JP2010043166A - Rubber composition for tread and tire using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a tread achieving high wear resistance, without impairing rolling resistance, and to provide a tread and a tire. <P>SOLUTION: A rubber composition for a tire tread contains, based on 100 pts.mass of a rubber component containing carboxy-modified acrylonitrile butadiene copolymer rubber obtained by copolymerization of a vinyl monomer containing a carboxy group, acrylonitrile and butadiene, 30-100 pts.mass of silica having nitrogen adsorption specific surface area of 50-500 m<SP>2</SP>/g according to BET method, and is vulcanized with sulfur. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber composition for a tire tread, a tread, and a tire, and particularly relates to a rubber composition for a tire tread, a tread, and a tire that can achieve both low rolling resistance and high wear resistance.

  Conventionally, the fuel consumption of a vehicle has been reduced by reducing the rolling resistance of a tire to suppress heat generation. In recent years, there has been an increasing demand for reducing fuel consumption of vehicles by using tires, and there is a particularly large demand for reducing fuel consumption by improving tread, which has a high occupation ratio among tire members.

  Thus, by adding silica to the tire tread rubber composition that forms the tire tread, rolling resistance is reduced and fuel efficiency is being reduced.

  However, since silica has a lower affinity for the rubber component than carbon black, the reinforcing effect of the rubber is small.

  Therefore, in order to make the silica reinforcing effect the same as that of carbon black, the silica reinforcing effect is increased by improving the dispersibility of the silica or chemically bonding the rubber component and the silica. At the same time, methods for reducing rolling resistance have been proposed as follows.

  In Patent Document 1, a tire tread is manufactured using a rubber composition for a tire tread to which a predetermined tin compound is added together with a diene rubber, silica, and a silane coupling agent, thereby reducing the fuel consumption of the vehicle. Technology is disclosed.

  In Patent Document 2, a tire tread is produced using a rubber composition for a tire tread containing an emulsion-polymerized rubber obtained by emulsion polymerization, silica and a silane coupling agent, thereby reducing the fuel consumption of the vehicle. Technology is disclosed.

  Patent Document 3 discloses a technology for reducing fuel consumption of a vehicle by producing a tire tread using a rubber composition for a tire tread in which two types of silica having different nitrogen adsorption specific surface areas are blended at a predetermined ratio. Has been.

  In a tire, it is desirable to improve rolling resistance from the viewpoint of reducing the rolling resistance and reducing the fuel consumption of the vehicle and extending the life of the tire.

However, the fuel efficiency reduction technology as described above can improve the rolling resistance of the tire, but there is a problem that the wear performance is deteriorated. Until now, a rubber composition for a tire tread that can achieve both low rolling resistance and high wear resistance of a tire has not been known.
Japanese Patent Laid-Open No. 11-181161 JP 2000-248120 A JP 2006-233177 A

  An object of the present invention is to provide a rubber composition for a tire tread, a tread, and a tire that can realize high wear resistance without deteriorating rolling resistance.

The present invention relates to a nitrogen adsorption specific surface area according to the BET method with respect to 100 parts by mass of a rubber component containing a carboxyl-modified acrylonitrile-butadiene copolymer rubber obtained by copolymerizing a vinyl monomer containing a carboxyl group, acrylonitrile and butadiene. It is a rubber composition for tire treads containing 30 to 100 parts by mass of silica having an A of 50 to 500 m ² / g and vulcanized with sulfur.

  In the tire tread rubber composition according to the present invention, the carboxyl-modified acrylonitrile-butadiene copolymer rubber preferably has an acrylonitrile copolymerization amount of 10 to 80% by mass.

  In the rubber composition for a tire tread according to the present invention, the content of the carboxyl-modified acrylonitrile-butadiene copolymer rubber in the rubber component is preferably 5 to 30% by mass.

  The rubber composition for a tire tread according to the present invention is preferably that obtained by hydrogenating the carboxyl-modified acrylonitrile-butadiene copolymer rubber.

The present invention is a tread formed from the rubber composition for a tire tread.
The present invention further relates to a tire manufactured using the tread.

  ADVANTAGE OF THE INVENTION According to this invention, the rubber composition for tire treads, a tread, and a tire which can obtain high abrasion resistance performance without deteriorating rolling resistance can be provided.

<Rubber composition>
The present invention relates to a rubber composition for a tire tread used for forming a tire tread, and a carboxyl-modified acrylonitrile-butadiene copolymer obtained by polymerizing a vinyl monomer having a carboxyl group, acrylonitrile and butadiene as a rubber component. Containing rubber (hereinafter also referred to as “carboxyl-modified NBR”) or hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber (hereinafter also referred to as “hydrogenated carboxyl-modified NBR”) in which the rubber is hydrogenated, and the rubber component It is a rubber composition for tire treads containing 30 to 100 parts by mass of silica having a nitrogen adsorption specific surface area of 50 to 500 m ² / g based on 100 parts by mass.

(Carboxyl-modified acrylonitrile-butadiene copolymer rubber)
The present invention provides an acrylonitrile-butadiene copolymer by using a carboxyl-modified acrylonitrile-butadiene copolymer rubber obtained by copolymerizing a vinyl monomer having a carboxyl group, which is considered to interact with silica, acrylonitrile, and butadiene. Dispersibility of silica can be improved more than that of coalescence, and at the same time, by strengthening the bond between silica and the rubber component, high wear resistance can be realized without deteriorating rolling resistance. A rubber composition for a tire tread can be produced. Furthermore, by using hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber obtained by hydrogenating carboxyl-modified acrylonitrile-butadiene copolymer rubber, higher wear resistance can be obtained.

  The amount of acrylonitrile copolymerization in the carboxyl-modified acrylonitrile-butadiene copolymer rubber and hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber used in the present invention is 10 to 80% by mass, preferably 25 to 80% by mass. If the acrylonitrile copolymerization amount is less than 10% by mass, it is not preferable because high wear resistance cannot be realized.

  In addition, the said acrylonitrile copolymerization amount can be measured by conventionally well-known methods, such as IR spectrum method, a gel Dahl method, or a gas chromatograph method, for example. In the present invention, the acrylonitrile copolymerization amount is the ratio of the mass of acrylonitrile to the total mass of the carboxyl-modified acrylonitrile-butadiene copolymer rubber and the hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber.

  In the rubber composition for a tire tread of the present invention, the rubber component is a mixture of a carboxyl-modified acrylonitrile-butadiene copolymer rubber, a hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber and a diene rubber usually used in other tires. It may be rubber. In this case, the content of the carboxyl-modified acrylonitrile-butadiene copolymer rubber and the hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber is 5 to 30% by mass, preferably 5 to 20% by mass in the rubber component. When the content is less than 5% by mass, high wear resistance cannot be realized, and when the content exceeds 30% by mass, rolling resistance is deteriorated.

  The vinyl monomer, acrylonitrile and butadiene containing the carboxyl group are blended so that the carboxyl group is 3-30 mol% in the carboxyl-modified acrylonitrile-butadiene copolymer rubber and the hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber. . Preferably, the carboxyl group content in the carboxyl-modified acrylonitrile-butadiene copolymer rubber and the hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber is 5 to 20 mol%.

  Examples of the vinyl monomer containing a carboxyl group include acrylic acid and methacrylic acid.

(Other rubber components)
Examples of the rubber other than the carboxyl-modified acrylonitrile-butadiene copolymer rubber and the hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber used in the present invention include natural rubber (NR), polyisoprene synthetic rubber (IR), and butadiene rubber. (BR), styrene butadiene copolymer rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR) and styrene-isoprene-butadiene copolymer rubber (SIBR). These rubbers may be used alone or in combination of two or more.

  Among these, from the viewpoint of ensuring sufficient tire strength and exhibiting excellent wear resistance, it is preferable to use a rubber mixture with NR, BR, and SBR as the rubber component used in the present invention. Here, as NR, SBR, and BR, for example, conventionally known ones can be used.

(silica)
As the silica used in the present invention, conventionally known silica can be used without limitation as long as it has a nitrogen adsorption specific surface area (N ₂ SA) of 50 to 500 m ² / g according to the BET method. Silica obtained by the method (anhydrous silica) and / or silica obtained by the wet method (hydrous silicic acid) can be used. Among these, silica (hydrous silicic acid) obtained by a wet method is preferable as the silica used in the present invention.

  Moreover, 30-100 mass parts of silica is contained with respect to 100 mass parts of said rubber components in the rubber composition for tire treads of this invention. Depending on the content, a rubber composition for a tire tread capable of realizing both low rolling resistance and high wear resistance can be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of the silica by the BET method is 50 to 500 m ² / g, particularly preferably 50 to 300 m ² / g. When the nitrogen adsorption specific surface area is less than 50 m ² / g, the fracture strength after vulcanization tends to decrease, and when it exceeds 500 m ² / g, the workability tends to deteriorate.

  In addition, the nitrogen adsorption specific surface area by BET method of a silica can be measured by the method based on ASTM-D-4820-93.

(Silane coupling agent)
When silica is blended, a silane coupling agent may be used in combination. Examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, and bis (2-triethoxy). Silylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyl Trimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarba Moyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilyl Propyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide And dimethoxymethylsilylpropylbenzothiazole tetrasulfide. Of these, bis (3-triethoxysilylpropyl) tetrasulfide and 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide are preferable from the viewpoint of improving reinforcing properties. These silane coupling agents may be used alone or in combination of two or more.

  The compounding amount of the silane coupling agent is preferably 1 part by mass or more and more preferably 2 parts by mass or more with respect to 100 parts by mass of the silica. If the compounding amount of the silane coupling agent is less than 1 part by mass, the viscosity of the unvulcanized rubber composition tends to be high and the processability tends to be poor. Moreover, it is preferable that it is 20 mass parts or less with respect to 100 mass parts of said silica, and, as for the compounding quantity of a silane coupling agent, it is more preferable that it is 15 mass parts or less. If the blending amount of the silane coupling agent exceeds 20 parts by mass, the blending effect of the silane coupling agent as much as the blending amount cannot be obtained, and the cost tends to increase.

(Vulcanization aid)
The tire rubber composition of the present invention may contain a vulcanization aid. As the vulcanization aid, stearic acid, zinc oxide (zinc white) or the like can be used.

  In the tire rubber composition of the present invention, various reinforcing agents, various oils, plasticizers, coupling agents, etc., various compounding agents and additives blended for tires or general rubber compositions are blended. Can do. Moreover, the content of these compounding agents and additives can also be set to general amounts. The rubber composition of the present invention thus obtained exhibits an excellent balance in processability, fuel efficiency and wet grip performance.

(Softener)
The tire rubber composition of the present invention may contain a softening agent. Softeners include petroleum-based softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt and petroleum jelly, and fatty oil-based softeners such as soybean oil, palm oil, castor oil, linseed oil, rapeseed oil and coconut oil. Agents, waxes such as tall oil, sub, beeswax, carnauba wax and lanolin, and fatty acids such as linoleic acid, palmitic acid, stearic acid and lauric acid. The blending amount of the softening agent is preferably 100 parts by mass or less with respect to 100 parts by mass of the rubber component, and in this case, there is a risk of reducing the wet grip performance when the rubber composition is used in a tire. Less is.

(Anti-aging agent)
The tire rubber composition of the present invention may contain an anti-aging agent. As the anti-aging agent, amine-based, phenol-based, and imidazole-based compounds, carbamic acid metal salts, waxes, and the like can be appropriately selected and used.

(Vulcanizing agent)
The tire rubber composition of the present invention may contain a vulcanizing agent. As the vulcanizing agent, an organic peroxide or a sulfur vulcanizing agent can be used. Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2, 5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne- 3 or 1,3-bis (t-butylperoxypropyl) benzene or the like can be used. Moreover, as a sulfur type vulcanizing agent, sulfur, morpholine disulfide, etc. can be used, for example. Of these, sulfur is preferred.

(Vulcanization accelerator)
The tire rubber composition of the present invention may contain a vulcanization accelerator. Vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, imidazoline, or xanthate vulcanization accelerators. Those containing at least one of them can be used.

(Other ingredients)
The rubber composition for tires of the present invention includes other reinforcing agents, vulcanizing agents, vulcanization accelerators, various oils, anti-aging agents, softeners, plasticizers, coupling agents, etc. for tires or general rubber compositions. Various compounding agents and additives blended in the product can be blended. Moreover, the content of these compounding agents and additives can also be set to general amounts.

<Method for producing rubber composition>
The rubber composition of the present invention can be produced by a conventionally known production method, and the production method is not limited. For example, it can be produced by kneading each of the above components using a kneading machine such as a Banbury mixer or a kneading roll under ordinary methods and conditions.

<Tire manufacturing method>
The method for producing a tire using the rubber composition of the present invention is not particularly limited. For example, the rubber composition of the present invention is extruded according to the shape of the tire member applied in the unvulcanized stage, A conventionally used method such as a method of obtaining a tire by pressing with a tire molding machine can be employed.

  The tire of the present invention thus obtained exhibits low fuel consumption and high wear resistance.

  Hereinafter, although concretely demonstrated based on the Example of this invention, this invention is not limited to these.

(Example 1-8, Comparative Example 1-3)
In accordance with the formulation shown in Tables 1 and 2, rubber components, silica, coupling agents, softeners (stearic acid), vulcanization aids (zinc oxide) and anti-aging agents are used in various compounding agents using 1.7 L Banbury. And kneaded for 4 minutes. Furthermore, a vulcanizing agent (sulfur) and a vulcanization accelerator were kneaded using a roll to obtain various unvulcanized rubber sheets. The resulting rubber composition was press vulcanized at 170 ° C. for 15 minutes to obtain a vulcanized product. Each obtained vulcanizate was tested for the following characteristics.

<Rolling resistance test>
Test pieces were prepared from the respective vulcanized rubber sheets of Example 1-8 and Comparative Example 1-3, and using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), temperature 30 ° C., initial strain 10%. The loss tangent (tan δ) was measured under the condition of 2% dynamic strain. The results are shown in the column of rolling resistance index in Tables 1 and 2.

  The numerical value in the column of rolling resistance index in Table 1 is the loss tangent (tan δ) of the test piece made of the vulcanized rubber sheet of Comparative Example 1, and the numerical value in the column of rolling resistance index in Table 2 is that of Comparative Example 3. The loss tangent (tan δ) of a test piece made of a vulcanized rubber sheet is taken as 100 and is calculated by the following formula. Therefore, the larger the value of the rolling resistance index is, the smaller the rolling resistance is, indicating that fuel consumption can be reduced.

(Rolling resistance index) = 100 × (loss tangent (tan δ) of Comparative Example 1) / (loss tangent (tan δ) of Examples 1-3 and Comparative Example 1)
(Rolling resistance index) = 100 × (loss tangent (tan δ) of Comparative Example 2) / (loss tangent (tan δ) of each of Example 4-8 and Comparative Example 2-3)
<Abrasion resistance test>
A test piece was prepared from each vulcanized rubber sheet of Example 1-8 and Comparative Example 1-3, and using a Lambone abrasion tester, Lambone was tested under the conditions of a temperature of 20 ° C., a slip rate of 20%, and a test time of 5 minutes. The amount of wear was measured and the volume loss was measured. The results are shown in the wear index column of Tables 1 and 2.

  The numerical values in the column of wear index in Table 1 are the volume loss amount of the test piece made of the vulcanized rubber sheet of Comparative Example 1, and the numerical values in the column of wear index in Table 2 are the vulcanized rubber sheet of Comparative Example 3. The volume loss amount of the test piece made of Therefore, it shows that it is excellent in abrasion resistance, so that the numerical value of an abrasion index is large.

(Wear index) = 100 × (Volume loss amount of Comparative Example 1) / (Volume loss amounts of Examples 1-3 and Comparative Example 1)
(Abrasion index) = 100 × (volume loss amount of comparative example 2) / (volume loss amounts of examples 4-8 and comparative example 2-3)

Below, various chemical | medical agents used by the Example and the comparative example are demonstrated.
Carboxyl-modified NBR (1): NIPOL 1072J manufactured by Nippon Zeon Co., Ltd. (carboxyl-modified acrylonitrile-butadiene copolymer rubber, acrylonitrile copolymerization amount: 27% by mass)
Carboxyl-modified NBR (2): NIPOL DN631 (carboxyl-modified acrylonitrile-butadiene copolymer rubber, acrylonitrile copolymerization amount: 33.5% by mass) manufactured by Nippon Zeon Co., Ltd.
Hydrogenated carboxyl-modified NBR: VPKA8889 manufactured by LANXESS (hydrogenated carboxyl-modified acrylonitrile-butadiene copolymer rubber, acrylonitrile copolymerization amount: 35% by mass)
NBR: NIPOL 1042 manufactured by Nippon Zeon Co., Ltd. (acrylonitrile-butadiene copolymer rubber, acrylonitrile copolymerization amount: 33.5% by mass)
SBR: NS116 manufactured by JSR Corporation (vinyl content: 60%, styrene content: 20%)
NR: RSS # 3
Silica: ULTRASIL VN3 (Nitrogen adsorption specific surface area: 175 m ² / g) manufactured by Tegusa
Silane coupling agent: Si266 manufactured by Tegussa
Vulcanizing aid: Zinc Hua 1 (Zinc Oxide) manufactured by Mitsui Mining & Smelting Co., Ltd.
Softener: Koji (stearic acid) manufactured by NOF Corporation
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Vulcanizing agent: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanizing accelerator (1): Noxeller NS (N-tert-butyl-2-benzothiazolylsulfanamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator (2): Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
(Evaluation results)
Table 1 shows the results when carboxyl-modified NBR, hydrogenated carboxyl-modified NBR or NBR is used alone. Examples 1 and 2 are rubber compositions using carboxyl-modified NBR. Compared to Comparative Example 1 using ordinary NBR, Example 1 has the same rolling resistance performance and improved wear resistance performance, and Example 2 improved both the rolling resistance performance and the wear resistance performance. Example 3 is a rubber composition using hydrogenated carboxyl-modified NBR. Compared to Comparative Example 1, both rolling resistance performance and wear resistance performance were improved.

  Table 2 shows the results of carboxyl-modified NBR, hydrogenated carboxyl-modified NBR, or a blend formulation of NBR and SBR and NR. Examples 4 to 6 are rubber compositions blended with carboxyl-modified NBR. Compared with Comparative Examples 2 and 3 using normal NBR, Examples 4 and 5 have the same rolling resistance performance and improved wear resistance performance, and Example 6 has improved both rolling resistance performance and wear resistance performance. did. Examples 7 and 8 are rubber compositions obtained by blending hydrogenated carboxyl-modified NBR, and both rolling resistance performance and wear resistance performance were improved as compared with Comparative Examples 2 and 3.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (6)

The nitrogen adsorption specific surface area by the BET method is 50 to 500 m with respect to 100 parts by mass of a rubber component containing a carboxyl-modified acrylonitrile-butadiene copolymer rubber obtained by copolymerizing a vinyl monomer containing carboxy group, acrylonitrile and butadiene. ^A rubber composition for a tire tread containing 30 to 100 parts by mass of ² / g of silica and vulcanized with sulfur.   The rubber composition for a tire tread according to claim 1, wherein the carboxyl-modified acrylonitrile-butadiene copolymer rubber has an acrylonitrile copolymerization amount of 10 to 80% by mass.   The rubber composition for a tire tread according to claim 1 or 2, wherein a content of the carboxyl-modified acrylonitrile-butadiene copolymer rubber is 5 to 30% by mass in the rubber component.   The rubber composition for a tire tread according to any one of claims 1 to 3, wherein the carboxyl-modified acrylonitrile-butadiene copolymer rubber is hydrogenated.   The tread formed from the rubber composition for tire treads in any one of Claims 1-4.   A tire manufactured using the tread according to claim 5.