JP2020055951A - Filler/rubber composite - Google Patents

Abstract

To provide a filler/rubber composite excellent in dispersibility and productivity of a filler, and a manufacturing method thereof.SOLUTION: A filler/rubber composite is obtained from a blended latex with viscosity 100 mPa s or more, containing a rubber latex and a filler. In the filler/rubber composite, aggregates of 10 μm or more are 5.0% or less in aggregates 100% formed by the filler.SELECTED DRAWING: None

Description

The present invention relates to a filler / rubber composite, a method for producing the same, a rubber composition, and a tire having a tire member composed of the rubber composition.

It is known that by adding a microfibrillated plant fiber such as a cellulose fiber to a rubber composition as a filler, the rubber composition can be reinforced and the modulus (complex modulus) can be improved. Has strong self-cohesive force and poor compatibility with rubber components.

The aqueous dispersion of nanofibrillated microfibrillated plant fibers usually has a high viscosity. Therefore, in order to ensure good dispersibility of the microfibrillated vegetable fiber, an aqueous dispersion diluted and sufficiently reduced in viscosity is usually used to prepare a composite of the microfibrillated vegetable fiber and the rubber component (master batch). ) Is manufactured.

However, when a microfibrillated plant fiber aqueous dispersion diluted and sufficiently reduced in viscosity is used, since the solid content is low, waste liquid is large, productivity is low, and material transportation costs are increased. There is a need for improvement.

An object of the present invention is to solve the above problems and to provide a filler / rubber composite excellent in filler dispersibility and productivity, a method for producing the same, and the like.

The present invention relates to a filler / rubber composite obtained from a compounded latex having a viscosity of 100 mPa · s or more containing a rubber latex and a filler, wherein an aggregate of 10 μm or more is contained in 100% of aggregates formed by the filler. The present invention relates to a filler / rubber composite having 0% or less.

The filler / rubber composite preferably has a Mooney viscosity (ML1 + 4 (130 ° C.)) of 100 or less.

The filler is preferably at least one selected from the group consisting of microfibrillated plant fibers, short fibrous cellulose, and gel compounds.

The rubber latex is preferably at least one selected from the group consisting of isoprene-based rubber latex, styrene-butadiene rubber latex, and butadiene rubber latex.

The compounded latex preferably contains 1 to 30 parts by mass of a filler (solid content) based on 100 parts by mass of the rubber solid content in the rubber latex.

The present invention relates to a method for producing a filler / rubber composite, which includes a step 1 of mixing a rubber latex and a filler using a self-revolving type mixing apparatus to produce a compounded latex having a viscosity of 100 mPa · s or more.

The rotation-revolution type mixing device is preferably a rotation-revolution stirrer or a planetary mixer.

The present invention relates to a rubber composition containing the filler / rubber composite.
The present invention also relates to a tire having a tire member composed of the rubber composition.

According to the present invention, there is provided a filler / rubber composite obtained from a compounded latex having a viscosity of 100 mPa · s or more containing a rubber latex and a filler, wherein an aggregate of 10 μm or more is formed in 100% of the aggregate formed by the filler. Since the filler / rubber composite is 5.0% or less, the filler has excellent dispersibility and productivity.

(Filler / rubber composite)
The filler-rubber composite of the present invention is obtained from a compounded latex containing a rubber latex and a filler and having a viscosity of 100 mPa · s or more. 0.0% or less. The composite has excellent filler dispersibility and good productivity.

Although the reason why such an effect is obtained is not clear, it is supposed as follows.
Dispersions of difficult-to-disperse fillers such as microfibrillated plant fibers have a high viscosity, so they are usually used by diluting the dispersion and reducing the viscosity. However, there are problems such as low performance, large amount of waste liquid, and high transportation cost. On the other hand, for example, when a relatively high-viscosity (relatively high-concentration) dispersion obtained by mixing rubber latex and a relatively high-concentration hard-to-disperse filler is mixed using a self-revolving type mixing device or the like, the revolving and revolving Due to centrifugal force, rotation, shearing, etc., even if the dispersion has a relatively high viscosity, the filler is sufficiently dispersed in the rubber, good filler dispersibility is obtained, and the size of the aggregate formed by the filler is It is presumed that a filler / rubber composite (master batch) having as little as 10% or more and 5.0% or less is prepared. Therefore, according to the present invention, it is presumed that a filler-rubber composite excellent in filler dispersibility can be provided while obtaining good productivity, low waste liquid property, and low cost.

In the filler-rubber composite, the ratio of aggregates having a size of 10 μm or more to 5.0% or less (5.0% or less) among 100% (100% by mass) of the aggregates formed by the filler in the composite is set. % By mass). Therefore, the dispersibility of the filler is excellent. The aggregate having a size of 10 μm or more is preferably at most 4.5% by mass, more preferably at most 3.5% by mass. The lower limit is not particularly limited, and the smaller the aggregate, the better.

In the present specification, the size of the aggregate formed by the filler in the filler / rubber composite can be measured by image analysis using a scanning electron micrograph, image analysis using a transmission electron micrograph, or the like. The size of the aggregate is an average value of the size of the aggregate observed in a scanning electron microscope photograph, a transmission electron microscope photograph, or the like. If the shape of the agglomerate is spherical, the diameter of the sphere is the size of the agglomerate.If the shape is a needle or rod, the minor diameter is the size of the agglomerate. The particle size is the size of the agglomerate.

The filler / rubber composite preferably has a Mooney viscosity (ML1 + 4, 130 ° C.) of 100 or less from the viewpoint of processability, filler dispersibility, and the like. It is more preferably at most 80, more preferably at most 65. In light of the physical properties of the rubber composition, the Mooney viscosity is preferably equal to or greater than 40, more preferably equal to or greater than 45, and still more preferably equal to or greater than 50.
The Mooney viscosity (ML1 + 4, 130 ° C.) can be measured by a method based on JIS K6300-1.

Here, as a method for satisfying the content of the agglomerate having a size of 10 μm or more and the Mooney viscosity, (a) a method of mixing using a self-revolving mixing device, (b) a rubber latex, a filler dispersion , A method of mixing an appropriate amount of a rubber latex and a filler, and a method of mixing a surfactant (d) alone or as appropriate.

The filler-rubber composite is produced using a compounded latex containing a rubber latex and a filler and having a viscosity of 100 mPa · s or more.

Examples of the rubber latex include isoprene-based rubber latex (natural rubber latex, modified natural rubber latex (saponified natural rubber latex, epoxidized natural rubber latex, etc.), isoprene rubber latex, etc.); butadiene rubber latex, styrene butadiene rubber Latex, styrene isoprene butadiene rubber latex, butyl rubber latex; and the like can be suitably used. These rubber latexes may be used alone or in combination of two or more. Among them, natural rubber latex, SBR latex, BR latex, and isoprene rubber latex are more preferable, and natural rubber latex is particularly preferable.

Natural rubber latex is collected as the sap of natural rubber trees such as Hevea trees, and contains water, proteins, lipids, inorganic salts, etc. in addition to rubber components, and the gel component in rubber is based on the complex presence of various impurities Is believed to be something. In the present invention, as natural rubber latex, raw latex (field latex) which is obtained by tapping a Hevea tree, concentrated latex concentrated by centrifugation or creaming (purified latex, high ammonia latex to which ammonia is added by a conventional method) And LATZ latex stabilized by zinc white, TMTD and ammonia.

Here, the pH of the rubber latex is preferably 8.5 or more, more preferably 9.5 or more. When the pH is 8.5 or more, the rubber latex is less likely to be unstable and hardly coagulates. The rubber latex preferably has a pH of 12 or less, more preferably 11 or less. When the pH is 12 or less, the rubber latex tends to hardly deteriorate.

The rubber latex can be prepared by a conventionally known production method, and various commercially available products can also be used. It is preferable to use a rubber latex having a rubber solid content of 10 to 80% by mass. More preferably, it is 20% by mass or more and 60% by mass or less.

As the filler, a filler used at the time of its use can be appropriately compounded according to the field of application, but generally a fibrous filler that is difficult to disperse in rubber can also be suitably used, for example, microfibrillated vegetable fiber, short fiber Hardly dispersible fillers such as cellulosic cellulose and gel compounds can also be suitably applied. Among them, microfibrillated plant fibers are preferred from the viewpoint of the physical properties of the obtained composite.

As the microfibrillated plant fiber, cellulose microfibril is preferable from the viewpoint that good reinforcing properties can be obtained. Cellulose microfibrils are not particularly limited as long as they are derived from natural products.For example, fruits, cereals, resource biomass such as root vegetables, wood, bamboo, hemp, jute, kenaf, and pulp obtained using these as raw materials Waste biomass such as paper, cloth, crop residue, food waste and sewage sludge, unused biomass such as rice straw, straw, and thinned wood, as well as those derived from cellulose produced by sea squirts, acetic acid bacteria, etc. Can be One type of these microfibrillated plant fibers may be used, or two or more types may be used in combination.

In addition, in this specification, a cellulose microfibril is typically a cellulose fiber having an average fiber diameter within a range of 10 μm or less, more typically, an average fiber diameter formed by aggregation of cellulose molecules. It means a cellulose fiber having a microstructure of 500 nm or less. A typical cellulose microfibril can be formed, for example, as an aggregate of cellulose fibers having the above average fiber diameter.

The method for producing the microfibrillated plant fiber is not particularly limited. For example, after the cellulose microfibril raw material is chemically treated with an alkali such as sodium hydroxide as necessary, a refiner, a twin-screw kneader (a twin-screw kneader) is used. Extruder), a twin-screw kneading extruder, a high-pressure homogenizer, a medium stirring mill, a stone mill, a grinder, a vibration mill, a sand grinder, and the like, and a method of mechanically grinding or beating. In these methods, since lignin is separated from the raw material by the chemical treatment, a microfibrillated plant fiber substantially free of lignin is obtained. Further, as another method, a method of subjecting the raw material of the cellulose microfibril to an ultra-high pressure treatment and the like can be mentioned.

As the microfibrillated plant fiber, for example, products such as Sugino Machine Co., Ltd. can be used.

As the microfibrillated plant fibers, those obtained by the above-mentioned production method, further subjected to an oxidation treatment or various chemical modification treatments, or natural products that can be derived from the cellulose microfibrils (for example, Wood, pulp, bamboo, hemp, jute, kenaf, agricultural waste, cloth, paper, squirt cellulose, etc.) are used as the cellulose material and subjected to oxidation treatment and various chemical modification treatments, and then defibration treatment as necessary Can also be used. For example, microfibrillated plant fibers that have been subjected to an oxidation treatment can be suitably used.

As an embodiment of the oxidation treatment, for example, an oxidation treatment using an N-oxyl compound is exemplified. The oxidation treatment using the N-oxyl compound can be performed, for example, by a method in which the N-oxyl compound is used as an oxidation catalyst in water and a co-oxidizing agent acts on the microfibrillated plant fiber. Examples of the N-oxyl compound include 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and derivatives thereof. Examples of the co-oxidizing agent include sodium hypochlorite and the like.

The average fiber diameter of the microfibrillated plant fiber is preferably 10 μm or less. When the content is in the above range, the dispersibility of the microfibrillated plant fibers in the rubber can be improved. In addition, breakage of the microfibrillated plant fibers during processing tends to be suppressed. The average fiber diameter is more preferably 500 nm or less, further preferably 100 nm or less, and particularly preferably 50 nm or less. Although the lower limit of the average fiber diameter is not particularly limited, it is preferably 4 nm or more, more preferably 10 nm or more, and still more preferably 20 nm or more, because the entanglement of the microfibrillated plant fiber is difficult to disperse and difficult to disperse.

The average fiber length of the microfibrillated plant fiber is preferably 100 nm or more, more preferably 300 nm or more, and further preferably 500 nm or more. Further, it is preferably 5 mm or less, more preferably 1 mm or less, further preferably 50 μm or less, particularly preferably 3 μm or less, and most preferably 2 μm or less. When the average fiber length is less than the lower limit or exceeds the upper limit, there is a tendency similar to the above-mentioned average fiber diameter.

In addition, when the said microfibrillated vegetable fiber consists of 2 or more types of combinations, the said average fiber diameter and the said average fiber length are calculated as an average in the whole microfibrillated vegetable fiber.

In the present specification, the average fiber diameter and average fiber length of the microfibrillated plant fiber are determined by image analysis using a scanning electron micrograph, image analysis using a transmission electron micrograph, image analysis using an atomic force micrograph, X-ray It can be measured by analysis of scattering data, pore electric resistance method (Coulter principle method) and the like.

Since the short fibrous cellulose has good dispersibility in rubber, it can be maintained or improved without deteriorating the breaking strength of rubber, and rubber physical properties become good.

The fiber width of the short fibrous cellulose is preferably 3 to 200 μm. Usually, the fibrous filler compounded in the rubber composition is preferable in terms of rubber reinforcing property as the fiber width is smaller, while the fibrous filler having a smaller fiber width tends to be hardly oriented. From the viewpoint of the balance between the reinforcing properties and the orientation of the fibers, and further from the viewpoint of the dispersibility in the rubber, the fiber width is preferably at least 10 μm, more preferably at least 15 μm, even more preferably at least 20 μm. Moreover, it is preferably 120 μm or less, more preferably 80 μm or less, and still more preferably 50 μm or less.

The short fibrous cellulose preferably has a fiber length of 20 to 1000 μm. As with the fiber width, the fiber length is preferably 50 μm or more, more preferably 100 μm or more, and more preferably 200 μm or more, from the viewpoint of the balance between the reinforcing properties of rubber and the orientation of the fibers, and further from the viewpoint of dispersibility in rubber. Is more preferred. Further, it is preferably 700 μm or less, more preferably 500 μm or less.

The short fibrous cellulose preferably has a ratio of fiber width to fiber length (fiber length / fiber width) of 5 to 1,000. Similarly to the fiber width, the ratio between the fiber width and the fiber length is preferably 6 or more, more preferably 10 or more, from the viewpoint of the balance between the reinforcing property of rubber and the orientation of the fiber. Further, it is preferably 800 or less, more preferably 500 or less, further preferably 400 or less, and particularly preferably 300 or less.

The fiber width and fiber length of the short fibrous cellulose are determined by image analysis of a scanning atomic force micrograph, image analysis of a scanning electron micrograph, image analysis of a transmission micrograph, analysis of X-ray scattering data, pore analysis. It can be measured by the electric resistance method (the Coulter principle method) or the like.

The gel compound is a substance obtained by gelling microfibrillated plant fibers or short fibrous cellulose. Even when such a gel is used, the gel compound can be dispersed well. The method of gelation is not particularly limited, and examples thereof include a method of stirring using an ultra-high pressure homogenizer or the like.

The filler may be mixed with rubber latex in the form of a dispersion liquid (filler dispersion liquid, slurry) dispersed in a solvent, or after replacing the filler dispersion liquid with ethanol or the like, followed by mixing with rubber latex. Alternatively, the filler may be directly mixed with the rubber latex. The solvent in the filler dispersion is not particularly limited, and includes water and the like. Among them, from the viewpoint of filler dispersibility, it is preferable to use a filler dispersion in which a filler is dispersed in a solvent such as water.

The filler dispersion can be manufactured by a known method, and the manufacturing method is not particularly limited.For example, a high-speed homogenizer, an ultrasonic homogenizer, a colloid mill, a blender-mill, an electronically controlled stirrer, and the like are used to reduce the filler to water or the like. Can be prepared by dispersing in a solvent. The temperature and time for the preparation can also be appropriately set within the range usually performed so that the filler is sufficiently dispersed in a solvent such as water.

The content (solid content) of the filler in the filler dispersion is not particularly limited, but from the viewpoint of filler dispersibility, a low concentration is preferable, while from the viewpoint of productivity, transportation cost, and the like, a high concentration is used. Preferably, there is. In the present invention, good dispersibility can be obtained by using a high-concentration dispersion instead of the conventional dispersion of about 1% by mass. Therefore, the content is preferably 0.5 to 20% by mass, more preferably 1.5 to 15% by mass, and still more preferably 2.0 to 10% by mass from the viewpoint of productivity and filler dispersibility. .

The compounded latex containing the rubber latex and the filler has a viscosity of 100 mPa · s or more. Thereby, transportation costs and the like can be reduced, and productivity can be improved. The viscosity is preferably at least 200 mPa · s, more preferably at least 250 mPa · s. The lower limit is not particularly limited, but is preferably 1500 mPa · s or less, more preferably 1000 mPa · s or less, and still more preferably 800 mPa · s or less from the viewpoint of filler dispersibility and the like.
The viscosity of the compounded latex is a value measured by a tuning fork vibrating viscometer under a condition of 23 ° C.

Here, as a method of satisfying the viscosity of the compounded latex, (a) a method of mixing using a self-revolving type mixing device, (b) a method of using a rubber latex, a filler dispersion, (c) a rubber latex, a filler , And (d) a method of blending a surfactant, alone or as appropriate.

The filler / rubber composite is obtained from the compounded latex, and may contain other components as long as the effect is not impaired.

The filler / rubber composite is obtained from a compounded latex having a viscosity of 100 mPa · s or more containing a rubber latex and a filler. For example, a rubber latex and a filler are mixed to prepare a compounded latex having a viscosity of 100 mPa · s or more. It can be manufactured by a manufacturing method including a step (1). According to such a production method, a master batch in which a filler is finely and highly dispersed in rubber can be obtained.

(Step (1))
In the step (1), the mixing of the rubber latex and the filler is not particularly limited as long as the rubber latex and the filler are mixed, and the rubber latex, a binder other than the filler, and a surfactant Other compounding agents may be further added. Above all, from the viewpoint of filler dispersibility, it is preferable to add a surfactant, and in particular, a method of mixing and dispersing the above-mentioned filler and surfactant, and then mixing with the above-mentioned rubber latex is preferable.

Examples of the surfactant include a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and the like, and it is preferable to use an anionic surfactant.

The anionic surfactant is a surfactant having a hydrophobic group and a hydrophilic group. By using such a surfactant, the hydrophobic group and the hydrophobic group of the rubber form a hydrophobic-hydrophobic bond to show an affinity, and the hydrophilic group and the hydroxyl group of the microfibrillated plant fiber are combined. In order to show affinity by adsorption through hydrogen bonding, it is necessary to increase the dispersibility of the microfibrillated plant fiber, suppress the aggregation of the microfibrillated plant fiber in rubber, and suppress the occurrence of aggregates. It is presumed that it can be done. As the anionic surfactant, one kind may be used, or two or more kinds may be used in combination.

The hydrophobic group may be any hydrophobic functional group, and among them, a hydrocarbon group is preferred. The hydrocarbon group may be linear, branched, or cyclic, and examples thereof include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Among them, an aliphatic hydrocarbon group and an aromatic hydrocarbon group are preferred. The hydrocarbon group preferably has 4 to 20, more preferably 4 to 15, and even more preferably 4 to 12, carbon atoms.

The aliphatic hydrocarbon group preferably has 1 to 20 carbon atoms, more preferably has 1 to 10 carbon atoms, and still more preferably has 1 to 6 carbon atoms. Preferred examples include an alkyl group having the above number of carbon atoms. Specifically, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert- Butyl, pentyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, octadecyl and the like. Further, alkenyl groups and alkynyl groups having the above carbon number are also exemplified.Examples include alkynyl groups such as vinyl group, allyl group, 1-propenyl group, 1-methylethenyl group and isobutylene group, alkynyl groups such as ethynyl group and propargyl group. Groups. Among them, an isobutylene group is preferred.

The alicyclic hydrocarbon group is preferably one having 3 to 8 carbon atoms, specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclopropenyl group, Examples include a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a cyclooctenyl group, and the like.

The aromatic hydrocarbon group preferably has 6 to 12 carbon atoms, and specific examples thereof include a phenyl group, a benzyl group, a phenethyl group, a tolyl group, a xylyl (xylyl) group, and a naphthyl group. Can be Of these, a phenyl group, a benzyl group and a phenethyl group are preferred, a phenyl group and a benzyl group are more preferred, and a phenyl group is particularly preferred. The substitution position of the methyl group on the benzene ring in the tolyl group and the xylyl group may be any of the ortho, meta and para positions.

The hydrophilic group is preferably at least one selected from the group consisting of a carboxyl group, a sulfonic group, a sulfate group, and a phosphate group. Among them, a carboxyl group is particularly preferred.

Among the above anionic surfactants, anionic surfactants having a phenyl group or an isobutylene group as a hydrophobic group and a carboxyl group as a hydrophilic group are particularly preferable.

Examples of the anionic surfactant include those having a functional group as described above in a preferred form. Specifically, carboxylic acid-based, sulfonic acid-based, sulfate-based, phosphate-based, and the like. It can be classified as a surfactant.

Examples of the carboxylic acid-based surfactant include a fatty acid salt having 6 to 30 carbon atoms, a polyvalent carboxylate, a rosinate, a dimer acid salt, a polymer acid salt, a tall oil fatty acid salt, and a polycarboxylic acid type. Polymeric surfactants and the like, preferably carboxylic acid salts having 10 to 20 carbon atoms, polycarboxylates, polycarboxylic acid type polymer surfactants, particularly preferably polycarboxylic acid type polymer surfactants Agent.
Examples of the sulfonic acid-based surfactant include an alkyl benzene sulfonate, an alkyl sulfonate, an alkyl naphthalene sulfonate, a naphthalene sulfonate, and a diphenyl ether sulfonate.
Examples of the sulfate-based surfactant include alkyl sulfate, polyoxyalkylene alkyl sulfate, polyoxyalkylene alkylphenyl ether sulfate, tristyrenated phenol sulfate, and distyrenated phenol sulfate. Examples thereof include ester salts, α-olefin sulfate esters, alkyl succinate sulfate salts, polyoxyalkylene tristyrenated phenol sulfate salts, and polyoxyalkylenedistyrenated phenol sulfate salts.
Examples of the phosphate ester-based surfactant include an alkyl phosphate ester salt and a polyoxyalkylene phosphate ester salt.
Examples of salts of these compounds include metal salts (Na, k, Ca, Mg, Zn, etc.), ammonium salts, amine salts (triethanolamine salts, etc.).

In addition, as an alkyl group in the said surfactant, a C4-C30 alkyl group is mentioned. Examples of the polyoxyalkylene group include those having an alkylene group having 2 to 4 carbon atoms. For example, those having an addition mole number of ethylene oxide of about 1 to 50 mol can be used.

The anionic surfactant preferably has a weight average molecular weight (Mw) of 500 or more, more preferably 1,000 or more. Further, it is preferably at most 50,000, more preferably at most 30,000.

As the above-mentioned anionic surfactant, for example, products such as ELEMENTIS, Kao Corporation, Daiichi Kogyo Seiyaku Co., Ltd. and Sanyo Chemical Industries, Ltd. can be used.

As a method of mixing the rubber latex, the filler (a filler dispersion or the like), and a surfactant as necessary, a method of mixing using a self-revolving mixing device is preferable from the viewpoint of filler dispersibility. In the present specification, the rotation-revolution type mixing device is a mixing device provided with both a rotation mechanism and a rotation mechanism, and examples thereof include a rotation-revolution stirrer and a planetary mixer.

A rotation revolving stirrer is a device that stirs a material by revolving and rotating the container in which the material is placed. Sufficient mixing is possible due to the centrifugal force, shear force, etc. caused by revolving and rotating the container. For example, a stirrer described in Japanese Patent Application Laid-Open No. 2015-52034 can be mentioned, and as a commercially available product, “Rotating / Rotating Mixer Awatori Rentaro ARE-310” manufactured by Shinky Corporation can be mentioned.

The planetary mixer is a planetary mixer having a blade (stirring blade) having a rotation function and a revolution function as a stirring mechanism.

In the rotation revolving stirrer and the planetary mixer, the rotation speed and the revolving speed may be appropriately set within a range in which good mixing can be realized in consideration of the materials used, the blending amount, and the like.

The temperature and time for mixing the rubber latex, the filler, and, if necessary, the surfactant may be appropriately set in consideration of the dispersion state and the like. The mixing temperature is not particularly limited and may be appropriately set, but is preferably 10 to 40 ° C, more preferably 15 to 30 ° C. The mixing time is not particularly limited, and may be set as appropriate. For example, the mixing time can be 1 to 120 minutes, but from the viewpoint of productivity, 1 to 10 minutes is preferable, and 2 to 8 minutes is more preferable. .

In preparing the compounded latex, it is preferable to mix the rubber latex and the filler such that the filler (solid content) is 1 to 30 parts by mass with respect to 100 parts by mass of the rubber solids. When the content is in the above range, good filler dispersibility and rubber properties tend to be obtained. The content of the filler (solid content) is more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more. Further, the amount is preferably 27 parts by mass or less, more preferably 25 parts by mass or less.

A compounded latex (mixture) having a viscosity of 100 mPa · s or more obtained by mixing with a self-revolution type mixing device is coagulated as necessary, and the coagulated material (agglomerated material containing agglomerated rubber and filler) is filtered by a known method. When the rubber is dried and further kneaded with a biaxial roll, a Banbury or the like, a composite (filler / rubber composite) in which the filler is sufficiently dispersed in the rubber matrix can be obtained. The filler-rubber composite may include other components.

The coagulation is usually performed by adding an acid to the obtained compounded latex. Examples of the acid for coagulation include sulfuric acid, hydrochloric acid, formic acid, and acetic acid. The temperature at the time of solidification is preferably from 10 to 40C.

At the time of the coagulation, the pH of the obtained compounded latex is preferably adjusted to 3 to 5, more preferably 3 to 4.

Further, a coagulant may be added for the purpose of controlling the state of coagulation (the size of coagulated coagulated particles). As the flocculant, a cationic polymer or the like can be used.

The obtained filler / rubber composite can be used as a masterbatch. In the filler / rubber composite, the filler is sufficiently dispersed in the rubber, and the filler can be sufficiently dispersed even in a rubber composition mixed with other components. Therefore, excellent filler dispersibility, good tensile properties (tensile strength, elongation at break), and low fuel consumption can be obtained.

(Rubber composition)
The filler / rubber composite can be used as a master batch. For example, a rubber composition containing the filler / rubber composite can be applied to various uses. In the filler / rubber composite, the filler is sufficiently dispersed in the rubber, and the filler can be sufficiently dispersed even in a rubber composition mixed with other components. Therefore, effective reinforcing properties can be exhibited, and rubber properties such as durability (breaking strength), steering stability, and fuel economy can be improved in a well-balanced manner.

The rubber composition may include a rubber component other than the rubber (rubber component) used in the filler / rubber composite. As the other rubber component, for example, a diene rubber can be used. Examples of the diene rubber include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). ). Examples of the rubber component other than those described above include butyl rubber and fluoro rubber. These may be used alone or in combination of two or more. As the rubber component, SBR, BR, isoprene rubber is preferable.

In this specification, Mw and number average molecular weight (Mn) are gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: manufactured by Tosoh Corporation) (TSKGEL SUPERMULTIPORE HZ-M) in standard polystyrene conversion.

The other rubber component may be a non-modified diene rubber or a modified diene rubber.
The modified diene rubber may be any diene rubber having a functional group that interacts with a filler such as silica. For example, a compound having at least one terminal of the diene rubber having the above functional group (modifier) Terminal-modified diene rubber (terminal-modified diene rubber having the above functional group at the terminal), main chain modified diene rubber having the above functional group at the main chain, or the above functional group at the main chain and terminal Having a main chain terminal modified diene rubber (for example, a main chain terminal modified diene rubber having the functional group in the main chain and at least one terminal modified with the modifying agent) or two or more in the molecule. Modified (coupled) with a polyfunctional compound having an epoxy group, and a terminal-modified diene rubber into which a hydroxyl group or an epoxy group has been introduced may be mentioned.

Examples of the functional group include, for example, amino group, amide group, silyl group, alkoxysilyl group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide Group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group and the like. . Note that these functional groups may have a substituent. Among them, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an alkoxysilyl group ( Preferably, it is a C1-C6 alkoxysilyl group).

The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), and the like can be used. These may be used alone or in combination of two or more.

The styrene content of the SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less. When the content is within the above range, the above-mentioned effect can be more suitably obtained.
In addition, in this specification, the styrene content of SBR is calculated by H ¹ -NMR measurement.

As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd. and the like can be used.

The SBR may be an unmodified SBR or a modified SBR. Examples of the modified SBR include a modified SBR into which a functional group similar to that of the modified diene rubber is introduced.

When SBR is contained, the content of SBR in 100% by mass of the rubber component is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, from the viewpoint of wet grip performance and the like.

The BR is not particularly limited, and for example, a high cis BR having a high cis content, a BR containing a syndiotactic polybutadiene crystal, a BR synthesized using a rare earth catalyst (rare earth BR), and the like can be used. These may be used alone or in combination of two or more. Among them, high cis BR having a cis content of 90% by mass or more is preferable because the abrasion resistance is improved.

The BR may be a non-modified BR or a modified BR. Examples of the modified BR include a modified BR into which a functional group similar to that of the modified diene rubber has been introduced.

When BR is contained, the content of BR in 100% by mass of the rubber component is preferably from 10 to 90% by mass, more preferably from 20 to 80% by mass, from the viewpoint of abrasion resistance and the like.

As the BR, for example, products such as Ube Industries, Ltd., JSR Corp., Asahi Kasei Corp., and Zeon Corp. can be used.

Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. As the NR, for example, SIR20, RSS # 3, TSR20, and the like generally used in the rubber industry can be used. The IR is not particularly limited, and for example, a general IR in the rubber industry such as IR2200 can be used. Modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR), and modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

When the isoprene-based rubber is contained, the content of the isoprene-based rubber in 100% by mass of the rubber component is preferably from 10 to 90% by mass, more preferably from 20 to 80% by mass from the viewpoint of low fuel consumption.

In the rubber composition, the content of the filler (the total content of the filler) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component, from the viewpoint of rubber physical properties. More preferably 15 parts by mass or more. Further, from the viewpoint of filler dispersibility and the like, 150 parts by mass or less is preferable, 120 parts by mass or less is more preferable, and 100 parts by mass or less is further preferable.

In the rubber composition, the total content of the microfibrillated plant fibers, short fibrous cellulose, and gel compound is preferably 1 part by mass or more based on 100 parts by mass of the rubber component from the viewpoint of rubber physical properties. 5 parts by mass or more is more preferable, and 10 parts by mass or more is further preferable. From the viewpoint of filler dispersibility and the like, the content is preferably 45 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. In addition, when using microfibrillated plant fiber, the content is preferably in the same range.

The rubber composition may include silica as a filler from the viewpoint of various rubber properties. Examples of the silica include dry silica (anhydrous silica) and wet silica (hydrous silica). Among them, wet method silica is preferred because it has many silanol groups. Commercially available products such as Degussa Co., Rhodia Co., Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd. and Tokuyama Co., Ltd. can be used. These may be used alone or in combination of two or more.

The content of silica is preferably at least 25 parts by mass, more preferably at least 30 parts by mass, even more preferably at least 50 parts by mass with respect to 100 parts by mass of the rubber component. By setting the lower limit or more, good wet grip performance and steering stability tend to be obtained. The upper limit of the content is not particularly limited, but is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, still more preferably 170 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 80 parts by mass or less. is there. When the content is not more than the upper limit, good dispersibility tends to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 70 m ² / g or more, more preferably 140 m ² / g or more, and further preferably 160 m ² / g or more. By setting the lower limit or more, good wet grip performance and good breaking strength tend to be obtained. The upper limit of N ₂ SA of silica is not particularly limited, but is preferably 500 m ² / g or less, more preferably 300 m ² / g or less, and further preferably 250 m ² / g or less. When the content is not more than the upper limit, good dispersibility tends to be obtained.
The N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-93.

When the rubber composition contains silica, it is preferable that the rubber composition further contains a silane coupling agent.
The silane coupling agent is not particularly limited and includes, for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilyl) B) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, Sulfides such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, NXT manufactured by Momentive, and mercapto such as NXT-Z; vinyltriethoxysilane; vinyl Vinyl-based such as trimethoxysilane, amino-based such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycid Glycidoxy type such as cypropyltrimethoxysilane, nitro type such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, and chloro type such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane And so on. Commercially available products such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Amax Co., Ltd. and Dow Corning Toray Co., Ltd. can be used. These may be used alone or in combination of two or more.

The content of the silane coupling agent is preferably at least 3 parts by mass, more preferably at least 6 parts by mass, per 100 parts by mass of silica. When the amount is 3 parts by mass or more, good breaking strength and the like tend to be obtained. The content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. When the amount is 20 parts by mass or less, there is a tendency that an effect commensurate with the amount is obtained.

The rubber composition preferably contains carbon black as a filler from the viewpoint of various rubber properties. In addition, the use of carbon black tends to increase the rubber viscosity, increase the shear, and improve the filler dispersibility.

Although it does not specifically limit as carbon black, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. are mentioned. Commercially available products include products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin Nikka Carbon Co., Ltd. and Columbia Carbon Co., Ltd. it can. These may be used alone or in combination of two or more.

The content of carbon black is preferably at least 1 part by mass, more preferably at least 3 parts by mass, based on 100 parts by mass of the rubber component. By setting the lower limit or more, good abrasion resistance, grip performance, and the like tend to be obtained. Further, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. When the content is equal to or less than the upper limit, good processability of the rubber composition tends to be obtained.

Nitrogen adsorption specific surface area _(N 2 SA) of carbon black is preferably not less than ^{50 m} 2 / g, more preferably at least ^{80m 2 / g, 100m 2 /} g or more is more preferable. By setting the lower limit or more, good abrasion resistance and grip performance tend to be obtained. Further, the N ₂ SA is preferably at most 200 m ² / g, more preferably at most 150 m ² / g, even more preferably at most 130 m ² / g. When the content is not more than the upper limit, good dispersion of carbon black tends to be obtained.
The nitrogen adsorption specific surface area of carbon black is determined according to JIS K6217-2: 2001.

The rubber composition may contain a filler other than silica and carbon black. Other fillers include calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica and the like.

The rubber composition may include a plasticizer. Although it does not specifically limit as a plasticizer, The material which has liquid plasticity at 25 degreeC, such as an oil and a liquid resin, is mentioned. These plasticizers may be used alone or in combination of two or more.

The oil is not particularly limited, and includes process oils such as paraffin-based process oils, aroma-based process oils, and naphthene-based process oils, low PCA (polycyclic aromatic) process oils such as TDAE and MES, vegetable oils and fats, and Conventionally known oils such as mixtures thereof can be used. Above all, an aroma-based process oil is preferable in terms of wear resistance and breaking characteristics. Specific examples of the aroma-based process oil include Diana Process Oil AH series manufactured by Idemitsu Kosan Co., Ltd.

The liquid resin is not particularly limited, but examples thereof include a liquid aromatic vinyl polymer, a coumarone indene resin, an indene resin, a terpene resin, a rosin resin, and hydrogenated products thereof.

The liquid aromatic vinyl polymer is a resin obtained by polymerizing α-methylstyrene and / or styrene, and is a homopolymer of styrene, a homopolymer of α-methylstyrene, or a copolymer of α-methylstyrene and styrene. A liquid resin such as a copolymer may be used.

Liquid cumarone indene resin is a resin containing coumarone and indene as the main monomer components constituting the skeleton (main chain) of the resin, and as the monomer components that may be contained in the skeleton other than cumarone and indene, Styrene, α-methylstyrene, methylindene, vinyltoluene and the like.

The liquid indene resin is a liquid resin containing indene as a main monomer component constituting a skeleton (main chain) of the resin.

A liquid terpene resin is a liquid represented by terpene phenol which is a resin obtained by polymerizing a terpene compound such as α-pinene, β-pinene, camfer and dipetene, or a resin obtained by using a terpene compound and a phenolic compound as raw materials. It is a terpene resin.

The liquid rosin resin is a liquid rosin resin represented by natural rosin, polymerized rosin, modified rosin, their ester compounds, or hydrogenated products thereof.

The rubber composition may contain a solid resin (solid state polymer at normal temperature (25 ° C.)).

When a solid resin is contained, the content is preferably at least 1 part by mass, more preferably at least 3 parts by mass, and still more preferably at least 5 parts by mass, based on 100 parts by mass of the rubber component. Further, the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 20 parts by mass or less. When the content is in the above range, good wet grip performance tends to be obtained.

Although it does not specifically limit as a solid resin, For example, a solid styrene resin, a coumarone indene resin, a terpene resin, a pt-butylphenol acetylene resin, an acrylic resin, a dicyclopentadiene resin (DCPD resin) , C5 petroleum resin, C9 petroleum resin, C5C9 petroleum resin, and the like. These may be used alone or in combination of two or more.

The solid styrene resin is a solid polymer using a styrene monomer as a constituent monomer, and examples thereof include a polymer obtained by polymerizing a styrene monomer as a main component (50% by mass or more). Specifically, styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.), in addition to a homopolymer, a copolymer obtained by copolymerizing two or more styrene monomers, and a styrene monomer. And copolymers of other monomers copolymerizable therewith.

Examples of the other monomers include acrylonitrile, acrylonitriles such as methacrylonitrile, acrylics, unsaturated carboxylic acids such as methacrylic acid, unsaturated carboxylic esters such as methyl acrylate and methyl methacrylate, chloroprene, butadiene. Examples include dienes such as isoprene, olefins such as 1-butene and 1-pentene; α, β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof.

Among them, solid α-methylstyrene resins (α-methylstyrene homopolymer, copolymers of α-methylstyrene and styrene, etc.) are preferred.

Examples of the solid-state coumarone indene resin include a solid resin having the same structural unit as the above-mentioned liquid state coumarone indene resin.

Examples of the solid terpene-based resin include polyterpenes, terpene phenols, and aromatic modified terpene resins.
Polyterpenes are resins obtained by polymerizing terpene compounds and hydrogenated products thereof. Terpene compounds are hydrocarbons represented by the composition of (C ₅ H ₈ ) _n and oxygen-containing derivatives thereof, and are monoterpenes (C ₁₀ H ₁₆ ), sesquiterpenes (C ₁₅ H ₂₄ ), and diterpenes (C ₂₀ H _32). And the like. For example, α-pinene, β-pinene, dipentene, limonene, myrcene, allocymene, ocimene, α-pherandrene, α-terpinene, γ-terpinene, terpinolene , 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, and the like.

Examples of the solid polyterpene include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, β-pinene / limonene resin, and the like, which are obtained by hydrogenating the terpene resin. Solid resins such as treated hydrogenated terpene resins are also included.

Examples of the solid terpene phenol include a solid resin obtained by copolymerizing the terpene compound and a phenol compound, and a solid resin obtained by subjecting the resin to a hydrogenation treatment.Specifically, the terpene compound, the phenol compound, A solid resin obtained by condensing formalin is used. In addition, as a phenol compound, phenol, bisphenol A, cresol, xylenol, etc. are mentioned, for example.

Examples of the solid aromatic modified terpene resin include a solid resin obtained by modifying a terpene resin with an aromatic compound, and a solid resin obtained by hydrogenating the resin. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring. For example, phenol compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol, alkylnaphthol, alkoxynaphthol, Naphthol compounds such as naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkyl styrene, alkoxy styrene and styrene containing an unsaturated hydrocarbon group; and coumarone and indene.

Examples of the solid pt-butylphenol acetylene resin include a solid resin obtained by a condensation reaction between pt-butylphenol and acetylene.

The solid acrylic resin is not particularly limited, but a solventless acrylic solid resin can be preferably used in that a resin having a small amount of impurities and a sharp molecular weight distribution can be obtained.

A solid solvent-free acrylic resin can be produced by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) without using a polymerization initiator, a chain transfer agent, an organic solvent, and the like as auxiliary raw materials as much as possible (US Pat. No. 4,414). 370, JP-A-59-6207, JP-B 5-58005, JP-A-1-313522, U.S. Pat. No. 5,010,166, Toa Gosei Annual Research Report TREND 2000 No. 3 (Methods described in p42-45) and (meth) acrylic resins (polymers). In this specification, (meth) acryl means methacryl and acryl.

It is preferable that the solid acrylic resin does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent, and the like, which are sub-materials. The acrylic resin preferably has a relatively narrow composition distribution and molecular weight distribution obtained by continuous polymerization.

As described above, it is preferable that the solid acrylic resin does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent, and the like, which are sub-materials, that is, a resin having high purity. The purity of the solid acrylic resin (the ratio of the resin contained in the resin) is preferably 95% by mass or more, more preferably 97% by mass or more.

Examples of the monomer component constituting the solid acrylic resin include (meth) acrylic acid, (meth) acrylic acid esters (such as alkyl esters, aryl esters, and aralkyl esters), (meth) acrylamide, and (meth) acrylic ester. (Meth) acrylic acid derivatives such as acrylamide derivatives.

Further, styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinyl, as well as (meth) acrylic acid and a (meth) acrylic acid derivative as monomer components constituting the solid acrylic resin. Aromatic vinyl such as naphthalene may be used.

The solid acrylic resin may be a resin composed of only a (meth) acrylic component or a resin having components other than the (meth) acrylic component as constituents.
In addition, the solid acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, and the like.

Examples of the plasticizer and the solid resin include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yashara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals, BASF, Arizona Chemical Co., Ltd., and Nikki Chemical Co., Ltd. Products such as Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

The rubber composition preferably contains an antioxidant from the viewpoint of crack resistance, ozone resistance and the like.

The antioxidant is not particularly limited, but a naphthylamine antioxidant such as phenyl-α-naphthylamine; a diphenylamine antioxidant such as octylated diphenylamine and 4,4′-bis (α, α′-dimethylbenzyl) diphenylamine. N-isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylene P-phenylenediamine anti-aging agents such as diamines; quinoline anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methyl Monophenolic antioxidants such as phenol and styrenated phenol; tetrakis- [methylene-3- (3 ', 5'-di-t) Butyl-4'-hydroxyphenyl) propionate] bis methane, tris, and the like polyphenolic antioxidants. Of these, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 And a polymer of 2,2-dihydroquinoline is more preferred. Commercially available products include, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis.

The content of the antioxidant is preferably at least 0.2 part by mass, more preferably at least 0.5 part by mass, based on 100 parts by mass of the rubber component. By setting the lower limit or more, sufficient ozone resistance tends to be obtained. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less. When the content is not more than the upper limit, a good appearance tends to be obtained.

The rubber composition preferably contains stearic acid. The content of stearic acid is preferably from 0.5 to 10 parts by mass, more preferably from 0.5 to 5 parts by mass, based on 100 parts by mass of the rubber component, from the viewpoint of the performance balance.

As the stearic acid, conventionally known stearic acids can be used. For example, products such as NOF Corporation, NOF, Kao Corporation, Wako Pure Chemical Industries, Ltd., and Chiba Fatty Acid Corporation can be used. .

The rubber composition preferably contains zinc oxide. The content of zinc oxide is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the rubber component, from the viewpoint of the performance balance.

Conventionally known zinc oxide can be used, for example, Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusuiteku Co., Ltd., Shodo Chemical Co., Ltd., Sakai Chemical Co., Ltd., etc. Products can be used.

A wax may be compounded in the rubber composition. The wax is not particularly limited, and examples thereof include a petroleum wax and a natural wax. A synthetic wax obtained by purifying or chemically treating a plurality of waxes can also be used. These waxes may be used alone or in combination of two or more.

Examples of the petroleum wax include paraffin wax and microcrystalline wax. The natural wax is not particularly limited as long as it is derived from a non-petroleum resource. For example, plant waxes such as candelilla wax, carnauba wax, wood wax, rice wax, jojoba wax, etc .; beeswax, lanolin, whale wax, etc. Animal-based waxes; mineral-based waxes such as ozokerite, ceresin, and petrolactam; and purified products thereof. As commercial products, for example, products of Ouchi Shinko Chemical Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used. The content of the wax may be appropriately set from the viewpoint of ozone resistance and cost.

It is preferable to add sulfur to the rubber composition from the viewpoint that an appropriate crosslinked chain is formed in the polymer chain and the above-mentioned good performance balance is imparted.

The content of sulfur is preferably at least 0.1 part by mass, more preferably at least 0.5 part by mass, even more preferably at least 0.7 part by mass with respect to 100 parts by mass of the rubber component. The content is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, and still more preferably 3.0 parts by mass or less. When the content is in the above range, a favorable balance of the performance tends to be obtained.

Examples of the sulfur include powdery sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur commonly used in the rubber industry. Commercially available products such as Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis, Nippon Kishii Kogyo Co., Ltd. and Hosoi Chemical Co., Ltd. can be used. These may be used alone or in combination of two or more.

The rubber composition preferably contains a vulcanization accelerator.
The content of the vulcanization accelerator is not particularly limited, and may be freely determined in accordance with a desired vulcanization rate or crosslinking density. Usually, 0.3 to 10 parts by mass with respect to 100 parts by mass of the rubber component. , Preferably 0.5 to 7 parts by mass.

The type of the vulcanization accelerator is not particularly limited, and a commonly used vulcanization accelerator can be used. Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), Tetrabenzylthiuram disulfide (TBzTD), thiuram-based vulcanization accelerators such as tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide, etc. The Sulfena De-based vulcanization accelerator; diphenylguanidine, may be mentioned di-ortho-tolyl guanidine, guanidine-based vulcanization accelerators such as ortho tri ruby guanidine. These may be used alone or in combination of two or more. Of these, sulfenamide vulcanization accelerators and guanidine vulcanization accelerators are preferred from the viewpoint of the above-mentioned performance balance.

In addition to the above components, usual additives used for the rubber composition may be appropriately added to the rubber composition according to the application field such as a release agent and a pigment.

As a method for producing the rubber composition, a known method can be used.For example, each component such as the filler / rubber composite is kneaded using a rubber kneading device such as an open roll or a Banbury mixer, and then kneaded. It can be manufactured by a method of sulfurizing.

As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30. The time is from seconds to 30 minutes, preferably from 1 minute to 30 minutes. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C. The composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200C, preferably 140 to 180C.

The rubber composition can be used for tires, shoe sole rubber, flooring rubber, vibration-isolating rubber, seismic isolation rubber, butyl frame rubber, belts, hoses, packings, chemical stoppers, other rubber industrial products, and the like. In particular, the rubber composition is preferably used as a rubber composition for a tire, since durability (breaking strength), handling stability, fuel economy, and the like can be improved.

The rubber composition can be suitably used for a pneumatic tire. The pneumatic tire is manufactured by a usual method using the rubber composition. That is, the rubber composition containing various materials as necessary is extruded in accordance with the shape of the tire member in the unvulcanized stage, and molded together with other tire members by a normal method on a tire molding machine. Thereby, after forming an unvulcanized tire, the tire can be manufactured by heating and pressing in a vulcanizer.

The present invention will be specifically described based on examples, but the present invention is not limited to these.

Various chemicals used in preparation of the following microfibrillated plant fiber dispersion and preparation of the filler-rubber composite will be described.
Microfibrillated plant fiber: Biomass nanofiber manufactured by Sugino Machine Co., Ltd. (product name "BiNFi-s cellulose", solid content: 2% by mass, water content: 98% by mass, average fiber diameter: 20 to 50 nm, average fiber length: 500 to 1000 nm) )
TEMPO: 2,2,6,6-tetramethylpiperidine-1-oxyl sodium bromide: Sodium hypochlorite manufactured by Wako Pure Chemical Industries, Ltd .: NaOH manufactured by Tokyo Chemical Industry Co., Ltd. NaOH: Wako Pure Chemical Industries, Ltd. NaOH)
Surfactant: NUOSPERSE FX 600 manufactured by Elementis (anionic surfactant, polycarboxylic acid amine salt (containing a phenyl group as a hydrophobic group and a carboxyl group as a hydrophilic group), Mw: 2000)
Natural rubber latex: Uses field latex obtained from Muhibbah LATEKS

(Preparation of Microfibrillated Plant Fiber Dispersion (Nanofied Cellulose Dispersion))
After dispersing 10 g of microfibrillated vegetable fiber, 150 mg of TEMPO, and 1000 mg of sodium bromide in 1000 ml of water, a 15% by mass aqueous solution of sodium hypochlorite was added with 1 g of microfibrillated vegetable fiber (absolutely dry) to hypochlorite. The reaction was started by adding sodium acid so that the amount became 5 mmol. During the reaction, the pH was kept at 10.0 by dropwise addition of a 3M aqueous solution of NaOH. The reaction was considered completed when no change in pH was observed. After filtering the reaction product through a glass filter, washing with a sufficient amount of water and filtration were repeated five times to impregnate water with a solid content of 15% by mass. A reactive fiber was obtained.
It was diluted to obtain 1% by mass and 3% by mass of nanodispersed cellulose dispersion.

(Preparation of microfibrillated plant fiber / rubber composite)
A predetermined amount of a natural rubber latex and a surfactant are added to the prepared 1% by mass or 3% by mass nanodispersed cellulose dispersion according to the formulation shown in Table 1, and the stirring conditions shown in Table 1 (stirrer, mixing time) , Mixing temperature) to obtain a compounded latex having the stated viscosity, solid content ratio (% by mass), and pH.
Next, a 2% by mass aqueous solution of formic acid was added to the obtained mixed latex at room temperature to adjust the pH to 3 to 4, and a coagulated product was obtained. The obtained coagulated product was filtered and dried to obtain a nano-cellulose / rubber composite (MB1-5).

In addition, the stirrers A to C used are as follows.
Stirrer A: Patch type homogenizer “T65D Ultra Turrax” manufactured by IKA (rotation speed: 7000 rpm)
Stirrer B: "Three One Motor BL1200" manufactured by Shinto Kagaku
Stirrer C: Rotating orbital stirrer “Awatori Naritaro ARV-310” manufactured by Shinky
(Stirring conditions: revolution speed 2000 rpm)

The viscosity of the blended latex, the size of the filler aggregate (agglomerate of nano-cellulose), and the Mooney viscosity were measured by the following methods.

(Measurement of viscosity of compounded latex)
The viscosity (mPa · s) at 23 ° C. of each compounded latex was measured by a tuning fork vibrating viscometer.

(Size measurement of filler agglomerates)
The size of filler aggregates (aggregates formed by fillers) in each master batch (MB) was measured by image analysis using a scanning electron microscope photograph.

(Mooney viscosity)
The Mooney viscosity of each master batch (MB) was measured at 130 ° C according to JIS K6300-1. The larger the index, the lower the viscosity and the easier the processing (the better the processability).

Hereinafter, various chemicals used will be described collectively.
Nano-cellulose / rubber composite (MB1 to MB5): prepared as above Antioxidant: Ozonone 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylene manufactured by Seiko Chemical Co., Ltd.) Diamine)
Zinc oxide: Zinc Hua No. 1 stearic acid manufactured by Mitsui Kinzoku Mining Co., Ltd. Stearic acid “Tsubaki” manufactured by NOF Corporation
Sulfur: powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd .: Noxeller NS (N-tert-butyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

<Preparation of vulcanized rubber composition>
According to the formulation shown in Table 2, materials other than sulfur and the vulcanization accelerator were kneaded at 150 ° C. for 4 minutes using a 1.7 L Banbury mixer. Next, using an open roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded at 80 ° C. for 4 minutes to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press-vulcanized at 170 ° C. for 12 minutes using a mold having a thickness of 2 mm to obtain a vulcanized rubber composition.

(Tensile test)
According to JIS K6251 "Vulcanized rubber and thermoplastic rubber-Determination of tensile properties", the tensile strength and elongation at break of each compound (vulcanized rubber composition) were measured. With the compounded rubber 1 as 100, the tensile strength index and the elongation at break of each compound were calculated. The larger the index, the better the vulcanized rubber composition is reinforced, indicating that the mechanical strength of the rubber is large and the rubber properties are excellent.

(Complex modulus)
Complex elasticity of each compound (vulcanized rubber composition) using a viscoelastic spectrometer VES manufactured by Iwamoto Seisakusho under the conditions of a temperature of 70 ° C., a frequency of 10 Hz, an initial stretching strain of 10% and a dynamic strain of 2%. The rate E ^* (MPa) was measured. Each compound was represented by an index, with E ^{* of} compounded rubber 1 being 100. The higher the index, the higher the rigidity.

(Low fuel consumption)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho), loss tangent of each compound (vulcanized rubber composition) under the conditions of a temperature of 70 ° C., an initial strain of 10%, a dynamic strain of 1%, and a frequency of 10 Hz. (Tan δ) was measured. The tan δ index of each compound was calculated, assuming that tan δ of compounded rubber 1 was 100. The larger the index is, the lower the rolling resistance is, indicating that it is preferable.

From Tables 1 and 2, compounded rubbers 2 and 4 using MBs 2 and 4 obtained from compounded latex having a viscosity of 100 mPa · s or more containing a rubber latex and a filler have a low viscosity despite being manufactured from a high-viscosity compounded latex. It had rubber properties equal to or higher than that of compounded rubber 1 (MB1) made from the viscosity compounded latex.

Claims (9)

A filler-rubber composite obtained from a compounded latex having a viscosity of 100 mPas or more containing a rubber latex and a filler,
A filler-rubber composite in which aggregates of 10 μm or more are 5.0% or less in 100% of aggregates formed by the filler. The filler / rubber composite according to claim 1, wherein the Mooney viscosity (ML1 + 4 (130 ° C)) is 100 or less. The filler / rubber composite according to claim 1 or 2, wherein the filler is at least one selected from the group consisting of microfibrillated plant fibers, short fibrous cellulose, and gel compounds. The filler / rubber composite according to any one of claims 1 to 3, wherein the rubber latex is at least one selected from the group consisting of isoprene-based rubber latex, styrene-butadiene rubber latex, and butadiene rubber latex. The filler / rubber composite according to any one of claims 1 to 4, wherein the compounded latex contains 1 to 30 parts by mass of a filler (solid content) based on 100 parts by mass of a rubber solid content in the rubber latex. A method for producing a filler-rubber composite, comprising a step 1 of mixing a rubber latex and a filler using a self-revolving type mixing apparatus to produce a compounded latex having a viscosity of 100 mPa · s or more. The method for producing a filler-rubber composite according to claim 6, wherein the rotation-revolution type mixing device is a rotation-revolution stirring machine or a planetary mixer. A rubber composition comprising the filler / rubber composite according to claim 1. A tire having a tire member composed of the rubber composition according to claim 8.