JP2869323B2 - Steel radial tires for passenger cars - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel radial tire for a passenger car which can suppress the peeling damage of an inner liner rubber without deteriorating the internal pressure holding property and can achieve a reduction in tire weight and a reduction in rolling resistance.

[0002]

2. Description of the Related Art In a tubeless tire, an inner liner rubber is provided on an inner surface of a carcass in order to keep air at an internal pressure airtight. Conventionally, the inner liner rubber has a butyl rubber layer, which is mainly composed of butyl rubber having excellent air permeability resistance and is disposed over the entire surface of the tire cavity to prevent air leakage of the tire, and has a natural rubber as a main component. It has a two-layer structure of a butyl rubber layer and a natural rubber layer that enhances adhesion to the carcass by being interposed between the butyl rubber layer and the carcass.

[0003]

However, such a conventional two-layer structure requires a thick inner liner rubber, which results in an increase in tire weight and an increase in rolling resistance due to an increase in tread thickness. And hinders the fuel efficiency of the vehicle.

Accordingly, the present inventor has accumulated research on various functions of a tire related to inner liner rubber in order to solve these problems. As a result, since the tread portion is thick and protected by the steel belt layer, the ratio of the air leak should be 10% or less of the total air leak; The inner liner rubber is liable to be peeled and damaged because of its large size.
More than 0%; the bead portion has a small tire deformation and is thick, so that the air leak ratio is about 20% and the risk of peeling damage is small.

That is, according to the present invention, the inner liner rubber is formed of a natural rubber layer containing natural rubber as a main component and a butyl rubber layer located inside the rubber layer and containing butyl rubber as a main component. It is an object of the present invention to provide a steel radial tire for a passenger car that can maintain airtightness, prevent peeling of an inner liner rubber, and reduce the weight of a tire, based on a difference between a tread portion, a sidewall portion, and a bead portion.

[0006]

In order to achieve the above object, a steel radial tire for a passenger car according to the present invention is folded around a bead core of a bead portion from a tread portion to a sidewall portion and surrounds a tire cavity. A carcass, a belt layer using a cord made of steel disposed radially above the carcass and below the tread portion, a bead apex rubber rising radially upward from the bead core, and located inside the carcass and An inner liner rubber continuously disposed facing the tire cavity, wherein the inner liner rubber extends from the tire equatorial plane to a position near the upper end of the bead apex and includes natural rubber (NR A) a natural rubber layer having a maximum content of said natural rubber layer; It is characterized in that the outer end position near the belt layer is formed from the maximum and butyl rubber layer the content of butyl rubber (IIR) of beauty Moreover rubber component to the upper end vicinity of the bead core.

[0007]

[Effect] Because it is configured as described above, the tread part,
In particular, in the region between the tire equatorial plane and the position near the outer edge of the belt layer, the inner liner rubber has a single-layer structure of only a natural rubber layer excluding a butyl rubber layer, and provides a minimum necessary air leak resistance. While reducing the thickness of the rubber, the tire weight and the rolling resistance can be reduced.

In the side wall portion, particularly in the region between the position near the outer end of the belt layer and the position near the upper end of the bead apex, a two-layer structure of a natural rubber layer and a butyl rubber layer is formed.
Demonstrate extremely high air leak resistance. Moreover, because a natural rubber layer is interposed between the butyl rubber layer and the carcass,
Adhesion with the carcass is greatly increased, and peeling damage of the inner liner rubber can be effectively prevented.

In the bead portion, particularly in the region between the position near the upper end of the bead apex and the position near the upper end of the bead core,
Since it has a one-layer structure of only the butyl rubber layer, the rubber thickness can be reduced while exhibiting relatively high air leak resistance. Moreover, in this region, since the deformation is small, peeling of the butyl rubber layer from the carcass can be suppressed.

As described above, since the inner liner rubber is formed of the natural rubber layer and the butyl rubber layer, and the arrangement of the rubber layer is different in each region, the air leak resistance and the peeling resistance are each excessive quality. It is possible to make the entire tire uniform without causing the tire to become lighter, to reduce the rolling resistance, to reduce the cost, and the like.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 showing a state in which the rim is assembled to the regular rim R, the passenger car steel radial tire 1 includes a pair of bead portions 3 having a bead core 2 and a sidewall portion 4 extending from each bead portion 3 upward in the tire radial direction. And a tread portion 5 extending between the upper ends of the side wall portions 4, and a toroidal cavity H for filling the internal pressure air is formed between the sidewalls 4 and the regular rim R.

A steel radial tire 1 for a passenger car is
A carcass 6 extending between the bead portions 3, a belt layer 7 disposed radially above the carcass 6 and below the tread portion 5, and a tire cavity located inside the carcass 6 and located inside the carcass 6. And an inner liner rubber 10 extending continuously toward H.

The carcass 6 extends from the tread portion 5 through the sidewall portion 4 to the bead core 2 to form a toroidal body portion 6A surrounding the tire cavity H.
And a turn portion 6B connected to the main body 6A and turned around the bead core 2 from inside the tire to outside.
The folded portion 6B extends to the vicinity of the maximum width position K of the tire to increase the lateral rigidity of the tire. The carcass 6 has a carcass cord 75 to 9 with respect to the tire equator C.
One or more carcass plies arranged at an angle of 0 degrees, in this example, one carcass ply are formed. In the carcass ply, the array of carcass cords is covered with a diene synthetic rubber such as styrene-butadiene rubber (SBR) or butadiene (BR) and a natural rubber (NR) or a ply rubber obtained by mixing these. As a carcass cord,
Organic fiber cords such as polyester, nylon, rayon and aromatic polyamide and metal fiber cords such as steel can be used, and the cord material and the number of plies are set according to the required tire performance and the like.

The carcass main body 6A and the folded back 6
B, a bead apex 8 made of hard rubber having a triangular cross section and rising upward from the upper end 2 e of the bead core 2 in the tire radial direction in the tire radial direction is disposed. The bead apex 8 has an upper end height H1 from the bead base line L that is larger than the rim flange height H2. In this example, the rim flange height H2 is 2.0 to 3.0.
By setting the width to about twice, the reinforcement extends from the bead core 3 to the sidewall portion 4 and the bead rigidity is increased, and the upper end 8e of the bead apex 8 terminates radially below the tire maximum width position K.

The belt layer 7 is formed of at least two belt plies in which a high-strength belt cord made of steel is arranged at an angle of 10 to 30 degrees with respect to the tire equator C. In this example, the belt layer 7 is composed of upper and lower two belt plies 7a and 7b, each cord intersects between the plies, and the belt effective width BW is changed to the tread contact width TW.
By making it larger than 0.8 times, the tread portion 5 is reinforced over substantially the entire width with a hammer effect. Here, the effective belt width BW is the maximum width in the tire axial direction of the overlapping portion where at least two belt plies overlap, and in this example, the upper belt ply 7a is narrower than the lower belt ply 7b. By the upper belt ply 7
The ply width of a corresponds to the effective belt width BW. The outer end of the overlapping portion in the tire axial direction is the outer end 7 of the belt layer 7.
e.

The inner liner rubber 10 is a thin rubber layer adjacent to the inner surface of the carcass body 6A facing the tire cavity H, and includes a natural rubber layer 11 mainly composed of natural rubber (NR); A butyl rubber layer 12 containing butyl rubber (IIR) as a main component.

Here, the natural rubber layer 11 is made of a rubber composition in which the content of the natural rubber (NR) in the rubber component is maximized, and exhibits high adhesiveness between the ply rubber and the carcass cord. The natural rubber layer 11 preferably contains the natural rubber (NR) in an amount of 50 parts by weight or more, more preferably 60 parts by weight or more, based on 100 parts by weight of rubber, from the viewpoint of the adhesiveness. Other rubber components contained in the natural rubber layer 11 include, for example, styrene-butadiene rubber (SB).
It is preferable to use a diene-based synthetic rubber such as R) and butadiene rubber (BR). In this example, styrene-butadiene rubber (SBR) is used to suppress thermal destruction of the rubber due to heat generated by the tire. Note that butyl rubber (IIR) can be contained as another rubber component.

The natural rubber layer 11 is located at a position Y2 near the upper end 8e of the bead apex 8 from the tire equatorial plane CO.
Up to a body portion 6A of the carcass 6 having a substantially constant thickness t1.
Adjacent to the inner surface. The thickness t1 is 0.3 to 0.5 mm
When the diameter is smaller than 0.3 mm, it is difficult to apply in the manufacturing process. On the other hand, when the diameter is larger than 0.5 mm, excessive quality results and the tire weight and rolling resistance are unnecessarily increased.

The vicinity position Y2 is defined as 1 to the normal line N2 of the carcass 6 passing through the upper end 8e of the bead apex.
0 mm or less, and the natural rubber layer 11
The lower end preferably terminates at the position of the normal line N2 or at a position radially below the normal line N2.

The butyl rubber layer 12 is made of a rubber composition having the maximum content of butyl rubber (IIR) in the rubber component, exhibits high air permeation resistance, and prevents air leak. The butyl rubber layer 12 preferably contains the butyl rubber (IIR) in an amount of 50 parts by weight or more, more preferably 60 parts by weight or more based on 100 parts by weight of rubber, from the viewpoint of air leak resistance. As the other rubber component contained in the butyl rubber layer 12, in addition to the diene-based synthetic rubber, natural rubber (NR) can be used. In particular, in this example, natural rubber ( NR).

The butyl rubber layer 12 is formed of the natural rubber layer 1.
1 and a position Y3 near the outer end 7e of the belt layer and a position Y3 near the upper end 2e of the bead core.
And has a substantially constant thickness t2. The thickness t2 of the butyl rubber layer 12 is the same as the thickness t1 of the natural rubber layer 11.
It is larger and more preferably in the range of 0.5 to 0.8 mm. When it is smaller than 0.5 mm, the side wall 4
And the air leak resistance at the bead portion 3 becomes insufficient,
Conversely, if the thickness exceeds 0.8 mm, excessive quality will result and the tire weight will increase unnecessarily.

The near position Y1 is a position at a distance of 10 mm or less from the normal line N1 of the carcass 6 passing through the outer end 7e of the belt layer. The upper end of the butyl rubber layer 12 is preferably Position of line N1 or normal line N1
Terminate further inward in the tire axial direction.

Similarly, the proximity position Y3 is a position having a distance of 10 mm or less from the normal line N3 of the carcass 6 passing through the upper end 2e of the bead core.

(Specific Example) A tire having the structure shown in FIG. 1 and having a tire size of 205 / 65R15 is prototyped based on the specifications shown in Table 1, and the air leak resistance, tire weight and rolling resistance of each test tire are measured. Each was compared. Table 2 shows the rubber composition of the natural rubber layer, the butyl rubber layer, and the ply rubber at that time.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

Since the present invention is constructed as described above, the required air leak resistance is maintained, the peeling damage of the inner liner rubber is suppressed, the weight of the tire is reduced, and the rolling resistance is reduced. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing the inner liner rubber developed and exaggerated in thickness.

[Explanation of symbols]

 2 Bead core 3 Bead section 4 Side wall section 5 Tread section 6 Carcass 7 Belt layer 8 Bead apex rubber 10 Inner liner rubber 11 Natural rubber layer 12 Butyl rubber layer H Tire lumen Y1, Y2, Y3 Nearby position

────────────────────────────────────────────────── (5) Continuation of the front page (56) References JP-A-5-169909 (JP, A) JP-A-61-60302 (JP, A) JP-A-5-50807 (JP, A) JP-A-59-60 190006 (JP, A) JP-A-4-90902 (JP, A) JP-A-4-191101 (JP, A) JP-A-63-222904 (JP, A) JP-A-62-67804 (JP, U) Japanese Patent Publication No. 62-8322 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60C 5/00 B60C 5/14

Claims (4)

(57) [Claims] 1. A carcass that is turned around a bead core of a bead portion from a tread portion to a sidewall portion and surrounds a tire bore, and a cord made of steel disposed radially above the carcass and below a tread portion. The used belt layer, a bead apex rubber rising radially upward from the bead core, and an inner liner rubber located inside the carcass and continuously disposed facing the tire cavity. The inner liner rubber extends from the equatorial plane of the tire to a position near the upper end of the bead apex and has a natural rubber (NR) content of the rubber component which is the maximum, and the natural rubber layer And extends from a position near the outer end of the belt layer to a position near the upper end of the bead core, and further includes a rubber component. Passenger car steel radial tire characterized by a content formed from the maximum and butyl rubber layer Chi butyl rubber (IIR). 2. The steel radial tire for a passenger car according to claim 1, wherein the thickness of the natural rubber layer is smaller than the thickness of the butyl rubber layer. 3. The natural rubber layer has a thickness of 0.3 to 0.3.
0.5mm, and the thickness of the butyl rubber layer is 0.5-0.8mm
3. A steel radial tire for a passenger car according to claim 2, wherein: 4. The passenger car according to claim 1, wherein the natural rubber layer contains at least 50 parts by weight of natural rubber among rubber components, and the butyl rubber layer contains at least 50 parts by weight of butyl rubber among rubber components. Steel radial tire.