JP2009062485A - Rubber composition and pneumatic tire obtained by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition which can sufficiently satisfy both steering stability and durability when it is applied to tread rubber of a tire without lowering plant operation efficiency; and to provide a pneumatic tire obtained by using the rubber composition. <P>SOLUTION: In the rubber composition, 10-200 pts.mass of a resin having ability to impart adhesiveness to the rubber composition is blended based on 100 pts.mass of a rubber component containing a polyrotaxane or a cross-linked polyrotaxane. The polyrotaxane has a cyclic molecule, a linear molecule included in the opening part of the cyclic molecule in a skewered state and blocking groups arranged at both terminals of the linear molecule so as to prevent detachment of the linear molecule from the cyclic molecule. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber composition and a pneumatic tire using the rubber composition in a tread rubber, and particularly, when applied to a tread of a tire without reducing factory workability, the steering stability and durability of the tire are improved. The present invention relates to a highly compatible rubber composition.

  In response to the evolution of advanced power performance of automobiles in recent years, more excellent handling stability, particularly handling stability on dry road surfaces, has been required as tire characteristics. In general, it is known that improvement in steering stability of a tire can be obtained by increasing a hysteresis loss at a room temperature or higher of a rubber composition used for a tread rubber of a tire.

  On the other hand, as a technique for increasing the hysteresis loss of the rubber composition, a technique of blending a petroleum resin is known (for example, Patent Document 1).

JP 05-009338 A

  However, if a large amount of the tackifier is blended in the rubber composition, the durability of the tire to which the rubber composition is applied may be lowered, or the factory workability may be deteriorated.

  On the other hand, in recent years, high durability has been required for tires from the viewpoint of safety. On the other hand, it is possible to improve the durability by blending natural rubber or carbon black in the rubber composition, but the tread rubber to which the rubber composition is applied is induced to be cured and stable. May decrease.

  Accordingly, an object of the present invention is to provide a rubber composition capable of achieving both high steering stability and durability when applied to a tire without deteriorating factory workability, and a pneumatic tire to which the rubber composition is applied. It is to provide.

  As a result of extensive studies to solve the above problems, the present inventors have formulated a rubber composition by blending a polyrotaxane, which is a cyclic polymer-introduced polymer, and a resin, which is a tackifier, into the rubber composition. It has been found that the steering stability and durability of a tire to which the rubber composition is applied can be highly compatible without deteriorating factory workability.

  That is, the rubber composition of the present invention is characterized in that 10 to 200 parts by mass of a resin having tackiness to the rubber composition is blended with 100 parts by mass of a rubber component containing a polyrotaxane or a crosslinked polyrotaxane. To do.

  In a preferred example of the rubber composition of the present invention, the polyrotaxane is a cyclic molecule, a linear molecule clasped into the opening of the cyclic molecule, and both ends of the linear molecule. And a blocking group that prevents the elimination of the cyclic molecule.

  In another preferred embodiment of the rubber composition of the present invention, the crosslinked polyrotaxane comprises a cyclic molecule, a linear molecule clasped into the opening of the cyclic molecule, and a linear molecule. It has at least two polyrotaxanes having a blocking group which is arranged at both ends and prevents the elimination of the cyclic molecule, and the cyclic molecules of the at least two polyrotaxanes are bonded to each other through a chemical bond. And

  In another preferred embodiment of the rubber composition of the present invention, when the cyclic molecule is included in a skewered manner by the linear molecule, the maximum inclusion amount of the cyclic molecule is set as the maximum inclusion amount. When the value is 1, the maximum inclusion amount of the cyclic molecule is 0.001 to 0.6.

  In another preferred embodiment of the rubber composition of the present invention, the cyclic molecule is selected from the group consisting of cyclodextrins, crown ethers, benzocrowns, dibenzocrowns and dicyclohexanocrowns. And Here, the cyclic molecule is preferably a cyclodextrin, and more preferably α-cyclodextrin.

  In another preferred embodiment of the rubber composition of the present invention, the linear molecule is polycaprolactone, natural rubber, styrene-butadiene copolymer, isobutylene-isoprene copolymer, polyisoprene, polyisobutylene, polybutadiene, polyethylene. It is selected from the group consisting of glycol, polypropylene glycol, polytetrahydrofuran, polydimethylsiloxane, polyethylene and polypropylene.

  In another preferred embodiment of the rubber composition of the present invention, the molecular weight of the linear molecule is 1,000 to 1,000,000.

  In another preferred embodiment of the rubber composition of the present invention, the blocking group is selected from the group consisting of dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, and pyrenes. It is characterized by.

  In another preferable example of the rubber composition of the present invention, the cyclic molecules of the at least two polyrotaxanes are bonded to each other through a chemical bond with a crosslinking agent.

  In another preferred embodiment of the rubber composition of the present invention, the molecular weight of the crosslinking agent is less than 2,000.

  In another preferred embodiment of the rubber composition of the present invention, the crosslinking agent is cyanuric chloride, trimesoyl chloride, terephthaloyl chloride, epichlorohydrin, dibromobenzene, glutaraldehyde, phenylene diisocyanate, trilein diisocyanate, It is selected from the group consisting of divinyl sulfone, 1,1′-carbonyldiimidazole, and alkoxysilanes.

  In another preferred embodiment of the rubber composition of the present invention, the content of the polyrotaxane or the crosslinked polyrotaxane in the rubber component is 0.1 to 20 parts by mass.

  In another preferred embodiment of the rubber composition of the present invention, the amount of the resin is 20 to 100 parts by mass with respect to 100 parts by mass of the rubber component.

  In another preferred embodiment of the rubber composition of the present invention, the softening point of the resin is 80 ° C to 200 ° C. Here, the softening point is preferably 120 ° C to 160 ° C.

  In another preferred embodiment of the rubber composition of the present invention, the resin has an OH value (KOHmg / g) of 20 to 210. Here, the OH value is preferably 50 to 130.

  In another preferred embodiment of the rubber composition of the present invention, the acid value (KOHmg / g) of the resin is 1 to 20. Here, the acid value is preferably 2 to 10.

  In another preferred embodiment of the rubber composition of the present invention, the rubber component contains a styrene-butadiene copolymer rubber.

  The pneumatic tire of the present invention is characterized in that the rubber composition is used for a tread rubber.

  According to the present invention, by combining a specific polyrotaxane or a crosslinked polyrotaxane and a resin having a tackifying property to a rubber composition, both the steering stability and durability of the tire are highly compatible without reducing factory workability. The rubber composition which can be made to provide can be provided. Moreover, the pneumatic tire which used this rubber composition for the tread rubber of a tire and made the steering stability and durability highly compatible can be provided.

  The present invention is described in detail below. The rubber composition of the present invention is obtained by blending 10 to 200 parts by mass of a resin having tackiness to the rubber composition with respect to 100 parts by mass of a rubber component containing a polyrotaxane or a crosslinked polyrotaxane. By blending the above resin in addition to the polyrotaxane or the crosslinked polyrotaxane with the rubber composition of the present invention, the handling stability is improved and the durability and flexibility are secured at the same time without deteriorating the factory workability. be able to.

  In the present invention, the polyrotaxane is composed of both ends of the pseudopolyrotaxane (both linear molecules) in which the opening of a cyclic molecule (rotator) is included in a skewered manner by a linear molecule (axis). At the end, a blocking group is arranged so that the cyclic molecule is not released.

  In the present invention, the crosslinked polyrotaxane has at least two molecules of the polyrotaxane, and the cyclic molecules are bonded or crosslinked by chemical bonds. In such a crosslinked polyrotaxane, there is no direct crosslinking point of a linear molecular ring, and a cyclic molecule penetrating through the linear molecule can move along the linear molecule (the pulley effect) Therefore, when the stress is applied to the cross-linked polyrotaxane, the internal stress in the cross-linked polyrotaxane is dispersed by the pulley effect, so that a high breaking strength can be brought about. By blending such a crosslinked polyrotaxane into the rubber composition, flexibility can be ensured while improving durability. Even when the uncrosslinked polyrotaxane is blended with the rubber composition, physical crosslinking between the cyclic molecules occurs when the temperature rises, so that the same effect as when the crosslinked polyrotaxane is blended can be obtained. it can.

In the present invention, an effect can be obtained by blending either the above polyrotaxane or the above crosslinked polyrotaxane into the rubber composition, but a crosslinked polyrotaxane is preferred because the effect of improving steering stability and durability can be further obtained. Also,
When the amount is 0.1 parts by mass or less, the effect is small, and when the amount is 20 parts by mass or more, the content of the polyrotaxane or the crosslinked polyrotaxane in the rubber component is 0 from the viewpoint of excessive crosslinking and reduced elongation at break. It is preferable that it is 1-20 mass parts, and 1-15 mass parts is more preferable.

  The linear molecule in the polyrotaxane and the crosslinked polyrotaxane is not particularly limited as long as it is a molecule or substance that is included in a cyclic molecule and can be integrated non-covalently and is linear. . In the present invention, the “linear molecule” refers to a molecule including a polymer and all other substances satisfying the above requirements. In the present invention, “linear” of “linear molecule” means substantially “linear”. That is, the linear molecule may have a branched chain as long as the cyclic molecule as a rotor is rotatable or the cyclic molecule is slidable or movable on the linear molecule. Further, the length of the “straight chain” is not particularly limited as long as the cyclic molecule can slide or move on the linear molecule.

  As the linear molecule, any of a hydrophilic polymer and a hydrophobic polymer can be used. Examples of the hydrophilic polymer include polyethers such as polyvinyl alcohol, polyvinyl pyrrolidone, poly (meth) acrylic acid, cellulose resin (carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, etc.), polyacrylamide, polyethylene oxide, polyethylene glycol, and polypropylene glycol. , Polyvinyl acetal resin, polyvinyl methyl ether, polyamine, polyethyleneimine, casein, gelatin, starch and the like, and copolymers thereof. Examples of hydrophobic polymers include polyolefin resins such as polyethylene, polypropylene and copolymer resins with other olefinic monomers, polyester resins such as polycaprolactone, polyvinyl chloride resins, polystyrene and acrylonitrile-styrene copolymer resins, etc. Polystyrene resins, polymethyl methacrylate, (meth) acrylic acid ester copolymers, acrylic resins such as acrylonitrile-methyl acrylate copolymer resins, polycarbonate resins, polyurethane resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl butyral resins Etc., and derivatives or modified products thereof. Besides these, as a linear molecule, natural rubber, styrene-butadiene copolymer, isobutylene-isoprene copolymer, polyisoprene, polyisobutylene, polybutadiene rubber polymer, polytetrahydrofuran, polydimethylsiloxane, etc. , Polyamides, and linear molecules having a benzene ring. Among these, polycaprolactone, natural rubber, styrene-butadiene copolymer, isobutylene-isoprene copolymer, polyisoprene, polyisobutylene, polybutadiene, polyethylene glycol, polypropylene glycol, polytetrahydrofuran, polydimethylsiloxane, polyethylene and polypropylene are preferable. . From the viewpoint of compatibility with rubber components other than polyrotaxane or crosslinked polyrotaxane, polycaprolactone is particularly preferable.

  The linear molecule has a molecular weight of 1,000 or more, for example, 1,000 to 1,000,000, from the viewpoint of easy inclusion in a cyclic molecule, workability at the time of rubber compounding, and productivity. Preferably 5,000 or more, such as 5,000 to 1,000,000 or 5,000 to 500,000, more preferably 10,000 or more, such as 10,000 to 1,000,000, 10,000 to 500. , Or 10,000 to 300,000. When the linear molecule is polycaprolactone, for the same reason as described above, the molecular weight is desirably 5,000 to 100,000, preferably 10,000 to 50,000, and preferably 10,000 to 10,000. 20,000 is more preferable.

  The linear molecule preferably has a reactive group at both ends. By having this reactive group, it can react easily with a blocking group. The reactive group depends on the blocking group to be used, and examples thereof include a hydroxyl group, an amino group, a carboxyl group, and a thiol group.

  The cyclic molecule in the polyrotaxane and the crosslinked polyrotaxane can be any cyclic molecule as long as it is a cyclic molecule that can be included in the linear molecule. In the present invention, “cyclic molecule” refers to various cyclic substances including cyclic molecules. In the present invention, “cyclic molecule” refers to a molecule or substance that is substantially cyclic. That is, “substantially ring-shaped” means that the letter “C” is not completely closed, such as the letter “C”, and one end and the other end of the letter “C” are not joined. It is intended to include those having overlapping spiral structures. Furthermore, a ring for a “bicyclo molecule” to be described later can be defined in the same manner as “substantially cyclic” in “cyclic molecule”. That is, one or both rings of the “bicyclo molecule” may not be completely closed like the letter “C”, and one end and the other end of the letter “C” are connected to each other. It may have a spiral structure that is not overlapped.

  Examples of the cyclic molecule include various cyclodextrins (for example, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, dimethylcyclodextrin and glucosylcyclodextrin, derivatives or modified products thereof), crown ethers, benzo Examples include crowns, dibenzocrowns, and dicyclohexanocrowns, and derivatives or modified products thereof.

  The above-mentioned cyclic molecules such as cyclodextrin can be used alone or in combination of two or more. As such a cyclic molecule, α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are particularly preferable, and α-cyclodextrin is preferable from the viewpoint of inclusion.

  The above-mentioned cyclodextrins and crown ethers differ in the size of the opening of the cyclic molecule depending on the type. Therefore, the type of linear molecule to be used, specifically, when the linear molecule to be used is assumed to be cylindrical, the cyclic molecule to be used depends on the diameter of the cross section of the cylinder, the hydrophobicity or hydrophilicity of the linear molecule, etc. Can be selected. When a cyclic molecule having a relatively large opening and a cylindrical linear molecule having a relatively small diameter are used, two or more linear molecules can be included in the opening of the cyclic molecule. .

  The cyclic molecule preferably has a reactive group outside the ring. When the cyclic molecules are bonded or cross-linked, the reaction can be easily performed using this reactive group. The reactive group depends on the crosslinking agent used, and examples thereof include a hydroxyl group, an amino group, a carboxyl group, a thiol group, and an aldehyde group. Moreover, it is good to use the group which does not react with a blocking group in the case of forming the blocking group mentioned later (blocking reaction).

  As the blocking group in the polyrotaxane and the crosslinked polyrotaxane, any group may be used as long as the cyclic molecule maintains a form skewered by a linear molecule. Examples of such a group include a group having “bulkiness” and / or a group having “ionicity”. Here, the “group” means various groups including a molecular group and a polymer group. That is, examples of the group having “bulkyness” include a spherical group and a side wall-shaped group. In addition, when the “ionicity” of the group having “ionicity” and the “ionicity” of the cyclic molecule interact with each other, for example, repel each other, the cyclic molecule is skewered by a linear molecule. It is possible to retain the shape that has been formed.

  The blocking group may be a polymer main chain or a side chain as long as it retains a skewered form as described above. When the blocking group is the polymer A, even if the polymer A is used as a matrix and the polyrotaxane or the crosslinked polyrotaxane is included in a part thereof, the matrix includes the polyrotaxane or the crosslinked polyrotaxane. The form in which the polymer A is contained in the part may be used. Thus, by combining with the polymer A having various properties, a composite material having a combination of the properties of the polyrotaxane or the crosslinked polyrotaxane and the properties of the polymer A can be formed.

  Specifically, as blocking groups for molecular groups, dinitrophenyl groups such as 2,4-dinitrophenyl group and 3,5-dinitrophenyl group, cyclodextrins, adamantane groups, trityl groups, fluoresceins and pyrene And derivatives or modified products thereof.

  The crosslinked polyrotaxane can be obtained by having at least two molecules of the polyrotaxane and bonding or crosslinking the cyclic molecules. The at least two molecules of polyrotaxane used for crosslinking may be the same or different. At this time, the cyclic molecules used for crosslinking in at least two polyrotaxanes may be the same or different.

  The cyclic molecule used for cross-linking is preferably cross-linked through a chemical bond. At this time, the chemical bond may be a simple bond or a bond via various atoms or molecules.

  As described above, the cyclic molecule preferably has a reactive group outside the ring. In particular, it is preferable to form a polyrotaxane having a blocking group and then to crosslink the cyclic molecules with a crosslinking agent. Under the present circumstances, the conditions of a crosslinking reaction must be the conditions which do not remove the blocking group of the polyrotaxane which formed the blocking group.

  Moreover, different types of cyclic molecules can be bonded or crosslinked. The cyclic molecules used for crosslinking can have reactive groups that can react with each other to form a bond.

  A conventionally known crosslinking agent can be used as the crosslinking agent used for the crosslinking reaction between the cyclic molecules. For example, cyanuric chloride, trimesoyl chloride, terephthaloyl chloride, epichlorohydrin, dibromobenzene, glutaraldehyde, phenylene diisocyanate, diisocyanate trilein (eg 2,4-diisocyanate trilein), 1,1'-carbonyldi Examples thereof include imidazole and divinyl sulfone. Moreover, various coupling agents, such as a silane coupling agent (for example, various alkoxysilanes) and a titanium coupling agent (for example, various alkoxytitanium), can be mentioned. Furthermore, various photocrosslinking agents used for soft contact lens materials, for example, stilbazolium salt photocrosslinkers such as formylstyrylpyridinium (K. Ichimura et al., Journal of polymer science. Polymer chemistry edition 20, 1411- 1432 (1982)), as well as other photocrosslinking agents, such as photocrosslinking agents by photoduplexing, specifically cinnamic acid, anthracene, thymines and the like.

  The cross-linking agent preferably has a molecular weight of less than 2,000, preferably less than 1,000, more preferably less than 600, and most preferably less than 400.

  When α-cyclodextrin is used as a cyclic molecule and crosslinking is performed using a crosslinking agent, examples of the crosslinking agent include cyanuric chloride, 2,4-diisocyanate trilein, 1,1′-carbonyldiimidazole, and trimesoyl chloride. , Terephthaloyl chloride, and alkoxysilanes such as tetramethoxysilane and tetraethoxysilane. In particular, it is preferable to use α-cyclodextrin as the cyclic molecule and cyanuric chloride as the crosslinking agent.

  The polyrotaxane and the crosslinked polyrotaxane can be prepared as follows. First, a pseudo-polyrotaxane is prepared by mixing a cyclic molecule and a linear molecule, and enclosing the linear molecule in a skewered manner in the opening of the cyclic molecule. Various solvents may be used in the mixing in this preparation step. Examples of the solvent include a solvent that dissolves the cyclic molecule and / or the linear molecule, or a solvent that suspends the cyclic molecule and / or the linear molecule. Specifically, it can be appropriately selected depending on the cyclic molecule and / or linear molecule used in the preparation of the pseudopolyrotaxane.

  During the preparation of the pseudopolyrotaxane, it is preferable to control the amount of cyclic molecules that are skewered on the linear molecules. At least two cyclic molecules are preferably included in a skewered manner on a linear molecule. In addition, when the amount that the cyclic molecule can exist to the maximum on the linear molecule, that is, when the maximum inclusion amount is 1, the amount of the cyclic molecule is 0.001 to 0.6 of the maximum inclusion amount. , Preferably 0.01 to 0.5, more preferably 0.05 to 0.4. If it is less than 0.001, the pulley effect may not be exhibited, and if it exceeds 0.6, the cyclic molecules may be arranged too densely and the mobility of the cyclic molecules may be lowered.

  The amount of the above-described cyclic molecule can be controlled by mixing time, temperature, pressure, and the molecular weight of the linear molecule to be used is made high molecular weight. More specifically, it is possible to dissolve excess linear molecules in a saturated solution of cyclic molecules.

  Next, a polyrotaxane is prepared by blocking both ends of the linear molecule with a blocking group so that the cyclic molecule is not detached from the skewered state from the obtained pseudopolyrotaxane. The cross-linked polyrotaxane is obtained by bonding two or more polyrotaxanes by bonding the obtained polyrotaxane cyclic molecules to each other through a chemical bond using, for example, the above-described cross-linking agent. The cross-linking reaction may be performed in parallel with the vulcanization reaction by applying a cross-linking agent to the rubber composition containing the polyrotaxane and vulcanizing.

  In addition to the above method, the crosslinked polyrotaxane or crosslinked polyrotaxane of the present invention can be obtained by the following method using a crosslinked cyclic molecule, that is, a “bicyclo molecule”. That is, a bicyclo molecule is first prepared. The bicyclo molecule has a first substantial ring and a second substantial ring as described above. Next, the bicyclo molecule, the first linear molecule, and the second linear molecule are mixed, and the first linear molecule is included in a skewered manner in the opening of the first ring of the bicyclo molecule. Thus, a crosslinked polyrotaxane is prepared in which a second linear molecule is skewered in the opening of the second ring and is crosslinked by the bicyclo molecule. Next, the bicyclic molecule is subjected to a step of blocking both ends of the linear molecule with blocking groups so that the bicyclo molecule is not detached from the skewered state.

  The bicyclo molecule is “bicyclo”, but may have one or more rings in addition to the first substantial ring and the second substantial ring. In addition, a molecule having a structure in which two English letters “C” are combined may be used as the bicyclo molecule. In this case, after inclusion of the linear molecule in a skewered form or after blocking with a blocking group, the “C” -shaped one can be closed. In addition, regarding a molecule having a structure in which two letters “C” are combined, and ring closure of the molecule, M. Asakawa et al., ANGEWANTE CHEMIE-INTERNATIONAL EDITION 37 (3), 333-337 (1998), and M. See Asakawa et al., EUROPEAN JOURNAL OF ORGANIC CHEMISTRY 5, 985-994 (1999).

  In the rubber composition of the present invention, the rubber components other than the polyrotaxane and the crosslinked polyrotaxane include natural rubber (NR), styrene-butadiene copolymer (SBR), polybutadiene rubber (BR), and polyisoprene rubber (IR). , Isobutene-isoprene copolymer (IIR), ethylene-propylene copolymer and the like can be used, and among these, styrene-butadiene copolymer is preferable. These rubber components may be used alone or as a blend of two or more.

  In the rubber composition of the present invention, it is necessary to blend 10 to 200 parts by mass of the resin having tackiness to the rubber composition with respect to 100 parts by weight of the rubber component. If the amount of the resin is less than 10 parts by mass, the desired effect of the present invention cannot be obtained. On the other hand, if it exceeds 200 parts by mass, the factory workability may be reduced. From this viewpoint, the amount of the tackifier resin is preferably 20 to 100 parts by mass.

  The resin having tackiness to the rubber composition is generally a thermoplastic resin having a molecular weight of several hundred to several thousand, and refers to a resin that imparts tackiness by blending with natural rubber or synthetic rubber. Natural and synthetic resins can be used. Specifically, natural resins include coumarone-indene resin, coumarone resin, naphthene resin, phenol resin, rosin mixture, terpene resin, terpene-phenol resin, rosin, rosin ester, hydrogenated rosin derivative, hydrogen Addition terpene resin etc. are mentioned. Synthetic resins include alkylphenol-formaldehyde resins, C5 petroleum resins, C9 petroleum resins, aliphatic petroleum resins, xylene-formaldehyde resins, phenol-modified C9 petroleum resins, carboxylic acid-modified C9 petroleum resins, dicyclo Examples include pentadiene-modified C9 petroleum resin.

  Further, from the viewpoint of further improving steering stability, the softening point of the resin (measurement method: ASTM E28-58-T) is preferably 80 to 160 ° C, and more preferably 120 to 150 ° C.

  Moreover, 20-210 are preferable and, as for the OH value (KOHmg / g, measuring method: JIS K0070) of the said tackifying resin, from the viewpoint of further improving steering stability and factory workability, 50-130 are more preferable.

  In addition, from the viewpoint of further improving handling stability and factory workability, the acid value (KOHmg / g, measurement method: JIS K0070) of the tackifying resin is preferably 1 to 20, and more preferably 2 to 10.

In the rubber composition of the present invention, a filler used in a general rubber composition can be blended. Although it does not specifically limit as this filler, Carbon black and an inorganic filler can be mentioned, These fillers may be used individually by 1 type, and may mix and use 2 or more types. Good. Further, the inorganic filler used preferably has a particle size of 10 μm or less, and more preferably 3 μm or less. By using an inorganic filler having a particle size of 10 μm or less, the fracture characteristics and wear resistance of the vulcanized rubber can be maintained well. Here, as the inorganic filler, silica and the following general formula (I):
mM · xSiO _y · zH ₂ O (I)
[Wherein, M is a metal selected from the group consisting of aluminum, magnesium, titanium, calcium and zirconium, an oxide or hydroxide of these metals, and a hydrate thereof, or a carbonate of these metals. And m, x, y, and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10]. The inorganic compound may contain a metal such as potassium, sodium, iron or magnesium, an element such as fluorine, or a group such as NH ₄ —.

Specific examples of the inorganic compound of the above formula (I) include aluminum hydroxide [Al (OH) ₃ ], aluminum carbonate such as alumina monohydrate (Al ₂ O ₃ .H ₂ O), gibbsite, bayerite, and the like. [Al ₂ (CO ₃ ) ₃ ], magnesium hydroxide [Mg (OH) ₂ ], magnesium oxide (MgO), magnesium carbonate (MgCO ₃ ), talc (3MgO · 4SiO ₂ · H ₂ O), attapulgite (5MgO · 8SiO ₂ .9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [Ca (OH) ₂ ], aluminum magnesium oxide (MgO · Al ₂ O) _3), clay _{(Al 2 O 3 · 2SiO 2} ), kaolin _{(Al 2 O 3 · 2SiO 2} · 2H 2 O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite ( _{l 2 O 3 · 4SiO 2 ·} 2H 2 O), aluminum silicate _{(Al 2 SiO 5, Al 4} · 3SiO 4 · 5H 2 O etc.), magnesium silicate (Mg ₂ SiO _4, MgSiO ₃ etc.), silicic acid Calcium (Ca ₂ SiO ₄ etc.), aluminum calcium silicate (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), water Examples include zirconium oxide [ZrO (OH) ₂ .nH ₂ O], zirconium carbonate [Zr (CO ₃ ) ₂ ], various zeolites, feldspar, mica, montmorillonite, and M in formula (I) is aluminum. Is preferred.

As the filler used in the rubber composition of the present invention, among the above fillers, carbon black, silica, aluminas and clays are preferable. Here, aluminas, among the inorganic compounds represented by the above general formula (I), the following general formula (II):
Al ₂ O ₃ · nH ₂ O (II)
[Wherein n is 0 to 3].

  The carbon black is not particularly limited, and examples thereof include FEF, SRF, HAF, ISAF, and SAF grades. The carbon black is preferably carbon black having an iodine adsorption amount (IA) of 60 mg / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or more. By blending carbon black, various physical properties of the rubber composition can be improved, but those of HAF, ISAF, and SAF grades are more preferable from the viewpoint of improving the wear resistance. Note that the rubber composition of the present invention may contain only carbon black as a filler. In this case, the amount of carbon black is in the range of 10 to 250 parts by mass with respect to 100 parts by mass of the rubber component. Yes, from the viewpoint of reinforcing properties and efficiency of improving various physical properties thereby, a range of 20 to 150 parts by mass is preferable. When the blending amount of carbon black is less than 10 parts by mass with respect to 100 parts by mass of the rubber component, the fracture characteristics and the like are not sufficient, and when it exceeds 250 parts by mass, the processability of the rubber composition is lowered.

  Further, the silica is not particularly limited, and examples thereof include wet silica (hydrous silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, and the like. Wet silica is preferred in that it has excellent effects and wet grip properties and low rolling resistance. In addition, in the rubber composition of the present invention, only silica as a filler may be blended. In this case, the blending amount of silica is in the range of 10 to 250 parts by mass with respect to 100 parts by mass of the rubber component, The range of 20-150 mass parts is preferable from a viewpoint of reinforcement property and the improvement efficiency of various physical properties by it. If the compounding amount of silica is less than 10 parts by mass, the fracture characteristics and the like are not sufficient, and if it exceeds 250 parts by mass, the processability of the rubber composition decreases.

  In the rubber composition of the present invention, when silica is used as a filler, it is preferable to add a silane coupling agent at the time of blending from the viewpoint of further improving the reinforcing property. Examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, and bis (2-triethoxysilyl). Ethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltri Methoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoy Tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate mono Sulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis (3-diethoxymethylsilylpropyl) tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethyl Silylpropylbenzothiazole tetrasulfide and the like. Among these, from the viewpoint of improving the reinforcing property, bis (3-trie Toxisilylpropyl) tetrasulfide and 3-trimethoxysilylpropylbenzothiazole tetrasulfide are preferred. These silane coupling agents may be used alone or in combination of two or more.

  Moreover, the rubber composition of this invention can use the general crosslinking system for rubber | gum, and it is preferable to use combining the crosslinking agent for rubber | gum, and a vulcanization accelerator. Here, sulfur etc. are mentioned as a crosslinking agent for rubber | gum, The usage-amount of the crosslinking agent for rubber | gum has the preferable range of 0.1-10 mass parts as a sulfur content with respect to 100 mass parts of rubber components, The range of 5 parts by mass is more preferable. When the compounding amount of the rubber crosslinking agent is less than 0.1 parts by mass with respect to 100 parts by mass of the rubber component, the fracture strength, wear resistance and low heat build-up of the vulcanized rubber are reduced and exceed 10 parts by mass. And rubber elasticity is lost.

  On the other hand, the vulcanization accelerator is not particularly limited, but 2-mercaptobenzothiazole (M), dibenzothiazyl disulfide (DM), N-cyclohexyl-2-benzothiazylsulfenamide (CZ). ), Thiazole vulcanization accelerators such as Nt-butyl-2-benzothiazolylsulfenamide (NS), and guanidine vulcanization accelerators such as diphenylguanidine (DPG). The amount of the vulcanization accelerator used is preferably in the range of 0.1 to 5 parts by mass and more preferably in the range of 0.2 to 3 parts by mass with respect to 100 parts by mass of the rubber component. These vulcanization accelerators may be used alone or in combination of two or more.

  In the rubber composition of the present invention, process oil or the like can be used as a softening agent, and examples of the process oil include paraffinic oil, naphthenic oil, and aromatic oil. Among these, aromatic oils are preferable from the viewpoint of tensile strength and wear resistance, and naphthenic oils and paraffinic oils are preferable from the viewpoint of hysteresis loss and low-temperature characteristics. The amount of these process oils used is preferably in the range of 0 to 100 parts by mass with respect to 100 parts by mass of the rubber component. If the amount of process oil used exceeds 100 parts by mass with respect to 100 parts by mass of the rubber component, the tensile strength and low heat build-up of the vulcanized rubber tend to deteriorate.

  In addition to the polyrotaxane or the crosslinked polyrotaxane, the resin, the filler, the silane coupling agent, the rubber crosslinking agent, the vulcanization accelerator, and the softening agent, the rubber composition of the present invention includes, for example, an antioxidant, zinc oxide Additives commonly used in the rubber industry, such as stearic acid, antioxidants, and ozone degradation inhibitors, can be appropriately selected and blended within a range that does not impair the object of the present invention.

  The rubber composition of the present invention is obtained by kneading using a kneader such as a roll or an internal mixer, and after molding, vulcanization is performed, and the tire tread rubber, under tread, carcass, sidewall In addition to tire applications such as beads, it can also be used in anti-vibration rubber, belts, hoses, and other industrial products, but is particularly suitable as a tread rubber for tires.

  The pneumatic tire of the present invention is characterized by using the rubber composition as a tread rubber. The tire has a high hysteresis loss (tan δ) and is excellent in handling stability and durability because the above-described rubber composition excellent in durability is applied to the tread rubber. The tire of the present invention is not particularly limited except that the above rubber composition is used for the tread rubber, and can be produced according to a conventional method. Moreover, as gas with which this tire is filled, inert gas, such as nitrogen, argon, helium other than normal or the air which adjusted oxygen partial pressure, can be used.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Method for producing cyclic polymer-introduced polymer (polyrotaxane))
(1) Preparation of PCL-carboxylic acid by TEMPO oxidation of PCL 10 g of PCL (polycaprolactone) with a molecular weight of 5,000, 100 mg of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy radical), odor 1 g of sodium chloride was dissolved in 100 ml of acetone. 5 ml of a commercially available sodium hypochlorite aqueous solution (effective chlorine concentration 5%) was added and stirred at room temperature for 10 minutes. In order to decompose the remaining sodium hypochlorite, ethanol was added in a range up to 5 ml to complete the reaction. Subsequently, the solution was distilled off with an evaporator, dissolved in 250 ml of warm ethanol, and then allowed to stand overnight in a freezer (about −4 ° C.) to precipitate only PCL-carboxylic acid, and recovered and dried.

(2) Preparation of inclusion complex using PCL-carboxylic acid and α-CD 0.2 g of PCL-carboxylic acid prepared as described above was dissolved in 50 ml of acetone, while 7.25 g of α-CD (cyclo Dextrin) was dissolved in 50 ml of water. After both were heated to 70 ° C., the PCL solution was added to the CD aqueous solution little by little and sonicated at 70 ° C. for 17 minutes. Next, the precipitate obtained by allowing to stand for 10 hours was collected and dried.

(3) Reduction of α-CD and blockage of inclusion complex using adamantamine and BOP reagent reaction system At room temperature, 10 ml of DMF (dimethylformamide) was added to BOP (benzotriazol-1-yl-oxy-tris- (dimethylamino). ) Phosphonium hexafluorophosphate) Reagent 3 g, HOBt (1-hydroxybenzotriazole) 1 g, adamantaneamine 1.4 g, and diisopropylethylamine 1.25 ml were dissolved in this order.
The obtained solution was added to 14 g of the inclusion complex obtained in (2) dispersed in 20 ml of a DMF / DMSO mixed solvent (75/25), and quickly and sufficiently shaken. The slurry sample was allowed to stand overnight in a refrigerator, and then 50 ml of a mixed solution of DMF / methanol = 1: 1 was added and mixed well, followed by centrifugation to discard the supernatant. This washing with the DMF / methanol mixed solution was repeated twice, and further washing with 100 ml of methanol was repeated twice by the same centrifugation. The obtained precipitate was vacuum-dried and then dissolved in 50 ml of DMSO, and the obtained transparent solution was dropped into 700 ml of water to precipitate polyrotaxane. The precipitated polyrotaxane was collected by centrifugation and vacuum-dried or freeze-dried. A cycle of dissolution in DMSO, precipitation in water, collection, and drying was repeated twice to finally obtain a purified polyrotaxane.

The obtained purified polyrotaxane was identified by ¹ H-NMR and GPC (gel permeation chromatography), and confirmed to be the desired polyrotaxane. The inclusion amount of α-CD was 0.06.

(Method for producing crosslinked polyrotaxane)
To a DMF solution of 10 g of the polyrotaxane obtained as described above, a solution of 3.5 g of cyanuric chloride in 250 ml of DMF is added, and 50 ml of a 1N aqueous sodium hydroxide solution is further added, and reacted at room temperature for 3 hours to obtain a crosslinked polyrotaxane gel. It was. Thereafter, toluene was blown off with a draft, followed by vacuum drying at 50 ° C. for 4 hours to obtain a crosslinked polyrotaxane gel.

  Next, using the PCL-carboxylic acid, polyrotaxane, and cross-linked polyrotaxane, a rubber composition having a formulation shown in Table 1 was prepared by kneading using a Banbury mixer. Next, a passenger car tire (size: 225 / 40R18) in which the obtained rubber composition was applied to a tread rubber was prototyped. In Example 5, an unvulcanized tire was prepared by applying a rubber composition obtained by blending polyrotaxane according to the blending formulation shown in Table 1 to a tread rubber, and then a DMF solution of cyanuric chloride (14 g / L). Was applied to the tread rubber of the unvulcanized tire, and then vulcanized to carry out a crosslinking reaction and a vulcanization reaction at the same time to obtain a prototype tire. The rubber composition used for the tread of each prototype tire was evaluated for steering stability and durability as follows. The results are shown in Table 1.

(1) Steering stability A prototype tire was mounted on a high-performance vehicle capable of traveling at a maximum speed of 300 kmh and traveled on a circuit, and the test driver's feeling was evaluated according to the following criteria. The evaluation results were evaluated relative to the following criteria, with the result of Comparative Example 1 being “0”. The larger the value, the better the steering stability.
+3: To the extent that a general driver with low driving frequency can clearly recognize the difference +2: To the extent that a general driver with high driving frequency can recognize the difference +1: To the extent that a professional driver can recognize the difference 0 ...・ Control-1: To the extent that a professional driver can recognize the difference-2 ... To the extent that a general driver with high driving frequency can recognize the difference-3 ... With a general driver with low driving frequency clearly seeing the difference As much as possible

(2) Durability A tensile test was performed according to JIS K6251-1993, and the tensile strength (Tb) of the vulcanized rubber composition was measured at room temperature. The result was expressed as an index with Comparative Example 1 as 100. It shows that it is so favorable that a numerical value is large.

(3) Factory workability According to the formulation shown in Table 1, when adjusting the rubber compositions of Examples 1 to 5 and Comparative Examples 1 to 5, the adhesion (adhesion) between the kneaded rubber and the roll was measured. . The results were expressed as an index with Comparative Example 1 being 100, and the factory workability was evaluated.

* 1 JSR Co., Ltd., SBR 1500 Bonded styrene content = 23.5 mass%, Vinyl bond content = 18%, Polystyrene equivalent weight average molecular weight = 450,000.
* 2 PCL-carboxylic acid produced by the above method.
* 3 Polyrotaxane produced by the above method.
* 4 Cross-linked polyrotaxane produced by the above method.
* 5 Toast Carbon Co., Ltd., Seast 9H (Nitrogen adsorption specific surface area (N ₂ SA) = 142 m ² / g, Dibutyl phthalate oil absorption = 130 ml / 100 g)
* 6 Made by Nippon Oil Corporation, Neopolymer 140, softening point = 145 ° C.
* 7 Fujikosan Co., Ltd., FUKKOL AROMAX # 3.
* 8 Microcrystalline wax manufactured by Seiko Chemical Co., Ltd.
* 9 N- (1,3-Dimethylbutyl) -N'-phenyl-p-phenylenediamine, manufactured by Ouchi Shinsei Chemical Co., Ltd.
* 10 Diphenylguanidine, manufactured by Sumitomo Chemical Co., Ltd.
* 11 Bis (4-methyldibenzothiazolyl-2) -disulfide manufactured by Sanshin Chemical Industry Co., Ltd.
* 12 N-cyclohexyl-2-benzothiazylsulfenamide, manufactured by Ouchi Shinsei Chemical Co., Ltd.

  From Table 1, in Examples 1 to 5 in which a polyrotaxane or a crosslinked polyrotaxane and a high softening point resin were blended, the steering stability was improved compared to Comparative Example 1 in which these were not blended, and the durability was comparable to that of Comparative Example 1. Compared to Comparative Example 1, it can be seen that the factory workability is comparable to Comparative Example 1.

  On the other hand, in Comparative Examples 2 to 4 in which a polyrotaxane or a crosslinked polyrotaxane was not blended and a high softening point resin was blended, the handling stability was improved as compared with Comparative Example 1, but the durability increased as the blending amount of the high softening point resin increased. And factory workability deteriorated. In Comparative Example 5 in which a polycaprolactone-carboxylic acid compound having no rotaxane structure was blended and a high softening point resin was not blended, durability and factory workability were comparable to those in Comparative Example 1, and steering stability However, it deteriorated from Comparative Example 1.

Claims (23)

  A rubber composition comprising 10 to 200 parts by mass of a resin having a tackifying property to a rubber composition with respect to 100 parts by mass of a rubber component containing a polyrotaxane or a crosslinked polyrotaxane.   The polyrotaxane is a cyclic molecule, a linear molecule that is skewered in the opening of the cyclic molecule, and a blockade that is disposed at both ends of the linear molecule and prevents the cyclic molecule from being detached. The rubber composition according to claim 1 having a group.   The cross-linked polyrotaxane is disposed at both ends of the cyclic molecule, the linear molecule clasped into the opening of the cyclic molecule, and prevents the cyclic molecule from detaching. The rubber composition according to claim 1, wherein the rubber composition has at least two molecules of polyrotaxane having a blocking group, and the cyclic molecules of the at least two molecules of polyrotaxane are bonded to each other through a chemical bond.   When the cyclic molecule is clasped with the linear molecule in a skewered manner, the maximum inclusion amount of the cyclic molecule is defined as the maximum inclusion amount. The rubber composition according to claim 2 or 3, wherein the maximum inclusion amount is 0.001 to 0.6.   The rubber composition according to claim 2 or 3, wherein the cyclic molecule is selected from the group consisting of cyclodextrins, crown ethers, benzocrowns, dibenzocrowns and dicyclohexanocrowns.   The rubber composition according to claim 2 or 3, wherein the cyclic molecule is a cyclodextrin.   The rubber composition according to claim 2 or 3, wherein the cyclic molecule is α-cyclodextrin.   The linear molecule is polycaprolactone, natural rubber, styrene-butadiene copolymer, isobutylene-isoprene copolymer, polyisoprene, polyisobutylene, polybutadiene, polyethylene glycol, polypropylene glycol, polytetrahydrofuran, polydimethylsiloxane, polyethylene and The rubber composition according to claim 2 or 3, which is selected from the group consisting of polypropylene.   The rubber composition according to claim 2 or 3, wherein the linear molecule has a molecular weight of 1,000 to 1,000,000.   The rubber composition according to claim 2 or 3, wherein the blocking group is selected from the group consisting of dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, and pyrenes.   The rubber composition according to claim 3, wherein the cyclic molecules of the at least two molecules of polyrotaxane are bonded to each other through a chemical bond with a crosslinking agent.   The rubber composition according to claim 11, wherein the molecular weight of the crosslinking agent is less than 2,000.   The cross-linking agent is cyanuric chloride, trimesoyl chloride, terephthaloyl chloride, epichlorohydrin, dibromobenzene, glutaraldehyde, phenylene diisocyanate, diisocyanate trilein, divinyl sulfone, 1,1'-carbonyldiimidazole, and alkoxy The rubber composition according to claim 11 or 12, selected from the group consisting of silanes.   The rubber composition according to claim 1, wherein a content of the polyrotaxane or the crosslinked polyrotaxane in the rubber component is 0.1 to 20 parts by mass.   The rubber composition according to claim 1, wherein the amount of the resin is 20 to 100 parts by mass with respect to 100 parts by mass of the rubber component.   The rubber composition according to claim 1, wherein a softening point of the resin is 80C to 200C.   The rubber composition according to claim 16, wherein the softening point of the resin is 120 ° C to 160 ° C.   The rubber composition according to claim 1, wherein the resin has an OH value (KOHmg / g) of 20 to 210.   The rubber composition according to claim 18, wherein the resin has an OH value (KOH mg / g) of 50 to 130.   The rubber composition according to claim 1, wherein the acid value (KOHmg / g) of the resin is 1 to 20.   The rubber composition according to claim 20, wherein the resin has an acid value (KOHmg / g) of 2 to 10.   The rubber composition according to claim 1, wherein the rubber component contains a styrene-butadiene copolymer rubber.   A pneumatic tire using the rubber composition according to any one of claims 1 to 22 for a tread rubber.