JP2015013922A - Modified conjugate diene polymer and rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified conjugate diene polymer that can increase heat resistance while suppressing discoloration such as brownish discoloration, and in particular, that can suppress hardening degradation of rubber and give a longer life, and to provide a rubber composition and a pneumatic tire using the polymer.SOLUTION: The modified conjugate diene polymer is obtained by allowing a polymer that is obtained by polymerizing a conjugate diene compound, or a conjugate diene compound and a non-conjugate diene compound, by use of a specific catalyst, to react with a compound having an ozone resistant effect and reactivity with a polymer.

Description

The present invention relates to a modified conjugated diene polymer, and a rubber composition and a pneumatic tire using the same.

Conventionally, anti-aging agents are widely used in rubber compositions used for tires and the like in order to increase the heat resistance of the rubber composition. For example, N- (1,3-dimethylbutyl) -N′-phenyl Amine-based antioxidants such as -p-phenylenediamine (6PPD) and N-phenyl-N'-isopropyl-p-phenylenediamine (IPPD) are used.

However, in recent years, the demand for improving heat resistance has further increased, and a longer life has been demanded. Although a long life can be achieved by increasing the amount of the anti-aging agent, there is a problem that the surface is browned by the precipitation of 6PPD or IPPD on the tire surface, resulting in poor appearance of the tire. Therefore, it is desired to provide a rubber composition that can improve heat resistance and extend the life without increasing the amount of anti-aging agent.

Patent Document 1 discloses a rubber composition in which N- (1-methylheptyl) -N′-phenyl-p-phenylenediamine as an antiaging agent and a wax are blended with a diene rubber. However, there is still room for improvement in terms of improving heat resistance and extending the life while suppressing discoloration such as brown discoloration.

Japanese Patent Laid-Open No. 10-324779

The present invention provides a modified conjugated diene polymer capable of solving the above-mentioned problems and improving heat resistance while suppressing discoloration such as brown discoloration, in particular, suppressing curing deterioration of rubber and extending the life, and It aims at providing the used rubber composition and a pneumatic tire.

The present invention provides a polymer obtained by polymerizing a conjugated diene compound or a conjugated diene compound and a non-conjugated diene compound using a catalyst having the following components (a) to (c) as main components. The present invention relates to a modified conjugated diene polymer obtained by reacting a compound having an ozone action and reactivity with a polymer.
(A) component; a rare earth element-containing compound having an atomic number of 57 to 71, or a reaction product of these compounds with a Lewis base (b) component; alumoxane and / or AlR ²¹ R ²² R ²³ (wherein R ²¹ and R ²² is the same or different and represents a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, R ²³ represents a hydrocarbon group having 1 to 10 carbon atoms, and R ²³ represents R ²¹ or R ^22. And may be the same as or different from the organic aluminum compound (c) component;

As the component (b), it is preferable to use the alumoxane and the organoaluminum compound in combination.

（式中、Ｒ^１、Ｒ^３、Ｒ^４及びＲ^５は、同一若しくは異なって、水素原子、又は置換若しくは非置換の１価炭化水素基を表す。Ｒ^２は、同一若しくは異なって、置換若しくは非置換の２価炭化水素基を表す。） The compound having ozone resistance and reactivity with the polymer is preferably a compound represented by the following formula (1).

(Wherein R ¹ , R ³ , R ⁴ and R ⁵ are the same or different and each represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. R ² is the same or different and is substituted or substituted. Represents an unsubstituted divalent hydrocarbon group.)

The present invention relates to a rubber composition containing the modified conjugated diene polymer.
The present invention also relates to a pneumatic tire produced using the rubber composition.

According to the present invention, a polymer obtained by polymerizing a conjugated diene compound or a conjugated diene compound and a non-conjugated diene compound using a specific catalyst has ozone resistance and reactivity with the polymer. Since it is a modified conjugated diene polymer obtained by reacting a compound, the heat resistance can be improved by using the modified conjugated diene polymer as the rubber component of the rubber composition, and in particular, suppression of rubber deterioration by curing. Is possible. Therefore, while suppressing discoloration such as brown discoloration of the rubber composition, it is possible to prolong the service life and to be suitably applied to each member of the tire.

The modified conjugated diene polymer of the present invention is obtained by polymerizing a conjugated diene compound, or a conjugated diene compound and a non-conjugated diene compound, using a catalyst having the components (a) to (c) as main components. It is obtained by reacting the obtained polymer with a compound having ozone resistance and reactivity with the polymer.

A modified conjugated diene polymer obtained by further reacting a polymer obtained by polymerization using the specific catalyst component with a compound having an ozone resistance and a reactivity with the polymer, the compound is heavy. Since it is bonded to the chain or at the end of the coalescence, it is difficult to deposit on the tire surface, and it is possible to suppress surface deposition more than necessary. In addition, the modified conjugated diene-based polymer produced using a specific catalyst component has a narrow molecular weight distribution of the polymer compared to other polymerization methods. It becomes possible to reduce an ingredient. Therefore, by using the modified conjugated diene polymer of the present invention, it is possible to prevent discoloration by suppressing excessive precipitation of the compound on the tire surface, and at the same time, the heat resistance is improved by the action of the compound, particularly rubber. Can be prevented from curing deterioration. Therefore, it is possible to extend the life of the rubber composition while obtaining good discoloration resistance, and it can be suitably applied to each member of a tire.

Note that the curing deterioration of rubber is a deterioration phenomenon in which the rubber becomes harder than the initial state when heat is applied under the condition where oxygen is present as a deterioration factor. It can be effectively suppressed.

The component (a) is a compound containing a rare earth element having an atomic number of 57 to 71 (rare earth element-containing compound), or a reaction product of these compounds with a Lewis base. Examples of rare earth elements include neodymium, praseodymium, cerium, lanthanum, gadolinium, and mixtures thereof. Examples of the rare earth element-containing compound include rare earth element carboxylates, alkoxides, β-diketone complexes, phosphates, and phosphites.

Examples of the rare earth element carboxylates include salts of octanoic acid, 2-ethylhexanoic acid, oleic acid, stearic acid, benzoic acid, naphthenic acid, versatic acid, and the like. Examples of the rare earth element alkoxide include compounds having an alkoxy group such as a 2-ethyl-hexylalkoxy group, an oleylalkoxy group, a stearylalkoxy group, a phenoxy group, and a benzylalkoxy group. Examples of the rare earth element β-diketone complex include rare earth element acetylacetone, benzoylacetone, and ethylacetylacetone complexes. As rare earth element phosphates or phosphites, bis (2-ethylhexyl) phosphate, bis (1-methylheptyl) phosphate, mono-2-ethylhexyl 2-ethylhexylphosphonate, bis (2-ethylhexyl) Examples thereof include phosphinic acid salts. Of these, neodymium phosphate and neodymium carboxylate are preferable, and carboxylates such as neodymium 2-ethylhexanoate and neodymium versatate are more preferable.

A Lewis base such as acetylacetone, tetrahydrofuran, or pyridine may be used for easily solubilizing the rare earth element-containing compound in a solvent and for stable storage for a long period of time.

（式中、Ｒ^１１は、同一若しくは異なって、炭素数１〜２０の炭化水素基、ｎは２以上の整数を表す。） Examples of the alumoxane of the component (b) include compounds having a structure represented by the following formula (I) or (II). In addition, Fine Chemicals, 23, (9), 5 (1994), J. Am. Am. Chem. Soc. 115, 4971 (1993); Am. Chem. Soc. 117, 6465 (1995).

(In the formula, R ¹¹ are the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms, and n represents an integer of 2 or more.)

In the alumoxane represented by the formulas (I) and (II), examples of the hydrocarbon group represented by R ¹¹ include methyl, ethyl, isobutyl, t-butyl group and the like. n is preferably an integer of 4 to 100. Specific examples of the alumoxane include methylalumoxane, ethylalumoxane, n-propylalumoxane, n-butylalumoxane and the like.

AlR ²¹ R ²² R ^{23 of the} other component (b) (wherein R ²¹ and R ²² are the same or different and represent a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom. R ²³ represents carbon Examples of the organoaluminum compound represented by the formula 1-10 hydrocarbon group, wherein R ²³ may be the same as or different from R ²¹ or R ²² ) include, for example, triethylaluminum, triisobutylaluminum, hydrogen And diethylaluminum hydride and diisobutylaluminum hydride. In addition, it is preferable to use alumoxane and an organoaluminum compound together.

Examples of the halogen-containing compound as the component (c) include a reaction product of a metal halide and a Lewis base, diethylaluminum chloride, silicon tetrachloride and the like. Here, examples of the metal halide include magnesium chloride, calcium chloride, barium chloride, manganese chloride, zinc chloride, and copper chloride. Examples of the Lewis base include phosphorus compounds, carbonyl compounds, nitrogen compounds, ether compounds, alcohols, and the like. Specifically, tri-2-ethylhexyl phosphate, tricresyl phosphate, acetylacetone, 2-ethylhexanoic acid, versatic There are acids, 2-ethylhexyl alcohol, 1-decanol, lauryl alcohol. In addition, a Lewis base is made to react with the ratio of 0.01-30 mol normally with respect to 1 mol of metal halides.

What is necessary is just to set the quantity or composition ratio of each component of the said catalyst according to the objective and necessity. The component (a) is preferably used in an amount of 0.00001 to 1.0 mmol with respect to 100 g of the conjugated diene compound, or the conjugated diene compound and the non-conjugated diene compound. The amount of component (b) used can be expressed as the molar ratio of Al to component (a), and the component (a) component to component (b) is preferably 1: 1 to 1: 1,000. Furthermore, the ratio of the component (a) to the component (c) is preferably 1: 0.1 to 1:30 in terms of molar ratio. In addition to the component (a), the component (b), and the component (c), a conjugated diene compound and / or a non-conjugated diene compound may be used as a catalyst component as necessary.

The catalyst can be produced, for example, by reacting the components (a) to (c) dissolved in a solvent and, if necessary, a conjugated diene compound and / or a non-conjugated diene compound. The order of adding each component is arbitrary. Each component is preferably mixed, reacted, and aged in advance from the viewpoint of improving the polymerization activity and shortening the polymerization initiation induction period. Here, the aging temperature may be appropriately set, and is, for example, 0 to 100 ° C. The aging time may be set appropriately and is usually 0.5 minutes or longer.

In the present invention, a conjugated diene compound, or a conjugated diene compound and a non-conjugated diene compound are polymerized using a catalyst having the components (a) to (c) as main components. Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and the like. Of these, 1,3-butadiene is preferable. The non-conjugated diene compound is not particularly limited. For example, styrene, α-methylstyrene, α-ethylstyrene, 4-cyclohexylstyrene, 2,4,6-trimethylstyrene, t-butylstyrene, 1-vinylnaphthalene, Examples thereof include aromatic vinyl compounds such as 3-vinyltoluene and ethylvinylbenzene. Of these, styrene is preferable. These may be used alone or in combination of two or more. In addition, as a polymer obtained by polymerizing a conjugated diene compound or a conjugated diene compound and a non-conjugated diene compound, butadiene rubber or styrene butadiene rubber is preferable.

The polymerization can be carried out with or without a solvent. Examples of the solvent include inert organic solvents such as saturated aliphatic hydrocarbons having 4 to 10 carbon atoms such as butane, pentane, and hexane, and saturated alicyclic compounds having 6 to 20 carbon atoms such as cyclopentane and cyclohexane. Examples include hydrocarbons, aromatic hydrocarbons such as benzene and toluene.

The polymerization temperature is usually −30 to 200 ° C., and the polymerization reaction may be either a batch type or a continuous type.

In the above, since a specific catalyst is used, a conjugated diene polymer having a high cis-1,4-bond content and a sharp molecular weight distribution is obtained. Specifically, a cis-1,4-bond is obtained. A polymer having a content of 90% or more, preferably 93% or more, and Mw / Mn of 3.5 or less, preferably 3.0 or less, more preferably 2.5 or less is prepared. In addition, adjustment of Mw / Mn can be implemented by controlling the molar ratio of said (a)-(c) component. The 1,2-vinyl bond content of the conjugated diene polymer obtained above is preferably 2.5% or less, and the Mooney viscosity (ML _{1 + 4} , 100 ° C.) is preferably 10-100.

Next, in the present invention, as described above, using a rare earth element compound-based catalyst, a conjugated diene compound, or a conjugated diene compound and a non-conjugated diene compound are polymerized to obtain a polymer. The modified conjugated diene polymer of the present invention can be produced by reacting a polymer with a compound having ozone resistance and reactivity with the polymer. As a method for reacting (modifying) the compound with the polymer, for example, after the polymerization, a compound having ozone resistance and reactivity with the polymer is subsequently added to the active terminal of the living polymer obtained. A modified conjugated diene-based polymer is obtained by reacting (modifying) the active terminal of the polymer with a compound having an ozone resistance and reactivity with the polymer. Moreover, after obtaining a polymer once by the said superposition | polymerization, a modified conjugated diene type polymer can also be obtained by making the said compound react in chains, such as a polymer principal chain. By using the modified conjugated diene-based polymer, it is possible to increase the heat resistance while obtaining good discoloration resistance, and in particular, to suppress the deterioration of curing of the rubber, thereby extending the life.

As a compound having ozone resistance and reactivity with a polymer (hereinafter also referred to as “ozone resistant modifier”), the rubber composition is given ozone resistance and is reactive to a polymer such as a diene polymer. If it is a compound which has this, it will not specifically limit.

Examples of the ozone-denaturing agent include amine-based antioxidants having reactivity with polymers (such as aromatic amine-based or amine-ketone-based amine antioxidants having reactivity). Especially, the compound shown by following formula (1) can be conveniently used as an ozone-resistant modifier from the point that the performance balance of ozone resistance and discoloration resistance can be improved.

（式中、Ｒ^１、Ｒ^３、Ｒ^４及びＲ^５は、同一若しくは異なって、水素原子、又は置換若しくは非置換の１価炭化水素基を表す。Ｒ^２は、同一若しくは異なって、置換若しくは非置換の２価炭化水素基を表す。）

(Wherein R ¹ , R ³ , R ⁴ and R ⁵ are the same or different and each represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. R ² is the same or different and is substituted or substituted. Represents an unsubstituted divalent hydrocarbon group.)

Examples of the substituted or unsubstituted monovalent hydrocarbon group for R ¹ , R ³ , R ⁴ and R ⁵ include a substituted or unsubstituted C 1-18 linear, cyclic or branched alkyl group, alkenyl group, An aryl group, an aralkyl group and the like are preferable. The substituted or unsubstituted divalent hydrocarbon group for R ² may be any of linear, cyclic or branched groups, and is particularly preferably a linear group. Specifically, a substituted or unsubstituted C1-C18 alkylene group, a C2-C18 alkenylene group, a C5-C18 cycloalkylene group, a C6-C18 cycloalkylalkylene group, carbon A C6-C18 arylene group, a C7-C18 aralkylene group, etc. are mentioned, Among these, a substituted or unsubstituted C1-C18 alkylene group is preferable. Incidentally, the substituent of the hydrocarbon group R ¹ to R ⁵ is not particularly limited, include a functional group such as a hydroxyl group, among them, it is preferred that R ³ has a substituent.

Specific examples of the substituted or unsubstituted monovalent hydrocarbon group for R ¹ , R ³ , R ⁴ and R ⁵ include a substituted or unsubstituted methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl. Group, isobutyl group, sec-butyl group, tert-butyl group and the like. Specific examples of the substituted or unsubstituted divalent hydrocarbon group for R ² include a substituted or unsubstituted methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group and the like. In the above formula, it is particularly preferred that R ¹ , R ⁴ and R ⁵ are hydrogen atoms, R ² is a substituted or unsubstituted linear alkylene group, and R ³ is an alkyl group such as a methyl group.

Specific examples of the ozone-modifying agent include N-phenyl-N ′-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine.

When the compound is subsequently reacted (modified) with the active end of the resulting living polymer after polymerization, the amount of the modifying agent used relative to the component (a) is usually 0.01 to 200, preferably 0.1 to 150. In the modification reaction, the reaction temperature is usually 160 ° C. or lower, preferably −30 ° C. to + 130 ° C., and the reaction time is usually 0.1 to 10 hours, preferably 0.2 to 5 hours. In addition, after obtaining a polymer once and preparing it by making an ozone-resistant modifier | denaturant react (denaturation) in the chain | strand of a polymer, what is necessary is just to adjust modification | denaturation amount (compound amount made to react), reaction temperature, and reaction time suitably. .

When the target modified conjugated diene polymer is prepared by reacting (modifying) the compound with the active terminal of the resulting living polymer after polymerization, after the modification reaction is completed, if necessary, A polymerization terminator and a polymer stabilizer can be added to the reaction system and recovered by a known solvent removal and drying operation in the production of a conjugated diene polymer. In addition, once a polymer is obtained, an ozone-resistant modifying agent can be reacted with the polymer when a modified conjugated diene polymer is prepared by reacting (modifying) an ozone-resistant modifying agent in the polymer chain. A modified conjugated diene polymer can be produced using a known method.

The resulting modified conjugated diene polymer has a cis-1,4-bond content of 90% or more, preferably 93% or more, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn). Is 4 or less, preferably 3.5 or less. When it is less than 90% and Mw / Mn exceeds 4, the wear resistance tends to decrease. The vinyl-1,2-bond content of the modified conjugated diene polymer is 2.5% or less, preferably 2.0% or less. If it exceeds 2.5%, the durability tends to decrease. The Mooney viscosity (ML _{1 + 4} , 100 ° C.) at 100 ° C. of the modified conjugated diene polymer is preferably 10 to 150. If it is less than 10, the abrasion resistance after vulcanization is inferior. On the other hand, if it exceeds 150, the workability during kneading tends to be inferior. Further, the polystyrene-equivalent Mw of the modified conjugated diene polymer is usually 100,000 to 1,500,000, preferably 150,000 to 1,000,000. In addition, the modified conjugated diene polymer obtained can be recovered by removing the solvent and drying after adding a process oil such as aromatic oil or naphthenic oil, if necessary, before removing the solvent.

The rubber composition of the present invention contains the modified conjugated diene polymer. Here, the content of the modified conjugated diene polymer is preferably 5% by mass or more, more preferably 20% by mass or more, and further preferably 35% by mass or more in 100% by mass of the rubber component. If it is less than 5% by mass, the effect of suppressing curing deterioration may not be sufficiently obtained. Moreover, the upper limit of this content is not specifically limited, Although 100 mass% may be sufficient, Preferably it is 90 mass% or less, More preferably, it is 80 mass% or less. In addition, the said modified conjugated diene type polymer may be used independently, and may use 2 or more types together.

In addition to the modified conjugated diene polymer, examples of rubber components that can be used include diene rubber, and specific examples include natural rubber (NR), isoprene rubber (IR), and butadiene rubber (BR). Styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and the like. Of these, NR, BR, and SBR are preferable, and NR is preferable from the viewpoint of heat resistance and an effect of suppressing curing deterioration.

The content of NR is preferably 5% by mass or more, more preferably 20% by mass or more, and further preferably 35% by mass or more in 100% by mass of the rubber component. If it is less than 5% by mass, the effect of suppressing curing deterioration may not be sufficiently obtained. Moreover, this content becomes like this. Preferably it is 90 mass% or less, More preferably, it is 80 mass% or less.

The rubber composition preferably contains a reinforcing filler known in the rubber field, such as carbon black and silica.

Examples of carbon black include ISAF and SAF. By blending such carbon black, the reinforcing property can be enhanced and a good effect of suppressing curing deterioration can be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 90 m ² / g or more, and more preferably 100 m ² / g or more. Also, _N 2 SA of the carbon black is preferably 150 meters ² / g or less, more preferably 130m ² / g. In the case of less than 90 m ² / g, in the case of exceeding 150 m ² / g, it may be difficult to confirm the effect of suppressing the curing deterioration. The N ₂ SA of carbon black is determined by the A method of JIS K6217.

The content of carbon black is preferably 20 parts by mass or more, more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 20 parts by mass, the effect of suppressing curing deterioration may not be obtained satisfactorily. Moreover, this content becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 70 mass parts or less. If it exceeds 100 parts by mass, the dispersibility of the filler may be deteriorated.

Examples of the silica include, but are not limited to, dry method silica (anhydrous silicic acid), wet method silica (anhydrous silicic acid), and the like, and wet method silica is preferable because it has many silanol groups. By blending silica, heat resistance (particularly the effect of suppressing curing deterioration) can be improved.

The BET specific surface area (BET) of the silica is preferably 50 m ² / g or more, more preferably 80 m ² / g or more. Further, N ₂ SA of silica is preferably 250 m ² / g or less, more preferably 200 m ² / g or less. If it is less than 50 m ² / g, when more than 250 meters ² / g, there is a possibility that hardening degradation suppressing effect can not be obtained. Incidentally, BET specific surface area _(N 2 SA) of the silica is a value determined by the BET method in accordance with ASTM D3037-81.

The content of silica is preferably 20 parts by mass or more, more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 20 parts by mass, there is a possibility that the curing deterioration suppressing effect cannot be sufficiently obtained. Content of this silica becomes like this. Preferably it is 100 mass parts or less, More preferably, it is 80 mass parts or less, More preferably, it is 70 mass parts or less. When the amount exceeds 100 parts by mass, the dispersion of silica is deteriorated, and the effect of suppressing curing deterioration may not be obtained.

When silica is blended with the rubber composition of the present invention, it is preferable to blend a silane coupling agent. As the silane coupling agent, any silane coupling agent conventionally used in combination with silica can be used in the rubber industry. For example, sulfide-based, mercapto-based, vinyl-based, glycidoxy-based, nitro-based, chloro-based And silane coupling agents such as Of these, sulfide-based silane coupling agents such as bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide are preferable from the viewpoint of the reinforcing effect and processability of the silane coupling agent. .

The content of the silane coupling agent is preferably 3 parts by mass or more and more preferably 7 parts by mass or more with respect to 100 parts by mass of silica. If it is less than 3 mass parts, there exists a tendency for a fracture strength to fall large. Moreover, 15 mass parts or less are preferable, and, as for content of this silane coupling agent, 10 mass parts or less are more preferable. When the amount exceeds 15 parts by mass, effects such as an increase in fracture strength and a reduction in rolling resistance due to the addition of the silane coupling agent tend not to be obtained.

In the present invention, other fillers may be blended in addition to the carbon black and silica. Examples of other fillers include inorganic fillers such as clay and calcium carbonate.

In the rubber composition of the present invention, the total content of the filler is preferably 20 parts by mass or more, more preferably 40 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 20 parts by mass, the effect of suppressing curing deterioration may not be obtained satisfactorily. The total content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and still more preferably 70 parts by mass or less. When the amount exceeds 100 parts by mass, the dispersion of the filler is deteriorated, and the effect of suppressing the curing deterioration may not be obtained.

In addition to the above components, the rubber composition of the present invention includes compounding agents conventionally used in the rubber industry, for example, stearic acid, zinc oxide, various anti-aging agents, vulcanizing agents such as wax, sulfur or sulfur compounds, Vulcanization accelerators and the like can be appropriately blended as necessary.

As described above, the rubber composition of the present invention contains a modified conjugated diene polymer modified with an ozone-resistant modifier. However, if necessary, an anti-aging agent may be added separately as needed. As the anti-aging agent, an amine-based anti-aging agent is preferably used from the viewpoint of excellent destructive properties. Examples of amine-based antioxidants include diphenylamine-based and p-phenylenediamine-based amine derivatives. Examples of the diphenylamine derivative include p- (p-toluenesulfonylamide) -diphenylamine, octylated diphenylamine, and the like. Examples of p-phenylenediamine derivatives include N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine (6PPD), N-phenyl-N′-isopropyl-p-phenylenediamine (IPPD). ), N, N′-di-2-naphthyl-p-phenylenediamine, and the like.

The lower limit of the blending amount of the anti-aging agent is not particularly limited, and if the modified conjugated diene polymer can achieve desired heat resistance and curing deterioration suppressing effect, it is not necessary to add, but when added, the blending The lower limit of the amount is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 0.1 part by mass, the desired heat resistance and curing deterioration suppressing effect may not be obtained. Moreover, this compounding quantity becomes like this. Preferably it is 3.0 mass parts or less, More preferably, it is 2.0 mass parts or less, More preferably, it is 1.5 mass parts or less. If it exceeds 3.0 parts by mass, bloom may be generated on the surface.

In the present invention, sulfur can be suitably used as a vulcanizing agent. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur.
The sulfur content is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and still more preferably 1.5 parts by mass or more with respect to 100 parts by mass of the rubber component. If the amount is less than 0.5 parts by mass, the effect of the present invention may be small. Moreover, this content becomes like this. Preferably it is 10 mass parts or less, More preferably, it is 6 mass parts or less, More preferably, it is 4 mass parts or less. If it exceeds 10 parts by mass, the effect of suppressing the curing deterioration may not be sufficiently obtained.

Examples of the vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N′-dicyclohexyl-2- Examples include benzothiazolylsulfenamide (DZ), mercaptobenzothiazole (MBT), dibenzothiazolyl disulfide (MBTS), diphenylguanidine (DPG), and the like. .1 to 2.0 parts by mass may be blended.

The rubber composition of the present invention is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll or the like and then vulcanizing.

The rubber composition of the present invention can be suitably used for tire members such as treads, sidewalls, and internal components.

The pneumatic tire of the present invention can be produced by a usual method using the rubber composition. That is, the rubber composition is extruded in accordance with the shape of the tire member at an unvulcanized stage, molded by a normal method on a tire molding machine, and bonded together with other tire members to form an unvulcanized tire. Form. This unvulcanized tire can be heated and pressurized in a vulcanizer to produce a tire.

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

According to the following manufacture example 1 and comparative manufacture examples 1-2, the polymer 1 and the comparative polymers 1-2 were prepared. Table 1 shows the physical properties of each polymer measured by the following method.

(Production Example 1)
A nitrogen-substituted 5 L autoclave was charged with 2.4 kg of cyclohexane and 300 g of 1,3-butadiene under nitrogen. To these, as a catalyst component, a solution of neodymium versatic acid (0.09 mmol) in cyclohexane, a solution of methylalumoxane (7.2 mmol) in toluene, diisobutylaluminum hydride (3.6 mmol) and diethylaluminum chloride (0.18 mmol) The toluene solution was charged with 5 times the amount of neodymium 1,3-butadiene and a catalyst that was aged at 50 ° C. for 30 minutes, and polymerization was carried out at 80 ° C. for 60 minutes. The reaction conversion of 1,3-butadiene was almost 100%. In order to measure Mooney viscosity, a part of the polymerization solution was extracted, coagulated and dried. The cis-1,4-bond content was 95.5%, the vinyl bond content was 1.4%, and Mw / Mn was 2.7. Next, the temperature of this polymerization solution was kept at 50 ° C., and N-phenyl-N ′-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine (4.5 mmol, Novak G-1 (Emerging Ouchi) Chemical Industry Co., Ltd.)) was added and allowed to react for 30 minutes. Thereafter, a methanol solution containing 1.5 g of 2,4-di-tert-butyl-p-cresol was added, and after the polymerization was stopped, the solvent was removed by steam stripping, followed by drying with a roll at 110 ° C. Got.

(Comparative Production Example 1)
A commercially available polybutadiene rubber (manufactured by JSR Corporation, polybutadiene rubber BR01) was used (Comparative Polymer 1).

(Comparative Production Example 2)
A 1.5 liter stainless steel autoclave was charged with 1 liter of a cyclohexane mixed solution containing 30% by mass of 1.3-butadiene, and then 2.7 mmol of triethylaluminum and 2.7 boron trifluoride diethyl etherate. The autoclave was heated up and the internal temperature reached 58.5 ° C., then 0.10 mmol of nickel octoate was added, and a polymerization reaction was carried out at 60 ° C. for 30 minutes. . Next, the temperature of this polymerization solution was kept at 50 ° C., and N-phenyl-N ′-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine (4.5 mmol) was added and reacted for 30 minutes. It was. Thereafter, a methanol solution containing 1.5 g of 2,4-di-tert-butyl-p-cresol was added, and after the polymerization was stopped, the solvent was removed by steam stripping, followed by drying with a roll at 110 ° C. 2 was obtained.

<Mooney viscosity (ML _{1 + 4} , 100 ° C.)>
Preheating was performed for 1 minute, measurement time of 4 minutes, and a temperature of 100 ° C.

<Number average molecular weight (Mn), weight average molecular weight (Mw)>
Measurement was performed under the following conditions using a differential refractometer as a detector using HLC-8120GPC manufactured by Tosoh Corporation.
Column: manufactured by Tosoh Corporation, column GMHHXL mobile phase: tetrahydrofuran

<Microstructure (cis-1,4-bond content, vinyl-1,2-bond content)>
It calculated | required by the infrared method (Morello method).

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Polymer 1: prepared in Production Example 1 Comparative polymer 1: Comparative Production Example 1 (polybutadiene rubber BR01)
Comparative Polymer 2: Prepared in Comparative Production Example 2 NR: TSR
Carbon black: Dia Black I (ISAF carbon, N ₂ SA: 114 m ² / g) manufactured by Mitsubishi Chemical Corporation
Silica: Silica 115Gr (N ₂ SA: 110 m ² / g) manufactured by Rhodia Japan Co., Ltd.
Silane coupling agent: Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Degussa
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd.
Anti-aging agent: Anti-aging agent 6C (SANTOFLEX, 6PPD) manufactured by FLEXSYS Corporation
Sulfur: Powder sulfur vulcanization accelerator 1 (TBBS) manufactured by Tsurumi Chemical Co., Ltd .: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator 2 (DPG): Soxinol D (diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

(Examples and Comparative Examples)
Materials other than sulfur and a vulcanization accelerator were kneaded using a 1.7 L Banbury mixer according to the blending contents shown in Tables 2-3. Sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 3 minutes at 80 to 90 ° C. using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press vulcanized at 170 ° C. for 10 to 20 minutes to obtain a vulcanized rubber composition. The obtained vulcanized rubber composition was used as a new sample.

Further, the obtained unvulcanized rubber composition was molded into a tread shape, bonded together with other tire members on a tire molding machine, vulcanized at 150 ° C. for 30 minutes, and a test tire (tire size) : 215 / 45R17).

(Deterioration conditions)
The new sample prepared above was thermally deteriorated in an oven at 80 ° C. for 7 days. The obtained sample was used as a deteriorated sample.

The following evaluation was performed using the obtained new samples and deteriorated samples. Each test result is shown in Tables 2-3. In the table, the value of the deteriorated sample when the new sample is set to 100 is shown as an index, and the hardness, swelling rate, and M100 performance are closer to 100, the deterioration is less than the new product, and the heat deterioration performance is lower. Shows good.

<Hardness>
Using the prepared sample, the hardness of the rubber was measured using a hardness meter at a temperature of 25 ° C. according to JIS K6253 (Shore-A measurement). It shows that it is so hard that a numerical value is large.

<Swelling rate>
The immersion test of the prepared sample was performed according to JIS K6258, and the volume of the sample after being immersed in toluene at 40 ° C. for 24 hours and swollen was measured and calculated from the volume change. The smaller the value, the higher the crosslink density.

<Stress at 100% elongation (M100)>
Using a No. 3 dumbbell-shaped test piece made of the prepared sample, a tensile test was performed at a pulling speed of 500 mm / min in accordance with JIS K6251 “vulcanized rubber and thermoplastic rubber—determining tensile properties”. The stress at 100% elongation at 23 ° C. (M100 (MPa)) was measured. Larger numbers indicate higher modulus and hardness. M100 is also an index of crosslink density.

<Discoloration resistance>
The prepared test tire was allowed to stand at ozone 50 pphm and 40 ° C. for 1 week, and then the discoloration (brown discoloration) was evaluated by measuring the blackness of the cap tread surface using a color difference meter. The evaluation criteria are as follows.
○: The surface is black and no discoloration is observed. Δ: The surface is slightly discolored to brown. ×: The surface is clearly discolored to brown.

From Tables 2 and 3, by using the modified BR of the present invention, superior discoloration resistance and heat resistance (particularly a curing deterioration inhibiting effect) are obtained as compared with the case of using ordinary BR or modified BR having a wide molecular weight distribution. It became clear that it was obtained.

Claims (5)

A polymer obtained by polymerizing a conjugated diene compound or a conjugated diene compound and a non-conjugated diene compound using a catalyst having the following components (a) to (c) as main components: A modified conjugated diene polymer obtained by reacting a compound having reactivity with.
(A) component; a rare earth element-containing compound having an atomic number of 57 to 71, or a reaction product of these compounds with a Lewis base (b) component; alumoxane and / or AlR ²¹ R ²² R ²³ (wherein R ²¹ and R ²² is the same or different and represents a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, R ²³ represents a hydrocarbon group having 1 to 10 carbon atoms, and R ²³ represents R ²¹ or R ^22. And may be the same as or different from the organic aluminum compound (c) component; The modified conjugated diene polymer according to claim 1, wherein the alumoxane and the organoaluminum compound are used in combination as the component (b). The modified conjugated diene polymer according to claim 1 or 2, wherein the compound having ozone resistance and reactivity with a polymer is a compound represented by the following formula (1).

(Wherein R ¹ , R ³ , R ⁴ and R ⁵ are the same or different and each represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. R ² is the same or different and is substituted or substituted. Represents an unsubstituted divalent hydrocarbon group.) A rubber composition comprising the modified conjugated diene polymer according to any one of claims 1 to 3. A pneumatic tire produced using the rubber composition according to claim 4.