JP7200672B2 - Method for producing rubber composition for tire - Google Patents

Description

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

In rubber compositions for tires, a technique of compounding a filler such as carbon black is widely used for the purpose of improving fuel efficiency and breaking properties.

However, inorganic fillers such as carbon black and silica are highly cohesive and difficult to disperse uniformly in rubber. As a method to solve these problems, natural rubber is kneaded with a small amount of peptizer, and after performing a mastication process to moderately lower the molecular weight of natural rubber, other rubber components and reinforcing agents are added. A method of adding agents and kneading is known.

Further, in Patent Document 1, in order to improve the dispersibility of the reinforcing agent, the formula (A):
NH2NHCO _- Rn _{- CONHNH2} Formula (A)
(wherein R is selected from substituted or unsubstituted aromatic groups having 6 to 20 carbon atoms or saturated or unsaturated, linear or branched aliphatic groups having 2 to 20 carbon atoms; is a divalent hydrocarbon group with n having the value 0 or 1.)
A rubber composition containing hydrazides represented by is disclosed.

Japanese translation of PCT publication No. 2012-513517

However, excessive reduction in the molecular weight of the rubber component deteriorates workability and fuel efficiency. Moreover, further improvement in dispersibility is required for the rubber composition of Patent Document 1 as well.

The present invention solves the above-mentioned problems, and provides a rubber composition for tires with improved fuel efficiency while maintaining the processability of the unvulcanized rubber composition and the dispersibility of carbon black in the vulcanized rubber composition. It is an object of the present invention to provide a method for producing the resulting rubber composition for tires.

As a result of intensive studies, the present inventors found that, in the production of a rubber composition for tires, a mastication step of kneading a rubber component and a peptization accelerator, and the masticated rubber and carbon black obtained in the mastication step. and a base kneading step of kneading hydrazides, and an extrusion step of extruding the kneaded product obtained in the kneading step with an extruder, wherein the extruder is a cylinder, a screw, and the inner surface of the cylinder. By providing a protruding pin and providing an average of 8 to 15 protruding pins for each screw pitch as a method for producing a tire rubber composition, the processability of unvulcanized rubber and carbon in vulcanized rubber The present inventors have found that the fuel efficiency of the vulcanized rubber composition can be further improved while maintaining the dispersibility of black, and that the above problems can be solved.

That is, the present invention
[1] A kneading step including a masticating step of kneading a rubber component and a peptizing accelerator, and a base kneading step of kneading the masticated rubber, carbon black and hydrazides obtained in the masticating step, and A method for producing a rubber composition for a tire, comprising an extrusion step of extruding the kneaded product obtained in the kneading step with an extruder,
The extruder comprises a cylinder, a screw, and a pin protruding from the inner surface of the cylinder, and the number of said pins per screw pitch is 8 to 15 on average, preferably 9 to 13 on average, more preferably 10 to 12 on average. A manufacturing method in which the individual projections are provided,
[2] The hydrazide content is 0.3 to 2.5 parts by mass, preferably 0.5 to 2.0 parts by mass, and more preferably 0.7 to 1.0 parts by mass based on 100 parts by mass of the total rubber component. Forming a tire member at a stage before vulcanization of the tire rubber composition obtained by the production method according to [1] above, and [3] the production method according to [1] or [2] above, A molding step of molding a raw tire in combination with other tire members;
The present invention relates to a tire manufacturing method including a vulcanization step of vulcanizing the raw tire obtained in the molding step.

The kneading step of the present invention includes a masticating step of kneading a rubber component and a peptizing accelerator, and a base kneading step of kneading the masticated rubber obtained in the masticating step, carbon black and hydrazides; and an extrusion step of extruding the kneaded product obtained in the kneading step with an extruder, wherein the extruder comprises a cylinder, a screw, and a pin protruding from the inner surface of the cylinder. According to the production method in which an average of 8 to 15 pins are provided for each screw pitch, the resulting unvulcanized rubber composition has good processability and carbon black in the vulcanized rubber composition. While maintaining the dispersibility of the vulcanized rubber composition, the fuel efficiency of the vulcanized rubber composition can be further improved.

It is an example of the schematic of the extruder used by an extrusion process. It is an example of the schematic of an extruder, and the schematic of the circumferential surface in a pin protrusion location.

The present disclosure includes a kneading step of kneading a rubber component and a peptizer, and a base kneading step of kneading the masticated rubber, carbon black and hydrazides obtained in the masticating step. and an extrusion step of extruding the kneaded product obtained in the kneading step with an extruder, the extruder having a cylinder, a screw, and a pin protruding from the inner surface of the cylinder, and averaging the pin for each screw pitch A method for producing a tire rubber composition having 8 to 15 projections.

By adopting a mastication process in which the rubber component and peptizer (radical scavenger) are kneaded, the softening of the rubber is accelerated in a short period of time. resistance (RR)) can be improved. In addition, when the kneaded product obtained in the kneading process is kneaded with an extruder, the higher the pin density (number of pins) provided in the cylinder or the like, the more effective kneading can be achieved, so the dispersibility of carbon black is improved. be able to. However, if these attempts to improve it further go too far, recombination will be suppressed by bonding with oxygen of the carbon radicals generated at the cut and cut parts of the rubber. Resistance worsens. Here, by adding hydrazides to the masticated rubber, the oxygen concentration in the rubber during kneading is reduced, and after the rubber molecular chains are cut, the ratio of bonding with oxygen is reduced, thereby suppressing the reduction of molecular weight and rolling. It is considered that deterioration of resistance (RR) is suppressed. In other words, in the present disclosure, the effect of improving the dispersibility of carbon black by masticating the rubber component with a peptization accelerator (radical scavenger), and further optimizing the pin density of the extruder to disperse carbon black. By adding hydrazides to the masticated rubber to suppress the reduction in molecular weight, these work together to maintain good processability and good carbon black dispersibility. It is thought that a synergistic effect of an exceptional improvement in fuel efficiency can be obtained while improving.

Details of each step will be described below.

(mastication process)
In the mastication step, a rubber component having a lower viscosity (harder) than other rubber components, such as natural rubber, is generally kneaded with a peptizer to match the viscosity with other rubber components.

As natural rubber, in addition to natural rubber (NR), modified natural rubber such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), and high-purity natural rubber (HPNR) etc. are also included.

NR is not particularly limited, and those commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used.

When NR is contained, the content of NR in the total rubber component is determined according to the tire member to be used, and is not particularly limited. is more preferable, 40% by mass or more is more preferable, 50% by mass or more is particularly preferable, and 60% by mass or more is even more preferable. By setting the content of NR in the total rubber component to 30% by mass or more, there is a tendency that the effect of improving fuel efficiency according to the present disclosure is likely to be obtained. Moreover, the content of NR in the total rubber component is more preferably 100% by mass. When the content of NR in the total rubber component is 100% by mass, there is a tendency that the effect of improving fuel efficiency according to the present disclosure is particularly pronounced.

Examples of peptization accelerators include thiophenols and disulfides such as Noctizer SD manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd. and Pepta 3S manufactured by Kawaguchi Kagaku Kogyo Co., Ltd., which are conventionally used in the tire industry.

The content of the peptizer is preferably 0.03 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.08 parts by mass or more, relative to 100 parts by mass of the total rubber component. By setting the content of the peptization accelerator to 0.03 parts by mass or more, the effect of reducing the viscosity due to the addition of the peptization accelerator is sufficiently obtained, and there is concern about the deterioration of processability, and the decrease in productivity is suppressed. tend to The content of the peptizer is preferably 0.75 parts by mass or less, more preferably 0.50 parts by mass or less, and more preferably 0.30 parts by mass or less. By setting the content of the peptizer to 0.75 parts by mass or less, deterioration of the wear resistance of the rubber composition tends to be suppressed. The term "all rubber components" as used herein means not only the rubber used in the mastication process, but also the rubber components added in the base kneading process and all other rubber components contained in the rubber composition. .

The mastication step is preferably carried out at a discharge temperature of 140 to 170° C. for 1 to 5 minutes as a whole, more preferably at a discharge temperature of 150 to 180° C. for 1 to 2 minutes. The kneaded product obtained in the mastication step is preferably cooled to 80° C. or less, preferably 25 to 45° C., before being used in the subsequent steps.

(Base kneading process)
In the base kneading step, the masticated rubber obtained in the masticating step is kneaded with a rubber component, carbon black and hydrazides, if necessary.

Examples of rubber components added in the base kneading step include diene rubbers such as natural rubber, isoprene rubber (IR), butadiene rubber (BR), and styrene-butadiene rubber (SBR).

BR is not particularly limited, and examples thereof include BR having a cis content of 95% or more (high-cis BR), rare earth-based butadiene rubber synthesized using a rare earth-based catalyst (rare earth-based BR), and syndiotactic polybutadiene crystals. BR (SPB-containing BR) and modified BR that are commonly used in the tire industry can be used according to the physical properties required for the target tire member.

When BR is contained, the content of BR in the rubber component is preferably 40% by mass or more, more preferably 50% by mass or more. If the BR content is less than 40% by mass, it tends to be difficult to obtain the effect of improving wear resistance. Also, the BR content is preferably 70% by mass or less, more preferably 65% by mass or less. If the BR content exceeds 70% by mass, dry grip performance and wet grip performance tend to significantly deteriorate.

The carbon black is not particularly limited, and GPF, FEF, HAF, ISAF, SAF, and the like commonly used in the tire industry can be used, and fine particle carbon black manufactured and sold by Mitsubishi Chemical Corporation is preferably used. can be done. 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 30 m ^{2 /g or more, more preferably 70 m 2 /} g or more, from the viewpoint of weather resistance and reinforcing properties. Further, the N ₂ SA of carbon black is preferably 250 m ² /g or less, more preferably 150 m ² /g or less, from the viewpoint of fuel efficiency, dispersibility, breaking properties and durability. The N ₂ SA of carbon black in this specification is a value measured according to JIS K 6217 A method.

The content of carbon black with respect to 100 parts by mass of the rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more. By setting the content of carbon black to 3 parts by mass or more, deterioration due to ultraviolet rays and ozone tends to be prevented when used for the outer surface of a tire. Also, the content of carbon black with respect to 100 parts by mass of the rubber component is preferably 120 parts by mass or less, more preferably 90 parts by mass or less. By setting the content of carbon black to 120 parts by mass or less, fuel efficiency tends to be improved.

Hydrazides are not particularly limited as long as they have a hydrazino group (--NHNH ₂ ). Specifically, general formula (1):
Ra- _{CONHNH2 (} 1)
(Wherein, R _a is an alkyl group having 1 to 30 carbon atoms, an unsaturated hydrocarbon group having 1 to 30 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, or an aryl group having 3 to 30 carbon atoms. indicates.)
A compound represented by the general formula (2):
NH2NHCO- _Rb - _CONHNH2 ( ₂ )
(Wherein, R _b is a divalent alkane having 1 to 30 carbon atoms, a divalent unsaturated hydrocarbon group having 1 to 30 carbon atoms, a divalent cycloalkane having 3 to 30 carbon atoms, a divalent carbon represents any of the aryls of numbers 3 to 30.)
The compound represented by is mentioned.

Specific examples of the compound represented by the general formula (1) include acetohydrazide, propionic hydrazide, butyl hydrazide, lauric hydrazide, palmitic hydrazide, stearic hydrazide, cyclopropyl hydrazide, cyclohexyl hydrazide, cycloheptyl hydrazide, benzoylhydrazine, benzoic acid hydrazide, salicylic acid hydrazide, o-, m- or p-tolylhydrazide, p-methoxyphenylhydrazide, 3,5-xylylhydrazide, 1-naphthylhydrazide and the like, preferably benzoylhydrazine, the above Specific examples of the compound represented by formula (2) include adipic acid dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, salicylic acid dihydrazide, dodecanediohydrazide and the like, and adipic acid dihydrazide is preferred.

The content of hydrazides relative to 100 parts by mass of the rubber component is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.7 parts by mass or more. By setting the content of hydrazides to 0.3 parts by mass or more, there is a tendency that the effect of improving fuel efficiency according to the present disclosure is likely to be obtained. Also, the content of hydrazides relative to 100 parts by mass of the rubber component is preferably 2.5 parts by mass or less, more preferably 2.0 parts by mass or less, and even more preferably 1.0 parts by mass or less. By setting the hydrazide content to 2.5 parts by mass or less, the effect of improving fuel efficiency while maintaining good processability and carbon black dispersibility tends to be more likely to be obtained. be.

The base kneading step is preferably performed at a discharge temperature of 130 to 160° C. for 1 to 5 minutes, more preferably at a discharge temperature of 150 to 180° C. for 1 to 3 minutes. The kneaded product obtained in the base kneading step is preferably cooled to 80° C. or lower, preferably 25 to 45° C., before being used in subsequent steps.

Another kneading step (base kneading step 2) may be performed between the base kneading step and the finish kneading step. The base kneading step 2 can be performed under the same conditions as the base kneading step by adding other compounding agents to the kneaded product obtained in the base kneading step. The kneaded product obtained in can be used in the base kneading step 2 without special cooling, and the kneaded product obtained in the base kneading step 2 is usually cooled to 80 ° C. or less, preferably to 25 to 45 ° C. It is preferable to use it in the subsequent steps.

(Finish kneading process)
In the finishing kneading step, a vulcanizing agent is added to the kneaded material obtained in the base kneading step and kneaded. The kneading method in the finishing kneading step is not particularly limited, and for example, a known kneader such as an open roll can be used.

The vulcanizing agent is not particularly limited, and those commonly used in the tire industry can be used, but those containing sulfur atoms are preferred, such as powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur and the like.

Vulcanization accelerators are not particularly limited, but examples include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine or aldehyde-ammonia, and imidazoline. and xanthate-based vulcanization accelerators. Among them, sulfenamide-based, thiuram-based, and guanidine-based vulcanization accelerators are preferable because the effects of the present disclosure can be obtained more suitably.

Sulfenamide vulcanization accelerators include CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (Nt-butyl-2-benzothiazylsulfenamide), N-oxyethylene- 2-benzothiazylsulfenamide, N,N'-diisopropyl-2-benzothiazylsulfenamide, N,N-dicyclohexyl-2-benzothiazylsulfenamide and the like. Thiazole vulcanization accelerators include 2-mercaptobenzothiazole and dibenzothiazolyl disulfide. Thiuram-based vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD). Guanidine-based vulcanization accelerators include diphenylguanidine (DPG), dioltolylguanidine, orthotolylbiguanidine, and the like. These may be used alone or in combination of two or more. Among them, CBS and TBBS are preferable because the effects of the present disclosure can be obtained more suitably.

In the finishing kneading step, it is preferable to discharge when the rubber temperature reaches 90 to 130°C, more preferably when the rubber temperature reaches 100 to 120°C.

(Extrusion process)
In the extrusion step, the kneaded product obtained in the finishing kneading step is extruded into a sheet. In the extrusion step, an extruder is provided with a cylinder, a screw, and a pin protruding from the inner surface of the cylinder (a pin attached to protrude from the inner surface of the cylinder), and the average number of pins per screw pitch is within a predetermined range. The kneaded material is extruded using

FIG. 1 is a schematic diagram of an example of an extruder used in the extrusion process. The extruder 1 shown in FIGS. 1(a) and 1(c) includes a cylinder 11, a screw 12, and a pin 13 protruding from the inner surface of the cylinder 11. FIG. It is a form that is not The screw 12 has a helical flight 121 around the shaft and is installed by being inserted into the cylinder 11 . Since the pins 13 in FIGS. 1(a) and 1(c) protrude into the material conveying space in the cylinder 11, the flight 121 is provided with a notch 122 to prevent interference with the pins 13. ing.

FIG. 2 shows an example of a schematic diagram of an extruder and a schematic diagram of a circumferential surface at a pin projecting position. The left figure of FIG. 2 shows a form having a pin 13 and a notch 122, as in FIGS. 1(a) and 1(c). Right figures (i), (ii), and (iii) show modes in which 6, 8, and 10 pins 13 protrude in the notch 122, respectively. Among them, a configuration in which 6 to 8 pins 13 protrude from the notch 122 is preferable.

The extruder 1 has an average of 8 to 15 pins 13 protruding for each screw pitch P, and from the viewpoint of carbon black dispersibility, a form in which an average of 9 to 13 protruding pins is preferable, and an average of 10 to 12 protruding pins. It is more preferable to have a The screw pitch P, as shown in FIGS. 1 and 2, is the distance (lead) that the screw 12 advances in the axial direction when the screw 12 rotates 360 degrees.

For example, in the case of the extruder 1 in FIG. 1 (a) (number of rows of pins per screw pitch P: 1 row) and FIG. 2 (iii) (number of pins 13 in the circumference: 10), the screw pitch The average number of pins 13 for each P is 10 (=1 row×10). In the case of the extruder 1 of FIG. 1(c) (number of rows of pins per screw pitch P: 1.5 rows) and FIG. 2(ii) (number of pins 13 in the circumference: 8), the screw pitch The average number of pins 13 for each P is 12 (=1.5 rows×8).

It is desirable that the pins 13 protrude uniformly for each screw pitch P. For example, as shown in FIGS. It is preferred that the portions 122) be evenly distributed in the axial direction of the screw. In addition, it is preferable that the number of each circumferential pin 13 installed in each notch 122 is the same in each notch 122 (a set of each circumferential pin 13).

In the extrusion process, the kneaded material supplied from the material supply unit (not shown) of the extruder 1 is sequentially moved by the rotation of the screw 12 in the kneading chamber in which a predetermined number of pins 13 in the cylinder 11 protrude. It is kneaded by 13 and screw 12, is plasticized, is injected into a mold of an injection nozzle (not shown) at the tip, and is molded into a sheet.

(Vulcanization process)
The kneaded material (unvulcanized rubber composition) produced in the extrusion process described above is usually vulcanized thereafter. For example, an unvulcanized rubber composition is extruded according to the shape of a tire member such as a tread, molded by a normal method on a tire building machine, and laminated with other tire members to form an unvulcanized tire. After forming, a tire can be manufactured by heating and pressurizing in a vulcanizer. The vulcanization temperature is preferably 130-200°C, more preferably 150-180°C. The vulcanization time is preferably 5 to 20 minutes, more preferably 10 to 15 minutes.

In addition, in the method for producing a rubber composition for tires of the present disclosure, in addition to the above components, compounding agents generally used in the conventional tire industry, such as reinforcing fillers other than carbon black, processing aids, stearic acid , various anti-aging agents, softening agents such as oils and adhesive resins, waxes, zinc oxide, etc. can be appropriately added and kneaded. The timing of injection is not particularly limited.

As reinforcing fillers other than carbon black, silica, calcium carbonate, alumina, clay, talc, and other fillers conventionally used in rubber compositions for tires can be blended.

Adding silica can improve fuel economy, wear resistance, and wet grip performance. Silica is not particularly limited. For example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), etc. Common ones in the tire industry can be used. can be done. Among them, hydrous silica prepared by a wet method is preferable because it contains many silanol groups. Silica may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 40 m ² /g or more, more preferably 80 m ² /g or more. Also, N ₂ SA is preferably 250 m ² /g or less, more preferably 200 m ² /g or less. Within the above range, fuel efficiency and workability tend to be obtained in a well-balanced manner. The N ₂ SA of silica in this specification is a value measured by the BET method according to ASTM D3037-81.

When silica is added, the content of silica is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 30 parts by mass or more relative to 100 parts by mass of the rubber component. A silica content of 3 parts by mass or more tends to improve the balance between wet grip performance and fuel economy performance. In addition, the content of silica relative to 100 parts by mass of the rubber component is preferably 150 parts by mass or less, more preferably 90 parts by mass or less. By setting the content of silica to 150 parts by mass or less, there is a tendency that good workability is likely to be obtained.

The oil is not particularly limited, and for example, process oil, vegetable oil or a mixture thereof can be used. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, etc. can be used. Among them, mineral oil is preferable from the viewpoint of good tire performance at low temperatures. These may be used alone or in combination of two or more.

When the oil is contained, the content relative to 100 parts by mass of the total rubber component is preferably 4 parts by mass or more, more preferably 6 parts by mass or more. By setting the oil content to 4 parts by mass or more, there is a tendency to obtain good low-temperature properties such as keeping soft hardness at low temperatures. The oil content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less. By setting the oil content to 15 parts by mass or less, the vulcanized rubber tends to have good tensile strength, good low heat build-up, and good processability.

The wax is not particularly limited, but paraffin waxes such as Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. and OK5258H manufactured by Paramelt are preferred.

When the paraffin wax is contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more. Moreover, 2.0 mass parts or less are preferable and 1.5 mass parts or less are more preferable.

As the anti-aging agent, amine-based, phenol-based, imidazole-based compounds, and anti-aging agents such as metal carbamates can be appropriately selected and blended. These anti-aging agents can be used alone. may be used, or two or more may be used in combination. Among them, amine anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine is more preferred because they can remarkably improve ozone resistance and have excellent destruction properties. .

The content of the anti-aging agent with respect to 100 parts by mass of the total rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more. If the content of the anti-aging agent is less than 0.5 parts by mass, there is a tendency that sufficient ozone resistance cannot be obtained and that it is difficult to improve the destruction property. Moreover, the content of the antioxidant is preferably 6 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 4 parts by mass or less. When the content of the antioxidant exceeds 6 parts by mass, discoloration tends to occur.

The tackifying resin can be used as necessary, such as when the tackiness of the compounded rubber is insufficient. Examples of adhesive resins include resins conventionally used in rubber compositions for tires, such as aromatic petroleum resins. Examples of aromatic petroleum resins include phenolic resins, coumarone-indene resins, terpene resins, styrene resins, acrylic resins, rosin resins, and dicyclopentadiene resins (DCPD resins). Examples of phenol-based resins include Cholecin (manufactured by BASF) and Tackyroll (manufactured by Taoka Chemical Industry Co., Ltd.). Examples of the coumarone-indene resin include knit resin cumarone (manufactured by Nichinuri Chemical Co., Ltd.), Esclone (manufactured by Nippon Steel Chemical Co., Ltd.), and neopolymer (manufactured by Nippon Petrochemical Co., Ltd.). Styrene resins include, for example, Sylvatraxx (registered trademark) 4401 (manufactured by Arizona Chemical Co.). Examples of terpene resins include TR7125 (manufactured by Arizona Chemical Co.) and TO125 (manufactured by Yasuhara Chemical Co.).

When an adhesive resin is used, there is no particular lower limit to the content of the adhesive resin per 100 parts by mass of the rubber component, but it is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more. By setting the content of the adhesive resin to 0.5 parts by mass or more, there is a tendency that good grip performance is likely to be obtained. The content of the adhesive resin with respect to 100 parts by mass of the rubber component is preferably 10 parts by mass or less, more preferably 6 parts by mass or less. By setting the content of the adhesive resin to 10 parts by mass or less, there is a tendency to easily obtain good fuel economy and wear resistance, and there is a tendency to obtain effects commensurate with the cost.

In addition, as zinc oxide and stearic acid, those conventionally used in the tire industry can be used.

For kneading in each step of the method for producing a rubber composition for tires of the present disclosure, a known kneader can be used. and mixing equipment.

Since the rubber composition obtained by the method for producing a rubber composition for tires of the present disclosure is excellent in rubber physical properties such as processability and fuel efficiency, it can be used in various tire components (for example, cap tread, base tread, sidewall, carcass). , clinch, bead, etc.).

<Tire Manufacturing Method>
The tire manufacturing method of the present disclosure forms a tire member (for example, a cap tread or a base tread) at a stage before vulcanization of the tire rubber composition manufactured by the manufacturing method of the present disclosure, and other tires. It includes a molding step of molding a raw tire in combination with a tire member, and a vulcanization step of vulcanizing the raw tire obtained in the molding step. The vulcanization temperature is, for example, 130-200°C.

These tires may be pneumatic tires or non-pneumatic tires, but pneumatic tires are preferred. In addition, as pneumatic tires, it can be used for various tires such as tires for passenger cars, tires for trucks and buses, tires for motorcycles, high-performance tires such as racing tires, and run-flat tires. , can be used as a studless tire.

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited only to these examples.

Various chemicals used in Examples and Comparative Examples are listed below.
・NR: TSR20
・ BR: BR150B manufactured by Ube Industries, Ltd.
・Mastication accelerator: Noctizer SD manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Carbon black (1): Show Black N134 (N ₂ SA: 147 m ² /g) manufactured by Cabot Japan Co., Ltd.
Carbon black (2): Diablack (registered trademark) LH (N326, N ₂ SA: 83 m ² /g) manufactured by Mitsubishi Chemical Corporation
・ Hydrazide compound (1): Tokyo Kasei Kogyo Co., Ltd. adipic acid dihydrazide hydrazide compound (2): Tokyo Kasei Kogyo Co., Ltd. benzoyl hydrazine ・ Wax: Nippon Seiro Co., Ltd. Ozoace 0355 (paraffin system)
· Anti-aging agent: Nocrack 6C (6PPD: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
・Stearic acid: Tsubaki beads stearate manufactured by NOF Corporation ・Oil: VivaTec400 (TDAE oil) manufactured by H&R Co., Ltd.
・Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. ・Vulcanization accelerator (1): Noccellar NS (Nt-butyl-2-benzothiazylsulfur manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) phenamide)
- Vulcanization accelerator (2): Noxcellar CZ (CBS, N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
・Sulfur: powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

Examples and Comparative Examples (1) Mastication Step Using a Banbury mixer, the rubber component was masticated according to the formulation shown in Tables 1 and 2 at a discharge temperature of 150° C. for 1.5 minutes to obtain a masticated rubber.
(2) Base kneading step To the masticated rubber (approximately 35°C) obtained in the masticating step of (1), the compounding ingredients described in the items of the base kneading step are added according to the compounding contents shown in Tables 1 and 2, Using a Banbury mixer, the mixture was kneaded at a discharge temperature of 150° C. for 2.5 minutes to obtain a kneaded product.
(3) Finish kneading step Using an open roll, the kneaded product (about 35 ° C.) obtained in the base kneading step (2) is added to the kneaded product (about 35 ° C.) according to the formulation shown in Tables 1 and 2, as described in the item of the finish kneading step. The ingredients were added and kneaded and discharged when the rubber temperature reached about 110°C.
(4) Extrusion step The kneaded product obtained in the finish kneading step of (3) is extruded by the extruder shown in FIGS. 1 (a) to (c) and FIG. A flat sheet was extruded at a temperature of 75° C. at a screw speed of 25 RPM and an extrusion speed of about 25 m/min to obtain an unvulcanized rubber composition. The specifications of the extruder used in each example and comparative example are as described in each table.
(5) Vulcanization step The unvulcanized rubber composition obtained in the extrusion step (4) was press-vulcanized at 170°C for 10 minutes in a 2 mm thick mold to obtain a vulcanized rubber composition.

The unvulcanized rubber compositions and vulcanized rubber compositions obtained in Examples and Comparative Examples were evaluated as follows. Results are shown in Tables 1 and 2. Comparative Example 3 is the standard formulation for Examples 1 to 5 and Comparative Examples 1 to 8, and Comparative Example 9 is the standard formulation for Examples 6 to 8 and Comparative Examples 9 to 11.

<Processability index (Mooney viscosity)>
The obtained unvulcanized rubber composition was measured at 130° C. according to the method for measuring Mooney viscosity according to JIS K 6300. The value of the standard formulation is set to 100 and indexed. The larger the index, the lower the viscosity and the better the workability. The target value is 89 or higher.

<Carbon black dispersion index>
Using an RPA2000 manufactured by Alpha Technology Co., Ltd., the strain dependence of the storage elastic modulus of the vulcanized rubber composition was measured under the conditions of a measurement temperature of 110° C. (1 minute of preheating), a frequency of 6 cpm, and an amplitude of 0.28 to 10%. , The value of the storage elastic modulus with a strain of 0.2% / (the value of the storage elastic modulus with a strain of 0.2% - the value of the storage elastic modulus with a strain of 64%) is obtained, and the value of the standard blend is 100 indexed as A higher index indicates better dispersion of carbon black.

<RR index>
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), the loss tangent (tan δ) of the vulcanized rubber composition was measured under the conditions of a temperature of 30 ° C., a frequency of 10 Hz, an initial strain of 10% and a dynamic strain of 2%. was measured and indexed with 100 as the standard formulation. A larger index indicates lower rolling resistance and better fuel efficiency. For Examples 1 to 5, the target value is 120 or more, and for Examples 6 to 8, the target value is 110 or more, preferably 114 or more.

From Tables 1 and 2, the examples in which the peptizer was kneaded in the mastication process, the hydrazides were kneaded into the masticated rubber together with carbon black in the base kneading process, and the pin density of the extruder was adjusted were Good processability was maintained, carbon black dispersibility was improved, and fuel efficiency was remarkably improved.

1 Extruder 11 Cylinder 12 Screw 13 Pin 121 Flight 122 Notch P Screw Pitch

Claims (6)

A kneading step including a kneading step of kneading a rubber component and a peptizer, and a base kneading step of kneading the masticated rubber, carbon black and hydrazides obtained in the masticating step, and the kneading step. A method for producing a rubber composition for a tire, comprising an extrusion step of extruding the kneaded product obtained in the above with an extruder,
A manufacturing method, wherein the extruder comprises a cylinder, a screw, and a pin projecting from the inner surface of the cylinder, and an average of 8 to 15 of the pins projecting from each screw pitch. The production method according to claim 1, wherein the hydrazide content is 0.3 to 2.5 parts by mass with respect to 100 parts by mass of the total rubber component. The production method according to claim 1, wherein the hydrazide content is 0.7 to 2.5 parts by mass with respect to 100 parts by mass of the total rubber component. The production method according to any one of claims 1 to 3, wherein the rubber component in the mastication step contains natural rubber. The production method according to any one of claims 1 to 4, wherein the extruder has an average of 8 to 12 pins protruding for each screw pitch. A tire member is molded at a stage before vulcanization of the tire rubber composition obtained by the production method according to any one of claims 1 to 5, and a raw tire is molded by combining with other tire members. molding process;
and a vulcanization step of vulcanizing the raw tire obtained in the molding step.

Images