KR101496242B1 - 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 a tire produced using the same, wherein the rubber composition for a tire tread comprises 20 to 50 parts by weight of a continuous solution-polymerized styrene-butadiene rubber, 20 to 50 parts by weight of a batch- And 10 to 40 parts by weight of neodymium butadiene rubber, 60 to 90 parts by weight of silica, and a mixture of saturated fatty acid amide and saturated fatty acid ester containing calcium salt, Parts by weight.
The rubber composition for a tire tread improves the low rolling resistance and the wear resistance while solving the workability problem accompanying introduction of a material which is difficult to process.

Description

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

The present invention relates to a rubber composition for a tire tread and a tire produced using the same. More particularly, the present invention relates to a rubber composition for a tire tread which improves the low rolling resistance and the abrasion resistance while solving workability problems caused by introduction of a material having difficulty in workability And a tire manufactured using the same.

Recently, due to the high performance of passenger cars, consumers are actively looking at the application of new concept raw materials to tires that have abrasion resistance, handling and ride performance, braking performance and low fuel consumption.

By using silica, the low fuel consumption, low rolling resistance, and braking performance on wet road surface are improved compared to carbon black, but silica is relatively difficult to disperse compared to conventional carbon black.

On the other hand, the neodymium butadiene rubber has a narrow molecular weight distribution and a linear molecular structure, which results in a low hysteresis of the rubber, which results in excellent rolling resistance and excellent abrasion resistance, but has a disadvantage in that processing is disadvantageous.

Therefore, it is necessary to develop a new processing aid which simultaneously improves the dispersibility and processability. In order to solve these problems, the improvement of the dispersibility of silica and the improvement of the processability at the time of extrusion were improved by using the processing aid, but the proper use of each processing aid for the required properties was a difficult technical problem due to the influence on the property value when using the processing aid .

Korea Patent Publication No. 2005-0122460 (Disclosure Date: December 29, 2005) Korean Patent Publication No. 2010-0084852 (Published on July 28, 2010)

It is an object of the present invention to provide a rubber composition for a tire tread which can improve the low rolling resistance and the abrasion resistance while solving the workability problem caused by introduction of a material with difficult machinability.

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

To achieve the above object, a rubber composition for a tire tread according to an embodiment of the present invention comprises 20 to 50 parts by weight of a continuous solution-polymerized styrene-butadiene rubber, 20 to 50 parts by weight of a batch-type solution-polymerized styrene-butadiene rubber, 100 parts by weight of a starting rubber comprising 10 to 40 parts by weight of a butadiene rubber, 60 to 90 parts by weight of silica, and 1 to 5 parts by weight of a processing aid comprising a mixture of a saturated fatty acid amide and a saturated fatty acid ester comprising a calcium salt have.

The saturated fatty acid may be a saturated fatty acid having 1 to 10 hydroxy (-OH) groups and having 14 to 18 carbon atoms.

The saturated fatty acid may be any one selected from the group consisting of capric acid, caprylic acid, palmitic acid, and combinations thereof.

Wherein the continuous solution-polymerized styrene-butadiene rubber has a styrene content of 20 to 30 wt%, a vinyl content of butadiene of 30 to 70 wt%, and a styrene-butadiene rubber having a styrene content of 35 to 45 wt% %, And the vinyl content of the butadiene may be 20 to 30 wt%.

The continuous solution-polymerized styrene-butadiene rubber further comprises 20 to 40 parts by weight of a TDAE oil, wherein the TDAE oil has a total content of polycyclic aromatic hydrocarbons of 3% by weight or less and a kinematic viscosity of 95 or more (210 S SUS), the aromatic component may be 15 to 25 wt%, the naphthene component may be 27 to 37 wt%, and the paraffin component may be 38 to 58 wt%.

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.

A rubber composition for a tire tread according to an embodiment of the present invention comprises 20 to 50 parts by weight of a continuous solution-polymerized styrene-butadiene rubber, 20 to 50 parts by weight of a batch-type solution-polymerized styrene-butadiene rubber, and 10 to 40 parts by weight of a neodymium- 100 parts by weight of raw rubber, 60 to 90 parts by weight of silica, and 1 to 5 parts by weight of a processing aid comprising a mixture of saturated fatty acid amide and saturated fatty acid ester containing calcium salt.

The rubber composition for a tire tread can solve the workability problem due to an increase in the introduction amount of the raw material, which is difficult to process, while improving the low rolling resistance and wear resistance by using the processing aid.

The rubber composition for tire tread uses batch-type solution-polymerized styrene-butadiene rubber, continuous solution-polymerized styrene-butadiene rubber and neodymium-butadiene rubber as raw rubber.

The batch solution-polymerized styrene-butadiene rubber is a rubber polymerized by a batch process, wherein the styrene content is 35 to 45% by weight and the vinyl content in butadiene is 20 to 30% by weight.

Batch solution-polymerized styrene-butadiene rubber having the above characteristics has a relatively low styrene content. Generally, since the structure of styrene is larger than the structure of vinyl, when the content of styrene is low, the hysteresis heat loss due to friction is low, Do.

The batch solution-polymerized styrene-butadiene rubber may be included in an amount of 20 to 50 parts by weight based on 100 parts by weight of the raw rubber. If the content of the batch-type solution-polymerized styrene-butadiene rubber is less than 20 parts by weight, improvement in the fuel-combustion performance may be poor, and if the amount is more than 50 parts by weight, braking performance may be disadvantageous.

In addition, since the batch-type solution-polymerized styrene-butadiene rubber does not contain an oil, hysteresis is somewhat higher than that of an oil-containing rubber, and the braking performance is also improved.

The continuous solution-polymerized styrene-butadiene rubber is a rubber polymerized by a continuous method and has a styrene content of 30% by weight in 20 and a vinyl content in butadiene of 30% to 70% by weight.

The continuous solution-polymerized styrene-butadiene rubber may contain 20 to 40 parts by weight of TDAE oil. The content of the TDAE oil refers to 100 parts by weight of the rubbery component of the continuous solution-polymerized styrene-butadiene rubber, and the rubbery component refers to all other components except for the oil in the continuous solution-polymerized styrene-butadiene rubber .

Wherein the TDAE oil has a total content of 3% by weight or less of polycyclic aromatic hydrocarbons, a kinematic viscosity of at least 210 ° F. SUS, an aromatic component of 15 to 25% by weight, a naphthene- 37% by weight and the paraffinic component is 38 to 58% by weight.

Unlike the styrene-butadiene rubber polymerized by the batch method, the continuous solution-polymerized styrene-butadiene rubber can be polymerized by a continuous method, and can exhibit excellent braking performance due to high hysteresis heat loss due to a large amount of low molecular substances. This can be seen as an optimized raw material that balances trade-off performance with low fuel consumption and braking performance.

The continuous solution-polymerized styrene-butadiene rubber may be included in an amount of 20 to 50 parts by weight based on 100 parts by weight of the raw rubber. The content of the continuous solution-polymerized styrene-butadiene rubber is the content of only the rubbery component except the oil. If the content of the continuous solution-polymerized styrene-butadiene rubber is less than 20 parts by weight, the braking performance and the fuel consumption performance improvement effect are insignificant. If the content is more than 50 parts by weight, the processability may be disadvantageous.

The neodymium butadiene rubber (Nd-BR) has a narrow molecular weight distribution and a linear molecular structure as compared with cobalt butadiene rubber (Co-BR) or nickel butadiene rubber, and has a low hysteresis heat loss. In this respect, the neodymium-butadiene rubber may have a glass transition temperature (Tg) of -100 to -110 ° C and a molecular weight distribution of 1.5 to 2.5.

If the content of the neodymium-butadiene rubber is less than 10 parts by weight based on 100 parts by weight of the raw rubber, the abrasion resistance and the low fuel consumption performance are disadvantageous. If the neodymium butadiene rubber is more than 40 parts by weight, the workability may be deteriorated.

The rubber composition for a tire tread does not use carbon black as a reinforcing filler but uses highly disperse silica alone.

In order to produce a rubber composition for a tire tread suitable for the purpose of the present invention, silica having a nitrogen adsorption amount of 160 to 180 m 2 / g, a CTAB value of 150 to 170 m 2 / g and a DBP oil absorption of 180 to 200 cc / It is preferable to use 60 to 90 parts by weight based on 100 parts by weight of the rubber. If the amount of the silica is less than 60 parts by weight, the braking performance may be poor. If the amount is more than 90 parts by weight, abrasion resistance and low fuel consumption performance may be disadvantageous.

A silane coupling agent may also be used to improve the dispersibility of the silica. The silane coupling agent includes bis (trialkoxysilylpropyl) polysulfide (TESPD) and bis-3-triethoxysilylpropyltetrasulfide (TESPT) in an alkoxy polysulfide silane compound. TESPD is a mixture of TESPT and carbon black 50 %. The silane coupling agent may be used in an amount of 10 to 20 parts by weight based on 100 parts by weight of the raw material rubber.

The rubber composition for a tire tread contains a processing aid comprising calcium salt, saturated fatty acid amide and saturated fatty acid ester as a processing aid in an amount of 1 to 5 parts by weight based on 100 parts by weight of the raw rubber. When the above-mentioned processing aid is used in the above amount, the dispersibility of the silica in the compounding of the tread rubber composition containing the silica as a filler can be increased and the workability at the time of extrusion can be improved, so that productivity and quality uniformity can be secured. The deterioration of physical properties can be minimized.

The conventional processing aid serves as a main raw material of zinc soap composed of unsaturated fatty acid, which helps to solve the entanglement of polymers during mixing and has an effect of lowering the Mooney viscosity. Since the conventional processing aid has a function of releasing the entanglement of the polymer itself rather than the dispersion with the silica, it is required to improve the performance of the processing aid as silica use increases.

The calcium salt of the processing aid less affects the crosslinking reaction and scorch, and the saturated fatty acid can be formed by substituting a double bond of an unsaturated fatty acid by a hydroxy (-OH) group. The saturated fatty acid may be selected from the group consisting of capric acid, caprylic acid, palmitic acid, and a combination thereof, which has 1 to 10 hydroxyl groups and 14 to 18 carbon atoms. Since the saturated fatty acid is substituted with the hydroxy group, the -COOH and -OH functional groups are hydrogen-bonded to the silanol groups on the surface of the silica, and the silica having lipophilic functional groups on the surface improves the dispersion degree in the rubber composition, Thereby improving the workability.

Further, since the processing aid contains a mixture of saturated fatty acid amides and saturated fatty acid esters, the processing aid acts on the silica to suppress re-aggregation between the silica to improve dispersion and to improve the modulus and hysteresis It is possible to improve the physical properties of the resin.

The rubber composition for a tire tread may further comprise a vulcanizing agent.

The vulcanizing agent may be a sulfur vulcanizing agent. Examples of such sulfur vulcanizing agents are the vulcanizing agents which produce elemental sulfur or sulfur, such as amine disulfides and polymeric sulfur. The vulcanizing agent may be included in an amount of 1.5 to 2.5 parts by weight based on 100 parts by weight of the raw rubber.

The rubber composition for a tire tread may further comprise a vulcanization accelerator.

The vulcanization accelerator may be a compound selected from an amine, a disulfide, a guanidine, a thio element, a thiazole, a thiuram, and a sulfene amide. The vulcanization accelerator may be contained in an amount of 0.8 to 2.0 parts by weight based on 100 parts by weight of the raw rubber.

The rubber composition for a tire tread may further comprise an anti-aging agent.

The antioxidant may be selected from the group consisting of N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine (6PPD) n-isopropyl-p-phenylenediamine (3PPD) or poly (2,2,4-trimethyl-1,2-dihydroquinoline (poly 4-trimethyl-1,2-dihydroquinoline, RD). The antioxidant may be included in an amount of 1 to 5 parts by weight based on 100 parts by weight of the raw rubber.

The rubber composition for a tire tread can be produced through a conventional two-step continuous manufacturing process. That is, during the finishing step in which the first stage of thermomechanical treatment or kneading and the crosslinking system are mixed at a maximum temperature of 110 to 190 占 폚, preferably at a high temperature of 130 to 180 占 폚, typically less than 110 占 폚, And a second step of mechanical treatment at a low temperature of 40 to 100 DEG C in a suitable mixer, but the present invention is not limited thereto.

The rubber composition for a tire tread is not limited to a tread (a tread cap and a tread base) but may be included in various rubber components constituting the tire. Said rubber components include sidewalls, sidewall inserts, apex, chafer, wire coat or inner liner.

A tire according to another embodiment of the present invention is manufactured using the rubber composition for the tire tread. The method of manufacturing a tire using the rubber composition for a tire tread may be any method conventionally used for manufacturing a tire, and a detailed description thereof will be omitted herein.

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 of the present invention improves the low rolling resistance and the abrasion resistance while solving the workability problem accompanying the introduction of a material having difficult processing properties.

1 is a photograph of a rubber specimen of Comparative Example 1 extruded at 60 ° C.
2 is a photograph of a rubber specimen of Comparative Example 1 extruded at 100 ° C.
3 is a photograph of the rubber specimen of Comparative Example 1 extruded at 120 ° C.
4 is a photograph of the rubber specimen of Example 1 being extruded at 60 ° C.
5 is a photograph of the rubber specimen of Example 1 extruded at 100 ° C.
6 is a photograph of the rubber specimen of Example 2 extruded at 120 ° C.

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.

[Production Example: Production of Rubber Composition]

Rubber compositions for tire treads according to the following Examples and Comparative Examples were prepared using the compositions shown in Table 1 below. The production of the rubber composition was in accordance with the usual production method of the rubber composition.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 1 S-SBR 1 ⁽¹⁾ 25
(30) 25
(30) 25
(30) 25
(30) 25
(30) 25
(30) S-SBR 2 ⁽²⁾ 45 45 45 45 45 45 BR ⁽³⁾ 30 30 30 30 30 30 Silica ⁽⁴⁾ 75 75 75 75 75 75 Coupling agent 15 15 15 15 15 15 Oil ⁽⁵⁾ 3 3 3 3 3 3 Zinc oxide 2 2 2 2 2 2 Stearic acid One One One One One One Antioxidant 4 4 4 4 4 4 Processing aid A ⁽⁶⁾ 2 - - - - - Processing aid B ⁽⁷⁾ - 2 - - - - Processing aid C ⁽⁸⁾ - - 2 - - - Processing aid D ⁽⁹⁾ - - - 2 - - Processing aid E ⁽¹⁰⁾ - - - - 2 - Processing aid F ⁽¹¹⁾ - - - - - 2 Vulcanizing agent 1.75 1.75 1.75 1.75 1.75 1.75 Vulcanization accelerator One One One One One One Accelerator (DPG) 2 2 2 2 2 2

week)

(Unit: parts by weight)

(1) S-SBR 1: Continuous solution polymerized styrene-butadiene rubber having a styrene content of 20 to 30% by weight and a vinyl content of 30 to 70% by weight in the butadiene (the values in parentheses are the content being)

(2) S-SBR 2: Batch solution-polymerized styrene-butadiene rubber having a styrene content of 35 to 45% by weight and a vinyl content of 20 to 30% by weight in butadiene

(3) BR: Neodymium butadiene rubber made by Lanxess

(4) Silica: A precipitated silica having a nitrogen adsorption specific surface area of 170 m ² / g and a CTAB adsorption specific surface area of 160 m ² / g

(5) Oil: TDAE oil

(6) Processing aid A: fatty acid having -OH group

(7) Processing aid B: Surfactant mixture containing fatty acid

(8) Processing aid C: Amino acid compound with fatty acid amide

(9) Processing aid D: Fatty acid and amino acid compound

(10) Processing aid E: Hydrophilic fatty acid ester having a high molecular weight

(11) Processing aid F: Saturated fatty acid amide and ester mixture containing calcium salt

[Experimental Example: Measurement of Physical Properties of the Rubber Composition]

The rubber specimens prepared in the above Examples and Comparative Examples were measured for Mooney viscosity, hardness, 300% modulus and viscoelasticity according to the ASTM-related regulations, and the results are shown in Table 2.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 1 Mooney viscosity 77 69 74 70 74 68 Hardness 68 67 67 66 66 68 300% modulus 11.8 11.9 11.1 11.7 11.1 11.9 0 deg. 0.470 0.458 0.450 0.444 0.454 0.457 60 deg. 0.142 0.136 0.128 0.130 0.127 0.126

- Mooney viscosity (ML1 + 4 (125 占 폚)) was measured according to ASTM standard D1646.

- Hardness (Shore A) was measured according to DIN 53505.

- 300% Modulus (MPa) was measured according to ISO 37 standard.

- The viscoelasticity was measured by using an RDS measuring instrument, G ', G ", and tan δ at a temperature of -60 ° C. to 80 ° C. under a frequency of 10 Hz at a strain of 0.5%.

In Table 2, the Mooney viscosity indicates the viscosity of the unvulcanized rubber, and the lower the numerical value, the better the workability of the unvulcanized rubber. The hardness indicates the adjustment stability, and the higher the value, the better the adjustment stability. The 0 ° C tan δ indicates the braking performance. The higher the value, the better the braking performance. The 60 ° C tan δ indicates the rotational resistance characteristic, and the lower the value, the better the performance.

Further, the rubber specimens of Comparative Examples 1 and 1 were extruded while changing the discharge temperature, and the surface processability was shown in Figs. 1 to 6. Fig. 1 shows the result of extruding the rubber specimen of Comparative Example 1 at 60 DEG C, Fig. 2 shows the result of extruding the rubber specimen of Comparative Example 1 at 100 DEG C, Fig. 3 shows the result of extruding the rubber specimen of Comparative Example 1 at 120 DEG C This is a result. Fig. 4 shows the result of extruding the rubber specimen of Example 1 at 60 DEG C, Fig. 5 shows the result of extruding the rubber specimen of Example 1 at 100 DEG C, Fig. 6 shows the result of extruding the rubber specimen of Example 1 at 120 DEG C This is a result.

Referring to Table 2, FIG. 1 to FIG. 6, in the case of Example 1, the workability was improved in terms of processability that can be confirmed through the Mooney viscosity, and the rotational resistance characteristic was improved as compared with Comparative Example. In addition, it can be seen that the reduction of the hardness and high elongation modulus value affects not only the processability but also the physical properties when using the processing aid.

In addition, it was confirmed that the extruded surface workability of Example 1 was improved compared to the comparative example as a result of the comparison of the surface formability during extrusion showing not only the Mooney viscosity showing the workability at the time of using the processing aid of the present invention but also the substantial workability. Also, it can be seen that the lower the discharge temperature, the better the extrusion surface processability, and the surface improvement effect according to the processing aid at the high temperature extrusion condition was minimal.

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 (6)

100 parts by weight of a raw rubber comprising 20 to 50 parts by weight of a continuous solution polymerized styrene-butadiene rubber, 20 to 50 parts by weight of a batch-type solution-polymerized styrene-butadiene rubber, and 10 to 40 parts by weight of neodymium-
60 to 90 parts by weight of silica, and
1 to 5 parts by weight of a processing aid comprising a mixture of saturated fatty acid amides and saturated fatty acid esters comprising calcium salts,
Wherein the saturated fatty acid has 1 to 10 hydroxy (-OH) groups and has 14 to 18 carbon atoms. delete The method according to claim 1,
Wherein the saturated fatty acid is any one selected from the group consisting of capric acid, caprylic acid, palmitic acid, and combinations thereof containing 1 to 10 hydroxy (-OH) groups. The method according to claim 1,
The continuous solution-polymerized styrene-butadiene rubber has a styrene content of 20 to 30% by weight, a butadiene-containing vinyl content of 30 to 70% by weight,
Wherein the batch solution polymerized styrene-butadiene rubber has a styrene content of 35 to 45% by weight and a vinyl content of butadiene of 20 to 30% by weight. The method according to claim 1,
The continuous solution-polymerized styrene-butadiene rubber further comprises 20 to 40 parts by weight of TDAE oil,
Wherein the TDAE oil has a total content of 3% by weight or less of polycyclic aromatic hydrocarbons, a kinematic viscosity of 210 or more and a aromatic component of 15 to 25% by weight, a naphthene component of 27 to 50% by weight, 37% by weight and paraffinic component is 38% by weight to 58% by weight. A tire produced by using the rubber composition for a tire tread according to claim 1.

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