JP3986129B2 - Process for producing modified carbon black-containing rubber composition for rubber reinforcement - Google Patents

Description

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【表２】

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【表３】

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【表４】

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【発明の効果】
表Ｉの結果から明らかなように、本発明に係るゴム補強用水分散シリカ変性カーボンブラック含有ゴム組成物の製造方法は、通常のカーボンマスターバッチと同じ方法で、しかも簡便かつ廉価に製造することができ、得られる組成物もカーボンブラックに比較し、高温域（６０℃）でのｔａｎδが低く、かつ耐摩耗性も低下しない。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a rubber masterbatch composition containing modified carbon black for rubber reinforcement (hereinafter sometimes simply referred to as “modified carbon”), and more specifically, a diene rubber and water-dispersed silica on the surface. The present invention relates to a method for producing a rubber masterbatch composition comprising a modified carbon black for reinforcing rubber to which is attached. This rubber-modified rubber-containing rubber composition for reinforcing rubber can be used for various rubber products such as belt conveyors, industrial rubber rolls, hoses, as well as tire materials such as tire cap treads and side treads.
[0002]
[Prior art]
In the rubber industry such as the tire industry, carbon black used for rubber reinforcement is preliminarily mixed with rubber using the wet carbon black masterbatch method to simplify the kneading process of carbon black into rubber. Improvements have been made in the dispersibility of carbon black in rubber (see, for example, JP 59-49247 A and JP 63-43937 A). By the way, in recent years, silica has been blended in place of carbon black due to the appearance of an excellent silane coupling agent. Silica has a characteristic that tan δ at a high temperature (around 60 ° C.) is low and tan δ at a low temperature (around 0 ° C.) is high compared to carbon black. For example, when used in a rubber composition for a tire tread, There is an advantage that a tire having low rolling resistance and high grip force can be manufactured. However, silica is inferior to carbon black in abrasion resistance and has low electrical conductivity. For example, when used for tires, the tires are charged during running, and noise is generated in electronic devices such as radios. In some cases, there are various problems such as malfunction.
[0003]
For example, Japanese Patent Publication No. 50-14254 and Japanese Patent Publication No. 7-30269 propose to improve the dispersibility and improve the weather resistance by coating the surface of a pigment or the like with silica. However, none mentions attaching silica to the surface of carbon black for reinforcing rubber. Furthermore, JP-A-8-277347 describes that silica is adhered to the surface of carbon black for reinforcing rubber, but does not mention industrially efficient production.
[0004]
When silica is blended into a rubber composition, since silica is difficult to disperse during kneading and requires a lot of labor for kneading, a master batch such as carbon black is desired. However, a satisfactory wet silica masterbatch has not been achieved so far because silica has a coagulation pH (about 4 to 7) different from the coagulation pH range of rubber latex (about 2.5 to 3).
[0005]
[Problems to be solved by the invention]
Therefore, the object of the present invention is to provide an excellent tan δ temperature dependency of silica, good wear resistance and workability, no problems due to low electrical conductivity, and simple and inexpensive production. Another object of the present invention is to provide a method for producing a rubber masterbatch composition of silica-modified carbon black for reinforcing rubber.
[0007]
[Means for Solving the Problems]
According to the present invention, (a) 100 parts by weight of latex of diene rubber component (as solid content) and (b) 10 to 250 parts by weight of modified carbon black modified and granulated by adding water-dispersed silica are mixed. Then, a method for producing a modified carbon black-containing rubber composition is provided, wherein the mixture is coagulated with a coagulant.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the inventors of the present invention have a completely new modified carbon for rubber reinforcement that has excellent tan δ temperature dependency of silica, has good wear resistance, and has no problems due to low electrical conductivity. By coagulating black with a diene rubber latex, a silica-containing rubber masterbatch composition was successfully obtained by a wet method.
[0009]
As a carbon black for rubber reinforcement used as a raw material for producing a silica-modified carbon black for rubber reinforcement used in the present invention, any carbon black conventionally used as a rubber reinforcing carbon for tires or the like is used. be able to. A preferred carbon black is a GPF to SAF grade rubber reinforcing carbon black produced by an oil furnace method, which can be used depending on the application of the rubber composition, or two or more kinds can be used in a blend.
[0010]
The modified carbon black for reinforcing rubber according to the present invention can be produced, for example, as follows. That is, carbon black for rubber reinforcement and water-dispersed silica are mixed to form a slurry. In order to improve the dispersibility of carbon black, an appropriate dispersant (for example, methanol, various surfactants) may be added. By setting this to, for example, a pH (near 7) in a region where water-dispersed silica particles cannot exist independently, modified carbon black in which silica is attached around carbon black can be obtained. The slurry thus obtained is mixed with rubber latex. The amount of silica attached to the carbon black surface is not particularly limited, but is preferably 0.1 to 25% by weight based on the weight of the silica-modified carbon black. If the amount of silica attached is too large, coagulation with rubber latex tends to be difficult. Further, after adding water-dispersed silica to carbon black, the carbon black granulated in the granulation step is slurried by a conventional method, and this can be mixed with a latex of a diene rubber component to obtain a mixture.
[0011]
The rubber latex-modified carbon black slurry mixture thus obtained can also be solidified by a conventional method to produce the rubber reinforcing modified carbon black-containing rubber composition of the present invention. As the coagulant, for example, an acid such as sulfuric acid and formic acid, an electrolyte such as sodium chloride, and a general coagulant such as a polymer flocculant can be used (they may be used in combination), and the addition amount is also conventional. Street.
[0012]
As the water-dispersed silica used in the present invention, those produced by mixing and reacting a silicate metal salt and an acid according to a conventional method can be used. The form of the water-dispersed silica (which may be sol or gel) and the concentration of silica in the water-dispersed silica are not particularly limited, but sol-like silica is preferred, and the sol is stable at 50,000 ppm. The following are appropriate. On the other hand, commercially available silica can also be used as the water-dispersed silica. Commercially available water-dispersed silica is generally produced by the ion exchange membrane method, and contains almost no impurities such as sodium salt as compared with the one produced by the above-mentioned method. It is characterized in that the state is maintained, and can be suitably used for producing the rubber composition of the present invention. The preferred diameter of the silica particles is 1 to 100 nm, and the sodium ion content is 1.0% by weight or less in terms of Na ₂ O.
[0013]
The water-dispersed silica sol is a state in which silica having a primary particle or a low-order structure is dispersed in water, and is usually stabilized in a basic state. In the present invention, in the production of the treated carbon black, for example, after adjusting to neutral conditions where the silica sol is gelled by addition of acid, the mixture is mixed with carbon black or mixed with carbon black and water-dispersed silica, and then added with acid. Carbon black and silica can be combined by adjusting to the sex condition. In addition, by simply mixing water-dispersed silica and carbon black and drying, silica gelation occurs during the drying process and complexation with carbon black occurs (at least a portion of the silica on the carbon black surface). Glue). The step of combining carbon black and silica by the method as described above may be a granulation step or after slurrying the carbon black.
[0014]
The feature of the present invention is that the above-mentioned water-dispersed silica is used as a silica source for adhering to carbon black. The rubber reinforcing modified carbon black disclosed by the present inventors in Japanese Patent Laid-Open No. 8-277347 is more industrial. Can be manufactured efficiently.
[0015]
According to the present invention, a rubber composition excellent in wear resistance, grip performance, rolling resistance and the like can be obtained by blending a modified carbon black for reinforcing rubber with a crosslinkable component such as a diene rubber. Examples of such crosslinkable rubber include natural rubber (NR), various butadiene rubbers (BR), various styrene-butadiene copolymer rubbers (SBR), polyisoprene rubber (IR), butyl rubber (IIR), and acrylo. Nitrilobutadiene rubber, chloroprene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber Chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber, urethane rubber and the like can be used alone or as a blend. Especially the ratio No.
[0016]
The rubber-reinforcing modified carbon black-containing composition used in the present invention contains 10 to 250 parts by weight, more preferably 15 to 200 parts by weight, of rubber-reinforcing modified carbon black per 100 parts by weight of the rubber component. If this blending amount is too small, it is impossible to blend the amount (10 parts or more) usually required for the rubber reinforcing modified carbon when used as various rubber products. On the other hand, if the amount is too large, the hardness becomes too high and the workability is lowered. In addition to the water-dispersed silica-modified carbon black, any carbon black or / and silica that is usually blended in the rubber composition can be used in combination with the rubber composition.
[0017]
In addition to the rubber, carbon black having water-dispersed silica attached to the surface, the rubber composition includes any compounding agent normally used in the rubber industry, such as sulfur, organic peroxide, softener, aging An inhibitor, a vulcanization accelerator, a filler, a plasticizer, a silane coupling agent, and the like can be appropriately blended within a range of a normal blending amount as necessary.
[0018]
The modified rubber black-containing rubber composition for rubber reinforcement according to the present invention can be produced by the same method as a normal wet carbon black masterbatch method. A slurry of carbon black with silica attached to the surface is prepared by the method as described above, and this is mixed with a diene rubber latex (for example, SBR latex) at an appropriate ratio. Subsequently, a coagulant (for example, a polymer flocculant, NaCl, etc.) conventionally used in the production of a carbon black master batch or the like is added to these and coagulated. The solidified rubber composition is separated from the aqueous phase, and moisture is removed by, for example, hot air drying to obtain a desired rubber master batch composition. In addition, an additive such as an antiaging agent process oil or a silane coupling agent can be added as necessary during the above steps.
[0019]
As described above, the modified carbon black for reinforcing rubber used in the present invention is produced, for example, by adhering water-dispersed silica to the surface of the carbon black in the carbon black slurry. To do. Therefore, the rubber composition of the present invention can also be produced by directly mixing this slurry with rubber latex. This eliminates the labor of kneading the silica with the rubber and improves the dispersion of the rubber reinforcing modified carbon black in the rubber. In addition, the rubber reinforcing modified carbon black is recovered from the slurry and dried. The process can be reduced and the manufacturing cost can be further reduced.
[0020]
In a preferred embodiment of the present invention, during the wet mixing, process oils such as aroma oils, paraffin oils, naphthenic oils, and / or synthetic plasticizers that have been conventionally used for rubber compounding, liquid rubbers, etc. 10 to 200 parts by weight of the liquid product per 100 parts by weight of the diene rubber can be blended.
[0021]
【Example】
Hereinafter, although an example and a comparative example explain the present invention further, it cannot be overemphasized that the scope of the present invention is not limited to these examples.
[0022]
Examples 1-7 and Comparative Examples 1-2
Preparation of modified carbon black for rubber reinforcement (for Example 1)
100 g of rubber reinforcing carbon black (N339) was used, and 2 liters of water-dispersed silica was added to form a mixed slurry. As water-dispersed silica, JIS No. 1 sodium silicate aqueous solution and dilute sulfuric acid in an amount to neutralize it are added to water adjusted to pH 10 with sodium hydroxide, and finally 0.5 wt% as SiO ₂ amount. A sol-like water-dispersed silica was obtained.
[0023]
The water-dispersed silica slurry of carbon black obtained above was heated to 90 ° C., and the pH was adjusted to 7, to obtain a slurry-like substance (solid content 5.2% by weight) containing the desired modified carbon black.
[0024]
Preparation of modified carbon black for rubber reinforcement (Examples 2 to 7)
Using commercially available water-dispersed silica (see Table III), modified carbon black for rubber reinforcement was produced as follows. Commercially available water-dispersed silica shown in Table III is appropriately diluted with non-granulated carbon black (N339) with water to equal the weight of carbon, and each silica content is 1 weight of the total amount of carbon black and silica. %, And granulated at about 80 ° C. with a normal carbon black granulator (barbed screw type). This was dried at about 105 ° C. to obtain modified carbon black for rubber reinforcement shown in Table II.
[0025]
Preparation of modified carbon black-containing rubber composition (Examples 1 to 7)
Next, the modified carbon black obtained above is made into a slurry (concentration 12.5 wt%), 200 g of the modified carbon black and 125 g of SBR1502 latex (concentration 41 wt%) are mixed, and this is mixed with saline (concentration 3 wt%) as a coagulant. 1,000 g was added and stirred at a temperature of 50 ° C. for 0.5 hour, followed by drying at 80 ° C. for 24 hours to obtain rubber-reinforced silica-modified carbon black-containing rubber compositions (master batches 1 to 7).
[0026]
Measurement of silica content of rubber-modified carbon black Modified carbon black sample was ashed in an electric furnace at 600 ° C, the ash was fluorinated, and the weight loss was deposited as silica. The silica content was 10% by weight and 1% by weight.
[0027]
According to the following composition, various rubber compositions were prepared by kneading with a Banbury mixer and a roll machine according to a conventional method (vulcanization conditions: 160 ° C. × 30 minutes). The results are shown in Table I.
[0028]
Recipe ────────────────────────
Diene rubber (SBR1502): 100 parts by weight ^{* 1}
Reinforcing filler (see Table I) 50 parts by weight ^{* 1}
Silane coupling agent ^{* 2} : 3 parts by weight ^{* 3}
Zinc flower (JIS 3): 3 parts by weight Stearic acid: 2 parts by weight anti-aging agent ^{* 4} : 2 parts by weight powdered sulfur: 2 parts by weight vulcanization accelerator ^{* 5} : 1 part by weight ───────── ───────────────
* 1) Wet masterbatch * 2) Si 69 (Degussa)
* 3) Not used when the reinforcing filler is carbon black.
* 4) Santoflex 13 (Monsant)
* 5) Santocure NS (Monsant)
[0029]
[Table 1]

[0030]
[Table 2]

[0031]
[Table 3]

[0032]
[Table 4]

[0033]
【The invention's effect】
As is apparent from the results in Table I, the method for producing a water-reinforcing silica-modified carbon black-containing rubber composition for reinforcing rubber according to the present invention is the same method as a normal carbon masterbatch, and can be produced simply and inexpensively. In comparison with carbon black, the resulting composition has a low tan δ at high temperature (60 ° C.) and does not deteriorate the wear resistance.

Claims (4)

(A) 100 parts by weight of a latex of a diene rubber component (as a solid content) and (b) 10 to 250 parts by weight of modified carbon black modified and granulated by adding water-dispersed silica are mixed. A method for producing a carbon black-containing rubber composition, characterized by coagulating with a coagulant. The production method according to claim 1 , wherein the water-dispersed silica contains silica particles having a diameter of 1 nm to 100 nm, and the sodium ion content is 1.0% by weight or less in terms of Na ₂ O. The manufacturing method of Claim 1 or 2 which further contains 5-150 weight part of aromatic process oil and / or high-viscosity oil in a mixture. The production method according to any one of claims 1 to 3, wherein the silica content is 0.1 to 25% by weight of the modified carbon black.