JPH09164810A - Heavy duty tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heavy duty tire with superior low heat generation without damaging tear characteristics. SOLUTION: This is a heavy duty tire which has a carcass and a breaker layer which is disposed at the outside in tire radial direction. A tread part 2 is constituted of a tread rubber 9 on a tread crown side and a wing rubber 10 on tread shoulder side. The wing rubber 10 extends to a buttless part 8 beyond a tread contact end E and contacts with a side wall rubber 11 under such a condition as the tire is combined with a standard rim and given normal load under the standard internal pressure. The wing rubber 10, whose width G in the axial direction of the tire is 15-25% of a tire cross-section width W, is constituted of rubber composition mixed with 0.5-5 pts.wt. of rubber modifier which contains 30-40% of N,N'-bis (2-methyl-2-nitropropyl)-1,6-hexadiamine in 100 pts.wt. of rubber component in which a weight ratio (NR/SBR) of natural rubber(NR) and styrene butadiene rubber(SBR) is in a range of 100/0-50/50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire for high load, which is excellent in low heat buildup without deteriorating tear characteristics.

[0002]

2. Description of the Related Art Heavy-duty tires for construction vehicles, heavy industrial machinery, aircraft, etc. are used with the remaining tires even if one of the wheels has a flat tire from the viewpoint of safety. Durability capable of carrying a load is required.

Therefore, a high-load tire is normally capable of transmitting braking force and driving force to and from a road surface even under a load condition of 1.5 to 2.0 times the normal load, and in the case of aircraft. It must also allow takeoffs and landings.

However, under a high load equivalent to several times the normal load, a large stress is generated in the tread portion, so that the tread portion is likely to generate heat and foaming may occur in the tread rubber. Such rubber foam is
May damage the tread. Further, such a problem becomes remarkable especially in a bias tire in which the rubber thickness of the tread portion is large.

Conventionally, in order to solve such a problem,
As the tread rubber, a low exothermic rubber having a small loss tangent (tan δ) is used.

[0006]

However, a rubber having a low loss tangent (tan δ) and a low exothermic property generally has a poor tearing performance. Therefore, when such a low heat-generating rubber is used in the tread portion, there is a problem that tear damage often occurs in a region where repeated deformation is severe, that is, a region from the axially outer side portion of the tread portion to the buttress portion. is there.

The present invention prevents tear damage in the vicinity of the buttress portion and, even when a high load is applied,
The purpose of the present invention is to provide a heavy-duty tire that suppresses heat generation and has improved durability.

[0008]

[Means for Solving the Problems] Claim 1 of the present invention
The invention described has a plurality of carcass plies that fold back around the bead core of the bead part from the tread part through the sidewall part, and a carcass in which the carcass plies are superposed in a direction in which the cords cross each other, and A tire for high load having a carcass tire radial direction outer side and a breaker layer arranged on the inner side of a tread portion, wherein the tread portion comprises a tread rubber on a tread crown side and a wing rubber on a tread shoulder side, In addition, the wing rubber extends to the buttress portion beyond the outermost tread grounding end in the axial direction of the tire where the tread contacts the ground when the tire is assembled on a standard rim and a regular load is applied under standard internal pressure. Existing wing rubber, and the width of the wing rubber in the tire axial direction is 15-25% of the section width, and natural rubber (NR) and styrene-butadiene (SBR)
And the weight ratio (NR / SBR) is 100/0 to 50/50
0.5 parts of the rubber modifier containing 30 to 40% of N, N'-bis (2-methyl-2-nitropropyl) -1,6-hexadiamine in 100 parts by weight of the rubber component.
It is a tire for high loads characterized by comprising a rubber composition mixed in an amount of up to 5 parts by weight.

According to the second aspect of the invention, the rubber modifier comprises 70 to 60% of calcined clay and 30 to 40% of N, N'-bis (2-methyl-2-nitropropyl). −
It is composed of 1,6-hexadiamine.

According to a third aspect of the present invention, in the carcass, the cords are arranged at an angle of 30 ° to 60 ° with respect to the tire equator.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. The high-load tire of the present invention is shown in FIG.
As shown in FIG. 2, a carcass 6 composed of a plurality of carcass plies 6A ... Folding back around the bead core 5 of the bead part 4 from the tread part 2 through the sidewall part 3, and the carcass 6 on the outside in the tire radial direction and on the inside of the tread part. And a breaker layer 7 arranged in the same manner. In this example, an aircraft tire used at high speed is illustrated.

In the present embodiment, the bead core 5 is exemplified as having the first, second and third bead cores 5A to 5C arranged from the inner side to the outer side in the tire axial direction. It may be configured with.

The carcass plies 6A, 6B ... consist of a plurality of carcass cords arranged at an angle of 30 to 60 ° with respect to the tire equator C, for example, about 4 to 14, and the carcass cords cross each other. A bias structure carcass is formed by superimposing it on.

Generally, a bias tire is inferior in rigidity to a tread portion as compared with a radial tire, so that it is difficult to reduce the thickness of a rubber portion and inferior in heat resistance. Therefore, the present invention can exert a more remarkable effect by being applied to the bias structure, but does not exclude the radial tire.

The carcass plies 6A ... May be piled up so that the direction of the cords may be different not only for each sheet but also for a plurality of sheets. Further, the carcass ply may include a ply that terminates from the tread portion 2 through the sidewall portion 3 inside the bead core 5 of the bead portion 4 in the tire radial direction to appropriately reinforce the tire. As the carcass cord,
For example, organic fiber cords such as nylon, rayon or polyester are preferable.

A breaker layer 7 capable of protecting the tread portion of the carcass is provided outside the carcass 6 in the tire radial direction and inside the tread portion 2.

The breaker layer 7 has cords 3 to 4 in which the cords are inclined in the same angle range as the carcass ply.
One breaker ply, four breaker plies in this example. The cords are stacked in different directions so as to intersect each other. The breaker ply cord may be made of an organic fiber cord such as nylon, rayon or polyester.

The breaker layer 7 has a width B in the tire axial direction.
W is 70 to 80% of the tire cross-section width W, and is terminated at a position beyond the ground contact end E of the tread to the outside in the tire axial direction. The ground contact end E of the tread means the position of the outermost end in the tire axial direction where the tread portion 2 contacts the ground when the tire is assembled on a standard rim and a regular load is applied under standard internal pressure.

Next, the tread portion 2 is composed of a tread rubber 9 on the tread crown side and a wing rubber 10 on the tread shoulder side.

As shown in the enlarged view of FIG. 2, the wing rubber 10 extends to the buttress portion 8 beyond the tread ground contact end E outward in the tire axial direction, and the sidewall portion 3 is provided.
Is provided so as to be in contact with the sidewall rubber 11 that covers the outer surface of the.

Therefore, the wing rubber 10 extends inside and outside the ground contact end E in the tire axial direction, and can cover all the both ends of the breaker ply forming the breaker layer 7. Therefore, the wing rubber 10 is preferable in that it can suppress heat generation at both ends of the breaker layer and prevent peeling of the ply.

When the wing rubber 10 is provided only on the outer side in the tire axial direction from the ground contact end E, it is not possible to suppress the significant heat generation of the tread shoulder portion which is always in contact with the road surface at the time of high load, and the durability is improved. It is not possible.

The wing rubber 10 is composed of the breaker layer 7
Also, the thing provided so as to form the tire outer surface of the buttress portion from the outer surface of the carcass 6 is illustrated. It is preferable to provide such a thickness as compared with the case where it is provided only on the surface of the buttress portion 8 in that the tear resistance and the heat resistance can be maintained for a long time even if abrasion occurs.

The wing rubber 10 is provided so as to be in contact with the tread rubber 9 by a dividing line extending in a normal line from the outer surface of the breaker layer 7. Generally, when the load is about twice as high as the normal load, the outer surface contour of the tire buttress portion 8 is as shown by the one-dot chain line V in FIG.

At this time, the wing rubber 10 works to compress the tread rubber 9. However, in this example, since the direction in which the wing rubber 10 compresses the tread rubber 9 and the rubber boundary surface are substantially perpendicular to each other, slippage between both rubbers is minimized, and the wing rubber 10 is prevented from peeling. You can

Further, an example is shown in which the outer end of the wing rubber 10 in the axial direction of the tire is arranged along the carcass 6 and is formed in a tapered shape so as to be covered with the sidewall rubber 11.

Next, the wing rubber 10 preferably has a width G in the tire axial direction of 15 to 25% of the tire sectional width W. If the width G is less than 15% of the tire cross-section width W, the vicinity of the buttress portion 8 cannot be sufficiently covered, and the tear resistance and the durability under high load cannot be improved. On the other hand, when the width G exceeds 25% of the tire cross-sectional width W, the wing rubber 10 also covers the tread crown portion, which reduces the grip force during normal running and impairs the steering stability performance.

As shown in FIG. 2, the wing rubber 1
When the width G of 0 is divided on the line extending from the ground contact end E to the outer side in the tire radial direction, the ratio of the inner width Gi to the outer width Go is, for example, 20/80 to 80/20, preferably 2
0/80 to 60/40, more preferably 25/75 to 5
It is desirable to set it to 0/50. In addition, when this condition is satisfied and a grounding end separates the wing rubber when a load twice the normal load acts, the ratio is 70/30 to 8
It is desired to be 0/20, preferably 75/25.

Further, the wing rubber 10 is based on a rubber component having a weight ratio (NR / SBR) of natural rubber (NR) to styrene-butadiene rubber (SBR) in the range of 100/0 to 50/50. It is necessary.

FIG. 4 shows the results of examining the heat resistance and the tear resistance (the test method is described later) by changing the weight ratio of the natural rubber and the styrene / butadiene rubber (note that the test method is described later).
Corresponds to Examples 1, 2, 3, 5, and 6 in Table 1 described later, and “5” surrounded by a square corresponds to Comparative Example 5). As is clear from this result, when the weight ratio of styrene / butadiene rubber exceeds 50 parts by weight, both heat resistance and tear resistance deteriorate.

Preferably, the weight ratio (NR / SBR) is
It is desirable to set it to 70/30 to 80/20. As described above, by adding an appropriate amount of styrene-butadiene rubber to natural rubber, it has the effect of increasing the foaming temperature, and foaming is less likely to occur even when heat is generated. From the standpoint of rubber physical properties, it is preferable to employ solution polymerization as the styrene-butadiene rubber rather than emulsion polymerization.

The wing rubber is a component for suppressing heat generation of rubber in 100 parts by weight of the rubber component,
N'-bis (2-methyl-2-nitropropyl) -1,
It is important to compound 0.5 to 5 parts by weight of a rubber modifier containing 30 to 40% of 6-hexadiamine.

FIG. 3 shows the relationship between the compounding amount of the rubber modifier with respect to 100 parts by weight of natural rubber and the heat resistance and tear resistance. As is clear from the figure, the rubber modifier
If it is less than 0.5 part by weight, the effect of improving the heat resistance cannot be sufficiently exerted. On the contrary, when the content is more than 5.0 parts by weight, the tear resistance can be improved but the heat resistance is deteriorated.

It is considered that this rubber modifier, when used in an appropriate amount, lowers the tan δ of the rubber, that is, improves the heat resistance and also improves the tear resistance.

Therefore, as is apparent from the figure, the rubber modifier is preferably 1.0 to 4.5 parts by weight, more preferably 1.5 to 4.0 parts by weight, still more preferably 1.5 to 4.0 parts by weight.
3.0 parts by weight is preferable.

As the rubber modifier, specifically, 66.6% of calcined clay and 33.4% of N, N 'are used.
-Bis (2-methyl-2-nitropropyl) -1,6-
The product name "Sumifine 1162" manufactured by Sumitomo Chemical, which is pre-blended with hexadiamine, is used.

In addition to the rubber modifier, the rubber composition forming the wing rubber 10 contains, for example, carbon black, an antioxidant, a vulcanization accelerator, a retarder and the like.

For carbon black, HAF having a nitrogen adsorption specific surface area of 70 m ² / g or more as determined by the BET method,
ISAF grade may be used, but it is more preferable to use ISAF having a nitrogen adsorption specific surface area of 100 m ² / g or more from the viewpoint of improving the tear resistance. Specifically, Show Black N330 (HA manufactured by Showa Cabot Co., Ltd.)
F), Show Black N220 (ISAF), and the like, which are 40 to 6 in 100 parts by weight of the rubber component.
0 parts by weight, preferably about 40 to 50 parts by weight is blended.

As the antiaging agent, N-phenyl-
N '-(1,3 dimethyl-butyl) -P-phenylenediamine is preferable, and specifically, about 0.5 to 5 parts by weight of Nocrac 6C manufactured by Ouchi Shinko Kagaku Co., Ltd. can be added.

The vulcanization accelerator was N-tert-butyl-2-benzothiazolylusulfenamide (Sanshinra NS manufactured by Sanshin Chemical Co., Ltd.), and the retarder was Sunguard PVI (manufactured by Nippon Monsanto Co., Ltd.). ) Or the like can be used.

[0041]

EXAMPLE A tire having a tire size of 49 × 19.0-20 and a high-load tire for aircraft having a specification shown in FIG. In addition, as the wing rubber, ones using the compounding examples of the present invention are used in Examples 1 to
The other formulations (Comparative Examples 1 to 8) were also prototyped. The shape of the wing rubber was the same. For the tread rubber and the sidewall rubber, the compounds shown in the following Table 1 different from the wing rubber were used.

[0042]

[Table 1]

The test was conducted in the following manner. A) Heat-resistant heat-resistant wing rubber was cut into a strip-shaped sample piece having a width of 30 mm, a length of 1.5 mm, and a loss coefficient (tan δ) of the strip-shaped sample piece was measured. The lower the index, the lower the heat generation and the better. The measurement conditions were 70 ° C., frequency 10 Hz, and dynamic strain rate 2% using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho.

B) Tear resistance The wing rubber was subjected to a tear test in accordance with JIS K6301, and the index was expressed as an index with Comparative Example 1 being 100. The higher the index, the better.

C) High load running test A takeoff test based on the United States Civil Aviation Bureau standard TSO-C62c was performed 100 times under a 150% normal (standard) load. The evaluation is shown by OK when completed and NG when destroyed.
In the case of NG, the tire was disassembled and the condition of the wing rubber was observed. Table 2 shows parts by weight of the composition of the wing rubber and the test results.

[0046]

[Table 2]

As a result of the test, for example, that of the first embodiment,
It can be confirmed that the heat resistance is improved while maintaining the tear resistance of Comparative Example 1.

Incidentally, in Example 4 in which HAF was used as the carbon black, the tear resistance was lower than that in the same example (Example 3) except that ISAF was used but the reinforcing property was poor.
Further, Comparative Examples 6 to 8 containing 6 parts by weight of a rubber modifier.
Has poor heat resistance. Further, in Comparative Examples 1, 3, and 4 in which the rubber modifier was not mixed, foaming was found in the wing rubber. In Comparative Example 2, tear damage occurred before foaming.

[0049]

As described above, the pneumatic tire of the present invention has the following features.
Heat resistance can be improved without lowering tear resistance,
Even when a high load of about 1.5 times the normal load acts, it is possible to prevent the tread portion from being broken.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view showing a buttress portion.

FIG. 3 is a graph showing the relationship between the compounding amount of a rubber modifier with respect to 100 parts by weight of natural rubber, and heat resistance and tear resistance.

FIG. 4 is a graph showing the relationship between the weight ratio of natural rubber and styrene / butadiene rubber and heat resistance and tear resistance.

[Explanation of symbols]

 2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 6A carcass ply 7 breaker layer 8 buttress part 9 tread rubber 10 wing rubber W tire section width G wing rubber width

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 7/00 LBD C08L 7/00 LBD 9/06 KDL 9/06 KDL

Claims (3)

[Claims] 1. A carcass having a plurality of carcass plies which fold back around a bead core of a bead part from a tread part to a sidewall part, and further, wherein the carcass plies are superposed in a direction in which the cords cross each other. A tire for high load having a carcass tire radial direction outer side and a breaker layer arranged on the inner side of a tread portion, wherein the tread portion comprises a tread rubber on a tread crown side and a wing rubber on a tread shoulder side, In addition, the wing rubber extends to the buttress portion beyond the outermost tread grounding end in the axial direction of the tire where the tread contacts the ground when the tire is assembled on a standard rim and a regular load is applied under standard internal pressure. The wing rubber, and the width in the tire axial direction is 15 to 25% of the cross-section width, and the weight ratio of natural rubber (NR) and styrene-butadiene rubber (SBR) (NR / SB
Rubber component 1 in which R) is in the range of 100/0 to 50/50
30 parts by weight of N, N'-bis (2-methyl-2-nitropropyl) -1,6-hexadiamine in 100 parts by weight.
% Of a rubber modifier, which is a rubber composition containing 0.5 to 5 parts by weight of a rubber modifier. 2. The rubber modifier comprises 70-60% calcined clay and 30-40% N, N'-bis (2-methyl-).
The high-load tire according to claim 1, which comprises 2-nitropropyl) -1,6-hexadiamine. 3. The high-load tire according to claim 1, wherein the carcass has cords arranged at an angle of 30 ° to 60 ° with respect to the tire equator.