Method of removing solvent from a solution of polymers

 

(57) Abstract:

Use: removal of solvent from a solution of polymers containing at least 20 wt. % elastomer. The inventive method of removing solvent from a solution of polymers, pre-heated to 150 - 200C, by filing a solution of polymers in a 3 - or 5-section extruder under a pressure exceeding the pressure of the solvent at boiling, with a speed of 100 to 300 rpm, the pressure in the first section of the extruder ranges from 600 to 800 mbar, in the last section - 5 to 10 mbar, with subsequent evaporation of the solvent and granulating the dry polymer. 1 Il.

The invention relates to a method of removing solvent from a solution of polymers containing elastomers at least 20 wt. % .

Processing of polymer solutions with the purpose of removal of solvent and obtain pellets of the polymer consists of two stages. In the first stage, remove most of the solvent and a relatively viscous solution, which is injected into the degassing apparatus, including one or two screws and a few located on the periphery of the screw holes for removal of solvent vapours.

When applying two-stage systems reduced thermal stabilnosti processing of polymer solutions rubber type (elastomer) in a conventional apparatus with granulation observed binding molecules of the rubber in the cylinder of the extruder, due to the high temperature resulting from pressure relief above the head with this type of granulation.

Spraying solutions of elastomers are required to the minimum content of residual volatile compounds, in the conventional way, the residual content of 0.5 wt. % .

A known method of removing solvent from a solution of polymer containing not less than 20% of the elastomer, pre-heated to 150-200aboutWith the extruder pressure reduction, evaporation of the solvent and granulation of the polymer at the outlet of the extruder [1] .

The aim of the proposed method is a simplification of the technology and increase the efficiency of the process.

This goal is achieved by a method of removing solvent from a solution of polymers containing at least 20% of the elastomer, pre-heated to 150-200aboutWith, by filing a solution of polymer in 3 or 5-section extruder under a pressure exceeding the pressure of the solvent at boiling, with the speed of 100-300 rpm, and the pressure in the first section of the extruder is 600-800 mbar, and in the last section of 5-10 mbar, followed by granulation of the dry polymer.

This pic is vinylaromatic monomers and conjugated dienes, for example, copolymers of styrene with butadiene or styrene-isoprene, in which the content of the conjugated diene monomer is at least 20 wt. % . The method can be applied to thermoplastic elastomeric polymers such as block copolymers of styrene and conjugate diene with a high content of styrene, diene may be partially or fully gidrirovanny.

This way you can remove solvent until the content of residual solvent of 0.11% . It is necessary to remove most of the solvent, namely from 80 to 95% through the hole located at the rear of the feeder. With this technology, not only pasty polymer continues to freely move with the auger, but the solvent can be easily removed, because there is nothing to prevent its passage to the rear of the auger.

Ventilation through the rear part is carried out by preheating the solution to a temperature of 150-200aboutAnd pressure relief in the boot area of the screw. The pressure relief regulate using the adjustment valve located on the line of the feeder.

Such removal of the solvent can significantly lower the temperature of the polymer solution. In order to achieve high efficiency polymer to a temperature of 150-200aboutS, and the supply of heat can be carried out either by heating the cylinder of the screw to a temperature of 180-250aboutWith, or should be in the auger detail that creates the efforts of the slice, or should be combined in various ways.

If the polymer solution is not heated to the required temperature, the residual solvent content of about 0.1% cannot be achieved.

Residual solvent is gradually removed through various ventilation zone simultaneously with the progress in the auger pasty polymer.

These zones are usually under pressure below atmospheric or equal. Depression increases simultaneously with the promotion of the polymer solution along the screw and varies from atmospheric to a pressure of about 5 mbar at the end of the auger. The number of such zones degassing is usually from three to five, depending on the number you want to delete a solvent.

Water supply can be provided between all zones degassing in order to facilitate solvent removal. Typically, the amount of water injected into a paste-like polymer is from 0.5 to 2 wt. % (based on the polymer.

To achieve effective removal of the Le which is in the range from 150 to 250 rpm

The method described according to the scheme (see the drawing), which illustrates the extruder to remove solvent from a polymer solution containing at least 20% of the polymer.

The polymer solution fed into the feeder 1 of the extruder 2, containing twin screw 3.

The pressure in the extruder and the feed rate adjust using the adjusting valve.

The extruder includes rear ventilation zone 5 through which is given a greater part of the solvent. Pasty polymer is pushed forward by the screw 3. To remove residual solvent on the extruder 2 is provided by the ventilation zone 6. Between ventilation zones there are also unit 7 for inputting fluid, usually water, to facilitate solvent removal.

Pasty polymer separated in the described manner from the solvent passes through the head 8 of the extruder and a pelletizer 9 is cut into pellets.

The following examples are provided to better explain the invention, but in no way limit its scope.

P R I m e R 1. After polymerization in a solution of butadiene and styrene selected cyclohexane solution containing 38% star of stirabout the motor of the extruder twin screw at the rate of 75 kg/h The pressure regulating by means of the valve installed on the supply line.

This extruder has a vent area located at the rear (in the direction of the material) of the feeder, and three area located ahead of the feeder. Head of the extruder and pelletizer installed immediately after the screw (in the course material).

Support the following operating conditions:

The negative pressure in the vent areas in the rear area of 800 mbar

the first front zone 900 mbar

the second front area of 80 mbar

the third front zone 10 mbar

speed - of-rotation 230 rpm

Water Inuktitut before the last two vent areas with a water flow of 1% (based on weight of the polymer.

The solvent is removed by 92% in the rear area, 3% in the first and second front areas and 2% in the last zone. The final volatile content is 0.1 wt. % .

Pressure pre-processing stage 15 bar, the temperature of the material before pelletizing 195aboutC.

The polymer fine granulated without the need for underwater cutting.

P R I m m e R 2. After polymerization in a solution of butadiene and styrene selected cyclohexane solution containing 39% Starovoitova block copolymere coupled by a screw at the rate of 80 kg/h The pressure regulating by means of the valve installed on the supply line.

This extruder has a vent area located at the rear (in the direction of the material) of the feeder, and three area located ahead of the feeder. The head of the extruder and pelletizer installed immediately after the screw (in the course material):

Support the following operating conditions:

The negative pressure in the vent areas in the rear area of 800 mbar

the first front area of 800 mbar

the second front area of 80 mbar

the third front zone 7 mbar

speed - of-rotation 270 rpm

Water Inuktitut before the last two vent areas with a water flow of 1% (based on weight of the polymer.

The solvent is removed by 89% in the rear area, 3% and 6% in the first and second front areas and 2% in the last zone. The final volatile content is 0.1 wt. % .

Pressure pre-processing stage 15 bar, the temperature of the material before pelletizing 192aboutC. the granular Polymer without the need for underwater cutting.

P R I m e R 3. After polymerization in a solution of isoprene and styrene selected cyclohexane solution containing 38% sterilizating block copolymer containing 15% styrene.

Support the following operating conditions:

The negative pressure in the vent areas in the rear area of 800 mbar

the first front zone 600 mbar

the second front zone 60 mbar

the third front zone 9 mbar

speed - of-rotation 220 rpm

Water Inuktitut before the last two vent areas with a water flow of 1% (based on weight of the polymer.

The solvent is removed by 89% in the rear zone, 4 and 6% in the first and second front areas and 1% in the last zone. The final volatile content is 0.1 wt. % .

Pressure before pelleting 8 bar, and the temperature of the material before pelletizing 1180aboutC.

The polymer fine granular, without the need for underwater cutting.

P R I m e R 4. After polymerization in a solution of butadiene and styrene Recuperat 20% solution in cyclohexane Starovoitova copolymer with 45% of the content of the styrene. This RA is/h).

The pressure regulating by means of the valve installed on the supply line. This extruder has a vent area located behind the bunker, and four zones in front of the feeder. Filler and granulator are located immediately behind the screw.

The process is carried out under the following operating conditions:

The pressure in the ventilation areas:

the first front zone 700 mbar

the second front zone 170 mbar

the third front area of 80 mbar

the fourth front zone 3 mbar

speed - of-rotation 300 rpm

Water Inuktitut before the last two zones of ventilation rate of 1% on weight of the polymer.

The solvent was removed: 80% - of the rear area, 10% from 1st front zone, 5% from 2nd front zone, 3% from the 3rd front area and 2% of the 4-th zone. The volatile content was 0.1% by weight. Pressure pre-processing stage 15 bar and a temperature of 195aboutC. the Polymer fine granulated without the need for underwater cutting.

P R I m e R 5. After polymerization in a solution of butadiene and styrene Recuperat 90% solution in cyclohexane Starovoitova 60% of a copolymer containing embracing styrene. This solution at a temperature of 165aboutServed with feeder twin auger (type ZSK-57WP) manufacturer one area ventilation behind the feeder and two zones in front of the feeder. Filler and granulator are right behind the screw. The process is carried out under the following operating conditions:

The pressure in the zones of ventilation: rear area of 900 mbar

the first front zone 900 mbar

the second front zone 30 mbar

speed - of-rotation 50 rpm

Before the last area ventilation water Inuktitut rate of 1% on weight of the polymer.

Solvent extracted: 91% of the rear area, 6% and 3% of the 1st and 2nd zones in front. The volatile content is 0.1% by weight. Pressure pre-processing stage 15 bar and the temperature 192aboutC. the Polymer fine granulated unnecessarily and cutting.

METHOD of REMOVING SOLVENT FROM a SOLUTION of POLYMERS containing at least 20% of the elastomer, preheated to 150 - 200oWith the subsequent decrease in pressure, evaporation of the solvent and granulating the dry polymer, characterized in that, with the aim of simplifying the technology and efficiency of the process, the solution polymers are served in the 3 - or 5-section extruder under a pressure exceeding the pressure of the solvent at boiling, with a speed of 100 to 300 rpm, and the pressure in the first section of the extruder 600 to 800 mbar, and in the last section 5 - 10 mbar.

 

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13 cl, 5 dwg, 1 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: method of degassing an aromatic polymer with an alkylene group is described, in which: a) a product aromatic polymer with an alkylene group in form of a mass of molten polymer is provided, also containing an aromatic monomer with an alkylene group, b) the mass of molten polymer is fed to a first degassing step to obtain a first gaseous stream containing an aromatic monomer with an alkylene group and oligomers, and a second stream containing the remaining part of the mass of molten polymer, c) water is added to the second stream as a washing substance to obtain a third stream containing the remaining part of the mass of molten polymer and water, d) the third stream is fed to a second degassing step to obtain a fourth gaseous stream containing water, an aromatic monomer with an alkylene group and oligomers, and a fifth stream containing a degassed mass of molten polymer, e) the fourth gaseous stream is fed to a separation step to obtain a sixth stream containing water and an aromatic monomer with an alkylene group, and a seventh stream containing oligomers, f) the sixth stream is fed to the separation step to separate an eighth stream containing water and a reduced amount of aromatic monomer with an alkylene group from a ninth stream containing the remaining part of the aromatic monomer with an alkylene group, g) the eighth stream is fed for azeotropic stripping in a stripping column in vacuum conditions using water vapour to obtain an overhead product stream containing water vapour and the main part of the aromatic monomer with an alkylene group which, together with the sixth stream, is fed to the separation step (f), and a bottom product stream containing water and a reduced amount of the aromatic monomer with an alkylene group, at least part of which is returned to step (c) as the washing substance.

EFFECT: reduced amount of water for recycling, reduced consumption of feed water used as the washing substance.

7 cl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a liquid poly-alpha-olefin. The method involves polymerisation in a reaction vessel of a C8-C12 α-olefin in the presence of a saturated C8-C12 hydrocarbon, hydrogen and a catalyst system to obtain an initial product of crude liquid poly-alpha-olefin. The C8-C12 hydrocarbon is fed into the reaction vessel in amount of 5-70 wt %. A stream rich in saturated hydrocarbon is then separated from the removed product of crude liquid poly-alpha-olefin. 5-35 wt % of the stream rich in hydrocarbon is removed from the polymerisation system in form of a blow-off stream to prevent accumulation of by-products and contamination. Saturated C8-C12 hydrocarbons are held in the reaction vessel with content of 8-40 wt % with respect to the combined weight of the C8-C12 alpha-olefin, saturated C8-C12 hydrocarbon and poly-alpha-olefin contained in the reaction vessel.

EFFECT: obtaining poly-alpha-olefins with desirable lubricant viscosity with high conversion, selectivity and output.

14 cl, 8 dwg, 7 tbl, 9 ex

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