KR20200065748A - Rubber composition for tire under tread and tire using the same - Google Patents

Abstract

The present invention relates to a rubber composition for tire under tread and a tire using the same. More particularly, the present invention relates to a rubber composition for tire under tread and a tire using the same, wherein the rubber composition comprises: 100 parts by weight of raw rubber; 50 to 85 parts by weight of carbon black; and 20 to 50 parts by weight of silica, wherein the raw rubber comprises 50 to 70 parts by weight of natural rubber, 20 to 50 parts by weight of styrene butadiene rubber and 10 to 30 parts by weight of butadiene rubber.

Description

Rubber composition for tire under tread and tire using the same {RUBBER COMPOSITION FOR TIRE UNDER TREAD AND TIRE USING THE SAME}

The present invention relates to a tire under tread rubber composition and a tire using the same, and relates to a tire under tread rubber composition having improved fatigue resistance and heat resistance and a tire using the same.

In very cold regions, such as parts of Northern Europe and North America, braking performance of the tire is particularly important because snow is formed in winter. In order to improve the braking performance of tires on snowy roads, soft rubber is often used on the tread.

When soft rubber is used in the tire tread portion as described above, handling performance may deteriorate somewhat. This problem can be compensated by using high-hardness rubber in the under tread portion.

However, if a rubber of high hardness is used in the under tread portion, the durability of the tire due to heat generation and the fuel efficiency of the vehicle may be reduced, which is a problem.

Accordingly, there is a need for research on a method for improving the fatigue resistance and heat generation characteristics of the tire under tread portion.

Accordingly, it is an object of the present invention to provide a rubber composition for tire under tread, which improves both fatigue resistance and heat resistance by using an appropriate amount of butadiene rubber for a raw rubber and using an appropriate amount of a silica reinforcing filler.

Another object of the present invention is to provide a tire having an under tread portion manufactured using the rubber composition for a tire under tread.

In order to achieve the above object, the rubber composition for tire under tread according to an aspect of the present invention includes: 100 parts by weight of raw rubber; Carbon black 50 to 85 parts by weight; And 20 to 50 parts by weight of silica, and the raw rubber comprises 50 to 70 parts by weight of natural rubber, 20 to 50 parts by weight of styrene butadiene rubber and 10 to 30 parts by weight of butadiene rubber.

Here, the silica may be 20 to 30 parts by weight.

In addition, the silica has a heating loss range of 4.0 to 7.0% under conditions heated for 2 hours at a temperature of 105°C, a specific surface area of CTAB adsorption is 148 to 172 m ² /g, and a hydrogen ion index of pH 5.8 to 7.2. , And may have a body residue of 10% or less at 325 mesh.

In addition, the butadiene rubber may be 10 to 20 parts by weight.

On the other hand, the tire according to another aspect of the present invention has an under tread portion manufactured using the rubber composition for a tire under tread according to the present invention described above.

According to the present invention, by including a specific content of butadiene rubber in the tire raw material rubber, by including a specific content of silica in the reinforcing filler, it is possible to simultaneously improve the fatigue resistance and heat resistance of the tire under tread portion.

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

Rubber composition for tire under tread according to an aspect of the present invention, raw material rubber 100 parts by weight; Carbon black 50 to 85 parts by weight; And 20 to 50 parts by weight of silica, and the raw rubber comprises 50 to 70 parts by weight of natural rubber, 20 to 50 parts by weight of styrene butadiene rubber and 10 to 30 parts by weight of butadiene rubber.

The raw material rubber of the conventional tire under tread rubber composition was made of natural rubber and styrene butadiene rubber, and the reinforcing filler was made of carbon black. Since the conventional rubber composition exhibits high hardness properties, tire durability due to heat generation And the fuel economy of automobiles could be a problem.

However, the rubber composition for tire under tread according to the present invention includes 10 to 30 parts by weight of butadiene rubber as a raw material rubber, preferably 10 to 20 parts by weight, thereby improving the fatigue resistance by adjusting the content of styrene butadiene rubber relatively less. It can be, and includes 20 to 50 parts by weight of silica as a reinforcing filler, preferably 20 to 30 parts by weight, so that the heat-resistant properties can be improved at the same time.

If the butadiene rubber as the raw material rubber is less than 10 parts by weight, there is a disadvantage that the effect of improving fatigue resistance is insufficient, and when it exceeds 30 parts by weight, there is a disadvantage that the implementation of high hardness properties may be insufficient.

And, if the silica as the reinforcing filler is less than 20 parts by weight, there is a disadvantage that the effect of improving heat generation performance is insufficient, and if it exceeds 50 parts by weight, it may be a problem due to too high hardness.

At this time, the butadiene rubber of the present invention, the content of cis-1,4 butadiene is 96% by weight or more, and a glass transition temperature (Tg) of -100 to -107°C is Gosis butadiene rubber (High Cis-Butadiene rubber) It may be, but is not limited to this.

In addition, the silica of the present invention has a heating loss range of 4.0 to 7.0%, a CTAB adsorption specific surface area of 148 to 172 m ² /g, and a hydrogen ion index at pH of 5.8 to 7.2 at a temperature of 105° C. for 2 hours. Is, 325 mesh (mesh) may be less than 10% body residue, but is not limited thereto. At this time, the silica may have a hydrogen ion index of pH 5.8 to 7.2, the silica having a hydrogen ion index of this range has the advantage that can be uniformly blended in the raw material rubber without the problem of lowering the physical properties of the raw material rubber.

On the other hand, the carbon black of the present invention, HAF-HS class iodine adsorption amount range is 85 to 95 mg/g, oil (DBP, paraffin oil) adsorption amount range is 117 to 127 cc/100g, coloration range is 107 to At 115%, 325 mesh (mesh), the body residue may be 0.1% or less, but is not limited thereto. At this time, if the oil adsorption amount range is less than 117 cc/100g, the reinforcing performance by the carbon black as a filler may be disadvantageous, and if it exceeds 127 cc/100g, the workability of the rubber composition may be deteriorated.

Representative examples of the carbon black are N110, N121, N134, N220, N231, N234, N242, N293, N299, S315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582 , N630, N642, N650, N683, N754, N762, N765, N774, N787, N907, N908, N990 or N991.

The carbon black may be included in an amount of 50 to 85 parts by weight based on 100 parts by weight of the raw material rubber. If the content of the carbon black is less than 50 parts by weight, the reinforcing performance by carbon black as a filler may decrease, and 85 parts by weight If exceeded, the processability of the rubber composition may be disadvantageous.

Meanwhile, the natural rubber of the present invention may be a general natural rubber or a modified natural rubber.

The general natural rubber may be any of those known as natural rubber, and the origin and the like are not limited. The natural rubber includes cis-1,4-polyisoprene as a main body, but may also include trans-1,4-polyisoprene depending on the required characteristics. Therefore, in addition to natural rubber containing cis-1,4-polyisoprene as a main body, natural rubber containing trans-1,4-isoprene as a main body, such as Valata, which is a kind of rubber from Sapota family in South America, is mainly used as the main rubber. Rubber may also be included.

In addition, the modified natural rubber means that the general natural rubber is modified or purified. For example, the modified natural rubber includes epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), and hydrogenated natural rubber.

Further, the styrene butadiene rubber (SBR) of the present invention may have a styrene content of 20 to 28% by weight, and a glass transition temperature (Tg) of about -58 to -45°C. When using the styrene content and the glass transition temperature range, there is an advantageous effect in terms of fuel efficiency, abrasion performance and braking performance.

Meanwhile, the rubber composition for tire under tread of the present application may further include various additives such as additional vulcanizing agents, vulcanization accelerators, vulcanization accelerators, anti-aging agents, softeners or adhesives. Any of the various additives may be used as long as they are commonly used in the field to which the present invention pertains, and their content is not particularly limited as it is in accordance with the compounding ratio used in the conventional rubber composition for tire under tread.

As the vulcanizing agent, a sulfur-based vulcanizing agent can be preferably used. The sulfur-based vulcanizing agent may use inorganic vulcanizing agents such as powdered sulfur (S), insoluble sulfur (S), precipitated sulfur (S), and colloidal sulfur. Specifically, the sulfur-based vulcanizing agent may be elemental sulfur or a vulcanizing agent that produces sulfur, for example, amine disulfide, polymer sulfur, and the like.

The vulcanizing agent is preferably included in 0.5 to 4.0 parts by weight based on 100 parts by weight of the raw material rubber, in that it is less sensitive to heat and chemically stable as a suitable vulcanizing effect.

The vulcanization accelerator refers to an accelerator that accelerates the vulcanization rate or accelerates the delaying action in the initial vulcanization step.

The vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic, aldehyde-amine, aldehyde-ammonia, imidazoline, xanthate, and Any one selected from the group consisting of combinations can be used.

Examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazolesulfenamide (CBS), N-tert-butyl-2-benzothiazolesulfenamide (TBBS), and N,N-dicyclohexyl Any one selected from the group consisting of -2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N,N-diisopropyl-2-benzothiazole sulfenamide and combinations thereof The sulfenamide-based compound can be used.

Examples of the thiazole-based vulcanization accelerator include 2-mercaptobenzothiazole (MBT), dibenzothiazole disulfide (MBTS), sodium salt of 2-mercaptobenzothiazole, and zinc salt of 2-mercaptobenzothiazole. , Copper salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-di Ethyl 4-morpholinothio) benzothiazole and any thiazole-based compound selected from the group consisting of these can be used.

Examples of the thiuram-based vulcanization accelerator include tetramethyl thiuram disulfide (TMTD), tetraethyl thiuram disulfide, tetramethyl thiuram monosulfide, dipentamethylene thiuram disulfide, dipentamethylene thiuram monosulfide, and dipentamethylene. Thiuram tetrasulfide, dipentamethylene thiuram hexasulfide, tetrabutyl thiuram disulfide, pentamethylene thiuram tetrasulfide, and combinations thereof can be used.

The thiourea vulcanization accelerator may be any thiourea system selected from the group consisting of thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea, and combinations thereof. Compounds can be used.

As the guanidine-based vulcanization accelerator, any one guanidine-based compound selected from the group consisting of diphenylguanidine, diorthotolylguanidine, triphenylguanidine, orthotolylbiguanide, diphenylguanidine phthalate, and combinations thereof can be used. Can be.

Examples of the dithiocarbamic acid-based vulcanization accelerator include zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, Zinc dibutyldithiocarbamate, zinc diamyldithiocarbamate, zinc dipropyldithiocarbamate, zinc pentamethylenedithiocarbamate and piperidine, hexadecyl isopropyldithiocarbamate, zinc octadecyl Zinc isopropyldithiocarbamate dibenzyldithiocarbamate zinc, diethyldithiocarbamate sodium, pentamethylenedithiocarbamate piperidine, dimethyldithiocarbamate selenium, diethyldithiocarbamate tellurium, dia Any dithiocarbamate-based compound selected from the group consisting of cadmium mildiocarbamate and combinations thereof can be used.

The aldehyde-amine or aldehyde-ammonia-based vulcanization accelerator may be, for example, an aldehyde selected from the group consisting of acetaldehyde-aniline reactant, butylaldehyde-aniline condensate, hexamethylenetetramine, acetaldehyde-ammonia reactant, and combinations thereof. -Amine-based or aldehyde-ammonia-based compounds can be used.

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

The vulcanization accelerator may be included in an amount of 0.5 to 4.0 parts by weight based on 100 parts by weight of the raw material rubber to maximize productivity and rubber properties through acceleration of vulcanization.

On the other hand, the vulcanization accelerator is used in combination with the vulcanization accelerator to complete its accelerating effect, and any one selected from the group consisting of inorganic vulcanization accelerators, organic vulcanization accelerators, and combinations thereof may be used. Can be.

As the inorganic vulcanization accelerator, any one selected from the group consisting of zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide, and combinations thereof can be used. have. The organic vulcanization accelerator is selected from the group consisting of stearic acid, zinc stearate, palmitic acid, linoleic acid, oleic acid, lauric acid, dibutyl ammonium oleate, derivatives thereof, and combinations thereof. Any one can be used.

In particular, the zinc oxide and the stearic acid may be used together as the vulcanization accelerator, and in this case, the zinc oxide is dissolved in the stearic acid to form an effective complex with the vulcanization accelerator, thereby releasing advantageous sulfur during the vulcanization reaction. By making it, the crosslinking reaction of the rubber is facilitated.

When the zinc oxide and the stearic acid are used together, they may be used in an amount of 1 to 5 parts by weight and 0.5 to 3 parts by weight with respect to 100 parts by weight of the raw material rubber, respectively, in order to serve as an appropriate vulcanization accelerator. When the content of the zinc oxide and the stearic acid is less than the above range, the vulcanization rate may be slow and productivity may be lowered.

Meanwhile, the anti-aging agent is an additive used to stop the chain reaction in which the tire is automatically oxidized by oxygen. As the anti-aging agent, any one selected from the group consisting of amine-based, phenol-based, quinoline-based, imidazole-based, carbamic acid metal salts, waxes, and combinations thereof can be appropriately selected and used.

Examples of the amine-based anti-aging agent include N-phenyl-N'-(1,3-dimethyl)-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-diaryl-p-phenylenediamine, N-phenyl-N' Any one selected from the group consisting of -cyclohexyl p-phenylenediamine, N-phenyl-N'-octyl-p-phenylenediamine and combinations thereof can be used. The phenol-based anti-aging agent is phenol-based 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), 2,2'-isobutylidene-bis (4,6-dimethylphenol), 2 Any one selected from the group consisting of ,6-di-t-butyl-p-cresol and combinations thereof can be used. As the quinoline-based anti-aging agent, 2,2,4-trimethyl-1,2-dihydroquinoline and derivatives thereof may be used, and specifically, 6-ethoxy-2,2,4-trimethyl-1,2-di Consisting of hydroquinoline, 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline, 6-dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline and combinations thereof Any one selected from the group can be used. As the wax, waxy hydrocarbon may be preferably used.

And, considering the conditions such as the anti-aging agent has a high solubility in rubber in addition to the anti-aging action, small volatility, inertness to the rubber, and should not inhibit vulcanization, 1 to 100 parts by weight of the raw rubber To 10 parts by weight.

Meanwhile, the softener is added to a rubber composition to impart plasticity to the rubber to facilitate processing or to lower the hardness of the vulcanized rubber, and refers to oils and other materials used in rubber compounding or rubber production. The softener refers to oils included in process oils or other rubber compositions. As the softener, any one selected from the group consisting of petroleum-based oils, vegetable oils and combinations thereof may be used, but is not limited thereto.

As the petroleum oil, any one selected from the group consisting of paraffin oil, naphthenic oil, aromatic oil, and combinations thereof can be used.

Representative examples of the paraffinic oils include P-1, P-2, P-3, P-4, P-5, P-6, etc. of Michang Oil Co., Ltd., and typical examples of the naphthenic oils are Michang Oil N-1, N-2, N-3, etc. of Co., Ltd., and typical examples of the aromatic oils include A-2, A-3, etc. of Michang Oil Co., Ltd.

However, when the content of polycyclic aromatic hydrocarbons (hereinafter referred to as PAHs) contained in the aromatic oil is more than 3% by weight with increasing environmental awareness, it is known that cancer-causing potential is high, TDAE (treated distillate aromatic extract) oil, MES (mild extraction solvate) oil, RAE (residual aromatic extract) oil or heavy naphthenic oil can be preferably used.

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

The TDAE oil has excellent properties for environmental factors such as cancer inducibility of PAHs while improving the low-temperature characteristics and fuel efficiency of the tire under tread including the TDAE oil.

The vegetable oils include castor oil, cottonseed oil, linseed oil, canola oil, soybean oil, palm oil, palm oil, peanut oil, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil , Jojoba oil, macadamia nut oil, sage flower oil, copper oil, and any one selected from the group consisting of combinations thereof.

The softener is preferably used in an amount of 0 to 20 parts by weight based on 100 parts by weight of the raw material rubber, in order to improve the processability of the raw material rubber.

In addition, the adhesive further improves the tack performance between the rubber and the rubber, and improves the properties of the rubber composition by improving the mixability, dispersibility and processability of other additives such as fillers.

As the adhesive, a natural resin-based adhesive such as rosin-based resin or terpene-based resin and synthetic resin-based adhesive such as petroleum resin, coal tar, or alkyl phenol-based resin may be used.

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

The petroleum resin is an aliphatic resin, acid-modified aliphatic resin, alicyclic resin, hydrogenated alicyclic resin, aromatic (C9) resin, hydrogenated aromatic resin, C5-C9 copolymer resin, styrene resin, styrene copolymer resin and It may be any one selected from the group consisting of a combination of these.

The coal tar may be a coumarone-indene resin.

The alkyl phenol resin may be p-tert-alkyl phenol formaldehyde resin or resorcinol formaldehyde resin, and the p-tert-alkyl phenol formaldehyde resin may be p-tert-butyl-phenol formaldehyde resin, p-tert -Octyl-phenol formaldehyde and combinations thereof.

The pressure-sensitive adhesive may be included in 2 to 4 parts by weight based on 100 parts by weight of the raw rubber. If the content of the pressure-sensitive adhesive is less than 2 parts by weight based on 100 parts by weight of the raw rubber, the adhesive performance may be deteriorated, and if it exceeds 4 parts by weight, rubber properties may be deteriorated.

Meanwhile, the rubber composition for tire under tread is not limited to the under tread portion, and may be included in various rubber components constituting a tire such as a tread (tread cap and tread base). Examples of the rubber component include sidewalls, sidewall inserts, apexes, chafers, wire coats, or inner liners.

On the other hand, the tire according to another aspect of the present invention is characterized by having an under tread portion manufactured using the above-described rubber composition for tire under tread.

The tire may be a tire for a passenger car, a racing tire, an airplane tire, an agricultural machinery tire, an off-the-road tire, a truck tire or a bus tire. In addition, the tire may be a radial tire or a bias tire, and is preferably a radial tire.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

[Production Example: Preparation of rubber composition]

A rubber composition for tire under tread according to the following Examples and Comparative Examples was prepared using the composition shown in Table 1 below. The production of the rubber composition was in accordance with the conventional method for producing the rubber composition.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 1 Raw rubber NR ⁽¹⁾ 50 60 60 50 50 70 SBR ⁽²⁾ 50 40 20 50 50 20 BR ⁽³⁾ - - 20 - - 10 Carbon Black ⁽⁴⁾ 85 85 85 50 50 50 Silica ⁽⁵⁾ - - - 20 30 20 Process oil ⁽⁶⁾ 5 5 5 5 5 5 Curing Agent ⁽⁷⁾ 2.8 2.8 2.8 2.8 2.8 2.8 Curing Accelerator ⁽⁸⁾ 1.6 1.6 1.6 1.6 1.6 1.6

(Unit: parts by weight)

(1) NR: TSR20 grade natural rubber

(2) SBR: glass transition temperature -47 ℃, styrene butadiene rubber with a styrene content of 23.5% by weight

(3) BR: neodymium-butadiene gobu (Nd-BR) having a glass transition temperature of -100°C

(4) Carbon black: Carbon black with an iodine adsorption value of 85 to 95 mg/g and an oil adsorption value of 117 to 127 cc/100g.

(5) Silica: Silica with a CTAB adsorption value of 148 to 172 m ² /g

(6) Process oil: TDAE (Treated Distillate Aromatic Extract) Oil

(7) Curing agent: sulfur (1% oil treated sulfur)

(8) Curing accelerator: CBZ (CZ, N-cyclohexyl-2-benzothiazolesulfenamide)

[Experimental Example: Measurement of physical properties of the prepared rubber composition]

The rubber specimens prepared in the above Examples and Comparative Examples were measured for vulcanization properties of tensile properties and viscoelasticity by vulcanization for 10 minutes at a 168°C vulcanizing press for the rubber specimens, and the results are shown in Table 2 below.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 1 Mooney viscosity (100℃) 76 81 88 90 108 99 T _max (160 ℃) 43.8 43.9 44.9 32.6 32.4 30.2 t90 (160 ℃) 5.6 6.4 5.3 7.1 8.1 5.8 Hardness (Shore A) 78 79 77 72 75 70 200% modulus (kgf/cm ² ) 164 167 149 123 127 130 60℃ tanδ 0.141 0.152 0.154 0.139 0.157 0.137 Fatigue Performance Index 100 159 344 72 85 233

In Table 2, Mooney viscosity (ML1+4 (100°C)) was measured according to ASTM standard D1646. The Mooney viscosity is a value indicating the viscosity of the uncured rubber, and the lower the value, the better the workability of the uncured rubber.

T _max (160°C), t90 (160°C): Measured by MDR measurement equipment, T _max is the maximum time taken to rise 5 points from the minimum value, and t90 is the time taken to rise 90 points.

Hardness was measured according to DIN 53505. Hardness indicates steering stability. The higher the value, the better the steering stability.

200% modulus was measured according to ISO 37 standard.

Viscoelasticity was measured under a 10 Hz frequency at 5% strain using an ARES meter.

The fatigue resistance is a value that indicates the number of cracks or breaks in the specimen due to the accumulated fatigue in the specimen, when the dumbbell-type specimen is repeatedly fatigued, and the higher the value, the better the fatigue performance.

Referring to Table 1 and Table 2, in the case of Comparative Example 2 and Comparative Example 3, there is a difference in the use of butadiene rubber. Instead of 40 parts by weight of SBR (Comparative Example 2), 20 parts by weight of SBR and 20 parts of butadiene rubber When the negative (Comparative Example 3) was used, it can be seen that the fatigue resistance index, which is one of the important characteristics of the rubber for under tread, is greatly improved.

In addition, when comparing Comparative Examples 4 and 5 and Comparative Example 1 in which a certain amount of carbon black was replaced with silica, Comparative Example 1 used 85 parts by weight of carbon black as a filler, while Comparative Example 4 used 50 parts by weight of carbon black and 20 silica. By weight, only 70 parts by weight in total was used, and Comparative Example 5 used only 50 parts by weight of carbon black and 30 parts by weight of silica, and 80 parts by weight in total. At this time, the tan δ value of 60° C. was measured to be 0.141 for Comparative Example 1, 0.139 for Comparative Example 4, and 0.157 for Comparative Example 5, although Comparative Example 4 had 15 parts by weight of filler less than Comparative Example 1 Then, the value of the heat-resistant property, that is, the tanδ value of 60° C. was measured almost the same. And, even though the total amount of the filler in Comparative Example 5 was less than that in Comparative Example 1, it was seen that the tanδ value was improved at 60° C., and when a certain amount of carbon black was replaced with silica as a reinforcing filler, the rubber for under tread It can be seen that the heat-resistant performance can be further improved.

Furthermore, Example 1 includes 10 parts by weight of butadiene rubber and 20 parts by weight of silica, and in this case, it can be confirmed that both fatigue resistance and heat resistance were appropriately improved.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (5)

100 parts by weight of raw rubber;
Carbon black 50 to 85 parts by weight; And
20 to 50 parts by weight of silica,
The raw rubber is a rubber composition for tire under tread comprising 50 to 70 parts by weight of natural rubber, 20 to 50 parts by weight of styrene butadiene rubber and 10 to 30 parts by weight of butadiene rubber. According to claim 1,
The silica is a rubber composition for tire under tread, characterized in that 20 to 30 parts by weight. According to claim 1,
The silica has a heating loss range of 4.0 to 7.0% under conditions heated for 2 hours at a temperature of 105° C., a specific surface area of CTAB adsorption is 148 to 172 m ² /g, and a hydrogen ion index of pH 5.8 to 7.2, Rubber composition for tire under tread, characterized in that the body residue in the 325 mesh is 10% or less. According to claim 1,
The butadiene rubber is a rubber composition for tire under tread, characterized in that 10 to 20 parts by weight. A tire having an under tread portion manufactured using the rubber composition for a tire under tread according to any one of claims 1 to 4.