JPS62115045A - Rubber composition - Google Patents

Abstract

PURPOSE:To provide a rubber compsn. which gives a pneumatic tire having little dependence of tan delta on temp., a high tan delta and excellent grip, by blending a rubber component with a mercapto compd. and a disulfide compd. CONSTITUTION:100pts.wt. rubber component composed of natural and/or synthetic rubber such as polybutadiene rubber is blended with 0.1-10pts.wt. mercapto compd. of formula I [wherein R is (COOH-, alkoxycarbonyl-, N- alkylamido-, N-anilino-amido-or NH2-substd.) 1-18C alkyl, aryl, aralkyl, alkaryl] (e.g., N-stearyl-alpha-mercapto-acetamide) and/or disulfide compd. of formula II [e.g., alpha,alpha'-dithiobis (N-anilinoacetamide)].

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a rubber composition applicable to all rubber products such as tires, conveyor belts, hoses, etc. The present invention relates to a rubber composition that can be applied to tires.

(Conventional technology) Recently, with the improvement of automobile performance and the development of expressway networks, there has been an increasing demand for pneumatic tires with high maneuverability. This has become an important required characteristic. Tires with high such characteristics can run faster and more accurately while maintaining safety.

Conventionally, in order to obtain high grip performance, a styrene-butadiene copolymer rubber with a high styrene content (rubber with a high glass transition temperature) was selected as the trend rubber composition of a tire, or process oil and carbon black were selected. It was necessary to select a highly filled compounding system to increase the loss coefficient tan δ of the rubber composition.

(Problems to be Solved by the Invention) However, there is a limit to the high filling of Procell oil or Kern black, and there is a drawback that if they are filled too much, the fracture characteristics and wear resistance are significantly reduced. Furthermore, if the styrene content in the copolymer is increased, the grip performance will certainly increase, but as the temperature of the rubber increases due to tire running, the JAN δ value will decrease, resulting in a sharp drop in grip performance. There was a drawback that it did. As a method for improving the grip performance associated with this temperature rise, Japanese Patent Application Laid-Open No. 187011/1987 describes a method of combining monomers such as 1,3-butadiene, styrene, or isoprene with diphenyl-2-
Methacryloyloxyethyl phosphate and diphenyl
It is described that a copolymer rubber obtained by copolymerizing an acrylate or methacrylate compound containing a diphenyl phosphate group such as 2-acryloyloxyethyl phosphate is used. However, such a method is not only inapplicable to natural rubber, but also has the problem that depending on the manufacturing conditions, the inherent properties of the polymer, such as styrene-butadiene copolymer rubber or polybutadiene rubber, may be impaired. There was a point.

Therefore, an object of the present invention is to provide a rubber composition that has been unable to be obtained in the past, which has a small temperature dependence of tan δ and a high jan δ value, and does not impair the original properties of the polymer. be.

(Means for Solving the Problems) As a result of intensive studies to solve the above problems, the present inventors have determined that the above problems can be achieved by blending a specific amount of a specific mercapto compound and/or a specific disulfide compound into a rubber component. It was confirmed that the problem could be solved, and the present invention was completed.

That is, the present invention applies the following -a formula (I) to 100 parts by weight of a rubber component consisting of natural rubber and/or synthetic rubber.
A mercapto compound represented by and/or a disulfide compound represented by the following general formula (■), R-3H (1) R-S-S-R (II) (R in the formula is a carboxyl group, an alkoxycarbonyl group , N-alkylamide group, N-anilinoamide group, or an alkyl group with 1 to 18 carbon atoms optionally substituted with an amino group, allyl group, aralkyl group, or alkaryl group) of 0.1 to 10% by weight The present invention relates to a rubber composition characterized in that:

In the present invention, natural rubber can be used alone or in a blend with synthetic rubber as the rubber component. Such synthetic rubbers include synthetic polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, etc., and they may be used alone or in a blend.

In the present invention, the mercapto compound includes, for example, N
-stearyl-α-mercaptoacetamide, N-(1
-naphthyl)-α-mercaptoacetamide, α-mercaptoacetanilide, N-(4-ethoxycarbonylphenyl)-α-mercaptoacetamide, N-(5-
carboxypentyl)-α-mercaptoacetamide,
N-(4-carboxyphenyl)-α-mercaptoacetamide, phenylmercaptan, 2-ethylhexyl-α-mercaptoacetate, stearyl-α-mercaptoacetate or stearylmercaptan, and disulfide compounds such as α, α′ −
These include dithiobis(N-anilinoacetamide) and diphenyl disulfide. These compounds may be used alone or in combination of two or more.

In the present invention, the compounding amount of these compounds is 100% of the rubber component.
The reason for specifying 0.1 to 10 parts by weight is that if the amount is less than 0.1 parts by weight, the desired effect of the present invention cannot be obtained, and if it exceeds 10 parts by weight, the This is because not only the effect commensurate with the increase in amount cannot be obtained, but also the scorch property and various physical properties after vulcanization are adversely affected, which is undesirable.

In addition, in the present invention, the above-mentioned mercapto compound and/or
In addition to disulfide compounds, compounding agents commonly used in the rubber industry, such as softeners, anti-aging agents, vulcanization accelerators,
Vulcanization accelerators, vulcanizing agents, and the like may be blended within the usual blending amounts as necessary.

(Function) The mercapto compound and disulfide compound used in the present invention modify the rubber molecule by adding it to the double bond of the rubber molecule during kneading or vulcanization of the rubber composition, thereby modifying the main chain of the rubber molecule. It has the effect of increasing the slip resistance, which has the effect of reducing the decrease in tan δ value at high temperatures.

(Example) Next, the present invention will be explained with reference to Examples and Comparative Examples.

First, various mercapto compounds and disulfide compounds were synthesized by the methods described in the following reference examples.

In a 500 ml four-bottle flask equipped with a stirrer with a mercury seal, a thermometer, a reflux condenser, and a water separator, 0.5 mol of the amine compound shown in Table 1 below, 200 ml of toluene, and 69.0 g (0.0 g) of thioglycolic acid were added. ,7
After stirring and refluxing for 5 hours, 9.5 m# of water was distilled out of the system, and the reaction was completed.

Next, after cooling to 0° C., the precipitated crystals were filtered, thoroughly washed with benzene on a filter paper, and then recrystallized with various solvents shown in Table 1. The generated crystals were heated at 50℃ for 24 hours.
The desired product was obtained by drying with hot air for several hours.

Actual amounts of various raw material amine compounds, product yields,
The yield and melting point are also listed in Table 1.

In a 200 ml four-neck flask equipped with a stirrer with a mercury seal, a thermometer, a reflux condenser, and a water separator, 25.9 g (0.24 M) of phenylhydrazine and 25.9 g of dithioglycolic acid were added. 0g (0,132M) and toluene 1
OOII+1 was charged, the mixture was stirred and refluxed for 2 hours, and after 3 ml of water was distilled out of the system, the reaction was completed.

Next, after cooling to 0°C, the precipitated crystals were filtered and subsequently recrystallized with methanol. 50 of the generated crystals
Dry with hot air at ℃ for 24 hours to obtain the desired α,α'-dithiobis(N-anilinoacetamide) with a melting point of 173.5~
A temperature of 175.0° C. was obtained in a yield of 16.8 g and a yield of 38.7×.

1 to 7, rl 37.5 parts by weight of aroma oil per 100 parts by weight of styrene-butadiene rubber, l5 AF Force-Bon Black 65
A rubber composition containing parts by weight and 3 parts by weight of zinc white,
2 parts by weight of the mercapto compounds or disulfide compounds of Reference Examples 1 to 7, respectively, and variable amounts of 1.3-diphenylguanidine, 2-mercaptobenzothiazole and sulfur were blended and vulcanized so that each had approximately the same modulus. did. For each of the obtained vulcanizates, 2
Tan δ was measured at 0°C and 80°C. The results obtained are shown in Table 2 below.

For comparison, the same evaluation was also conducted on a vulcanizate produced in the same manner as in the above example except that the specific mercapto compound and the specific disulfide compound of the present invention were not blended.

The obtained results are also listed in Table 2.

As is clear from Table 1, all of the rubber compositions of the present invention shown in Examples have larger jan δ values in the high temperature range than the rubber composition of Comparative Example 1, and have a tan δ value of 20°C and 80°C.
The temperature dependence of tan δ, which is expressed by the difference in °C jan δ values, is reduced.

・-Sei8~lO2 Eave side 2 Styrene butadiene rubber with 35% styrene content 10
0 parts by weight of l5AF force - 80 parts by weight of Bombrack,
100 parts by weight of aroma oil, 1 part by weight of stearic acid, 1 part by weight of anti-aging agent (IPPD), 3 parts by weight of zinc white, 0.3 parts by weight of accelerator DPG, 0.7 parts by weight of accelerator DM, and 1.5 parts by weight of sulfur. A tread was produced using a rubber composition in which 5 parts by weight of each of the compounds of Reference Examples 2 and 4 was blended with a rubber composition containing 1.9 parts by weight, and a rubber composition in which 3 parts by weight of each of the compounds of Reference Examples 2 and 7 was blended. Size 2051
515-13 (for front wheel), 2251515-13
A tire (for the rear wheel) was manufactured.

These tires were used to run 20 laps around a circuit consisting of 4.41 km per lap, and the difference between the first lap time and the 20th lap time and the best lap time were measured. For comparison,
The time difference and best lap time of tires manufactured in the same manner as in the above example except that the specific mercapto compound and disulfide compound of the present invention were not blended were each expressed as an index with 100 as 100. The obtained results are shown in the third section below.
Shown in the table. The larger the value, the higher the grip performance.

Table 3 (Effects of the Invention) As explained above, the rubber composition of the present invention has a structure in which a specific amount of a specific mercapto compound or a disulfide compound is blended into the rubber component, so that the jan δ value in the high temperature region is increased. Largely, 20℃ tan δ value and 80℃ ta
The temperature dependence of jan δ, which is expressed by the difference in n δ values, is small, and therefore, if such a rubber composition is used especially for tire treads, as seen in Examples 8 to 10, the tire temperature during running will decrease. Since it becomes possible to suppress the decrease in the jan δ value accompanying the increase, the effect of improving the grip performance can be obtained.

Claims (1)

[Claims] 1. A mercapto compound represented by the following general formula (I) and/or a mercapto compound represented by the following general formula (II) with respect to 100 parts by weight of a rubber component consisting of natural rubber and/or synthetic rubber. A disulfide compound, R-SH (I) R-S-S-R (II) (R in the formula is a carboxy group, an alkoxycarbonyl group,
0.1 to 10 parts by weight of an alkyl group having 1 to 18 carbon atoms, an allyl group, an aralkyl group, or an alkaryl group optionally substituted with an N-alkylamide group, N-anilinoamide group, or amino group A rubber composition comprising: 2. The mercapto compound is N-stearyl-α-mercaptoacetamide, N-(1-naphthyl)-α-mercaptoacetamide, α-mercaptoacetanilide, N-
(4-ethoxycarbonylphenyl)-α-mercaptoacetamide, N-(5-carboxypentyl)-α-
Mercaptoacetamide, N-(4-carboxyphenyl)-α-mercaptoacetamide, phenylmercaptan, 2-ethylhexyl-α-merptoacetate,
The rubber composition according to claim 1, which is stearyl-α-mercaptoacetate or stearyl mercaptan. 3. The disulfide compound is α,α′-dithiobis(N-
2. The rubber composition according to claim 1, wherein the rubber composition is anilinoacetamide) or diphenyl disulfide.