JP5250206B2 - Method for producing natural rubber and / or synthetic isoprene rubber masterbatch using microbially decomposed powder rubber - Google Patents

Description

  The present invention relates to a method for producing a natural rubber and / or synthetic isoprene rubber masterbatch using a microbially decomposed powder rubber and a rubber composition containing the same.

  Waste tires have a higher recovery rate than ordinary plastic products, and are reused as fuel, especially in cement factories. However, with the recent increase in environmental problems, there is a demand for an improvement in the so-called material recycling rate in which rubber pieces or rubber powder obtained by cutting or crushing waste tires are reused. In addition to the mechanical crushing method at room temperature, such as a roll crushing method, there are a freezing crushing method that crushes after freezing with liquid nitrogen or the like, and a water hammer crushing method that uses ultra-high pressure water, Attempts have been made to produce fine particles at low cost.

  On the other hand, in order to mix powder rubber with unvulcanized rubber and use it as a vulcanized rubber product, it is important to vulcanize and bond powder rubber and new unvulcanized rubber. Recycled rubber made by mixing, desulfurizing by heating and making into a sheet with a roll has been used for a long time. Various desulfurization methods for the surface of the powder rubber have been proposed. For example, there is a method in which a large shear force is applied to the powder rubber by a twin screw extruder or the like to pulverize and desulfurize. However, these methods have a drawback in that the energy cost is high because the treatment temperature is high and the treatment is performed with a high shearing force.

Japanese Patent Laid-Open No. 11-236464

  Accordingly, it is an object of the present invention to provide a method having a low energy cost for treating rubber pieces or rubber powder, and further providing a method for recycling the product obtained by the treatment.

Therefore, in order to solve the above problems, the present inventors diligently studied. As a result, a slurry obtained by decomposing a specific powdered rubber with a specific microorganism dispersed in water, a natural rubber latex and / or a synthetic isoprene rubber latex By mixing, a natural rubber and / or synthetic isoprene rubber wet masterbatch was obtained. Furthermore, the present inventors have found that a rubber composition containing a natural rubber and / or a synthetic isoprene rubber master batch obtained by drying the natural rubber wet master batch maintains high physical properties, thereby completing the present invention. It came to.

The present invention comprises the following (1) to (11) .
(1) and the slurry solution obtained by dispersing in advance in water a powder rubber was decomposed by the microorganism, the production method of natural rubber you mixed natural rubber latex and / or synthetic isoprene rubber latex and / or synthetic isoprene rubber wet master batch Because
The natural rubber characterized in that the powdered rubber decomposed by the microorganism is a powdered rubber containing polyisoprene rubber, which is decomposed by BS-HA strain (FERM BP-10750) which is an actinomycete belonging to the genus Nocardia. Manufacturing method of rubber and / or synthetic isoprene rubber wet masterbatch .
(2) The method according to (1) above, wherein the content of the polyisoprene rubber in the powder rubber is 10% by weight or more.
(3) The method according to (1) above, wherein the powder rubber has an average particle size of 200 microns or less.
(4) The method according to (1) above, wherein a slurry concentration of the rubber powder in the slurry solution is 0.5 wt% to 60 wt% with respect to the slurry solution.
(5) In the mixed solution of the slurry solution and the natural rubber latex and / or synthetic isoprene rubber latex, the concentration of the powder rubber is 100 parts by weight of the rubber component resulting from the natural rubber latex and / or synthetic isoprene rubber latex. The method according to (1) above, wherein the content is 0.1 to 100 parts by weight.
(6) The above (1), wherein a slurry solution obtained by previously dispersing carbon black and / or silica and a powdered rubber decomposed by microorganisms in water is mixed with natural rubber latex and / or synthetic isoprene rubber latex. The method described.
(7) The blending amount of the carbon black and / or silica in the natural rubber and / or synthetic isoprene rubber wet masterbatch is 5 with respect to 100 parts by weight of the rubber component resulting from the natural rubber and / or synthetic isoprene rubber latex. The method according to (6) above, which is ˜100 parts by weight.
(8) A natural rubber and / or synthetic isoprene rubber wet masterbatch obtained by the method according to any one of (1) to (7) above.
(9) (8) natural rubber and / or synthetic isoprene rubber wet master batch to coagulate the natural rubber and / or synthetic isoprene rubber master batch, wherein the kite is prepared by further drying according.
(10) A rubber composition comprising the natural rubber and / or synthetic isoprene rubber masterbatch described in (9 ) above.
(11) The amount of powder rubber contained in the natural rubber and / or synthetic isoprene rubber masterbatch is 0.1 to 50 parts by weight with respect to 100 parts by weight of rubber components other than the powder rubber of the rubber composition. The rubber composition as described in (10) above, wherein

According to the present invention, a microbially decomposed powder rubber obtained by decomposing a powder rubber containing polyisoprene rubber with BS-HA strain (FERM BP-10750) which is an actinomycete belonging to the genus Nocardia is dispersed in water. It became possible to produce a natural rubber and / or synthetic isoprene rubber wet masterbatch by mixing the prepared slurry solution with natural rubber latex and / or synthetic isoprene rubber latex. By blending the natural rubber and / or synthetic isoprene rubber master batch obtained by drying the natural rubber and / or synthetic isoprene rubber wet master batch, a rubber composition maintaining high physical properties can be obtained.

Embodiments of the invention will be specifically described below.
In the present invention, a slurry solution prepared by dispersing in advance in water microorganisms decomposed powdery rubber, you mixed natural rubber latex and / or synthetic isoprene rubber latex natural rubber and / or synthetic isoprene rubber wet master batch production method of The powdered rubber decomposed by the microorganisms is a powdered rubber containing polyisoprene rubber, which is decomposed with a BS-HA strain (FERM BP-10750) which is an actinomycete belonging to the genus Nocardia. The manufacturing method of the natural rubber and / or synthetic isoprene rubber wet masterbatch to be used is the gist. In general, a slurry in which a filler such as carbon black and silica and water are mixed in advance at a predetermined ratio and the filler is finely dispersed in water by a mechanical force, a natural rubber latex and / or a synthetic isoprene rubber. The latex is mixed, and then a coagulant such as an acid is added and coagulated. The obtained coagulum is collected and further dried to produce a carbon wet masterbatch. On the other hand, in the present invention, a microbially decomposed powder rubber obtained by decomposing a powder rubber containing polyisoprene rubber with BS-HA strain (FERM BP-10750) which is an actinomycete belonging to the genus Nocardia A slurry mixed with a certain ratio and thoroughly dispersed in water is mixed with a natural rubber latex and / or a synthetic isoprene rubber latex to prepare a powder rubber wet master batch in advance.

Since the surface of the rubber powder decomposed by microorganisms becomes hydrophilic when covered with sugar or protein, the rubber powder decomposed by microorganisms is easily dispersed in water. In the present invention, you biodegradation powder rubber BS-HA1 strain is actinomycete belonging to the genus Nocardia. Nocardia genus actinomycetes are known to degrade natural rubber and other polyisoprene-based rubbers, but normal Nocardia genus bacteria cannot decompose hard rubber compounded with carbon black. is there.

  However, as a result of intensive screening for natural rubber-degrading bacteria from many soils, the present inventor found a BS-HA1 strain belonging to the genus Nocardia. The BS-HA1 strain is suitable for decomposing rubber powders used in rubber products such as tires because it can decompose polyisoprene rubber compounded with carbon black. This BS-HA1 strain was deposited domestically on June 2, 2003 as FERM P-19378 in the Patent Organism Depositary, National Institute of Advanced Industrial Science and Technology, and internationally registered on December 11, 2006 as FERM BP-10750. It has been transferred to the deposit.

  The BS-HA1 strain used in the present invention grows while assimilating powdered rubber in a liquid medium of inorganic salt. Examples of inorganic salts contained in the liquid medium include those containing nitrogen, phosphorus, potassium, calcium, magnesium and the like. The powdered rubber thus treated with a microorganism has a hydrophilic surface as described above. Since BS-HA1 strain is an actinomycete that degrades polyisoprene rubber, it is preferable that the content of polyisoprene rubber in the powder rubber is large. The content of the polyisoprene rubber in the powder rubber is preferably 10% by weight or more, more preferably 50% by weight or more.

  In order to obtain a stable slurry in the present invention, the average particle diameter of the rubber powder is preferably 200 microns or less. This is because it is difficult to produce a uniform slurry when the particle diameter of the powder rubber is large.

  In order to obtain a more stable slurry solution, a certain amount of water is added to rubber decomposed by microorganisms, and the mixture is stirred at a high speed for a certain time using a mixer such as a colloid mill. If necessary, in the present invention, an anionic, cationic, nonionic or amphoteric surfactant can be added to the slurry, and anionic and nonionic surfactants are particularly preferred. In addition, it is preferable that the slurry density | concentration of powder rubber is 0.5 weight%-60 weight% with respect to this slurry, and the especially preferable range is 1 weight%-30 weight%.

  A natural rubber latex and / or a synthetic isoprene rubber latex is mixed with the slurry solution to prepare a wet masterbatch. The blending amount of the powder rubber when preparing the mixed solution of the slurry solution and the natural rubber latex and / or the synthetic isoprene rubber latex is 100 parts by weight of the rubber component resulting from the natural rubber latex and / or the synthetic isoprene rubber latex. Thus, it is preferably in the range of 0.1 to 100 parts by weight, and more preferably in the range of 1 to 10 parts by weight. This is because if the amount of powdered rubber is small, the recyclability is low, while if the amount of powdered rubber is too large, the physical properties deteriorate.

  In still another aspect, the present invention is characterized by mixing a slurry solution obtained by previously dispersing carbon black and / or silica and a powdered rubber decomposed by microorganisms in water with natural rubber latex and / or synthetic isoprene rubber latex. A natural rubber and / or synthetic isoprene rubber wet masterbatch. In general, fillers such as carbon black and silica and water are mixed in a certain ratio in advance, and a slurry in which the filler is finely dispersed in water by mechanical force and natural rubber latex are mixed, and then a coagulant such as acid. There is known a method for producing a carbon wet masterbatch obtained by collecting and drying a solidified product obtained by adding water, but in the present invention, a filler such as carbon black and / or silica and a powdered rubber treated with microorganisms are fixed in water. A slurry in which the filler is finely dispersed in water by a mechanical force and natural rubber and / or synthetic isoprene rubber latex is mixed to prepare a microorganism-treated powder rubber carbon wet masterbatch in advance.

  In order to obtain a stable slurry solution, a certain amount of the above-mentioned rubber powder, filler and surfactant are added to water and constant at a high speed with a mixer such as a high shear mixer, a high-pressure homogenizer, an ultrasonic homogenizer, a colloid mill, or an impeller mill. Stir for hours. As the carbon black used in the present invention, those used in the normal rubber industry can be used. For example, various grades of carbon black such as SAF, HAF, ISAF, FEF, and GPF can be used alone or in combination. Further, the silica used in the present invention is not particularly limited, but wet silica, dry silica, and colloidal silica are preferable.

  The total slurry concentration of the carbon black and / or silica and the microorganism-treated powder rubber is preferably 0.5 to 60% by weight, and particularly preferably 1 to 30% by weight, based on the slurry. Carbon black and / or silica is preferably added in an amount of 5 to 100 parts by weight, particularly 10 to 70 parts by weight, based on 100 parts by weight of the rubber component resulting from the natural rubber latex of the masterbatch. Is preferred. This is because if the amount of the filler is less than 5 parts by weight, sufficient reinforcement may not be obtained, and if it exceeds 100 parts by weight, the workability may be deteriorated.

  The masterbatch is coagulated by using a coagulant such as formic acid or sulfuric acid or a salt such as sodium chloride as usual. In the present invention, coagulation may be carried out by mixing the natural rubber latex and the slurry without adding a coagulant.

  Thereafter, the wet master batch is coagulated. As a coagulation method that can be adopted there, a method using a coagulant of an acid such as formic acid or sulfuric acid or a salt such as sodium chloride can be exemplified. If desired, additives such as carbon black, silica, other inorganic fillers, vulcanizing agents, anti-aging agents, coloring agents, and dispersing agents can be added to the wet masterbatch.

  In the final process of master batch production, drying is usually performed. In the present invention, ordinary dryers such as a vacuum dryer, an air dryer, a drum dryer, and a hand dryer can be used. In order to further improve the dispersibility of the rubber powder, drying is performed while applying a mechanical shearing force. It is preferable to carry out. Although this drying can be performed using a general kneader, it is preferable to use a continuous kneader from the viewpoint of industrial productivity. Furthermore, it is preferable to use a twin-screw kneading extruder that rotates in the same direction or in the direction of the tool.

  In the step of drying while applying the shearing force, the moisture in the wet masterbatch before the drying step is preferably 10% or more. If this moisture content is less than 10%, the improvement width of the filler dispersion in the drying process will be small.

  Further, a final rubber composition can be obtained by blending the master batch, and other rubber types can be kneaded with the rubber composition. The amount of powder rubber contained in the masterbatch blended in the rubber composition is preferably 0.1 to 50 parts by weight with respect to 100 parts by weight of the rubber component other than the powder rubber of the finally obtained rubber composition. .

  In addition, the rubber composition includes carbon black, silica, other inorganic fillers, vulcanizing agents, vulcanization accelerators, anti-aging agents, scorch preventing agents, zinc white, stearin, as long as the object of the present invention is not impaired. An acid or the like can be added.

  EXAMPLES Next, although this invention is demonstrated using an Example and a comparative example, this invention is not limited at all by the following Example.

Example 1
(1) Preparation of latex solution It was diluted with water so that the rubber content of natural rubber field latex (DRC 26.2%, pH 10.5) was 20%.

(2) Microbial degradation of powder rubber 10 g / 1 of acetone-extracted natural rubber powder rubber (average particle size 100 μm) is placed in a medium with the composition shown in Table 1 prepared in a glass container with a silicone stopper at 90 ° C. Sterilized in an autoclave. To this was added a bacterial solution of BS-HA1 strain that had been pre-cultured using glove rubber as the sole carbon source, and after 20-day rotation with a magnetic stirrer, autoclaved at 121 ° C., and the rubber powder was filtered through filter paper. The powder rubber on the filter paper was washed several times with acetone, then with pure water, and after confirming that it was sufficiently dried, it was used as a sample of the microbially decomposed powder rubber to be blended.

(3) Preparation of slurry solution The above-mentioned microorganism-decomposed powder rubber was added to a certain amount of water and stirred at a high speed for a certain time in a colloid mill. The slurry concentration of the powder rubber was 10% by weight with respect to the slurry.

(4) Coagulation process Add the latex and slurry prepared in the above to a homomixer so that the rubber content is 10 parts by weight with respect to 100 parts by weight of rubber, and add formic acid to pH 4.7 while stirring. We got a wet masterbatch. The solidified wet masterbatch was collected, washed with water and dehydrated.

(5) Drying step The solidified sample was dried with an air dryer to obtain a master batch.

(6) Rubber composition For the above master batch (100 parts by weight of rubber, 10 parts by weight of powdered rubber), 50 parts by weight of HAF, 3 parts by weight of zinc oxide, 1.2 parts by weight of sulfur, 2 parts by weight of stearic acid, A rubber composition was obtained by kneading 1 part by weight of NS and 6 parts by weight of NS.

(Comparative Example 1)
The composition of Comparative Example 1 was produced through the same operation as in Example 1, but the powdered rubber was not treated with microorganisms. The rubber composition was vulcanized and the tensile fracture strength was measured by a method based on JIS K6251-1993. As shown in Table 2 below, Example 1 showed higher physical properties than Comparative Example 1. .

(Example 2)
(1) Preparation of latex The same procedure as in Example 1 was performed.

(2) Microbial treatment of powdered rubber The same procedure as in Example 1 was performed.

(3) Preparation of slurry solution A certain amount of the above-mentioned microorganism-treated rubber powder was added to water and stirred at a high speed for a certain time in a colloid mill. The slurry concentration of the powder rubber was 2% by weight with respect to the slurry.

(4) Coagulation step Add the latex and slurry prepared in the above into a homomixer so that the rubber content is 10 parts by weight with respect to 100 parts by weight of rubber, and add formic acid to pH 4.7 while stirring. We got a wet masterbatch. The solidified wet masterbatch was collected, washed with water and dehydrated.

(5) Drying step The same procedure as in Example 1 was performed.

(6) Rubber composition The same procedure as in Example 1 was performed.

(Example 3)
(1) Preparation of latex The same procedure as in Example 2 was performed.

(2) Microbial treatment of powdered rubber The same procedure as in Example 2 was performed.

(3) Preparation of slurry solution A certain amount of the above-mentioned microorganism-treated rubber powder and carbon black HAF were added to water, and stirred at high speed for a certain time in a colloid mill. The total slurry concentration of carbon black and powder rubber was 10% by weight of carbon black and 2% by weight of powder rubber based on the slurry.

(4) Coagulation step The latex and slurry prepared as described above were added to a homomixer so that the total weight of carbon black and powdered rubber was 60 parts by weight with respect to 100 parts by weight of rubber, and formic acid was added while stirring. A powder rubber / carbon wet masterbatch was obtained until the pH reached 4.7. The solidified wet masterbatch was collected, washed with water and dehydrated.

(5) Drying process The solidified wet masterbatch was dried with an air dryer.

(6) Rubber composition 3 parts by weight of zinc oxide, 1.2 parts by weight of sulfur, 2 parts by weight of stearic acid, NS for the above master batch (100 parts by weight of rubber, 50 parts by weight of carbon black, 10 parts by weight of powdered rubber) 1 part by weight and 1 part by weight of 6C were kneaded to obtain a rubber composition.

Example 4
Only the latex was prepared according to the following procedure, and the others were performed in the same manner as in Example 2.
(1) Preparation of latex Commercially available synthetic polyisoprene latex (Sepolex IR-100K DRC: 65.4%, manufactured by Sumitomo Seika Co., Ltd.) was diluted with water so that the rubber content was 20%.

(Comparative Example 2)
(1) Preparation of latex Natural rubber field latex (DRC 26.2%, pH 10.5) was diluted with water so that the rubber content was 20%.

(2) Coagulation step Formic acid was added to a pH of 4.7 while stirring the latex prepared as described above in a homomixer. The solidified natural rubber was recovered, washed with water and dehydrated.

(3) Drying process The coagulated natural rubber was dried with an air dryer.

(4) Rubber composition Based on 100 parts by weight of the natural rubber, 10 parts by weight of powder rubber having an average particle size of 100 microns, 50 parts by weight of HAF, 3 parts by weight of zinc oxide, 1.2 parts by weight of sulfur, 2 parts by weight of stearic acid, A rubber composition was obtained by kneading 1 part by weight of NS and 1 part by weight of 6C.

(Comparative Example 3)
(1) Preparation of latex Commercially available synthetic polyisoprene latex (Sepolex IR-100K DRC: 65.4%, manufactured by Sumitomo Seika Co., Ltd.) was diluted with water so that the rubber content was 20%.

(2) Coagulation step Formic acid was added to the pH adjusted to 4.7 while stirring the latex prepared as described above in a homomixer. The coagulated synthetic polyisoprene rubber was recovered, washed with water and dehydrated.

(3) Drying step The above-mentioned solidified synthetic polyisoprene rubber was dried with an air dryer.

(4) Rubber composition 10 parts by weight of powder rubber having an average particle diameter of 100 microns, 50 parts by weight of HAF, 3 parts by weight of zinc oxide, 1.2 parts by weight of sulfur, and 2 parts by weight of stearic acid with respect to 100 parts by weight of the above synthetic polyisoprene rubber Parts, 1 part by weight of NS, and 1 part by weight of 6C were kneaded to obtain a rubber composition.

  The physical properties of the rubber compositions of Examples 2, 3, and 4 blended with the master batch of the present invention and the rubber compositions of Comparative Examples 2 and 3 not blended with the master batch are shown in terms of the breaking strength and the results of the constant elongation fatigue test. Evaluated as an indicator. (Table 3) The breaking strength was measured by a method based on JIS K6151-1993. In the constant elongation fatigue test, dumbbell-shaped test pieces were repeatedly pulled at a speed of 300 rpm and a strain of 100%, and evaluation was performed by logarithm of the number of times of fracture. As shown in Table 3, the physical properties of Examples 2, 3, and 4 were superior to those of Comparative Examples 2 and 3.

  According to the present invention, a natural rubber and / or synthetic isoprene rubber wet masterbatch can be produced by mixing a slurry solution in which microbially decomposed powder rubber is dispersed in water and natural rubber latex and / or synthetic isoprene rubber latex. It has become possible. By blending the natural rubber and / or synthetic isoprene rubber master batch obtained by drying the natural rubber and / or synthetic isoprene rubber wet master batch, a rubber composition maintaining high physical properties can be obtained. The rubber treatment method of the present invention has the advantage of low energy cost, and the natural rubber and / or synthetic isoprene rubber masterbatch obtained by the method of the present invention is useful for rubber recycling.

Claims (11)

A slurry solution prepared by dispersing in advance in water powder rubber was decomposed by the microorganisms, a natural rubber latex and / or you mixed synthetic isoprene rubber latex natural rubber and / or method of manufacturing a synthetic isoprene rubber wet master batch ,
The natural rubber characterized in that the powdered rubber decomposed by the microorganism is a powdered rubber containing polyisoprene rubber, which is decomposed by BS-HA strain (FERM BP-10750) which is an actinomycete belonging to the genus Nocardia. Manufacturing method of rubber and / or synthetic isoprene rubber wet masterbatch . The method according to claim 1 , wherein the content of the polyisoprene rubber in the powder rubber is 10% by weight or more. The method according to claim 1, wherein the powder rubber has an average particle size of 200 microns or less.   The method according to claim 1, wherein the slurry concentration of the rubber powder in the slurry solution is 0.5 wt% to 60 wt% with respect to the slurry solution.   In the mixed solution of the slurry solution and the natural rubber latex and / or synthetic isoprene rubber latex, the concentration of the powder rubber is 0.1 to 100 parts by weight with respect to 100 parts by weight of the rubber component resulting from the natural rubber latex and / or synthetic isoprene rubber latex. 2. A method according to claim 1, characterized in that it is 100 parts by weight.   2. The method according to claim 1, wherein a slurry solution obtained by previously dispersing carbon black and / or silica and powdered rubber decomposed by microorganisms in water is mixed with natural rubber latex and / or synthetic isoprene rubber latex. The blending amount of the carbon black and / or silica in the natural rubber and / or synthetic isoprene rubber wet masterbatch is 5 to 100 weights with respect to 100 parts by weight of the rubber component resulting from the natural rubber and / or synthetic isoprene rubber latex. The method according to claim 6 , wherein the method is a part. A natural rubber and / or synthetic isoprene rubber wet masterbatch obtained by the method according to any one of claims 1 to 7 . Natural rubber and / or synthetic isoprene rubber master batch according to claim 8 to coagulate the natural rubber and / or synthetic isoprene rubber wet master batch, wherein said the kite is prepared by further drying. A rubber composition comprising the natural rubber and / or synthetic isoprene rubber masterbatch according to claim 9 . The amount of powder rubber contained in the natural rubber and / or synthetic isoprene rubber masterbatch is 0.1 to 50 parts by weight with respect to 100 parts by weight of rubber components other than the powder rubber of the rubber composition. The rubber composition according to claim 10 .