JP2019163414A - Method for producing rubber/filler complex - Google Patents

Abstract

To provide a method for producing a rubber/filler complex (master batch) that has improved dispersibility of a filler in rubber and, when blended in a rubber composition, can improve the requested performances of a tire in a balanced manner.SOLUTION: A method for producing a rubber/filler complex has a step (1) of mixing rubber latex and a filler to prepare a latex, and a step (2) of putting the latex obtained in the step (1) into coagulation liquid to obtain a coagulum.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a rubber / filler composite.

Conventionally, a rubber composition is reinforced by adding fillers such as short fibers such as aramid, microfibrillated plant fibers such as cellulose fibers, and crystalline polymers such as syndiotactic polybutadiene to the rubber composition. It is known that the complex elastic modulus can be improved. However, the filler has a strong self-aggregation force and is often incompatible with the rubber component. For example, even if microfibrillated plant fibers are added to rubber latex and mixed, the microfibrillated plant fibers added are mixed. About 20% remained in the solution without being taken into the rubber component.

Further, when a rubber / filler composite (masterbatch) was prepared by mixing rubber latex and a filler, filler agglomerates tended to easily occur in the rubber / filler composite. For example, when such rubber / filler composites are used in tires, the generated agglomerates can cause premature wear, cracking, chipping, and interlayer separation, and further air leakage and loss of steering stability. Therefore, it has been desired to improve the dispersibility of the filler in the rubber in the rubber / filler composite.

As a method for improving the dispersibility of the filler in the rubber and improving the physical properties of the rubber in the rubber / filler composite, conventionally, after mixing the rubber latex and the filler, the pH is adjusted to adjust the rubber / filler composite. There have been methods of making. In addition, for example, a carbon black-containing slurry solution having a predetermined zeta potential and a rubber latex solution are mixed and coagulated and dried to produce a wet masterbatch (see, for example, Patent Document 1), natural rubber latex A method for producing a natural rubber masterbatch by decomposing an amide bond therein and mixing the decomposed latex with a slurry solution of an inorganic filler (see, for example, Patent Document 2), a slurry of inorganic particles, and the inorganic A method for producing a polymer composite by mixing a slurry of particles and a latex of a polymer having a surface potential with the opposite sign (for example, see Patent Document 3), combining a single component in the state of an aqueous dispersion In the aqueous dispersion, the particles have the same sign surface charge, a predetermined zeta potential, a ratio between the zeta potential of the particles of each predetermined dispersion. A method of coagulating the obtained mixed dispersion (for example, see Patent Document 4), removing water from an aqueous dispersion having a predetermined solid content concentration containing cellulose nanofibers having a predetermined average fiber width and rubber latex A method for producing a rubber masterbatch (see, for example, Patent Document 5) and a compound obtained by removing moisture from a liquid mixture having a predetermined solid content concentration containing fine cellulose fibers having a predetermined average fiber width and a resin emulsion. A method of manufacturing a material (see, for example, Patent Document 6) is disclosed.

JP 2010-209175 A JP 2004-99625 A JP 2006-348216 A JP 62-104871 A JP 2014-141737 A JP-A-2015-93882

As described above, various methods for improving the dispersibility of the filler in rubber and improving the physical properties of the rubber in the rubber / filler composite (masterbatch) have been studied. There was room for improvement.

This invention solves the said subject, improves the dispersibility of the filler in rubber | gum, and if it mix | blends with a rubber composition, the method of manufacturing the rubber / filler composite_body | complex (masterbatch) which can improve the required performance of a tire with sufficient balance. The purpose is to provide.

The present invention includes a step (1) for preparing a compounded latex by mixing a rubber latex and a filler, and a step (2) for obtaining a coagulated product by adding the compounded latex obtained in the above step (1) to a coagulation liquid. The present invention relates to a method for producing a rubber / filler composite containing

The filler is preferably at least one selected from the group consisting of silica, microfibrillated plant fiber, clay mineral, and short fibrous filler.

The coagulation liquid is preferably an acid and / or a salt.

The present invention also relates to a rubber / filler composite obtained by the above production method.

The present invention also relates to a rubber composition comprising the rubber / filler composite.

The present invention also relates to a pneumatic tire produced using the rubber composition.

The present invention includes a step (1) for preparing a compounded latex by mixing a rubber latex and a filler, and a step (2) for obtaining a coagulated product by adding the compounded latex obtained in the above step (1) to a coagulation liquid. In particular, since the compounded latex is put into a coagulating liquid to obtain a coagulated product, the dispersibility of the filler in the rubber is further improved, and the filler is finely formed in the rubber. A dispersed rubber / filler composite can be obtained.
Furthermore, the filterability at the time of obtaining a rubber / filler composite can be improved by introducing the blended latex into the coagulation liquid. Thereby, the productivity at the time of manufacturing the rubber / filler composite is further improved, and a rubber / filler composite having improved performance can be manufactured with high productivity. By using such a rubber / filler composite, it is possible to obtain a rubber composition and a pneumatic tire in which the breaking strength, elongation at break, and fuel efficiency required for the tire are improved in a well-balanced manner.

[Method for producing rubber / filler composite]
The method for producing a rubber / filler composite according to the present invention includes the step (1) of mixing a rubber latex and a filler to prepare a blended latex, and the blended latex obtained in the above step (1) is put into a coagulation liquid. And a step (2) of obtaining a coagulated product. In addition, as long as the manufacturing method of this invention includes the said process (1) and (2), it may include the other process, and the said process (1) and (2) are each performed once. Alternatively, it may be repeated a plurality of times.

Even when the rubber latex and the filler are mixed, the compatibility is poor, and it is generally difficult to sufficiently disperse the filler in the rubber in the rubber / filler composite. And (2), in particular, by adding the blended latex obtained in step (1) to the coagulation liquid to obtain a coagulated product, the dispersibility of the filler in the rubber is further improved, It has been found that a rubber / filler composite in which filler is finely dispersed in rubber can be obtained. Furthermore, by adding the compounded latex into the coagulation liquid, the filterability when obtaining a rubber / filler composite can be improved, so that a rubber / filler composite with improved performance can be produced with high productivity. I found it.

General methods for coagulating a rubber / filler composite include a method of drying a compounded latex obtained by mixing a rubber latex and a filler, or a method of coagulating into a compounded latex obtained by mixing a rubber latex and a filler. Examples thereof include a method of adding a liquid to lower the pH of the latex to coagulate. However, in these methods, since the pH and timing at which the rubber and the filler are solidified are different, the rubber does not begin to coagulate at the same time but begins to coagulate from one of them. A bad form or a filler is agglomerated and taken into the rubber, resulting in a poorly dispersed form. In particular, in the case of a method in which a coagulating liquid is added to a compounded latex obtained by mixing a rubber latex and a filler to lower the pH of the latex to coagulate, the compounded latex coagulates when it becomes acidic, but it is acidic to an alkaline compounded latex. Even when the coagulating liquid is added, the acidic component is neutralized at first and the latex as a whole continues to be in an alkaline state, so that the coagulation proceeds slowly and coagulation occurs from around the neutrality as a whole. Since the speed of coagulation differs between the rubber and filler in the compounded latex, the rubber and filler may coagulate separately, resulting in a poorly dispersed form.
On the other hand, in the method for producing a rubber / filler composite according to the present invention, a blended latex obtained by mixing a rubber latex and a filler is added to a coagulating liquid to obtain a coagulated product, thereby obtaining an acidic product. Even if alkaline compounded latex is added to the coagulation liquid, the entire system is in an acidic state, so the charged compounded latex will coagulate immediately and only one of the rubber or filler begins to coagulate. Thus, it is presumed that a rubber / filler composite in which the filler is finely dispersed in the rubber can be obtained because the solidification reaction occurs in a state where the filler is dispersed in the rubber.
Furthermore, by adding the blended latex into the coagulation liquid, the aggregation proceeds faster, and the size of the resulting coagulated particles increases, so it is assumed that the filterability when obtaining a rubber / filler composite is improved. .

(Process (1))
In the present invention, first, a step (1) of preparing a compounded latex by mixing a rubber latex and a filler is performed.

Examples of the rubber latex include natural rubber latex, modified natural rubber latex (saponified natural rubber latex, epoxidized natural rubber latex, etc.), synthetic diene rubber latex (butadiene rubber (BR), styrene butadiene rubber (SBR)). Diene rubber latex such as styrene isoprene butadiene rubber (SIBR), isoprene rubber, acrylonitrile butadiene rubber, latex of ethylene vinyl acetate rubber, chloroprene rubber, vinyl pyridine rubber, butyl rubber, etc.) can be suitably used. Thus, it is also one of the preferred embodiments of the present invention that the rubber latex is a diene rubber latex. These rubber latexes may be used alone or in combination of two or more. Of these, natural rubber latex, SBR latex, BR latex, and isoprene rubber latex are more preferable, and natural rubber latex is particularly preferable because the effects of the present invention can be more suitably obtained.

Natural rubber latex is collected as the sap of natural rubber trees such as Hevea, and contains rubber, water, proteins, lipids, inorganic salts, etc., and the gel content in rubber is based on the complex presence of various impurities. It is considered a thing. In the present invention, as a natural rubber latex, raw latex (field latex) produced by tapping Hevea tree, concentrated latex concentrated by centrifugation or creaming method (purified latex, high ammonia latex added with ammonia by a conventional method) , Zinc oxide, TMTD and ammonia stabilized LATZ latex, etc.) can be used.

Natural rubber latex has honeycomb-shaped cells made of proteins and phospholipids, and this cell tends to inhibit the incorporation of fillers into natural rubber. Therefore, natural rubber latex and filler are mixed. At that time, it was necessary to take measures such as removing cells in the natural rubber latex by saponification in advance, but in the present invention, a manufacturing method including the above steps (1) and (2) is adopted, In particular, by adding the blended latex obtained in step (1) to the coagulation liquid to obtain a coagulated product, even when natural rubber latex that has not been saponified is used, the filler is finely contained in the rubber. Can be dispersed.

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 difficult to coagulate. The pH of the rubber latex is preferably 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. In addition, it is preferable to use a rubber latex having a rubber solid content of 10 to 80% by mass. More preferably, it is 20 mass% or more and 60 mass% or less.

As the filler, fillers used in the use thereof can be appropriately blended according to the application field. For example, the filler is selected from the group consisting of silica, microfibrillated plant fiber, clay mineral, and short fibrous filler. It is preferable that it is at least one kind.

Examples of the silica include dry method silica (anhydrous silica) and wet method silica (hydrous silica). Of these, wet-process silica is preferred because it has many silanol groups. As commercial products, products such as Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used. These may be used alone or in combination of two or more.

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 still more preferably 160 m ² / g or more. By setting it to the lower limit or more, good wet grip performance and breaking strength tend to be obtained. Moreover, 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. By making it below the upper limit, good dispersibility tends to be obtained.
The _N 2 SA of silica is a value determined by the BET method in accordance with ASTM D3037-93.

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, resource biomass such as fruits, cereals, root vegetables, wood, bamboo, hemp, jute, kenaf, and pulps obtained using these as raw materials, Paper, cloth, crop waste, waste biomass such as food waste and sewage sludge, unused biomass such as rice straw, straw and thinned wood, as well as cellulose derived from sea squirts and acetic acid bacteria, etc. It is done. One type of these microfibrillated plant fibers may be used, or two or more types may be used in combination.

In the present specification, the 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 an assembly of cellulose molecules. It means a cellulose fiber having a microstructure of 500 nm or less. A typical cellulose microfibril can be formed as an aggregate of cellulose fibers having the above average fiber diameter, for example.

Although it does not specifically limit as a manufacturing method of the said microfibrillated plant fiber, For example, after refine | purifying the raw material of the said cellulose microfibril with alkalis, such as sodium hydroxide as needed, a refiner, a biaxial kneader (biaxial Extruder), twin-screw kneading extruder, high-pressure homogenizer, medium stirring mill, stone mill, grinder, vibration mill, sand grinder, and the like. In these methods, since lignin is separated from the raw material by chemical treatment, microfibrillated plant fibers substantially free of lignin are obtained. In addition, as another method, a method of subjecting the raw material of the cellulose microfibril to an ultra-high pressure treatment may be mentioned.

As said microfibrillated plant fiber, products, such as a Sugino machine, can be used, for example.

In addition, as the microfibrillated plant fiber, those obtained by the above production method, further subjected to oxidation treatment and various chemical modification treatments, and natural products that can be derived from the cellulose microfibril (for example, Wood, pulp, bamboo, hemp, jute, kenaf, crop waste, cloth, paper, squirt cellulose, etc.) are used as raw materials for cellulose, and then subjected to oxidation treatment and various chemical modification treatments, followed by defibration treatment as necessary. What performed this can also be used.

The average fiber diameter of the microfibrillated plant fiber is preferably 10 μm or less. When the average fiber diameter of the microfibrillated plant fiber is in such a range, the dispersibility of the microfibrillated plant fiber in rubber can be further improved, and the effect of the present invention is more suitable. can do. In addition, breakage of the microfibrillated plant fiber during processing tends to be suppressed. The average fiber diameter is more preferably 500 nm or less, still more preferably 100 nm or less, and even more preferably 50 nm or less, from the viewpoint that the effects of the present invention can be more suitably obtained. Further, the lower limit of the average fiber diameter of the microfibrillated plant fiber is not particularly limited, but is preferably 4 nm or more because it is difficult to unwind and disperse the microfibrillated plant fiber, and is preferably 10 nm or more. Is more preferable, and 20 nm or more is still more preferable.

The average fiber length of the microfibrillated plant fiber is preferably 100 nm or more. More preferably, it is 300 nm or more, More preferably, it is 500 nm or more. Moreover, 5 mm or less is preferable, 1 mm or less is more preferable, 50 micrometers or less are still more preferable, 3 micrometers or less are especially preferable, and 2 micrometers or less are the most preferable. When the average fiber length is less than the lower limit or exceeds the upper limit, there is a tendency similar to the average fiber diameter described above. In addition, by using microfibrillated plant fibers having such an average fiber length, when blended in a rubber composition, it is possible to suppress strain concentration on the rubber matrix in the vicinity of the fiber edge, and to provide fracture strength and abrasion resistance. Tend to be better.

In addition, when the said microfibrillated plant 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 plant fiber.

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

Examples of the clay mineral include, for example, kaolin groups such as kaolinite, nacrite, enderite, dickite, halloysite, chrysotile; Vermiculite group such as montmorillonite, beidellite, nontronite, saponite, laponite, hectorite, saconite, stevensite, etc .; , Phyllosilicates such as margarite, clintnite, muscovite, biotite, phlogopite, synthetic mica, fluorine mica, paragolite, phlogopite, lepidrite, tetrasilic mica, teniolite; Pasaito, Sudou stone, Kukkaito, clinochlore, chamosite, chlorite, chlorite such as Nantaito; sepiolite, attapulgite, attapulgus clay, Pioraito such palygorskite - Parigosukaito; bentonites; hydrotalcite; and the like. These clay minerals may be used alone or in combination of two or more.

Among the above clay minerals, from the viewpoint of dispersibility in rubber, kaolin group, antigolite group, vermiculite group, smectite group, phyllosilicate, chlorite, and piolite-palygoskite are more preferable, kaolin group, antimony A golite group, vermiculite group, smectite group, and piolite-palygoskite are more preferred, a smectite group and piolite-palygoskite are more preferred, and montmorillonite and sepiolite are particularly preferred.

As the clay mineral, for example, products such as Enomoto Kasei Co., Ltd. and Kunimine Industries Co., Ltd. can be used.

The average particle size of the clay mineral is preferably 50 μm or less. More preferably, it is 30 μm or less. Moreover, 1 micrometer or more is preferable and 3 micrometers or more are more preferable. When the average particle diameter of the clay mineral is in such a range, the dispersibility of the clay mineral in the rubber can be further improved, and the effect of the present invention can be further improved.
The average particle size of the clay mineral is a mass-based average particle size calculated from a particle size distribution measured according to JIS Z 8815-1994.

The short fiber filler has a fiber width of 3 to 200 μm, a fiber length of 20 to 1000 μm, and a ratio of fiber width to fiber length (fiber length / fiber width) of 5 to 1000. Is preferred. By using such a short fiber filler as a filler, the dispersibility in rubber is good, so that it can be maintained or improved without impairing the breaking strength of the rubber, and the rubber physical properties are excellent. can do.

The short fiber filler has a fiber width of 3 to 200 μm. Normally, the fibrous filler blended in the rubber composition is preferable in terms of rubber reinforcement as the fiber width is small. On the other hand, the fibrous filler having a small fiber width tends to be difficult to be oriented. The fiber width is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more from the viewpoint of the balance between reinforcement and fiber orientation, and further from the viewpoint of dispersibility in rubber. Moreover, 120 micrometers or less are preferable, 80 micrometers or less are more preferable, and 50 micrometers or less are still more preferable.

The fiber length of the short fibrous filler is 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 rubber reinforcement and fiber orientation, and further from the viewpoint of dispersibility in rubber. Is more preferable. Moreover, 700 micrometers or less are preferable and 500 micrometers or less are more preferable.

The short fiber filler has a fiber width to fiber length ratio (fiber length / fiber width) of 5 to 1000. Similarly to the fiber width, from the viewpoint of the balance between rubber reinforcement and fiber orientation, the ratio of the fiber width to the fiber length is preferably 6 or more, and more preferably 10 or more. Moreover, 800 or less is preferable, 500 or less is more preferable, 400 or less is further more preferable, and 300 or less is especially preferable.

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

Although it does not specifically limit as said short fiber filler, For example, the short fiber filler which has the said specific fiber width and fiber length can be obtained by defibrating inorganic fiber, an animal fiber, and a synthetic fiber. Specific examples include inorganic fibers such as glass fibers, potassium titanate fibers, activated carbon fibers, rayon, polyester fibers, and aramid fibers.

As the short fiber filler, for example, products such as Rhein Chemie, Toray Industries, Inc. can be used.

The filler may be mixed with a rubber latex in the form of a dispersion (filler dispersion, slurry) dispersed in a solvent, or after the filler dispersion is solvent-substituted with ethanol or the like, it is mixed with the rubber latex. Alternatively, the filler may be mixed with the rubber latex as it is. In addition, it does not specifically limit as a solvent in the said filler dispersion liquid, Water etc. are mentioned.

The filler dispersion can be produced by a known method, and the production method is not particularly limited. For example, the filler dispersion is made of water using a high-speed homogenizer, an ultrasonic homogenizer, a colloid mill, a blender mill, an electronically controlled agitator, or the like. It can be prepared by dispersing in a solvent. The temperature and time during the preparation can also be appropriately set within a range that is usually performed so that the filler is sufficiently dispersed in a solvent such as water.

Although content (solid content) of the filler in the said filler dispersion liquid is not specifically limited, Preferably it is 0.2-20 mass%, More preferably, it is 0.5-10 mass%, More preferably, it is 0.5-5. % By mass.

In the step (1), 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 such as may be further added. In particular, a preferable mode is one in which the filler and the surfactant are mixed and dispersed and then mixed with the rubber latex.

In the step (1), a method for mixing the rubber latex and the filler is not particularly limited. For example, the rubber is added to a known stirring device such as a high-speed homogenizer, an ultrasonic homogenizer, a colloid mill, or a blender mill. A method of dropping the filler and the filler dispersion while stirring the latex, a method of dropping the rubber latex while stirring and adding the filler and the filler dispersion to the known stirring device, The rubber latex, the filler, and the filler dispersion are put in a known stirring device, and a method of stirring and mixing is exemplified. In this way, a blended latex can be prepared. The temperature and time for preparing the blended latex can be appropriately set within a range that is usually performed until the rubber latex, the filler, and the filler dispersion are sufficiently dispersed. It is preferably 3 to 120 minutes at ° C and more preferably 5 to 90 minutes at 15 to 40 ° C.

The pH of the compounded latex obtained in the above step (1) is preferably 9.0 or more, and more preferably 9.5 or more. Moreover, 12 or less is preferable and 11.5 or less is more preferable. When the pH of the blended latex is within such a range, a stable blended latex with little deterioration can be obtained.

In the step (1), it is preferable to mix the rubber latex and the filler so that the filler content is 5 to 70 parts by mass with respect to 100 parts by mass of the rubber solid content of the rubber latex. . By blending in such a range, the effects of the present invention can be obtained more suitably. As for content of this filler, 7 mass parts or more are more preferable, and 10 mass parts or more are still more preferable. Moreover, 50 mass parts or less are more preferable.
In particular, when the shape of the filler is spherical, the filler content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 20 parts by mass or more. On the other hand, it is preferably 70 parts by mass or less, and more preferably 50 parts by mass or less.
Moreover, when the shape of a filler is fibrous form, 5 mass parts or more are preferable, 7 mass parts or more are more preferable, and 10 mass parts or more are still more preferable. On the other hand, it is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and still more preferably 40 parts by mass or less.

The total solid content (total solid content, total solid content concentration) contained in the blended latex is 0.5% in 100% by weight of the blended latex from the viewpoint of dispersibility of the solid content in the blended latex. % By mass or more is preferable, and 1% by mass or more is more preferable. Moreover, 30 mass% or less is preferable, 10 mass% or less is more preferable, and 5 mass% or less is still more preferable.

(Process (2))
In the present invention, next, step (2) is performed in which the blended latex obtained in step (1) is charged into a coagulation liquid to obtain a coagulated product.
As a result, a coagulated product (aggregate containing aggregated rubber and filler) is obtained by the above step (2). In the present invention, when the coagulation reaction is performed in the step (2), the compounded latex is coagulated. By introducing into a liquid to obtain a solidified product, the dispersibility of the filler in the rubber is further improved, and a rubber / filler composite in which the filler is finely dispersed in the rubber can be obtained. By introducing the compounded latex into the coagulation liquid, the filterability when obtaining a rubber / filler composite can be improved, and therefore a rubber / filler composite with improved performance can be produced with high productivity.

In the step (2), as a method for obtaining the coagulated product by adding the compounded latex obtained in the step (1) to the coagulation liquid, a sufficient amount of the coagulation liquid is put into a stirrer and stirred. A method of adding the above-described blended latex is preferred. Furthermore, from the viewpoint of dispersibility of the filler, a method of adding the above-mentioned compounded latex in a stepwise manner (adding the whole amount dividedly) is more preferable, and a method of dropping the above-mentioned compounded latex and a method of continuously adding it are further. preferable.

As a method for adding the compounded latex, a method of dropping the compounded latex or adding the compounded latex continuously is preferable, but it is particularly preferable to add the compounded latex at a constant rate. The addition rate is preferably constant, and the rate itself is not particularly limited and can be appropriately adjusted. For example, it is preferable to add the blended latex at a rate of 100 to 1500 g / min. When the addition rate is within such a range, the effects of the present invention can be more suitably obtained without impairing productivity. The addition rate is more preferably 200 g / min or more. Moreover, 500 g / min or less is more preferable.

As the addition rate, for example, it is preferable to add the compounded latex so that the rubber (solid content) in the compounded latex is added at a rate of 1 to 70 g / min. When the addition rate is within such a range, the effects of the present invention can be more suitably obtained without impairing productivity. The addition rate is more preferably 20 g / min or more. On the other hand, it is more preferably 50 g / min or less.
Further, for example, it is preferable to add the compounded latex so that the filler in the compounded latex is added at a rate of 0.1 to 20 g / min. When the addition rate is within such a range, the effects of the present invention can be more suitably obtained without impairing productivity. The addition rate is more preferably 2 g / min or more. On the other hand, it is more preferably 10 g / min or less.

The coagulation liquid is preferably an acid and / or a salt. And it is especially preferable that they are an acid and a salt.
Examples of the acid include formic acid, sulfuric acid, hydrochloric acid, and acetic acid. Moreover, as said salt, 1-3 metal salts, such as calcium salts, such as sodium chloride, magnesium chloride, calcium nitrate, calcium chloride, are mentioned, for example.

Examples of the stirrer include known stirrers such as a high-speed homogenizer, an ultrasonic homogenizer, a colloid mill, a blender mill, and an electronically controlled stirrer. From the viewpoint of filler dispersibility, an electronically controlled stirrer is used. preferable. In addition, although the stirring conditions of this stirring can be suitably set in the range normally performed, from the viewpoint of the dispersibility of a filler, for example, 10-500 rpm is preferable and 50-200 rpm is more preferable. Moreover, 3-120 minutes are preferable at 10-50 degreeC, and, as for stirring temperature and stirring time, 5-90 minutes are more preferable at 15-40 degreeC. In addition, from the viewpoint of filler dispersibility, the temperature of the compounded latex during coagulation is preferably 10 to 40 ° C, more preferably 35 ° C or less.

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

When the coagulated product (aggregate containing agglomerated rubber and filler) obtained in the above step (2) is filtered and dried by a known method, and further dried, rubber is kneaded with a biaxial roll, a banbury, etc. A composite (rubber / filler composite) sufficiently dispersed in the rubber matrix can be obtained. The rubber / filler composite obtained by the production method of the present invention is also one of the present invention, but the rubber / filler composite contains other components as long as the effects of the present invention are not impaired. But you can.

The filtration can be performed by a known method such as a natural filtration method, a vacuum filtration method, a pressure filtration method, or a centrifugal filtration method. For example, in the case of a natural filtration method, filtration can be performed by placing a filter cloth on a basket having a hole and placing a coagulum on the filter cloth.
The cage having a hole is not particularly limited as long as it has a structure in which water flows down, and examples thereof include a plastic and a metal.
As said filter cloth, a nonwoven fabric, an exposure, a metal mesh, a polymesh etc. are mentioned, for example. Examples of the material of the polymesh include polypropylene, Teflon (registered trademark), polyethylene, and the like. The mesh opening is usually 500 μm or less.

(Rubber composition)
The rubber composition includes the rubber / filler composite. The rubber / filler composite can be used as a master batch. In the rubber / filler 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 reinforcement can be exhibited, and breaking strength, elongation at break, and fuel efficiency can be improved in a well-balanced manner.

The rubber composition may contain other rubber components other than the rubber (rubber component) used in the rubber / filler 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), acrylonitrile butadiene rubber ( NBR). Examples of rubber components other than those described above include butyl rubber and fluororubber. These may be used alone or in combination of two or more. As the rubber component, SBR, BR, and isoprene-based rubber are preferable, and SBR is more preferable.

Here, the other rubber component is preferably a rubber having a weight average molecular weight (Mw) of 200,000 or more, more preferably 350,000 or more. The upper limit of Mw is not particularly limited, but is preferably 4 million or less, more preferably 3 million or less.

In this specification, Mw and number average molecular weight (Mn) are gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corp., detector: differential refractometer, column: manufactured by Tosoh Corp.) Of TSKGEL SUPERMULTIPORE HZ-M) can be determined by 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 a diene rubber having a functional group that interacts with a filler such as silica. For example, at least one terminal of the diene rubber is a compound having the above functional group (modifier). Terminal-modified diene rubber modified with (terminated modified diene rubber having the above functional group at the end), main chain modified diene rubber having the above functional group at the main chain, and the above functional group at the main chain and terminal. 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 modifier), or two or more in the molecule Examples thereof include terminal-modified diene rubbers that are modified (coupled) with a polyfunctional compound having an epoxy group and into which a hydroxyl group or an epoxy group is introduced.

Examples of the functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfides. 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, etc. . 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 ( An alkoxysilyl group having 1 to 6 carbon atoms is preferred.

It does not specifically limit as SBR, For example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), etc. can be used. These may be used alone or in combination of two or more.

The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more. The styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less. The said effect is acquired more suitably as it is in the said range.
In the present specification, the styrene content of SBR is calculated by H ¹ -NMR measurement.

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

The SBR may be non-modified SBR or modified SBR. Examples of the modified SBR include modified SBR in which the same functional group as 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 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and may be 100% by mass. By setting it within the above range, good wet grip performance tends to be obtained.

BR is not particularly limited, and for example, high cis BR having a high cis content, BR containing syndiotactic polybutadiene crystals, 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 these, high cis BR having a cis content of 90% by mass or more is preferable because the wear resistance is improved.

In addition, BR may be non-modified BR or modified BR. Examples of the modified BR include modified BR in which the same functional group as that of the modified diene rubber is introduced.

As BR, for example, products such as Ube Industries, JSR, Asahi Kasei, Nippon Zeon, and the like 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, those generally used in the rubber industry such as SIR20, RSS # 3, and TSR20 can be used. The IR is not particularly limited and, for example, IR2200 or the like commonly used in the rubber industry can be used. As modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. 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.

In the rubber composition, the filler content (solid content) is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, and still more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, 70 mass parts or less are preferable, and 50 mass parts or less are more preferable. The said effect is acquired more suitably as content of the filler in a rubber composition is such a range.
In particular, when the shape of the filler is spherical, the filler content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 20 parts by mass or more. On the other hand, it is preferably 70 parts by mass or less, and more preferably 50 parts by mass or less.
Moreover, when the shape of a filler is fibrous form, 5 mass parts or more are preferable, 7 mass parts or more are more preferable, and 10 mass parts or more are still more preferable. On the other hand, it is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and still more preferably 40 parts by mass or less.

The rubber composition preferably contains silica as a filler from the viewpoint of the performance balance. Examples of the silica include dry method silica (anhydrous silica) and wet method silica (hydrous silica). Of these, wet-process silica is preferred because it has many silanol groups. As commercial products, products such as Degussa, Rhodia, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used. These may be used alone or in combination of two or more.
When silica is used as the filler of the rubber / filler composite, it means that silica is further added to the rubber composition separately from the silica.

The content of silica is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably 50 parts by mass or more 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. By making it below 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 still more preferably 160 m ² / g or more. By setting it to the lower limit or more, good wet grip performance and breaking strength tend to be obtained. Moreover, 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. By making it below the upper limit, good dispersibility tends to be obtained.
The _N 2 SA of silica is a value determined by the BET method in accordance with ASTM D3037-93.

(Silane coupling agent)
When the rubber composition contains silica, it is preferable to further contain a silane coupling agent.
The silane coupling agent is not particularly limited. 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 ester) 3) disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3 -Sulphides such as triethoxysilylpropyl methacrylate monosulfide, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Momentive NXT, NXT-Z, etc. mercapto, vinyltriethoxysilane, vinyl Vinyl type such as trimethoxysilane, amino type such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycid Glycidoxy such as cyclopropyltrimethoxysilane, nitro such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, chloro such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane Etc. As commercially available products, products such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Amax Co., Ltd., Toray Dow Corning Co., Ltd. can be used. These may be used alone or in combination of two or more.

3 mass parts or more are preferable with respect to 100 mass parts of silica, and, as for content of a silane coupling agent, 6 mass parts or more are more preferable. There exists a tendency for favorable fracture strength etc. to be acquired as it is 3 mass parts or more. The content is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less. There exists a tendency for the effect corresponding to the compounding quantity to be acquired as it is 20 mass parts or less.

The rubber composition preferably contains carbon black as a filler from the viewpoint of the performance balance. Although it does not specifically limit as carbon black, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762 etc. are mentioned. As commercial products, products such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Nisshinka Carbon Co., Ltd., Columbia Carbon Co., etc. are used. it can. These may be used alone or in combination of two or more.

The content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the rubber component. By setting it to the lower limit or more, good wear resistance, grip performance and the like tend to be obtained. Moreover, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. By making it below the upper limit, good processability of the rubber composition tends to be obtained.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 50 m ² / g or more, more preferably 80 m ² / g or more, and still more preferably 100 m ² / g or more. By setting the lower limit or more, good wear resistance and grip performance tend to be obtained. Further, the _N 2 SA is preferably 200 meters ² / g or less, more preferably 150 meters ² / g, more preferably not more than 130m ² / g. By making it below the upper limit, good dispersion of carbon black tends to be obtained.
In addition, the nitrogen adsorption specific surface area of carbon black is calculated | required by JISK6217-2: 2001.

The rubber composition may contain a filler other than silica and carbon black. Other fillers include, but are not limited to, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica and the like.
In addition, when using a clay mineral as a filler of the said rubber / filler composite body, it means adding the above other fillers to the rubber composition separately from the clay mineral.

The rubber composition may contain a plasticizer. Although it does not specifically limit as a plasticizer, Oil, liquid resin, etc. are mentioned. These plasticizers may be used alone or in combination of two or more.

The oil is not particularly limited, but process oils such as paraffinic process oils, aroma based process oils, naphthenic process oils, low PCA (polycyclic aromatic) process oils such as TDAE and MES, vegetable oils and fats, and Conventionally known oils such as a mixture thereof can be used. Among these, an aromatic process oil is preferable in terms of wear resistance and fracture 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, and examples thereof include liquid aromatic vinyl polymers, coumarone indene resins, indene resins, terpene resins, rosin resins, and hydrogenated products thereof.

The liquid aromatic vinyl polymer is a resin obtained by polymerizing α-methylstyrene and / or styrene, and includes a homopolymer of styrene, a homopolymer of α-methylstyrene, and α-methylstyrene and styrene. Examples thereof include liquid resins such as copolymers.

The liquid coumarone indene resin is a resin containing coumarone and indene as a main monomer component constituting the resin skeleton (main chain). As a monomer component that may be contained in the skeleton other than coumarone and indene, , Styrene, α-methylstyrene, methylindene, vinyltoluene, and other liquid resins.

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

The liquid terpene resin is a liquid typified by terpene phenol which is a resin obtained by polymerizing a terpene compound such as α-pinene, β-pinene, camphor and dipetene, and a resin obtained by using a terpene compound and a phenolic compound as raw materials. Terpene resin.

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

The rubber composition may be blended with a solid resin (a polymer in a solid state at room temperature (25 ° C.)).

When the solid resin is contained, the content thereof is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. 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. Within the above range, good wet grip performance tends to be obtained.

Although it does not specifically limit as solid resin, For example, solid styrene resin, coumarone indene resin, terpene resin, pt-butylphenol acetylene resin, acrylic resin, 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.) each independently polymerized, a copolymer obtained by copolymerizing two or more styrene monomers, and a styrene monomer And copolymers of other monomers that can be copolymerized therewith.

Examples of other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, chloroprene, and butadiene. Examples thereof 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, and the like.

Of these, solid α-methylstyrene resins (α-methylstyrene homopolymer, copolymer of α-methylstyrene and styrene, etc.) are preferable.

Examples of the solid coumarone indene resin include solid resins having the same structural unit as the liquid coumarone indene resin described above.

Examples of the solid terpene resin include polyterpene, terpene phenol, and aromatic modified terpene resin.
Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. The terpene compound is a hydrocarbon represented by a composition of (C ₅ H ₈ ) _n and an oxygen-containing derivative thereof. Monoterpene (C ₁₀ H ₁₆ ), sesquiterpene (C ₁₅ H ₂₄ ), diterpene (C ₂₀ H ₃₂₎ ), Etc., which are classified into terpenes, for example, α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-ferrandrene, α-terpinene, γ-terpinene, terpinolene. 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and the like.

Solid polyterpenes include α-pinene resins, β-pinene resins, limonene resins, dipentene resins, β-pinene / limonene resins and other terpene resins made from the above-mentioned terpene compounds, as well as hydrogenation of the terpene resins. 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 the phenol compound, and a solid resin obtained by hydrogenation treatment of the resin. Specifically, the terpene compound, the phenol compound, and Examples include solid resins condensed with formalin. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol.

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 has an aromatic ring. For example, phenol compounds such as phenol, alkylphenol, alkoxyphenol, unsaturated hydrocarbon group-containing phenol; naphthol, alkylnaphthol, alkoxynaphthol, Examples thereof include naphthol compounds such as unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone and indene.

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

Although it does not specifically limit as solid acrylic resin, A solventless acrylic solid resin can be used conveniently from the point that there are few impurities and a molecular weight distribution is sharp.

A solid solventless acrylic resin is a high-temperature continuous polymerization method (high-temperature continuous mass polymerization method) (U.S. Pat. No. 4,414) without using a polymerization initiator, a chain transfer agent, an organic solvent, or the like as auxiliary materials as much as possible. No. 3,370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, US Pat. No. 5,010,166, Toa Gosei Research Annual Report TREND2000 3 (Meth) acrylic resin (polymer) synthesized by the method described in No. p42-45 and the like. In the present 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, or the like, which are substantially auxiliary materials. The acrylic resin preferably has a relatively narrow composition distribution and molecular weight distribution obtained by continuous polymerization.

As described above, the solid acrylic resin is preferably a resin that does not substantially contain a polymerization initiator, a chain transfer agent, an organic solvent, or the like that is a secondary raw material, that is, a high purity resin. The purity of the solid acrylic resin (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 ester (alkyl ester, aryl ester, aralkyl ester, etc.), (meth) acrylamide, and (meth). Examples include (meth) acrylic acid derivatives such as acrylamide derivatives.

In addition, as a monomer component constituting a solid acrylic resin, together with (meth) acrylic acid and (meth) acrylic acid derivatives, styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinyl Aromatic vinyl such as naphthalene may be used.

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

Examples of plasticizers and solid resins include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yashara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Arizona Chemical Co., Ltd., and Nikko Chemical Co., Ltd. , Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Co., Ltd., Taoka Chemical Co., Ltd., etc. can be used.

The rubber composition preferably contains an anti-aging agent from the viewpoint of crack resistance, ozone resistance and the like.

Although it does not specifically limit as anti-aging agent, Diphenylamine type anti-aging agents, such as naphthylamine type anti-aging agents, such as phenyl-alpha-naphthylamine; Octylated diphenylamine, 4,4'-bis (alpha, alpha'-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-based antioxidants such as diamines; quinoline-based antioxidants 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-based antioxidants and quinoline-based antioxidants are preferable, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1 More preferred is a polymer of 1,2-dihydroquinoline. Examples of commercially available products include Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and Flexis Co., Ltd.

The content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. By making 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. There exists a tendency for a favorable external appearance to be acquired by making it below an upper limit.

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

As stearic acid, conventionally known ones can be used. For example, products such as NOF Corporation, NOF, Kao Corporation, Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd. 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 with respect to 100 parts by mass of the rubber component, from the viewpoint of the performance balance.

In addition, as a zinc oxide, a conventionally well-known thing can be used, for example, Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. Can be used.

You may mix | blend a wax with the said rubber composition. The wax is not particularly limited, and examples thereof include petroleum wax and natural wax. A synthetic wax obtained by refining 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 petroleum waxes include paraffin wax and microcrystalline wax. Natural waxes are not particularly limited as long as they are derived from non-petroleum resources. For example, plant waxes such as candelilla wax, carnauba wax, wood wax, rice wax, jojoba wax; beeswax, lanolin, whale wax, etc. Animal waxes; mineral waxes such as ozokerite, ceresin, petrolactam; and purified products thereof. As a commercial item, products, such as Ouchi Shinsei Chemical Co., Ltd., Nippon Seiwa Co., Ltd., Seiko Chemical Co., Ltd., can be used, for example. In addition, what is necessary is just to set content of wax suitably from the point of ozone resistance and cost.

The rubber composition is preferably blended with sulfur in that an appropriate cross-linked chain is formed in the polymer chain and a good performance balance is imparted.

The sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and still more preferably 0.7 parts by mass or more 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. There exists a tendency for the said favorable performance balance to be acquired by making it in the said range.

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur that are generally used in the rubber industry. As commercial products, products such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Ltd., Nihon Kiboshi Kogyo Co., Ltd., Hosoi Chemical Industry 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 according to the desired vulcanization speed and crosslinking density, but is usually 0.3 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The amount is preferably 0.5 to 7 parts by mass.

There is no restriction | limiting in particular in the kind of vulcanization accelerator, The normally used thing can be used. Examples of the vulcanization accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram disulfide (TMTD ), Tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N) and other thiuram vulcanization accelerators; N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl- 2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N, N′-diisopropyl-2-benzothiazolesulfenamide, etc. Sulfena De-based vulcanization accelerator; diphenylguanidine, it 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 preferable from the viewpoint of the performance balance.

In addition to the above components, the rubber composition may be appropriately blended with conventional additives used for their use according to the application field such as a release agent and pigment.

As a method for producing the rubber composition, known methods can be used. For example, the above components can be produced by kneading each component using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing. .

As the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30. Second to 30 minutes, preferably 1 to 30 minutes. In the final 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. Further, a 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 200 ° C, preferably 140 to 180 ° C.

The rubber composition can be used for tires, shoe sole rubber, flooring rubber, anti-vibration rubber, seismic isolation rubber, butyl frame rubber, belts, hoses, packings, medicine plugs, and other industrial rubber products. In particular, the rubber composition for tires is preferably used because the breaking strength, elongation at break, and fuel economy can be improved in a well-balanced manner.

The said rubber composition can be used conveniently for a pneumatic tire. The pneumatic tire is manufactured by a normal method using the rubber composition. That is, a rubber composition containing various materials as necessary is extruded in accordance with the shape of the tire member at an unvulcanized stage, and is molded together with other tire members by a normal method on a tire molding machine. Thus, 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 examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described together.
Natural rubber latex: Field latex obtained from Muhibah LATEKS is used Silica: Ultrasil VN3 (N ₂ SA: 172 m ² / g) manufactured by Degussa
Microfibrillated plant fiber: Biomass nanofiber manufactured by Sugino Machine Co., Ltd. (Product name “BiNFi-s cellulose”, average fiber length: about 2 μm, average fiber diameter: about 0.02 μm, solid content: 2% by mass)
Sepiolite: Sepiolite manufactured by Enomoto Kasei Co., Ltd. (trade name: “PANSIL”, average particle size: 5 μm)
Aramid fiber: aramid fiber manufactured by Rhein Chemie (trade name: “AFP-40”, fiber width: 20 μm, fiber length: 500 μm)
Anti-aging agent: NOCRACK 6C (N- (1,3-dimethylbutyl) -N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Zinc oxide: 2 types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Amber sulfur manufactured by NOF Corporation: Sulfur powder vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd .: Ouchi Shinsei Chemical Industry Co., Ltd. Noxera-NS (N-tert-butyl-2-benzothiazolylsulfenamide)

<Example 1>
Silica is diluted with water so that the solid content concentration is 5% by mass, and stirred at room temperature (20-30 ° C.) for about 60 minutes using a high-speed homogenizer (“magicLAB” manufactured by IKA Japan, rotation speed: 20000 rpm). Thus, a uniform aqueous dispersion (silica aqueous dispersion) was prepared.
After adjusting the solid content concentration (DRC) of the natural rubber latex to 30% by mass, the dry weight (solid content) of silica of the aqueous dispersion prepared above is 10 with respect to 100 parts by mass of the rubber solid content of the natural rubber latex. A rubber latex dispersion liquid (compounded latex) is prepared by adding and mixing with a high-speed homogenizer (“T50” manufactured by IKA Japan, rotation speed: 8000 rpm) at 25 ° C. for 5 minutes. (PH 10.5).
Subsequently, the blended latex is continuously added to an aqueous solution (coagulation liquid) containing 1% by mass formic acid and 0.5% by mass calcium chloride at room temperature at a rate of 250 g / min (rubber solid content: 20 g / min, silica: 2 g / min). The mixture was stirred with an electronically controlled stirrer (500 rpm, room temperature, 10 minutes) to obtain a solidified product. The obtained solidified product was filtered and dried to obtain a rubber / filler composite 1-1.

<Comparative Example 1>
A rubber / filler composite 1-2 was obtained in the same manner as in Example 1 except that the coagulation liquid was continuously added to the compounded latex at room temperature.

<Example 2>
A dispersion in which microfibrillated plant fibers are dispersed in water is diluted with water so that the solid content concentration is 0.5% by mass, and this is stirred at room temperature (20 to 30 ° C.) and subjected to ultrasonic treatment. For 5 minutes to obtain an aqueous dispersion of microfibrillated plant fibers.
After adjusting the solid content concentration (DRC) of the natural rubber latex to 30% by mass, the above prepared aqueous dispersion is added to the dry weight (solid content of the microfibrillated plant fiber with respect to 100 parts by mass of the rubber solid content of the natural rubber latex. The rubber latex dispersion (compounding) was added with stirring at 25 ° C. for 5 minutes using a high speed homogenizer (“T50” manufactured by IKA Japan, rotation speed: 8000 rpm). (Latex) was prepared (pH 10.5).
Next, 500 g / min of the compounded latex in an aqueous solution (coagulation liquid) containing 1% by mass formic acid and 0.5% by mass calcium chloride at room temperature (rubber solid content: 20 g / min, microfibrillated plant fiber: 2 g / min) The mixture was stirred with an electronically controlled stirrer (500 rpm, room temperature, 10 minutes) to obtain a solidified product. The obtained solidified product was filtered and dried to obtain a rubber / filler composite 2-1.

<Comparative example 2>
A rubber / filler composite 2-2 was obtained in the same manner as in Example 2 except that the coagulation liquid was continuously added to the compounded latex at room temperature.

<Example 3>
Sepiolite was diluted with water so that the solid concentration was 2% by mass, and about 24 at room temperature (20-30 ° C.) using an electronically controlled stirrer (“Eurostar” manufactured by IKA Japan, rotation speed: 500 rpm). By stirring for a while, a uniform aqueous dispersion (an aqueous dispersion of sepiolite) was prepared.
After adjusting the solid content concentration (DRC) of the natural rubber latex to 30% by mass, the dry weight (solid content) of sepiolite is 10 for the aqueous dispersion prepared above with respect to 100 parts by mass of the rubber solid content of the natural rubber latex. A rubber latex dispersion liquid (compounded latex) is prepared by adding and mixing with a high-speed homogenizer (“T50” manufactured by IKA Japan, rotation speed: 8000 rpm) at 25 ° C. for 5 minutes. (PH 10.5).
Next, the blended latex is continuously added to an aqueous solution (coagulation liquid) containing 1% by mass formic acid and 0.5% by mass calcium chloride at room temperature at a rate of 300 g / min (rubber solid content: 20 g / min, sepiolite: 2 g / min). The mixture was stirred with an electronically controlled stirrer (500 rpm, room temperature, 10 minutes) to obtain a solidified product. The obtained solidified product was filtered and dried to obtain a rubber / filler composite 3-1.

<Comparative Example 3>
A rubber / filler composite 3-2 was obtained in the same manner as in Example 3 except that the coagulation liquid was continuously added to the compounded latex at room temperature.

<Example 4>
The aramid fiber is diluted with water so that the solid content concentration becomes 0.5% by mass, and about a room temperature (20 to 30 ° C.) using a high-speed homogenizer (“magicLAB” manufactured by IKA Japan, rotation speed: 20000 rpm). The mixture was stirred for 60 minutes to prepare a uniform aqueous dispersion (aramid fiber aqueous dispersion).
After adjusting the solid content concentration (DRC) of the natural rubber latex to 30% by mass, the dry weight (solid content) of the aramid fiber is used for the aqueous dispersion prepared above with respect to 100 parts by mass of the rubber solid content of the natural rubber latex. Add to 10 parts by mass, and stir and mix at 25 ° C. for 5 minutes using a high-speed homogenizer (“T50” manufactured by IKA Japan, rotation speed: 8000 rpm) to mix the rubber latex dispersion (compounded latex). Prepared (pH 10.5).
Subsequently, the blended latex is added to an aqueous solution (coagulation liquid) containing 1% by mass formic acid and 0.5% by mass calcium chloride at room temperature at a rate of 500 g / min (rubber solid content: 20 g / min, aramid fiber: 2 g / min). While continuously added, the mixture was stirred with an electronically controlled stirrer (500 rpm, room temperature, 10 minutes) to obtain a solidified product. The obtained solidified product was filtered and dried to obtain a rubber / filler composite 4-1.

<Comparative example 4>
A rubber / filler composite 4-2 was obtained in the same manner as in Example 4 except that the coagulation liquid was continuously added to the compounded latex at room temperature.

In Examples 1 to 4 and Comparative Examples 1 to 4, the filtration rate when filtering the coagulum was measured and evaluated for the time taken to filter 500 g of the coagulum. The results are shown in Table 1.
The filtration was performed by placing a non-woven fabric on a plastic sieve and placing a coagulum on it.

From Table 1, in Examples 1 to 4 in which the blended latex is added to the coagulated liquid, the time required for filtration is shorter and the filtration speed is faster than in Comparative Examples 1 to 4 in which the coagulated liquid is charged to the blended latex. It became clear that the filterability when obtaining a rubber / filler composite was excellent.

<Examples 11-14 and Comparative Examples 11-14>
According to the formulation shown in Table 2, chemicals other than sulfur and a vulcanization accelerator were kneaded at 130 ° C. for 4 minutes using a 1.7 L Banbury mixer. Next, using a roll, sulfur and a vulcanization accelerator were added to the obtained kneaded material 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 to obtain a vulcanized product. The obtained vulcanizates were evaluated as follows, and the results are shown in Table 2.

(Breaking strength / elongation at break)
No. 3 dumbbell-shaped rubber test piece was prepared from the vulcanized product, and a tensile test was conducted according to JIS K6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”. Breaking strength (TB), at break Elongation (EB) was measured. The TB index and EB index of the rubber test piece (reference test piece) of Comparative Example 11 were set to 100, respectively, and the TB and EB of the blend (vulcanized product) of Example 11 were indicated by the following formula. The larger the TB index, the greater the breaking strength and the better the reinforcing property, and the larger the EB index, the larger the elongation at break and the better the crack resistance.
(TB index) = (TB of formulation of Example 11) / (TB of reference specimen) × 100
(EB index) = (EB of formulation of Example 11) / (EB of reference specimen) × 100
Similarly, TB and EB of the blend of Example 12 (vulcanized product) are the test specimens of the rubber test piece of Comparative Example 12, and TB and EB of the blend of Example 13 (vulcanized product) are the comparative examples. The rubber test piece of Example 14 was used as a reference test piece, and TB and EB of the formulation (vulcanized product) of Example 14 were indexed using the rubber test piece of Comparative Example 14 as a reference test piece.

(Rolling resistance)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), tan δ of each compound (vulcanized product) was measured under conditions of a temperature of 50 ° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz. Using tan δ of the rubber test piece (reference test piece) of Comparative Example 11 as 100, tan δ of the blend (vulcanized product) of Example 11 was expressed as an index (rolling resistance index) by the following formula. The larger the index, the better the rolling resistance characteristics (low fuel consumption).
(Rolling resistance index) = (tan δ of reference test piece) / (tan δ of formulation of Example 11) × 100
Similarly, the tan δ of the blend (vulcanized product) of Example 12 is the rubber test piece of Comparative Example 13, and the tan δ of the blend (vulcanized product) of Example 13 is the rubber test of Comparative Example 13. Using the piece as a reference test piece, the tan δ of the composition (vulcanized product) of Example 14 was indicated by an index using the rubber test piece of Comparative Example 14 as the reference test piece.

(Filler dispersibility)
The elastic modulus G * of each compound (vulcanized product) was measured from 1% to 64% of strain with a rubber testing machine dynamic viscoelasticity device “RPA” manufactured by TA Instruments Japan. ΔG * was calculated from the following equation and used as an index of filler dispersibility.
ΔG * = G * max [maximum value of G *] − G * min [minimum value of G *]
Using ΔG * of the rubber test piece (reference test piece) of Comparative Example 11 as 100, ΔG * of the formulation (vulcanized product) of Example 11 was expressed as an index (filler dispersibility index) by the following formula. The larger the index, the better the filler dispersibility.
(Filler dispersibility index) = (ΔG * of the formulation of Example 11) / (ΔG * of the reference specimen) × 100
Similarly, ΔG * of the formulation (vulcanized product) of Example 12 is the same as that of Comparative Example 13 except that the rubber test piece of Comparative Example 12 is the reference test piece. The rubber test piece was used as a reference test piece, and ΔG * of the composition (vulcanized product) of Example 14 was indicated by an index using the rubber test piece of Comparative Example 14 as a reference test piece.

From Table 2, the step (1) of mixing the rubber latex and the filler to prepare the compounded latex, and the step (2) of adding the compounded latex obtained in the step (1) to the coagulation liquid to obtain a coagulated product In Examples 11 to 14 using the rubber / filler composite obtained by the manufacturing method including the filler, the dispersibility of the filler is improved as compared with the respective reference comparative examples, and the breaking strength required for the tire, the elongation at break, and It was obtained in a well-balanced manner with high fuel efficiency.

Claims (6)

A rubber / comprising step (1) of preparing a blended latex by mixing a rubber latex and a filler, and a step (2) of adding the blended latex obtained in the step (1) to a coagulating liquid to obtain a coagulated product A method for producing a filler composite. The method for producing a rubber / filler composite according to claim 1, wherein the filler is at least one selected from the group consisting of silica, microfibrillated plant fibers, clay minerals, and short fibrous fillers. The method for producing a rubber / filler composite according to claim 1, wherein the coagulation liquid is an acid and / or a salt. A rubber / filler composite obtained by the production method according to claim 1. A rubber composition comprising the rubber / filler composite according to claim 4. A pneumatic tire produced using the rubber composition according to claim 5.