JP3280783B2 - Tread rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tread rubber for fuel-efficient tires, which maintains grip performance.

[0002]

2. Description of the Related Art Various performances are required for automobile tires, such as low fuel consumption, handling stability, wear resistance, and riding comfort. Of these performances,
In particular, the grip resistance of the tire and the trailing resistance are all characteristics relating to hysteresis loss of the rubber. In general, increasing the hysteresis loss increases grip,
The braking performance is improved, but the rolling resistance is also increased, resulting in an increase in fuel efficiency. As described above, since the gripping property and the rolling resistance are in an opposing relationship, various rubber compositions for tires have been proposed to satisfy both properties at the same time.

[0003] In a rubber composition for a tire, particularly, a polymer and carbon black greatly influence both properties. For example, when a styrene-butadiene copolymer is used as a polymer, the content of bound styrene, butadiene The rolling resistance and the grip are both improved by appropriately selecting the 1,2 bond content of the portion. on the other hand,
For carbon black, increase the particle size,
If the compounding amount is reduced, the cut chipping resistance and the like are reduced. Therefore, a new type of carbon black (for example, N3
51) has been developed and is effective.

[0004]

However, from the viewpoints of global environmental protection and resource protection in recent years, with the development of electric vehicles and solar cars, fuel-efficient tires, more specifically, tires with even lower rolling resistance, have been required. ing. An object of the present invention is to provide a tread rubber composition capable of further reducing rolling resistance without lowering wet grip properties and satisfying steering stability.

[0005]

SUMMARY OF THE INVENTION The tread rubber of the present invention
The composition has a bound styrene content of 5 to 45% by weight,
The 1,2 bond content of the butadiene portion is 10 to 80% by weight.
50% by weight or more of styrene-butadiene copolymer
Per 100 parts by weight of the diene rubber contained,Kaolinai
Fired clay, which is an amorphous metakaolin
10 to 60 parts by weight of the total amount of reinforcing agent up to 10 to 50 parts by weight
% Of the rubber composition.
X _Three SiR (where X is an alkoxy group or a chlorine atom
Represents a vinyl group, a glycidyl group, a methacrylic group,
Mino, mercapto, epoxy, or imide groups
Or one type) or (C _n H _{2n + 1} O) _Three -Si- (C
H _Two ) _m -S _k − (CH _Two ) M-Si- (C _n H _{2n + 1} O)
_Three (In the formula, n represents an integer of 1 to 4, and m and k each represent 1 to 4.
Indicates an integer of 6. 1) The silane coupling agent 1 represented by
6 parts by weight.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer used in the present invention is:
In order to ensure grip, a styrene-butadiene copolymer (hereinafter, referred to as “SBR”) having a bound styrene content of 5 to 45% by weight and a 1,2 bond content of a butadiene portion of 10 to 80% by weight. ). When the content of the bound styrene in the SBR is less than 5% by weight, the gripping property decreases, and when the content of the bound styrene exceeds 45% by weight, the rolling resistance can be extremely increased. On the other hand, if the 1,2 bond content of the butadiene portion is less than 10% by weight, the gripping property is reduced, and the partial resistance exceeding 80% by weight can be extremely increased. The SBR having such a configuration may constitute a rubber component alone or may be used as a mixture with another diene rubber such as natural rubber. When used in combination with another polymer, the SBR is mixed so that the content of SBR is 50% by weight or more.

In the rubber composition of the present invention, clay containing kaolinite as a main component is used to eliminate a water film between a tire surface and a road surface. Among the clays mainly containing kaolinite, an amorphous metakaolin clay fired at 600 ° C. is particularly preferably used. Further, after firing, clay treated with a silane coupling agent is effective. The content of the clay is 10 to 50 parts by weight, preferably 20 to 40 parts by weight, per 100 parts by weight of the polymer. If the amount of the clay exceeds 50 parts by weight, the reinforcing property decreases, which is not preferable. On the other hand, when the compounding amount of the clay is less than 10 parts by weight, the improvement of the grip force on the wet road surface of the present invention is hardly recognized.

The clay used in the present invention has a large particle size and is inferior in the reinforcing effect. Therefore, a reinforcing agent such as carbon black or silica is used in combination. In this case, it is preferable that the compounding amount of the clay is 10 to 60% by weight based on the total amount of the reinforcing agent, which is the total amount of the reinforcing agent such as carbon black. The total amount of the reinforcing agent is preferably 60 to 120 parts by weight per 100 parts by weight of the rubber component. The tread rubber composition of the present invention further comprises
In order to prevent the deterioration of fracture characteristics due to the addition of clay,
It is preferable to add a silane coupling agent. Examples of the silane coupling agent include X ₃ SiR (wherein X represents an alkoxy group or a chlorine atom, and R represents any one of a vinyl group, a glycidyl group, a methacrylic group, an amino group, a mercapto group, an epoxy group, and an imide group. One type) or (C _{n
H 2n + 1 O) 3 -Si-} (CH 2) m -S k - (CH 2) m -S
_{i- (C n H 2n + 1} O) 3 ( wherein, n represents an integer of 1 to 4, m, k denotes each integer from 1 to 6.) is preferably a silane coupling agent represented by Used. The amount of the silane coupling agent is preferably 1 to 6 parts by weight, more preferably 2 to 4 parts by weight, per 100 parts by weight of the rubber component. When the content of the silane coupling agent is less than 1 part by weight, the reinforcing effect is hardly recognized. When the content exceeds 6 parts by weight, the unreacted portion of the silane coupling agent precipitates on the tread surface in the molded tire, and conversely, the grip is increased. This may cause a decrease in sex. The silane coupling agent may be added alone to the composition or may be added as a clay treating agent.

The rubber composition of the present invention contains, in addition to the above compounds, vulcanizing agents, vulcanization accelerators, vulcanization accelerators, antioxidants, and softeners, which are compounding agents used in ordinary rubber industries. Etc. may be included. [Specific Example] As the polymer, a mixture of SL552 (styrene content: 24% by weight, butadiene 1,2 bond content: 40% by weight) manufactured by Japan Synthetic Rubber Co., Ltd. and natural rubber was used. Show Black N220 manufactured by Showa Cabot Corporation was used as carbon black. Kaolinite as clay mainly, Shiraishi Calcium Co., Ltd. of amorphous ice cap was calcined at 600 ° C. is a metakaolin of K (hereinafter abbreviated as "Clay A") and ice cap KE (hereinafter, "clay B "). The ice cap KE (clay B) was fired at 600 ° C. and then treated with a silane coupling agent. In 30 parts by weight of the ice cap KE, 3 parts of the silane coupling agent were used.
% By weight (1 part by weight). As a silane coupling agent, Si69 manufactured by Degussa was used. this is,
Bis (3-triethoxysilylpropyl) tetrasulfene.

Various additives shown in Table 1 were used as other additives. The amounts of the various additives shown in Table 1 are based on 100 parts by weight of the rubber component. As an antioxidant shown in Table 1, Ozonone 6c manufactured by Seiko Chemical Co., Ltd. was used.
This is N-phenyl-N '-(1,3 dimethylbutyl) -p-phenylenediamine. Noxera-NS manufactured by Ouchi Shinko Chemical Co., Ltd. was used as a vulcanization accelerator. This is N-tert-butyl-2-benzothiazylsulfenamide.

[0011]

[Table 1]

SBR, natural rubber, reinforcing agent (combination of carbon black, clay A, clay B) and silane coupling agent are blended in the amounts shown in Table 2, and various blending agents shown in Table 1 are blended. The rubber compositions of Examples 1 to 7 and Comparative Examples 1 to 4 shown in Table 2 were prepared. The amount of the silane coupling agent shown in Table 2 indicates the content in the finally prepared rubber composition, and the numerical value in parentheses in Example 7 indicates the amount of the silane coupling agent obtained by blending clay B. It shows the content of the ring agent. A sample piece was prepared using the prepared rubber composition, and the breaking properties of the rubber composition were evaluated by the following method. Using the above rubber composition, a tire (rim; 6JJ × 14, internal pressure of tire: 2 kg / c)
m ² ), and for this tire, rolling resistance,
Driving stability and braking performance were evaluated by the following methods. The results are shown in Table 2.

[0013]

[Table 2]

[Evaluation Method] (a) Rolling Resistance With a load of 350 kgf applied, the tire was rotated at a speed of 80 km / h to measure the rolling friction coefficient. Taking the rolling friction coefficient of a tire made of a rubber composition containing no clay (Comparative Example 2) as 100, the rolling friction resistance of other Examples and Comparative Examples was represented by an index. The smaller the index, the smaller the rolling resistance and the better. (B) Steering stability The tires prepared above were mounted on a 2000 cc front-wheel drive (FF) type vehicle, and the steering stability when traveling on wet asphalt road was 1 (worst) to 10 (worst).
The sensory evaluation was performed on a 10 (best) scale. Six or more points pass the steering stability. (C) Braking performance The vehicle equipped with the prepared tires was driven on a wet asphalt road at a speed of 60 km / h, and the distance from when the wheels were locked by sudden braking until the vehicle stopped was measured. The stopping distance of Comparative Example 2 was set to 100, and the stopping distances of the other Examples and Comparative Examples were represented by indexes. The smaller the index, the better. [Evaluation] As can be seen from Table 2, generally, the lower the clay content, the lower the rolling resistance. Therefore, any one of Comparative Examples 1 to 4 is inferior in steering stability, rolling resistance, and braking performance. Was. Comparative Example 4 shows good rolling resistance and steering stability. However, after completion of the steering stability test, the tread rubber was chipped, and the durability was insufficient. .

On the other hand, the tires produced using the rubber composition of the present invention all have rolling resistance, steering stability,
Excellent braking performance. Further, it can be seen that, in the rubber compositions of Examples 1 to 7, when the content of the silane coupling agent is 1 to 6 parts by weight, the steering stability tends to be improved.

[0016]

As described above, the tread rubber composition of the present invention has a small rolling resistance, and is excellent in steering stability and braking performance. Therefore, a tire produced by using the tread rubber composition of the present invention for a tread portion has low fuel consumption and excellent steering stability and braking performance. Further, by using the tread rubber composition of the present invention containing a predetermined amount of a silane coupling agent, the steering stability can be further improved.

Continuation of the front page (56) References JP-A-61-18505 (JP, A) JP-A-5-27177 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 9 / 06 B60C 1/00

Claims (2)

(57) [Claims] 1. The content of bound styrene is 5 to 45% by weight.
A styrene-butadiene copolymer having a 1,2 bond content of a butadiene portion of 10 to 80% by weight is 50% by weight.
An amorphous metakaolin containing kaolinite as a main component per 100 parts by weight of the diene rubber contained above.
10 to 50 parts by weight of the total amount of reinforcing agent
A tread rubber composition characterized by being blended so as to be in an amount of about 60% by weight . 2. X ₃ SiR wherein X is an alkoxy group or
Represents a chlorine atom, and R represents a vinyl group, a glycidyl group,
A lyl group, an amino group, a mercapto group, an epoxy group, or an
It represents any one of the bromide group) or _{(C n H 2n + 1 O} ) 3 -
_{Si- (CH 2) m -S k} - (CH 2) m-Si- (C n H
_{2n + 1} O) ₃ (wherein, n represents an integer of 1 to 4, and m and k represent
Each represents an integer of 1 to 6. Silane coupling represented by)
2. The composition according to claim 1, wherein 1 to 6 parts by weight of a carburizing agent is added.
5. The tread rubber composition according to item 1.