KR20170070554A

KR20170070554A - Tire tread rubber composition

Info

Publication number: KR20170070554A
Application number: KR1020150178214A
Authority: KR
Inventors: 고현옥
Original assignee: 금호타이어 주식회사
Priority date: 2015-12-14
Filing date: 2015-12-14
Publication date: 2017-06-22
Also published as: KR101796194B1

Abstract

The present invention is directed to a rubber composition for a tire tread. Specifically, according to one embodiment of the present invention, it is possible to provide a rubber composition for tire tread comprising 1 to 20 parts by weight of graphene per 100 parts by weight of raw rubber.

Description

[0001] Tire tread rubber composition [0002]

The present invention relates to a tire tread rubber composition having improved wear characteristics, and more particularly, to a tire tread rubber composition comprising graphene adsorbed on sodium sulfate as a reinforcing agent.

In recent years, development of high performance environmentally friendly tires has been demanded in accordance with the implementation of the tire efficiency rating system, and various studies have been conducted to develop tires having excellent economy (low rolling resistance, low wear resistance) and safety (wet traction).

In a tire, since tire tread comes into direct contact with the ground first, much research has been conducted on the rubber composition of such a tire tread. Particularly, the characteristics of the tire are closely related to the degree of dispersion of the filler in the rubber composition constituting the tire tread. Therefore, in order to uniformly disperse the rubber filler, carbon and radical bonding to the SBR (Styrene Butadiene Rubber) The purpose of this study is to improve the interactions between rubber compositions such as radical bonding and chemical bonding by imparting various functions such as terminal groups having Sn capable of forming a functional group having a carboxyl group capable of ionic bonding with silica, Has come.

Carbon black is used as such a rubber composition or additive. Carbon blacks with large surface area and small particle size provide greater strength, which is known to improve abrasion resistance, tensile strength and cracking properties, and carbon black with large particle size is known to be wet and dry Are known to exhibit reduced rolling resistance and slipping performance on wet road surfaces, i.e., improved wet performance.

On the other hand, graphene is a nano material of carbon black, which is a carbon black and an allotropic material. It is used as a new material in various areas and is used as a material for devices, reinforcements, radio frequency logic devices, sensors, displays, and transparent electrodes.

However, when such graphene is introduced into the rubber composition, since the crosslinking force between the polymer and graphene is weak, there is a problem that it is difficult to uniformly disperse the rubber composition and realize excellent physical properties.

KR 10-2005-0050487 B1

Embodiments of the present invention have been made in view of the above-described problems of the prior art, and provide rubber compositions for tires having excellent physical and mechanical properties.

According to an aspect of the present invention, there is provided a rubber composition for tire tread comprising graphene adsorbed on sodium sulfate, wherein the graphene is contained in an amount of 1 to 20 parts by weight based on 100 parts by weight of the raw rubber.

In addition, the graphene may include a hydrophilic group, and the hydrophilic group may be covalently bonded to the sodium sulfate.

Also, there is provided a method of manufacturing a graphene sheet, Oxidizing the ground graphene with an acidic aqueous solution; And a step of adding a sodium polysulfite mixture to the acidic aqueous solution to obtain graphene adsorbed with sodium sulfate, thereby providing a rubber composition for a tire tread.

According to the embodiments of the present invention, there is provided a rubber composition for a tire having excellent physical and mechanical properties.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

A rubber composition for a tire tread according to an embodiment of the present invention includes a raw rubber and a graphene. The raw material rubber may be natural rubber or synthetic rubber.

Such a rubber composition may contain graphene, and its content is 1 to 20 parts by weight based on 100 parts by weight of the raw rubber.

Graphene is a hexagonal net structure like a honeycomb, and has an atomic structure in which planes of carbon are arranged in layers, and has an excellent physical strength of more than 200 times that of steel. Therefore, when graphene is applied to a tire material, physical strength such as abrasion resistance of a tire can be improved.

In addition, graphene adsorbed on sodium sulfate may be included so that the graphene can be more dispersed in the rubber composition. That is, graphene adsorbed by sodium sulfate may be contained in an amount of 1 to 20 parts by weight based on 100 parts by weight of the raw rubber.

If the content of sodium sulfate adsorbing graphene is less than 1 part by weight based on 100 parts by weight of the starting rubber, graphene does not play a sufficient role as a reinforcing agent, so that the hardness corresponding to the physical strength and the rubber hardness such as 300% modulus, tensile strength and abrasion resistance And when the content of graphene adsorbed by sodium sulfate is more than 20 parts by weight based on 100 parts by weight of the raw rubber, viscosity and temperature of the rubber composition are excessively increased during tire production, And the increase of the viscosity causes the scorch due to the sulfation reaction of sodium sulfate in the extrusion process.

Graphene is produced by chemical stripping and sodium sulfate is adsorbed on graphene by the addition of a reducing agent to oxidized graphene after chemical stripping. For example, after the graphite crystal is oxidized, the graphene pieces separated by using ultrasonic waves are obtained. When such an oxidized graphene is uniformly dispersed in an aqueous solution of an oxidizing agent and then the sodium polysulfite mixture is oxidized by adding it as a reducing agent, the sodium polysulfide is covalently bonded to the hydrophilic group of the graphene particles produced in the oxidation step. The covalent bond of the sodium polysulfide is due to the reaction between the carboxyl group formed on the surface of the graphene and the sodium polysulfate. Through this, the graphene finally becomes positive and the graphene sheet Can be manufactured.

The sodium sulfate adsorbed graphene obtained through this reduction structure has an excellent crystallinity by removing the oxidation structure. In other words, such a sodium sulfate adsorption graphene is imparted with a chemical functional group to reduce the degree of cohesion, and a small functional group or molecules are bonded to the surface, so that the mutual action force between the substances increases and dispersion is facilitated.

As a result, the graphene adsorbed by sodium sulfate can be more uniformly dispersed when kneaded together with the raw material rubber and the additive, and the bonding force with the rubber is improved. In addition, the abrasion resistance of a tire including graphene adsorbed by sodium sulfate can be further improved.

The effect of the rubber composition according to one embodiment of the present invention will be described with reference to the following table.

The compositions of the rubber compositions of Examples 1 and 2 and Comparative Examples 1 and 2 (parts per hundred rubber) Raw materials Example 1 Example 2 Comparative Example 1 Comparative Example 2 Natural rubber 100 100 100 100 Carbon black 30 30 30 30 TDAE oil 20 20 20 20 brimstone 2.0 2.0 2.0 2.0 Stearic acid One One One One Antioxidant One One One One Grapina 10 20 10 - Remarks Sodium sulfate adsorbed on graphene. -

The physical properties of the carbon black, graphene and sodium sulfate adsorption grains used in Examples 1, 2 and Comparative Examples 1 and 2 Item Carbon black Grapina Sodium sulfate adsorption graphene Iodine adsorption value (mg / g) 140 - - Nitrogen adsorption specific surface area (m2 / g) 127 150 125 DBP oil absorption (ml / 100g) 130 - - The length (탆) - 1 to 1.5 1 to 1.5 Thickness (nm) - 8 or less 8 or less Sulfur content - - 20%

In Table 2, the sulfur content of sodium sulfate adsorption graphene was calculated by extracting sulfur with acetone and measuring the sulfur content before and after the extraction using a sulfur analyzer. The extraction method uses Soxhlet extraction.

Specifically, first, a sulfur analyzer is used to measure the amount of sulfur in a sample not under-sluhed. After that, the weight of the Thimble filter is measured, and the cylindrical filter paper and the sample are put into the Soxlet extraction equipment and extracted for at least 4 hours. After the extraction is completed, it is dried in an oven at 105 ° C for 1 hour and the weight of the cylindrical filter paper is measured. The sulfur content is measured by comparing the weight of the dried sample with the weight of the un-sulced sample.

Properties of Examples 1 and 2 and Comparative Examples 1 and 2 Representative properties Example 1 Example 2 Comparative Example 1 Comparative Example 2 Mooney viscosity 1
[100 DEG C] 83 95 92 68 Mooney Viscosity 2
[125 DEG C] 93 113 117 84 T05 10.5 9.1 11.1 13.3 Hardness (HD's) 67 72 65 63 Tensile modulus
[300% M] 147 160 128 133 The tensile strength
[TS (Kg / cm 2)] 282 271 310 290 Elongation
[EB (%)] 450 410 500 510 Tanδ 0 C
(Index) 0.1048
(108) 0.1060
(110) 0.0977
(101) 0.0968
(100) Tanδ 70 ° C
(Index) 0.0409
(96) 0.0411
(97) 0.049
(116) 0.0424
(100) Wear
(Index) 0.170
(93) 0.174
(95) 0.215
(117) 0.183
(100)

(In the above table, index represents the relative comparison value.)

As shown in the above Table 3, the rubber specimens of Examples 1 and 2 of the present invention have the basic properties such as hardness and tensile modulus (300% modulus) as compared with the rubber specimens to which the conventional carbon black according to the comparative example is applied Is improved. Particularly, in the case of containing graphene adsorbing sodium sulfate as in Examples 1 and 2, the dispersibility is improved and the bonding with rubber is better than Comparative Example 1 in which graphene without adsorbing sodium sulfate is applied, resulting in low viscosity. This indicates that in the case where graphene adsorbed with sodium sulfate is included, the processability is superior to the case where common graphene is contained.

The Mooney viscosity is measured for 4 minutes after preheating for 1 minute. These Mooney viscosities are measured at 125 캜 and 100 캜, respectively. The higher the content of the reinforcing agent, the higher the Mooney viscosity.

The scorch time (T05), as measured by a Mooney viscometer, is the time taken to raise the Mooney viscosity by 5 points from the minimum value. Through scorch time (T05), it is possible to confirm the extent to which the composition of the rubber composition is scorched (early flow), and the better the scorch stability, the greater the scorch time.

The higher the tensile modulus (300% modulus), the better the abrasion resistance. In other words, even if a 300% elongation strain is given, the stress value is excellent, so that it can withstand abrasion better. In particular, in Examples 1 and 2 in which sodium sulfate was adsorbed, the modulus was increased by 10% to 20%.

Tanδ 0 ℃ and Tan δ70 ℃ show dynamic characteristics. Specifically, tanδ0 ℃ is a substitute for wet traction, and the higher tanδ70 ℃ is the fuel efficiency substitution, the lower the better. Generally, as the carbon, graphene and other reinforcing agents are added, the fuel consumption substitution characteristics are lowered. In the case of Examples 1 and 2 in which sodium sulfate is adsorbed, the cross-linking properties with rubber are improved by the adsorption of sodium sulfate, thereby reducing the hysteresis loss of the rubber The characteristics of the fuel efficiency substitution were also measured stably.

The abrasion performance is measured by a DIN abrasion tester, and the smaller the loss, the better. The wear amounts of Examples 1 and 2 were improved by about 5% and 20%, respectively, compared to the rubber application specimen of Comparative Example 1, in which general graphenes were applied, showing a remarkably improved effect.

&Lt; Examples 1 and 2 >

As shown in Table 1, a known additive for a tread rubber composition for a truck / bus and sodium sulfate adsorption graphene were added to 100 parts by weight of raw rubber (natural rubber) and vulcanized at 145 ° C for 40 minutes to prepare a rubber specimen.

&Lt; Comparative Example 1 &

As shown in Table 1, a known rubber / tread rubber composition additive and graphene were added to 100 parts by weight of raw rubber (natural rubber), and vulcanized at 145 ° C for 40 minutes to prepare a rubber specimen.

&Lt; Comparative Example 2 &

As shown in Table 1, an additive for a known tread rubber composition for a truck / bus was added to 100 parts by weight of raw rubber (natural rubber) and vulcanized at 145 DEG C for 40 minutes to prepare a rubber specimen.

Claims

Sodium sulfate absorbed graphene,
Wherein the graphene is contained in an amount of 1 to 20 parts by weight based on 100 parts by weight of the raw rubber.

The method according to claim 1,
Wherein the graphene comprises a hydrophilic group,
Wherein the hydrophilic group is covalently bonded to the sodium sulfate.

Grinding the graphene;
Oxidizing the ground graphene with an acidic aqueous solution; And
And adding a sodium polysulfite mixture to the acidic aqueous solution to obtain graphene adsorbing sodium sulfate.