JP2011256373A - Composite and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite (master batch) in which a zinc oxide is uniformly dispersed in a rubber component, and a method of manufacturing the same.SOLUTION: There is disclosed the composite which is obtained by using blended latex mixed with rubber latex and the zinc oxide. There is also disclosed the method of manufacturing the composite including a step (I) for adjusting the blended latex by mixing the rubber latex and the zinc oxide, and a step (II) for coagulating the blended latex obtained in the step (I), and after that, drying it.

Description

The present invention relates to a composite and a method for producing the same.

Usually, when manufacturing a rubber composition, the zinc oxide particle which functions as a catalyst of a vulcanization reaction is mix | blended in order to accelerate | stimulate a vulcanization reaction. As a method of blending zinc oxide, a so-called kneading method in which solid rubber and zinc oxide are kneaded using a Banbury mixer, an open roll, a kneader or the like has been conventionally employed.

However, in the above kneading method, since zinc oxide is difficult to be uniformly dispersed, there is a problem that only a part of the added zinc oxide can function as a catalyst. In particular, since zinc oxide fine particles have a large specific surface area and are easily aggregated, this problem becomes remarkable. On the other hand, the problem is often solved by adding a large amount of zinc oxide, but on the other hand, reduction of the amount of zinc oxide used is also desired from the viewpoint of cost.

Patent Document 1 discloses a method for producing a composite by mixing fine particle silica produced from water glass with rubber latex in a liquid state. Here, zinc oxide is blended by a conventional kneading method. However, no improvement of the dispersibility of zinc oxide has been studied.

JP 2009-51955 A

An object of the present invention is to solve the above-mentioned problems and to provide a composite (master batch) in which zinc oxide is uniformly dispersed in a rubber component, and a method for producing the same.

The present invention relates to a composite obtained by using a compounded latex in which a rubber latex and zinc oxide are mixed.

The blended latex is preferably obtained by mixing a silica dispersion and the zinc oxide and further mixing the rubber latex.

The silica dispersion is preferably manufactured by adjusting the pH of the aqueous water glass solution using an ion exchange resin.

The average primary particle diameter of the zinc oxide is preferably 100 nm or less.

The present invention also includes a step (I) of preparing the compounded latex by mixing the rubber latex and the zinc oxide, and a step of coagulating and drying the compounded latex obtained in the step (I) (II ) Containing the above composite.

Since the present invention is a composite obtained by using a compounded latex in which rubber latex and zinc oxide are mixed, zinc oxide is uniformly dispersed in the rubber component, and the catalytic function of zinc oxide can be efficiently exhibited. . Thereby, the usage-amount of zinc oxide can be reduced, without reducing the efficiency of a vulcanization reaction.

2 shows a TEM photograph of the composite of Comparative Example 1. 2 shows a TEM photograph of the composite of Example 1. 2 shows a TEM photograph of the composite of Example 2. 2 shows a TEM photograph of the composite of Example 2. 3 shows a TEM photograph of the composite of Comparative Example 2. The TEM-EDX photograph of the composite_body | complex of Example 4 is shown. A curast curve (1.5 parts by mass of zinc oxide) is shown. A curast curve (3.0 parts by mass of zinc oxide) is shown. A curast curve (1.5 parts by mass of zinc oxide and 3.0 parts by mass) is shown.

<Composite>
The composite of the present invention is obtained using a compounded latex in which a rubber latex and zinc oxide are mixed. By using the blended latex, a composite in which zinc oxide is uniformly dispersed can be obtained. As a result, the function as a vulcanization acceleration aid by zinc oxide can be efficiently exhibited, and the amount of zinc oxide used can be reduced.

The composite of the present invention is prepared by, for example, mixing the rubber latex and the zinc oxide to prepare the blended latex (I), and coagulating the blended latex obtained in the step (I), followed by drying. It is obtained by a production method including the step (II).

(Process (I))
The rubber latex used in step (I) includes natural rubber (NR), epoxidized natural rubber (ENR), a copolymer of styrene and butadiene (SBR), a copolymer of styrene, isoprene and butadiene ( Examples thereof include rubber latexes such as SBIR), isoprene rubber (IR), butadiene rubber (BR), and chloroprene rubber (CR). In particular, NR latex is preferably used.
The rubber latex preferably has a rubber solid content of 10 to 70% by mass.

The zinc oxide used in step (I) is not particularly limited, and zinc oxide particles common in the tire industry can be used.

The average primary particle diameter of zinc oxide is preferably 100 nm or less, more preferably 50 nm or less, still more preferably 30 nm or less, and particularly preferably 25 nm or less. When it exceeds 100 nm, the surface area becomes small and the function as a catalyst tends to be lowered.
The average primary particle diameter of zinc oxide is preferably 1 nm or more, more preferably 5 nm or more. If it is less than 1 nm, the dispersibility of zinc oxide may not be sufficiently improved.

In this specification, transmission electron microscope (TEM) observation is used as a method for measuring the average primary particle diameter of zinc oxide. Specifically, zinc oxide is photographed with a transmission electron microscope, and the diameter of the sphere is the particle diameter when the shape of the zinc oxide is spherical, and the minor diameter is the particle diameter when it is needle-shaped or rod-shaped, In the case of an indeterminate type, the average particle size from the center is defined as the particle size, and the average value of the particle size of 100 fine particles is defined as the average primary particle size.

The method of mixing zinc oxide and rubber latex in step (I) is not particularly limited, and can be performed by a known method.

In the step (I), the compounding amount of zinc oxide with respect to 100 parts by mass (solid content) of the rubber is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and further preferably 0.5 parts by mass or more. It is. If it is less than 0.1 part by mass, the amount of zinc oxide may be reduced when used as a master batch. The zinc oxide content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and still more preferably 5 parts by mass or less. When it exceeds 10 parts by mass, the uniform dispersibility of zinc oxide tends to decrease.

From the viewpoint that the dispersibility of zinc oxide can be further improved in the silica compounded rubber, the compounded latex is preferably obtained by mixing a silica dispersion and zinc oxide and further mixing a rubber latex. That is, in the step (I), it is preferable to first mix the silica dispersion and zinc oxide, and then further mix the rubber latex with the obtained mixture. Such an improvement effect is presumed to be achieved by the fact that zinc oxide is adsorbed on the surface of highly dispersed silica to suppress aggregation of zinc oxide.

Examples of the silica dispersion include a dispersion in which silica particles are dispersed in water. Among these, a dispersion produced from water glass is preferable. In this case, silica is used by growing it as spherical fine particles instead of using the raw water glass as it is. In this growth, it is more preferable to take a long ripening time and to make it spherical. When the spherical shape is obtained, the contact between the silica particles is minimized, the cohesive force is reduced, and the silica is easily dispersed.

As the dispersion produced from water glass, a dispersion produced by adjusting the pH of the water glass aqueous solution is preferable. For example, a silica dispersion can be prepared by preparing an aqueous solution of water glass and adjusting the pH of the aqueous solution to a range of 9 to 11 (preferably 9.5 to 10.5).

The water glass is usually represented by a composition represented by the following formula.
Na ₂ O · nSiO ₂ · mH ₂ O
The coefficient n is a value represented by a molecular ratio of SiO ₂ / Na ₂ O, and is a range defined in JIS K 1408-1966 generally called a molar ratio. Although this coefficient n is not specifically limited, Preferably it is 2.1-3.3, More preferably, it is 3.1-3.3. When the coefficient n is 3.1 to 3.3, the silica component (in terms of SiO ₂ ) in the water glass increases, so that the efficiency of the composite treatment with rubber is improved.

In general, the water glass having the coefficient n of 3.1 to 3.3 is commercially available as Water Glass No. 3. The water glass which can be used for this invention is not limited to this, For example, No. 1-3 water glass prescribed | regulated to JISK1408, and other various grade products can be used.

Examples of methods for adjusting the pH of the aqueous water glass solution include addition of an acid or alkali, use of an ion exchange resin, and the like. Among these, use of an ion exchange resin is preferable.

When the silica and rubber are finally combined, if the primary particle size of the silica is too small, the surface area becomes large and the silica tends to aggregate. Therefore, in order to uniformly disperse silica and obtain the above-described improvement effect, it is considered desirable to have an appropriate silica particle size.

From the point that an appropriate silica particle diameter can be obtained, as a silica dispersion, the pH of the water glass aqueous solution 1 is adjusted to 2 to 5 using an ion exchange resin, and the step (a) and the step (a) The pH of the mixed solution obtained by mixing the ripening solution obtained in step 1) and the water glass aqueous solution 2 is adjusted to 9 to 11 using an ion exchange resin, and obtained in the step (b-1) or the step (a) for aging. What is obtained from the process (b-2) which mixes the aging liquid and the adjustment liquid which adjusted pH of the water glass aqueous solution 2 to 9-11 using the ion exchange resin, and can be used suitably can be used.

(Process (a))
In the step (a), the water glass aqueous solution 1 is prepared by a method of diluting water glass with pure water in advance. Here, the concentration of the silica component (SiO ₂ ) contained in the water glass aqueous solution 1 is preferably in the range of 0.5 to 7% by mass. If it is less than 0.5% by mass, the efficiency is poor, and if it exceeds 7% by mass, gelation tends to occur. The concentration of the silica component is more preferably in the range of 0.5 to 5% by mass, still more preferably 0.5 to 3% by mass.

In the step (a), the pH of the aqueous water glass solution 1 is adjusted to a predetermined range using an ion exchange resin, and is aged. When an acid such as sulfuric acid is used for pH adjustment, an excessive silica network is formed by aging and tends to gel (solidify). On the other hand, the use of an ion exchange resin is desirable because it removes sodium ions in the aqueous water glass solution and suppresses the formation of an excessive silica network. In addition, the pH can be adjusted stably.

Examples of the pH adjustment method using an ion exchange resin include a method of bringing an aqueous solution of water glass into contact with a cation exchange resin. Specifically, an aqueous solution of water glass diluted to a predetermined concentration is brought into contact with a cation exchange resin to be dealkalized, and if necessary, brought into contact with an OH type strongly basic anion exchange resin to deanion. Can be done by. As the method of contacting, a batch method (a method of adjusting pH by mixing the water glass aqueous solution 1 and the ion exchange resin) in which the cation exchange resin is directly put into the aqueous solution of water glass and stirred and contacted, cation A method of passing an aqueous solution of water glass through a column filled with an exchange resin (a method of adjusting pH by passing an aqueous solution of water glass 1 through a column filled with an ion exchange resin). In the batch method, the ion exchange resin can be removed by filtration after pH adjustment. A method using a column is preferable because the operation is simple. Further, in pH adjustment, silica loss occurs during filtration in the batch method, but silica loss in the pH adjustment stage can be suppressed in a method using a column.

As the cation exchange resin, H-type strong acid cation exchange resin, weak acid cation exchange resin and the like can be used, and as a commercial product, Amberlite IR120B, IR124, 200CT, IRC76, FPC3500 manufactured by Organo Corporation are available. Can be mentioned. It is presumed that sodium ions and the like in water glass are removed and silica nuclei are generated by the above method.

In the step (a), the pH of the aqueous water glass solution 1 is adjusted to 2-5. Outside this range, there is a tendency to solidify during aging. The pH is preferably in the range of 2-4, more preferably in the range of 2.5-3.5.

In the step (a), aging is performed after pH adjustment, and an aging solution is prepared. The aging temperature is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and further preferably 70 ° C. or higher. The aging temperature is preferably 95 ° C. or lower, more preferably 90 ° C. or lower, and still more preferably 85 ° C. or lower. The aging time is preferably 0.5 to 24 hours, and more preferably 2 to 10 hours. If the aging temperature or aging time is less than the lower limit, the aging is insufficient and the generation of nuclei may not be sufficient. If the upper limit is exceeded, the tendency to gel will increase.

(Step (b-1), Step (b-2))
As a step subsequent to the step (a), “the pH of the mixed solution obtained by mixing the ripening solution obtained in the step (a) and the aqueous water glass solution 2 is adjusted to 9 to 11 using an ion exchange resin, and ripening is performed. Step (b-1) "or" Aging solution obtained in the above step (a) and an adjustment solution in which the pH of the water glass aqueous solution 2 is adjusted to 9 to 11 using an ion exchange resin, Step (b-2) of aging "is performed. Thereby, a silica dispersion is prepared.

As said water glass aqueous solution 2, the thing similar to the said water glass aqueous solution 1 can be used.
In the steps (b-1) and (b-2), the concentration of the silica component (SiO ₂ ) contained in the water glass aqueous solution 2 is preferably in the range of 2 to 30% by mass. If it is less than 2% by mass, the efficiency is poor, and if it exceeds 30% by mass, gelation tends to occur. The concentration of the silica component is more preferably in the range of 2 to 10% by mass, still more preferably 3 to 8% by mass.

The method of adjusting the pH of the mixed solution to 9 to 11 using an ion exchange resin in the step (b-1) and the method of adjusting the pH of the water glass aqueous solution 2 to 9 to 11 in the step (b-2) A method similar to the pH adjustment in step (a) can be used. More preferably, the pH is adjusted to 9.0 to 10.0. Even when this pH adjustment is performed by the batch method, silica loss occurs during filtration. Therefore, by changing the mixing order from step (b-1) to step (b-2), silica loss can be reduced and the silica yield is increased. The mixing in the steps (b-1) and (b-2) can be performed by a known method.

Aging is performed after pH adjustment, and the aging temperature is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and still more preferably 70 ° C. or higher. The aging temperature is preferably 95 ° C. or lower, more preferably 90 ° C. or lower, and still more preferably 85 ° C. or lower. The aging time is preferably 4 to 50 hours, more preferably 8 to 35 hours. If the aging temperature or aging time is less than the lower limit, aging is insufficient and silica having a desired particle size may not be generated. If the upper limit is exceeded, the possibility of gelation (solidification) increases.

A silica dispersion in which silica is dispersed can be prepared by the above-described production method.
The average primary particle diameter of silica contained in the silica dispersion is preferably 50 nm or less, more preferably 30 nm or less, and still more preferably 15 nm or less. The average primary particle diameter is preferably 5 nm or more, more preferably 6 nm or more, and further preferably 7 nm or more. Here, the size of the average primary particle size can be adjusted by the water glass aqueous solution, the above mixed solution, the pH of the adjusting solution, the concentration of the silica component, the aging temperature, the aging time, and the like. Within the above range, silica is uniformly dispersed, and the dispersion of zinc oxide can be promoted.
In addition, the average primary particle diameter of silica is measured by the same method as that for zinc oxide.

The method of mixing zinc oxide and silica dispersion, and the method of mixing the obtained mixture and rubber latex are not particularly limited, and can be performed by a known method.

In step (I), when zinc oxide and silica dispersion are mixed and then rubber latex is mixed, silica is 5 to 150 parts by mass (SiO ₂ equivalent) with respect to 100 parts by mass (solid content) of rubber. Thus, it is preferable to mix the silica dispersion. If the amount is less than 5 parts by mass, the amount of silica blended is small, so there is a possibility that the dispersion of zinc oxide cannot be promoted sufficiently by silica. If it exceeds 150 parts by mass, it will be difficult to obtain a uniform dispersion of silica in the rubber latex, and the uniform dispersion of silica in the composite after coagulating the compounded latex will be reduced, so that the dispersibility of zinc oxide will also be reduced. There is a risk. More preferably, it is 5-120 mass parts, More preferably, it is 10-100 mass parts, Most preferably, it is 12-50 mass parts, Most preferably, it is 15-40 mass parts.

(Process (II))
In step (II), the compounded latex obtained in step (I) is coagulated and then dried to produce a composite in which zinc oxide is uniformly dispersed in the rubber. There are acid coagulation, salt coagulation, methanol coagulation and the like as coagulation of the compounded latex, but acid coagulation, salt coagulation, or a combination thereof is preferable for uniformly coagulating zinc oxide. Examples of the acid for coagulation include sulfuric acid, hydrochloric acid, formic acid, acetic acid and the like. Examples of the salt include monovalent to trivalent metal salts (such as calcium salts such as sodium chloride, magnesium chloride, calcium nitrate, and calcium chloride).

Especially, coagulation | solidification of mixing | blending latex adjusts the pH of mixing | blending latex to 5-9 (preferably 6-8, more preferably 6.5-7.5) by addition of an acid or a salt, and solidifies solid content. It is preferable to be implemented. Thereby, the composite body in which zinc oxide is finely dispersed can be suitably produced.

The coagulated compounded latex is usually dried by a known method (such as an oven). When the rubber is kneaded with a biaxial roll or a banbury after drying, a composite in which zinc oxide is uniformly dispersed in the rubber matrix can be obtained.
In addition, the said composite_body | complex may contain another component in the range which does not inhibit the effect of this invention.

The composite obtained in the present invention can be used as a master batch. Also, a rubber composition obtained by mixing with other rubber compounding agents can be suitably used, and a rubber composition in which zinc oxide is uniformly dispersed can be obtained by including the composite. Examples of the rubber compounding agent include carbon black, silane coupling agent, stearic acid, antiaging agent, sulfur, vulcanization accelerator and the like generally used in the tire industry. The rubber composition may further contain a rubber component, zinc oxide, silica and the like in addition to the composite.

In the rubber composition, the total silica content is preferably 5 to 150 parts by mass and the total zinc oxide content is 0.1 to 10 parts by mass with respect to 100 parts by mass (solid content) of the total rubber. . The content of other compounding agents such as carbon black can also be set as appropriate.

The said rubber composition can be manufactured by the method etc. which knead | mixes said each component using rubber | gum kneading apparatuses, such as an open roll, a Banbury mixer, and a closed kneader, and vulcanize | curing after that. At the time of manufacture, the catalytic action of zinc oxide is effectively exhibited, and the vulcanization efficiency is increased, so that productivity can be improved. Further, the obtained rubber composition has required performance of the tire such as low fuel consumption, crack resistance, and wear resistance. Therefore, the rubber composition can be suitably used for each member (tread, sidewall, etc.) of the tire.

A pneumatic tire can be manufactured by a normal method using the rubber composition. That is, the rubber composition is extruded in accordance with the shape of each tire member such as tread and sidewall at an unvulcanized stage, molded by a normal method on a tire molding machine, and pasted together with other tire members. Together, an unvulcanized tire is formed. This unvulcanized tire can be heated and pressurized in a vulcanizer to produce a tire.

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

The various chemicals used in the examples are described below.
Natural rubber latex: high ammonia type (rubber solid content concentration 60 mass%)
Surfactant: teric 16A29 manufactured by Huntsman
Water glass: Water glass No. 3 manufactured by Fuji Chemical Co., Ltd. (Na ₂ O.nSiO ₂ .mH ₂ O, n = 3.2, silica component (SiO ₂ equivalent) content: 28% by mass)
Ion exchange resin: Amberlite IR-120B (H) HG (manufactured by Organo Corporation, cation exchange resin)
2 types of zinc white (Zinc oxide 1): 2 types of zinc white (average primary particle size: 500 nm) manufactured by Mitsui Mining & Smelting Co., Ltd.
Zinc oxide fine particles (zinc oxide 2): Zinc oxide (average primary particle size: 20 nm) manufactured by Wako Pure Chemical Industries, Ltd.
Carbon black: Dia Black I (ISAF) manufactured by Mitsubishi Chemical Corporation
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by EVONIK-DEGUSSA
Aroma oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Stearic acid: Anti-aging agent manufactured by NOF Corporation: NOCRACK 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Sulfur: Powder sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. NS: Noxera-NS (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Co., Ltd.

(Comparative Examples 1-3)
300 g of a water glass aqueous solution having a silica component content (silica concentration) of 1.5% by mass was prepared, and water was passed through a column packed with 100 g of an ion exchange resin over 45 minutes. The obtained adjustment liquid became pH 3.2. This was aged at 80 ° C. for 3 hours (aging solution A). On the other hand, 9.8 g of an ion exchange resin was added to 46.3 g of a water glass aqueous solution having a silica concentration of 6% by mass to adjust the pH to 9.5. The ion exchange resin was removed by filtration, and this was added to a part 108 g of the aging liquid A, stirred and mixed, and then aged at 80 ° C. for 24 hours.
To the obtained silica dispersion, 33 g of NR latex (solid content 60% by mass) is added, and after adding a surfactant, 1% by mass sulfuric acid is added to adjust to pH 7, and natural filtration is performed using filter paper # 2. Thereafter, it was dried in an oven at 40 ° C. to obtain a silica / rubber composite.
When the silica content of the obtained silica / rubber composite was determined by thermogravimetric analysis, it was 20 parts by mass with respect to 100 parts by mass (solid content) of rubber.
In the silica / rubber composite, in a roll mill, sulfur (1 part by mass), vulcanization accelerator (0.5 part by mass), and two types of zinc white (in Table 1) with respect to 100 parts by mass (solid content) of rubber. The blending amount shown: 100 parts by mass of rubber (solid content)) was added and kneaded for about 5 minutes to obtain an unvulcanized rubber composition (composite).

(Examples 1-4)
To the above silica dispersion after 24 hours at 80 ° C., two kinds of zinc oxide or zinc oxide fine particles (blending amount shown in Table 1: 100 parts by mass of rubber (solid content)) are added, and after stirring for about 1 hour, NR latex is added. An unvulcanized rubber composition (composite) was prepared in the same manner as in the comparative example except that the added point and the two types of zinc oxide were not added by a roll mill.

About the obtained composite_body | complex, the TEM observation and the change of a torque were measured with the following method, and the result was shown to FIGS.

(TEM observation)
Using the obtained composites (Comparative Examples 1 and 2, Examples 1 and 2), a thin piece having a thickness of about 100 nm was cut out using a microtome, and a transmission electron microscope (H-7100 manufactured by Hitachi, Ltd.) was cut. Was observed.

(Torque change)
In accordance with JIS K6300, a vulcanization test (vulcanization rate curve) in which a vulcanization test was performed at a measurement temperature of 150 ° C. using a vibration vulcanization tester (Orientec Curast Meter Co., Ltd.) and time and torque were plotted. )

From TEM observation, it was observed that the silica contained in the composites prepared in Examples and Comparative Examples had an average primary particle size of 8.5 nm.
From the TEM observation, it was found that in the examples, zinc oxide was well dispersed and silica was also well dispersed (FIGS. 2 to 4). In particular, in the example using zinc oxide fine particles, a large lump (about 100 nm) in which the zinc oxide fine particles are aggregated is not observed (FIG. 3), and only a few aggregated zinc oxide fine particles are observed. (FIG. 4), it turned out that it has disperse | distributed favorably. Although zinc oxide fine particles smaller than 20 nm were also observed, it was speculated that there was a possibility that the zinc oxide fine particles were eluted to reduce the particle size.
On the other hand, in the comparative example in which two kinds of zinc white were added by a roll mill (example added at the time of rubber kneading), a large lump in which two kinds of zinc white were aggregated was observed (FIG. 5).

It was found from TEM-EDX that zinc oxide was present on the silica (FIG. 6).

As a result of curast measurement, it was found that when 1.5 parts by mass of zinc oxide was blended, the better the dispersion of zinc oxide, the greater the torque (FIG. 7). Further, when 3 parts by mass of zinc oxide was blended, there was no significant difference in torque (FIG. 8). This was thought to be because zinc oxide was saturated.

As shown in FIG. 9, Example 4 in which 1.5 parts by mass of zinc oxide fine particles were blended had substantially the same maximum torque as Comparative Example 2 in which 3 parts by mass of zinc oxide was blended during conventional rubber kneading. From this result, it was found that the amount of zinc oxide used can be reduced to about half by mixing rubber latex and zinc oxide fine particles.

(Example 5, Comparative Example 4)
A composite (a) was produced in the same manner as in Example 3 except that sulfur and vulcanization accelerator were not added. Also, a comparative example was obtained except that sulfur and vulcanization accelerator were not added. In the same manner as in Example 3, a composite (b) was produced.

Next, chemicals other than sulfur and a vulcanization accelerator were kneaded using a 1.7 L Banbury mixer according to the formulation shown in Table 2. Next, using a roll, sulfur and a vulcanization accelerator were added to the obtained kneaded product and kneaded to obtain an unvulcanized rubber composition.
The obtained unvulcanized rubber composition was press vulcanized at 150 ° C. for 30 minutes to obtain a vulcanized product.
The obtained unvulcanized rubber composition and vulcanizate were evaluated as follows, and the results are shown in Table 2.

(Culast test)
A vulcanization test was performed at a measurement temperature of 150 ° C. using a vibration type vulcanization tester (curast meter) described in JIS K6300, and a vulcanization rate curve in which time and torque were plotted was obtained. Then, when the minimum value of torque on the vulcanization speed curve is ML, the maximum value is MH, and the difference (MH−ML) is ME, time T95 (vulcanization time (minutes)) to reach ML + 0.95ME is read. It was. In addition, vulcanization time can be shortened, so that T95 is small.

(Rolling resistance)
Using a viscoelastic spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.), tan δ of each compound (vulcanized product) was measured under the conditions of a temperature of 50 ° C., an initial strain of 10%, a dynamic strain of 2%, and a frequency of 10 Hz. The tan δ of the rubber test piece (reference test piece) of Comparative Example 4 was set to 100, and the index was expressed by the following formula (rolling resistance index). The larger the index, the better the rolling resistance characteristics (low fuel consumption).
(Rolling resistance index) = (tan δ of standard test piece) / (tan δ of each formulation) × 100

(Abrasion test)
Using a Lambourn abrasion tester, the Lambourn abrasion amount was measured under the conditions of a temperature of 20 ° C., a slip ratio of 20% and a test time of 2 minutes. Furthermore, the volume loss amount was calculated from the measured amount of lamborn wear, and the rubber loss index of the rubber test piece (reference test piece) of Comparative Example 4 was set to 100, and the volume loss amount of each formulation was displayed as an index according to the following formula. . It shows that it is excellent in abrasion resistance, so that an index | exponent is large.
(Lambourn wear index) = (Volume loss of standard specimen) / (Volume loss of each formulation) × 100

(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 4 were set to 100, respectively, and the TB and EB of each blend were indicated by an index according to the following formula. It shows that it is excellent in reinforcement property, so that TB index is large, and it is excellent in crack resistance, so that EB index is large.
(TB index) = (TB of each formulation) / (TB of reference specimen) × 100
(EB index) = (EB of each formulation) / (EB of reference specimen) × 100

From Table 2, Example 5 using the composite (a) produced by using the compounded latex in which rubber latex and zinc oxide are mixed is the fuel efficiency required for the tire, wear resistance, breaking strength, at break Elongation was provided and vulcanization characteristics were excellent. In particular, compared with Comparative Example 4 using the composite (b) in which zinc oxide was added during rubber kneading, the vulcanization time was shortened, the vulcanization reaction proceeded efficiently, and the crack resistance was excellent.

Claims (5)

A composite obtained by using a compounded latex in which rubber latex and zinc oxide are mixed. The composite according to claim 1, wherein the compounded latex is obtained by mixing a silica dispersion and the zinc oxide and further mixing the rubber latex. The composite according to claim 2, wherein the silica dispersion is produced by adjusting the pH of an aqueous water glass solution using an ion exchange resin. The composite according to any one of claims 1 to 3, wherein the zinc oxide has an average primary particle size of 100 nm or less. A step (I) of preparing the blended latex by mixing the rubber latex and the zinc oxide, and a step (II) of coagulating and drying the blended latex obtained in the step (I). The manufacturing method of the composite_body | complex in any one of 1-4.