JP6702433B2 - Method for producing rubber composition for tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a rubber composition for a tire, which is excellent in wet grip performance, low rolling resistance and wear resistance.

BACKGROUND ART Conventionally, a pneumatic tire has been required to have excellent wet grip performance to enhance safety, to reduce rolling resistance to enhance fuel efficiency, and to have high abrasion resistance to prolong life. However, it is difficult to make these properties compatible because these properties conflict with each other. For example, in order to improve wet grip performance and low rolling property, it is known to blend silica into a rubber composition for tires to modify dynamic viscoelastic properties. However, when silica is blended, there is a problem that abrasion resistance is lower than when carbon black is blended.

Silane coupling for improving the dispersibility of silica in a diene rubber in order to improve the wear resistance of a rubber composition containing silica and to further improve wet grip performance and low rolling resistance. It is known to use a silica compounded with an agent or subjected to surface treatment in advance. Further, Patent Documents 1 and 2 propose to improve the dispersibility of silica by sequentially adding and/or separately kneading the constituent components of the rubber composition. However, the use of surface-treated silica, and the sequential addition and/or divisional kneading increase the number of steps and increase the production cost.

Japanese Patent Laid-Open No. 2016-151018 Japanese Patent Laid-Open No. 2016-169268

An object of the present invention is to provide a method for producing a rubber composition for a tire, which is excellent in wet grip performance, low rolling resistance and abrasion resistance.

In the method for producing a rubber composition for a tire of the present invention which achieves the above object, 80 to 180 parts by mass of silica is mixed with 100 parts by mass of a diene rubber, and a silane coupling agent is mixed with 5 to 18% by mass based on the amount of silica. The method for producing a rubber composition as described above, wherein the silica and the silane coupling agent are added in the mixer in the first amount and mixed, and then the diene rubber is added in the second amount and kneaded. And

According to the production method of the present invention, after the total amount of silica and silane coupling agent is charged into a mixer and mixed, a diene rubber is added and kneaded, so that the silica and silane coupling agent are easily contacted. Along with lowering the mixer temperature and adding the diene rubber, it is possible to improve the dispersibility of silica by applying a high shearing force, wet grip performance, low rolling resistance and abrasion resistance. An excellent rubber composition for tires can be obtained.

In the production method of the present invention, carbon black and/or aroma oil can be added and mixed together with silica and a silane coupling agent. Further, carbon black and/or aromatic oil and/or a dispersant for silica can be added and mixed together with the silica and the silane coupling agent. The dispersant for silica is preferably at least one selected from amine compounds, silane compounds, epoxy compounds, and guanidine compounds. The silica and silane coupling agent can be mixed in a mixer at 20 to 90°C. The CTAB specific surface area of silica is preferably 150 to 300 m ² /g. Further, 30% by mass or more of the modified diene rubber may be contained in 100% by mass of the diene rubber.

Generally, a method for producing a rubber composition for a tire includes a kneading step of mixing and kneading a diene rubber, silica, a silane coupling agent, carbon black, an aroma oil, and a compounding agent excluding a vulcanizing compounding agent (the first step). At least two steps are included: a one-step mixing step) and a step of cooling the mixture obtained in this kneading step and then mixing the vulcanizing compounding agent (final step mixing step). The method for producing a rubber composition for a tire according to the present invention comprises a step of first adding all the amounts of silica and a silane coupling agent to a mixer and mixing them in the kneading step (mixing step of the first step) described above. After the second charging/mixing step, the diene rubber is charged and kneaded in a mixer containing silica and a silane coupling agent, and the second charging/mixing step is performed at least in two steps.

The production method of the present invention starts the first-stage mixing step by performing the step of first adding all the amounts of silica and the silane coupling agent to a mixer and mixing them. This makes it easier for the silica and the silane coupling agent to come into contact with each other, and the silane coupling agent acts on the silica more effectively. As a result, it is possible to reduce the number of steps and the production cost as compared with the case where the surface treatment of silica is conventionally performed in another step. Further, by mixing the silica and the silane coupling agent first, the temperature of the mixer is lowered, the temperature when the diene rubber is then kneaded is lowered, and the kneading strength in the mixer is further increased to improve the dispersibility of silica. You can do better. In the conventional first step of mixing, in which the diene rubber is first charged into the mixer and kneaded, and then various compounding agents are added and kneaded, the temperature in the mixer increases due to the kneading of the diene rubber and Since the viscosity decreases, high shearing force cannot be applied when silica is added and kneaded afterwards, so that silica cannot be dispersed well.

The amount of silica and the silane coupling agent to be added to the mixer is 5 to 18% by mass, preferably 6 to 15% by mass, based on the amount of silica. Dispersion of silica can be improved by adjusting the amount of the silane coupling agent to be 5% by mass or more of the amount of silica. Further, by setting the amount of the silane coupling agent to be 18% by mass or less of the amount of silica, it is possible to suppress the condensation between the silane coupling agents and obtain a rubber composition having desired hardness and strength.

The silica and the silane coupling agent can be mixed with each other by using a mixer which is usually used for producing a rubber composition for tires. The type of the rotor that constitutes the mixer may be a meshing type or a non-meshing type. The rotation speed of the rotor can be set to a normal rotation speed when manufacturing the rubber composition for tires.

In the present invention, the temperature at which the silica and the silane coupling agent are mixed can be preferably 20 to 90°C, more preferably 30 to 70°C. In particular, by setting the upper limit temperature at the time of mixing to 70° C., the shearing force can be increased and the dispersibility of silica can be improved by performing the step of adding and kneading the diene rubber after this step. ..

The time for mixing the silica and the silane coupling agent can be preferably 5 seconds to 2 minutes, more preferably 20 seconds to 90 seconds. By setting the mixing time to 20 seconds or more, the silica and the silane coupling agent can be mixed and brought into sufficient contact with each other. Further, by setting the mixing time to 90 seconds or less, it is possible to suppress the decrease in productivity.

In the production method of the present invention, carbon black and/or aroma oil can be added and mixed together with silica and a silane coupling agent, whereby rolling resistance can be further reduced and abrasion resistance can be further increased. Carbon black and aroma oil may be added to the mixer simultaneously with the silica and silane coupling agent. The mixing conditions when the carbon black and the aroma oil are added can be the same as above.

In the present invention, the diene rubber is charged and kneaded in the mixer after mixing the silica and the silane coupling agent. The diene rubber can be added to the mixer within the range of usual charging conditions. The conditions for kneading the silica and the silane coupling agent and the diene rubber can also be carried out within the usual range.

The compounding agents to be compounded in the tire rubber composition, excluding the vulcanizing compounding agent, may be added and kneaded at the same time as the diene rubber, or may be added and mixed after the kneading of the diene rubber. As compounding agents excluding vulcanizing compounding agents, various additives generally used in tire rubber compositions such as anti-aging agents, plasticizers, processing aids, liquid polymers, terpene resins, thermosetting resins, etc. The agent can be exemplified. These compounding agents can be used in the conventional general compounding amounts as long as they do not violate the object of the present invention. For example, a filler other than silica such as carbon black is added and kneaded at the same time as the diene rubber is added, and so-called rubber drugs such as zinc oxide, stearic acid and an antioxidant are added and kneaded at the same time as the diene rubber is added. Alternatively, or after the kneading of the diene rubber is finished, aroma oil may be added and mixed.

In the present invention, a diene rubber, silica, a silane coupling agent, carbon black, aroma oil, and a compounding agent other than a vulcanizing compounding agent are mixed and kneaded (after the mixing step of the first step), The obtained mixture is cooled, and the step of mixing the vulcanizing compounding agent (final stage mixing step) is performed. Examples of the vulcanizing compounding agent include vulcanizing or crosslinking agents, vulcanization accelerators, vulcanization retarders, and the like. The method of mixing the vulcanizing compounding agent can be carried out in the same manner as in the usual method for producing a rubber composition for tires. Before the final mixing step, the mixture obtained in the first mixing step may be further kneaded in the second mixing step or the third mixing step. In the second-stage mixing step, the kneaded product is taken out from the mixer of the first-step mixing step, cooled if necessary, and put into the same mixer or another mixer for mixing. The mixing step of the third step is to mix the mixture obtained in the mixing step of the second step in the same manner as above. In the mixing step of the second step and/or the mixing step of the third step, the mixture obtained in the mixing step of each preceding step may be added and mixed as it is, or a compounding agent is additionally added to the mixture. You may mix by mixing.

The rubber composition for tires manufactured by the present invention is obtained by mixing 80 to 180 parts by mass of silica with 100 parts by mass of a diene rubber and 5 to 18% by mass of a silane coupling agent with respect to the amount of silica.

The diene rubber is not particularly limited as long as it is usually used in a rubber composition for tires, and for example, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, styrene-isoprene rubber, styrene-isoprene- Examples thereof include butadiene rubber and acrylonitrile-butadiene rubber. Of these, natural rubber, butadiene rubber, and styrene-butadiene rubber are preferable.

These diene rubbers may be diene rubbers in which the ends and/or side chains of their molecular chains are modified with a functional group having a hetero atom. Heteroatoms include oxygen, nitrogen, silicon, and sulfur islands. Further, as a functional group, an epoxy group, a carboxy group, an amino group, a hydroxy group, an alkoxy group, a silyl group, an amide group, an oxysilyl group, a silanol group, an isocyanate group, an isothiocyanate group, a carbonyl group, an aldehyde group, etc. The modified diene rubber may be used.

As the modified diene rubber, for example, epoxy group modified natural rubber, epoxy group modified isoprene rubber, amino group modified styrene-butadiene rubber, hydroxy group modified styrene-butadiene rubber, silyl group modified styrene-butadiene rubber, oxysilyl group modified styrene- Examples thereof include butadiene rubber, silanol group-modified styrene-butadiene rubber, imino group-modified styrene-butadiene rubber, carboxyl group-modified styrene-butadiene rubber, tin group-modified styrene-butadiene rubber, and epoxy group-modified styrene-butadiene rubber. ..

The modified diene rubber may be contained in 100 mass% of the diene rubber, preferably 30 mass% or more, and more preferably 35 mass% or more. The modified diene rubber may be contained in an amount of 100% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less. When the content of the modified diene rubber is 30% by mass or more, the dispersibility of silica can be further improved, and wet grip performance, low rolling resistance and abrasion resistance can be further improved. ..

Examples of silica include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. These may be used alone or in combination of two or more. Further, surface-treated silica whose surface is treated with a silane coupling agent may be used.

The CTAB adsorption specific surface area of silica is not particularly limited, but is preferably 150 to 300 m ² /g, more preferably 160 to 260 m ² /g. By setting the CTAB adsorption specific surface area of silica to 150 m ² /g or more, abrasion resistance of the rubber composition can be secured. By setting the CTAB adsorption specific surface area of silica to 300 m ² /g or less, wet grip performance and low rolling resistance can be improved. In this specification, the CTAB specific surface area of silica is a value measured according to ISO 5794.

Silica is added in an amount of 80 to 180 parts by mass, preferably 90 to 160 parts by mass, based on 100 parts by mass of the diene rubber. By adjusting the amount of silica to be 80 parts by mass or more, wet grip performance and low rolling resistance can be improved. Further, by setting the amount of silica to be 180 parts by mass or less, abrasion resistance can be ensured.

The silane coupling agent is not particularly limited as long as it can be used in the silica-containing rubber composition, and examples thereof include a sulfur-containing silane coupling agent and an amino group-containing silane coupling agent. .. Further, a silane coupling agent represented by the formula (1) described below and a polysiloxane represented by the average composition formula of the formula (2) can be preferably used. Examples of the silane coupling agent include bis-(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, 3-trimethoxysilylpropylbenzothiazoletetrasulfide, γ-mercaptopropyltriethoxy. Silane, sulfur-containing silane coupling agents such as 3-octanoylthiopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyl Dimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxy Examples of the amino group-containing silane coupling agent include silane and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride.

In the production method of the present invention, a silane coupling agent represented by the following formula (1) can be preferably used.
_{(C p H 2p + 1)} t (C p H 2p + 1 O) 3-t -SiC q H 2q -S-C (O) -C r H 2r + 1 ··· (1)
(In the formula (1), p represents an integer of 1 to 3, q represents an integer of 1 to 3, r represents an integer of 1 to 15, and t represents an integer of 0 to 2.)

In the above formula (1), p is 2 to 3 in that the affinity with silica is high, the workability of the rubber composition for tires is good, and the dispersibility of silica in the rubber composition for tires is good. It is preferable that it is 2 and it is more preferable that it is 2. For the same reason, q is preferably 2 to 3, and more preferably 3. r is preferably 5 to 10, more preferably 6 to 9, and even more preferably 7 from the viewpoint that the scorch time at the time of kneading the rubber composition for a tire will be good. t represents an integer of 0 to 2, is preferably 0 or 1, and is more preferably 0. Such a silane coupling agent can be produced by a known method, and examples thereof include the method described in WO 99/09036. Examples of commercially available products include NXT silane manufactured by Momentive.

The sulfur-containing silane coupling agent is preferably a mercapto group-containing silane coupling agent, and more preferably a polysiloxane represented by the following average composition formula (2).
(A) _a (B) _b (C) _c (D) _d (R ¹ ) _e SiO _{(4-2a-b-c-d-e)/2} (2)
(In the formula, A contains a divalent organic group represented by the following formula (3), B contains a monovalent hydrocarbon group having 5 to 20 carbon atoms, C contains a hydrolyzable group, and D contains a mercapto group. An organic group, R ¹ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms, a to e are 0≦a<1, 0<b<1, 0<c<3, 0<d<1, It is a real number that satisfies the relational expressions of 0≦e<2 and 0<2a+b+c+d+e<4.
_{* - (CH 2) n -Sx-} (CH 2) n - * ··· (3)
(In the above formula (3), n represents an integer of 1 to 10, x represents an integer of 1 to 6, and * represents a bonding position.)

The polysiloxane (mercaptosilane compound) having the average composition formula represented by the general formula (2) has a siloxane skeleton as its skeleton. The siloxane skeleton can have a linear, branched, or three-dimensional structure, or a combination thereof.

In the general formula (2), at least one of a and b is not 0. That is, at least one of a and b may be greater than 0, and both a and b may be greater than 0. Therefore, this polysiloxane always contains at least one selected from a divalent organic group A containing a sulfide group and a monovalent hydrocarbon group B having 5 to 10 carbon atoms.

When the silane coupling agent composed of the polysiloxane having the average composition formula represented by the above general formula (2) has a monovalent hydrocarbon group B having 5 to 10 carbon atoms, it protects the mercapto group and Mooney scorch time. It has a long working time, and at the same time, has excellent affinity with rubber, which makes it more processable. Therefore, the subscript b of the hydrocarbon group B in the general formula (2) is preferably 0.10≦b≦0.89. Specific examples of the hydrocarbon group B include monovalent hydrocarbon groups having preferably 6 to 10 carbon atoms, more preferably 8 to 10 carbon atoms, such as hexyl group, octyl group and decyl group. This makes it possible to protect the mercapto group, lengthen the Mooney scorch time, improve workability, and further improve low heat buildup.

When the silane coupling agent composed of the polysiloxane having the average composition formula represented by the above general formula (2) has the divalent organic group A containing a sulfide group, it has low heat generation property and processability (especially Mooney Scorch). To maintain and prolong time). Therefore, the subscript a of the divalent organic group A containing a sulfide group in the general formula (5) is preferably 0<a≦0.50.

In the general formula (3), the divalent organic group A containing a sulfide group represents an integer of 1 to 10, and preferably an integer of 2 to 4 among them. In addition, x represents an integer of 1 to 6, and is preferably an integer of 2 to 4 among them. The organic group A can be a hydrocarbon group which may have a hetero atom such as an oxygen atom, a nitrogen atom or a sulfur atom.

Specific examples of the group represented by the general formula (3), for _{example, * - CH 2 -S 2 -CH} 2 - *, * - C 2 H 4 -S 2 -C 2 H 4 - *, * _{-C 3 H 6 -S 2 -C 3} H 6 - *, * - C 4 H 8 -S 2 -C 4 H 8 - *, * - CH 2 -S 4 -CH 2 - *, * - C 2 _{H 4 -S 4 -C 2 H 4} - *, * - C 3 H 6 -S 4 -C 3 H 6 - *, * - C 4 H 8 -S 4 -C 4 H 8 - * , and the like ..

The silane coupling agent composed of polysiloxane having the average composition formula represented by the above general formula (2) has a hydrolyzable group C, and thereby has excellent affinity and/or reactivity with silica. To do. The subscript c of the hydrolyzable group C in the general formula (2) is 1.2≦c≦2.0 for the reason that the heat generation property is better, the processability is better, and the dispersibility of silica is better. Good. Specific examples of the hydrolyzable group C include, for example, an alkoxy group, a phenoxy group, a carboxyl group, an alkenyloxy group and the like. The hydrolyzable group C is preferably a group represented by the following general formula (4) from the viewpoint of improving the dispersibility of silica and further improving the processability.
*-OR ² ...(4)
In the general formula (4), * indicates a bonding position. R ² represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group (arylalkyl group) having 6 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms. It is preferably an alkyl group having 1 to 5 carbon atoms.

Specific examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a decyl group and an octadecyl group. Specific examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a tolyl group. Specific examples of the aralkyl group having 6 to 10 carbon atoms include benzyl group and phenylethyl group. Specific examples of the alkenyl group having 2 to 10 carbon atoms include vinyl group, propenyl group, pentenyl group and the like.

The silane coupling agent composed of polysiloxane having the average composition formula represented by the above general formula (2) has an organic group D containing a mercapto group, and thus interacts and/or reacts with a diene rubber. And excellent low heat build-up. The subscript d of the organic group D containing a mercapto group is preferably 0.1≦d≦0.8. The organic group D containing a mercapto group is preferably a group represented by the following general formula (5) from the viewpoint of improving the dispersibility of silica and further improving the processability.
_{* - (CH 2) m -SH} ··· (5)
In the general formula (5), m represents an integer of 1 to 10, and preferably an integer of 1 to 5. Further, in the formula, * indicates a bonding position.

Specific examples of the group represented by the general formula _{(5), * - CH 2} SH, * - C 2 H 4 SH, * - C 3 H 6 SH, * - C 4 H 8 SH, * - C _{5 H 10 SH, * - C} 6 H 12 SH, * - C 7 H 14 SH, * - C 8 H 16 SH, * - C 9 H 18 SH, * - C 10 H 20 SH and the like.

In the general formula (2), R ¹ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms. Examples of the hydrocarbon group R ¹ include a methyl group, an ethyl group, a propyl group and a butyl group.

The content of the silane coupling agent is 5 to 18% by mass, preferably 6 to 15% by mass, based on the mass of silica. Dispersion of silica can be improved by adjusting the amount of the silane coupling agent to be 5% by mass or more of the amount of silica. Further, by setting the amount of the silane coupling agent to be 18% by mass or less of the amount of silica, it is possible to suppress the condensation between the silane coupling agents and obtain a rubber composition having desired hardness and strength.

The rubber composition for tires manufactured by the present invention may be blended with carbon black and/or aroma oil together with silica and a silane coupling agent.

Examples of the carbon black include furnace carbon blacks such as SAF, ISAF, HAF, FEF, GPF, HMF, and SRF, and these may be used alone or in combination of two or more kinds. The nitrogen adsorption specific surface area of carbon black is not particularly limited, but is preferably 70 to 240 m ² /g, more preferably 90 to ²⁰⁰ m ² /g. By setting the nitrogen adsorption specific surface area of carbon black to 70 m ² /g or more, the mechanical properties and abrasion resistance of the rubber composition can be secured. By setting the nitrogen adsorption specific surface area of carbon black to 240 m ² /g or less, low rolling resistance can be improved. In the present specification, the nitrogen adsorption specific surface area of carbon black is to be measured according to JIS K6217-2.

The carbon black can be blended in an amount of preferably 5 to 100 parts by mass, and more preferably 10 to 80 parts by mass with respect to 100 parts by mass of the diene rubber. By setting the blending amount of carbon black to 5 parts by mass or more, the mechanical properties and abrasion resistance of the rubber composition can be secured. By setting the amount of carbon black to be 100 parts by mass or less, low rolling resistance can be ensured.

The rubber composition for tires may contain a filler other than silica and carbon black. Other fillers include calcium carbonate, magnesium carbonate, talc, clay, alumina, aluminum hydroxide, titanium oxide and calcium sulfate. You may use these individually or in combination of 2 or more types.

As the aroma oil, for example, one having a mass percentage of aromatic hydrocarbons of 15% by mass or more, which is determined in accordance with ASTM D2140, is preferably used. That is, the molecular structure thereof may contain aromatic hydrocarbons, paraffin hydrocarbons, and naphthene hydrocarbons, and the aromatic hydrocarbon content is preferably 15% by mass or more, and 17% by mass. The above is more preferable. The content ratio of aromatic hydrocarbons in the aromatic oil is preferably 70% by mass or less, more preferably 65% by mass or less.

Commercially available aroma oils include, for example, Showa Shell Sekiyu's Extract No. 4S, Idemitsu Kosan's AC-12, AC-460, AH-16, AH-24, AH-58, and Japan Energy's. Process NC300S, process X-140, etc. are mentioned.

In the rubber composition for tires, the blending amount of the aromatic oil is preferably 3 to 50 parts by mass, and more preferably 5 to 40 parts by mass with respect to 100 parts by mass of the diene rubber. By setting the blending amount of the aroma oil to 3 parts by mass or more, low rolling resistance can be secured. In addition, abrasion resistance can be secured by adjusting the amount of aroma oil to be 50 parts by mass or less.

The tire rubber composition produced in the present invention may be blended with a silica and a silane coupling agent together with a silica dispersant. Examples of the silica dispersant include amine compounds, silane compounds, epoxy compounds, guanidine compounds, and the like. It is preferable to use at least one selected from amine compounds, silane compounds, and guanidine compounds.

Examples of amine compounds include cyclic amine compounds. Of these, cyclic amine compounds are preferable.
Preferred cyclic amine compounds include piperidine derivatives, piperazine derivatives, morpholine derivatives, thiomorpholine derivatives, and the like. Among them, a piperazine derivative, a morpholine derivative, and a thiomorpholine derivative are more preferable. The cyclic amine compound does not have to have a silicon atom and an enamine structure (NC=C).

The piperazine derivative, morpholine derivative and thiomorpholine derivative are respectively bonded to the piperazine ring, morpholine ring and thiomorpholine ring and the carbon atom or nitrogen atom forming the ring, directly or through another organic group. It is preferable that the structure has a hydrocarbon group having 3 to 30 carbon atoms. Other organic groups include divalent hydrocarbon groups containing oxygen such as carbonyl groups, oxyalkylene groups, and polyoxyalkylene groups.

Examples of the hydrocarbon group having 3 to 30 carbon atoms include an aliphatic hydrocarbon group (including linear, branched, and cyclic), an aromatic hydrocarbon group, and a combination thereof. Among them, an aliphatic hydrocarbon group is preferable, and a saturated aliphatic hydrocarbon group is more preferable, from the viewpoint of more excellent processability. Further, a hydrocarbon group having 8 to 22 carbon atoms is preferable from the viewpoint of being more excellent in processability. The hydrocarbon group having 3 to 30 carbon atoms is preferably composed only of carbon atoms and hydrogen atoms. Further, the hydrocarbon group having 3 to 30 carbon atoms is preferably monovalent. One molecule of the cyclic amine compound may have one or more hydrocarbon groups having 3 to 30 carbon atoms, and preferably one or two hydrocarbon groups.

式（Ｉ）中、Ｘ_３、Ｘ_４、Ｘ_５、Ｘ_６は、互いに独立に、水素原子または炭素数３〜３０の一価の炭化水素基であり、Ｘ_１、Ｘ_２は、互いに独立に、水素原子、−Ａ^１−Ｒ^２、−Ｒ^２、−（Ｒ^３−０）ｎ−Ｈ、スルホン系保護基、カルバメート系保護基からなる群から選ばれる１つであり、Ｘ_１、Ｘ_２の少なくとも１つは、−Ａ^１−Ｒ^２または−Ｒ^２である。−Ｒ^２は、炭素数３〜３０の１価の炭化水素基であり、Ａ^１は、カルボニル基または−Ｒ^４（ＯＨ）−Ｏ−である。Ｒ^３は、炭素数２〜３の２価の炭化水素基、Ｒ^４は、炭素数３〜３０の３価の炭化水素基である。ｎは１〜１０、好ましくは１〜５の数である。上記式（Ｉ）において炭素数３〜３０の１価の炭化水素基は、直鎖状、分岐状または環状の脂肪族炭化水素基が好ましい。The piperazine derivative can be preferably represented by the following formula (I).

In formula (I), X ₃ , X ₄ , X ₅ , and X ₆ are each independently a hydrogen atom or a monovalent hydrocarbon group having 3 to 30 carbon atoms, and X ₁ and X ₂ are independently of each other. represent hydrogen ^{atom, -A 1 -R 2, -R 2} , - (R 3 -0) n-H, sulfone protecting group is one selected from the group consisting of carbamate protecting _{groups, X} 1, At least one of X ₂ is -A ¹ -R ² or -R ² . —R ² is a monovalent hydrocarbon group having 3 to 30 carbon atoms, and A ¹ is a carbonyl group or —R ⁴ (OH)—O—. R ³ is a divalent hydrocarbon group having 2 to 3 carbon atoms, and R ⁴ is a trivalent hydrocarbon group having 3 to 30 carbon atoms. n is a number of 1 to 10, preferably 1 to 5. In the above formula (I), the monovalent hydrocarbon group having 3 to 30 carbon atoms is preferably a linear, branched or cyclic aliphatic hydrocarbon group.

In the above formula (I), examples of the sulfone-based protecting group include a methanesulfonyl group, a tosyl group and a nosyl group. Further, examples of the carbamate-based protecting group include a tert-butoxycarbonyl group, an allyloxycarbonyl group, a benzyloxycarbonyl group and a 9-fluorenylmethyloxycarbonyl group.

上記式中、Ｒは、互いに独立に−Ｃ_１２Ｈ_２５または−Ｃ_１３Ｈ_２７を表す。Examples of the piperazine derivative include compounds represented by the following formula.

Herein, R represents _-C 12 _{H 25} or _-C 13 _{H 27} independently of one another.

上記式中、ｎは、２〜１０、好ましくは２〜５の数である。

In the above formula, n is a number of 2 to 10, preferably 2 to 5.

上記式中、Ｒは、−Ｃ_１２Ｈ_２５または−Ｃ_１３Ｈ_２７を表し、これらピペラジン系誘導体の混合物でもよい。

Herein, R _{represents -C} 12 _{H 25} or _-C 13 _{H 27,} may be a mixture of these piperazines derivatives.

式（ＩＩ）中、Ｘ_３、Ｘ_４、Ｘ_５、Ｘ_６は、互いに独立に、水素原子または炭素数３〜３０の１価の炭化水素基であり、Ｘ_１は、−Ａ^１−Ｒ^２または−Ｒ^２であり、Ｘ_７は酸素原子または硫黄原子である。−Ｒ^２は、炭素数３〜３０の１価の炭化水素基であり、Ａ^１は、カルボニル基または−Ｒ^４（ＯＨ）−Ｏ−であり、Ｒ^４は、炭素数３〜３０の３価の炭化水素基である。上記式（ＩＩ）において炭素数３〜３０の１価の炭化水素基は、直鎖状、分岐状または環状の脂肪族炭化水素基が好ましい。The morpholine-based derivative and the thiomorpholine-based derivative can be preferably represented by the following formula (II).

Wherein _{(II), X 3, X} 4, X 5, X 6 are each independently a monovalent hydrocarbon group hydrogen atom or a C3-30, _{X 1} is, ^-A 1 -R ² or -R ^2, _{X 7} is an oxygen atom or a sulfur atom. —R ² is a monovalent hydrocarbon group having 3 to 30 carbon atoms, A ¹ is a carbonyl group or —R ⁴ (OH)—O—, and R ⁴ is 3 having 3 to 30 carbon atoms. It is a valent hydrocarbon group. In the above formula (II), the monovalent hydrocarbon group having 3 to 30 carbon atoms is preferably a linear, branched or cyclic aliphatic hydrocarbon group.

上記式中、Ｒは、−Ｃ_１２Ｈ_２５または−Ｃ_１３Ｈ_２７を表し、これらモルホリン系誘導体の混合物でもよい。Examples of morpholine derivatives include compounds represented by the following formula.

Herein, R _{represents -C} 12 _{H 25} or _-C 13 _{H 27,} may be a mixture of these morpholine derivatives.

Examples of the thiomorpholine derivative include compounds in which the oxygen atom in the ring of the above morpholine derivative is replaced with a sulfur atom.

The method for producing the cyclic amine compound including the above-mentioned piperazine derivative, morpholine derivative, and thiomorpholine derivative is not particularly limited and can be obtained by a usual production method. For example, at least one selected from the group consisting of piperazine, morpholine, and thiomorpholine which may have a substituent, a halogen atom (chlorine, bromine, iodine, etc.), an acid halogen group (acid chloride group, acid bromide group). , An acid iodide group, etc.) and a glycidyloxy group, and a hydrocarbon compound having at least one selected from the group consisting of 3 to 30 carbon atoms, if necessary, in a solvent. You can The substituents are the same as above. The hydrocarbon group having 3 to 30 carbon atoms in the above hydrocarbon compound is the same as above. As a method for producing the piperazine-based derivative having a (poly)oxyalkyl group, for example, a method of reacting a piperazine-based derivative having a hydroxy group with an alkylene oxide in the presence of a metal alkoxide can be mentioned.

In the rubber composition for tires, the amount of the cyclic amine compound compounded is preferably 0.5 parts by mass or more, more preferably 0.5 to 10 parts by mass, and further preferably 0.8 parts by mass with respect to 100 parts by mass of the diene rubber. ~5 parts by mass is preferable. By adjusting the amount of the cyclic amine compound to be 0.5 parts by mass or more, rolling resistance of the tire can be reduced and wet grip performance can be improved.

Examples of the silane-based compound include alkylalkoxysilane, and examples thereof include monoalkyltrialkoxysilane, dialkyldialkoxysilane, and trialkylmonoalkoxysilane. Among them, alkyltrialkoxysilane is preferable, and alkyltriethoxysilane is more preferable. By compounding the alkylalkoxysilane, aggregation of silica and increase in viscosity of the rubber composition can be suppressed, and the wet grip performance can be further improved.

The alkyltriethoxysilane preferably has an alkyl group having 3 to 20 carbon atoms, and more preferably an alkyl group having 7 to 20 carbon atoms. As the alkyl group having 3 to 20 carbon atoms, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group. Group, heptadecyl group, octadecyl group, nonadecyl group, and icosyl group. Among them, an alkyl group having 8 to 10 carbon atoms is more preferable, and an octyl group and a nonyl group are further preferable, from the viewpoint of compatibility with a diene rubber.

The amount of alkyltriethoxysilane compounded is preferably 0.5 to 10% by mass, more preferably 2 to 6% by mass, based on the amount of silica compounded. If the compounding amount of alkyltriethoxysilane is less than 0.5% by mass, the effect of suppressing the aggregation of silica and the effect of suppressing the increase in the viscosity of the rubber composition cannot be sufficiently obtained. Further, if the amount of the alkyltriethoxysilane compounded exceeds 10% by mass, the amount of stagnation on the roll during preparation of the rubber composition increases. In addition, the rolling resistance of the rubber composition is increased, and the abrasion resistance may be reduced.

The rubber composition for a tire of the present invention is a rubber composition for a tire such as a vulcanizing or crosslinking agent, a vulcanization accelerator, an antioxidant, a plasticizer, a processing aid, a liquid polymer, a terpene resin, and a thermosetting resin. Various additives commonly used in the above can be added within a range that does not impair the object of the present invention. Further, such an additive can be kneaded by a general method into a rubber composition, which can be used for vulcanization or crosslinking. The amounts of these additives to be compounded can be conventional general amounts, as long as they do not violate the object of the present invention.

Hereinafter, the present invention will be further described with reference to examples, but the scope of the present invention is not limited to these examples.

For the rubber compositions 1 to 6 having the formulations shown in Table 3, the rubber compositions for tires were manufactured by different manufacturing methods. The rubber compositions prepared in the following examples and comparative examples have the corresponding rubber composition formulations of Table 3 shown in the "Rubber Composition Formulations" column of Tables 1 and 2. The compounding amount of the rubber composition in Table 3 is shown in the compounding amount based on 100 parts by mass of the diene rubber (SBR and/or modified SBR). It was described whether it was put. In the first-stage mixing, the total amount of each component described in the column of “First-stage mixing” in Table 3 was added to a mixer (a closed-type Banbury mixer with a capacity of 1.7 liters, manufactured by Kobe Steel) in Tables 1 and 2. In the order of "first charging", "second charging", and "third charging" shown in (1), kneading was performed to obtain a kneaded product, which was discharged from the mixer and cooled. After cooling, the kneaded product was again charged into the mixer, and the respective components described in the column of “final stage mixing” in Table 3 were added and mixed to prepare a rubber composition by 14 kinds of production methods ( Examples 1 to 10, standard examples, and comparative examples 1 to 3).

With the temperature control of the Banbury mixer set at 60° C., the mixing of the various raw materials is started at room temperature (23° C.). In the mixing in the first stage, as mixing conditions, the mixing time of the first added component, the temperature after completion of the mixing, and the initial mixing temperature of the second added component are shown in Tables 1 and 2. The mixing time of the second and third components added was each 1 minute. The kneaded product obtained by the first-stage mixing was cooled to 23° C. outside the machine by air cooling, and after mixing with the vulcanizing agent, the mixing was performed for 1.5 minutes with a Banbury mixer.

The obtained rubber composition for tires was vulcanized at 170° C. for 10 minutes using a mold having a predetermined shape (internal dimensions; length 150 mm, width 150 mm, thickness 2 mm) to prepare a vulcanized rubber test piece. .. Using the obtained vulcanized rubber test piece, the wet performance, rolling resistance and abrasion resistance were measured by the following test methods.

Wet performance and rolling resistance [tan δ at 0°C and 60°C]
The dynamic viscoelasticity of the obtained vulcanized rubber test piece was measured using a viscoelasticity spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. under the conditions of elongation deformation strain rate 10±2%, frequency 20 Hz, temperature 0° C. and 60° C. And tan δ (0°C) and tan δ (60°C) were determined. The obtained results are shown in the columns of "wet performance" and "rolling resistance" in Tables 1 and 2 as indexes for setting the value of the standard example to 100. The larger the wet performance index, the larger the tan δ (0° C.) and the better the wet grip performance. Further, the smaller the rolling resistance index, the smaller the tan δ (60° C.) and the lower heat generation, which means that the rolling resistance when the tire is made is small.

Abrasion resistance The obtained vulcanized rubber test piece was used in accordance with JIS K6264 using a Lambourn abrasion tester (manufactured by Iwamoto Seisakusho) at a temperature of 20°C, a load of 39N, a slip ratio of 30%, and a time of 4 minutes. The amount of wear was measured under the conditions. The obtained results are shown in the "wear resistance" column of Tables 1 and 2 as an index with the reciprocal of the standard example being 100. The larger this index, the better the abrasion resistance.

In Table 3, the types of raw materials used are as follows.
SBR: Styrene butadiene rubber (unmodified product), Nipol 1502 manufactured by Nippon Zeon Co., Ltd.
-Modified SBR: styrene-butadiene rubber modified with an epoxy group, Nipol NS616 manufactured by Nippon Zeon Co., Ltd.
Silica: Rhodia 200MP, CTAB adsorption specific surface area is 203m ² /g
Surface-treated silica: Rhodia 200MP, Evonik Degussa Si69 surface-treated silica 10% by mass relative to silica. Silane coupling agent 1: sulfide-based silane coupling agent, Evonik Degussa Si69, bis (tri (Ethoxysilylpropyl)tetrasulfide/silane coupling agent 2: NXT silane manufactured by Momentive Co., represented by the following formula.
_{(CH 3 CH 2 O) 3} -Si-C 3 H 6 -S-C (O) -C 6 H 12 CH 3
Alkyltriethoxysilane: Octyltriethoxysilane, Shin-Etsu Chemical Co., Ltd. KBE-3083
・Carbon black: Show black N339 made by Cabot Japan
・Aroma oil: Showa Shell Sekiyu's extract No. 4 S
Zinc oxide: 3 types of zinc oxide manufactured by Shodo Chemical Co., Ltd.-Stearic acid: stearic acid manufactured by NOF CORPORATION Anti-aging agent 1: Santoflex 6PPD manufactured by Solutia Europe
-Anti-aging agent 2: PILNOX TDQ manufactured by Nocil Limited
・Sulfur: Fine sulphur containing Tanami Chemical Co., Ltd. gold flower oil (sulfur content 95.24% by mass)
・Vulcanization accelerator-1: Ouchi Shinko Chemical Co., Ltd. Nox Cellar CZ-G (CZ)
・Vulcanization accelerator-2: Sumitomo Chemical Co., Ltd. Sokushinol DG (DPG)

As is clear from Tables 1 and 2, the rubber compositions obtained by the production methods of Examples 1 to 10 had wet grip performance (tan δ at 0° C.), low rolling resistance (tan δ at 60° C.) and abrasion resistance. Was confirmed to be improved.

In the rubber composition obtained in Comparative Example 1, surface-treated silica was blended in place of the silica in the standard example, but the rolling resistance could not be improved by the first temperature rise due to the temperature rise of the mixer.
In the rubber composition obtained in Comparative Example 2, a modified SBR was blended in place of the SBR in the standard example, but the balance of low rolling resistance and wet performance due to the temperature increase of the mixer at the time of the first charging was found in Example 1. It is inferior to the rubber composition obtained in Nos. 5 to 5.
The rubber composition obtained in Comparative Example 3 had the first addition to the mixer in the first-stage mixing and the only mixing was silica, and the silane coupling agent was not added first. The ring agent does not react sufficiently to improve wet performance and abrasion resistance.

Claims (7)

A method for producing a rubber composition, wherein 100 to 100 parts by mass of a diene rubber is mixed with 80 to 180 parts by mass of silica, and 5 to 18% by mass of a silane coupling agent is mixed with respect to the amount of silica. A method for producing a rubber composition for a tire, characterized in that the total amount of the ring agent is added first and mixed, and then the total amount of the diene rubber is added second and kneaded. The method for producing a tire rubber composition according to claim 1, wherein carbon black and/or aroma oil is added and mixed together with the silica and the silane coupling agent. The method for producing a rubber composition for a tire according to claim 1, wherein carbon black and/or aromatic oil and/or a dispersant for silica are added and mixed together with the silica and the silane coupling agent. The method for producing a rubber composition for a tire according to claim 3, wherein the silica dispersant is at least one selected from an amine compound, a silane compound, an epoxy compound, and a guanidine compound. The method for producing a rubber composition for a tire according to any one of claims 1 to 4, wherein the silica and the silane coupling agent are mixed in the mixer at 20 to 90°C. The method for producing a rubber composition for a tire according to claim 1, wherein the CTAB specific surface area of the silica is 150 to 300 m ² /g. Method for producing a diene rubber in 100% by mass, tire rubber composition according to any one of claims 1 to 6, characterized in that it contains modified diene rubber least 30 mass%.