RU2289590C1 - Filled butadiene-styrene rubber production process - Google Patents

Abstract

FIELD: rubber industry.

SUBSTANCE: invention relates to production of butadiene-styrene rubbers via emulsion butadiene-styrene copolymerization process, in particular to isolating rubbers from their latexes in presence of radical initiators. Process is stopped by adding oil filler and antioxidant, after which follows degassing and isolation of rubber from latex by coagulation method. Process is distinguished by that, as filler and antioxidant, fiber/oil/antioxidant composite is used, which is prepared by preliminarily mixing divided unwound fibers with hydrocarbon solution of oil PN-6 containing amine- or phenol-type antioxidant, grinding resulting composite, dispersing it in aqueous phase containing surfactants, and introducing it into rubber in amounts of 2-6% oil and 0.1-1.5% fibrous filler based on the weight of rubber.

EFFECT: reduced loss of rubber, reduced environmental pollution, and improved physico-mechanical 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 P.A., 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 to stabilize the process of rubber isolation from latex, reduce rubber losses with crumbs formed from the separation shops, reduce environmental pollution by rubber products, improve the physical and mechanical properties of vulcanizates.

The problem is achieved in that in the method of producing filled styrene-butadiene rubber by copolymerizing butadiene with styrene in an emulsion in the presence of radical initiators, stopping the process, introducing an oil filler and an antioxidant, degassing and isolating rubber from latex by coagulation, what is new in as a filler and antioxidant use fiber-oil-antioxidant composite obtained by pre-mixing the crushed fiberized fibers with a hydrocarbon with a solution of PN-6 oil containing an amine or phenolic type antioxidant, milling the resulting composite, dispersing it in an aqueous phase containing surfactants, distilling off a low-boiling hydrocarbon fraction and introducing in an amount of 2-6% oil and 0.1-1, 5% fibrous filler on 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 stopper of the radical process (sodium nitrite, rongalite, etc.) is introduced into the system and the resulting latex is sent to degassing, where non-polymerized monomers (styrene, butadiene) and other low-boiling products are distilled off. From the degassing department, latex enters 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 for washing, dehydration, drying and packaging (Raspopov I.V., Nikulin S.S., Garshin A.P. and others. Improving the equipment and technology for the isolation of butadiene- (α-methyl) styrene rubbers from latexes. M .: TsNIITE-neftekhim, 1997.68 p.). This process corresponds to the restrictive part of the claims.

Fibrous materials, which are waste products of various industries (trimming fabrics, threads, tangles, etc.), are subjected to sizing, pulverized to a size of 2-10 mm and mixed with milling with a hydrocarbon solution of PN-6 oil containing amine or phenolic antioxidants. The resulting composite is mixed on a high-speed mixer for 10-15 minutes at a temperature of 60-90 ° C and subjected to additional grinding for 1-3 hours. As a result of this technological operation, oil is rubbed into the fibrous material and dehydrated. The resulting composite with constant high-speed stirring is dispersed in the aqueous phase containing surfactants at 40-60 ° C for 1-3 hours. The dosage of the fibrous filler can withstand 0.1-1.5% for rubber, oils PN-6 - from 2 to 15% for rubber. The use of higher dosages of fibrous filler (more than 1.5% per rubber) leads to a sharp increase in the viscosity of the system, which negatively affects its mobility and transportability through pipelines. After the hydrocarbon solvent is distilled off with a water-water-oil-antioxidant dispersion (VVMAD), it is mixed with SCS-30 ARC latex. Rubber latex containing VVMAD, served on coagulation.

Styrene-butadiene latex SKS-30 ARC, containing VVMAD, is poured into a coagulation tank equipped with a mixing device and placed in a thermostat to maintain a given temperature. It is kept at a given temperature for 10-15 minutes, a coagulating agent, 24% aqueous solution of sodium chloride, is introduced and mixed for 5-10 minutes. The selection process is completed by introducing a 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%. Upon exiting the last polymerization agent, the latex is continuously charged with a stopper - a solution of sodium dimethyldithiocarbamate with sodium nitrite. Latex filled with a stopper passes through the filter and is sent to distill off the non-polymerized monomers to the top of the preliminary degassing column, where the bulk of the 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.

80 g of PN-6 oil, 20 g of solvent (toluene) and antioxidants of the amine or phenolic type are introduced into a container equipped with a mixing device in quantities that meet the requirements of TU for the manufactured rubber brand. The mixture is heated to a temperature of 60-90 ° C with constant stirring and a fibrous filler (cotton, rayon, capron) is introduced, subjected to raking and grinding to a size of 2-10 mm, the resulting mixture is stirred for another 10-15 minutes. The milling of the resulting composite is carried out in a ball mill for 1-3 hours. After milling, the resulting composite is mixed with an aqueous solution containing surfactants - rosin soap, soaps based on fatty acids, tall oil in amounts of 6% and 0.5% leucanol on the dispersible phase and homogenize for 1-3 hours at 40- 80 ° C on equipment equipped with a high-speed mixing device. At the same time, the solvent is distilled off from the resulting dispersion. The dry residue is 30-50%. The resulting dispersion is fed to the SKS-30 ARC rubber styrene butadiene rubber latex in a coagulation vessel equipped with a mixing device and placed in a thermostat to maintain the set temperature. It is kept at a given temperature for 10-15 minutes and, 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 PN-6 oil 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 VVMAD in latex before feeding it to coagulation allows to increase the mass (yield,%) of the formed coagulum, which can be associated both with the additional introduction of oil and fibrous material, as well as due to reduction of losses with the resulting finely divided crumb, carried away from the stage of separation and washing with serum and wash water.

The rubber crumb SKS-30 ARK isolated after coagulation, filled with PN-6 oil 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.

The use of increased dosages of PN-6 oil (14-17% per rubber), corresponding to the brand of manufactured oil-filled rubber SKS-30 ARKM-15, allows to increase the dosage of fibrous filler to 1.5% per rubber (Table 3) and obtain filled rubber, possessing a number of enhanced indicators, which were confirmed by studying the properties of rubber compounds and vulcanizates based on it.

From the above results it is seen that the additional introduction of fibrous material in the amount of 0.1-1.5% and PN-6 oil in the amount of 2-15% per rubber into the composition of the resulting coagulum ensures the best effect of maximizing the coagulum yield and improving indicators of vulcanizates, such as: resistance to repeated stretching, thermal aging and temperature resistance.

Table 1
The effect of the dosage of fibrous filler, PN-6 oil, coagulation temperature on the consumption of sodium chloride and the yield of the resulting coagulum Number of experiments one 2 3 four 5 6 7 8 9 10 eleven Dosage of fiber,% on 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 - - - Dosage of oil PN-6 K,% for 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 175 173 176 180 178 175 176 170 174 177 171 The yield of coagulum formed, wt.% 94.7 95.0 96.6 97.3 98.1 96.5 97.2 96.8 96.3 97.0 96.9 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 PN-6 K oil with fibrous fillers Indicators Type of fibrous filler and its dosage,% for rubber control, oil PN-6 without fiber cotton viscose nylon 0.1 0.5 1,0 0.1 0.5 1,0 0.1 0.5 1,0 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 1,2 1,2 Mass fraction of oil PN-6 K,% 2.0 4.0 6.0 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 52.0 49.0 45.0 52,5 50,0 48.5 55.0 51.0 48.0 rubber compound 56.0 55.0 52.0 56.0 54.0 52.0 55.0 53.0 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 multiple 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

Table 3
Properties of rubbers, rubber compounds and vulcanizates prepared on the basis of rubber SKS-30 ARKM-15, filled with PN-6 K oil with fibrous fillers Indicators Type of fiber filler dosage,% on rubber no cotton viscose nylon Dosage of fibrous filler,% 0 1,5 1,5 1,5 Mass fraction of oil PN-6 K,% fifteen fifteen fifteen fifteen Mass fraction of antioxidant (BC-1),% 0.3 0.3 0.3 0.3 Mooney viscosity, MB 1 + 4 (100 ° C) 41 43 42 42 Conditional tensile strength, MPa 24.8 25.1 24.7 25.9 Elongation at break,% 650 640 660 635 Relative residual deformation,% 16 fourteen 13 12 Resistance to multiple stretching, thousand cycles 53,2 68.1 62.3 70,4 Aging coefficient (100 ° С, 72 h): - by strength 0.52 0.58 0.55 0.61 - relative elongation 0.38 0.45 0.42 0.44

Claims (1)

A 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 an oil filler and antioxidant, degassing and isolating rubber from latex by coagulation method, characterized in that an oil-antioxidant fiber is used as a filler and antioxidant, obtained by pre-mixing the crushed fiberized fibers with a hydrocarbon solution of oil PN-6 containing antioxidant Dant of the amine or phenolic type, by grinding the resulting composite, dispersing it in the aqueous phase containing surfactants, distilling off the low-boiling hydrocarbon fraction and introducing in the amount of 2-6% oil and 0.1-1.5% fibrous filler onto rubber.