JP2522438B2 - Rubber composition with excellent dynamic properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a rubber composition having stable scorch characteristics and excellent dynamic characteristics.

<Prior Art> In recent years, in the automobile industry, there is an increasing demand for various types of products and parts to improve their physical properties. For example, taking rubber products such as tires and anti-vibration rubber as examples
Pursuit of economic efficiency such as improvement of durability and extension of product life, and improvement of riding comfort such as reduction of vibration and noise have become important issues. 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.

Conventionally, 4-nitroso-N- (2-nitro-2-methylpropyl) aniline has been used as such a dynamic property improving agent.
Nitroso compounds such as 5-nitroso-8-hydroxyquinoline are known. However, the hygiene of nitrosamines has become a social issue, making their use difficult. Therefore, as a dynamic property improver containing no nitroso group, an 8-hydroxyquinoline derivative is proposed in JP-A-58-118837, and a nitro compound containing sulfur is disclosed in JP-A-59-18740. Proposed. Although these compounds are effective in improving resilience and heat resistance, they have a problem of reducing flex cracking resistance.

On the other hand, the following general formula [I] proposed by JP-A-63-23942 is proposed. (In the formula, X is a divalent chain aliphatic group, a cycloaliphatic group or an aromatic group, which 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.) The dinitrodiamines represented by the above have the above-mentioned problems. It is possible to obtain a rubber composition having excellent dynamic properties when compounded with rubber.

Since these dinitrodiamines impart excellent dynamic properties to rubber, they have been applied to tires and anti-vibration rubber. However, these dinitrodiamines
Although the scorch property is improved as compared with the above-mentioned 8-hydroxyquinoline derivative and the like, since it is basic, the scorch property tends to be accelerated. Therefore, the processing step and vulcanization time of the rubber composition containing the dinitrodiamines have to be changed to some extent as compared with the case of a normal rubber composition not containing the compound.

Conventionally, as a method of delaying the scorch property, it has been known to add a scorch retarder, and particularly N- (cyclohexylthio) phthalimide is often used. Although this compound is effective for delaying the scorch property, it decreases the dynamic properties and has a bloom property, so it is necessary to minimize the addition amount, and practically there is a problem. there were.

<Problems to be Solved by the Invention> From such a background, the present inventors intend to develop a rubber composition that maximizes the dynamic characteristics that are characteristic of the dinitrodiamines and that also has stable scorch properties. As a result of earnest research, the present invention has been completed.

<Means for Solving the Problems> The present invention is a composition containing carbon black,
Raw rubber 100 made of natural rubber and / or synthetic rubber
0.1 to 10 parts by weight of dinitrodiamine represented by the general formula [I], and 2,3,5,6-tetrachloro-
The present invention provides a rubber composition containing 0.1 to 3 parts by weight of 1,4-benzoquinone.

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
It is a divalent chain aliphatic group, a cycloaliphatic group or an aromatic group, which can contain a halogen in the group as in the above 33rd and 34th examples, and can also be used in the 40th to 43rd examples. Thus, oxygen can be contained in the group. Among these, X is preferably a chain aliphatic group, particularly a chain aliphatic group having 4 to 12 carbon atoms.

Further, R ¹ in the general formula [I] is a hydrogen atom, a chain aliphatic group, a cycloaliphatic group or an aromatic group, and when all the X delay R ¹ are 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
Those in which R ³ is bonded to form a ring are also included.

The form of compounding such dinitrodiamines with rubber is arbitrary, and the 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 other It may take the form of a compounding agent, for example, 2,3,5,6-tetrachloro-1,4-benzoquinone which is another component of the present invention, or a mixture with various compounding agents described later. Therefore, any of these forms can be added to the rubber.

The amount of the dinitrodiamines used is 0.1 to 10 parts by weight per 100 parts by weight of the rubber, because if it is too small, the effect of improving the dynamic properties is insufficient, and if it is too large, it becomes uneconomical, and preferably It is in the range of 0.2 to 3 parts by weight.

The amount of 2,3,5,6-tetrachloro-1,4-benzoquinone used as the other component of the present invention is too small, the scorch property improving effect is insufficient, and if it is too large, the mechanical properties are insufficient. Therefore, the range is 0.1 to 3 parts by weight per 100 parts by weight of rubber.

This 2,3,5,6-tetrachloro-1,4-benzoquinone is
In JP-A-53-94577, JP-A-63-86728 and the like, it is known to compound with rubber in order to improve the adhesiveness of rubber, but the above general formula [I] The use in the coexistence with dinitrodiamines represented by is first revealed by the present invention. Further, in the present invention, in order to improve the scorch property of the dinitrodiamines while maximizing the excellent dynamic characteristics of the dinitrodiamines represented by the general formula [I], 2,3,5,6-tetrachloro Since a specific amount of -1,4-benzoquinone is added, a composition having excellent dynamic properties and no blooming can be obtained only by adding the specific amount.

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, preferred rubbers are natural rubber alone or blended with synthetic rubber mainly containing natural rubber (that is, containing 50% by weight or more of natural rubber), styrene-butadiene copolymer rubber alone or styrene-butadiene copolymer. Examples thereof include a blend system containing a rubber as a main component (that is, containing 50% by weight or more of a styrene-butadiene copolymer rubber) and a natural rubber or a butadiene rubber.

Natural rubber-based materials are often used as tires or anti-vibration rubbers for large vehicles, and styrene-butadiene copolymer rubber-based materials are often used as tires for passenger cars. In order to enhance the dynamic properties of such materials and to improve their scorchability, the dinitrodiamines of the general formula [I] and 2,3,5,6-tetrachloro-1,4-benzoquinone are compounded according to the invention. It is effective to do.

When the present invention is applied using a styrene-butadiene copolymer rubber-based material, compared with the case where only the dinitrodiamines of the general formula [I] are blended, the dynamic properties such as resilience and heat resistance of the vulcanized rubber are improved. The characteristics can be further improved. Styrene-butadiene copolymer rubber is
It may be an emulsion polymerization type or a solution polymerization type. Also, excellent dynamic properties can be imparted to a modified rubber having a modified rubber microstructure or molecular weight distribution.

The carbon black used in the present invention includes various carbon blacks having different reinforcing properties that have been conventionally used, for example, SAF, ISAF, HAF, SPF, FEF, GPF, SRF, MT, etc., and the types thereof are not particularly limited. Not done. For the styrene-butadiene copolymer rubber material, it is preferable to use carbon black having a nitrogen adsorption specific surface area of 30 to 130 m ³ / g, such as ISAF, HAF and FEF. The amount of carbon black added is not particularly limited, but usually 10
It is 10 to 150 parts by weight per 0 parts by weight, and about 10 to 80 parts by weight per 100 parts by weight of rubber is preferable for a styrene-butadiene copolymer rubber material.

In the present invention, various other compounding agents commonly used in the rubber industry can also be used according to the purpose.
Usually, various addition accelerators such as thiazoles, thiurams, dithio acids, guanidines, phthalic anhydride, scorch retarders such as N- (cyclohexylthio) phthalimide, other sulfur, fillers, stearic acid, peptizers, zinc Flower, process oil, processing aid, anti-aging agent,
Antiozonants, waxes, etc. are used. The types and amounts of these compounding agents can be selected as necessary and are not particularly limited in the present invention.

Generally, when compounding agents are mixed with natural rubber or synthetic rubber,
The compounding is basically done in two steps. That is, carbon black and other fillers, process oil, stearic acid, etc. are added in the first step at a relatively high temperature of rubber temperature of 120 to 220 ° C., and the vulcanization accelerator and vulcanizing agent are added at a rubber temperature of 40 to 40 ° C. It is added in the second step at a relatively low temperature of about 120 ° C.

The dinitrodiamines of the general formula [I] and 2,3,5,6-tetrachloro-1,4-benzoquinone according to the present invention can be blended in any step, and the blending timing of each is not particularly limited. However, the dinitrodiamines are preferably added in the first step in which carbon black or the like is blended, and the blending temperature at that time is higher at 140 to 200 ° C. because the effect of improving the rubber properties is higher at higher temperatures. preferable.

The rubber composition of the present invention is preferably used, for example, as various members of a tire, particularly a tread portion or a vibration-proof 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, the term "part" means "unless otherwise specified".
Parts by weight.

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-diaminobutane C: N, N'-bis (2-methyl-2-nitropropyl)-
1,12-Diaminododecane D: N, N'-bis (2-methyl-2-nitropropyl)-
1,4-diaminobenzene E: N, N'-bis (2-methyl-2-nitropropyl)-
4,4-Diaminodiphenylmethane Example 1 (formulation) Using a Toyo Seiki 250 ml Labo Plastomill as a Banbury mixer, at an oil bath temperature of 170 ° C., dinitrodiamines, carbon black, stearic acid and zinc white are added to the natural rubber based on the above compounding recipe, and 60 rpm
The mixture was kneaded for 5 minutes at the mixer rotation speed of. The rubber temperature at this time was 150 to 160 ° C.

The formulation was then transferred to an open mill and at a temperature of 60-70 ° C, 2,3,5,6-tetrachloro-
1,4-Benzoquinone, N- (cyclohexylthio) phthalimide, a deterioration inhibitor, a vulcanization accelerator and sulfur were added and kneaded.

Further, it was vulcanized at 145 ° C. for 25 minutes by a vulcanizing press and then subjected to various tests. However, the following Mooney scorch test was carried out using the compound before vulcanization. The test results are summarized in Table 1.

 The various test methods are as follows.

(1) Mooney scorch property In accordance with JIS K-6300, the time until the rubber compound before vulcanization increased by 5 points from the minimum value at 125 ° C was defined as the scorch time.

(2) Resilience The resilience 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, under a load of 35 lbs, a stroke of 6.35 mm, a frequency of 1800 rpm, and a chamber temperature of 40 ° C,
The exothermic temperature after 0 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 factor) It 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.
The smaller the value, the smaller the rolling resistance.

(5) Dynamic Magnification Measured with a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho at a temperature of 25 ° C and a vibration frequency of 100 Hz.

(6) Tensile stress (M ₃₀₀ ) Measured with a dumbbell-shaped test piece according to JIS K-6301.

(7) Blooming The vulcanized rubber sheet is placed in an atmosphere with a temperature of 25 ° C and a humidity of 50%.
After standing for a week, the surface of the vulcanized rubber was observed, and those in which no bloom was generated were indicated by ◯, and those in which bloom was indicated by x.

Example 2 (formulation combination) An experiment similar to that of Example 1 was conducted based on the above-mentioned compounding recipe in which the raw material rubber was a blend system of natural rubber and butadiene rubber. The vulcanization condition was 155 ° C. for 30 minutes. The results are summarized in Table-2.

Example 3 (formulation combination) Using Toyo Seiki's 250 ml Labo Plastomill as a Banbury mixer, at an oil bath temperature of 170 ° C, dinitrodiamines, carbon black, stearic acid, process oil and zinc white are added to the styrene-butadiene copolymer rubber based on the above compounding recipe. Then, the mixture was kneaded at a mixer rotation speed of 60 rpm for 5 minutes. The rubber temperature at this time is 150-160 ℃
Met.

The formulation was then transferred to an open mill and at a temperature of 60-70 ° C, 2,3,5,6-tetrachloro-
1,4-benzoquinone, an antioxidant, a vulcanization accelerator and ions were added and kneaded.

Further, it was vulcanized at 170 ° C. for 25 minutes by a vulcanizing press and then subjected to various tests. However, the following Mooney scorch test was carried out using the compound before vulcanization. The test results are summarized in Table-3.

 The various test methods are as follows.

(1) Mooney scorch property According to JIS K-6300, the time required for the rubber compound before vulcanization to rise by 5 points from the minimum value at 135 ° C was defined as the scorch time.

(2) Resilience The resilience 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, under a load of 35 lbs, a stroke of 6.35 mm, a frequency of 1800 rpm, and a chamber temperature of 40 ° C,
The exothermic temperature after 0 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) It was measured using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho under the conditions of static load 100 g, frequency 10 Hz, and temperature 60 ° C.
The smaller the value, the smaller the rolling resistance.

(5) Tensile stress (M ₃₀₀ ) Based on JIS K-6301, measured with a dumbbell-shaped test piece.

Example 4 (formulation) The same experiment as in Example 3 was conducted based on the above compounding recipe in which the raw material rubber was a blend system of styrene-butadiene copolymer rubber and natural rubber or butadiene rubber. The vulcanization conditions were 155 ° C. and 50 minutes. The results are summarized in Table-4.

<Effects of the Invention> According to the present invention, a rubber composition having stable scorch characteristics and excellent dynamic characteristics can be obtained. That is, the rubber composition of the present invention has a stable scorch property,
Moreover, resilience, heat resistance, tan δ at 60 ° C and dynamic magnification are maintained at good levels. Therefore, when such a rubber composition is applied to a tire member, for example, a tread portion of a tire, the fuel economy of the vehicle and the durability of the tire are improved, and the improvement of economic efficiency due to the extension of the product life is expected. It Further, when the rubber composition of the present invention is applied to a vibration-proof rubber, vibration and noise are reduced, and for example, in a vehicle equipped with such a vibration-proof rubber, improvement in riding comfort is expected.

Claims (7)

(57) [Claims] 1. A rubber composition containing carbon black, which is a raw rubber made of natural rubber and / or synthetic rubber.
For 100 parts by weight, the general formula [I] (In the formula, X is a divalent chain aliphatic group, a cycloaliphatic group or an aromatic group, which 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.) 0.1 to 10 parts by weight of dinitrodiamine, and
A rubber composition comprising 0.1 to 3 parts by weight of 2,3,5,6-tetrachloro-1,4-benzoquinone. 2. The composition according to claim 1, wherein the raw rubber is a natural rubber alone or a blended system with a synthetic rubber mainly composed of natural rubber. 3. The composition according to claim 1, wherein the raw rubber is a styrene-butadiene copolymer rubber alone or a blend system with a natural rubber or a butadiene rubber containing styrene-butadiene copolymer rubber as a main component. 4. The composition according to claim 1, wherein X in the general formula [I] is a chain aliphatic group having 4 to 12 carbon atoms. 5. A tire using the composition according to any one of claims 1 to 4. 6. The composition according to claim 5, wherein the composition is used in a tread portion.
Tires listed. 7. An anti-vibration rubber using the composition according to claim 1, 2 or 4.