KR101509478B1 - Method of manufacturing rubber for tire tread comprising silica of controlled moisture contents and rubber compositions - Google Patents

Abstract

The present invention relates to a method for producing a rubber for a tire tread, comprising the steps of: introducing a raw material rubber into a mixture of silica and other additives having a controlled moisture content at an initial temperature of 40 to 80 캜; Holding 135 to 160 캜 for 240 seconds or more while maintaining a shear rate of 20 to 60 rpm and an energy of shear stress of 350 to 1,000 kJ / kg; And supplying the energy for 300 seconds to 800 seconds and kneading the silica. The present invention also provides a method for producing a rubber for a tire tread.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a rubber for tire tread including silica having a controlled moisture content,

The present invention relates to a method and a composition for producing a rubber for tire tread comprising silica having a controlled moisture content, and more particularly, to a tread rubber composition comprising a reinforcing filler and having a water content adjusted to 3 wt% The present invention relates to a method and a composition for producing a rubber for a tire tread in which improved mechanical properties, process stability, and productivity are simultaneously improved by incorporating the obtained silica through an optimal kneading method.

The filler used in tires was used for the purpose of reducing the manufacturing cost within the range that does not affect the physical properties of the original rubber, but it was used as an important material to improve the characteristics of the rubber, .

The main reason why carbon black is most widely used as a reinforcing filler for rubber is that it is easy to control physical properties of rubber compound and contributes to improvement of rubber properties such as mechanical properties, wear and fatigue characteristics, It plays a role as a reinforcing agent.

Silica has been widely used as a material for tires from the past for the purpose of improving the cut and chip characteristics of winter tires and unpacked tires, or applying heat to kakas or belt layers to reduce heat generation.

The use of silica as a reinforcing filler in the tread area of tires for passenger cars has begun to be used in earnest to prevent air pollution caused by depletion of natural resources such as fossil fuels, coal and oil, carbon dioxide emitted from automobile exhaust gas, and global warming phenomenon The automotive fuel economy has become one of the important performance characteristics of the vehicle.

When applied to rubber formulations, the silica has the characteristics of improved friction and hysteresis on wet roads, although the reinforcing effect and abrasion resistance are reduced compared to carbon black of the same particle size.

It is the same as carbon black in which silica is gathered in aggregate in the form of particles, but the main reason for this characteristic is that the surface is hydrated. Therefore, the silica showing hydrophilicity is not mixed well with the hydrophobic rubber, and the silica has a disadvantage in that the dispersibility is lowered because the silica is well aggregated. Therefore, in order to improve the dispersibility of the silica rubber compound, a silane coupling agent that connects rubber and silica is inevitably required.

The use of silane coupling agents shows a significant improvement in the case of the deterioration of the dispersibility and physical properties which are disadvantages of the rubber compounds to which silica is applied. However, in order for the silane coupling agent to chemically react with the silica surface, an optimal condition of about 140 to 160 ° C. is required. When the temperature exceeds this range, the sulfur contained in the silane coupling agent exists as free sulfur in the mixing process There is a risk of scorch (precarge), so fine temperature control is needed. There is also a problem that the productivity of the tire is deteriorated due to the delay of the vulcanization due to the adsorption of the silica surface and the vulcanization accelerators.

As a solution to this, a method in which a glycol or a glycol derivative is added in order to inhibit the reaction with the promoter to induce a reaction with the silanol group on the surface of the silica, thereby preventing the amine-based promoter from being adsorbed on the silica surface.

In addition, there is a problem that bubbles are generated in the final rubber product by the ethanol generated as a byproduct of the silica itself and moisture in the silica silane reaction. Therefore, in the case of the tire finished product, additional vulcanization time is required to remove moisture and bubbles, It also causes a problem of deterioration.

Generally, precipitated silica used as a reinforcing filler is prepared by heating a high-purity sand with Na ₂ CO _{3 at} high temperature to make a watery state, adding an acid to the solution, and washing the precipitate through an acid- And drying process. Therefore, the precipitated silica generally contains about 5 wt% of water. The most expensive part of the manufacturing process is the product drying process, which requires a certain amount of water to react with the silica silane, so that the drying process does not proceed any further.

On the other hand, in the prior art using precipitated silica having a controlled moisture content, U.S. Patent No. 3,867,326 discloses a method for producing a vulcanized rubber by using a mixture of silica having an extremely limited moisture content and a polyethylenimine which is a polar polymer auxiliary agent (Adjuvant) A rubber composition having improved reinforcing properties, wear characteristics, heat generation properties and viscoelastic properties due to improvement in dispersibility is disclosed. However, in the above invention, a mixture of a polar polymer auxiliary agent for improving dispersibility was used for the silica subjected to dehydration treatment.

Accordingly, the present inventors have studied a method of solving the problems of the prior art as described above, and have studied a method capable of improving dispersibility and other properties without using a polar polymer auxiliary, and in the case of silica, It is difficult to maintain the silica property when the moisture content is 0 wt%, and the silica surface and the vulcanization accelerator may combine to affect the vulcanization characteristics. The reinforcing filler It has been found that when the silica having a moisture content of 3 wt% or less relative to the weight of silica is applied to the tire tread rubber composition using silica by the optimized kneading method, the vulcanization time is shortened through the control of moisture and air bubbles, Fuel ratio characteristics can be improved and the present invention has been completed.

The present invention provides a method and a composition for producing a rubber for a tire tread, which comprises silica having a controlled moisture content relative to the weight of silica to improve productivity as well as mechanical properties of the rubber composition using silica as a reinforcing filler.

According to an aspect of the present invention, there is provided a method of manufacturing a rubber for a tire tread,

Introducing a mixture of silica and other additives having controlled moisture content in the raw rubber at an initial temperature of 40 to 80 DEG C;

Holding 135 to 160 캜 for 240 seconds or more while maintaining a shear rate of 20 to 60 rpm and an energy of shear stress of 350 to 1,000 kJ / kg; And

And supplying the energy for 300 seconds to 800 seconds for kneading. The present invention also provides a method for manufacturing a rubber for a tire tread.

In the method for producing a rubber for a tire tread according to the present invention, it is preferable that the silica having a controlled moisture content has a specific surface area of 40 to 600 m ² / g and the water content is 3 wt% or less with respect to the weight of silica.

In order to achieve the above object, the present invention provides a rubber composition for a tire tread, wherein 100 parts by weight of a raw rubber containing one or two or more selected from natural rubber and synthetic rubber has a moisture content controlled by a reinforcing filler Wherein at least 20 parts by weight of the silica is contained in the tread rubber composition.

In the rubber composition for a tire tread according to the present invention, it is preferable that the silica having a controlled moisture content has a moisture content of 3 wt% or less with respect to the weight of silica and a specific surface area of 40 to 600 m ² / g.

According to the present invention, the rubber for tire treads prepared by adding silica as a reinforcing filler by adjusting the content of water to 3 wt% or less based on the weight of silica is kneaded under the optimum mixing condition, Workability, productivity and mechanical properties are improved by solving the problem of vulcanization delay.

Further, the present invention provides a rubber for a tire tread having improved mechanical properties and productivity, thereby enhancing the performance and productivity of the tire.

1 is a graph showing the relationship between the vulcanization time and the tensile properties according to the moisture content of silica in the rubber composition.
2 is a schematic view showing a mold used in a blow point analyzer.
3 is a photograph showing the results of measurement of the blow points of the rubber specimens obtained in Comparative Examples 1 to 3 and Example 3. Fig.
4 is a photograph showing the results of measurement of the blow points of Comparative Example 6 and Example 5. Fig.

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

The present invention also relates to a process for the production of a rubber for tire treads, comprising the steps of: introducing into the raw rubber a mixture of silica and other additives with controlled moisture content at an initial temperature of from 40 to 80 캜; Holding 135 to 160 캜 for 240 seconds or more while maintaining a shear rate of 20 to 60 rpm and an energy of shear stress of 350 to 1,000 kJ / kg; And supplying the energy for 300 to 800 seconds and kneading the rubber. The present invention also provides a method for producing rubber for tire tread,

When the shear rate is less than 20 rpm and / or the shear stress is less than 350 kJ / kg in the melt mixing of the raw rubber, the silica with the moisture content controlled silica and other additives, the rate of temperature rise of the raw rubber is low, When the shear rate exceeds 60 rpm and / or the shear stress exceeds 1,000 kJ / kg, the temperature of the mixture rapidly rises, causing the deterioration of the raw rubber and the scorch due to the sulfur contained in the silane coupling agent Scorch, and early vulcanization). Therefore, a mixture of raw rubber, silica having a controlled moisture content and other additives is prepared by adding silica and other additives whose moisture content is controlled to the molten rubber at an initial temperature of 40 to 80 ° C by using an internal mixer and measuring a shear rate of 20 to 60 rpm And holding the energy of the shear stress of 350 to 1000 kJ / kg at 135 to 160 DEG C for 240 seconds or more.

Then, the energy is supplied and kneaded for 300 to 800 seconds. In the case of mixing less than 300 seconds, excellent rubber properties due to insufficient dispersion of rubber and silica and lack of reaction time between silica and silane coupling agent can not be expected. In case of 800 seconds or more, There is a risk that the sulfur contained in the silane coupling agent may cause a problem of scorch and that the molten rubber sticks to the wall surface of the inner mixer chamber and shear stress is not supplied.

The water content of the silica used as a reinforcing filler in the present invention can be confirmed by the change in weight before and after the adjustment, expressed as wt%.

In the water content controlled silica used as the reinforcing filler, the water content is adjusted to 3 wt% or less, preferably 0 wt% or more and / or 2 wt% or less. The specific surface area is not particularly limited, but is usually in the range of 40 to 600 m ² / g, preferably 70 to 300 m ² / g. The silica may be used singly or in combination of two or more kinds.

In the case of the rubber produced through the above-described production method, the uniformity of product performance is excellent.

The present invention relates to a tread rubber composition for a tire, which comprises at least 20 parts by weight of silica having a moisture content controlled by a reinforcing filler in 100 parts by weight of a raw rubber containing one kind or two or more kinds selected from natural rubber and synthetic rubber Which is a tread rubber composition for a tire.

In the rubber composition for a tire tread according to the present invention, the starting rubber may be any raw material that can be used as a raw material for a tread rubber composition for a tire, and preferably one or more selected from natural rubber and synthetic rubber Can be mixed and used.

The synthetic rubber may be selected from diene polymer synthetic rubber, diene copolymer synthetic rubber, nitrile rubber, butyl rubber, and ethylene-propylene rubber, and is preferably selected from polybutadiene rubber, styrene-butadiene rubber and polyisoprene rubber Is preferably selected.

 In the water content controlled silica used as the reinforcing filler, the water content is adjusted to 3 wt% or less, preferably 0 wt% or more and / or 2 wt% or less.

The specific surface area of the silica to be used as the reinforcing filler is not particularly limited, but it is usually in the range of 40 to 600 m ² / g, preferably 70 to 300 m ² / g, They may be used alone or in combination of two or more.

The silica having a controlled moisture content is not less than 20 parts by weight based on 100 parts by weight of the starting rubber, preferably not less than 30 parts by weight and / or not more than 140 parts by weight.

The present invention relates to a rubber composition for a tire tread comprising silica as a reinforcing filler, wherein silica having a moisture content of not more than 3 wt% based on the weight of silica is added as a reinforcing filler, It is possible to solve the problems involved in application of a general precipitated silica as a reinforcing filler, such as a vulcanization delay problem, and also to improve various physical properties at the same time.

In the rubber composition for a tire tread according to the present invention, in addition to the above-mentioned raw rubber, silica and resin, there may be used stearic acid, zincification, antioxidant, processing oil, processing aid vulcanizing agent and vulcanization accelerator The various additives may be appropriately selected as needed and used in a predetermined amount. However, since these are general components used in conventional tire rubber compositions, they are not essential components of the present invention, and therefore, detailed description thereof will be omitted.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

Example  One

80 parts by weight of silica B having a moisture content of 0.8% by weight based on the weight of silica and 12.8 parts by weight of a silane coupling agent X-50S as shown in the following Table 1 were charged into a rubber composition composed of 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution- And the other additives were added with reference to the contents shown in Table 2 below to prepare rubber specimens. At this time, the mixture of the raw rubber, the silica with the moisture content controlled, and the other additives is added to the molten rubber at an initial temperature of 60 ° C by using an internal mixer, and the silica and other additives whose moisture content is controlled are mixed, And held at 140 to 150 DEG C for 360 seconds while maintaining a shear stress of 550 to 750 kJ / kg, and discharged by kneading for 600 seconds at a shear rate of 50 rpm and a shear stress of 550 kJ / kg. The rubber composition containing silica with controlled moisture content was mixed in a roll mill at a roll surface temperature of 50 DEG C and a friction ratio of 1.3 to 1 for 5 minutes and then charged into an internal mixer to prepare zinc oxide, a vulcanizing agent, a vulcanization accelerator Were added and mixed to prepare a rubber for confirming the silica basic properties according to the moisture content. The moisture content of the silica with controlled moisture content is shown in Table 1.

Example  2

80 parts by weight of Silica C having a moisture content of 1.5% by weight based on the weight of silica and 12.8 parts by weight of a silane coupling agent X-50S were added to 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution-polymerized styrene-butadiene rubber, The rubber specimens were prepared in the same manner as in Example 1, with reference to the contents shown in Table 2 below.

Example  3

80 parts by weight of Silica D having a moisture content of 3.3% by weight based on the weight of silica and 12.8 parts by weight of a silane coupling agent X-50S based on 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution-polymerized styrene-butadiene rubber, The rubber specimens were prepared in the same manner as in Example 1, with reference to the contents shown in Table 2 below.

Comparative Example  One

80 parts by weight of silica A having a moisture content of 5.3% by weight based on the weight of silica and 12.8 parts by weight of a silane coupling agent X-50S based on 100 parts by weight of a raw material rubber composed of 100 parts by weight of a solution polymerized styrene-butadiene rubber, The rubber specimens were prepared in the same manner as in Example 1, with reference to the contents shown in Table 2. At this time, the mixture of the raw rubber, the silica with the moisture content controlled, and the other additives was kneaded at an initial temperature of 60 DEG C at a shear rate of 50 to 60 rpm and a shear stress of 550 to 750 kJ / kg for 300 seconds using an internal mixer to obtain 150 Lt; / RTI > The rubber composition containing the silica released above was mixed in a roll mill at a roll surface temperature of 50 ° C and a friction ratio of 1.3: 1 for 5 minutes, and then the mixture was placed in an internal mixer, and zinc oxide, a vulcanizing agent and a vulcanization accelerator were added thereto, A rubber was prepared to confirm the basic properties of silica according to the contents. The moisture content of the silica with controlled moisture content is shown in Table 1.

Comparative Example  2

80 parts by weight of Silica E having a water content of 8.3% by weight based on the weight of silica and 12.8 parts by weight of a silane coupling agent X-50S based on 100 parts by weight of a raw material rubber composed of 100 parts by weight of a solution polymerized styrene-butadiene rubber, The rubber specimens were prepared in the same manner as in Comparative Example 1, with reference to the contents shown in Table 2 below.

Comparative Example  3

80 parts by weight of silica F having a moisture content of 10.2% by weight based on the weight of silica and 12.8 parts by weight of a silane coupling agent X-50S based on 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution- The rubber specimens were prepared in the same manner as in Comparative Example 1, with reference to the contents shown in Table 2 below.

Comparative Example  4

82 parts by weight of silica A having a moisture content of 5.3% by weight based on the weight of silica and 12.8 parts by weight of a silane coupling agent X-50S based on 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution-polymerized styrene-butadiene rubber, The rubber specimens were prepared in the same manner as in Comparative Example 1, with reference to the contents shown in Table 2.

Comparative Example  5

84 parts by weight of Silica E having a water content of 8.3% by weight based on the weight of silica and 12.8 parts by weight of a silane coupling agent X-50S based on 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution- The rubber specimens were prepared in the same manner as in Comparative Example 1, with reference to the contents shown in Table 2 below.

Water content ( wt %) Silica A 5.3 Silica B 0.8 Silica C 1.5 Silica D 3.3 Silica E 8.3 Silica F 10.2

* The silica has a BET (Brunaeur, Emmet and Teller) specific surface area of 175 m ² / g.

* The moisture content of silica was determined by the change in weight before and after the adjustment, expressed in wt%.

division
( Weight portion ) Comparative Example
One Comparative Example
2 Comparative Example
3 Comparative Example
4 Comparative Example
5 Example
One Example
2 Example
3 ^* S- SBR  One 137.5 137.5 137.5 137.5 137.5 137.5 137.5 137.5 ^* Silica A [5.3 wt %] 80 - - 82 - - - - ^* Silica B [0.8 wt %] - - - - - 80 - - ^* Silica C [1.5 wt %] - - - - - - 80 - ^* Silica D [3.3 wt %] - - - - - - - 80 ^* Silica E [8.3 wt %] - 80 - - 84 - - - ^* Silica F [10.2 wt %] - - 80 - - - - - Stearic acid 2 2 2 2 2 2 2 2 Silane Coupling agent 12.8 12.8 12.8 12.8 12.8 12.8 12.8 12.8 oil - - - - - - - - Antioxidant - - - - - - - - Processing aid - - - - - - - - ^* Vulcanization accelerator 1 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 ^* Vulcanization accelerator 2 One One One One One One One One brimstone 2.1 2.1 2.1 2.1 2.1 2.1 2.1 2.1 Zincification 3 3 3 3 3 3 3 3

* S-SBR 1 is a solution-polymerized styrene butadiene rubber with a styrene content of 25% and an oil content of 27%. Therefore, when 137.5 phr is applied, the rubber is 100 phr.

* The silica has a BET (Brunaeur, Emmet and Teller) specific surface area of 175 m ² / g.

cf) silica [wt%] is the water content of silica.

* Vulnerability promoter 1 is N-cyclohexyl-2-benzothiazole sulfenamide (CZ).

* Vulnerability promoter 2 is 1,3-diphenylguanidine (DPG).

Example  4

40 parts by weight of silica C having a water content of 1.5 wt% based on the weight of silica, 6.5 parts by weight of a silane coupling agent X-50S, 47 parts by weight of carbon black N234 47 wt.% Based on 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution- And the other additives were added with reference to the contents shown in Table 3 below to prepare rubber specimens in the same manner as in Example 1. [

Example  5

40 parts by weight of silica D having a moisture content of 3.3% by weight based on 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution-polymerized styrene-butadiene rubber, 6.5 parts by weight of silane coupling agent X-50S, 47 parts by weight of carbon black N234 And the other additives were added with reference to the contents shown in Table 3 below to prepare rubber specimens in the same manner as in Example 1.

Comparative Example  6

40 parts by weight of silica A having a water content of 5.3 wt% based on the weight of silica, 6.5 parts by weight of a silane coupling agent X-50S, 47 parts by weight of carbon black N234 47 wt.% Based on 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution- And the other additives were added with reference to the contents shown in Table 3 below to prepare rubber specimens in the same manner as in Comparative Example 1.

Comparative Example  7

40 parts by weight of silica E having a water content of 8.3% by weight based on 100 parts by weight of a raw rubber composed of 100 parts by weight of a solution-polymerized styrene-butadiene rubber, 6.5 parts by weight of silane coupling agent X-50S, 47 parts by weight of carbon black N234 And the other additives were added with reference to the contents shown in Table 3 below to prepare rubber specimens in the same manner as in Comparative Example 1.

division
( Weight portion ) Comparative Example  6 Comparative Example  7 Example  4 Example  5 ^* S- SBR  One 82 82 82 82 ^* S- SBR  2 60 60 60 60 ^* Silica A [5.3 wt %] 40 - - - ^* Silica B [0.8 wt %] - - - - ^* Silica C [1.5 wt %] - - 40 - ^* Silica D [3.3 wt %] - - - 40 ^* Silica E [8.3 wt %] - 40 - - ^* Silica F [10.2 wt %] - - - - Carbon black 47 47 47 47 Stearic acid 2 2 2 2 Silane Coupling agent 6.5 6.5 6.5 6.5 oil 2 2 2 2 Antioxidant 5 5 5 5 Processing aid 2 2 2 2 ^* Vulcanization accelerator 1 1.5 1.5 1.5 1.5 ^* Vulcanization accelerator 2 One One One One brimstone 2.1 2.1 2.1 2.1 Zincification 3.5 3.5 3.5 3.5

* S-SBR 1 is a solution-polymerized styrene butadiene rubber with a styrene content of 25% and an oil content of 27%.

* S-SBR 2 is a solution-polymerized styrene butadiene rubber with a styrene content of 40% and an oil content of 33%.

* In the case of S-SBR 2, [33.333 ...%] oil is included. Therefore, 60 phr of S-SBR 1 is 60 phr and 82 phr of S-SBR 1 is 60 phr.

* The silica has a BET (Brunaeur, Emmet and Teller) specific surface area of 175 m ² / g.

cf) silica [wt%] water content of silica

* Vulnerability promoter 1 is N-cyclohexyl-2-benzothiazole sulfenamide (CZ).

* Vulnerability promoter 2 is 1,3-diphenylguanidine (DPG).

Test Example  One

The rubber compositions of Examples 1 to 3 and Comparative Examples 1 to 5 are rubber compositions for confirming the basic properties of silica. Particularly, in the case of Comparative Examples 4 to 5, the amount of the filler considering the moisture content is the same as that of Example 3 This is a comparative evaluation to confirm the characteristics of pure water content.

The rubber compositions of Examples 4 to 5 and Comparative Examples 6 to 7 are compositions for predicting and confirming tread properties.

The viscosity, vulcanization time, maximum torque and limit vulcanization time of each rubber composition were confirmed by rheometer and blowpoint analyzer measurement. The vulcanization characteristics were evaluated by pressing hot press for 15 minutes, And then tested for hardness, 300% modulus, tensile strength and elongation according to ASTM regulations. For the elastic modulus, a steel ball with a diameter of 15.88 mm (16.3 g) was dropped on a prepared rubber specimen using a steel ball rebound tester to measure the degree of springing. For the wear characteristics, the rubber specimens prepared using the WILLIAM abrasion tester were evaluated by changing the weight before and after the test under the condition of Abrasor having a diameter of 25.4 mm and a load of 1 kg at 37 rpm. In case of the heating characteristics, prepared using GOODRICH FLEXOMETER The rubber specimens were repeatedly compressed under constant load for a certain period of time, and then measured by ascertaining the temperature rise after 25 minutes.

For the convenience of the test; (1) Modulus of elasticity: 40 mm in diameter and 20 mm in height with hot press for 20 minutes, (2) WILLIAM abrasion: 50 mm X 25.4 mm X 25.4 mm in size with hot press for 20 minutes, (3) Heat characteristic: 17.8 mm in diameter and 25 mm in height The specimens were pressed with a hot press for 15 minutes, and specimens were produced from each mold. The test results were shown in Tables 4 and 5.

Comparative Example  One Comparative Example  2 Comparative Example  3 Comparative Example  4 Comparative Example  5 Example  One Example  2 Example  3 Leo
Meter T ₄₀ (minute) 6.6 6.2 6.0 6.5 6.5 4.5 4.8 5.3 group
system
enemy
water
castle Mooney  Viscosity 88 86 85 89 87 92 91 89 Hardness( Shore  A) 75 76 76 76 77 78 76 76 300% Modulus  ( kgf / Cm2) 123 130 133 129 134 138 137 132 The tensile strength  ( kgf / Cm2) 209 212 215 213 216 228 222 224 Elongation (%) 420 440 440 410 420 460 460 450 Modulus of elasticity  (%) 26.1 26.6 26.7 26.0 26.3 24.7 24.9 25.4 Heat generation characteristic (℃) 24.1 24.4 24.4 24.9 25.2 23.5 23.6 23.9 Wear characteristics (%) 0.61 0.64 0.72 0.60 0.62 0.54 0.55 0.58

In Table 4, the higher the value, the harder, and the higher the value for the tensile properties (300% modulus, tensile strength, elongation), the better the respective properties. In addition, the elastic modulus refers to the elasticity of the rubber specimen. The higher the elastic modulus, the greater the elasticity. The exothermic characteristic means the temperature of the specimen generated when the rubber specimen is repeatedly deformed for 25 minutes, Indicating excellent properties. In the case of the wear characteristics, it represents the ratio of the weight lost to the initial weight. The lower the value, the better the wear characteristic.

As a result of confirming the properties of Comparative Examples 1 to 5 and Examples 1 to 3, which are the rubber compositions for confirming the basic characteristics according to the silica water content, as shown in Table 4, which is the result of the test example, Comparative Examples 1 to 5 in which the rubber composition for tread was applied Comparative Examples 1 to 5 Comparative Examples 4 to 5 having excellent physical properties equal to or superior to those of the rubber in comparison with each other and confirming the characteristics of the filler content difference according to the water content were corrected And the results of the evaluation of the characteristics of Example 3 also showed that the physical properties and other characteristics were influenced by the water content rather than the effect of the filler.

Comparative Example  6 Comparative Example  7 Example  4 Example  5 Leo
Meter T ₄₀ (minute) 5.6 5.4 4.7 4.9 group
system
enemy
water
castle Mooney  Viscosity 68 66 72 70 Hardness( Shore  A) 73 73 73 73 300% Modulus  ( kgf / Cm2) 130 133 138 135 The tensile strength  ( kgf / Cm2) 202 210 215 213 Elongation (%) 470 470 480 480 Modulus of elasticity  (%) 20.1 20.5 20.7 20.4 Heat generation characteristic (℃) 38.0 37.5 36.6 36.8 Wear characteristics (%) 2.95 2.99 2.52 2.60

From the results of the above Table 5, the comparative evaluation results of Comparative Examples 6 to 7 and Examples 4 to 5 also confirmed the same characteristic tendency as that of the rubber composition for confirming the basic characteristics according to the silica water content. In the vulcanization time, Respectively.

Test Example  2

The rubber compositions of Comparative Examples 1 to 3 and Examples 1 to 3 were analyzed for the relationship between the vulcanization time and the tensile properties according to the water content, and the results are shown in Fig. According to FIG. 1, it was confirmed that an inflection point was formed at a moisture content of 3 wt% or less, the vulcanization time was shortened sharply, and the tensile properties were also improved. Especially, the vulcanization time (T40) was shortened up to 32% depending on the water content, and the heat generation characteristics were improved even though the elastic modulus was low. It is also expected that hysteresis (hysteresis) will be improved when the tire is applied through improving the heat generation characteristics.

For rubber compositions in general, it is common to determine the vulcanization time using a rheometer, but in the case of silica rubber formulations, time to remove bubbles generated by ethanol, which is a byproduct of moisture and silica silane reaction, must be considered So that additional vulcanization time is required compared to general rubber compounds. A recent Blow Point Analyzer is used to determine the vulcanization time of rubber compound. Blow point refers to the time at which the air bubbles disappear when the tire is vulcanized. By using vulcanized molds vulcanizing compounded rubber, the heat transfer rate is different according to the thickness difference of the rubber in the mold. Comparative Examples 1 to 3, which are rubber compositions for evaluating basic properties according to the silica moisture content, and Blow Point Analyzers (B-2 to B-3) The results of measuring points are shown in Fig.

According to FIG. 3, in the case of Comparative Examples 1 to 3, bubbles were observed at the third point of the uncrosslinked phase, and in Example 3, which was a tread rubber composition using silica with controlled moisture content, .

Similarly, the specimen for the blowpoint analysis was evaluated under a vulcanization condition of 160 ° C for 11 minutes, and the results of measurement of the blowpoints of the rubber compositions for tire treads of Comparative Example 6 and Example 5 are shown in FIG.

As a result of the evaluation, in Comparative Example 6, bubbles appearing at the unvulcanized phase were observed from the fourth point, and in Example 5, which is a tread rubber composition using silica with controlled moisture content, Respectively.

Therefore, when the silica having moisture content controlled in the rubber composition for a tire tread is applied as a reinforcing filler through the present invention, the tensile strength characteristics are improved without sacrificing other properties, and the productivity and economic efficiency The tire performance can be improved by improving the physical properties.

As described above, the tread rubber composition for a tire having improved rubber performance, productivity and economy is described as a preferred embodiment of the present invention. However, the present invention is not limited to the specific preferred embodiments described above. 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 in the appended claims and their equivalents. .

Claims (5)

A method of manufacturing a rubber for a tire tread,
30 to 140 parts by weight of silica having a controlled moisture content in 100 parts by weight of the starting rubber and a mixture of other additives at an initial temperature of 40 to 80 DEG C;
Maintaining 135-160 DEG C for 240 seconds or more while maintaining a shear rate of 20 to 60 rpm and an energy of shear stress of 350 to 1000 kJ / kg; And
And supplying and kneading the energy for 300 seconds to 800 seconds,
Wherein the silica having a controlled moisture content is not more than 3 wt% based on the weight of silica. The method according to claim 1,
Wherein the silica having a controlled moisture content has a specific surface area of 40 to 600 m ² / g. A tread rubber composition for a tire,
A rubber composition comprising 30 to 140 parts by weight of silica having a moisture content controlled by a reinforcing filler in 100 parts by weight of a raw rubber containing one or two or more selected from natural rubber and synthetic rubber,
The water content of the controlled silica is 3 wt% or less based on the weight of silica,
The tread rubber composition for a tire is characterized by comprising the steps of: injecting the raw rubber with a mixture of silica and other additives whose moisture content is controlled, at an initial temperature of 40 to 80 캜; Maintaining 135-160 DEG C for 240 seconds or more while maintaining a shear rate of 20 to 60 rpm and an energy of shear stress of 350 to 1000 kJ / kg; And supplying the energy for 300 seconds to 800 seconds and kneading the tire. The method of claim 3,
Wherein the silica having a controlled moisture content has a specific surface area in the range of 40 to 600 m ² / g. The method according to claim 1,
The rubber composition produced by the method for producing a rubber for a tire tread,
Characterized in that the vulcanization time is reduced by 16 to 32% by controlling the formation of bubbles.

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