JP2014156534A - Method for producing wet master batch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a wet master batch which, when producing a wet master batch by mixing and coagulating a slurry solution and a rubber solution, can make dispersion of filler and the like into a composition generated from a coagulum sufficiently uniform.SOLUTION: Provided is a method for producing a wet master batch by mixing and coagulating a slurry solution containing filler and a rubber solution, wherein the slurry solution and the rubber solution are supplied to a mixing tank, stirred, mixed, and coagulated and, when a coagulated liquid containing a coagulum, which was aged in an aging tank, is taken out, a constant amount of the coagulated liquid is left in the aging tank and a coagulant of the next batch is supplied to the aging tank and stirred together with the residual coagulated liquid.

Description

  The present invention relates to a method for producing a wet masterbatch, and more particularly to a method for producing a wet masterbatch with improved blending ratio accuracy.

  Conventionally, a method using a wet masterbatch is known in order to improve the molding processability and dispersibility of a rubber composition containing a filler. This wet masterbatch is produced by mixing and coagulating a rubber solution, a slurry solution containing a filler such as carbon black and silica, and a coagulant, and the wet masterbatch containing these coagulates. By separating only the solid content from the batch, and dehydrating and drying the separated solid content, carbon black and the like can be uniformly dispersed in the rubber as compared with the case of kneading in a normal dry state. .

  Thus, in the production process of the wet masterbatch, in order to improve the productivity, a method of producing by a continuous process is common. For example, Patent Document 1 shows an operation process diagram in FIG. In addition, as a method of mixing and coagulating the slurry solution and the rubber solution, the slurry solution and the rubber solution are continuously supplied to the coagulation tank, and these are coagulated in the coagulation tank, and the coagulation containing the coagulated product made from these A method for continuously removing the liquid from the coagulation tank is described.

However, fillers such as carbon black and silica often have a specific gravity exceeding 1, and the specific gravity of the coagulum produced therefrom also exceeds 1, and these are water, cyclohexane, Because it is heavier than benzene etc., in the above prior art, the solidified material etc. will settle and accumulate at the bottom of the coagulation tank, and especially the carbon black variation in the wet masterbatch will increase. There was a possibility that the dispersibility of the resin would be lowered.
In order to cope with this, it has been proposed to stir the liquid in the tank so that it does not settle at the bottom, but this is not sufficient to prevent the accumulation of coagulated substances etc. at the bottom of the coagulation tank. There wasn't.

JP 2009-126978 A

  Therefore, in the present invention, in particular, when producing a wet master batch for mixing and coagulating a slurry solution and a rubber solution, the dispersibility of the filler and the like in the composition produced from the coagulated product is sufficiently uniform. The manufacturing method of the wet masterbatch which can be made.

  As a result of diligent investigations to achieve the above object, the present inventors have found that the amount of carbon black taken into the wet masterbatch is not uniform at the time of mixing, solidification, and ripening in the production of the wet masterbatch. A small amount of carbon black has a low specific gravity, is biased toward the upper part of the aging tank, and is often taken to the last when taking out the coagulating liquid from the bottom of the aging tank. After taking out, the next batch of solidified material is charged and operations such as stirring are carried out, so that the amount of carbon black taken up is small and the influence of solidified material with a low specific gravity is relatively small and stable. The present invention has been found to be able to be taken out and the present invention has been completed.

  The method for producing a wet masterbatch according to the present invention is to mix and solidify a slurry solution containing a filler and a rubber solution by supplying the slurry solution and the rubber solution to a mixing tank and stirring and mixing and coagulating. Furthermore, when taking out the coagulated liquid containing the coagulated product aged in the aging tank, the solidified liquid of the next batch is supplied to the aging tank in a state where a certain amount of coagulated liquid is left in the aging tank. And stirring and mixing.

  In such a wet masterbatch production method, more preferably, the amount of coagulation liquid left in the mixing tank is in the range of 10 to 30% of the treatment amount.

  In the present invention, when a slurry solution and a rubber solution are supplied to a mixing vessel and stirred, mixed and coagulated, and a coagulating solution containing coagulated material aged in the aging vessel is taken out, a certain amount of coagulating solution is put into the aging vessel. In the remaining state, supply the next batch of coagulated material to the aging tank and mix it with the remaining coagulating liquid to stir and mix, particularly using the variation in carbon black between the lower and upper parts in the aging tank based on the specific gravity of the carbon black Thus, the dispersion of the carbon black in the solidified product can be made sufficiently uniform.

It is process drawing which illustrates the process of a manufacturing method of a wet masterbatch, and a post-processing process. It is the schematic which shows the stirring apparatus of the wet masterbatch which mixes and solidifies a slurry solution and a rubber solution used for the manufacturing method of the wet masterbatch of this invention. It is an operation | movement process figure which shows an example of the manufacturing method of the wet masterbatch of this invention. It is an operation | movement process figure which shows an example of the manufacturing method of the conventional wet masterbatch.

Below, the manufacturing method of the wet masterbatch of this invention is demonstrated in detail, referring drawings.
FIG. 1 is a process diagram illustrating a process and a post-processing process of the method for manufacturing a wet masterbatch of the present invention.
In the figure, the overall process 20 includes a filler slurry solution preparation process 21 prepared by preparing a slurry solution in which a filler such as carbon or silica is dispersed, a natural rubber or synthetic rubber solution, a surfactant, and the like. A rubber solution compounding step 22 for preparing a rubber solution by stirring in a solvent such as water, and the coagulating liquid containing the coagulated product by mixing and coagulating the slurry solution and the rubber solution prepared in these steps A mixing / coagulation step 23 for forming a wet master batch, an aging step 24 for aging the coagulated master batch, a dehydration step 25 for sequentially discharging the aged master batch from the aging step and dehydrating, and drying the dehydrated solid content A drying step 26, and a molding step 27 for molding the dried solid content into a desired shape such as a granular shape or a bale shape to form a product.

  In the filler slurry solution preparation step 21, a known method can be used as a method for preparing the slurry solution (A), and is not particularly limited, but is a rotor-stator type high shear mixer, a high-pressure homogenizer, An ultrasonic homogenizer, a bead mill, a colloid mill, or the like can be used. For example, a slurry solution can be prepared by putting a predetermined amount of filler such as carbon black and water in a colloid mill and stirring at high speed for a certain time.

  In the slurry solution (A) used in the method for producing a rubber wet masterbatch, a filler is dispersed in a solvent. Examples of the solvent include water, alcohols such as methanol, ethanol, and isopropyl alcohol, and organic solvents such as aromatic, aliphatic, alicyclic, and halogenated hydrocarbon solvents, and water is preferable. These solvents may be used alone or as a mixture of plural kinds.

Here, as the slurry solution (A), carbon black, silica, or a material in which at least one filler represented by the general formula (I) is dispersed in water in advance can be used. In addition, these fillers may be used individually by 1 type, and 2 or more types may be mixed and used for them.
nM ₁ · xSiO _y · zH ₂ O (I)
[Wherein M ₁ is a metal selected from the group consisting of aluminum, magnesium, titanium, calcium and zirconium, an oxide or hydroxide of these metals, and a hydrate thereof, or a carbonate of these metals. N, x, y and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10]

The filler represented by the general formula (I), .gamma.-alumina, alpha-alumina, such as alumina _{(Al 2 O} 3), boehmite, alumina monohydrate such as diaspore _{(Al 2 O 3 · H 2} O ), Gibbsite, Bayerite, etc. Aluminum hydroxide [Al (OH) ₃ ], Aluminum carbonate [Al ₂ (CO ₃ ) ₂ ], Magnesium hydroxide [Mg (OH) ₂ ], Magnesium oxide (MgO), Magnesium carbonate (MgCO _3), talc _{(3MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O), titanium white _(TiO 2), titanium black _{(TiO 2n-1),} calcium oxide (CaO) , calcium hydroxide [Ca _(OH) 2], magnesium aluminum oxide _{(MgO · Al 2 O 3)} , clay _(Al 2 _{O 3} · SiO _2), kaolin _{(Al 2 O 3 · 2SiO 2} · 2H 2 O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O) Aluminum silicate (Al ₂ SiO ₅ , Al ₄ · 3SiO ₄ · 5H ₂ O etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ etc.), calcium silicate (Ca ₂ · SiO ₄ etc.), silicic acid Aluminum calcium (Al ₂ O ₃ · CaO · 2SiO ₂ etc.), magnesium calcium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ), zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO (OH) ₂ · nH ₂ O], zirconium carbonate _{[Zr (CO 3) 2]} , hydrogen to correct electric charge as various zeolites, Such as crystalline aluminosilicates including alkali metal or alkaline earth metal can be used. Preferably, M ₁ in the general formula (I) is at least one selected from aluminum metal, aluminum oxide or hydroxide, and hydrates thereof, or aluminum carbonate.

  Examples of the rubber solution (B) prepared in the rubber solution preparation step 22 include a rubber latex in which rubber component fine particles are dispersed in water, and a solution in which the rubber component is dissolved in an organic solvent. Examples of the organic solvent for dissolving the rubber component include aromatic, aliphatic, alicyclic, and halogenated hydrocarbon solvents. Among these, toluene and cyclohexane are particularly preferable. Here, the rubber component of the rubber wet masterbatch comprises at least one of natural rubber (NR) and synthetic diene rubber. Here, as the synthetic diene rubber, those synthesized by emulsion polymerization or solution polymerization are preferable. Specific examples of the synthetic diene rubber include polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber ( CR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR) and the like. Preferred are natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, and polybutadiene rubber, and more preferred are natural rubber and styrene-butadiene copolymer rubber. In addition, the said rubber component may be used individually by 1 type, and may combine 2 or more types.

  For the purpose of improving the stability of the rubber solution (B), a surfactant can be added, and examples thereof include anionic, cationic, nonionic and amphoteric surfactants, preferably anionic, It is a nonionic surfactant.

Next, FIG. 2 is a schematic diagram showing a stirring apparatus for a wet masterbatch that mixes and solidifies the slurry solution (A) and the rubber solution (B) in the mixing / coagulation step 23.
In the figure, the stirring device 1 includes a mixing tank 2 that contains the slurry solution (A), the rubber solution (B), and the coagulating liquid, and a radial flow that is disposed at the bottom of the mixing tank 2 with the axis of rotation directed vertically. A mold agitator 3; In addition, the slurry solution supply port 4 that supplies the slurry solution (A) prepared in the filler slurry solution preparation step 21 to the mixing vessel 2 and the rubber solution preparation step 22 are prepared at a position above the mixing vessel 2. The rubber solution supply port 5 for supplying the rubber solution (B) to the mixing tank 2 is further provided. The mixing tank 2 further has an outlet 6 for taking out a coagulated liquid containing a coagulated product formed by mixing and coagulation. It is provided at the lower part of the side wall of the mixing tank 2.

  And in this invention, using the stirring apparatus 1 comprised as mentioned above, a slurry solution (A) and a rubber solution (B) are supplied in the mixing tank 2 which accommodates coagulating liquid, and the stirrer 3 is supplied. While rotating, supply water, a coagulant, a solution containing various additives, etc., and stir, mix and coagulate, and after stirring, take out the coagulated liquid containing the produced coagulum from the outlet 6 To the aging tank. Further, when discharging from the aging tank, as shown in the operation process diagram of FIG. 3, the solidified liquid of the next batch is supplied to the aging tank in a state where a certain amount of the coagulating liquid is left in the aging tank. Mix with stirring.

  Although only the slurry solution (A) and the rubber solution (B) are stirred and mixed, they can be coagulated. However, the slurry solution (A) and the rubber are improved because the coagulation reaction is caused and promoted to improve the coagulation yield. In addition to the solution (B), a coagulant comprising an acid such as formic acid or sulfuric acid or a salt such as sodium chloride can be introduced into the mixing tank 2.

  In addition, from the viewpoint of improving the performance of wet master batches and rubber compositions using the same, surfactants, vulcanizing agents, anti-aging agents, coloring agents, dispersing agents, etc. are appropriately selected as necessary. Can be added.

  In such a wet masterbatch production method, more preferably, the amount of coagulation liquid left in the aging tank is in the range of 10 to 30% of the treatment amount.

  By setting it as this range, the liquid level of the aging tank can be kept high, and the reduction in the stirring ability that occurs at the low tank level can be prevented, so that the dispersion of carbon black can be prevented.

  Next, any means may be used in the dewatering step 25. For example, a metal mesh, a centrifugal dewatering device, a vacuum dewatering device, a pressure dehydrator such as a filter press, a metal roll, a rubber kneader, a screw type extrusion An air dryer, a hot air dryer, a vacuum dryer, a freeze dryer or the like can be used.

  In the drying step 26 for drying the dehydrated solid content, a normal dryer such as a vacuum dryer, an air dryer, a drum dryer, a band dryer or the like can be used, but in order to further improve the dispersibility of the filler, It is preferable to perform drying while applying a mechanical shearing force. Thereby, rubber excellent in processability, reinforcement, and low fuel consumption can be obtained. Although this drying can be performed using a general kneader, a continuous kneader such as a twin screw extruder can be used from the viewpoint of industrial productivity.

  The solid content produced by such a production method can be molded into a desired shape such as granular or veiled and used in a rubber composition. This is due to the factor of wet mixing and the shape factor of fine particles, It is excellent in dispersibility, and it can improve rubber properties such as reduction of energy loss and wear / durability.

  Further, the rubber composition can be produced in accordance with a conventional method for tire parts such as a tread, a base, a side, a ply, and a belt. A tire using the rubber composition can improve fuel efficiency, fracture characteristics, and wear resistance.

  The carbon black content was evaluated for each of the example batch and the comparative example batch, using the operation process diagram of the wet master batch production method shown in the figure.

(Example batch)
In a coagulation tank, the carbon black slurry liquid and natural rubber latex diluted to 15 to 25% by weight were mixed with stirring, and then the crumb was coagulated by adjusting the pH to 4.7 ± 1.0 with formic acid, Move to another tank B and age. When discharging the ripened crumb, stop discharging at a tank level of 10-30% and restart the discharge after the next batch is charged.
The discharged crumb was dried in a subsequent process and then formed into a bale having a constant weight, and the carbon black content was measured in units of the bale.

(Comparative example batch)
In a coagulation tank, the carbon black slurry liquid and natural rubber latex diluted to 15 to 25% by weight were mixed with stirring, and then the crumb was coagulated by adjusting the pH to 4.7 ± 1.0 with formic acid, Move to another tank B and age. When discharging the ripened crumb, the tank level is set to 0%, and after the next batch is charged, the discharging is resumed.
After discharging, the carbon black content was measured in the same manner as in the example.

(Carbon black content)
The master batch used for the measurement is 1 g, and the weight of the magnetic crucible is accurately weighed in units of 0.1 mg with a precision balance. The master batch is placed in a magnetic crucible and baked in an electric furnace set at 750 ° C. for 5 minutes 30 seconds to remove carbon black. After taking it out of the electric furnace and air-cooling for 15 minutes, it is further cooled in a desiccator for 30 minutes. The weight of the magnetic crucible containing the master batch after cooling is measured, and the weight ratio of the master batch before and after removing the carbon black is calculated. here,
Weight of masterbatch before carbon black removal / weight of masterbatch after carbon black removal = (carbon black content (%) / (100 + carbon black content (%)))
Therefore, the carbon black content is calculated from this equation.
When carbon black is uniformly dispersed, the carbon black content is 43%.

(Evaluation results)
As mentioned above, the difference between the carbon black content measured in units of veil and the carbon black content (43%) when the carbon black is uniformly dispersed is ± 1.5 points or less. The rejection rate was measured for each of the example batch and the comparative example batch. The results are shown in Table 1.

  From the results of Table 1, the failure rate of the example batch was significantly reduced compared to the comparative example batch, and a master batch could be stably produced with the intended carbon black content.

DESCRIPTION OF SYMBOLS 1 Stirring apparatus 2 Mixing tank 3 Stirrer 4 Slurry solution supply port 5 Rubber solution supply port 6 Outlet 20 Overall process 21 Filler slurry solution preparation process 22 Rubber solution preparation process 23 Mixing / coagulation process 24 Aging process 25 Dehydration process 26 Drying Process 27 Molding process

Claims (2)

In a method for producing a wet masterbatch by mixing and solidifying a slurry solution containing a filler and a rubber solution,
When the slurry solution and the rubber solution were supplied to a mixing tank and stirred, mixed and coagulated, and a coagulating liquid containing coagulated material aged in the aging tank was taken out, a certain amount of coagulating liquid was left in the aging tank. In the state, the coagulated material of the next batch is supplied to an aging tank, and stirred and mixed together with the residual coagulating liquid. The method for producing a rubber wet masterbatch according to claim 1, wherein the amount of the coagulation liquid left in the aging tank is in the range of 10 to 30% of the treatment amount.

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