KR100333410B1 - Tire tread composition for truck-bus - Google Patents

Abstract

The present invention relates to a rubber composition for tire treads, 100 parts by weight of diene-based natural rubber; 35 to 55 parts by weight of carbon black having a nitrogen adsorption specific surface area of 95 to 150 m 2 / g and a DBP oil absorption of 90 to 130 ml / 100 g; 5-25 parts by weight of silica having a nitrogen adsorption specific surface area of 175 m 2 / g and a CTAB surface area of 166 m 2 / g; 2-6 parts by weight of rosin modified with terpene oil; 0.8 to 4 parts by weight of bis (3-triethoxy silyl propyl tetrasulfide) or mercapto propyl triethoxy silane as a coupling agent; 1 to 3 parts by weight of a cresol type alkyl phenol formaldehyde resin; 0.2 to 2 parts by weight of hexamethoxy methylmelamine as a crosslinking agent; And additives, which can simultaneously improve cutting resistance and durability on unpaved roads or damaged pavements, making it suitable for truck tread rubber.

Description

Tire tread composition for truck-bus

The present invention relates to a rubber composition of a tire tread for truck buses, and more particularly, to a rubber composition of a tire tread for truck buses that can simultaneously improve cutting resistance and durability on an unpaved road or a damaged pavement.

Truck bus tires are often used on unpaved roads, often resulting in chip-cut phenomena where the tread rubber is torn off, that is, when the rubber is released when the force is applied enough to puncture or crack the tread surface. External force such as sudden stop acts, causing tearing at right angles to the direction of force, resulting in the phenomenon of deviation.

The improvement of physical properties of the chip-cut phenomenon mainly uses reinforcement resin and small particle size carbon to increase the modulus and strength of rubber at low deformation, thus delaying the occurrence of cut when external impacts such as sharp stones are applied to the rubber. A technique was used to improve chip-cut performance by increasing the hysteresis of the rubber to delay the breakage of the rubber molecular chains at repeated stresses.

However, when the reinforcing resin is used, the reinforcing effect is very insignificant compared to the method of increasing the amount of reinforcing filler, and if a large amount is added to increase the effect, the heat generation of the rubber increases, adversely affecting the durability of the tire.

Accordingly, the present inventors have made efforts to simultaneously improve cutting resistance and durability on unpaved roads or damaged pavements, which are problems of conventional truck bus tread rubber compositions. As a result, cresol type alkylphenol formaldehyde resins and hexamethoxy methyl as crosslinking agents By using melamine, the present invention has been found that not only improves the modulus at low deformation, thereby improving cutting resistance, but also excellent heat generation characteristics, thereby simultaneously improving durability of the tire.

Accordingly, an object of the present invention is to provide a tire tread rubber composition for a truck bus that can simultaneously improve cutting resistance and durability on an unpaved road or a damaged pavement.

The tire tread rubber composition for truck buses of the present invention for achieving the above object is carbon black 35 having 100 parts by weight of diene-based natural rubber, nitrogen adsorption specific surface area of 95 to 150 m 2 / g and DBP oil absorption of 90 to 130 ml / 100 g. 55 parts by weight, nitrogen adsorption specific surface area of 175 m 2 / g and 5-25 parts by weight of silica having a CTAB surface area of 166 m 2 / g, bis (3-triethoxy silyl propyl tetrasulfide) or mercapto propyl triethoxy as coupling agents It is characterized by consisting of 0.8 to 4 parts by weight of silane, 1 to 3 parts by weight of a cresol type alkyl phenol formaldehyde resin, 0.2 to 2 parts by weight of hexamethoxy methylmelamine as a crosslinking agent, and an additive.

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

In the rubber composition of the tire tread of the present invention, as raw material rubber, a dark brown to yellow ribbed smoked sheet or technical standard rubber by an international standard sample may be used as the diene-based natural rubber.

On the other hand, the cutting resistance required in the tire tread of the present invention is affected by the degree of structural development of carbon black.

The carbon black used in the present invention has a DBP oil absorption amount of 90 to 130 ml / 100 g, which represents a carbon black structure. If the DBP oil absorption amount is less than 90 ml / 100 g, there is a problem that the rubber strength is weak and wear is reduced, and more than 130 ml / 100 g. Not only does the cut resistance to cut resistance be reduced, but also the cutting phenomenon is promoted along the shape of the developed structure.

In addition, the carbon black of the present invention has a nitrogen adsorption specific surface area of 95 to 150 m 2 / g. If the nitrogen adsorption specific surface area is less than 95 m 2 / g, the filling effect of the rubber is insufficient, and exceeds 130 m 2 / g. In this case, the rubber generates excessive heat, making it unsuitable for use.

On the other hand, the silica added in the present invention is to improve the cutting resistance by physical lubrication between the carbon black, nitrogen adsorption specific surface area of 175㎡ / g, CTAB surface area of 166㎡ / 5-25 Add in parts by weight.

And 0.8-4 weight part of bis (3-triethoxy silyl propyl tetrasulfite) or mercapto propyl triethoxy silane is used as a coupling agent of a silica and rubber | gum.

If less than 5 parts by weight of silica or less than 0.8 parts by weight of silica coupling agent is used, the heat generation is high and the durability is detrimental. If it exceeds 25 parts by weight of silica or 4 parts by weight of silica coupling agent, wear resistance is lowered.

At low deformation, 1 to 3 parts by weight of cresol-type alkylphenol formaldehyde resin is used to significantly improve modulus and rebound elasticity and to delay the occurrence of cuts when external force is applied to the tread surface in the unpaved furnace. Hexamethoxy is used as a crosslinking agent. 0.2 to 2 parts by weight of methylmelamine is used.

If the cresol type alkylphenol formaldehyde resin is used in less than 1 part by weight, it is not effective in increasing modulus and rebound elasticity at low deformation, and when it is more than 3 parts by weight, the Mooney viscosity of the unvulcanized rubber is high. Problems arise in machinability.

And in order to maintain the hysteresis of rubber suitably, the rosin modified with terpene oil is added in 2-6 weight part.

In addition, compounding agents added to conventional tire tread rubbers may be added. N-tert-butyl-2-benzolsulfenamide as a vulcanization accelerator, sulfur as a vulcanizing agent, stearic acid, zinc oxide, and N- as an antioxidant for rubber. 1,3-dimethylbutyl poly 2,2,4-trimethyl, 1,2-dihydro quinoline, waxy hydrocarbon, and the like can be used.

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

Examples 1-5 and Comparative Examples 1-4

A rubber sheet was prepared by blending a compounding agent as shown in Table 1 using a half-variable mixer.

Example Comparative example One 2 3 4 5 One 2 3 4 Diene Natural Rubber 100 100 100 100 100 100 100 100 100 Carbon black 45 45 45 45 45 45 45 45 45 Zinc oxide 4 4 4 4 4 4 4 4 4 Stearic acid 3 3 3 3 3 3 3 3 3 Anti-aging N-1,3-dimethylbutylpoly 2,2,4-trimethyl 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1,2-dihydroquinoneline One One One One One One One One One Waxy hydrocarbon One One One One One One One One One Suzy 4 4 4 4 4 4 4 4 4 RF-resin 1.5 3 One 1.5 1.5 - One 5 1.5 Silica 20 20 20 25 8 20 5 20 35 X50S 3.5 3.5 3.5 4 0.8 3.5 0.8 3.5 5.6 Hexamethoxy methyl melamine 0.8 2.0 0.6 0.8 0.8 - 0.6 2.5 0.8 Vulcanization accelerator One One One One One One One One One brimstone 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 Diene natural rubber: Dark brown to yellow rib smoke sheet carbon black according to international standard sample: Carbon black resin with nitrogen adsorption specific surface area of 95 to 150 m2 / g and DBP oil absorption of 90 to 130 ml / 100 g: Molecular weight: 3,000 A mixture of rosin + C9 petroleum resin acid anhydride + nylon residue oil + toll rosin oil modified with terpene oil having a softening point of 90 to 120 DEG C, a specific gravity of 1.0 to 1.2 and an acid value of 50 or more; Alkylphenol formaldehyde resin (trade name: SUMIKANOL 610) Silica: Silica with nitrogen adsorption specific surface area of 175 m 2 / g, CTAB surface area of 166 m 2 / g

Experimental Example

After preparing the test specimens by vulcanizing the rubber sheet obtained according to the above Examples and Comparative Examples for 30 minutes in a vulcanization press at 150 ° C., modulus, viscoelasticity, cutting resistance, and abrasion resistance were measured. The MV2000 manufactured by Monsanto was measured and the results are shown in Table 2 below.

Specifically, the Mooney viscosity was measured at 125 ℃ using the MV2000 manufactured by Monsanto, when the Mooney viscosity exceeds a certain level it is difficult to process during compounding and extrusion occurs when the actual tire production does not occur.

Modulus measurement was carried out with a tensile tester (Model 4502) manufactured by Instron by cutting the specimen into a dumbbell shape. Modulus refers to the stress value at each elongation, and 50% M refers to the stress acting on the specimen when the specimen is stretched 50%.

The dynamic viscoelasticity of rubber is the loss modulus (G '') and the storage modulus among the dynamic viscoelastic properties obtained when the specimen is made rectangular (10mm × 30 × 2.5mm) and subjected to torsional strain at a frequency of 10 Hz and 0.5% of strain. G ') value was measured and the viscoelastic value was calculated (tanδ = G' '/ G'). The higher the tanδ value measured at 60 ° C, the higher the heat generation.

Abrasion resistance (rambon wear performance test) is to rotate the disk-shaped abrasive stone and the specimen on the disk independently, and to drop the silicon carbide between the pressed abrasive stone and the specimen to prevent the wear surface of the specimen to adhere to the abrasive stone, It is a measure of the wear loss of a specimen caused by the difference in surface speed between the specimen and the specimen. The measurement result of Table 2 is the value indicated by exponentially the value of Example 1 to 100, the higher the number, the better the wear resistance.

Lastly, the cut resistance is an impact cut test for evaluating the cut resistance on the unpaved road. The test blade is made in the shape of a rectangle (10cm × 10cm × 4cm) and the striking blade is needle-shaped. The depth of penetration of the striking penetrating specimen was measured by free fall on the specimen at the height of. The smaller the penetration depth, the better the cut resistance.

Example Comparative example One 2 3 4 5 One 2 3 4 50% M (kg / ㎠) 24 27 22 25 23 17 20 29 25 Wear resistance 100 99 101 100 102 101 98 97 90 tanδ (60 ° C) 0.105 0.104 0.106 0.103 0.108 0.113 0.112 0.106 0.100 Cutting resistance (mm) 12.2 11.2 12.8 12.2 12.0 18.3 13.2 11.4 12.5 Mooney viscosity (lb-in) 75 80 71 76 73 68 70 100 85

From the results of Table 2, the rubber using the reinforcing resin, RF-resin and hexamethoxy methylmelamine (Examples 1 to 5) has a large increase in the modulus of the rubber in the low deformation region compared to the case of Comparative Example 1 which is not It can be seen that the cutting resistance is improved.

In Comparative Example 2, which is the case where 5 parts by weight of silica and 0.8 parts by weight of silica coupling agent are applied, the exothermic property is disadvantageous, which adversely affects the durability of the tire.

In Comparative Example 3, the RF-resin was used in an amount of more than 3 parts by weight and 5 parts by weight. Compared to Examples 1 to 5, the modulus of the rubber was increased, but the Mooney viscosity was greatly increased. Can't.

Comparative Example 4 is a case in which silica was added in an amount of 35 parts by weight exceeding 25 parts by weight, and the exothermic properties of the rubber were more favorable than those in Example 1, but the wear resistance was greatly decreased.

As described in detail above, according to the present invention, a diene-based natural rubber is used as a raw material rubber, and a rosin modified by carbon black, silica, silica coupling agent, cresol type alkylphenol formaldehyde resin, terpene oil, In the case of a rubber composition made by adding hexamethoxymethylmelamine as a crosslinking agent, it is suitable as a rubber for truck tread tires by simultaneously improving cutting resistance and durability on unpaved roads or damaged pavements.

Claims (1)

100 parts by weight of diene-based natural rubber; 35 to 55 parts by weight of carbon black having a nitrogen adsorption specific surface area of 95 to 150 m 2 / g and a DBP oil absorption of 90 to 130 ml / 100 g; 5-25 parts by weight of silica having a nitrogen adsorption specific surface area of 175 m 2 / g and a CTAB surface area of 166 m 2 / g; 2-6 parts by weight of rosin modified with terpene oil; 1 to 3 parts by weight of a cresol type alkyl phenol formaldehyde resin; 0.8 to 4 parts by weight of bis (3-triethoxy silyl propyl tetrasulfide) or mercapto propyl triethoxy silane as a coupling agent; 0.2 to 2 parts by weight of hexamethoxy methylmelamine as a crosslinking agent; And a rubber tread for truck buses made of an additive.