JP2001240707A - Rubber composition suitable for base rubber of bias tire for large-sized vehicle and bias tire for large-sized vehicle using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which has low heat build-up properties and fracture resistance compatibilized with each other. SOLUTION: This rubber composition gives a base rubber having a tensile stress at 100% elongation M100 (100% modulus) of 2.5-3.5 Mpa, satisfies the relation represented by the relation M100(Ca)<M100 (Ba)<M100 (Br), wherein M100(Ca), M100(Ba), and M100(Br) are M100 of a cap rubber, the base rubber, and a breaker rubber, respectively, and has a tanδ at a dynamic strain of 2% at 25 deg.C of 0.100 or lower and an elongation at break EB after aging of 400% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition suitable for a base rubber of a bias tire for a large vehicle,
The present invention relates to a rubber composition having improved heat generation and crack resistance by increasing the elastic modulus, and a bias tire for a large vehicle in which the rubber composition is applied to a base layer.

[0002]

2. Description of the Related Art There is a demand for a base rubber for a bias tire for a large vehicle to have low heat build-up in order to suppress heat generated from a canvas thickness gauge peculiar to a bias tire and prevent various troubles. For this reason, it has been conventionally handled by reducing the amount of the filler.

[0003]

By the way, with the recent increase in size and speed of vehicles, further improvement in heat resistance and durability of bias tires is required. However, in the improvement by reducing the amount of filler, which is an extension of the conventional method, among the physical properties of rubber, particularly, the crack resistance is significantly reduced,
One of the important failures for bias tires is that a cut from the outside reaches the inside of the base rubber, from which cracks propagate in the rubber, eventually causing a tear failure in which the rubber loses its pattern. For this reason, it was not possible to sufficiently reduce heat generation. Therefore, an object of the present invention is to provide a rubber composition for a base rubber that can improve crack resistance while reducing heat generation.

[0004]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and, as a result, have noticed that the bias tire has a large tread rubber movement due to its structure. It has been found that higher elasticity suppresses distortion during rolling of the tire, and as a result, it is possible to improve the low heat build-up and crack resistance of the rubber. The present invention has been completed by making it possible to achieve both performances.

The structure of the present invention is as follows. sand
In other words, the tread rubber consists of the cap rubber and the base rubber.
Breaker adjacent to the base rubber opposite to the cap rubber side.
The base rubber of a bias tire for a large vehicle having rubber
The rubber composition applied to the
Stress M at 100% elongation₁₀₀(100% moji
Is 2.5 to 3.5 MPa, and the cap
Of rubber, base rubber and breaker rubber₁₀₀Is M
₁₀₀(Ca), M₁₀₀(Ba), M₁₀₀ (Br)
And M₁₀₀(Ca) <M₁₀₀(Ba) <M
₁₀₀(Br), and the dynamic strain 2
%, Tan δ at 25 ° C. is 0.100 or less;
Elongation at break E after aging_BIs more than 400%
Sign. The Tan δ is 0.08 or less,
EB after the conversion is 450% or more,₁₀₀(Ca)
Is less than 2.7 MPa, and the M₁₀₀(Br)
It is preferred that it is larger than 3.3 MPa. Also, for large vehicles
Preference bias tires are located radially outside.
Cap layer and the base
Tread part consisting of
Having a breaker disposed therein and constituting the base layer
Tensile stress M at 100% elongation of rubber composition₁₀₀Is 2.
5 to 3.5 MPa, dynamic strain 2%, measured at 25 ° C.
Is less than 0.100, and the elongation at break after aging.
And E_BIs 400% or more, and
The tensile stress at 100% elongation of the rubber composition is M₁₀₀(C
a) at the time of 100% elongation of the rubber composition constituting the base layer
The tensile stress of M₁₀₀(Ba), constituting a breaker layer
The tensile stress at 100% elongation of the rubber composition₁₀₀
(Br), M₁₀₀(Ca) <M₁₀₀(B
a) <M₁₀₀(Br).
You.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail. In the present invention, 10% of the base rubber to which the rubber composition of the present invention is applied.
Tensile stress M _{100 at 100} % elongation (100% modulus)
Is 2.5 to 3.5 MPa, and M ₁₀₀ of the cap rubber, base rubber, and breaker rubber is M
₁₀₀ (Ca), M ₁₀₀ (Ba), M ₁₀₀ (B
when the _{r), M 100 (Ca)} <M 10 0 (Ba)
<Satisfy the relation of _M 100 (Br), further, dynamic strain 2%, and a Tanδ at 25 ° C. is 0.100 or less, but the elongation at break _{E B} after aging defines that this is 400% or more This means that M ₁₀₀ (Ba) is 2.5MP
If less than a, the effect of reducing strain is small and the effect of lowering heat generation is not sufficient, and if it exceeds 3.5 MPa, although the effect of reducing strain can be obtained, the balance of the elastic modulus between adjacent members is poor, which is inconvenient. M ₁₀₀ (Ca) <M ₁₀₀ (Ba)
If the relationship of M ₁₀₀ (Br) is not satisfied, the above 3
The elastic modulus balance of the laminated rubber of the species is lost, BLC separation due to uneven distribution of strain occurs, and Tanδ is 0.100.
By weight, heat generation is too large, a disqualified as a base rubber which requires heat generation limit, the less than 400% E _B after aging, when the base rubber in the travel end is exposed, such as chipping occurred, This is because the appearance becomes poor. For example, by adjusting the compounding ratio of the vulcanization accelerator and sulfur,
The elastic modulus can be optimized.

The rubber component of the rubber composition of the present invention is preferably natural rubber (NR), butadiene rubber (BR), styrene butadiene rubber (SBR), and the grade of carbon black is preferably N330 or N339. , And may further contain silica. The amount of these components is preferably 34 to 40 parts by weight in total of carbon black and silica with respect to 100 parts by weight of the rubber component.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. A test bias tire (tire size: 1000) using a rubber composition having the composition shown in Table 1 as a base rubber
-20, rug pattern) by a conventional method. Cut out a sample from the base rubber of the created tire,
The measurement of ₁₀₀ is based on JIS K630 for the sample.
Performed in conformity with 1 (1995), the measurement of _{E B} is 100 ° C.
JIS for samples aged for 24 hours in a constant temperature oven
K6301 (1995). Tan δ
Was measured using a Toyo Seiki spectrometer on a sample cut from the base rubber, with a dynamic strain of 2% and 25%.
C. The measurement of the tire temperature was performed by performing a drum test and measuring the temperature of the thickest part of the tire after traveling for 6 hours at a speed of 57 km / h and a load of 2770 kg. The lag tear property was measured by conducting a field test using a dump truck and running until the tires were completely worn under the condition of paved road / unpaved road 90/10. Books: For example, 10 for 1
If the number is 0.1, the calculation was performed.

[0009]

[Table 1] * 1: Failure occurred during the drum test. * 2: Field test was stopped due to failure during the drum test. * 3: Field test was stopped because the temperature was higher than that of Comparative Example 1 during the drum test. * 4: At the end of running. When the base rubber was exposed, chipping occurred. Silica: Nipseal AQ (trademark: Nippon Silica Industry Co., Ltd.)
Vulcanization accelerator: Noxeller NS-F (trademark: manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Antiaging agent: Nocrack 6C (trademark: manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) Comparative Examples 1, 3, and 4 5 has a small ratio of vulcanization accelerator / sulfur among the conventional compounds, but in this case, the elastic modulus is low for the total amount of the vulcanization accelerator and sulfur. Therefore, as in the examples, by optimizing this ratio, the vulcanization efficiency can be improved and the elastic modulus can be increased.

[0010]

As described above, according to the present invention,
By increasing the elasticity of the rubber composition suitable for the base rubber of bias tires for large vehicles, distortion in the rubber during transfer is suppressed, and as a result, both low heat generation and fracture resistance (crack resistance) are achieved. Can be realized.

Claims (6)

[Claims] 1. A rubber composition applied to a base rubber of a large vehicle bias tire having a tread rubber comprising a cap rubber and a base rubber and having a breaker rubber adjacent to the base rubber on a side opposite to the cap rubber. The applied base rubber has a tensile stress M ₁₀₀ (10%) at 100% elongation.
0% modulus) is 2.5～3.5MPa, and the cap rubber, the base rubber, _{M 1} respectively _{M 100} of the breaker rubber _{00 (Ca), M 100 (} Ba), M
₁₀₀ (Br), M ₁₀₀ (Ca) <M
₁₀₀ (Ba) <M ₁₀₀ (Br), and the dynamic strain is 2% and the Tan δ at 25 ° C. is 0.1.
00 or less, a rubber composition elongation at break E _B after aging is equal to or is more than 400%. 2. The rubber composition according to claim 1, wherein said Tan δ is 0.08 or less. Wherein at break after the aging elongation _{E B} is 450%
The rubber composition according to claim 1 or 2, wherein: 4. The rubber composition according to claim 1, wherein the M ₁₀₀ (Ca) is less than 2.7 MP. 5. The method according to claim 1, wherein said M ₁₀₀ (Br) is 3.3 MPa.
The rubber composition according to any one of claims 1 to 4, wherein the rubber composition is larger. 6. A tread portion comprising a cap layer disposed on the tire radial outside and a base layer disposed on the tire radial inside, and a breaker disposed on the tire radial inside, tensile stress _{M 100} at 100% elongation of the rubber composition constituting the base layer is 2.5 to 3.5
MPa, dynamic strain 2%, Tan δ measured at 25 ° C.
There is 0.100 or less, elongation at break _{E B} is 4 after aging
And at 00% or more, 100% elongation at a tensile stress _{M 10 0 (Ca), M} 1 and at 100% elongation the tensile stress of the rubber composition constituting the base layer ₀₀ of the rubber composition constituting the cap layer (Ba), when the tensile stress at 100% elongation of the rubber composition constituting the breaker layer is M ₁₀₀ (Br), M ₁₀₀ (Ca) <M ₁₀₀ (Ba) <M _1
A pneumatic bias tire for a large vehicle, wherein the tire satisfies the relationship of ( ₀₀ ) (Br).