JP2995866B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition having excellent strength characteristics and grip performance, and a method for increasing the loss factor of rubber without impairing mechanical strength.

[0002]

2. Description of the Related Art In recent years, with the advancement of high-performance automobiles, pavement of roads, and the development of a highway network, there has been an increasing demand for improvement in tire grip performance, which is closely related to automobile acceleration performance and braking performance. I have. It is known that in order to obtain high grip performance, energy loss due to friction between the tread portion of the tire and the road surface should be increased, and in response to this, the loss coefficient during deformation (tan δ )
A tread rubber material having a large size is required.

Conventionally, techniques for increasing tan δ during deformation include a method of using a styrene / butadiene copolymer rubber having a high styrene content as a base, a method of adding a large amount of process oil, and a carbon black having high reinforcing properties. And the like have been proposed.

Further, Japanese Patent Application Laid-Open No. Sho 64-70539 discloses that grip properties are improved by compounding a p-phenylenediamine derivative such as N-methacryloyl-N'-phenyl-p-phenylenediamine with rubber. It is described.

[0005]

When a styrene-butadiene rubber having a high styrene content is used, although the grip performance is improved to some extent, it is not always sufficient. In addition, in the method of adding a large amount of process oil or highly reinforcing carbon black, although the grip performance is improved, the high addition increases the heat build-up of the rubber, and accordingly, the strength characteristics and wear resistance are reduced. There is a problem that the temperature is significantly reduced. On the other hand, JP-A-64-7
The method of blending a p-phenylenediamine derivative described in Japanese Patent No. 0539 raises the tan δ of rubber, but it has been revealed that such blending deteriorates the strength characteristics.

[0006] From such a background, the present inventors have proposed tan δ
As a result of intensive research to develop a compounding agent that can improve grip performance, especially when the temperature of the tire becomes high, and that does not impair the mechanical strength, Invented the invention.

[0007]

That is, the present invention relates to a method of preparing a natural rubber and / or synthetic rubber by adding a filler and a compound represented by the following general formula [I]:

[0008]

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Wherein R ₁ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms,
-9, an alkylcarbonyl group, a hydroxyl group, a carboxyl group, an amino group, a nitro group, a cyano group or a halogen atom, and R ₂ is an alkyl group having 1 to 8 carbon atoms). A rubber composition is provided.

[0010] The present invention also provides a method for increasing the loss coefficient of rubber by blending a filler and an ester compound represented by the above general formula [I] with natural rubber and / or synthetic rubber.

The ester compound represented by the above general formula [I] can be prepared by, for example, converting a corresponding p-phenylaminophenol compound into an inert solvent such as toluene or chloroform.
The compound can be produced by subjecting a saturated fatty acid chloride to a dehydrochlorination reaction in the presence of a basic compound such as triethylamine, pyridine and sodium hydroxide.

In the general formula [I], the alkyl portion of the alkyl group, alkoxy group and alkylcarbonyl group represented by R ₁ has 1 to 8 carbon atoms, and those having 3 or more carbon atoms are linear. Or may be branched. Of these, those with relatively low carbon numbers,
For example, methyl, ethyl, methoxy, ethoxy, acetyl and the like are preferable.

The amino group represented by R ₁ may be unsubstituted amino, monosubstituted amino or disubstituted amino. Examples of the group which may be substituted with an amino group include methyl, ethyl and the like. Therefore, the term "amino group" as used herein includes methylamino, ethylamino, dimethylamino, diethylamino and the like in addition to unsubstituted amino.

The halogen atom represented by R ₁ includes fluorine, chlorine, bromine, iodine and the like.

In the general formula [I], the alkyl group represented by R ₂ has 1 to 8 carbon atoms, and those having 3 or more carbon atoms may be linear or branched. . The alkyl group is preferably one having a relatively small number of carbon atoms, for example, methyl or ethyl.

In the present invention, among the compounds represented by the general formula [I], those in which R ₁ is a hydrogen atom and R ₂ is a methyl group are particularly preferably used.

Specific examples of the ester compound of the general formula [I] which can be used in the present invention include, but are not necessarily limited to, the following.

[0018]

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[0019]

The form in which the ester compound is added to the rubber may be each compound alone,
It may be a mixture of a plurality of compounds, or a mixture with a carrier such as clay that does not affect the physical properties of rubber. Such an alkyl ester compound can be added at any stage of producing a compounded rubber.

In compounding the rubber, the above-mentioned general formula [I]
Although the amount of the compound represented by is not limited, it is generally used in the range of about 0.1 to 20 parts by weight per 100 parts by weight of natural rubber and / or synthetic rubber.

As the filler used in the present invention, various fillers used in the rubber industry are applied, but carbon black is generally preferred. The type of carbon black is not particularly limited, and various carbon blacks conventionally used in the rubber industry can be used. Conventionally, SAF black and ISA have been used to improve tire grip performance.
F black, HAF black etc., nitrogen adsorption specific surface area 8
High reinforcing carbon black of 0 to 250 m ² / g is used, and it is preferable to use such high reinforcing carbon black in the present invention. Although the amount of the filler is not particularly limited, it is generally used in the range of about 20 to 200 parts by weight based on 100 parts by weight of rubber.

The types of rubber that can be used in the present invention include natural rubber, polyisoprene rubber (IR),
Various types of styrene / butadiene copolymer rubber (SBR), polybutadiene rubber (BR), acrylonitrile / butadiene copolymer rubber (NBR), isoprene / isobutylene copolymer rubber (IIR), ethylene / propylene / diene copolymer rubber (EPDM) Examples include synthetic rubber, blends of natural rubber and synthetic rubber, and blends of synthetic rubber such as SBR and IR, SBR and BR.

In recent years, SBR having a particularly high styrene content has been preferably used in recent years in order to improve the grip properties of the tire. In the present invention, such an SBR having a high styrene content can be used. The present invention
It is also effective for SBR with a styrene content of 20 to 50% by weight, and such SBR is one of the preferred rubbers. The type of SBR may be a solution polymerization type or an emulsion polymerization type.

In compounding the tire tread rubber material,
Conventionally, a technique of blending a process oil has been often used to enhance the grip performance of a tire. However, the process oil can be used in combination in the present invention, and is preferable. The amount of the process oil is not particularly limited, but is generally 200 parts by weight or less per 100 parts by weight of rubber, and is preferably selected from the range of 5 to 200 parts by weight. The type of process oil is not limited in the present invention, and various process oils conventionally used in the rubber industry can be used.

Further, in the present invention, various rubber chemicals such as an antioxidant, a vulcanizing agent, a vulcanization accelerator, a retarder, a peptizing agent and a softening agent which are usually used in the rubber industry are used in the same manner as in the prior art. It goes without saying that they may be used in combination.

[0027]

Next, the present invention will be described in more detail with reference to examples in which the compound represented by the above general formula [I] is compounded into rubber to evaluate physical properties. However, the present invention is limited by these examples. Not something. In the following examples,% and parts represent% by weight and parts by weight, respectively, unless otherwise specified.

The ester compounds used in the examples and the p-phenylenediamine derivatives used in the comparative examples are as follows, and are indicated by the respective symbols.

[0029]

Example [Blending Formula] Styrene-butadiene copolymer rubber Table 1 listed (styrene content 35%, aromatic oil 37.5 parts per 100 parts rubber) Butadiene rubber (BR-01) Table-1 Description Natural rubber described in Table-1 ISAF carbon black described in Table-1 Stearic acid 3 parts Zinc white 5 parts Aromatic process oil described in Table-1 Vulcanization accelerator 1 part (N-cyclohexyl-2-benzothiazolesulfenamide) Sulfur 2 parts Compound described in Table-1

A Banbury mixer manufactured by Toyo Seiki 25
Oil bath temperature 170 using 0 ml Labo Plastmill ^R
At 0 ° C., the rubber is charged with the compound of the present invention or a p-phenylenediamine derivative for comparison, carbon black, stearic acid, process oil, and zinc white based on the above formulation, and the mixer is rotated at 50 rpm. Kneaded by number for 5 minutes. The rubber temperature at this time is 160 to 17
It was 0 ° C.

Next, this rubber compound was transferred to an oven mill, and at 40 to 50 ° C., the vulcanization accelerator and the sulfur shown in the above compounding recipe were added and kneaded.

Further, after vulcanizing with a vulcanizing press to form a specific shape, it was subjected to measurement of tan δ. The tan δ was measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho at a temperature of −50 to 100 ° C. under a condition of a frequency of 10 Hz.

As a mechanical strength test, a vulcanized rubber test piece (JIS-K-630) manufactured from the rubber composition was used.
1 using a dumbbell No. 3) at room temperature with a tensile stress (M
100 and M300) were measured.

Of the results obtained, tan at 80 ° C.
Table 1 shows δ, M100 and M300 at room temperature. In the table, a blank column of M300 means that measurement was impossible.

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

According to the present invention, by blending a specific ester compound, tan δ in a high temperature region of 60 ° C. or more corresponding to the grip force when the tire is heated to a high temperature.
Can be effectively improved, and the strength characteristics are hardly reduced. Therefore, when the rubber composition according to the present invention is applied particularly to a tread portion of a tire, a tire having excellent grip performance closely related to acceleration performance and braking performance of an automobile can be obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideo Nagasaki 3-98, Kasuganaka, Konohana-ku, Osaka-shi, Osaka Inside Sumitomo Chemical Co., Ltd. (72) Inventor Shinichi Yachigo Osaka-shi, Osaka 3-1-98 Kasuganaka, Konohana-ku Sumitomo Chemical Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) C08L 7/00-21/02 C08K 5/18 CA (STN) REGISTRY (STN)

Claims (5)

(57) [Claims] [Claim 1] under following general formula: 1] (Wherein, R ₁ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms,
An alkoxy group having 1 to 8 carbon atoms, an alkylcarbonyl group having 2 to 9 carbon atoms, a hydroxyl group, a carboxyl group, an amino group,
A nitro group, a cyano group or a halogen atom, and R ₂ is an alkyl group having 1 to 8 carbon atoms) . 2. In the above formula, R ₁ is a hydrogen atom, R ₂
Is a methyl group, and the loss coefficient of the rubber is increased.
Agent . 3. A loss factor of a natural rubber and / or a synthetic rubber, a filler and a rubber according to claim 1 or 2.
Rubber composition characterized by containing an enhancer
Stuff. (4) Fill natural rubber and / or synthetic rubber
Loss factor of the rubber according to any one of claims 1 to 2
Increasing the loss factor of rubber characterized by compounding
How to make it big. (5) A rubber composition produced from the rubber composition according to claim 3.
tire.