RU2291161C1 - Filled butadiene-styrene rubber manufacturing process - Google Patents

Abstract

FIELD: rubber industry.

SUBSTANCE: invention relates to production of butadiene-styrene rubbers obtained via emulsion (co)polymerization, in particular to methods for isolation thereof out of latexes. A process for manufacturing filled butadiene-styrene rubber is described comprising butadiene-styrene copolymerization in emulsion in presence of radical initiators, stopping the process, adding oil filler and antioxidant, and degassing and isolating rubber out of latexes utilizing coagulation technique. Process is characterized by that, as filler and antioxidant, fiber-polymer-antioxidant composite is used, obtained by preliminarily mixing milled garneted fibers with hydrocarbon solution of a low-molecular weight polymer material. The latter is prepared on the basis of (i) still residue of recycled solvent (toluene) purification process in production of polybutadiene rubber and (ii) styrene modified by maleic anhydride and containing amine- or phenol-type antioxidant. Thus obtained composite is grinded and dispersed in surfactant-containing aqueous phase, after which low-boiling hydrocarbon fraction is distilled off and low-molecular weight polymer material and fibrous filler are added in amounts, respectively, 2-6 and 0.1-1.0% based on the weight of rubber.

EFFECT: reduced loss of rubber and environmental pollution at higher physicochemical characteristics of vulcanizates.

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Description

The invention relates to the production of styrene-butadiene rubbers obtained by emulsion (co) polymerization, in particular to methods for filling them at the latex stage, and can be used in the petrochemical industry.

The closest in technical essence is a method for producing filled styrene-butadiene rubbers at the latex stage using naphthenic and paraffin oils as fillers, followed by isolation of the filled rubber with water-salt solutions and an acidifying agent [Kirpichnikov PA, Averko-Antonovich L.A. ., Averko-Antonovich Yu.O. Chemistry and Technology of Synthetic Rubber: A Textbook for High Schools. - 3rd ed., Revised. - L .: Chemistry, 1987. - 424 p., Ill.].

The main disadvantages of this method of producing filled styrene-butadiene rubbers are:

- the formation of fine crumb rubber, which is carried away with serum and wash water from the selection workshops, which leads to a decrease in the productivity of the process;

- violation of the stability of the process;

- environmental pollution by rubber products;

- low resistance to thermo-oxidative effects.

The problem to which this invention is directed is the stabilization of the process of rubber isolation from latex, the reduction of rubber losses with crumbs formed from the separation shops, the reduction of environmental pollution by rubber products, the improvement of the physical and mechanical properties of vulcanizates.

The problem is achieved in that in the method for producing filled styrene-butadiene rubber by copolymerizing butadiene with styrene in an emulsion in the presence of radical initiators, stopping the process, introducing filler and antioxidant, degassing and isolating rubber from latex by coagulation, new is that as filler and antioxidant use a fiber-polymer antioxidant composite obtained by preliminary mixing the crushed fiberized fibers with a hydrocarbon solution rum of a low molecular weight polymeric material obtained on the basis of the bottom residue of refining solvent - toluene production of polybutadiene rubber and styrene modified with maleic anhydride containing an amine or phenolic type antioxidant, milling the resulting composite, dispersing it in an aqueous phase containing surface-active substances, distilling off low hydrocarbon fraction and the introduction of 2-6% low molecular weight polymer material and 0.1-1.0% fibrous filler and rubber.

The proposed method for producing filled styrene-butadiene rubber can stabilize the coagulation process, reduce rubber losses, reduce environmental pollution and increase the physical and mechanical properties of vulcanizates.

The method is as follows

The copolymerization of butadiene with styrene is carried out in a battery consisting of 10-12 polymerization apparatuses, in the presence of radical initiators (for example, pinane hydroperoxide). After reaching a conversion of 65-70%, a radical stopper is introduced into the system (sodium nitrite, rongalite, etc.) and the obtained latex is sent to degassing, where non-polymerized monomers (styrene, butadiene and other low-boiling products) are distilled off. From the degassing department, the latex is transferred to coagulation where it is mixed with an oil-antioxidant emulsion and agents that release rubber from latex (an aqueous solution of sodium chloride and sulfuric acid). The resulting crumb of rubber is fed to washing, dehydration, drying and packaging (Raspopov I.V., Nikulin S.S., Garshin A.P. et al. Improving the equipment and technology for the isolation of butadiene- (α-methyl) styrene rubbers from latexes. M: TsNIITEneftekhim, 1997, 68 p. .). This process corresponds to the restrictive part of the claims.

A low molecular weight polymeric material (NPM) was obtained by copolymerization of unsaturated compounds (4-vinylcyclohexene; cyclododecatriene-1.5.9; n-dodecatatetraene-2,4,6,10) contained in the bottoms of the purification of the return solvent - toluene with styrene in the presence of aluminosilicate catalysts. This process has been implemented on an industrial scale. The NPM obtained after leaving the last apparatus of the polymerization battery was mixed in the reactor with maleic anhydride and heated at 160-200 ° C for 5-15 hours (Tutorskii I.A., Potapov E.E., Shvarts A.G. Chemical modification elastomers. M: Chemistry. 1993. 304 S.). Properties of the NPM obtained on the basis of the bottom residue of the purification of the return solvent — toluene from the production of polybutadiene rubber and styrene modified with maleic anhydride: color on the iodometric scale (IMS) - 200-400; molecular weight - 1100-1500; acid number - 5-6 mg KOH / 100 g; the content of maleic anhydride is 3-5%.

At the first stage, a modification of the low molecular weight styrene-containing copolymer obtained on the basis of bottoms from the purification of the return solvent, toluene, and the production of polybutadiene rubber by maleic anhydride is carried out. The modification process was carried out as follows. A low molecular weight copolymer was charged into the reactor and ~ 3% maleic anhydride was introduced. The reactor was sealed and with constant stirring, the process was carried out at 160-180 ° C for 15-20 hours. The resulting modified polymer material was a dark brown oily product readily soluble in hydrocarbon solvents.

Fibrous materials, which are waste from various industries (trimming fabrics, threads, thread, etc.), are crushed to a size of 2-10 mm and mixed with a hydrocarbon solution of low molecular weight polymer material (NPM), obtained on the basis of unsaturated compounds contained in the bottoms of the rectification of the return the solvent is toluene and styrene modified with maleic anhydride containing amine or phenolic antioxidants. The resulting composite is mixed on a high-speed mixer for 10-15 minutes at 60-90 ° C and subjected to additional mashing for 1-3 hours. As a result of these technological operations, oil is rubbed into the fibrous material and dehydrated. The resulting composite with constant stirring is dispersed in the aqueous phase containing surfactants at 40-80 ° C for 1-3 hours. The dosage of the fibrous filler can withstand 0.1-1.0% per rubber, NPM - from 2 to 6% per rubber. The use of higher dosages of fibrous filler (more than 1.0% per rubber) leads to a sharp increase in the viscosity of the system, which negatively affects its mobility and transportability through pipelines. The resulting water-fiber polymer antioxidant dispersion (GDP) is fed into mixing with SCS-30 ARC latex. Rubber latex containing GDPA is fed for coagulation.

Styrene-butadiene latex SKS-30 ARC, containing VVPAD, is poured into a coagulation tank equipped with a mixing device and placed in a thermostat to maintain a given temperature, kept at a given temperature for 10-15 minutes, a coagulating agent is introduced - a 24% aqueous solution of sodium chloride and mix for 5-10 minutes. The selection process is completed by introducing a 1-2% aqueous solution of sulfuric acid. pH coagulation withstand 2.0-2.5. The resulting coagulum is separated from serum, washed with water and dried at a temperature of 80-85 ° C. The completeness of coagulation was evaluated visually (transparent serum — complete coagulation), as well as by the mass of the formed coagulum.

The method is illustrated by the following examples.

The copolymerization of butadiene with styrene is carried out according to a continuous scheme on a battery consisting of 12 polymerizers. The aqueous and hydrocarbon phases (a mixture of 70% butadiene and 30% styrene), a radical initiator (hydroperoxides of isopropylbenzene, pinan, etc.) and a molecular weight regulator (tertiary dodecyl mercaptan) are fed into the first polymerizer during the process. Additional amounts of molecular weight regulator are introduced into the process before the fifth and ninth polymerizers. The polymerizers are equipped with agitators. The copolymerization of butadiene with styrene is carried out at 4-8 ° C. The process is conducted until the conversion of 65-68%. When leaving the last polymerization unit, the latex is continuously filled with stopper - a solution of sodium dimethyldithiocarbamate with sodium nitrite. The latex, filled with a stopper, passes through the filter and is sent to distill off the unpolymerized monomers to the upper part of the preliminary degassing column, where the main amount of butadiene is distilled off. After the preliminary degassing column, the latex is sent to a vacuum stripper, where styrene and the remaining butadiene are distilled off. Latex from the degassing department is fed to coagulation.

Into a tank equipped with a mixing device, 80 g of NPM, 20 g of a solvent of toluene and antioxidants of the amine or phenolic type are introduced in amounts that meet the requirements of TU for the manufactured rubber brand. The mixture with constant stirring is heated to a temperature of 60-90 ° C and a fibrous filler (cotton, viscose, nylon) is introduced, the resulting composite is mixed for another 10-15 minutes, after which it is subjected to grinding in a ball mill for 1-3 hours. An aqueous solution containing surfactants — rosin soap, soaps based on fatty acids, tall oil in amounts of 3-6% and leucanol 0.5% per dispersible phase — is introduced into the resulting composite and mixed on a high-speed mixer at 40-80 ° С within 1-3 hours. After that, the obtained water-fiber-polymer-antioxidant dispersion (GVPAD) is fed to the SKS-30 ARC rubber styrene butadiene rubber latex into a coagulation vessel equipped with a stirrer and placed in a thermostat to maintain the set temperature and kept at the set temperature for 10-15 minutes. Then, with constant stirring, a 24% aqueous solution of sodium chloride is introduced. To complete the coagulation process, an acidifying agent is introduced in the form of a 1-2% aqueous solution of sulfuric acid. The consumption of sulfuric acid is 15.0 kg / t of rubber. coagulation pH 2-2.5. After coagulation, the resulting coagulum is separated from serum, washed with water and dried at a temperature of 80-85 ° C. The completeness of coagulation was evaluated visually (transparent serum — complete coagulation), as well as by the mass of the formed coagulum.

Table 1 shows examples of the effect of temperature, dosage of NPM and fibrous material (% on rubber) on the process of rubber isolation from latex. The experimental data presented in Table 1 show that the additional introduction of GDP in latex before feeding it to coagulation allows to increase the mass (yield,%) of the formed coagulum, which can be associated with both the additional introduction of NPM and fibrous material, as well as due to reduction of losses with fine crumbs carried away from the stage of separation and washing with serum and wash water.

The rubber crumb SKS-30 ARC isolated after coagulation, filled with NPM and fibrous fillers, was dried in an oven at a temperature of 80-85 ° С. Subsequently, based on the filled rubber SKS-30 ARK, a rubber mixture was prepared according to the standard formulation and vulcanizates based on it.

Table 2 shows the indicators of rubbers, rubber compounds and vulcanizates of standard rubbers based on the selected rubbers SKS-30 ARK.

From the above results it is seen that the additional introduction of 2-6% NPM into the composition of the resulting coagulum and 0.1-1.0% fibrous material on rubber, the best effect is observed, which consists in achieving the maximum coagulum yield and improving such properties of vulcanizates as : resistance to repeated stretching, thermal aging and temperature resistance.

Table 1 The effect of dosage of fibrous filler and NPM, coagulation temperature on the consumption of sodium chloride and the output of the resulting coagulum Number of experiments one 2 3 four 5 6 7 8 9 10 eleven Mass fraction of fiber,% per rubber: Cotton 0 0.05 0.1 0.5 1,0 1,2 - - 0.5 0.5 0.5 Viscose 0 - - - - - 0.5 - - - - Kapron 0 - - - - - - 0.5 - - - Mass fraction of NPM,% on rubber 0 one 2 four 6 8 four four four four four Coagulation temperature, ° С 60 60 60 60 60 60 60 60 40 80 60 Sodium chloride consumption, kg / t rubber 175 168 164 175 176 179 176 173 168 169 173 The yield of coagulum formed,% 94.7 95.0 97.0 97.8 98.4 98.0 97.0 97.2 97.1 96.9 97.5 Mass fraction of antioxidant,%: VTS-150 1,2 1,2 1,2 1,2 1,2 1,2 1,2 1,2 1,2 1,2 BC-30A - - - - - - - - - 1,5

table 2 Properties of rubbers, rubber compounds and vulcanizates prepared on the basis of rubber SKS-30 ARK, filled with NPM with fibrous fillers Indicators Type of fibrous filler and its dosage,% for rubber control, oil PN-6 without fiber cotton viscose nylon 2.0 4.0 6.0 0.1 0.5 1,0 0.1 0.5 1,0 0.1 0.5 1,0 Dosage of NPM,% on rubber - - - 2.0 4.0 6.0 2.0 4.0 6.0 2.0 4.0 6.0 Mooney Viscosity Rubber 53.0 50,0 47.0 54.0 51.0 49.0 52,5 50,0 48.5 55.0 51.0 48.0 rubber compound 56.0 55.0 52.0 57.0 56.0 55.0 56.0 54.0 51.0 59.0 57.0 52.0 Plasticity according to Carrera r / cm usled 0.36 0.38 0.39 0.35 0.37 0.38 0.31 0.32 0.34 0.33 0.35 0.36 Conditional tensile strength, MPa 24.1 22.0 20.7 25.5 24.0 23,2 26.0 24.5 23.0 26.5 25.8 24.4 Elongation at break,% 660 690 680 660 675 690 680 690 695 670 675 680 Relative residual deformation,% eleven 12 12 10 10 10 12 eleven 10 12 eleven 12 Resistance to repeated stretching, thousand cycles 62.9 60,2 64,2 67.0 71.6 70,2 72,2 81.3 80.8 89.7 83.1 79.0 Aging coefficient (100 ° С, 72 h): - by strength 0.50 0.49 0.52 0.56 0.59 0.59 0.58 0.65 0.58 0.69 0.66 0.70 - relative elongation 0.35 0.37 0.34 0.40 0.41 0.44 0.34 0.37 0.39 0.40 0.42 0.41

Claims (1)

A method of producing filled styrene-butadiene rubber, which consists in copolymerizing butadiene with styrene in an emulsion in the presence of radical initiators, stopping the process, introducing an oil filler and antioxidant, degassing and isolating rubber from latex by coagulation, characterized in that fiber-polymer is used as filler and antioxidant -antioxidant composite obtained by preliminary mixing of crushed fiberized fibers with a low molecular weight hydrocarbon solution of the polymeric material obtained on the basis of the bottom residue of the purification of the return solvent — toluene — production of polybutadiene rubber and styrene modified with maleic anhydride containing an amine or phenolic type antioxidant, milling the obtained composite, dispersing it in the aqueous phase containing surfactants, distilling off low-boiling hydrocarbon fractions and the introduction of 2-6% low molecular weight polymer material and 0.1-1.0% fibrous filler per rubber.