KR20030093624A - Tire having dual structure - Google Patents

Abstract

The present invention relates to a tire having a two-layer inner liner composed of a first layer inner liner made of butyl rubber and a second layer inner liner made of NR rubber, and a second layer inner liner composed of NR rubber The present invention relates to a tire including a silica and a coupling agent to prevent the aging of the belt layer due to moisture and the like due to the high hygroscopic action of silica while maintaining adhesion to carcass.

Description

Tire having inner liner of two-layer structure {Tire having dual structure}

The present invention relates to a tire having an inner liner having a two-layer structure. More particularly, the present invention relates to a tire having improved durability by incorporating silica and a coupling agent in an inner liner layer made of a diene rubber containing natural rubber. .

In general, the inner liner of a tire includes a first layer made of butyl rubber having excellent air permeability; In order to improve the disadvantage that the butyl-based rubber layer has a disadvantage in adhesiveness with Carcass, etc., a diene-based (hereinafter NR-based) inner liner containing natural rubber is added between the butyl-based inner liner and the carcass layer to add two layers. Form the innerliner structure.

The function in the tire having such a two-layer innerliner structure complements the adhesive force between the butyl-based rubber layer and the carcass layer as described above; If the inner liner rubber penetrates the carcass layer during the tire manufacturing process, the butyl inner liner penetrates into the carcass layer and the NR inner liner is used to penetrate the carcass layer instead of the butyl rubber. Will be done.

On the other hand, in general, the air injected into the tire contains a certain amount of water, and especially when the tire is left outdoors, it contains a large amount of water inside the tire. When air is injected into the tire in such a state, the air pressure inside the tire contains a certain amount of water, and this moisture gradually decreases as the air pressure passes through the rubber layer of the tire together with the air due to the high air pressure inside the tire. .

In this process, when oxygen and moisture approaches the belt layer, the steel cord is oxidized to promote rapid aging and consequently reduce tire durability.

In order to improve this, some techniques have proposed a method of improving the durability of a tire by giving a function of absorbing oxygen passing through the rubber layer by air pressure using a salt in the NR-based inner liner layer.

Therefore, in the present invention, while searching for a method for improving the durability of the tire as a method other than using salt, it is applied to the tire tread part and is used a lot to improve the low rolling resistance performance or the running performance of the tire. Some have found that silica, which is used to supplement chip-cut performance in tread compounds, has a high hygroscopic property and can contain a large amount of moisture in the air when used in the innerliner. The invention was completed.

An object of the present invention is a tire having an inner liner having a two-layer structure that can improve moisture durability by preventing moisture penetration while maintaining adhesion, which is an inherent function of the NR-based inner liner layer, and consequently improving the durability of the tire. To provide.

Tire of the present invention for achieving the above object is an innerliner of the first layer made of butyl rubber; The inner liner having a two-layered inner liner including an inner liner of a second layer made of a diene rubber containing natural rubber and positioned between the inner liner and the carcass layer of the first layer, wherein the inner liner of the second layer The liner is made of a rubber composition containing 10 to 30 parts by weight of silica with respect to 100 parts by weight of diene rubber containing natural rubber, and 2 to 8 parts by weight of a coupling agent based on 100 parts by weight of silica. It is done.

The present invention will be described in more detail as follows.

The present invention employs silica having a high moisture absorption rate in the NR-based inner liner to absorb moisture from the inner liner including silica during the passage of air inside the tire through the rubber layer as described above. Preventing the proximity to the belt layer of steel cord) ultimately relates to a tire that can prevent the aging of the belt layer and thereby improve the durability of the tire.

In the present invention, it is intended to prevent aging of the belt layer due to moisture or the like by including silica, which is a material having high moisture absorption rate, in the NR-based inner liner layer to perform a hygroscopic action.

In this case, the reason for not applying silica to the first layer inner liner made of butyl rubber, which is the innermost part of the tire, is that butyl rubber lacks bonding strength with very high hydrophilic silica, and in this case, butyl rubber is used as a filler. This is because air or the like may leak between the silica interfaces.

NR-based innerliners generally have a formulation similar to that of carcass in order to improve adhesion to the carcass layer. That is, based on 100 parts by weight of the diene rubber including natural rubber, 40 to 70 parts by weight of carbon black, 3 to 10 parts by weight of aromatic oil, and the like, and is a basic formulation composed of other basic drugs.

Here, the compounding agents, of course, include vulcanizing agents and vulcanization accelerators, including zincation, stearic acid, anti-aging agents and the like used in conventional rubber compounding.

When silica is added to such a rubber composition, the content thereof is preferably 10 to 30 parts by weight with respect to 100 parts by weight of the diene rubber containing natural rubber. If the content of silica is less than 10 parts by weight, the effect of silica addition is insignificant. If the amount of silica is more than 30 parts by weight, the tire durability is improved, but the adhesive strength with carcass is poor.

At this time, the silica which can be used has a specific surface area (N 2 SA) of 140 to 180 m 2 / g, preferably 5 to 10% moisture content.

However, when only silica is used alone, since the adhesive strength with the carcass layer may be insufficient, the coupling agent is further included.

As the coupling agent, bis (triethoxysilylpropyl) tetrasulfane and the like can be used, and the content thereof is preferably 2 to 8 parts by weight based on 100 parts by weight of silica.

If the content of the coupling agent is less than 2 parts by weight based on 100 parts by weight of silica, the adhesive strength with the carcass layer is insufficient, and when used in excess of 8 parts by weight, the adhesive strength is good but the problem of insufficient tire durability improvement is insufficient. have.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Examples 1-3 and Comparative Examples 1-3

Next, a rubber specimen for an NR-based innerliner was prepared according to a conventional method with the composition as shown in Table 1 below.

Comparative Example 1 shows a general natural rubber inner liner, Comparative Example 2 is a case of using a small amount of silica, Comparative Example 3 is a case using 20 parts by weight of silica and no coupling agent, Comparative Example 4 is a silica It is the case of using 20 weight part and using 10 weight% of coupling agents.

And Example 3 is the example which used 40 weight part excessive silica.

Comparative Example Example One 2 3 4 One 2 3 Natural rubber 80 80 80 80 80 80 80 SBR 20 20 20 20 20 20 20 Carbon black 50 5 30 30 30 30 10 Process oil 7 7 7 7 7 7 7 Other Formulations 5 5 5 5 5 5 5 Vulcanizing agent + vulcanizing accelerator 3.5 3.5 3.5 3.5 3.5 3.5 3.5 Silica - 5 20 20 20 20 40 Coupling agent - - - 2.0 0.6 1.0 2.0 Hardness 59 60 61 62 61 60 61 Adhesive force with carcass layer 12.0 11.5 8.0 11.8 11.6 11.5 9.5 Tire durability index 100 101 120 101 115 110 117 Other compounding agent: Zinc oxide, stearic acid, anti-aging agent used in conventional rubber compounding. Equivalent accelerator: Mean sulfur and sulfenamide type vulcanization accelerator used in conventional rubber compound. Silica: Specific surface area (N2SA) General purpose silica coupling agent from 140 to 180 m2 / g and water content from 5 to 10%: Bis (triethoxysilylpropyl) tetrasulfane (Si69, TESPT) generally used for silica compounding and 1: 1 with HAF carbon black A mixture can also be used. Adhesion to the carcass layer: The inner liner and carcass adhesion sites were sampled from the tire and measured using a tensile tester. Tire durability index: tires maintained at 80 ° C. for one week at 80 ° C. under tire pressure. Endurance time is expressed as an index based on Comparative Example 1.

From the results of Table 1, in the case of Comparative Example 2 using a small amount of silica, there is no significant difference from Comparative Example 1 which is a general NR inner liner, and in Comparative Examples 3 and 4 in which 20 parts by weight of silica was applied, a coupling agent was used. In the case of Comparative Example 3 which is not, the adhesive strength with the carcass layer is insufficient, and when the coupling agent is used at 10% by weight with respect to silica, the adhesive strength is not improved at a good level or tire durability performance.

On the other hand, in the case of Examples 1 and 2, where the coupling agent content is 3% and 5% of silica, respectively, the adhesive strength was similar to that of Comparative Example 1, and the tire durability was improved by about 10 to 15% or more.

On the other hand, in the case of Example 3 in which the silica content was used at 40 parts by weight, the tire durability was improved, but the adhesion with carcass was inferior.

That is, in order to improve the aging durability by preventing moisture penetration while maintaining the adhesion by applying silica to the natural rubber inner liner, it should be understood that the silica should be limited to 10 to 30 phr and the coupling agent to 2 to 8% by weight of the silica content. have.

As described in detail above, in the manufacture of a tire having a two-layer inner liner composed of a first layer inner liner made of butyl rubber and a second layer inner liner made of NR rubber according to the present invention. In the case of including the silica and the coupling agent in the second layer inner liner composition, the high hygroscopic action of silica while maintaining the adhesive force with the carcass prevents the aging of the belt layer due to moisture or the like and ultimately improves tire durability. have.

Claims (3)

An inner liner of the first layer made of butyl rubber; In the tire having a two-layer inner liner comprising the inner liner of the second layer made of a diene rubber containing natural rubber, located between the inner liner and the carcass layer of the first layer, The inner liner of the second layer comprises 10-30 parts by weight of silica with respect to 100 parts by weight of diene rubber containing natural rubber, and a rubber composition containing 2-8 parts by weight of a coupling agent based on 100 parts by weight of silica. A tire having an innerliner having a two-layer structure, characterized in that manufactured by. The tire having a two-layer inner liner according to claim 1, wherein the coupling agent is bis (triethoxysilylpropyl) tetrasulfane. The tire having a two-layer inner liner according to claim 1, wherein the silica has a specific surface area (N 2 SA) of 140 to 180 m 2 / g and a water content of 5 to 10%.