JPH07119320B2 - Method for producing rubber composition containing dinitrodiamine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for producing a rubber composition containing dinitrodiamines, and particularly to a method for producing the rubber composition with improved processability.

<Prior Art> In recent years, in the automobile industry, demands for improving various physical properties of each product and part are increasing. For example, taking rubber products such as tires and anti-vibration rubber as examples, it is possible to improve fuel economy, improve durability, prolong economic life by extending product life, and improve ride comfort by reducing vibration and noise. It is becoming an important issue. Therefore, it is important to improve the dynamic properties such as resilience, heat resistance, and dynamic ratio of the vulcanized rubber used for such rubber products.

As methods for improving dynamic properties, methods such as improvement in rubber microstructure and molecular weight distribution, improvement in compounding formulation of organic rubber chemicals and reinforcing agents, addition of dynamic physical property improvers, etc. are also known. Among these methods, the method of adding a dynamic physical property improver has attracted attention because it can improve the dynamic characteristics more easily than other methods and can be applied to natural rubber.

As such a dynamic physical property improver, JP-A-63-23942 discloses the following general formula [I]. (In the formula, X is a divalent chain aliphatic group, a cycloaliphatic group or an aromatic group, and may contain halogen or oxygen. R ¹ is a hydrogen atom, a chain aliphatic group, A cyclic aliphatic group or an aromatic group, but when both X and R ¹ are chain aliphatic groups, nitrogen atoms may be further linked to each other via R ^1. R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and R ² and R ³ may combine to form a ring.) And the like. Since these dinitrodiamines impart excellent dynamic properties to rubber, they have been applied to tires and anti-vibration rubber.

However, the dinitrodiamines have a coupling function between rubber and carbon black, and further have a function of improving the dispersibility of carbon black. The Mooney viscosity becomes high and the processability tends to deteriorate. For this reason, there is a problem that molding defects sometimes occur, which hinders the production of rubber products.

<Problems to be Solved by the Invention> From such a background, the present inventors have made the most of the dynamic characteristics characteristic of the dinitrodiamines to the maximum extent, and have a rubber composition containing the dinitrodiamines. As a result of earnest research to improve the workability of, the present invention was completed.

<Means for Solving the Problems> That is, according to the present invention, in producing a rubber composition containing carbon black and dinitrodiamines represented by the general formula [I], carbon black and dinitrodiamines are first added to a rubber component. The present invention provides a method for producing a dinitrodiamine-containing rubber composition having excellent processability, which comprises blending and then blending stearic acid.

Specific examples of the dinitrodiamines of the general formula [I] used in the present invention include the following compounds. In the following examples, -Z is Indicates.

_{(1) Z-NHCH 2 2} NH-Z (2) Z-NHCH 2 3 NH-Z (3) Z-NHCH 2 4 NH-Z (4) Z-NHCH 2 6 NH-Z (5) Z-NHCH _{2 10} NH-Z (6) Z-NHCH _{2 12} NH-Z (8) NO ₂ CH _{2 2} NHCH _{2 2} NHCH _{2 2} NO ₂ (9) NO ₂ CH _{2 2} NHCH _{2 6} NHCH _{2 2} NO ₂ Thus, the substituent X in the general formula [I] is 2
It is a valent chain aliphatic group, a cycloaliphatic group or an aromatic group, and can contain a halogen in the group as in the 33rd and 34th examples, and as in the 40th to 43rd examples. The base may contain oxygen. Among these, those in which X is a chain aliphatic group, particularly a chain aliphatic group having 4 to 12 carbon atoms are preferably used.

R ¹ in the general formula [I] is a hydrogen atom, a chain aliphatic group, a cycloaliphatic group or an aromatic group, and when X and R ¹ are both chain aliphatic groups, as in the first 23 patients and the 24 patients, via R ¹ further linked nitrogen atom together, X, are also encompassed that form a ring with R ¹ and the two nitrogen atoms.

Further, R ² and R ³ in the general formula [I], which may be the same or different, are each a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. Incidentally, as in the 12th example, the 13th example, the 22nd example and the 30th example, R ² and R ³
Also included are those in which are bonded to form a ring.

The form of compounding such dinitrodiamines with rubber is arbitrary, and its compound alone, a mixture of a plurality of compounds, a mixture with a carrier such as clay that does not affect the physical properties of rubber, and further described below. It may take a form such as a mixture with various compounding agents. Therefore, any of these forms can be added to the rubber.

The amount of dinitrodiamines used is not particularly limited, but is usually 0.1 to 10 parts by weight per 100 parts by weight of rubber.

As carbon black, various carbon blacks having different reinforcing properties that have been conventionally used, for example, SA
F, ISAF, HAF, SPF, FEF, GPF, SRF, MT and the like can also be used in the present invention, and the type thereof is not particularly limited. The addition amount thereof is not particularly limited, but is usually 10 to 150 parts by weight per 100 parts by weight of rubber.

As the rubber that can be used in the present invention, in addition to natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, acrylonitrile-butadiene copolymer rubber, isoprene-isobutylene copolymer rubber, ethylene-propylene-diene copolymer Various synthetic rubbers such as rubber are exemplified, and these rubbers can be used alone or blended with different kinds of rubber.
Among these, natural rubber alone or a blend system with a synthetic rubber mainly composed of natural rubber is preferable.

Carbon black and the dinitrodiamines represented by the above general formula [I] are added to such a rubber component, and stearic acid is added. One of the important constitutions of the present invention is that of stearic acid. It is in the compounding period. That is, for rubber components such as natural rubber and / or synthetic rubber,
Only by adding stearic acid after adding carbon black and dinitrodiamines, a rubber having a low Mooney viscosity and excellent processability can be utilized while maximally utilizing the dynamic characteristics characteristic of the dinitrodiamines. A composition is obtained.

The stearic acid used in the present invention has been conventionally generally used as one of rubber compounding agents, but its addition was usually performed before or almost simultaneously with carbon black. When the above-mentioned dinitrodiamines are blended together with carbon black according to the conventional technique, the Mooney viscosity of the blended amount of rubber is increased.

On the other hand, the Mooney viscosity can be lowered by changing the addition timing of stearic acid according to the present invention, that is, by adding stearic acid after adding carbon black and dinitrodiamines to the rubber component. The amount of stearic acid added is not particularly limited, but is usually 0.3 to 5 parts by weight per 100 parts by weight of rubber.

In the present invention, the compounding machine used for compounding the rubber may be one commonly used in the rubber industry and is not particularly limited. For example, an open roll, a Banbury mixer, a kneader and the like are suitable.

In addition, when compounding rubber, carbon black and the dinitrodiamines are preferably compounded at about 120 to 220 ° C., since compounding at high temperature has a greater effect of improving rubber physical properties. On the other hand, stearic acid may be blended at a temperature about the same as the blending temperature of carbon black and dinitrodiamines, but blending at a relatively low temperature is more effective in improving processability, so a temperature of about 50 to 120 ° C is preferable. It is preferable to blend in.

In the present invention, various other compounding agents commonly used in the rubber industry can also be used according to the purpose. Usually, fillers, sulfur, peptizers, zinc white, various vulcanization accelerators, scorch retarders, process oils, processing aids, antioxidants, antiozonants, waxes and the like are used. The type and amount of these compounding agents and the order of compounding can be selected as necessary and are not particularly limited in the present invention.

The rubber composition obtained according to the present invention is preferably used, for example, as various members of a tire, particularly a tread portion, or a vibration isolating rubber. For example, this rubber composition can be applied to the tread portion or other members and molded by a method commonly used in the tire industry to obtain a tire. Further, the rubber composition can be molded into an appropriate shape or adhered to a metal to obtain a vibration-proof rubber.

<Example> Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
In the following examples, parts are based on weight unless otherwise specified.

Further, the dinitrodiamines used in the examples are as follows, and are indicated by respective symbols below.

A: N, N'-bis (2-methyl-2-nitropropyl)
-1,6-diaminohexane B: N, N'-bis (2-methyl-2-nitropropyl)
-1,4-Diaminobenzene Example 1 Using a Toyo Seiki 250 ml Labo Plastomill as a Banbury mixer, an oil bath temperature of 170 ° C, 100 parts of natural rubber, 45 parts of HAF carbon black and 1 part of dinitrodiamine (A). Then, 3 parts of aromatic process oil and 5 parts of zinc white were added, and the mixture was kneaded at a mixer rotation speed of 60 rpm for 5 minutes. The temperature of the rubber at this time was 162 ° C.

Next, in a Labo Plastomill with an oil bath temperature of 90 ° C., 3 parts of stearic acid, 1.5 parts of sulfur, and Nt as a vulcanization accelerator were used.
-Butyl-2-benzothiazylsulfenamide 1 part and tetramethylthiuram disulfide 0.5 part, N- (cyclohexylthio) phthalimide 0.2 part as scorch retarder, and N-phenyl-N'-1,3- 2 parts of dimethylbutyl-p-phenylenediamine was additionally charged and kneaded for 3 minutes at a mixer rotation speed of 60 rpm. The temperature of the rubber at this time was 93 ° C. The Mooney viscosity of the compounded rubber thus obtained was measured.

Furthermore, after vulcanizing at 145 ° C for 25 minutes with a vulcanizing press,
It was subjected to various tests. Each test method is as follows.

(1) Mooney viscosity According to JIS K-6300, ML _{1 + 4} was measured at 100 ° C.

(2) Resilience It was measured using a Lupke type tester.

(3) Heat resistance Measured according to ASTM D-623-58. That is, using a Goodrich type heat generation tester, load 35 1bs, stroke 6.35 mm, frequency 1800 rpm, tank temperature 40 ℃, 40
The heat generation temperature after minutes (displayed by the difference between the rubber temperature after 40 minutes and the initial rubber temperature) was measured.

(4) 60 ° C. tan δ (loss coefficient) The viscosity was measured using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho under the conditions of static load 300 g, frequency 50 Hz, and temperature 60 ° C.

(5) Dynamic magnification Using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho, temperature
It was measured at 25 ° C and a vibration frequency of 100 Hz.

Example 2 Dinitrodiamines (A) are replaced with dinitrodiamines (B)
A rubber composition was prepared in the same manner as in Example 1 except that the above was changed to, and the same test was performed.

Comparative Example A rubber composition was prepared in the same manner as in Example 1 except that 3 parts of stearic acid was not added in the second step and was mixed with carbon black and the dinitrodiamines (A) in the first step, A similar test was conducted.

The test results of Examples 1 and 2 and Comparative Example are summarized in Table-1.

<Effects of the Invention> According to the present invention, in the production of a rubber composition containing the dinitrodiamines represented by the general formula [I] and having excellent dynamic properties, it is possible to improve the processability, which has been a difficult point in the past. Get rid of. That is, by changing the order of addition of stearic acid, the Mooney viscosity of the unvulcanized rubber can be reduced, thereby eliminating troubles during the production of rubber products.

Claims (3)

[Claims] 1. A rubber component comprising carbon black and the following general formula [I]: (In the formula, X is a divalent chain aliphatic group, a cycloaliphatic group or an aromatic group, and may contain halogen or oxygen. R ¹ is a hydrogen atom, a chain aliphatic group, A cyclic aliphatic group or an aromatic group, but when both X and R ¹ are chain aliphatic groups, nitrogen atoms may be further linked to each other via R ^1. R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and R ² and R ³ may combine to form a ring.) A method for producing a dinitrodiamine-containing rubber composition having excellent processability, which comprises blending an acid. 2. The method according to claim 1, wherein the rubber component is a natural rubber alone or a blend system with a synthetic rubber mainly composed of natural rubber. 3. The method according to claim 1, wherein X in the general formula [I] is a chain aliphatic group having 4 to 12 carbon atoms.