KR20160004570A - Rubber composition for tire tread and tire manufactured by using the same - Google Patents

Abstract

The present invention relates to a rubber composition for a tire tread, and to a tire produced by using the same. The rubber composition for the tire tread comprises: 20-120 parts by weight of silica; and 1-30 parts by weight of a disulfide-based silane coupling agent, in which content of sulfur is 15-20 wt%, and the molecular weight is 480-520 g/mol, with respect to 100 parts by weight of raw rubber containing 40-70 parts by weight of natural rubber and 20-30 parts by weight of epoxidized natural rubber. Accordingly, coherence and mixing properties of the natural rubber and silica increase by keeping a scorch generation temperature high. As a result, rolling resistance, braking force on a wet surface of a road, and wear resistance can be improved harmoniously.

Description

TECHNICAL FIELD [0001] The present invention relates to a tire tread rubber composition, and a tire produced using the same. BACKGROUND OF THE INVENTION [0002]

The present invention relates to a rubber composition for a tire tread which can maintain a high scorch temperature to improve bonding force and mixing property between silica and natural rubber and consequently improve the balance of rolling resistance, wet road surface braking force and abrasion resistance of a tire, And a tire manufactured using the same.

As European (EU) labeling and minimum regulatory applications have been applied to truck-bus tires, fuel consumption and wet road surface braking power of the vehicle have become essential elements as well as the tire wear performance that is usually required.

The tread of a tire, which is a part of the vehicle that is in direct contact with the ground, greatly dominates the wear, fuel economy and wet road surface braking performance of the tire. However, since the performance of each of the abrasion, fuel consumption, and wet road surface braking force has a trade-off characteristic due to the characteristics of the tire tread, it is most important that the performance is balanced.

In the case of truck-bus tires, a rubber composition containing mainly natural rubber and carbon black as a filler was used because durability according to running characteristics under high load conditions and abrasion performance directly related to tire life are more important. However, the rubber composition containing the natural rubber and the carbon black as the filler alone can not satisfy both the rotational resistance and the wet road surface braking performance.

In order to improve the fuel consumption and the wet road surface braking force of the rubber composition for tire tread, silica is used as a reinforcing filler. However, in the case of silica, the hydrophilic silanol group (-SiOH) . However, since the polarity of such silica lowers the mixing property with rubber, the rubber composition containing silica as a filler reacts with the silanol group present on the surface of the silica to change the surface chemical property of the silica to nonpolar, A silane coupling agent should be used together.

However, in the case of a commonly used tetrasulfide-based silane coupling agent, a scorch occurs when the rubber composition is mixed at a certain temperature or more, so the temperature must be kept constant during mixing. In order to ensure the durability of a truck-bus tire, a certain amount or more of natural rubber should be applied. In this case, the mixing temperature condition of the natural rubber can not be satisfied, and as a result, mixing with a silica filler is difficult.

Korean Patent Publication No. 2006-0102731 (published on September 28, 2006)

Disclosure of the Invention The present invention has been made to overcome the above problems and to improve the bonding force and mixing property between silica and natural rubber by keeping the scorch generating temperature high and consequently to improve the rolling resistance, And a rubber composition for a tire tread.

Another object of the present invention is to provide a tire produced by using the rubber composition for a tire tread.

In order to achieve the above object, the rubber composition for a tire tread according to an embodiment of the present invention comprises 100 parts by weight of a raw material rubber comprising 40 to 75 parts by weight of a natural rubber and 20 to 30 parts by weight of an epoxidized natural rubber, To 120 parts by weight of a silane coupling agent and 1 to 30 parts by weight of a silane coupling agent, wherein the silane coupling agent is a disulfide compound having a sulfur content of 15 to 20% by weight and a molecular weight of 480 to 520 g / mol.

In the raw material rubber, the epoxidized natural rubber may have a glass transition temperature (Tg) of -50 to -40 캜, a pattern viscosity of 60 to 80, and an epoxidation degree of 5 to 50 mol%.

Further, the raw material rubber further contains a neodymium butadiene rubber having a weight average molecular weight of 7 x 10 ⁵ to 9.2 x ^{10 5} g / mol and a molecular weight distribution of 3.2 to 3.5 in an amount of 10 to 25 wt% based on the total weight of the raw rubber .

In the rubber composition for a tire tread, the silica has an adsorption specific surface area of cetyl trimethyl ammonium bromide (CTAB) of 105 to 175 m 2 / g and a BET (Brunauer-Emmett-Teller) Lt; ² > / g.

The rubber composition for a tire tread has an iodine adsorption of 50 to 170 mg / g and an oil adsorption specific surface area of 85 to 129 cc / 100 g, an oil absorption of dibutyl phthalate (DBP) of 100 to 160 cc / 100 g and a tint (TINT) value of 110 To 157 carbon black in an amount of 5 to 35 parts by weight based on 100 parts by weight of the raw rubber.

According to another embodiment of the present invention, there is provided a rubber composition comprising 20 to 120 parts by weight of silica, 20 to 120 parts by weight of sulfur, and 10 to 30 parts by weight of sulfur, By weight of a disulfide compound having a molecular weight of 480 to 520 g / mol, based on the total weight of the rubber composition.

In the above production process, the mixing step of the respective components is carried out in such a manner that the iodine adsorption value is 50 to 170 mg / g, the oil adsorption specific surface area is 85 to 129 cc / 100 g, the DBP oil absorption amount is 100 to 160 cc / 100 g, 157 is added in an amount of 5 to 35 parts by weight based on 100 parts by weight of the raw rubber, and the mixture is mixed while maintaining the temperature at 155 to 180 캜.

A tire according to another embodiment of the present invention is manufactured using the rubber composition for a tire tread.

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

The present invention uses a silane coupling agent capable of improving the bonding force and mixing property between silica and natural rubber while maintaining the scorch-generating temperature at a high level in the production of a rubber composition for a tire tread including silica as a reinforcing filler together with natural rubber In addition, by using epoxidized natural rubber to facilitate mixing of natural rubber and silica and to maintain wet road surface braking performance, it is possible to improve tire rotation resistance, fuel consumption characteristics, wet road surface braking force and abrasion resistance with good balance .

That is, the rubber composition for a tire tread according to an embodiment of the present invention comprises 20 to 120 parts by weight of silica with respect to 100 parts by weight of a raw rubber comprising 40 to 75 parts by weight of a natural rubber and 20 to 30 parts by weight of an epoxidized natural rubber And 1 to 30 parts by weight of a disulfide-based silane coupling agent having a sulfur content of 15 to 20% by weight and a molecular weight of 480 to 520 g / mol.

In the raw material rubber, the natural rubber (NR) serves to improve the tensile strength and the frictional resistance of the tire rubber composition, and can be used without particular limitation as long as it is usually used in a tire rubber composition. Specifically, the natural rubber may be a modified natural rubber except general natural rubber or epoxidized natural rubber.

The natural rubber includes cis-1,4-polyisoprene as a main component, but may also include trans-1,4-polyisoprene depending on required characteristics. Therefore, in addition to natural rubber containing cis-1,4-polyisoprene as a main component, natural rubber including trans-1,4-isoprene as a main component, such as balata, Rubber may also be included.

The modified natural rubber means that the natural rubber is denatured or purified. Examples of the modified natural rubber include deproteinized natural rubber (DPNR), hydrogenated natural rubber, and the like.

On the other hand, in the raw material rubber, the epoxidized natural rubber (ENR) is an epoxidized unsaturated double bond of a natural rubber (NR). The epoxidized natural rubber is an environmentally friendly, polar epoxy group, Has a high transition temperature (Tg), and is excellent in mechanical strength and abrasion resistance. Also, when silica is used as the reinforcing filler, the epoxy group of the epoxidized natural rubber reacts with the silanol group on the silica surface to increase the dispersibility of the silica, thereby improving the mechanical strength and abrasion resistance of the rubber composition without lowering the wet road surface braking performance .

Specifically, the epoxidized natural rubber may preferably have an epoxidation degree of 5 to 50 mol%. The degree of epoxidation refers to the number of epoxidized double bonds / (number of double bonds before epoxidation). If the degree of epoxidation of the epoxidized natural rubber is less than 5 mol%, gas permeability may increase. If the epoxidized natural rubber exceeds 50 mol%, workability and adhesiveness may be deteriorated.

The epoxidized natural rubber preferably satisfies the above-mentioned degree of epoxidation, has a glass transition temperature (Tg) of -50 to -40 캜, and has a pattern viscosity of 60 to 80. If the above-mentioned glass transition temperature condition is not satisfied or the pattern viscosity range condition is not satisfied, there is a possibility that the endothelial property, workability and adhesiveness of the rubber composition are lowered.

The epoxidized natural rubber preferably has an epoxidation degree of 20 to 25 mol%, a glass transition temperature (Tg) of -50 to -40 DEG C, and a pattern It is more preferable that the viscosity is 60 to 70.

The above-mentioned epoxidized natural rubber (ENR) may be commercially available or may be an epoxidized natural rubber (NR). A method of epoxidizing a natural rubber is not particularly limited, and a conventional epoxidation method such as a chlorohydrin method, a direct oxidation method, a hydrogen peroxide method, an alkyl hydroperoxide method, a peracid method and the like can be used. For example, in the case of the over-acid method, the reaction can be carried out by reacting natural rubber with organic acids such as peracetic acid and formic acid.

The raw rubber containing the natural rubber and the epoxidized natural rubber may include 40 to 75 parts by weight of the natural rubber and 20 to 30 parts by weight of the epoxidized natural rubber. If the content of the natural rubber is less than 40 parts by weight or exceeds 75 parts by weight, the tensile strength and the frictional resistance may be lowered. If the content of the epoxidized natural rubber is less than 20 parts by weight or more than 30 parts by weight There is a possibility that the workability and the dispersibility of silica are lowered. Considering the effect of improving the tensile strength and the frictional resistance in using natural rubber and the remarkable effect of improving the dispersibility of silica according to the use of epoxidized natural rubber, the raw rubber is composed of 50 to 70 parts by weight of natural rubber and 20 to 70 parts by weight of epoxidized natural rubber 20 By weight to 25 parts by weight.

The raw material rubber may further include neodymium butadiene rubber (Nd-BR).

The neodymium butadiene rubber (Nd-BR) is a butadiene rubber prepared by using neodymium (Nd) catalyst and has a molecular weight distribution as compared with cobalt butadiene rubber (Co-BR) or nickel butadiene rubber Because of the narrow and low branching degree, that is, the linearity of the molecular chain is high, it is possible to compensate for the decrease in abrasion resistance according to the use of silica and to improve the fuel consumption performance.

Specifically, the neodymium butadiene rubber may have a weight average molecular weight (Mw) of 7 × ^{10 5} to 9.2 × 10 ⁵ g / mol and a molecular weight distribution (Mw / Mn) of 3.2 to 3.5.

More specifically, the neodymium butadiene rubber may have an average molecular weight of 8.0 to 9.2x10 ⁵ g / mol, a molecular weight distribution (Mw / Mn) of 3.3 to 3.5, and a pattern viscosity of 40 to 50. By using the neodymium butadiene rubber having a high molecular weight and a high molecular weight distribution with a narrow molecular weight distribution as described above, compared with the nickel-catalyzed butadiene rubber having a molecular weight distribution of 2.5 to 3.5 used in a rubber composition for a tire, The performance can be further improved.

The neodymium butadiene rubber may be included in an amount of 10 to 25% by weight based on the total weight of the raw rubber, from the viewpoint of improving the fuel-combustion performance.

If the content of the neodymium butadiene rubber is less than 10% by weight, the effect of improving the wear performance by the use of the neodymium butadiene rubber is insignificant. If the content exceeds 25% by weight, the workability and braking performance may be deteriorated. Also, considering the remarkable improvement effect, it is more preferable that the neodymium butadiene rubber is contained in an amount of 20 to 25% by weight based on the total weight of the starting rubber.

The rubber composition for a tire tread according to the present invention includes silica as a reinforcing filler together with the raw rubber described above.

The silica can be used as long as it is generally used in a rubber composition for tire tread. Specifically, it can be produced by a wet process or a dry process such as a precipitated silica, and commercially available products include Ultrasil 7000Gr (Evonik) Zeosil 1165MP ™ (manufactured by Rhodia), Zeosil 200MP ™ (manufactured by Rhodia), Zeosil 195HR ™ (manufactured by Rhodia), and the like can be used.

Considering the effect of improving the reinforcing performance of the rubber composition for tire tread of silica and the workability, the silica has an adsorption specific surface area of cetyl trimethyl ammonium bromide (CTAB) of 105 to 175 m 2 / g and a BET Brunauer-Emmett-Teller) specific surface area of 140 to 250 m ² / g.

The CTAB adsorption specific surface area and the BET specific surface area condition of the silica should satisfy both the BET specific surface area requirement and the CTAB adsorption specific surface area of less than 105 m2 / g, The reinforcing performance may be deteriorated, while when it exceeds 175 m 2 / g, the workability of the rubber composition may be deteriorated. When the BET specific surface area of silica is less than 140 m ² / g, the reinforcing property is lowered. When the BET specific surface area of silica is more than 250 m ² / g, the physical properties and workability of the tire are lowered .

The silica has a CTAB adsorption specific surface area of 150 to 170 m ² / g and a BET specific surface area of 150 to 210 m ² / g. The silica has a high porosity on the surface of silica and a small interfacial interaction, And may be more preferable.

The silica satisfies the above-described CTAB and BET conditions, and has a nitrogen surface area per gram (N 2 SA) of 95 to 185 m 2 / g, or 155 to 180 m 2 / g, It may be more preferable in terms of improvement effect.

The silica may be included in an amount of 20 to 120 parts by weight based on 100 parts by weight of the raw rubber, more preferably 50 to 80 parts by weight. If the content of the silica is less than 20 parts by weight, the strength of the rubber may not be improved and the braking performance of the tire may be deteriorated. If the content of the silica exceeds 120 parts by weight, the wear performance may be deteriorated.

Typically, silica is chemically bonded to the rubber while being modified to be organophilic in the rubber through reaction with a silane coupling agent. When the surface chemical properties of the silica are modified, the movement of the silica in the rubber is restricted, thereby lowering the hysteresis and consequently lowering the heat generation and rotation resistance of the rubber composition. However, if silica is not sufficiently dispersed in the rubber, it is difficult to lower the heat generation and rotation resistance, and the wear resistance may be lowered.

Thus, the rubber composition for tire tread has a disulfide-based silane coupling agent capable of reacting with the silanol group of the above-mentioned silica to change the surface chemical characteristic thereof, thereby facilitating mixing of silica and rubber and improving the fuel- .

Specifically, the disulfide-based silane coupling agent may preferably be a disulfide compound having a sulfur content of 15 to 20% by weight and a molecular weight of 480 to 520 g / mol. By using a disulfide-based compound in which the content of sulfur in the molecule and the molecular weight thereof are optimized as the silane coupling agent, the scorch-generating temperature can be maintained at a high level, thereby remarkably improving the low fuel consumption and durability of the tire. However, when the sulfur content in the disulfide compound is less than 15 wt% or more than 20 wt%, the effect of improving the dispersibility to silica is insignificant. When the molecular weight is less than 480 g / mol or more than 520 g / mol, It is not preferable because there is a fear of occurrence.

More specifically, a disulfide compound satisfying the above sulfur content and weight average molecular weight range conditions can be directly prepared and used, or commercially available such as Si75 ( ^R ), Evonik ( ^R ), Si266 ( ^R ), Evonik).

The disulfide silane coupling agent may be included in an amount of 1 to 30 parts by weight based on 100 parts by weight of the starting rubber. When the content of the disulfide-based silane coupling agent is less than 1 part by weight, the improvement effect of using the disulfide-based silane coupling agent is insignificant. When the amount exceeds 30 parts by weight, the interaction between silica and rubber is too strong, The performance may be significantly deteriorated. If the coupling agent not reacted with silica remains in the rubber composition, the physical properties of the rubber composition may be deteriorated.

The rubber composition for a tire tread according to the present invention having the above-described structure may further comprise carbon black.

The carbon black can prevent degradation of abrasion performance according to use of the silica, and can improve the appearance characteristic of the tire tread by increasing coloring degree by black coloring. In addition, the mixing temperature is higher than that in the case of using silica alone, and it is possible to prevent the scorch phenomenon and the weakening of the bond between the silica and the silane coupling agent.

Specifically, the carbon black has an iodine adsorption value of 50 to 170 mg / g, an oil adsorption specific surface area of 85 to 129 cc / 100 g, an oil absorption of dibutyl phthalate (DBP) of 100 to 160 cc / 100 g and a TINT value 110 to 157. < / RTI >

The iodine adsorption value, the oil adsorption specific surface area, the DBP oil absorption amount, and the TINT value of the carbon black are satisfied simultaneously. For example, the iodine adsorption value of the carbon black is set to satisfy the following requirements If it exceeds 170 cc / 100 g, the workability of the rubber composition may be deteriorated. On the other hand, if the iodine adsorption value is less than 50 cc / 100 g, the reinforcing performance by the carbon black as the filler may be deteriorated. In addition, wear and appearance performance are improved in the case of carbon black in which the oil adsorption specific surface area is more than 129 cc / 100 g, but the relatively high level of modulus in the strain region is relatively high. have.

The carbon black has an iodine adsorption value of 135 to 147 mg / g, an oil adsorption specific surface area of 97 to 107 cc / 100 g, a DBP oil absorption of 120 to 145 cc / 100 g, and a tint TINT) value of 125 to 132 may be more preferable.

The carbon black may be included in an amount of 5 to 35 parts by weight based on 100 parts by weight of the raw rubber. When the content of carbon black is less than 5 parts by weight, there is a fear of a decrease in abrasion resistance, a scorch phenomenon, and a weakening bond between silica and a silane coupling agent. When the content of carbon black exceeds 35 parts by weight, There is a fear that the performance may deteriorate.

In addition to the above-mentioned components, the rubber composition for a tire tread according to the present invention is optionally used for improving the physical properties of rubber compositions for tire treads, such as vulcanizing agents, vulcanization accelerators, vulcanization accelerators, softening agents, The additive may be added singly or in combination of two or more.

Specifically, as the vulcanizing agent, a metal oxide such as a sulfur vulcanizing agent, an organic peroxide, a resin vulcanizing agent, or a magnesium oxide can be used.

The sulfur vulcanizing agent is an inorganic vulcanizing agent such as powder sulfur (S), insoluble sulfur (S), precipitated sulfur (S), colloid sulfur, etc., tetramethylthiuram disulfide (TMTD) Organic vulcanizing agents such as tetraethyltriuram disulfide (TETD) and dithiodimorpholine can be used. In addition, vulcanizing agents which produce elemental sulfur or sulfur such as amine disulfide, polymer sulfur Etc. may be used.

Also, the organic peroxide is selected from the group consisting of benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5- Butylperoxybenzene, di-t-butylperoxy-diisopropylbenzene, t-butylperoxybenzene, 2,4-dichlorobenzoylperoxide, 1,1-dibutylperoxy- 3,3,5-trimethylsiloxane, or n-butyl-4,4-di-t-butylperoxyvalerate.

It is preferable that the vulcanizing agent is included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the raw material rubber in view of a vulcanization effect which is less sensitive to heat and chemically stable.

The vulcanization accelerator refers to an accelerator that promotes the vulcanization rate or accelerates the retardation in the initial vulcanization step. Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamate, aldehyde-amine, aldehyde-ammonia, imidazoline, Or a combination thereof.

Examples of the sulfenamide type vulcanization accelerator include N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), N-tert-butyl-2-benzothiazyl sulfenamide (TBBS), N, N-dicyclohexyl -2-benzothiazyl sulfenamide, N-oxydiethylene-2-benzothiazyl sulfenamide, N, N-diisopropyl-2-benzothiazole sulfenamide, and combinations thereof Based compound can be used.

Examples of the thiol-based vulcanization accelerator include 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide (MBTS), sodium salt of 2-mercaptobenzothiazole, zinc salt of 2-mercaptobenzothiazole , A copper salt of 2-mercaptobenzothiazole, a cyclohexylamine salt of 2-mercaptobenzothiazole, 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- Ethyl 4-morpholinothio) benzothiazole, and combinations thereof. The thiazole-based compound may be used alone or in combination of two or more thereof.

Examples of the thiuram-based vulcanization accelerator include tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylthiuram disulfide, dipentamethylthiuram monosulfide, dipentamethylene Any one of thiuram-based compounds selected from the group consisting of thiuram tetrasulfide, dipentamethylenethiuram hexasulfide, tetrabutylthiuram disulfide, pentamethylenethiuram tetrasulfide, and combinations thereof can be used.

Examples of the thiourea vulcanization accelerator include thiourea compounds selected from the group consisting of thiacarbamide, diethyl thiourea, dibutyl thiourea, trimethyl thiourea, diorthotolyl thiourea, and combinations thereof. Compounds may be used.

Examples of the guanidine-based vulcanization accelerator include guanidine-based compounds selected from the group consisting of diphenyl guanidine, diorthotolyl guanidine, triphenyl guanidine, orthotolyl biguanide, diphenyl guanidine phthalate, and combinations thereof .

Examples of the dithiocarbamate-based vulcanization accelerator include zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, Zinc dibutyldithiocarbamate, zinc diamidithiocarbamate, zinc dipropyldithiocarbamate, complexation of zinc with piperidinedithiocarbamate and piperidine, zinc hexadecylisopropyldithiocarbamate, octadecyl Isopropyl dithiocarbamic acid zinc zinc dibenzyldithiocarbamate, sodium diethyldithiocarbamate, penta methylenedithiocarbamate, sodium selenium dimethyldithiocarbamate, diethyldithiocarbamate, sodium diethyldithiocarbamate, Cadmium dithiocarbamate, and combinations thereof. The dithiocarbamic acid-based compound may be used alone or in combination of two or more thereof.

Examples of the aldehyde-amine-based or aldehyde-ammonia-based vulcanization accelerator include aldehyde selected from the group consisting of acetaldehyde-aniline reactant, butylaldehyde-aniline condensate, hexamethylenetetramine, acetaldehyde- -Amine-based or aldehyde-ammonia-based compounds may be used.

As the imidazoline-based vulcanization accelerator, for example, an imidazoline-based compound such as 2-mercaptoimidazoline can be used. Examples of the xanthate vulcanization accelerator include xanthates such as zinc dibutylxanthogenate Compounds may be used.

The vulcanization accelerator may be included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the raw material rubber in order to maximize productivity improvement and rubber property enhancement through vulcanization speed promotion.

The vulcanization accelerating assistant may be any one selected from the group consisting of an inorganic vulcanization accelerator aid, an organic vulcanization accelerator aid, and a combination thereof, which is used in combination with the vulcanization accelerator to complete the promoting effect thereof .

As the inorganic vulcanization accelerating aid, any one selected from the group consisting of zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide and combinations thereof may be used have. Examples of the organic-based vulcanization accelerator include stearic acid, zinc stearate, palmitic acid, linoleic acid, oleic acid, lauric acid, dibutyl ammonium oleate, derivatives thereof, You can use one.

In particular, the zinc oxide and the stearic acid may be used together as the vulcanization accelerating assistant. In this case, the zinc oxide is dissolved in the stearic acid to form an effective complex with the vulcanization accelerator to produce favorable sulfur during the vulcanization reaction Thereby facilitating the crosslinking reaction of the rubber.

When zinc oxide and stearic acid are used together, it is preferable to use 1 to 10 parts by weight per 100 parts by weight of the raw material rubber in order to serve as an appropriate vulcanization accelerating auxiliary.

The softening agent is added to the rubber composition in order to impart plasticity to the rubber to facilitate processing or to reduce the hardness of the vulcanized rubber, and means a processing oil used for rubber compounding or rubber production. The softener may be selected from the group consisting of petroleum oils, vegetable oils, and combinations thereof, but the present invention is not limited thereto.

The petroleum-based oil may be selected from the group consisting of paraffinic oil, naphthenic oil, aromatic oil, and combinations thereof.

Examples of the paraffin oil include P-1, P-2, P-3, P-4, P-5 and P-6 of Mychang Oil Co., N-1, N-2 and N-3 of Kokai Co., Ltd., and representative examples of the aromatic oils include A-2 and A-3 of Mingchang Oil Co.,

However, it is known that when the content of Polycyclic Aromatic Hydrocarbons (hereinafter referred to as 'PAHs') contained in the aromatic oil is 3 wt% or more together with the increase of environmental consciousness, Treated distillate aromatic extract (TDAE) oil, mild extraction solvate (MES) oil, residual aromatic extract (RAE) oil or heavy naphthenic oil.

Particularly, the oil used as the softener preferably has a total content of PAHs components of 3% by weight or less, a kinematic viscosity of 95 ° C or more (210 ° F. SUS), an aromatic component in the softener of 15 to 25% A TDAE oil having 27 to 37% by weight of a component and 38 to 58% by weight of a paraffin component can be preferably used.

The TDAE oil is advantageous for environmental factors such as the low temperature characteristics of the tire tread including the TDAE oil and the possibility of the cancer induction of PAHs while improving the fuel consumption performance.

Examples of the vegetable oils include vegetable oils such as castor oil, cottonseed oil, linseed oil, canola oil, soybean oil, palm oil, palm oil, peanut oil, pine oil, pine tar, tall oil, cone oil, rice bran oil, safflower oil, sesame oil, , Jojoba oil, macadamia nut oil, four flower oil, tung oil, and combinations thereof.

It is preferable that the softening agent is used in an amount of 1 to 10 parts by weight based on 100 parts by weight of the raw material rubber in order to improve workability of the raw rubber.

The antioxidant is an additive used to stop the chain reaction in which the tire is autoxidized by oxygen. As the anti-aging agent, any one selected from the group consisting of an amine type, a phenol type, a quinoline type, an imidazole type, a carbamic acid metal salt, a wax and a combination thereof can be appropriately selected and used.

Examples of the amine type antioxidant include N-phenyl-N '- (1,3-dimethyl) -p-phenylenediamine, N- (1,3-dimethylbutyl) -N'- Phenyl-N'-isopropyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, -Cyclohexyl p-phenylenediamine, N-phenyl-N'-octyl-p-phenylenediamine, and combinations thereof.

Examples of the phenolic antioxidant include phenol-based 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), 2,2'- isobutylidene- Di-t-butyl-p-cresol, and combinations thereof.

As the quinoline antioxidant, 2,2,4-trimethyl-1,2-dihydroquinoline and its derivatives can be used. Specifically, 6-ethoxy-2,2,4-trimethyl- Dihydroquinoline, 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline, 6-dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline and combinations thereof Any one selected from the group can be used.

As the wax, waxy hydrocarbons can be preferably used.

Considering the conditions such that the antioxidant has a high solubility in rubber, a low volatility, an inertness to rubber, and no inhibition of vulcanization, it is preferable that the antioxidant is used in an amount of 0.1 to 10 parts by weight, By weight.

The pressure-sensitive adhesive further improves the tack performance between the rubber and the rubber and improves the physical properties of the rubber by improving the mixing properties, dispersibility and processability of other additives such as fillers.

As the pressure-sensitive adhesive, a natural resin-based pressure-sensitive adhesive such as a rosin-based resin or a terpene-based resin and a synthetic resin-based pressure-sensitive adhesive such as a petroleum resin, a coal tar, or an alkylphenolic resin can be used.

The rosin-based resin may be any one selected from the group consisting of rosin resins, rosin ester resins, hydrogenated rosin ester resins, derivatives thereof, and combinations thereof. The terpene resin may be any one selected from the group consisting of terpene resin, terpene phenol resin, and combinations thereof.

Wherein the petroleum resin is selected from the group consisting of an aliphatic resin, an acid-modified aliphatic resin, an alicyclic resin, a hydrogenated alicyclic resin, an aromatic (C9) resin, a hydrogenated aromatic resin, a C5-C9 copolymer resin, a styrene resin, And a combination thereof.

The coal tar may be a coumarone-indene resin.

The alkylphenol resin may be a p-tert-alkylphenol formaldehyde resin and the p-tert-alkylphenol formaldehyde resin may be a p-tert-butyl-phenol formaldehyde resin, p-tert- And a combination thereof.

The pressure-sensitive adhesive may be included in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the raw material rubber. If the amount of the pressure-sensitive adhesive is less than 0.5 parts by weight based on 100 parts by weight of the raw material rubber, the adhesion performance is poor. If the amount is more than 10 parts by weight, rubber properties may be deteriorated.

More specifically, the rubber composition for a tire tread further comprises 0.5 to 5 parts by weight of a vulcanizing agent, 0.1 to 5 parts by weight of a vulcanization accelerator, 1 to 10 parts by weight of a vulcanization accelerator, and 1 to 5 parts by weight of a softening agent based on 100 parts by weight of the raw rubber can do.

The rubber composition for a tire tread may be prepared by mixing the above-mentioned components according to a conventional method. Specifically, during the finishing step in which the first step of thermomechanical processing or kneading and the crosslinking system are mixed at a maximum temperature of 110 to 190 캜, preferably at a high temperature of 150 to 180 캜, typically less than 110 캜, And a second step of mechanical treatment at a low temperature of 40 to 100 DEG C in a two-step continuous process.

In the case of using the carbon black in the production of the rubber composition for a tire tread, mixing the above-mentioned components while maintaining the temperature at 155 to 180 ° C is more effective in terms of abrasion resistance performance, LRR and wet performance .

The rubber composition for a tire tread produced by the above-described method has a high scorch-generating temperature to improve the bonding force and the mixing property between silica and natural rubber, and as a result, the rotation resistance of the tire, the wet road surface braking force and the wear resistance performance Balance can be improved better. Accordingly, the rubber composition for a tire tread is not limited to a tread (a tread cap and a tread base), and may be included in various rubber components constituting the tire. Said rubber components include sidewalls, sidewall inserts, apex, chafer, wire coat or inner liner.

In addition, the rubber composition for tire tread exhibits an excellent balance effect in terms of abrasion resistance, LRR and wet performance, and thus is useful as a tire-tread rubber composition for truck-bus.

According to another embodiment of the present invention, there is provided a tire manufactured using the rubber composition for a tire tread.

The tire is manufactured from the rubber composition for a tire tread and exhibits improved balance in all aspects of rotational resistance, wet road surface braking force and abrasion resistance.

The method of manufacturing the tire may be any method used for manufacturing a tire except for the use of the rubber composition for tire tread, and a detailed description thereof will be omitted herein. However, the tire may include a tire tread made using the rubber composition for a tire tread.

The tires may be automobile tires, racing tires, airplane tires, agricultural tires, off-the-road tires, truck tires or bus tires. Further, the tire may be a radial tire or a bias tire, and preferably a radial tire.

The rubber composition for a tire tread according to the present invention can improve abrasion resistance and cut-chip performance while maintaining fuel economy performance, and improve appearance characteristics of a tire including coloring degree.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Examples and Comparative Examples: Preparation of Rubber Composition for Tire Tread

Were mixed in the compositions and contents as shown in Table 1 below, and mixed in a Banbury mixer to prepare a rubber composition for a tire tread.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Mixing temperature (캜) 170 170 150 170 170 Natural rubber 50 75 50 50 50 Polybutadiene rubber ¹ 25 - 25 25 25 ENR ² 25 25 25 25 25 Silica ³ 50 50 50 50 - Silane coupling agent ^4-1 5 5 5 - - Silane coupling agent ^4-2 - - - 5 - Carbon black ⁵ 20 20 20 20 55 Process oil ⁶ 5 5 5 5 5 Zinc oxide 3 3 3 3 3 Stearic acid 1.5 1.5 1.5 1.5 1.5 Vulcanizing agent
(brimstone) 2.0 2.0 2.0 2.0 2.0 Vulcanization
Accelerator ⁷ 1.8 1.8 1.8 1.8 1.8

1. Polybutadiene rubber: A butadiene rubber (weight average molecular weight 7.5 to 9.2x10 ⁵ g / mol and molecular weight distribution 3.3) prepared by neodymium catalyst,

2. ENR: epoxidized natural rubber having an epoxidization degree of 20 mol%, a Tg of -45 DEG C and a pattern viscosity of 70

3. Silica: precipitated silica (CTAB 161 m ² / g, BET 176 m ² / g, N ² SA 155 m ² / g)

4-1. Silane coupling agent: disulfide compound (Si75 ^® , manufactured by Evonik) having a sulfur content of 16% by weight and a molecular weight of 485 g / mol,

4-2: Silane coupling agent: tetrasulfide compound (Si69 ^® , manufactured by Evonik) having a sulfur content of 23% by weight and a molecular weight of 535 g / mol,

5. Carbon black: Carbon black particles (iodine adsorption value of 142 mg / g, oil adsorption specific surface area (OAN) of 102 cc / 100 g, DBP oil absorption of 130 cc / 100 g, TINT value of 120)

6. Process oil: Process oil having a PAH content of 3% by weight or less, a kinematic viscosity of 95 (210 S SUS), an aromatic component of 20% by weight, a naphthene component of 32% and a paraffin component of 48%

7. Vulcanization accelerator: CBS (N-cyclohexyl-2-benzothiazoyl sulfonamide)

Test example: Measurement of physical properties

Rubber specimens were prepared using the rubber compositions for tire treads prepared in Examples 1 to 3 and Comparative Examples 1 and 2 and various physical properties were evaluated according to the ASTM regulations for the rubber specimens. Were manufactured and evaluated as 315 / 70R22.5 standard for trucks. The results are shown in Table 2 below.

(1) Mixing processability: The Mooney viscosity (ML1 + 4 (125 ° C)) was measured using a Mooney MV2000 (Alpha Technology) Respectively. The Mooney viscosity is an index showing the workability. The smaller the value, the better the workability.

(2) The scorch time is measured using a moving die rheometer. The shorter the time, the disadvantage is.

(2) The hardness was measured using a Shore A hardness meter.

(4) The 300% modulus is the tensile strength at 300% elongation, measured according to ISO 37 standard, and the higher the value, the better the strength.

(5) Low Rolling Resistance (LRR) The performance index is a measure of the reaction force acting on the side of a tire when the tire is rotated at a constant speed when the tire is brought into contact with a drum of a certain size that reproduces the road surface indoors. ) Was measured and the rotational resistance value was calculated. The larger the LRR performance, the better the performance.

(6) The abrasion resistance index was expressed by indexing on the basis of the measurement value of Example 1 after measuring the abrasion amount under the condition of a slip rate of 25% by using a rambone abrasion tester. The wear resistance performance means that the higher the value, the better the performance.

(7) Wet index: Calculated by the ratio of the maximum static friction coefficient of the test tire to the reference tire, and the measured value of Example 1 was taken as 100, and expressed as index based on this value. The larger the value of the wet index, the better the performance.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Mixability
(Pattern viscosity) 64 63 65 66 67 Scorch time (t5) 9.8 9.5 9.1 6.2 10.4 Hardness (Shore A) 66 64 59 60 68 300% modulus
(kgf / cm2) 162 157 141 145 171 LRR performance index 100 95 91 90 84 Wear resistance performance index 100 96 95 82 94 Wet performance index 100 93 91 92 87

As shown in Table 2, in Example 3 in which the compounding temperature was low, the bond between the polymer and the filler was insufficient, and thus showed a slightly lower figure of merit than Example 1 having the same composition. Nevertheless, Examples 1 to 3, which satisfied the combination configuration according to the present invention, exhibited improved effects in terms of wear resistance, LRR and wet performance, as compared with Comparative Examples 1 and 2, in both cases.

In detail, Comparative Example 1 using a tetrasulfide-based coupling agent exhibited a short scorch time due to the deterioration of high-temperature properties, and exhibited an overall deteriorated performance index due to deterioration of bonding force between rubber and filler. In Comparative Example 2, in which only carbon black was used as a filler without using silica, the wear performance was improved as compared with Comparative Example 1, but the LRR and wet performance were significantly lowered.

In order to obtain the effects of the present invention from the above experimental results, it is necessary to satisfy the optimum combination composition of the rubber composition according to the present invention. Further, as the high-temperature compounding is maintained in the production, an improved effect is obtained in terms of wear resistance performance, LRR and wet performance .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims (8)

Based on 100 parts by weight of a raw material rubber comprising 40 to 75 parts by weight of a natural rubber and 20 to 30 parts by weight of an epoxidized natural rubber,
20 to 120 parts by weight of silica, and
1 to 30 parts by weight of a silane coupling agent,
Wherein the silane coupling agent is a disulfide compound having a sulfur content of 15 to 20 wt% and a molecular weight of 480 to 520 g / mol. The method according to claim 1,
Wherein the epoxidized natural rubber has a glass transition temperature (Tg) of -50 to -40 占 폚, a pattern viscosity of 60 to 80, and an epoxidation degree of 5 to 50 mol%. The method according to claim 1,
Further comprising neodymium butadiene rubber having a weight average molecular weight of 7 x 10 ⁵ to 9.2 x ^{10 5} g / mol and a molecular weight distribution of 3.2 to 3.5 in an amount of 10 to 25 wt% based on the total weight of the starting rubber Rubber composition for tire tread. The method according to claim 1,
Wherein the silica has an adsorption specific surface area of cetyl trimethyl ammonium bromide of 105 to 175 m ² / g and a BET (Brunauer-Emmett-Teller) specific surface area of 140 to 250 m ² / g. The method according to claim 1,
Carbon black having an iodine adsorption of 50 to 170 mg / g, an oil adsorption specific surface area of 85 to 129 cc / 100 g, a dibutylphthalate oil absorption of 100 to 160 cc / 100 g and a TINT value of 110 to 157, By weight based on 100 parts by weight of the rubber composition. Wherein the rubber comprises 20 to 120 parts by weight of silica, 15 to 20% by weight of sulfur, 15 to 20% by weight of silica, and 480 to 580 parts by weight of silica, based on 100 parts by weight of raw rubber comprising 40 to 75 parts by weight of natural rubber and 20 to 30 parts by weight of epoxidized natural rubber. And 1 to 30 parts by weight of a disulfide-based silane coupling agent having a weight-average molecular weight (Mw) of 520 g / mol. The method according to claim 6,
Carbon black having an iodine adsorption of 50 to 170 mg / g and an oil adsorption specific surface area of 85 to 129 cc / 100 g, a dibutyl phthalate oil absorption of 100 to 160 cc / 100 g, and a TINT value of 110 to 157, By weight based on 100 parts by weight of the rubber composition, and further adding the rubber component in an amount of 5 to 35 parts by weight based on 100 parts by weight of the rubber component. A tire produced by using the rubber composition for a tire tread according to any one of claims 1 to 5.