JP2003026858A - Rubber composition for tire and method for producing tire by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for tires without causing corrosion of a processing machine with an acid component, improving a frictional performance of the tires on ice and having excellent a abrasion resistance by blending expanded graphite. SOLUTION: This rubber composition for the tires contains 100 pts.wt. diene- based rubber, 1-30 pt.wt. expanded graphite and 1.0-2.5 pt.wt. sulfenamide vulcanization accelerator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition for tires, and more specifically, it is an acid which may be generated from expanded graphite when a rubber composition is mixed and vulcanized by mixing expanded graphite with a diene rubber. Suitable for use as a tire with improved friction performance on ice while maintaining wear resistance at a practical level without causing problems such as corrosion of processing machinery due to its components, especially for treads of radial tires for ice and snow road running. TECHNICAL FIELD The present invention relates to a rubber composition for tires and a method for producing a pneumatic tire using the same for a tread portion, for example.

[0002]

2. Description of the Related Art There are many methods for improving the frictional force on ice by mixing hard foreign matter, a foaming agent, and hollow fine particles in rubber to form microscopic unevenness on the surface to remove a water film generated on the surface of ice. Is being considered. However, these methods have a problem in that the additives may be fragile, so that after mixing, some of the additives may be miniaturized or destroyed and the predetermined effects may not be exhibited. In addition, when these foreign matter powders are mixed in a rubber composition, the abrasion resistance of the rubber vulcanizate is generally significantly reduced.

For example, as an example of blending the above-mentioned hard foreign matter, JP-A-60-258235 (ceramic fine powder), JP-A-2-274740 (crushed plant) and JP-A-2-281052 are used. Although there are gazettes (metals) and the like, these methods have a problem in that the hardness of the rubber increases and the flexibility of the rubber is lost, so that the ability to follow the road surface is poor. Further, as examples of blending the hollow particles, there are JP-A-2-170840 and JP-A-2-170840.
Although there are JP-A-208336 and JP-A-4-5543, these methods also have a problem that the hardness of rubber similarly rises or hollow particles are broken during the mixing thereof. On the other hand, the thermally expandable microcapsules are compounded as hollow particles capable of improving the frictional force on ice of the rubber without increasing the hardness of the rubber and breaking by the shearing force at the time of kneading (JP-A-11-35736).
However, it is unavoidable that the wear resistance performance of the rubber vulcanizate decreases with the increase of the compounding amount.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention firstly developed a rubber composition for tires in which a vulcanized rubber has improved friction performance on ice while maintaining a balance with abrasion resistance, and a tire using the same. The method of manufacturing was proposed. However, when the rubber composition is processed, the acid component generated from the expanded graphite partially destroyed during mixing and the acid component generated by the expansion action during vulcanization may cause problems such as corrosion of the processing machine. was there.

Accordingly, the present invention provides a rubber composition for tires having improved icing performance of a vulcanized rubber without causing the above-mentioned problems such as corrosion of a processing machine based on an acid component derived from expanded graphite, and a rubber composition for the tire. An object of the present invention is to provide a method for manufacturing a pneumatic tire using

[0006]

According to the present invention, 100 parts by weight of a diene rubber, 1 to 30 parts by weight of expanded graphite and 1.0 to 2.5 parts by weight of a sulfenamide vulcanization accelerator are included. A rubber composition for a tire is provided.

According to the present invention, the diene rubber 10 is also used.
In manufacturing a tire using a rubber composition containing 0 part by weight, 1 to 30 parts by weight of expanded graphite, a vulcanizing agent and a sulfenamide vulcanization accelerator, first, expanded graphite, a vulcanizing agent and a sulfur are used. Except for the vulcanization system containing phenamide vulcanization accelerator, other components are kneaded together with the diene rubber, and then vulcanization containing expanded graphite and vulcanizing agent and sulfenamide vulcanization accelerator. The system is added and mixed under conditions such that the maximum temperature reached is below the expansion start temperature of the expanded graphite, and subsequent extrusion is carried out at similar temperature conditions, and a green tire is assembled with the extrudate of the rubber mixture, and then A method for manufacturing a tire is provided, which comprises vulcanizing a green tire at a temperature equal to or higher than an expansion start temperature of expanded graphite.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Expandable graphite is a powder material having a particle size of 30 to 600 μm, preferably 100 to 350 μm, which contains a substance that is vaporized by heat between layers of graphite particles. It is preferable to expand to become an expanded graphite (Expanded Graphite).

Expanded graphite has a structure in which sheets made of carbon atoms are laminated in layers and contain a vaporizable interlayer substance between the layers, and the interlayer substance is vaporized and expanded by heating, for example, to become a graphite expanded body. Since the material is hard before the expansion treatment, quality deterioration due to mixing is unlikely to occur, and since it irreversibly expands at a constant temperature, foreign matter with a space inside the rubber matrix can be easily formed by vulcanization of the tire. . The tread portion of the tire using such rubber has an appropriate surface irregularity when worn, and effectively removes the water film on the contact surface between the ice and the tire to improve the frictional force on ice.

On the other hand, expanded graphite has a good affinity with a rubber matrix and carbon black because it has a skeletal structure composed of carbon atoms, and even if it is added to the rubber, the abrasion resistance of the vulcanized rubber deteriorates. There is an advantage that there are few.

Expanded graphite is a known material and is manufactured by a known manufacturing method. Such expanded graphite generally contains an intercalation compound, which is volatilized by heat treatment to open the interlayer and expand. Conventionally, it usually expands by heat treatment at 300 ° C. or higher, but expanded graphite whose expansion start temperature is lowered to 300 ° C. or lower is manufactured and marketed by modifying the intercalation substance or using or using other low boiling acid compounds. ing. The processing temperature of the rubber composition containing a diene rubber as a main component in the present invention is 200 ° C. or lower, and in the present invention, a predetermined effect is exhibited by using expanded graphite whose expansion start temperature is 190 ° C. or lower. It

Examples of such expanded graphite having an expansion start temperature of 190 ° C. or lower include, for example, UCAR manufactured by Tomoe Kogyo in the United States.
Graphtech "Graph Guard 160-5"
0 ”or“ Graph Guard 160-80 ”and the like are commercially available.

Expanded graphite refers to an unexpanded product immediately after acid treatment, but it may be referred to as an expanded product after heat treatment. The expanded graphite blended as a rubber composition in the present invention is an unexpanded product before heat treatment. The particle size of the unexpanded graphite is not particularly limited, but is preferably 30 to 600 μm, more preferably 100 to 350 μm from the viewpoint of the effect of improving the frictional force on ice and workability.

In the present invention, the expanded graphite is preferably not expanded in the kneading step and extrusion molding step of the rubber composition but expanded in the vulcanization step, and the expansion start temperature is preferably 120 to 190 ° C., more preferably the expansion start temperature. Is used at 140 to 170 ° C. If the expansion start temperature is lower than 120 ° C., the expanded graphite may expand during kneading or during extrusion, and the rubber specific gravity may change during the process, which may impair the processability. Further, the expansion start temperature is 190
If the temperature exceeds ℃, the processing temperature in the vulcanization step must be set to 190 ° C. or higher, and the heat deterioration of the diene rubber molecule which is the main component of the rubber composition tends to be remarkable.

As described above, by blending the expanded graphite with the diene rubber, the frictional force on ice of the rubber is improved. However, when this rubber composition is processed, the expanded graphite is partially destroyed during mixing to generate an acid component. And the acid component is generated due to the expansion action even during vulcanization. This acid component has a problem that it may cause problems such as corrosion of processing machines.

According to the present invention, 1.0-2.5 parts by weight, preferably 1.2-about 100 parts by weight of a rubber of any sulfenamide accelerator conventionally known as a vulcanization accelerator is used. It has succeeded in solving such a problem by mix | blending 1.8 weight part. That is, the acid component generated from the expanded graphite during processing is rapidly neutralized in the rubber system by using a basic sulfenamide vulcanization accelerator as an accelerator, and remains in the rubber as an acid. Will disappear.
The vulcanization accelerating function of the sulfenamide vulcanization accelerator is lowered by the neutralization reaction, but this can be easily countered by increasing the compounding amount of the accelerator. Further, in the rubber composition further containing heat-expandable microcapsules, since the acid component generated from the expanded graphite during mixing is quickly neutralized, there is no erosion of the microcapsule shell material by the acid, and the microcapsule component is It is possible to exert a predetermined on-ice performance improving effect.

The sulfenamide vulcanization accelerator that can be used in the present invention is not particularly limited,
For example, a sulfenamide vulcanization accelerator represented by the following formula (I) or (II) can be used.

[0018]

[Chemical 2] (In the formula, R ¹ , R ² and R ³ independently represent an alkyl group having 1 to 6 carbon atoms)

More basically, N-cyclohexyl-2
-Benzothiazole sulfenamide (CBS), N-
t-butyl-2-benzothiazole sulfenamide (TBBS), N-oxydiethylene-2-benzothiazolyl sulfenamide (NOBS), N, N-dicyclohexyl-2-benzothiazolyl sulfenamide (DCBS) It can be given as a representative example.

The diene rubber used in the present invention is
Any diene rubber conventionally used for tires, for example, natural rubber (NR), polyisoprene rubber (IR), various styrene-butadiene copolymer rubbers (S
BR), various polybutadiene rubbers (BR), acrylonitrile-butadiene copolymer rubbers, and the like, and these can be used alone or as an arbitrary blend.

In the present invention, 1 to 30 parts by weight, preferably 5 to 15 parts by weight of the expanded graphite is mixed with 100 parts by weight of the diene rubber. If the blending amount is too small, the desired effect cannot be obtained, which is not preferable. On the contrary, if the blending amount is too large, the contact area at the micro level between the rubber surface and the icing road surface decreases, and the frictional force on ice decreases, which is not preferable. . If the blending amount is too large, the abrasion resistance and mechanical strength of the rubber vulcanizate will decrease, which is not preferable.

In the present invention, it is preferable that 100 parts by weight of the diene rubber be filled with a liquid or solid that is vaporized, decomposed or chemically reacted by heat to generate a gas, or thermally expandable thermoplastic resin particles (micro). Capsule) 1
20 parts by weight, more preferably 5 to 10 parts by weight can be further included. If the amount is too small, the desired effect cannot be obtained, and if it is too large, the wear resistance is significantly deteriorated, which is not preferable.

The heat-expandable thermoplastic resin particles (microcapsules) are powder particles in which a liquid or solid which vaporizes, decomposes or chemically reacts with heat to generate a gas is included in the thermoplastic resin, and the expansion start temperature thereof. Above temperature, usually 140
When heated at a temperature of ~ 190 ° C, it expands, and the gas is contained in the outer shell made of the thermoplastic resin.
The particle size of the thermoplastic resin particles is 5 to 300 μm before expansion.
Is preferable, and more preferably 10-20.
The thickness is 0 μm.

Examples of such heat-expandable thermoplastic resin particles include, for example, currently EXPANCEL in Sweden.
Company name as "Expansel 091 DU-80" or "Expansel 092 DU-120" or the like, or Matsumoto Yushi Co., Ltd. as trade name "Matsumoto Microsphere F-85" or "Matsumoto Microsphere F".
-100 "or the like.

The thermoplastic resin constituting the outer shell component of the gas-filled thermoplastic resin particles has an expansion start temperature of 100 ° C. or higher, preferably 120 ° C. or higher, and a maximum expansion temperature of 150 ° C. or higher, preferably Those having a temperature of 160 ° C. or higher are preferably used. As such a thermoplastic resin, for example, a (meth) acrylonitrile polymer or a copolymer having a high (meth) acrylonitrile content is preferably used. As the other monomer (comonomer) in the case of the copolymer, vinyl halide, vinylidene halide, styrene monomer, (meth) acrylate monomer, vinyl acetate, butadiene, vinyl pyridine, chloroprene and other monomers are used. . The above thermoplastic resins include divinylbenzene, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, It may be cross-linkable with a cross-linking agent such as allyl (meth) acrylate, triacrylic formal, triallyl isocyanurate. As for the cross-linking form, uncross-linking is preferable, but it may be partially cross-linked to the extent that the properties as a thermoplastic resin are not impaired.

Examples of the liquid or solid which vaporizes, decomposes or chemically reacts with the heat to generate a gas include, for example, n-
Hydrocarbons such as pentane, isopentane, neopentane, butane, isobutane, hexane, petroleum ether,
Liquids such as chlorinated hydrocarbons such as methyl chloride, methylene chloride, dichloroethylene, trichloroethane, trichloroethylene, or azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, toluenesulfonylhydrazide derivatives, fragrances Solids such as group succinyl hydrazide derivatives are mentioned.

The rubber composition of the present invention may contain, as a rubber-reinforcing agent, any carbon black usually contained in rubber compositions. Also, carbon black surface-treated with silica can be used. Silica can also be used. The amount of carbon black used is 20 to 80 parts by weight, preferably 30 to 60 parts by weight, based on 100 parts by weight of the rubber component. If the blending amount is too small, the rubber cannot be sufficiently reinforced, and therefore, for example, the abrasion resistance is deteriorated, which is not preferable. On the contrary, if the blending amount is too large, the hardness becomes too high or the workability is deteriorated, which is not preferable. The precipitated or dry silica is preferably added in an amount of 0 to 50 parts by weight, more preferably 0 to 20 parts by weight, based on 100 parts by weight of the rubber component. Silica does not have to be used, and when it is used, it is preferable to use it in a compounding amount such that the viscoelastic properties of vulcanized rubber such as tan δ are improved. This is not preferable because the cohesive force of the agent becomes strong and the dispersion during kneading becomes insufficient.

The carbon black used in the present invention preferably has a nitrogen adsorption specific surface area (N ₂ SA) of 70 m.
² / g or more, more preferably 80 to ²⁰⁰ m ² / g, and the dibutyl phthalate (DBP) oil absorption is preferably 95 ml / 100 g or more, more preferably 105 to 140.
It is ml / 100g.

According to the present invention, 100 parts by weight of diene rubber, particle size 30 to 600 μm, preferably 100 to
350 μm expanded graphite 1 to 30 parts by weight, preferably 5 to
In producing a tire using a rubber composition for a tire, which comprises 15 parts by weight and a vulcanizing system (for example, a vulcanizing agent such as sulfur and a vulcanization accelerator if necessary), expanded graphite and a vulcanizing system are used. Except for the other components, together with the diene rubber, kneading is performed using, for example, a Banbury mixer, and then expanded graphite and a vulcanization system are added so that the maximum attainable temperature is lower than the expansion start temperature of the expanded graphite, preferably expansion start. Mix at a temperature 20 ° C or more below temperature. Further extruded under the same temperature conditions as when kneading the expanded graphite, and after assembling a green tire by normal molding using this extrudate, a temperature above the expansion start temperature of the expanded graphite, preferably expansion start Vulcanize the green tire at a temperature 10 ° C or more higher than the temperature. When the temperature of the kneading, mixing or extruding step reaches a temperature equal to or higher than the expansion start temperature of the expansive graphite, the expansive graphite expands and the expandability in the vulcanizing step becomes insufficient, and the expansion expanded in the mixing and extruding step. It is not preferable because graphite breaks or deforms. Further, when the temperature of the mixing or extruding step reaches a temperature equal to or higher than the expansion start temperature of the expanded graphite, the specific gravity of the rubber composition is changed during the processing due to the expansion of the expanded graphite, which is not preferable.

The rubber composition for a tire according to the present invention further comprises a usual vulcanizing or crosslinking agent, other vulcanizing or crosslinking accelerators, various oils, antioxidants, fillers, plasticizers, and other general vulcanizing or crosslinking agents. Various additives that are commonly compounded for rubber can be compounded, and such compounds can be kneaded into a composition by a general method and vulcanized or crosslinked.
The amounts of these additives to be added can also be the conventional amounts generally used unless they are against the object of the present invention.

[0031]

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

Preparation of Samples of Comparative Examples 1 to 3 and Examples 1 to 3 According to the formulation (parts by weight) shown in Table I, 5 compounding agents such as rubber and carbon black were used in a 1.7 liter internal Banbury mixer. After mixing for a minute, releasing the rubber outside the mixer and cooling it to room temperature, with the same Banbury mixer,
A vulcanization accelerator, sulfur, microcapsules and expanded graphite were blended and mixed.

Evaluation Test of Samples In 300 g of water, 50 g of unvulcanized rubber or vulcanized rubber was boiled for 1 hour, and the pH after cooling the water was measured. Sheet-like rubber pieces obtained by vulcanizing each compound were attached to a flat columnar base rubber, and the friction coefficient on ice was measured by an inside drum type ice-on-friction tester. Measurement temperature is -3.0 ℃
The temperature was 1.5 ° C., the load was 5.5 kg / cm ³ , and the drum rotation speed was 25 km / h. The results are shown in Table II.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]Ingredients in Table I RSS # 3: Natural rubber NIPOL 1220: BR manufactured by Zeon Corporation, Gala
Transition temperature = 101 ° C SHOBLACK N220: Showa Cabot Co., Ltd.
Carbon black, N ₂ SA: 111m² / G, DBP
Oil absorption: 111ml / 100g SANTOFLEX 6PPD: Aging made by FLEXSIS
Preventive agent Zinc oxide No. 3: ZnO manufactured by Shodo Chemical Industry Co., Ltd. Stearic acid: manufactured by NOF CORPORATION Aroma oil: Fuji Kosan Co., Ltd. MBT: FLEXSIS-made thiazole vulcanization accelerator P
erkacit MBT MBTS: FLEXSIS-made thiazole vulcanization accelerator
Perkacit MBTS TBBS: Sulfenamide vulcanization accelerator made by FLEXSIS
Advancing agent Santocure TBBS CBS: Sulfenamide vulcanization acceleration made by FLEXSIS
Agent Santocure CBS Sulfur: Made by Karuizawa Smelter & Refinery Expanded graphite 160-50N: Expanded graphite commercially available from Tomoe Kogyo (average
(Particle size: 300 μm, expansion start temperature: 160 ° C) Microcapsule: Matsumoto Yushi Microsphere F
100

[0037]

As described above, according to the present invention, the diene rubber is mixed with the expansive graphite and, in some cases, the thermally expansive gas-filled thermoplastic resin and the sulfenamide vulcanization accelerator. It is possible to improve the frictional performance on ice of the vulcanized rubber while maintaining the balance with the wear resistance, without causing the problem of corrosion of the processing machine due to the acid component based on the expanded graphite.

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08K 5/44 C08K 5/44 // B29K 9:00 B29K 9:00 105: 16 105: 16 105: 24 105: 24 307: 04 307: 04 B29L 30:00 B29L 30:00 (72) Inventor Takashi Shirokawa 2-1, Oiwake, Hiratsuka, Kanagawa Yokohama Rubber Co., Ltd. Hiratsuka Factory F-term (reference) 4F207 AA46 AB03 AB17 AB18 AH20 KA01 KA17 KK12 KW33 4J002 AC011 AC031 AC061 AC071 AC081 DA026 DA039 DJ018 EV197 GN01

Claims (7)

[Claims] 1. A diene rubber 100 parts by weight, and expanded graphite 1
˜30 parts by weight and sulfenamide vulcanization accelerator 1.0
A rubber composition for a tire, which comprises ˜2.5 parts by weight. 2. The rubber composition according to claim 1, further comprising 1 to 20 parts by weight of microcapsules, which expands by heat to form a gas-filled thermoplastic resin, relative to 100 parts by weight of the diene rubber. 3. The rubber composition according to claim 1, wherein the glass transition temperature of the diene rubber is −55 ° C. or lower on average. 4. The sulfenamide vulcanization accelerator has the formula (I) and / or (II): (Wherein R ¹ , R ² and R ³ independently represent an alkyl group having 1 to 6 carbon atoms).
The rubber composition according to any one of 3 above. 5. 20 to 80 parts by weight of carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 70 m ² / g or more and a dibutyl phthalate (DBP) oil absorption of 95 ml / 100 g or more based on 100 parts by weight of rubber. The rubber composition according to claim 1, further comprising 0 to 50 parts by weight of precipitated or dry silica. 6. A diene rubber 100 parts by weight, and expanded graphite 1
In producing a tire using a rubber composition containing 30 to 30 parts by weight and a vulcanizing agent and a sulfenamide-based vulcanization accelerator, first, expanded graphite and a vulcanizing agent and a sulfenamide-based vulcanization accelerator are used. And other components except the vulcanization system containing kneaded together with the diene rubber, and then added the vulcanization system containing expanded graphite and vulcanizing agent and sulfenamide vulcanization accelerator Is mixed below the expansion start temperature of the expanded graphite and the subsequent extrusion is performed under similar temperature conditions, and a green tire is assembled from the extruded product of the rubber mixture, and then the expansion start temperature of the expanded graphite or higher. A method for manufacturing a tire, which comprises vulcanizing a green tire at a temperature of. 7. A radial tire for traveling on ice and snowy roads, wherein the rubber composition according to claim 1 is used for a tread of a pneumatic tire.