallel wire is H2, 1.8 ≦ H1 / H2 ≦ 3.5 is satisfied. (Iii) A reference state in which a tire is incorporated in a rim, a predetermined internal pressure is applied, and no load is applied. When the maximum length of the side reinforcing rubber 151 in the tire radial direction in the tire width direction cross section is H1 (mm), the relational expression 10 (mm) ≤ (SW / OD) x H1 ≤ 20 (mm) is used. Fulfill.

In the case of a narrow-width, large-diameter pneumatic tire, when a side-reinforced run-flat tire is used, the outermost circumferential main groove in the tire width direction is arranged closer to the tire equatorial plane CL in the tire width direction. Further improvement in run-flat durability can be realized. This is because in the case of a narrow and large diameter pneumatic run-flat tire for passenger cars, the deformation of the side part and tread part is relatively small during run-flat running, while the deformation from the shoulder part to the buttress part is relatively small. It is based on the finding that the deformation becomes large. This deformation is in contrast to the conventional size, where the deformation is relatively large on the side portion. Due to the deformation characteristic of such a narrow and large diameter size, by arranging the outermost circumferential main groove in the tire width direction from the tire equatorial plane CL, the shoulder land portion during run-flat running is buttressed. The ground contact property can be improved and the ground pressure is relaxed. As a result, the run-flat durability can be further improved.
FIG. 11 is a cross-sectional view in the tire width direction of the tire according to the fourth embodiment of the present invention when the tire of the present invention is a run-flat tire.
Specifically, the width in the tire width direction is the largest of the one or more belt layers in the cross section in the tire width direction in the reference state in which the tire is incorporated in the rim, a predetermined internal pressure is applied, and no load is applied. The half width of the belt layer in the tire width direction is WB, and the outermost peripheral main groove in the tire width direction of one or more circumferential main grooves from the tire width direction end of the belt layer having the largest width in the tire width direction 161 When the distance in the tire width direction to the center position in the tire width direction is WG, it is preferable to satisfy the relational expression 0.5 ≦ WG / WB ≦ 0.8.

Although the embodiment of the present invention has been described above with reference to the drawings, the pneumatic tire of the present invention is not limited to the above example and can be appropriately modified.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

<Test tire>
Each test tire is a tire having a tire size of 165 / 60R19 as shown in FIGS. 1 and 2, and each test tire has a tread surface rubber layer located on the outermost surface of the tread and the tread surface. It is provided with a tread rubber including a tread inner rubber layer located inside the tire radial direction from the rubber layer. Each rubber layer is formed from the rubber compositions of the specifications shown in Table 1 and has 100% modulus shown in Table 1. The content (parts by mass) of each material in each rubber layer refers to a value when the rubber component (A) is 100 parts by mass.
The loss tangent (tan δ) and storage elastic modulus (E') of the tread surface rubber layer of Example 1 are as follows.
Tan δ at 0 ° C: 0.426
Tan δ at 30 ° C: 0.244
Tan δ at 60 ° C: 0.190
E'at 0 ° C.: 17 MPa
Vulcanized rubber obtained by vulcanizing a rubber composition at 145 ° C. for 33 minutes was measured for loss tangent (tan δ) at 0 ° C., 30 ° C. and 60 ° C., and storage elastic modulus (E') at 0 ° C. On the other hand, the measurement was performed using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd. under the conditions of initial strain of 2%, dynamic strain of 1%, and frequency of 52 Hz.

<Evaluation>
For each test tire, the rigidity, wet performance (performance on a wet road surface) and fuel efficiency performance when the vehicle turned were evaluated by the following methods. The results are shown in Table 1.

(1) Rigidity when turning the vehicle The test tire was attached to the test vehicle, and the rigidity when turning the vehicle was evaluated by the turning performance, which is one index of the rigidity evaluation when turning the vehicle, in the actual vehicle test on a dry road surface. .. Specifically, the test vehicle equipped with the test tire was run from a straight line to a turning run, and the performance such as stability at that time was evaluated by the driver's feeling. The result of the evaluation shows that the feeling score of the tire of Comparative Example 1 is displayed as an index as 100, and that the larger the index value, the better the turning performance and the higher the rigidity when the vehicle turns.

(2) Wet Performance Each of the above test tires was mounted on a rim (rim size 5.5J19), filled with an internal pressure (300 kPa), mounted on a vehicle, and then traveled on a wet road surface at a speed of 80 km / h. Then, after traveling in the above state, the stopping distance (m) when the full brake was applied was measured, and the average deceleration (m / s ² ) = V ² / 25.92L at this time was calculated (average deceleration). speed a, initial velocity v, the mass m, when the stopping distance L, from mv ^2/2 = maL, can be calculated as a = v ² / 2L. coefficient of friction during the wet (wet μ)). The evaluation result is shown by an index in which the value for each test tire is reciprocal and the tire described in Example 1 is 100. The larger the index value, the better the wet performance.

＊１ 天然ゴム：インドネシア製「ＳＩＲ２０」
＊２ スチレン−ブタジエン共重合体ゴム：ＪＳＲ株式会社製、商品名「＃１５００」
＊３ Ｃ₉系樹脂：ＪＸ日鉱日石エネルギー株式会社製、商品名「日石ネオポリマー（登録商標）１４０」
＊４ シリカ：東ソー・シリカ工業株式会社製、商品名「ニプシルＡＱ」（ＢＥＴ表面積＝２０５ｍ²／ｇ）
＊５ カーボンブラック：Ｎ２３４（ＩＳＡＦ）、旭カーボン株式会社製、商品名「＃７８」

* 1 Natural rubber: Indonesian "SIR20"
* 2 Styrene-butadiene copolymer rubber: manufactured by JSR Corporation, trade name "# 1500"
* 3 C ₉ resin: manufactured by JX Nippon Oil Energy Co., Ltd., trade name "Nippon Neopolymer (registered trademark) 140"
* 4 Silica: Made by Tosoh Silica Industry Co., Ltd., trade name "Nipsil AQ" (BET surface area = 205 m ² / g)
* 5 Carbon black: N234 (ISAF), manufactured by Asahi Carbon Co., Ltd., product name "# 78"

From Table 1, the tire of Example 1 in which the 100% modulus of the inner rubber layer of the tread was made larger than the 100% modulus of the rubber layer of the tread surface and the rubber composition of the rubber layer of the tread surface was predetermined was Comparative Example 1. Since the turning performance and the wet performance are higher than those of the tires of No. 2 and 2, it can be seen that the tire of the first embodiment has high rigidity when the vehicle turns and the wet performance is sufficiently improved.

According to the present invention, it is possible to provide a pneumatic tire capable of sufficiently improving wet performance while increasing the rigidity when the vehicle turns.

1: Pneumatic tire, 21: bead part, 22: carcass, 23: tread rubber, 23a: tread surface rubber layer, 23b: tread inner rubber layer, 24: tread part, 25: sidewall part, 26: belt, 3 : Rib-shaped land part, 3s: Shoulder rib-shaped land part, 3c: Center rib-shaped land part, 4: Circumferential main groove, 5: One-sided opening sipe, 5c: One-sided opening sipe (of center rib-shaped land part), 5s : One end open sipe (of shoulder rib-shaped land), 5c1: Circumferential sipe, 5c2: Width sipe, 6: Both ends closed sipe, 6c: Both ends closed sipe (of center rib-shaped land), 6s: (Shoulder rib-shaped land part) Both ends closed sipe, 100: Width direction groove, 110: Main groove on the end side of the tread, 111: Adjacent land part, 112: One end opening groove, 113: Shallow groove, 121, 122: Inclined belt layer, 123, 124: Circumferential belt layer, 131, 132: Tilt belt layer, 133: Circumferential belt layer, 141, 142: Tilt belt layer, 143: Circumferential belt layer, 151: Side reinforcement rubber, 161: Circumferential main Groove, CL: Tire equatorial plane, E: Tread ground contact end, L: Pitch length, P1 to P3: Pattern, T: Tread tread, W: Land width

Claims (11)

A pneumatic tire having a tread rubber including a tread surface rubber layer located on the outermost surface of the tread and a tread inner rubber layer located inside the tread surface rubber layer in the tire radial direction.
The 100% modulus of the inner tread rubber layer is greater than the 100% modulus of the tread surface rubber layer.
The tan δ of the rubber composition forming the tread surface rubber layer at 0 ° C. is 0.4 or less.
The difference between tan δ at 30 ° C. and tan δ at 60 ° C. of the rubber composition is 0.070 or less.
A pneumatic tire characterized in that the dynamic strain of the rubber composition is 1% and the storage elastic modulus at 0 ° C. is 20 MPa or less. The rubber composition contains a rubber component (A) containing 50% by mass or more of at least one isoprene-based rubber selected from the group consisting of natural rubber and synthetic isoprene rubber, a thermoplastic resin (B), and silica 70. Containing a filler (C) containing a mass% or more,
The pneumatic tire according to claim 1, wherein in the rubber composition, the blending amount of the thermoplastic resin (B) is 5 to 40 parts by mass with respect to 100 parts by mass of the rubber component (A). The tread tread is partitioned by a tread ground contact end and a circumferential main groove that extends continuously in the tire circumferential direction, or is partitioned by two circumferential main grooves that are adjacent to each other and extend continuously in the tire circumferential direction. The pneumatic tire according to claim 1 or 2, further comprising at least one ribbed tread that is formed. The ribbed land portion is provided with both-end opening sipes that open at both ends at both the tread ground contact end and the circumferential main groove, or at both of the two circumferential main grooves. Zu,
One end of the ribbed land portion is opened to either one of the tread ground contact end and the circumferential main groove, or one of the two circumferential main grooves, and the other end is The pneumatic tire according to claim 3, wherein an opening sipe is provided at one end, which is terminated in the ribbed land portion. The one-end opening sipe includes a circumferential sipe portion extending from the other end in the tire circumferential direction and a width sipe portion extending from the circumferential sipe portion in the tire width direction and opening to the circumferential main groove or the tread ground contact end. The pneumatic tire according to claim 4, wherein the tire comprises. The pneumatic tire according to any one of claims 3 to 5, wherein the rib-shaped land portion is provided with closed-ended sipes at both ends that terminate in the rib-shaped land portion. The pneumatic tire according to any one of claims 1 to 6, wherein the 100% modulus of the inner rubber layer of the tread is 1.05 to 2.50 times the 100% modulus of the rubber layer on the surface of the tread. The pneumatic tire according to claim 7, wherein the 100% modulus of the inner rubber layer of the tread is 1.10 to 2.00 times the 100% modulus of the rubber layer on the surface of the tread. The pneumatic tire according to any one of claims 1 to 8, wherein the thickness of the tread surface rubber layer is 0.5 to 0.9 times the thickness of the tread inner rubber layer. The rubber composition of the tread surface rubber layer contains a thermoplastic resin.
The thermoplastic resin is C ₅ System resin, C ₉ System resin, C ₅ -C ₉ The pneumatic tire according to any one of claims 1 to 9, which is a single type or a combination of two or more types of a based resin, a dicyclopentadiene resin, a rosin resin, an alkylphenol resin or a terpenephenol resin. The rubber composition of the tread surface rubber layer contains a rubber component and a filler.
The filler contains carbon black
The pneumatic tire according to any one of claims 1 to 10, wherein the blending amount of the carbon black is in the range of 1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

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