JP4464723B2 - Rubber composition - Google Patents

Description

  The present invention relates to a rubber composition, and more particularly to a rubber composition for a tire excellent in fuel efficiency.

In recent years, there has been a strong demand for both a reduction in fuel consumption of tires and an improvement in wet grip performance. In order to satisfy this requirement, silica has been added to a rubber composition for tire treads. As such silica, silica having a primary particle diameter of 15 nm or more or a nitrogen adsorption specific surface area of less than 400 m ² / g has been used.

For example, Patent Document 1 discloses that silica having an average particle size of 10 to 30 μm and a specific surface area of 400 to 700 m ² / g formed by a sol-gel method is used for a tire rubber composition.

  However, the current situation is that it is now required to achieve both high fuel efficiency and high wet grip performance, and it is difficult to meet the demand.

JP-A-6-116440

  An object of this invention is to provide the rubber composition which can make high improvement of the fuel-consumption property of a tire, and wet grip performance highly.

The present invention relates to a rubber composition comprising a rubber component and a silica having an extremely small particle diameter having a primary particle diameter of 14 nm or less and a nitrogen adsorption specific surface area of 400 m ² / g or more.

  The rubber composition further includes a silica other than the ultrafine particle silica and a silane coupling agent, and the total amount of the ultrafine silica and the silica other than the ultrafine silica with respect to 100 parts by weight of the rubber component. Is preferably 40 parts by weight or more.

According to the present invention, by blending a unique silica having a primary particle diameter of 14 nm or less and a nitrogen adsorption specific surface area of 400 m ² / g or more, further ensuring low fuel consumption and wet grip, Abrasion can be improved.

  The rubber composition of the present invention is obtained by blending a rubber component with ultrafine particle size silica.

  Examples of the rubber component include natural rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile rubber, ethylene rubber, ethylene propylene rubber, and butyl rubber. Among these, natural rubber, SBR, IR, nitrile rubber, and butyl rubber are preferably used in terms of excellent wet grip performance. These rubbers may be used alone or in combination.

  The primary particle diameter of the ultrafine particle diameter silica is 14 nm or less, preferably 12 nm or less, more preferably 11 nm or less. When the primary particle diameter exceeds 14 nm, the wear resistance deteriorates. Further, the primary particle diameter of the ultrafine particle diameter silica is preferably 5 nm or more, more preferably 8 nm or more. When the primary particle diameter is less than 5 nm, dispersion in rubber becomes difficult and aggregation occurs, which tends to deteriorate fuel efficiency. Here, the primary particle diameter is determined by TEM measurement.

Further, the nitrogen adsorption specific surface area (N ₂ SA) of the ultrafine particle silica is 400 m ² / g or more, preferably 500 m ² / g or more. When N ₂ SA is less than 400 m ² / g, the bonding point with rubber is reduced, and fuel efficiency is not reduced. The N ₂ SA of the ultrafine particle silica is preferably 1000 m ² / g or less, more preferably 850 m ² / g or less. When N ₂ SA exceeds 1000 m ² / g, dispersion in rubber becomes extremely difficult, and wear resistance tends to deteriorate.

  The amount of the ultrafine particle silica is preferably 5 parts by weight or more, more preferably 10 parts by weight or more with respect to 100 parts by weight of the rubber component. When the blending amount is less than 5 parts by weight, there is a tendency that sufficient effect of improving wear resistance and fuel economy is not observed. Moreover, the compounding quantity of the ultrafine particle diameter silica becomes like this. Preferably it is 40 weight part or less, More preferably, it is 35 weight part or less. If the blending amount exceeds 40 parts by weight, the cost tends to be undesirable.

  Furthermore, the rubber composition of the present invention can also contain silica other than the above-mentioned extremely small particle diameter silica.

  The amount of the silica is preferably 25 parts by weight or more, more preferably 30 parts by weight or more with respect to 100 parts by weight of the rubber component. If the blending amount is less than 25 parts by weight, the effect of improving fuel economy tends to be small. The amount of silica is preferably 100 parts by weight or less, more preferably 80 parts by weight or less. When the blending amount exceeds 100 parts by weight, the rubber becomes too hard and a sufficient wet grip tends not to be obtained.

  The total amount of the minimum particle diameter silica and silica other than the minimum particle diameter silica is preferably 40 parts by weight or more with respect to 100 parts by weight of the rubber component. If the total amount is less than 40 parts by weight, there is a tendency that sufficient effect of improving fuel economy is not observed. The total amount is preferably 140 parts by weight or less, more preferably 115 parts by weight or less. If the total amount exceeds 140 parts by weight, the rubber tends to be too hard and sufficient wet grip cannot be obtained.

  Furthermore, a silane coupling agent can be blended in the rubber composition of the present invention.

  The silane coupling agent is not particularly limited, and sulfide-based, mercapto-based, vinyl-based, amino-based, glycidoxy-based, nitro-based, and chloro-based silane coupling agents are used.

  Specifically, sulfide-based silane coupling agents include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3- Trimethoxysilylpropyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilane Ruethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide, 3-triethoxysilylpropylbenzothiazole Examples thereof include tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide.

  Examples of mercapto-based silane coupling agents include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the like.

  Examples of vinyl-based silane coupling agents include vinyltriethoxysilane and vinyltrimethoxysilane.

  Examples of amino silane coupling agents include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, and 3- (2-aminoethyl) aminopropyl. Examples include trimethoxysilane.

  Examples of glycidoxy-based silane coupling agents include Y-glycidoxypropyltriethoxysilane, Y-glycidoxypropyltrimethoxysilane, Y-glycidoxypropylmethyldiethoxysilane, and Y-glycidoxypropylmethyldimethoxysilane. Etc.

  Examples of the nitro silane coupling agent include 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane.

  Examples of the chloro-based silane coupling agent include 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, and the like.

  The aforementioned silane coupling agents may be used alone or in combination of two or more.

  The blending amount of the silane coupling agent is preferably 5 parts by weight or more, more preferably 7 parts by weight or more with respect to 100 parts by weight of the total amount of the ultrafine particle diameter silica and silica other than the ultrafine particle diameter silica. . If the blending amount of the silane coupling agent is less than 5 parts by weight, not only the processability is deteriorated but also the fuel efficiency tends to be deteriorated. If the amount exceeds 15 parts by weight, the unreacted silane coupling agent is increased and the processing is in progress. At the same time that the rubber adheres to the roll, fuel economy tends to deteriorate.

  Furthermore, in the rubber composition of the present invention, as other compounding agents, reinforcing agents other than silica such as carbon black, oils, coloring agents, anti-aging agents and the like can be compounded.

  When carbon black is blended, as the carbon black, for example, commercially available HAF, ISAF, SAF and the like are used.

  The compounding amount of the carbon black is preferably 5 parts by weight or more, more preferably 30 parts by weight or more with respect to 100 parts by weight of the rubber component. When the blending amount of carbon black is less than 5 parts by weight, the wear resistance tends to deteriorate. The blending amount of carbon black is preferably 50 parts by weight or less, more preferably 40 parts by weight or less. When the blending amount of carbon black exceeds 50 parts by weight, there is a tendency that the effect of improving fuel efficiency is lost.

  In the rubber composition of the present invention, the rubber component, silica (silica other than ultrafine particle silica and ultrafine particle silica), a silane coupling agent, and other compounding agents are kneaded using a kneader or a Banbury mixer. After that, it can be manufactured by making it into a predetermined shape and performing vulcanization molding.

  In addition, when blending the compounding agent, the silica component is preliminarily kneaded with the rubber component, silica (silica other than ultrafine particle silica and ultrafine silica), a silane coupling agent, and oil as necessary. It is preferable to add the compounding agent and knead after preparing the batch. By preparing a silica masterbatch in advance, there is an advantage that the coupling effect of the silane coupling agent is sufficiently exhibited.

  The rubber composition of the present invention obtained as described above is used for tires, particularly treads, and can achieve both high fuel economy and improved wet grip performance.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

Example 1 and Comparative Examples 1-2
(Description of chemicals)
Natural rubber: RSS # 3
SBR: SBR1502 manufactured by JSR Corporation
Silica 1: Ultrazil VN3 manufactured by Degussa (primary particle size: 16 nm, N ₂ SA: 175 m ² / g)
Silica 2: MN1S-0210 (Primary particle size: 15 nm, N ₂ SA: 160 m ² / g) manufactured by Siberbergner
Ultra-small particle diameter silica: MN1S-0220 manufactured by Siebel Hegner (primary particle diameter: 10 nm, N ₂ SA: 640 m ² / g)
Silane coupling agent: Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Degussa
Aroma oil: X140 made by Japan Energy Co., Ltd.
Carbon black: Diamond Black I (ISAF) manufactured by Mitsubishi Chemical Corporation
Stearic acid: Nippon Oil & Fats Co., Ltd. Zinc oxide: Mitsui Mining & Mining Co., Ltd. Zinc Hua 2 types Sulfur: Tsurumi Chemical Industries Co., Ltd. Noxeller NS made
Vulcanization accelerator DPG: Noxeller D manufactured by Ouchi Shinsei Chemical Co., Ltd.

(Method for producing rubber composition)
First, natural rubber, SBR, silica (usually silica and / or extremely small particle diameter silica), silane coupling agent, and oil in the amounts shown in Table 1 were kneaded using a 1.7 liter Banbury mixer. Next, carbon black, aroma oil, stearic acid, and zinc oxide were kneaded into the kneaded material obtained using a Banbury mixer with a capacity of 1.7 liters. Furthermore, each unvulcanized rubber sheet was obtained by kneading sulfur and a vulcanization accelerator using a roll.

  The obtained rubber composition was press vulcanized at 170 ° C. for 20 minutes to obtain a vulcanized product. Each obtained vulcanizate was used for the test of each characteristic shown below.

(Explanation of test method)
(Processability)
As an index of processability, Mooney viscosity ML _{(1 + 4)} of an unvulcanized rubber composition was measured at 130 ° C. It shows that it is excellent in workability, so that a numerical value is small.

(Wet grip performance)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), tan δ of each vulcanizate was measured under the conditions of a temperature of 0 ° C., an initial strain of 10%, a dynamic strain of 0.2%, and a frequency of 10 Hz. It shows that it is excellent in wet grip performance, so that tan-delta is large.

(Rolling resistance characteristics)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), tan δ of each vulcanizate was measured under conditions of a temperature of 70 ° C., an initial strain of 10%, a dynamic strain (2%), and a frequency of 10 Hz. It shows that it is excellent in rolling resistance characteristics, so that tan-delta is small.

(Abrasion resistance)
Using a Lambourn abrasion tester, the sample was worn under the conditions of a load of 2.5 kgf, a slip rate of 20%, and a test time of 4 minutes, and the volume loss amount of each sample was measured. With the wear index of Comparative Example 1 as 100, the wear index of each formulation was calculated by the following formula. Higher wear index indicates better wear resistance.
(Wear index for each formulation)
= (Volume loss amount of comparative example 1) ÷ (volume loss amount of each example) × 100

  Each test result is shown in Table 1.

Claims (3)

For 100 parts by weight of rubber component ,
The primary particle size of 5～12Nm, and nitrogen adsorption specific surface area of 500~850m ² / g a minimum particle size silica viewed 5-35 parts by weight containing a,
A tire tread using a rubber composition containing 30 to 80 parts by weight of silica other than ultrafine particle silica . Further comprising a silane-coupling agent, relative to 100 parts by weight of the rubber component, of a tire according to claim 1, wherein the total amount of silica other than minimum particle size silica and the minimum particle size silica is 40 parts by weight or more tread . Furthermore, the tire tread of Claim 1 or 2 which contains 5-50 weight part of carbon black with respect to 100 weight part of rubber components.