JP3444925B2 - Large pneumatic radial tire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large pneumatic radial tire having excellent durability.

[0002]

2. Description of the Related Art Conventionally, as a large pneumatic radial tire, for example, a reinforcing layer made of a corrugated cord is arranged between a carcass ply layer and a belt layer applied by the applicant of the present invention to increase the tire diameter growth and running growth. And improved tire durability (JP-A-2-234805, JP-A-4).
No. 328003) or an outermost layer belt ply having aramid fibers, a single wire and a single twist cord arranged to suppress the diameter growth and running growth of the tire and improve the durability of the tire (special feature). Japanese Laid-Open Patent Application No. 2-81707 and Japanese Patent Laid-Open No. 3-136905) are known.

However, the former JP-A-2-2348
In the case of Japanese Laid-Open Patent Publication No. 05, etc., there is a slight problem that the ply cord is likely to move and a failure such as BLC is likely to occur because the corrugated cord is directly on the carcass ply during traveling. In the case of the latter Japanese Patent Laid-Open No. 2-81707, cord fatigue becomes a problem when the filament diameter is increased so as to suppress diameter growth due to single twisting or single wire, and the filament diameter remains thin. Even if you try to drive in, the effect is not so great due to manufacturing constraints, and the reality is that diameter growth and running growth cannot be suppressed very much.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to prevent the occurrence of BLC of a tire during traveling, and to reduce the diameter when traveling due to flattening. Providing large pneumatic radial tires with excellent durability by preventing growth and running growth, and large pneumatic radial tires that meet the social needs of large pneumatic radial tires, that is, the requirements for weight reduction and cost reduction To provide tires.

[0005]

As a result of intensive studies to solve the above-mentioned conventional problems, the present inventors have found that one or two parallel belts in which a corrugated cord having a specific structure is embedded in the outer layer of the belt layer. By using a ply, a large pneumatic radial tire capable of achieving the above object was successfully obtained, and the present invention was completed.

That is, the pneumatic large radial tire of the present invention includes a carcass layer including at least one carcass ply in which a large number of cords substantially orthogonal to the tire equatorial plane are embedded, and a carcass layer radially outside the carcass layer. And a belt layer having parallel belt plies in which cords made of a large number of steel bent in a wavy or zigzag shape are embedded and arranged so as to be substantially parallel to the equatorial plane of the tire. In a large pneumatic radial tire, the parallel belt plies are arranged as one or two layers of parallel belt plies on the outer layer of a normal belt ply in the radial direction of the tire, and the cords embedded in each parallel belt ply are: It consists of a two-layer twist structure without spirals, the core and sheath filament diameters are almost the same, and The filament diameter is 0.15 to 0.
30 mmφ, the wave-like or zig-zag wavelength of the code is λ (mm), and the wave-like or zig-zag one-sided amplitude (mm) is a.
Then, the following equations (I) and (II) 2.0 × 10 ⁻² <2a / λ <7.0 × 10 ⁻² ………… (I) 30 <λ <38 ………… (II) And, when the number of cores is one, the core is shaped in a straight line, wavy, or spiral, and when there are two or more cores, the twisting directions of the core and the sheath are the same, and The ratio P _C / P _S between the pitch P _C and the sheath pitch P _S satisfies the following expression (III) 0.4 ≦ P _C / P _S ≦ 0.9 (III) . The above-mentioned large pneumatic radial tire in which a normal belt ply has two to four layers. The large pneumatic radial tire described above, in which a protect belt ply is arranged on the outer layer of the parallel belt ply. Two-layer twist structure is 3 + 9, 2+
The large pneumatic large radial tire described above, which is 6, 2 + 7 or 1 + 6. 0.6 to 0.9 cord gap
(Mm) The large pneumatic radial tire described above. The large pneumatic radial tire described above, wherein the tensile strength of the cord is less than 300 kgf / mm ² .

The contents of the present invention will be described below. An example of a large pneumatic radial tire according to the present invention will be described with reference to FIGS. 1 and 2. A large pneumatic radial tire A is at least one in which a large number of cords substantially orthogonal to the tire equatorial plane are embedded, In this example, a carcass layer 1 made of a single carcass ply, is arranged on the outer side in the radial direction of the carcass layer 1, is arranged so as to be substantially parallel to the equatorial plane of the tire, and is folded in a wavy or zigzag shape. A belt layer 2 having a parallel belt ply in which cords made of a large number of bent steels are embedded, and in the present example, the belt layer 2 is composed of one layer of the protective belt ply 3 in order from the outermost layer in the radial direction of the tire. Parallel belt ply 4,5
And two layers of belt plies 6 and 7.

The parallel belt plies are arranged as two layers of parallel belt plies 4 and 5 on the outer layer in the radial direction of the tire. The cords 8, 8 embedded in the parallel belt plies 4, 5 have a two-layer twist structure without a spiral, and the filament diameters of the core and the sheath are almost the same, and the filament diameter is 0.15. Is 0.30 mm, and as shown in FIG. 1 (b), when the wavy or zigzag wavelength of the code 8 is λ (mm) and the wavy or zigzag half amplitude is a (mm), The formulas (I) and (II) satisfy 2.0 × 10 ⁻² <2a / λ <7.0 × 10 ⁻² ··· (I) 30 <λ <38 ··· (II). In addition, when the number of cores is one, the cores are shaped in a linear shape, a wave shape, or a spiral shape. When there are two or more cores, the twisting directions of the core and the sheath are the same, and the pitch P of the cores is P. Ratio of _C to sheath pitch P _S P _C
/ P _S satisfies the following expression (III) 0.4 ≦ P _C / P _S ≦ 0.9 (III).

The two-layer belt plies 6 and 7 disposed under the parallel belt plies 4 and 5 are ordinary belt plies in which cords made of a large number of steel or organic fibers are embedded, and the shape of the cords is The structure is not particularly limited, and it is preferable that the belt ply has two to four layers. If the belt ply has five layers or more, the belt layer 2 as a whole becomes thick and the heat separation resistance decreases. Becomes Further, an outer layer of the parallel belt ply 4 is provided with a further layer of the protect belt ply 3. The protect belt ply 3 is arranged as required, and protects the parallel belt plies 4 and 5 to further improve the effect of the present invention.

In the present invention, the reason why the parallel belt plies 4 and 5 of the outer layer in the radial direction of the tire are one layer or two layers is that the diameter growth and running growth cannot be suppressed unless the parallel belt plies are provided. This is because if the number of layers is three or more, the belt layer 2 as a whole becomes thicker and the heat separation resistance is significantly reduced.

In the present invention, the parallel belt plies 4, 5
The cords 8, 8 buried in are composed of a two-layer twist structure having no spiral. The reason for using two-ply twist is that in the case of three-ply twist, kinks are likely to occur in the part of the different-direction twist when different directions enter, and when all the same-direction twists are made into a corrugated cord, three-dimensional This is because the cord is likely to be in a general state, the cord is twisted in the middle, the belt layer 2 itself becomes thick, and the thermal durability is significantly lowered. In the case of a single-layered twist, if the filament diameter is the same, the rigidity will be lower than in a double-layer twisted cord, and the diameter growth and running growth cannot be suppressed so much. However, since the fatigue resistance deteriorates, the flexibility in designing the cord is narrowed, and the cord strength of the single-twist cord is low, so that the cut resistance is also significantly reduced, which is not preferable. In addition, the increase in the number of inputs is
Due to tire manufacturing restrictions, it cannot be increased so much. Also,
The reason for making it non-spiral is that if there is a spiral, secondary bending becomes tight at that location, and kinks easily occur.

In the present invention, the two-layer twist structure has 3+
It is preferably 9, 2 + 6, 2 + 7 and 1 + 6.
In the two-layer twist structure, when N of 2 + N is 8 or more, the rubber penetration becomes poor, and when it is 5 or less, the sheath filament becomes liable to move and a biased portion is generated, which is not preferable because the rubber penetration becomes poor. Further, when the number of cores is three, it becomes difficult for rubber to enter the inside of the cores, and the cut separation resistance is not improved so much. Among them, the number of sheath filaments is 1
If the number is 0 or more, it becomes more difficult for rubber to enter, and the cut separation resistance is significantly reduced. On the other hand, if the number of filaments is 8 or less, the filaments are likely to move easily, and some areas are apt to be deformed, and the rubber penetration is further deteriorated, which is not preferable. Therefore, 3 + 9 is the most stable. Also,
When the number of cores is 1, only 6 sheaths are preferable, and when the number of sheaths is 5 or less, the cord strength decreases and
Cut resistance is also reduced, and if the filament diameter is made thicker to compensate for it, kinks are likely to occur and fluctuation strain increases,
Fatigue resistance decreases.

In the present invention, the filament diameters of the core and the sheath in the two-layer twist structure are substantially the same, and the filament diameter is 0.15 to 0.30 mm. If the filament diameter exceeds 0.30 mm, kink tends to occur when the required a / λ is set, and the variable strain also increases, so the fatigue resistance decreases, and if it is less than 0.15 mm, the cord strength decreases, Cut resistance is reduced, bending rigidity is reduced, and the effect of suppressing diameter growth is also reduced.

In the present invention, as shown in FIG. 1 (b), the wavelength of the wave 8 or zigzag of the code 8 is set to λ (m
m), and the wavy or zigzag half amplitude is a (mm), the code 8 has the following formulas (II) and (III) 2.0 × 10 ⁻² <2a / λ <7.0 × 10 ^-2 ……… (I) 30 <λ <38 ……… (II) is satisfied. When 2a / λ is 7.0 × 10 ^-2 or more, kink is likely to occur even when the above sample is used, and when 2a / λ is 2.0 × 10 ^-2 or less, the internal pressure and the diameter are decreased. The cord is fully grown during the growth, and the tire buckles and the tire does not have a normal shape, which is not preferable. When λ is set to 38 or more, a must be increased, and for that purpose, the gear engagement amount of the manufacturing apparatus must be increased, which easily causes scratches and deteriorates fatigue properties. Further, if λ is less than 30, a becomes too small to make a wave skillfully, and variations in the amplitude of the wave become very large, and buckling is likely to occur. Needless to say, when a kink occurs, filament breakage easily occurs.

In the present invention, the cord gap is 0.6-.
It is preferably 0.9 (mm). Code gap 0.
When it is less than 6 (mm), it is substantially restricted from the viewpoint of tire manufacturing, and when it exceeds 0.9 (mm), the number of scratches reaching the lower belt ply increases, and the cut burst rate increases.

In the present invention, when the number of cores is one, the cores are shaped in a straight line, wavy, or spiral, and when there are two or more cores, the twisting directions of the cores and the sheaths are substantially the same. And the ratio P _C / P _S of the core pitch P _C to the sheath pitch P _S satisfies the following equation 0.4 ≦ P _C / P _S ≦ 0.9 (III) is there. If the pitch ratio P _C / P _S exceeds 0.9, the sheath filament is likely to fall between the core filaments, and the core is likely to be kinked. Further, when the pitch ratio P _C / P _S is less than 0.4, the core and the sheath become closer to a point contact type, and a kink easily occurs in the sheath and the core.

In the present invention, the tensile strength (T.
S) is preferably less than 300 kgf / mm ² . With the same 2a / λ, tensile strength is 300kgf
If it exceeds / mm ² , the elastic modulus increases, the plasticity change, that is, the wave is less likely to be formed, and it is necessary to mold excessively, and the scratches become large and the fatigue property deteriorates.

[0018]

EXAMPLES Next, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these Examples. (Examples 1 and 2 and Comparative Examples 1 to 13) In Table 1 below, the number of belts, the cord structure, the pitch ratio of the cords (P _C / P _S ), the code amplitude a and the value of 2a / λ of the wavelength λ, λ Value, the cord clearance, and the examples and comparative examples of the respective trial tires, rubber penetration, tensile strength (TS) of cord, diameter growth and running growth, heat separation property, kink, cord break, burst property, cut The result of having measured the separation property is shown. Rubber penetration, cord gap, T.I. The methods for measuring S, diameter growth + running growth, heat separation property, kink, cord breakage, burst property, cut separation property and the like are as follows.

(1) The core was taken out from the rubber penetration belt and the ratio of the rubber adhering to the surface was visually judged and expressed in%. (2) Cord gap prototype (new) tire was analyzed and measured near the crown center. The average value of N = 10 was calculated. (3) Code tensile strength (TS) The code tensile strength (TS) was calculated by the following formula. T. S = code strength ÷ W × 7.86 code strength: A cord was taken from a new tire and measured with a tensile tester. W: Cord size, Weight per meter 7.86: Specific gravity of iron

[0020] (4) radial growth and traveling growth diameter growth, and the internal pressure ^{1kg / cm 2 ~7.25kg / cm 2} , to measure the change in the tire circumference of the crown center portion. The running growth was measured by measuring the change in tire circumference of the crown center portion after running the QC drum for 5000 km. The control of the control (Comparative Example 1) was 100, and the smaller the index, the better the diameter growth and running growth.

(5) Heat separation property Evaluation was made by the running distance of the QC drum. The control (Comparative Example 1) was set to 100, and the larger the index, the better. (6) Ten cords, 60 cm, were taken from a new kink tire, disassembled for each filament and visually measured. If there was a kink even in one place, it was evaluated as “present”.

(7) A cord-cut tire (size 11/70 R22.5) was put into practice for 150,000 k.
After running for m, tires 10 cm long from both ends of the belt
The cords were taken out one by one and visually checked for breakability. If there was filament breakage even at one place, it was evaluated as "present". (8) Bursting property The above tire was subjected to PE test and compared with a control. The control (Comparative Example 1) was set to 100, and the larger the index, the better. (9) Cut separation property The above-mentioned tire cut portion was checked at 10 positions, the separation length was measured, and the total value was evaluated in comparison with the control. The control (Comparative Example 1) was set to 100, and the larger the index, the better.

[0023]

[Table 1]

From the results shown in Table 1 above, the following was found.
Comparative Example 1 is a control tire (symmetrical example) having the current structure, and the index display of Examples 1 and 2 and Comparative Examples 2 to 13 shows the index of Comparative Example 1 as 100. In Example 1, the cord structure is 3 + 9 and the rubber penetration is insufficient, so the cut separation property is hardly improved. Example 2 is included in the preferable range of the present invention, is an example in which the rubber penetration is improved, and the cut separation property is also improved. In Comparative Example 2, since there is sp, a kink occurs at sp, a cord breakage occurs, and the cut burst resistance also deteriorates. In Comparative Example 3, the filament diameter is 0.3.
Since it is as thick as 2 mm, fluctuating strain becomes large, kinks occur, cord breakage also occurs, cut burst resistance decreases, and the belt layer becomes thick and heat separation property also decreases. In Comparative Example 4, since the filament diameter is as small as 0.12 mm, the diameter growth cannot be suppressed, and the heat separation property also deteriorates. In Comparative Example 5, since the (P _C / P _S ) ratio between the core and the sheath was as small as 0.30, kinks were likely to occur, cord breakage also occurred, and burst resistance was also reduced.

In Comparative Example 6, the core and the sheath (P _C / P _S )
Since the ratio is as large as 0.95, kinks are likely to occur, the burst resistance is lowered, and the rubber penetration is poor, so the cut separation property is not improved. In Comparative Example 7, since the cord gap is as wide as 1.0 mm, the number of cuts reaching the intersecting layer increases and the burst resistance decreases. In Comparative Example 8, the cord tensile strength (TS) is 34.
Since it is as large as 0 kgf / mm ² , scratches become large at the time of molding, cord breakage easily occurs, and burst resistance also decreases. In Comparative Example 9, since 2a / λ is as large as 0.082, the diameter growth cannot be suppressed so much, the heat separation property is deteriorated, and kink easily occurs, the cord breaks, and the burst resistance. Will also decrease. In Comparative Example 10, since λ is as large as 41, a is also large, scratches are large, cord breakage occurs, and burst resistance is also reduced. In Comparative Example 11, since λ is as small as 25, kinks are generated at the vertices, scratches are increased, cord breakage occurs, and burst resistance is reduced. In Comparative Example 12, since the single twist structure (1 + 5 × 0.25), the rigidity is low, the diameter growth cannot be suppressed so much, the heat separation property is deteriorated, and the burst property is also deteriorated.

[0026]

Industrial Applicability According to the large pneumatic radial tire of the present invention, BLC of the tire is prevented from occurring during running, and the diameter growth and running growth during running due to flattening are prevented, and the durability is improved. A large pneumatic radial tire is provided that is excellent in terms of weight and satisfies the requirements for weight reduction and cost reduction.

[Brief description of drawings]

FIG. 1 (a) is an end view showing an example of a large pneumatic radial tire of the present invention, and FIG. 1 (b) is a sectional view showing a parallel belt ply in which a cord is embedded.

FIG. 2 is an enlarged cross-sectional view showing a main part of a belt layer.

[Explanation of symbols]

Large pneumatic radial tires 1 carcass layer 2 belt layers 3 Protect belt ply 4 Parallel belt plies 5 Parallel belt plies 6 belt plies 7 Belt ply 8 codes Waveform or zigzag wavelength of λ code a code wavy or zigzag half amplitude

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-234805 (JP, A) JP-A-4-328003 (JP, A) JP-A-2-241802 (JP, A) JP-A-2- 141304 (JP, A) JP 5-44184 (JP, A) JP 2-154086 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 9/00 B60C 9 / 18 B60C 9/20

Claims (6)

(57) [Claims] 1. A carcass layer composed of at least one carcass ply in which a large number of cords which are substantially orthogonal to the tire equatorial plane are embedded, and a carcass layer arranged radially outside of the carcass layer and being substantially aligned with the equatorial plane of the tire. A large pneumatic radial tire provided with a belt layer having parallel belt plies in which cords made of a large number of steel bent in a wavy or zigzag shape are embedded while being arranged in parallel, wherein the parallel belt The plies are arranged as one or two layers of parallel belt plies on the outer layer of a normal belt ply in the radial direction of the tire, and the cord embedded in each parallel belt ply has a double-layer twist structure without a spiral. And the filament diameters of the core and the sheath are almost the same, and the filament diameters are 0.15 to 0.30 mmφ. A wavy or zigzag wave code λ a (mm), wavy or zigzag half amplitude (mm) when the a, the following formula (I) and ^{(II) 2.0 × 10 -2 <} 2a / λ <7.0 × 10 ^-2 (I) 30 <λ <38 (II) and when the number of cores is one, the cores are shaped into a straight line, a wavy form, or a spiral form. When the number of cores is two or more, the twisting directions of the core and the sheath are the same, and the ratio P _C / P _S of the pitch P _C of the core and the pitch P _S of the sheath is expressed by the following formula (III) 0: 4 ≦ P _C / P _S ≦ 0.9 (...) (III), which is a large pneumatic radial tire. 2. The large pneumatic radial tire according to claim 1, wherein the normal belt ply is composed of two to four layers. 3. The large pneumatic radial tire according to claim 1, wherein a protect belt ply is arranged on an outer layer of the parallel belt ply. 4. The two-layer twist structure is 3 + 9, 2 + 6, 2 + 7.
Alternatively, the pneumatic large large radial tire according to claim 1, which is 1 + 6. 5. The large pneumatic radial tire according to claim 1, wherein the cord gap is 0.6 to 0.9 (mm). 6. The tensile strength of the cord is 300 kgf / mm ²
The pneumatic large radial tire according to claim 1, which is less than 1.