RU2253656C1 - Method of recovering synthetic rubbers from latexes - Google Patents

Abstract

FIELD: rubber industry.

SUBSTANCE: invention discloses a method for recovering synthetic rubbers from latexes stabilized by carboxylic acid soaps, which consists in action of mineral acid and organic amine coagulant on antioxidant-containing rubber latex. Organic amine coagulant is added in amount 0.01 to 1.0% in two steps: first portion constituting 50-90% of total amount of coagulant is added directly to latex and resulting mixture is stirred for at least 0.5 h at 20-70°C, after which second portion of coagulant or its mixture with mineral salt (coagulant/salt weight ratio from 1:0 to 1:15000) is fed into coagulation apparatus jointly with recycling serum at latex-to-serum weight ratio between 1:1 and 1:2. Rubber is thus obtained in the form of homogeneous porous crumb.

EFFECT: improved environmental characteristics of process due to lowered content of carboxylic acid soaps in waste water, which is also prevented to be polluted with leukanol, and accelerated drying of rubber crumb.

2 tbl, 18 ex

Description

The invention relates to the field of isolation of synthetic rubbers from latexes and can be used in the petrochemical and oil refining industries.

The most common industrial method for isolating synthetic rubbers from latexes obtained using carboxylic acid soaps as emulsifiers and NF dispersants (leucanol) is to isolate rubbers using sodium chloride and sulfuric acid. Consumption of sodium chloride even with serum recycle ranges from 200 to 400 kg per ton of rubber. All sodium chloride, as well as biodegradable leucanol, are washed out in wastewater and cause environmental problems. (P.A. Kirpichnikov, L.A. Averko-Antonovich, Yu.O. Averko-Antonovich. Chemistry and technology of synthetic rubber. Chemistry. Leningrad Branch., 1970, p. 395-399, 402-403).

A known method of isolating synthetic rubbers from latexes with mineral acids in the presence of high molecular weight amino-containing coagulating additives of synthetic or natural origin:

- polyalkylene polyamines (US Pat. US No. 3112299, CL 260-94);

- sodium lignate and water-soluble polyamine (US Pat. US No. 4025711, class C 08 F 6/22, publ. 24.05.77);

- polyhexamethylene guanidine hydrochloride (metacide) (RF patent No. 1700007, IPC С 08 С 1/15, publ. 23.02.91).

A common drawback of these technical solutions is the need to withstand low pH values (1.5-2.5), which causes equipment corrosion, increased sulfate content in wastewater, leaching of coagulants and antioxidants into serum.

In addition, these amine coagulants are water-soluble substances and, when coagulated, pass into wastewater, which significantly affects the environmental characteristics of the process.

Some of them, such as sodium lignate, give the rubbers a dark color, which makes it impossible to use them when obtaining light grades of rubbers.

Such a coagulant as metacid is a highly hygroscopic substance, which complicates its storage and preparation of working solutions.

There is also a method for the isolation of styrene-butadiene (methyl-styrene) and butadiene rubbers from latexes, in which the product of the interaction of polyethylene-polyamine (PEPA) with tall oil or with rosin or fatty acids taken in a mass ratio of 0 is used as an organic coagulant , 8: 1 to 2: 1 and subjected to heating at a temperature of 130-140 ° C for 60-80 minutes in an amount of 0.05-0.5 wt.h. on allocated rubber (Pat. RF №2186072 with prior. dated 04.12.2000, published on 07.27.2002, BI No. 21; IPC С 08 С 1/15, С 08 F 6/22, С 08 F 36 / 06). This method eliminates the discharge of biodegradable leucanol into wastewater, while significantly reducing or completely eliminating the use of mineral salts.

However, this method has a significant drawback, namely, that the used organic coagulant contains free PEPA, which is biologically oxidized by only 30%, which is not acceptable from an environmental point of view.

A known method of isolating synthetic rubbers from latexes by the action of an organic coagulant, followed by separation of the resulting rubber crumbs from serum and washing and drying thereof. As an organic coagulant, a protein collagen hydrolyzate with a content of 0.07-20 wt.% Carboxyl groups is used (AS USSR No. 1065424 with priority from 09/09/1982, IPC С 08 С 1/15, publ. 07.01.1984) as well as methods using mixtures of collagen hydrolyzate or phenolamine resin (a product of the condensation of nonylphenol and hexamethylenetetramine with diethanolamine) with anti-agglomerators, calcium chloride, magnesium chloride or bischofite (RF Patent No. 2140928 with prior. dated 04.02.98. IPC С 08 С 1 1. 14, C 08 C 1/15; C 08 F 6/22, publ. 10.11.99, BI No. 31), as well as with the introduction of acetic anti-agglomerators in the decomp. devices for the coagulation and washing of rubber crumb cascade, with an additional input of potassium hydroxide or sodium hydroxide and sodium chloride (RF Patent No. 2203287 with prior dated June 24, 02, IPC С 08 С 1/14, С 08 С 1/15, published on April 27, 2003, BI No. 12).

The disadvantages of these methods are the ability of proteinaceous matter of animal origin to rot during storage and transportation with the release of volatile sharply smelling decomposition products, such as hydrogen sulfide, ammonia, etc. In addition, the contact of working personnel with a protein product during loading for hydrolysis can cause allergic diseases. ("Belcosine" is a dusty powdery product).

The relatively high consumption of protein coagulants is explained by the fact that proteins of both animal and plant origin are high molecular weight products. In aqueous solutions, micromolecules, as a rule, are in the form of tangles or twisted spirals-fibrils, and access to nitrogen atoms is difficult. Since the efficiency of coagulation is largely determined by the rate of interaction of the leukanol sulfo group with the amino group of the protein, isolation of the amino group significantly slows down the speed of the process and reduces the effectiveness of the coagulant.

A significant disadvantage of these methods is that the aqueous solution of the coagulant has an acidic environment. Its introduction into latex causes local point-wise premature coagulation.

The additional introduction of anti-agglomerators, potassium, sodium and sodium chloride hydroxides significantly complicates the hardware design and the process of rubber separation.

The main advantages and disadvantages of the above and other methods are given in the work of V.N. Papkov and other authors "Modern methods of coagulation of synthetic latexes in the production of emulsion rubbers." "Production and use of elastomers." M., 2000, No. 6, pp. 3-6.

A synthesis of foreign and domestic experience shows the need for a significant change in technology and hardware design salt-free allocation of rubbers.

To date, methods for salt-free isolation of rubbers from latexes have not been introduced on an industrial scale at any plant in Russia.

Closest to the technical solution to the proposed one is a method for isolating synthetic rubber from latex stabilized with carboxylic acid soaps, exposure to mineral acid at pH 3.0-3.5 and an organic coagulant, which is used as poly (N-3,5-ditretbutyl- 4oxytolyl) ethyleneimine in an amount of 0.05-0.25% by weight of rubber (RF Patent No. 859377 with prior. 08/30/81, M.C. ³ C 08 C 2/06; C 08 C 1/14, publ. 09/01/81, BI No. 32).

The main disadvantages of this method are the following:

1. Lack of time required for uniform distribution of coagulant in latex. Its introduction into latex under industrial conditions in such small quantities leads to an inhomogeneous distribution in the latex volume and the formation of heterogeneous crumbs, especially for oil-filled rubbers.

2. As an antioxidant, this product is suitable for a limited number of rubbers (only for oil-filled rubbers SKS (MS) -30ARKM-15). For most rubbers, the required dosage of antioxidants is from 0.7 to 1.5% to ensure the stability of rubbers during processing and long-term storage.

3. When introducing the coagulant in one step, the operational control of coagulation is not achieved, since there is a certain inertia in the reaction of the interaction of the coagulant with leucanol, the formation of crumbs uniform in size and pore formation.

The content of free organic acids in rubbers is at the lower acceptable limit, which is associated primarily with the incompleteness of coagulation and the loss of soaps with wastewater.

The technical task of the invention is to improve the environmental characteristics of the process by reducing the loss of soaps of carboxylic acids with wastewater and, accordingly, increasing the content of free organic acids in rubbers; the achievement of more complete coagulation of the biodegradable leucanol by the coagulant into an insoluble complex and the prevention of wastewater contamination by leucanol; obtaining a uniform and porous crumb of rubber, accelerating its drying and increasing the stability of rubber during processing.

The stated technical problem is achieved by the fact that in the inventive method for the isolation of synthetic rubbers from latexes stabilized with carboxylic acid soaps, exposure to mineral acid and an organic amine coagulant, the latex is filled with an antioxidant before coagulation, and the coagulant in an amount of 0.01-1.0 wt.% Per rubber served in two doses, and the first portion of the coagulant in an amount of 50-90% of its total dosage is administered directly in latex, kept under stirring and at a temperature of 20-70 ° C for at least 0.5 hours, and the second portion coagulant or its mixture with a mineral salt in a mass ratio amine coagulant: mineral salt from 1: 0 to 1: 1500 is introduced into the coagulation apparatus together with recycled serum in a mass ratio of latex: serum from 1: 1 to 1: 2.

Changing the dosage of the second portion of the coagulant allows you to quickly influence the size and porosity of the rubber crumb and the completeness of coagulation.

The introduction of the coagulant in two doses provides the following advantages over known methods:

- the introduction of the first portion of the coagulant in latex and keeping it with stirring for a certain time at a certain temperature allows for its uniform distribution in latex throughout the volume and partial flocculation of latex particles, which significantly accelerates and enhances the action of the second portion of coagulant introduced with serum. Since the mass ratio of latex and serum is from 1: 1 to 1: 2, despite the small amount of the second portion, its introduction with a large amount of serum contributes to the quick and effective control of the size and porosity of crumbs and the completeness of coagulation, characterized by the complete conversion of soaps to carbon acids, which is especially important for styrene butadiene and methyl styrene butadiene rubbers;

- the second portion of the coagulant contributes to a more complete binding of leucanol if it is present in serum with a single injection, and in the case of adding mineral salts, a significant reduction in the stickiness of crumbs to the equipment;

- obtaining a more uniform and porous crumb significantly speeds up the drying time of rubber;

- a complex of coagulant with leucanol in combination with an antioxidant increases the stability of rubbers during processing.

When implementing the proposed method using organic amine coagulants:

product of OMP (poly (N-3,5-ditretbutyl-4-hydroxytolyl) ethyleneimine) in the form of a 2-10% aqueous emulsion obtained by the following method,

the product of the interaction of polyethylene polyamine with tall oil or with rosin, or with fatty acids (coagulant TMP according to the patent of the Russian Federation No. 2186072) in the form of 1-10% aqueous emulsion,

bone glue according to GOST 2067-80 in the form of a 2-5% aqueous solution,

sodium chloride according to GOST 4233-78 in the form of a 20-24% aqueous solution,

potassium alum according to GOST 15028-77 or aluminum sulfate according to GOST 3758-65 in the form of 1-4% aqueous solution,

calcium chloride according to GOST 450-77 in the form of a 5% solution.

Polyamine coagulant poly (N-3,5-ditretbutyl-4-hydroxytolyl) ethyleneimine (product of OMP) is synthesized according to the following recipe (parts by weight):

2,6-di-tert-butylphenol 1.0

polyethylene polyamine 1,3

formaldehyde 0.15

methyl alcohol 0.6

The calculated amount of 2,6-di-tert-butylphenol (2,6-diTBP) is charged into a reactor equipped with a stirrer, a heating jacket and a meter, and methanol is fed there. After loading, turn on the stirrer and mix for 30 minutes. After dissolving 2,6-diTBP in methyl alcohol with a working stirrer, polyethylene polyamine (PEPA) is charged into the reactor. The reaction mass is heated to 90 ° C and, with constant stirring, gradual dosing of formaldehyde containing 37 wt.% Formalin is carried out for 2.5 hours. At the end of dosing, the mixture is kept under constant stirring at 130 ° C until a complete conversion of 2,6-diTBP is achieved. Upon completion of the reaction, the water-alcohol fraction is distilled off, then the temperature is reduced to 70 ° C and poly (N-3,5-ditretbutyl-4-hydroxytolyl) ethyleneimine (OMP) is discharged.

An OMP emulsion containing 10% coagulant is prepared in an apparatus with a stirrer and a heating jacket. To 90 parts by weight water with a temperature of 60-65 ° C is poured with stirring 10 wt.h. WMD heated to 60-65 ° C. Preparation is carried out at 60-65 ° C and stirring for 1 hour.

The rubber crumb homogeneity is evaluated by sieve analysis. 400 g of washed raw chips are mechanically dispersed on two sieves with mesh sizes of 7 and 2 mm. A crumb of more than seven and less than two mm in size is considered non-optimal, since in industrial conditions the fine crumbs clogs the expeller shirt slots and the perforation of the dryer conveyors, and the large crumb dries more slowly and can plasticize during the drying process.

After sieving, each fraction of the crumbs is dried and the percentage of crumbs of non-optimal size is estimated. The data obtained are shown in table 1.

In examples 1-14, the isolation of rubbers from latexes stabilized with carboxylic acid soaps is carried out on a pilot installation in a coagulation apparatus equipped with a high-speed stirrer and a heating jacket.

Examples 15-18 are the isolation of rubbers from latexes stabilized with carboxylic acid soaps under industrial conditions.

The characteristics of the rubber release from latexes are given in table 1, in table 2 - the properties of rubbers.

Example 1

To 5 kg of styrene-butadiene rubber latex SKS-Z0ARKPN containing 20 wt.% Dry matter, stabilizer VS-30A is introduced with stirring 1 wt.% Of the rubber mass, the first portion is 0.025 kg of 10% OMP coagulant emulsion, which is 50% of the total dosage of coagulant equal to 0.5 wt.%. on the mass of rubber, and incubated for 0.5 hours with stirring and a temperature of 50 ° C. Next, the latex is mixed in a coagulation apparatus with 10 kg of serum containing water, sulfuric acid and a second portion of the coagulant WMD 0.0025 kg (50% of the total dosage of the coagulant), where rubber is released from the latex in the form of crumbs at pH 4. The rubber is separated from the serum, washed with softened water and dried in an air dryer at 80 ° C.

Example 2

To 3.95 kg of SKMS-30ARKM-15 butadiene-methylstyrene rubber latex containing 21 wt.% Dry matter, 0.02 kg of a 10% OMP emulsion (first portion), which is 80% of the coagulant of the total dosage, is added with stirring WMD equal to 0.25 wt.%. on the mass of oil-filled rubber, incubated for 0.5 hours with stirring and a temperature of 65 ° C. After that, 0.17 kg of oil filler PN-6, containing 1.5 wt.% Stabilizer BC-1, is added to the latex, and additionally stirred for 0.1 hour. The resulting latex-oil emulsion is mixed in a coagulation apparatus with 5.9 kg of regulatory serum containing sulfuric acid and a second portion of coagulant OMP 0.0005 kg (20% of the total amount of coagulant), where rubber is released from latex at pH 3.2. The rubber is separated from the serum, washed with softened water and dried in an air dryer at 80 ° C.

Example 3 (prototype)

To 3.35 kg of styrene-butadiene rubber latex SKS-30ARKM-15, containing 24.8 wt.% Dry matter, 312 ml of a 0.8% poly (N-3,5-ditretbutyl-4) solution are poured into the coagulation bath -oxytolyl) ethyleneimine (coagulant OMP), which is 0.25 wt.% by weight of rubber. The latex is heated to 65 ° C and 170 g of PN-6 oil are added with stirring. Then, 630 ml of a 1.5% sulfuric acid solution are added. The pH of the medium is 3.2. The coagulated polymer is separated, washed with water, dried in an air dryer at 80 ° C.

Example 4

To 4.7 kg of styrene-butadiene rubber latex SKS-30ARK, containing 21.3 wt.% Dry matter, VTS-150 stabilizer and the first portion of OMC coagulant 0.035 kg of 10% emulsion are introduced with stirring 1 wt.% On the mass of rubber , which is 70% of the total amount of coagulant 0.5 wt.% on the mass of rubber. After stirring at 70 ° C for 0.5 hours, the latex is mixed in a coagulation apparatus with 9.4 kg of serum containing sulfuric acid and a second portion of coagulant OMP 0.0015 kg (30% of the total amount of coagulant), where at pH 3, 4 emit latex rubber. The coagulated polymer is separated from serum, washed and dried at 80 ° C.

Example 5

To 5.0 kg of styrene-butadiene rubber latex SKMS-30ARK, containing 20.0 wt.% Dry matter, VTS-150 stabilizer and the first portion of OMP coagulant 0.02 kg 10% are introduced with stirring 1 wt.% On the mass of rubber emulsion, which is 80% of the total amount of coagulant 0.25 wt.%. on the mass of rubber. After stirring at 60 ° C for 0.5 hours, the latex is mixed in a coagulation apparatus with 10 kg of serum containing sulfuric acid, bone glue in an amount of 0.001 kg (0.1 wt.% Per rubber mass) and a second portion of coagulant OMP 0 , 0005 kg (20% of the total coagulant), where rubber is released from latex at pH 3.5. The coagulated rubber is separated from serum, washed and dried.

Example 6

To 5.0 kg of SKMS-30ARK butadiene-methylstyrene latex containing 20 wt.% Dry matter, 1.0 wt.% VTS-150 stabilizer and 0.25 kg of a 2% aqueous solution of bone glue are introduced with stirring, which is 0.5 wt.% By weight of rubber. After stirring at a temperature of 60 ° C for 0.5 hours, the latex is mixed in a coagulation apparatus with 10 kg of recycled serum containing sulfuric acid. Partial coagulation, lumpy, latex is occluded in sticky rubber, white serum contains uncoagulated latex. Rubber not analyzed.

Example 7

To 4.74 kg of styrene-butadiene rubber latex SKS-30ARKPN containing 21.1 wt.% Dry matter, 1.0 wt.% Stabilizer BC-30A and the first portion of TMP coagulant (the product of the interaction of tall oil and polyethylene polyamine, synthesized according to the patent of the Russian Federation No. 2186072 dated 12/04/2002) in an amount of 0.0225 kg of a 10% emulsion of the coagulant TMP, which is 75% of the total dosage of the coagulant, equal to 0.3 wt.% by weight of rubber. After stirring at a temperature of 50 ° C for 0.5 hours, latex is mixed in a coagulation apparatus with 9.5 kg of recycle serum containing sulfuric acid and a second portion of TMP coagulant in an amount of 0,00075 kg, which is 25% of its total dosage. Rubber isolated from latex at pH 4 is separated from serum, washed and dried at 80 ° C.

Example 8

To 5.05 kg of nitrilast-26 butadiene-nitrile rubber latex containing 19.8% by weight of dry matter, 1.2% by weight of BC-30A stabilizer and the first portion in the amount of 0.01 kg of 10% are added to the rubber with stirring emulsion of the coagulant OMP, which is 50% of the total dosage of the coagulant, equal to 0.2 wt.h. per 100 parts by weight rubber. After stirring for 0.5 hours at 60 ° C, the latex is mixed in a coagulation apparatus with 7.6 kg of recirculating serum containing sulfuric acid, sodium chloride in an amount of 0.05 kg (5 parts by weight per rubber) and a second portion of OMP 0.001 kg, which is 50% of the total dosage of WMD. The rubber isolated from latex at pH 4 is separated, washed and dried at 80 ° C.

Example 9

To 4.3 kg of EPB-M-15 polybutadiene rubber latex containing 19.3 wt.% Of dry matter, the first portion of the coagulant of OMP is added with stirring in the amount of 0.027 kg of a 10% emulsion, which is 90% of the total dosage of OMP, equal to 0.3 wt.% on the weight of oil-filled rubber. After 0.5 hours of stirring at 60 ° C, 0.17 kg of PN-6 oil containing 1.5 wt.% Of BC-1 stabilizer is added, and additionally stirred for 0.1 hours at 60 ° C. The obtained latex-oil emulsion is mixed in a coagulation apparatus with 4.3 kg of recycle serum containing sulfuric acid, potassium alum in an amount of 0.005 kg (0.5 wt.% Per rubber) and a second portion of coagulant OMP 0.0003 kg, which is 10 % of the total amount of WMD. The rubber isolated from latex at pH 3.7 is separated, washed and dried at 80 ° C.

Example 10

To 3.5 kg of styrene-butadiene rubber latex SKS-30ARKM-27, containing 20.3 wt.% Of dry matter, the first portion of the OMP coagulant is added with stirring in the amount of 0.006 kg of a 10% emulsion, which is 60% of the total dosage WMD equal to 0.1 wt.% On the weight of oil-filled rubber. After stirring for 0.5 hours at 65 ° C, 0.29 kg of PN-6 oil containing 1.5 wt.% BC-1 stabilizer is introduced into the latex, and additionally stirred for 0.1 hour. The latex-oil emulsion is mixed in a coagulation apparatus with 3.5 kg of recirculating serum containing sulfuric acid, potassium alum in an amount of 0.01 kg (1 wt.% Per rubber) and a second portion of coagulant OMP 0.0004 kg, which is 40% of the total dosage of WMD. The separated rubber is separated, washed and dried at 80 ° C.

Example 11

To 5.05 kg of nitrilast-18 butadiene-nitrile rubber latex containing 19.8% by weight of dry matter, 1.25% by weight of BC-30A stabilizer and the first portion of 0.004 kg of a 10% emulsion are introduced with stirring coagulant WMD, which is 80% of the total dosage of coagulant WMD, equal to 0.05 wt.% on the mass of rubber, and stirred for 0.5 hours at 65 ° C. Next, the latex is mixed in a coagulation apparatus with 10.1 kg of recycle serum containing sulfuric acid, calcium chloride in an amount of 0.015 kg (1.5 wt.% Per rubber) and a second portion of coagulant OMP 0.0001 kg (20% of the total amount of OMP ) The rubber isolated from latex at pH 4 is separated, washed and dried at 80 ° C.

Example 12

To 5.05 kg of nitrilast-40 butadiene-nitrile rubber latex containing 19.8% by weight of dry matter, 1.25% by weight of rubber, BC-30A stabilizer and the first portion of 0.0045 kg, 2%, are added with stirring emulsion of the coagulant OMP, which is 90% of the total dosage of the coagulant, equal to 0.01 wt.% per rubber mass. After stirring at 50 ° C for 0.5 hours, the latex is mixed with 7.6 kg of recycle serum containing sulfuric acid, 0.15 kg sodium chloride (15 wt.% Per rubber) and a second portion of OMP coagulant in an amount of 0 , 00001 kg (10% of the total dosage). Rubber isolated from latex at pH 3.8 is separated, washed and dried at 80 ° C.

Example 13

To 5.5 kg of styrene-butadiene rubber latex SKS-30ARPD containing 18.2 wt.% Dry matter, stabilizer BC-ZOA and the first portion of the coagulant OMP in the amount of 0.05 are introduced with stirring 1.5 wt.% On the mass of rubber kg of 10% emulsion, which is 50% of the total dosage of coagulant equal to 1 wt.%. on the mass of rubber. After stirring at 20 ° C for 0.5 hours, the latex is mixed with 11 kg of recycle serum containing sulfuric acid and a second portion of the coagulant WMD in an amount of 0.005 kg (50% of the total dosage). The rubber isolated from latex at pH 3.0 is separated, washed and dried at 80 ° C.

Example 14

To 4.33 kg of SKMS-30ARK butadiene-methylstyrene rubber latex containing 23.1 wt.% Dry matter, VTS-150 stabilizer and the first portion of OMP coagulant in an amount of 0.014 kg 10 are introduced with stirring 1.5 wt.% On the mass of rubber % emulsion, which is 70% of the total dosage of coagulant, equal to 0.2 wt.% on the mass of rubber. After stirring at 40 ° C for 0.5 hours, the latex is mixed in a coagulation apparatus with 8.6 kg of recirculating serum containing sulfuric acid, aluminum sulfate in an amount of 0.01 kg, which is 1 wt.% Per rubber, and a second portion coagulant WMD in the amount of 0.0006 kg, which is 30% of the total dosage of the coagulant. coagulation pH 3.5. The separated rubber is separated, washed and dried at 80 ° C.

Example 15 (production)

In the container-averager to 259500 kg of styrene-butadiene rubber latex SKS-30ARKM-15, containing 21.7 wt.% Dry matter, 2554 kg of an 8.5% OMP coagulant emulsion are added with stirring, which is 80% of the total dosage WMD equal to 0.4 wt.% On the weight of oil-filled rubber. After stirring and circulating at 65 ° C for two hours, latex is continuously fed for coagulation. Before the first coagulation apparatus, PN-6 oil is continuously injected into the latex at the rate of 170 kg per 830 kg of latex dry matter, containing 1.5 wt.% Of the BC-1 stabilizer. Then, a solution of sodium chloride in an amount of 5.0 wt.% Mineral salt per weight of oil-filled rubber is introduced into the latex-oil emulsion. In a coagulation apparatus, with a continuous supply of components, the latex-oil emulsion is mixed with recirculating serum in a mass ratio of latex: serum = 1: 1.5, containing sulfuric acid and a second portion of coagulant OMP in the amount of 0.8 kg of coagulant per 1 ton of oil-filled rubber, which accounts for 20% of the total dosage of WMD. coagulation pH 3.2. Further, according to the traditional scheme, the resulting pulp is fed to the batching apparatus. The crumb of rubber is separated from serum in a concentrator, washed, squeezed in an expeller screw machine and dried in a conveyor air dryer at 100-115 ° C.

Example 16 (production)

A stabilizer BC-30A and a first portion of 1456 kg of a 10% emulsion are introduced into the capacity of the homogenizer to 260,000 kg of nitrilast butadiene-nitrile rubber latex Nitrilast-18 containing 20 wt.% Dry matter with stirring. coagulant WMD, which is 80% of the total dosage of WMD equal to 0.35 wt.% on the mass of rubber. After stirring and circulation at 60 ° C for two hours, the latex is fed into a coagulation apparatus, where recycled serum is introduced in a mass ratio of latex: serum = 1: 2, containing sulfuric acid, sodium chloride in an amount of 1 wt.% Per rubber mass and the second a portion of the coagulant WMD in the amount of 0.7 kg per 1 ton of rubber, which is 20% of the total dosage of WMD. coagulation pH 3.3. Further, according to the scheme of example 15.

Example 17 (production)

In the capacity-averager to 256900 kg of nitrilast-33 butadiene-nitrile rubber latex containing 21.8 wt.% Dry matter, stabilizer BC-30A is introduced with stirring 1.0 wt.% On the mass of rubber and the first portion of 1512 kg 10% - emulsion of the coagulant OMP, which is 90% of its total dosage equal to 0.3 wt.% per rubber mass. After stirring and circulation at 55 ° C for two hours, the latex is fed into a coagulation apparatus, where recycled serum is introduced in a mass ratio of latex: serum = 1: 1.5, containing sulfuric acid, sodium chloride in an amount of 2 wt.% Per rubber mass and the second portion of the coagulant OMP in the amount of 0.3 kg per 1 ton of rubber, which is 10% of the total portion of the WMD. coagulation pH 4.0. Further, according to the scheme of example 13.

Example 18 (production, prototype)

To 244400 kg of styrene-butadiene rubber latex SKS-30ARKM-15, containing 21.3 wt.% Dry matter, not charged with a stabilizer, 1650 kg of a 9.5% poly (N-3,5-) emulsion are added as a coagulant-stabilizer ditretbutyl-4-hydroxytolyl) ethyleneimine - PDE (product of OMP), which corresponds to 0.25 wt.% by weight of rubber, is stirred at 65 ° C for two hours and sent for coagulation.

PN-6 oil is continuously introduced into the latex stream before the first coagulation apparatus at the rate of 170 kg per 830 kg of latex dry matter. In a coagulation apparatus, a latex-oil emulsion is mixed with serum in a mass ratio of latex: serum = 1: 2 containing sulfuric acid. pH 3.2. The coagulated rubber is separated, washed and dried.

As can be seen from the data given in examples 1-18 and tables 1 and 2, the inventive method provides a more complete conversion of soaps to carboxylic acids, increasing their content in rubber and reducing their loss with waste water, reduces the drying time of the rubber due to higher uniformity crumbs, almost completely eliminates the discharge of biodegradable leucanol with wastewater by binding it to a water-insoluble complex.

In combination with mineral salts, organic amine coagulants are highly effective. The use of coagulants together with the stabilizers used provides high physical and mechanical properties of rubbers and high stability of rubbers against heat aging and machining.

Claims (1)

A method for isolating synthetic rubbers from latexes stabilized with carboxylic acid soaps, the action of mineral acid and an organic amine coagulant, characterized in that the latex is filled with an antioxidant before coagulation, and the coagulant in an amount of 0.01-1.0 wt.% Per rubber mass is fed into two reception, and the first portion of the coagulant in an amount of 50-90 wt.% of its total dosage is injected directly into the latex, kept with stirring and at a temperature of 20-70 ° C for at least 0.5 hours, and the second portion of the coagulant or its mixture with mineral The oligomer in the mass ratio of the amine coagulant: mineral salt from 1: 0 to 1: 1500 is introduced into the coagulation apparatus together with the recycled serum in the mass ratio of latex: serum from 1: 1 to 1: 2.