JP2015083649A - Rubber composition and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both wet road brake performance and rolling resistance performance while maintaining tear resistance.SOLUTION: There is provided a rubber composition containing 100 pts.mass of diene rubber, 10 to 150 pts.mass of silica, 1 to 30 pts.mass of a diene polymer chain having at least one group represented by the general formula (1) in a molecule and a main chain with a number average molecular weight of 4000 to 50000, and 1 to 30 pts.mass of at least one kind of resin selected from a group consisting of petroleum resin, rosin-based resin, and styrenic resin. In the general formula (1), R, R, and Rare an alkyl group or alkoxy group having 1 to 6 carbon atoms and at least one is an alkoxy group, X is a hydrocarbon group having 1 to 18 carbon atoms, and Y is an urethane bond, an amide bond, an imide bond, and an urea bond.

Description

  The present invention relates to a rubber composition and a pneumatic tire using the same.

  In recent tires, there is a high demand for low fuel consumption, and excellent rolling resistance performance, that is, low rolling resistance is required. On the other hand, tires are also required to have excellent braking performance on wet road surfaces, that is, wet road braking performance. However, since these performances are contradictory, it is generally difficult to achieve both.

  In Patent Document 1, a low molecular weight diene rubber having a mass average molecular weight of 500 to 10,000 is modified in order to improve workability, rolling resistance performance, wet skid performance, wet on ice performance, and wear resistance. The use of a modified diene rubber modified with an organosilicon compound containing an alkoxy group as an agent is disclosed. However, as the modifying agent, only a silane coupling agent that undergoes an addition reaction with a double bond of a diene rubber is disclosed, and the combined use with a resin is not mentioned.

  In Patent Document 2, in order to improve unvulcanized physical properties, wear resistance, heat aging resistance, and low heat build-up, a modified liquid polymer having an organosilicon functional group is added to a rubber composition via a urethane bond. Is disclosed. In Patent Document 3, a modified liquid polymer into which an organosilicon functional group is introduced may be added to a rubber composition in order to improve processability, low heat build-up, and wear resistance without impairing tensile properties. It is disclosed. Although these documents describe that the number average molecular weight of the modified liquid polymer is 500 to 10,000, it is described that the number average molecular weight is preferably 1,000 to 3,000, and specifically disclosed modified liquids. The number average molecular weight of the polymer is about 2500, and only a relatively low molecular weight modified liquid polymer is disclosed. Also, there is no disclosure of blending a modified liquid polymer in combination with a resin, and it is impossible to achieve both wet road braking performance and rolling resistance performance.

  Patent Document 4 discloses that a plasticizer and a resin such as an aromatic petroleum resin are blended in a rubber composition in order to improve fuel economy, processability, adhesion, and rubber strength in a balanced manner. It is disclosed that a diene polymer having a mass average molecular weight of 3000 to 150,000 is used as the agent, and that the diene polymer may be modified with a modifier such as aminoalkyltrialkoxysilane. . As described above, Patent Document 4 discloses a modified diene polymer having an alkoxysilyl group as a modifying group as a plasticizer, but the modified group does not contain a carbonyl group, and wet road braking performance. No mention is made of the balance of rolling resistance performance.

JP 2002-114874 A JP 2005-350603 A JP 2006-063209 A JP2013-028650A

  The present invention has been made in view of the above, and an object of the present invention is to provide a rubber composition capable of achieving both wet road braking performance and rolling resistance performance.

The rubber composition according to the present invention has 100 parts by mass of a diene rubber, 10 to 150 parts by mass of silica, and at least one group represented by the following general formula (1) in the molecule, and the main chain is several. 1 to 30 parts by mass of a modified liquid diene polymer consisting of a diene polymer chain having an average molecular weight of 4000 to 50000, and at least one resin selected from the group consisting of petroleum resin, rosin resin and styrene resin Part.

In the formula (1), R ¹ , R ² and R ³ each represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and at least one is an alkoxy group. X represents a C1-C18 hydrocarbon group which may contain a hetero atom, and Y represents a urethane bond, an amide bond, an imide bond or a urea bond.

  The pneumatic tire according to the present invention is formed using the rubber composition.

  According to the present invention, by using a specific modified liquid diene polymer having a high molecular weight and the above resin in combination, it is possible to achieve both wet road braking performance and rolling resistance performance while maintaining tearing characteristics.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

  In the rubber composition according to this embodiment, silica (B), a specific modified liquid diene polymer (C) having a high molecular weight, and a resin (D) are blended with the diene rubber (A) as a rubber component. It is made. In the low molecular weight modified liquid polymer, there are many reaction points of silica per the polymer, and the silica is agglomerated with the progress of the reaction, and the dispersion of silica tends to deteriorate. Therefore, the tearing property tends to deteriorate. On the other hand, by using a modified liquid diene polymer having a high molecular weight, it is possible to prevent deterioration of tear characteristics. In addition, since the modified liquid diene polymer has an alkoxysilyl group that reacts with silica, the mobility of the polymer is reduced, and the rolling resistance is reduced. In general, wet road braking performance and rolling resistance performance are contradictory, but the modified liquid diene polymer of this embodiment has a highly polar urethane bond, amide bond, imide bond, and urea bond. It is considered that the dispersion of the resin is improved by the action or the like, which leads to a remarkable improvement in the wet road braking performance. By combining these effects, it is possible to balance the contradictory physical properties of improving wet road braking performance and reducing rolling resistance while maintaining the tear characteristics.

  The diene rubber as the rubber component (A) is not particularly limited. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene- Isoprene rubber, butadiene-isoprene rubber, styrene-butadiene-isoprene rubber, nitrile rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like are used, and these are used alone or in combination of two or more. be able to. More preferably, it is NR, SBR, BR, or a blend rubber of two or more thereof. Further, in these molecular terminals or molecular chains, modification is made with at least one functional group selected from the group consisting of an amino group, hydroxyl group, epoxy group, alkoxy group, alkylsilyl group, alkoxysilyl group, and carboxyl group. Modified diene rubber modified, or modified diene rubber modified with a compound containing tin can also be used. In the present invention, the diene rubber (A) is made of a solid rubber having no fluidity at room temperature (23 ° C.), and the modified liquid diene polymer (C) is not included in the rubber component. . The number average molecular weight (Mn) of the diene rubber (A) is usually 100,000 or more, and Mn may be 100,000 to 1,200,000 as one embodiment. In this specification, a number average molecular weight is a value (polystyrene conversion value) measured at 40 ° C. by GPC (gel permeation chromatography), solvent: THF (tetrohydrofuran).

Although it does not specifically limit as said silica of (B), Wet silica, such as wet precipitation method silica and wet gel method silica, is used preferably. The BET specific surface area (measured according to the BET method described in JIS K6430) of silica is preferably, for example, 90 to 250 m ² / g, and more preferably 150 to 220 m ² / g.

  The compounding amount of silica is appropriately set so as to obtain the reinforcing property required according to the application, and is usually 10 to 150 parts by mass with respect to 100 parts by mass of the diene rubber (A), more preferably. It is 30-120 mass parts, More preferably, it is 40-100 mass parts.

In the rubber composition according to this embodiment, silica may be used alone, but carbon black may be used in combination with silica. Carbon black is not particularly limited, and various known varieties can be used. For example, when used for tire tread rubber, those having a nitrogen adsorption specific surface area (N ₂ SA) (JIS K6217-2) of 70 to 150 m ² / g are preferably used. Specifically, SAF class (N100 series), ISAF class (N200 series), HAF class (N300 series) (both ASTM grade) are preferably used. When carbon black is used in combination, the blending amount is preferably 20 to 180 parts by mass in total with silica, more preferably 30 to 150 parts by mass, and still more preferably 50 to 100 parts by mass. . When silica and carbon black are used in combination, the amount of silica is preferably equal to or greater than the amount of carbon black.

  The modified liquid diene polymer (C) is a liquid polymer having fluidity at room temperature (23 ° C.), and the main chain is a diene polymer chain having a number average molecular weight of 4000 to 50000. Therefore, it is clearly distinguished from the diene rubber (A) whose number average molecular weight is usually 100,000 or more. Such a modified liquid diene polymer may be used as a component for substituting part or all of the oil, but is not limited to the case where the oil is substituted and blended.

  In the modified liquid diene polymer (C), the number average molecular weight (Mn) of the diene polymer chain constituting the main chain is 4000 to 50000, and the liquid diene polymer has a relatively high molecular weight. By modifying and using such a liquid diene polymer having a high molecular weight, it is possible to suppress degradation of tearing properties. The number average molecular weight (Mn) of the diene polymer chain is preferably 4000 to 35000, and more preferably 4500 to 30000. When the number average molecular weight of the diene polymer chain is too large, the above-mentioned Y having polarity is decreased, and the interaction with the resin (D) is considered to be weakened, and the improvement range of the wet road braking performance is reduced.

  The diene polymer chain is a molecular chain of a polymer containing a conjugated diene monomer as a constituent unit, and may be a homopolymer composed of one kind of conjugated diene monomer or a copolymer of two or more kinds of conjugated diene monomers. Also, a copolymer of a conjugated diene monomer and a vinyl monomer may be used. Specific examples of such a diene polymer chain include, for example, a polybutadiene chain having a repeating structure of a butadiene unit, a polyisoprene chain having a repeating structure of an isoprene unit, a styrene butadiene copolymer chain having a butadiene unit and a styrene unit, and an isoprene unit. And a styrene isoprene copolymer chain composed of styrene units and a butadiene isoprene copolymer chain composed of butadiene units and isoprene units. Preferably, it is a polybutadiene chain or a polyisoprene chain, and therefore a preferable modified liquid diene-based polymer is a modified liquid polybutadiene and / or a modified liquid polyisoprene.

  The modified liquid diene polymer (C) has at least one group represented by the general formula (1) (hereinafter sometimes referred to as a modified group) in the molecule. Such a modifying group may be introduced at the end (both ends or one end) of the molecular chain of the main chain, or may be introduced at one or a plurality of positions in the molecular chain. The introduction amount of the modifying group is not particularly limited, but is preferably 1 to 20 on average per molecule, and more preferably 2 to 15 per molecule. The modifying group may be directly bonded to the main chain diene polymer chain, or may be bonded via any linking group.

In the formula (1), R ¹ , R ² and R ³ each represent an alkyl group having 1 to 6 carbon atoms or an alkoxy group, and at least one is an alkoxy group. Preferably, it is a C1-C3 alkyl group or an alkoxy group. As the alkyl group, for example, a methyl group or an ethyl group is preferable. As the alkoxy group, for example, a methoxy group or an ethoxy group is preferable. Two or more of R ¹ , R ² and R ³ are preferably alkoxy groups, and more preferably all three are alkoxy groups. That is, the alkoxysilyl group represented by -SiR ¹ R ² R ³ is preferably an alkyl dialkoxysilyl group or a trialkoxysilyl group, more preferably a triethoxysilyl group or a trimethoxysilyl group. An alkoxysilyl group.

In formula (1), X represents a C1-C18 divalent hydrocarbon group which may contain a hetero atom. Examples of the hetero atom include at least one selected from an oxygen atom, a nitrogen atom, a halogen atom, and a sulfur atom. X preferably represents an alkylene group having 1 to 18 carbon atoms (more preferably 1 to 6 carbon atoms) (that is, an alkanediyl group), and may be linear or branched. Preferable specific examples of X include a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group. In one embodiment, X is a linear alkylene group represented by — (CH ₂ ) _n —, where n = 1 to 6 (preferably n = 1 to 3).

  In formula (1), Y represents a urethane bond, an amide bond, an imide bond or a urea bond. These all contain a carbonyl group together with a nitrogen atom, and are considered advantageous for improving the dispersibility of the resin (D). The modified liquid diene polymer having such a functional group can be synthesized from a commercially available liquid diene polymer having a hydroxyl group, a carboxyl group, an acid anhydride group, or the like.

  For example, when Y is a urethane bond, an alkoxysilyl group can be introduced through a urethane bond by reacting a liquid diene polymer having a hydroxyl group with a silane compound having an isocyanate group and an alkoxy group.

  When Y is an amide bond, an alkoxysilyl group can be introduced via the amide bond by reacting a liquid diene polymer having a carbosyl group with a silane compound having an isocyanate group and an alkoxy group.

  When Y is an imide bond, an alkoxysilyl group can be introduced through an imide bond by reacting a liquid diene polymer having an acid anhydride group with a silane compound having an isocyanate group and an alkoxy group.

  When Y is a urea bond, a diisocyanate compound is reacted with a liquid diene polymer having a hydroxyl group, an isocyanate group is introduced through a urethane bond, and then a silane compound having an amino group and an alkoxy group is reacted. An alkoxysilyl group can be introduced through a urea bond.

In the case of such an introduction method, —X—Y— in the formula (1) is represented by any of the following formulas (2) to (5).

In formulas (2) to (5), R ⁴ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a methyl group, and still more preferably a hydrogen atom. When formula (2) is a urethane bond, formula (3) is an amide bond, formula (4) is an imide bond, and formula (5) is a urea bond. In the case of a urea bond, since the urethane bond is also introduced according to the introduction method, the following formula (6) is introduced into the liquid diene polymer in more detail.

^X in the formula ^{(6), R 1, R} 2, R 3 and ^{R 4} are the same as the formula (1) and ^X in the formula ^{(5), R 1, R} 2, R 3 and ^{R 4.} Z represents the C1-C18 bivalent hydrocarbon group which may contain a hetero atom similarly to said X, and its preferable aspect is also the same as X.

  The modified liquid diene polymers (C) listed above may be used alone or in combination of two or more. The blending amount of the modified liquid diene polymer (C) is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the diene rubber (A). An improvement effect can be heightened by mix | blending 1 mass part or more. Further, when the blending amount is 30 parts by mass or less, it is possible to suppress a decrease in hardness and to enhance the deterioration of tear characteristics and the improvement effect of wet road braking performance. The blending amount of the modified liquid diene polymer (C) is more preferably 3 to 20 parts by mass, still more preferably 5 to 15 parts by mass.

  Examples of the resin (D) include petroleum resins, rosin resins, and styrene resins, which may be used alone or in combination of two or more. As these resins, those having a softening point of 80 to 140 ° C. are preferably used. Here, the softening point is a value measured according to JIS K2207 (ring and ball type).

  Examples of petroleum resins include C5 aliphatic hydrocarbon resins, C9 aromatic hydrocarbon resins, and C5 / C9 aliphatic / aromatic copolymer hydrocarbon resins. An aliphatic hydrocarbon resin is a resin obtained by cationic polymerization of an unsaturated monomer such as isoprene or cyclopentadiene, which is a petroleum fraction (C5 fraction) having 4 to 5 carbon atoms, and is hydrogenated. It may be a thing. An aromatic hydrocarbon resin is a resin obtained by cationic polymerization of monomers such as vinyltoluene, alkylstyrene, and indene, which are petroleum fractions (C9 fractions) equivalent to 8 to 10 carbon atoms. It may be what you did. The aliphatic / aromatic copolymer hydrocarbon resin is a resin obtained by copolymerizing the C5 fraction and the C9 fraction by cationic polymerization, and may be hydrogenated.

  Examples of the rosin resin include raw rosins such as gum rosin, wood rosin, tall oil rosin, disproportionate of raw rosin, stabilized rosin obtained by hydrogenating raw rosin, rosins such as polymerized rosin, and rosins. Various known products such as esterified products (rosin ester resins), phenol-modified rosins, unsaturated acid (such as maleic acid) -modified rosins, and formylated rosins obtained by reducing rosins can be used. Among these, polymerized rosin, phenol-modified rosins, unsaturated acid-modified rosins, and rosin ester resins are preferable, and unsaturated acid-modified rosins such as rosin-modified maleic resin are more preferable.

  Examples of the styrene resin include α-methylstyrene homopolymer, styrene / α-methylstyrene copolymer, styrene monomer / aliphatic monomer copolymer, α-methylstyrene / aliphatic monomer copolymer. And a styrene monomer / α-methylstyrene / aliphatic monomer copolymer.

  The resins (D) listed above may be used alone or in combination of two or more. It is preferable that the compounding quantity of resin (D) is 1-30 mass parts with respect to 100 mass parts of diene rubber (A). An improvement effect can be heightened by mix | blending 1 mass part or more. Moreover, the improvement effect of rolling resistance performance can be heightened when a compounding quantity is 30 mass parts or less. The blending amount of the resin (D) is more preferably 3 to 20 parts by mass, still more preferably 5 to 15 parts by mass.

  A silane coupling agent may be blended with the rubber composition according to the present embodiment in order to further improve the dispersibility of silica. The silane coupling agent is not particularly limited. For example, sulfide silane coupling agents such as bis (3-triethoxysilylpropyl) tetrasulfide and bis (3-triethoxysilylpropyl) disulfide; 3-mercaptopropyltrimethoxy Examples thereof include mercaptosilane coupling agents such as silane and 3-mercaptopropyltriethoxysilane; protected mercaptosilane coupling agents such as 3-octanoylthio-1-propyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane. These can be used alone or in combination of two or more. Although the compounding quantity of a silane coupling agent is not specifically limited, It is preferable that it is 2-25 mass parts with respect to 100 mass parts of silica.

  You may mix | blend oil, such as process oil, with the rubber composition which concerns on this embodiment. Although the compounding quantity of oil is not specifically limited, For example, it is 5-60 mass parts by the total amount with the said modified | denatured liquid diene polymer (C) with respect to 100 mass parts of diene rubber (A). Preferably, it is 10-50 mass parts.

  In the rubber composition according to the present embodiment, in addition to the above-described components, various types of rubber compositions generally used in rubber compositions such as zinc white, stearic acid, anti-aging agent, wax, vulcanizing agent, and vulcanization accelerator. Additives can be blended. Examples of the vulcanizing agent include sulfur components such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. Although not particularly limited, the blending amount thereof is 100 parts by mass of diene rubber. It is preferable that it is 0.1-10 mass parts with respect to it, More preferably, it is 0.5-5 mass parts.

  The rubber composition according to the embodiment can be prepared by kneading according to a conventional method using a commonly used Banbury mixer, kneader, roll, or other mixer. That is, in the first mixing stage, other additives except the vulcanizing agent and the vulcanization accelerator are added and mixed with the rubber component in the first mixing stage, and then the vulcanizing agent is added to the obtained mixture in the final mixing stage. And a rubber composition can be prepared by adding and mixing a vulcanization accelerator.

  The rubber composition thus obtained can be used for various rubber members for tires, vibration-proof rubbers, conveyor belts and the like. It is preferably used for tires, and can be applied to various parts of tires such as tread parts and sidewall parts of various sizes of tires for passenger cars, trucks and buses, and pneumatic tires of sizes. According to a conventional method, the rubber composition is molded into a predetermined shape by, for example, extrusion, and combined with other components, and then vulcanized at, for example, 140 to 180 ° C. to produce a pneumatic tire. it can. Among these, it is particularly preferable to use as a tire tread formulation.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  Using a Banbury mixer, according to the formulation (parts by mass) shown in Table 1 below, first, in the first mixing stage, other compounding agents except for sulfur and vulcanization accelerator are added to the diene rubber component and kneaded ( (Discharge temperature = 160 ° C.) Then, sulfur and a vulcanization accelerator were added and kneaded to the obtained kneaded product in the final mixing stage (discharge temperature = 90 ° C.) to prepare a rubber composition. As a common composition other than the composition shown in Table 1, each rubber composition has a zinc flower ("Zinc Flower No. 1" manufactured by Mitsui Metal Mining Co., Ltd.) of 3.0 mass with respect to 100 parts by mass of the diene rubber. Part, anti-aging agent (Ouchi Shinsei Chemical Co., Ltd. “NOCRACK 6C”) 2.0 parts by mass, stearic acid (“LUNAC S20” manufactured by Kao Corporation) 2.0 parts by mass, wax (Nippon Seiki ( Co., Ltd. “OZOACE0355”) 2.0 parts by mass was blended. The details of each component in Table 1 are as follows.

Modified SBR: amino group and alkoxy group terminal modified solution polymerized styrene butadiene rubber, “HPR350” manufactured by JSR Corporation (glass transition temperature (Tg) = − 35 ° C., styrene content (St) = 21 mass%, vinyl content (Vi ) = 56 mol%)
-BR: “BR150B” manufactured by Ube Industries, Ltd.
・ Silica: “Nip seal AQ” manufactured by Tosoh Silica Co., Ltd. (BET = 205 m ² / g)
Silane coupling agent: bis (3-triethoxysilylpropyl) tetrasulfide, “Si69” manufactured by Evonik Degussa
Carbon black: “Dia Black N339” manufactured by Mitsubishi Chemical Corporation
・ Process oil: Japan Energy “JOMO Process NC140”
・ Sulfur: “5% oil-filled fine powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.
・ Vulcanization accelerator: “Soxinol CZ” manufactured by Sumitomo Chemical Co., Ltd.
Rosin resin: rosin-modified maleic resin (softening point: 100 to 110 ° C.), “Harimak R100” manufactured by Harima Kasei Co., Ltd.
Petroleum resin: Aliphatic / aromatic copolymer petroleum resin (softening point: 95 ° C.), “Petrotac 90” manufactured by Tosoh Corporation
Styrene resin: Styrene monomer / aliphatic monomer copolymer (softening point: 125 ° C.), “FTR6125” manufactured by Mitsui Chemicals, Inc.
・ Isocyanate silane: 3-isocyanatopropyltriethoxysilane, “KBE-9007” manufactured by Shin-Etsu Chemical Co., Ltd.
Aminosilane: 3-aminopropyltriethoxysilane, “KBE-903” manufactured by Shin-Etsu Chemical Co., Ltd.
-Low molecular weight liquid polymer: Liquid polybutadiene, "Ricon 130" (Mn: 2500) manufactured by Clay Valley
・ High molecular weight liquid polymer 1: Liquid polybutadiene, “LBR307” (Mn: 8000) manufactured by Kuraray Co., Ltd.
High molecular weight liquid polymer 2: Hydroxyl-terminated liquid polybutadiene, “Krasol LBH5000” (Mn: 5000), manufactured by Clay Valley
-High molecular weight liquid polymer 3: Carboxyl group-containing liquid polyisoprene, "LIR410" (Mn: 30000) manufactured by Kuraray Co., Ltd.
High molecular weight liquid polymer 4: Liquid polyisoprene containing maleic anhydride group, “LIR403” (Mn: 34000) manufactured by Kuraray Co., Ltd.

Modified low molecular weight liquid polymer: Hydroxyl-terminated liquid polybutadiene (“R-45HT” manufactured by Idemitsu Kosan Co., Ltd., Mn: 2800) 100 g, 3-isocyanatopropyltriethoxysilane (“KBE-9007” manufactured by Shin-Etsu Chemical Co., Ltd.) ] 18g was put into the temperature control container with a stirring function, 0.5 g of dibutyltin dilaurate ("KS-1260" by Kyodo Chemical Co., Ltd.) was added and mixed, and it was made to react at 70 degreeC for 10 minutes. As a result, the hydroxyl groups at both ends of the liquid polybutadiene reacted with the isocyanate groups of the isocyanate silane, and alkoxysilyl groups were introduced via urethane bonds (the number of modified groups introduced was about 2 per molecule).

・ Modified high molecular weight liquid polymer 1: 100 g of hydroxyl-terminated liquid polybutadiene (“Krasol LBH5000” manufactured by Clay Valley, Mn: 5000) and 10 g of 3-isocyanatopropyltriethoxysilane (“KBE-9007” manufactured by Shin-Etsu Chemical Co., Ltd.) Into a temperature-controlled container with a stirring function, 0.05 g of dibutyltin dilaurate (“KS-1260” manufactured by Kyodo Yakuhin Co., Ltd.) was added while mixing and reacted at 90 ° C. for 40 minutes. As a result, the hydroxyl groups at both ends of the liquid polybutadiene reacted with the isocyanate groups of the isocyanate silane, and alkoxysilyl groups were introduced via urethane bonds (the number of modified groups introduced was about 2 per molecule).

Modified high molecular weight liquid polymer 2: Hydroxyl-terminated liquid polybutadiene (“Krasol LBH5000” manufactured by Clay Valley, Mn: 5000) 100 g and hexamethylene diisocyanate (HDI, “Takenate 700” manufactured by Mitsui Chemicals, Inc.) 7 g of temperature with stirring function 0.05 g of dibutyltin dilaurate (“KS-1260” manufactured by Kyodo Yakuhin Co., Ltd.) was added while mixing and mixing, and the mixture was reacted at 120 ° C. for 1 hour. Thereby, the hydroxyl group part of the both ends of liquid polybutadiene and the isocyanate group of HDI reacted, and the isocyanate group was introduce | transduced through the urethane bond. Then, 10 g of 3-aminopropyltriethoxysilane (“KBE-903” manufactured by Shin-Etsu Chemical Co., Ltd.) was added and reacted at 80 ° C. for 2 hours. As a result, the terminal isocyanate group and the amino group of aminosilane reacted to introduce an alkoxysilyl group via a urea bond (the introduction amount of modifying groups was about 2 per molecule).

-Modified high molecular weight liquid polymer 3: Carboxyl group-containing liquid polyisoprene ("LIR410" manufactured by Kuraray Co., Ltd., Mn: 30000, number of functional groups per molecule: 10) and 3-isocyanatopropyltriethoxysilane (Shin-Etsu) 8 g of chemical industry (“KBE-9007”) is added to a temperature-controlled container with stirring function, and 0.05 g of dibutyltin dilaurate (“KS-1260” manufactured by Kyodo Yakuhin Co., Ltd.) is added while mixing. The reaction was carried out at 2 ° C. for 2 hours. As a result, the carboxy group incorporated in the molecular chain of the liquid polyisoprene and the isocyanate group of the isocyanate silane reacted to introduce an alkoxysilyl group via an amide bond (the introduction amount of the modifying group was about 10 per molecule). Pieces).

Modified high molecular weight liquid polymer 4: Maleic anhydride group-containing liquid polyisoprene (“LIR403” manufactured by Kuraray Co., Ltd., Mn: 34000, number of functional groups per molecule: 3) 100 g and 3-isocyanatopropyltriethoxysilane ( 2 g of Shin-Etsu Chemical Co., Ltd. “KBE-9007”) in a temperature-controlled container with stirring function, and 0.05 g of dibutyltin dilaurate (“KS-1260” manufactured by Kyodo Yakuhin Co., Ltd.) are added while mixing. The reaction was carried out at 90 ° C. for 1 hour. As a result, the maleic anhydride moiety incorporated in the molecular chain of the liquid polyisoprene and the isocyanate group of the isocyanate silane reacted to introduce an alkoxysilyl group via an imide bond (the amount of the modifying group introduced per molecule). About 3).

  About each obtained rubber composition, the tearing characteristic, wet road braking performance, and rolling resistance performance were evaluated using the test piece of the predetermined shape vulcanized at 160 degreeC for 30 minutes. Each evaluation method is as follows.

・ Tearing characteristics: punched with a crescent shape defined in JIS K6252 and prepared a test sample with a notch of 0.50 ± 0.08 mm in the center of the indentation. The test sample was 500 mm by a tensile tester manufactured by Shimadzu Corporation. The test was conducted at a pulling rate of / min. The value of Comparative Example 1 is expressed as an index with a value of 100. The larger the index, the greater the tearing force and the better the tearing performance.

-Wet road braking performance: According to JIS K6255, a Lupke-type rebound resilience test was performed, and a rebound resilience at 23 ° C. was measured. The reciprocal of the rebound resilience was obtained and indicated as an index with the value of Comparative Example 1 being 100. A larger value means a smaller impact resilience and better wet road braking performance.

Rolling resistance performance: Using a viscoelasticity tester manufactured by Toyo Seiki Co., Ltd., loss factor tan δ was measured under the conditions of frequency 10 Hz, static strain 10%, dynamic strain 1%, and temperature 60 ° C. The reciprocal of tan δ was determined and indicated as an index with the value of Comparative Example 1 being 100. A larger value means lower rolling resistance and better rolling resistance performance (low fuel consumption).

  The results are as shown in Table 1. Compared to Comparative Example 1, which is a control, Comparative Example 2 in which an unmodified low molecular weight liquid diene polymer and a resin are used in combination improves the wet road braking performance, but lowers the tearing property and inferior in rolling resistance performance. It was. In Comparative Example 3, the tear characteristics were improved by using a high molecular weight liquid diene polymer, but the wet road braking performance and the rolling resistance performance were not compatible. In Comparative Examples 4 and 5, a modified liquid diene polymer having an alkoxysilyl group introduced via a urethane bond was used, but because it was a low molecular weight product, wet road braking performance and rolling resistance performance were not compatible, and tear characteristics It was also inferior. In Comparative Example 6, the resin was blended without blending the liquid polymer, and the wet road braking performance was excellent, but the rolling resistance performance was poor. In Comparative Example 7, a high-molecular-weight modified liquid diene polymer was used in place of oil, and the rolling resistance performance was improved. However, since the resin was not blended, the wet road braking performance was inferior. In Comparative Example 8, since the blending amount of the high molecular weight modified liquid diene polymer was too large, the rolling resistance performance was excellent, but the wet road braking performance was deteriorated. However, a decrease in hardness was also observed. In Comparative Example 9, since the amount of the resin was too large, the wet road braking performance was excellent, but the rolling resistance performance was deteriorated.

  On the other hand, in Examples 1 to 6 in which a high molecular weight modified liquid diene polymer and a resin were used in combination, the wet road braking performance and the rolling resistance performance were highly compatible while maintaining the tearing properties. In Example 6, the improvement range of the wet road braking performance is smaller than in Examples 1 to 5, but this is considered to be due to the large molecular weight of the modified liquid diene polymer used.

  In addition, Comparative Examples 10-13 are the rubber composition in the quantity corresponding to each Example with the liquid diene polymer before modification | denaturation used when synthesize | combining the modified | denatured liquid diene polymer of an Example. It is the example added at the time of kneading | mixing. As shown in these Comparative Examples 10 to 13, the excellent effects of the examples were not obtained only by adding them during kneading without being previously modified.

Claims (5)

A diene polymer having 100 parts by mass of a diene rubber, 10 to 150 parts by mass of silica, and at least one group represented by the following general formula (1) in the molecule and having a main chain having a number average molecular weight of 4000 to 50000 A rubber composition containing 1 to 30 parts by mass of a modified liquid diene polymer comprising a chain, and 1 to 30 parts by mass of at least one resin selected from the group consisting of petroleum resins, rosin resins and styrene resins. .

(In the formula ^(1), R 1, ^{R 2} and ^{R 3} each represent an alkyl group or an alkoxy group having 1 to 6 carbon atoms having 1 to 6 carbon atoms, at least one is an alkoxy group .X is Represents a C1-C18 hydrocarbon group which may contain a hetero atom, and Y represents a urethane bond, an amide bond, an imide bond or a urea bond.   The rubber composition according to claim 1, wherein the modified liquid diene polymer is modified liquid polybutadiene and / or modified liquid polyisoprene.   The rubber composition according to claim 1 or 2, wherein X in the general formula (1) is an alkylene group having 1 to 18 carbon atoms. The rubber composition according to any one of claims 1 to 3, wherein -X-Y- in the general formula (1) is represented by any one of the following formulas (2) to (5).

(In formulas (2) to (5), R ⁴ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.)   The pneumatic tire which uses the rubber composition of any one of Claims 1-4.