RU2447087C2 - Method of extracting butadiene-(alpha-methyl)-styrene rubber from latex - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to extraction of synthetic rubber from latex, particularly extraction of butadiene-(alpha-methyl)-styrene rubber. The method of extracting butadiene-(alpha-methyl)-styrene rubber from latex, which is stabilised with carboxylic acid soap and sodium salt of naphthalene sulphonic acid, is carried out using 0.5% sulphuric acid solution and a polyelectrolyte coagulant. The polyelectrolyte coagulant is an epichlorohydrin and dimethylamine copolymer obtained with molar ratio of reactants (1.03-1.10):1, or is a product of reaction of natural and organic compounds, having free amine groups, obtained by grafting a synthetic polymer to a carbohydrate backbone under the effect of an enzyme, said synthetic polymer forming side chains of the polyelectrolyte or poly(N[-3,5-ditertbutyl-4-oxybenzyl)ethylene amine. Latex is introduced into a serum medium which contains sulphuric acid and the polyelectrolyte coagulant at a rate which prevents formation lumps at temperature 20-40°C. Further, the formed rubber crumbs are separated from the serum, washed with water at pH 6.5-8.0 and the rubber crumbs are separated from the washing water, dehydrated, dried and briquetted.

EFFECT: higher extraction of rubber due to considerably low stickiness of the formed rubber crumbs.

1 tbl, 15 ex

Description

The invention relates to the field of isolation of synthetic rubbers from latexes stabilized with carboxylic acid soaps and sodium salt of naphthalene sulfonic acid, and can be used in the production of synthetic rubbers by emulsion polymerization.

A common method for isolating synthetic rubbers from latexes stabilized with carboxylic acid soaps is the use of coagulation of latexes with electrolytes - sodium chloride and sulfuric acid (P.A. Kirpichnikov, L.A. Averko-Antonovich, Yu.O. Averko-Antonovich. Chemistry and Technology synthetic rubber. - L .: Chemistry, 1970, p. 395-399, 402-403). However, electrolyte coagulation has a significant drawback: mineral salts, having passed treatment plants, are completely discharged into natural water bodies, which leads to their salinization and environmental degradation.

Known methods for the isolation of rubbers from latexes using polyelectrolytes as coagulants (AS USSR No. 859377, IPC C08C 2/06, C08C 1/14, 1979; AS USSR No. 1700007, IPC C08C 1/15, 1991; RF patent No. 2067592, IPC C08F 236/10, C08C 1/15, 1994). Known methods include coagulation of latexes with small amounts of highly effective polymer coagulants in an acidic environment at a temperature of 55-65 ° C. The use of polyelectrolytes as coagulants can completely eliminate the use of sodium chloride and significantly improve the environmental characteristics of the process of rubber separation from latexes. The widespread introduction of salt-free coagulation into the production process is hindered by the increased stickiness of the resulting rubber crumb, which leads to clumping and clogging of equipment.

This problem is partially eliminated by the use of coagulation, combining the introduction of polyelectrolytes and small amounts of sodium, calcium and / or magnesium chlorides. It is known the use of protein coagulants in combination with sodium chloride for the isolation of rubber from latex (V.V. Moiseev, O.K. Popova, V.V. Kosovtsev. The use of proteins in the production of elastomers. Thematic review. - M .: TSNIITENeftekhim, 1985, p. 33-34). This technique can significantly reduce the stickiness of crumb rubber and the consumption of sodium chloride. However, its significant drawback is the formation of very fine crumbs of rubber, which leads to large losses of it with washing water.

The use of the APK-46 coagulant based on the protein component, combining the positive properties of synthetic cationic coagulants and natural high molecular weight compounds, is also known. As additional ingredients to the protein component, the coagulant contains carboxymethyl cellulose, urea, fatty amine compounds, urea-formaldehyde resin (RF patent No. 2281293, IPC C08C 1/15, C08C 2/06, C02F 1 | 56, 2005). The APK-46 coagulant in the form of a 3-8% solution is introduced into latex at a temperature of 40-60 ° C in an amount of 0.1-1.0% relative to the mass of rubber released, after which a 1-10% sulfuric acid solution is introduced to pH≈2. The use of this coagulant allows for complete coagulation, to bind leucanol, to improve the physical and mechanical properties of the released rubber (uniform distribution of oil, drying kinetics, fractional composition of crumbs). Significantly reduced the lack of protein coagulant, as its low resistance to decomposition, leading to the appearance of an unpleasant odor. However, when using this latex coagulation method, the increased stickiness of the rubber crumb remains.

A known method of isolating synthetic rubbers from latexes by introducing a polymer amine coagulant and an antiagglomerator selected from the group: calcium chloride, magnesium chloride, bischofite (RF patent No. 2203228, IPC C08C 1/15, C08C 1/14, 2002). The disadvantage of this method is to increase the mineralization and water hardness of natural reservoirs when they discharge treated wastewater from the coagulation stage. In addition, when coagulating latexes using this method, water-insoluble calcium or magnesium soaps of carboxylic acids are formed, which leads to an increase in the content of carboxylic acids and ash soaps in rubber above the regulated values, i.e. to receive substandard rubber.

A known method of isolating styrene-butadiene rubbers from latex under the action of lignin in the form of sodium, potassium or ammonium salt, polyamine and sulfuric acid with the continuous introduction of latex, solutions of lignate, polyamine and acid with the required certain speed in the coagulation apparatus or cascade of coagulation apparatus, coagulation temperature 40-80 ° C and pH 2.5-3.5 (US patent No. 4025711, IPC C08C 1/00, C08C 1/14, C08F 6/22, 1977). The resulting rubber crumb is characterized by high porosity, which facilitates drying of the rubber. However, the use of this allocation method does not significantly reduce the stickiness of the rubber crumb.

The closest in essential distinguishing features and the achieved effect to the proposed method is a method for isolating synthetic rubbers from latexes, described in RF patent No. 22253656, IPC C08C 1/15, 06/10/2005 - prototype.

According to the prototype, the isolation of synthetic rubber from latex is carried out by the action of mineral acid and an organic amine coagulant, supplied in an amount of 0.01-1.0 wt.% Per rubber mass in two doses: the first portion of coagulant in an amount of 50-90 wt.% Of its total dosages are administered directly in 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 salt in a mass ratio of amine coagulant: mineral salt from 1: 0 to 1: 1500 is administered in the coagulation apparatus of owls estno serum with the recycle in a weight ratio of latex: serum from 1: 1 to 1: 2.

An advantage of the method is the possibility of an operative influence on the size and porosity of the rubber crumb and the completeness of coagulation by changing the dosage of the second portion of the coagulant. The disadvantage of this method is the need to introduce in addition to the organic coagulant mineral salt to eliminate the increased stickiness of crumb rubber.

The technical task of the invention is to increase the manufacturability of the salt-free coagulation process of latex by reducing the stickiness of the resulting rubber crumb.

The problem is solved in that in the inventive method for the isolation of butadiene- (α-methyl) styrene rubber from latex, latex is introduced into a serum medium containing sulfuric acid and a coagulant-polyelectrolyte at a rate excluding clotting at a temperature of 20-40 ° C.

When implementing the proposed method as a coagulant-polyelectrolyte using:

- a copolymer of epichlorohydrin with dimethylamine obtained with a molar ratio of reactants (1.03-1.10): 1 - “EPAM reagent”, TU 2494-008-55868659-2003;

- a product of the interaction of natural and organic compounds having free amino groups obtained by grafting to a ridge of carbohydrate under the action of an enzyme of a synthetic polymer forming the side chains of a polyelectrolyte - “APK-46", TU 2482-001-74068031-2005;

- poly (N-3,5-ditretbutyl-4-hydroxybenzyl) ethyleneimine - "OMP", TU 38.40371-03.

Significant distinguishing features are the introduction of the entire amount of coagulant-polyelectrolyte in serum and the coagulation of latex at a temperature of 20-40 ° C. The temperature regime of coagulation has a significant effect on the structure of polymer particles, changing their morphology. Reducing the coagulation temperature to 20-40 ° C leads to a decrease in the stickiness of the rubber crumb and its adhesion to metal surfaces. The definition of “stickiness” is based on recording the force required to separate two identical rubber samples, and the “stickiness” is based on recording the force required to separate a rubber sample from a steel plate by tearing at right angles.

The essence of the invention is confirmed by the following examples.

Example 1. To 400 ml of serum (0.5% solution of sulfuric acid) at a temperature of 20 ° C add 6 ml of a 2% solution of coagulant "EPAM Reagent" (at the rate of 3 g / kg of rubber), mix for 10 minutes and with continued stirring, 200 ml of SCS-30 ARC latex with a dry residue of 20% is fed from a separatory funnel at a rate excluding clot formation. The coagulated polymer in the form of coarse chips is separated from serum, washed with softened water with the addition of a 10% sodium hydroxide solution to pH 6.5-8.0, and dried in a convective dryer at a temperature of 70-80 ° C.

The conditions for implementing the method of example 1 and the results are presented in the table.

Example 2. The selection of rubber from latex is carried out as in example 1, but using latex SCMS-30 ARC with a dry residue of 20.1%, coagulation is carried out at a temperature of 30 ° C. The conditions for implementing the method of example 2 and the results are presented in the table.

Example 3. The selection of rubber from latex is carried out as in example 1, but using latex SKMS-30 ARKM-15 with a dry residue of 19.8%, coagulation is carried out at a temperature of 40 ° C. The conditions for implementing the method of example 3 and the results are presented in the table.

Example 4. The selection of rubber from latex is carried out as in example 1, but using latex SCMS-30 ARC with a dry residue of 20.1%, coagulation is carried out at a temperature of 60 ° C. The conditions for implementing the method of example 4 and the results are presented in the table.

Example 5. The selection of rubber from latex is carried out as in example 1, but coagulation is carried out at a temperature of 15 ° C. The conditions for implementing the method of example 5 and the results are presented in the table.

Example 6. To 400 ml of water at a temperature of 40 ° C, 200 ml of SCS-30 ARC latex are dosed with a dry residue of 20%, 6 ml of a 2% solution of coagulant "EPAM Reagent" and 25 ml of a 2% solution of sulfuric acid to pH 3 at a rate excluding clot formation. The coagulated polymer in the form of coarse chips is separated from serum, washed with softened water with the addition of a 10% sodium hydroxide solution to pH 6.5-8.0, and dried in a convective dryer at a temperature of 70-80 ° C.

The conditions for implementing the method of example 6 and the results are presented in the table.

Example 7. Isolation of rubber from latex is carried out as in example 1, but SKMS-30ARK latex with a dry residue of 20.1% is used, “APK-46” is used as a coagulant, and coagulation is carried out at a temperature of 20 ° C. The conditions for implementing the method of example 7 and the results are presented in the table.

Example 8. The selection of rubber from latex is carried out as in example 1, but using latex SKMS-30ARK-15 with a dry residue of 19.8%, as the coagulant used "APK-46" and coagulation is carried out at a temperature of 30 ° C. The conditions for implementing the method of example 8 and the results are presented in the table.

Example 9. The selection of rubber from latex is carried out as in example 1, but as a coagulant used "APK-46" and coagulation is carried out at a temperature of 40 ° C. The conditions for implementing the method of example 9 and the results are presented in the table.

Example 10. Isolation of rubber from latex is carried out as in example 1, but SCMS-30ARK latex with a dry residue of 20.1% is used, "APK-46" is used as a coagulant, coagulation is carried out at a temperature of 55 ° C. The conditions for implementing the method of example 10 and the results are presented in the table.

Example 11. To 200 ml of latex SKS-30 ARK with a dry residue of 20% at a temperature of 40 ° C add 6 ml of a 2% solution of the coagulant APK-46, mix for 10 minutes and with continued stirring, 400 ml of 0.5% a solution of sulfuric acid to pH 2. After stirring for 10-20 minutes, coagulation is completely completed, serum is transparent. The selected rubber is washed with softened water with the addition of a 10% sodium hydroxide solution in it to a pH of 6.5-8.0 and dried in a convective dryer at a temperature of 70-80 ° C.

The conditions for implementing the method of example 11 and the results are presented in the table.

Example 12. Isolation of rubber from latex is carried out as in example 1, but using latex SKMS-30ARK with a dry residue of 20.1%, coagulation is carried out at a temperature of 20 ° C, using 3.3 ml of a 5% solution of coagulant "OMP" ( based on 4.1 g / kg of rubber). The conditions for implementing the method of example 12 and the results are presented in the table.

Example 13. The isolation of rubber from latex is carried out as in example 1, but using latex SKMS-30ARK with a dry residue of 20.1%, coagulation is carried out at a temperature of 30 ° C, using 3.3 ml of a 5% solution of coagulant "OMP" ( based on 4.1 g / kg of rubber), coagulation is carried out at a temperature of 30 ° C. The conditions for implementing the method of example 13 and the results are presented in the table.

Example 14. The selection of rubber from latex is carried out as in example 1, but using latex SKMS-30ARKM-15 with a dry residue of 19.8%, coagulation is carried out at a temperature of 40 ° C, using 3.3 ml of a 5% solution of coagulant "OMP "(Based on 4.1 g / kg of rubber). The conditions for implementing the method of example 14 and the results are presented in the table.

Example 15 (prototype). To 200 ml of SCMS-30 ARC latex with a dry residue of 20.1%, 2.3 ml of a 5% solution of the coagulant “OMP” are added with stirring (based on 70% of the total dosage of coagulant 4.1 g / kg of rubber), mixed 30 minutes at a temperature of 40 ° C and mixed with a speed that excludes lump formation, with serum obtained by mixing 400 ml of a 0.5% solution of sulfuric acid with 1 ml of a 5% solution of coagulant "OMP", which is 30% of the total dosage of coagulant at a temperature of 65 ° C. The coagulated polymer is separated from serum, washed with softened water with the addition of a 10% sodium hydroxide solution to a pH of 6.5-8.0, and dried in a convective dryer at a temperature of 80 ° C.

The conditions for implementing the method of example 15 and the results are presented in the table.

From the table it follows that the process of isolation of rubber from latex according to the present method with the dosing of the entire amount of coagulant-polyelectrolyte in serum at a coagulation temperature in the range of 20-40 ° C (examples 1-3, 7-9, 12-14) to increase the manufacturability of the process and achieve 100% completeness of rubber release due to a significant reduction in the stickiness of the resulting rubber crumb and its adhesion compared to known methods in which coagulation is carried out at a standard temperature of 55-65 ° C (examples 4, 10) maintaining the entire amount or most of the coagulant electrolyte directly in latex (examples 11, 15) and at the same time mixing the latex, coagulant polyelectrolyte and acid (example 6). At the same time, the properties of rubber remain consistent with the level of regulatory and technical documentation. When lowering the coagulation temperature below 20 ° C (example 5), the completeness of rubber release is reduced due to the formation of very fine crumb rubber.

Table The effect of coagulation temperature on the completeness of polymer isolation from latex, chem. composition and properties of butadiene- (methyl) styrene rubbers. Coagulant name Reagent "Epam" APK-46 WMD Experience Number one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen fifteen Rubber grade SKS-30ARK SKMS-30APK SKMS-30APKM-15 SKMS-30ARK SKS-30ARK SKS-30ARK SKMS-30APK SKMS-30APKM-15 SKS-30APK SKMS-30APK SKS-30APK SKMS-30ARK SKMS-30APK SKMS-30APK M-15 SKS-30APK Name of parameters: Coagulation temperature, ° С twenty thirty 40 60 fifteen 40 twenty thirty 40 55 40 twenty thirty 40 65 coagulation pH, ° С 2.0 2.5 2,8 2.0 2.5 2.5 2,4 2,4 2.1 2.0 2.0 2,8 3.0 2.6 2,8 rinse water 6.3 7.8 8.0 8.0 7.8 7.8 7.2 7.8 6.3 7.3 7.8 6.5 6.0 6.8 7.8 The completeness of the polymer, wt.% one hundred one hundred one hundred 98 86 98 one hundred one hundred one hundred 98 98 one hundred one hundred one hundred 96 Mass fraction of organic acids,% 5.85 5.8 6.0 5.7 5.8 5.8 5.9 5,4 5.2 5.5 5,6 5.3 5,4 5.5 5.2 Mass fraction of soaps of organic acids,% from from from 0.10 0.12 out from from 0.11 0.12 0.12 0.08 0.10 0.09 0.09 Weight loss during drying,% 0.21 0.16 0.40 0.60 0.50 0.40 0.21 0.24 0.40 0.47 0.38 0.25 0.16 0.21 0.54 Mass fraction of ash,% 0,031 0,029 0,025 0,035 0,028 0,028 0,030 0,030 0,030 0,025 0,027 0,020 0,020 0,031 0,027 Thermostability (ICP),% 89 88 96 90 80 89 85 93 87 83 85 87 88 95 86 Stickiness, g / cm ² 75.9 74.5 63.5 87.1 65.6 85.6 76.0 64.5 77.1 80.1 78.6 74.9 76.1 63.8 83.9 Adhesion, g / cm ² 16.25 17.0 13,4 26.25 16,0 28.15 15.95 11.3 16,2 22.0 17.1 16.5 16.7 14.0 25.8

Claims (1)

The method of isolation of butadiene- (alpha-methyl) -styrene rubbers from latex by the action of a 0.5% solution of sulfuric acid to achieve a pH of serum of 1.0-3.5 and a coagulant-polyelectrolyte selected from a copolymer of epichlorohydrin with dimethylamine obtained by the molar ratio of reagents (1.03-1.10): 1, the product of the interaction of natural and organic compounds having free amino groups, obtained by grafting to the ridge of a carbohydrate under the action of an enzyme of a synthetic polymer forming the side chains of a polyelectrolyte, or poly (N-3,5 Ditretbutyl -4-hydroxybenzyl) ethyleneimine, followed by separation of the resulting rubber crumb from serum, washing the crumb with water with a pH of 6.5-8.0, separating the rubber crumb from the wash water, dehydration, drying and briquetting of the rubber, characterized in that the latex is introduced into medium of serum containing sulfuric acid and a coagulant-polyelectrolyte, with a speed excluding clot formation, at a temperature of 20-40 ° C.