JP2000086818A - Rubber composition and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition that prevents a change in physical properties of an unvulcanized rubber with time and enhances storage stability by kneading a filler comprising a filler having a silanol group on the surface thereof and a coupling agent with a rubber raw material, and thereafter further kneading a thiophthalimide derivative, and then blending a vulcanizing agent and a vulcanizing accelerator thereinto. SOLUTION: Into 100 pts.wt. rubber raw material comprising a crosslinkable rubber, 30-100 pts.wt. filler containing 0.1-50 wt.%, preferably 0.3-30 wt.% filler having a silanol group on the surface and a silane coupling agent are formulated and kneaded. To the resultant kneaded product, 0.1-10 pts.wt., preferably 0.1-0.8 pts.wt. thiophthalimide derivative of the formula and optionally, 1-10 pts.wt., preferably 3-8 pts.wt. silica are added and kneaded, and thereafter a vulcanizing agent and a vulcanizing accelerator are compounded. In the formula, R is 1-22C aliphatic hydrocarbon, 3-22C alicyclic hydrocarbon or 6-22C aromatic hydrocarbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a raw material rubber containing fillers (carbon black, silica, a mixture thereof, a carbon black / silica composite, and an arbitrary mixture thereof).
And a method for producing a rubber composition containing a silane coupling agent, and more particularly to a method for producing a rubber composition in which the untempered rubber properties of a rubber composition containing such a filler and a silane coupling agent are suppressed over time. About.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for lower fuel consumption of tires. In order to meet such demands, improvements have been made in polymers and fillers incorporated in rubber compositions for tires. Among them, silica is blended as a filler (for example, blending of silica into solution-polymerized SBR is disclosed in JP-A-3-239737) or blending of a composite filler of silica and carbon black (such composite Fillers are described in, for example, JP-A-8-277347) and the like are proposed as particularly effective means. However, when silica or a silica / carbon black composite filler is blended, it is necessary to blend a silane coupling agent in order to chemically bond the rubber to silanol groups on the filler surface and exhibit a sufficient reinforcing effect. However, when a silane coupling agent is blended, due to the presence of the silane coupling agent,
There is a problem that the properties of the unvulcanized rubber change drastically with time, and the processability of the rubber composition decreases.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems of compounding a silane coupling agent, and provides a rubber composition containing a silane coupling agent. The present invention provides a method for producing a rubber composition capable of increasing storage stability, suppressing an increase in Mooney viscosity, and suppressing a reduction in scorch time by suppressing a change over time of unvulcanized material properties. The purpose is to:

[0004]

According to the present invention, in producing a rubber composition containing a filler and a silane coupling agent in a crosslinkable rubber, a filler containing a filler having a silanol group on the surface and a silane coupling agent are used. Before kneading the vulcanizing agent and the vulcanization accelerator,
The following formula:

[0005]

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(Wherein, R is an aliphatic hydrocarbon having 1 to 22 carbon atoms, an alicyclic hydrocarbon having 3 to 22 carbon atoms, or 6 to 22 carbon atoms)
Which is a process for kneading a thiophthalimide derivative represented by formula (22).

According to the present invention, in producing a rubber composition containing a filler and a silane coupling agent in a crosslinkable rubber, a filler containing a filler having a silanol group on the surface and a silane coupling agent are kneaded. Thereafter, there is provided a method for producing a rubber composition, which comprises mixing and kneading silica.

According to the present invention, in producing a rubber composition containing a filler and a silane coupling agent in a crosslinkable rubber, a filler containing a filler having a silanol group on the surface and a silane coupling agent are kneaded. Next, before compounding the vulcanizing agent and the vulcanization accelerator, the compound of the formula (I)
A method for producing a rubber composition comprising kneading a thiophthalimide derivative of the above, further kneading a filler containing a filler having a silanol group on the surface and a silane coupling agent, then compounding silica, and kneading is provided. You.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies in order to suppress the change with time of the unvulcanized properties of a rubber composition obtained by blending a silane coupling agent with a raw rubber, and as a result, the formula (I) By mixing and kneading the thiophthalimide derivative and / or silica in a specific order when compounding the rubber and the filler, the temporal change in the physical properties of the unvulcanized rubber composition containing the silane coupling agent is suppressed, It has been found that a rubber composition having excellent stability over time in the properties of unvulcanized rubber can be produced.

The raw rubber compounded as a main component in the rubber composition according to the present invention may be any rubber conventionally compounded generally in various rubber compositions, particularly a diene rubber such as natural rubber (NR), Diene rubbers such as polyisoprene rubber (IR), various styrene-butadiene copolymer rubbers (SBR), various polybutadiene rubbers (BR), acrylonitrile-butadiene copolymer rubber (NBR) and butyl rubber (IIR) can be used alone or optionally. Can be used as a blend.

In the rubber composition according to the present invention, silica, a silica / carbon black composite, an arbitrary mixture thereof, and a mixture of these and carbon black are used as the filler containing a filler having a silanol group on the surface of the raw rubber. And a silane coupling agent. The carbon black and silica used in the present invention are not particularly limited, and any carbon black and silica conventionally widely used for rubber can be used.

The silica / carbon black composite filler that can be used in the present invention is described in, for example, Japanese Patent No. 2788212, JP-A-10-25428, JP-A-10-30065, and JP-A-10-30066.
JP, JP-A-10-30067, JP-A-10-30067
As described in Japanese Patent No. 46047 and WO 96/37547, it can be produced by putting or bonding silica to the surface of carbon black, for example, by putting carbon black into an atmosphere that produces white carbon. It is also possible to disperse carbon black in water, e.g. to hydrolyze sodium silicate, for example, while adjusting the pH to 6 or higher, preferably 10 to 11 and maintaining the temperature at 70 ° C or higher, preferably 85 to 95 ° C. And depositing or depositing amorphous silica on the surface of the carbon black particles. The amount of silica attached to the silica surface-treated carbon black is not particularly limited, but generally 0.1 to 50% by weight is used, and more preferably 0.3 to 30% by weight.

The amount of the filler in the present invention is not particularly limited, but is preferably 30 to 100 parts by weight of rubber.
It is 100 parts by weight, more preferably 40 to 90 parts by weight. If the amount of the filler is too small, the desired reinforcing effect is, of course, not sufficient, while if it is too large, not only the hardness becomes too high, but also the abrasion resistance and the like are undesirably reduced.

The silane coupling agent blended in the rubber composition according to the present invention is not particularly limited, and any silane coupling agent conventionally blended together with a silica filler in a rubber composition is conventionally used. Can be used. Examples of such a silane coupling agent include vinyl trichlorosilane, vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tris (β-methoxyethoxy) silane, and β- (3,4 epoxycyclohexyl).
Ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyl Trimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltri Methoxysilane, N-β (aminoethyl)
γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxy Examples thereof include silane and bis- (3- [triethoxysilyl] -propyl] -tetrasulfan.

According to the present invention, the thiophthalimide derivative of the formula (I) and / or silica is blended in order to suppress the above-mentioned change with time of the unvulcanized rubber.
The thiophthalimide derivative of the formula (I) is a known compound and is commercially available. Specifically, for example, N
-(Cyclohexylthio) phthalimide and the like. Silica which is generally used for rubber compounding can be used. According to the present invention, this compound and / or silica must be compounded after compounding a rubber with a filler and a silane coupling agent and kneading the compound before mixing the vulcanizing agent and the vulcanization accelerator. No. The thiophthalimide derivative and / or
Alternatively, when silica is blended with the filler and the silane coupling agent in the raw rubber, a desired effect of stabilizing the properties of the unvulcanized rubber over time cannot be obtained. The amount of the thiophthalimide derivative is not particularly limited, but is preferably 0.1 to 1.0 part by weight, more preferably 0.1 to 0.8 part by weight, per 100 parts by weight of the raw rubber. If the amount is too small, the desired effect of stabilizing with time cannot be obtained, while if it is too large, the vulcanization rate is lowered, which is not preferable.

In the present invention, the amount of silica added afterwards is not particularly limited, but is preferably 1 to 10 parts by weight, more preferably 3 to 10 parts by weight, per 100 parts by weight of the raw rubber.
８8 parts by weight. If the amount is too small, the desired effect of stabilizing with time cannot be obtained. On the other hand, if the amount is too large, the amount of silica that does not react with the silane coupling agent increases and the mechanical properties deteriorate, which is not preferable. This silica is effective regardless of whether silica is already compounded or not, as a filler. In the former case, the compounding amount is the amount of post-added silica.

In the rubber composition according to the present invention, in addition to the above-mentioned essential components, various additives generally used for tires and other general rubbers such as various oils, anti-aging agents, plasticizers, etc. The compound can be kneaded and vulcanized by a general method into a composition, and can be used for vulcanization or crosslinking. The compounding amounts of these additives can be made conventional general compounding amounts as long as they do not contradict the object of the present invention.

As described above, the method of producing the rubber composition according to the present invention is based on the fact that the compounding order of the thiophthalimide derivative and / or post-added silica is determined after the step of kneading the filler and the silane coupling agent into the raw rubber. There is no particular difference from the conventional rubber composition except that the vulcanizing agent and the vulcanization accelerator are compounded before compounding. That is, first, the raw rubber, filler, silane coupling agent, and other necessary conventional components are compounded and kneaded in a closed mixer such as a Banbury mixer, a pressure kneader, or a twin-screw extruder, and then the thiophthalimide derivative An unvulcanized rubber composition can be obtained by compounding the and / or post-added silica with the above-mentioned closed mixer or kneading roll. The obtained unvulcanized rubber composition can be vulcanized and molded by a conventional method by adding a vulcanizing agent and a vulcanization accelerator according to a conventional method to obtain a rubber product.

[0019]

EXAMPLES Hereinafter, the present invention will be further described with reference to Examples, but it goes without saying that the scope of the present invention is not limited to these Examples.

Examples 1 to 3 and Comparative Examples 1 to 2 In the formulations (parts by weight) shown in Table I, the components described in the first blending step were mixed in a 1.8-liter closed mixer for 3 to 5 parts.
When the temperature reached 165 ± 5 ° C. for minutes, in Examples 1 to 3, the components described in the second blending step were blended, sufficiently kneaded, and released. In the third blending step, a vulcanization accelerator and sulfur were added to the obtained masterbatch and kneaded with an 8-inch open roll to obtain a rubber composition. The unvulcanized properties of the obtained rubber composition were measured one day after mixing and two weeks after mixing. The results are shown in Table I. Next, the composition was added to 15 ×
The target test piece (rubber sheet) was prepared by press vulcanization at 160 ° C. for 20 minutes in a 15 × 0.2 cm mold, and the vulcanization properties were evaluated. The results are shown in Table I.

[0021]

[Table 1]

The methods for measuring the unvulcanized and vulcanized properties shown in Table I are as follows. 1) Mooney viscosity Measured at 100 ° C. based on JIS K6300. 2) Mooney scorch test According to JIS K6300, the time required for the viscosity to rise by 5 Mooney units at a temperature of 125 ° C was measured. A smaller value is better. 3) tan δ (0 ° C., 60 ° C.) Using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho, measurement was performed under the conditions of an elongation deformation strain of 10 ± 2% and a frequency of 20 Hz. 4) Abrasion resistance A Lambourn abrasion tester (manufactured by Iwamoto Seisakusho Co., Ltd.) was used to measure abrasion loss under the conditions of 5 kg load, 25% slip ratio, 4 minutes of time, and room temperature. Exponential display. The larger the number, the better the wear resistance.

[0023]

As is clear from the results in Table I, in a system in which a carbon black / silica composite and a silane coupling agent are blended in a rubber blend containing equal amounts of emulsion-polymerized SBR and solution-polymerized SBR, a thiophthalimide derivative is used. In Comparative Example 2 initially blended, the Mooney viscosity increases with time, and the scorch time is shortened. On the other hand, in Examples 1 and 2 in which the thiophthalimide derivative or silica was blended in the second blending step, respectively, the results that the increase of Mooney viscosity with time and the shortening of scorch time with time were suppressed were observed. The effect of the improvement is remarkable in Example 3 in which

Continued on the front page (72) Inventor Fumi Yayanagi 2-1 Oiwake, Hiratsuka-shi, Kanagawa F-term in Yokohama Rubber Co., Ltd. Hiratsuka Works 4F070 AA08 AC04 AC05 AC23 AC50 AC52 AE01 AE03 AE08 FA03 FC03 FC05 4J002 AC011 AC031 AC061 AC071 AC081 BB181 DA036 DJ016 EV348 EX037 EX067 EX077 EX087 FD016 FD038 GN01

Claims (6)

[Claims] In producing a rubber composition comprising a filler and a silane coupling agent in a crosslinkable rubber,
Before kneading a raw material rubber with a filler containing a filler having a silanol group on the surface and a silane coupling agent, and then compounding a vulcanizing agent and a vulcanization accelerator, the following formula (I): (Wherein, R is an aliphatic hydrocarbon having 1 to 22 carbon atoms, an alicyclic hydrocarbon having 3 to 22 carbon atoms or an aromatic hydrocarbon having 6 to 22 carbon atoms) kneaded with a thiophthalimide derivative represented by the following formula: A method for producing a rubber composition. 2. In producing a rubber composition containing a filler and a silane coupling agent in a crosslinkable rubber,
A method for producing a rubber composition, comprising: kneading a filler containing a filler having a silanol group on its surface and a silane coupling agent into a raw rubber, and then mixing and kneading silica. 3. In producing a rubber composition containing a filler and a silane coupling agent in a crosslinkable rubber,
Before kneading a filler containing a filler having a silanol group on the surface and a silane coupling agent to a raw rubber, and then blending a vulcanizing agent and a vulcanization accelerator, the following formula (I): (Wherein, R is an aliphatic hydrocarbon having 1 to 22 carbon atoms, an alicyclic hydrocarbon having 3 to 22 carbon atoms or an aromatic hydrocarbon having 6 to 22 carbon atoms) kneaded with a thiophthalimide derivative represented by the following formula: A method for producing a rubber composition, further comprising kneading a filler containing a filler having a silanol group on the surface thereof with a silane coupling agent, and then mixing and kneading silica with the raw rubber. 4. The method for producing a rubber composition according to claim 1, wherein the amount of the thiophthalimide derivative is 0.1 to 1.0 part by weight per 100 parts by weight of the raw rubber. 5. The method according to claim 1, wherein a filler containing a filler having a silanol group on the surface and a silane coupling agent are kneaded and then added, and the amount of silica to be kneaded is 1 to 10 parts by weight per 100 parts by weight of rubber. 5. The method for producing a rubber composition according to 2, 3, or 4. 6. A rubber composition for a tire produced by the method according to any one of claims 1 to 5.