RU2563844C1 - Method for mass polymerisation of isoprene in low-volume cells - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: described method for mass polymerisation of isoprene in low-volume cells. The method includes feeding a catalyst system acting in the presence of isoprene. The used catalyst system is a system based on a monomer, which is a conjugated diene, one salt of one or more rare-earth metals of organic phosphoric acid, one alkylating agent of formula AlR₃ or HalR₂ and one halogen donor, which is an alkylaluminium halide. A polyethylene film with thickness of 1-10 mcm is applied on a conveyor belt having hemisphere-shaped cells. The conveyor belt with the film is then heated to 80-120°C. The polyethylene film acquires a fluidity property and accurately repeats the shape of the cells of the conveyor belt. The conveyor belt with the adhered polyethylene film is then cooled by blowing with a cold inert gas. The catalyst system and the monomer are mixed in a mixer at temperature of -80 to -50 C° in ratio of 1/40000 to 1/200000 mol/mol. The ready mixture of the monomer and the catalyst system is then packed using a batcher into polymerisation cells with a volume of 0.01 to 1 dm³ without further mixing of the mixture. Mass polymerisation of the monomer is carried out in each separate cell at high pressure of 1-10 atm and temperature of -50 to +100°C for 90-5 min. The cells of the polyethylene film are sealed with micro-perforations. The cells are evacuated to strip the remaining unpolymerised monomer for 10-600 s. A modifying agent is fed. An antioxidant is fed into each cell. The finished cells with the polymer are removed from the conveyor and the cells with the polymer are divided on a drum with a wavy surface to form separate granules. The granules are unloaded for further packaging.

EFFECT: obtaining a product of high quality and high technological effectiveness, simple process of producing the product, low power consumption and metal consumption of the equipment, high environmental friendliness of production and improved working conditions.

1 dwg, 1 tbl, 10 ex

Description

The invention relates to the chemical industry, namely to the production of polyisoprene.

The most energy-intensive and apparatus-intensive stages are those that go after the polymerization stage of isoprene, i.e. These are solvent rectification plants - isopentane and toluene (distillation columns), degassers (apparatus with a volume of 100 m ³ filled with water at t ~ 100 ° C), condensers, cooling towers, electric motors, instrumentation, pipelines, pumps and etc. etc.

When the process of polymerization of isoprene in bulk (in the absence of solvent) is carried out, all subsequent stages after the stage of introducing stopper and antioxidants (washing the polymer, isolating the polymer, drying the polymer) are excluded from the technological scheme - this is 80% of the metal consumption and 70% of the process energy consumption. A preliminary analysis of information sources showed that currently in the world there are no experimental and industrial plants for the polymerization of isoprene in bulk.

The main tasks that need to be solved are reduced to the heat removal of the polymerization reaction and to overcome the forces of high viscosity friction when mixing the polymerization mass.

Known methods of bulk polymerization described in the patents.

Known patent CN 200610043556.4 (RU 2395528), 04/11/2006, C08F 136/08, China, METHOD FOR SYNTHESIS OF POLYISOPRENE, CHARACTERIZED BY A HIGH LEVEL OF CONTENTS TRANS-1,4-ZENVEN, relating to a method for the synthesis of trans-isoprene containing 1-polyisoprene , 4 links. This method uses block precipitation polymerization of isoprene catalyzed by a supported TiCl4 / MgCl2 titanium catalyst, which includes prepolymerization, polymerization, degassing and drying steps carried out in a prepolymerization reactor equipped with an anchor stirrer, a polymerization reactor equipped with a blade stirrer and a tape mixer vacuum scraper dryer.

The patent claims the advantages of the method compared to existing technologies: high catalytic activity, simplicity of the method, low energy and material consumption, low cost of rubber produced, the technology can be scaled.

In the prepolymerization patent, a large volume of monomer is used, which can cause an increase in temperature. In this way, it is impossible to provide heat removal and, therefore, there is an uncontrolled increase in temperature in the reaction zone to obtain a substandard product.

With a large conversion - a large heat dissipation, and with a low conversion - this method is not cost-effective.

The disadvantages of this method are: the adhesion of rubber in the prepolymer, the performance of the equipment until overgrowing no more than 20 hours, the prepolymer is completely blocked by the polymer

The claimed catalyst residue for titanium is unattainable at the indicated initial ratio: the residue is too small, three orders of magnitude less than the real one. The indicated regiospecificity of the obtained polymer does not correspond to reality, since with a titanium catalyst and polymerization in the mass the usual content of trans-1,4-units is not more than 80%, the product will be crosslinked, the content of the gel fraction is 40%. The scraper mixer will not work due to polymer overgrowing.

Known patent CN 85102250 from 01/17/1987, C08F 136/08, C08F 2/00, C08F 2/02, C08F 36/08, C08F 4/52, China, MASS POLYMERIZATION IN THE PRESENCE OF A RARE EARTH CATALYST, relating to polymerization of isoprene mass carried out in a wide temperature range from minus 78 to plus 100 degrees Celsius. The catalytic system may be based on neodymium or praseodymium-neodymium enrichment of aluminum alkyl chlorides or aluminum alkyl halogens; and aluminum trichloride or praseodymium-neodymium enrichment — trialkyl alcohol.

Compared to the state of the art of solution polymerization, bulk polymerization can reduce energy consumption, the amount of catalyst, and improve the properties of isoprene rubber.

The disadvantage of this method is the laboratory description of the preparation of the catalyst without a description of the process and technological equipment related to the industrial method of producing polyisoprene.

For the polymerization process, very low monomer: catalyst ratios are indicated. The regiospecificity of the polymer is poor - the content of cis-1,4 units is very low (96%).

Known patent US 4696984 from 09/29/1987, C08A 4/52, Italy, ISOPRENE POLYMERIZATION PROCESS relating to the polymerization and copolymerization of isoprene by a process carried out in the absence of solvents and in the presence of a catalyst system containing (a) at least one element or a compound of an element of Group IIIB of the Periodic Table, (b) at least one aluminum alkyl derivative, (c) at least one organic halogen derivative, or at least one halide of an element can exist at least f, in two valence states with a halide, corresponding to a higher state than at least one or at least one halogen or at least one hydrogen atom, an acid halide, (d) at least one compound containing one or more hydroxyl groups from which hydrogen can be substituted, the ratio of component (b) to component (a) is equal to or less than 20.

The disadvantage of this method is the laboratory method for the polymerization of isoprene on the appropriate catalysts without a description of the process and technological equipment related to the industrial method of producing polyisoprene.

Known patent adopted as a close analogue No. 2304151 RU from 11/13/2000, C08F 136/08, C08F 136/04, C08F 4/54, C08F 2/02, C08F 2/06, France, SYNTHETIC POLYISOPRENES AND THE METHOD FOR PRODUCING THEM, relating to synthetic polyisoprenes having a high content of cis-1,4 units, and a method for their preparation. A synthetic polyisoprene having a cis-1,4 unit content, measured by carbon magnetic resonance 13 and quantitative analysis using infrared radiation, above 99.0%, is obtained by a process comprising introducing a catalyst system operating in the presence of isoprene. As a catalytic system, a system is used based on at least one monomer, which is a conjugated diene, one salt of one or more rare-earth metals of organic phosphoric acid, one alkylating agent of the formula AlR ₃ or HalR ₂ and one halogen donor, which is an aluminum aluminum halide. The specified salt of the catalytic system is in the form of a suspension in at least one inert saturated hydrocarbon solvent of an aliphatic or alicyclic type, and the molar ratio of the alkylating agent / rare-earth metal salt is from 1 to 5. A polymerization reaction is carried out.

The technical result consists in the fact that the method allows the polymerization of isoprene with sufficient activity at temperatures lower than or equal to 5 ° C, and to obtain polyisoprenes at the indicated low temperatures, in which the content of cis-1,4 units, measured simultaneously using nuclear magnetic resonance carbon-13 and the method of quantitative analysis using infrared radiation, strictly above 99.0%.

The disadvantages of this method are:

- laboratory method of polymerization without a description of the process and technological equipment related to the industrial method,

- a weak ratio of monomer-catalyst, they have 10000/1 mol / mol,

- the polymerization in bulk is not given,

- after polymerization, interruption of the polymerization by the introduction of acetylacetone is described, and the remaining non-polymerized isoprene was extracted by steam stripping, after which the polymer was dried for 18 hours at 50 degrees Celsius and at 200 mm Hg (0.3 atm) and with a nitrogen purge 72 hours - the process under such conditions lasts 5-7 days.

The technical result from the use of the proposed method is to obtain the final product of higher quality and higher adaptability, to simplify the process of obtaining the product, reducing the energy and metal consumption of the equipment, increasing the environmental cleanliness of production and improving working conditions.

The goal is achieved as follows.

The method of polymerization of isoprene in bulk in small cells includes

the introduction of a catalytic system operating in the presence of isoprene, where

as a catalytic system using a system based on at least one monomer, which is a conjugated diene,

one salt of one or more rare earth metals of organic phosphoric acid,

one alkylating agent of the formula AlR ₃ or HalR ₂ and

one halogen donor, which is an alkyl aluminum halide,

polymerization of isoprene in bulk, while

on a conveyor belt in which cells having the shape of a hemisphere are made, a polyethylene film 1-10 μm thick is applied,

the conveyor belt together with the film is heated to a temperature of 80-120 ° C, as a result of which the polyethylene film acquires a flow property and exactly repeats the shape of the cell of the conveyor belt,

the conveyor belt is cooled together with the adjacent plastic film by blowing with cold inert gas: argon, nitrogen,

for the best distribution of the substance of the catalytic system in the mass of isoprene and to prevent the premature start of the polymerization reaction, the catalytic system and isoprene are mixed in the mixer, in the temperature range from minus 80 to minus 50 ° C in a ratio of 1/40000 to 1/200000 mol / mol s exact maintenance of a ratio of components;

the finished mixture of isoprene and the catalytic system is packaged using a dispenser into polymerization cells with a volume of from 0.01 to 1 dm ³ , without subsequent mixing of the mixture, at overpressure to suppress boiling (pricing) of isoprene, in an inert gas, selected from the group: helium , argon, nitrogen, at a temperature of -80 ÷ -50 ° C,

the polymerization process is carried out in a mass of isoprene in each individual cell at an elevated pressure of 1-10 atm and a temperature of from -50 to + 100 ° C for 90-5 minutes,

sealing the cells with a microperforated plastic film,

carry out the process of evacuating the cells to distill off the remaining non-polymerized isoprene for 10-600 s,

supplying a modifying agent selected from the group: chlorine, bromine,

supplying an antioxidant to each cell,

remove the finished cells with the polymer from the conveyor and separate the cells with the polymer on a drum with a corrugated surface to form individual granules,

granules are unloaded for further packaging.

In the drawing, Fig.1 is a block diagram of a device where

1 - a drum for feeding a plastic film,

2 - tension drum conveyor,

3 - lingering feed mechanism,

4 - heat chamber for the formation of cells,

5 - vacuum chamber,

6 - cooling chamber,

7 - dispenser

8 - polymerization chamber,

9 - feed drum

10 - broaching device,

11 - a vacuum chamber,

12 is a modifier feed device,

13 - feed device antioxidant,

14 - universal camera

15 - a device for removing the product from the conveyor belt,

16 - drive drum conveyor,

17 - receiving hopper for the finished product,

18 - capacity with monomer,

19 - capacity with a catalytic system,

20 - mixer

21 - receiver

22 - conveyor belt.

The essence is as follows.

The device contains a conveyor belt 22, which is located on the drive 16 and tension 2 reels, a plastic film designed to cover the conveyor belt is stored on the drum 1. The broaching mechanism 3, which is designed to broach the conveyor belt, consists of two drums rotating in opposite directions . The heat chamber 4 serves to maintain a temperature of 80 to 100 ° C by circulating an inert gas (argon, nitrogen) to heat polyethylene to a highly plastic state. The vacuum chamber 5 is located under the conveyor belt and is designed to create a vacuum (0.7-0.9 atm) in the cells of the conveyor belt to ensure a snug fit of the plastic film to the inner surface of the cells. The cooling chamber 6 is designed to cool the conveyor belt and polymerization cells to a temperature of from -80 to -50 ° C using inert gas circulation (argon, nitrogen). The dispenser 7 is designed for the simultaneous supply of a certain portion of the mixture of isoprene with the catalytic system in the polymerization cells located on the conveyor belt, at the same time the mixture can be fed into 10-500 cells. The polymerization chamber 8 is designed to maintain a certain temperature by circulating an inert gas (argon, nitrogen) to conduct the polymerization process and to ensure the removal of excess heat that is generated during the polymerization reaction. The microperforated film is stored on the drum 9 and is intended for sealing polymerization cells. The broaching device 10, which is designed to broach the conveyor belt, consists of two drums rotating in opposite directions, the upper drum may have a heating surface to a temperature of from 80 to 120 ° C. The vacuum chamber 11 serves to distill off the remaining (non-polarized) isoprene from the polymerization cells. The modifier feed device 12 serves to supply a modifier to each polymerization cell. The antioxidant supply device 13 serves to supply an antioxidant to each polymerization cell. Universal camera 14 provides a serial connection of each of the devices (vacuum chamber 11, modifier feed device 12, antioxidant feed device 13) simultaneously to several polymerization cells (from 10 to 500 cells). The device for removing the product from the conveyor belt 15 consists of two drums rotating towards each other. Drums can have a special profile on the surface for cutting polyethylene tape into individual granules with the finished polymer. The receiving hopper 17 serves to receive the finished product (granular polymer). Capacity 18 is designed to store isoprene at low temperatures from -90 to -50 ° C and has a metering pump for feeding monomer to mixer 20. Tank 19 is designed to store isoprene at a low temperature from -90 to -50 ° C and has a metering pump for feeding the catalytic system to the mixer 20. The mixer 20 is designed for fast and highly efficient mixing of the mixture of isoprene with the catalytic system at low temperatures from -80 to -50 ° C and is a rotary disk apparatus. The receiver 21 serves for temporary storage of the finished mixture of monomer with a catalytic system at low temperatures from -80 to -50 ° C for subsequent supply of the mixture to the dispenser 7. The catalytic system is aged for 20 hours at a temperature of 20 ° C and consists of a conjugated diene-piperylene , neodymium bis-2-ethylhexylphosphate, an alkylating agent-triisobutylaluminum, a halogen donor of diisobutylaluminum chloride in a molar ratio of 10: 1: 9: 2.7.

The method is as follows.

The polymerization process is carried out on a conveyor, which is made in the form of a continuous conveyor belt 22, rotating by means of a drive drum 16. The conveyor belt is made of a release material that can operate in a wide temperature range: from -80 to + 120 ° C, for example tetrafluoroethylene. In the body of the conveyor belt 22 are made cells having the shape of a hemisphere.

In zone No. 1, a plastic film 1-10 μm thick is applied to the conveyor belt 22. The film is fed from the drum 1 by means of two rolls of the broaching feed mechanism 3, rotating in opposite directions, which ensures a dense and uniform fit of the film to the conveyor belt 22 over the entire surface area.

In zone No. 2, the conveyor belt 22 together with the film is subjected to heating in the heat chamber of cell formation 4 to a temperature of 80-120 ° C, as a result of which the polyethylene film acquires a flow property and exactly repeats the shape of the cell of the conveyor belt 22. To ensure a tight fit of the polyethylene to the inner surface of each cell, the cells are evacuated through special channels using a vacuum chamber 5, which is located on the back of the conveyor belt.

Then, in zone No. 3, the conveyor belt 22 is cooled in the cooling chamber 6 together with the adjacent plastic film by blowing with cold inert gas: argon, nitrogen, etc., which ensures the removal of harmful impurities and the required temperature before the polymerization process begins.

Then the tape 22 is served in zone No. 4, where the finished mixture of the monomer and the catalyst system is dosed into the cells. Dosage is carried out using an automatic dispenser 7, which evenly distributes the mixture into the cells, ensuring their filling in 70-95% of the volume.

In zone No. 5 in the polymerization chamber 8, the polymerization process is carried out in the mass of monomer in each individual cell at a temperature of -20 ÷ + 100 ° C. The process takes from 10 to 90 minutes, depending on the temperature and dosage of the catalytic system.

After the polymerization process is completed in the polymerization chamber 8, the conveyor belt 22 is fed into zone No. 6, where the cells are sealed (glued) with microperforated plastic film coming from the feeding drum 9. The film is fed from the roll using two rolls of the broaching device 10, rotating in opposite directions, which provides a dense and uniform fit of the film to the conveyor belt 22 over the entire surface area. The surface of the upper pressure drum of the broaching device 10 is heated to a temperature that provides heat sealing of polyethylene films - lower and upper.

In zone No. 7, the cells are evacuated by connecting a vacuum chamber 11 to distill off the remaining unpolymerized monomer, which is possible due to the use of a microperforated film that allows the monomer vapor to be driven off but prevents the entrained polymer from being carried away. In the same zone, the modifier is fed through the modifier 12 feeder and the antioxidant through the antioxidant feeder 13 to each cell that is still under vacuum - this ensures uniform penetration of the modifier and antioxidant throughout the finished polymer. As an antioxidant used "Agidol-1" in the melt at a temperature of 75-80 ° C.

The granules of the finished polymer in a polyethylene shell are removed from the conveyor belt 22 in zone No. 8 using a product removal device 15, which consists of two drums rotating towards each other, on which the tape is divided into separate granules using the topography of the drums or served as a single tape in the hopper 17 for further packaging.

In zone No. 9 there is a reservoir for storing monomer 18 and a reservoir for storing the catalytic system 19 at low temperatures from -80 to -50 ° C. From the reservoirs 18 and 19, the monomer and the catalyst system are fed into an efficient low-volume mixer 20, where the catalyst system and the monomer are mixed for the best distribution of the substance of the catalyst system in the monomer mass. To eliminate the premature start of the polymerization reaction, mixing in the mixer 20 is carried out in the temperature range from -80 to -50 ° C in a ratio of 1/40000 to 1/200000 mol / mol with exact keeping the ratio of components. Next, the finished mixture of monomer and catalyst system is fed into the receiver 21, where it is contained at a temperature of -90 to -60 ° C and, if necessary, is supplied to the dispenser 7, located in zone No. 4.

findings

This method allows you to:

1) get a higher quality and more technological product,

2) to simplify the process of obtaining the finished product by eliminating from the process the stage of washing the polymer, isolating the polymer and drying the polymer,

3) reduce the energy intensity of the process by 20-40%,

4) reduce the metal consumption of equipment by 40-60%,

5) reduce capital costs for construction by 20-30%,

6) increase the environmental cleanliness of production by reducing harmful emissions of liquid, solid and gaseous wastes,

7) improve working conditions in the workplace.

In all subsequent examples, a catalytic complex was used, synthesized by sequentially mixing the calculated amounts of a solution of neodymium bis-2-ethylhexylphosphate in hexane, piperylene, toluene solutions (16%, mass.) Of triisobutylaluminum (TIBA) and diisobutylaluminium chloride (DIBAC) in a molar ratio: 10/9/2/7 at a temperature of + 20 ° C. Before use in the polymerization process, the catalytic complex was kept at + 20 ° C for at least 20 hours (a homogeneous brown-red solution).

The concentration of [Nd] in the catalyst solution was 1.33 · 10 ^-4 mol / liter, the concentration of isoprene 10 mol / liter.

The dosage of the antioxidant (agidol-1) per polymer is 2% by weight, the dosage of the modifying agent (chlorine, bromine is 0.5 ... 1.0% by weight).

For preliminary experiments, a transparent sealed box with dimensions 800 × 600 × 500 of polymethylmethacrylate with a wall thickness of 20 mm was prepared with the possibility of creating argon pressure in it up to 6 atm and vacuum up to 0.01 atm (ost).

For experiments in a sealed box, a semi-automatic control system was used; subsequently, an advanced control system was applied to the conveyor system, allowing the polymerization of isoprene in bulk to be carried out automatically.

Example I

Pure isoprene from an isoprene pretreatment circuit at a temperature of -80 ° C and a catalytic complex from a catalyst pretreatment circuit at a temperature of -50 ° C in a ratio of 20,000/1 mol were loaded into a 150 ml stainless steel intensive mixer. In an intensive rotary disk mixer, the components were mixed at a temperature of -80 ° C with a rotor speed of 3000 min ^-1 . From an intensive mixer, 50 ml of the resulting mixture of isoprene and catalyst was dosed into a 75 ml cell, the inner surface of which was previously lined with a sterile, softened (~ 120 ° C) polyethylene film with a thickness of 10 μm.

The process of polymerization of isoprene in bulk was carried out in a cell at an ambient argon temperature of 0 ° C and a pressure of 3 atm for 30 minutes. Then, the cell with the finished polymer was sealed using a thermal press with a plastic film (thickness - 10 μm) with microperforation. At the next stage of the process, the unpolymerized monomer was distilled off for 5 minutes by creating a vacuum in the box with a residual pressure of 0.1 atm, after which the pressure in the box was brought to normal by argon etching.

Agidol-1 melt was introduced into the cell with the finished polymer through a needle at the rate of 2%, mass. to the polymer from the antioxidant preparation loop, where it circulated at a temperature of + 80 ° C, and also supplied to the cell from a cylinder of gaseous chlorine in an amount of 0.7 wt%, to the polymer, which acted as a modifying agent. At the final stage, chlorine gas was displaced from the box with argon and the finished polymer was removed from the cell in a thin polyethylene film.

The yield of polyisoprene was -84.7%

]/ растворимость - 6,4/100Intrinsic viscosity [

] / solubility - 6.4 / 100

Mooney viscosity (B-100-1-4) - 79.3

The conditions of the following examples of isoprene polymerization in the presence of a catalyst based on 2-ethylhexylphosphate neodymium, piperylene, TIBA, DIBAC, as well as some properties of the obtained polyisoprene are summarized in Table No. 1.

Claims (1)

A method of mass polymerization of isoprene in small cells, comprising introducing a catalytic system operating in the presence of isoprene, where at least a system based on at least one is used as a catalytic system
one monomer, which is a conjugated diene,
one salt of one or more rare earth metals of organic phosphoric acid,
one alkylating agent of the formula AlR ₃ or HalR ₂ and
one halogen donor, which is an alkyl aluminum halide, conducting polymerization of isoprene in bulk,
characterized in that
- on a conveyor belt in which cells having the shape of a hemisphere are made, a plastic film 1-10 μm thick is applied,
- the conveyor belt together with the film is heated to a temperature of 80-120 ° C, as a result of which the polyethylene film acquires a flow property and exactly repeats the shape of the cell of the conveyor belt,
- produce cooling of the conveyor belt together with the adjacent plastic film by blowing cold inert gas: argon, nitrogen,
- for the best distribution of the substance of the catalytic system in the mass of isoprene and to prevent the premature start of the polymerization reaction, the catalytic system and isoprene are mixed in the mixer in the temperature range from -80 ° C to -50 ° C in a ratio of 1/40000 to 1/200000 mol / a mole with exact adherence to the ratio of components
- produce the packaging of the finished mixture of isoprene and the catalytic system using a dispenser into polymerization cells with a volume of from 0.01 to 1 dm ³ , without subsequent mixing of the mixture, at overpressure to suppress boiling (foaming) of isoprene, in an inert gas, selected from the group: helium, argon, nitrogen, at a temperature of -80 ÷ -50 ° C,
- the polymerization process is carried out in a mass of isoprene in each individual cell at an elevated pressure of 1-10 atm and a temperature of from -50 to + 100 ° C for 90-5 minutes,
- make sealing of the cells with a plastic film with microperforation,
- carry out the process of evacuating the cells to distill off the remaining non-polymerized isoprene for 10-600 s,
- produce the supply of a modifying agent selected from the group: chlorine, bromine,
- produce the supply of antioxidant in each cell,
- remove the finished cells with the polymer from the conveyor and separate the cells with the polymer on a drum with a corrugated surface to form individual granules,
- produce unloading of granules for further packaging.

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