JP3189127B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having excellent wet grip performance and abrasion resistance and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the global warming phenomenon has become a problem, and there has been an increasing movement to regulate the amount of carbon dioxide emitted.
For this reason, reducing the consumption of fossil fuels has become a technical issue, and there is a strong demand for vehicles that have improved fuel efficiency by reducing weight. It is effective to reduce the unsprung weight of the vehicle to reduce the weight of the vehicle, and the weight reduction of the pneumatic tire has been regarded as important. However, the volume reduction of each part of the pneumatic tire has reached its limit due to the balance with tire performance, and drastic weight reduction cannot be achieved by extension of the conventional technology.

If the volume of the cap tread portion can be reduced among the parts of the pneumatic tire, the weight of the pneumatic tire can be reduced. However, when the volume is reduced, the groove depth becomes shallower as the tread portion becomes thinner, so that the wear life of the cap tread portion is shortened. Conventionally, in a tread portion of a pneumatic radial tire or the like, carbon black, oil, an antioxidant, a vulcanizing additive, and the like are usually compounded in a polymer (rubber composition). The wear resistance of such a pneumatic tire is better as the glass transition point of the tread rubber is lower (Rubber Chem. & Tech., Vol. 44, 1971).
Yearly publication, p. 996). On the other hand, the wet grip performance of the pneumatic tire is better as the loss coefficient tan δ of the tread rubber at −10 to 0 ° C. is higher. Therefore, when the wear resistance and wet grip performance of the tread are compatible, the first rubber composition such as butadiene rubber (BR) or styrene butadiene rubber (SBR) having a glass transition point in a low temperature region, and a glass transition point It is mixed with a second rubber composition such as styrene-butadiene rubber having a peak of -10 to 0 ° C. at a temperature of −30 ° C. or more and a loss coefficient tan δ of about -10 ° C. or higher. However, the cap tread portion is a portion that is actually in contact with the road surface, and must have various performances. Rolling resistance, wet grip performance, and the like are reduced if improvement in wear resistance is pursued. For example, when the mixing amount of carbon black is increased or the particle size of carbon black is reduced in order to improve the wear resistance, the rolling resistance increases. On the other hand, when a rubber composition having a low glass transition point is used to reduce the rolling resistance, the wet grip performance is reduced. In such material development, only the balance of the performance is selected, and it is difficult to simultaneously improve the wear resistance, the wet grip performance, and the rolling resistance.

In such a situation, for example, Japanese Patent Application Laid-Open No. 63-301243 attempts to achieve both abrasion resistance and wet grip performance by devising carbon black itself. Japanese Patent Application Laid-Open No. 57-100146 attempts to achieve both of these properties by devising a polymer.

[0005]

However, in the above-mentioned conventional pneumatic tires, the effect of achieving both abrasion resistance and wet grip performance is insufficient. There is a problem that the weight cannot be reduced. An object of the present invention is to provide a pneumatic tire capable of improving wear resistance and reducing weight without deteriorating wet grip performance, and a method of manufacturing the same.

[0006]

The pneumatic tire according to the present invention comprises a first rubber composition having a glass transition point in a temperature range of -60 ° C or less and a glass having a glass transition point in a temperature range of -30 ° C or more. The rubber composition comprises a mixed rubber composition with a second rubber composition having a transition point, wherein 70% by weight or more of the total amount of carbon black is compounded in the first rubber composition. is there.

Further, according to the method of manufacturing a pneumatic tire according to the present invention, the first rubber composition having a glass transition point in a temperature range of -60 ° C. or less is added to the first rubber composition having a total content of carbon black of 70%.
% By weight of a green rubber having a tread portion composed of a mixed rubber composition obtained by mixing the remaining carbon black with a second rubber composition having a glass transition point in a temperature range of −30 ° C. or more in advance. A tire is manufactured, and the green tire is vulcanized and molded using a mold.

In the present invention, a rubber composition comprising a first rubber composition having a low glass transition point and excellent abrasion resistance and a second rubber composition having a high glass transition point and excellent wet grip performance are provided. When the tread portion is formed, by increasing the blending amount of carbon black in the first rubber composition, the wear resistance can be improved without lowering the wet grip performance. As a result, the volume of the tread portion can be reduced, so that the weight of the pneumatic tire can be reduced. In this case, if the compounding amount of carbon black in the first rubber composition is less than 70% by weight of the total compounding amount, it is impossible to achieve both abrasion resistance and wet grip performance. For this reason, the carbon black to be blended in the first rubber composition is 70% by weight or more of the total blended amount.

When the above-mentioned pneumatic tire is manufactured, the first rubber composition having excellent wet grip performance is mixed with the first rubber composition having excellent wear resistance. 7 of the total amount of carbon black in the composition
0% by weight or more is blended. Then, except that the mixed rubber composition blended with carbon black is used as a material constituting the tread portion as described above, the tire is used as a material for a tire such as another belt layer, a carcass layer and a sidewall in accordance with a conventional method. To produce a green tire, and vulcanization molding using a mold. Thereby, both wet grip performance and wear resistance performance can be achieved, and a pneumatic tire that can be reduced in weight can be easily manufactured.

In the present invention, as the rubber component of the first rubber composition, BR or low styrene content SBR can be used, and as the rubber component of the second rubber composition, high styrene content SBR or the like can be used. Can be used. Further, these first and second rubber compositions include, in addition to carbon black, zinc white (zinc oxide), stearic acid, an antioxidant, a wax, an aromatic oil, sulfur And a rubber chemical such as a vulcanization accelerator can be appropriately compounded and may be used as a wet master batch. In the present invention, the glass transition point is defined as ASTM D3417-75.
Means the value measured according to the method specified in

[0011]

EXAMPLES As a polymer A (first rubber composition), BR having a glass transition temperature of -100.degree.
pol 1441 ″) and SB having a glass transition temperature of −20.7 ° C. as polymer B (second rubber composition)
R (“Nipol 9529” manufactured by Zeon Corporation) was used. Then, after changing the compounding ratio of the polymers A and B and the compounding ratio of the HAF carbon black (CB) to the polymers A and B as shown in Table 1 below, after mixing a predetermined carbon black with the polymer A, The remaining carbon black, polymer B, and other ingredients were mixed to make formulations 1-6. At this time, as other compounding agents, 3
0.0 parts by weight of aromatic oil, 2.5 parts by weight of zinc oxide, 1.7 parts by weight of stearic acid, 2.0 parts by weight of sulfur, 1.7 parts by weight of antioxidant and 1.5 parts by weight Parts of the vulcanization accelerator were used.

Incidentally, N- (1,3-dimethylbutyl) -N'-phenyl-P-phenylenediamine is used as an anti-aging agent, and N-cyclohexyl-benzothiazyl sulfenamide is used as a vulcanization accelerator. It was used. Abrasion Test After vulcanizing each of Formulations 1 to 6 at 148 ° C. for 40 minutes, the abrasion loss was measured by a Goodrich-type pico abrasion tester. The reciprocal of this measured value was determined, and Formulation 1 was used as the reference value (10
The results are shown in Table 1 together with an index of 0). That is, the larger the index value, the better the wear resistance performance.

Wet skid resistance value After vulcanizing each of Formulations 1 to 6 at 148 ° C. for 40 minutes, an approximate pavement surface (safety walk manufactured by 3M) wetted with distilled water was used at 25 ° C. The wet skid resistance was measured with a British portable skid tester in the atmosphere described above. The measured values are shown in Table 1 together with an index using Formulation 1 as a reference value (100). That is, the larger the index value, the better the wet grip performance. As is clear from Table 1, Formulations 2, 4, and 6 included in the specified range of the present invention have wet grip performance and abrasion resistance performance with respect to Formulations 1, 3, and 5 formulated according to the prior art. Both were excellent.

[0014]

As described above, the pneumatic tire according to the present invention is a mixed rubber composition of the first rubber composition having excellent wear resistance and the second rubber composition having excellent wet grip performance. The first rubber composition contains 70% by weight or more of the total amount of carbon black, so that the wear resistance can be improved without reducing wet grip performance. As a result, the weight of the pneumatic tire can be reduced. In the method for manufacturing a pneumatic tire according to the present invention, 70% by weight or more of the total amount of carbon black is preliminarily compounded with the first rubber composition when the first and second rubber compositions are mixed. Therefore, the above-described pneumatic tire can be easily manufactured.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI C08K 3/04 C08K 3/04 // C08L 21:00 (58) Field surveyed (Int.Cl. ⁷ , DB name) C08L 21/00 B29D 30/06 B60C 1/00 C08J 3/20 C08J 3/24 C08K 3/04

Claims (2)

(57) [Claims] 1. A mixture of a first rubber composition having a glass transition point in a temperature range of −60 ° C. or lower and a second rubber composition having a glass transition point in a temperature range of −30 ° C. or higher. A pneumatic tire comprising a rubber composition, wherein 70% by weight or more of the total amount of carbon black is blended in the first rubber composition. 2. A first rubber composition having a glass transition point in a temperature range of -60.degree. C. or lower is preliminarily compounded with 70% by weight or more of the total amount of carbon black, which is then -30.degree.
A green tire having a tread portion made of a mixed rubber composition obtained by mixing the second rubber composition having a glass transition point in the above temperature range with the remaining carbon black is produced, and the green tire is molded using a mold. A method for manufacturing a pneumatic tire to be sulfur molded.