KR100333412B1 - Tires having rubber layer enhanced anti-ozone crack at tread shoulder part - Google Patents

Abstract

According to the present invention, the rubber composition between the tread shoulder portion and the side wall portion is different, but the rubber composition having excellent ozone resistance is positioned on the tread shoulder portion, and the adhesive rubber composition having excellent adhesion is excellent in order to improve adhesion with the conventional side wall rubber. The present invention relates to a tire manufactured by applying a liquid between a tread shoulder portion and a sidewall portion, and is a tread shoulder due to an oil-containing EPDM rubber having excellent ozone crack resistance and excellent dispersibility with other rubbers used in the tread shoulder portion. It can prevent the negative ozone cracking performance and prevent the problem of poor adhesion between the tread shoulder and the sidewall, and can improve the appearance of tires and reduce the manufacturing cost by eliminating excessive use of anti-aging agents. .

Description

Tires having rubber layer enhanced anti-ozone crack at tread shoulder part}

The present invention relates to a tire having a rubber layer having improved ozone crack resistance in a tread shoulder portion, and more particularly, an EPDM rubber and butadiene rubber having excellent ozone crack resistance and excellent dispersibility with other rubber in the tread shoulder portion. And it relates to a tire manufactured by placing a rubber made of natural rubber as a raw material, applying a liquid cement rubber excellent in adhesion to improve the adhesion of the side wall and the tread shoulder portion.

The schematic structure of the tire includes a cap tread (1), a tread shoulder or tread wing (2), a sidewall (3), an inner belt (4), and an inner liner (5) in contact with the ground as shown in FIG. Can be divided into

In general, since tires have a long service life and bend in the air, tire manufacturers are trying to improve the crack resistance of the outer rubber.

As a conventional technique for this purpose, a rubber composition containing a large amount of ethylene-propylene-diene terpolymer having excellent ozone resistance may be used for the sidewall site. However, such a rubber composition has excellent ozone resistance, but has a problem in adhesion to adjacent rubber, in particular, a tread wing part, and the cost of the rubber composition is increased, so that it is not practically used.

In another technique, a rubber composition containing a large amount of an ozone anti-aging agent has been used in the sidewall portion to improve ozone resistance crack resistance. However, this technique has the following problems; First of all, tires are accompanied by heat generation while driving for a long time, but if a large amount of anti-aging agent is included, there is no problem in the initial driving, but when the long-term use is used, loss of the anti-aging agent occurs and ozone cracks are generated. And, by containing a large amount of anti-aging agent, discoloration of the rubber occurs, the appearance quality is lowered, causing a cost increase.

In addition, conventionally, by using the rubber composition which improved such an ozone crack performance similarly to a tread shoulder part or a side wall part, there existed a problem in external color and cost.

However, when the rubber composition of the tread shoulder part and the side wall part is used differently, a problem of poor adhesion between the tread shoulder part and the side wall part occurs.

In particular, the problem of poor adhesion is that a rubber composition containing a large amount of ethylene-propylene-diene terpolymer or a very low unsaturated butyl rubber having excellent ozone resistance is used on the sidewall, and a natural rubber and butadiene rubber is used on the tread shoulder part. When using a conventional sidewall rubber composition consisting of a large difference in the rubber composition of the two parts due to the poor adhesion of the shoulder and the sidewall portion, there is a problem that causes cracks.

Accordingly, the present inventors have solved the problem of ozone crack generation in the conventional tread shoulder part, and while seeking a solution to solve the problem of adhesion with the adjacent rubber and the appearance color and cost increase of the tire, the ozone crack performance is very excellent. To properly disperse ethylene-propylene-diene terpolymer containing a large amount of non-polluting oil with other rubbers, place it in the tread shoulder portion, and improve the adhesion between the tread shoulder portion and the sidewall rubber. As a result of applying an adhesive rubber composition with excellent adhesion between the tread shoulder rubber and the side wall rubber, it is possible to improve the adhesion problem between both rubbers and to improve the ozone crack resistance of the tread shoulder part even after long-term use. Since it does not need to contain a large amount, it improves the rubber discoloration to improve the appearance quality of the tires at the same time. It has been found that the present invention can be improved to complete the present invention.

Accordingly, an object of the present invention is to provide a tire that can solve the problem of adhesion between both rubbers while improving the ozone crack resistance of the tread shoulder part by varying the rubber composition of the tread shoulder part and the side wall part.

In order to achieve the above object, the tire of the present invention is an ethylene-propylene-diene terpolymer (pure rubber powder 10 − 40 parts by weight of natural rubber, 10 to 30 parts by weight of butadiene rubber and 30 to 50% oil). 40 parts by weight), 100 parts by weight of the raw material rubber (total parts by weight of pure rubber); 40 to 60 parts by weight of carbon black having a DBP oil absorption of 80 to 110 ml / 100 g and an iodine adsorption amount of 30 to 95 mg / g; within 1.5 parts by weight of p-phenylene diamine-based antioxidant; And placing the second rubber composition layer including the additive in the tread shoulder portion, and applying liquid cement composed of an adhesive rubber composition to the sidewall portion and the adjacent surface of the tread shoulder portion.

1 is a cross-sectional view showing a general structure of a tire,

2 is a cross-sectional view showing the structure of a tire according to the present invention.

<Detailed Description of Major Symbols in Drawing>

1, 111-cap tread

2, 112-tread shoulder

3, 113-sidewall

4, 114-belt

5, 115-inner liner

Referring to the present invention as described in detail based on the accompanying drawings as follows.

In the present invention, the rubber composition of the tread shoulder portion and the side wall portion is different, the specific structure is as shown in FIG.

Specifically, the tread shoulder portion 112 is an ethylene-propylene-diene terpolymer (pure rubber powder 10-40) containing 40 to 60 parts by weight of natural rubber, 10 to 30 parts by weight of butadiene rubber and 30 to 50% oil. Parts by weight), 100 parts by weight of the raw material rubber (total parts by weight of pure rubber); 40 to 60 parts by weight of carbon black having a DBP oil absorption of 80 to 110 ml / 100 g and an iodine adsorption amount of 30 to 95 mg / g; within 1.5 parts by weight of p-phenylene diamine-based antioxidant; And a second rubber composition layer comprising the additive.

This rubber layer has very good ozone crack resistance, has an oil so that it has good dispersibility with other rubbers, and when mixed with an ethylene-propylene-diene terpolymer containing a large amount of non-polluting oil, the ozone crack resistance of the tread shoulder part is appropriate. Can improve.

Specifically, the ethylene-propylene-diene terpolymer has 6-10% of ethylidene norbornene and 60-80% of ethylene in terms of the vulcanization rate of rubber and dispersibility with natural rubber. desirable

In addition, the use of ethylene-propylene-diene terpolymer and butadiene rubber together can improve the adhesion between the flex crack and the adjacent rubber without sacrificing the ozone performance.

Meanwhile, in the present invention, in order to distinguish between the second rubber composition layer and the side wall portion 113, the tread and the tread shoulder rubber are simultaneously extruded when the tread is extruded, or after the tire is finished, a rubber strip ( Strips are attached to the green tire (unvulcanized tire) shoulder portion separately so as to form the structure of FIG. 2.

When such a rubber composition is used for tread shoulder rubber, the ozone resistance can be maintained due to the effect of the ethylene-propylene-diene terpolymer even if the tire runs for a long time and the anti-aging agent contained in the rubber composition is lost.

However, the second rubber composition layer as described above has a problem in that both the ozone resistance and the flex crack resistance are superior to those of the conventional tread shoulder rubber, but the adhesion between the rubbers is low. Therefore, in the present invention, the liquid cement including the adhesive rubber composition having excellent adhesion between the second rubber composition layer 112 as described above and adjacent to the sidewall portion 113 rubber is applied.

At this time, the liquid cement is an organic solvent containing an adhesive rubber composition containing 30 to 50 parts by weight of carbon black with respect to 100 parts by weight of the raw material rubber consisting of 70 to 90 parts by weight of natural rubber and 10 to 30 parts by weight of ethylene-propylene-diene terpolymer. It was dissolved in to give a solid content of 5 to 15% to apply.

When the content of the ethylene-propylene-diene terpolymer in the liquid cement exceeds 30 parts by weight, the adhesive strength with the second rubber composition layer is reduced.

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

Preparation Example 1 and Comparative Examples 1 to 3

Next, a second rubber composition layer of the tread shoulder part was prepared in the composition as shown in Table 1 below. Then, the ozone crack resistance, the flex crack growth length, and the adhesive strength between rubbers with the rubber of Comparative Example 1 were measured on the obtained rubber, and the results are shown in Table 2 below.

At this time, the ozone crack generation time was measured when the ozone crack was first generated when the specimen was left in a chamber having a 50 ppm ozone concentration given a 20% strain. After leaving for 30 days at, the specimen was placed in a chamber having an ozone concentration of 50pphm with 20% strain and then measured at the time of the first occurrence of ozone cracks.

In addition, the flex crack growth test measures the length (initial crack length is fixed at 0.2 mm) grown at 100 kcycle flex fatigue with a Demattia crack tester.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Preparation Example 1 Natural rubber 60 60 60 60 EPDM A - 40 - - EPDM B - - 80 40 Butadiene rubber 40 - - 20 Carbon black 50 50 50 50 Processing oil 10 10 - - Antioxidant A 2.5 - - 1.0 Antioxidant B 2 - - - Wax 2 - - 1.0 Zinc oxide 3 3 3 3 Stearic acid 1.5 1.5 1.5 1.5 Sulfur and vulcanization accelerators 3 3 3 3 EPDM Co., Ltd .: A-ethylene-propylene-diene terpolymer B with 7% ENB% and 56% ethylene content B-ENB% 9.5%, ethylene content 74%, naphthenic acid oil 100 Ethylene-propylene-diene terpolymer carbon black containing a weight part: Carbon black antiaging agent whose DBP oil absorption amount is 80-110 ml / 100g, and the iodine adsorption amount is 30-95 mg / g: A-N-phenyl-N /-( 1,3-dimethyl butyl) -p-phenylenediamine B-poly- (2,2,4-trimethyl-1,2-dihydroquinoline) wax: microcrystalline wax

Comparative Example 1 Comparative Example 2 Comparative Example 3 Preparation Example 1 Ozone crack resistance When the initial crack occurred 12 days 38 days 48 days 31st Ozone cracks after outdoor exposure 5 days 32 days 42 days 25 days Flexural Crack Growth Length (100kcycle) 20.5mm 17.0mm 15.5mm 8.5mm Adhesion between rubbers (Manufacture Comparative Example 1 Adhesion with rubber) 31kg / in 12kg / in 14kg / in 20kg / in

In Comparative Example 1, the rubber composition commonly used in the tread shoulder portion as well as the sidewall portion is the same composition (because of its own comparison), and thus, the adhesion between rubbers is very excellent. However, it can be seen that the ozone crack resistance is very disadvantageous as compared with the case of Preparation Comparative Examples 2 to 3 and Preparation Example 1.

In addition, Comparative Example 2 contained a large amount of EPDM rubber with excellent ozone resistance, and excellent ozone and bending crack performances compared to Comparative Example 1, but showed low adhesion between rubbers. Thus, in the case of using such a rubber composition in the tread shoulder portion, there may be a problem in adhesion with the conventional sidewall rubber, such as Preparation Comparative Example 1.

Comparative Example 3 contains EPDM rubber containing oil, which has good mixing and dispersibility between EPDM rubber and natural rubber, which has completely different properties between rubbers. And it can be seen that the adhesion between the rubber is good. However, this also has a significantly lower adhesion between rubbers than in Production Comparative Example 1 as in Production Comparative Example 2.

However, when mixed with the oil-containing EPDM rubber and butadiene rubber as in Preparation Example 1, the bending crack resistance and the adhesive strength between the rubber can be greatly improved as compared to the Comparative Examples 2 or 3 without sacrificing the ozone performance. there was. By the way, it can be seen that Preparation Example 1 also has a slight decrease in the adhesive strength between rubbers.

Therefore, it is necessary to apply a separate liquid cement that can improve the adhesion between the rubber.

Preparation Example 1 'and Comparative Example 1'-2'

From the results of Preparation Example 1, in the present invention, it can be seen that the adhesive cement rubber for improving the adhesion between the tread shoulder rubber and the sidewall rubber, the composition as shown in the following Table 3 cement rubber composition for adhesion Was prepared. About obtained rubber

Comparative Example 1 ' Comparative Example 2 ' Preparation Example 1 caoutchouc 100 60 80 EPDM A - 40 20 Carbon black 40 40 40 Processing oil 5 5 5 Anti-aging 1.5 1.5 1.5 Zinc oxide 3 3 3 Stearic acid 1.5 1.5 1.5 Sulfur and vulcanization accelerators 3 3 3

The rubber composition as shown in Table 3 was dissolved in an organic solvent, made into a liquid phase, and applied between a tread shoulder and a side wall.

The concentration of the rubber cement is preferably 5 to 10% solids content.

Example

The adhesive strength between the tread shoulder portion rubber and the liquid cement rubber obtained through the preparation example was evaluated, and the results are shown in Table 4 below.

Adhesion test is a tread shoulder rubber / adhesive cement / normal sidewall rubber composition obtained through the above production example, and the vulcanized rubber is combined between the compositions in three layers and vulcanized at 160 ° C. for 20 minutes at a rate of 50 mm / min. The force required at this time is measured by peeling off the rubber layers.

(Unit: kg / in) Tread shoulder rubber Comparative Example 1 Comparative Example 2 Comparative Example 3 Preparation Example 1 Adhesive Rubber Comparative Example 1 ' 41 13 15 23 Comparative Example 2 ' 12 12 14 13 Preparation Example 1 36 29 31 37

From the results of Table 4, it can be seen that the adhesive rubber of the manufacturing example 1 'is placed between the tread shoulder rubber and the side wall portion of the manufacturing example 1 is the most excellent adhesion.

As described above in detail, according to the present invention, the rubber composition having excellent ozone resistance is positioned in the tread shoulder portion, and the adhesive rubber composition having excellent adhesion is tread in a liquid state in order to improve the adhesion with a conventional sidewall rubber. When applied between the shoulder part and the side wall part, it can be seen that the ozone crack performance of the tread shoulder part can be prevented from deterioration (see the results of the outdoor exposure ozone crack test), and the problem of poor adhesion between the tread shoulder part and the side wall can also be solved. have.

Claims (3)

It is composed of 40 to 60 parts by weight of natural rubber, 10 to 30 parts by weight of butadiene rubber and 30 to 50% of ethylene-propylene-diene terpolymer (10 to 40 parts by weight of pure rubber), and 100 parts of raw rubber Parts (gross weight of pure rubber); 40 to 60 parts by weight of carbon black having a DBP oil absorption of 80 to 110 ml / 100 g and an iodine adsorption amount of 30 to 95 mg / g; within 1.5 parts by weight of p-phenylene diamine-based antioxidant; And placing the second rubber composition layer comprising the additive in the tread shoulder portion, A tire manufactured by applying a liquid cement made of an adhesive rubber composition to a side wall portion and an adjacent surface of the tread shoulder portion. The tire according to claim 1, wherein the ethylene-propylene-diene terpolymer in the second rubber composition layer has 6-10% ethylidene norbornene and 60-80% ethylene content. The adhesive cement according to claim 1, wherein the liquid cement contains 30 to 50 parts by weight of carbon black with respect to 100 parts by weight of raw material rubber composed of 70 to 90 parts by weight of natural rubber and 10 to 30 parts by weight of ethylene-propylene-diene terpolymer. A tire, characterized in that the composition is dissolved in an organic solvent and applied in a liquid with a solid content of 5 to 15%.