JPH04249552A - Rubber composition for tire - Google Patents

Abstract

PURPOSE:To obtain a rubber composition which has an increased loss factor especially in a high-temperature region and can give an automobile tire improved in grip by mixing a rubber with a 4-phenylurazole compound and a filler. CONSTITUTION:A rubber composition of an increased loss factor is obtained by mixing a rubber such as a natural rubber or a polybutadiene rubber with a filler (e.g. carbon black) and a 4-phenylurazole compound of the formula (wherein R is H, 1-5C alkyl, alkoxy or halogen). Examples of the compounds of the formula include 4-phenylurazole, 4-(4-methylphenyl)urazole and 4-(2- methylphenyl)urazole. The obtained rubber composition can be desirably used as a tread material of a tire and, when mixed with a process oil, the obtained composition can give a tire further improved in grip.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a rubber composition having high grip performance suitable as a tire tread material, and more specifically, to a rubber composition having an increased loss coefficient (tan δ) without impairing mechanical strength. The present invention relates to a rubber composition.

0002

[Background Art] In recent years, as automobiles have become more sophisticated, roads have become more paved, and expressway networks have developed, there has been an increasing demand for improved tire grip performance, which is closely related to automobile acceleration and braking performance. There is. It is known that in order to obtain high grip performance, it is sufficient to increase the energy loss due to friction between the tire tread and the road surface.
) is in demand.

Conventionally, techniques for increasing tan δ during deformation include a method of using styrene-butadiene copolymer rubber with a high styrene content as a base, a method of adding a large amount of process oil, and a method of adding highly reinforcing carbon black. A method of adding a large amount has been proposed. Furthermore, JP-A-64-70539 discloses p-methacryloyl-N'-phenyl-p-phenylenediamine and other
It is described that grip properties can be improved by blending a phenylenediamine derivative into rubber.

0004

[Problems to be Solved by the Invention] When using styrene-butadiene rubber with a high styrene content, although some improvement in grip performance can be seen, this alone has not always been sufficient. Furthermore, although the grip performance is improved by adding a large amount of process oil or highly reinforcing carbon black, the addition of a large amount increases the heat generation property of the rubber, and as a result, the strength properties and wear resistance deteriorate. There was a problem of a significant drop in the performance. On the other hand, Japanese Patent Publication No. 64-7
Although the method of blending a p-phenylenediamine derivative described in Publication No. 0539 increases the tan δ of the rubber, it has become clear that such blending causes a decrease in strength properties.

[0005] Against this background, the present inventors have developed ta
As a result of intensive research to develop a compound that can sufficiently increase nδ and thereby improve grip performance, especially grip performance when the tire becomes hot, without impairing mechanical strength, we have found that: This led to the present invention.

[0006]

[Means for Solving the Problems] That is, the present invention provides rubber with a filler and the following general formula (I).

[0007]

[C3]

[0008] A rubber composition containing a 4-phenylurazole compound represented by the following formula (wherein R is a hydrogen atom, an alkyl or alkoxy group having 1 to 5 carbon atoms, or a halogen atom) is provided. The present invention also provides a method of increasing the loss factor of rubber by blending a filler and a 4-phenylurazole compound represented by the general formula (I) into rubber.

As the 4-phenylurazole compound represented by the general formula (I), commercially available products can be used as they are, and for example, the corresponding 1-ethoxycarbonyl-4-phenyl semicarbazide compound can be used as
It can be produced by a deethanol cyclization reaction in which it is heated with an aqueous potassium hydroxide solution, cooled, and acidified with concentrated hydrochloric acid.

In the general formula (I), R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen atom. Examples of alkyl groups include methyl, ethyl, propyl, butyl and pentyl, and examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy and pentyloxy, each having 3 or more carbon atoms. It may be chain-like or branched. An example of a halogen atom is
These include fluorine, chlorine, bromine, and iodine. General formula (I)
R in is preferably hydrogen, or an alkyl or alkoxy group having a small number of carbon atoms such as methyl, ethyl, methoxy, or ethoxy. In the present invention, a compound in which R in formula (I) is a hydrogen atom, ie, 4-phenylurazole, is preferably used.

The above general formula (
Examples of the 4-phenylurazole compound I) include the following. (1) 4-phenylurazole (2) 4-(4-methylphenyl)urazole (3
) 4-(2-methylphenyl)urazole (4)
4-(4-t-butylphenyl)urazole (5)
4-(4-n-butylphenyl)urazole (6)
4-(4-methoxyphenyl)urazole (7)
4-(3-ethoxyphenyl)urazole (8) 4
-(4-chlorophenyl)urazole (9) 4-(
2-chlorophenyl)urazole (10) 4-(4
-iodophenyl)urazole

When the 4-phenylurazole compound of the general formula (I) is added to rubber, each compound may be added alone, a mixture of multiple compounds may be added, or a mixture of multiple compounds may be used. It may be mixed with a carrier such as clay that does not affect the physical properties of the rubber. Such a 4-phenylurazole compound can be added at any stage of producing compounded rubber. When compounding rubber, the amount of 4-phenylurazole compound used is not limited, but generally,
It is preferable to use it in a range of about 0.1 to 20 parts by weight per 100 parts by weight of rubber.

[0013] As the filler used in the present invention, various fillers used in the rubber industry can be used, but carbon black is generally preferred. The type of carbon black is not particularly limited, and various carbon blacks conventionally employed in the rubber industry can be used in the present invention. In addition, in order to improve the grip performance of tires, SAF black, ISAF
Black, HAF black, etc. Nitrogen adsorption specific surface area 80
-250 m2/g of highly reinforcing carbon black is used, and it is preferable to use such highly reinforcing carbon black in the present invention as well. The amount of the filler blended is not particularly limited, but is generally preferably in the range of about 20 to 200 parts by weight per 100 parts by weight of rubber.

[0014] In addition to natural rubber, the types of rubber that can be used in the present invention include polyisoprene rubber (IR),
Various types of styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), isoprene-isobutylene copolymer rubber (IIR), ethylene-propylene-diene copolymer rubber (EPDM), etc. Synthetic rubber, blends of natural rubber and synthetic rubber, and SBR and IR, SBR and BR
Blends of synthetic rubber are exemplified. Note that recently, SBR with a particularly high styrene content has been preferably used to improve the grip properties of tires, and such SBR with a high styrene content can also be used in the present invention. The present invention has a styrene content of 20 to 50
It is also effective against SBR of % by weight, and such SBR
BR is one of the preferred rubbers. The type of SBR may be either a solution polymerization type or an emulsion polymerization type.

[0015] When formulating the tire tread rubber material,
Conventionally, a method of blending a process oil in order to improve the grip performance of a tire has often been used, but it is also possible and preferable to use a process oil in combination in the present invention. The amount of process oil blended is not particularly limited, but is generally 200 parts by weight or less per 100 parts by weight of rubber, preferably selected from the range of 5 to 200 parts by weight. The type of process oil is also not limited in the present invention, and various process oils conventionally used in the rubber industry can be used.

In addition, in the present invention, various rubber chemicals commonly used in the rubber industry such as anti-aging agents, vulcanizing agents, vulcanization accelerators, retarders, peptizers, and softeners are used in combination in the same manner as in the past. It goes without saying that it is okay to do so.

[0017]

[Example] Next, the present invention will be explained in more detail with reference to Examples in which the compound represented by the general formula (I) was blended into rubber and the physical properties were evaluated, but the present invention is not limited by these. It's not a thing. In the following examples, all percentages and parts are by weight unless otherwise specified.

The test compounds used in the examples are as follows, and are indicated by the respective symbols below. A: 4-phenylurazole B: 4-(4-methylphenyl)urazole C:
4-(4-t-butylphenyl)urazole D:
4-(2-methylphenyl)urazole E: 4-(
3-ethoxyphenyl)urazole F: 4-(4-
Chlorophenyl)urazole X: N-methacryloyl-N'-phenyl-p-phenylenediamine

Example 1 [Blending recipe] Styrene-butadiene copolymer rubber
Listed in Table 1 (Styrene content: 35%, containing 37.5 parts of aromatic oil per 100 parts of rubber) Butadiene rubber (BR-
01)
Listed in Table-1 Natural
rubber
Listed in Table-1
ISAF carbon black
Table-1
Description stearic acid

Part 3 Zinc
flower
Part 5 Aromatic process oil
Table-1
Description Vulcanization accelerator

1 part (N-cyclohexyl-2-benzothiazolesulfenamide) a
Oh

Part 2 Test compound

Listed in Table-1

2 manufactured by Toyo Seiki as a Banbury mixer
Using a 50ml Labo Plastomill R, the test compound, carbon black, stearic acid, process oil, and zinc white were added to the rubber based on the above formulation at an oil bath temperature of 170°C, and the mixture was mixed at a mixer rotation speed of 50 rpm. Kneaded for 5 minutes. The rubber temperature at this time is 160-170℃
Met. This rubber compound is then transferred to an open mill,
The vulcanization accelerator and sulfur shown in the above formulation were added and kneaded at a temperature of 40 to 50°C.

[0021] Furthermore, after being vulcanized using a vulcanization press to form a predetermined shape, it was subjected to tan δ measurement. tan
δ was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under the condition of a frequency of 10 Hz from -50°C to 100°C.
Performed at temperatures up to ℃. In addition, as a mechanical strength test,
Vulcanized rubber test piece (JIS
M100 and M300 were measured at room temperature using a dumbbell No. 3 by K 6301. Among the results obtained, tan δ at 80°C, M100 at room temperature
and M300 are shown in Table-1. In the table, M300
A blank column means that measurement was not possible.

[0022]

[0023]

[0024]

[0025]

Effects of the Invention The rubber composition containing the 4-phenylurazole compound according to the present invention effectively improves the tan δ in the high temperature region of 60°C or higher, which corresponds to the grip force when the tire becomes hot. Moreover, there is almost no deterioration in strength properties. Therefore, by applying the rubber composition of the present invention to the tread portion of a tire, it is possible to obtain a tire with excellent grip performance, which is closely related to the acceleration performance and braking performance of an automobile.

Claims (3)

[Claims] Claim 1: Rubber containing a filler and 4-phenyl represented by the following general formula [Formula 1] (wherein R is a hydrogen atom, an alkyl or alkoxy group having 1 to 5 carbon atoms, or a halogen atom) A rubber composition containing a urazole compound. 2. The rubber composition according to claim 1, wherein the 4-phenylurazole compound is 4-phenylurazole. 3. A filler and 4-phenyl represented by the following general formula [Formula 2] (wherein R is a hydrogen atom, an alkyl or alkoxy group having 1 to 5 carbon atoms, or a halogen atom) in the rubber. A method for increasing the loss coefficient of rubber, which comprises blending a urazole compound.