KR101666717B1 - Tire Sidewall Rubber Compositions Improved Anti-aging Properties and Tire Comprising the Same - Google Patents

Abstract

The present invention relates to a rubber composition for a tire side wall having improved anti-aging properties by incorporating a weathering agent in a raw rubber containing partially crosslinked butyl rubber, and a tire containing the rubber composition.

Description

Technical Field [0001] The present invention relates to a rubber composition for a tire side wall having improved anti-aging properties, and a tire comprising the rubber composition.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for a tire side wall and a tire comprising the same, and more particularly, to a rubber composition for a tire side wall, which comprises a raw rubber containing partially crosslinked butyl rubber (PCP) To a rubber composition for an improved tire side wall and a tire including the same.

In the tire, the sidewall part is directly exposed to the external environment such as ultraviolet rays or ozone, and therefore, it is one of the areas where oxidation may occur most rapidly due to oxidation. Repeated deformation during driving accelerates this aging. Therefore, in order to prevent such cracking, a heat aging inhibitor and an antioxidant are included in the rubber composition for a tire side wall. However, such low molecular weight organic substances disappear naturally by oxidation, and durability is difficult to sustain.

In Korean Patent Application No. 1997-0061757, diene rubbers as a sidewall rubber composition and butyl rubber as an EPDM rubber were mixed to propose improvement of aging resistance to ozone and ultraviolet exposure.

In Korean Patent Application No. 2006-0055557, titanium dioxide and thermochromic dye are applied to raw rubber including butyl rubber and EPDM rubber as sidewall rubber composition to improve crack prevention and color improvement by ozone Respectively.

However, since the butyl rubber has an unsaturated structure of only 0.8 to 2.5 mol%, co-cure with the natural rubber or butadiene rubber used in the sidewall is difficult to occur, and the durability can be lowered.

It is an object of the present invention to provide a rubber composition for a tire side wall having improved resistance to aging due to ozone and ultraviolet radiation in order to solve the problems of the prior art.

The rubber composition for a tire side wall of the present invention comprises 1 to 5 parts by weight of a butyrated reaction product of p-cresol and dicyclopentadiene as 100 parts by weight of raw rubber containing partially crosslinked butyl rubber .

The raw rubber used in the rubber composition for a tire side wall of the present invention may be a partially crosslinked butyl rubber and a mixed rubber of natural rubber. The weight ratio of the partially crosslinked butyl rubber: natural rubber is 10 to 90: 90 ≪ / RTI >

In the present invention, the starting rubber may further include at least one rubber selected from synthetic rubbers in addition to the above-mentioned natural rubbers.

Examples of the synthetic rubber include, but not limited to, styrene butadiene rubber, butadiene rubber, butyl rubber, epichlorohydrin rubber, nitrile rubber, hydrogenated nitrile rubber, polyisobutylisoprene- Butadiene styrene copolymer rubber, ethylene propylene rubber, ethylene propylene diene monomer rubber, hyaluron rubber, chloroprene rubber, styrene-butadiene styrene copolymer rubber, Ethylene vinyl acetate rubber, acrylic rubber and the like, and styrene butadiene rubber or butadiene rubber can be preferably used.

The partially crosslinked butyl rubber is used for improving co-cure, and preferably has a degree of crosslinking of 1 to 90% and a specific gravity of 0.90 to 0.95. When the degree of crosslinking and specific gravity are out of the above range The co-cure property with the inner component declines, which is undesirable.

It is preferable that the reaction product of p-cresol and dicyclopentadiene used in the rubber composition for a tire side wall of the present invention is 1 to 5 parts by weight based on 100 parts by weight of the starting rubber. When the amount is less than 1 part by weight, And the fatigue property is lowered in the natural aging process, and if it exceeds 5 parts by weight, the mechanical properties are deteriorated.

In the rubber composition of the present invention, additives such as carbon black, zinc oxide, stearic acid, a pressure-sensitive adhesive, a process oil, a vulcanizing agent, and an accelerator may be appropriately selected and added to conventional rubber composition additives, And the content are well known in the art.

The rubber composition for a tire side wall of the present invention exhibits improved aging resistance by using a raw rubber containing partially crosslinked butyl rubber and a butylated reaction product of p-cresol and dicyclopentadiene as weather resistance, The pad-test performance and the durability performance by the tire sidewall rubber and the co-cure have an effect showing equal level.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples. The following examples are merely examples for carrying out the present invention and are not intended to limit the scope of protection of the present invention.

≪ Comparative Example 1 &

60 parts by weight of butadiene rubber and 40 parts by weight of natural rubber were used as the raw rubber, and 50 parts by weight of carbon black, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 5 parts by weight of a pressure- 10 parts by weight of oil, 0.5 part by weight of a vulcanizing agent and 1.5 parts by weight of an accelerator were added to prepare a rubber composition for a tire side wall.

≪ Comparative Example 2 &

60 parts by weight of butadiene rubber and 40 parts by weight of natural rubber were used as raw material rubber, and 50 parts by weight of carbon black as a filler, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 5 parts by weight of a pressure-sensitive adhesive, 10 parts by weight of a process oil, 0.5 parts by weight of a vulcanizing agent and 1.5 parts by weight of an accelerator were added to prepare a rubber composition for a tire side wall.

≪ Comparative Example 3 &

60 parts by weight of butyl rubber as a raw material rubber and 40 parts by weight of natural rubber were used as a raw material rubber, and 50 parts by weight of carbon black as a filler, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, , 5 parts by weight of a pressure-sensitive adhesive, 10 parts by weight of a process oil, 0.5 parts by weight of a vulcanizing agent and 1.5 parts by weight of an accelerator were added to prepare a rubber composition for a tire side wall.

≪ Example 1 >

30 parts by weight of butyl rubber, 30 parts by weight of partially crosslinked butyl rubber (PCP) and 40 parts by weight of natural rubber were used as the starting rubber as the raw rubber, and 50 parts by weight of carbon black and 3 parts by weight of zinc oxide , 2 parts by weight of stearic acid, 2 parts by weight of an antistatic agent, 5 parts by weight of a pressure-sensitive adhesive, 10 parts by weight of a process oil, 0.5 parts by weight of a vulcanizing agent and 1.5 parts by weight of an accelerator were added to prepare a rubber composition for a tire side wall.

≪ Example 2 >

60 parts by weight of a partially crosslinked butyl rubber (PCP) and 40 parts by weight of a natural rubber were used as raw rubber in the composition shown in the following Table 1, and 50 parts by weight of carbon black as a filler, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of an antistatic agent, 5 parts by weight of a pressure-sensitive adhesive, 10 parts by weight of a process oil, 0.5 parts by weight of a vulcanizing agent and 1.5 parts by weight of an accelerator were added to prepare a rubber composition for a tire side wall.

The specimens were prepared from each of the rubber compositions prepared according to the above Comparative Examples and Examples, vulcanized, and then their physical properties were measured according to the ASTM standard. The results are shown in Table 2 below.

                                                   (Unit: parts by weight) division Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Butadiene rubber 60 60 0 0 0 Butyl rubber 0 0 60 30 0 Partially crosslinked butyl rubber (PCP) ^{1 )} 0 0 0 30 60 Natural rubber 40 40 40 40 40 Carbon black ^{2 )} 50 50 50 50 50 Process oil 10 10 10 10 10 Zinc oxide 3 3 3 3 3 Stearic acid 2 2 2 2 2 Noise control ^{3 )} 0 2 2 2 2 Adhesive ^{4 )} 5 5 5 5 5 sulfur 0.5 0.5 0.5 0.5 0.5 Accelerator ^{5 )} 1.5 1.5 1.5 1.5 1.5

Note 1) KALAR 5263 (Royal Elastomer): Crosslinking degree 2%

2) Iodine adsorption value: 36 mg / g, DBP adsorption value: 90 ml / 100 g

3) Butyrated reaction product of p-cresol and dicyclopentadiene (trade name: Wingstay-L, manufactured by Kumho Petrochemical Co., Ltd.)

4) Adhesive (Dyphene-8318): octyl-phenol formaldehyde resin

5) 2'-dibenzothiazole disulfide

                                            (Unit: relative index) division Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Hardness ^{1 )} 102 100 100 100 100 100% modulus ^{2 )} 102 100 98 98 98 Adhesive strength ^{3 )} 100 100 80 97 99 Crack growth length ^{4 )} 98 100 70 66 65 Aging
Crack growth length ^{5 )} 120 100 65 62 60 Durability ^{6 )} 98 100 90 102 103

1) The hardness is based on the Shore A test, and the higher the hardness, the harder it is.

2) 100% modulus represents the stress applied when the tensile specimen is elongated at 100%.

3) The adhesive strength is measured by peeling the adhesive specimen, and the higher the strength, the higher the strength.

4) The crack growth length is measured with a Demattia Flex Crack tester. After the sample is made, the length of crack growth is measured after flexing 100,000 times at 50 ℃. The higher the value, the more cracks are present and the lower the fatigue.

5) The aging crack growth length is measured by measuring the crack growth length with a Demattial Flex Carck tester after storing the sample in a chamber of 105 ℃ for 1 day. After the sample is made, the length of crack growth is measured after bending 100,000 times at 50 ℃ do. The higher the value, the more cracks are present and the lower the fatigue.

6) The durability refers to the time from dismantling after running at 80km / h under standard load condition after attaching actual finished product tires (205 / 65R16 standard) to the durability tester. The higher the durability, the better the durability.

As shown in Table 2, it can be seen that Examples 1 and 2 improved the anti-aging performance while maintaining the same mechanical properties as Comparative Examples 1 to 3.

Claims (3)

To 100 parts by weight of a raw rubber containing a partially crosslinked butyl rubber having a crosslinking degree of 1 to 90% and a specific gravity of 0.90 to 0.95, butylated reaction product of p-cresol and dicyclopentadiene as an antistatic agent To 5 parts by weight,
The raw material rubber is made of the partially crosslinked butyl rubber and natural rubber or synthetic rubber other than the natural rubber may be selected from styrene butadiene rubber, butadiene rubber, butyl rubber, epichlorohydrin rubber, nitrile rubber, hydrogenated nitrile rubber, Brominated polyisobutyl isoprene-co-paramethyl styrene (BIMS) rubber, urethane rubber, fluorine rubber, silicone rubber, styrene ethylene butadiene styrene copolymer rubber, ethylene propylene rubber, ethylene propylene diene monomer The rubber composition for a tire side wall, further comprising at least one synthetic rubber selected from the group consisting of rubber, hypalon rubber, chloroprene rubber, ethylene vinyl acetate rubber and acrylic rubber. delete A tire having a side wall portion made of the rubber composition for a tire side wall according to Claim 1.