JP4843549B2 - Rubber composition - Google Patents

Description

The present invention relates to a rubber composition, and more particularly to a rubber composition for a tire.

Conventionally, rolling resistance of tires has been reduced (improvement of rolling resistance performance), and vehicle fuel efficiency has been reduced. In recent years, there has been a strong demand for low fuel consumption, and excellent low heat build-up is required for rubber compositions for producing treads having a high occupation ratio among tire members.

As a method of reducing the heat generation of the rubber composition, a method of reducing the amount of the reinforcing filler is known. However, if the amount of the reinforcing filler is reduced, the height of the rubber composition decreases. There is a problem that the tire is softened and the steering stability of the vehicle and the wet skid performance of the tire are lowered. In order to solve these problems, silica or the like is generally used as a filler, and at the same time, a silane coupling agent is also used (Patent Document 1). As the silane coupling agent, polysulfide silane such as bis- (3-triethoxysilylpropyl) tetrasulfide is used, but there is a problem that viscosity increase occurs during processing.

On the other hand, since silica absorbs the vulcanization accelerator and consequently delays the vulcanization speed, there is a problem in the vulcanization system.

JP 2002-363346 A

An object of the invention is to provide a rubber composition for producing a tire having excellent low heat generation performance and capable of achieving low fuel consumption of a vehicle.

That is, in the present invention, 15 to 150 parts by weight of silica with respect to 100 parts by weight of the rubber component, the following general formula (1):

_{(C p H 2p + 1 O} ) 3 Si-C q H 2q -S-CO-C k H 2k + 1 (1)

(Wherein p is an integer of 1 to 3, q is an integer of 1 to 5, and k is an integer of 5 to 12), or the following general formula (2):

_{(C x H 2x O 2)} (C p H 2p + 1 O) Si-C q H 2q -S-CO-C k H 2k + 1 (2)

(In the formula, p is an integer of 1 to 3, q is an integer of 1 to 5, k is an integer of 5 to 12, and x is an integer of 3 to 6. )
0.1 to 20 parts by weight of the silane coupling agent represented by the following formula (3):

_{(C 6 H 5 -CH 2)} 2 N- (C = S) -S y - (C = S) -N (CH 2 -C 6 H 5) 2 (3)

(In the formula, y is an integer of 1 to 8.)
It is related with the rubber composition which contains 0.1-5 weight part of vulcanization accelerators represented by these with respect to 100 weight part of rubber components.

It is preferable to contain 10 parts by weight or more of silica having an average primary particle diameter of 20 nm or more and 5 parts by weight or more of silica having an average primary particle diameter of less than 20 nm with respect to 100 parts by weight of the rubber component.

The present invention also relates to a tire having a tread formed from the rubber composition.

According to the rubber composition of the present invention, it is possible to provide a tire that has excellent low heat generation performance and can achieve low fuel consumption of a vehicle.

The rubber composition of the present invention comprises 15 to 150 parts by weight of silica with respect to 100 parts by weight of the rubber component, 0.1 to 20 parts by weight of a specific silane coupling agent with respect to 100 parts by weight of silica, and a specific additive. The sulfur accelerator is contained in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of the rubber component.

The rubber component used in the present invention is natural rubber (NR) and / or a diene synthetic rubber. Diene-based synthetic rubbers include styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), butadiene rubber (BR), isoprene rubber (IR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR ), Butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR) and the like, and may be contained in one or more kinds in the rubber component used in the present invention. SBR is particularly preferable from the balance of rolling resistance and wet skid performance.

The silica used in the present invention is not particularly limited, and examples thereof include dry method silica and wet method silica, and wet method silica is preferable. The compounding quantity of a silica is 15-150 weight part with respect to 100 weight part of said rubber components. When the amount of silica is less than 15 parts by weight, the wear resistance is lowered, and when it exceeds 150 parts by weight, it is difficult to disperse the silica into the rubber and the workability is lowered. From the viewpoint of low heat build-up and workability, the upper limit of the amount of silica is preferably 120 parts by weight, more preferably 100 parts by weight, and the lower limit is preferably 30 parts by weight, more preferably 40 parts by weight.

Silica is 10 parts by weight or more of large particle size silica (1) having an average primary particle size of 20 nm or more and small particle size silica (2) having an average primary particle size of less than 20 nm with respect to 100 parts by weight of the rubber component. It is preferable to contain 5 parts by weight or more. If the silica having an average primary particle diameter of 20 nm or more is less than 10 parts by weight, or if the silica having an average primary particle diameter of less than 20 nm is less than 5 parts by weight, the effect of using two types of silica tends not to be obtained. The upper limit of the amount of the large particle size silica (1) having an average primary particle size of 20 nm or more is preferably 40 parts by weight, more preferably 30 parts by weight, and the lower limit is preferably 10 parts by weight, more preferably 15 parts by weight. The upper limit of the amount of the small particle size silica (2) having an average primary particle size of less than 20 nm is preferably 80 parts by weight, more preferably 70 parts by weight, and the lower limit is preferably 20 parts by weight, more preferably 30 parts by weight. .

The average primary particle size of the large particle size silica (1) is 20 nm or more, preferably 25 nm or more. If it is less than 20 nm, the rolling resistance tends to increase. The average primary particle size of the small particle size silica (2) is 20 nm or less, preferably 18 nm or less. If it exceeds 20 nm, the rubber strength is insufficient and the wear resistance tends to decrease.

The silane coupling agent used in the present invention is represented by the following general formula (1) or (2).

_{(C p H 2p + 1 O} ) 3 Si-C q H 2q -S-CO-C k H 2k + 1 (1)

_{(C x H 2x O 2)} (C p H 2p + 1 O) Si-C q H 2q -S-CO-C k H 2k + 1 (2)

In the formula, p is an integer of 1 to 3, but 2 is preferable. When p is 4 or more, the coupling reaction tends to be slow. q is an integer of 1 to 5, but 3 is preferable. When q is 0 or 6 or more, synthesis is difficult. k is an integer of 5 to 12, but is preferably an integer of 7 to 12. If k is 4 or less, the odor is strong and the workability tends to deteriorate. Conversely, if k is 13 or more, the cost tends to increase. As a silane coupling agent, only 1 type may be used and 2 or more types may be used together. The silane coupling agent represented by the general formula (2) has a cyclic structure in which a part of (C _x H _2x O ₂ ) forms a ring with Si, and has a total of three SiO bonds. In particular, the silane coupling agent represented by the general formula (2) can suppress the generation of alcohol when reacting with silica.

The compounding quantity of a silane coupling agent is 0.1-20 weight part with respect to 100 weight part of silica. If the amount of silica is less than 0.1 parts by weight, the rolling resistance tends to increase, and if it exceeds 20 parts by weight, the performance improvement effect is small and uneconomical. The upper limit of the amount of the silane coupling agent is preferably 16 parts by weight, and the lower limit is preferably 2 parts by weight, more preferably 4 parts by weight.

The rubber composition of the present invention can also contain carbon black as a filler. Examples of carbon black that can be used include HAF, ISAF, SAF, FEF, and GPF, but are not particularly limited.

The vulcanization accelerator used in the present invention is represented by the following general formula (3).

_{(C 6 H 5 -CH 2)} 2 N- (C = S) -S y - (C = S) -N (CH 2 -C 6 H 5) 2 (3)

In the formula, y is an integer of 1 to 8, and 2 is more preferable. If y is 9 or more, synthesis is difficult.

The amount of the vulcanization accelerator is 0.1 to 5 parts by weight with respect to 100 parts by weight of the rubber component. If the blending amount of the vulcanization accelerator is less than 0.1 parts by weight, the effect of promoting vulcanization cannot be obtained, and if it exceeds 5 parts by weight, blooming occurs. The upper limit of the amount of the vulcanization accelerator is preferably 4 parts by weight, more preferably 3 parts by weight, and the lower limit is preferably 0.2 parts by weight.

The vulcanization accelerator can be used in combination with other vulcanization accelerators. Examples of other vulcanization accelerators include guanidine vulcanization accelerators and sulfenamide vulcanization accelerators.

Examples of the guanidine vulcanization accelerator include diphenyl guanidine, diort triguanidine, triphenyl guanidine, orthotolyl biguanide, diphenyl guanidine phthalate and the like. When used in combination, the content of the guanidine vulcanization accelerator is 0.1 parts by weight or more, preferably 0.5 parts by weight or more with respect to 100 parts by weight of the rubber component. When the content of the guanidine vulcanization accelerator is less than 0.1 parts by weight, the effect of increasing the vulcanization speed is insufficient. The content of the guanidine vulcanization accelerator is 4 parts by weight or less, preferably 3 parts by weight or less with respect to 100 parts by weight of the rubber component. When the content of the guanidine vulcanization accelerator exceeds 4 parts by weight, it exceeds the solubility limit in rubber and blooms (deposits) on the rubber surface.

The sulfenamide vulcanization accelerator is represented by the general formula (1).

In General formula (1), R shows a C1-C18 linear alkyl group or branched alkyl group. R is particularly preferably a branched alkyl group.

Specific examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS) and N-cyclohexyl-2-benzothiazolylsulfenamide (CBS). can give. Of these, TBBS is preferred as the sulfenamide-based vulcanization accelerator (C) because the effect of good dispersibility in rubber and stability of vulcanized physical properties can be obtained.

When used in combination, the content of the sulfenamide vulcanization accelerator is at least 0.1 part by weight, preferably at least 0.5 part by weight, based on 100 parts by weight of the rubber component. When the content of the sulfenamide-based vulcanization accelerator is less than 0.1 parts by weight, the crosslinking becomes insufficient and the rubber properties are inferior. Further, the content of the sulfenamide vulcanization accelerator is 4 parts by weight or less, preferably 3 parts by weight or less with respect to 100 parts by weight of the rubber component. When the content of the sulfenamide vulcanization accelerator exceeds 4 parts by weight, it exceeds the limit solubility in rubber and precipitates on the surface.

In addition to the rubber component, silica, silane coupling agent, carbon black, and vulcanization accelerator, the rubber composition of the present invention includes inorganic filler such as clay, aluminum hydroxide, and calcium carbonate as necessary. A compounding agent used in a normal rubber industry such as an agent, a process oil, a softening agent, an anti-aging agent, a vulcanizing agent, and a vulcanization accelerating aid can be appropriately blended.

The rubber composition of the present invention can be suitably used for tire members such as tire treads, carcass, belts, sidewalls and beads, anti-vibration rubbers, belts, hoses, and other various industrial rubbers. Among tire members, it is preferable to use the tire tread from the viewpoints of both wet performance and rolling resistance and wear performance.

The tire of the present invention is obtained by kneading various additives as necessary to the rubber composition obtained by kneading using a rubber kneader such as a Banbury mixer or an open roll, and obtaining the unvulcanized rubber composition It is manufactured by extruding an object according to the shape of the tire tread, forming an unvulcanized tire on a tire molding machine, and further heating and pressurizing the unvulcanized tire in a vulcanizer. . Here, the processing into the tread is created by a method of pasting the sheet into a predetermined shape, or a method of charging two or more extruders and forming them in two layers at the head outlet of the extruder. be able to.

Experimental Examples Hereinafter, the present invention will be specifically described based on examples, but these do not limit the present invention.

The various chemicals and test methods used in the examples and comparative examples are described below.

<Various chemicals>
Diene rubber: E15 (styrene-butadiene copolymer) manufactured by Asahi Kasei Corporation
Silica (1): Ultrasil U360 manufactured by Degussa Co., Ltd., average primary particle size 28 nm)
Silica (2): Ultrasil VN3 manufactured by Degussa Co., Ltd., average primary particle size 15 nm)
Coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa Co., Ltd.
Coupling agent A: NXT manufactured by GE Toshiba Silicone Co., Ltd.
_{(C p H 2p + 1 O} ) 3 Si-C q H 2q -S-CO-C k H 2k + 1
(P = 2, q = 3, k = 7)
Coupling agent B: NXT-LV manufactured by GE Toshiba Silicone Co., Ltd.
_{(C 2 H 4 O 2)} (C p H 2p + 1 O) 3 Si-C q H 2q -S-CO-C k H 2k + 1
(P = 2, q = 3, k = 7)
Zinc oxide: Mitsui Kinzoku Mining Co., Ltd.
Aromatic oil: Diana Process AH-24 manufactured by Idemitsu Kosan Co., Ltd.
Anti-aging agent: Antigen 6C manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. CZ: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical
Vulcanization accelerator DPG: Noxeller D (diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Vulcanization accelerator α: Noxeller TBzTD made by Ouchi Shinsei Chemical Co., Ltd.

_{(C 6 H 5 -CH 2)} 2 N- (C = S) -S 2 - (C = S) -N (CH 2 -C 6 H 5) 2

(Processability)
The Mooney viscosity of the unvulcanized rubber composition was measured at 100 ° C. according to the Mooney viscosity measurement method defined in JIS K6300. The Mooney viscosity (ML _{1 + 4} ) of Comparative Example 1 was set to 100, and indexed by the following calculation formula. The larger the index, the lower the Mooney viscosity and the better the processability.

(Mooney viscosity index) = (ML _{1 + 4} of Comparative Example 1) / (ML _{1 + 4 of} each formulation) × 100

Further, a vulcanization test was performed at a measurement temperature of 160 ° C. using a vibration type vulcanization tester (curast meter) described in JIS K 6300 to obtain a vulcanization rate curve in which time and torque were plotted. . When the minimum value of the torque of the vulcanization speed curve is ML, the maximum value is MH, and the difference (MH−ML) is ME, time T ₉₅ (minute) to reach ML + 0.95ME was read.

(Rolling resistance index)
A rolling resistance tester was used to measure the rolling resistance when the sample tire was run at a rim (15 × 6JJ), internal pressure (230 kPa), load (3.43 kN), speed (80 km / h), and Comparative Example 1 Is expressed as an index when the value is 100. The larger the index, the better.

(Wet skid performance)
On the wet asphalt road surface, the braking distance from the initial speed of 100 km / h was obtained, calculated according to the following formula, and displayed as an index. The larger the index, the better the wet skid performance.

(Wet skid performance) = (braking distance of comparative example 1) ÷ (braking distance of 10 commands) × 100

(Abrasion resistance)
The sample tire was run on a real vehicle, the change in pattern groove depth before and after running 30000 km was determined, and displayed as an index when Comparative Example 1 was taken as 100. The higher the index, the better the wear characteristics.

(Maneuvering stability)
The test tires were mounted on all wheels of a vehicle (domestic FF car 2000cc) and the vehicle was run on the test course, and the driving stability was evaluated by sensory evaluation of the driver. Evaluation was made relative with 10 points being the perfect score and Comparative Example 1 being 6 points. The higher the score, the better.

Examples 1-4 and Comparative Examples 1-4
In accordance with the formulation shown in Table 1 below, SBR, silica, silane coupling agent, aromatic oil, zinc oxide, stearic acid, antioxidant, and wax were kneaded for 3 minutes with a Banbury mixer. Sulfur and a vulcanization accelerator were kneaded with a roll into the obtained rubber composition to obtain an unvulcanized rubber composition.

The obtained unvulcanized rubber composition was molded into a tread shape, bonded to another tire member, and vulcanized for 12 minutes under the conditions of 175 ° C. and 20 kgf, whereby a tire for a passenger car (tire size: 195 / 65R15) was manufactured and used for testing.

As is apparent from the results of Tables 1 and 2, the tire obtained from the rubber composition containing a specific silane coupling agent and a specific vulcanization accelerator has excellent processability, rolling resistance index, and wet skid. It can be seen that it has a good balance of performance, wear resistance, and steering stability, and can achieve low fuel consumption of the vehicle.

Claims (4)

15 to 150 parts by weight of silica per 100 parts by weight of the rubber component, the following general formula (1):
_{(C p H 2p + 1 O} ) 3 Si-C q H 2q -S-CO-C k H 2k + 1 (1)
(Wherein p is an integer of 1 to 3, q is an integer of 1 to 5, and k is an integer of 5 to 12), or the following general formula (2):
_{(C x H 2x O 2)} (C p H 2p + 1 O) Si-C q H 2q -S-CO-C k H 2k + 1 (2)
(In the formula, p is an integer of 1 to 3, q is an integer of 1 to 5, k is an integer of 5 to 12, and x is an integer of 3 to 6.)
0.1 to 20 parts by weight of the silane coupling agent represented by the following formula (3):
_{(C 6 H 5 -CH 2)} 2 N- (C = S) -S y - (C = S) -N (CH 2 -C 6 H 5) 2 (3)
(In the formula, y is an integer of 1 to 8.)
In the vulcanization accelerator represented by a rubber composition containing 0.1 to 5 parts by weight per 100 parts by weight of the rubber component,
A rubber composition containing 10 parts by weight or more of silica having an average primary particle diameter of 20 nm or more and 5 parts by weight or more of silica having an average primary particle diameter of less than 20 nm with respect to 100 parts by weight of the rubber component . The rubber composition according to claim 1, wherein the rubber component contains styrene-butadiene rubber. The guanidine vulcanization accelerator is contained in 0.1 to 4 parts by weight and the sulfenamide vulcanization accelerator is contained in 0.1 to 4 parts by weight with respect to 100 parts by weight of the rubber component. Rubber composition. A tire having a tread formed from the rubber composition according to any one of claims 1 to 3 .