JP5172091B2 - Method for producing rubber composition for tire - Google Patents

Description

  The present invention relates to a method for producing a tire rubber composition.

  High-performance tires such as racing tires are required to have dry grip performance and wet grip performance. In order to obtain dry grip performance and wet grip performance, a tire rubber composition requires a large energy loss (tan δ) in a wide temperature range from room temperature to high temperature.

  In order to satisfy the energy loss of such a rubber composition, it is conceivable to add a liquid polymer to the rubber composition. In this case, there is a problem that the degree of freedom of the blending amount is low. Further, since the liquid polymer scattered during the kneading adheres to or remains in the kneading machine, there is also a problem that dispersion of the compound in the rubber composition tends to vary. Furthermore, when it mix | blends abundantly, the viscosity of a compound was caused to fall and there existed a problem that dispersibility, such as carbon black, fell.

  Patent Document 1 discloses a tire rubber composition having a masterbatch composed of styrene-butadiene rubber and silica. However, since the styrene-butadiene rubber in the rubber composition is not liquid, silica is used. The dispersion of was not sufficient.

JP-A-2005-206680

  The present invention provides a method for producing a rubber composition for a tire in which carbon black and / or silica is sufficiently dispersed while suppressing processing problems such as scattering and adhesion of the kneaded material to the kneader during kneading. For the purpose.

  The present invention includes (1) a step of mixing a liquid polymer having a weight average molecular weight of 1000 to 10,000, and silica and / or carbon black, and (2) mixing the mixture obtained in step (1) with a rubber component. The present invention relates to a method for producing a rubber composition for a tire comprising steps.

The BET specific surface area of the silica is preferably 100 m ² / g or more.

  Moreover, this invention relates to the rubber composition for tires obtained by the said manufacturing method.

  According to the present invention, the liquid polymer is not kneaded alone, but pre-blended with the liquid polymer and carbon black, so that the kneaded material is dispersed and adhered to the kneader during kneading. It is possible to provide a method for producing a tire rubber composition in which carbon black and / or silica is sufficiently dispersed while suppressing the problem. Furthermore, the tire obtained from the tire rubber composition has excellent wet grip performance and dry grip performance.

  The method for producing a rubber composition for a tire according to the present invention comprises (1) a step of mixing a liquid polymer and silica and / or carbon black, and (2) mixing the mixture obtained in step (1) with a rubber component. It consists of the process to do.

  The liquid polymer to be mixed in the step (1) refers to a liquid that shows a liquid state at room temperature, and is preferably used as a softening agent.

  The weight average molecular weight (Mw) of the liquid polymer is 1000 or more, preferably 1500 or more. If Mw is less than 1000, the wear resistance is inferior, and the necessary grip performance cannot be obtained. The Mw of the liquid polymer is 10,000 or less, preferably 9000 or less, more preferably 8000 or less. If Mw exceeds 10,000, grip performance at low temperatures cannot be obtained.

BET specific surface area of silica is preferably at least 100 m ² / g, more preferably at least 110m ² / g, still more preferably at least 170m ² / g. When the BET specific surface area is less than 100 m ² / g, there is a tendency that the grip performance and the wear resistance are not compatible. Further, BET specific surface area of silica used in the masterbatch is preferably from 250 meters ² / g or less, more preferably 220 m ² / g. When the BET specific surface area exceeds 250 m ² / g, the dispersibility tends to decrease.

The carbon black has a cetyltrimethylammonium bromide specific surface area (CTAB specific surface area) of preferably 100 m ² / g or more, and more preferably 120 m ² / g or more. If the CTAB specific surface area is less than 100 m ² / g, the required grip performance cannot be obtained, and the wear resistance tends to decrease. Further, CTAB specific surface area of the carbon black is preferably 300 meters ² / g or less, more preferably 250m ² / g. When the CTAB specific surface area exceeds 300 m ² / g, the dispersibility is lowered and the wear resistance tends to be extremely inferior.

  The blending amount of silica and / or carbon black in the step (1) is preferably 40 parts by weight or more, and more preferably 45 parts by weight or more with respect to 100 parts by weight of the liquid polymer. When the blending amount is less than 40 parts by weight, there is a tendency that adhesion is strong and removal is difficult. Further, the blending amount of silica and / or carbon black in the step (1) is preferably 80 parts by weight or less, more preferably 70 parts by weight or less with respect to 100 parts by weight of the liquid polymer. When the blending amount exceeds 80 parts by weight, silica / carbon that cannot be sufficiently mixed tends to remain.

  It is preferable that the mixing process of a process (1) is mixed with closed type mixers, such as a Banbury mixer and a kneader.

  30-170 degreeC is preferable and the mixing temperature in the mixing process of a process (1) has more preferable 30-150 degreeC. If the mixing temperature is less than 30 ° C., the liquid polymer is hard and mixing tends to be difficult. On the other hand, if the mixing temperature exceeds 170 ° C., low molecular weight components may be diffused from the liquid polymer.

  The mixing time in the mixing step of step (1) is preferably 3 minutes or more. If the mixing time is less than 3 minutes, the dispersion tends to be insufficient.

  Examples of the rubber component to be mixed in the step (2) include arbitrary diene rubbers. Specifically, natural rubber (NR), polyisoprene rubber (IR), various polybutadiene rubbers (BR), and various styrene- Examples thereof include butadiene copolymer rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber, and polychloroprene (CR). In particular, SBR, particularly SBR having a high styrene content, is preferable because an effect of achieving both grip performance and wear resistance can be obtained.

  In the step (2), it is preferable to mix a reinforcing filler in addition to the mixture and the rubber component obtained in the step (1).

  As reinforcing fillers, carbon black, silica, talc, clay, etc., which are common in the tire industry can be mixed, but among them, the effect of achieving both grip performance and wear resistance can be obtained. Silica and / or carbon black are preferred.

  In the step (2), it is preferable to add a softener.

  As the softening agent, those commonly used in the tire industry such as aroma oil can be mixed. The softener includes oil in oil-extended rubber.

  In the step (2), waxes generally used in the tire industry, antiaging agents, stearic acid, zinc oxide and the like can be blended.

  The mixing step of step (2) is preferably mixed by a closed mixer such as a Banbury mixer or a kneader, and the discharge temperature is preferably 140 to 170 ° C.

  The production method of the present invention preferably further includes a step of further mixing a vulcanizing agent and a vulcanization accelerator with respect to the mixture obtained through (3) step (2).

  Examples of the vulcanizing agent include sulfur generally used in the tire industry. Examples of the vulcanization accelerator include those generally used in the tire industry, such as a sulfenamide vulcanization accelerator and a guanidine vulcanization accelerator.

  In the production method of the present invention, the mixture obtained through the step (3) is preferably vulcanized. The vulcanization temperature is preferably 150 to 185 ° C., and the vulcanization time is preferably 10 to 60 minutes.

  The rubber composition for tires can be produced by the production method of the present invention.

  In the tire rubber composition, the content of the liquid polymer is preferably 5 parts by weight or more, and more preferably 10 parts by weight or more with respect to 100 parts by weight of the rubber component. If the content is less than 5 parts by weight, there is a tendency that sufficient grip performance cannot be obtained. Further, in the tire rubber composition, the content of the liquid polymer is preferably 100 parts by weight or less, and more preferably 80 parts by weight or less with respect to 100 parts by weight of the rubber component. When the content exceeds 100 parts by weight, the wear resistance tends to be remarkably lowered.

  In the tire rubber composition, the total content of silica and / or carbon black is preferably 50 parts by weight or more, and more preferably 80 parts by weight or more with respect to 100 parts by weight of the rubber component. If the total content is less than 50 parts by weight, grip performance and wear resistance tend not to be obtained. In the tire rubber composition, the total content of silica and / or carbon black is preferably 180 parts by weight or less and more preferably 150 parts by weight or less with respect to 100 parts by weight of the rubber component. When the content exceeds 180 parts by weight, the workability is lowered, the heat generated in the tire is large, and the durability performance tends to be affected. The total content of silica and / or carbon black refers to the total amount of silica and / or carbon black compounded in steps (1) and (2).

  The total content of the softening agent in the tire rubber composition is preferably 60 parts by weight or more, and more preferably 80 parts by weight or more with respect to 100 parts by weight of the rubber component. When the content is less than 60 parts by weight, there is a tendency that sufficient grip performance cannot be obtained. Further, the total content of the softening agent in the tire rubber composition is preferably 200 parts by weight or less, and more preferably 170 parts by weight or less with respect to 100 parts by weight of the rubber component. When the content exceeds 200 parts by weight, the workability tends to decrease. Note that the total content of the softening agent includes the content of the liquid polymer.

  Specific examples of tires obtained from the rubber composition for tires include racing tires and passenger car tires, but it is possible to improve performance such as dry grip performance and wet grip performance. In particular, racing tires are preferred.

  The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

The various compounding agents used in the present invention are shown below.
Oil exhibition SBR: Toughden 4350 manufactured by Asahi Kasei Co., Ltd. (40% styrene-containing SBR, 50 parts by weight of oil with respect to 100 parts by weight of SBR)
Carbon Black 1: Diamond Black I (N220, CTAB specific surface area: 111 m ² / g) manufactured by Mitsubishi Chemical Corporation
Carbon Black 2: Diamond Black A (N110, CTAB specific surface area: 126 m ² / g) manufactured by Mitsubishi Chemical Corporation
Silica 1: Z115Gr (BET specific surface area: 112 m ² / g) manufactured by Rhodia
Silica 2: Nipsil VN3 manufactured by Nippon Silica Kogyo Co., Ltd. (BET specific surface area: 208 m ² / g)
Silane coupling agent: Si266 manufactured by Degussa
Liquid SBR: Rycon 100 manufactured by Sartomer (weight average molecular weight: 6000)
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Anti-aging agent 6PPD: Santoflex 13 manufactured by Flexis
Stearic acid: Tungsten zinc oxide manufactured by NOF Corporation: Zinc oxide manufactured by Mitsui Kinzoku Mining Co., Ltd. Sulfur: Tsurumi Chemical Co., Ltd. vulcanization accelerator CBS: Ouchi Shinsei Chemical Co., Ltd. Noxeller CZ
Vulcanization accelerator DPG: Noxeller D from Ouchi Shinsei Chemical Co., Ltd.

<Method for producing master batches 1 to 4>
(Master batch 1)
In a kneader, at 50 ° C., liquid SBR (Lycon 100) and carbon black 1 (Diamond I) were mixed at a weight ratio of 60:40 for 15 minutes to prepare a master batch 1.

(Master batch 2)
In a kneader, at 50 ° C., liquid SBR (Lycon 100) and carbon black 2 (Dia Black A) were mixed at a weight ratio of 60:40 for 15 minutes to prepare a master batch 2.

(Master batch 3)
Master batch 3 was produced by mixing liquid SBR (Lycon 100) and silica 1 (Z115Gr) at a weight ratio of 60:40 for 15 minutes at 50 ° C. in a kneader.

(Master batch 4)
Masterbatch 4 was produced by mixing liquid SBR (Lycon 100) and silica 2 (Nipsil VN3) at a weight ratio of 60:40 for 15 minutes in a kneader at 50 ° C.

Examples 1-4 and Comparative Examples 1-4
(Preparation of unvulcanized kneaded product and calculation of residual rate in kneader)
Add the compounding ingredients except sulfur and vulcanization accelerators CBS and DPG to the blending amounts shown in Table 1 and kneading machines (Banbury mixer), knead them at a discharge temperature of 160 ° C, and discharge the unvulcanized kneaded material did. In addition, before putting into a Banbury mixer, the total amount of the compounding agent thrown into a Banbury mixer was measured, respectively.

Then, the weight of the discharged unvulcanized kneaded material was measured, and the “residual ratio in the kneader” of the unvulcanized kneaded materials of Examples 1 to 4 and Comparative Examples 1 to 4 was calculated by the following formula. In the formula, X represents “total amount of compounding ingredients to be charged into Banbury mixer”, and Y represents “weight of discharged unvulcanized kneaded product”.
(Residual ratio in kneader) = (X−Y) / X × 100

(Preparation of vulcanizate and calculation of dispersion ratio of undispersed carbon black or silica)
To the unvulcanized product, sulfur and vulcanization accelerators CBS and DPG were added in the amounts shown in Table 1, respectively, and kneaded at 80 ° C. for 4 minutes using an open roll. The vulcanizates of Examples 1 to 4 and Comparative Examples 1 to 4 were prepared by vulcanization at 170 ° C. for 20 minutes.

A thin piece was produced from the obtained vulcanizate by a microtome, and undispersed carbon black or silica was observed using a transmission microscope. And the dispersion degree of carbon black or silica was calculated by the following formula.
(Dispersion degree of carbon black or silica)
= (Volume of undispersed carbon black or silica) / (total volume of blended carbon black or silica) x 100

  The results are shown in Table 1.

Claims (3)

(1) A tire comprising a step of mixing a liquid polymer having a weight average molecular weight of 1000 to 10,000, and silica and / or carbon black, and (2) a step of mixing the mixture obtained in step (1) and a rubber component. A method for producing a rubber composition for use, comprising:
The compounding amount of silica and / or carbon black in the step (1) is 40 to 80 parts by weight with respect to 100 parts by weight of the liquid polymer, and the mixing temperature in the step (1) is 30 to 170 ° C.,
The content of the liquid polymer in the tire rubber composition is 5 to 100 parts by weight with respect to 100 parts by weight of the rubber component,
The manufacturing method whose total compounding quantity of the silica and / or carbon black mix | blended by the said process (1) and the process (2) is 50-180 weight part with respect to 100 weight part of rubber components. The production method according to claim 1, wherein the silica has a BET specific surface area of 100 m ² / g or more. The process according to claim 1 or 2, wherein the step (2) is mixed by a closed mixer, and the discharge temperature is 140 to 170 ° C.