JP2001049033A - Rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition, which has good productivity and is suited as a tread rubber having a high modulus of elasticity, or the like, by compounding natural rubber and/or synthetic diene rubber, with a specific type bismaleimide compound and a polyaniline. SOLUTION: This rubber composition comprises a rubber component consisting of at least one rubber selected from natural rubber and synthetic diene rubber, at least one bismaleimide compound of formula I and at least one polyaniline of formula II. In formula I, R represents a 6-18C aromatic group or a 7-24C alkylaromatic group; and (x) and (y) are each independently and integer of 0 to 3. In formula II, R1, R2, R3, R4 and R5 independently represent H or NH2 provided that at least one of R1 to R5 is NH2; (n) is an integer of 2 or larger; and R6 represents an n-valent hydrocarbon residue, or O, S or SO2. The compounding rations are preferably such that the bismaleimide compound is used in an amount of 0.1 to 30 pts.wt. per 100 pts.wt. of the rubber component, and the polyaniline is used in an amount of 10 to 200 wt.% based on the bismaleimide compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition and a pneumatic tire, and more particularly to a technique for obtaining a rubber composition and a pneumatic tire having good workability and a high elastic modulus.

[0002]

2. Description of the Related Art In recent years, with the increase in horsepower and speed of automobiles, tire performance has been required to have higher steering stability and higher grip performance than ever before. on the other hand,
Bismaleimide has been studied in the rubber industry as a crosslinking agent, but JP-A-63-99251 discloses that styrene
It has been reported that by blending a bismaleimide compound with a butadiene copolymer rubber (SBR), both heat resistance and high mobility can be achieved.

[0003]

Recently, the present inventors have found that, in particular, when bismaleimide is added to a rubber containing 50% by weight or more of SBR, not only the heat resistance is improved, but also the dynamic storage modulus ( E ′) was increased, and it was found that when a rubber composition using bismaleimide was used for a tread, steering stability was improved. However, SB as described above
When a large amount of bismaleimide is added to the R-containing rubber, the vulcanization reaction is inhibited by the bismaleimide, and it takes a long time for vulcanization. Is larger)
In order to vulcanize rubber products without leaving air bubbles, vulcanization for a longer period of time is required, and productivity is greatly reduced, which is not practical. To solve this problem, it is naturally conceivable to use an accelerator for accelerating the onset of vulcanization, a so-called super accelerator, for example, guanidines, dithiocarbamates, and xanthates. Although the rise time can be shortened and the scorch time of the unvulcanized rubber can be shortened, the blow point cannot be greatly improved. Therefore, the present inventors have investigated the cause of the vulcanization reaction inhibition by bismaleimide, and as the cause, in particular,
In the SBR compound system, it was found that the reaction between the vulcanization accelerator and the bismaleimide occurred earlier than the vulcanization reaction, and as a result, vulcanization was inhibited. This is particularly noticeable when thiazole and thiuram vulcanization accelerators are used.
Further, by the reaction of bismaleimide and vulcanization accelerator,
Part of the bismaleimide is decomposed and gasified, so that a larger amount of gas is generated in the rubber than usual, and it has also been found that the blow point worsens. Then, an object of the present invention is to solve the above-mentioned inconvenience, to further improve the merit of high elasticity by bismaleimide, and to provide a technique capable of avoiding the disadvantage of productivity due to vulcanization delay.

[0004]

As described above, it has been found that the decrease in productivity due to the use of bismaleimide is due to the reaction between bismaleimide and the vulcanization accelerator. As a result of examining a compound that achieves the improvement of tire performance by increasing the dynamic storage modulus, which is the original object, it was found that the object can be achieved by blending a specific bismaleimide and polyaniline, and the present invention was completed. Was.

The present invention has the following configuration. (1) The rubber composition of the present invention comprises a rubber component comprising at least one rubber selected from the group consisting of a natural rubber and a synthetic diene rubber, and at least one bismaleimide represented by the above general formula [Formula 1], And at least one kind of polyaniline represented by the general formula [Formula 2]. The bismaleimide is a rubber component 1
It is preferable that the polyaniline is blended at a ratio of 0.1 to 30 parts by weight, and more preferably the polyaniline is blended at a ratio of 10 to 200% by weight of the bismaleimide. Also, bismaleimide is N, N '-(4,
4′-diphenylmethane) bismaleimide, and the polyaniline is bis (3-aminophenyl) sulfone, 4,4 ′-(m-phenylenediisopropylidene) dianiline, or a compound represented by the aforementioned general formula [Formula 3]. It is more preferable that the aromatic polyaniline be used. further,
More preferably, the rubber composition further contains at least one of a thiazole vulcanization accelerator and a thiuram vulcanization accelerator, and 50% by weight or more of the rubber component is a styrene / butadiene copolymer rubber. (2) A pneumatic tire according to the present invention is characterized in that the above rubber composition is applied as a rubber member. Preferably, the rubber member is a tread.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Bismaleimides that can be suitably used in the present invention include:
N, N'-1,2-phenylenedimaleimide, N, N '
-1,3-phenylenedimaleimide, N, N'-1,4
-Phenylenedimaleimide, N, N '-(4,4'-diphenylmethane) bismaleimide, 2,2-bis [4-
(4-maleimidophenoxy) phenyl] propane, bis (3-ethyl-5-methyl-4-maleimidophenyl] methane, and the like.
More than one species can be included. In addition, with respect to the bismaleimide represented by Chemical Formula 1, when x or y is 4 or more, the molecular weight becomes large, and the desired effect of increasing the dynamic storage modulus cannot be obtained for the compounding amount, which is inconvenient. It is. Examples of the polyaniline include bisaniline and aromatic polyaniline. Examples of the bisaniline include p-phenylenediamine, m-phenylenediamine, bis (4
-Aminophenyl) methane, bis (4-aminophenyl) ether, bis (3-aminophenyl) sulfone,
Bis (4-aminophenyl) sulfone, bis (4-aminophenyl) sulfide, 4,4 ′-(m-phenylenediisopropylidene) dianiline and aromatic polyaniline are represented by the above general formula [Formula 3]. Aromatic polyaniline and the like can be exemplified, and one or more of these can be contained in the rubber composition. It should be noted that, for the polyaniline represented by Chemical Formula 2, if n is 0 or 1, the elastic modulus is not sufficiently improved, which is inconvenient. Further, the carbon number of R ₆ is not particularly limited. The possible range of 1 of the aromatic polyaniline represented by the chemical formula 3 is an integer of 0 or more, preferably an integer of 0 to 80. In the present invention, the amount of bismaleimide is based on 100 parts by weight of the rubber component.
It is preferred that the amount be 0.1 to 30 parts by weight.
If the amount is less than 1 part by weight, the effect of the compounding may not be sufficiently obtained. From the same viewpoint, preferably 0.5 to
5.0 parts by weight. Further, the blending amount of polyaniline is preferably 10 to 200% by weight of bismaleimide. If the amount is less than 10% by weight, a synergistic effect due to the combination with bismaleimide cannot be obtained, and
If the ratio exceeds, the vulcanization is accelerated and the rubber is easily burnt. From the same viewpoint, preferably 20 to 100% by weight
It is.

[0007] The vulcanization accelerator that can be used in the present invention includes:
Although not particularly limited, preferably MBT (2
-Mercaptobenzothiazole), DM (dibenzothiazyldisulfide), CBS (N-cyclohexyl-
Benzothiazole vulcanization accelerators such as 2-benzothiazylsulfenamide), guanidine vulcanization accelerators such as DPG (diphenylguanidine), and thiuram vulcanization such as tetraoctylthiuram disulfide and tetrabenzylthiuram disulfide. Accelerators, vulcanization accelerators such as zinc dialkyldithiophosphate can be exemplified, the amount of use thereof,
The amount is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 3 parts by weight, based on 100 parts by weight of the rubber component. The present invention is extremely effective for rubber compositions and tires containing a thiazole vulcanization accelerator and / or a thiuram vulcanization accelerator.

In the present invention, natural rubber and synthetic diene rubber can be used.
1,4-polyisoprene, styrene-butadiene copolymer, low cis-1,4-polybutadiene, high cis-1,4
-Polybutadiene, ethylene-propylene-diene copolymer, chloroprene, halogenated butyl rubber, acrylonitrile-butadiene rubber and the like can be exemplified, and natural rubber and synthetic diene rubber can be used alone or as a blend. Preferred rubbers are natural rubber, cis-1,
4-polyisoprene, styrene-butadiene copolymer, and polybutadiene. It is preferable that the rubber component contains 50% by weight or more of a styrene / butadiene copolymer rubber because the improvement effect by the combination of bismaleimide and polyaniline, which is the object of the present invention, becomes clear.

In the present invention, as the reinforcing filler, at least one of carbon black, silica, calcium carbonate, titanium oxide and the like can be used, and carbon black and silica are preferred. The amount of the reinforcing filler is 2 parts by weight based on 100 parts by weight of the rubber component.
0 to 150 parts by weight is preferred. This is because if it is less than 20 parts by weight, the vulcanizate has insufficient breaking characteristics and wear resistance, and if it exceeds 150 parts by weight, it is not preferable in terms of workability and the like. From the same viewpoint, 25 to 80 parts by weight is more preferable. Examples of the carbon black used as the reinforcing filler include HAF, ISAF, SAF and the like. When carbon black and silica are used in combination, the mixing ratio can be arbitrarily changed according to the mixing purpose.

In the rubber composition of the present invention, in addition to the above rubber component, reinforcing filler, bismaleimide and polyaniline, if necessary, a silane coupling agent, a vulcanizing agent ordinarily used in the rubber industry. , A vulcanization accelerator, a vulcanization accelerator, an antioxidant, an antiozonant, an antioxidant, a process oil, zinc white (ZnO), stearic acid, and the like. As the vulcanizing agent that can be used in the present invention,
For example, sulfur and the like can be mentioned, and the amount of use thereof is 0.1 to 10 parts by weight, preferably 0.5 to 5.0 parts by weight, based on 100 parts by weight of the rubber component. 0.1
If the amount is less than 10 parts by weight, the fracture properties and abrasion resistance of the vulcanized rubber will be reduced. If the amount exceeds 10 parts by weight, the rubber elasticity tends to be lost.

The process oil that can be used in the present invention includes:
For example, paraffin-based, naphthenic-based, aromatic-based and the like can be mentioned, and aromatic-based is used in applications where emphasis is placed on fracture characteristics and wear resistance, and naphthene-based is used in applications where low heat generation and low-temperature characteristics are emphasized. System or paraffin system is preferably used. The amount of the rubber component is 10
The amount is preferably not more than 100 parts by weight with respect to 0 parts by weight, because if it exceeds 100 parts by weight, the fracture characteristics of the vulcanized rubber tend to decrease.

The rubber composition of the present invention is obtained by kneading the above rubber component, bismaleimide, polyaniline, reinforcing filler and the like using a kneading machine such as a roll or an internal mixer. It can be suitably used for tires such as tire treads, undertreads, carcass, sidewalls, bead portions, and other tires, as well as anti-vibration rubbers, belts, hoses, and other industrial products.

[0013]

The present invention will be described more specifically below. Table 1
And each of the components shown in Table 2 or Table 3
Using a Labo Plastomill and a 3 inch roll, kneading and compounding were performed to obtain an unvulcanized rubber composition (Examples 1 to 10 and Comparative Examples 1 to 7). For each rubber composition, a curast test and a blow point test were conducted by the following methods (1) and (2), and a tensile test and a dynamic viscoelasticity test after vulcanization of these compounded rubbers were performed according to the following (3),
It measured by the method of (4). The results are shown in Tables 2 and 3. (1) Curast test Measured at 145 ° C. using MDR2000 manufactured by Flexis, USA. M _H, M _L is the maximum value of each torque is a minimum value, T _10, T ₉₀ 10% increase overall torque due to vulcanization reaction, representing the time to reach 90%. Each data is represented by an index with Comparative Example 1 or 6 being 100. (2) Blow point test Using a blow point measuring machine manufactured by Toyo Seiki Co., Ltd.
The measurement was performed at 170 ° C. under an activation energy of 20 kcal. Each data is 100 for Comparative Example 1 or 6.
As an exponent. The larger this index is, the larger the blow point value is, which means that a longer vulcanization time is required and the productivity is deteriorated. (3) Tensile test 145 ° C. (1) pressurized between 1.5 times corresponding to vulcanization of T ₉₀ obtained in after curing, subjected to tensile tests based on JISK6301-1975 (3 test piece No. use), elongation at break (EB),
The breaking strength (TB) and the elastic modulus at 300% elongation (M ₃₀₀ ) were measured. Similarly, each data is represented by an index with Comparative Example 1 or 6 being 100. (4) Dynamic viscoelasticity test Using a spectrometer (dynamic viscoelasticity measuring tester) manufactured by Toyo Seiki Co., Ltd., frequency 52 Hz, measurement temperature 30 ° C,
E ′ (dynamic storage modulus), E ″ (dynamic loss modulus) and tan δ (loss coefficient) were measured at a strain of 1%. Similarly, each data was expressed as an index with Comparative Example 1 or 6 as 100, respectively. Represent.

Furthermore, using the rubber compositions of Examples 2, 4, 8, 9, and 10 and Comparative Examples 1, 3, 6, and 7 as tread rubbers, an air human having a tread (one-layer structure) of 185 / 70R14 size. Tires were prototyped, and the performance of each tire was evaluated for maneuverability in actual vehicle running.

(5) Drivability On a test course on a dry asphalt road surface, a real vehicle was run using an FF4 door sedan fitted with each new tire, and the driving performance, braking performance, steering wheel responsiveness, and controllability at the time of steering were improved. The test driver comprehensively evaluated the tires of Comparative Example 1 or 6 as control tires. +1: Protest driver feels slightly better than control tires. +2: Protest driver feels better than control tires. +3: Skilled driver compared to control tires. +4: When the driver feels good enough to understand the general driver compared to the control tire

[0016]

[Table 1]

Noxeller D: DPG bismaleimide: N, N '-(4,4'-diphenylmethane) bismaleimide (BM manufactured by Mitsui Chemicals, Inc.)
IS) Polyaniline A: aromatic polyamine (ANILIX manufactured by Mitsui Chemicals, Inc.) Polyaniline B: 4,4 ′-(m-phenylenediisopropylidene) dianiline Polyaniline C: 3,3′-diaminodiphenylsulfone

[0018]

[Table 2]

[0019]

[Table 3]

[0020] From the above results, but Comparative Example 2-4 is an example of using bismaleimide alone, E 'is contrary to increase more than 20%, T ₉₀ is greatly extended, and, significantly blow point To increase. Comparative Example 5 is an example in which polyaniline A was used alone, but the _T90 was shorter, but the blow point was comparable to the control. Although E 'slightly increases, tan δ greatly increases, which is not preferable. On the other hand, in Examples 1 to 7, by using bismaleimide and polyaniline in combination, the delay in vulcanization is improved and the blow point is greatly improved. Also,
E ′ greatly increases, and tan δ tends to decrease as compared with the case of using bismaleimide alone. Example 8
Even in the combination system of carbon black / silica of 10 to 10, by using bismaleimide and polyaniline together,
Similar synergistic effects were demonstrated.

[0021]

According to the present invention, it is possible to provide a rubber composition which is suitable for tread rubber and the like with high workability, high productivity and high elastic modulus. A pneumatic tire using such a rubber for a tread is excellent in maneuverability.

Claims (9)

[Claims] 1. A rubber component comprising at least one rubber selected from the group consisting of a natural rubber and a synthetic diene rubber, wherein at least one of a bismaleimide represented by the following general formula [Formula 1] and a general formula [ A rubber composition comprising at least one of the polyanilines represented by Chemical formula 2]. Embedded image (Wherein, R represents an aromatic group having 6 to 18 carbon atoms or an alkyl aromatic group having 7 to 24 carbon atoms;
Any integer of 3 is independently represented. ) (Wherein R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are H or NH
₂ each independently, at least one of R _{1 to} R ₅ is NH ₂ , n represents an integer of 2 or more, and R ₆ is an n-valent hydrocarbon residue, or —O—, —S -, -SO ₂
And, in the case of a hydrocarbon residue, any of saturated, unsaturated, aliphatic, aromatic, branched, and linear, and may be any of —O—, —S—, and —SO ₂ —. At least one of
It may contain species heteroatoms. ) 2. The rubber composition according to claim 1, wherein the bismaleimide is blended in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the rubber component. 3. The method according to claim 1, wherein the polyaniline is a bismaleimide.
3. The rubber composition according to claim 2, wherein the rubber composition is blended at a ratio of about 200% by weight. 4. A method according to claim 1, wherein the bismaleimide is N, N ′-(4,
4. The rubber composition according to claim 1, wherein the rubber composition is 4'-diphenylmethane) bismaleimide. 5. The polyaniline is bis (3-aminophenyl) sulfone, 4,4 ′-(m-phenylenediisopropylidene) dianiline, or the following general formula:
4. The rubber composition according to claim 1, which is an aromatic polyaniline represented by the formula: Embedded image (In the formula, 1 represents an integer of 0 or more.) 6. The rubber composition according to claim 1, further comprising at least one of a thiazole vulcanization accelerator and a thiuram vulcanization accelerator. 7. The rubber composition according to claim 1, wherein 50% by weight or more of the rubber component is a styrene / butadiene copolymer rubber. 8. A pneumatic tire, wherein the rubber composition according to any one of claims 1 to 7 is applied as a rubber member. 9. The pneumatic tire according to claim 8, wherein the rubber member is a tread.