阅读说明：本技术 充气轮胎 (Pneumatic tire ) 是由 佐藤拓也 汤川直树 松波翔 于 2021-03-18 设计创作，主要内容包括：本发明的课题在于提供以下的充气轮胎：在刺穿孔大时,也能充分发挥刺穿密封性能。本发明的充气轮胎是以下的充气轮胎：在胎面部(2)的内周面(2s)上配置有防止刺穿用的密封层(11),并且在密封层(11)的内周面(11s)上配置有噪声抑制体(12)。噪声抑制体(12)是由具有独立气泡的海绵材料所构成,且空气透过量为20mL/cm～(2)/s以下。(The present invention addresses the problem of providing a pneumatic tire that: when the puncture hole is large, the puncture sealing performance can be fully exerted. The pneumatic tire of the present invention is a pneumatic tire comprising: a sealing layer (11) for preventing puncture is disposed on the inner peripheral surface (2s) of the tread portion (2), and a noise suppressor (12) is disposed on the inner peripheral surface (11s) of the sealing layer (11). The noise suppressing body (12) is made of a sponge material having independent air bubbles and has an air permeability of 20mL/cm 2 The ratio of the water to the water is less than s.)

1. A pneumatic tire, which is a pneumatic tire of: a sealing layer for preventing puncture is arranged on the inner circumferential surface of the tread portion, and a noise suppressor is arranged on the inner circumferential surface of the sealing layer;

the noise suppressor is made of sponge material with independent air bubbles, and the air permeability is 20mL/cm²The ratio of the water to the water is less than s.

2. The pneumatic tire according to claim 1, wherein the hardness of the noise suppressing body is 300N/314cm²The following.

3. The pneumatic tire according to claim 1, wherein the hardness of the noise suppressing body is 10N/314cm²The above.

4. The pneumatic tire according to claim 1 or 2, wherein the tensile strength of the noise suppressing body is 20kPa or more.

5. The pneumatic tire according to claim 1 or 2, wherein the tensile strength of the noise suppressing body is 400kPa or less.

6. The pneumatic tire according to any one of claims 1 to 3, wherein the thickness of the noise suppressing body is 20mm or more.

7. The pneumatic tire according to any one of claims 1 to 3, wherein the thickness of the noise suppressing body is 50mm or less.

Technical Field

The present invention relates to a pneumatic tire having improved puncture sealing performance.

Background

Patent document 1 proposes a pneumatic tire having both puncture sealing performance and road noise reduction performance. The pneumatic tire of this proposal has a puncture-preventing sealing layer made of a sealing material on the inner side of the inner liner layer in the tire radial direction, and has a sound absorbing layer made of a sponge material or the like on the inner side of the sealing layer in the tire radial direction.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2017-65673

Disclosure of Invention

Problems to be solved by the invention

However, the proposed pneumatic tire has a problem that when the puncture hole is large (for example, when a thick nail or the like is inserted), it is difficult to sufficiently close the puncture hole with the sealing material, and the puncture sealing performance cannot be sufficiently exhibited.

The present invention addresses the problem of providing a pneumatic tire that can sufficiently exhibit puncture sealing performance even when a puncture hole is large.

Means for solving the problems

The pneumatic tire of the present invention has a sealing layer for preventing puncture on the inner circumferential surface of a tread portion, and a noise suppressing body on the inner circumferential surface of the sealing layer; the noise suppressor is made of sponge material with independent air bubbles, and the air permeability is 20mL/cm²The ratio of the water to the water is less than s.

In the pneumatic tire according to the present invention, the hardness of the noise suppressing body is preferably 300N/314cm²The following.

In the pneumatic tire according to the present invention, the tensile strength of the noise suppressor is preferably 20kPa or more.

In the pneumatic tire according to the present invention, the thickness of the noise suppressing body is preferably 20mm or more.

In the present invention, the "air permeability" of the sponge material is measured according to the following measurement method. As shown in FIGS. 5(a) and (b), a sample A of a sponge material having a width W of 60mm, a depth L of 60mm and a thickness T of 30mm was closely attached to a hole H having a diameter of 1mm (the opening area corresponded to 0.00785 cm)²) Plate B having a thickness of 10 mm. At this time, the sample A was closely adhered so that the center of the surface having the width W × the depth L of the sample A was positioned as the hole H. Further, the pressure P2 on the sample a (sponge material) side was increased, and the pressure difference (P2-P1) between the pressure P2 and the pressure P1 on the plate B side was set to 200kPa, at which time the air flow rate (mL) leaking from the hole H per second(s) was measured. The flow rate was 1.0cm in terms of the opening area²The value of time was taken as the air permeation amount (mL/cm)²/s)。

In the present invention, the hardness of the sponge is measured in accordance with JIS-K6400-2 "Soft foam-physical Properties-part 2: hardness and compressive stress-deformation characteristics were obtained by measurement according to method D of the 6 th hardness test defined in "method for obtaining hardness and compressive stress-deformation characteristics". Specifically, the sponge was laid flat, a circular pressing plate having a diameter of 200mm was loaded, the sponge was pressed to a distance of 75% of the thickness (original thickness) of the sponge in the unloaded state, and then the sponge was returned to the original state and pressed again to a distance of 25% of the original thickness, and the load value at rest for 20 seconds was represented by N (newton).

In the present invention, the tensile strength of the sponge is measured in accordance with JIS-K6400-5 "Soft foam-physical Properties-part 5: the tensile strength, elongation and tear strength were obtained by measuring the tensile strength and elongation of the dumbbell test piece having the shape of No. 1 in item 5 defined in the method for obtaining tensile strength, elongation and tear strength.

Effects of the invention

As described above, the noise suppressing body of the present invention is constituted by a sponge material having independent air bubbles, and the air permeability is 20mL/cm²The ratio of the water to the water is less than s. The air permeability was measured according to the above measurement method.

In the present invention, even when the pierced hole is large and the pierced seal cannot be sufficiently performed by the sealing material, the air permeation amount of the noise suppressing body is 20mL/cm²The air tightness is excellent at a value of/s or less, and thus the noise suppressing member itself can suppress the outflow of air from the pierced hole.

Further, since the noise suppressor has high airtightness, the operation of pressing the sealing material around the pierced hole can be performed. Therefore, the sealing material is easily pressed into the pierced hole, and the effect of blocking the pierced hole by the sealing material can also be improved. In addition, these interactions can improve the puncture sealing performance and thus improve the success rate of the puncture seal.

Drawings

Fig. 1 is a sectional view showing an embodiment of a pneumatic tire of the present invention.

Fig. 2 is a conceptual diagram illustrating the effect of the noise suppressor.

Fig. 3 is a partial sectional view exaggeratedly illustrating the press-fitting effect of the sealing material.

Fig. 4(a) and (b) are cross-sectional views showing a problem point when the tensile strength of the noise suppressor is small.

Fig. 5(a) and (b) are a perspective view and a cross-sectional view for explaining a method of measuring air permeability of the noise suppressor.

[ notation ] to show

1 pneumatic tire

2 tread portion

2s inner peripheral surface

11 sealing layer

11s inner peripheral surface

12 noise suppressor

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail.

As shown in fig. 1, a pneumatic tire 1 of the present embodiment is a tubeless tire, and includes: a puncture-proof sealing layer 11 disposed on the inner circumferential surface 2s of the tread portion 2; and a noise suppressor 12 disposed on the inner peripheral surface 11s of the sealing layer 11.

In this example, the pneumatic tire 1 has disposed therein: a carcass 6 passing from the tread portion 2 through the sidewall portion 3 and reaching the bead core 5 of the bead portion 4; and a belt layer 7 located radially outside the carcass 6 and inside the tread portion 2.

The carcass 6 is formed by arranging 1 or more carcass cords, in this example, 1 carcass ply 6A. The carcass ply 6A has turn-up portions 6b turned up at the bead cores 5 at both ends of the main body portion 6A spanning between the bead cores 5, 5. Between the main body portion 6a and the folded portion 6b, a bead apex rubber 8 for bead reinforcement extending outward in the tire radial direction from the bead core 5 is provided.

The belt layer 7 is formed of a plurality of (for example, 2) belt layers 7A and 7B in which belt cords are arranged. A belt (band) layer (not shown) obtained by spirally winding a belt cord may be provided on the radially outer side of the belt layer 7 for the purpose of improving the high-speed durability of the tire.

An inner liner rubber layer 10 is disposed inside the carcass 6. The inner liner rubber layer 10 is made of air-impermeable rubber such as butyl rubber, and maintains the tire inner pressure in an airtight state.

The sealing layer 11 is disposed on the inner circumferential surface 2s of the tread portion 2. As the sealing material 13 for forming the sealing layer 11, the material described in patent document 1 is suitably used. Specifically, the sealing material 13 of this example contains a rubber component, a liquid polymer, a crosslinking agent, and the like.

As the rubber component, butyl rubber such as butyl rubber and halogenated butyl rubber is used. The rubber component is preferably a rubber component obtained by mixing the butyl rubber and the diene rubber.

Examples of the liquid polymer include liquid polybutene, liquid polyisobutylene, liquid polyisoprene, liquid polybutadiene, liquid polyalphaolefin, liquid isobutylene, liquid ethylene- α -olefin copolymer, liquid ethylene-propylene copolymer, liquid ethylene-butene copolymer, and the like. Among them, liquid polybutene is preferable from the viewpoint of imparting tackiness and the like.

As the crosslinking agent, a well-known compound, preferably an organic peroxide, can be used. By using a butyl rubber or a liquid polymer in the organic peroxide crosslinking system, adhesiveness, sealing property, fluidity, and processability can be improved.

The sealing material 13 may be appropriately added with a crosslinking aid (vulcanization accelerator), an inorganic filler, a plasticizer, and the like.

The sealing layer 11 is formed by: on the inner peripheral surface 2s of the tread portion 2 of the tire molded by vulcanization in advance, a sealing material 13 made by adjusting and mixing the above-mentioned materials is applied. As described in patent document 1, for example, the sealing material 13 continuously extruded from a biaxial kneading extruder is preferably spirally adhered to the inner circumferential surface 2s of the tread portion 2 of the rotating tire. The sealing material 13 is vulcanized by heating the tire coated with the sealing material 13, thereby forming the sealing layer 11 having excellent sealing properties.

The width 11W of the seal layer 11 in the tire axial direction is not particularly limited, but is preferably 80% to 120% of the tread ground contact width TW. The lower limit of the width 11W is more preferably 85% or more, and still more preferably 90% or more of the tread ground contact width TW. The upper limit of the width 11W is more preferably 115% or less, and still more preferably 110% or less of the tread ground contact width TW.

The meaning of the tread ground-contact width TW is as follows: the maximum width of a ground contact surface to be grounded in the tire axial direction when a standard load is applied to the tire in a state where the tire is mounted on a standard rim and filled with a standard internal pressure. The "standard rim" means a rim specified for each tire in a standard system including a standard under which the tire is based; for example, if JATMA, then "standard rim"; if TRA, it represents "Design Rim (Design Rim)"; or if ETRTO, it means "Measuring Rim". The "standard internal pressure" is an air pressure specified for each tire by the above-mentioned standard; if JATMA, the maximum air pressure is represented; if it is TRA, it indicates the maximum value described in "Tire load limits at various cold inflation pressures (Tire load limits at variable Tire inflation pressures)"; if ETRTO, then represent "Inflation pressure"; however, in the case of a passenger car tire, the "standard internal pressure" is set to 180 kPa. The "standard load" is a load specified for each tire by the above-mentioned standard; if JATMA, the maximum load capacity is represented; if it is TRA, it indicates the maximum value described in "Tire load limits at various cold inflation pressures (Tire load limits at variable Tire inflation pressures)"; if ETRTO, it indicates "Load capacity".

In the present specification, unless otherwise specifically stated, the respective part sizes and the like of the tire mean specific values in the no-load state filled with the above-mentioned standard internal pressure.

The thickness 11t of the sealing layer 11 is preferably 1.0mm or more, more preferably 2.0mm or more, and further preferably 3.0mm or more. The upper limit of the thickness 11t is preferably 10.0mm or less, more preferably 8.0mm or less, and further preferably 5.0mm or less. When the thickness 11t is less than 1.0mm, it is difficult to reliably block the pierced hole. On the contrary, even if the thickness 11t exceeds 10.0mm, the effect of clogging the puncture hole is not so changed, resulting in a disadvantage of increasing the tire mass.

A noise suppressor 12 made of a sponge material is disposed on the inner peripheral surface 11s of the sealing layer 11. The noise suppressor 12 is adhered to the sealing layer 11 by the adhesive force of the sealing material 13.

The noise suppressing body 12 extends in the tire circumferential direction. In particular, it is preferable to form the noise suppressor 12 in an annular shape in which both ends in the tire circumferential direction are opposed to each other. In this case, the distance between the ends of the noise suppressing body 12 in the tire circumferential direction may be preferably 80mm or less, more preferably 70mm or less, and still more preferably 60mm or less.

As the sponge material forming the noise suppressing body 12, a foam having closed cells formed by foaming rubber and synthetic resin can be used. Examples of the rubber foam include chloroprene rubber sponge, ethylene propylene rubber sponge, and nitrile rubber sponge. Examples of the synthetic resin foam include polyurethane-based sponges (e.g., ether-based polyurethane sponges, ester-based polyurethane sponges, and ether/ester-based polyurethane sponges), polyethylene-based sponges (e.g., polyethylene sponges), and the like.

The sponge material preferably has a density of 60kg/m for the purpose of exhibiting sound-damping performance³Hereinafter, more preferably 55kg/m³Hereinafter, more preferably 50kg/m³The following. Further, the lower limit of the density is preferably 10kg/m³Above, more preferably 15kg/m³Above, more preferably 20kg/m³The above.

Further, the air permeability of the noise suppressor 12 was 20mL/cm²The ratio of the water to the water is less than s.

As the "air permeability", it is determined according to the above-mentioned determination method. The air permeation amount was 20mL/cm²The following values/s are values assuming the following case: for example, in a tire for a passenger car filled with 200kPa air, the pressure drops by 10 to 15kPa per day by the amount of air leakage (amount of air leakage from a hole having a diameter of 1 mm).

Such a noise suppressor 12 has a low air permeability and excellent airtightness. Therefore, as shown in fig. 2(a) and (b), for example, when the puncture hole H is large and the puncture sealing cannot be sufficiently performed by the sealing material 13, the noise suppressing body 12 itself blocks the puncture hole H and suppresses the outflow of air. This effect may be referred to as a "noise suppressor sealing effect".

Further, since the noise suppressor 12 is excellent in airtightness, the sealing material 13 around the puncture hole H can be pressed. Therefore, the sealing material 13 is easily pushed into the pierced hole H, and the effect of blocking the pierced hole H by the sealing material 13 is improved. This effect may be referred to as a "seal material press-fitting effect". In addition, the sealing effect of the noise suppressor and the pressing effect of the sealing material are mutually acted, so that the piercing sealing performance is improved, and the success rate of piercing sealing can be improved.

The thickness 12t of the noise suppressor 12 is preferably 20mm or more. Therefore, the noise suppressor 12 is less likely to be penetrated by the foreign matter 20 such as a nail, and the above-described effects can be more reliably exhibited. As a result of market research, the length of foreign matter penetrating into the tire is substantially 25mm or less in the market. Therefore, when the thickness 12t of the noise suppressing body 12 is 20mm or more in consideration of the tire thickness, penetration of the noise suppressing body 12 by the foreign matter 20 can be almost reliably prevented.

When the air permeability exceeds 20mL/cm²At the time of/s, the noise suppressor 12 easily passes air, and thus the noise suppressor sealing effect cannot be sufficiently exhibited. Further, the sealing material press-fitting effect cannot be sufficiently expected. From such a viewpoint, the upper limit of the air permeation amount is preferably 15mL/cm²Less than s, more preferably 10mL/cm²Less than s, more preferably 5mL/cm²The ratio of the water to the water is less than s. The lower limit of the air permeation amount is not particularly limited, and is preferably set lower.

When the thickness 12t of the noise suppressor 12 is less than 20mm, the foreign matter 20 such as a nail penetrates through the hole, and air leaks from the penetrating hole, and the sealing effect of the noise suppressor cannot be sufficiently exhibited. Therefore, the lower limit of the thickness 12t is preferably 25mm or more, and more preferably 30mm or more. However, when the thickness 12t is too large, the following problems are caused: the mass increases and the noise suppressing body 12 falls off from the sealing layer 11 due to the centrifugal force. In addition, adverse effects on the workability in assembling and disassembling the rim are also considered. Therefore, the upper limit of the thickness 12t is preferably 50mm or less, more preferably 45mm or less, and further preferably 40mm or less.

Further, during traveling, due to the centrifugal force, the noise suppressor 12 applies a force in a direction in which the thickness 12t decreases. However, the noise suppressor 12 formed of a sponge material having a low air permeability is supported by the air in the independent air cells, so that the volume reduction is small and the damping performance can be stably exhibited.

The width 12W of the noise suppressing body 12 in the tire axial direction may be smaller than the width 11W of the sealing layer 11, the same as or larger than this. When the width 12W is smaller than the width 11W (12W < 11W), the puncture sealing performance can be exhibited by the original performance of the seal layer 11 even at the position of the seal layer 11. When the width 12W is equal to or larger than the width 11W (12 W.gtoreq.11W), the sealing effect of the noise suppressor and the press-in effect of the sealing material can be exhibited over the entire surface of the sealing layer 11. However, from the viewpoint of balance among damping performance, weight, rim assembling workability, and the like, the width 12W is desirably 40% or more, more desirably 45% or more, and still more desirably 50% or more of the width 11W. The upper limit of the width 12W is preferably 100% or less, more preferably 95% or less, and further preferably 90% or less of the width 11W. However, when applied to a tire having a narrow width, the noise suppressing body 12 may fall off even when the width 12W of the noise suppressing body 12 is excessively narrow within the above range. Therefore, the width 12W is preferably equal to or larger than the thickness 12 t.

In order to more effectively exert the effect of pressing the sealing material into the noise suppressor 12, the hardness of the noise suppressor 12 is preferably 300N/314cm²The following. As a result, as shown exaggeratedly in fig. 3, the noise suppressor 12 bends and intensively presses the sealing material 13 around the pierced hole H, and the pressing and flowing of the sealing material 13 into the pierced hole H can be improved. In this regard, the hardness of the noise suppressor 12 exceeds 300N/314cm²The hardness of (3) is widely dispersed in the pressing force, and it is difficult to press the sealing material 13 around the pierced hole intensively. From such a viewpoint, noise suppressionThe hardness of the body 12 is preferably 100N/314cm²Hereinafter, more preferably 80N/314cm²The following. However, even if the hardness is too low, the flow of the sealing material 13 will be deteriorated. Therefore, the lower limit of the hardness is preferably 10N/314cm²Above, more preferably 20N/314cm²Above, it is more preferably 30N/314cm²The above.

In the noise suppressor 12, the tensile strength is preferably 20kPa or more. When the tensile strength is less than 20kPa, as shown in fig. 4(a), when the foreign substance 20 penetrates the noise suppressor 12, the foreign substance 20 attached with the sealing material 13 easily tears a part of the sponge (noise suppressor 12). Then, when the foreign matter 20 falls out of the tire, as shown in fig. 4(b), the torn sponge sheet 15 remains in the puncture hole H, resulting in a tendency to hinder the puncture sealing by the sealing material 13. From such a viewpoint, the tensile strength of the noise suppressor 12 is preferably 100kPa or more, and more preferably 120kPa or more. The upper limit of the tensile strength is not particularly limited, but is preferably higher.

In addition, from the viewpoint of preventing the sponge material from being torn, it is preferable that the noise suppressor 12 be easily peeled off from the sealing material. Thus, when a foreign object penetrates and is pulled out, the sponge material becomes difficult to tear, and therefore, piercing of the seal is not hindered.

Therefore, the adhesive force between the noise suppressor 12 and the sealing material, which is defined by the following measurement method, is preferably 5.0N/cm²The following. The measurement method is as follows. First, a rectangular parallelepiped test piece having a square adhesive surface of 30mm × 30mm and a thickness of 10mm was cut out from the noise suppressor 12, and the adhesive surface of the test piece was brought into close contact with the flat sealing layer 11. The surface opposite to the bonding surface of the test piece was firmly bonded to the jig. Next, the test piece was stretched perpendicularly to the sealing layer 11 using the above-mentioned jig, the force at which the test piece was peeled from the sealing layer 11 was measured, and the force was divided by the area of the adhesive surface of the test piece to obtain the adhesive force. Further, the drawing speed of the jig was set to 300mm m/min. The above adhesive force is preferably 4.5N/cm²Hereinafter, more preferably 4.0N/cm²The following. Further, the lower limit of the adhesive force is preferably 0.1N/cm²Above, more preferably 0.5N/cm²Above, more preferably 1.0N/cm²The above.

While the particularly preferred embodiments of the present invention have been described in detail, the present invention is not limited to the embodiments shown in the drawings, and can be carried out in various forms.

[ examples ] A method for producing a compound

Pneumatic tires (tire size: 215/55R17) having the basic structure shown in fig. 1 and to which noise suppressors having the specifications shown in table 1 were attached were tried, and the puncture sealing success rate (puncture sealing performance) of each of the tried tires was evaluated.

Various ether/ester-based polyurethane sponges (density 31 kg/m) were used as noise suppressors³). Each test tire has substantially the same specification except for the noise suppressor.

< puncture sealing success rate >

50 nails (JIS N150 nails: 5.2mm in diameter and 40mm in length) were driven into the groove bottom portion on the tire equator line in the tread portion of the test tire filled with the internal pressure (250kPa) in a dispersed manner in the circumferential direction. Subsequently, the nail was removed after being left at room temperature and 25 ℃ for 1 hour, and soapy water was injected into the pierced hole to confirm the presence or absence of gas leakage. The success rate of piercing and sealing was determined from the number of piercing holes having no air leakage, and evaluated. The larger the value, the more excellent the puncture sealing performance.

[ TABLE 1 ]

As shown in the table, it was confirmed that example samples can improve the puncture sealing success rate.

The thickness of the sealing layer was 3.0mm, and a sealing material having the composition shown in Table 2 was used. The various chemicals shown in table 2 are shown below.

Butyl rubber: IIR065 manufactured by JSR corporation

Polybutene: HV-1900, manufactured by JX Nissan energy Co., Ltd., number average molecular weight 2900

Carbon black: n330 manufactured by Cabot Japan K.K

Oil: DOS (dioctyl sebacate), manufactured by Taoka chemical industries, Ltd

Crosslinking agent: niper NS (BPO 40%, DBP 48%), manufactured by Niber oil Co., Ltd

Crosslinking coagents: QO (quinone dioxime), manufactured by Innovative chemical industries, Ltd

[ TABLE 2 ]

Sealing material	Proportioning (parts by mass)
		Butyl rubber	100
Polybutylene	200
		Carbon black	15
Oil	15
		Crosslinking agent	7
Crosslinking aid	7