JP7494478B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

In recent years, a technology has been proposed to suppress cavity resonance within the tire cavity and reduce road noise by attaching a long strip of sound-damping material made of sponge material or the like to the inner surface of the tread of a pneumatic tire in the circumferential direction of the tire. As a method for attaching the sound-damping material, a method has been proposed that uses synthetic rubber adhesives made by dissolving chloroprene rubber or the like in an organic solvent, double-sided tape, etc.

However, simply using adhesives is not enough to adequately adhere the sound-damping body to the inside of the tread, and methods such as buffing the inside of the tread to flatten the uneven pattern and increase the adhesion area are used. However, buffing requires time and effort, which reduces work efficiency, and causes various problems such as excessively reducing the thickness of the inner liner rubber layer that forms the tire cavity surface, compromising the airtightness of the tire (see Patent Documents 1 and 2).

International Publication No. WO2003/103989 JP 2003-063208 A

The present invention aims to solve the above problems and provide a pneumatic tire with improved resistance to peeling of the noise damping body.

The present invention provides a pneumatic tire having a noise damping body fixed to a tire inner cavity surface by a fixing layer,
The fixation layer is a pneumatic tire in which an average storage modulus Gc' [Pa] in a 40% region consisting of 20% of the region in each of both tire width directions centered on the tire equator, and average storage modulus values Ga' [Pa] and Gb' [Pa] in 30% regions from both ends in the tire width direction satisfy the following formulas (1) and (2):
Ga' ≦ Gc' (1)
Gb'<Gc' (2)

It is preferable that the pneumatic tire satisfies the following formula.
0.25≦Ga′/Gb′≦4.00

It is preferable that the pneumatic tire satisfies the following two formulas.
0.10≦Gb′/Gc′≦0.70
0.50≦Ga′/Gb′≦2.00

It is preferable that the pneumatic tire satisfies the following two formulas.
0.30≦Gb′/Gc′≦0.50
0.80≦Ga′/Gb′≦1.25

In the pneumatic tire, it is preferable that the loss tangent at 30°C of the rubber composition forming the rubber layer in the tread portion that comes into contact with the road surface is 0.13 or less.

According to the present invention, a pneumatic tire is provided with a noise-damping body fixed to the tire inner cavity surface by a fixing layer, and the fixing layer is a pneumatic tire in which the average storage modulus Gc' [Pa] in a 40% region consisting of 20% of the region in both tire width directions centered on the tire equator, and the average storage modulus Ga' [Pa] and Gb' [Pa] in a 30% region from both ends in the tire width direction satisfy the above formulas (1) and (2). Therefore, a pneumatic tire with improved peeling resistance of the noise-damping body can be provided.

1 is a cross-sectional view showing an embodiment of a pneumatic tire. 1 is a circumferential cross-sectional view of a pneumatic tire taken along a tire equator. FIG. 4 is a partially enlarged cross-sectional view showing an enlarged fixed portion of the noise damper. 10 is a cross-sectional view showing another cross-sectional shape of the noise damper. FIG.

The pneumatic tire of the present invention has a sound-damping body fixed to the tire cavity surface by a fixation layer, and the fixation layer has an average storage modulus Gc' [Pa] in a 40% region consisting of 20% of the region in both tire width directions centered on the tire equator, and average storage modulus values Ga' [Pa] and Gb' [Pa] in 30% regions from both ends in the tire width direction, which satisfy the above formulas (1) and (2).

The reason why the effect of improving the peeling resistance of the sound damper is obtained is presumed to be as follows.
Conventionally, a fixing layer of uniform thickness in the tire width direction is formed using double-sided tape, adhesive or glue, and a sound-damping body is attached to the fixing layer. In the actual driving mode of a vehicle, when the tire is strained by going over a protrusion, the sound-damping body attached to the inner cavity is also strained following the shape change of the tire inner surface. At this time, stress is likely to concentrate at the adhesive end of the double-sided tape, adhesive or glue, and peeling from the adhesive end is often observed, especially when the thickness of the double-sided tape, adhesive or glue is uniform.

Regarding this point, the inventors first focused on the fact that the harder the fixation layer formed by double-sided tape, pressure-sensitive adhesive, adhesive, etc., the stronger the adhesion, but the harder it is, the more likely it is that stress will concentrate and peeling will occur at locations with large strain such as the adhesive end, and that a soft fixation layer has the disadvantage of lowering the adhesive strength, but the advantage is that it disperses stress even at locations with large strain such as the adhesive end, making peeling less likely to occur. They then discovered that by distributing the hardness of the fixation layer formed by double-sided tape, pressure-sensitive adhesive, adhesive, etc. in the width direction, making the center harder and the adhesive end softer, it is possible to make it more difficult for peeling to occur at the adhesive end where stress is particularly likely to concentrate, and that the peeling resistance of the sound damping body can be improved throughout the tire, and they completed the present invention. Therefore, it is presumed that the peel resistance of the sound damper can be improved by adjusting the average storage modulus Gc' of the central region and the average storage modulus Ga' and Gb' of the end regions so as to satisfy the above formulas (1) and (2) with respect to the storage modulus of the fixing layer that fixes the sound damper.

In this way, the present invention solves the problem (objective) of improving the peeling resistance of the noise damper by configuring the tire to satisfy Ga'≦Gc', Gb'<Gc'. In other words, the parameters Ga'≦Gc', Gb'<Gc' do not define the problem (objective); the object of this application is to improve the peeling resistance of the noise damper, and the invention is configured to satisfy these parameters as a means to achieve this.

Hereinafter, an embodiment of the present invention will be described in detail.
In FIG. 1 , a pneumatic tire 1 of this embodiment is provided with a noise damper 9 whose outer circumferential surface is bonded to an inner tread surface 2S of the pneumatic tire 1 via a fixing layer 10 and which extends in the tire circumferential direction.

The pneumatic tire 1 is a tubeless tire that includes a tread portion 2, a pair of sidewall portions 3 that extend radially inward from both ends of the tread portion 2, and a bead portion 4 located at the inner end of each sidewall portion 3, and the tire cavity surface is covered with an inner liner rubber (not shown) made of low air permeable rubber. As the pneumatic tire 1, various tires can be used without being restricted by their internal structure or category. Passenger car tires, which require a high level of quietness inside the vehicle cabin, and in particular passenger car radial tires with an aspect ratio of 60% or less, are preferably used.

The pneumatic tire 1 is reinforced by a tire cord layer including a carcass 6 spanning between the bead portions 4, 4 and a belt layer 7 arranged radially outside the carcass 6 and inside the tread portion 2. The carcass 6 is formed of one or more carcass plies, one in this example, in which organic fiber cords are arranged at a predetermined angle (70 to 90 degrees, etc.) with respect to the circumferential direction of the tire. Both ends of the carcass ply are folded back around the bead core 5. The belt layer 7 is formed of multiple belt plies, two in this example, in which steel cords are arranged at a predetermined angle (10 to 40 degrees, etc.) with respect to the circumferential direction of the tire. The belt layer 7 has a hoop effect to strongly reinforce the tread portion 2, with the steel cords crossing between the plies to increase the belt rigidity.

The noise-damping body 9 can be, for example, a long band-shaped sponge material extending in the tire circumferential direction. The noise-damping body 9 is fixed in the tire circumferential direction along the tire equator C to the tread inner surface 2S (tire cavity surface), for example, via a fixing layer 10.

In this example, as shown in FIG. 2, one end e1 and the other end e2 of the noise damper 9 in the circumferential direction are butted against each other, that is, the noise damper 9 is formed continuously in a ring shape. Note that one end e1 and the other end e2 may be spaced apart in the circumferential direction, and in such a case, in order to suppress the influence on the weight balance and prevent the deterioration of the tire uniformity, it is preferable that the circumferential length of the spaced part is 100 mm or less, and further 80 mm or less. In addition, the fixing layer 10 formed along the noise damper 9 is exemplified as being formed continuously in a ring shape with one end ea and the other end eb in the circumferential direction butted against each other, similar to the noise damper 9. Similarly, one end ea and the other end eb may be spaced apart in the circumferential direction, and the length of the spaced part is preferably in the same range.

From the viewpoint of the effect of suppressing cavity resonance energy in terms of the porosity ratio, etc., it is preferable to use a sponge material with a specific gravity of 0.005 to 0.060. In addition, a sponge material with a sponge hardness of 5.0 to 500 N and a tensile strength of 10.0 to 1000 kPa is preferable. When the sponge hardness is limited, the sound damping body 9 is ensured to have a moderate elongation. This elongation helps to widely disperse stress when distortion is applied to the sound damping body 9. Particularly preferably, the sponge hardness is 80 N or more, and even more preferably 90 N or more, and the upper limit is preferably 150 N or less, 130 N or less, and even more preferably 110 N or less. When the tensile strength of the sponge material is limited, the strength against the stress is further increased. Particularly preferably, the tensile strength of the sponge material is 120 kPa or more, and even more preferably 130 kPa or more, and the upper limit is not particularly regulated, but 160 kPa or less, and even more preferably 150 kPa or less, is preferable from the viewpoints of cost, productivity, ease of availability in the market, etc.

The sponge hardness is the value measured in accordance with Method A (Section 6.3) of the measurement method for "Hardness" in Section 6 of JIS K6400, "Testing Methods for Flexible Urethane Foams." The tensile strength of the sponge is the value measured on a No. 1 dumbbell-shaped test piece in accordance with Section 10 of the same JIS, "Tensile strength and elongation."

As sponge materials, synthetic resin sponges such as ether-based polyurethane sponge, ester-based polyurethane sponge, and polyethylene sponge, and rubber sponges such as chloroprene rubber sponge (CR sponge), ethylene propylene rubber sponge (GPDM sponge), and nitrile rubber sponge (NBR sponge) can be suitably used. Among these, polyurethane sponges including ether-based polyurethane sponges are preferred from the viewpoints of sound-damping properties, light weight, foaming adjustability, durability, etc.

As shown in the partially enlarged cross-sectional view of the fixed portion of the sound-damping body 9 in FIG. 3, the sound-damping body 9 has its outer peripheral surface So fixed to the tread inner surface 2S by the fixing layer 10. The fixing layer 10 is not particularly limited as long as it can fix the sound-damping body 9 to the tread inner surface 2S, and is formed, for example, by a pressure-sensitive adhesive, adhesive, double-sided tape, etc. By fixing to the tread inner surface 2S (tire cavity surface) along the tire circumferential direction, the sound-damping body 9 is prevented from moving freely within the tire cavity during running, and damage to the sound-damping body 9 is prevented, and a stable resonance suppression effect is exerted. In particular, from the viewpoint of rim assembly and the like, it is preferable that the sound-damping body 9 is fixed to the tire cavity surface, especially the tread inner surface 2S. The tread inner surface 2S means the surface of the tire cavity surface that is located in the tread portion 2 that comes into contact with the road surface, and in this specification, it includes at least the width region TW (tread contact width) in the tire axial direction where the belt layer 7 is arranged. In a particularly preferred embodiment, the noise damper 9 is installed so that its width center is located on the tire equator C.

Here, tread width TW means the maximum axial width of the contact surface that comes into contact with the ground when the tire is mounted on a standard rim and inflated to the standard internal pressure and is subjected to a standard load. "Standard rim" means a rim that is determined for each tire by the standard system including the standard on which the tire is based, for example, standard rim for JATMA, "DGsign Rim" for TRA, and "MGasuring Rim" for GTRTO. "Standard internal pressure" means the air pressure determined for each tire by the standard, which means the maximum air pressure for JATMA, the maximum value listed in the table "TIRG LOAD LIMITS AT VARIOUS COLD INFLATION PRGSURGS" for TRA, and "INFLATION PRGSURG" for GTRTO, but is 180 kPa for passenger car tires. "Normal load" refers to the load that the standard specifies for each tire; for JATMA, it is the maximum load capacity; for TRA, it is the maximum value listed in the table "TIRG LOAD LIMITS AT VARIOUS COLD INFLATION PRGSURGS"; and for GTRTO, it is the "LOAD CAPACITY."

The width W1 of the noise-damping body 9 in the tire axial direction (in the example of FIG. 1, the same width as the width W1 of the fixing layer 10 in the tire width direction) is preferably in the range of 80 to 120% of the tread contact width TW. The lower limit of the width W1 is more preferably 90% or more of the tread contact width TW, and the upper limit is more preferably 110% or less.

The lower limit of the thickness of the sound-damping layer 9 (the total thickness of the sound-damping layer 9) is preferably 5.0 mm or more, and more preferably 7.0 mm or more, from the viewpoint of sound-damping effect. The upper limit of the thickness is preferably 40.0 mm or less, and more preferably 30.0 mm or less, from the viewpoint of preventing unnecessary increases in cost and mass. The thickness of the sound-damping layer 9 at a given point is measured along the normal line at that point, and the thickness of the sound-damping layer 9 (the total thickness of the sound-damping layer 9) is the average value of the thicknesses at each point.

In this example, a rectangular shape is shown as an example of the cross-sectional shape perpendicular to the length direction of the sound-damping body 9, but various shapes such as a trapezoid, a triangle, or a semicircular shape can be used. Among these, as shown in FIG. 4, it is preferable to provide one or more circumferential grooves 20 on the inner surface Si side of the sound-damping body 9, thereby forming mountain-shaped raised portions 21 on both sides of the circumferential grooves 20. Such a sound-damping body 9 can increase its surface area due to the unevenness caused by the circumferential grooves 20 and the raised portions 21, thereby achieving a higher sound-damping effect. This increase in surface area also improves the heat dissipation of the sound-damping body 9, and helps prevent thermal destruction of the sound-damping body itself.

Adhesives and adhesives that can be used in the fixation layer 10 include inorganic adhesives (adhesives) and organic adhesives (adhesives). Examples of inorganic adhesives (adhesives) include sodium silicate, cement, ceramics, etc. Examples of organic adhesives (adhesives) include natural and synthetic (thermoplastic resin, thermosetting resin, elastomer, etc.) adhesives (adhesives). Examples of natural adhesives (bonds) include starch, protein, natural rubber, asphalt, etc.; examples of thermoplastic resins include vinyl acetate resins, polyvinyl acetal, ethylene vinyl acetate resins, vinyl chloride resins, acrylic resins (acrylic esters such as butyl acrylate), polyamides, cellulose, α-olefins, etc.; examples of thermosetting resins include urea resins, melamine resins, phenolic resins, resorcinol resins, epoxy resins, structural acrylic resins, polyesters, polyaromatics, etc.; examples of elastomers include chloroprene, nitrile rubber, styrene butadiene rubber, polysulfide, butyl rubber, silicone rubber, acrylic rubber, modified silicone rubber, urethane rubber, silylated urethane resin, telechelic polyacrylate, cyanoacrylate, etc.

As a double-sided tape that can be used for the immobilization layer 10, for example, one having an adhesive layer (bonding layer) on one side and the other side of a flexible base sheet can be used. As the base sheet, for example, plastic films such as polyethylene, polypropylene, polyvinyl chloride, polyester (polyethylene terephthalate, etc.), rayon, pulp, synthetic fibers, woven fabrics, nonwoven fabrics, cotton fabrics, acrylates, plastic foam sheets (acrylic foam using a foaming agent, etc.), metals (aluminum, copper, etc.), etc. are suitably used. The adhesive layer (bonding layer) can be formed using the above-mentioned adhesives and adhesives.

The outer peripheral surface So of the noise damper 9 is fixed to the tread inner surface 2S via a fixing layer 10 made of such an adhesive or the like. Then, as shown in FIG. 3, when fixing via the fixing layer 10, the average value Gc' of the storage modulus in a region 10c that is 20% in the tire width direction from the tire equator C, the average value Ga' of the storage modulus in a region 10a that is 30% from one end in the tire width direction, and the average value Gb' of the storage modulus in a region 10b that is 30% from the other end in the tire width direction satisfy a predetermined relationship in the tire width direction of the fixing layer 10, thereby improving the peel resistance of the noise damper 9.

Here, with respect to the 40% region 10c consisting of 20% of the region in both tire width directions centered on the tire equator C in the fixation layer 10, the 30% region 10a from one end of the fixation layer 10 in the tire width direction, and the 30% region 10b from the other end of the fixation layer 10 in the tire width direction, as shown in FIG. 3, if the position Pk corresponds to k% of the width W1 (width from one end 10ea to the other end 10eb) of the fixation layer 10 in the tire width direction at 100%, the regions 10c, 10a, and 10b of the fixation layer 10 are respectively from P30 (30% position) to P70 (70% position) ) (a central region of 40% of the width W1 of the fixation layer 10 in the tire width direction, with 20% in each direction in the tire width direction centered on the tire equator C), a region from P0 (0% position) to P30 (30% position) (a one end region of 30% of the width W1 of the fixation layer 10 in the tire width direction from one end 10ea of the fixation layer 10 in the tire width direction), and a region from P70 (70% position) to P100 (100% position) (another end region of 30% of the width W1 of the fixation layer 10 in the tire width direction from the other end 10eb of the fixation layer 10 in the tire width direction). Note that the positions of P30 and P70 correspond to the region 10c, and do not correspond to the regions 10a and 10b.

The average storage elastic modulus Gc' [Pa] of region 10c of the immobilization layer 10, the average storage elastic modulus Ga' [Pa] of region 10a, and the average storage elastic modulus Gb' [Pa] of region 10b satisfy the following formulas (1) and (2).
Ga' ≦ Gc' (1)
Gb'<Gc' (2)

From the viewpoint of the peeling resistance of the sound damper 9, with respect to formula (1), 0.10≦Ga'/Gc'≦1.00 is preferable, 0.10≦Ga'/Gc'≦0.70 is more preferable, and 0.30≦Ga'/Gc'≦0.50 is even more preferable. With respect to formula (2), 0.10≦Gb'/Gc'≦0.70 is preferable, and 0.30≦Gb'/Gc'≦0.50 is even more preferable.

As defined in formula (1), Ga' = Gc' may also be satisfied. In other words, peel resistance can be improved even when the average storage modulus of only region 10b out of regions 10a and 10b is smaller than the average storage modulus of region 10c (when the region is soft). For example, when the tire rotation direction is specified and the alignment of the vehicle on which the tire is mounted is negative camber, the hardness of one end on the inside of the vehicle when mounted on the vehicle can be reduced by taking into account the rotation direction and camber angle, thereby dispersing the stress at the end on the inside of the tire that is repeatedly deformed during normal driving, and good adhesion (peeling resistance) can be obtained.

On the other hand, in formula (1), Ga' < Gc' may also be satisfied. In other words, even if the average value of the storage modulus in both regions 10a and 10b is smaller (softer) than the average value of the storage modulus in region 10c, excellent peel resistance is obtained. For example, when applied to replacement products where the tire rotation direction is not specified and the alignment of the vehicle on which it is installed is not specified, excellent adhesion (peel resistance) can be obtained by reducing the hardness of both end portions.

From the viewpoint of the peeling resistance of the noise damper 9, it is preferable that Ga′ and Gb′ satisfy the following formula.
0.25≦Ga′/Gb′≦10.00
Also, 0.25≦Ga′/Gb′≦4.00 is preferable, 0.50≦Ga′/Gb′≦2.00 is more preferable, and 0.80≦Ga′/Gb′≦1.25 is even more preferable.

From the viewpoint of the peeling resistance of the noise damper 9, it is preferable that Ga′ satisfies the following formula.
0.5×10 ⁴ Pa≦Ga′≦2.0×10 ⁶ Pa
Also, 2.0×10 ⁴ Pa≦Ga′≦1.0×10 ⁶ Pa is preferable, and 2.5×10 ⁴ Pa≦Ga′≦0.5×10 ⁶ Pa is more preferable.

From the viewpoint of the peeling resistance of the noise damper 9, it is preferable that Gb′ satisfies the following formula.
0.5×10 ⁴ Pa≦Gb′≦2.0×10 ⁶ Pa
Also, 2.0×10 ⁴ Pa≦Gb′≦1.0×10 ⁶ Pa is preferable, and 2.5×10 ⁴ Pa≦Gb′≦0.5×10 ⁶ Pa is more preferable.

From the viewpoint of the peeling resistance of the noise damper 9, it is preferable that Gc′ satisfies the following formula.
0.5×10 ⁵ Pa≦Gc′≦2.0×10 ⁶ Pa
Also, 2.0×10 ⁵ Pa≦Gc′≦1.0×10 ⁶ Pa is preferable, and 4.0×10 ⁵ Pa≦Gc′≦0.8×10 ⁶ Pa is more preferable.

The storage modulus G' of the immobilizing layer can be adjusted, for example, by the type of pressure-sensitive adhesive, adhesive, or pressure-sensitive adhesive (adhesive) used in the double-sided tape.
Specifically, when a pressure-sensitive adhesive or bonding agent such as a hard acrylic resin or epoxy resin is used, G' tends to increase, whereas when a pressure-sensitive adhesive or bonding agent such as a silicone resin is used, G' tends to decrease. Another method for adjusting G' includes the addition of a curing agent and/or a softening agent, and when a curing agent is used to make a thermosetting resin, G' tends to increase, whereas when a thermoplastic resin is used without a thermosetting agent and a softening agent is added, G' tends to decrease.

The storage modulus G' at each point of the fixation layer was measured by taking a sample of the fixation layer from a pneumatic tire with a sound-damping body fixed in the fixation layer on the tire cavity surface, placing and stacking the sample between the parallel plates of an ARES manufactured by TA Instruments equipped with φ7.9 mm parallel plates to a thickness of 1 mm, adjusting the gap to a sample thickness of 1 mm, and heating the sample to 50°C. After confirming that the normal force had stabilized, the storage modulus G' was measured under conditions of an angular frequency of 10 Hz and dynamic strain of ±2%.

Gc' is the average value of the storage modulus at each point in region 10c, Ga' is the average value of the storage modulus at each point in region 10a, and Gb' is the average value of the storage modulus at each point in region 10b. The average value of the storage modulus is calculated from the average value of the storage modulus G' of the immobilization layer sampled from 10 or more parts around the circumference in each region. If measurement is impossible with only one sampling point, the samples may be stacked during measurement, and in that case, the average value averaged by the number of stacks is treated as the average value of the storage modulus. For example, if 10 points are measured when one measurement is possible at one point, the G' values measured at 10 points are averaged to calculate the average value. If one measurement is impossible at one point and measurement is possible by stacking five adhesive layer samples, two 5-layer stacked samples are prepared by stacking five samples, and the G' value of each is measured, and the obtained G' value is averaged by 2 (divided by 2) to calculate the value calculated as the average value of the storage modulus calculated by measuring 10 or more parts. If it is not possible to measure at one location and it is possible to measure by stacking 100 adhesive layer samples, one 100-layer laminate sample is made by stacking 100 samples, and the G' value is measured. The obtained G' value is the average value of the storage modulus calculated by measuring 10 or more locations.

From the viewpoint of the peel resistance of the sound damping body 9, the thickness T of the fixing layer 10 is preferably 0.10 to 2.50 mm, and more preferably 0.50 to 2.00 mm.

The thickness distribution of the fixation layer 10 is not particularly limited, and various distributions can be adopted, such as a form in which both ends of the fixation layer 10 are thin, such that the thickness of region 10c is thicker than the thicknesses of regions 10a and 10b, a form in which both ends of the fixation layer 10 are thick, such that the thickness of region 10c is thinner than the thicknesses of regions 10a and 10b, and a form in which the thickness of the fixation layer 10 is uniform, such that regions 10a, 10b, and 10c are the same.

With regard to thickness, the double-headed arrow T in FIG. 3 indicates the thickness T of the fixation layer 10 at point P, and this thickness T is measured along the normal to the tread inner surface 2S at point P. For example, P0, P30, P50, P70, and P100 are measured along the normal to the tread inner surface 2S at points corresponding to 0%, 30%, 50%, 70%, and 100% of the width W1. The thickness of the fixation layer 10 in the tire width direction is the average value of the thicknesses at each point P. Note that the thickness of the fixation layer when double-sided tape is used is the total thickness of the base sheet and the adhesive layer (bonding layer), and the thickness of the fixation layer when an adhesive or adhesive is used is the thickness of the adhesive layer or adhesive layer formed thereby.

In the tread portion 2 of the pneumatic tire 1, the rubber composition forming the rubber layer in contact with the road surface in the tread portion 2 preferably has a loss tangent (tan δ) at 30°C of 0.17 or less. If this parameter is satisfied, it is presumed that the heat generation of the tread rubber is suppressed, which prevents the central portion from becoming hot and the G' of the adhesive layer from decreasing. The smaller tan δ is, the more desirable it is, and it is more preferably 0.16 or less, even more preferably 0.13 or less, and particularly preferably 0.11 or less. Tan δ can be measured by the method described in the examples below.

The tan δ of the rubber composition can be adjusted by, for example, the type of rubber and its blending amount, the type of filler and its blending amount, and the like.
Specifically, when low heat generating rubber such as natural rubber, isoprene-based rubber, or modified rubber is used, when the amount of such rubber used in the rubber component is increased, when silica is used as a filler, or when the amount of filler is reduced, tan δ tends to decrease.

The above describes in detail a particularly preferred embodiment of the present invention, but the present invention is not limited to the illustrated embodiment and can be modified and implemented in various ways.

The present invention will be specifically explained based on examples, but the present invention is not limited to these.

To confirm the effects of the present invention, pneumatic tires with noise dampers (tire size: 215/60R16) were prototyped with the specifications shown in each table, and the peel resistance (durability) of each sample tire was tested. With regard to the specifications of the fixing layer, Table 1 shows a layer formed with the following adhesive (adhesive), and Table 2 shows a double-sided tape having the following base sheet and adhesive (adhesive). The reference comparative examples in Tables 1 and 2 are Comparative Examples 1-1 and 2-1, respectively.

[Sound-absorbing body specifications, etc.]
Material of sound-damping body: Ether-based polyurethane sponge ("G16" manufactured by Marusuzu Co., Ltd.)
Specific gravity of sound damper: 0.016
Sponge hardness: 5.0 to 500N
Tensile strength: 10.0 to 1000 kPa
Cross-sectional shape of sponge: Horizontally elongated rectangular shape with a width of 150 mm and a thickness of 10 mm (tread contact width TW = 150 mm)

[Specifications of the immobilization layer]
Adhesive (adhesive) for region 10c (central region): acrylic emulsion adhesive (acrylic resin-based)
Adhesive (adhesive) in regions 10a and 10b (one end region, the other end region): hard acrylic resin type Double-sided tape in region 10c (center region): polyethylene (base sheet), acrylic emulsion adhesive (acrylic resin type)
Double-sided tape in areas 10a and 10b (one end area, the other end area): Hard acrylic resin type Width of immobilizing layer: Same as the width of the sponge Thickness: 1.00 mm (uniform)
Storage modulus: Specifications in each table

1. Storage modulus G'
The sound damper was peeled off from the tire equipped with the sound damper, and the immobilizing layer attached to the sound damper and the inner rubber was sampled, and the storage modulus G' was measured using the above-mentioned method. When the thickness was less than 1 mm, or the sample size was smaller than the parallel plate, sampling was performed from multiple locations, and the samples were stacked on the parallel plate to obtain a predetermined immobilizing layer measurement sample, and the storage modulus G' was measured.

2. Loss tangent (tan δ)
A rubber composition was collected from the tread rubber (the rubber layer in the tread that comes into contact with the road surface) of a pneumatic tire with a noise damper, and a sample with a width of 4 mm, a length of 40 mm, and a thickness of 2 mm was cut out. The loss tangent (tan δ) was measured at a temperature of 30° C. under the conditions of a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of 1%.

3. Peel resistance (durability)
Each test tire filled with air at a specified internal pressure was pressed against a drum with multiple protrusions on its smooth surface at a specified load, and the drum was rotated at a specified speed, so that the test tire rolled freely, but the protrusions on the drum repeatedly applied a certain amount of strain to the tire, to conduct a tire durability test. The sponge peeling and destruction behavior of the tire cavity was confirmed by monitoring the cavity at each specified running distance, and the running distance until the sponge (noise-damping body) peeled off was measured. The running distance of the reference comparative example was set to 100, and the running distance of each test tire was expressed as an index. The higher the index, the better the resistance to peeling (durability).

From each table, tires in which Ga' in one end region in the tire width direction of the fixing layer of the sound-damping body fixed with a fixing layer formed using an adhesive (glue) or double-sided adhesive tape is equal to or less than Gc' in the tire width direction central region centered on the tire equator, and Gb' in the other end region is less than Gc', particularly tires adjusted to the ranges of claims 3 and 4, had excellent peel resistance (durability). In addition, tires that further satisfied 0.25≦Ga'/Gb'≦4.00 also had particularly excellent peel resistance (durability). In addition, the sound-damping properties were also good.

Furthermore, similar effects (peel resistance, quietness) were obtained when the fixation layer was formed using other adhesives (adhesives) such as the inorganic or organic adhesives (bonds) mentioned above, and when a double-sided tape (fixation layer) was formed using other base sheets such as polyethylene or polypropylene and other adhesives (adhesives) mentioned above.

1 Pneumatic tire 2 Tread portion 3 Sidewall portion 4 Bead portion 5 Bead core 6 Carcass 7 Belt layer 9 Noise-damping body 10 Fixing layers 10a, 10b One end region and other end region 10c of the fixing layer in the tire width direction Central region 10ea of the fixing layer in the tire width direction One end 10eb of the fixing layer in the tire width direction Other end 20 of the fixing layer in the tire width direction Circumferential groove 21 Mountain-shaped raised portion 2S Tread inner surface (tire cavity surface)
So Outer peripheral surface C Tire equator e1 One end of noise damper in the circumferential direction e2 Other end of noise damper in the circumferential direction ea One end of fixing layer in the circumferential direction eb Other end of fixing layer in the circumferential direction TW Tread contact width Si Inner peripheral surface W1 of noise damper Width of fixing layer in the tire width direction T Thickness of fixing layer 10 at point P

Claims (5)

A pneumatic tire having a sound-damping body fixed to a tire inner cavity surface by a fixing layer,
The fixation layer is a pneumatic tire in which an average value Gc' [Pa] of the storage elastic modulus in a 40% region consisting of 20% of the region in each of both tire width directions centered on the tire equator, and average values Ga' [Pa] and Gb' [Pa] of the storage elastic modulus in 30% regions from both ends in the tire width direction satisfy the following formulas (1) and (2).
Ga' ≦ Gc' (1)
Gb'<Gc' (2) 2. The pneumatic tire according to claim 1, which satisfies the following formula:
0.25≦Ga′/Gb′≦4.00 3. The pneumatic tire according to claim 1 or 2, which satisfies the following two formulas:
0.10≦Gb′/Gc′≦0.70
0.50≦Ga′/Gb′≦2.00 The pneumatic tire according to any one of claims 1 to 3, which satisfies the following two formulas:
0.30≦Gb′/Gc′≦0.50
0.80≦Ga′/Gb′≦1.25 A pneumatic tire according to any one of claims 1 to 4, in which the loss tangent at 30°C of the rubber composition forming the rubber layer in the tread portion that comes into contact with the road surface is 0.13 or less.

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