JP2018090699A - Materials mixing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a materials mixing method by which the dispersibility of materials can be improved, and a rubber composition and a pneumatic tire prepared by the same.SOLUTION: The present invention provides a materials mixing method for mixing two or more polymers with a kneader. Based on storage elastic moduli (G') of the polymers at 30°C and the temperature dependency of storage elastic moduli (G') of the polymers, the order of input of the polymers is determined.SELECTED DRAWING: None

Description

The present invention relates to a material kneading method, a rubber composition obtained by the material kneading method, and a pneumatic tire.

In recent years, due to the accompanying tire labeling system in each country, it is required for rubber to have a high level of performance (rolling resistance, wear performance, wet grip performance, etc.).

In order to draw out the potential of various materials, the dispersion of each material, particularly the improvement of the dispersion of the filler, contributes to the performance improvement. Therefore, it is desired to provide a technology related to this.

An object of the present invention is to provide a material kneading method capable of solving the above-described problems and improving the dispersibility of each material, a rubber composition and a pneumatic tire produced using the material kneading method.

The present invention is a material kneading method for kneading two or more polymers using a kneader,
The present invention relates to a material kneading method for determining the charging order of each polymer based on the storage elastic modulus (G ′ ₃₀ ) of each polymer at 30 ° C. and the temperature dependence of the storage elastic modulus (G ′) of each polymer.

In the material kneading method, in the temperature dependency of the storage elastic modulus (G ′) of each polymer, the change rate of the storage elastic modulus (G ′) is within the range of −0.5 to 0.3 kPa / ° C. When there is a temperature that changes to less than 5 kPa / ° C. When the temperature that changes to less than −1.5 kPa / ° C. is the plasticizing temperature of the polymer, and when there is no temperature that changes to less than −1.5 kPa / ° C. Is preferably determined that the polymer does not have a plasticizing temperature.

It is preferable that the material kneading method determines the charging order of each polymer based on the criteria determined in the following order (1) to (2).
(1) When the storage elastic moduli (G ′ ₃₀ ) at 30 ° C. are different, they are introduced in descending order of G ′ ₃₀ .
(2) When the storage elastic modulus (G ′ ₃₀ ) at 30 ° C. is the same, the change rate of the storage elastic modulus (G ′) is maintained at a high temperature within the range of −0.5 to 0.3 kPa / ° C. Put them in order.

The present invention relates to a rubber composition obtained by the material kneading method.
The present invention also relates to a pneumatic tire using the rubber composition.

The present invention is a material kneading method in which two or more kinds of polymers are kneaded using a kneader, and each of the polymers has a storage elastic modulus (G ′ ₃₀ ) at 30 ° C. and a storage elastic modulus (G ′) of each polymer. Therefore, the dispersibility of each material, particularly the dispersibility of the filler in the polymer can be improved.

It is an example of the figure which shows the temperature dependence of the storage elastic modulus (G'30) in ₃₀ degreeC of each polymer, and also the storage elastic modulus (G ') of each polymer. It is a figure which shows the temperature dependence of G 'of each polymer.

[Material kneading method]
The present invention is a material kneading method in which two or more kinds of polymers are kneaded using a kneader, and each of the polymers has a storage elastic modulus (G ′ ₃₀ ) at 30 ° C. and a storage elastic modulus (G ′) of each polymer. This is a material kneading method that determines the order in which each polymer is charged based on the temperature dependency of the polymer.

Improving the dispersibility of the filler is important for improving the performance, but in order to disperse the filler in the rubber (polymer), it is first necessary to plasticize the polymer so that the filler is taken in. This is sometimes referred to as “plasticization” or “wetting”. In particular, the present invention pays attention to the polymer property of ease of plasticization of the polymer, and by determining the order of introduction theoretically without changing the type of material, the plasticization points of a plurality of input polymers can be determined simultaneously. Thus, the dispersion is improved.

Specifically, when a plurality of polymers that are easily plasticized and difficult to plasticize are kneaded at the same time, it is difficult for the filler to enter the polymer that is difficult to plasticize, and as a result, the dispersion of the filler as a rubber composition deteriorates. . A polymer having a plasticizing temperature needs to be raised to a certain temperature before being plasticized. By first adding and starting kneading, the temperature of the polymer is increased first, and the plasticizing points of a plurality of input polymers are increased. Can be done at the same time.

In the present invention, the dispersibility of the filler can be enhanced even with a plurality of polymers based on the temperature dependence of the storage elastic modulus (G ′ ₃₀ ) of each polymer at 30 ° C. and the storage elastic modulus (G ′) of each polymer. For example, a polymer having a large storage elastic modulus (G ′ ₃₀ ) at 30 ° C., a polymer having a high plasticizing temperature, and G ′ is maintained up to a high temperature when it does not have a plasticizing temperature. By knead | mixing the polymer which does (it does not change) previously, these polymer temperatures will rise previously and it will be in the state which takes in a filler. Therefore, according to the method of the present invention, it is possible to provide a rubber composition excellent in various physical properties in which the filler is well dispersed even if two or more kinds of polymers having different capacities for incorporating the filler are used.

The material kneading method of the present invention in which two or more kinds of polymers are kneaded using a kneader is a temperature dependency of the storage elastic modulus (G ′ ₃₀ ) of each polymer at 30 ° C. and the storage elastic modulus (G ′) of each polymer. The charging order of each polymer is determined based on the properties.

For example, the charging order of each polymer is determined by the following method.
First, the temperature dependence of the storage elastic modulus G ′ of a polymer is measured. If G ′ does not change to a predetermined temperature and has a point at which it begins to drop sharply at a certain point, the temperature is set to the plasticizing temperature of the polymer. And set. Specifically, in the temperature dependence of the storage elastic modulus (G ′) of each polymer, the change rate of the storage elastic modulus (G ′) is −1.5 kPa from the range of −0.5 to 0.3 kPa / ° C. When there is a temperature that changes to less than / ° C., the temperature that changes to less than −1.5 kPa / ° C. is set as the plasticizing temperature of the polymer (the change rate of G ′ is shown in the temperature dependence curve of G ′). The lowest temperature at which the rate of change is less than -1.5 kPa / ° C when the location is -0.5 to 0.3 kPa / ° C and where the rate of change of G 'is less than -1.5 kPa / ° C. Is set as the plasticization temperature of the polymer).

On the other hand, if G 'does not change to high temperature (does not change to final temperature) or G' continues to drop linearly, the polymer is set to have no plasticization temperature. Specifically, in the absence of the changing temperature, the polymer is set to have no plasticizing temperature.

For each polymer, the presence or absence of the plasticizing temperature is measured, and if it is measured, the temperature is measured, and then the charging order of each polymer is determined based on the criteria determined in the order of (1) to (2) below. To do.
(1) When the storage elastic moduli (G ′ ₃₀ ) at 30 ° C. are different, they are introduced in descending order of G ′ ₃₀ .
(2) When the storage elastic modulus (G ′ ₃₀ ) at 30 ° C. is the same, the change rate of the storage elastic modulus (G ′) is maintained at a high temperature within the range of −0.5 to 0.3 kPa / ° C. Put them in order.

Specifically multiple G of the total polymer of (i) mixing 'when the ₃₀ different, G' was charged in order of _30, in this case, plasticized whether the temperature of each polymer, the temperature, the supply sequence It does not affect. For example, G _'30 is 25 kPa / ° C., G of the polymer B1' of polymer A1 ₃₀ 20 kPa / ° C., 'if ₃₀ is 15kPa / ℃, G' G polymers C1 as a large order of _30, the polymer A1, B1, Input in order of C1.

(Ii) 'include those having _30, the same G' identical G in a plurality of polymers of kneading when the polymer having a ₃₀ have both plasticizing temperature, first, to introduce a large polymer of G _'30 Assuming this, each polymer having the same G ′ ₃₀ is charged in the order in which the range in which the rate of change in G ′ is small continues to a high temperature, that is, in the order in which the plasticizing temperature is high. For example, when G ′ _{30 of} polymer A2 is 25 kPa / ° C., G ′ _{30 of} polymer B2 is 20 kPa / ° C. and the plasticizing temperature is 70 ° C., G ′ _{30 of} polymer C2 is 20 kPa / ° C. and the plasticizing temperature is 50 ° C. first, 'put the largest polymer A2 of _30, then, G' G ₃₀ is a plasticizing temperature is high polymer B2 at 20 kPa / ° C., finally plasticizing temperature turns on the low polymer C2.

(Iii) 'include those having _30, the same G' identical G in a plurality of polymers of kneading the polymer with _30, having a plasticizing temperature, the change in G 'without a plasticizing temperature In cases where a low rate range includes those that continue to a high temperature, and those that do not have a plasticizing temperature and G ′ falls linearly, it is the same on the assumption that a polymer with a large G ′ ₃₀ is first introduced. Each polymer having G ′ ₃₀ is in the order in which the rate of change of G ′ lasts to a high temperature in a range where the rate of change of G ′ is small, that is, a polymer having a low rate of change of G ′ up to the highest temperature (having no plasticization temperature) A polymer having a plasticizing temperature and a polymer in which G ′ continues to descend linearly (not having a plasticizing temperature) are added in this order. For example, the G ′ _{30 of the} polymer A3 is 25 kPa / ° C. and the range in which the change rate of G ′ is small is maintained up to a high temperature (no plasticization temperature), the G ′ _{30 of the} polymer B3 is 25 kPa / ° C. and the plasticization temperature is 50 ° C. When G ′ _{30 of} polymer C3 is 25 kPa / ° C. and G ′ is linearly lowered (no plasticization temperature), first, polymer A3 in which the range in which the change rate of G ′ is small continues to a high temperature, and then the plasticization temperature Polymer B3 at 50 ° C. (the range in which the rate of change of G ′ is small continues to 50 ° C.) and finally polymer C3 in which G ′ falls linearly (there is no range in which the rate of change of G ′ is small) are added.

FIG. 1 is an example of a graph showing the temperature dependence of the storage elastic modulus (G ′ ₃₀ ) of each polymer at 30 ° C., and further the storage elastic modulus (G ′) of each polymer. Each polymer (polymer to D), the 'different _30, the polymer A, B, C, G in the order of D' G ₃₀ is high. Therefore, the filler can be well dispersed in each polymer by charging the kneading machine in this order and kneading the polymer.

(Rubber composition)
Next, the rubber composition obtained by the material kneading method will be described.
In the rubber composition, for example, a first step of determining the charging order of each rubber component (each polymer) by the material kneading method, and a second step of charging and kneading each rubber component in the order determined in the first step. A step, a third step in which a filler is added to the kneaded product 1 obtained in the second step and a kneaded product 2 obtained in the third step is charged with a vulcanized chemical and kneaded. It can be produced by a production method including the fourth step of obtaining a vulcanized rubber composition.

(First step)
The first step is a step of determining the charging order of each rubber component (each polymer) by the material kneading method described above. That is, as described above, based on the storage elastic modulus (G ′ ₃₀ ) of each polymer at 30 ° C. and the temperature dependence of the storage elastic modulus (G ′) of each polymer, the charging order of each polymer is determined. Good.

(Second step)
In the second step, the first rubber component is charged and kneaded in the kneading machine in the order determined in the first step, and then the next rubber component is charged and kneaded until the final rubber component, and two or more types of rubber are repeated. A kneaded product 1 in which the component (polymer) is kneaded is obtained.

The kneading machine used in the second step is preferably a closed Banbury mixer. The shape of the rotor of the Banbury mixer may be tangential or meshing. The kneading temperature and kneading time may be set as appropriate.

As the rubber component, diene rubber is preferably used. As the diene rubber, natural rubber (NR) and diene synthetic rubber can be used. Examples of the diene synthetic rubber include isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), and acrylonitrile butadiene rubber. (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like. These may be used alone or in combination of two or more. For example, NR, BR, and SBR may be selected from the viewpoint of fuel efficiency and processability.

(Third process)
In the third step, a filler is added to the kneaded material 1 (mixture of rubber components) obtained in the second step and kneaded. Filling and kneading of the filler can be performed by a usual method.

As the kneader used in the third step, a closed Banbury mixer is preferable. The shape of the rotor of the Banbury mixer may be tangential or meshing. The kneading temperature and kneading time may be set as appropriate.

The filler is not particularly limited, and examples thereof include carbon black and silica.
Although it does not specifically limit as carbon black, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762 etc. are mentioned. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 5 m ² / g or more, more preferably 50 m ² / g or more, and still more preferably 100 m ² / g or more. By setting it to the lower limit or more, good fracture strength and the like tend to be obtained. Further, the _N 2 SA is preferably 200 meters ² / g or less, more preferably 150 meters ² / g, more preferably not more than 130m ² / g. By making it below the upper limit, good dispersion of carbon black can be easily obtained.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by JISK6217-2: 2001.

The silica is not particularly limited, and examples include silica prepared by a dry method (anhydrous silica) and silica prepared by a wet method (hydrous silica), etc., and there are many silanol groups on the surface and reaction with a silane coupling agent. Silica prepared by a wet method is preferred because it has many points. Silica may be used alone or in combination of two or more. Examples of commercially available silica include Ultrasil VN3 manufactured by Evonik.

Nitrogen adsorption specific surface area _(N 2 SA) of the silica, from the viewpoint of fracture properties, preferably ^90m 2 / g or more, more preferably ^{95 m} 2 / g or more, further preferably 100 m ² / g or more. Further, N ₂ SA of silica is preferably 300 m ² / g or less, more preferably 240 m ² / g or less, from the viewpoint of dispersibility of silica.
The nitrogen adsorption specific surface area of silica is a value measured by the BET method according to ASTM D3037-81.

In the third step, in addition to the rubber component and the filler, other components may be added and kneaded. Other components are not particularly limited as long as they are components other than vulcanized chemicals, and examples thereof include silane coupling agents, oils, anti-aging agents, waxes, stearic acid, and zinc oxide.

As the silane coupling agent, bis (3-triethoxysilylpropyl) disulfide, bis (bis) is preferable because it is easy to control the temperature during the reaction treatment in the first step and is excellent in the reinforcing effect of the rubber composition. Sulfide-based silane coupling agents such as (3-triethoxysilylpropyl) tetrasulfide and 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide are preferable, and bis (3-triethoxysilylpropyl) disulfide is more preferable. These silane coupling agents may be used alone or in combination of two or more.

(Fourth process)
The fourth step is a step of adding an vulcanized chemical to the kneaded material 2 obtained in the third step and kneading to obtain an unvulcanized rubber composition. Ordinary methods can be used for charging and kneading the vulcanizing chemical. The kneading temperature and kneading time may be set as appropriate.

The kneader used in the fourth step may be a closed Banbury mixer or an open roll.

Examples of vulcanizing chemicals include vulcanizing agents and vulcanization accelerators, and it is preferable to use vulcanizing agents and vulcanization accelerators in combination.

As the vulcanizing agent, organic peroxides, sulfur-based vulcanizing agents and the like can be used. Examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2, 5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne- Examples include 3,1,3-bis (t-butylperoxypropyl) benzene. Examples of the sulfur vulcanizing agent include sulfur and morpholine disulfide. These may be used alone or in combination of two or more. Especially, since the effect of this invention is acquired favorably, a sulfur type vulcanizing agent is preferable and sulfur is more preferable.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine, aldehyde-ammonia, imidazoline, and xanthate vulcanization accelerators. Is mentioned. These may be used alone or in combination of two or more. Of these, sulfenamide-based and guanidine-based are preferable, and the combined use of sulfenamide-based and guanidine-based is more preferable because the effects of the present invention can be obtained satisfactorily.

(Other processes)
The unvulcanized rubber composition obtained in the fourth step is extruded according to the shape of various tire members, molded by a normal method on a tire molding machine, and bonded together with other tire members. After forming the vulcanized tire, the tire can be manufactured by heating and pressing in a vulcanizer.

In the rubber composition of the present invention obtained by using the material kneading method from the viewpoint of low fuel consumption, processability, etc., the BR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably. Is 15% by mass or more, preferably 70% by mass or less, more preferably 50% by mass or less.

In the rubber composition of the present invention obtained by using the material kneading method from the viewpoint of low fuel consumption, processability, etc., the SBR content in 100% by mass of the rubber component is preferably 30% by mass or more, more preferably Is 50% by mass or more, preferably 95% by mass or less, more preferably 85% by mass or less.

In the rubber composition of the present invention obtained by using the material kneading method, the carbon black content is preferably 1 part by mass or more, more preferably 3 parts per 100 parts by mass of the rubber component from the viewpoint of reinforcement. More than part by mass. The carbon black content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 8 parts by mass or less from the viewpoint of low fuel consumption.

In the rubber composition of the present invention obtained by using the material kneading method, the content of silica is preferably 5 parts by mass or more, more preferably 30 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoint of reinforcement. Part or more, more preferably 50 parts by weight or more. The silica content is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, and still more preferably 100 parts by mass or less, from the viewpoint of processability.

In the rubber composition of the present invention obtained using the material kneading method, the content of the silane coupling agent is preferably 1 part by mass or more, more preferably 100 parts by mass with respect to 100 parts by mass of silica, from the viewpoint of reinforcing properties. 2 parts by mass or more. In addition, the content of the silane coupling agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, from the viewpoint of cost effectiveness.

In the rubber composition of the present invention obtained by using the material kneading method from the viewpoints of low fuel consumption and processability, the content of the vulcanizing agent is preferably 0.1 with respect to 100 parts by mass of the rubber component. It is not less than 0.5 parts by mass, more preferably not less than 0.5 parts by mass, preferably not more than 8 parts by mass, more preferably not more than 5 parts by mass.

From the viewpoint of low fuel consumption, processability, etc., in the rubber composition of the present invention obtained by using the material kneading method, the content of the vulcanization accelerator is preferably 0.00 with respect to 100 parts by mass of the rubber component. It is 5 parts by mass or more, more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less.

The pneumatic tire of the present invention produced by the above method can be suitably used for passenger car tires, large passenger car tires, large SUV tires, heavy duty tires such as trucks and buses, and light truck tires.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Polymer A: SBR (styrene content 25%)
Polymer B: SBR (styrene content 25%)
Polymer C: SBR (styrene content 39%)
Carbon black: N ₂ SA 114 m ² / g
Silica: N ₂ SA 175 m ² / g
Oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Silane coupling agent: bis (3-triethoxysilylpropyl) disulfide anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Stearic acid: Stearic acid “椿” manufactured by NOF Corporation
Zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powder sulfur vulcanization accelerator manufactured by Karuizawa Sulfur Co., Ltd. 1: Noxeller CZ (N-cyclohexyl-2) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. -Benzothiazolylsulfenamide)
Vulcanization accelerator 2: Noxeller D (N, N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

<Examples and Comparative Examples>
(First step)
About each polymer, the temperature dependence of the storage elastic modulus G 'was measured on the following conditions using the RPA2000 type tester by Alpha Technologies.
Temperature range: 30-150 ° C
Temperature rising condition: 3 ° C / min
Frequency: 10Hz
Distortion: 2%
FIG. 2 shows the temperature dependence of G ′ of each polymer. Based on this, the presence / absence of plasticizing temperature of each polymer, its temperature, and G ′ ₃₀ were determined and measured, and the results are shown in Table 1.
(Second step)
In the order shown in Table 3, the polymer was put into a Banbury mixer and masticated under the following conditions to prepare a kneaded product 1 composed of polymers A, B and C.
1) Kneading polymer A (kneading at 100 ° C. for 5 minutes)
2) Kneading polymer B (kneading at 100 ° C. for 5 minutes)
3) Kneading polymer C (kneading at 100 ° C for 5 minutes)
(Third process)
According to the blending contents shown in Table 2, materials other than sulfur and a vulcanization accelerator were put into a Banbury mixer and kneaded to obtain a kneaded product 2 (kneaded at 165 ° C. for 10 minutes and then discharged).
(Fourth process)
The obtained kneaded product 2, sulfur and vulcanization accelerator were put into an open roll and kneaded to obtain an unvulcanized rubber composition (kneading at 80 ° C. for 5 minutes).
(Vulcanization process)
The obtained unvulcanized rubber composition was vulcanized at 170 ° C. for 15 minutes to obtain a vulcanized rubber composition.

The following evaluation was performed about the unvulcanized rubber composition and vulcanized rubber composition obtained above. The results are shown in Table 3.

(Mooney viscosity)
According to JIS K6300, the Mooney viscosity of the unvulcanized rubber composition was measured at 130 ° C. Example 1 was represented as 100 and indicated as an index. The larger the index, the better the workability (workability index).

(Filler dispersibility)
For the vulcanized rubber composition, strains of 0.5, 1, 2, 4, 8, 16, 32, and 64% under conditions of 100 ° C. and 1 Hz using an RPA2000 type tester manufactured by Alpha Technologies, Inc. * Was measured, and from the difference between the maximum value of G * and the minimum value of G *, the Payne effect was obtained by the following equation.
ΔG * = (maximum value of G * −minimum value of G *) / maximum value of G * When the kneading is carried out effectively, the dispersion of the filler proceeds, and the smaller the ΔG *, the better the dispersibility of the filler It is. Example 1 was represented as 100 and indicated as an index. A larger index indicates better dispersibility (filler dispersibility index).

Example 1 introduced in the order of polymer introduction determined based on Table 1 (A → B → C: large order of storage elastic modulus G ′ ₃₀ at 30 ° C.) was compared with Comparative Examples introduced in other orders, Excellent workability and filler dispersibility. Therefore, the usefulness of the method of determining the charging order of each polymer based on the storage elastic modulus (G ′ ₃₀ ) of each polymer at 30 ° C. and the temperature dependence of the storage elastic modulus (G ′) of each polymer is confirmed.

In addition, although an Example and a comparative example showed the example which used the minimum material so that the effect and principle of the present invention may be understood easily, about tire performance, when a filler is thrown in, a filler of Since the contribution of the dispersion to the performance is large, the same result can be obtained even if other materials are further added.

Claims (5)

A material kneading method for kneading two or more polymers using a kneader,
A material kneading method for determining the charging order of each polymer based on the storage elastic modulus (G ′ ₃₀ ) of each polymer at 30 ° C. and the temperature dependence of the storage elastic modulus (G ′) of each polymer. In the temperature dependence of the storage elastic modulus (G ′) of each polymer, the change rate of the storage elastic modulus (G ′) changed from within the range of −0.5 to 0.3 kPa / ° C. to less than −1.5 kPa / ° C. If there is a temperature to change to less than -1.5 kPa / ° C, the temperature of the polymer is plasticized, and if there is no temperature to change to less than -1.5 kPa / ° C, the polymer is plasticized. The material kneading method according to claim 1, wherein the material kneading method is determined to have no temperature. The material kneading method according to claim 2, wherein the charging order of each polymer is determined on the basis of the criteria determined in the order of the following (1) to (2).
(1) When the storage elastic moduli (G ′ ₃₀ ) at 30 ° C. are different, they are introduced in descending order of G ′ ₃₀ .
(2) When the storage elastic modulus (G ′ ₃₀ ) at 30 ° C. is the same, the change rate of the storage elastic modulus (G ′) is maintained at a high temperature within the range of −0.5 to 0.3 kPa / ° C. Put them in order. A rubber composition obtained by the material kneading method according to claim 1. A pneumatic tire using the rubber composition according to claim 4.

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