JP6909710B2 - Manufacturing method of rubber composition and manufacturing method of tire - Google Patents

Description

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

Patent Documents 1 and 2 disclose that a compound (2Z) -4-[(4-aminophenyl) amino] -4-oxo-2-sodium butenoate is added to rubber and kneaded with a Banbury mixer. ing. That is, Patent Documents 1 and 2 disclose that this compound is dispersed in rubber by dry kneading.

Japanese Unexamined Patent Publication No. 2014-95019 Japanese Unexamined Patent Publication No. 2014-95020

However, since this compound easily aggregates to form an agglomerate, it is difficult to highly disperse this compound in rubber by dry kneading.

If the agglomerates are not sufficiently broken, the fatigue resistance of the vulcanized rubber is lowered. This is because the agglomerates remaining without being broken become the starting points of cracks when the vulcanized rubber is bent and deformed.

An object of the present disclosure is to provide a method for producing a rubber composition capable of improving the fatigue resistance of a vulcanized rubber and suppressing a decrease in fatigue resistance due to aging. Another object of the present disclosure is to provide a method of manufacturing a tire.

（式（Ｉ）において、Ｒ^１およびＲ^２は、水素原子、炭素数１〜２０のアルキル基、炭素数１〜２０のアルケニル基または炭素数１〜２０のアルキニル基を示す。Ｒ^１およびＲ^２は、同一であっても異なっていてもよい。Ｍ^＋はナトリウムイオン、カリウムイオンまたはリチウムイオンを示す。） The method for producing a rubber composition in the present disclosure is a method for producing ^{a rubber composition containing carbon black in which the ratio of the nitrogen adsorption specific surface area (unit: m 2} / g) to the iodine adsorption amount (unit: mg / g) is 1.00 or more. This includes a step of adding the compound of the following formula (I) to the rubber latex to obtain the rubber latex after the addition, and a step of solidifying the rubber latex after the addition.

In (formula (I), ^{R 1} and ^{R 2} are hydrogen atom, an alkyl group having 1 to 20 carbon atoms, .R ¹ an alkenyl group or an alkynyl group having 1 to 20 carbon atoms having 1 to 20 carbon atoms and R ² may be the same or different. M ⁺ indicates sodium ion, potassium ion or lithium ion.)

The method for producing a tire in the present disclosure includes a step of vulcanizing and molding an unvulcanized tire produced from the rubber composition obtained by the method for producing a rubber composition.

（式（Ｉ）において、Ｒ^１およびＲ^２は、水素原子、炭素数１〜２０のアルキル基、炭素数１〜２０のアルケニル基または炭素数１〜２０のアルキニル基を示す。Ｒ^１およびＲ^２は、同一であっても異なっていてもよい。Ｍ^＋はナトリウムイオン、カリウムイオンまたはリチウムイオンを示す。） The method for producing the rubber composition of the embodiment in the present disclosure includes a step of adding the compound of the following formula (I) to the rubber latex to obtain the rubber latex after the addition, and a step of solidifying the rubber latex after the addition. The rubber composition contains carbon black having a specific surface area of N ₂ SA (unit: m ² / g) and a ratio of 1.00 or more to the amount of iodine adsorbed IA (unit: mg / g).

In (formula (I), ^{R 1} and ^{R 2} are hydrogen atom, an alkyl group having 1 to 20 carbon atoms, .R ¹ an alkenyl group or an alkynyl group having 1 to 20 carbon atoms having 1 to 20 carbon atoms and R ² may be the same or different. M ⁺ indicates sodium ion, potassium ion or lithium ion.)

The method for producing the rubber composition of the embodiment in the present disclosure can improve the fatigue resistance of the vulcanized rubber. The reason for this will be explained. Since the compound of the formula (I) can be dissolved in the rubber latex, it can be solidified in a state where the generation of agglomerates of the compound of the formula (I), which can be the starting point of cracks, is suppressed. Therefore, a masterbatch in which the compound of the formula (I) is highly dispersed can be obtained. Even in such a rubber composition for tires in which a compounding agent is kneaded into a masterbatch, the compound of the formula (I) can be highly dispersed. Therefore, the method for producing the rubber composition of the embodiment in the present disclosure can improve the fatigue resistance of the vulcanized rubber.

Further, the method for producing the rubber composition of the embodiment in the present disclosure can suppress a decrease in fatigue resistance of the vulcanized rubber due to aging. The reason for this will be explained. Since the compound of formula (I) is highly dispersed in the rubber composition, the compound of formula (I) can be reacted with the rubber polymer at a high level. Furthermore, since carbon black has N ₂ SA / IA of 1.00 or more and has many functional groups, it can react with many compounds of the formula (I). Therefore, the carbon black and the rubber polymer can be firmly connected by the compound of the formula (I), and the peeling of the rubber-carbon black interface, which can be the starting point of cracks, can be suppressed. Therefore, the method for producing the rubber composition of the embodiment in the present disclosure can suppress a decrease in fatigue resistance of the vulcanized rubber due to aging.

Hereinafter, the first embodiment of the present disclosure will be described.

The method for producing a tire in the first embodiment includes a step of adding a compound of formula (I) to a rubber latex to obtain a rubber latex after the addition, a step of solidifying the rubber latex after the addition to obtain a master batch, and at least a master batch. And a step of kneading the compounding agent to obtain a mixture, a step of kneading a vulcanized compounding agent into the mixture to obtain a rubber composition, and a step of vulcanizing and molding an unvulcanized tire made of the rubber composition. including.

The method for manufacturing a tire according to the first embodiment includes a step of adding a compound of the formula (I) to a rubber latex to obtain a rubber latex after the addition. In rubber latex, rubber particles are colloidally dispersed in water. The rubber latex can contain ammonia. The rubber latex is, for example, a natural rubber latex, a synthetic rubber latex, or the like. The number average molecular weight of natural rubber in natural rubber latex is, for example, 2 million or more. Synthetic rubber latex is, for example, styrene-butadiene rubber latex, butadiene rubber latex, nitrile rubber latex, chloroprene rubber latex. The dry rubber content of the rubber latex can be, for example, 10% by mass or more, and can be 20% by mass or more. The upper limit of the dry rubber content in the rubber latex is, for example, 60% by mass, 50% by mass, and the like. The amount of the compound of the formula (I) is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, still more preferably 1 part by mass or more, based on 100 parts by mass of the dried rubber content of the rubber latex. More preferably, it is 2 parts by mass or more. The amount of the compound of the formula (I) is, for example, 10 parts by mass or less with respect to 100 parts by mass of the dried rubber content of the rubber latex.

（式（Ｉ）において、Ｒ^１およびＲ^２は、水素原子、炭素数１〜２０のアルキル基、炭素数１〜２０のアルケニル基または炭素数１〜２０のアルキニル基を示す。Ｒ^１およびＲ^２は、同一であっても異なっていてもよい。Ｍ^＋はナトリウムイオン、カリウムイオンまたはリチウムイオンを示す。）
式（Ｉ）の化合物は、カップリング機能、すなわちゴムポリマーとカーボンブラックとをつなぐ機能を有する。具体的には、末端の窒素官能基がカーボンブラックと結合することが可能であり、炭素−炭素二重結合の部分がゴムポリマーと結合できると考えられる。式（Ｉ）において、Ｒ^１およびＲ^２が水素原子であることが好ましい。Ｍ^＋がナトリウムイオンであることが好ましい。式（Ｉ）化合物は、好ましくは下記式（Ｉ’）の化合物である。

The formula (I) is shown below.

In (formula (I), ^{R 1} and ^{R 2} are hydrogen atom, an alkyl group having 1 to 20 carbon atoms, .R ¹ an alkenyl group or an alkynyl group having 1 to 20 carbon atoms having 1 to 20 carbon atoms and R ² may be the same or different. M ⁺ indicates sodium ion, potassium ion or lithium ion.)
The compound of formula (I) has a coupling function, that is, a function of connecting the rubber polymer and carbon black. Specifically, it is considered that the terminal nitrogen functional group can be bonded to carbon black, and the carbon-carbon double bond portion can be bonded to the rubber polymer. In formula (I), it is preferable that ^{R 1} and R ^{2 are hydrogen atoms.} It is preferable that M ⁺ is a sodium ion. The compound of formula (I) is preferably a compound of the following formula (I').

The method for manufacturing a tire according to the first embodiment includes a step of coagulating the rubber latex after addition to obtain a masterbatch. Coagulation can occur by drying the rubber latex after addition. On the other hand, in order to cause coagulation, a coagulant may be added to the rubber latex after the addition. The coagulant is, for example, an acid. Examples of the acid include formic acid and sulfuric acid. The coagulated product obtained by coagulating the rubber latex after the addition contains water. Therefore, this step can include dehydrating and drying the coagulated product. In this step, specifically, the coagulated product can be passed between two rolls to dehydrate, dried, dried, and washed with water. Ammonia can be washed away by washing with water. By such a procedure, a masterbatch containing the rubber and the compound of the formula (I) dispersed in the rubber can be obtained.

The method for producing a tire according to the first embodiment includes at least a step of kneading a masterbatch and a compounding agent to obtain a mixture. The masterbatch may undergo a process such as kneading. Examples of the compounding agent include carbon black, zinc oxide, stearic acid, and an antiaging agent. One or more of these can be selected and kneaded with the masterbatch. In carbon black, the _{ratio of N 2} SA (unit: m ² / g) to IA (unit: mg / g) is 1.00 or more. N ₂ SA / IA is an indicator of the surface activity of carbon black. The _{higher the N 2} SA / IA, the more functional groups on the carbon black surface. The N ₂ SA / IA of carbon black is preferably 1.10 or more, more preferably 1.25 or more. The upper limit of N ₂ SA / IA is, for example, 2.0, preferably 1.5. The N ₂ SA of carbon black is preferably 100 m ² / g or more. The upper limit of N ₂ SA is, for example, 200 m ² / g, preferably 180 m ² / g, and more preferably 160 m ² / g. The IA of carbon black is preferably 50 mg / g or more, more preferably 60 mg / g or more, still more preferably 70 mg / g or more. The upper limit of IA is, for example, 150 mg / g, preferably 130 mg / g. N ₂ SA and IA are values measured according to JIS K 6217. In carbon black, the half-value width ΔDst of the Stokes mode diameter / Stokes mode diameter Dst represents the aggregate distribution. The ΔDst / Dst of carbon black is preferably 0.2 to 0.9. Dst and ΔDst can be measured by the following method. Dry carbon black is mixed with a 20% by volume ethanol aqueous solution containing a small amount of a surfactant to prepare a dispersion liquid having a carbon black concentration of 50 mg / l, which is sufficiently dispersed by ultrasonic waves. The disk centrefuge device was set to a rotation speed of 8000 rpm, 10 ml of a spin solution consisting of a 2 wt% glycerin aqueous solution was added, 1 ml of a buffer solution composed of a 20% by volume ethanol aqueous solution was injected, and further, carbon black dispersion solution 0. Add 5 ml to start centrifugal sedimentation, optically create a distribution curve of the Stokes diameter of the carbon black aggregate, set the maximum frequency of Stokes diameter in the distribution curve to Dst (nm), and set the frequency to 50% of the maximum frequency. Let ΔDst (nm) be the difference between the two large and small Stokes diameters from which is obtained. As anti-aging agents, aromatic amine anti-aging agents, amine-ketone anti-aging agents, monophenol anti-aging agents, bisphenol anti-aging agents, polyphenol anti-aging agents, dithiocarbamate anti-aging agents, thiourea anti-aging agents Anti-aging agents and the like can be mentioned. In this kneading step, other rubbers can be kneaded together with the masterbatch and the compounding agent. Examples of the rubber added to the master batch at the time of kneading include natural rubber, polyisoprene rubber, styrene-butadiene rubber, nitrile rubber, and chloroprene rubber. Kneading can be performed with a closed mixer. Banbury mixers, kneaders, etc. can be mentioned as closed mixers.

The method for producing a tire according to the first embodiment further includes a step of kneading a vulcanization-based compounding agent into the mixture to obtain a rubber composition. Examples of the vulcanization-based compounding agent include vulcanization agents such as sulfur and organic peroxides, vulcanization accelerators, vulcanization acceleration aids, and vulcanization retarders. Examples of sulfur include powdered sulfur, precipitated sulfur, insoluble sulfur, and highly dispersible sulfur. Sulfenamide-based vulcanization accelerator, thiuram-based vulcanization accelerator, thiazole-based vulcanization accelerator, thiourea-based vulcanization accelerator, guanidine-based vulcanization accelerator, dithiocarbamate-based vulcanization accelerator as vulcanization accelerators And so on.

The rubber composition comprises rubber derived from the masterbatch. The amount of rubber derived from the masterbatch can be, for example, 40% by mass or more, 60% by mass or more, and 80% by mass or more with respect to 100% by mass of rubber in the rubber composition. It can be, and it can be 100% by mass.

The rubber composition comprises a compound of formula (I). The amount of the compound of the formula (I) is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, still more preferably 1 part by mass or more, based on 100 parts by mass of the rubber in the rubber composition. More preferably, it is 2 parts by mass or more. The amount of the compound of the formula (I) is, for example, 10 parts by mass or less with respect to 100 parts by mass of the rubber in the rubber composition.

The rubber composition comprises carbon black. The amount of carbon black is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass of rubber in the rubber composition. The amount of carbon black is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, based on 100 parts by mass of rubber in the rubber composition.

_{The amount of carbon black having N 2} SA / IA of 1.00 or more is preferably 50% by mass or more, more preferably 80% by mass or more, still more preferably 80% by mass, based on 100% by mass of carbon black in the rubber composition. It is 100% by mass.

The rubber composition can further contain stearic acid, zinc oxide, anti-aging agents, sulfur, vulcanization accelerators and the like. The amount of sulfur is preferably 0.5 parts by mass to 5 parts by mass in terms of sulfur content with respect to 100 parts by mass of rubber in the rubber composition. The amount of the vulcanization accelerator is preferably 0.1 part by mass to 5 parts by mass with respect to 100 parts by mass of rubber in the rubber composition.

The rubber composition can be used in the production of tires. Specifically, it can be used for manufacturing a tire member constituting a tire, and for example, it can be used for manufacturing sidewall rubber, tread rubber, and the like.

The method for manufacturing a tire according to the first embodiment includes a step of vulcanizing and molding an unvulcanized tire made of a rubber composition. The unvulcanized tire comprises a tire member made of a rubber composition.

Examples of the present disclosure will be described below.

The raw materials and chemicals are shown below.
Natural rubber latex NR field latex manufactured by Golden Hope (dry rubber content 31.2%)
Carbon Black A "Niteron # 300IH" (N ₂ SA 120m ² / g IA 124mg / g N ₂ SA / IA 0.97) Carbon Black B "Seast 7HM" (N ₂ SA 126m ² / g) manufactured by Shin Nikka Carbon Co., Ltd. IA 120mg / g N ₂ SA / IA 1.05) Carbon Black C "VULCAN 7H" manufactured by Tokai Carbon Co., Ltd. (N ₂ SA 123m ² / g IA 118mg / g N ₂ SA / IA 1.04) Compound 1 manufactured by Cabot Co., Ltd. Sumilink 200 ”manufactured by Sumitomo Chemical Co., Ltd. (2Z) -4-[(4-aminophenyl) amino] -4-oxo-2-sodium butenoate (compound of formula (I'))
Zinc Oxide "Zinc Oxide Type 1" Mitsui Kinzoku Co., Ltd. Stearate "Lunac S-20" Kao Co., Ltd. Anti-aging agent "Antigen 6C"(N-phenyl-N'-(1,3-dimethylbutyl) -p-phenylene Diamine) Sumitomo Chemical Co., Ltd. Sulfur "5% oil-containing fine powder sulfur" Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator "Sunseller NS-G" Sanshin Chemical Industry Co., Ltd.

Preparation of Rubber A A natural rubber latex was poured thinly on a tray and dried at room temperature to obtain rubber A.

Preparation of Rubber B To 100 parts by mass of dry rubber, 3 parts by mass of Compound 1 was added to natural rubber latex, poured thinly on a tray, and dried at room temperature to obtain Rubber B.

Preparation of vulcanized rubber A compounding agent excluding sulfur and a vulcanization accelerator was added to the rubber according to Tables 1 and 2, and kneaded with a B-type Banbury mixer manufactured by Kobe Steel Co., Ltd., and the rubber mixture was discharged. The rubber mixture, sulfur and the vulcanization accelerator were kneaded with a B-type Banbury mixer to obtain unvulcanized rubber. The unvulcanized rubber was vulcanized at 150 ° C. for 30 minutes to obtain a vulcanized rubber.

Fatigue resistance of vulcanized rubber The vulcanized rubber was exposed to an environment of 90 ° C. for 24 hours for aging. A bending crack growth test was conducted using vulcanized rubber before and after aging in accordance with JIS K6260. In Table 1, the value of each example is shown by an index with the value of Comparative Example 1 as 100. In Table 2, the value of each example is shown by an index with the value of Comparative Example 3 as 100. The larger the index, the slower the crack growth rate and the better the fatigue resistance.

The fatigue resistance of the vulcanized rubber before aging in Examples 1 and 2 was superior to that of Comparative Example 1. The fatigue resistance of the vulcanized rubber after aging in Examples 1 and 2 was also superior to that of Comparative Example 1.

The decrease in fatigue resistance due to aging was smaller in the vulcanized rubbers of Examples 1 and 2 than in the vulcanized rubbers of Comparative Example 1. This is because the difference between the index of Comparative Example 1 and the index of Example 1 increases from 15 to 30 due to aging, and the difference between the index of Comparative Example 1 and the index of Example 2 increases from 16 to 28. Because it has become.

The decrease in fatigue resistance due to aging was smaller in the vulcanized rubbers of Examples 1 and 2 than in the vulcanized rubbers of Comparative Example 2. This is because the difference between the index of Comparative Example 2 and the index of Example 1 increases from 0 to 18 due to aging, and the difference between the index of Comparative Example 2 and the index of Example 2 increases from 1 to 16. Because it has become.

Claims (2)

A method for producing a rubber composition containing carbon black having a ratio of the specific surface area (unit: m ² / g) to the amount of iodine adsorbed (unit: mg / g) of 1.00 or more.
The step of adding the compound of the following formula (I) to the rubber latex and obtaining the rubber latex after the addition,
The step of coagulating the rubber latex after the addition is included.
A method for producing a rubber composition.

In (formula (I), ^{R 1} and ^{R 2} are hydrogen atom, an alkyl group having 1 to 20 carbon atoms, .R ¹ an alkenyl group or an alkynyl group having 1 to 20 carbon atoms having 1 to 20 carbon atoms and R ² may be the same or different. M ⁺ indicates sodium ion, potassium ion or lithium ion.) A method for producing a tire, which comprises a step of vulcanizing and molding an unvulcanized tire produced by the rubber composition obtained by the method for producing a rubber composition according to claim 1.