JP3946222B2 - Manufacture of natural rubber / carbon black masterbatch - Google Patents

Description

  The present invention relates to the production of a natural rubber / carbon black masterbatch from natural rubber latex, and more specifically, to produce a natural rubber / carbon black masterbatch that has good productivity and thermal efficiency and suppresses deterioration of rubber quality from natural rubber latex. And a natural rubber / carbon black masterbatch obtained therefrom.

  At present, natural rubber is shipped in the form of a sheet (RSS) or a block (TSR) obtained by manually collecting sap from a rubber tree, filtering and coagulating the latex. Thus, even at the present time when the importance of natural rubber is increasing, the current situation is that rubber is still manufactured from rubber latex with the help of human hands. Also, processes such as latex coagulation process, water washing process, and drying process, especially the drying process, have a great influence on the viscosity of the product of the resulting rubber. There are things that are not enough. From this viewpoint, Patent Document 1 proposes a manufacturing method capable of improving productivity and quality.

  On the other hand, natural rubber (NR) carbon masterbatch is difficult to mix in a slurry state due to instability of latex. Patent Document 2 discloses a method of making an NR master batch by simultaneously spraying and solidifying NR latex and carbon black slurry, and removing water while mixing. However, this method is kneaded at a high temperature as a drying step, so that although the dispersibility of carbon black is good, there remains a problem in rubber physical properties due to thermal history.

JP 2003-26704 A JP 2000-507892 A

  In the production of a natural rubber / carbon black masterbatch from natural rubber latex, the present invention greatly improves workability and thermal efficiency, and the resulting masterbatch may cause thermal degradation or gel of the rubber that may be generated by conventional heat drying. An object of the present invention is to provide a method for producing a natural rubber / carbon black masterbatch with excellent quality by suppressing the conversion.

According to the invention, a natural rubber latex, and a water slurry of the carbon black comprising carbon black of the rubber solid content to 200 parts by weight per 100 parts, by injection dried under an atmosphere of a shock wave by the pulse combustion natural In producing a rubber / carbon black masterbatch , 1 to 30% by weight of the surfactant of carbon black is first blended with at least one of natural rubber latex or water slurry of carbon black, and then at least two raw material supply routes. Natural rubber latex and carbon black slurry are supplied separately from each other, converged in one path, then sprayed into a shock wave atmosphere by pulse combustion and dried, natural rubber / carbon black master A method of manufacturing a batch is provided.

According to the present invention, also, the natural rubber latex, and a water slurry of carbon black, when jetted dried atmosphere of a shock wave by the pulse combustion to produce a natural rubber / carbon black master batch, firstly, natural rubber latex Alternatively, at least one of the carbon black slurries is blended with a water-soluble polymer, and then natural rubber latex and carbon black slurry are separately supplied from at least two raw material supply paths and converged into one path, followed by pulse combustion. There is provided a method for producing a natural rubber / carbon black masterbatch, characterized in that it is sprayed and dried in a shock wave atmosphere.

According to the present invention, a natural rubber latex and a carbon black water slurry are further mixed with a surfactant or a water-soluble polymer in at least one of the natural rubber latex or the carbon black water slurry, and then mixed and dried to form a natural rubber. / A device for producing a carbon black masterbatch, wherein the surfactant or water-soluble polymer is mixed, and the natural rubber latex and carbon black water slurry raw material liquids are supplied separately, and the supply of each pump control mechanism for controlling the ratio, by spraying in an atmosphere of a shock wave by the pulse combustion after the starting solution converges at least two raw material liquid supply path and the raw material liquid supply path to a path for supplying at any ratio An apparatus for producing a masterbatch with a pulse combustor to be dried is provided.

According to the invention, also in place of the conventional processes such as coagulation and natural coagulation by acid or the like, since the drying and slurry instantly comprising natural rubber latex and carbon black was fed separately with pulse combustion, productivity In addition, a significant improvement in thermal efficiency is achieved, and the thermal degradation of natural rubber and gelation of natural rubber that occur in conventional heat drying are suppressed, making it much easier to control the quality of the masterbatch and the gel. By suppressing the conversion, the viscosity of the natural rubber is reduced, and the subsequent treatment of the natural rubber such as the rubber mastication step can be simplified as compared with the conventional method.

  According to the present invention, the natural rubber latex and carbon black water slurry is dried by using a pulse combustor for generating a pulse shock wave described in, for example, Japanese Patent Publication No. 6-28681. Make a batch. In the present invention, using such a pulse combustor, an aqueous slurry of a natural rubber (NR) latex having a solid content concentration of 60% by weight or less and a carbon black (CB) of 20% by weight or less, preferably NR / CB (solid weight ratio) = 100/1 to 100/200, preferably 50 to 1200 Hz, more preferably 200 to 1000 Hz, preferably 140 ° C. or less, more preferably 40 to 100 ° C. The object can be achieved by spray drying latex into the chamber.

  The solid content concentration of the mixture of natural rubber latex and carbon black slurry to be dried according to the present invention is preferably 60% by weight or less, more preferably 10 to 50% by weight. If the solid content is too high, the viscosity of the natural rubber latex increases and the stability decreases, so when it is put into the pulse shock wave dryer, it solidifies inside the transport pipe or is injected well into the combustion chamber. There is a possibility that problems such as not being broken occur. If the solid content concentration is too low, there is no problem with the drying itself, but it is not practical because the amount of treatment that can be dried per unit time is reduced.

The present inventors, is injected under the shock wave to the drying device provided with a pulse combustor and an aqueous slurry of natural rubber latex and carbon black was fed separately generated by the pulse combustion atmosphere, the solvent (water, organic The present inventors have found that a masterbatch can be produced in a short time and at a low cost without causing deterioration or gelation of the polymer by removing the solvent) and drying it instantaneously. A method of injecting a natural rubber latex, a water slurry of carbon black in an atmosphere of a shock wave by the pulse combustion, natural rubber latex and a carbon black slurry fed separately respectively, were encountered at a constant rate just prior to injection This is sprayed from one nozzle. The carbon black to be used is not particularly limited, and any carbon black can be used. The viscosity at 25 ° C. of the mixed liquid before drying thus treated is preferably 3000 mPa · s or less, more preferably 2000 mPa · s or less, and particularly preferably 1000 mPa · s or less. And drying defects can be effectively prevented.

  As described above, according to the method of the present invention, since the drying of the wet masterbatch containing carbon black, which has been very time-consuming in the past, becomes instantaneous, the natural rubber / carbon black masterbatch can be processed with industrially sufficient processing capacity. It can be manufactured.

In drying by pulse combustion, if necessary, a vulcanizing agent, vulcanization accelerator, antioxidant, metal oxide, mixed fatty acid, a resin, a rubber compounding agents commonly incorporated into the rubber composition such as oil By drying by the method of the present invention, it is possible to greatly omit the kneading step of the compounding agent into rubber, which has been conventionally performed by a Banbury mixer, a kneader, etc. become able to.

  In the first aspect of the present invention, the natural rubber latex and / or carbon black slurry is 1 to 30% by weight, preferably 3 to 20% by weight, based on the weight of the preliminarily carbon black before drying by pulse combustion. The desired master batch can be obtained by uniformly mixing and drying the surfactant. By using a surfactant, it is possible to improve the stability of a mixed liquid of NR latex and carbon black that is gelled only by mixing, and to make a master batch that achieves uniform dispersion. Also, by pulse burning drying, drying with less molecular cutting and heat history can be obtained, and master batches showing very good physical properties can be obtained, and other rubber compounding agents can be blended together and dried The compounding of these compounding agents in the subsequent process can be omitted, and a significant improvement in productivity can be achieved.

  The surfactant (emulsifier) that can be used in the present invention is not particularly limited, and examples thereof include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. In particular, nonionic surfactants and anionic surfactants are preferably used. Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, sugar fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyhydric alcohol fatty acid ester, polyoxyethylene fatty acid ester. , Polyoxyethylene alkylamine, alkylalkanolamide, and the like. Examples of the anionic surfactant include alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, naphthalene sulfonate, alkyl sulfosuccinate, Examples thereof include alkyl diphenyl ether disulfonate, fatty acid salt, polyvalent carboxylate, alkyl sulfate triethanolamine, alkenyl succinate, alkyl phosphate ester salt, polyoxyalkylene phosphate ester salt and the like.

According to a second aspect of the present invention, the natural rubber latex and / or carbon black slurry is mixed with a water-soluble polymer in advance and uniformly mixed before drying by pulse combustion, so that the natural rubber latex and carbon are mixed. A desired master batch can be obtained by separately supplying the black slurry to a drying apparatus equipped with a pulse combustor and drying the slurry . The water-soluble polymer is used in an amount of 1 to 30% by weight, more preferably 3 to 20% by weight, based on the weight of the carbon black. With such a mixture, a mixture of NR latex and carbon black that gels only by mixing. It is possible to create a masterbatch that improves the stability of the material and achieves uniform dispersion. Further, by performing pulse combustion drying, drying with less molecular cutting and thermal history can be performed, and very good physical properties can be exhibited.

  The water-soluble polymer used in the present invention is not particularly limited as long as it is water-soluble. For example, starch such as corn starch, natural polysaccharides such as mannan and pectin, seaweed such as agar and alginic acid, various gums, dextran and pullulan Polysaccharides derived from microorganisms, proteins such as glue and gelatin, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, synthetic polymers such as polyacrylic acid, polyacrylamide, polyvinyl alcohol, polyethyleneimine, polyethylene oxide, and polyvinylpyrrolidone can be used. Particularly preferred water-soluble polymers are polyvinyl alcohol (PVA) or water-soluble cellulose derivatives or salts thereof. Among the polyvinyl alcohols, sulfonic acid-modified polyvinyl alcohol is more preferable, and a mixed liquid having further excellent emulsion stability can be obtained. Of the water-soluble cellulose derivatives, carboxymethyl cellulose (CMC) or a salt thereof is particularly preferable, and those having a degree of etherification of 0.5 to 1.6, more preferably 0.6 to 1.5 are more preferable. This is because carboxymethyl cellulose (CMC) is particularly superior in emulsification stability than ordinary emulsifiers and can provide a stable mixed solution, and the cellulose derivative has a very low environmental impact and high safety. .

According to the third aspect of the present invention, for example, as shown in FIG. 1, an apparatus for mixing and drying a raw material liquid (natural rubber latex and carbon black slurry) of at least two kinds of solid substances or dispersions. A pump for supplying at least two kinds of raw material liquids, a control mechanism for controlling a supply ratio of each pump, at least two raw material liquid supply paths for supplying at least two kinds of raw material liquids in an arbitrary ratio, and the two Natural rubber latex and carbon black slurry and one or both of them using a drying apparatus equipped with a pulse combustor that sprays and drys under a shock wave atmosphere by pulse combustion after converging the raw material liquid supply path into one path to a surfactant or water-soluble polymer dispersion is added by introducing a separate raw material liquid supply path is dried by pulse combustion However, it is suitable for mass production but not for small and multi-product production, as in the method of mixing and drying slurry of latex and carbon black. By controlling the supply ratio, there is a feature that a master batch or a composition having an arbitrary mixing ratio can be freely set and dried.

In particular, the method of the present invention is very effective in preparing a master batch of a mixed solution of natural rubber latex and carbon black that gels in several seconds to several tens of seconds after mixing. Drying with less molecular cutting and thermal history is possible. In addition, you may add emulsifiers, such as surfactant, PVA, or a water-soluble cellulose derivative, to either as needed.

According to the present invention, when producing a master batch by mixing and drying a natural rubber latex and an aqueous slurry of carbon black, the natural rubber latex and the carbon black slurry are separately supplied from at least two raw material supply paths. Then, after converging it into a single path, it is sprayed and dried in a shock wave atmosphere by pulse combustion to produce a masterbatch. The time from when this raw material supply path is converged to one and after being injected into the atmosphere of the shock wave by pulse combustion is preferably 0.1 to 10 seconds, more preferably 1 to 5 seconds. If this time is too long, there is a risk of solidifying inside the nozzle before jetting, which is not preferable.
The viscosity of the mixed solution of the raw material latex and the carbon black slurry at 25 ° C. is preferably 3000 [mPa · s] or less, more preferably 100 to 2000, respectively.

  The frequency of pulse combustion is preferably 50 to 1200 Hz, and the temperature of the drying chamber for injecting the latex is preferably 140 ° C. or less, more preferably 40 to 100 ° C. According to the present invention, as shown in FIG. 1, a control mechanism that automatically controls the supply ratio of each pump that supplies raw material liquids I and II is provided, and at least two raw materials are supplied at an arbitrary ratio. A desired result is obtained by having two or more raw material supply paths, converging them into one, and then spraying and drying in an atmosphere of shock waves by pulse combustion. FIG. 2 shows the structure of a conventional injector, and FIGS. 3 and 4 show the structure of a preferred embodiment of the injector according to the present invention.

Examples of the present invention will be described below, but it goes without saying that the scope of the present invention is not limited to these examples.
Examples 1 to 4 and Comparative Example 1
According to the formulation shown in Table I, pulse combustion drying was performed and a stabilization test was performed. Pulse combustion drying was performed by adding a surfactant to the carbon black slurry at a frequency of 1000 Hz and a temperature of 60 ° C. using a high pulcon manufactured by Partec. The results are shown in Table I. In Comparative Example 1, gelation occurred immediately after mixing the natural rubber latex and the carbon black slurry, and a drying test could not be performed.

Stabilization test: Immediately after the production of the produced master batch and after standing at room temperature for 24 hours, the following criteria were observed and evaluated.
A: Maintains a uniform liquid state, and no thickening or gel is observed.
○ ... Although it thickens slightly, it remains liquid.

Examples 5 to 8 and Comparative Example 2
Next, using the carbon master batches of Examples 1 to 4 obtained above, the rubber physical properties were evaluated according to the formulations shown in Table II. That is, in the formulation shown in Table II, the vulcanization accelerator and the component excluding sulfur were kneaded for 3 minutes (mixed in Comparative Example 2 for 5 minutes) with a 1.7 liter Banbury mixer to obtain a master batch. A vulcanization accelerator and sulfur were kneaded with this master batch with an 8-inch open roll to obtain a rubber composition. The obtained unvulcanized rubber composition was vulcanized in a 15 × 15 × 0.2 cm mold at 150 ° C. for 30 minutes to obtain a vulcanized rubber sheet, and rubber physical properties were measured by the following test methods. The results are shown in Table II. The weight average molecular weight was measured and the results are shown in Table II.

300% modulus (MPa): Measured according to JIS K-6251 (JIS No. 3 dumbbell) Breaking strength: Measured according to JIS K-6251 (JIS No. 3 dumbbell) Break elongation: JIS K-6251 (JIS No. 3 dumbbell) Weight average molecular weight (GPC method): The weight average molecular weight (Mw) of the solvent-soluble components of the carbon black master batches of Examples and Comparative Examples was measured using GPC (Gel Permeation Chromatography).

Examples 9-12 and Comparative Example 3
According to the formulation shown in Table III, a master batch was prepared by adding and mixing the water-soluble cellulose derivative to the carbon black slurry at a frequency of 1000 Hz and a temperature of 60 ° C. using a high pulcon manufactured by Partec. The stability test of the obtained master batch was performed according to the following criteria, and the results are shown in Table III. In Comparative Example 3, gelation occurred immediately after mixing the natural rubber latex and the carbon black slurry, and a drying test could not be performed.

Stabilization test: Immediately after the production of the produced master batch and after standing at room temperature for 24 hours, the following criteria were observed and evaluated.
A: Maintains a uniform liquid state, and no thickening or gel is observed.
○ ... Although it thickens slightly, it remains liquid.
Δ: Viscosity is considerably increased and fine gel is observed, but spraying is possible.

Examples 13 to 16 and Comparative Example 4
Next, using the carbon master batches of Examples 9 to 12 obtained above, the rubber physical properties were evaluated with the formulations shown in Table IV. That is, in the formulation shown in Table IV, the components other than the vulcanization accelerator and sulfur were kneaded with a 1.7 liter Banbury mixer for 3 minutes (mixed in Comparative Example 4 for 5 minutes) to obtain a master batch. A vulcanization accelerator and sulfur were kneaded with this master batch with an 8-inch open roll to obtain a rubber composition. The obtained unvulcanized rubber composition was vulcanized in a 15 × 15 × 0.2 cm mold at 150 ° C. for 30 minutes to obtain a vulcanized rubber sheet, and rubber physical properties were measured by the following test methods. The results are shown in Table II. The results are shown in Table IV.

300% modulus (MPa): Measured according to JIS K-6251 (JIS No. 3 dumbbell) Breaking strength: Measured according to JIS K-6251 (JIS No. 3 dumbbell) Break elongation: JIS K-6251 (JIS No. 3 dumbbell) Measured according to

According to the method for producing a masterbatch from a natural rubber latex and a carbon black slurry according to the present invention, a surfactant or a water-soluble polymer is blended into at least one of the natural rubber or the water slurry of carbon black, and these are then added at least. Natural rubber / carbon black masterbatch is manufactured by supplying separately from two raw material supply channels and spraying under shock wave atmosphere by pulse combustion to remove solvent and instantly dry natural rubber latex and carbon black slurry The workability and thermal efficiency of the masterbatch can be improved, and the quality of the masterbatch obtained is less likely to cause thermal degradation and gelation, and the masterbatch production can be greatly simplified. Mixing time of rubber by mixer etc., energy can be reduced, It is useful as a manufacturing method of Tana masterbatch.

It is explanatory drawing which shows an example of the pulse combustion drying apparatus of this invention. It is drawing which shows an example of the structure of the injector part of the conventional pulse combustion drying apparatus. It is drawing which shows an example of the structure of the injector part of the pulse combustion drying apparatus of this invention. It is drawing which shows the other example of the structure of the injector part of the pulse combustion drying apparatus of this invention.

Claims (12)

Natural rubber latex, the carbon black comprising carbon black rubber solids 1-200 parts by weight per 100 parts by weight of a water slurry, by injection dried under an atmosphere of a shock wave natural rubber / carbon black master batch by pulse combustion First, a surfactant of 1 to 30% by weight of carbon black is blended into at least one of natural rubber latex or water slurry of carbon black, and then natural rubber latex and carbon are fed from at least two raw material supply paths. A method for producing a natural rubber / carbon black masterbatch, characterized in that the black slurry is supplied separately, converged in one path, and then sprayed and dried in a shock wave atmosphere by pulse combustion.   The method for producing a masterbatch according to claim 1, wherein the surfactant is a nonionic surfactant or an anionic surfactant.   The method for producing a masterbatch according to claim 1 or 2, wherein the frequency of pulse combustion is 50 to 1200 Hz, and the temperature of the drying chamber in a shock wave atmosphere by pulse combustion injecting latex is 140 ° C or lower. Natural rubber latex, and a water slurry of carbon black, when jetted dried atmosphere of a shock wave by the pulse combustion to produce a natural rubber / carbon black master batch, firstly, of natural rubber latex or carbon black slurry on at least one After blending a water-soluble polymer, natural rubber latex and carbon black slurry are separately supplied from at least two raw material supply routes, converged into one route, and then injected into a shock wave atmosphere by pulse combustion. A method for producing a natural rubber / carbon black masterbatch, characterized by being dried.   The method for producing a masterbatch according to claim 4, wherein the water-soluble polymer is polyvinyl alcohol (PVA), a water-soluble cellulose derivative or a salt thereof.   The method for producing a masterbatch according to claim 5, wherein the water-soluble cellulose derivative has a degree of etherification of 0.5 to 1.6.   The manufacturing method of the masterbatch of any one of Claims 4-6 whose frequency of pulse combustion is 50-1200Hz, and the temperature of the drying chamber which injects latex is 140 degrees C or less.   The masterbatch according to any one of claims 1 to 7, wherein the time from when the raw material supply path is converged to one and before injection into a shock wave atmosphere by pulse combustion is 0.1 to 10 seconds. Manufacturing method.   The method for producing a master batch according to any one of claims 1 to 8, wherein the natural rubber latex and the water slurry of carbon black each have a viscosity at 25 ° C of 3000 [mPa · s] or less.   The method for producing a masterbatch according to claim 8 or 9, wherein the frequency of pulse combustion is 50 to 1200 Hz, and the temperature of the drying chamber for injecting latex is 140 ° C or lower. A natural rubber latex and carbon black water slurry is mixed with a surfactant or a water-soluble polymer in at least one of the natural rubber latex or carbon black water slurry, and then mixed and dried to produce a natural rubber / carbon black masterbatch. an apparatus, wherein the surfactant or raw liquid pump each supplied separately of the natural rubber latex and carbon black slurry in water after mixing the water-soluble polymer, a control mechanism for controlling the feed ratio of the pumps, the At least two raw material liquid supply paths for supplying the raw material liquid at an arbitrary ratio, and a pulse combustor for converging the raw material liquid supply path into one path and then spraying and drying in an atmosphere of shock waves by pulse combustion Masterbatch manufacturing equipment. The apparatus for producing a masterbatch according to claim 11 , wherein the time from when the raw material supply path is converged to one and after being injected into a shock wave atmosphere by pulse combustion is 0.1 to 10 seconds.

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