JP2003327751A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition that uses a nanocomposite rubber to improve physical properties such as reinforcing properties of a material prepared by dispersing a filler in a rubber component by kneading. <P>SOLUTION: This rubber composition comprises the rubber component, the filler, and the nanocomposite rubber with a layered clay mineral dispersed in a diene rubber at a molecular level. The filler is 1-99 pts.mass based on 100 pts.mass of the sum of the nanocomposite rubber and the rubber component. The layered clay mineral is present in the nanocomposite rubber in an amount of 1-50 mass%. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition, and more particularly to a rubber composition containing a nanocomposite rubber used for tires.

[0002]

2. Description of the Related Art In recent years, rubber materials have been required to have higher performance and higher functionality. Particularly, in automobile tires, strict characteristics have been demanded due to speeding up of automobiles. Is coming.

Conventionally, a rubber material has been produced by kneading a filler such as an inorganic mineral with a rubber component using a Banbury mixer, a kneader or the like to form a compound. At this time, the bond between the filler and the rubber component is mainly only a weak intermolecular force, and the chemical bond is hardly involved, so that it is difficult to obtain a rubber material having significant properties. That is, even if the filler is dispersed in the rubber by kneading, uniform and fine dispersion cannot be obtained, and it is difficult to obtain sufficient reinforcing property. Furthermore, depending on the inorganic powder used, there are some that cannot be used as tires because of poor dispersion in the rubber component.

[0004]

Therefore, the present invention provides a rubber composition having high performance and high functionality by dispersing a filler in a rubber component at a molecular level or a nano level to form a nanocomposite structure. The purpose is to provide.

[0005]

The rubber composition of the present invention comprises:
A rubber composition comprising a nanocomposite rubber in which a rubber component, a filler, and a layered clay mineral are dispersed in a diene rubber at a molecular level, wherein the layered clay mineral is contained in the nanocomposite rubber in an amount of 1% by mass to 50% by mass. It is characterized by being present in a mass%.

[0006] Preferably, the filler is 1 to 100 parts by weight of the total of the nanocomposite rubber and the rubber component.
It can be 99 parts by weight.

Preferably, the diene rubber of the nanocomposite rubber is styrene butadiene rubber, cis polyisoprene, cis polybutadiene, ethylene propylene rubber,
It is preferable that the layered clay mineral is at least one of chloroprene rubber, butyl rubber, and halogenated butyl rubber, and the layered clay mineral is montmorillonite.

Further, the filler is carbon black,
It is preferable to include any one of silica, kaolin, clay, talc, feldspar, calcium carbonate, and aluminum hydroxide.

Further, the rubber component contains at least one of natural rubber, cis polyisoprene, cis polybutadiene, ethylene propylene rubber, chloroprene rubber, styrene butadiene rubber, butyl rubber, halogenated butyl rubber and acrylonitrile-butadiene rubber. preferable.

With the above rubber composition provided by the present invention, properties required for the tire, such as breaking strength and flex fatigue, can be remarkably improved, and a tire having more excellent properties can be provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION (Nanocomposite Rubber) In general, a nanocomposite refers to a composite material in which a reinforcing substance is ultrafinely dispersed in a matrix polymer in a nanometer size (about 1 to 100 nm). In the present invention,
A layered clay mineral dispersed in a diene rubber component at a molecular level or a nano level is used. This allows
Excellent heat resistance and strength can be obtained. Layered clay minerals that can be used include kaolin, such as hylosite and amesite, smectites, such as monlorillonite and hectorite, mica clay minerals, such as phlogopite and celadonite, and chlorite, such as kukkeite. They may be used alone or in combination. Suitably, montlorillonite may be used. In the nanocomposite rubber, the layered clay mineral is present in the nanocomposite rubber in an amount of 1 to 50% by mass, preferably 3 to 20% by mass. If it is less than 1% by mass, sufficient tensile strength, tensile modulus and flexural modulus cannot be obtained in the produced composite, and if it exceeds 50% by mass, the content of diene rubber is decreased and sufficient impact strength is obtained. Will not be obtained. Further, in the present invention, the diene rubber used for preparing the nanocomposite rubber includes styrene butadiene rubber, cis polyisoprene, cis polybutadiene, ethylene propylene rubber, chloroprene rubber, butyl rubber, halogenated butyl rubber, and other diene rubbers. Is mentioned. Styrene butadiene rubber is preferably used.

Next, a method for producing the nanocomposite rubber of the present invention will be described with reference to FIG. First, FIG. 1 (A)
As shown in Fig. 2, a diene rubber monomer is mixed in water as a medium, and soaps such as fatty acid sodium, disproportionated sodium rosinate and sodium alkylallylsulfonate are added to the mixed solution to prepare an emulsion. To do. Then, as shown in FIG. 1 (B), a layered clay mineral (for example, monlorillonite) is added to this emulsion to intercalate the monomer between the layered clay mineral layers,
And let it swell. After that, as a polymerization initiator, a water-soluble organic peroxide such as potassium persulfate and paraffin hydroperoxide was used as an oxidizing agent, and ferrous sulfate and sodium formaldehyde sulfoxylate were used as reducing agents, and then chelated with EDTA. In addition, the monomer is polymerized into a polymer within the layered clay mineral layer as shown in FIG. 1 (C). At this time, n-dodecyl mercaptan, t-dodecyl mercaptan, etc. can be added as a molecular weight regulator. as a result,
The layered clay minerals can be successively finely dispersed to form a nanocomposite rubber. The rubber thus formed has high performance and high performance, and particularly exhibits good heat resistance, strength and wear characteristics. The nanocomposite rubber manufactured as described above can be evaluated by using X-ray diffraction and an electron microscope.

(Rubber Component) The rubber composition containing the nanocomposite of the present invention may contain a rubber component in order to give the tire the properties required when used as a tire. In addition, it is necessary to select the material to be used according to the site where the tire is used. In the nanocomposite rubber composition of the present invention, usable rubber components are:
Natural rubber, cis polyisoprene, cis polybutadiene, ethylene propylene rubber, chloroprene rubber,
Examples thereof include styrene butadiene rubber, butyl rubber, halogenated butyl rubber, and acrylonitrile-butadiene rubber, but the present invention is not limited thereto, and it is preferable to use at least one or more of them. In the present invention,
Polybutadiene, styrene butadiene rubber and natural rubber are preferably used, and more preferably natural rubber is used. The reason is that these rubbers have excellent compatibility and are mixed well when compounded with the nanocomposite rubber. Further, the reinforcing property can be greatly improved without impairing the basic properties such as tensile strength, modulus and hysteresis. The rubber component is the nanocomposite rubber 10
0 to 99 parts by weight, preferably 20
It is preferably contained in an amount of about 80 parts by mass. If it exceeds 99 parts by mass, the properties of the nanocomposite rubber cannot be sufficiently obtained.

(Filler) The filler is strength, heat resistance,
Used as a reinforcing material for further imparting properties such as abrasion resistance to the rubber composition. Fillers that can be used include, but are not limited to, carbon black, silica, kaolin, clay, talc, feldspar, calcium carbonate and aluminum hydroxide. In the present invention, at least one of these may be used, and two or more of these may be used in combination. In the present invention, carbon black is preferably used and can be masterbatched with the rubber component. The filler is contained in an amount of 1 to 99 parts by mass, preferably 30 to 80 parts by mass, based on 100 parts by mass of the total of the nanocomposite rubber and the rubber component. When it is less than 1 part by mass, abrasion resistance and strength are deteriorated, while when it exceeds 99 parts by mass, workability is deteriorated.

(Additives) In addition to the above, the rubber composition containing the nanocomposite rubber of the present invention includes, in addition to the above, vulcanizing agents such as sulfur which are usually used in the rubber industry, various vulcanization accelerators, various softening agents, Additives such as various antiaging agents, stearic acid, oil, antioxidants, antiozonants, polymerization initiators and zinc oxide can be added.

(Production Method of Tire Using Rubber Composition Containing Nanocomposite Rubber) A tire can be produced using the rubber composition of the present invention. As the manufacturing method, a conventional one can be used, and first, the rubber component, the filler and the nanocomposite rubber described above are masticated,
Mix and mix to mix. A Banbury mixer can be mainly used as the kneading machine. Next, using the compounded rubber, tread rubber, sidewall rubber, beet filler, carcass ply rubber, and other members required for tire formation are manufactured. Then, the obtained members are assembled using a tire molding machine and vulcanized. Then, the protruding rubber is removed to obtain a tire. Since the tire obtained as described above contains the nanocomposite rubber, it can exhibit good heat resistance, strength and abrasion resistance.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 (Preparation of Nanocomposite Rubber) 360 g of water (20
150 g of styrene (Asahi Kasei) and 50 g of butadiene (Nippon Zeon) are added to the solution, and sodium dialkylsulfosuccinate (Perex O) which is soap is added to the solution.
10 g of TP (Kao) was further mixed to prepare an emulsion. 20 g of bentonite was added to the solution, and the monomer was intercalated between the bentonite layers for 60 minutes. Next, 0.6 g of potassium persulfate (industrial gas chemistry), which is a polymerization initiator, was added, and the mixture was added at 12
It was polymerized for a time. Bentonite was successively finely dispersed to form a nanocomposite, and after performing necessary post-treatments, 150 g of nanocomposite rubber was obtained. The content of the layered clay mineral in the nanocomposite rubber is 12.
It was 5% by mass.

(Preparation of rubber composition containing nanocomposite rubber) 80 parts by mass of the above nanocomposite rubber, 30 parts by mass of natural rubber and 60 parts by mass of carbon black were masticated and compounded using a Banbury mixer. Compounded. Then, using this compounded rubber, a tread rubber was produced through an extrusion process. In this step, necessary additives were added. Then, this tread rubber was vulcanized at 170 ° C. for 15 minutes. Table 1 shows the composition of the obtained vulcanized rubber.

Comparative Example 1 A vulcanized rubber was produced through the same steps as in Example 1 except that 70 parts by mass of styrene-butadiene rubber (SBR1502) was used instead of the nanocomposite rubber in Example 1 above. . Table 1 shows the composition in the obtained vulcanized rubber.

(Comparative Example 2) As an alternative to the nanocomposite rubber in the above-mentioned Example 1, 70 parts by mass of styrene-butadiene rubber (SBR1502) and 10 parts by mass of bentonite were compounded by kneading without being made into nanocomposite. A vulcanized rubber was produced through the same steps as in Example 1 except for the above. Table 1 shows the composition in the obtained vulcanized rubber.

[0022]

[Table 1]

Note 1) Nipol 1502: Nippon Zeon Note 2) RSS 3: SOUTHLAND RUBBER Note 3) Seast KH: Tokai Carbon Note 4) Process X-140: Japan Energy Note 5) Zinc oxide: Mitsui Mining & Smelting Note 6) Bead stearic acid / Tsubaki: Nippon Oil & Fats Note 7) Antigen 6c: Sumitomo Chemical Co., Ltd. Note 8) Sunnock N: Ouchi Seiko Kagaku Kogyo Note 9) Oil-treated sulfur: Karuizawa Smelter & Refinery Note 10) Nox Cellar CZ: Ouchi Shinko Chemical Industry.

(Evaluation) The vulcanized rubbers produced in Example 1 and Comparative Examples 1 and 2 were evaluated as follows. Breaking strength (TB) Measured by a method according to JIS K6251. -Elongation at break (EB) Measured by a method according to JIS K6251. -300% modulus (M300) It measured by the method according to JIS K6251. Hardness (Hs) Measured by a method according to JIS K6253. Bending fatigue resistance Measured according to JIS K6260. Viscoelastic property E *, tan δ Measured at a temperature of 70 ° C., an initial strain of 10% and an amplitude of ± 1% using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho. -Air permeation resistance It was measured using a gas permeability measuring device manufactured by Toyo Seiki Seisakusho. With respect to the above evaluation, Table 2 shows the results expressed as an index with Comparative Example 1 set to 100.

[0025]

[Table 2]

From Table 2, it can be seen that the vulcanized rubber using the rubber composition containing the nanocomposite rubber of the present invention has a higher breaking strength than the vulcanized rubber not using the nanocomposite rubber and the vulcanized rubber by kneading. It can be seen that is significantly improved. Furthermore, it can be seen that the bending fatigue resistance and the air permeation resistance are also improved.

The embodiments and examples disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0028]

As described above, the nanocomposite rubber composition of the present invention contains a nanocomposite in which a layered clay mineral such as monlorilonite is ultrafinely dispersed in a diene polymer. It is possible to increase the breaking strength of the vulcanized rubber produced by using it. Further, the bending fatigue resistance and the air permeation resistance can be significantly increased, and a high-performance and high-performance vulcanized rubber, particularly a tire can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing each step in which a layered clay mineral is ultrafinely dispersed in a diene-based polymer matrix to produce a nanocomposite rubber, and (A) is a step of preparing an emulsion of a diene-based monomer, (B) is a step of intercalating a monomer between layered clay minerals, and (C) is
It is a state in which a monomer is polymerized to form a nanocomposite.

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Claims (5)

[Claims] 1. A rubber composition comprising a nanocomposite rubber in which a rubber component, a filler, and a layered clay mineral are dispersed in a diene rubber at a molecular level, wherein the layered clay mineral is contained in the nanocomposite rubber. 1% by mass to 5
A rubber composition, characterized in that it is present at 0% by weight. 2. The rubber composition according to claim 1, wherein the filler is 1 to 99 parts by mass with respect to a total of 100 parts by mass of the nanocomposite rubber and the rubber component. 3. The diene rubber of the nanocomposite rubber is at least one of styrene butadiene rubber, cis polyisoprene, cis polybutadiene, ethylene propylene rubber, chloroprene rubber, butyl rubber and halogenated butyl rubber, and the layered clay mineral is The rubber composition according to claim 1, wherein the rubber composition is montmorillonite. 4. The filler according to claim 1, wherein the filler contains any one kind of carbon black, silica, kaolin, clay, talc, feldspar, calcium carbonate, and aluminum hydroxide. Rubber composition. 5. The rubber component is natural rubber, cis polyisoprene, cis polybutadiene, ethylene propylene rubber,
The rubber composition according to any one of claims 1 to 4, which comprises at least one of chloroprene rubber, styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, and acrylonitrile-butadiene rubber.