RU2603653C1 - Method of extracting butadiene-styrene rubber from latex - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to petrochemical industry, in particular, to production of butadiene-styrene rubber obtained by emulsion (co)polymerisation, and can be used for extraction of rubber obtained by emulsion polymerisation from latex. Method of extracting butadiene-styrene rubber from latex, includes using N,N-dimethyl-N,N-diallylammonium chloride, poly-N,N-dimethyl-N,N-diallylammonium chloride as coagulants and sulphuric acid as an acidifying agent. Latex, before mixing with solutions of coagulants and acidifying agents, is treated with a constant magnetic field with intensity of 8.0-22.0·10⁴ A·m^-1 for 5-15 minutes at temperature 20-60 °C.

EFFECT: proposed method enables to reduce consumption of coagulants, cost of products and water consumption of shops for separating rubber from latex; enables to obtain a product with improved physical and mechanical properties; reduces environmental load in region.

1cl, 7 ex, 3 tbl, 1 dwg

Description

The invention relates to the petrochemical industry, in particular to the production of styrene-butadiene rubbers obtained by emulsion (co) polymerization, and can be used to isolate rubbers obtained by emulsion polymerization from latexes.

Due to the fact that the traditionally used industrial methods for the isolation of styrene-butadiene rubbers from latexes involve the use of large quantities of sodium chloride or other inorganic salts, as well as mineral acids that enter water bodies together with wastewater, it is relevant to search for more environmentally friendly ways to isolate rubbers from latex, allowing to reduce the harmful environmental burden on the environment.

The basis of these methods is the use of organic coagulants (flocculants), in particular synthetic high molecular weight cationic polyelectrolytes, among which quaternary ammonium polymer salt poly-N, N-dimethyl-N, N-diallylammonium chloride (PDMDAAH), commercially available, is of particular interest. under the trademark VPK-402, as well as a copolymer based on it with sulfur oxide (SPDMDAAHOS).

A known method for the isolation of butadiene- (α-methyl) -styrene rubber, in which mineral salts (sodium chloride, magnesium chloride, etc.) are used as a coagulating agent, introduced into the latex in the amount of 140-160 kg / t of rubber based on dry substance , then an acidifying agent and serum are introduced until a pH of 3.5-4.5 is created and rubber crumb is released.

Closest to the proposed method is a method for the isolation of butadiene- (α-methyl) -styrene rubber “Effect of the concentration of the dispersed phase on the patterns of rubber isolation from latex” by coagulation of rubber latex in an acidic medium using polymeric quaternary ammonium salts as a coagulating agent, consumption which ranges from 3.0 to 5.0 kg / t of rubber. [Nikulin S.S., Verezhnikov V.N., Poyarkova T.N., Vostrikova G.Yu. The effect of the concentration of the dispersed phase on the patterns of rubber release from latex. Journal of Applied Chemistry, vol. 73, no. 10, 2000, S.1720-1724].

The disadvantage of this method is that the polymer quaternary ammonium salts have high antiseptic activity, and if they slip into the treatment plant, they can lead to the death of activated sludge and disruption of the treatment plant, these polymer cationic coagulants have a high cost.

An object of the invention is to develop a method for the isolation of styrene-butadiene rubber from latex, which allows to reduce the consumption of coagulating agents (quaternary ammonium salts), to reduce the cost of production, to improve the quality of vulcanizates and rubber compounds, to reduce the water consumption of the rubber isolation workshops from latexes, which reduces environmental stress in the region.

The technical task of the invention is achieved by the fact that in the method for the isolation of styrene-butadiene rubber from latex, including the use of quaternary ammonium salts as coagulating agents and sulfuric acid as an acidifying agent, it is new that N, N-dimethyl- is used as coagulating agents N, N-diallylammonium chloride (DMDAAX), poly-N, N-dimethyl-N, N-diallylammonium chloride (PDMDAAH, VPK-402), and the latex, before being mixed with solutions of coagulating and acidifying agents, is treated with a constant magnetic field with yazhennostyu from 8,0-22,0 × 10 ⁴ A m ^-1 during 5-15 minutes at a temperature of 20-60 ^° C.

The technical result of the invention is to use pretreatment of styrene-butadiene rubber latex with a magnetic field, to reduce the consumption of coagulating agents (quaternary ammonium salts), to reduce the cost of production, to improve the quality of vulcanizates and rubber compounds, to reduce water consumption by the rubber separation workshops from latexes, which leads to a decrease in environmental stress.

As the product containing the polymer cationic flocculant, N, N-dimethyl-N, N-diallylammonium chloride (DMDAAH), poly-N, N-dimethyl-N, N-diallylammonium chloride (PDMDAAH, VPK-402) containing, according to TU, not less than 25 wt.% Of the basic substance, as well as a copolymer of DMDAAH with sulfur oxide (SPDMDAAHOS). VPK-402 polyelectrolyte is used in the oil and gas industry, in water treatment technologies for the treatment of natural and waste waters.

In figure 1. presents a schematic diagram of an installation for processing latex styrene-butadiene rubber SKS-30 ARC. The installation is: 1 - winding of an electromagnet; 2 - shoes of an electromagnet; 3 - heating device with a sample; 4 - yoke; 5 - power supply; 6 - potentiometer; 7 - power source of the heating device; 8 - power source. The installation consists of an electromagnetic inductor made in a portable version. The magnetic yoke made of steel grade 10880 (GOST 11036-75) is mounted from two movable shoes. Magnetizing coils made from PSD wire are interconnected in series. The electromagnet is connected to a special power supply, from which a current of up to 12 A is supplied to the coil windings.

The magnetic field is regulated by the magnitude of the supplied current and the distance between the poles of the electromagnet. The installation allows you to create a magnetic field with a strength of 8.0 to 22.0 · 10 ⁴ A · m ^-1 . To create the necessary thermal regime in the area of the working cell, a special heating element with a universal power source is used. Information about the thermal regime in the working cell comes from two chromel - copel thermocouples through a potentiometer. A special device complete with a potentiometer allows for the simultaneous fixation of temperature in the area of the sample and automatic temperature control.

The method is as follows.

Styrene-butadiene latex, charged with an antioxidant, is introduced into a coagulation container made of glass or plastic, and placed in the above installation to expose the sample to a constant magnetic field: at a given temperature of 20 ° C or 40 ° C or 60 ° C and withstand 5- 15 minutes. Then, with constant stirring, coagulating agents are introduced - aqueous solutions of DMDAAX, or PDMDAAX, or SPDMDAAHOS and mixed for 2-3 minutes. Further, without stopping mixing, an acidifying agent - 1-2% aqueous solution of sulfuric acid - is introduced into a coagulation vessel with latex and a coagulating agent until a pH of 2.5-3.5 is reached. The consumption of sulfuric acid is 15.0 kg / t of rubber. The resulting crumb of rubber is separated from the aqueous phase (serum) and, after washing and squeezing, is dehydrated in a drying cabinet. The completeness of coagulation is determined gravimetrically - by the mass of rubber crumb allocated, and visually - by the transparency of the serum. Table 1 presents the results of the influence of the magnetic field, the duration of the processing of latex on the consumption of coagulating agent. Table 2 presents the results of the influence of the duration of the magnetic field treatment and temperature on the flow rate of the coagulating agent.

The method is illustrated by the following examples.

Example 1 (control)

The capacitance measuring 25 × 40 × 70 mm was charged with 50 ml of a latex of styrene butadiene rubber SCS 30 ARC (dry residue 19.8%) obtained by copolymerizing butadiene with styrene in a continuous pattern, after which the latex was added 28 kg · m ^-1 coagulating agent DMDAAH (aqueous solution with a concentration of 5.2%). After stirring for 2 minutes, 12 kg / t of rubber of an aqueous solution of sulfuric acid with a concentration of 2.0% was introduced into latex and mixed for another 2 minutes. The resulting crumb of rubber was separated from the aqueous phase, washed with warm water, squeezed and dehydrated in an oven at a temperature of 80 ^about C.

The full release of rubber from latex is achieved with a consumption of coagulating agent of 28 kg · t ^-1 rubber. The rubber compounds obtained from crumb rubber after vulcanization are tested for physical and mechanical properties. The analysis data are presented in table 3.

Example 2

50 ml latex styrene-butadiene rubber SKS-30 ARK (dry residue 19.8%) was loaded into a container 25 × 40 × 70 mm in size (dry residue 19.8%), placed in a unit for exposure to it with a constant magnetic field (Fig. 1) and kept at a temperature of 20 ^about C for 15 minutes. The magnetic field strength of 8.0 A · m ^-1 . After that, 16.8 kg · t ^-1 coagulating agent DMDAAX (aqueous solution with a concentration of 5.2%) was introduced into latex. After stirring for 2 minutes, 12 kg / t of rubber of an aqueous solution of sulfuric acid with a concentration of 2.0% was introduced into latex and mixed for another 2 minutes. The resulting crumb of rubber was separated from the aqueous phase, washed with warm water, squeezed and dehydrated in an oven at a temperature of 80 ^about C.

As the coagulating agent used DMDAAH (aqueous solution with a concentration of 5.2%). The analysis data are presented in table 3.

The full release of rubber from latex processed by a magnetic field is achieved with a coagulating agent consumption of 16.8 kg · t ^-1 rubber with a magnetic field strength of 8.0 · 10 ⁴ A · m ^-1 with a processing time of 15 minutes.

Rubber compounds obtained from crumbs after vulcanization are tested for physical and mechanical properties.

Table 3 presents the test results in comparison with the corresponding indicators of the control sample (prototype) of rubber SKS-30 ARC according to TU 38.40355-99.

As can be seen from table 3, vulcanizates obtained from rubber extracted from latex using latex magnetic field treatment have improved compared with the control sample (example 1): higher tensile strength and greater resistance to thermo-oxidative effects (aging factors).

Thus, the proposed method for the isolation of styrene-butadiene rubber from latex provides complete coagulation of the latex at a lower cost of quaternary ammonium salts compared to the control sample, and at the same time allows to obtain vulcanizates with improved physical and mechanical properties.

Example 3

A method for isolating rubber from latex was carried out analogously to Example 2. An aqueous DMDAAH solution with a concentration of 5.2% was used as a coagulating agent.

The analysis data are presented in table 3. The analysis of experimental data shows that the consumption of a coagulating agent of 18.0 kg · t ^{-1 is} achieved using a magnetic field of 22.0 · 10 ⁴ A · m ^-1 with a processing time of 5 minutes.

The resulting crumb rubber is separated from serum, washed with water and dried at a temperature of 80 ° C. Rubber compounds obtained from crumbs after vulcanization are tested for physical and mechanical properties. Vulcanizates have higher tensile strength and have greater resistance to thermo-oxidative effects (aging factors).

Example 4

The isolation method was carried out analogously to example 2. An aqueous solution of PDMDAAH with a concentration of 2.1% was used as a coagulating agent. As a source of PDMDAAH, VPK-402 Polyelectrolyte was used.

The analysis data are presented in table 3.

The analysis of experimental data shows that coagulation completeness is achieved with a coagulating agent consumption of 2.3 kg · t ^-1 , magnetic field strength of 8.0 · 10 ⁴ A · m ^-1 , processing time 15 minutes.

The resulting crumb rubber is separated from serum, washed with water and dried at a temperature of 80 ° C. Rubber compounds obtained from crumbs after vulcanization are tested for physical and mechanical properties. Vulcanizates have higher tensile strength and have greater resistance to thermo-oxidative effects (aging factors).

Example 5

Isolation was carried out analogously to example 2. An aqueous solution of PDMDAAH with a concentration of 2.1% was used as a coagulating agent. As a source of PDMDAAH, VPK-402 Polyelectrolyte was used.

The analysis of experimental data shows (table 3) that the completeness of coagulation is achieved with a consumption of coagulating agent of 2.6 kg · t ^-1 , magnetic field strength of 22.0 · 10 ⁴ A · m ^-1 , processing time 5 minutes.

After the coagulation process, the crumb of rubber is separated from the serum, washed with water and dried at a temperature of 80 ° C. Rubber compounds obtained from crumbs after vulcanization are tested for physical and mechanical properties. Vulcanizates have higher tensile strengths and have greater resistance to thermo-oxidative effects (aging factors).

Example 6

The coagulation process was carried out according to the procedure described in example 2. An aqueous solution of SDMDAAXOS with a concentration of 1.8% was used as a coagulating agent.

Analysis of experimental data shows (Table 3) that the consumption of a coagulating agent of 3.8 kg · t ^{-1 is} achieved when using a magnetic field of 8.0 · 10 ⁴ A · m ^-1 with a processing time of 15 minutes.

The separated rubber crumb is separated from serum, washed with water and dried at a temperature of 80 ° C. Rubber compounds obtained from crumbs after vulcanization are tested for physical and mechanical properties. Vulcanizates have higher tensile strength and have greater resistance to thermo-oxidative effects (aging factors).

Example 7

The coagulation process was carried out according to the procedure described in example 2. An aqueous solution of SDMDAAXOS with a concentration of 1.8% was used as a coagulating agent.

An analysis of experimental data shows (Table 3) that the consumption of a coagulating agent of 2.8 kg · t ^{-1 is} achieved when using a magnetic field of 22.0 · 10 ⁴ A · m ^-1 with a processing time of 5 minutes.

The separated rubber crumb is separated from serum, washed with water and dried at a temperature of 80 ° C. Rubber compounds obtained from crumbs after vulcanization are tested for physical and mechanical properties. Vulcanizates have higher tensile strength and have greater resistance to thermo-oxidative effects (aging factors).

As can be seen from table 3, the method makes it possible to reduce the consumption of coagulating agents (quaternary ammonium salts), to reduce the cost of production, and at the same time provides a product with improved physical and mechanical properties.

If the intensity of the constant magnetic field is less than 8 · 10 ⁴ A · m ^-1 , then there is no significant decrease in the coagulating agent. If the intensity of the constant magnetic field is more than 22 · 10 ⁴ A · m ^-1 , then there is no decrease in the consumption of the coagulating agent (Table 1).

The proposed method for the isolation of styrene-butadiene rubber from latex allows:

- reduce the consumption of coagulating agents (quaternary ammonium salts);

- reduce the cost of production;

- provides a product with improved physical and mechanical properties;

- reduce water consumption by the workshops for the separation of rubbers from latex;

- reduce environmental tensions in the region.

Claims (1)

A method for isolating styrene-butadiene rubber from latex, comprising using quaternary ammonium salts as coagulating agents and sulfuric acid as an acidifying agent, characterized in that N, N-dimethyl-N, N-diallylammonium chloride (DMDAAX) is used as coagulating agents , poly-N, N-dimethyl-N, N-diallylammonium chloride (PDMDAAH, VPK-402), and latex, before mixing with solutions of coagulating and acidifying agents, is treated with a constant magnetic field with a strength of 8.0-22.0 10 ⁴ A · m ^-1 for 5-15 minutes at a pace a temperature of 20-60 ° C.

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