RU2247751C1 - Butadiene-styrene rubber recovery method - Google Patents

Abstract

FIELD: rubber industry.

SUBSTANCE: method consists in coagulation of latex with sodium chloride and mineral acid and is characterized by that mineral acid utilized is fiber-acidifying composite obtained by treating fibrous material for 10-60 min with sulfuric acid at 40-80°C, amount of the acid constituting 0.1 to 1.0% on the weight of rubber.

EFFECT: stabilized recovery process, reduced loss of rubber with produced rubber crumb, and weakened environmental pollution with rubber products.

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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 their isolation from latexes, and can be used in the petrochemical industry.

The closest isolation method is the method for isolating styrene-butadiene rubbers using water-salt solutions as coagulating agents, where sodium chloride, calcium chloride and an acidifying agent are used as salts [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 in the case of using sodium chloride as a coagulating agent 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.

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, and reduce environmental pollution by rubber products.

The problem is achieved in that in the method for isolating styrene-butadiene rubber, which consists in coagulating latex with sodium chloride and mineral acid, it is new that a fiber-acidifying composite obtained from processing a fibrous material in a dosage of 0.1-1.0 is used as a mineral acid % on rubber with sulfuric acid at a temperature of 40-80 ° C and for 10-60 minutes.

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

The method is as follows

Fibrous materials, which are cotton, viscose, kapron threads, which are waste products of various industries (trimming fabrics, threads, threads, etc.), are crushed to a thread size of 3-10 mm and are mixed with rubber at a dosage of 0.1-1.0% with an aqueous solution of sulfuric acid of 2% concentration, and are processed with constant stirring at 40-80 ° C for 10-60 minutes. After that, the obtained fiber-acidifying composite is used to isolate rubber from latex.

Styrene-butadiene latexes SKS-30 ARK, SKS-30 ARKPN are poured into a container equipped with a mixing device for coagulation, placed in a thermostat to maintain a given temperature. It is kept at a given temperature for 10-15 minutes, and a coagulating agent, a 24% aqueous solution of sodium chloride, is introduced and mixed for 5-10 minutes. To complete the coagulation process, a fiber-acidifying composite is introduced in the form of a 2% sulfuric acid solution containing fibrous material. coagulation pH is maintained 2-2.5. After coagulation, the resulting coagulum is separated from serum, washed with water and dried at a temperature of 85-90 ° C. The completeness of coagulation was evaluated visually. Transparent serum - complete coagulation, as well as the mass of the resulting coagulum.

The method is illustrated by examples.

Styrene-butadiene latex SKS-30 ARC is poured into a container equipped with a stirring device for coagulation, placed in a thermostat to maintain a given temperature. It is kept at a given temperature, then a 24% aqueous solution of sodium chloride is introduced and mixed. To complete the coagulation process, a fiber-acidifying composite is introduced, obtained by processing viscose fiber with a dosage of 0.5% on rubber with sulfuric acid at a temperature of 60 ° C and for 30 minutes. coagulation pH is maintained 2-2.5. After coagulation, the resulting coagulum is separated from serum, washed with water and dried at a temperature of 85-90 ° C. The completeness of coagulation was evaluated visually. Transparent serum - complete coagulation, as well as the mass of the resulting coagulum.

Other examples of the effect of dosage of fibrous material (% on rubber), temperature, and duration of treatment with an acidifying agent (2% sulfuric acid solution) are presented in Table 1-3.

Thus, the results of the experiments presented in table. 1-3 show that optimal results are achieved in the case of the coagulation process using a fiber-acidifying composite obtained by processing fibrous material in an amount of 0.1-1.0% per rubber at a temperature of 40-80 ° C for 10-60 minutes .

Table 4 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 when using a fiber-acidizing composite as a mineral acid, obtained by processing fibrous material in an amount of 0.1-1.0% per rubber at a temperature of 40-80 ° C for 10-60 minutes, the best effect is achieved, consisting of in achieving maximum yield of coagulum and improving such properties of rubbers and vulcanizates as tear resistance, resistance to repeated stretching, heat aging and temperature resistance.

Table 1
The influence of the dosage of viscose fiber, the duration and temperature regime of treatment with an acidifying agent on the coagulation process Number of experiments 1 2 3 4 5 6 7 8 nine Dose of viscose fiber,% rubber 0 0.1 0.5 1,0 1,5 0.5 0.5 0.5 0.5 The processing temperature of viscose fiber with a 2% solution of sulfuric acid, ° C - 60 60 60 60 twenty 40 80 90 The processing time of viscose fiber with a 2% solution of sulfuric acid, min - thirty thirty thirty thirty 70 60 10 5 Coagulation temperature, ° С 60 60 60 60 60 60 60 60 60 Sodium chloride consumption, kg / t rubber 180 180 174 169 168 178 175 173 178 The yield of coagulum formed, wt.% 94.3 94.9 96.8 97.7 97.8 95.1 96.3 96.8 95.0

table 2
The effect of the dosage of kapron fiber, the duration and temperature regime of treatment with an acidifying agent on the coagulation process Number of experiments 1 2 3 4 5 6 7 8 nine Dosage of kapron fiber,% on rubber 0 0.1 0.5 1,0 1,5 0.5 0.5 0.5 0.5 The processing temperature of kapron fiber 2% solution of sulfuric acid, ° C - 60 60 60 60 twenty 40 80 90 Duration of processing kapron fiber with 2% sulfuric acid solution, min - thirty thirty thirty thirty 70 60 10 5 Coagulation temperature, ° С 60 60 60 60 60 60 60 60 60 Sodium chloride consumption, kg / t rubber 180 179 173 167 166 179 174 170 176 The yield of coagulum formed, wt.% 94.3 95.5 97.9 98.5 98.4 97.3 96.9 97.2 95.0

Table 3
The effect of cotton fiber dosage, duration and temperature regime of treatment with an acidifying agent on the coagulation process Number of experiments 1 2 3 4 5 6 7 8 nine The dosage of cotton fiber,% rubber 0 0.1 0.5 1,0 1,5 0.5 0.5 0.5 0.5 The processing temperature of cotton fiber with a 2% solution of sulfuric acid, ° C - 60 60 60 60 twenty 40 80 90 The processing time of cotton fiber 2% solution of sulfuric acid, min - thirty thirty thirty thirty 70 60 10 5 Coagulation temperature, ° С 60 60 60 60 60 60 60 60 60 Sodium chloride consumption, kg / t rubber 180 180 175 170 170 174 170 180 170 The yield of coagulum formed, wt.% 94.3 95.6 97.8 98.1 98.2 96.3 98.0 95.4 94.9

Claims (1)

A method for isolating styrene-butadiene rubber, which consists in coagulating latex with sodium chloride and mineral acid, characterized in that a fiber-acidifying composite obtained by processing a fibrous material with a dosage of 0.1-1.0% on rubber with sulfuric acid at a temperature of 40 is used as a mineral acid -80 ° C and for 10-60 minutes