KR100357049B1 - Hard Apes Rubber Composition for Tire - Google Patents

Abstract

The present invention is a hard apex rubber constituting the tire bead portion, a rubber composition having excellent hardness and heat resistance properties, and the addition ratio of sulfur and accelerator is 1.5 parts by weight / 2.5 parts by weight-3.0 parts by weight / 1.5 parts by weight based on 100 parts by weight of the raw material rubber. It consists of a rubber composition.

By the above configuration, the rubber composition of the present invention can improve the durability of the tire by improving the heat aging characteristics without using the dimorpholyl disulfide, which is an environmental regulatory substance, and also does not use dimorpholyl disulfide. It provides an environmentally friendly rubber composition that can fundamentally block rosamine (Nitrosamine).

Description

Hard Apex Rubber Composition for Tires

The present invention relates to a rubber composition having excellent hardness and heat resistance as a hard apex rubber constituting the tire bead portion.

In the case of radial tires, road pavement improves and high-speed long-distance operation increases, causing problems such as early detachment due to deterioration of physical properties due to heat aging of rubber at the bead area due to high temperature heat. The bead part is composed of bead, hard apex, soft apex, etc. In the case of the existing hard apex (HARD-apex) to use 100 parts by weight of natural rubber alone to improve the adhesive properties with other parts, high-hardness rubber Sulfur-bonded donor which induces mono-sulfide bond to give heat-resistant carbon black with a large surface area of about 65 parts by weight and at least 2.0 parts by weight of sulfur. Dimorpholine disulfide is mainly used as a compound.

However, the dimorpholyl disulfide compound is an environmentally harmful substance that causes harmful nitrosamine (Nitrosamine) to the human body and is currently taking measures such as restricting imports when using such drugs in Western Europe. Legislation is under way to reduce it.

The inventors of the present invention seek to improve tire durability without using the dimorphyl disulfide compound, and the fact that the thermal aging characteristics can be remarkably improved by changing the amount of sulfur and accelerator used in conventional vulcanization systems. After finding out the present invention was completed.

Accordingly, an object of the present invention is to apply a new crosslinking system that improves heat resistance and rupture and blow-out characteristics due to heat generated while the tire is running, without using dimorphyl disulfide, which is known as an environmentally harmful substance. To provide an apex rubber composition.

1 is a cross-sectional view of a tire showing a hard apex part.

<Description of Symbols for Major Parts of Drawings>

1: Hard Apex 2: Soft Apex

3: bead 4: rim

The present invention is a high-pex rubber composition excluding the application of the existing sulfur-bonding donor dimorphoryl disulfide by adjusting the sulfur and the accelerator in a predetermined content ratio.

1 shows a hard apex 1 of a tire. The hard apex (1) is a part located between the tire rim (4) and the soft apex (2), and should have good adhesion properties with the adjacent part, and in particular, it is required to have good heat aging characteristics, high hardness, bending resistance, and compression ratio. . Meanwhile, reference numeral 3 denotes beads coupled with the hard apex 1.

The hard apex rubber composition of the present invention uses 100 parts by weight of natural rubber alone in order to improve the adhesive properties with other parts, and has about 60 to 80 parts by weight of carbon black having a large surface area as a reinforcing filler and 3 to 10 parts by weight of process oil. In addition, sulfur and an accelerator are added at a predetermined composition ratio together with 1 to 3 parts by weight of stearic acid, 5 to 10 parts by weight of zinc (ZnO), other plasticizers, softeners, preservatives, and the like as an active agent. Among the components constituting the hard-apex rubber composition, except for sulfur and accelerators, all known components and composition ratios are used, and thus only sulfur and accelerators will be described in detail below.

The sulfur raw material usable in the present invention is 70-90% sulfur, preferably 80% crystax sulfur, in which oil is treated instead of free sulfur, which is determined in consideration of process stability as a vulcanizing agent. The amount of sulfur added is preferably 1.5 to 3.0 parts by weight based on 100 parts by weight of the raw rubber, and if the amount of sulfur is less than 1.5 parts by weight, it is difficult to meet the required physical properties of the hard airpex, and if it exceeds 3.0 parts by weight, the bending resistance However, this is undesirable because it leads to a decrease in process stability and heat resistance.

In addition, the promoters usable in the present invention include N-cyclohexyl 2-benzothiazylsulfenamide or N-tertiarybutyl 2-benzothiazolesulfenamide, and these are conventionally used materials in the art. You may use a compound which performs the same function. The amount of the accelerator added is preferably 1.5 to 2.5 parts by weight based on 100 parts by weight of the raw material rubber. If the amount is less than 1.2 parts by weight, the improvement of the heat resistance is not expected. It is not desirable to cause.

In order to improve the durability of the tire without using a conventional sulfur-bonded donor, it is required to adjust the composition ratio of the sulfur and the accelerator added to the rubber composition to a certain range. In the conventional classical vulcanization system, the composition ratio of sulfur and accelerator is 3: 1, and the sulfur modulus and the thermal aging characteristics of the rubber are remarkably deteriorated under such a composition. Therefore, a sulfur binding donor such as dimorphyl disulfide must be added.

The present invention, unlike the conventional classical vulcanization system as described above, by increasing the content of the added accelerator to adjust the ratio of sulfur / accelerator to 1.5 / 2.5 ~ 3.0 / 1.5 to ensure the thermal stability of the cross-linking system and also in the above range Desired physical properties can be easily obtained by adjusting the amount of sulfur and accelerator mixed in accordance with the user's level of demand within.

Hereinafter, the contents of the present invention will be described in detail with reference to examples, but the scope of the present invention is not limited to these examples.

<Example 1>

70 parts by weight of carbon black (N330), 5 parts by weight of oil, 7 parts by weight of zinc oxide, 1 part by weight of stearic acid, B-18-S (formaldehyde resin) based on 100 parts by weight of natural rubber (SMR-5CV) as a raw material rubber And 8.5 parts by weight of an aerosol (amine), 2.5 parts by weight of Cyrez-964, 3.0 parts by weight of 80% sulfur, and 1.0 parts by weight of accelerator (N-tertiarybutyl 2-benzothiazolesulfenamide) in a Banbury mixer. Emitted at In Example 1, the mixing ratio of the existing sulfur / promoting agent was followed as it is, but dimorpholyl disulfide (Sulfasan-R: trade name) was not used.

Physical properties of the resulting rubber composition was carried out in accordance with the ASTM standard specifications, and the composition ratios and characteristics test results of the rubber composition are shown in Table 1.

<Example 2>

Except for adding 1.5 parts by weight of the accelerator was carried out in the same manner as in Example 1, the physical properties of the rubber composition produced in accordance with the ASTM standard specifications, the composition ratio and characteristics test results of the rubber composition in Table 1 Indicated.

<Example 3>

Except for 2.75 parts by weight of 80% sulfur and 1.5 parts by weight of the accelerator was added in the same manner as in Example 1, wherein the physical properties of the resulting rubber composition was carried out according to the ASTM standard, rubber composition Table 1 shows the component ratios and characteristics of the test results.

<Example 4>

Except that the addition of 2.50 parts by weight of sulfur and 1.5 parts by weight of 80% sulfur was carried out in the same manner as in Example 1, wherein the physical properties of the resulting rubber composition was carried out according to the ASTM standard, rubber composition Table 1 shows the component ratios and characteristics of the test results.

Example 5

Except that 2.75 parts by weight of 80% sulfur and 2.0 parts by weight of the accelerator was added in the same manner as in Example 1, wherein the physical properties of the resulting rubber composition was carried out in accordance with the ASTM standard, rubber composition Table 1 shows the component ratios and characteristics of the test results.

Comparative Example

Except for adding 1.0 parts by weight of dimorpholyl disulfide (Sulfasan-R: brand name) as a conventional vulcanizing system was carried out in the same manner as in Example 1, the physical properties of the resulting rubber composition was carried out in accordance with ASTM standard standards , The composition ratio of the rubber composition and the results of the characteristic test are shown in Table 1.

<Table 1> Rubber composition and physical property test results

Creation costs Comparative example Example 1 Example 2 Example 3 Example 4 Example 5 Natural Rubber (SMR-5CV) 100 100 100 100 100 100 Carbon black (N330) 70 70 70 70 70 70 oil 5 5 5 5 5 5 Zinc (ZnO) 7 7 7 7 7 7 Stearic acid One One One One One One Other chemical 8.5 8.5 8.5 8.5 8.5 8.5 Cyrez-964 2.5 2.5 2.5 2.5 2.5 2.5 80% sulfur (oil treatment) 3.0 3.0 3.0 2.75 2.50 2.50 Accelerator (NS) 1.0 1.0 1.5 1.5 1.5 2.0 Sulfasan-R 1.0 0 0 0 0 0 Hardness (Shore-A) 71 68 74 71 70 69 300% modulus (Kgf / ㎠) 205 168 217 207 208 200 Tensile Strength (Kgf / ㎠) 238 230 240 225 241 231 Elongation break (%) 367 359 357 325 372 369 Revision (%) 180 ℃ at 30min 200 ℃ at 10min 4535 6549 2118.5 2520 2117 1815 DMFC (cm) 10.2 / 8.4 11.3 / 8.2 8.7 / 6.5 8.5 / 5.7 6.4 / 3.9 4.7 / 3.3 Heat-build up (℃) 30.7 34.8 27.6 26.4 27.8 24.5 Blow-out time (minutes) 12.5 7.8 21.5 17.8 15.4 18.4

As shown in Table 1, the rubber of Example 1, which does not use Sulfasan-R while maintaining the existing sulfur / promoter ratio, can be seen that the modulus and heat aging characteristics are significantly reduced. On the other hand, it can be seen that the rubbers of Examples 2 to 5 in which the sulfur / promoter ratio was applied without the application of Sulfasan-R were significantly improved in heat aging characteristics, heat generation and rupture characteristics at high temperatures.

<Test Example>

The rubber composition of Comparative Example and Example 3 was applied to a truck bus tire (11R22.5 973 pattern) to test the durability of the bead site is shown in Table 2.

<Table 2> Bead endurance test results

division Comparative example Example 3 BAB test (average) 431 hours 498 hours

* BAB (Bead above Burst) test: Measures the time it takes for an accident while varying the load index with time when driving from 80 to 40 km / h.

As shown in Table 2, the tire of the present invention applied at a ratio of sulfur / accelerator = 2.5 / 1.5 has a relatively superior durability property than the conventional one as a comparative example.

The present invention can improve the durability of the tire by improving the heat aging characteristics without using the dimorpholyl disulfide which is an environmental regulatory material. In addition, the present invention provides an environmentally friendly rubber composition that can fundamentally block nitrosamine (Nitrosamine) harmful to the human body because it does not use dimorphyl disulfide.

Claims (3)

In the hard-apex rubber composition which supports the sidewall of a tire, 70-90% sulfur and N-cyclohexyl 2-benzothiazylsulfenamide or N-ter as oil is treated with respect to 100 parts by weight of natural rubber. A hard apex rubber composition comprising 1.5 parts by weight / 2.5 parts by weight to 3.0 parts by weight / 1.5 parts by weight of an addition ratio of sherrybutyl 2-benzothiazolesulfenamide. delete delete