JP2866585B2 - Tire 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 tire tread rubber composition, and more particularly to a tire tread rubber composition having improved grip on a frozen road surface.

[0002]

2. Description of the Related Art In order to prevent dust pollution caused by spike tires, the ban on spike tires has been legislated, and studless tires have been used in place of spike tires in cold regions. As a result of improvements, studless tires having a grip similar to that of spike tires have been developed and are currently used.

[0003] Factors governing the friction between the tread rubber and the road surface that affect the grip of a studless tire include: 1. Hysteresis loss friction 2. Adhesive friction Although there is excavation friction, the friction due to hysteresis loss is extremely small on roads with extremely low friction coefficient, such as frozen roads, and the ratios of sticking friction and excavation friction are large.

[0004] In order to enhance the excavation frictional force, the tread pattern and the surface form of the tread rubber are important. Spike tires have a large digging and frictional force, but studless tires have also been devised to increase the ruggedness of the tread surface by using foamed rubber or mixing organic fibers in order to increase the digging and frictional force. The unevenness of the tread surface has an effect of eliminating a water film generated between the tread surface and the frozen road surface and increasing the adhesive friction force. However, in this method, the adhesive friction force is indirectly increased by increasing the actual contact area, and there is a limit in increasing the actual contact area, and there is a limit in increasing the adhesive friction force.

Since the rubber itself has an effect on increasing the adhesive frictional force, for example, it is also effective to soften the rubber to increase the contact area with the road surface. For this purpose, the amount of filler has been reduced, butadiene rubber or isoprene rubber, which hardens even at low temperatures, and a softener has been added, but from the viewpoint of handling stability and abrasion resistance. Therefore, it was not possible to make it extremely soft and was an insufficient measure.

As described above, the present studless tires have insufficient grip characteristics and exhibit performance comparable to spiked tires in terms of performance on snow. In some cases, the grip performance is inferior to that of spiked tires due to such conditions, and improvement is required.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a tread for a studless tire used in a studless tire capable of exhibiting excellent grip even on a frozen road surface. It is to provide a rubber composition.

In general, regarding the friction between ice and a tire, ice near 0 ° C. is the most slippery, which is considered to be a lubrication effect by a water film generated by friction at the time of starting and braking.

In order to improve the adhesive friction, it is necessary to remove the water film and increase the contact area between the tread rubber and ice.

In the prior art, various measures have been taken to increase the unevenness of the tread rubber surface. This is effective to enhance the improvement and digging friction traction force by water film removal, increasing the actual contact area by providing irregularities on the front surface
There is a limit to.

Therefore, in order to achieve an improvement in the adhesive friction force, generally, the surface of a rubber exhibiting hydrophobicity or water repellency is further increased in water repellency, thereby making it difficult for water to adhere to the tire surface, It was devised to increase ease of separation.

[0012]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and have found that a rubber composition containing a silylating agent works to improve the adhesive friction force and is very effective. And completed the present invention.

As a means for achieving this, a silylating agent is used. Silylating agents include OH groups in rubber compositions, NHR
The compound having an active hydrogen can easily react with a compound having an active hydrogen such as a group, a COOH group, a CONH group, or an SH group to make the compound having an active hydrogen hydrophobic.

[0014] This means that the hydrophilic portion in the tread rubber composition is changed to hydrophobic to impart water repellency to the tread rubber itself, thereby suppressing the adhesion of a water film interposed between ice and the tread rubber, In addition, water droplets attached to the rubber surface can be easily removed. As a result, the actual contact area between the tread rubber and ice increases, and the adhesive friction force increases.

That is, the present invention relates to 100 parts (parts by weight, the same applies hereinafter) of the rubber component and 30 to 80 carbon black.
Parts, phenyltrichlorosilane, diphenyldichlorosi
Orchid, phenyltriethoxysilane, isobutyltrime
Toxysilane, diphenyldimethoxysilane, hexame
Tildisilazane, N, O- (bistrimethylsilyl) a
Cetamide, N, N-bis (trimethylsilyl) urea
And tert-butyldimethylchlorosilane
At least one silylating agent selected from the group
Part of the invention relates to a tire tread rubber composition.

[0016]

In the present invention, the hydrophilic portion having an active hydrogen group in the tread rubber composition is made hydrophobic by a silylating agent in order to improve the adhesive frictional force, and the tread rubber itself is made water-repellent. Has been granted. This allows
The adhesion of a water film to the rubber surface can be suppressed, and the attached water droplets can be easily removed. As a result, the actual contact area between the tread rubber and ice increases, and the adhesive friction force increases.

As the rubber component in the present invention, natural rubber, isoprene rubber or butadiene rubber having a small increase in hardness at low temperatures is preferably used in order to increase the actual contact area of the frozen road surface on ice and increase the adhesive frictional force. .
These rubbers can be used alone or in any combination.

The carbon black is blended in an amount of 30 to 80 parts, preferably 40 to 60 parts, more preferably 40 to 50 parts with respect to 100 parts of the rubber component to obtain a predetermined hardness. If the amount is less than 30 parts, the abrasion resistance and crack resistance tend to be inferior.

[0019]

[0020]

[0021]

The above silylating agents can be used alone or in any combination.

The silylating agent is used in an amount of 2 to 15 parts, preferably 3 to 8 parts, per 100 parts of the rubber component. If the amount is less than 2 parts, the effect of the blending is hardly observed, and 15
If the amount is more than 10 parts by weight, unreacted silylating agent is deposited on the surface to reduce slip resistance, and conversely, performance on ice tends to decrease.

The tire tread rubber composition of the present invention has a contact angle with water of at least 5%, preferably at least 8%, as compared with a rubber composition containing no silylating agent.

In the rubber composition of the present invention, organic fibers can be mixed to enhance the drainage effect and the scratching effect, or foamed rubber can be used as the rubber component.

In the tire tread rubber composition of the present invention, if necessary, compounding agents usually used for compounding rubber of tires, such as antioxidants, softeners, zinc white, stearic acid, vulcanization accelerators, vulcanization accelerators An agent, sulfur and the like can be appropriately blended.

The tire tread rubber composition of the present invention can be produced by a usual method using a rubber component, carbon black, a silylating agent and the above-mentioned usual compounding agents.

The tire tread rubber composition of the present invention can be applied to treads such as studless tires for passenger cars, studless tires for trucks, and studless tires for buses.

Next, the present invention will be described with reference to examples, but the present invention is not limited to only these examples.

Example 1 Experimental Example 1-1 A base was kneaded at 150 ° C. ± 5 ° C. with the following composition except for a vulcanizing agent (sulfur, an accelerator) and an antioxidant.
A tread rubber composition was prepared by adding a vulcanizing agent and an antioxidant at a temperature of 10 ° C ± 10 ° C and kneading with a finish.

Natural rubber 70 parts Butadiene rubber 30 parts Carbon black ⁽¹⁾ 50 parts Silylating agent ⁽²⁾ 2 parts Stearic acid 2 parts Zinc whitening 4 parts Antioxidant ⁽³⁾ 1 part Sulfur 1.5 parts Vulcanization acceleration Agent ⁽⁴⁾ 0.5 part In addition, carbon black (1) is N220 manufactured by Showa Cabot Co., Ltd., and silylating agent (2) is KBE-103 (phenyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. Ouchi Shinko Chemical Co., Ltd. as an anti-aging agent (3)
6C (N-phenyl-N '-(1,3 dimethylbutyl) -P-phenylenediamine) manufactured by Ouchi Shinko Chemical Co., Ltd. as a vulcanization accelerator (4).
S (N-tert-butyl-2benzothiazylsulfenamide) was used.

Experimental Examples 1-2 to 1-7 A rubber composition was prepared in the same manner as in Experimental Example 1-1, except that the blends of carbon black, process oil and silylating agent were changed as shown in Table 1. The process oil used was Diana Process PS32 manufactured by Idemitsu Kosan Co., Ltd.

If the base kneading temperature is lower than 130 ° C., the reaction of the silylating agent is not sufficiently performed, and if the base kneading temperature is higher than 170 ° C., the rubber tends to deteriorate.
0 ° C. is preferred.

EXPERIMENTAL EXAMPLE 1-8 A rubber composition was prepared in the same manner as in Experimental Example 1-1, using KA 103 (phenyltrichlorosilane) manufactured by Shin-Etsu Chemical Co., Ltd. as a silylating agent.

EXPERIMENTAL EXAMPLE 1-9 Experimental Example 1 was conducted using HMDS (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd. as a silylating agent with the composition shown in Table 1.
A rubber composition was prepared in the same manner as -1.

[0036]

[Table 1]

Example 2 Experimental Example 2-1 Using the tread rubber composition of Experimental Example 1-1, 165R1
No. 3 studless tires were produced. The internal pressure of this tire is 2 kgf / cm ² and the domestically produced 1500 cc FF A
The vehicle was mounted on a BS (with an anti-lock braking system) vehicle, and the acceleration time and braking stop distance on an icy road were measured under the following conditions.

Measurement place: Sumitomo Rubber Industries, Ltd. Nayoro Test Course Icy Road Temperature: -5 ° C Ice temperature: -2 ° C [Acceleration time] Measure the time required to accelerate from a stop and travel 50 m did. The results are shown in Table 2 by an index with the measurement time of Experimental Example 2-5 using a normal tread rubber composition being 100. The smaller the index, the better.

[Brake Stopping Distance] The distance required to stop the vehicle during traveling at a speed of 30 km / h was measured. The results are shown in Table 2 as an index, with the distance in Experimental Example 2-5 using a normal tread rubber composition as 100. The smaller the index, the better.

[Contact Angle] The contact angle is obtained by measuring the forward contact angle and the receding contact angle using the apparatus shown in FIG.
The result was measured as 100 for the rubber sample of Experimental Example 2-5.
As an index. A larger value indicates a larger contact angle. The value of the contact angle is preferably 108 or more, particularly preferably 113 or more.

[0041]

(Equation 1)

The magnitude of the water repellency can be quantitatively expressed by measuring the contact angle between water and the rubber composition. The larger the contact angle, the more water repellent. Note that the contact angle is measured by the number of samples and the number of measurements so that a difference of the unit value 1 of the average value can be detected at the 5% significance level.

Experimental Example 2-2 Experimental Example 2-2-1 Using the tread rubber composition of Experimental Example 1-2, Experimental Example 2-
A tire was produced in the same manner as in Example 1, and the same test was performed. Table 2 shows the results.

Experimental Example 2-2-2 The tread rubber composition of Experimental Example 1-2 was prepared in the same manner as in Experimental Example 1-1 except that the addition of an antioxidant was carried out during base kneading. -1 to produce a tire in the same manner as
Similarly, the acceleration time and the braking stop distance were measured. Table 2 shows the results.

Since the antioxidant inhibits the reaction of the silylating agent, it is usually added at the time of finish kneading, but those having low reactivity may be added at the time of base kneading. It is more preferable to add at the time of base kneading from the viewpoint of dispersion.

Experimental Examples 2-3 to 2-9 Experimental Examples 1-3, 1-4, 1-5, 1-6, 1-7, 1-
Experimental Example 2-1 Using the Tread Rubber Compositions 8 and 1-9
The same tire was manufactured. Using these tires, the acceleration time, braking stop distance, and contact angle were measured in the same manner as in Experimental Example 2-1. Table 2 shows the results.

[0047]

[Table 2]

In Example 2, the tread rubber composition of the present invention (Experimental Examples 1-1, 1-2, 1-3, 1-4,
Experimental Examples 2-1 and 2-2-1 using 1-8, 1-9),
In 2-2-2, 2-3, 2-4, 2-8, and 2-9, excellent results were obtained. In Experimental Example 2-5, excellent results were not obtained because the tread rubber composition did not contain a silylating agent. In Experimental Example 2-6, an excellent result was not obtained because the tread rubber composition containing the compounding amount of the silylating agent was too large. In Experimental Example 2-7, excellent results were not obtained because the tread rubber composition containing too much carbon black was used.

[0049]

By using the tire tread rubber composition of the present invention, it is possible to obtain a studless tire having excellent grip performance on a frozen road surface and excellent acceleration performance and braking performance.

[Brief description of the drawings]

FIG. 1 is a block diagram of a contact angle measuring device used when measuring a contact angle in Example 2.

────────────────────────────────────────────────── (5) Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C08K 5:54) (72) Inventor Katsumi Terakawa 2-14-24 Miyashita, Nishi-ku, Kobe-shi, Hyogo (56) References JP-A-64 -20246 (JP, A) JP-A-63-270751 (JP, A) JP-A-5-331319 (JP, A) JP-A-3-252431 (JP, A) JP-A-3-252433 (JP, A) JP-A-61-18505 (JP, A) JP-A-5-247256 (JP, A) JP-A-5-51484 (JP, A) JP-A-4-277539 (JP, A) 277537 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 7/00-21/02 C08K 3/00-13/02 C08C 19/25 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. 30 to 80 parts by weight of carbon black based on 100 parts by weight of a rubber component, phenyltrichlorosila
, Diphenyldichlorosilane, phenyltriethoxy
Silane, isobutyltrimethoxysilane, diphenyldi
Methoxysilane, hexamethyldisilazane, N, O-
(Bistrimethylsilyl) acetamide, N, N-bis
(Trimethylsilyl) urea and tert-butyldi
At least selected from the group consisting of methylchlorosilane
A tire tread rubber composition comprising 2 to 15 parts by weight of one silylating agent. Wherein compared to a tire tread rubber composition not blended with silylating agent contact angle with water at least 5% greater claim 1 Symbol mounting of a tire tread rubber composition.