Modified conjugated diene rubber

Abstract

Provided is a modified conjugated diene rubber having a siloxane compound modified structure at at least one end of a polymer chain containing a conjugated diene monomer unit and a vinyl compound monomer unit containing a functional group capable of interacting with silica.

Description

[Technical field]

[0001] The present invention relates to a modified conjugated diene rubber, and more specifically, to a modified conjugated diene rubber which, when made into a rubber composition, is effectively inhibited from adhering to a roll and which can give a cross-linked rubber product having low heat build-up, excellent wet grip properties, and excellent handling stability. [Background technology]

[0002] In recent years, automobile tires are required to have low fuel consumption due to environmental and resource issues, while excellent wet grip properties are also required from the safety standpoint. A crosslinked product of a rubber composition containing silica as a filler in rubber has excellent low heat build-up properties compared to a crosslinked product of a rubber composition containing carbon black, and therefore has low rolling resistance when used in a tire. Therefore, a tire with excellent fuel consumption can be obtained by using a crosslinked product of a rubber composition containing silica in the tire.

[0003] In order to increase the affinity between rubber and silica in the rubber constituting such a rubber composition, various attempts have been made. For example, Patent Document 1 discusses a technique in which, when obtaining a rubber polymer by a solution polymerization method, a specific polymerization initiator is used to polymerize a monomer component containing a silicon-containing vinyl compound in addition to a conjugated diene compound, thereby giving the rubber itself an affinity with silica. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2013 / 018424 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in view of the increasing performance requirements for automobile tires in recent years, tires newly developed in the future are required to be capable of providing a cross-linked rubber product that is even more excellent in low heat build-up and wet grip properties, as compared with the case where conventional rubbers such as the rubber described in Patent Document 1 are used.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a modified conjugated diene rubber which, when made into a rubber composition, is effectively inhibited from adhering to rolls and which can give a cross-linked rubber product having low heat build-up, excellent wet grip properties, and excellent handling stability. [Means for solving the problem]

[0007] As a result of intensive research by the present inventors in order to achieve the above-mentioned object, they have found that the above-mentioned object can be achieved by a modified conjugated diene rubber obtained by introducing a modified structure with a siloxane compound into at least one end of a polymer chain containing a conjugated diene monomer unit and a monomer unit of a vinyl compound containing a functional group capable of interacting with silica, and have thus completed the present invention.

[0008] That is, according to the present invention, there is provided a modified conjugated diene rubber having a siloxane compound modified structure at at least one end of a polymer chain containing a conjugated diene monomer unit and a monomer unit of a vinyl compound containing a functional group capable of interacting with silica. In the modified conjugated diene rubber of the present invention, the monomer unit of the vinyl compound containing a functional group capable of interacting with silica is preferably a unit represented by the following general formula (1). [ka] (In the above general formula (1), X 1 represents a chemical single bond or a hydrocarbylene group, and X 2 , X 3 and X 4each independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent. In the modified conjugated diene rubber of the present invention, the siloxane compound is preferably a polyorganosiloxane represented by the following general formula (2). [ka] (In the above general formula (2), R 1 ~R 8 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different. X 5 and X 8 is any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, which may be the same or different. 6 is an alkoxy group having 1 to 5 carbon atoms or a group containing an epoxy group and having 4 to 12 carbon atoms; 6 When there are multiple X's, they may be the same or different. 7 is a group containing 2 to 20 repeating alkylene glycol units, X 7 When there are a plurality of, they may be the same or different. m is an integer of 1 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m+n+k is 1 or more.

[0009] According to the present invention, there is provided a method for producing a modified conjugated diene rubber, comprising the steps of: polymerizing, in an inert solvent, a monomer containing a conjugated diene compound and a vinyl compound containing a functional group capable of interacting with silica to obtain a conjugated diene polymer chain having an active end; and reacting a siloxane compound with the active end of the conjugated diene polymer chain having an active end.

[0010] According to the present invention, there is also provided a rubber composition comprising a rubber component containing any one of the modified conjugated diene rubbers described above and silica. The rubber composition of the present invention preferably further contains a crosslinking agent.

[0011] Furthermore, according to the present invention, there are provided a cross-linked rubber product obtained by cross-linking the above rubber composition, and a tire comprising the cross-linked rubber product. Effect of the Invention

[0012] According to the present invention, it is possible to provide a modified conjugated diene rubber which, when made into a rubber composition, is effectively inhibited from adhering to a roll and which can give a cross-linked rubber product having excellent low heat build-up, wet grip properties, and handling stability. Also, according to the present invention, it is possible to provide a method for producing such a modified conjugated diene rubber, and a rubber composition, a cross-linked rubber product, and a tire using such a modified conjugated diene rubber. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <Modified conjugated diene rubber> The modified conjugated diene rubber of the present invention has a modified structure with a siloxane compound at at least one end of a polymer chain containing a conjugated diene monomer unit and a monomer unit of a vinyl compound containing a functional group capable of interacting with silica.

[0014] According to such a modified conjugated diene rubber of the present invention, when it is made into a rubber composition, adhesion to rolls is effectively suppressed, and a cross-linked rubber product having low heat buildup, excellent wet grip properties, and excellent handling stability can be obtained. In particular, the present inventors have conducted intensive research into further improving low heat buildup and wet grip properties in light of the increasing performance requirements for automobile tires in recent years, and have found that by copolymerizing a vinyl compound containing a functional group capable of interacting with silica with a conjugated diene compound and introducing a modified structure with a siloxane compound into at least one end of the polymer chain, the affinity for fillers such as silica can be further improved, thereby further improving low heat buildup and wet grip properties, and further improving not only low heat buildup and wet grip properties but also steering stability.In particular, steering stability can be improved by fully exerting the reinforcing properties of fillers such as silica, and it is believed that this is due to the fact that the reinforcing properties of fillers such as silica can be fully exerted by adopting the above-mentioned configuration.

[0015] In addition to the above, the inventors have also found through their research that the modified conjugated diene rubber of the present invention having the above-mentioned configuration has an unexpected effect that is completely different from the improvement of low heat buildup and wet grip properties, that is, when a filler such as silica is blended into a rubber composition and the rubber composition is processed into a sheet shape using a roll, adhesion to the roll can be effectively suppressed. In particular, when the rubber composition is processed into a sheet shape using a roll, adhesion to the roll can be effectively suppressed, thereby realizing better processability.

[0016] The conjugated diene compound for forming the conjugated diene monomer unit is not particularly limited, but may include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, etc. Among these, 1,3-butadiene and isoprene are preferred. These conjugated diene compounds may be used alone or in combination of two or more.

[0017] The content ratio of the conjugated diene monomer unit in the polymer chain constituting the modified conjugated diene rubber of the present invention is not particularly limited, but is preferably 50 to 99.99% by weight, more preferably 55 to 94.98% by weight, further preferably 60 to 89.95% by weight, and particularly preferably 65 to 84.90% by weight. By setting the content ratio of the conjugated diene monomer unit in the above range, the production of the modified conjugated diene rubber becomes easy.

[0018] The vinyl compound containing a functional group capable of interacting with silica for forming a monomer unit of a vinyl compound containing a functional group capable of interacting with silica is not particularly limited, as long as it is a compound containing a functional group capable of interacting with silica and a vinyl group. Here, the functional group capable of interacting with silica is a functional group capable of forming a covalent bond between the functional group and the silica surface, or a molecular force weaker than a covalent bond (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.). Such a functional group capable of interacting with silica is not particularly limited, but includes a nitrogen atom-containing functional group, a silicon atom-containing functional group, an oxygen atom-containing functional group, etc., and among these, a silicon atom-containing functional group is preferred from the viewpoint of high interaction with silica. That is, as the vinyl compound containing a functional group capable of interacting with silica, it is preferable to use a vinyl compound containing a silicon atom-containing functional group, and by using a vinyl compound containing a silicon atom-containing functional group, a monomer unit of a vinyl compound containing a silicon atom-containing functional group can be introduced into the modified conjugated diene rubber.

[0019] As described above, the monomer unit of the vinyl compound containing a functional group capable of interacting with silica is not particularly limited as long as it is a monomer unit derived from a vinyl compound containing a functional group capable of interacting with silica. However, from the viewpoint of further improving low heat generation and wet grip properties, it is preferably a monomer unit of a vinyl compound containing a silicon atom-containing functional group, and more preferably a unit represented by the following general formula (1). [ka] In the above general formula (1), X 1 represents a chemical single bond or a hydrocarbylene group, and X 2 , X 3 and X 4 each independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0020] The unit represented by the above general formula (1) can be formed, for example, by using a vinyl compound containing a silicon atom-containing functional group represented by the following general formula (3). [ka] In the above general formula (3), X 9 represents a chemical single bond or a hydrocarbylene group, and X 10 , X 11 and X 12 each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0021] In the unit represented by the general formula (1), X 1 is X in the compound represented by the above general formula (3). 9 In the unit represented by the general formula (1), X 2 , X 3 and X 4 is X in the compound represented by the above general formula (3). 10 , X 11 and X 12 Therefore, in the unit represented by the above general formula (1), X 1 , X 2 , X 3 and X 4 is X in the compound represented by the above general formula (3). 9 , X 10 , X 11 and X 12 In addition, the compound represented by the above general formula (3) may be the same as X 10 , X 11 and X 12 In the case where at least one of X is a substituted amino group or a hydrocarbyloxy group, the substituted amino group or the hydrocarbyloxy group can be hydrolyzed at any step and timing to obtain X 10 , X 11 and X 12 At least one of the groups may be a hydroxyl group.

[0022] In the above general formula (3), X 9 is a chemical single bond or a hydrocarbylene group, preferably a chemical single bond. Examples of the hydrocarbylene group include an alkylene group, an alkenediyl group, an arylene group, and a group in which an arylene group and an alkylene group are bonded together. Examples of the alkylene group include a methylene group, an ethylene group, and a trimethylene group. Examples of the alkene diyl group include a vinylene group and an ethylene-1,1-diyl group. Examples of the arylene group include a phenylene group, a naphthylene group, and a biphenylene group. Examples of the group in which an arylene group and an alkylene group are bonded include a group in which a phenylene group and a methylene group are bonded, and a group in which a phenylene group and an ethylene group are bonded. X 9 When X is a hydrocarbylene group, 9 is preferably an arylene group, more preferably a phenylene group.

[0023] In the above general formula (3), X 10 , X 11 and X 12 each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent. X 10 , X 11 and X 12 At least one of X is preferably a substituted amino group. 10 , X 11 and X 12 It is more preferable that two of them are substituted amino groups.

[0024] X 10 , X 11 and X 12 As the substituted amino group which can constitute the above, a group represented by the following general formula (4) is preferable. [ka] In the above general formula (4), R 9 and R 10may or may not be bonded to each other, R 9 and R 10 If they are not bonded to each other, R 9 and R 10 each independently represents a hydrocarbyl group which may have a substituent or a trihydrocarbylsilyl group; R 9 and R 10 When and are bonded to each other, R 9 and R 10 represents a hydrocarbylene group which may contain nitrogen and / or oxygen atoms.

[0025] R 9 and R 10 Examples of the hydrocarbyl group that can constitute the above include chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and n-octyl groups; cyclic alkyl groups such as cyclopentyl and cyclohexyl groups; and aryl groups such as phenyl, benzyl, and naphthyl groups. Among these, chain alkyl groups are preferred, and methyl or ethyl groups are more preferred. R 9 and R 10 When the hydrocarbyl group that can constitute the above has a substituent, examples of the hydrocarbyl group include a hydrocarbyloxy group as a substituent. Examples of the hydrocarbyl group having a hydrocarbyloxy group as a substituent include alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and a methoxyethyl group; and aryloxyalkyl groups such as a phenoxymethyl group.

[0026] R 9 and R 10 Specific examples of the trihydrocarbylsilyl group that can constitute the above group include trialkylsilyl groups such as a trimethylsilyl group, a triethylsilyl group, and a tert-butyldimethylsilyl group.

[0027] R 9 and R 10When and are bonded to each other, R 9 and R 10 Examples of the hydrocarbylene group that can constitute R include alkylene groups such as trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene, and 2,2,4-trimethylhexane-1,6-diyl; and alkene diyl groups such as pentan-2-ene-1,5-diyl. 9 and R 10 When the hydrocarbylene group that can constitute the above formula contains a nitrogen atom and / or an oxygen atom, examples of the hydrocarbylene group containing a nitrogen atom and / or an oxygen atom include a group represented by -CH=N-CH=CH-, a group represented by -CH=N-CH2-CH2-, a group represented by -CH2-CH2-O-CH2-CH2-, and the like. R 9 and R 10 is an alkyl group, or R 9 and R 10 and R are preferably bonded to each other to form an alkylene group. 9 and R 10 is more preferably an alkyl group, and R 9 and R 10 is more preferably a methyl group or an ethyl group.

[0028] In the above general formula (4), R 9 and R 10 When is a hydrocarbyl group, specific examples of the group represented by the above general formula (4) include dialkylamino groups such as dimethylamino group, diethylamino group, ethylmethylamino group, di-n-propylamino group, diisopropylamino group, di-n-butylamino group, diisobutylamino group, di-sec-butylamino group, and di-tert-butylamino group; diarylamino groups such as diphenylamino group; etc. Among these, dialkylamino groups are preferred, and dimethylamino group, diethylamino group, and di-n-butylamino group are more preferred.

[0029] In the above general formula (4), R 9 and R 10 In the case where is a hydrocarbyl group having a hydrocarbyloxy group as a substituent, specific examples of the group represented by the above general formula (4) include di(alkoxyalkyl)amino groups such as di(methoxymethyl)amino and di(ethoxymethyl)amino.

[0030] In the above general formula (4), R 9 and R 10 When is a trihydrocarbylsilyl group, specific examples of the group represented by the above general formula (4) include trialkylsilyl group-containing amino groups such as a bis(trimethylsilyl)amino group, a bis(tert-butyldimethylsilyl)amino group, and an N-trimethylsilyl-N-methylamino group.

[0031] In the above general formula (4), R 9 and R 10 and 1-(2-methylphenyl)-1-propanediyl group are bonded to each other to form a hydrocarbylene group. Specific examples of the group represented by general formula (4) above include 1-alkyleneimino groups such as a 1-trimethyleneimino group, a 1-pyrrolidino group, a 1-piperidino group, a 1-hexamethyleneimino group, a 1-heptamethyleneimino group, a 1-octamethyleneimino group, a 1-decamethyleneimino group, and a 1-dodecamethyleneimino group.

[0032] In the above general formula (4), R 9 and R 10 and are bonded to each other to form a hydrocarbylene group containing a nitrogen atom and / or an oxygen atom, specific examples of the group represented by the above general formula (4) include a 1-imidazolyl group, a 4,5-dihydro-1-imidazolyl group, and a morpholino group.

[0033] As the group represented by the above general formula (4), a dialkylamino group or a 1-alkyleneimino group is preferable, a dialkylamino group is more preferable, and a dimethylamino group, a diethylamino group or a di-n-butylamino group is even more preferable.

[0034] In the above general formula (3), X 10 , X 11 and X 12 Examples of hydrocarbyloxy groups that can constitute the above formula include alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, and tert-butoxy groups; aryloxy groups such as phenoxy and benzyloxy groups; and the like.

[0035] In the above general formula (3), X 10 , X 11 and X 12 Examples of hydrocarbyl groups that can constitute the above formula include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl groups; and aryl groups such as phenyl, 4-methyl-1-phenyl, and benzyl groups. X 10 , X 11 and X 12 When the hydrocarbyl group that can constitute the above has a substituent, examples of the substituent include hydrocarbyl groups having a hydrocarbyloxy group, such as alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and an ethoxyethyl group.

[0036] In the above general formula (3), X 9 is a chemical single bond, and X 10 , X 11 and X 12Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (3) in the case where one of the above is a substituted amino group include (dialkylamino)dialkylvinylsilanes such as (dimethylamino)dimethylvinylsilane, (ethylmethylamino)dimethylvinylsilane, (di-n-propylamino)dimethylvinylsilane, (diisopropylamino)dimethylvinylsilane, (dimethylamino)diethylvinylsilane, (ethylmethylamino)diethylvinylsilane, (di-n-propylamino)diethylvinylsilane, and (diisopropylamino)diethylvinylsilane; [bis(trimethylsilyl)amino]dimethylvinylsilane, [bis(t-butyldimethylsilyl)amino]dimethylvinylsilane, [bis(trimethylsilyl)amino]diethylvinylsilane, and [bis(t-butyldimethylsilyl)amino]diethylvinylsilane; (dimethylamino)di(methoxymethyl)vinylsilane, (dimethylamino)di(methoxyethyl)vinylsilane, (dimethylamino)di(ethoxymethyl)vinylsilane, (dimethylamino)di(ethoxyethyl)vinylsilane, (diethylamino)di(methoxymethyl)vinylsilane, (diethylamino)di(methoxyethyl)vinylsilane, (diethylamino)di(ethoxymethyl)vinylsilane, (diethylamino)di(ethoxyethyl)vinylsilane and other (dialkylamino)di(alkoxyalkyl)vinylsilanes; pyrrolidinodimethylvinylsilane, piperidinodimethylvinylsilane, hexamethyleneiminodimethylvinylsilane, 4,5-dihydroimidazolyldimethylvinylsilane, morpholinodimethylvinylsilane and other cyclic aminodialkylvinylsilane compounds;

[0037] In the above general formula (3), X 9 is a hydrocarbylene group, and X 10 , X 11 and X 12Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (3) in which one of the groups is a substituted amino group include (dimethylamino)dimethyl-4-vinylphenylsilane, (dimethylamino)dimethyl-3-vinylphenylsilane, (diethylamino)dimethyl-4-vinylphenylsilane, (diethylamino)dimethyl-3-vinylphenylsilane, (di-n-propylamino)dimethyl-4-vinylphenylsilane, (di-n-propylamino)dimethyl-3-vinylphenylsilane, (di-n-butylamino)dimethyl-4-vinylphenylsilane, (di-n-butylamino)dimethyl- and (dialkylamino)dialkylvinylphenylsilanes such as (dialkylamino)diethyl-3-vinylphenylsilane, (dimethylamino)diethyl-4-vinylphenylsilane, (dimethylamino)diethyl-3-vinylphenylsilane, (diethylamino)diethyl-4-vinylphenylsilane, (diethylamino)diethyl-3-vinylphenylsilane, (di-n-propylamino)diethyl-4-vinylphenylsilane, (di-n-propylamino)diethyl-3-vinylphenylsilane, (di-n-butylamino)diethyl-4-vinylphenylsilane, and (di-n-butylamino)diethyl-3-vinylphenylsilane.

[0038] In the above general formula (3), X 9 is a chemical single bond, and X 10 , X 11 and X 12Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (3) in the case where two of the above are substituted amino groups include bis(dialkylamino)alkylvinylsilanes such as bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, bis(di-n-propylamino)methylvinylsilane, bis(di-n-butylamino)methylvinylsilane, bis(dimethylamino)ethylvinylsilane, bis(diethylamino)ethylvinylsilane, bis(di-n-propylamino)ethylvinylsilane, and bis(di-n-butylamino)ethylvinylsilane; bis[bis(trimethylsilyl)amino]methylvinylsilane, bis[bis(tert-butyldimethylsilyl)amino]methylvinylsilane, bis[bis(trimethylsilyl)amino]ethylvinylsilane, and bis[bis(tert-butyldimethylsilyl)amino]ethylvinylsilane. which bis[bis(trialkylsilyl)amino]alkylvinylsilanes; bis(dialkylamino)alkoxyalkylsilanes such as bis(dimethylamino)methoxymethylvinylsilane, bis(dimethylamino)methoxyethylvinylsilane, bis(dimethylamino)ethoxymethylvinylsilane, bis(dimethylamino)ethoxyethylvinylsilane, bis(diethylamino)methoxymethylvinylsilane, bis(diethylamino)methoxyethylvinylsilane, bis(diethylamino)ethoxymethylvinylsilane, and bis(dimethylamino)ethoxyethylvinylsilane; bis(cyclic amino)alkylvinylsilane compounds such as bis(pyrrolidino)methylvinylsilane, bis(piperidino)methylvinylsilane, bis(hexamethyleneimino)methylvinylsilane, bis(4,5-dihydroimidazolyl)methylvinylsilane, and bis(morpholino)methylvinylsilane; and the like.

[0039] In the above general formula (3), X 9 is a hydrocarbylene group, and X 10 , X 11 and X 12Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (3) in the case where two of the above are substituted amino groups include bis(dimethylamino)methyl-4-vinylphenylsilane, bis(dimethylamino)methyl-3-vinylphenylsilane, bis(diethylamino)methyl-4-vinylphenylsilane, bis(diethylamino)methyl-3-vinylphenylsilane, bis(di-n-propylamino)methyl-4-vinylphenylsilane, bis(di-n-propylamino)methyl-3-vinylphenylsilane, bis(di-n-butylamino)methyl-4-vinylphenylsilane, bis(di-n-butylamino)methyl- and bis(dialkylamino)alkylvinylphenylsilanes such as bis(dimethylamino)ethyl-3-vinylphenylsilane, bis(dimethylamino)ethyl-4-vinylphenylsilane, bis(dimethylamino)ethyl-3-vinylphenylsilane, bis(diethylamino)ethyl-4-vinylphenylsilane, bis(diethylamino)ethyl-3-vinylphenylsilane, bis(di-n-propylamino)ethyl-4-vinylphenylsilane, bis(di-n-propylamino)ethyl-3-vinylphenylsilane, bis(di-n-butylamino)ethyl-4-vinylphenylsilane, and bis(di-n-butylamino)ethyl-3-vinylphenylsilane.

[0040] In the above general formula (3), X 9 is a chemical single bond, and X 10 , X 11 and X 12 Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (3) in the case where three of the above are substituted amino groups include tris(dialkylamino)vinylsilanes such as tris(dimethylamino)vinylsilane, tris(diethylamino)vinylsilane, tris(di-n-propylamino)vinylsilane, and tris(di-n-butylamino)vinylsilane.

[0041] In the above general formula (3), X 9 is a hydrocarbylene group, and X 10 , X 11 and X 12Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (3) in the case where three of them are substituted amino groups include tris(dialkylamino)vinylphenylsilanes such as tris(dimethylamino)-4-vinylphenylsilane, tris(dimethylamino)-3-vinylphenylsilane, tris(diethylamino)-4-vinylphenylsilane, tris(diethylamino)-3-vinylphenylsilane, tris(di-n-propylamino)-4-vinylphenylsilane, tris(di-n-propylamino)-3-vinylphenylsilane, tris(di-n-butylamino)-4-vinylphenylsilane, and tris(di-n-butylamino)-3-vinylphenylsilane.

[0042] In the above general formula (3), X 9 is a chemical single bond, and X 10 , X 11 and X 12 Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (3), in which none of the above groups is a substituted amino group, include trialkoxyvinylsilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, and tripropoxyvinylsilane; dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane and methyldiethoxyvinylsilane; dialkoxyarylvinylsilanes such as di(tert-pentoxy)phenylvinylsilane and di(tert-butoxy)phenylvinylsilane; monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane; monoalkoxydiarylvinylsilanes such as tert-butoxydiphenylvinylsilane and tert-pentoxydiphenylvinylsilane; monoalkoxyalkylarylvinylsilanes such as tert-butoxymethylphenylvinylsilane and tert-butoxyethylphenylvinylsilane; and substituted alkoxyvinylsilane compounds such as tris(β-methoxyethoxy)vinylsilane.

[0043] Among the compounds represented by the above general formula (3), X 9 is preferably a chemical single bond, and X9 is a chemical single bond and X 10 , X 11 and X 12 Among these, a compound in which two are substituted amino groups is more preferred, and X 9 is a chemical single bond and X 10 , X 11 and X 12 Among these, a compound in which two of the groups are dialkylamino groups is particularly preferred.

[0044] Among the compounds represented by the above general formula (3), bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, and bis(di-n-butylamino)methylvinylsilane are preferred, with bis(diethylamino)methylvinylsilane being particularly preferred.

[0045] In addition, vinyl compounds containing functional groups capable of interacting with silica other than the compound represented by the general formula (3) include bis(trialkylsilyl)aminostyrenes such as 4-N,N-bis(trimethylsilyl)aminostyrene and 3-N,N-bis(trimethylsilyl)aminostyrene; bis(trialkylsilyl)aminoalkylstyrenes such as 4-bis(trimethylsilyl)aminomethylstyrene, 3-bis(trimethylsilyl)aminomethylstyrene, 4-bis(trimethylsilyl)aminoethylstyrene and 3-bis(trimethylsilyl)aminoethylstyrene; pyrrolidinoethylstyrene, among which pyrrolidinoethylstyrene is preferred. Note that pyrrolidinoethylstyrene may be any of ortho, meta, and para, but meta and para are preferred, and a mixture of meta and para is more preferred.

[0046] In the polymer chain constituting the modified conjugated diene rubber of the present invention, the content ratio of the monomer unit of the vinyl compound containing a functional group capable of interacting with silica is preferably 0.01 to 20% by weight, more preferably 0.02 to 2% by weight, further preferably 0.05 to 1% by weight, and particularly preferably 0.1 to 0.8% by weight. By setting the content ratio of the monomer unit of the vinyl compound containing a functional group capable of interacting with silica within such a range, the effect of suppressing adhesion to the roll, and the effect of improving low heat generation, wet grip property, and steering stability can be more remarkable.

[0047] From the viewpoint of being able to further improve the low heat generation and wet grip properties when made into a cross-linked rubber, the modified conjugated diene rubber of the present invention preferably contains an aromatic vinyl monomer unit in addition to the conjugated diene monomer unit and the monomer unit of a vinyl compound containing a functional group capable of interacting with silica.

[0048] Examples of aromatic vinyl compounds for forming aromatic vinyl monomer units include styrene, methylstyrene, ethylstyrene, t-butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, chlorostyrene, bromostyrene, methoxystyrene, dimethylaminomethylstyrene, dimethylaminoethylstyrene, diethylaminomethylstyrene, diethylaminoethylstyrene, cyanoethylstyrene, vinylnaphthalene, etc. Among these, styrene is preferred.

[0049] The content of aromatic vinyl monomer units in the polymer chain constituting the modified conjugated diene rubber of the present invention is preferably 49.99% by weight or less, more preferably 5 to 44.98% by weight, further preferably 10 to 39.95% by weight, and particularly preferably 15 to 34.90% by weight. By setting the content of aromatic vinyl monomer units in such a range, the effect of improving low heat build-up and wet grip properties can be further enhanced.

[0050] In addition, the modified conjugated diene rubber of the present invention may contain other monomer units other than the conjugated diene monomer units, the monomer units of vinyl compounds containing functional groups capable of interacting with silica, and the aromatic vinyl monomer units. Examples of other compounds constituting such other monomer units include linear olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; non-conjugated diene compounds such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene; and the like. The content ratio of other monomer units in the polymer chain constituting the modified conjugated diene rubber of the present invention is preferably 10% by weight or less, more preferably 5% by weight or less.

[0051] The modified conjugated diene rubber of the present invention is obtained by introducing a modified structure by a siloxane compound into at least one end of a polymer chain containing the units of each of the above-mentioned monomers. The modified structure by the siloxane compound may be introduced via a modified structure by another modifier.

[0052] The siloxane compound is not particularly limited as long as it has a siloxane structure (-Si-O-) as the main chain, but is preferably an organosiloxane having an organic group on the side chain, and more preferably a polyorganosiloxane represented by the following general formula (2). [ka] In the above general formula (2), R 1 ~R 8 is an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different. X 5 and X 8 is any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, which may be the same or different. 6is an alkoxy group having 1 to 5 carbon atoms or a group containing an epoxy group and having 4 to 12 carbon atoms; 6 When there are multiple X's, they may be the same or different. 7 is a group containing 2 to 20 repeating alkylene glycol units, X 7 When there are a plurality of m, they may be the same or different. m is an integer of 1 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m+n+k is 1 or more.

[0053] In the polyorganosiloxane represented by the above general formula (2), R 1 ~R 8 , X 5 and X 8 Examples of the alkyl group having 1 to 6 carbon atoms that can constitute the above include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these, from the viewpoint of ease of production of the polyorganosiloxane itself, a methyl group and an ethyl group are preferred.

[0054] In addition, in the polyorganosiloxane represented by the above general formula (2), X 5 , X 6 and X 8 Examples of the alkoxy group having 1 to 5 carbon atoms that can constitute the above include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. Among these, from the viewpoint of ease of production of the polyorganosiloxane itself, a methoxy group and an ethoxy group are preferred.

[0055] Furthermore, in the polyorganosiloxane represented by the above general formula (2), X 5 , X 6 and X 8 Examples of the epoxy group-containing group having 4 to 12 carbon atoms that can constitute the above formula include groups represented by the following general formula (5). -Z1 -Z 2 -E (5) In the above general formula (5), Z 1 is an alkylene group or an alkylarylene group having 1 to 10 carbon atoms; Z 2 is a methylene group, a sulfur atom, or an oxygen atom, and E is a hydrocarbon group having 2 to 10 carbon atoms and an epoxy group.

[0056] The group represented by the above general formula (5) is Z 2 is preferably an oxygen atom, and Z 2 is an oxygen atom and E is a glycidyl group, 1 is an alkylene group having 1 to 3 carbon atoms, and Z 2 It is particularly preferred that R is an oxygen atom and E is a glycidyl group.

[0057] In addition, in the polyorganosiloxane represented by the above general formula (2), X 5 and X 8 Among the above, X is preferably a group containing an epoxy group and having 4 to 12 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. 6 Among the above, an epoxy group-containing group having 4 to 12 carbon atoms is preferable. 5 and X 8 is an alkyl group having 1 to 6 carbon atoms, and X 6 It is more preferable that the group is an epoxy group-containing group having 4 to 12 carbon atoms.

[0058] In addition, in the polyorganosiloxane represented by the above general formula (2), X 7 That is, as a group containing 2 to 20 repeating units of alkylene glycol, a group represented by the following general formula (6) is preferred. [ka] In the above general formula (6), t is an integer of 2 to 20, and X 13 is an alkylene group or alkylarylene group having 2 to 10 carbon atoms, R 11 is a hydrogen atom or a methyl group, and X14 is an alkoxy group or an aryloxy group having 1 to 10 carbon atoms. Among these, t is an integer of 2 to 8, and X 13 is an alkylene group having 3 carbon atoms, and R 11 is a hydrogen atom and X 14 is preferably a methoxy group.

[0059] In the polyorganosiloxane represented by the general formula (2), m is an integer of 1 to 200, preferably an integer of 20 to 150, and more preferably an integer of 30 to 120. When m is 1 to 200, the polyorganosiloxane represented by the general formula (2) itself becomes easier to produce, and the viscosity does not become too high, making it easier to handle.

[0060] In the polyorganosiloxane represented by the general formula (2), n is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 120. k is an integer of 0 to 200, preferably an integer of 0 to 150, more preferably an integer of 0 to 130. The total number of m, n, and k is 1 or more, preferably 1 to 400, more preferably 20 to 300, and particularly preferably 30 to 250. When the total number of m, n, and k is 1 or more, the reaction between the polyorganosiloxane represented by the general formula (2) and the conjugated diene polymer chain having an active terminal is easily progressed, and when the total number of m, n, and k is 400 or less, the polyorganosiloxane represented by the general formula (2) itself is easily produced, and the viscosity does not become too high, making it easy to handle.

[0061] The method for producing the modified conjugated diene rubber of the present invention is not particularly limited, but may, for example, include a step of polymerizing, in an inert solvent, a monomer containing a conjugated diene compound and a vinyl compound containing a functional group capable of interacting with silica to obtain a conjugated diene polymer chain having an active end; and reacting a siloxane compound with the active end of the conjugated diene polymer chain having the active end.

[0062] The inert solvent used in the polymerization is not particularly limited as long as it is one that is usually used in solution polymerization and does not inhibit the polymerization reaction. Specific examples of the inert solvent include linear or branched aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, and n-heptane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, ethylbenzene, toluene, and xylene; and ether compounds such as tetrahydrofuran and diethyl ether. These inert solvents may be used alone or in combination of two or more. The amount of the inert solvent used is not particularly limited, but is, for example, an amount that provides a monomer concentration of 1 to 50% by weight, and preferably an amount that provides a monomer concentration of 5 to 40% by weight.

[0063] The polymerization initiator used in the polymerization is not particularly limited as long as it can polymerize a monomer containing a conjugated diene compound and a vinyl compound containing a functional group capable of interacting with silica to give a conjugated diene polymer chain having an active end. Specific examples of the polymerization initiator include polymerization initiators using an organic alkali metal compound, an organic alkaline earth metal compound, and a lanthanum series metal compound as a main catalyst. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium, ethyl lithium, n-propyl lithium, isopropyl lithium, tert-octyl lithium, n-decyl lithium, 2-naphthyl lithium, 2-butylphenyl lithium, 4-phenylbutyl lithium, hexyl lithium, cyclopentyl lithium, a reaction product of diisopropenylbenzene with butyl lithium, and stilbene lithium; dilithium compounds such as diisopropenylbenzene, 1,4 -dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-tris(lithiomethyl)benzene, organic polyvalent lithium compounds such as a reaction product of sec-butyllithium and diisopropenylbenzene, a reaction product of n-butyllithium and 1,3-butadiene and divinylbenzene, and a reaction product of n-butyllithium and a polyacetylene compound; organic sodium compounds such as sodium naphthalene; organic potassium compounds such as potassium naphthalene; organic rubidium compounds; organic cesium compounds, etc. Other examples include alkoxides, sulfonates, carbonates, amides, etc. of lithium, sodium, potassium, etc. Also, other organometallic compounds may be used in combination. Furthermore, known organoalkali metal compounds disclosed in U.S. Pat. No. 5,708,092, British Patent No. 2,241,239, U.S. Pat. No. 5,527,753, etc. may also be used.

[0064] Examples of organic alkaline earth metal compounds include di-n-butyl magnesium, di-n-hexyl magnesium, diethoxy calcium, calcium distearate, di-t-butoxy strontium, diethoxy barium, diisopropoxy barium, diethylmercapto barium, di-t-butoxy barium, diphenoxy barium, diethylamino barium, barium distearate, diketyl barium, etc. Examples of polymerization initiators using a lanthanum series metal compound as a main catalyst include polymerization initiators using a lanthanum series metal salt consisting of a lanthanum series metal such as lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, etc., a carboxylic acid, and a phosphorus-containing organic acid, etc., as a main catalyst, and a co-catalyst such as an alkyl aluminum compound, an organoaluminum hydride compound, an organoaluminum halide compound, etc. Among these polymerization initiators, organic monolithium compounds and organic polyvalent lithium compounds are preferably used, organic monolithium compounds are more preferably used, and n-butyllithium is particularly preferably used from the viewpoint of industrial availability and ease of control of polymerization reaction.The organic alkali metal compound may be reacted in advance with a secondary amine such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, piperidine, hexamethyleneimine, and heptamethyleneimine to be used as an organic alkali metal amide compound.These polymerization initiators may be used alone or in combination of two or more. The organic alkali metal amide compound is not particularly limited, but examples thereof include lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, lithium dipropylamide, lithium diheptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiberazide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, and lithium methylphenethylamide.

[0065] The amount of the polymerization initiator used may be determined depending on the molecular weight of the desired conjugated diene polymer chain, but is usually in the range of 1 to 50 mmol, preferably 1.5 to 20 mmol, and more preferably 2 to 15 mmol per 1000 g of monomer.

[0066] The polymerization temperature is usually in the range of -80 to +150°C, preferably 0 to 100°C, and more preferably 30 to 90°C. As the polymerization mode, any mode such as batchwise or continuous can be adopted, but when a conjugated diene compound and an aromatic vinyl compound are copolymerized, the batchwise mode is preferred in that it is easy to control the randomness of the bonds between the conjugated diene monomer units and the aromatic vinyl monomer units. In addition, the bonding mode of each monomer in the conjugated diene polymer chain can be various bonding modes such as block, tapered, and random. Among these, the random mode is preferred. By making it random, the low heat build-up property of the obtained rubber cross-linked product can be further improved.

[0067] In addition, when polymerizing a monomer containing a conjugated diene compound, it is preferable to add a polar compound to an inert organic solvent in order to adjust the vinyl bond content in the conjugated diene monomer unit in the resulting conjugated diene polymer chain. Examples of polar compounds include ether compounds such as dibutyl ether, tetrahydrofuran, and 2,2-di(tetrahydrofuryl)propane; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; and phosphine compounds. Among these, ether compounds and tertiary amines are preferred, tertiary amines are more preferred, and tetramethylethylenediamine is particularly preferred. These polar compounds may be used alone or in combination of two or more. The amount of the polar compound used may be determined according to the desired vinyl bond content, and is preferably 0.001 to 100 mol, more preferably 0.01 to 10 mol, relative to 1 mol of the polymerization initiator. When the amount of the polar compound used is within this range, it is easy to adjust the vinyl bond content in the conjugated diene monomer unit, and problems due to deactivation of the polymerization initiator are unlikely to occur.

[0068] The vinyl bond content in the conjugated diene monomer units in the conjugated diene polymer chain having an active terminal obtained by polymerization is preferably 1 to 90% by weight, more preferably 3 to 85% by weight, and particularly preferably 5 to 80% by weight. By setting the vinyl bond content in the conjugated diene monomer units within the above range, the obtained cross-linked rubber product can be made to have excellent low heat build-up properties.

[0069] The weight average molecular weight (Mw) of the conjugated diene polymer chain having an active terminal is not particularly limited, but is preferably 50,000 to 1,000,000, more preferably 100,000 to 800,000, and particularly preferably 150,000 to 700,000, as a value measured by gel permeation chromatography in terms of polystyrene. By setting the weight average molecular weight (Mw) of the conjugated diene polymer chain having an active terminal within the above range, the obtained cross-linked rubber product can have a good balance between wet grip properties and low heat generation.

[0070] In addition, the molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the conjugated diene polymer chain having an active terminal is not particularly limited, but is preferably 1.0 to 3.0, and more preferably 1.0 to 2.5. When the molecular weight distribution (Mw / Mn) of the conjugated diene polymer chain having an active terminal is within the above range, the production of the modified conjugated diene rubber becomes easy.

[0071] Next, a siloxane compound is reacted with an active end of a conjugated diene polymer chain having an active end, which is obtained by polymerizing a monomer including a conjugated diene compound and a vinyl compound containing a functional group capable of interacting with silica, to introduce a modified structure by the siloxane compound into the end of the conjugated diene polymer chain.

[0072] The amount of the siloxane compound used when reacting the conjugated diene polymer chain having an active terminal with the siloxane compound is preferably 0.25 to 25 moles, more preferably 0.5 to 12.5 moles, calculated as the -Si-O- repeating unit contained in the siloxane compound, per mole of the polymerization initiator used in the polymerization reaction. When the amount of the siloxane compound used is within the above range, the low heat build-up property of the obtained cross-linked rubber can be further improved.

[0073] The method of reacting the siloxane compound with the conjugated diene polymer chain having an active terminal is not particularly limited, but includes a method of mixing them in a solvent in which each of them can be dissolved. The solvent used in this case can be any of those exemplified as the inert solvent used in the polymerization reaction described above. In addition, in this case, a method of adding the siloxane compound to the polymerization solution used in the polymerization to obtain the conjugated diene polymer chain having an active terminal is simple and preferable. Furthermore, in this case, it is preferable to dissolve the siloxane compound in an inert solvent and add it to the polymerization system, and the solution concentration is preferably in the range of 1 to 50% by weight. The reaction temperature is not particularly limited, but is usually 0 to 120°C, and the reaction time is not particularly limited, but is usually 1 minute to 1 hour.

[0074] The timing of adding the siloxane compound to the solution containing the conjugated diene polymer chain having an active terminal is not particularly limited, but it is preferable to add the siloxane compound to the solution when the polymerization reaction is not completed and the solution containing the conjugated diene polymer chain having an active terminal also contains a monomer, more specifically, when the solution containing the conjugated diene polymer chain having an active terminal contains 100 ppm or more, more preferably 300 to 50,000 ppm of a monomer.By adding the siloxane compound in this way, it is possible to suppress the side reaction between the conjugated diene polymer chain having an active terminal and impurities contained in the polymerization system, and to control the reaction well. In addition, after adding and mixing a siloxane compound to a solution containing a conjugated diene polymer chain having an active terminal, an organometallic compound such as n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium, ethyl lithium, n-propyl lithium, isopropyl lithium, tert-octyl lithium, n-decyl lithium, 2-naphthyl lithium, 2-butylphenyl lithium, 4-phenylbutyl lithium, hexyl lithium, cyclopentyl lithium, a reaction product of diisopropenylbenzene with butyl lithium, or an organomonolithium compound such as stilbene lithium may be mixed, thereby improving the processability of the resulting rubber composition (reducing compound Mooney).

[0075] In this way, by reacting a siloxane compound with the active end of a conjugated diene polymer chain having an active end, a modified structure by the siloxane compound can be introduced into the end of at least a part of the conjugated diene polymer chain. The conjugated diene polymer chain after the reaction has a modified structure by the siloxane compound introduced into the polymer chain end, but may also include an unmodified conjugated diene polymer chain to which no modified structure by the siloxane compound has been introduced.

[0076] In addition, before reacting a siloxane compound with a conjugated diene polymer chain having an active end, or after reacting a siloxane compound, when the conjugated diene polymer chain having an active end remains, a part of the active end of the conjugated diene polymer chain having an active end may be coupled or modified by adding a coupling agent or other modifier that has been conventionally used in the polymerization system within a range that does not impair the effects of the present invention.The other modifier used at this time is not particularly limited, but may include a compound containing a silicon atom other than a siloxane compound, a compound containing a nitrogen atom, etc.

[0077] After reacting the siloxane compound with the conjugated diene polymer chain having an active terminal, it is preferable to add a polymerization terminator such as an alcohol such as methanol, ethanol, or isopropanol, or water to deactivate the unreacted active terminal.

[0078] After deactivating the active end of the conjugated diene polymer chain, if desired, an antiaging agent such as a phenol-based stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer, a crumbing agent, and a scale inhibitor are added to the reaction solution, and then the polymerization solvent is separated from the reaction solution by direct drying or steam stripping, etc., to recover the modified conjugated diene rubber. Note that, before separating the polymerization solvent from the reaction solution, an extender oil may be mixed with the polymerization solution, and the modified conjugated diene rubber may be recovered as an oil-extended rubber.

[0079] Examples of the extender oil used when recovering the modified conjugated diene rubber as an oil-extended rubber include paraffinic, aromatic and naphthenic petroleum-based softeners, vegetable-based softeners, and fatty acids. When using a petroleum-based softener, it is preferable that the content of polycyclic aromatics extracted by the IP346 method (testing method of THE INSTITUTE PETROLEUM in the UK) is less than 3%. When using an extender oil, the amount of the extender oil used is preferably 5 to 100 parts by weight, more preferably 10 to 60 parts by weight, and even more preferably 20 to 50 parts by weight, based on 100 parts by weight of the modified conjugated diene rubber.

[0080] The coupling ratio of the modified conjugated diene rubber of the present invention is not particularly limited, but is preferably 10% by weight or more, more preferably 15% by weight or more, particularly preferably 20% by weight or more, and is preferably 80% by weight or less, more preferably 75% by weight or less, particularly preferably 70% by weight or less. When the coupling ratio is within the above range, the mechanical strength and abrasion resistance of the obtained cross-linked rubber can be well balanced. The coupling ratio is the weight fraction of the polymer molecule having a molecular weight 1.8 times or more of the peak top molecular weight of the conjugated diene polymer chain having an active terminal before reacting with the siloxane compound and the coupling agent or other modifiers used as necessary, relative to the total amount of the finally obtained modified conjugated diene rubber, and the molecular weight is measured as a polystyrene-equivalent molecular weight by gel permeation chromatography.

[0081] The weight average molecular weight (Mw) of the modified conjugated diene rubber of the present invention is preferably 50,000 to 5,000,000, more preferably 75,000 to 3,000,000, and particularly preferably 100,000 to 1,000,000, as measured by gel permeation chromatography in terms of polystyrene. By making the weight average molecular weight of the modified conjugated diene rubber within the above range, it becomes easy to compound silica into a rubber composition containing such a modified conjugated diene rubber, and the processability of the rubber composition can be further improved, and further the low heat build-up property of the obtained rubber cross-linked product can be further improved.

[0082] The molecular weight distribution of the modified conjugated diene rubber of the present invention, represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.1 to 3.0, more preferably 1.2 to 2.5, and particularly preferably 1.2 to 2.2. By setting the molecular weight distribution (Mw / Mn) of the modified conjugated diene rubber within the above range, the low heat build-up property of the obtained cross-linked rubber can be further improved.

[0083] In addition, the Mooney viscosity (ML 1+4 , 100° C.) is preferably 20 to 100, more preferably 30 to 90, and particularly preferably 35 to 80. When the modified conjugated diene rubber is used as an oil-extended rubber, it is preferable that the Mooney viscosity of the oil-extended rubber is within the above range.

[0084] The glass transition temperature (Tg) of the modified conjugated diene rubber of the present invention is not particularly limited, but is preferably 20° C. to −110° C., and more preferably 10° C. to −70° C. The glass transition temperature of the modified conjugated diene rubber of the present invention can be appropriately adjusted, for example, by adjusting the aromatic vinyl monomer unit content in the modified conjugated diene rubber and the vinyl bond content in the modified conjugated diene monomer unit portion.

[0085] <Rubber composition> The rubber composition of the present invention is a composition containing silica in addition to a rubber component containing the modified conjugated diene rubber of the present invention described above.

[0086] The rubber composition of the present invention may contain rubbers other than the above-mentioned modified conjugated diene rubber of the present invention. Examples of other rubbers include natural rubber (which may be modified natural rubber such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber (UPNR), and grafted natural rubber), polyisoprene rubber, emulsion-polymerized styrene-butadiene copolymer rubber, solution-polymerized styrene-butadiene copolymer rubber, polybutadiene rubber (which may be high cis-BR or low cis BR. Also, it may be polybutadiene rubber containing crystal fibers made of 1,2-polybutadiene polymer), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylonitrile-styrene-butadiene copolymer rubber, butyl rubber (IIR), ethylene-propylene copolymer, chloroprene rubber, nitrile chloroprene rubber, and nitrile isoprene rubber, which are other than the above-mentioned modified conjugated diene rubbers. Among these, natural rubber, polyisoprene rubber, polybutadiene rubber, and solution-polymerized styrene-butadiene copolymer rubber are preferred. These rubbers can be used alone or in combination of two or more, such as natural rubber and polybutadiene rubber, or natural rubber and styrene-butadiene copolymer rubber.

[0087] In the rubber composition of the present invention, the modified conjugated diene rubber of the present invention preferably accounts for 10 to 100% by weight, particularly preferably 50 to 100% by weight, of the rubber component in the rubber composition. By including the modified conjugated diene rubber of the present invention in the rubber component in such a ratio, a cross-linked rubber having low heat build-up, excellent wet grip properties, and excellent handling stability can be obtained.

[0088] Examples of silica used in the present invention include dry process white carbon, wet process white carbon, colloidal silica, precipitated silica, calcium silicate, and aluminum silicate. Among these, wet process white carbon containing hydrous silicic acid as a main component is preferable. Carbon-silica dual phase filler in which silica is supported on the surface of carbon black may also be used. These silicas may be used alone or in combination of two or more kinds. The nitrogen adsorption specific surface area of ​​the silica used (measured by the BET method in accordance with ASTM D3037-81) is preferably 20 to 400 m. 2 / g, more preferably 50 to 220m 2 / g, particularly preferably 80 to 170m 2 The pH of the silica is preferably 5 to 10.

[0089] The silica used in the present invention has a dibutyl phthalate (DBP) absorption value preferably in the range of about 100 to about 400, particularly preferably in the range of about 150 to about 300.

[0090] The silica used in the present invention preferably has an average ultimate particle size in the range of 0.01 to 0.05 μm as measured by electron microscopy, but the average ultimate particle size of the silica is not limited to this range and may be smaller or larger.

[0091] As the silica used in the present invention, for example, various commercially available silicas can be used, such as Hi-Sil, 210, Hi-Sil 233, and Hi-Sil 243LD manufactured by PPG Industries, Zeosil 1115MP, Zeosil 1165MP, and Zeosil 165GR manufactured by Rhodia, and ULTRASIL VN2 and ULTRASIL VN3 manufactured by EVONIK.

[0092] The amount of silica blended in the rubber composition of the present invention is preferably 10 to 250 parts by weight, more preferably 15 to 150 parts by weight, and further preferably 20 to 130 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition. By making the amount of silica blended within the above range, the wet grip property, low heat generation property, and handling stability of the obtained cross-linked rubber product can be further improved.

[0093] The rubber composition of the present invention may further contain a silane coupling agent from the viewpoint of further improving the low heat generation property. The silane coupling agent is not particularly limited, and various silane coupling agents can be used, but in the present invention, sulfide-based, mercapto-based, protected mercapto-based (e.g., those having a carbonylthio group), thiocyanate-based, vinyl-based, amino-based, methacrylate-based, glycidoxy-based, nitro-based, epoxy-based or chloro-based silane coupling agents can be preferably used. Specific examples of the silane coupling agent include bis(3-(triethoxysilyl)propyl) disulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-(triethoxysilyl)propyl) tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-[ ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl]-1-propanethiol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, γ-trimethoxysilylpropyl benzothiazyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazole tetrasulfide, 3-thiocyanatepropyl triethoxysilane, vinyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane, 3-trimethoxysilylpropyl methacrylate monosulfide, γ-glycidoxypropyl triethoxysilane, 3-nitropropyl trimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, and 3-chloropropyl trimethoxysilane. In addition, NXT-Z100, NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z45, NXT manufactured by Momentive Performance Materials, Si69, Si75, VP Si363 manufactured by Evonik Degussa, etc. can also be used. These silane coupling agents can be used alone or in combination of two or more. In addition, one or more of these can be oligomerized in advance and used in the oligomerized state.The amount of the silane coupling agent to be added is preferably 0.1 to 30 parts by weight, and more preferably 1 to 15 parts by weight, based on 100 parts by weight of silica.

[0094] The rubber composition of the present invention may further contain carbon black such as furnace black, acetylene black, thermal black, channel black, and graphite. Among these, furnace black is preferred. These carbon blacks may be used alone or in combination of two or more. The amount of carbon black is usually 120 parts by weight or less per 100 parts by weight of the rubber component in the rubber composition.

[0095] The method for adding silica to the rubber component containing the modified conjugated diene rubber of the present invention is not particularly limited, and may include a method of adding silica to a solid rubber component and kneading it (dry kneading method) or a method of adding silica to a solution containing the modified conjugated diene rubber and coagulating / drying it (wet kneading method).

[0096] In addition, the rubber composition of the present invention preferably further contains a crosslinking agent. Examples of the crosslinking agent include sulfur-containing compounds such as sulfur and sulfur halides, organic peroxides, quinone dioximes, organic polyamine compounds, and alkylphenol resins having a methylol group. Among these, sulfur is preferably used. The amount of the crosslinking agent is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

[0097] Furthermore, in addition to the above-mentioned components, the rubber composition of the present invention may contain, in accordance with a conventional method, necessary amounts of compounding agents such as crosslinking accelerators, crosslinking activators, antioxidants, fillers (excluding the above-mentioned silica and carbon black), activators, process oils, plasticizers, lubricants, and tackifiers.

[0098] When sulfur or a sulfur-containing compound is used as the crosslinking agent, it is preferable to use a crosslinking accelerator and a crosslinking activator in combination. Examples of the crosslinking accelerator include sulfenamide crosslinking accelerators, guanidine crosslinking accelerators, thiourea crosslinking accelerators, thiazole crosslinking accelerators, thiuram crosslinking accelerators, dithiocarbamic acid crosslinking accelerators, and xanthogenic acid crosslinking accelerators. Among these, those containing sulfenamide crosslinking accelerators are preferable. These crosslinking accelerators are used alone or in combination of two or more. The amount of the crosslinking accelerator is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

[0099] Examples of the crosslinking activator include higher fatty acids such as stearic acid, zinc oxide, etc. These crosslinking activators may be used alone or in combination of two or more. The amount of the crosslinking activator is preferably 0.05 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition.

[0100] To obtain the rubber composition of the present invention, each component may be kneaded according to a conventional method. For example, the components other than the heat-unstable components such as the crosslinking agent and the crosslinking accelerator are kneaded with the modified conjugated diene rubber, and then the heat-unstable components such as the crosslinking agent and the crosslinking accelerator are mixed with the kneaded mixture to obtain the desired composition. The kneading temperature of the components other than the heat-unstable components and the modified conjugated diene rubber is preferably 80 to 200°C, more preferably 120 to 180°C, and the kneading time is preferably 30 seconds to 30 minutes. In addition, the kneaded mixture is usually mixed with the heat-unstable components after cooling to 100°C or less, preferably 80°C or less.

[0101] <Rubber cross-linked products> The cross-linked rubber product of the present invention is obtained by cross-linking the above-mentioned rubber composition of the present invention. The cross-linked rubber product of the present invention can be produced by using the rubber composition of the present invention, for example, molding the rubber composition into a desired shape using a molding machine such as an extruder, an injection molding machine, a compressor, or a roll, and heating the composition to cause a cross-linking reaction and fix the shape as a cross-linked rubber product. In this case, the cross-linking may be carried out after molding in advance or simultaneously with molding. The molding temperature is usually 10 to 200°C, preferably 25 to 120°C. The cross-linking temperature is usually 100 to 200°C, preferably 130 to 190°C, and the cross-linking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, and particularly preferably 3 minutes to 6 hours.

[0102] Depending on the shape, size, etc. of the cross-linked rubber product, even if the surface is cross-linked, the inside may not be sufficiently cross-linked, so secondary cross-linking may be performed by further heating.

[0103] The heating method may be appropriately selected from among methods commonly used for crosslinking rubber, such as press heating, steam heating, oven heating, and hot air heating.

[0104] The cross-linked rubber of the present invention thus obtained is obtained by using the modified conjugated diene rubber of the present invention described above, and therefore has excellent wet grip properties, low heat generation properties, and steering stability. In particular, the modified conjugated diene rubber of the present invention is obtained by copolymerizing a vinyl compound containing a functional group capable of interacting with silica with a conjugated diene compound, and introducing a modified structure by a siloxane compound into at least one end of the polymer chain, and therefore has high affinity for fillers such as silica due to these actions, and therefore the fillers such as silica can be dispersed well, and furthermore, the reinforcing properties of the fillers such as silica can be fully exhibited. Therefore, the cross-linked rubber of the present invention obtained by using such modified conjugated diene rubber of the present invention has excellent wet grip properties, low heat generation properties, and steering stability.

[0105] Therefore, by taking advantage of its excellent wet grip properties, low heat generation and steering stability, the cross-linked rubber product of the present invention can be used in various applications, such as, for example, in tires, materials for various tire portions such as cap tread, base tread, carcass, sidewalls and bead portions, materials for hoses, belts, mats, anti-vibration rubber and other various industrial products, resin impact resistance improvers, resin film cushioning agents, shoe soles, rubber shoes, golf balls, toys, etc. In particular, since the cross-linked rubber product of the present invention is excellent in wet grip properties, low heat generation and steering stability, it can be suitably used as a tire material, particularly a material for low fuel consumption tires, and is most suitable for tread applications. EXAMPLES

[0106] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" are by weight unless otherwise specified. Tests and evaluations were performed according to the following.

[0107] [Weight average molecular weight, molecular weight distribution] The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) were determined based on a chart obtained by gel permeation chromatography based on the molecular weight converted into polystyrene. The specific measurement conditions for gel permeation chromatography were as follows: Measuring instrument: High-performance liquid chromatograph (Tosoh Corporation, product name "HLC-8220") Column: Two columns (trade name "GMH-HR-H") manufactured by Tosoh Corporation were connected in series. Detector: Differential refractometer Eluent: Tetrahydrofuran Column temperature: 40℃

[0108] [Microstructure] The styrene monomer unit content, the bis(diethylamino)methylvinylsilane monomer unit content, and the vinyl bond content are 1 Measurements were performed by H-NMR.

[0109] [Roll Adhesion of Rubber Composition] The obtained rubber composition was molded into a sheet using an open roll at 50° C. The state of the obtained sheet-like rubber composition when peeled off from the surface of the open roll was evaluated according to the following criteria. ⊚: When the rubber composition was peeled off from the surface of the open roll, no adhesion to the roll occurred and the rubber composition could be peeled off easily. In addition, since no adhesion to the roll occurred, the surface of the sheet-like rubber composition was sufficiently smooth. ×: When the rubber composition was peeled off from the surface of the open roll, it was difficult to peel off because of the strong adhesion to the roll. In addition, because of the strong adhesion to the roll, the sheet-shaped rubber composition had poor surface smoothness.

[0110] [Wet Grip Property of Cross-Linked Rubber] Wet grip performance was evaluated by measuring the tan δ value at 0°C under conditions of dynamic strain of 0.5% and 10 Hz using an ARES manufactured by Rheometrics, Inc., for a test piece of the cross-linked rubber 50 mm long, 12.7 mm wide, and 2 mm thick. The tan δ value is expressed as an index with the measured value of Comparative Example 2 set at 100. The higher this index, the better the wet grip performance.

[0111] [Low heat build-up of cross-linked rubber] The low heat build-up property was evaluated by measuring tan δ at 60°C under conditions of a dynamic strain of 2.5% and 10 Hz using an ARES manufactured by Rheometrics, Inc. for a test piece of the cross-linked rubber 50 mm long, 12.7 mm wide and 2 mm thick. The values ​​of tan δ for Examples 1 to 4 and Comparative Examples 1 and 3 are shown as indexes with the measured value for Comparative Example 2 set to 100, and for Example 5 and Comparative Example 5, the measured value for Comparative Example 4 set to 100. The smaller the index, the better the low heat build-up property.

[0112] [Handling stability of cross-linked rubber product] Handling stability was evaluated by conducting tensile tests on test pieces of the cross-linked rubber according to JIS K6301, and measuring and calculating the value of (stress at 300% elongation) / (stress at 100% elongation). The higher this value, the higher the reinforcement by silica and the better the handling stability.

[0113] Example 1 In a nitrogen atmosphere, 792 g of cyclohexane, 1.41 mmol of tetramethylethylenediamine, 76.3 g of 1,3-butadiene, 28.7 g of styrene, and bis(diethylamino)methylvinylsilane (X in the above general formula (3)) were placed in an autoclave equipped with a stirrer. 9 = chemical single bond, X 10 , X 11 = diethylamino group, X 12 After 0.144g of 0.144g of a compound (=methyl group) was added, 0.98mmol of n-butyl lithium was added, and polymerization was started at 60°C. The polymerization reaction was continued for 60 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, polyorganosiloxane represented by the following formula (7) was added so that the content of -Si-O- repeating units was 1.00mmol, and the reaction was carried out for 30 minutes. Then, as a polymerization terminator, methanol was added in an amount equivalent to twice the moles of n-butyl lithium used to obtain a solution containing a modified conjugated diene rubber. To this solution, 0.20 parts of Irganox 1520L (manufactured by BASF) was added as an anti-aging agent with respect to 100 parts of the modified conjugated diene rubber, and the solvent was removed by steam stripping, and the mixture was vacuum dried at 60°C for 24 hours to obtain a solid modified conjugated diene rubber. The weight average molecular weight (Mw) of the modified conjugated diene rubber obtained in Example 1 was 375,000, the styrene monomer unit content was 27% by weight, and the vinyl bond content was 59% by weight. The bis(diethylamino)methylvinylsilane monomer unit content in the modified conjugated diene rubber obtained in Example 1 was 0.15% by weight. [ka]

[0114] Example 2 In a nitrogen atmosphere, 792 g of cyclohexane, 1.41 mmol of tetramethylethylenediamine, 76.3 g of 1,3-butadiene, 28.7 g of styrene, and bis(diethylamino)methylvinylsilane (X in the above general formula (3)) were placed in an autoclave equipped with a stirrer. 9 = chemical single bond, X 10 , X 11 = diethylamino group, X 12 After 0.144g of 0.144g of the compound (=methyl group) was added, 0.98mmol of n-butyl lithium was added, and polymerization was started at 60°C. The polymerization reaction was continued for 60 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, polyorganosiloxane represented by the above general formula (7) was added so that the content of -Si-O- repeating units was 2.51mmol, and the reaction was allowed to proceed for 20 minutes. Next, 2.35mmol of n-butyl lithium was added, and the reaction was allowed to proceed for 30 minutes. Thereafter, as a polymerization terminator, methanol was added in an amount equivalent to twice the moles of the n-butyl lithium used, to obtain a solution containing a modified conjugated diene rubber. To this solution, 0.20 parts of Irganox 1520L (manufactured by BASF) was added as an anti-aging agent relative to 100 parts of the modified conjugated diene rubber, and the solvent was removed by steam stripping, and the mixture was vacuum dried at 60°C for 24 hours to obtain a solid modified conjugated diene rubber. The weight average molecular weight (Mw) of the modified conjugated diene rubber obtained in Example 2 was 472,000, the styrene monomer unit content was 27% by weight, and the vinyl bond content was 59% by weight. The bis(diethylamino)methylvinylsilane monomer unit content in the modified conjugated diene rubber obtained in Example 2 was 0.15% by weight.

[0115] Example 3 A solid conjugated diene rubber was obtained in the same manner as in Example 1, except that 0.144 g of bis(diethylamino)methylvinylsilane was replaced with 0.135 g of m / p-pyrrolidinoethylstyrene (a mixture of m-pyrrolidinoethylstyrene and p-pyrrolidinoethylstyrene). The weight average molecular weight (Mw) of the obtained conjugated diene rubber of Example 3 was 546,000, the styrene monomer unit content was 27 wt%, and the vinyl bond content was 58 wt%. The m / p-pyrrolidinoethylstyrene monomer unit content in the obtained conjugated diene rubber of Example 3 was 0.13 wt%.

[0116] Example 4 In a nitrogen atmosphere, 792 g of cyclohexane, 1.41 mmol of tetramethylethylenediamine, 0.98 mmol of piperidine, 76.3 g of 1,3-butadiene, 28.7 g of styrene, and bis(diethylamino)methylvinylsilane (X in the above general formula (3)) were placed in an autoclave equipped with a stirrer. 9 = chemical single bond, X 10 , X 11 = diethylamino group, X 12After 0.144g of 0.144g of the compound (=methyl group) was added, 0.98mmol of n-butyl lithium was added, and polymerization was started at 60°C. The polymerization reaction was continued for 60 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, polyorganosiloxane represented by the above general formula (7) was added so that the content of -Si-O- repeating units was 2.51mmol, and the reaction was allowed to proceed for 20 minutes. Next, 2.35mmol of n-butyl lithium was added, and the reaction was allowed to proceed for 30 minutes. Thereafter, as a polymerization terminator, methanol was added in an amount equivalent to twice the moles of the n-butyl lithium used, to obtain a solution containing a modified conjugated diene rubber. To this solution, 0.20 parts of Irganox 1520L (manufactured by BASF) was added as an anti-aging agent relative to 100 parts of the modified conjugated diene rubber, and the solvent was removed by steam stripping, and the mixture was vacuum dried at 60°C for 24 hours to obtain a solid modified conjugated diene rubber. The weight average molecular weight (Mw) of the modified conjugated diene rubber obtained in Example 4 was 409,000, the styrene monomer unit content was 27% by weight, and the vinyl bond content was 60% by weight. The bis(diethylamino)methylvinylsilane monomer unit content in the modified conjugated diene rubber obtained in Example 4 was 0.15% by weight.

[0117] Comparative Example 1 In an autoclave equipped with a stirrer, 792g of cyclohexane, 1.41mmol of tetramethylethylenediamine, 76.3g of 1,3-butadiene, 28.7g of styrene, and 0.144g of bis(diethylamino)methylvinylsilane were charged under a nitrogen atmosphere, and then 0.98mmol of n-butyllithium was added to initiate polymerization at 60°C. The polymerization reaction was continued for 60 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, methanol was added as a polymerization terminator in an amount equivalent to twice the moles of n-butyllithium used to obtain a solution containing a conjugated diene rubber. After adding 0.20 parts of Irganox 1520L (manufactured by BASF) as an anti-aging agent to this solution relative to 100 parts of conjugated diene rubber, the solvent was removed by steam stripping, and the mixture was vacuum dried at 60°C for 24 hours to obtain a solid conjugated diene rubber. The weight average molecular weight (Mw) of the obtained conjugated diene rubber of Comparative Example 1 was 218,000, the styrene monomer unit content was 27% by weight, and the vinyl bond content was 59% by weight. The bis(diethylamino)methylvinylsilane monomer unit content in the obtained conjugated diene rubber of Comparative Example 1 was 0.15% by weight.

[0118] Comparative Example 2 In an autoclave equipped with a stirrer, 792g of cyclohexane, 1.41mmol of tetramethylethylenediamine, 76.3g of 1,3-butadiene, and 28.7g of styrene were charged under a nitrogen atmosphere, and then 0.98mmol of n-butyllithium was added to initiate polymerization at 60°C. The polymerization reaction was continued for 60 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by the above formula (7) was added so that the content of -Si-O- repeating units was 1.00mmol, and the reaction was allowed to proceed for 30 minutes. Thereafter, methanol was added as a polymerization terminator in an amount equivalent to twice the moles of the n-butyllithium used to obtain a solution containing a modified conjugated diene rubber. To this solution, 0.20 parts of Irganox 1520L (manufactured by BASF) was added as an anti-aging agent relative to 100 parts of the modified conjugated diene rubber, and the solvent was removed by steam stripping, followed by vacuum drying at 60° C. for 24 hours to obtain a solid modified conjugated diene rubber. The weight average molecular weight (Mw) of the modified conjugated diene rubber obtained in Comparative Example 2 was 456,000, the styrene monomer unit content was 27% by weight, and the vinyl bond content was 59% by weight.

[0119] Comparative Example 3 A solid conjugated diene rubber was obtained in the same manner as in Comparative Example 1, except that 0.144 g of bis(diethylamino)methylvinylsilane was replaced with 0.135 g of m / p-pyrrolidinoethylstyrene. The weight average molecular weight (Mw) of the obtained conjugated diene rubber of Comparative Example 3 was 246,000, the styrene monomer unit content was 27 wt%, and the vinyl bond content was 59 wt%. The m / p-pyrrolidinoethylstyrene monomer unit content in the obtained conjugated diene rubber of Comparative Example 3 was 0.13 wt%.

[0120] [Production and Evaluation of Rubber Composition and Cross-Linked Rubber Product] In a 250 ml Brabender type mixer, 100 parts of the modified conjugated diene rubber of Example 1 was masticated for 30 seconds, and then 50 parts of silica (manufactured by Rhodia, trade name "Zeosil1115MP"), 20 parts of process oil (manufactured by Nippon Oil Corporation, trade name "Aromax T-DAE"), and 6.0 parts of a silane coupling agent: bis(3-(triethoxysilyl)propyl)tetrasulfide (manufactured by Degussa, trade name "Si69") were added, and the mixture was kneaded for 1.5 minutes at a starting temperature of 110°C, after which 25 parts of silica (manufactured by Rhodia, trade name "Zeosil1115MP"), 3 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of an antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac 6C") were added, and the mixture was kneaded for a further 2.5 minutes, and then the kneaded product was discharged from the mixer. The temperature of the kneaded product at the end of kneading was 150°C. After cooling the kneaded product to room temperature, it was kneaded again in a Brabender type mixer with a starting temperature of 110°C for 2 minutes, and then the kneaded product was discharged from the mixer. Next, 1.40 parts of sulfur, 1.2 parts of a crosslinking accelerator: N-tert-butyl-2-benzothiazolyl sulfenamide (trade name "Noccela NS-P", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), and 1.2 parts of 1,3-diphenylguanidine (trade name "Noccela D", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were added to the kneaded product obtained by kneading them with an open roll at 50°C to obtain a rubber composition. The obtained rubber composition was then molded into a sheet using an open roll at 50° C., and the roll adhesion of the rubber composition was evaluated according to the above-mentioned method. The results are shown in Table 1. The obtained rubber composition in sheet form was press-crosslinked at 160° C. for 20 minutes to prepare a test piece of the crosslinked rubber, which was then used to evaluate wet grip performance, low heat build-up, and steering stability. The results are shown in Table 1.

[0121] In addition, for the modified conjugated diene rubbers of Examples 2 to 4, the conjugated diene rubbers of Comparative Examples 1 and 3, and the modified conjugated diene rubber of Comparative Example 2, rubber compositions were prepared in the same manner, and the roll adhesion of the rubber compositions was evaluated. Also, test pieces of the cross-linked rubber were prepared in the same manner, and the wet grip properties, low heat generation properties, and handling stability were evaluated. The results are shown in Table 1.

[0122] [Table 1]

[0123] [Evaluation of Examples 1 to 4 and Comparative Examples 1 to 3] As can be seen from Table 1, the modified conjugated diene rubber having a modified structure with a siloxane compound at at least one end of a polymer chain containing a conjugated diene monomer unit and a monomer unit of a vinyl compound containing a functional group capable of interacting with silica effectively suppresses adhesion to rolls when made into a rubber composition, thereby enabling excellent processability to be achieved, and furthermore, the rubber cross-linked product obtained using this has excellent low heat build-up properties, wet grip properties, and handling stability (Examples 1 to 4). When a conjugated diene rubber not having a modified structure with a siloxane compound introduced at the end of the polymer chain was used, the rubber composition obtained showed significant adhesion to the roll, and the cross-linked rubber obtained was inferior in low heat build-up, wet grip properties, and handling stability (Comparative Examples 1 and 3). Similarly, even when a modified conjugated diene rubber not having a monomer unit of a vinyl compound containing a functional group capable of interacting with silica in the polymer chain was used, the rubber composition obtained had significant adhesion to the roll, and the cross-linked rubber obtained was inferior in low heat build-up, wet grip properties, and handling stability (Comparative Example 2).

[0124] Example 5 In an autoclave equipped with a stirrer, 830g of cyclohexane, 1.28mmol of tetramethylethylenediamine, 80.3g of 1,3-butadiene, 29.7g of styrene, and 0.066g of bis(diethylamino)methylvinylsilane were charged under a nitrogen atmosphere, and then 0.80mmol of n-butyllithium was added to initiate polymerization at 60°C. The polymerization reaction was continued for 60 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, 0.30mmol of N,N-dimethylaminopropylacrylamide was added and reacted for 15 minutes. Next, polyorganosiloxane represented by the above general formula (7) was added so that the content of -Si-O- repeating units was 0.33mmol, and reacted for 30 minutes. Thereafter, methanol was added as a polymerization terminator in an amount equivalent to twice the moles of n-butyllithium used to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 parts of an antioxidant (product name "Irganox 1520L", manufactured by BASF) was added per 100 parts of the conjugated diene rubber, and the solvent was removed by steam stripping. The mixture was vacuum dried at 60°C for 24 hours to obtain a solid conjugated diene rubber. The weight average molecular weight (Mw) of the obtained conjugated diene rubber of Example 5 was 254,000, the styrene monomer unit content was 27% by weight, and the vinyl bond content was 58% by weight. The bis(diethylamino)methylvinylsilane monomer unit content in the obtained conjugated diene rubber of Example 5 was 0.060% by weight.

[0125] Comparative Example 4 In a stirrer-equipped autoclave, 830g of cyclohexane, 1.28mmol of tetramethylethylenediamine, 0.61mmol of piperidine, 80.3g of 1,3-butadiene, 29.7g of styrene, and 0.132g of bis(diethylamino)methylvinylsilane were charged under a nitrogen atmosphere, and then 0.80mmol of n-butyllithium was added to initiate polymerization at 60°C. The polymerization reaction was continued for 60 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.61mmol of N-phenylpyrrolidone was added and reacted for 30 minutes. Thereafter, methanol was added as a polymerization terminator in an amount equivalent to twice the moles of the n-butyllithium used to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 parts of an antioxidant (product name "Irganox 1520L", manufactured by BASF) was added per 100 parts of the conjugated diene rubber, and the solvent was removed by steam stripping. The mixture was vacuum dried at 60°C for 24 hours to obtain a solid conjugated diene rubber. The weight average molecular weight (Mw) of the obtained conjugated diene rubber of Comparative Example 4 was 340,000, the styrene monomer unit content was 26% by weight, and the vinyl bond content was 57% by weight. The bis(diethylamino)methylvinylsilane monomer unit content in the obtained conjugated diene rubber of Comparative Example 4 was 0.12% by weight.

[0126] Comparative Example 5 In an autoclave equipped with a stirrer, 830g of cyclohexane, 1.28mmol of tetramethylethylenediamine, 80.3g of 1,3-butadiene, and 29.7g of styrene were charged under a nitrogen atmosphere, and then 0.80mmol of n-butyllithium was added to initiate polymerization at 60°C. The polymerization reaction was continued for 60 minutes, and after it was confirmed that the polymerization conversion rate was in the range of 95% to 100%, 0.30mmol of N,N-dimethylaminopropylacrylamide was added and reacted for 15 minutes. Next, polyorganosiloxane represented by the above general formula (7) was added so that the content of -Si-O- repeating units was 0.33mmol, and the reaction was allowed to proceed for 30 minutes. Thereafter, methanol was added as a polymerization terminator in an amount equivalent to twice the moles of n-butyllithium used to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 parts of an antioxidant (product name "Irganox 1520L", manufactured by BASF) was added per 100 parts of the conjugated diene rubber, and then the solvent was removed by steam stripping and the mixture was vacuum dried at 60°C for 24 hours to obtain a solid conjugated diene rubber. The weight average molecular weight (Mw) of the obtained conjugated diene rubber of Comparative Example 5 was 399,000, the styrene monomer unit content was 26% by weight, and the vinyl bond content was 57% by weight.

[0127] For the modified conjugated diene rubber of Example 5 and the modified conjugated diene rubbers of Comparative Examples 4 and 5, test pieces of the cross-linked rubbers were prepared and evaluated for low heat build-up in the same manner as in Example 1. The results are shown in Table 2.

[0128] [Table 2]

[0129] [Evaluation of Example 5 and Comparative Examples 4 and 5] From Table 2, even when two types of compounds, a compound other than a siloxane compound and a siloxane compound, were used as the modifier reacted with the active end of the polymer chain and reacted in sequence, the cross-linked rubber obtained using the modified conjugated diene rubber thus obtained was also excellent in low heat buildup (Example 5). Also, in Example 5, as in Examples 1 to 4, when made into a rubber composition, adhesion to the roll was effectively suppressed, and the processability was excellent. Furthermore, the cross-linked rubber obtained using this was excellent in wet grip properties and steering stability in addition to low heat buildup properties. On the other hand, when a compound other than a siloxane compound was used as the modifier reacted with the end of the polymer chain, or when two types of compounds, a compound other than a siloxane compound and a siloxane compound, were used as the modifier reacted with the active end of the polymer chain but a vinyl compound containing a functional group capable of interacting with silica was not copolymerized, the low heat generation properties were poor (Comparative Examples 4 and 5).

Claims

1. a step of copolymerizing a monomer including a conjugated diene compound, an aromatic vinyl monomer, and a vinyl compound containing a functional group capable of interacting with silica in an inert solvent in the presence of a polymerization initiator and a tertiary amine to obtain a conjugated diene polymer chain having an active terminal; and reacting a siloxane compound with an active end of the conjugated diene polymer chain having an active end, The vinyl compound having a functional group capable of interacting with silica is a compound represented by the following general formula (3): The siloxane compound is a polyorganosiloxane represented by the following general formula (2): the amount of the tertiary amine used is 0.01 to 10 mol per 1 mol of the polymerization initiator, the amount of the siloxane compound used is 0.5 to 12.5 moles, calculated as the number of -Si-O- repeating units contained in the siloxane compound, per mole of the polymerization initiator, A method for producing a modified conjugated diene rubber, wherein a content ratio of monomer units derived from a vinyl compound containing a functional group capable of interacting with the silica in a polymer chain constituting the modified conjugated diene rubber is 0.05 to 1% by weight. 【Chemistry 9】 (In the above general formula (3), X ９ represents a chemical single bond or a hydrocarbylene group, X １０ , X １１ and X １２ each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent. 【Chemistry 10】 (In the above general formula (2), R 1 to R 8 are alkyl groups having 1 to 6 carbon atoms or aryl groups having 6 to 12 carbon atoms, which may be the same as or different from each other. X 5 and X 8 are any groups selected from the group consisting of alkyl groups having 1 to 6 carbon atoms, aryl groups having 6 to 12 carbon atoms, alkoxy groups having 1 to 5 carbon atoms, and groups containing an epoxy group and having 4 to 12 carbon atoms, which may be the same as or different from each other. X 6 is an alkoxy group having 1 to 5 carbon atoms, or a group containing an epoxy group and having 4 to 12 carbon atoms, and when there are multiple X 6 s, they may be the same as or different from each other. X 7 is a group containing 2 to 20 repeating units of alkylene glycol, and when there are multiple X 7 s, they may be the same as or different from each other. m is an integer of 1 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m+n+k is 1 or more.)

2. 2. The method for producing a modified conjugated diene rubber according to claim 1, wherein an organic alkali metal amide compound obtained by reacting an organic alkali metal compound with a secondary amine is used as the polymerization initiator.

3. A method for producing a rubber composition, comprising obtaining a modified conjugated diene rubber by the method according to claim 1 or 2, and then mixing a rubber component containing the obtained modified conjugated diene rubber with silica.

4. The method for producing a rubber composition according to claim 3, further comprising mixing a crosslinking agent.

5. A method for producing a cross-linked rubber product, comprising obtaining a rubber composition by the method according to claim 3 or 4, and then cross-linking the obtained rubber composition.

6. A method for producing a tire, comprising obtaining a cross-linked rubber product by the method according to claim 5, and then producing a tire using the cross-linked rubber product obtained.

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