JPH1076818A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten the rigidity of a tire side part and enhance the car running performance including the comfortableness, straightness in running, and cornering property or the like. SOLUTION: A reinforcing rubber layer 10 consisting of rubber compound in which 2-50 part by wt. radially stretching short fibers are included relative to 100 parts by wt. rubber component, is installed between the outer side face of a carcass and the external wall surface of the tire side part 9 extending from each end of the tread part 2 to the bead part 4 via the side wall part 3 where carcass 6 turned up and a belt layer 7 are furnished, and is equipped with a first reinforcing rubber layer 11 in which short fibers are aligned and a second reinforcing rubber layer 12 in which the direction of short fibers is different from the first with the intersecting angle over 10deg., wherein the first and second reinforcing rubber layers have an overlapping part 13 in the tire axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of enhancing the rigidity of a tire side portion and improving ride comfort, straight running performance and cornering performance.

[0002]

2. Description of the Related Art As means for reducing rolling resistance in a pneumatic tire for the purpose of saving fuel consumption, conventionally, it has been known to increase the tire internal pressure, reduce the tire weight, and the like. However, although such improvement measures can reduce the rolling resistance, they reduce the riding comfort and the tire running performance such as the steering stability.

In order to solve one of the above problems, a proposal has been made to dispose a cap ply containing short fibers outside the belt layer as disclosed in Japanese Patent Application Laid-Open No. Hei 4-2740903.
It has been proposed to reinforce the side wall portion with a rubber layer containing short fibers.

[0004]

However, in the former case, the rigidity of the sidewall portion cannot be improved, and in the latter case, only one rubber reinforcing layer containing short fibers is provided. Although the rigidity of the part was slightly improved, steering stability and ride comfort could be improved, but this was not sufficient, and a measure for further increasing rigidity was required.

[0005] The inventor has conducted various studies to solve the above problems, and as a result, using two rubber reinforcing layers, the directions of the short fibers blended in each rubber reinforcing layer are crossed at a small angle. The inventors found that the rigidity of the sidewall portion was remarkably increased by the formation, and the above problem could be solved, and the present invention was completed.

An object of the present invention is to provide a pneumatic tire capable of improving ride comfort and running performance.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a carcass wound from the tread portion to the sidewall portion from the inside to the outside in the tire axial direction at the bead core of the bead portion, and a radius of the carcass inside the tread portion. A belt layer disposed on the outer side in the tire direction, and extending radially between the outer wall surface of the carcass and the outer wall surface on the tire side from both ends of the tread portion to the bead portion through the sidewall portion. And a reinforcing rubber layer comprising a rubber composition in which 2 to 50 parts by weight of short fibers are blended with respect to 100 parts by weight of the rubber component. A first reinforcing rubber layer comprising a first reinforcing rubber layer and a second reinforcing rubber layer in which the direction of short fibers is different from the first reinforcing rubber layer by an intersection angle of 10 degrees or more. The layers overlap in the tire axial direction Cormorant polymerization unit is a pneumatic tire formed by arranged with a.

The reinforcing rubber layer comprises first and second reinforcing rubber layers, and the direction of short fibers contained in the rubber composition forming each reinforcing rubber layer has an intersection angle of 10 degrees or more. Have different. As a result, the rigidity of the tire side portion is increased, and the riding comfort and steering stability can be improved.

Further, the first and second reinforcing rubber layers are arranged so as to have overlapping portions overlapping in the tire axial direction. By providing such overlapping portions, the tire side portions are effectively reinforced. sell.

The short fibers of the first reinforcing rubber layer and the short fibers of the second reinforcing rubber layer are preferably oriented at an inclination of 5 ° or more and 60 ° or less with respect to the tire circumferential direction. or,
The short fibers are organic fibers and have an average length L
(Μ) is 10 to 1000, and the aspect ratio L / D, which is the ratio of the average length L to the average short fiber diameter D (μ), is 100 to 1000.
Preferably it is 2000.

According to a third aspect of the present invention, the tire side portion includes an upper point at which a perpendicular line to a carcass passing through the outer edge of the belt layer in the tire axial direction intersects an outer surface of the carcass, and a radius of a bead core. In the tire radial direction JH of the overlapping portion is 20% of the carcass height CH from the bead base line to the radially outermost point of the carcass. It is preferable that the thickness is not less than 90% and the first and second reinforcing rubber layers are formed so as to adhere to each other in the overlapping portion.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Referring to FIGS. 1 to 3, a pneumatic tire 1 includes:
From the tread portion 2 to the bead portion 4 through the sidewall portion 3
A carcass 6 having a winding portion 6b that winds around the bead core 5 from the inside to the outside in the tire axial direction, and a belt layer 7 disposed radially outside the carcass 6 and inside the tread portion 2. In this example, a bead apex 8 is provided which extends from the bead core 5 outward in the tire radial direction in a tapered shape.

In the present embodiment, the carcass 6 comprises one or more carcass plies having a radial structure in which the carcass cord is inclined at an angle of 65 to 90 degrees with respect to the tire equator C, and in this embodiment, one carcass ply. As the carcass cord, in addition to organic fibers such as nylon, rayon, polyester, and aromatic polyamide, a steel cord or the like can be appropriately used. Preferably, an organic fiber cord is used to reduce tire weight.

In the present embodiment, the raised portion 6b of the carcass 6 has a so-called high turn-up (HTU) structure in which the tip is located near the tire maximum width point B.

In the present embodiment, the belt layer 7 is composed of two belt plies 7A and 7B overlapping inward and outward in the tire radial direction, and the width BW of the inner belt ply 7A in the tire axial direction.
Is larger than the outer belt ply 7B, and is about 0.8 to 1.2 times the tread width TW in this example.

The belt plies 7A and 7B are made of organic fibers such as nylon, polyester and aromatic polyamide.
Alternatively, by arranging a belt cord made of a steel cord at a small angle of, for example, 30 degrees or less, preferably 20 degrees or less with respect to the tire equator C and crossing each other between the belt plies 7A and 7B, the carcass 6 The tread portion 2 is strongly reinforced by giving a tag effect. In this embodiment, a band layer 21 is provided on the outer side of the belt layer 7 in the radial direction to cover the belt layer 7 over substantially the entire surface and to prevent the lifting of the belt layer 7.

The bead apex 8 is made of hard rubber,
For example, it is made of a rubber composition having a JISA hardness of about 65 to 95 degrees, and is formed so as to extend outward in the tire radial direction in a tapered cross section of the tire.

The reinforcing rubber layer 10 is provided in the outer wall rubber 16 between the outer wall surface 9a of the tire side portion 9 and the outer surface of the carcass 6.

The tire side portion 9 is a portion between each end of the tread portion 2 and the bead portion through the sidewall portion 3, and in this example, a belt formed by an edge of the inner belt ply 7A in the tire axial direction. It is set as a range between an upper point P where a perpendicular V to the carcass 6 passing through the outer edge F of the layer 7 intersects the outer surface of the carcass 6 and a lower point Q which is a radial outer end 5 a of the bead core 5. I have.

The reinforcing rubber layer 10 includes a first reinforcing rubber layer 11
And a second reinforcing rubber layer 12. The first and second rubber layers 11, 12 are arranged so as to have a superposed portion 13 overlapping in the tire axial direction.

The first and second reinforcing rubber layers 11 and 12
Is formed by a rubber composition in which 2 to 50 parts by weight of short fibers are blended in a uniform direction with respect to 100 parts by weight of the rubber component.

In this example, the rubber component is formed by mixing 30 to 60 parts by weight of natural rubber NR and / or isoprene rubber (IR) with 40 to 70 parts by weight of butadiene rubber (BR). In forming the composition, 15 to 25 parts by weight of carbon black is contained in addition to the short fibers.

Examples of the short fibers include organic fibers such as nylon, polyester, aramid, rayon, vinylon, aromatic polyamide, cotton, cellulose resin, and crystalline polybutadiene, as well as metal fibers, whiskers, boron, and glass fibers. Inorganic materials can be used, and these can be used alone or in combination of two or more. More preferably, the short fibers may be subjected to a surface treatment to improve the adhesiveness with the rubber component. .

The amount of the short fibers is 100
2 to 50 parts by weight, preferably 10 to 2 parts by weight based on parts by weight
0 parts by weight. If the short fiber is less than 2 parts by weight, it is not possible to secure the rigidity in the circumferential direction of the tire as described below, and there is no effect on the improvement of steering stability. .

The average length L (μ) of the short fibers is 10 to 1
000, particularly preferably in the range of 50 to 1000. Also,
The aspect ratio (L / D), which is the ratio of the fiber length (L) to the fiber diameter (D), is 100 to 2000, particularly 200 to 2000.
Is preferred. If the ratio (L / D) is less than 100, that is, if the fiber length with respect to the fiber diameter is small, sufficient strength due to the orientation of short fibers described below cannot be imparted to the rubber. The average length L and the average short fiber diameter of the short fibers mean that the length or diameter is distributed within a range of ± 50% of the respective nominal length and nominal diameter.

It is important that at least 90% of the short fibers are oriented at an angle of ± 20 ° with respect to the circumferential direction of the tire. And riding comfort can be improved at the same time. If the short fibers are not oriented in the predetermined direction, rigidity in the tire circumferential direction cannot be increased, and the effect of improving steering stability is small.

The orientation of the short fibers is specifically determined by the ratio (E * b) of the complex elastic modulus E * a in the orientation direction of the short fibers and the complex elastic modulus E * b in the direction perpendicular to the orientation direction. * A / E *
b) and this ratio is greater than or equal to 5, preferably between 7 and
It needs to be 20. This ratio (E * a / E *
If b) is less than 5, the ride comfort is improved, but the steering stability, especially the handle response, is undesirably reduced.
The complex elastic modulus and the above-described loss tangent (tan δ) are measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. as described in Examples.

Examples of the carbon black include HAF (82) and FEF (4) commercially available from Showa Cabot, Mitsubishi Chemical, Tokai Carbon, and the like.
3), GPF (36) and the like can be suitably used, and those having an iodine adsorption amount of 30 to 90 mg / g are preferably used.

The carbon black has an iodine adsorption amount of 3
If it is less than 0 mg / g, the rubber reinforcing property is low, and the strength and cut resistance are both inferior. On the other hand, if it exceeds 90 mg / g, the heat generation is high and the rolling resistance may be deteriorated.

As described above, the amount of the carbon black to be added is about 15 to 25 parts by weight based on 100 parts by weight of the rubber component. When the content of the carbon black exceeds 25 parts by weight, the heat generation of the rubber increases, and the rolling resistance also increases. That is, in the present invention, by orienting the short fibers in the circumferential direction, the elastic modulus in the tire circumferential direction can be increased, and the hardness of the entire rubber and the amount of carbon black that enhances heat generation can be reduced. As a result, it is possible to balance the rolling resistance and the steering stability and reduce the weight.

The rubber component of the reinforcing rubber layer 10 may further contain oil, an antioxidant, a wax, a vulcanization accelerator and the like as additives.

The above components are kneaded and extruded by an extruder calender or the like according to a conventional method to form a rubber sheet body reinforced by short fibers having 90% or more of the short fibers oriented in the extrusion direction. Is done.

The first and second reinforcing rubber layers 11 and 12
Each have a thickness of 0.3 to 1.0 mm, preferably 0.1 to 1.0 mm.
5 to 1.0 mm. If the thickness exceeds 1.0 mm, the orientation of the short fibers is inferior, and the expected difference in rigidity cannot be obtained. As a result, the improvement in steering stability is small, and the tire weight increases to increase the rolling resistance. On the other hand, if it is smaller than 0.3 mm, production becomes difficult.

Also, the first and second reinforcing rubber layers 11 and 12
Are oriented such that the directions of the short fibers 14 intersect at an intersection angle θ of 10 degrees or more, as shown in FIGS. If the crossing angle θ is less than 10 degrees, the stagnant effect of the short fibers 14 cannot be exerted, the rigidity of the tire side portion 9 does not increase, and the steering stability and the riding comfort cannot be improved. More preferably, the intersection angle θ is set to 20 degrees or more.

In this embodiment, the inclination α, α1 of the short fibers 14, 14 with respect to the tire circumferential direction between the first and second rubber reinforcing layers 11, 12 is more than 5 degrees and 60 degrees, respectively.
Degrees or less. As a result, the circumferential rigidity of the tire is increased, and the turning stability and the straight running stability are enhanced. On the other hand, the rigidity in the radial direction of the tire is not greatly increased, and the riding comfort is maintained. More preferably, the inclination α is 5 to 30.
It is better to be in the range of degrees.

The first reinforcing rubber layer 11 and the second reinforcing rubber layer 12 are connected to each other with a superposed portion 13 which closely overlaps in the tire axial direction. The length JH of the overlapping portion 13 in the tire radial direction is not less than 20% and not more than 90% of the carcass height CH, which is the distance in the tire radial direction from the bead base line H to the radially outermost point K of the carcass 6. You have set. When the length JH of the overlapping portion JH is less than 20% of the carcass height CH, the rigidity of the tire side portion 9 cannot be expected because the length of the overlapping portion is small, and the steering stability is inferior, but exceeds 90%. And the stiffness of the tire side portion 9 becomes excessive, and the ride comfort is reduced, preferably 40 to 90%.
Is within the range.

In addition, between the reinforcing rubber layer 10 and the outer wall surface 9a,
Alternatively, a normal rubber ply made of a rubber composition containing no short fibers may be further provided between the reinforcing rubber layer 10 and the carcass 6.

Further, the carcass 6 is formed as shown in FIG.
In the case where the reinforcing rubber layer 10 is formed with the a, the tire is easily formed by disposing the reinforcing rubber layer 10 on the outer side in the tire axial direction of the winding portion 6a.

[0040]

EXAMPLES A tire having a tire size of 185 / 60R14 and having the structure shown in FIG. 1 was prototyped according to the specifications shown in Table 1 (Examples 1 to 4), and its performance was tested. Tires outside the configuration of the present application (Comparative Examples 1 to 4)
A test was also conducted for 3), and the performance was compared. Further, the configuration of the carcass and the belt layer and the rubber composition of the reinforcing rubber layer were the same in both the examples and comparative examples.

[0041]

[Table 1]

[0042]

[Table 2]

The straight running stability, ride comfort, and cornering performance are as follows:
1. Attach each test tire to 5.5J × 14 rim,
Under the internal pressure of 0 kgf / cm ² , the FF was mounted on the front and rear wheels of a 2000cc class front-wheel-drive vehicle and run on a paved road.
Is set to 100 and the index is shown. The higher the value, the better.

As a result of the test, it was confirmed that the driving performance of the embodiment was improved in running performance such as straight running stability and cornering performance while maintaining the riding comfort, as compared with that of the comparative example.

[0045]

As described above, the pneumatic tire of the present invention has the following features.
Two reinforcing rubber layers made of a rubber composition containing short fibers are arranged on the tire side so that the directions of the short fibers of each reinforcing rubber layer cross at an angle of 10 degrees or more, and the two reinforcing rubber layers overlap. Since the gist of the present invention has the overlapping portion, the rigidity of the tire side portion can be increased, and the riding performance and running performance such as straight running performance and cornering performance can be improved.

[Brief description of the drawings]

FIG. 1 is a right half sectional view of a tire showing an example of an embodiment of the present invention.

FIG. 2 is a side view showing the reinforcing rubber layer.

FIGS. 3A and 3B are diagrams showing directions of short fibers of a reinforcing rubber layer.

[Explanation of symbols]

 Reference Signs List 2 tread part 3 side wall part 4 bead part 5 bead core 5a outer end 6 carcass 7 belt layer 9 tire side part 9a outer wall surface 10 reinforcing rubber layer 11 first reinforcing rubber layer 12 second reinforcing rubber layer 13 overlapping part 14 short Fiber D Average short fiber diameter F Outer edge of belt layer H Bead base line L Average length of short fiber P Upper point Q Lower point V Perpendicular α, α 'Slope of short fiber in circumferential direction θ Crossing angle

Claims (4)

[Claims] 1. A carcass wound from a tread portion to a sidewall portion from a bead core of a bead portion to an inside from a tire axial direction to an outside thereof, and a belt layer disposed inside the tread portion and radially outside the carcass. Between the outer wall surface of the carcass and the outer wall surface of the tire side extending from both ends of the tread portion to the bead portion through the sidewall portion, and extending in the radial direction with respect to 100 parts by weight of the rubber component. A reinforcing rubber layer made of a rubber composition containing 2 to 50 parts by weight of short fibers, and the reinforcing rubber layer comprises a first reinforcing rubber layer in which short fibers are oriented in the same direction as the first reinforcing rubber layer. The direction of the short fiber is 10 in the rubber layer.
A second reinforcing rubber layer having a crossing angle of not less than degrees and different, and the first and second reinforcing rubber layers are arranged so as to have an overlapped portion overlapping in the tire axial direction. Containing tires. 2. The short fiber is an organic fiber having an average length L (μ) of 10 to 1000, and an aspect ratio which is a ratio of the average length L to an average short fiber diameter D (μ). The pneumatic tire according to claim 1, wherein L / D is 100 to 2,000. 3. The tire side portion includes an upper point where a perpendicular to a carcass passing through an outer edge of the belt layer in the tire axial direction intersects an outer surface of the carcass, and a lower point which is a radial outer end of the bead core. And the length JH of the overlapping portion in the tire radial direction is not less than 20% and not more than 90% of the carcass height CH from the bead base line to the outermost point of the carcass in the radial direction. 2. The pneumatic tire according to claim 1, wherein the first and second reinforcing rubber layers adhere to each other in the overlapping portion. 4. The short fibers of the first reinforcing rubber layer and the short fibers of the second reinforcing rubber layer are oriented at an inclination of 5 degrees or more and 60 degrees or less with respect to the tire circumferential direction. The pneumatic tire according to claim 1, wherein