JP7127340B2 - Method for producing rubber composition for tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a tire rubber composition having excellent wet grip properties and durability.

Conventionally, pneumatic tires are required to have excellent wet grip performance and durability (especially, chip and cut resistance) in order to improve safety. However, these characteristics are contradictory, and it is difficult to make them compatible. For example, in order to improve wet grip performance, it is known to blend silica into rubber compositions for tires to modify dynamic viscoelastic properties. However, when silica is blended, there is a problem that good durability cannot be obtained as compared with when the same amount of carbon black is blended.

Silane coupling to improve the dispersibility of silica in diene rubber in order to improve the wear resistance of rubber compositions containing silica, and to improve wet grip performance and low rolling resistance. It is known to mix an agent or to use silica which has been subjected to surface treatment in advance. Further, Patent Literatures 1 and 2 propose improving 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 or the sequential addition and/or divided kneading increases the number of man-hours and raises the production cost.

JP 2016-151018 A JP 2016-169268 A

An object of the present invention is to provide a method for producing a rubber composition for tires having excellent wet grip performance and durability.

The method for producing a rubber composition for tires according to the present invention, which achieves the above objects, comprises blending 100 parts by mass of diene rubber with silica, carbon black, and aromatic oil, and adding the amount of silica to the total amount of silica and carbon black. A method for producing a rubber composition in which the amount is 10% to 60% by mass and a silane coupling agent is blended in an amount of 5% to 18% by mass with respect to the amount of silica, wherein a mixer contains the silica, the silane coupling agent, The carbon black and the aromatic oil are added together and mixed, and then the diene rubber is added and kneaded.

According to the production method of the present invention, the silica, the silane coupling agent, and the aromatic oil are all added to the mixer and mixed, and then the diene rubber is added and kneaded. In addition to making it easier to contact, the temperature of the mixer is lowered and after the diene rubber is added, a high shearing force is applied to further improve the dispersibility of silica. It is possible to obtain a rubber composition for tires having excellent chip cutability). In addition, a pneumatic tire using this rubber composition for tires can satisfactorily exhibit these performances due to the excellent wet performance and durability of the rubber composition for tires.

In the production method of the present invention, the total amount of silica and carbon black is preferably 40 to 180 parts by mass with respect to 100 parts by mass of diene rubber. Furthermore, it is preferable that 10 parts by mass or more of silica is contained with respect to 100 parts by mass of the diene rubber.

In general, the method of manufacturing a rubber composition for tires includes a kneading step (Second one-step mixing step) and a step of cooling the mixture obtained in this kneading step and then mixing the vulcanization compounding agent (final-step mixing step). In the method for producing a rubber composition for tires of the present invention, the above-described kneading step (mixing step of the first stage) is performed. First, the silica, the silane coupling agent, and the aroma oil are put into a mixer and mixed. and at least two steps consisting of a second charging/mixing step of charging and kneading the diene rubber in a mixer containing silica, a silane coupling agent, and an aromatic oil after the first charging/mixing step. It is characterized by comprising:

In the manufacturing method of the present invention, the mixing process of the first stage is started by first charging the silica, the silane coupling agent, and the aromatic oil into a mixer and mixing them. This makes it easier for silica and the silane coupling agent to come into contact with each other, and the silane coupling agent acts more effectively on silica. As a result, the number of man-hours can be reduced and the production cost can be reduced as compared with the conventional case where the surface treatment of silica is performed in a separate process. Also, by first mixing silica, silane coupling agent, and aromatic oil, the temperature of the mixer is lowered, and then the temperature when kneading the diene rubber is lowered to increase the kneading strength in the mixer. better dispersibility. In the conventional first-stage mixing process, in which the diene rubber is first put into a mixer and kneaded, and then various compounding agents are put in and kneaded, the kneading of the diene rubber raises the temperature inside the mixer, Since the viscosity is lowered, a high shearing force cannot be applied when silica is subsequently added and kneaded, and silica cannot be dispersed satisfactorily.

The amount of silica and silane coupling agent added to the mixer is such that the silane coupling agent is 5% by mass to 18% by mass, preferably 6% by mass to 15% by mass, relative to the amount of silica. Silica dispersion can be improved by setting the compounding amount of the silane coupling agent to 5% by mass or more of the amount of silica. Also, by setting the compounding amount of the silane coupling agent to 18% by mass or less of the amount of silica, condensation between the silane coupling agents can be suppressed, and a rubber composition having desired hardness and strength can be obtained.

Silica, the silane coupling agent, and the aromatic oil can be mixed using a mixer that is commonly used to produce rubber compositions for tires. Further, the type of the rotor that constitutes the mixer may be either an intermeshing type or a non-meshing type. The number of rotations of the rotor can be set to a normal number of rotations when producing a rubber composition for tires.

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

The time for mixing silica, silane coupling agent and aromatic oil is preferably 5 seconds to 2 minutes, more preferably 20 seconds to 90 seconds. By setting the mixing time to 20 seconds or longer, the silica and the silane coupling agent can be mixed and sufficiently brought into contact with each other. A decrease in productivity can be suppressed by setting the mixing time to 90 seconds or less.

In the production method of the present invention, carbon black can be added and mixed together with silica, a silane coupling agent, and an aromatic oil, so that wet grip properties can be improved and durability can be increased. Carbon black is preferably added to the mixer at the same time as silica and the silane coupling agent. Also, the mixing conditions when the carbon black is added can be the same as above.

In the present invention, the diene rubber is put into the mixer after mixing the silica, the silane coupling agent, and the aromatic oil, and kneaded. Carbon black can also be added and kneaded at this stage, ie, together with the diene rubber, without being added together with the silica, silane coupling agent, and aromatic oil as described above. The injection of the diene rubber into the mixer can be carried out within the range of normal injection conditions. Further, the conditions for kneading the silica, silane coupling agent, and aromatic oil with the diene rubber can also be carried out within the usual range.

Compounding agents other than vulcanization compounding agents to be compounded in the rubber composition for tires may be added and kneaded at the same time as the diene rubber, or may be added and mixed after kneading the diene rubber. Compounding agents other than vulcanization compounding agents include anti-aging agents, plasticizers, processing aids, liquid polymers, terpene-based resins, thermosetting resins, and other additives commonly used in tire rubber compositions. agents can be exemplified. These compounding agents can be used in conventional general compounding amounts as long as they do not contradict 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, or a so-called rubber agent such as zinc oxide, stearic acid, anti-aging agent is added and kneaded at the same time as the diene rubber is added. Alternatively, the aroma oil may be added and mixed after kneading the diene rubber.

In the present invention, after the kneading step (first stage mixing step) of mixing and kneading compounding agents other than diene rubber, silica, silane coupling agent, carbon black, aromatic oil, and vulcanizing compounding agents, The obtained mixture is cooled, and the step of mixing the vulcanization compounding agent (the final mixing step) is carried out. Examples of vulcanization compounding agents include vulcanization or cross-linking agents, vulcanization accelerators, vulcanization retarders, and the like. The method of mixing the vulcanization compounding agent can be carried out in the same manner as in the production of a normal rubber composition for tires. In addition, before the final stage mixing process, the mixture obtained in the first stage mixing process may be further kneaded in a second stage mixing process or a third stage mixing process. In the second-stage mixing process, the kneaded material is taken out from the mixer used in the first-stage mixing process, cooled if necessary, put into the same mixer or another mixer, and mixed. In the third mixing step, the mixture obtained in the second mixing step is mixed in the same manner as described above. In the second-stage mixing step and/or the third-stage mixing step, the mixture obtained in the respective previous mixing steps may be added and mixed as it is, or the compounding agent may be added to the mixture. may be mixed together.

In the rubber composition for tires produced in the present invention, when silica and carbon black are blended with 100 parts by mass of diene rubber, the amount of silica is 10% by mass to 60% by mass of the total amount of silica and carbon black, and silane A coupling agent is blended in an amount of 5% by mass to 18% by mass based on the amount of silica.

The diene rubber is not particularly limited as long as it is usually used in rubber compositions for tires. Examples include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, styrene-isoprene rubber, styrene-isoprene butadiene rubber, acrylonitrile-butadiene rubber, and the like. Of these, natural rubber, butadiene rubber, and styrene-butadiene rubber are preferred.

These diene-based rubbers may be diene-based rubbers whose molecular chain ends and/or side chains have been modified with functional groups having heteroatoms. Heteroatoms include oxygen, nitrogen, silicon, and iwo Jima. In addition, functional groups such as epoxy group, carboxyl group, amino group, hydroxy group, alkoxy group, silyl group, amide group, oxysilyl group, silanol group, isocyanate group, isothiocyanate group, carbonyl group, aldehyde group, etc. modified diene rubber may be used.

Modified diene rubbers include, 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 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, epoxy group-modified styrene-butadiene rubber, and the like. .

The modified diene rubber is preferably contained in an amount of 30% by mass or more, more preferably 35% by mass or more, based on 100% by mass of the diene rubber. The modified diene rubber should be contained in an amount of 100% by mass or less, preferably 95% by mass or less, and more preferably 90% by mass or less. By setting the content of the modified diene rubber to 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, aluminum silicate, etc. These may be used alone or in combination of two or more. Alternatively, surface-treated silica obtained by treating the surface of silica with a silane coupling agent may be used.

Although the CTAB adsorption specific surface area of silica is not particularly limited, it is preferably 150 m ² /g to 300 m ² /g, more preferably 160 m ² /g to 260 m ² /g. By setting the CTAB adsorption specific surface area of silica to 150 m ² /g or more, the wear resistance of the rubber composition can be ensured. 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 blended in an amount of 10% by mass to 60% by mass, preferably 20% by mass to 50% by mass, based on a total of 100% by mass of carbon black and silica. Wet grip performance and low rolling resistance can be improved by setting the compounding amount of silica to 10% by mass or more based on the total amount of carbon black and silica. Further, by setting the compounding amount of silica to 60% by mass or less with respect to the total amount of carbon black and silica, durability (resistance to chipping and cutting) can be ensured. The total amount of silica and carbon black is preferably 40 to 180 parts by mass, more preferably 50 to 120 parts by mass, per 100 parts by mass of the diene rubber. The amount of silica compounded is preferably 10 parts by mass or more, more preferably 20 to 50 parts by mass, per 100 parts by mass of the diene rubber.

The silane coupling agent is not particularly limited as long as it can be used in a silica-blended rubber composition, and examples include sulfur-containing silane coupling agents, amino group-containing silane coupling agents, and the like. . Also, a silane coupling agent represented by the formula (1) described later and a polysiloxane represented by the average composition formula of the formula (2) can be preferably used. Silane coupling agents such as 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 include amino group-containing silane coupling agents such as silane, hydrochloride of N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, and the like.

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) _3-7 —SiC _q H _2q —S—C(O)—C _r H _2r+1 (1)
(In formula (1), p is an integer of 1 to 3, q is an integer of 1 to 3, r is an integer of 1 to 15, and t is an integer of 0 to 2.)

In the above formula (1), p is 2 to 3 in terms of high affinity with silica, good processability of the rubber composition for tires, and good dispersibility of silica in the rubber composition for tires. One is preferred, and two is more preferred. For the same reason, q is preferably 2 to 3, more preferably 3. r is preferably from 5 to 10, more preferably from 6 to 9, and even more preferably 7, from the viewpoint of improving the scorch time during kneading of the tire rubber composition. t represents an integer of 0 to 2, preferably 0 or 1, more preferably 0. Such a silane coupling agent can be produced by a known method, such as the method described in International Publication No. 99/09036. Examples of commercially available products include NXT silane from Momentive.

The sulfur-containing silane coupling agent is preferably a silane coupling agent having a mercapto group, and more preferably polysiloxane represented by the following average composition formula (2).
(A) _a (B) _b (C) _c (D) _d (R ¹ ) _e SiO _{(4-2a-bcde)/2} (2)
(Wherein, A is a divalent organic group represented by the following formula (3), B is a monovalent hydrocarbon group having 5 to 20 carbon atoms, C is a hydrolyzable group, and D is a mercapto group. an organic group, R1 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, 0 It is a real number that satisfies the relational expressions ≦e<2 and 0<2a+b+c+d+e<4.
*-( _CH2 ) _n - _Sx- ( _CH2 ) _n- * (3)
(In the above formula (3), n is an integer of 1 to 10, x is an integer of 1 to 6, and * indicates a bonding position.)

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

In general formula (2) above, at least one of a and b is not zero. That is, at least one of a and b may be greater than zero, and both a and b may be greater than zero. Therefore, this polysiloxane necessarily 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 made of polysiloxane having the average compositional formula represented by the above general formula (2) has a monovalent hydrocarbon group B having 5 to 10 carbon atoms, the mercapto group is protected and the Mooney scorch time is At the same time as the length increases, the affinity with rubber improves the workability. Therefore, the subscript b of the hydrocarbon group B in general formula (2) is preferably 0.10≦b≦0.89. Specific examples of the hydrocarbon group B include monovalent hydrocarbon groups preferably having 6 to 10 carbon atoms, more preferably 8 to 10 carbon atoms, such as hexyl group, octyl group and decyl group. This protects the mercapto group, prolongs the Mooney scorch time, makes it possible to improve workability, and further improve low heat build-up.

When the silane coupling agent composed of polysiloxane having the average compositional formula represented by the general formula (2) has a divalent organic group A containing a sulfide group, low heat build-up and workability (especially Mooney scorch maintenance and prolongation of time) to be better. 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 divalent organic group A containing a sulfide group, n represents an integer of 1 to 10, preferably an integer of 2 to 4, in the general formula (3). Also, x represents an integer of 1 to 6, preferably an integer of 2 to 4. The organic group A can be a hydrocarbon group optionally containing heteroatoms such as, for example, oxygen atoms, nitrogen atoms, sulfur atoms.

Specific examples of the group represented by the general formula (3) include *--CH ₂ --S ₂ --CH ₂ --*, *--C ₂ H ₄ --S ₂ --C ₂ H ₄ --*, * _{-C3H6 -} S2 _{- C3H6-} *, * _{-C4H8 -} S2 _{- C4H8- *} , * _{-CH2 - S4 -} CH2-*, * _-C2 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 -*, etc. .

The silane coupling agent made of polysiloxane having the average compositional formula represented by the general formula (2) has a hydrolyzable group C, so that it has excellent affinity and / or reactivity with silica. do. The subscript c of the hydrolyzable group C in the general formula (2) is 1.2 ≤ c ≤ 2.0 for the reason that low heat build-up, excellent processability, and excellent silica dispersibility are obtained. Good. Specific examples of the hydrolyzable group C include 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 improving the workability.
*-OR ² (4)
In the above 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 having 6 to 10 carbon atoms (arylalkyl group) or an alkenyl group having 2 to 10 carbon atoms, An alkyl group having 1 to 5 carbon atoms is preferred.

Specific examples of the alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group and 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 and pentenyl group.

The silane coupling agent composed of polysiloxane having the average compositional formula represented by the above general formula (2) interacts and/or reacts with the diene rubber by having an organic group D containing a mercapto group. 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 improving workability.
*-(CH ₂ )m-SH (5)
In the general formula (5), m represents an integer of 1-10, preferably an integer of 1-5. In the formula, * indicates the bonding position.

Specific examples of the group represented by the general formula (5) include *--CH ₂ SH, *--C ₂ H ₄ SH, *--C ₃ H ₆ SH, *--C ₄ H ₈ SH and *--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 and *--C ₁₀ H ₂₀ SH.

In general formula (2) above, R ¹ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms. Hydrocarbon group R ¹ includes, for example, methyl group, ethyl group, propyl group and butyl group.

The amount of the silane coupling agent compounded is 5 to 18% by mass, preferably 6 to 15% by mass, based on the mass of silica. Silica dispersion can be improved by setting the compounding amount of the silane coupling agent to 5% by mass or more of the amount of silica. Also, by setting the compounding amount of the silane coupling agent to 18% by mass or less of the amount of silica, condensation between the silane coupling agents can be suppressed, and a rubber composition having desired hardness and strength can be obtained.

The rubber composition for tires produced in the present invention always contains carbon black and aromatic oil together with silica and a silane coupling agent.

Examples of 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. The nitrogen adsorption specific surface area of carbon black is not particularly limited, but is preferably 70 m ² /g to 240 m ² /g, more preferably 90 m ² /g to 200 m ² /g. By setting the nitrogen adsorption specific surface area of the carbon black to 70 m ² /g or more, the mechanical properties and abrasion resistance of the rubber composition can be ensured. Also, by setting the nitrogen adsorption specific surface area of the carbon black to 240 m ² /g or less, the low rolling resistance can be improved. In this specification, the nitrogen adsorption specific surface area of carbon black shall be measured according to JIS K6217-2.

Carbon black can be blended in an amount of preferably 5 to 100 parts by mass, more preferably 10 to 80 parts by mass, per 100 parts by mass of 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 ensured. Also, 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 fillers other than silica and carbon black. Other fillers can include calcium carbonate, magnesium carbonate, talc, clay, alumina, aluminum hydroxide, titanium oxide, calcium sulfate. You may use these individually or in combination of 2 or more types.

As the aromatic oil, for example, one having a mass percentage of aromatic hydrocarbons determined according to ASTM D2140 of 15% by mass or more is preferably used. That is, its molecular structure can contain aromatic hydrocarbons, paraffinic hydrocarbons, and naphthenic hydrocarbons, and the content of aromatic hydrocarbons is preferably 15% by mass or more, and 17% by mass. The above are more preferred. Also, the content of aromatic hydrocarbons in the aroma oil is preferably 70% by mass or less, more preferably 65% by mass or less.

Commercially available aromatic oils include, for example, Extract No. 4S manufactured by Showa Shell Sekiyu K.K.; Process NC300S, Process X-140, and the like.

In the rubber composition for tires, the amount of the aromatic oil compounded is preferably 3 parts by mass to 50 parts by mass, more preferably 5 parts by mass to 40 parts by mass, per 100 parts by mass of the diene rubber. Low rolling resistance can be ensured by setting the blending amount of the aromatic oil to 3 parts by mass or more. Also, by setting the blending amount of the aromatic oil to 50 parts by mass or less, the wear resistance can be ensured.

The rubber composition for tires produced in the present invention can contain a dispersant for silica together with silica and a silane coupling agent. Examples of dispersants for silica include amine-based compounds, silane-based compounds, epoxy-based compounds, guanidine-based compounds, and the like. Preferably, at least one selected from amine-based compounds, silane-based compounds, and guanidine-based compounds is used.

A cyclic amine compound etc. can be mentioned as an amine compound. Preferred cyclic amine compounds include piperidine derivatives, piperazine derivatives, morpholine derivatives, thiomorpholine derivatives and the like. Incidentally, the cyclic amine-based compound does not have to have a silicon atom and an enamine structure (NC=C).

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

Examples of hydrocarbon groups having 3 to 30 carbon atoms include aliphatic hydrocarbon groups (including linear, branched and cyclic), aromatic hydrocarbon groups, and combinations thereof. Among them, an aliphatic hydrocarbon group is preferable, and a saturated aliphatic hydrocarbon group is more preferable, from the viewpoint of superior workability. A hydrocarbon group having 8 to 22 carbon atoms is preferable from the viewpoint of better workability. A 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, preferably one or two, hydrocarbon groups having 3 to 30 carbon atoms.

式（Ｉ）中、Ｘ₃ 、Ｘ₄ 、Ｘ₅ 、Ｘ₆ 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、Ｘ₁ 、Ｘ₂ は、互いに独立に、水素原子、－Ａ¹ －Ｒ² 、－Ｒ² 、－（Ｒ³ －Ｏ）_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、Ｘ₁ 、Ｘ₂ の少なくとも１つは、－Ａ¹ －Ｒ² または－Ｒ² である。－Ｒ² は、炭素数３～３０の１価の炭化水素基であり、Ａ¹ は、カルボニル基または－Ｒ⁴ （ＯＨ）－Ｏ－である。Ｒ³ は、炭素数２～３の２価の炭化水素基、Ｒ⁴ 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 preferably be 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 each independently is one selected from the group consisting of a hydrogen atom, —A ¹ —R ² , —R ² , —(R ³ —O) _n —H, a sulfone-based protecting group, and a carbamate-based protecting group; 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 from 1 to 10, preferably from 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), sulfone-based protective groups include, for example, methanesulfonyl, tosyl and nosyl groups. Examples of carbamate-based protective groups include tert-butoxycarbonyl, allyloxycarbonyl, benzyloxycarbonyl and 9-fluorenylmethyloxycarbonyl groups.

上記式中、Ｒは、互いに独立に－Ｃ₁₂Ｈ₂₅または－Ｃ₁₃Ｈ₂₇を表す。 Examples of piperazine derivatives include compounds represented by the following formulas.

In the above formula, R independently represents -C ₁₂ H ₂₅ or -C ₁₃ H ₂₇ .

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 2-10, preferably 2-5.

上記式中、Ｒは、－Ｃ₁₂Ｈ₂₅または－Ｃ₁₃Ｈ₂₇を表し、これらピペラジン系誘導体の混合物でもよい。

In the above formula, R represents -C ₁₂ H ₂₅ or -C ₁₃ H ₂₇ and may be a mixture of these piperazine derivatives.

式（Ｉ）中、Ｘ₃ 、Ｘ₄ 、Ｘ₅ 、Ｘ₆ 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、Ｘ₇ は、酸素原子または硫黄原子であり、Ｘ₁ は、－Ａ¹ －Ｒ² または－Ｒ² である。－Ｒ² は、炭素数３～３０の１価の炭化水素基であり、Ａ¹ は、カルボニル基または－Ｒ⁴ （ＯＨ）－Ｏ－であり、Ｒ⁴ 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。 Morpholine derivatives and thiomorpholine derivatives are preferably represented by the following formula (II).

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 ₇ is an oxygen atom or a sulfur atom. and X ₁ is -A ¹ -R ² or -R ² . —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 a trivalent hydrocarbon group having 3 to 30 carbon atoms. 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、－Ｃ₁₂Ｈ₂₅または－Ｃ₁₃Ｈ₂₇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 formulas.

In the above formula, R represents -C ₁₂ H ₂₅ or -C ₁₃ H ₂₇ and 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 composed of the piperazine derivative, morpholine derivative, and thiomorpholine derivative described above is not particularly limited, and can be obtained by a normal production method. For example, at least one selected from the group consisting of optionally substituted piperazine, morpholine and thiomorpholine, 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 3 to 30 carbon atoms, optionally in a solvent. can be done. Substituents are the same as above. The hydrocarbon group having 3 to 30 carbon atoms possessed by the above hydrocarbon compound is the same as described above. A method for producing a piperazine derivative having a (poly)oxyalkyl group includes, for example, a method of reacting a piperazine derivative having a hydroxy group with an alkylene oxide in the presence of a metal alkoxide.

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 parts by mass to 10 parts by mass, and still more preferably 0 parts by mass with respect to 100 parts by mass of the diene rubber. .8 parts by mass to 5 parts by mass. By setting the compounding amount of the cyclic amine compound to 0.5 parts by mass or more, the rolling resistance of the tire can be reduced and the wet grip performance can be enhanced.

Examples of silane-based compounds include alkylalkoxysilanes, such as monoalkyltrialkoxysilanes, dialkyldialkoxysilanes, and trialkylmonoalkoxysilanes. Among them, alkyltrialkoxysilane is preferred, and alkyltriethoxysilane is more preferred. By blending the alkylalkoxysilane, it is possible to suppress aggregation of silica and increase in viscosity of the rubber composition, and to improve wet grip performance.

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

The amount of alkyltriethoxysilane compounded is preferably 0.5% by mass to 10% by mass, more preferably 2% by mass to 6% by mass, based on the amount of silica compounded. If the amount of alkyltriethoxysilane is less than 0.5% by mass, the effect of suppressing aggregation of silica and the effect of suppressing increase in viscosity of the rubber composition cannot be sufficiently obtained. If the amount of alkyltriethoxysilane exceeds 10% by mass, the retention on the rolls increases during preparation of the rubber composition. Moreover, the rolling resistance of the rubber composition increases, and there is a possibility that the wear resistance decreases.

The rubber composition for tires of the present invention includes vulcanizing or crosslinking agents, vulcanization accelerators, antioxidants, plasticizers, processing aids, liquid polymers, terpene resins, thermosetting resins, and other rubber compositions for tires. Various additives commonly used in the present invention can be blended within a range that does not impede the object of the present invention. Also, such additives can be kneaded in a conventional manner to form a rubber composition and used for vulcanization or cross-linking. The blending amount of these additives can be a conventional general blending amount as long as it does not contradict the object of the present invention.

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

For rubber compositions 1 to 7 having the formulations shown in Table 3, rubber compositions for tires were produced using different production 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 of the rubber composition in Table 3 describes the compounding amount per 100 parts by mass of diene rubber (SBR), the abbreviation of each component, and which mixing step, the first stage or the final stage, was added to the mixer. did. In the first-stage mixing, the total amount of each component listed in the "First-stage mixing" column of Table 3 was added to a mixer (1.7 liter closed Banbury mixer, manufactured by Kobe Steel, Ltd.). Tables 1 and 2 "First charge", "second charge" and "third charge" shown in Fig. 2 were charged and kneaded to obtain a kneaded product, which was discharged from the mixer and cooled. After cooling, the kneaded product was put into the mixer again, and each component described in the "Final stage mixing" column of Table 3 was put in and mixed to obtain a rubber composition (standard example 1 ) by 11 kinds of production methods. , Comparative Examples 1 to 5, and Examples 1 to 5) were prepared (Examples 1 to 3 in which carbon black is not added together with silica, silane coupling agent, and aromatic oil are reference examples).

The temperature control of the Banbury mixer is set to 60° C., and the temperature of various raw materials is normal temperature (23° C.) to start mixing. Tables 1 and 2 show the mixing time and temperature after the completion of the mixing of the component added first and the mixing start temperature of the component added second as the mixing conditions in the first stage of mixing. The mixing time for the components added second and third was 1 minute each. The kneaded material obtained by mixing in the first stage was air-cooled outside the machine until it reached 23°C.

The obtained tire rubber composition was vulcanized at 170° C. for 10 minutes using a mold of a predetermined shape (inner dimensions: length 150 mm, width 150 mm, thickness 2 mm) to prepare a vulcanized rubber test piece. . Using the obtained vulcanized rubber test pieces, wet performance, rolling resistance and wear resistance were measured by the test methods shown below.

Wet performance 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 an extension deformation strain rate of 10 ± 2%, a frequency of 20 Hz, and a temperature of 0 ° C. and tan δ (0°C) was obtained. The obtained results are shown in the "wet performance" column of Tables 1 and 2 as indices with the value of the standard example being 100. The larger the index, the larger the tan δ (0°C) and the better the wet grip performance.

Chip and cut resistance Using the obtained vulcanized rubber test piece, a dumbbell JIS No. 3 test piece was prepared in accordance with JIS K6251, and a tensile test was performed at room temperature (20 ° C.) at a tensile speed of 500 mm / min. The tensile elongation at break was measured. The obtained results are shown in the column of "Chip and Cut Resistance" in Tables 1 and 2 as indices with the value of Standard Example 1 being 100. The larger the index value, the higher the tensile elongation at break and the better the chip-cut resistance.

In Table 3, the types of raw materials used are as follows.
・ SBR: Styrene-butadiene rubber (unmodified), Nipol 1502 manufactured by Nippon Zeon Co., Ltd.
・Carbon black: Show Black N339 manufactured by Cabot Japan
・Silica: ZEOSIL PREMIUM 200MP manufactured by Rhodia, CTAB adsorption specific surface area of 203 m ² /g
Silane coupling agent: sulfide-based silane coupling agent, Si69 manufactured by Evonik Degussa, bis (triethoxysilylpropyl) tetrasulfide Carbon coupling agent: 2EBZ manufactured by Shikoku Kasei Co., Ltd.
Stearic acid: bead 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
・Aroma oil: Extract No. 4 S manufactured by Showa Shell Sekiyu K.K.
・ Zinc oxide: 3 types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd. ・ Sulfur: Fine grain sulfur with Kinkain oil manufactured by Tsurumi Chemical Industry Co., Ltd. (sulfur content 95.24% by mass)
・ Vulcanization accelerator 1: Soxinol DG (DPG) manufactured by Sumitomo Chemical Co., Ltd.
・ Vulcanization accelerator 2: Noxcellar CZ-G (CZ) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

As is clear from Tables 1 and 2, it was confirmed that the rubber compositions obtained by the production methods of Examples 1 to 6 had improved wet performance (tan δ at 0°C) and chip resistance.

On the other hand, in the rubber composition obtained in Comparative Example 1, only carbon black was first charged into the mixer in the first stage of mixing, and silica and the silane coupling agent were not charged first. , the silica and the silane coupling agent do not sufficiently react, and the wet performance and chip-cut resistance cannot be improved. Since the rubber composition obtained in Comparative Example 2 did not contain a silane coupling agent, the wettability and chip resistance were deteriorated. Since the rubber composition obtained in Comparative Example 3 contained too much silane coupling agent, the wettability and chip-cut resistance were deteriorated. In the rubber composition obtained in Comparative Example 4, since the amount of silica compounded was too large, even if silica and the silane coupling agent were added first, the chipping resistance deteriorated. The rubber composition obtained in Comparative Example 5 was the first addition to the mixer in the first stage of mixing. Only silica and the silane coupling agent were mixed. You can't improve your character.

Claims (3)

100 parts by mass of diene rubber is blended with silica, carbon black, and aromatic oil, the amount of silica blended is 10% by mass to 60% by mass of the total amount of silica and carbon black, and the silane coupling agent is the amount of silica. A method for producing a rubber composition containing 5% to 18% by mass of
A method for producing a rubber composition for a tire, characterized in that the silica, the silane coupling agent, the carbon black, and the aromatic oil are put together in a mixer and mixed, and then the diene rubber is added and kneaded. . 2. The method for producing a rubber composition for tires according to claim 1, wherein the total amount of said silica and carbon black is 40 to 180 parts by mass with respect to 100 parts by mass of said diene rubber. 3. The method for producing a rubber composition for a tire according to claim 1, wherein the silica is contained in an amount of 10 parts by mass or more based on 100 parts by mass of the diene rubber.