RU2281293C1 - Coagulant for synthetic rubber isolation from liquid media - Google Patents

Abstract

FIELD: fluid medium purification, production of emulsified synthetic rubber.

SUBSTANCE: coagulant based on protein component contains as additional ingredients carboxymethyl cellulose, carbamide, α- and β-amylase, fat aminoderivatives, carbamideformaldehyde resin and formalin in the next ratio (mass %): protein component 45.0-46.0; carboxymethyl cellulose 16.0-17.0; carbamide 10.1-10.2; α-amylase 9.4-0.5; β-amylase 9.4-9.5; fat aminoderivatives 8.8-8.9; carbamideformaldehyde resin 0.03-0.04; and formalin 0.02-0.03. 50 % of aminoderivatives may be replaced with alkylbenzyldimethylammonium chlorides. As protein component preferably animal- or plant-origin protein is used. Coagulant is used in 3-8 % aqueous solution form, and consumption thereof in process of fluid medium purification is 0.1-1.0 mass % based on mass of isolating rubber.

EFFECT: stabilized coagulation process; reagent of increased coagulating action; isolated rubber of improved quality.

Description

The invention relates to the purification of liquid media, including washing and wastewater (CB), the production of artificial and synthetic latexes from polymers, and can be used in the industry of emulsion synthetic rubbers (SC) and other industries related to the production, processing of latexes and the production of rubbers .

Latex waters are characterized by the presence of a colloidal dispersed phase of synthetic rubber. Rubber isolation is usually carried out by coagulation. Currently, various methods are used to coagulate synthetic latexes: physical, mechanical, chemical. The physical method of coagulation is coagulation by heating or freezing. Mechanical coagulation is carried out in a screw unit. The chemical method can be divided into so-called salt and salt-free methods.

Salt methods include coagulation using electrolytes - sodium chloride or calcium, sulfuric or acetic acid, in some embodiments with additives - bone glue hydrolyzate, BP coagulant. Despite the simplicity, reliability and effectiveness of electrolyte coagulation, it has a significant drawback, because mineral salts, passing through the treatment, are completely discharged into natural water bodies, causing their salinization.

Salt-free coagulation methods are carried out through the use of synthetic cationic coagulants based on amine compounds, copolymers of polyamines with epichloro- and epibromohydrin, copolymers of acrylic acid or dimethyl sulfates with 2-methyl-5-vinylpyridine, OMP, polymer salts of a quaternary ammonium base (VPK-46).

The value of these organic coagulants is the ability to bind a biodegradable leucanol into a water-insoluble complex, which is used further as a dispersant in polymerization.

For the coagulation of synthetic latexes, natural high-molecular compounds are also used, such as proteins (protein hadrolysates), starch, cellulose derivatives, lignin, polysaccharides, etc.

In the manufacture of general-purpose rubbers, the main coagulants of synthetic latex are sodium chloride and sulfuric acid (SU 536193).

Sodium chloride, used for coagulation of latexes, is preliminarily purified from mechanical impurities and ions of divalent metals. The coagulum formed during latex coagulation is thoroughly washed to obtain the final product with an ash content of less than 0.6%. For washing use softened water.

When coagulating the latexes of some low molecular weight rubbers (for example, latex of butadiene-β-diethylaminoethyl methacrylate rubber) using a solution of sodium chloride, rubber with an ash content of less than 1.5-2% cannot be obtained. In the process of isolating high molecular weight, structured rubbers with solutions of sodium chloride and sulfuric acid, hard-to-filter crumbs of small size (1-2 mm) are formed, which leads to the loss of rubber when it is separated from serum, additional pollution of washing water and insufficient wastewater treatment. The use of sodium chloride as a coagulant requires that the pH of the coagulating solution be accurately maintained.

In addition, depending on the brand of rubber, the consumption of sodium chloride for coagulation is an average of 190-250 kg per 1 ton of rubber. The volume of production of emulsion rubbers in the hundreds of thousands of tons is discharged into reservoirs a huge amount of sodium chloride, which causes irreparable damage to the environment.

Of the known methods, it should also be noted the allocation of synthetic diene rubbers from latexes by coagulation under the action of protein coagulants of plant origin. As protein coagulants, a solution of a polysaccharide and a protein substance of plant origin is used. A solution of a polysaccharide and a protein substance of plant origin is prepared by dissolving corn starch, soy flour, wheat flour, peanut flour, sunflower in alkaline water (French patent 2470138).

The disadvantages of the coagulant is that when the plant products are dissolved in alkali, not a true solution is obtained, but a difficult to separate suspension that must be filtered. In production, this stage causes great difficulties. The duration of the alkaline solution preparation operation, including the filtration stage, is 4-6 hours. The effectiveness of the action decreases as the solution is stored under industrial conditions. For example, storing a solution of soy flour for 20 hours changes the flow rate from 2 kg per ton of rubber to 5 kg.

A known method for the isolation of styrene-butadiene rubbers using animal proteins and products of protein origin as coagulating agents (SU 1131883).

The main disadvantages of such protein coagulants are coagulating activity only in a strongly acidic environment (pH 2.0-3.5). At a higher pH value (4 and above), protein coagulants either work very poorly (complete coagulation is not achieved), or require very high costs. Very often, when using a protein coagulant, the tendency of the rubber crumb to clump due to sticking is observed. This creates additional difficulties when drying the rubber - the drying time increases, the process productivity decreases. In addition, an aqueous solution of protein coagulant has a limited shelf life, especially in the summer season, that is, at elevated temperatures. In the warm season, the processes of decomposition of protein coagulant begin actively, which is expressed in the appearance of a sharp, unpleasant odor, which significantly complicates the use of this coagulant in the technological process. A characteristic, unpleasant odor also appears in the working areas of industrial premises, which violates the ecological purity of the environment. To exclude bacterial infection of the equipment during the receipt, storage, transportation and use of protein coagulants, it is necessary to thoroughly rinse it with water, prolonged treatment with hot steam and a formalin disinfectant solution. Vulcanizates based on rubbers isolated with the help of protein are characterized by insufficiently high properties. In addition, they are characterized by the duration of vulcanization.

There is also known a method of treating wastewater from polymers formed in industries using synthetic latexes, in which an aqueous solution of phenol-formaldehyde resin (3%, having a pH of 9.0) is used to coagulate the latex, preferably at a ratio of (0.15-1, 1): 1 to latex (in terms of dry matter). Then, an additional treatment is carried out with an aqueous solution of aluminum sulfate to increase the degree of purification. The clarification effect is up to 95.4%. The resulting coarse non-sticking coagulum is easily separated by filtration (SU 1288163). However, the resulting polymer chips are heterogeneous in composition and contaminated with aluminum ions.

The closest to the proposed technical essence and the achieved effect is a protein coagulant of synthetic rubber latexes obtained by the interaction of a protein with a quaternary ammonium salt of poly-N, N-dimethylammonium chloride in a mass ratio of 1: (1-0.1), respectively. The proposed coagulating system can significantly stabilize the coagulation process, improve the technology and improve the properties of the resulting rubber. This is achieved due to the fact that the product of the interaction of the protein with the polymer quaternary salt has high stability, is quite stable during storage and does not have a pronounced vulcanizing activity, which does not have a sharp negative effect on the properties of the styrene rubbers obtained during their isolation, drying, and also during the manufacture of rubber compounds (RU 2063980).

The advantage of coagulants based on the protein component is their environmental friendliness and the absence of toxic properties.

The disadvantages of such coagulants are the incomplete coagulation of synthetic latexes in the production of emulsion rubbers, a decrease in productivity due to poor drying of the rubber. The reason for the unsatisfactory drying of rubber is the adhesion of rubber to the equipment and the particles of rubber crumb among themselves, due to the properties of protein compounds. In addition, there is a large consumption of coagulant.

Despite the variety of well-known protein coagulants in the synthetic rubber industry in Russia, they are not widely used due to a number of economic (high consumption rates) and technical and technological (non-compliance of technological equipment with lump coagulation conditions, insufficient stability).

Thus, the common disadvantages of the above known methods for salt-free isolation of rubbers from latex using both organic, synthetic coagulants and natural protein are: process instability, incomplete coagulation and, therefore, incomplete treatment of wastewater and industrial water, poor physical and mechanical properties allocated rubber, heterogeneity of the fractional composition of rubber crumbs in size (agglomeration or crumbling of crumbs), stickiness of crumbs, leading to clogging equipment and process shutdown, which leads to a decrease in the productivity of the plants.

An object of the invention is to eliminate the disadvantages of known methods, stabilize and increase the coagulating effect of the reagent with the availability of its components, improve the manufacturability of the process for the isolation of rubbers from liquid latex media and wastewater, increase the economy and simplify the use of coagulant, as well as improve the quality of the emitted rubber, improve its filterability , obtaining a more uniform crumb in size, and when using a coagulant for cleaning CB, an increase in the degree of their cleaning.

The problem is solved by using a coagulant based on a protein component that combines the positive properties of synthetic cationic coagulants and natural macromolecular compounds. As additional to the protein component of the ingredients, the coagulant contains carboxymethyl cellulose, urea, α- and β-amylase, fatty amino compounds, urea-formaldehyde resin and formalin in the following mass content of all components, wt.%:

protein component 45.0-46.0 carboxymethyl cellulose 16.0-17.0 urea 10.1-10.2 α-amylase 9.4-9.5 β-amylase 9.4-9.5 fatty amine compounds 8.8-8.9 urea-formaldehyde resin 0.03-0.04 formalin 0.02-0.03,

however, 50% of the total content of amino compounds can be replaced by alkylbenzyldimethylammonium chlorides. Preferably, starch, polysaccharide, animal or vegetable protein, or a mixture thereof, is used as the protein component. The coagulant is used in the form of a 3-8% aqueous solution, and its consumption in the purification of liquid media is 0.1-1.0 wt.% Relative to the mass of rubber released.

Coagulants are obtained by deacetylation or the introduction of additional free amino groups in the structure of the original carbohydrate. Synthetic polymers are grafted onto the carbohydrate backbone, forming side chains of the polyelectrolyte. Synthesized products are invited to name:

1. "APK-46 cationic active polymer flocculant" is obtained when there are fatty amino compounds in the starting components, and

2. "Coagulant KP", upon receipt of which 50% of the total content of amino compounds is replaced by alkylbenzyldimethylammonium chlorides.

All initial components of coagulants are produced in the Russian Federation and comply with GOST and TU.

An exemplary formulation for the preparation of "Cationically active polymer flocculant APK-46" and "Coagulant KP" is presented in table No. 1.

Table number 1 Name of components The composition of coagulants: APK-46 KP kg / t % kg / t % 1. Protein component 455.43 45.543 455.43 45.543 2. Formalin 0.25 0,025 0.25 0,025 3. α-Amylase 94.88 9,488 94.88 9,488 4. β-amylase 94.88 9,488 94.88 9,488 5. Fatty Amino Compounds 88.55 8,855 44.27 4,427 6. Urea 101.24 10,124 101.24 10,124 7. Urea-formaldehyde resin 0.31 0,031 0.31 0,031 8. Carboxymethyl cellulose 164.46 16,446 164.46 16,446 9. Alkylbenzyldimethylammonium chloride 0 0 44.28 4,428 Total: 1000 kg one hundred% 1000 kg one hundred%

Example 1. "Cationically active polymer flocculant APK-46" is obtained in three stages.

First stage. A calculated amount of softened water is loaded into a reactor equipped with a jacket and a mixing device, heated to a temperature of 75-80 ° С, after which a calculated amount of protein (starch, polysaccharide, animal or vegetable protein, etc.) is loaded, with constant stirring complete dissolution of the loaded protein. After complete dissolution of the protein, the solution is treated with soda, sedimented for 2-3 hours and filtered, after which it is treated with formalin at the rate of 0.002 wt.% Of the loaded protein and analyzed for dry matter content, which should be at least 38-40%. Mass fraction of total nitrogen should be at least 18%.

Second stage. After obtaining a homogeneous solution with the specified concentration, in order to accelerate the process of attaching to the main carbohydrate chain, grafting a synthetic polymer, to form the side chains of the polyelectrolyte, the calculated amount of the enzyme protein (a mixture of α-amylase with β-amylase in equal amounts) is loaded with stirring, based on 1.5-2.5 wt.% of the loaded protein. The temperature is maintained equal to 75-80 ° C.

Third stage. After the loading of the protein-enzyme is completed with constant stirring, the calculated amount of the following ingredients is alternately loaded:

1. Amino compounds of the fat series at the rate of 0.6-0.8 mass parts per 3.5-3.7 mass parts of the loaded protein.

2. Urea 0.6-1.0 mass parts.

3. Urea-formaldehyde resin 0.002-0.003 mass parts.

4. Carboxyl methyl cellulose 1.2-1.4 mass parts.

At the time of loading, the heating of the reaction mass is stopped. At the end of the load, the mixture is kept under stirring for 0.5-1.5 hours. Due to the heat of the deacetylation reaction, the temperature is maintained at 75-80 ° C.

After the synthesis, the finished product is analyzed. In terms of non-volatile content, the result should be at least 49%, the pH of a 5% aqueous solution is 10.2-10.5, and the mass fraction of total nitrogen should be at least 28%. Then the resulting product is poured into a container.

Changes in the ratio of components in the composition are unacceptable, for example, an increase in the resin content in the mixture can lead to clumping of the released rubber crumb, an increase in the stickiness of the crumb and clogging of the equipment, and an increase in the protein component also adversely affects the quality of the released rubber, coagulation stability and expiration date of the coagulant.

In appearance, the “APC-46 Cationically Active Polymeric Flocculant” is a homogeneous, viscous brown mass without foreign matter with a mass fraction of non-volatile substances of at least 49%. The 3-5% aqueous solution used is a homogeneous yellow liquid without a precipitate, the pH of such a solution is 10.2-10.5.

Example 2. The process of obtaining the “Coagulant KP” is similar to the preparation of the “Cationically active polymer flocculant APK-46,” but in the third stage, the dosage of the fatty amine compounds is changed based on the calculation of 0.3-0.4 (50%) of the mass parts of amine compounds, and alkylbenzyldimethylammonium chloride is also added in an amount of 0.3-0.4 (50%) parts by weight.

In appearance, "Coagulant KP" is a homogeneous viscous mass from yellow to brown in color without foreign matter with a mass fraction of non-volatile substances of at least 48%. The used 3-5% aqueous solution is a homogeneous yellow liquid, it is allowed with a small amount of mobile sediment, the pH of this solution is 9.7-10.3.

As noted above, the SC industry in the isolation of rubber from latex by known coagulants encounters very significant difficulties. When using the "Cationically active polymer flocculant APK-46" or coagulant KP, the disadvantages of the known methods are eliminated, and the whole complex of these problems is solved.

The use of "Cationically active polymer flocculant APK-46" and "Coagulant KP" can be illustrated as follows.

Example 3. In a container with a stirrer pour 1/3 of the volume of partially-softened water. Download with stirring the calculated amount of "Cationically active polymer flocculant APK-46" or "Coagulant KP" at a rate of 3-8%. After loading APK-46 or KP, the solution is mixed and passed for analysis. After receiving the analysis, the APK-46 or KP solution is pumped through the flow regulator to the latex mixer before the first cascade coagulation apparatus, usually based on the calculation of 2-3 kg / t of rubber released, the serum pH is maintained at 2.0-2.4, serum consumption is 1: 2 in relation to the latex supplied.

The coagulant consumption for the release of rubber from latex is determined by the usual method of trial coagulation. The consumption of coagulant in the General case is 0.1-1 wt.% From the mass of the selected rubber and depends on the qualitative and quantitative composition of the liquid medium in which coagulation of the polymer is carried out.

In the first coagulation apparatus along the way, the rotation of the mixer is controlled within 100-300 rpm. The apparatus is equipped with a two-tier propeller-type mixer with a different-angled arrangement of the blades to ensure complete coagulation and the formation of the required size of crumbs and a changed angle of the pulp exit from the coagulation apparatus and ensures complete removal of crumbs. The slope angle of the pneumatic transport and coating the inner surface with a composition having low adhesion to crumbs also facilitate the removal of the crumbs released.

Example 4. In a container for coagulation pour 1000 ml of production latex of styrene-butadiene rubber with a dry residue of 20.5% and heat it (40-60 ° C). While stirring, a certain amount of one of the obtained coagulants (0.5-10 ml of a 4% aqueous solution) is added to the container, stirring is continued for another 5-10 minutes and a 1-10% solution of sulfuric acid is introduced to pH≈2. After stirring for 10-20 minutes, coagulation is completely completed, serum is transparent. The extracted rubber is washed with water and dried in the usual way at ≈65 ° C for 3-4 hours, then the moisture content of the product is determined. The consumption of reagents is up to 0.25% by weight of the allocated rubber. The degree of extraction is up to 99.8%. The resulting polymer chips are evaluated for uniformity (conditioning) by size. Separate conditioner chips smaller than 6 mm and more than 2 mm.

The isolated product dries well, is well filtered, and in terms of moisture content and uniformity of the size of the crumbs, it meets the necessary requirements for rubber. The moisture content in rubber is not higher than 0.2-0.4%, which corresponds to standard values.

Example 5. To 100 kg of latex of styrene butadiene rubber add coagulant KP at the rate of 0.25% by weight of rubber. The latex is heated to 70 ° C and a 10% solution of sulfuric acid is slowly introduced to a pH of 2.5, then vigorously stirred. Latex is completely coagulated and excreted in the form of loose crumb, which dries well at 70 ° C. Rubber is obtained with a moisture content of 0.2%, while a similar crumb obtained by coagulation according to the prototype has a moisture content of 0.72%. The crumb obtained using the claimed coagulant is uniform in size, does not stick together in agglomerates and does not stick on the walls of the apparatus and in the mixer.

Example 6. To 1000 ml of wastewater containing latex chloroprene rubber at a concentration of 10 g / l, add 2.5 ml of a 4% aqueous solution of coagulant APK-46, which is 1% by weight of rubber. The mixture is thoroughly mixed and the formation of a well-formed, easily filtered precipitate from non-coalescing large polymer chips is observed. 1 hour after the introduction of the coagulant, the clarification effect is more than 97%.

The use of the "APC-46 Cationically Active Polymer Flocculant" or "KP Coagulant" allows for complete coagulation, binding of leucanol, and improvement of the physicomechanical properties of the released rubber (uniform distribution of oil, drying kinetics, fractional composition of crumbs). Quick and easy preparation of a quality-stable APK-46 or KP solution reduces the load on the expellers to 100 amperes / hour, ensures environmental safety due to the absence of toxic properties. These coagulants can be used both in the treatment of industrial, washing, and wastewater. The coagulant solution is stable over time, does not change its effectiveness when standing. Significantly reduced the lack of protein coagulant, as its low resistance to decomposition, leading to the appearance of an unpleasant odor

The improved quality of treated wastewater allows the use of discharged effluents for recycling water supply to the SK plant. The coagulants APK-46 and KP are non-combustible and non-explosive. They make it possible to treat wastewater from the production of synthetic latex with higher efficiency than the known coagulants, with the exception of “lumpy” coagulation, which complicates the process of separating the polymer precipitate. The proposed coagulants do not reduce the stability of rubber isolated from latex during thermal aging, and provide its plasticity even after heating. The moisture content of the resulting rubber meets the standard. The polymer crumb is not prone to clumping, uniform in composition.

An industrial test of the "Cationically active polymer flocculant APK-46" and "Coagulant KP" at the Omsk plant SK showed the whole range of the above advantages of this product over others, both in terms of technological and economic indicators, even in relation to low salt coagulation.

More than 10,000 tons of rubber grades were produced: SKMS - 30 ARK, SKMS - 30 ARKPN, SKMS - 30 ARKM - 15, SKMS - 30 ARKM - 15, SKN. The resulting rubbers meet all the requirements of GOST.

Claims (5)

1. Coagulant for the isolation of synthetic rubbers from liquid media, obtained on the basis of the protein component, characterized in that as additional to the protein component of the ingredients it contains carboxymethyl cellulose, urea, α- and β-amylase, fatty amine compounds, urea-formaldehyde resin and formalin the following mass content of all components, wt.%: Protein component 45.0-46.0 Carboxymethyl cellulose 16.0-17.0 Urea 10.1-10.2 α-amylase 9.4-9.5 β-amylase 9.4-9.5 Fatty Amino Compounds 8.8-8.9 Urea-formaldehyde resin 0.03-0.04 Formalin 0.02-0.03 2. The coagulant according to claim 1, characterized in that 50% of the content of amino compounds are alkylbenzyldimethylammonium chloride. 3. The coagulant according to claim 1, characterized in that the protein component is animal or vegetable protein or a mixture thereof. 4. Coagulant according to any one of claims 1 to 3, characterized in that it is used in the form of a 3-8% aqueous solution. 5. The coagulant according to any one of claims 1 to 3, characterized in that its flow rate during the purification of liquid media is 0.1-1.0 wt.% Relative to the mass of rubber released.