Method for producing fine particles, fine particles, rubber composition for tires, and tires

Abstract

To provide fine particles that improve wet grip performance while maintaining excellent low fuel consumption performance of a tire.SOLUTION: A method for producing fine particles comprising, in a dispersion system containing an unmodified diene polymer, a nonionic or silicone surfactant, a hydroxy group-containing diene polymer having a hydroxy group and having a number average molecular weight of 1000 to 3000, and a chain extender containing an ionic chain extender, mixing a polyisocyanate compound having a plurality of isocyanate groups, in the mixing a molar ratio of the isocyanate groups to a total amount of the hydroxy groups and active hydrogen-containing groups possessed by the chain extenders is 1.5 to 6.0, and the fine particles are produced by polymerizing the hydroxy group-containing diene polymer, the chain extender, and the polyisocyanate compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for producing fine particles, fine particles, a rubber composition for tires, and tires. [Background technology]

[0002] Conventionally, rubber compositions for tires containing fine particles have been proposed. For example, Patent Document 1 describes a method for preparing a turbid paste-like product by mixing hydroxyl-terminated liquid polybutadiene, polybutene, m-xylylene diisocyanate, and a trimethylolpropane adduct of xylylene diisocyanate as fine particles contained in a tire rubber composition. This paste-like product generates fine particles with a particle size of 5 to 10 μm (backbone: polybutadiene, crosslinking: urethane bond) and is dispersed in a hydrolyzable silyl-terminated polyether (paragraph

[0080] ). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5229431 [Overview of the project] [Problems that the invention aims to solve]

[0004] On the other hand, when a car drives on a wet surface, the coefficient of friction decreases compared to a dry surface, making the tires more prone to slipping. Therefore, from a safety perspective, tires are required to have excellent wet grip performance. Furthermore, from an environmental perspective, tires are required to have low fuel consumption performance. Under these circumstances, the present inventors prepared a rubber composition with reference to Patent Document 1 and evaluated it. They found that such a rubber composition has room for improvement in terms of improving wet grip performance while maintaining the excellent fuel efficiency performance of the conventional composition.

[0005] Therefore, the present invention aims to provide fine particles that improve wet grip performance while maintaining the excellent fuel efficiency of the tire. [Means for solving the problem]

[0006] As a result of diligent research to solve the above problems, the present inventors have found that by mixing a polyisocyanate compound with a dispersion system containing an unmodified diene polymer, a nonionic or silicone surfactant, a hydroxyl group-containing diene polymer having a number average molecular weight of 1000 to 3000 and a chain extender containing an ionic chain extender, and by polymerizing the hydroxyl group-containing diene polymer, chain extender, and polyisocyanate compound in the above mixture, it is possible to obtain fine particles that improve wet grip performance while maintaining the excellent fuel efficiency performance of the tire, leading to the present invention. The present invention is based on the above findings, and specifically solves the above problems with the following configuration.

[0007] [1] A dispersion system containing an unmodified diene polymer, a nonionic or silicone surfactant, a hydroxyl group-containing diene polymer having a number average molecular weight of 1000 to 3000 and a hydroxyl group, and a chain extender containing an ionic chain extender, A polyisocyanate compound having multiple isocyanate groups is mixed, and in the above mixture, the molar ratio of the isocyanate groups to the total amount of the hydroxyl groups and the active hydrogen-containing groups of the chain extender is 1.5 to 6.0. A method for producing fine particles, comprising polymerizing the above-mentioned hydroxyl group-containing diene polymer, the above-mentioned chain extender, and the above-mentioned polyisocyanate compound. [2] The method for producing fine particles according to [1], wherein the average particle size of the fine particles is 0.1 to 200 μm. [3] The fine particles are a collection of multiple primary particles having an average particle diameter of 0.01 to 20 μm, as described in [1] or [2]. [4] The fine particles are produced as a dispersion dispersed in the above-mentioned unmodified diene-based polymer, and the content of the fine particles is 5 to 60% by mass in the above-mentioned dispersion, and the method for producing fine particles according to any one of [1] to [3]. [5] The method for producing fine particles according to any one of [1] to [4], wherein the fine particles have a urethane bond and a urea bond. [6] The method for producing fine particles according to any one of [1] to [5], wherein the ionic chain extender contains a carboxylate having a plurality of active hydrogen group-containing groups per molecule. [7] The method for producing fine particles according to any one of [1] to [6], wherein the ionic chain extender contains a compound having an ionic group, which is a combination of a compound having a plurality of active hydrogen group-containing groups and a carboxy group and a tertiary amine having a plurality of active hydrogen group-containing groups. [8] The method for producing fine particles according to any one of [1] to [7], wherein the polyisocyanate compound contains a polyisocyanate compound having an average functionality of 2.1 or more. [9] Fine particles produced by the production method according to any one of [1] to [8].

[0008]

[10] A rubber composition for tires containing a diene rubber, fine particles produced by the production method according to any one of [1] to [8], and a filler containing at least one of carbon black and a white filler, wherein the content of the fine particles is 1 to 30 parts by mass with respect to 100 parts by mass of the diene rubber, and the content of the filler is 30 to 100 parts by mass with respect to 100 parts by mass of the diene rubber.

[11] A tire produced using the rubber composition for tires according to

[10] . [Effect of the Invention]

[0009] According to the production method of the present invention, fine particles capable of improving wet grip performance while maintaining excellent low fuel consumption performance of tires can be produced. [Brief Description of the Drawings]

[0010] [Figure 1] Figure 1 is a photograph taken by observing the fine particles of this embodiment 1 with a scanning electron microscope. [Figure 2] Figure 2 is a schematic partial cross-sectional view of an example of an embodiment of the tire of the present invention. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below. In this specification, a numerical range represented by "~" means the range that includes the numbers written before and after "~". In this specification, unless otherwise specified, each component may be composed of the substance corresponding to that component, either individually or in combination of two or more substances. If a component contains two or more substances, the content of the component means the total content of the two or more substances. In this specification, "the effects of the present invention are superior" may refer to a situation where at least one of the wet grip performance and fuel efficiency performance is superior. In this specification, fine particles produced by the method for producing fine particles of the present invention may be referred to as "specific fine particles."

[0012] [Method for producing fine particles] The method for producing fine particles of the present invention (the manufacturing method of the present invention) is as follows: A dispersion system containing an unmodified diene polymer, a nonionic or silicone surfactant, a hydroxyl group-containing diene polymer having a number average molecular weight of 1000 to 3000 and containing hydroxyl groups, and a chain extender containing an ionic chain extender, A polyisocyanate compound having multiple isocyanate groups is mixed, and in the above mixture, the molar ratio of the isocyanate groups to the total amount of the hydroxyl groups and the active hydrogen-containing groups of the chain extender is 1.5 to 6.0. This is a method for producing fine particles, which involves polymerizing the above-mentioned hydroxyl group-containing diene polymer, the above-mentioned chain extender, and the above-mentioned polyisocyanate compound.

[0013] Because the manufacturing method of the present invention has this configuration, it is believed that the desired effect can be obtained. The reason for this is not clear, but it is presumed to be as follows. Since the fine particles produced by the manufacturing method of the present invention are formed by polymerizing the above-mentioned hydroxyl group-containing diene polymer, the above-mentioned chain extender containing the above-mentioned ionic chain extender, and the above-mentioned polyisocyanate compound, it can be inferred that ionic groups derived from the ionic chain extender are introduced into primary particles, and multiple primary particles aggregate to form fine particles due to the action of the above-mentioned ionic groups. Here, the fine particles produced by the manufacturing method of the present invention will be described with reference to the attached drawings. However, the present invention is not limited to the attached drawings. Figure 1 is a photograph taken by observing the fine particles of this embodiment 1 with a scanning electron microscope (SEM) (magnification 16,000x). In Figure 1, multiple primary particles 12 aggregate to form fine particles 10. The fine particles 10 have multiple protrusions formed by the primary particles 12. Generally, microparticles formed by the aggregation of primary particles of the same material tend to have smooth, perfectly spherical surfaces. On the other hand, in the manufacturing method of the present invention, as described above, ionic groups derived from the ionic chain extender are introduced into the primary particles. As a result, the primary particles partially aggregate due to the action of the ionic groups, and therefore, the fine particles produced by the manufacturing method of the present invention do not aggregate integrally and have a smooth, spherical surface, but rather have multiple protrusions formed by the primary particles as described above. Furthermore, the fine particles produced by the manufacturing method of the present invention are thought to have multiple protrusions formed by primary particles, thereby improving the surface roughness of the tire and enhancing the wet grip performance while maintaining the tire's excellent fuel efficiency. The manufacturing method of the present invention will be described in detail below.

[0014] [Unmodified diene polymers] The unmodified diene polymer used in the manufacturing method of the present invention may be any unmodified polymer in which the main chain is formed by monomers containing a conjugated diene monomer. Unmodified diene polymers can serve as a dispersion medium for dispersions produced by the manufacturing method of the present invention.

[0015] Examples of unmodified diene polymers include polyisoprene, polybutadiene, acrylonitrile butadiene copolymer, styrene butadiene copolymer, styrene isoprene copolymer, and styrene isoprene butadiene rubber copolymer. Among these, the present invention is more likely to produce a copolymer containing polybutadiene, polyisoprene, or styrene butadiene copolymer, and more likely to produce a copolymer containing polyisoprene.

[0016] (Number-average molecular weight of unmodified diene polymers) The number-average molecular weight (Mn) of the unmodified diene polymer is preferably 1,000 to 100,000, and more preferably 5,000 to 50,000, for better performance of the present invention. In the present invention, the above Mn can be a standard polystyrene equivalent value obtained by gel permeation chromatography (GPC) measurement under the following conditions. • Solvent: tetrahydrofuran • Detector: RI detector

[0017] (Amount of unmodified diene polymer) The amount of unmodified diene polymer is preferably 200 to 5000 parts by mass per 100 parts by mass of the hydroxyl group-containing diene polymer described later, for the reason that the effects of the present invention are superior.

[0018] [Hydroxy group-containing diene polymer] The hydroxyl group-containing diene polymer used in the manufacturing method of the present invention is a polymer whose skeleton is a diene polymer, which has hydroxyl groups, and whose number average molecular weight is 1000 to 3000. Hydroxyl group-containing diene polymers can react with polyisocyanate compounds, as described later.

[0019] (Skeleton) Examples of the skeleton of a hydroxyl group-containing diene polymer include polyisoprene, polybutadiene, acrylonitrile butadiene copolymer, styrene butadiene copolymer, styrene isoprene copolymer, and styrene isoprene butadiene rubber copolymer. Among these, the skeleton is preferably polybutadiene or polyisoprene because it provides superior effects of the present invention. Furthermore, the skeleton is more preferably polybutadiene because it provides superior effects of the present invention (particularly fuel efficiency). The skeleton is more preferably polyisoprene because it provides superior effects of the present invention (particularly wet grip performance).

[0020] [Hydroxy group] In the present invention, the hydroxyl group-containing diene polymer only needs to have one or more hydroxyl groups per molecule, but from the viewpoint of achieving superior effects of the present invention, it is preferable that it has multiple hydroxyl groups per molecule.

[0021] [Number average molecular weight] In the present invention, the number-average molecular weight (Mn) of the hydroxyl group-containing diene polymer is 1000 to 3000. The number-average molecular weight of the hydroxyl group-containing diene polymer is preferably 2000 to 3000, for which the effects of the present invention are superior. In the present invention, the above Mn can be a standard polystyrene equivalent value obtained by gel permeation chromatography (GPC) measurement under the following conditions. • Solvent: tetrahydrofuran • Detector: RI detector

[0022] [Chain extender] The manufacturing method of the present invention uses a chain extender, and the chain extender includes an ionic chain extender. Chain extenders are compounds that have multiple active hydrogen group-containing groups per molecule. The chain extender can react with isocyanate groups, such as those found in polyisocyanate compounds described later, at the active hydrogen group-containing group described above. Examples of active hydrogen group-containing groups include hydroxyl groups and amino groups.

[0023] [Ionic chain extenders] The ionic chain extender used in the manufacturing method of the present invention is a compound having an ionic group in addition to the active hydrogen group-containing group described above. In the ionic chain extender, the ionic group is a group different from the active hydrogen group-containing group. By using an ionic chain extender, ionic groups can be introduced into specific microparticles (polymers that form specific microparticles). One preferred embodiment of the ionic chain extender is that it has a hydroxyl group as an active hydrogen group-containing group.

[0024] (Ionic group) Examples of ionic groups in ionic chain extenders include carboxylate ions (-COO - ) anions such as; NH derived from tertiary amines + Examples include organic cations such as the onium ion (a tertiary nitrogen atom); and metallic cations such as the sodium ion. In the above ionic group, the above anion and the above organic cation or the above metal cation may be in a counterion relationship (combination). Examples of the above counterion combinations include a combination of a carboxylate ion and the above cation, and specifically, examples include a combination of a carboxylate ion and an organic cation, and a combination of a carboxylate ion and a metal cation. When the above combination of counterions is present, the ionic chain extender may be a carboxylate salt having multiple active hydrogen group-containing groups per molecule.

[0025] From the viewpoint of achieving superior effects of the present invention, it is preferable that the ionic group consists of an anion and a cation in a counterion relationship (combination). From the viewpoint of achieving superior effects of the present invention, the combination of counterions (combination of anion and cation) is preferably a combination of a carboxylate ion and the cation, and a combination of a carboxylate ion and an organic cation (for example, NH derived from a tertiary amine) is preferable.+ A combination of ) or a combination of carboxylate ions and sodium ions is more preferable, and a combination of carboxylate ions and organic cations (for example, NH derived from tertiary amines) is preferred. + A combination with ) is even more preferable, and the carboxylate ion and NH derived from a tertiary amine + This combination is particularly preferable.

[0026] From the viewpoint of achieving superior effects of the present invention, the ionic chain extender preferably contains a carboxylate salt having multiple active hydrogen group-containing groups per molecule. The counterion combinations in the above carboxylate salts are the same as those described above.

[0027] Examples of ionic chain extenders include compounds having anionic groups and compounds having cationic groups. Compounds having anionic groups also have multiple active hydrogen group-containing groups per molecule, in addition to the anionic group. The same applies to compounds having cationic groups.

[0028] (Raw material for compounds containing anionic groups) Examples of raw materials for compounds having anionic groups (compounds capable of forming anionic groups) include compounds having multiple active hydrogen group-containing groups and a carboxyl group (-COOH). Specifically, examples include bis(hydroxyalkyl)carboxylic acids. In bis(hydroxyalkyl)carboxylic acids, the number of carbon atoms in the alkyl group of the hydroxyalkyl portion can be 1 to 10. In bis(hydroxyalkyl)carboxylic acids, the number of carbon atoms in the hydrocarbon group to which the hydroxyalkyl group and the carboxyl group are bonded can be 1 to 10. From the viewpoint of achieving superior effects of the present invention, it is preferable that the compound capable of forming an anionic group includes a bis(hydroxyalkyl)carboxylic acid such as bis(hydroxymethyl)propionic acid.

[0029] (Compounds that can form cationic groups) Examples of compounds that can form cationic groups (raw materials for compounds having cationic groups) include tertiary amines that have multiple active hydrogen group-containing groups. From the viewpoint of achieving superior effects of the present invention, it is preferable that the compound capable of forming a cationic group includes a tertiary amine having multiple active hydrogen group-containing groups.

[0030] (Tertiary amine containing an active hydrogen group) A tertiary amine having an active hydrogen group is a compound having an active hydrogen group and a nitrogen atom (tertiary nitrogen atom) that forms a tertiary amine. The hydrocarbon group to which the active hydrogen group and the nitrogen atom are bonded is not particularly limited. From the viewpoint of achieving superior effects of the present invention, the tertiary amine having an active hydrogen group preferably includes a tertiary amine having three hydroxyl groups, more preferably a tertiary amine in which three hydroxyalkyl groups having 1 to 10 carbon atoms are bonded to one nitrogen atom, and even more preferably triethanolamine.

[0031] Examples of ionic chain extenders include compounds having ionic groups, obtained by combining a compound having multiple active hydrogen group-containing groups and a carboxyl group (-COOH) with a tertiary amine having multiple active hydrogen group-containing groups; and compounds having ionic groups, obtained by combining a compound having multiple active hydrogen group-containing groups and a carboxyl group (-COOH) with a metal cation (e.g., sodium ion). Examples of raw materials for the above-mentioned metal cation include metal hydroxides such as sodium hydroxide. From the viewpoint of achieving superior effects of the present invention, the ionic chain extender preferably contains a compound having an ionic group, which is a combination of a compound having multiple active hydrogen group-containing groups and a carboxyl group (-COOH) with a tertiary amine having multiple active hydrogen group-containing groups; more preferably contains a compound having an ionic group, which is a combination of a bis(hydroxyalkyl)carboxylic acid and a tertiary amine having multiple active hydrogen group-containing groups; and even more preferably contains a compound having an ionic group, which is a combination of a bis(hydroxyalkyl)carboxylic acid and a tertiary amine in which three hydroxyalkyl groups having 1 to 10 carbon atoms are bonded to one nitrogen atom.

[0032] When the ionic chain extender is a combination of a compound having multiple active hydrogen group-containing groups and a carboxyl group (-COOH) (carboxyl compound) and a tertiary amine having multiple active hydrogen group-containing groups, one or both of the carboxyl compound and the tertiary amine may be incorporated into the polymer constituting the fine particles.

[0033] (Method for preparing ionic chain extenders) One method for preparing an ionic chain extender is to mix a compound capable of forming an anionic group and a compound capable of forming a cationic group in water.

[0034] One example of a compound that can form anionic groups is 2,2-bis(hydroxymethyl)propionic acid, which has a high melting point and is a solid at room temperature (23°C). Thus, when a compound capable of forming an anionic group and a compound capable of forming a cationic group have a high melting point or are solid under room temperature (23°C) conditions, one preferred embodiment is to use a mixture obtained by mixing the compound capable of forming an anionic group and the compound capable of forming a cationic group in water. In addition to water, the above mixture may contain a salt formed by the compound capable of forming an anionic group and the compound capable of forming a cationic group (for example, the carboxylate salt having multiple active hydrogen group-containing groups per molecule as described above) as an ionic chain extender. When using the above mixture as the ionic chain extender, it is preferable to disperse the ionic chain extender in an unmodified diene polymer so that the ionic chain extender can react efficiently with the polyisocyanate compound. When water is used in the preparation of ionic chain extenders, it is sufficient to use an amount of water that can dissolve the compounds capable of forming anionic groups and the compounds capable of forming cationic groups. The molar ratio of a compound capable of forming an anionic group to a compound capable of forming a cationic group (compound capable of forming anionic groups: compound capable of forming cationic groups) is preferably 1:0.9 to 1.1, and more preferably 1:1, from the viewpoint of achieving superior effects of the present invention.

[0035] (Nonionic chain extenders) From the viewpoint of achieving superior effects of the present invention, it is preferable that the chain extender further includes a nonionic chain extender in addition to the ionic chain extender. One preferred embodiment of the nonionic chain extender is that it has an amino group as an active hydrogen group-containing group. Examples of nonionic chain extenders include diamine-based nonionic chain extenders such as dimethylthiotoluenediamine. If the chain extender further contains a nonionic chain extender, the molar ratio of the ionic chain extender to the nonionic chain extender (ionic chain extender:nonionic chain extender) is preferably 1:0.5 to 2.0 from the viewpoint of achieving superior effects of the present invention.

[0036] (Amount of chain extender) The amount of the chain extender (or, if the chain extender further contains a nonionic chain extender, the total amount of the ionic chain extender and the nonionic chain extender) is preferably 10 to 50 parts by mass per 100 parts by mass of the hydroxyl group-containing diene polymer, for the reasons that the effects of the present invention are superior.

[0037] [Nonionic or silicone-based surfactants] The nonionic or silicone-based surfactant used in the manufacturing method of the present invention is a nonionic surfactant or a silicone-based surfactant. By using the above-mentioned surfactant, hydroxyl group-containing diene polymers during manufacturing, or specific fine particles after manufacturing, can be dispersed in the unmodified diene polymer. In the manufacturing method of the present invention, a nonionic surfactant and a silicone surfactant may be used in combination.

[0038] (Nonionic surfactants) The nonionic surfactant is not particularly limited. Examples of nonionic surfactants include glycerol-based fatty acid esters, sorbitan-based fatty acid esters, and sorbitol-based fatty acid esters.

[0039] (Silicone-based surfactant) Silicone-based surfactants are surfactants based on silicone polymers. Note that silicone-based surfactants do not contain nonionic surfactants.

[0040] The above-mentioned surfactant preferably includes a silicone-based surfactant because it provides superior effects for the present invention.

[0041] (Amount of nonionic or silicone-based surfactant) The amount of nonionic or silicone surfactant (or the total amount of both when nonionic and silicone surfactants are used in combination) is preferably 1 to 20 parts by mass per 100 parts by mass of the hydroxyl group-containing diene polymer, for the reasons that the effects of the present invention are superior.

[0042] [Polyisocyanate compounds] The polyisocyanate compound used in the manufacturing method of the present invention is a compound having multiple isocyanate groups. Examples of polyisocyanates include aromatic polyisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI; e.g., 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate), polymeric MDI, 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), tollidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), and triphenylmethane triisocyanate; Hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanate (NBDI), transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), bis(isocyanate-methyl)cyclohexane (H6XDI), dicyclohexylmethane diisocyanate (H 12 Aliphatic polyisocyanates (including alicyclic polyisocyanates), such as MDI; These carbodiimide-modified polyisocyanates; These urethane prepolymers are examples.

[0043] The polyisocyanate preferably contains an aromatic polyisocyanate, more preferably an MDI-based aromatic polyisocyanate such as MDI, polymeric MDI, or carbodiimide-modified MDI, and even more preferably polymeric MDI.

[0044] Polymeric MDI is generally a mixture of monomeric MDI and its multinuclear form.

[0045] Carbodiimide-modified MDI is MDI that has been modified with carbodiimide.

[0046] The polyisocyanate compound is preferably a polyisocyanate compound with an average number of functional groups of 2.1 or more, for the reasons that the effects of the present invention are superior. The functional group in the above average number of functional groups is an NCO group. One preferred embodiment is that the polyisocyanate compound is a polyisocyanate compound with an average number of functional groups of 2.1 or more.

[0047] (Amount of polyisocyanate compound) The amount of the polyisocyanate compound is preferably 100 to 500 parts by mass per 100 parts by mass of the hydroxyl group-containing diene polymer, for reasons that the effects of the present invention are superior.

[0048] (Reactive catalyst) In the manufacturing method of the present invention, one preferred embodiment is the use of a reactive catalyst, for which the effects of the present invention are even better. A reactive catalyst is a compound that reacts with an isocyanate group while simultaneously promoting the reaction between the two. The reactive catalyst preferably contains a tertiary amine having multiple active hydrogen group-containing groups, for which the effects of the present invention are superior.

[0049] (Tertiary amine containing an active hydrogen group) A tertiary amine having an active hydrogen group is a compound having an active hydrogen group and a nitrogen atom that forms a tertiary amine. The hydrocarbon group to which the active hydrogen group and the nitrogen atom are bonded is not particularly limited. From the viewpoint of achieving superior effects of the present invention, the tertiary amine having an active hydrogen group preferably includes a tertiary amine having three hydroxyl groups, more preferably a tertiary amine in which three hydroxyalkyl groups having 1 to 10 carbon atoms are bonded to one nitrogen atom, and even more preferably triethanolamine. Furthermore, the reactive catalyst does not have ionic groups. In the production method of the present invention, when a reactive catalyst (for example, a tertiary amine having an active hydrogen group) is used, the reactive catalyst is used as is, so the reactive catalyst does not have ionic groups, and therefore, in the present invention, the reactive catalyst does not fall under the category of an ionic chain extender.

[0050] (Amount of reactive catalyst) When a reactive catalyst is further used in the manufacturing method of the present invention, the amount of the reactive catalyst is preferably 1.0 to 20.0 parts by mass per 100 parts by mass of the hydroxyl group-containing diene polymer, for the reason that the effects of the present invention are superior.

[0051] [Molar ratio of isocyanate groups in the polyisocyanate compound to the total amount of hydroxyl groups in the hydroxyl group-containing diene polymer and active hydrogen-containing groups in the chain extender] In the production method of the present invention, the molar ratio of isocyanate groups in the polyisocyanate compound to the total amount of hydroxyl groups in the hydroxyl group-containing diene polymer and active hydrogen-containing groups in the chain extender [NCO groups / (OH groups + active hydrogen-containing groups)] is 1.5 to 6.0. If the chain extender further contains a nonionic chain extender, the amount of active hydrogen-containing groups in the chain extender includes the amount of active hydrogen-containing groups in the nonionic chain extender. In the manufacturing method of the present invention, if a reactive catalyst is further used and the reactive catalyst has active hydrogen group-containing groups, the amount of active hydrogen group-containing groups of the reactive catalyst is added to the total amount of hydroxyl groups of the hydroxyl group-containing diene polymer and active hydrogen group-containing groups of the chain extender [(OH group + active hydrogen group) in the above formula]. Furthermore, when the amount of active hydrogen-containing groups in the reactive catalyst is added as described above in the calculation of the above molar ratio, the numerical range of the molar ratio obtained and its preferred range are the same as the numerical range of the above molar ratio (1.5 to 6.0) and its preferred range described later. Note that the total amount of hydroxyl groups in the hydroxyl group-containing diene polymer and the active hydrogen-containing groups in the chain extender does not include the amount of active hydrogen groups produced by water. Furthermore, when a metal hydroxide is used as a raw material for the metal cation when preparing an ionic chain extender, the OH group derived from the metal hydroxide is not included in the active hydrogen-containing group of the chain extender.

[0052] From the viewpoint of achieving superior effects of the present invention, the above molar ratio is preferably 1.8 to 4.0, and more preferably 2.0 to 2.5.

[0053] (Manufacturing method) In the production method of the present invention, the polyisocyanate compound is mixed with a dispersion system containing an unmodified diene polymer, the surfactant, the hydroxyl group-containing diene polymer, and a chain extender containing an ionic chain extender. As described above, pre-prepared ionic chain extenders can be used. In the production method of the present invention, if a reactive catalyst is used further, it is preferable to add the reactive catalyst to the above-mentioned dispersion system.

[0054] • Preparation of dispersion systems For preparing a dispersion system containing an unmodified diene polymer, the above-mentioned surfactant, the above-mentioned hydroxyl group-containing diene polymer, a chain extender containing an ionic chain extender, and a reactive catalyst that can be used as needed, it is preferable to stir and mix these components. The temperature during the preparation of the above dispersion system is preferably between 10 and 60°C. Examples of dispersion systems obtained by the above preparation include a dispersion system in which the hydroxyl group-containing diene polymer, an ionic chain extender, and (if a nonionic chain extender and / or a reactive catalyst is used, a nonionic chain extender and / or a reactive catalyst) are dispersed in an unmodified diene polymer in the presence of the surfactant.

[0055] • Mix the above polyisocyanate compound into the dispersion system. Next, the polyisocyanate compound is mixed into the dispersion system. The method of mixing the polyisocyanate compound into the dispersion system is not particularly limited. It is preferable to perform the mixing while stirring. When mixing the polyisocyanate compound into the above dispersion system, the temperature is preferably between 10 and 60°C.

[0056] In the manufacturing method of the present invention, fine particles (specific fine particles) can be produced by polymerizing the above-mentioned hydroxyl group-containing diene polymer, a chain extender containing an ionic chain extender, and the above-mentioned polyisocyanate compound.

[0057] The specific fine particles may have at least urethane bonds. The urethane bonds can be introduced into the specific fine particles by the reaction of the hydroxyl group-containing diene polymer with the polyisocyanate compound, and by the reaction of a chain extender containing an ionic chain extender (when the chain extender or ionic chain extender has a hydroxyl group) with the polyisocyanate compound. Furthermore, the specific fine particles may also have urea bonds in addition to the urethane bonds described above. The urea bonds can be introduced into the specific fine particles by a reaction between the compound having an amino group as the active hydrogen-containing group and the polyisocyanate compound, when a compound having an amino group as the active hydrogen-containing group is further used in the production method of the present invention. Examples of compounds having an amino group as the active hydrogen-containing group include diamine-based nonionic chain extenders such as dimethylthiotoluenediamine.

[0058] (Average particle size of specific fine particles) From the viewpoint of achieving superior effects of the present invention, the average particle size of the specific fine particles (overall) is preferably 0.1 to 200 μm. The average particle size of the specific microparticles (overall) is the average value obtained from the particle sizes of five arbitrary specific microparticles in photographs observed with a scanning electron microscope (SEM, magnification 500 to 16,000x).

[0059] From the viewpoint of achieving superior effects of the present invention, it is preferable that the specific fine particles are formed by the aggregation of multiple primary particles having an average particle diameter of 0.01 to 20 μm. The average particle diameter of the primary particles constituting the specific microparticles is the average value obtained from the particle diameters of 10 arbitrary primary particles in photographs observed with a scanning electron microscope (SEM, magnification 500 to 16,000x).

[0060] (Convex part) Specific fine particles may have multiple protrusions formed by primary particles.

[0061] (dispersion) The specific fine particles can be produced as a dispersion in the above-mentioned unmodified diene polymer. The above dispersion may contain specific fine particles, an unmodified diene polymer, and the above-mentioned surfactant, etc.

[0062] (Content of specific fine particles) When the specific fine particles are dispersed in an unmodified diene polymer, the content of the specific fine particles is preferably 5 to 60% by mass of the dispersion, from the viewpoint of achieving superior effects of the present invention.

[0063] [Fine particles] The fine particles of the present invention are fine particles produced by the manufacturing method of the present invention. The fine particles of the present invention are not particularly limited except that they are manufactured by the manufacturing method of the present invention. The fine particles of the present invention are the same as the specified fine particles described above. Furthermore, in the present invention, the multiple protrusions formed by primary particles of specific fine particles have diverse specific embodiments, and it is not possible to comprehensively express the above specific embodiments. Therefore, it is impossible or impractical to directly identify the fine particles of the present invention by their structure or properties. Accordingly, it is considered that "impossible or impractical circumstances" may be recognized for the fine particles of the present invention and the rubber composition of the present invention described later.

[0064] [Rubber composition for tires] The rubber composition for tires of the present invention (the rubber composition of the present invention) This is a rubber composition for tires, comprising a diene rubber, fine particles (specific fine particles) produced by the manufacturing method of the present invention, and a filler containing at least one of carbon black and a white filler, wherein the content of the fine particles is 1 to 30 parts by mass per 100 parts by mass of the diene rubber, and the content of the filler is 30 to 100 parts by mass per 100 parts by mass of the diene rubber. The rubber composition of the present invention, by containing specific fine particles, can improve wet grip performance while maintaining excellent fuel efficiency when used in a tire.

[0065] [Diene-based rubber] Examples of diene rubbers contained in the rubber composition of the present invention include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR), and derivatives of these rubbers. The above diene-based rubber preferably contains SBR because it provides superior effects for the present invention.

[0066] The weight molecular weight (Mw) of the above diene rubber is not particularly limited, but for reasons that the effects of the present invention are superior, it is preferably 100,000 to 10,000,000, more preferably 200,000 to 1,500,000, and even more preferably 300,000 to 3,000,000. Furthermore, while the number-average molecular weight (Mn) of the diene rubber is not particularly limited, it is preferably 50,000 to 5,000,000, more preferably 100,000 to 750,000, and even more preferably 150,000 to 1,500,000, for reasons that the effects of the present invention are superior. In addition, in the rubber composition of the present invention, the number-average molecular weight (Mn) of the diene rubber can be greater than 100,000.

[0067] The Mw and Mn values ​​of the above diene rubber can be obtained as standard polystyrene equivalent values ​​obtained by gel permeation chromatography (GPC) measurement under the following conditions. • Solvent: tetrahydrofuran • Detector: RI detector

[0068] Furthermore, the diene-based rubber contained in the rubber composition of the present invention does not include the unmodified diene-based polymer that is included as a dispersion medium in the dispersion described later.

[0069] [Fine particles] The fine particles contained in the rubber composition of the present invention are not particularly limited, except that they are produced by the method for producing fine particles of the present invention. The fine particles contained in the rubber composition of the present invention are the same as the specified fine particles described above. In the present invention, a dispersion containing specific fine particles can be used as the specific fine particles.

[0070] [Content of fine particles] In the rubber composition of the present invention, the content of the above-mentioned fine particles (net content of specific fine particles) is 1 to 30 parts by mass per 100 parts by mass of the above-mentioned diene-based rubber. Note that "100 parts by mass of the above-mentioned diene-based rubber" refers to 100 parts by mass of the above-mentioned diene-based rubber blended in the rubber composition of the present invention. The same applies hereafter to the standard "100 parts by mass of diene-based rubber" for the content of each component contained in the rubber composition of the present invention. The content of the above-mentioned fine particles (net content of specific fine particles) is preferably 5 to 20 parts by mass per 100 parts by mass of the above-mentioned diene rubber, for the reason that the effects of the present invention are superior.

[0071] [Filler] The rubber composition of the present invention contains a filler. In the rubber composition of the present invention, the filler comprises at least one of carbon black and a white filler. The filler may also comprise both carbon black and a white filler.

[0072] (Carbon Black) The above carbon black is not particularly limited, and for example, various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, SRF can be used. The nitrogen adsorption specific surface area (N2SA) of the above carbon black is not particularly limited. The carbon black preferably contains carbon black with an N2SA of 50 to 200 m 2 / g, and more preferably contains carbon black with an N2SA of 70 to 150 m 2 / g. Here, the nitrogen adsorption specific surface area (N2SA) is a value measured according to JIS K6217-2:2001 "Part 2: Method for determining specific surface area - Nitrogen adsorption method - Single point method" for the amount of nitrogen adsorbed on the carbon black surface.

[0073] (White filler) The above white filler is not particularly limited, and examples include silica, calcium carbonate, magnesium carbonate, talc, clay, alumina, aluminum hydroxide, titanium oxide, calcium sulfate, etc. Among them, it is preferable to contain silica because the effects of the present invention are more excellent.

[0074] The above silica is not particularly limited, and examples include wet silica (hydrous silicic acid) and dry silica (anhydrous silicic acid).

[0075] The cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of the above silica is not particularly limited. The silica preferably contains silica with a CTAB adsorption specific surface area (hereinafter abbreviated as CTAB) of 100 to 400 m 2 / g, more preferably contains silica with a CTAB of 150 to 300 m 2 / g, and even more preferably contains silica with a CTAB of 160 to 250 m 2 / g. Here, the CTAB adsorption specific surface area is the value obtained by measuring the amount of CTAB adsorbed onto the silica surface according to JIS K6217-3:2001 "Part 3: Method for determining specific surface area - CTAB adsorption method".

[0076] [Filler content] In the rubber composition of the present invention, the content of the filler (the total amount of carbon black and white filler if both are used as fillers) is 30 to 100 parts by mass per 100 parts by mass of the diene-based rubber. When carbon black and white filler are used in combination as fillers, the amount of white filler can be 5 to 10 times (by mass) the amount of carbon black.

[0077] (optional ingredient) The rubber composition of the present invention may further contain components other than those described above (optional components) as needed. Examples of the optional components mentioned above include silane coupling agents, zinc oxide, stearic acid, antioxidants, sulfur, and vulcanization accelerators.

[0078] (Method for manufacturing rubber composition) The method for producing the rubber composition of the present invention is not particularly limited, and specific examples include, for example, a method of mixing each of the above-mentioned components using known methods and apparatus (e.g., Banbury mixer, kneader, roll, etc.). If the rubber composition of the present invention further contains sulfur or a vulcanization accelerator, it is preferable to first mix the components other than sulfur and the vulcanization accelerator at a high temperature (preferably 100 to 160°C), cool them, and then mix in the sulfur or vulcanization accelerator. The rubber composition of the present invention can be vulcanized under conventionally known vulcanization or crosslinking conditions.

[0079] The rubber composition of the present invention can be used, for example, in tires. The rubber composition of the present invention is preferably used in the tread portion of a tire.

[0080] [tire] The tire of the present invention is a tire manufactured using the rubber composition of the present invention. The tire of the present invention is not particularly limited except that it is manufactured using the rubber composition of the present invention.

[0081] Examples of tires according to the present invention include pneumatic tires. One preferred embodiment is a tire having a tire tread portion manufactured using the rubber composition of the present invention.

[0082] Figure 2 shows a schematic partial cross-sectional view of an example embodiment of the tire of the present invention. Note that the tire of the present invention is not limited to the attached drawings. In Figure 2, reference numeral 1 represents the bead portion, reference numeral 2 represents the sidewall portion, and reference numeral 3 represents the tire tread portion. Furthermore, a carcass layer 4 with embedded fiber cords is installed between the pair of left and right bead sections 1, and the ends of this carcass layer 4 are folded back and wrapped around the bead core 5 and bead filler 6 from the inside to the outside of the tire. Furthermore, in the tire tread section 3, a belt layer 7 is arranged around the entire circumference of the tire, on the outside of the carcass layer 4. Furthermore, a rim cushion 8 is positioned in the bead portion 1 where it contacts the rim. It is preferable that the tire tread portion 3 is formed using the rubber composition of the present invention.

[0083] The tire of the present invention can be manufactured, for example, according to conventionally known methods. If the tire of the present invention is a pneumatic tire, the gas used to fill the pneumatic tire can be, for example, ordinary air or air with adjusted oxygen partial pressure, as well as inert gases such as nitrogen, argon, or helium. [Examples]

[0084] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. [Method for producing fine particles] (Example 1) Method for producing fine particles 1 50.0 g of a diene polymer containing hydroxyl groups (Poly bd R-45HT, manufactured by Idemitsu Kosan Co., Ltd.; liquid polybutadiene with hydroxyl groups at both ends; number average molecular weight 2,800; hydroxyl group content 0.83 mol / kg), 7.5 g of dimethylthiotoluenediamine (nonionic chain extender; Heartcure 30, manufactured by Kumiai Chemical Co., Ltd.), 4.7 g of 2,2-bis(hydroxymethyl)propionic acid (0.035 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), and triethanolamine (5.3 g of triethanolamine, manufactured by Tokyo Chemical Industry Co., Ltd.) A mixture of 10 g of a salt formed by (manufactured by) and 10 g of water (the above mixture was obtained by dissolving the above 2,2-bis(hydroxymethyl)propionic acid (0.035 mol) and triethanolamine (0.035 mol) in 10 g of water beforehand), 5 g of triethanolamine (reactive catalyst), 212.0 g of liquid isoprene polymer (LIR-30 manufactured by Kuraray Co., Ltd., unmodified isoprene polymer, number average molecular weight 28000), and 2.5 g of Niax silicone L-5111 (silicone-based surfactant, manufactured by Momentive Performance Materials Inc.) was stirred in a rotary-orbiting stirrer for 2 minutes under room temperature conditions to prepare a dispersion system. Note that the above salt (carboxylate salt) of 2,2-bis(hydroxymethyl)propionic acid and the above triethanolamine corresponds to the ionic chain extender in the present invention. Next, 125.0 g of polymeric MDI (Millionate MR-400, manufactured by Tosoh Corporation, NCO% 30.4%, average number of functional groups 3.0) was added to the above dispersion system and stirred for 2 minutes under room temperature conditions, resulting in fine particles 1 (backbone: polybutadiene, crosslinking: urethane bond and urea bond, ionic group: COO - and N + A dispersion 1 was prepared by dispersing (which is incorporated into the polymer constituting the fine particles 1) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of fine particles 1 in the entire dispersion 1 was 50% by mass. When particle 1 was observed with a scanning electron microscope (SEM, 16,000x magnification), it was confirmed that multiple primary particles with an average particle diameter of 0.5 μm had aggregated to form aggregates with an average particle diameter of 3 μm, each with multiple protrusions. A photograph of the above observation results is shown in Figure 1. In Figure 1, multiple primary particles 12 aggregate to form fine particles 10. The fine particles 10 have multiple protrusions formed by the primary particles 12.

[0085] (molar ratio) * ) The molar ratio of isocyanate groups in the polyisocyanate compound to the total amount of hydroxyl groups in the hydroxyl group-containing diene polymer and active hydrogen-containing groups in the chain extender when producing fine particles 1 is shown in the "Molar Ratio" column of Dispersion 1 in Table 1. * As shown above, in the production of fine particles 1, a nonionic chain extender and a reactive catalyst were used, so the above molar ratio * In the calculation, the total amount of hydroxyl groups in the hydroxyl group-containing diene polymer and the active hydrogen-containing groups in the chain extender was added to the number of moles of active hydrogen-containing groups in the nonionic chain extender and the reactive catalyst. The above molar ratio when manufacturing fine particles other than comparative fine particle 1 is shown in the "Molar Ratio" column for each dispersion in Table 1. * This is shown in ".

[0086] (Example 2) Method for producing fine particles 2 Fine particle 2 was prepared in the same manner as fine particle 1, except that 50.0 g of Idemitsu Kosan's Poly ip (liquid polyisoprene with hydroxyl groups at the terminals; number average molecular weight 2500; hydroxyl group content 0.83 mol / kg) was used instead of Poly bd R-45HT as the diene polymer containing hydroxyl groups. (Scaffold: polyisoprene, Crosslinking: urethane bond and urea bond, Ionic group: COO) - and N + A dispersion 2 was prepared by dispersing (which has been introduced into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of fine particles 2 in the entire dispersion 2 was 50% by mass. When microparticle 2 was observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 0.4 μm had aggregated to form aggregates with an average particle diameter of 5 μm, each containing multiple protrusions.

[0087] (Example 3) Method for producing fine particles 3 Fine particles 3 (backbone: polybutadiene, crosslinking: urethane bond and urea bond, ionic group: COO) were prepared in the same manner as fine particles 1, except that a mixture of a salt formed by 2,2-bis(hydroxymethyl)propionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and triethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and water was used as an ionic chain extender, instead of a mixture of a salt formed by 2,2-bis(hydroxymethyl)propionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and triethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.) and water was used (the above mixture was obtained by dissolving the above 2,2-bis(hydroxymethyl)propionic acid (0.035 mol) and the above sodium hydroxide (0.035 mol) in 10 g of water beforehand). - Na + A dispersion 3 was prepared by dispersing (which has been introduced into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of the fine particles 3 in the entire dispersion 3 was 50% by mass. When microparticle 3 was observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 2 μm had aggregated to form aggregates with an average particle diameter of 20 μm, each containing multiple protrusions. In Example 3, the OH groups derived from sodium hydroxide used in preparing the above ionic chain extender are as shown in the "molar ratio" in column 3 of the dispersion. * In calculating the value, the active hydrogen-containing groups of the chain extender are not included.

[0088] (Example 4) Method for producing fine particles 4 Except for the absence of dimethylthiotoluenediamine, microparticle 4 was produced in the same manner as microparticle 1 (backbone: polybutadiene, crosslinking: urethane bond, ionic group: COO - and N + A dispersion 4 was prepared by dispersing the polymer (which is incorporated into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of the fine particles 4 in the entire dispersion 4 was 50% by mass. When the fine particles 4 were observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 10 μm had aggregated to form aggregates with an average particle diameter of 120 μm, each containing multiple protrusions.

[0089] (Example 5) Method for producing fine particles 5 Except for using 125.0g of carbodiimide-modified polyisocyanate (Millionate MTL, manufactured by Tosoh Corporation, NCO% 29.0%, average number of functional groups 2.0) instead of polymeric MDI as the polyisocyanate, fine particle 5 (backbone: polybutadiene, crosslinking: urethane bond and urea bond, ionic group: COO) was prepared in the same manner as fine particle 1. - and N + A dispersion 5 was prepared by dispersing (which has been introduced into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of the fine particles 5 in the entire dispersion 5 was 50% by mass. When the fine particles 5 were observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 0.1 μm had aggregated together, forming aggregates with an average particle diameter of 0.8 μm that had multiple protrusions.

[0090] (Example 6) Method for producing fine particles 6 Except for using a liquid butadiene polymer (unmodified butadiene polymer, LBR-305 manufactured by Kuraray Co., Ltd., number average molecular weight 26,000) instead of a liquid isoprene polymer as the unmodified diene polymer, fine particles 6 (backbone: polybutadiene, crosslinking: urethane bond and urea bond, ionic group: COO) were prepared in the same manner as fine particles 1. - and N + A dispersion 6 was prepared by dispersing (which has been introduced into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid butadiene polymer). The content of the fine particles 6 in the entire dispersion 6 was 50% by mass. When the fine particles 6 were observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 0.4 μm had aggregated to form aggregates with an average particle diameter of 2 μm, each containing multiple protrusions.

[0091] (Comparative Example 2) Method for producing comparative fine particles 2 Comparative dispersion 2 was prepared in the same manner as for fine particles 1, except that a mixture of water and a salt formed from 2,2-bis(hydroxymethyl)propionic acid and triethanolamine (ionic chain extender) was omitted, the amount of dimethylthiotoluenediamine was changed to 15 g, the amount of polymeric MDI was changed to 35 g, and the amount of liquid isoprene polymer was changed to 107.5 g. Comparative dispersion 2 was prepared by dispersing comparative fine particles 2 (backbone: polybutadiene, crosslinking: urethane and urea bonds, no ion introduction by ionic chain extender) in a liquid (dispersion medium containing the above liquid butadiene polymer). The content of comparative fine particles 2 in the entire comparative dispersion 2 was 50% by mass. When comparative particle 2 was observed using a scanning electron microscope in the same manner as described above, it was confirmed that perfectly spherical particles with an average particle diameter of 20 μm were being generated.

[0092] (Comparative Example 3) Method for producing comparative fine particles 3 Comparative microparticle 3 was prepared in the same manner as microparticle 1, except that the amount of polymeric MDI was changed to 65g and the amount of liquid isoprene polymer was changed to 150g (backbone: polybutadiene, crosslinking: urethane bond and urea bond, ionic group: COO - and N + A comparative dispersion 3 was prepared by dispersing the comparative fine particles (which are incorporated into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of comparative fine particles 3 in the entire comparative dispersion 3 was 50% by mass. When comparative fine particles 3 were observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 1 μm had aggregated to form aggregates with an average particle diameter of 15 μm, each containing multiple protrusions.

[0093] (Comparative Example 4) Method for producing comparative fine particles 4 Comparative microparticle 4 (backbone: polybutadiene, crosslinking: urethane and urea bonds, ionic group: COO) was prepared in the same manner as microparticle 1, except that the amount of polymeric MDI was changed to 350g and the amount of liquid isoprene polymer to 435g. - and N +A comparative dispersion 4 was prepared by dispersing the comparative fine particles (which are incorporated into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of the comparative fine particles 4 in the entire comparative dispersion 4 was 50% by mass. When comparative fine particles 4 were observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 0.5 μm had aggregated to form aggregates with an average particle diameter of 10 μm, each containing multiple protrusions.

[0094] (Example 9) Method for producing fine particles 7 Fine particles 7 (backbone: polybutadiene, crosslinking: urethane bond and urea bond, ionic group: COO) were prepared in the same manner as fine particles 1, except that a mixture of 5 g of a salt formed from 2,2-bis(hydroxymethyl)propionic acid (0.0175 mol, manufactured by Tokyo Chemical Industry Co., Ltd.) and triethanolamine (0.0175 mol, manufactured by Tokyo Chemical Industry Co., Ltd.) and 5 g of water was used as an ionic chain extender (the above mixture was obtained by first dissolving the above 2,2-bis(hydroxymethyl)propionic acid (0.0175 mol) and triethanolamine (0.0175 mol) in 5 g of water). - and N + A dispersion 7 was prepared by dispersing (which has been introduced into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of the fine particles 7 in the entire dispersion 7 was 50% by mass. When the fine particles 7 were observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 0.5 μm had aggregated to form aggregates with an average particle diameter of 2 μm, each containing multiple protrusions.

[0095] (Example 10) Method for producing fine particles 8 Microparticle 8 (backbone: polybutadiene, crosslinking: urethane bond and urea bond, ionic group: COO) was prepared in the same manner as microparticle 1, except that 15 g of a salt formed from 2,2-bis(hydroxymethyl)propionic acid (0.0525 mol, manufactured by Tokyo Chemical Industry Co., Ltd.) and triethanolamine (0.0525 mol, manufactured by Tokyo Chemical Industry Co., Ltd.) was used as an ionic chain extender (the above 15 g of salt was obtained by dissolving the above 2,2-bis(hydroxymethyl)propionic acid (0.0525 mol) and triethanolamine (0.0525 mol) in 15 g of water beforehand). - and N + A dispersion 8 was prepared by dispersing the polymer (which is incorporated into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of the fine particles 8 in the entire dispersion 8 was 50% by mass. When the fine particles 8 were observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 0.5 μm had aggregated to form aggregates with an average particle diameter of 20 μm, each containing multiple protrusions.

[0096] (Example 11) Method for producing fine particles 9 Except for using Rheodol TW-O320V (manufactured by Kao Corporation) as a nonionic surfactant instead of Niax silicone L-5111 (silicone-based surfactant), microparticle 9 (backbone: polybutadiene, crosslinking: urethane bond and urea bond, ionic group: COO) was prepared in the same manner as microparticle 1. - and N + A dispersion 9 was prepared by dispersing the polymer (which is incorporated into the polymer constituting these fine particles) in a liquid (a dispersion medium containing the above-mentioned liquid isoprene polymer). The content of the fine particles 9 in the entire dispersion 9 was 50% by mass. When the fine particles 9 were observed using a scanning electron microscope in the same manner as described above, it was confirmed that multiple primary particles with an average particle diameter of 0.8 μm had aggregated to form aggregates with an average particle diameter of 6 μm, each containing multiple protrusions.

[0097] [Manufacturing of rubber compositions] Each of the fine particles produced in the above examples was used in a rubber composition in the form of a dispersion. Each rubber composition was prepared by mixing the components shown in Table 1 in the proportions (parts by mass) indicated in the table using a stirrer. The amounts shown in the dispersion column of Table 1 represent the total amount of the dispersion, including the fine particles. In each dispersion prepared above, the fine particle content was 50% by mass of the total dispersion.

[0098] <Rating> The following evaluations were performed using each rubber composition manufactured as described above. The results are shown in Table 1. (Manufacturing of vulcanized rubber sheets) Each rubber composition manufactured as described above was vulcanized in a mold (internal dimensions: length 150 mm, width 150 mm, thickness 2 mm) at 170°C for 15 minutes to produce vulcanized rubber sheets.

[0099] (tanδ at 0°C and 60°C) The dynamic viscoelasticity of each vulcanized rubber sheet obtained as described above was measured using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd., with an initial strain of 10%, amplitude of ±2%, and frequency of 20 Hz, and tanδ was determined at temperatures of 0°C and 60°C. The tanδ result at a temperature of 0°C is shown as an exponent with the value of Standard Example 1 set to 100. The tanδ result at a temperature of 60°C is shown as an exponent using the reciprocal of the measured value, with the value of standard example 1 set to 100.

[0100] (Evaluation Criteria) • Fuel efficiency In this invention, when the index of tanδ(60°C) is 100 or greater, it means that tanδ(60°C) is small, resulting in low rolling resistance when used as a tire and excellent fuel efficiency. Furthermore, the greater the index is greater than 100, the better the fuel efficiency.

[0101] • Wet grip performance In this invention, if the index of tanδ(0℃) is 105 or higher, it means that tanδ(0℃) is large, and that the wet grip performance when made into a tire is excellent. Furthermore, the greater the index is greater than 105, the better the wet grip performance. On the other hand, if the tanδ(0℃) index was less than 105, the wet grip performance was evaluated as poor.

[0102] [Table 1]

[0103] [Table 2]

[0104] The details of each component shown in Table 1 are as follows: (Diene-based rubber) • SBR: Styrene-butadiene rubber, manufactured by Nippon Zeon Corporation, NIPOL1739 (Tg -39℃) (White filler) • Silica: Rhodia Zeosil 1165MP (Carbon Black) • Carbon Black: Tokai Carbon Co., Ltd. Seast 6

[0105] (fine particles) • Dispersions 1-9: Dispersions 1-9 manufactured as described above.

[0106] • Comparative microparticle 1: NH-RAS06 manufactured by Iwase Cosfa (containing polymethylsilsesquioxane and alumina microparticles) • Comparative Dispersion 2: Comparative dispersion 2 manufactured as described above. The comparative fine particles 2 contained in comparative dispersion 2 were manufactured without the use of an ionic chain extender. The comparative fine particles 2 are perfectly spherical. • Liquid isoprene polymer: Unmodified isoprene polymer. LIR-30 manufactured by Kuraray Co., Ltd., number average molecular weight 28,000. • Comparative dispersion 3: Comparative dispersion 3 manufactured as described above. • Comparative dispersion 4: Comparative dispersion 4 manufactured as described above.

[0107] • Silane coupling agent: Bis-(3-triethoxysilylpropyl)tetrasulfide, manufactured by Evonik, Si69 • Zinc oxide: Three types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd. • Stearic acid: NOF Corporation's Bead Stearic Acid YR • Anti-aging agent: Flexis Santoflex 6PPD • Sulfur: Finely powdered sulfur containing Kinka oil, manufactured by Tsurumi Chemical Industries Co., Ltd. • Vulcanization accelerator 1: Noxellar CZ-G manufactured by Ouchi Shinko Chemical Industry Co., Ltd. • Vulcanization accelerator 2: Soccinol DG manufactured by Sumitomo Chemical Co., Ltd.

[0108] As shown in Table 1, Comparative Example 1, in which the polymer constituting the fine particles was not polyurethane-based, exhibited poor fuel efficiency and wet grip performance. Comparative Example 2, which contained comparative fine particles 2, was manufactured without the use of an ionic chain extender, and the molar ratio of isocyanate groups in the polyisocyanate compound to the total amount of active hydrogen-containing groups in the hydroxyl group-containing diene polymer and the chain extender was outside the specified range. Comparative Example 2 exhibited poor fuel efficiency and had room for improvement in wet grip performance. Comparative Examples 3 or 4, which contained comparative fine particles 3 or 4 in which the molar ratio of isocyanate groups in the polyisocyanate compound to the total amount of active hydrogen-containing groups in the hydroxyl group-containing diene polymer and chain extender was outside a predetermined range during the production of the fine particles, exhibited poor fuel efficiency and wet grip performance.

[0109] In contrast to these, the rubber composition of the present invention, which contains the fine particles of the present invention, exhibits excellent fuel efficiency and wet grip performance. Therefore, the fine particles of the present invention were able to improve wet grip performance while maintaining the tire's excellent fuel efficiency. [Explanation of Symbols]

[0110] 1. Bead section 2 Sidewall section 3. Tire tread section 4. Carcass layer 5 Bead core 6. Bead Filler 7 Belt layer 8 Rim Cushion 10 Fine particles 12 Primary particles

Claims

1. A dispersion system containing an unmodified diene polymer, a nonionic or silicone surfactant, a hydroxyl group-containing diene polymer having a number average molecular weight of 1000 to 3000 and containing hydroxyl groups, and a chain extender containing an ionic chain extender, A polyisocyanate compound having multiple isocyanate groups is mixed, and in the mixing, the molar ratio of the isocyanate groups to the total amount of the hydroxyl groups and the active hydrogen-containing groups of the chain extender is 1.5 to 6.

0. A method for producing fine particles, comprising polymerizing the hydroxyl group-containing diene polymer, the chain extender, and the polyisocyanate compound.

2. The method for producing fine particles according to claim 1, wherein the average particle size of the fine particles is 0.1 to 200 μm.

3. The method for producing fine particles according to claim 1, wherein the fine particles are formed by the aggregation of a plurality of primary particles having an average particle diameter of 0.01 to 20 μm.

4. The method for producing fine particles according to claim 1, wherein the fine particles are produced as a dispersion dispersed in the unmodified diene polymer, and the content of the fine particles is 5 to 60% by mass of the dispersion.

5. The method for producing fine particles according to claim 1, wherein the fine particles have urethane bonds and urea bonds.

6. The method for producing fine particles according to claim 1, wherein the ionic chain extender comprises a carboxylate salt having multiple active hydrogen group-containing groups per molecule.

7. The method for producing fine particles according to claim 1, wherein the ionic chain extender includes a compound having an ionic group, obtained by combining a compound having multiple active hydrogen group-containing groups and a carboxyl group with a tertiary amine having multiple active hydrogen group-containing groups.

8. The method for producing fine particles according to claim 1, wherein the polyisocyanate compound comprises a polyisocyanate compound having an average number of functional groups of 2.1 or more.

9. Fine particles produced by the manufacturing method described in any one of claims 1 to 8.

10. A rubber composition for tires comprising a diene rubber, fine particles produced by the manufacturing method described in any one of claims 1 to 8, and a filler comprising at least one of carbon black and a white filler, wherein the content of the fine particles is 1 to 30 parts by mass per 100 parts by mass of the diene rubber, and the content of the filler is 30 to 100 parts by mass per 100 parts by mass of the diene rubber.

11. A tire manufactured using the tire rubber composition described in claim 10.

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