KR101073117B1 - Rubber composition for tire tread - Google Patents

Abstract

The present invention relates to a rubber tread rubber composition, the tire tread rubber composition, based on 100 parts by weight of natural rubber, 50 to 80 parts by weight of carbon black; And 3 to 20 parts by weight of a novolak-based phenolic resin, wherein the carbon black has a pH of 7 to 10, an I ₂ adsorption of 115 to 135, a DBP adsorption of 105 to 120 cc / 100 g, and a tin strength of 115 to 115. 125, toluene coloring transmittance is characterized by 40 to 48%.

The rubber composition for tire treads according to the present invention has the advantage of minimizing the movement of the stud pins and at the same time improving the wear resistance and chip cut performance.

Tire tread, rubber composition, carbon black, novolac phenolic resin, snow rally tire

Description

Rubber composition for tire treads {RUBBER COMPOSITION FOR TIRE TREAD}

The present invention relates to a rubber composition for tire treads, and more particularly, to a rubber composition capable of preventing movement and detachment of a stud pin while having excellent wear resistance and chip cut performance.

Recently, car racing is being used as an active marketing tool for the promotion of automobiles and makers, which are becoming increasingly high-performance, and the stage passing time of the race competition section is being reduced very quickly. In addition to being harsh, the situation is using tires optimized for the conditions according to various conditions such as road surface, temperature.

In the snow ice rally, when the air temperature is low and the snow accumulates, the road surface becomes more difficult, and it is difficult to balance stability and durability by changing the braking force, traction force and cornering performance.

for teeth. In snow ice rally on snow and ice roads, stud pins are used to minimize grip on the ice to indicate tire grip. However, when the general tread rubber composition is used, the wear resistance and chip cut performance are remarkably degraded, and the stud pin that exhibits the tire grip is excessively generated and excessive movement during driving cannot be used as a general tread rubber composition.

Conventional patents related to tread rubber compositions for snow tires for general passenger cars (KR 2006-0028342), but does not meet the above requirements for the tread rubber composition for snow rally tires.

Accordingly, an object of the present invention is a tire that has high hardness and modulus while maintaining wear resistance and chip cut performance, and lowers heat generation of rubber and increases hardness and modulus to prevent movement and detachment of stud pins that may occur during driving. It is to provide a rubber composition for tread.

However, technical problems to be achieved by the present invention are not limited to the above-mentioned problems, and other technical problems will be clearly understood by the average technician from the following description.

In order to achieve the above object, the present invention with respect to 100 parts by weight of natural rubber, 50 to 80 parts by weight of carbon black; And 3 to 20 parts by weight of a novolak-based phenolic resin, wherein the carbon black has a pH of 7 to 10, an I ₂ adsorption of 115 to 135, a DBP adsorption of 105 to 120 cc / 100 g, and a tin strength of 115 to 115. 125, toluene coloring transmittance provides a rubber composition for tire treads, characterized in that 40 to 48%.

The rubber composition for tire treads according to the present invention has high hardness and modulus while maintaining wear resistance and chip cut performance, and lowers heat generation of rubber, and increases hardness and modulus, thereby causing movement and departure of the stud pin. Has the advantage of preventing.

The present invention applies carbon black and novolac-based phenolic resins satisfying specific conditions to raw rubber to prevent the departure of the rally stud pins during unpaved road driving and cultivation, and minimize the movement of the stud pins during driving, and at the same time wear resistance And it provides a rubber composition for the tire tread applicable to the snow rally tire mounted on the snow road and ice road racing car by improving the chip cut performance.

Hereinafter, the present invention will be described in more detail.

The present invention is a natural rubber raw material rubber; Carbon black; And it provides a rubber composition for tire tread comprising a novolak-based phenolic resin.

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The carbon black is contained in 50 to 80 parts by weight based on 100 parts by weight of the raw material rubber. If the content of the carbon black is less than 50 parts by weight, wear resistance is reduced, there is a problem that the initial departure of the stud pin and runaway occurs when running, if it exceeds 80 parts by weight there is a problem in dispersion and workability, brittle There is a problem that can occur.

The carbon black may have a pH of 7 to 10, an I ₂ adsorption of 115 to 135, a DBP adsorption of 105 to 120 cc / 100 g, a tint strength of 115 to 125, and a toluene coloring permeability of 40 to 48%.

When the pH is in the above range there is an advantage to shorten the initial vulcanization time, there is an advantage in the exothermic properties when the I ₂ adsorption is in the above range, easy to mix when the DBP adsorption is in the above range There is one advantage. In addition, when the tint strength is within the above range, reinforcing properties suitable for the present invention can be obtained, and when the toluene coloring transmittance is within the above range, there is an advantage in terms of dispersion. Carbon black according to the present invention can obtain a low heat generation characteristics and high reinforcement that satisfies all the above conditions.

In general, as a method of lowering the heat generation of rubber, carbon black is used as a filler to reduce specific surface area, but in this case, the wear resistance of the composition is lowered due to the use of carbon black having a small specific surface area, thereby reducing the overall tire. There is a problem that the life is reduced.

In addition, there is a method of blending a large amount of carbon black having a large specific surface area in the rubber composition, but in this case, carbon black having a large specific surface area has a problem of deterioration in durability due to deterioration of abrasion resistance or disadvantage of internal heat generation due to a large amount of use. have.

In the present invention, although the specific surface area of the carbon black is not large in a state, the carbon black having a high tint strength is used to reduce the wear resistance, chip cut performance, and the movement of the stud pin due to heat generated while driving and to prevent the stud pin from falling off. Effects can be obtained, and the use of a phenolic resin of Novolak system maintains high hardness and modulus, thereby minimizing the movement of the stud pin at the beginning of driving.

The novolak-based phenol resin is represented by the following Chemical Formula 1, and is included in an amount of 3 to 20 parts by weight based on 100 parts by weight of the raw material rubber. If the content of the novolak-based phenol resin is less than 3 parts by weight, the effect of increasing the hardness is not obtained, if it exceeds 20 parts by weight there is a problem that excessive hardness increase and crackability is lowered.

Specific examples of the novolak-based phenol resins include para-tertiary -butylphenol, para-tertiary-octylphenol, para-nonylphenol, formaldehyde, and copolymers thereof, but are not limited thereto. In addition, the novola-based phenolic resin can be easily purchased and used commercially, examples thereof include KOREFORTE 5211.

Novolak-based phenolic resins are known to be used in the bead filler of electric belts or tires in the domestic patent (KR 1999-0025415, KR 2000-0049368), but in the present invention, a novolak-based phenolic resin is added to the tread rubber composition. By applying it, the hardness and modulus can be improved to obtain the required characteristics for being applicable for snow ice rally tires.

The present invention may further comprise 7 to 15% by weight of hexamethylene tetramine as a curing agent based on 100% by weight of the novolak-based phenol resin. If the content of the hexamethylene tetramin is less than 7% by weight it is not possible to obtain an effect of preventing the strength decrease at high temperatures, when the content of more than 15% by weight has a problem that the scorch time is shortened.

Meanwhile, the rubber composition for tire treads according to the present invention may further include an additive. The additives typically include sulfur as a vulcanizing agent, zinc oxide as a vulcanizing agent, aromatic oil as a softener and processing aids, and N-cyclohexyl-2-benzothiazoylsulfonamide as a vulcanization accelerator (N). -cyclohexyl-2-benzothiazoyl sulfonamide (CBS) accelerator, and anti-aging agent.

The content of the additive can be easily adjusted according to the desired physical properties, for example, 1.4 parts by weight of normal tertbutyl-2-benzodiazyl sulfenamide as accelerator, 1.5 parts by weight of sulfur as vulcanizing agent, 2 parts by weight of stearic acid 3 parts by weight of zinc oxide may be used, and 2 parts by weight of normal 1,3-dimethybutyl normal phenyl paraffin phenylenediamine and 1 part of poly-2,2,4-trimethyl-1,2-dihydroquinoline as anti-aging agents 1 part by weight of waxy hydrocarbon may be used.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the present invention is not limited to the following examples.

[Examples 1 to 2 and Comparative Examples 1 to 5]

The compounding agent composition of the rubber composition was blended in the component ratios shown in Table 1 below to prepare test pieces of the rubber composition using a Banbury Mixer and an Open Mill.

Example Comparative example One 2 One 2 3 4 5 Natural Rubber (NR) 100 100 100 100 100 100 100 Carbon Black① 60 80 60 80 Carbon black② 0 0 60 60 80 Novolak-based phenolic resin ③ 10 5 0 0 0 10 5 Hexamethylene
Tetramine One 0.5 0 0 0 One 0.5 Stearic acid 2 2 2 2 2 2 2 Zinc oxide 3 3 3 3 3 3 3 Antioxidant ④ 2 2 2 2 2 2 2 Anti-aging agent⑤ One One One One One One One Antioxidant⑥ One One One One One One One Accelerator ⑦ 1.4 1.4 1.4 1.4 1.4 1.4 1.4 sulfur 1.5 1.5 1.5 1.5 1.5 1.5 1.5

(Unit: parts by weight)

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(1): Carbon black having pH of 7 to 10, I ₂ adsorption to 115 to 135, DBP adsorption to 105 to 120 cc / 100 g, tint strength of 115 to 125, and toluene coloring permeability of 48%.

②: carbon black with pH 7-10, I ₂ adsorption 115-135, DBP adsorption 100-120cc / 100g, tintstrength 130-140, toluene coloring permeability 90%

③: KOREFORTE 5211 (Schill)

④: normal 1,3-dimethybutyl normal phenyl paraffin phenylenediamine

⑤: poly-2,2,4-trimethyl-1,2-dihydroquinoline

⑥: Wax Hydrocarbon

⑦: Tetramethyl thiuram disulfide

The rubber specimens prepared according to Examples 1 to 2 and Comparative Examples 1 to 5 were measured for physical properties in the following manner according to ASTM-related regulations, and the results are shown in Table 2 below. Values shown in Table 2 are shown based on the value of Example 1 (100).

(1) The scorch time was measured by the pattern bismeter and measured from the minimum of the pattern to 5 points. The longer the time, the better the scorch stability.

(2) Modulus measurement was carried out with a tensile tester manufactured by Instron by cutting the specimen into a dumbbell shape. 300% modulus refers to the stress acting on a specimen when the specimen is stretched 300%.

(3) 0 ° C Tan δ is used as a substitute for braking performance of tires. Higher values indicate better performance. Tan δ of 60 ° C. is used as a substitute for tire rolling resistance, and the lower the value, the better the rolling resistance.

(4) Abrasion refers to Lambbourn abrasion, which represents the loss of worn rubber by rotating at a sliding ratio of 25% and a load of 1.5 kg at room temperature. The relative index indicated by the relative index indicates that the wear performance is excellent. Indicates.

(5) In the heat resistance test, the rubber test piece was subjected to a strain of 10 Hz and 1% at 60 ° C. to measure the viscous modulus and elastic modulus at this time. The value of δ was calculated.

The results measured by the Rheometrics tester are shown in Table 2 below.

Properties Example Comparative example One 2 One 2 3 4 5 Fairness 125 ℃ viscosity 83 84 72 83 73 80 87 Scotch time
(t5, min) 15.47 15.35 16.32 15.47 14.12 16.27 16.27 Seal
Properties Hardness
(hardness) 82 84 75 80 76 81 83 300% modulus (Kgf / ㎠) 214 225 186 208 191 203 211 % Elongation 379 330 403 321 407 397 387 The tensile strength
(Kgf / ㎠) 254 262 263 249 241 264 264 Viscoelastic 0 ℃ Tan δ 0.145 0.134 0.132 0.145 0.131 0.133 0.133 60 ℃ Tan δ 0.159 0.169 0.157 0.161 0.163 0.168 0.168 Wear resistance 100 102 93 90 95 101 101 Heat resistance 100 92 99 95 98 99 91

As shown in Table 2, when comparing the physical property test results of Examples 1 to 2 and Comparative Examples 1 to 5, the use of novolak-based phenolic resin increases the reinforcement of the rubber composition to increase the hardness and modulus It can be increased, and improved physical properties can be obtained in terms of wear resistance and heat resistance.

Therefore, the rubber composition prepared according to the present invention can provide a rubber composition for snow rally that can minimize the departure and movement of the stud pin by higher hardness and modulus than the conventional rubber composition.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (2)

Per 100 parts by weight of natural rubber, 50 to 80 parts by weight of carbon black; And 3 to 20 parts by weight of a novolak-based phenol resin, The carbon black has a tire tread having a pH of 7 to 10, an I ₂ adsorption of 115 to 135, a DBP adsorption of 105 to 120cc / 100g, a tint strength of 115 to 125, and a toluene coloring permeability of 40 to 48%. Rubber composition for The rubber composition for tire treads according to claim 1, further comprising 7 to 15 wt% of hexamethylene tetramin based on 100 wt% of the novolak-based phenol resin.