JP2002121326A - Rubber composition and tire using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber composition having high elastic modulus in high productivity and a tire using the composition. SOLUTION: This rubber composition comprises a rubber component having at least one of a natural rubber and a synthetic diene rubber, a specific bismaleimide, and a specific functionalized polyolefin. It is used for tire treads.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition and a tire, and more particularly to a rubber composition having good workability and a high elastic modulus, and a technique for obtaining a tire for a vehicle or an aircraft.

[0002]

2. Description of the Related Art In recent years, with higher horsepower and higher speed of automobiles and the like, 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]

SUMMARY OF THE INVENTION The inventor of the present invention has
When bismaleimide is blended with a rubber containing at least 50% by weight of BR, not only the heat resistance is increased, but also the dynamic storage modulus (E ') is increased, and when a rubber composition using bismaleimide is used for a tread, steering becomes difficult. We found that stability increased. However, when a large amount of bismaleimide is added to the SBR-containing rubber as described above, the vulcanization reaction is inhibited by the bismaleimide, and long-time vulcanization is required,
The productivity is disadvantageous in that it is greatly reduced and is not practical. Therefore, an object of the present invention is to provide a technique capable of improving the merit of high elasticity with a small amount of bismaleimide and avoiding the disadvantage of productivity due to vulcanization delay in order to solve the above-mentioned disadvantages.

[0004]

DISCLOSURE OF THE INVENTION As described above, a compound which suppresses the deterioration of productivity due to bismaleimide, greatly increases the dynamic storage elastic modulus which is the original purpose, and improves tire performance has been studied. As a result, they have found that the above object can be achieved by blending a specific bismaleimide and a functionalized polyolefin, and completed the present invention.

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 of functionalized polyolefins. The bismaleimide is based on 100 parts by weight of the rubber component.
It is preferable that it is blended in a ratio of 0.1 to 30 parts by weight, and it is more preferable that the functionalized polyolefin is blended in a ratio of 0.1 to 30 parts by weight. It is more preferable that the bismaleimide is N, N '-(4,4'-diphenylmethane) bismaleimide, and that the functionalized polyolefin is an acrylic acid-modified polyolefin and / or a citraconic anhydride-modified polyolefin. A maleic acid-modified polyolefin is more preferred because of its high synergistic effect with bismaleimide. Further, it is more preferable that the rubber composition further contains at least one of a thiazole-based vulcanization accelerator and a thiuram-based vulcanization accelerator, and 50% by weight or more of the rubber component is a styrene / butadiene copolymer rubber. . (2) The tire of 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. Further, the polyolefin constituting the functionalized polyolefin may be not only polyethylene, polypropylene and the like, but also a (co) polymer containing at least one of ethylene, propylene, 1-butene and 1-hexene. On the other hand, as the modifying group of the polyolefin, maleic anhydride, acrylic acid, citraconic anhydride, and maleic acid can be preferably exemplified, and among them, maleic anhydride is more preferable in that the high E 'of the present invention can be obtained. One or more such functionalized polyolefins can be included in the rubber composition. In the present invention, the amount of bismaleimide is 0.1 to 100 parts by weight of the rubber component.
The amount is preferably 30 parts by weight, but if the amount is less than 0.1 part by weight, the effect of the compounding may not be sufficiently obtained.
If the amount exceeds the weight part, the fracture properties tend to decrease. From the same viewpoint, the amount is preferably 0.5 to 5.0 parts by weight. Furthermore, the compounding amount of the functionalized polyolefin is
It is preferable that the amount is from 0.1 to 30 parts by weight based on 100 parts by weight of the rubber component.
If the amount exceeds 30 parts by weight, the workability of the unvulcanized rubber deteriorates. From the same viewpoint, it is preferably 0.5 to 10 parts by weight.

[0007] The vulcanization accelerator that can be used in the present invention includes:
Although not particularly limited, preferably MBT (2
-Mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CBS (N-cyclohexyl-2)
-Benzothiazole based vulcanization accelerators such as -benzothiazylsulfenamide), DPG (diphenylguanidine)
Guanidine-based vulcanization accelerators, such as tetraoctylthiuram disulfide, thiuram-based vulcanization accelerators such as tetrabenzylthiuram disulfide, and vulcanization accelerators such as zinc dialkyldithiophosphate can be exemplified. The amount is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 3 parts by weight, per 100 parts by weight. 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,
Polybutadiene. In the rubber component, styrene-
When the butadiene copolymer rubber is contained in an amount of 50% by weight or more, the improvement effect by the combination of the bismaleimide and the functionalized polyolefin, which is the object of the present invention, is preferable because it 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 rubber component, reinforcing filler, bismaleimide, functionalized polyolefin, and vulcanization accelerator, if necessary, silanes commonly used in the rubber industry may be used. Coupling agents, vulcanizing agents, other vulcanization accelerators, vulcanization accelerators, antioxidants, antiozonants, antioxidants, process oils, zinc oxide (ZnO),
Stearic acid and the like can be blended. Examples of the vulcanizing agent that can be used in the present invention include sulfur and the like, and the amount of these used is 0.1 to 10 parts by weight, preferably 0.5 part by weight, based on 100 parts by weight of the rubber component. ~ 5.
0 parts by weight. If the amount is less than 0.1 part by weight, the fracture characteristics and abrasion resistance of the vulcanized rubber decrease, and if it 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, paraffinic, naphthenic, and aromatic types can be mentioned. An aromatic type is used for applications that emphasize fracture characteristics and abrasion resistance, and a naphthene type is used for applications that emphasize low heat generation and low temperature characteristics. 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 rubber component, bismaleimide, functionalized polyolefin, reinforcing filler and the like using a kneading machine such as a roll or an internal mixer. After processing, it is vulcanized, and is suitable for use as a rubber material for tire treads, undertreads, carcass, sidewalls, beads, etc., as well as anti-vibration rubber, belts, hoses and other industrial products. it can.

As an example of the tire of the present invention, a pneumatic tire for a passenger car shown in FIG. 1 is shown. This is a tubeless structure, in which a carcass 2 (one ply) is arranged between a pair of beads 1 and 1 ′, and a crown portion 3 has two belt layers 4 and 4 ′ reinforced by a steel cord.
A belt reinforcing layer 6 covering the entire belt layer and a belt reinforcing layer 6 ′ covering both end portions of the belt layer are formed on the outer side and inside the tread 5. It goes without saying that the tire structure is not limited to this,
Further, the gas to be filled is not limited to air, but may be nitrogen or the like.

[0014]

The present invention will be described more specifically below. Table 1 and each of the components listed in Table 2, Table 3 or Table 4,
The mixture was kneaded and compounded using a 500 ml Labo Plastomill and a 3-inch roll to obtain an unvulcanized rubber composition (Examples 1 to 14 and Comparative Examples 1 to 19). For each rubber composition, a curast test is performed by the following method (1), and a tensile test and a dynamic viscoelastic test of these compounded rubbers after vulcanization are measured by the following methods (2) and (3). did. The results are shown in Tables 2, 3 and 4.

(1) Curast test Measured at 145 ° C. using MDR2000 manufactured by Flexis, USA. T ₉₀ denotes the time to reach 90% of the total increase in torque due to vulcanization reaction. Each data is shown in Comparative Examples 1 and 1.
0 or 15 is represented by an index with 100 as each.

[0016] (2) Tensile Test 145 ° C. (1) obtained in T ₉₀ of 1.5 corresponding to a vulcanization time in vulcanized, subjected to tensile tests based on JISK6301-1975 (3 test piece No. used) , Elongation at break (EB),
The breaking strength (TB) and the elastic modulus at 300% elongation (M ₃₀₀ ) were measured. Similarly, each data is Comparative Example 1, 10 or 1
5 is represented by an index with 100 being each. (3) 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) at 1% strain, tan δ (loss coefficient)
Was measured. Similarly, each data is represented by an index with Comparative Example 1, 10 or 15 as 100, respectively.

Examples 1, 2, 4, 7, 8, 9,
11, 12, 13, Comparative Examples 1, 3, 10, 12, 15,
Using the rubber composition of No. 17 as a tread rubber, 185
A / 70R14 size tread (single-layer structure) air pneumatic tire was prototyped, and the performance of each tire was evaluated for maneuverability in actual vehicle running.

(4) Drivability On a test course on a dry asphalt road surface, a real vehicle was run using an FF4 door sedan equipped with each new tire, and the driving performance, braking performance, steering wheel response, and controllability during driving were improved. The test driver comprehensively evaluated the tires of Comparative Examples 1, 10 and 15 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

[0019]

[Table 1]

Noxeller D: DPG bismaleimide: N, N '-(4,4'-diphenylmethane) bismaleimide (BMI-S manufactured by Mitsui Chemicals, Inc.) Unmodified polyolefin: HDPE HIZEX 6200B (manufactured by Mitsui Chemicals, Inc.) ) Maleic anhydride-modified polyolefin A: HDPE Admer
HB030 (manufactured by Mitsui Chemicals, Inc.) Maleic anhydride-modified polyolefin B: LLDPE Admer
NE065 (manufactured by Mitsui Chemicals, Inc.) Maleic anhydride-modified polyolefin C: PP ADMER QF
500 (Mitsui Chemicals)

[0021]

[Table 2]

[0022]

[Table 3]

[0093]

[Table 4]

From the above results, Comparative Examples 2 to 4 are examples in which bismaleimide is used alone. When a large amount of bismaleimide is added, E ′ increases by 20% or more, while T ′ increases.
₉₀ is greatly extended. Comparative Example 5 is an example in which maleic anhydride-modified polyolefin A was used alone.
Although E ′ increases, its use alone is not preferable because it has little effect. In contrast, in Examples 1 to 6, the delay in vulcanization is improved by using a bismaleimide and a functionalized polyolefin in combination. Also, E 'rises greatly and tan
δ tends to be lower than in the case of using bismaleimide alone. Furthermore, the same synergistic effect was also exhibited by using the bismaleimide and the functionalized polyolefin in combination in the carbon black / silica combination compounding system of Examples 7-14.

[0095]

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 tire using such a rubber for a tread is excellent in maneuverability.

[Brief description of the drawings]

FIG. 1 shows an example of a tire structure of the present invention in a left half cross-sectional view.

[Explanation of symbols] 2 carcass, 5 treads

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/45 C08K 5/45 C08L 9/00 C08L 9/00 // (C08L 7/00 (C08L 7 / 00 23:26) 23:26) (C08L 9/00 (C08L 9/00 23:26) 23:26)

Claims (10)

[Claims] 1. 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 following general formula [Chemical Formula 1] and a functionalized polyolefin. A rubber composition characterized by comprising: 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. ) 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 rubber composition of claim 1, wherein the functionalized polyolefin is a rubber component.
The rubber composition according to claim 1 or 2, wherein the rubber composition is blended in an amount of 0.1 to 30 parts by weight based on 0 part 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 rubber composition according to claim 1, wherein the functionalized polyolefin is an acrylic acid-modified polyolefin and / or a citraconic anhydride-modified polyolefin. 6. The method according to claim 1, wherein the functionalized polyolefin is a maleic anhydride-modified polyolefin.
5. The rubber composition according to any one of the above-mentioned items. 7. The rubber composition according to claim 1, further comprising at least one of a thiazole vulcanization accelerator and a thiuram vulcanization accelerator. 8. The rubber composition according to claim 1, wherein 50% by weight or more of the rubber component is a styrene / butadiene copolymer rubber. 9. A tire, wherein the rubber composition according to any one of claims 1 to 8 is applied as a rubber member. 10. The tire according to claim 9, wherein the rubber member is a tread.