JP2010070119A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in the run-flat durability without impairing the rolling resistance and the riding feeling during normal traveling. <P>SOLUTION: The pneumatic tire includes a bead core, a carcass layer having one or more carcass plys in which a plurality of reinforcing cords laid in parallel are embedded in a coating rubber, a tread rubber layer, an inner liner, a side reinforcing layer and a bead filler. The reinforcing cords is of material of a cellulose based fiber, has a rigidity represented by a cord modulus of elasticity of 50 cN/dtex or higher (at 180°C and a stress caused when a force of 29.4 N is applied per piece of the reinforcing cord), and employs a rubber composition containing (A) rubber component of 100 pts.mass and (B) carbon black of 55 pts.mass or more and with the physical properties of vulcanized rubber of 10 MPa or more of the 100% elongation elasticity (M100) and 6.0 or less of Σ value of tangent loss tanδ at 28-150°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber composition having a vulcanized rubber characteristic having an elastic modulus at 100% elongation of not less than a certain value and a tangent loss tan δ of not more than a certain Σ value at 28 ° C. to 150 ° C. Further, the present invention relates to a pneumatic tire that is used for a bead filler and uses a specific cellulosic fiber for a carcass layer and has improved run-flat durability without impairing rolling resistance and riding comfort during normal running.

2. Description of the Related Art Conventionally, in a pneumatic tire, particularly a run flat tire, a side reinforcing layer made of a rubber composition alone or a composite of a rubber composition and a fiber is provided to improve the rigidity of a sidewall portion. (For example, see Patent Document 1)
Pneumatic tires run when the internal pressure of the tire (hereinafter referred to as internal pressure) drops due to puncture, etc., so-called run-flat running state, the deformation of the tire sidewall and bead filler increases, and heat is generated. In some cases, the temperature reaches 200 ° C. or higher. In such a state, even in a pneumatic tire having a side reinforcing layer, the side reinforcing layer and the bead filler exceed the fracture limit, leading to a tire failure.
As a means of prolonging the time until such a failure, the rubber composition used for the side reinforcing layer and the bead filler is highly compounded with sulfur, and the rubber composition is made highly elastic so that the tire sidewall portion and Although there is a technique for suppressing the deformation amount of the bead filler, there is a problem that the rolling resistance during normal running of the tire becomes high and the fuel efficiency is lowered.

On the other hand, Patent Document 2 proposes that a rubber composition containing various modified conjugated diene-aromatic vinyl copolymers and a heat resistance improver is used for the side reinforcing layer and the bead filler.
Furthermore, Patent Document 3 proposes that a rubber composition containing a specific conjugated diene polymer and a phenol resin is used for the side reinforcing layer and the bead filler.
These are intended to increase the elastic modulus of the rubber composition used for the side reinforcing layer and bead filler, and to suppress a decrease in the elastic modulus at high temperatures, and greatly improve the run-flat durability. However, the rolling resistance during normal running is significantly deteriorated.

On the other hand, as a means of earning time to the failure, there is something that increases the volume of rubber, such as increasing the maximum thickness of the arranged side reinforcing layer and the bead filler, but when taking such a method, Undesirable situations such as deterioration of riding comfort during normal driving, increase in weight, and increase in noise level occur.
If the volume of the side reinforcing layer and the bead filler to be disposed is reduced in order to avoid the above-mentioned situation, for example, deterioration of the ride comfort, the load at the time of run flat cannot be supported. Deformation becomes very large, leading to an increase in heat generation of the rubber composition, and as a result, the tire has a problem of causing failure earlier.
Similarly, when the rubber used is made to be less elastic by changing the compounding material, the rubber composition is not able to support the load during run-flat, and the deformation of the sidewall portion of the tire becomes very large. As a result, the tires are likely to break down earlier as a result.

  In recent years, cellulosic fibers such as rayon or lyocell have high elasticity at room temperature and have high adhesive strength, and therefore, application to tires has been studied. In particular, lyocell has higher elasticity than rayon, and therefore, attention has been focused on the application to tires (see, for example, Patent Documents 4 and 5). However, the pneumatic tires disclosed in these patent documents are not sufficient in terms of run-flat durability and riding comfort, and these contradictions such as improving run-flat durability without impairing riding comfort. Development of pneumatic tires that can achieve both high performance levels is desired.

JP 11-310019 A WO02 / 02356 brochure JP 2004-74960 A JP 2004-66930 A JP 2005-199763 A

  Under such circumstances, an object of the present invention is to provide a pneumatic tire with improved run-flat durability without impairing rolling resistance and riding comfort during normal driving.

As a result of intensive research to develop a pneumatic tire having the above-mentioned preferable properties, the present inventor has found that the vulcanized rubber properties have a modulus of elasticity at 100% elongation of not less than a certain value and a tangent loss tan δ of 28. A pneumatic tire comprising a rubber composition having a Σ value at a temperature of ˜150 ° C. below a certain value, particularly for a side reinforcing layer and / or a bead filler, and using a specific cellulosic fiber for the carcass layer is suitable for the purpose. Found to get. The present invention has been completed based on such findings.
That is, the present invention
(1) A pneumatic tire comprising a bead core, a carcass layer having one or more carcass plies in which a plurality of parallel reinforcing cords are embedded in a covering rubber, a tread rubber layer, an inner liner, a side reinforcing layer, and a bead filler. The reinforcing cord is made of cellulosic fiber and has a stiffness expressed by a cord elastic modulus of 50 cN / dtex or more (at a temperature of 180 ° C. and a stress applied with a force of 29.4 N per reinforcing cord). And (A) a rubber component and 100 parts by mass thereof, (B) containing 55 parts by mass or more of carbon black, and in the physical properties of vulcanized rubber, the elastic modulus at 100% elongation (M100) is 10 MPa or more and tangent A pneumatic tire characterized by using a rubber composition having a Σ value of loss tan δ at 28 ° C. to 150 ° C. of 6.0 or less,
(2) The rubber composition according to (1), wherein (B) carbon black is at least one selected from FEF grade, FF grade, HAF grade, ISAF grade and SAF grade. Pneumatic tires,
(3) The pneumatic tire according to (2) above, wherein (B) carbon black is FEF grade grade,
(4) The pneumatic tire according to any one of the above (1) to (3), wherein in the rubber composition, (A) the rubber component contains an amine-modified conjugated diene polymer.
(5) The pneumatic tire according to (4), wherein the amine-modified conjugated diene polymer is a protic amine-modified conjugated diene polymer,
(6) The pneumatic tire according to (4) or (5), wherein the amine-modified conjugated diene polymer is a primary amine-modified conjugated diene polymer.
(7) The pneumatic tire according to (6), wherein the primary amine-modified conjugated diene polymer is obtained by reacting a protected primary amine compound with an active terminal of the conjugated diene polymer.
(8) The above conjugated diene polymer is obtained by anionic polymerization of a conjugated diene compound alone or a conjugated diene compound and an aromatic vinyl compound in an organic solvent using an organic alkali metal compound as an initiator. The pneumatic tire according to (7),
(9) The pneumatic tire according to (8), wherein the conjugated diene polymer is polybutadiene,
(10) The pneumatic tire according to any one of (7) to (9), wherein the protected primary amine compound is N, N-bis (trimethylsilyl) aminopropyltriethoxysilane.
(11) The pneumatic tire according to any one of (1) to (10), wherein an upper twist coefficient of the reinforcing cord is 0.3 to 0.7.
(12) The pneumatic tire according to any one of (1) to (11), wherein a twisting coefficient of the reinforcement cord is 0.3 to 0.7.
(13) The pneumatic tire according to (12), wherein the upper twist coefficient and the lower twist coefficient are different from each other,
(14) The pneumatic tire according to (13), wherein the upper twist coefficient is larger than the lower twist coefficient,
(15) The pneumatic tire according to any one of (1) to (14), wherein the cellulosic fiber is made of rayon or lyocell.
(16) The pneumatic tire according to any one of the above (1) to (15), wherein the reinforcing cord is made of an organic fiber having a melting point of 300 ° C. or higher.
(17) The pneumatic tire according to any one of (1) to (16), wherein the rubber composition is used for the side reinforcing layer.
(18) The pneumatic tire according to any one of (1) to (17), wherein the rubber composition is used as a bead filler, and (19) the rubber composition as a side reinforcing layer and a bead filler. The pneumatic tire according to any one of the above (1) to (18),
Is to provide.

  According to the present invention, a rubber composition having a vulcanized rubber property having an elastic modulus at 100% elongation of 10 MPa or more and a tangent loss tan δ of Σ value at 28 ° C. to 150 ° C. of 6.0 or less, particularly a tire. Pneumatics with improved run-flat durability without sacrificing rolling resistance and riding comfort during normal running by using a specific cellulosic fiber for the carcass layer and for side reinforcement layers and / or bead fillers Tires can be provided.

[Pneumatic tire]
First, the pneumatic tire of the present invention will be described below with reference to the drawings. Drawing 1 is a mimetic diagram showing the section of one embodiment of the pneumatic tire of the present invention.
In FIG. 1, a preferred embodiment of the pneumatic tire according to the present invention is toroidally connected between a pair of beadcos 1, 1 ′ (1 ′ is not shown), and both ends of the bead core 1 are connected to the outside from the inside of the tire. A carcass layer 2 composed of at least one radial carcass ply in which a plurality of reinforcing cords wound in parallel and embedded in a covering rubber are disposed on the outer side in the tire axial direction of the side region of the carcass layer 2 A side rubber layer 3 that forms a portion, a tread rubber layer 4 that is disposed outside the crown region of the carcass layer 2 in the tire radial direction to form a ground contact portion, and a crown region of the tread rubber layer 4 and the carcass layer 2. A belt layer 5 disposed between them to form a reinforcing belt, an inner liner 6 disposed on the entire inner surface of the carcass layer 2 to form an airtight film, A bead filler 7 disposed between the body portion of the carcass layer 2 extending from the core 1 to the other bead core 1 ′ and a winding portion wound up on the bead core 1, and the bead filler 7 in the side region of the carcass layer Air including at least one side reinforcing layer 8 having a substantially crescent-shaped cross section along the tire rotation axis between the carcass layer 2 and the inner liner 6 from the side portion to the shoulder region 10. This is a tire. By using the rubber composition according to the present invention for the side reinforcing layer 8 and / or the bead filler 7 of this pneumatic tire and using a specific cellulosic fiber for the reinforcing cord of the carcass ply constituting the carcass layer 2, The pneumatic tire of the invention can achieve the above-described effects.

[Rubber composition]
In the pneumatic tire of the present invention described above, the side reinforcing layer 8 and / or the bead filler 7 includes (A) a rubber component and 100 parts by mass of (B) 55 parts by mass of carbon black, and A rubber composition having an elastic modulus at 100% elongation (M100) of 10 MPa or more and a sigma value of tangent loss tan δ at 28 ° C. to 150 ° C. of 6.0 or less in vulcanized rubber properties can be used.
((A) rubber component)
As the rubber component (A) in the rubber composition according to the present invention, one containing an amine-modified conjugated diene polymer obtained by amine-modifying a conjugated diene polymer can be preferably used. A polymer containing 30% by mass or more, preferably 50% by mass or more can be used. When the rubber component contains the modified conjugated diene polymer in an amount of 30% by mass or more, the resulting rubber composition can provide a pneumatic tire with low heat generation and improved run-flat running durability.

As the amine-modified conjugated diene polymer, a polymer in which a protonic amino group which is an amine functional group and / or an amino group protected by a detachable group is introduced as a functional group for modification in the molecule is preferable. Further, those having a silicon atom-containing functional group introduced are preferred.
Examples of the functional group containing a silicon atom include a silane group formed by bonding a hydrocarbyloxy group and / or a hydroxy group to a silicon atom.
Such a functional group for modification may be present at any of the polymerization initiation terminal, the side chain and the polymerization active terminal of the conjugated diene polymer. A silicon atom having an amino group protected with a protic amino group and / or a detachable group and a hydrocarbyloxy group and / or a hydroxy group, particularly preferably one or two hydrocarbyloxy groups, And / or a silicon atom having a hydroxy group bonded thereto.

Examples of the protic amino group include at least one selected from a primary amino group, a secondary amino group, and salts thereof.
On the other hand, examples of the amino group protected with a detachable group include N, N-bis (trihydrocarbylsilyl) amino group and N- (trihydrocarbylsilyl) imino group. Preferably, the hydrocarbyl group is carbon. The trialkylsilyl group which is a C1-C10 alkyl group can be mentioned, Especially preferably, a trimethylsilyl group can be mentioned.
An example of a primary amino group protected with a detachable group (also referred to as a protected primary amino group) is N, N-bis (trimethylsilyl) amino group, which is protected with a detachable group. Examples of the secondary amino group include N- (trimethylsilyl) imino group. The N- (trimethylsilyl) imino group-containing group may be an acyclic imine residue or a cyclic imine residue.

  Among the amine-modified conjugated diene polymers described above, as a primary amine-modified conjugated diene polymer modified with a primary amino group, a protected primary amine compound is reacted with the active terminal of the conjugated diene polymer. The obtained primary amine-modified conjugated diene polymer modified with a protected primary amino group is preferred.

<Conjugated diene polymer>
The conjugated diene polymer used for modification may be a conjugated diene compound homopolymer or a copolymer of a conjugated diene compound and an aromatic vinyl compound.
Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and the like. Is mentioned. These may be used alone or in combination of two or more, and among these, 1,3-butadiene is particularly preferable.
Examples of the aromatic vinyl compound used for copolymerization with the conjugated diene compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, and 4-cyclohexylstyrene. 2,4,6-trimethylstyrene and the like. These may be used alone or in combination of two or more, and among these, styrene is particularly preferable.
As the conjugated diene polymer, polybutadiene or styrene-butadiene copolymer is preferable, and polybutadiene is particularly preferable.

  In order to modify the active end of the conjugated diene polymer by reacting with a protected primary amine, it is preferable that the conjugated diene polymer has at least 10% polymer chains having a living property or pseudo-living property. As such a polymerization reaction having a living property, an organic alkali metal compound is used as an initiator, and a conjugated diene compound alone or a reaction in which an conjugated diene compound and an aromatic vinyl compound are anionically polymerized in an organic solvent, or an organic solvent. Among them, a conjugated diene compound alone or a reaction in which a conjugated diene compound and an aromatic vinyl compound are coordinated anionic polymerized by a catalyst containing a lanthanum series rare earth element compound can be mentioned. The former is preferable because a conjugated diene moiety having a higher vinyl bond content than the latter can be obtained. Heat resistance can be improved by increasing the amount of vinyl bonds.

  As the organic alkali metal compound used as an initiator for the above-mentioned anionic polymerization, an organic lithium compound is preferable. The organolithium compound is not particularly limited, but hydrocarbyl lithium and lithium amide compounds are preferably used. When the former hydrocarbyl lithium is used, it has a hydrocarbyl group at the polymerization initiation terminal and the other terminal has polymerization activity. A conjugated diene polymer as a site is obtained. When the latter lithium amide compound is used, a conjugated diene polymer having a nitrogen-containing group at the polymerization initiation terminal and the other terminal being a polymerization active site is obtained.

  As the hydrocarbyl lithium, those having a hydrocarbyl group having 2 to 20 carbon atoms are preferable, for example, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl. Examples include lithium, phenyllithium, 2-naphthyllithium, 2-butylphenyllithium, 4-phenylbutyllithium, cyclohexyllithium, cyclobenthyllithium, and reactive organisms of diisopropenylbenzene and butyllithium. Of these, n-butyllithium is particularly preferred.

On the other hand, examples of the lithium amide compound include lithium hexamethylene imide, lithium pyrrolidide, lithium piperide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethyl amide, lithium diethyl amide, lithium dibutyl amide, lithium dipropyl amide, and lithium disulfide. Heptylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiverazide, lithium ethylpropylamide, lithium ethylbutyramide, lithium ethylbenzylamide, lithium methylphenethylamide, etc. Is mentioned. Among these, from the viewpoint of the interaction effect on carbon black and the ability to initiate polymerization, cyclic hexaamides such as lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, and lithium dodecamethylene imide are preferable, In particular, lithium hexamethylene imide and lithium pyrrolidide are suitable.
In general, these lithium amide compounds prepared from a secondary amine and a lithium compound can be used for polymerization, but can also be prepared in a polymerization system (in-situ). The amount of the polymerization initiator used is preferably selected in the range of 0.2 to 20 mmol per 100 g of monomer.

A method for producing a conjugated diene polymer by anionic polymerization using the organolithium compound as a polymerization initiator is not particularly limited, and a conventionally known method can be used.
Specifically, in an organic solvent inert to the reaction, for example, a hydrocarbon solvent such as an aliphatic, alicyclic, and aromatic hydrocarbon compound, the conjugated diene compound or the conjugated diene compound and the aromatic vinyl compound are If desired, a conjugated diene polymer having an active terminal can be obtained by anionic polymerization in the presence of a randomizer to be used, if desired, using a lithium compound as a polymerization initiator.
In addition, when an organic lithium compound is used as a polymerization initiator, it has not only a conjugated diene polymer having an active end but also an active end, compared to the case of using a catalyst containing the lanthanum series rare earth element compound described above. A copolymer of a conjugated diene compound and an aromatic vinyl compound can also be obtained efficiently.

The hydrocarbon solvent is preferably one having 3 to 8 carbon atoms, such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2. -Butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or in combination of two or more.
The monomer concentration in the solvent is preferably 5 to 50% by mass, more preferably 10 to 30% by mass. When copolymerization is performed using a conjugated diene compound and an aromatic vinyl compound, the content of the aromatic vinyl compound in the charged monomer mixture is preferably in the range of 55% by mass or less.

  The randomizer used as desired is a control of the microstructure of the conjugated diene polymer, such as an increase in 1,2 bonds in the butadiene portion in the butadiene-styrene copolymer, an increase in 3,4 bonds in the isoprene polymer, or the like. It is a compound having an effect of controlling the composition distribution of monomer units in a conjugated diene compound-aromatic vinyl compound copolymer, for example, randomizing butadiene units and styrene units in a butadiene-styrene copolymer. The randomizer is not particularly limited, and any one of known compounds generally used as a conventional randomizer can be appropriately selected and used. Specifically, dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, oxolanylpropane oligomers [especially those containing 2,2-bis (2-tetrahydrofuryl) -propane, etc.], triethylamine, pyridine N-methylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, ethers such as 1,2-dipiperidinoethane, and tertiary amines. Further, potassium salts such as potassium tert-amylate and potassium tert-butoxide, and sodium salts such as sodium tert-amylate can also be used.

One of these randomizers may be used alone, or two or more thereof may be used in combination. The amount used is preferably selected in the range of 0.01 to 1000 molar equivalents per mole of the lithium compound.
The temperature in this polymerization reaction is preferably selected in the range of 0 to 150 ° C, more preferably 20 to 130 ° C. The polymerization reaction can be carried out under generated pressure, but it is usually desirable to operate at a pressure sufficient to keep the monomer in a substantially liquid phase. That is, the pressure depends on the particular material being polymerized, the polymerization medium used and the polymerization temperature, but higher pressures can be used if desired, such pressure being a gas that is inert with respect to the polymerization reaction. Can be obtained by an appropriate method such as pressurizing.

<Modifier>
In the present invention, a primary amine-modified conjugated diene polymer is reacted with a protected primary amine compound as a modifier on the active terminal of the conjugated diene polymer having an active terminal obtained as described above. Can be manufactured. As the protected primary amine compound, an alkoxysilane compound having a protected primary amino group is suitable.
Examples of the alkoxysilane compound having a protected primary amino group used as the modifier include N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane, 1-trimethylsilyl-2,2-dimethoxy-1-aza-2- Silacyclopentane, N, N-bis (trimethylsilyl) aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) aminopropyltriethoxysilane, N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane, N, N -Bis (trimethylsilyl) aminoethyltrimethoxysilane, N, N-bis (trimethylsilyl) aminoethyltriethoxysilane, N, N-bis (trimethylsilyl) aminoethylmethyldimethoxysilane and N, N-bis (trimethylsilyl) Aminoethylmethyldiethoxysilane and the like, preferably N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane, N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane or 1-trimethylsilyl-2 , 2-dimethoxy-1-aza-2-silacyclopentane.

Moreover, as a modifier, N-methyl-N-trimethylsilylaminopropyl (methyl) dimethoxysilane, N-methyl-N-trimethylsilylaminopropyl (methyl) diethoxysilane, N-trimethylsilyl (hexamethyleneimin-2-yl) Propyl (methyl) dimethoxysilane, N-trimethylsilyl (hexamethyleneimin-2-yl) propyl (methyl) diethoxysilane, N-trimethylsilyl (pyrrolidin-2-yl) propyl (methyl) dimethoxysilane, N-trimethylsilyl (pyrrolidine- 2-yl) propyl (methyl) diethoxysilane, N-trimethylsilyl (piperidin-2-yl) propyl (methyl) dimethoxysilane, N-trimethylsilyl (piperidin-2-yl) propyl (methyl) diethoxysila N-trimethylsilyl (imidazol-2-yl) propyl (methyl) dimethoxysilane, N-trimethylsilyl (imidazol-2-yl) propyl (methyl) diethoxysilane, N-trimethylsilyl (4,5-dihydroimidazol-5-yl) ) Alkoxysilane compounds having protected secondary amino groups such as propyl (methyl) dimethoxysilane, N-trimethylsilyl (4,5-dihydroimidazol-5-yl) propyl (methyl) diethoxysilane; N- (1,3 -Dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine, N- (1-methylethylidene) -3- (triethoxysilyl) -1-propanamine, N-ethylidene-3- (triethoxy Silyl) -1-propanamine, N- (1-methylpropiyl) Den) -3- (triethoxysilyl) -1-propanamine, N- (4-N, N-dimethylaminobenzylidene) -3- (triethoxysilyl) -1-propanamine, N- (cyclohexylidene) Alkoxysilane compounds having an imino group such as -3- (triethoxysilyl) -1-propanamine; 3-dimethylaminopropyl (triethoxy) silane, 3-dimethylaminopropyl (trimethoxy) silane, 3-diethylaminopropyl (triethoxy) Silane, 3-diethylaminopropyl (trimethoxy) silane, 2-dimethylaminoethyl (triethoxy) silane, 2-dimethylaminoethyl (trimethoxy) silane, 3-dimethylaminopropyl (diethoxy) methylsilane, 3-dibutylaminopropyl (triethoxy) silane Examples thereof include alkoxysilane compounds having an amino group such as lan.
These modifiers may be used individually by 1 type, and may be used in combination of 2 or more types. The modifier may be a partial condensate.
Here, the partial condensate means a product in which a part (not all) of the modifier SiOR is SiOSi bonded by condensation.

In the modification reaction with the modifying agent, the amount of the modifying agent used is preferably 0.5 to 200 mmol / kg · conjugated diene polymer. The amount used is more preferably 1 to 100 mmol / kg · conjugated diene polymer, and particularly preferably 2 to 50 mmol / kg · conjugated diene polymer. Here, the conjugated diene polymer means the mass of only a polymer that does not contain an additive such as an anti-aging agent added during or after the production. By making the usage-amount of a modifier into the said range, it is excellent in the dispersibility of a filler, especially carbon black, and the fracture resistance after vulcanization and low heat build-up are improved.
The method of adding the modifier is not particularly limited, and examples thereof include a method of adding all at once, a method of adding in divided portions, a method of adding continuously, and the like. preferable.
Further, the modifier can be bonded to any of the polymer main chain and the side chain other than the polymerization initiation terminal and the polymerization termination terminal, but it can suppress the loss of energy from the polymer terminal and improve the low heat generation. Therefore, it is preferably introduced at the polymerization initiation terminal or the polymerization termination terminal.

<Condensation accelerator>
In the present invention, a condensation accelerator is preferably used in order to accelerate the condensation reaction involving the alkoxysilane compound having a protected primary amino group used as the modifier.
Examples of such a condensation accelerator include a compound containing a tertiary amino group, or among group 3, 4, 5, 12, 13, 14, and 15 of the periodic table (long period type). An organic compound containing one or more elements belonging to any of the above can be used. Furthermore, as a condensation accelerator, an alkoxide, a carboxyl containing at least one metal selected from the group consisting of titanium (Ti), zirconium (Zr), bismuth (Bi), aluminum (Al), and tin (Sn). It is preferably an acid salt or an acetylacetonate complex salt.
The condensation accelerator used here can be added before the modification reaction, but is preferably added to the modification reaction system during and / or after the modification reaction. When added before the denaturation reaction, a direct reaction with the active end may occur, and a hydrocarbyloxy group having a protected primary amino group at the active end may not be introduced.
The addition time of the condensation accelerator is usually 5 minutes to 5 hours after the start of the modification reaction, preferably 15 minutes to 1 hour after the start of the modification reaction.

  Specific examples of the condensation accelerator include tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, tetra-n-butoxytitanium, tetra-n-butoxytitanium oligomer, tetra-sec- Butoxytitanium, tetra-tert-butoxytitanium, tetra (2-ethylhexyl) titanium, bis (octanediolate) bis (2-ethylhexyl) titanium, tetra (octanediolate) titanium, titanium lactate, titanium dipropoxybis (triethanol Aminate), titanium dibutoxybis (triethanolaminate), titanium tributoxy systemate, titanium tripropoxy systemate, titanium ethyl Sildiolate, Titanium tripropoxyacetylacetonate, Titanium dipropoxybis (acetylacetonate), Titanium tripropoxyethylacetoacetate, Titaniumpropoxyacetylacetonatebis (ethylacetoacetate), Titanium tributoxyacetylacetonate, Titanium dibutoxybis ( Acetylacetonate), titanium tributoxyethyl acetoacetate, titanium butoxyacetylacetonate bis (ethylacetoacetate), titanium tetrakis (acetylacetonate), titanium diacetylacetonate bis (ethylacetoacetate), bis (2-ethylhexano) Ate) titanium oxide, bis (laurate) titanium oxide, bis (naphthene) ) Titanium oxide, bis (stearate) titanium oxide, bis (oleate) titanium oxide, bis (linoleate) titanium oxide, tetrakis (2-ethylhexanoate) titanium, tetrakis (laurate) titanium, tetrakis (naphthenate) titanium, tetrakis Examples thereof include compounds containing titanium such as (stearate) titanium, tetrakis (oleate) titanium, tetrakis (linoleate) titanium, and the like.

  Examples of the condensation accelerator include tris (2-ethylhexanoate) bismuth, tris (laurate) bismuth, tris (naphthenate) bismuth, tris (stearate) bismuth, tris (oleate) bismuth, and tris (linoleate). Bismuth, tetraethoxyzirconium, tetra-n-propoxyzirconium, tetraisopropoxyzirconium, tetra-n-butoxyzirconium, tetra-sec-butoxyzirconium, tetra-tert-butoxyzirconium, tetra (2-ethylhexyl) zirconium, zirconium tributoxy Stearate, zirconium tributoxyacetylacetonate, zirconium dibutoxybis (acetylacetonate), zirconium tributoxyethylacetoacetate Zirconium butoxyacetylacetonate bis (ethylacetoacetate), zirconium tetrakis (acetylacetonate), zirconium diacetylacetonate bis (ethylacetoacetate), bis (2-ethylhexanoate) zirconium oxide, bis (laurate) zirconium oxide, Bis (naphthenate) zirconium oxide, bis (stearate) zirconium oxide, bis (oleate) zirconium oxide, bis (linoleate) zirconium oxide, tetrakis (2-ethylhexanoate) zirconium, tetrakis (laurate) zirconium, tetrakis (naphthenate) Zirconium, tetrakis (stearate) zirconium, tetrakis (oleate) zirconium, Tetrakis (linolate) zirconium and the like.

  Also, triethoxyaluminum, tri-n-propoxyaluminum, triisopropoxyaluminum, tri-n-butoxyaluminum, tri-sec-butoxyaluminum, tri-tert-butoxyaluminum, tri (2-1 ethylhexyl) aluminum, aluminum di Butoxy systemate, aluminum dibutoxyacetylacetonate, aluminum butoxybis (acetylacetonate), aluminum dibutoxyethylacetoacetate, aluminum tris (acetylacetonate), aluminum tris (ethylacetoacetate), tris (2-ethylhexanoate) Ate) aluminum, tris (laurate) aluminum, tris (naphthenate) aluminum, tris (stearate) aluminum, Squirrel (oleate) aluminum, tris (linolate) aluminum, and the like.

Of the above condensation accelerators, titanium compounds are preferable, and titanium metal alkoxides, titanium metal carboxylates, or titanium metal acetylacetonate complex salts are particularly preferable.
The amount of the condensation accelerator used is preferably such that the number of moles of the compound is 0.1 to 10 as the molar ratio to the total amount of hydrocarbyloxy groups present in the reaction system, and 0.5 to 5 Particularly preferred. By setting the use amount of the condensation accelerator within the above range, the condensation reaction proceeds efficiently.

The condensation reaction in the present invention proceeds in the presence of the above-described condensation accelerator and water vapor or water. An example of the presence of water vapor is a solvent removal treatment by steam stripping, and the condensation reaction proceeds during steam stripping.
The condensation reaction may be carried out in an aqueous solution, and the condensation reaction temperature is preferably 85 to 180 ° C, more preferably 100 to 170 ° C, and particularly preferably 110 to 150 ° C.
By setting the temperature during the condensation reaction within the above range, the condensation reaction can be efficiently advanced and completed, and the deterioration of the quality due to the aging reaction of the polymer due to the change over time of the resulting modified conjugated diene polymer can be suppressed. Can do.

The condensation reaction time is usually about 5 minutes to 10 hours, preferably about 15 minutes to 5 hours. By setting the condensation reaction time within the above range, the condensation reaction can be completed smoothly.
In addition, the pressure of the reaction system at the time of condensation reaction is 0.01-20 Mpa normally, Preferably it is 0.05-10 Mpa.
There is no restriction | limiting in particular about the format in the case of performing a condensation reaction in aqueous solution, You may carry out by a continuous type using apparatuses, such as a batch type reactor and a multistage continuous type reactor. Moreover, you may perform this condensation reaction and a desolvent simultaneously.
The primary amino group derived from the modifying agent of the modified conjugated diene polymer of the present invention is generated by performing the deprotection treatment as described above. Specific examples of suitable deprotection treatments other than the solvent removal treatment using steam such as steam stripping described above will be described in detail below.
That is, the protecting group on the primary amino group is converted to a free primary amino group by hydrolysis. By removing the solvent, a modified conjugated diene polymer having a primary amino group can be obtained. In addition, the deprotection treatment of the protected primary amino group derived from the modifier can be performed as necessary in any stage from the step including the condensation treatment to the solvent removal to the dry polymer.

<Modified conjugated diene polymer>
The modified conjugated diene polymer thus obtained has a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of preferably 10 to 150, more preferably _{15 to} 100. When the Mooney viscosity is less than 10, sufficient rubber physical properties such as fracture resistance characteristics cannot be obtained.
The Mooney-viscosity (ML _{1 + 4} , 130 ° C.) of the unvulcanized rubber composition according to the present invention containing the modified conjugated diene polymer is preferably 10 to 150, more preferably 30 to 100. is there.
The modified conjugated diene polymer used in the rubber composition according to the present invention has a ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), that is, the molecular weight distribution (Mw / Mn) is 1. It is preferable that it is -3, and it is more preferable that it is 1.1-2.7.
By making the molecular weight distribution (Mw / Mn) of the modified conjugated diene polymer within the above range, even if the modified conjugated diene polymer is blended with the rubber composition, the workability of the rubber composition may be reduced. And kneading is easy, and the physical properties of the rubber composition can be sufficiently improved.

The modified conjugated diene polymer used in the rubber composition according to the present invention preferably has a number average molecular weight (Mn) of 100,000 to 500,000, preferably 150,000 to 300,000. Is more preferable. By setting the number average molecular weight of the modified conjugated diene polymer within the above range, the elastic modulus of the vulcanizate is reduced and an increase in hysteresis loss is suppressed to obtain excellent fracture resistance, and the modified conjugated diene polymer Excellent kneading workability of the rubber composition containing can be obtained.
The modified conjugated diene polymer used in the rubber composition according to the present invention may be used singly or in combination of two or more.

<Other rubber components>
(A) In the rubber component, examples of the rubber component used in combination with the modified conjugated diene polymer include natural rubber and other diene synthetic rubbers. Examples of other diene synthetic rubbers include styrene-butadiene copolymer. Polymer (SBR), polybutadiene (BR), polyisoprene (IR), styrene-isoprene copolymer (SIR), butyl rubber (IIR), halogenated butyl rubber, ethylene-propylene-diene terpolymer (EPDM) and These mixtures are mentioned. Further, some or all of the other diene-based synthetic rubber is more preferably a diene-based modified rubber having a branched structure by using a polyfunctional modifier, for example, a modifier such as tin tetrachloride. .

((B) Carbon black)
In the rubber composition according to the present invention, it is necessary to use carbon black as the component (B) at a ratio of 55 parts by mass or more with respect to 100 parts by mass of the rubber component (A) described above. When the amount of carbon black is less than 55 parts by mass, sufficient reinforcing effect is not exhibited, and in the vulcanized rubber properties of the resulting rubber composition, the elastic modulus at 100% elongation (M100) described later does not exceed 10 MPa. There is. If the amount of carbon black is too large, the Σ value at 28 ° C. to 150 ° C. of the tangent loss tan δ described later may not be 6.0 or less in the physical properties of the vulcanized rubber of the resulting rubber composition. Therefore, the preferable amount of the carbon black is 55 to 70 parts by mass, and more preferably 60 to 70 parts by mass.
As the carbon black, in order that the vulcanized rubber physical properties of the obtained rubber composition satisfy the above vulcanized rubber physical properties, FEF grade, FF grade, HAF grade, ISAF grade and SAF grade It is preferable to use at least one selected from among them, and the FEF grade grade is particularly preferable.

Further, the rubber composition according to the present invention includes various chemicals usually used in the rubber industry, for example, a vulcanizing agent, a vulcanization accelerator, a process oil, an aging, as desired, as long as the effects of the present invention are not impaired. An inhibitor, a scorch inhibitor, zinc white, stearic acid and the like can be contained.
As said vulcanizing agent, sulfur etc. are mentioned, The usage-amount is 0.1-10.0 mass parts as sulfur content with respect to 100 mass parts of (A) rubber components, More preferably, it is 1.0. -5.0 parts by mass. If the amount is less than 0.1 parts by mass, the rupture strength, wear resistance, and low heat build-up of the vulcanized rubber may be reduced. If the amount exceeds 10.0 parts by mass, the rubber elasticity is lost.
The vulcanization accelerator that can be used in the present invention is not particularly limited, and examples thereof include M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), and CZ (N-cyclohexyl-2-benzothiazyl). Thiophene vulcanization accelerators such as thiazoles such as sulfenamide), guanidines such as DPG (diphenylguanidine), or thiurams such as TOT (tetrakis (2-ethylhexyl) thiuram disulfide). The amount used is preferably from 0.1 to 5.0 parts by weight, more preferably from 0.2 to 3.0 parts by weight, per 100 parts by weight of the (A) rubber component.

Examples of the process oil used as a softening agent that can be used in the rubber composition according to the present invention include paraffinic, naphthenic, and aromatic oils. Aromatics are used for applications that emphasize tensile strength and wear resistance, and naphthenic or paraffinic systems are used for applications that emphasize hysteresis loss and low-temperature characteristics. The amount used is preferably 0 to 100 parts by mass with respect to 100 parts by mass of the rubber component (A), and if it is 100 parts by mass or less, the tensile strength and low heat build-up (low fuel consumption) of the vulcanized rubber deteriorate. Can be suppressed.
Furthermore, examples of the antioxidant that can be used in the rubber composition according to the present invention include 3C (N-isopropyl-N′-phenyl-p-phenylenediamine, 6C [N- (1,3-dimethylbutyl) -N ′). -Phenyl-p-phenylenediamine], AW (6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline), high-temperature condensate of diphenylamine and acetone, etc. (A) 0.1-5.0 mass part is preferable with respect to 100 mass parts of rubber components, More preferably, it is 0.3-3.0 mass part.

(Physical properties of vulcanized rubber of rubber composition)
The rubber composition according to the present invention is required to have a vulcanized rubber property having an elastic modulus at 100% elongation (M100) of 10 MPa or more. When the elastic modulus (M100) is less than 10 MPa, the tire is not sufficiently bent during run-flat running, and the run-flat running durability of the tire is reduced. Preferred M100 is 10.5 MPa or more, and the upper limit thereof is not particularly limited, but is usually about 13 MPa.
The elastic modulus at 100% elongation (M100) is a value measured by the following method.
<Measurement method of elastic modulus at 100% elongation (M100)>
An elastic modulus at 100% elongation is measured based on JIS K 6251 for a slab sheet having a thickness of 2 mm obtained by vulcanizing the rubber composition at 160 ° C. for 12 minutes.

Further, as the physical property of the vulcanized rubber, the Σ value [Σtan δ (28 to 150 ° C.)] at 28 ° C. to 150 ° C. of the tangent loss tan δ is required to be 6.0 or less. When the sigma value of tan δ exceeds 6.0, the heat generation of the tire during run-flat running is large, and the run-flat running durability of the tire is lowered. The lower limit of Σtan δ (28 to 150 ° C.) is not particularly limited, but is usually about 5.
The Σtanδ (28 to 150 ° C.) is a value measured by the following method.
<Measuring method of Σtan δ (28 to 150 ° C.)>
A sheet having a width of 5 mm and a length of 40 mm was cut out from a slab sheet having a thickness of 2 mm obtained by vulcanizing the rubber composition at 160 ° C. for 12 minutes to prepare a sample. About this sample, a tangent loss tan δ was measured under the measurement conditions of a distance between chucks of 10 mm, an initial strain of 200 μm, a dynamic strain of 1%, a frequency of 52 Hz, and a measurement start temperature of 25 to 200 ° C. using a spectrometer manufactured by Ueshima Seisakusho. As shown in FIG. 2, the relationship between temperature and tan δ is graphed, the area of the shaded portion is obtained, and the value is Σ tan δ (28 to 150 ° C.).

(Preparation of rubber composition)
The rubber composition according to the present invention is obtained by kneading using a kneading machine such as a Banbury mixer, a roll, an internal mixer or the like according to the above compounding prescription, vulcanized after molding, and in FIG. Used as a side reinforcing layer 8 and / or a bead filler 7 of a pneumatic tire.

[Cellulose fiber]
In the tire according to the present invention, the carcass layer has one or more carcass plies in which a plurality of reinforcing cords arranged in parallel are embedded in the covering rubber. It is necessary to have rigidity represented by a cord elastic modulus of dtex or more (at a temperature of 180 ° C. and a stress applied with a force of 29.4 N per reinforcing cord). This is because with the rigidity represented by the cord elastic modulus of less than 50 cN / dtex, the deflection of the tire increases during the run-flat running, and the run-flat durability performance may deteriorate.

  This rigidity can be determined using the stress-elongation curve of the reinforcing cord. FIG. 3 is a graph showing an example of a stress (load) -elongation curve of a reinforcing cord. As shown in FIG. 3, the force applied per cord at the time of loading from the inner pressure filling of the tire is estimated to be 3 kgf (about 29.4 N), and the stress (load) -elongation curve C at about 29. A tangent line S at the time of 4N stress is drawn, and the slope of the tangent line S is calculated as the cord elastic modulus. The cord elastic modulus indicated by the unit “N /% (180 ° C. · 29.4 N)” and the unit “N / dtex (180 ° C. · 29.4 N)” is obtained by using the stress-elongation curve of the same reinforcing cord. For example, in a 1840 dtex / 3 cord structure, about 34.3 N (3.5 kgf) /% (180 ° C. · 29.4 N) corresponds to 50 cN / dtex (180 ° C. · 29.4 N). .

Reinforcing cords made from cellulosic fibers can be produced by dipping (hereinafter referred to as DIP) the cellulosic fiber cords. Specifically, a reinforcing cord having a predetermined rigidity with respect to the fiber stretching direction can be obtained by using a DIP tension for the fiber cord, that is, by performing a DIP treatment in a state where the predetermined tension is applied. . For example, a reinforced cord having a cord elastic modulus of about 39.2 N (4 kgf) /% (180 ° C., 29.4 N) or more can be obtained by performing DIP treatment by raising the DIP tension to 0.71 cN / dtex or more. can get. No conventional rayon yarn or lyocell yarn is DIP treated with such DIP tension.
By using such a high-strength, high-strength reinforcing cord for the carcass ply, the spring during normal internal pressure hardly changes and the vertical spring during run-flat running can be specifically improved. Thus, a synergistic effect with the rubber composition can suppress the amount of bending during run-flat travel and improve run-flat durability performance. That is, the run-flat durability performance can be improved without impairing the riding comfort when the tire weight increases and the air pressure is filled, that is, when the pressure is filled (hereinafter referred to as INF).

The upper twist coefficient and the lower twist coefficient of the reinforcing cord are each preferably in the range of 0.3 to 0.7, more preferably in the range of 0.35 to 0.7, and still more preferably in the range of 0.4 to 0.7. . Here, the upper twist coefficient and the lower twist coefficient are coefficients calculated by the following equations. In general, the strength and fatigue of a reinforcing cord depend on the twisting coefficient of the fiber used. When the twisting coefficient is small, the strength is improved, but the fatigue is lowered. Conversely, when the twisting coefficient is large, the fatigue is improved. There is a conflicting relationship that the strength decreases. If the upper twist coefficient and the lower twist coefficient of the reinforcing cord are within the above ranges, the strength and fatigue properties of the cord can be favorably maintained, which is preferable.
Further, the upper twist coefficient and the lower twist coefficient of the reinforcing cord are preferably different, and the upper twist coefficient is more preferably larger than the lower twist coefficient. The difference between the upper twist coefficient and the lower twist coefficient is preferable because the above-described cord strength and fatigue can be maintained well, and excellent run-flat durability and riding comfort can be obtained.

(In the formula, N _t1 : Lower twist coefficient, N _t2 : Upper twist coefficient, N: Number of twists (times / 10 cm), D ₁ : Total dtex of cord, D ₂ : Half of total dtex of cord, ρ: Represents specific gravity.)

  Preferred examples of the cellulosic fiber used as the raw material for the reinforcing cord include fibers such as rayon and lyocell. The lyocell fiber is, for example, a cellulosic fiber obtained from a raw material cellulose by a solvent spinning method. For example, as described in JP-B-60-28848, JP-T-11-504959, etc., an organic solvent A solution containing cellulose dissolved in water and a non-solvent such as water is spun into air or a non-precipitating medium, and pulled at a speed higher than the speed at which the fiber-forming solution discharged from the spinneret is fed. After stretching at a draw ratio of at least twice, it is obtained by treating with a non-solvent.

  The reinforcing cord is preferably an organic fiber having a melting point of 300 ° C. or higher. Examples of such organic fibers include cellulosic fibers, among which rayon fibers and lyocell fibers are preferable, and lyocell fibers are more preferable. If the melting point of the organic fiber constituting the reinforcing cord is within the above range, the ply cord does not melt even if the temperature in the tire during the run-flat running becomes very high.

(Production of pneumatic tires)
In the tire of the present invention, the rubber composition according to the present invention described above is used, and the reinforcing cord constituting the carcass ply is made from the above-described cellulosic fiber, preferably the rubber composition according to the present invention. The product is manufactured by a normal method for manufacturing a run flat tire using the side reinforcing layer 8 and / or the bead filler 7. That is, as described above, the rubber composition according to the present invention containing various chemicals is processed into each member at an unvulcanized stage, and pasted and molded by a normal method on a tire molding machine, and a raw tire is molded. Is done. The green tire is heated and pressed in a vulcanizer to obtain a tire.

As shown in FIG. 1, the carcass layer 2 is composed of at least one carcass ply, and can be composed of two or more carcass plies. In that case, the end portion of one carcass ply can be folded back around the bead core 1 to form a folded end portion, and the other carcass ply is disposed in the side rubber layer 3 outside the folded end portion. be able to.
The pneumatic tire of the present invention thus obtained has improved run-flat durability without impairing rolling resistance and riding comfort during normal running.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Various characteristics were measured according to the following methods.
<< Physical Properties of Unmodified or Modified Conjugated Diene Polymer >>
<Microstructure analysis method>
The vinyl bond content (%) was measured by an infrared method (Morero method).
<Measurement of Number Average Molecular Weight (Mn), Weight Average Molecular Weight (Mw) and Molecular Weight Distribution (Mw / Mn)>
It measured using GPC [the Tosoh make, HLC-8020] using the refractometer as a detector, and showed it by polystyrene conversion which used the monodisperse polystyrene as the standard. The column is GMHXL [manufactured by Tosoh], and the eluent is tetrahydrofuran.

<Measurement of primary amino group content (mmol / kg)>
First, the polymer was dissolved in toluene, and then the amino group-containing compound not bound to the polymer was separated from the rubber by precipitation in a large amount of methanol, followed by drying. Using this treated polymer as a sample, the total amino group content was quantified by the “total amine value test method” described in JIS K7237. Subsequently, the contents of secondary amino groups and tertiary amino groups were quantified by the “acetylacetone blocked method” using the polymer subjected to the above treatment as a sample. As a solvent for dissolving the sample, o-nitrotoluene was used, acetylacetone was added, and potentiometric titration was performed with a perchloracetic acid solution. The primary amino group bound to the polymer by subtracting the secondary amino group content and tertiary amino group content from the total amino group content to determine the primary amino group content (mmol) and dividing by the polymer mass used in the analysis. The content (mmol / kg) was determined.

<< Physical properties of vulcanized rubber of rubber composition >>
The Σ value at 28 ° C. to 150 ° C. [Σ tan δ (28 to 150 ° C.)] of the 100% elastic modulus (M100) and the tangent loss tan δ was measured according to the method described in the specification.
<< Evaluation of reinforcement cord >>
As described above, the elastic modulus of the reinforcing cord is estimated by using the stress-elongation curve of the reinforcing cord as described above. The tangent of the stress-elongation curve at the time was drawn and calculated.
<< Evaluation of pneumatic tire >>
<Runflat durability>
Each test tire (passenger car radial tire with tire size 215 / 45ZR17) is assembled with rims at normal pressure, filled with 230 kPa of internal pressure, left in a room at 38 ° C. for 24 hours, then the valve core is removed to increase the internal pressure. The drum running test was performed under the conditions of a pressure of 4.17 kN (425 kg), a speed of 89 km / h, and an indoor temperature of 38 ° C. as atmospheric pressure. The travel distance until failure of each test tire was measured, and the travel distance of Comparative Example 1 was taken as 100, and the index was displayed by the following formula. The larger the index, the better the run flat durability.
Run-flat durability (index) = (travel distance of test tire / travel distance of tire of Comparative Example 1) × 100
<Riding comfort (evaluation of longitudinal spring during INF)>
Evaluation of the longitudinal spring constant of a tire In my opinion, the slope of the tangent of a certain load value in the load-deflection curve is defined as the longitudinal spring constant (kg / mm) for the load, and the longitudinal spring constant index is Comparative Example 1. This is expressed as a ratio when the vertical spring constant is 100. The larger the value, the better the ride comfort.

Production Example 1 Production of primary amine-modified polybutadiene (1) Polybutadiene In a nitrogen-substituted 5 L autoclave, 1.4 kg of cyclohexane, 250 g of 1,3-butadiene, 2,2-ditetrahydrofurylpropane (0.0285 mmol) cyclohexane under nitrogen. The solution was injected as a solution, and 2.85 mmol of n-butyllithium (BuLi) was added thereto, followed by polymerization in a 50 ° C. warm water bath equipped with a stirrer for 4.5 hours. The reaction conversion of 1,3-butadiene was almost 100%. The polymer solution was drawn into a methanol solution containing 1.3 g of 2,6-di-tert-butyl-p-cresol, and after the polymerization was stopped, the solvent was removed by steam stripping and dried with a roll at 110 ° C. Thus, polybutadiene was obtained. The resulting polybutadiene was measured for microstructure (vinyl bond amount), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn). As a result, the vinyl bond content was 14%, Mw was 150,000, and Mw / Mn was 1.1.
(2) Production of primary amine-modified polybutadiene The polymer solution obtained in (1) above is maintained at a temperature of 50 ° C. without deactivating the polymerization catalyst, and the primary amino group protected N, N-bis ( 1129 mg (3.364 mmol) of trimethylsilyl) aminopropylmethyldiethoxysilane was added and the modification reaction was carried out for 15 minutes. Finally, 2,6-di-tert-butyl-p-cresol was added to the polymer solution after the reaction. Next, the primary amino group, which was desolvated and protected by steam stripping, was removed, and the rubber was dried with a ripening roll adjusted to 110 ° C. to obtain primary amine-modified polybutadiene. The resulting modified polybutadiene was measured for microstructure (vinyl bond amount), weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), and primary amino group content. As a result, the vinyl bond content was 14%, Mw was 150,000, Mw / Mn was 1, 2, and the primary amino group content was 4.0 mmol / kg.

Production Example 2 DMBTESPA Modified Polybutadiene In Production Example 1, 1129 mg (3.364 mmol) of N, N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane was mixed with N- (1,3-dimethylbutylidene) -3- (triethoxysilyl). ) DMBTESPA-modified polybutadiene was obtained in the same manner as in Production Example 1, except that the amount was changed to 3.364 mmol.

Example 1
Eight types of rubber compositions having the compounding compositions A to H shown in Table 1 were prepared, and physical properties of vulcanized rubber, that is, M100 and Σtanδ (28 to 150 ° C.) were obtained. These results are shown in Table 1.
Next, the cord of the cellulosic fiber (rayon) is pulled with a DIP tension of 0.71 cN / dtex and subjected to DIP treatment (temperature: 149 ° C., time: 180 seconds), and 50 cN / dtex (180 ° C., 29.4 N). A reinforcing cord having rigidity represented by the above cord elastic modulus is created, and this reinforcing cord is applied to a carcass ply to form a tire. Here, fiber cord type: 1840 dtex / 3, 38 × 38, DIP solution of fiber cord is F / R molar ratio: 1.98, RF / L solid mass%: 16.0, (NaOH + NH ₄ OH) / R A molar ratio of 0.80 is used, and the number of lower twists is 30 (lower twisting factor: 0.45), and the number of upper twists is 38 (upper twisting factor: 0.57).
The eight rubber compositions of the above-mentioned blends A to H are arranged in the side reinforcing layer 8 and the bead filler 7 shown in FIG. 1, and driving the carcass ply into the tire: 35 tires / cm. Radial tires for passenger cars of 215 / 45ZR17 were produced according to a conventional method, and run-flat durability and riding comfort of these tires were evaluated. The results are shown in Table 2.

Examples 2-32, Comparative Examples 1 and 2
Radial tires for passenger cars were manufactured in the same manner as in Example 1 using the rubber compositions and the reinforcing cords shown in Tables 2 to 4. About the manufactured tire, run flat durability and riding comfort were evaluated. The results are shown in Tables 2-5.

［注］
１）天然ゴム：ＴＳＲ２０
２）未変性ポリブタジエン：ＪＳＲ社製ＢＲ０１
３）一級アミン変性ポリブタジエン：製造例１で得られたもの
４）カーボンブラック：ＦＥＦ（Ｎ５５０）、旭カーボン社製「旭＃６０」
５）プロセスオイル：アロマティックオイル、富士興産社製「アロマックス＃３」
６）老化防止剤６Ｃ：Ｎ−（１，３−ジメチルブチル）−Ｎ’−フェニル−ｐ−フェニレンジアミン、大内新興化学工業社製「ノクラック６Ｃ」
７）加硫促進剤ＤＺ：Ｎ，Ｎ’−ジシクロヘキシル−２−ベンゾチアジルスルフェンアミド、大内新興化学工業社製「ノクセラーＤＺ」
８）加硫促進剤ＴＯＴ：テトラキス（２−エチルへキシル）チウラムジスルフィド、大内新興化学工業社製「ノクセラーＴＯＴ−Ｎ」
９）ＤＭＢＴＥＳＰＡ変性ポリブタジエン：製造例２で得られたもの

[note]
1) Natural rubber: TSR20
2) Unmodified polybutadiene: BR01 manufactured by JSR
3) Primary amine-modified polybutadiene: obtained in Production Example 1 4) Carbon black: FEF (N550), “Asahi # 60” manufactured by Asahi Carbon Co., Ltd.
5) Process oil: Aromatic oil, “Aromax # 3” manufactured by Fuji Kosan Co., Ltd.
6) Anti-aging agent 6C: N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine, “NOCRACK 6C” manufactured by Ouchi Shinsei Chemical Co., Ltd.
7) Vulcanization accelerator DZ: N, N′-dicyclohexyl-2-benzothiazylsulfenamide, “Noxeller DZ” manufactured by Ouchi Shinsei Chemical Co., Ltd.
8) Vulcanization accelerator TOT: Tetrakis (2-ethylhexyl) thiuram disulfide, “Noxeller TOT-N” manufactured by Ouchi Shinsei Chemical Co., Ltd.
9) DMBTESPA modified polybutadiene: obtained in Production Example 2

  From the results of Tables 2 to 5, the pneumatic tire of the present invention using the rubber composition according to the present invention for the side reinforcing layer and the bead filler and using the cellulosic fiber for the reinforcing cord is comfortable to ride. It can be seen that the run-flat durability can be improved without impairing. Moreover, by contrast with Example 3 and Example 7, and other Examples, the direction from which a lower twist coefficient and an upper twist coefficient differ is excellent in any evaluation of run flat durability and riding comfort. It was shown that

  The pneumatic tire of the present invention has a vulcanized rubber property having a modulus of elasticity at 100% elongation of not less than a certain value, a tangent loss tan δ of 28 ° C. to 150 ° C. being a certain value or less, and carbon black. In particular, the rubber composition containing a large amount of the rubber composition is used for the side reinforcing layer and / or the bead filler, and by using a specific cellulosic fiber for the carcass layer, the running resistance and riding comfort during normal running are not impaired. Flat durability can be improved.

It is a mimetic diagram showing the section of one embodiment of the pneumatic tire of the present invention. It is explanatory drawing for calculating | requiring (SIGMA) tan (delta) (28-150 degreeC) in the vulcanized rubber physical property of a rubber composition. It is a graph which shows an example of the stress (load) -elongation curve of a reinforcement cord.

Explanation of symbols

1, 1 'bead core 2 carcass layer 3 side rubber layer 4 tread rubber layer 5 belt layer 6 inner liner 7 bead filler 8 side reinforcing layer 10 shoulder area

Claims (19)

  A pneumatic tire comprising a bead core, a carcass layer having one or more carcass plies in which a plurality of parallel reinforcing cords are embedded in a covering rubber, a tread rubber layer, an inner liner, a side reinforcing layer, and a bead filler, The reinforcing cord is made of cellulosic fiber, and has a rigidity represented by a cord elastic modulus of 50 cN / dtex or more (at a temperature of 180 ° C. and a stress applied with a force of 29.4 N per reinforcing cord), (A) The rubber component and 100 parts by mass of (B) containing 55 parts by mass or more of carbon black, and in the physical properties of vulcanized rubber, the elastic modulus at 100% elongation (M100) is 10 MPa or more and the tangent loss tan δ A pneumatic tire using a rubber composition having a Σ value of 6.0 or less at 28 ° C to 150 ° C.   2. The pneumatic tire according to claim 1, wherein in the rubber composition, (B) the carbon black is at least one selected from FEF grade, FF grade, HAF grade, ISAF grade and SAF grade.   (B) The pneumatic tire according to claim 2, wherein the carbon black is FEF grade grade.   The pneumatic tire according to any one of claims 1 to 3, wherein in the rubber composition, the rubber component (A) contains an amine-modified conjugated diene polymer.   The pneumatic tire according to claim 4, wherein the amine-modified conjugated diene polymer is a protic amine-modified conjugated diene polymer.   The pneumatic tire according to claim 4 or 5, wherein the amine-modified conjugated diene polymer is a primary amine-modified conjugated diene polymer.   The pneumatic tire according to claim 6, wherein the primary amine-modified conjugated diene polymer is obtained by reacting a protected primary amine compound with an active terminal of the conjugated diene polymer.   The conjugated diene polymer is obtained by anionic polymerization of a conjugated diene compound alone or a conjugated diene compound and an aromatic vinyl compound in an organic solvent using an organic alkali metal compound as an initiator. The described pneumatic tire.   The pneumatic tire according to claim 8, wherein the conjugated diene polymer is polybutadiene.   The pneumatic tire according to any one of claims 7 to 9, wherein the protected primary amine compound is N, N-bis (trimethylsilyl) aminopropyltriethoxysilane.   The pneumatic tire according to any one of claims 1 to 10, wherein an upper twist coefficient of the reinforcing cord is 0.3 to 0.7.   The pneumatic tire according to any one of claims 1 to 11, wherein a lower twist coefficient of the reinforcing cord is 0.3 to 0.7.   The pneumatic tire according to claim 12, wherein an upper twist coefficient and a lower twist coefficient are different.   The pneumatic tire according to claim 13, wherein an upper twist coefficient is larger than a lower twist coefficient.   The pneumatic tire according to any one of claims 1 to 14, wherein the cellulosic fibers are made of rayon or lyocell.   The pneumatic tire according to any one of claims 1 to 15, wherein the reinforcing cord is made of an organic fiber having a melting point of 300 ° C or higher.   The pneumatic tire according to claim 1, wherein the rubber composition is used for a side reinforcing layer.   The pneumatic tire according to claim 1, wherein the rubber composition is used for a bead filler.   The pneumatic tire according to claim 1, wherein the rubber composition is used for a side reinforcing layer and a bead filler.

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