KR101794829B1

KR101794829B1 - Rubber Composition for Tire Tread and Method thereof

Info

Publication number: KR101794829B1
Application number: KR1020150143980A
Authority: KR
Inventors: 강유신
Original assignee: 현대자동차주식회사
Priority date: 2015-10-15
Filing date: 2015-10-15
Publication date: 2017-11-07
Also published as: KR20170044375A

Abstract

The present invention relates to a rubber composition for a tire tread and a method for producing the same, and more particularly to a rubber composition for a tire tread including a rubber polymer, a filler, an additive, and a butadiene rubber-acrylate terpolymer (BR-acrylate terpolymer) To a rubber composition for a tire tread and a method for producing the same.
According to the rubber composition for a tire tread of the present invention and the method for producing the same, the cornering force is improved and the alignment torque is improved. In addition, since the master batch in which the BR-acrylate terpolymer is dispersed is used, The dispersibility of BR is ensured and the mechanical properties are improved by increasing the hardness, tensile strength and modulus of the tread composition.

Description

Technical Field [0001] The present invention relates to a rubber composition for a tire tread,

The present invention relates to a rubber composition for a tire tread and a method for producing the same, and more particularly to a rubber composition for a tire tread including a rubber polymer, a filler, an additive, and a butadiene rubber-acrylate terpolymer (BR-acrylate terpolymer) To a rubber composition for a tire tread and a method for producing the same.

The tire tread is a part forming a ground portion between an automobile and a road surface, and has a direct relationship with the braking performance, fuel consumption and handling performance of an automobile, and is an important part that may be connected by human accident in the event of a problem such as performance deterioration of the tire.

Therefore, the rubber used for the tire tread portion which is in direct contact with the ground should have excellent abrasion resistance, braking force, and durability as well as excellent adjustment stability, ride comfort, fuel economy performance and snow performance when driving the vehicle.

In recent years, a tread composition of a tire has been used in which the styrene content of the microstructure of SBR (Styrene Butadiene Rubber) is increased. In this case, the braking performance of the tire is improved but the fuel efficiency is lowered. In order to compensate for this, increasing the vinyl content of the microstructure of the SBR improves the fuel efficiency, but at the same time, the braking performance progresses in a downward direction.

Recently, in order to improve the handling performance of automobiles, development of technology for increasing the rigidity of the tire side portion has been actively progressed. However, if the side stiffness is increased, the cornering stiffness is increased, but the alignment torque stiffness is lowered. In other words, it is difficult to improve various properties at the same time because each performance is balanced with each other, and generally, when one characteristic improves, a trade off phenomenon in which the remaining characteristic deteriorates occurs.

Therefore, it is necessary to develop a technology capable of simultaneously improving the performance of the tire treads which are contradictory while minimizing the trade-off problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art,

And an object of the present invention is to provide a rubber composition for a tire tread having improved on-center feel and on-handling performance by improving side surface rigidity and road surface gripping force, and a manufacturing method thereof.

In addition, the present invention utilizes a master batch in which a BR-acrylate terpolymer is already dispersed in a polymer and a filler, thereby ensuring the dispersibility of the BR-acrylate terpolymer without any additional dispersion process. The present invention provides a rubber composition for a tire tread capable of maintaining a balance of performance without causing a trade-off problem between performances due to the absence of degradation of the rubber composition and a manufacturing method thereof.

The technical objects to be achieved by the present invention are not limited to the technical matters mentioned above, and other technical subjects which are not mentioned can be clearly understood by those skilled in the art from the description of the present invention .

According to one aspect of the present invention, there is provided a rubber composition for a tire tread, which comprises a rubber polymer, a filler, an additive, a butadiene rubber-acrylate terpolymer (BR) -acrylate terpolymer).

In one embodiment of the present invention, the rubber polymer comprises 50 to 80% by weight of styrene butadiene rubber (SBR) in 100% by weight of the rubber polymer, 0 to 50% or less of natural rubber By weight and butadiene rubber (BR) of more than 0 and 40% by weight or less.

In one embodiment of the present invention, it is preferable that the filler comprises 50 to 100 parts by weight of silica and 2 to 20 parts by weight of carbon black to 100 parts by weight of the rubber polymer.

In an embodiment of the present invention, the additive may include 2 to 3 parts by weight of sulfur (S), 2 to 4 parts by weight of a vulcanization accelerator, 0.5 to 2 parts by weight of stearic acid, and zinc oxide zinc oxide, ZnO) in an amount of 2 to 5 parts by weight.

In one embodiment of the present invention, the butadiene rubber-acrylate terpolymer preferably comprises 1 to 7 wt% of 100 wt% of the rubber composition.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a base by mixing a rubber polymer, a filler, and an additive; A second step of adding a fatty acid sucrose ester (nonionic surfactant) to the master batch polymer; A third step of adding butadiene rubber-acrylate terpolymer to the solvent of the second step; A fourth step of injecting ultrasonic into the solvent of the third step; And a fifth step of adding the solvent of the fourth step to the base of the first step.

According to the rubber composition for a tire tread of the present invention and its manufacturing method, it is possible to improve on-center performance and handling performance by improving i) the cornering force and the opposite alignment torque, and ii) -acrylate terpolymer is dispersed, the dispersibility of BR-acrylate terpolymer is ensured without any additional dispersion process, and iii) there is no deterioration of fuel consumption and braking performance by adding BR-acrylate terpolymer, and iv) the hardness, the tensile strength and the modulus of the tread composition are increased, and the mechanical properties are improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing changes in cornering force according to changes in constituent components and contents of a rubber composition for a tire tread according to the prior art. FIG.
2 is a graph showing changes in on-center performance according to changes in constituent components and content of a rubber composition for a tire tread according to the prior art.
3 is an enlarged photograph of a BR-acrylate terpolymer according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present.

FIG. 1 is a graph showing a change in cornering force according to changes in constituent components and content of a rubber composition for a tire tread according to the prior art, and FIG. 2 is a graph showing changes in constituents and content of the rubber composition for a tire tread And the on-center performance according to the present invention.

The tire tread has a direct contact between the tire and the ground, and has a direct influence on the power transmission, the redirection, and the fuel consumption of the vehicle. Cornering force and aligning torque are typical characteristics required for such a rubber composition for tread. The cornering force is a force parallel to the centrifugal force generated when the vehicle turns, that is, Since the lower part of the tire rotates when it is turned, it is the operating force that occurs inside the tire from the road surface due to the friction between the tire and the road surface. Further, when the tire is rotated with the slip angle, the alignment point does not coincide with the center of gravity of the tire, so that the torque acts in a direction to reduce the slip angle around the center of the ground It says.

However, since the cornering force and the alignment torque are in a trade off state, when the C tire has a superior cornering force as compared with the D tire as shown in FIGS. 1 and 2, It can be seen that the value of the steering wheel torque according to the variation of the lateral acceleration and the steering wheel angle is decreased because the treading torque stiffness of the tread becomes lower, center feel) is lowered.

In recent years, SBR, BR, and NR have been blended with a main polymer as a material for automobile tire tread at a specific ratio. In particular, a polymer having a higher styrene content in the microstructure of styrene-butadiene rubber (SBR) It is mainly used. In addition, silica filler fillers for compound reinforcement are being developed to improve fuel efficiency by reducing rolling resistance by applying silica, and to improve braking performance on dry and wet road surfaces.

However, the conventional tread material has a disadvantage in that the fuel efficiency is lowered as the styrene content in the microstructure of the SBR is increased. In order to compensate the decrease in the fuel efficiency, the amount of vinyl in the microstructure of the SBR The tread fuel efficiency is improved, but at the same time, the braking performance is disadvantageous in that it proceeds in a downward direction.

Accordingly, the rubber composition for a tire tread of the present invention is characterized by being able to simultaneously improve the main performance of a tire in a trade-off by introducing BR-acrylate terpolymer as a new filler. More specifically, Thereby improving the sense of centering of the center.

In the present invention, the use of a master batch in which a BR-acrylate terpolymer is already dispersed is advantageous in that the dispersibility of the BR-acrylate terpolymer can be secured without any additional dispersion process . Further, the rubber composition for a tread according to the present invention does not cause deterioration of fuel consumption performance due to addition of BR-acrylate terpolymer. In other words, it does not cause the trade off problem between the performance and maintains the performance balance.

In addition, the rubber composition for tread of the present invention is characterized in that mechanical properties such as hardness, tensile strength and modulus are improved as compared with the composition for tread according to the prior art, and the same level can be maintained without lowering the fuel consumption and braking performance .

Table 1 below shows constituent components and content of the rubber composition for treads according to the prior art and the rubber composition for treads according to the present invention.

Raw material Comparative Example
(0%) Example 1
(One%) Example 2
(3%) Example 3
(5%) Example 4
(7%) Example 5
(9%)
Polymer S-SBR 60 60 60 60 60 60 BR 30 30 30 30 30 30 NR 10 10 10 10 10 10
Filler Silica 85 85 85 85 85 85 Carbon black 5 5 5 5 5 5 BR-acrylate terpolymer 0 2 6 10 14 18
additive sulfur 2 2 2 2 2 2 ZnO 3 3 3 3 3 3 Vulcanization accelerator 2 2 2 2 2 2 Stearic acid One One One One One One

In Table 1, S-SBR represents a solution of styrene-butadiene rubber. As to the constituents and contents of the comparative examples and the examples, the composition of the polymer is 60 wt% of S-SBR, 30 wt% of BR, NR The filler comprises 85 parts by weight of silica and 5% by weight of carbon black relative to 100 parts by weight of the rubber polymer. The additive is composed of 2 parts by weight of sulfur, 100 parts by weight of zinc oxide, 3 parts by weight of vulcanization accelerator 2 By weight, and 1 part by weight of stearic acid, which are the same in both Comparative Examples and Examples.

In the Examples, BR-acrylate terpolymer was added in an amount of 1%, 3%, 5%, 7%, and 9% in 100% by weight of the total composition.

3 is an enlarged view of a BR-acrylate terpolymer according to an embodiment of the present invention. BR-acrylate terpolymer is a crosslinked BR having a hydroxyl group and has a nanoscale spherical shape with a diameter of about 10 to 50 nm. The hydroxyl functionalization of the terpolymer is characterized by facilitating the interaction between the rubber matrix and the polarized silica filler. More specifically, the butadiene rubber-acrylate terpolymer refers to a butadiene rubber-acrylate-hydroxyl terpolymer, and any of the known products may be used.

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In the first step, a base is formed by mixing a rubber polymer, a filler, and an additive. In a second step, a polymer for masterbatch is mixed with a nonionic surfactant, Add the ester (Sugar-ester). Masterbatch refers to a blend of vulcanizing agents, vulcanizing accelerators, antioxidants and coloring agents, or a mixture of some of the poorly mixed and dispersed blend materials at a certain ratio in advance. It is advantageous that mixing with raw gum is facilitated.

In the third step, the butadiene rubber-acrylate terpolymer is added to the solvent of the second step, and ultrasonic is injected into the solvent of the third step in the fourth step. In the fifth step, The solvent of the fourth step is added to the base of the first step. More specifically, the butadiene rubber-acrylate terpolymer refers to a butadiene rubber-acrylate-hydroxyl terpolymer, and any of the known products may be used.

Table 2 below shows the mechanical properties of each of the comparative examples shown in Table 1 and Examples 1 to 5 and the increase rate relative to the comparative example.

division Hardness
(Shorea) The tensile strength
(kgf / cm2) Elongation
(%) 300% modulus
(kgf / cm2) BR-acrylate terpolymer Comparative Example (0%) 65 187 611 78 Example 1 (1%) 66 (+ 1.5%) 196 (+ 5%) 593 (-3%) 80 (+ 3%) Example 2 (3%) 68 (+ 5%) 207 (+ 11%) 586 (-4%) 94 (+ 21%) Example 3 (5%) 70 (+ 9%) 219 (+ 17%) 568 (-7%) 111 (+ 43%) Example 4 (7%) 72 (+ 10%) 234 (25%) 527 (-14%) 163 (+ 109%) Example 5 (9%) 72 (+ 10%) 238 (27%) 530 (-15%) 112 (+ 44%)

Modulus refers to the tensile stress, ie, the force when the rubber specimen is stretched to a certain length. Typically, 100% elongation is expressed as 100% modulus, and 300% elongation is expressed as 300% modulus.

As shown in Table 2, the mechanical properties of Comparative Examples in which BR-acrylate terpolymer was not added and Examples 1 to 5 in which BR-acrylate terpolymer was added in 1,3,5,7,9 wt% were measured Experiments show that the hardness, the tensile strength and the 300% modulus increase in the case of the comparative example, compared with the comparative example.

However, the addition of BR-acrylate terpolymer reduced the elongation of the examples, but the other mechanical properties were remarkably improved. As a whole, the examples of the present invention are superior to the comparative examples in rubber properties for tire tread It can be evaluated as having.

Table 3 below shows the fuel efficiency substitution performance and the braking substitution performance value in each of the comparative examples and the examples shown in Table 1. [

division Fuel consumption substitute performance Braking performance tanδ 60 ° C tanδ 0 ° C tanδ25 ° C BR-acrylate terpolymer Comparative Example 0.136 0.310 0.193 Example 1 0.132 0.305 0.192 Example 2 0.130 0.304 0.195 Example 3 0.131 0.311 0.200 Example 4 0.125 0.315 0.198 Example 5 0.131 0.304 0.189

Table 3 shows values of fuel consumption substitution performance and braking substitution performance of Examples and Comparative Examples measured using tan delta (tan delta) values by temperature. The higher the tan delta value at 0 ° C and 25 ° C, the better the braking performance, and the lower the tan delta value at 60 ° C, the better the fuel economy.

In the case of the comparative example, the tan delta value at 60 ° C was 0.136, which was 0.125 to 0.132 in the examples. As a result, it was confirmed that the example in which the BR-acrylate terpolymer was added had better fuel consumption performance than the comparative example.

In the comparative example, the tan delta value at 0.degree. C. was measured to be 0.304 to 0.311 in the examples, and the tan delta value at 25.degree. C. was 0.193 in the comparative example. And the change in the value is insignificant. As a result, it was confirmed that the braking substitute performance was maintained at the same level in the comparative example and the example.

Table 4 below shows the tire dynamic characteristics and actual vehicle evaluation test results of the comparative examples and the examples shown in Table 1. [

division Tire Dynamic Characteristics Actual vehicle evaluation Aligning Torque Cornering force On center
Steering handling
Performance 1 ° 1 ° 4 ° Max BR-acrylate terpolymer Comparative Example (0%) 100% 100% 100% 100% 6+ 7 Example 1 (1%) 102% 102% 103% 106% 7- 7 Example 2 (3%) 103% 101% 102% 107% 7-7 7 Example 3 (5%) 104% 103% 104% 109% 7-7 7 ~ + 7 Example 4 (7%) 108% 104% 105% 111% 7 ~ 7 + 7 ~ + 7 Example 5 (9%) 101% 104% 105% 111% 6+ 7 ~ + 7

The slip angle is an angle formed by the traveling direction of the tire and the center plane of the tire when the tire is in a turning state. As shown in Table 4, when the slip angle is 1 degree, And at the same time, the cornering force of the embodiment is also increased at the slip angle of 1 deg., 4 deg. Max. As a result, it can be confirmed that the tire dynamic characteristics are improved as a whole.

As described above, according to the related art, since the aligning torque of the rubber composition for tread and the cornering force are in a trade-off relationship with each other, In the case of the rubber composition for tread, this problem is solved, and the alignment torque and the cornering force required for the tire tread are simultaneously improved.

On the other hand, in the case of the embodiment, the on-center steering feeling and handling performance are both improved in the measured values evaluated on the basis of the on-center steering feeling and steering performance.

As described above, according to the rubber composition for a tire tread of the present invention and the method of manufacturing the same, it is possible to improve the cornering force and to improve the aligning torque which is opposite to the above, The dispersibility of BR-acrylate terpolymer can be ensured without any additional dispersion process, and the process efficiency can be improved. There is no deterioration of fuel consumption and braking performance by adding BR-acrylate terpolymer, There is an advantage in that the performance balance can be maintained because it does not cause a trade-off problem, and the hardness, tensile strength and modulus of the composition for tread are increased, and mechanical properties can be improved.

Although the present invention has been described in connection with the specific embodiments of the present invention, it is to be understood that the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Various modifications and variations are possible.

Claims

A rubber polymer, a filler, an additive, butadiene rubber-acrylate-hydroxyl terpolymer (BR-acrylate terpolymer)
The rubber polymer comprises 50 to 80% by weight of styrene butadiene rubber (SBR) relative to 100% by weight of the rubber polymer, 0 to less than 50% by weight of natural rubber (NR) rubber; BR) from 0 to 40% by weight,
Wherein the filler comprises 50 to 100% by weight of silica and 2 to 20% by weight of carbon black based on 100% by weight of the rubber polymer,
Wherein the additive comprises 2 to 3% by weight of sulfur (S), 2 to 4% by weight of a vulcanization accelerator, 0.5 to 2% by weight of stearic acid and 2 to 5% by weight of zinc oxide (ZnO) % &Lt; / RTI >
Wherein the butadiene rubber-acrylate-hydroxyl terpolymer is contained in an amount of 1 to 7 wt% based on 100 wt% of the rubber composition.

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A first step of forming a base through mixing of the rubber polymer, the filler and the additive;
A second step of adding a fatty acid sucrose ester (nonionic surfactant) to the master batch polymer;
A third step of adding butadiene rubber-acrylate-hydroxyl terpolymer to the solvent of the second step;
A fourth step of injecting ultrasonic into the solvent of the third step; And
And a fifth step of adding the solvent of the fourth step to the base of the first step,
The rubber polymer comprises 50 to 80% by weight of styrene butadiene rubber (SBR) relative to 100% by weight of the rubber polymer, 0 to less than 50% by weight of natural rubber (NR) rubber; BR) from 0 to 40% by weight,
Wherein the filler comprises 50 to 100% by weight of silica and 2 to 20% by weight of carbon black based on 100% by weight of the rubber polymer,
Wherein the additive comprises 2 to 3% by weight of sulfur (S), 2 to 4% by weight of a vulcanization accelerator, 0.5 to 2% by weight of stearic acid and 2 to 5% by weight of zinc oxide (ZnO) % &Lt; / RTI >
Wherein the butadiene rubber-acrylate-hydroxyl terpolymer comprises 1 to 7 wt% based on 100 wt% of the rubber composition.

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