KR100506840B1 - Back-up rubber layer compound improved anti-fatigue property - Google Patents

Abstract

The present invention relates to a backing rubber layer rubber composition, comprising 55 to 65 parts by weight of carbon black (N-330) and 2 to 4 parts by weight of aromatic oils based on 100 parts by weight of natural rubber.

As described above, by using N-330 and aromatic oil instead of carbon black N-351 in the backup rubber layer rubber composition without using a silica, a coupling agent, and a dispersant, modulus performance and fatigue resistance are greatly improved without any other performance deterioration. This also improves tire life.

Description

Back-up rubber layer compound improved anti-fatigue property

The present invention relates to a backing rubber layer rubber composition, and more particularly, a backing rubber layer having improved modulus performance and fatigue resistance by applying N-330 and aromatic oils instead of carbon black N-351 without using silica, a coupling agent, and a dispersant. It relates to a rubber composition.

The most realistic and rapid development with the development of modern civilization is the automobile culture. Recently, with the development of the automobile culture, the demands of consumers are rapidly changing with respect to tires, and one of the typical trends is a characteristic of allowing tires to be used for a long time in truck / bus cars. In particular, since tires for trucks / buses are relatively expensive, regeneration is essential, and it is important to improve fatigue resistance that can maintain physical properties for a long time in rubber compositions as well as structures forming tires.

The fatigue resistance of the tire can be largely divided into a carcass part and a bead part, and in the present invention, the fatigue resistance of the carcass part is complemented. In particular, the rubber composition of the carcass layer for tires may have a slight flow as time goes by, and in order to minimize the flow and minimize the flow of the carcass layer by using a backup rubber composition with improved fatigue resistance, The purpose is to improve the quality of finished tires.

In such truck / bus tires, steel cords and bead wires are designed as main structures, so it is essential to apply a rubber composition that can protect the carcass portion in which steel cords are mainly used from various stimuli including external moisture. In order to obtain a rubber composition having improved fatigue resistance, it is important to select an appropriate carbon black, and in the Banbury formulation, an optimum process aid should be added to achieve an optimum dispersion.

However, in recent years, rubber compositions that use silica as a reinforcing filler have been increasing in rubber used in tires. However, when the silica is used in a rubber composition, the viscosity is increased due to poor dispersion, and the rubber property is decreased due to the gelation reaction when it is left for a long time.

In order to prevent the above problems, dispersing aids, process oils and coupling agents are used to improve the dispersibility of silica.

The silane coupling agent serves as a crosslinking linkage between the silanol group on the silica surface used as a reinforcing agent and the rubber material of the rubber composition, and when used alone, the silane coupling agent serves to crush strong cohesion between silica and silica. However, the coupling agent has a disadvantage in that the price is high and ethanol is volatilized in the process.

The present invention has been made in order to achieve the above object, the present invention in the back rubber layer rubber composition without using silica, coupling agent and dispersant, carbon black N-351 instead of N-330 and aromatic oils without any other performance degradation modulus Its purpose is to improve performance and fatigue resistance.

In order to achieve the above object, the present invention, in the known back-up rubber layer rubber composition, 55 to 65 parts by weight of carbon black (N-330), 2 to 4 parts by weight of aromatic oils based on 100 parts by weight of natural rubber.

When the carbon black N-330 is added in less than 55 parts by weight, there is a problem that the minimum physical properties of the backup compound, in particular the modulus is reduced, and when the carbon black N-330 is added in excess of 65 parts by weight, Uniformity falls, which causes a problem that the overall physical properties fall.

In addition, when the aromatic oil is added in less than 2 parts by weight, a problem that the dispersibility of the carbon black is reduced, and when applying more than 4 parts by weight of the aromatic oil, a problem that the adhesive properties are reduced .

Table 1 is a characteristic table of carbon black according to the present invention (N-330) and the conventional invention (N-351).

<Table 1> Carbon Black Characteristic Table

division ASTM TINT (% of IRB # 3) DBP adsorption rate (cm 3 / gm) ASTM Iodine number (mg / gm) N-351 104 1.01 82 N-330 99 1.20 67

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.

Comparative Example

As shown in the compounding ratios shown in Table 2, the present invention is based on 100 parts by weight of natural rubber (SMR-20) 40 parts by weight of carbon black N-351, 7 parts by weight of a dispersing aid as a dispersant, coupling agent (Si-69) 12 Parts by weight, zinc oxide 7 parts by weight, 1.8 parts by weight of aromatic oil, 1.5 parts by weight of stearic acid, 2 parts by weight of Kumanox-RD and 1 part by weight of Kumanox-13 as anti-aging agent, 0.9 parts by weight of vulcanization accelerator (DZ), vulcanization retardant (PVI) ) 0.1 parts by weight and 3.8 parts by weight of sulfur were added to a Banbury mixer, mixed and vulcanized at 145 ° C. for 45 minutes to prepare a rubber specimen.

<Example 1>

Carbon black was added 58 parts by weight of N-330 instead of N-351, dispersing aid and coupling agent was not added, except that 2.5 parts by weight of aromatic oil was applied, the composition, composition ratio and Rubber specimens were prepared using the method.

<Example 2>

60 parts by weight of N-330 was added instead of N-351, and a dispersion aid and a coupling agent were not added, except that 3 parts by weight of aromatic oil and Kumanox-RD were applied. Rubber specimens were prepared using the same composition, composition ratio, and method.

<Example 3>

Carbon black was added with 63 parts by weight of N-330 instead of N-351, dispersing aid and coupling agent were not added, except that 3.3 parts by weight and 3.5 parts by weight of aromatic oil and Kumanox-RD were applied, respectively. Rubber specimens were prepared using the same composition, composition ratio, and method as in Comparative Example.

Table 2 Rubber Compositions of Examples and Comparative Examples

division Comparative example Example 1 Example 2 Example 3 Natural Rubber (SMR-20) 100 100 100 100 N-351 40 0 0 0 N-330 0 58 60 63 Dispersion Preparation 7 0 0 0 Coupling agent 12 0 0 0 Zincification 7 7 7 7 Aromatic oils 1.8 2.5 3.0 3.3 Stearic acid 1.5 1.5 1.0 1.0 Kumanox-RD 2.0 2.0 3.0 3.5 Kumanox-13 1.0 1.0 1.0 1.0 DZ 1.0 1.0 1.0 1.0 PVI 0.1 0.1 0.1 0.1 sulfur 3.8 3.8 3.8 3.8

Coupling Agent: Bis- (3- (triethoxysilyl) -propyl) -tetrasulfide (TESPT), known under the trade name Si69.

* Sulfur: 80-Crystex used.

<Test Example>

Comparative Examples and Examples The physical properties of the rubber specimens measured by ASTM-related regulations are shown in Table 3, and the fatigue resistance properties are shown in Table 4.

(1) scorching time

This indicates the stability of the scorch, which means that the longer the scorch time, the better the scorch stability.

(2) Home time

Monsanto rhemoter is used to measure the degree of vulcanization by the force applied to rubber with time at a certain temperature. The lower the test value, the lower the vulcanization time.

(3) Hardness: Measured with a Shore A type hardness tester at room temperature at 20 ° C. after vulcanization at 168 ° C. for 10 minutes.

(4) tensile strength

The strength at the time of cutting | disconnection was measured using the tensile tester of Instron Co., Ltd., The larger the value is, the more excellent it is.

(5) modulus

The measurement is carried out with a tensile tester (Model 4502) manufactured by Instron, by cutting the specimen into dumbbells. 100% modulus and 300% modulus refer to stress acting on the specimen when the specimen is stretched 100% and 300%, respectively, and the higher the value, the better the performance.

(6) Resistance to fatigue

The growth of cracks after 30,000 repeated refractions was recorded using the DIMATIA tester. The smaller the length of the transverse breakage and the vertical breakdown, the better the fatigue resistance.

<Table 3> Measurement results of physical properties of Comparative Example and Example 1-3

division Comparative example Example 1 Example 2 Example 3 Mooney viscosity (100 ℃) 88.5 88.9 88.3 85.4 Scorch Time (T5) 20.05 20.27 21.47 21.60 Proper Curing Time (min) 25.00 25.07 26.13 26.27 Hardness 78 77 79 80 100% modulus 52 54 56 58 300% modulus 192 193 192 198 The tensile strength 258 262 257 259 Elongation at Cutting 412 420 431 412

Table 4 Fatigue Resistance Characteristics of Comparative Examples and Examples 1-3

division Comparative example Example 1 Example 2 Example 3 Horizontal breakdown amount (mm) 6.2 5.5 4.7 5.0 Vertical breakage (mm) 3.5 3.2 1.5 2.5

As shown in Table 2, the physical property measurement results are as follows.

1) The embodiment according to the present invention can be seen that significantly improved than the comparative example in terms of fatigue performance and modulus performance.

2) The Examples according to the present invention have a performance equal to or greater than that of Comparative Examples in hardness, strength performance and the like.

As described above, by using N-330 and aromatic oil instead of carbon black N-351 in the backup rubber layer rubber composition without using a silica, a coupling agent, and a dispersant, modulus performance and fatigue resistance are greatly improved without any other performance deterioration. This also improves tire life.

Claims (1)

A known backing rubber layer rubber composition, comprising 55 to 65 parts by weight of carbon black (N-330) and 2 to 4 parts by weight of aromatic oil, based on 100 parts by weight of natural rubber.