DE852304C - Process and device for the production of interpolymerization products - Google Patents

Description

Process and device for the production of interpolymerization products The invention relates to a method and device for low-temperature polymerization of olefin compounds, especially on polymerization processes, which are a Use solvent for the olefin monomers, in which also the polymerization products are soluble. The invention relates above all to a method and device for Use of a solvent in conjunction with heat exchangers and flow processes to utilize the cold content of the solution of the finished polymers for the purpose Cooling of the solution of unpolymerized monomers for subsequent polymerization.

As in American patents 2,356,127, 2,356,128 and 2 356 129, high-quality elastomeric polymers, especially are important as a substitute for rubber, through copolymerization of Isobutylene and a polyene are produced using lower temperatures a Friedel-Crafts catalyst; according to a semi-continuous process very large quantities of an industrial polymer were produced. The process used a diluent that is miscible with the olefin monomers, but not a solvent for the polymers. This process produces a slurry of the Polymer in the diluent at a lower temperature, which in warm water discharged for the purpose of volatilization of the diluent and unreacted monomers is, and a slurry of the polymer in water from which the polymer by Separation and drying is obtained. The procedure is technically feasible because of the loss of the cold content of the relatively large volume of cold diluent and unreacted olefin monomers, which are emptied into the warm separation container, but very expensive.

It is here to remove the polymer from the reaction vessel It is essential that this is kept in the form of a slurry during the polymerization will. However, it is now largely due to hydrocarbons in the reaction mixture solvated. In order to keep the polymer in the form of sludge particles and an amalgamation To prevent larger dressings, the product must be added from the reaction vessel very low polymerization temperature can be removed in order to reduce the solvation effect to diminish. Furthermore, the. The concentration of the monomer is kept as low as possible be 'in order to avoid the formation of large masses of agglomerated polymer, which interrupt the circulation and do not carry themselves out through the overflow permit.

The molecular weight of the polymer is a function of the one used low temperature, the degree of purity of the reactants and the concentration of the polymer present.

By using pure raw materials in a relatively high concentration a sufficient molecular weight can be achieved at - 50 to - 40 ° or higher Temperatures. In the older process, which the monomer in low concentration must be used to prevent agglomeration and suspension of the slurry but also the temperature can be kept very low to the desired molecular weight to achieve. In the interests of efficient operating times, it turned out to be necessary the polymerization temperature in the range from -85 to -103 ° and the concentration of the monomer in the reaction mixture to be kept below 10%.

The refrigeration requirement makes the process considerably more expensive. The cold content can also not be partially harnessed because the slurry instantly must be discharged into warm water to remove the polymer and unsaturated Compounds from the slurry in the solvent to an aqueous slurry convict.

In addition, the process is not fully continuous because polymer deposited in solid form on the inner surface of the reaction vessel, the transfer from heat on the cooling jacket and periodically at intervals of 20 to 15 hours must be removed. Cleaning requires the reaction vessels to be shut down and used large amounts of solvent, warming to room temperature and restarting of the reaction vessel, which is associated with considerable difficulties, what the Formation of polymers with a different degree of polymerization results.

It has already been proposed to produce the copolymer from the solution of the monomers in a solvent which also dissolves the finished polymer. However, if the usual procedure is followed, this procedure is unsatisfactory because of the very high viscosity of the solutions of the polymers, in particular at low temperatures. Thus about 10% solutions of the copolymer with a S taudinger molecular weight of 35,000 to 60,000 are. most appropriate range, in carbon disulfide at the polymerization temperature not pumpable because of the high viscosity and flow so extremely slowly that they can hardly be handled. The cold solution can only be moved through pipes and pumps in concentrations of less than 4 or 5%. Thus, the older continuous processes are less effective when the polymer is formed in solution because of its concentration limitation. While the cold solution to be treated must be kept below 3, 4 or 5%, a cold slurry is slightly viscous and can be processed at concentrations of 15, 20 or even 25%.

Such a high viscosity also results in very little heat transferability and insufficient and difficult dispersion of the catalyst. It was found well, that a solution of olefin monomers in almost any proportion in a low boiling hydrocarbon such as light naphtha with a boiling point can preferably be presented at about room temperature; particularly suitable Solvents are propane with a boiling point of or close to -40 °, technical Butane with a boiling point of or close to -6 °, pentane with a boiling point of slightly above room temperature, technical grade hexane with a boiling point of or near at + 6c9 °. The mixture of olefins and solvent can be in any concentration be prepared, which is most favorable for the respective molecular weight, in the frame the degree of purity of the reactants and the desired temperature. The good is then cooled (e.g. in countercurrent) in a tubular heat exchanger and with a Catalyst solution added when the temperature has been reduced to a sufficient extent, preferably in a second heat exchanger with a jacket for boiling liquid Ethylene as a refrigerant.

Also liquid ethane, liquid carbon dioxide, liquid sulfur dioxide or other conventional coolants can be used to fill the jacket. the Reaction can then take place in a template at the necessary low temperature up to be carried out at the end. The degree of polymerization is limited by restriction the amount of catalyst limited to the extent that the amount of dissolved solid polymer is so low that the resulting solution has such a low viscosity that it is easy to flow and so low that the heat transfer and the dispersion of the catalytic converter are not adversely affected. This low-grade solution of the polymer and the unpolymerized monomers in the solvent is then allowed to cool the fresh solution of the monomers used; one brings here the temperature of the the first-mentioned solution to the boiling point of the solvent (at this temperature the viscosity is greatly reduced) and drives the main amount of the solvent and the unpolymerized monomers with exclusion of water from and condensed this immediately and uses fresh olefin for reuse as a starting material adds or fractionates the aborted material and mixes it for reuse as a return on. The residue of dissolved solid polymer with a solution concentration from 1o to 35% at a relatively higher temperature then turns into hot Water transferred by means of an atomizer nozzle or other suitable means, to dissolve the solution into an aqueous slurry to volatilize the remainder To transfer diluent and any residues of the monomers; the polymer is then separated from the water, dried and further treated in a known manner.

According to the invention, a mixing device is provided in which isobutylene of a sufficient degree of purity (possibly as a main component) with a Polyene (possibly in a smaller amount) with 4 to 14 carbon atoms in the molecule and 3 to 25 volumes of light naphtha with a boiling point of - 40 to -: - 69 ° Formation of the starting material for the reaction is mixed.

The mixing device is connected to a number of heat exchangers, in which the mixed batch is heated to around the polymerization temperature by a cold Solution of the finished polymer is cooled in countercurrent. The heat exchangers are connected to another heat exchanger, which by boiling liquid Ethylene is cooled. Two corresponding coolers are provided, which alternate as a cooler for the fresh feed or for the circulating partially polymerized Serve material. These two heat exchangers are equipped with valve systems, which allow their functions to be exchanged; one of them is used for Cooling the partially polymerized circulating mixture until it is deposited with Polymer is complete; at the same time the other becomes of deposited polymer freed by washing out and also serves to cool the fresh load.

The heat exchanger equipped with an ethylene jacket, which is used for Cooling of the circulating, partially polymerized material is used with a Mixing nozzle connected, which is also connected to a solution vessel for preparing the solution of the catalyst communicates. The path via the mixing nozzle leads to a reaction template, which is provided with a pump for the circulating liquid, which in turn is connected to the heat exchanger with an ethylene jacket. This creates a through Ethylene-cooled circuit, the ethylene cooler, the mixing nozzle, reaction template and circulation pump. An overflow of the circuit with transfer pump leads to a second reaction template, in which the last traces of the activity of the catalyst come into effect, This template contains a dilute solution of the finished polymer; it is connected to the countercurrent heat exchangers in which the debris is cooled as much as possible while dissolving the reaction product if possible is heated. The emerging solution of the polymer then passes into a series of evaporators, in which the diluting solvent largely and the unreacted monomers practically completely evaporate. A fractionation and condensation system that works under higher pressure, is also to the evaporator for the purpose of recovery, Separation and condensation of the evaporated material connected. The vaporizers will then attached to a separator in which the last traces of the volatile Hydrocarbons are driven out of the solution of the non-evaporated polymer and a slurry of the polymer in water is formed.

Through this sequence of work stages and combination of the Plant a copolymer is formed at low temperature in dilute solution; in this way a polymer is obtained with the least amount of cooling, Drying and separation work for monomers and circulating solvent.

Furthermore, the resulting from filling the reaction vessels Difficulties largely eliminated. The operation can therefore be continuous over longer operating times with maximum throughput and a minimum of work for cleaning and overhaul.

Other objects and details of the invention will appear below Description in connection with the drawing.

Fig. I shows schematically an apparatus for polymerization in a Solution of n-butane; Fig. 2 shows schematically a similar plant for polymerization in a solution of isopentane.

The starting materials for this process are isobutylene and a polyene having 4 to about 14 carbon atoms in the molecule. As a diluent serve z. B. propane, one or more isomeric butanes, one or more isomeric pentanes, one or more isomeric hexanes (possibly also a heptane or octane; however the boiling points of these substances are undesirably high for most purposes). Carbon disulfide and similar substances can also be used.

The number of substances that can be used as diluents is proportional small. Only those substances come into consideration that are at the polymerization temperature are liquid, the polymer dissolve at the polymerization temperature and also dissolve do not react with the catalyst or the reactants. These conditions do not correspond to the lower alcohols that react with the catalyst and are not solvents for the polymer. Also the ethers, aldehydes and organic Acids are eliminated, all of which are non-solvents for the polymer and almost without exception react with the catalyst.

The hydrocarbon solvents are usually obtained from the fixed gases of petroleum cracking. Isobutylene is usually relatively pure, around 96 to 99.5%; any n- or isobutane present is irrelevant. In contrast, the content of unsaturated compounds, such as propylene, butene-1 and butene-2, should be as small as possible. Unsaturated impurities are best kept below 0.5% , butene-2 is best kept below 0.1%.

As mentioned, propane, butane, pentane, hexane, occasionally also heptane or octane or carbon disulfide can serve as the solvent-diluent, as free as possible from troublesome unsaturated compounds. The material preferably consists of a narrow fraction of original naphtha so that unsaturated substances are eliminated as far as possible. Low-boiling saturated compounds in small amounts are not harmful. The high-boiling members are undesirable because they are difficult to separate out of the polymer during slurrying in water and final treatment. Since a large part of the diluent runs back, the material intended for the return must be carefully cleaned. It is best to avoid using mixtures of diluents because mixtures can easily introduce an uncertainty factor for the separation process in handling the return material.

The third component of the mixture is a polyene with 4 to 14 carbon atoms in the molecule, such as butadiene, isoprene, dimethylbutadiene, myrcene, dimethallyl, 2-methyl-3-nonylbutadiene-i, 3 or 2-methyl-4-pentylbutadiene-i, 3 or the like.

For the purposes of the invention, each unsaturated hydrocarbon is with two or more ethylene double bonds, regardless of the structural formula, as third component suitable.

The starting materials are preferably mixed with one another in a mixer of suitable design. Isobutylene is usually supplied as a liquid at room temperature and a pressure of about 2.7 atm. introduced according to the real temperature of the environment. The solvent-diluent is also introduced as a liquid at room temperature under similar pressure conditions, depending on which diluent is used; Pentane and hexane are liquid at room temperature and normal pressure. The proportion in which isobutylene and polyene are mixed with one another is determined by which copolymer is to be produced. If the latter (according to the Wijs method) is to have an iodine number below about 50 and isoprene or a higher polyene is to be used, isobutylene will be present as the main component and the polyene as a minor component. If isoprene is used in addition to isobutylene in a mixture which contains 1 to about 7 percent by volume, the copolymer consists of about 0.3 to 5 mol percent of copolymerized isoprene. Butadiene must be used in an amount of about 30 percent by weight as a constituent of the starting mixture in order to provide a copolymer with 3 to 5 mol percent butadiene. This can be easily done with the present process, because an excess of unpolymerized monomers is irrelevant and a corresponding proportion of butadiene can be easily incorporated by adjusting the starting material, without disruptions to the course of the polymerization, which cannot be avoided with the known processes .

Cyclopentadiene has a significantly higher interpolymerization ratio, namely, it is copolymerized to a greater extent than its proportion in the mixture is equivalent to. Here, too, the desired isobutylene content is achieved by setting the isobutylene content Amount of the mixture slightly copolymerized.

A Friedel-Craftsian is used to carry out the polymerization Catalyst in the form of a liquid, active metal halide. As a catalyst a solution of aluminum chloride in methyl chloride is preferred; this is for Mixtures containing any or all of the polyenes listed above are effective. Almost the same a solution of boron trifluoride in methyl chloride or in a low-boiling one is effective Hydrocarbon, such as in the hydrocarbon used as a solvent-diluent.

Also a solution of aluminum bromide in a suitable hydrocarbon, such as that used as a diluent is useful. Is aluminum bromide not only in methyl or ethyl chloride, but also in the lower-boiling hydrocarbons sufficiently soluble.

The catalyst used is preferably a Friedel-Crafts catalyst in the form of an active metal halide which is soluble in a solvent with a low solidification point and without a tendency to form complex compounds. The Friedel-Crafts catalysts are described by NO Calloway in the article "Friedel-Crafts Synthesis", which was published in the edition of the "Chemical Reviews" published for the American Chemical Society, Baltimore, in the year 1935, Vol. XVII, No. 3, is reprinted; the essay begins on p. 327; the compilation is given by name on p. 375.

As far as the freezing point is concerned, it is sufficient if this is below o ° is, it does not need to be below the polymerization temperature; because the Solution of the catalyst can be used as a liquid above the polymerization temperature added and dissolves in the polymerization mixture before any signs appear noticeable incipient solidification.

From a solvent that is not a complexing agent, only requires that the distillation of the solvent from the solute be a little or negligible deviation of the boiling point of the solution from that of the pure Solvent results and that a small change in the boiling temperature with changes in concentration takes place, furthermore, that the dissolved is consistently unchanged only by evaporation of the solvent can be obtained.

The mixed batch of monoolefin, polyene and solvent-diluent and the solution of the catalyst can be carried out in a conventional manner at conventional temperatures be prepared. These work stages need to be different from those of the known processes indistinguishable, as they are only the starting materials for the polymerization reaction deliver.

According to Fig. I, a first embodiment for the generation of a Copolymer of isobutylene and isoprene with n-butane as a solvent-diluent shows the feed mixture is isobutylene, polyene, and solvent-diluent fed through line i to a series of heat exchangers a 2, 3, 4, 5, 6 (a Series of exchangers is shown for maximum cooling effect; an exchanger could to be used). It is very desirable that the starting mixture should be as low in moisture as possible is. Therefore, the mixed batch is often left on after partial cooling Pass calcium chloride tower 7. The participation of a drying tower is desirable, but not a necessary part of the invention because feed and return previously are well dried by distillation.

The mixed feed passes over from the heat exchangers 2 to 6 Line 8 in a circulation system 9 for the polymerization. This is expedient from at least two ethylene high-performance coolers ii and 12, one of which through corresponding pipeline between the cooler and in the first place the circulation system switched on, the other through lines 14, 15 and 16 to one Nozzle 17 is connected, which in turn via line 18 to a reaction template ig is connected. The latter is with a circulation pump 21, this via lines 22 and 23 connected to the high-performance ethylene coolers ii and 12. The catalyst nozzle 17 is charged with catalyst solution via line 24. Suitable pressure or pumping equipment are located between the storage containers for the mixed feed and pipe i as well as between the storage tank for the catalyst and pipe 24 and provide the feed of starting material and catalyst for the polymerization system 9, as set out above; the piping is arranged so that each of the coolers 12 and 12 is between the circulation system and the coolers 2 to 6, the other of the coolers ii or 12 in the circulation system 9 can be switched on.

The ethylene coolers ii and 12 are connected in parallel with valve regulators, so that one for cooling the circulation mixture, the other for final cooling of the incoming Loading is used. Although the polymerization takes place in a solution, some polymer separates on the walls of the system. This is for that Reaction template 19 insignificant because only one layer of adhering polymer the thermal insulation of the template is improved. There are deposits in the recirculating cooler but undesirable. The fresh, cold batch of isobutylene, polyene and solvent now has a strong dissolving effect on adhering polymer and removes it consequently, when passing through the cooler in the absence of the catalyst, deposits easily occur of the polymer. If then the other cooler accordingly with a deposit is covered, the coolers are switched over in alternation; the cleaned cooler is now used to cool the circulating polymer solution, while the contaminated Cooler for final cooling of the fresh load and simultaneous cleaning of adhering Polymer is used.

A pump 25, which is also connected to the circulation system 9, is expedient is connected to line 16, pushes the polymer solution out of the circulation system 9 on the second side of the heat exchangers 6, 5, 4, 3 and 2. With the outlet side the pump 25 is connected to a reservoir 26 which is used to store the dilute polymer solution and completing the polymerization reaction. The dilute solution of the polymer then passes through the heat exchangers in countercurrent to the fresh feed. At this In the process, the fresh feed enters the circulation system 9 at one temperature a, which is very, close to the polymerization temperature; there is only one caused by the temperature gradient dy'rch the metal wall of the heat exchanger Difference. The diluted polymer solution leaves the last heat exchanger 2 approximates the temperature of the incoming charge; also exists here only one due to the temperature gradient through the metal wall of the heat exchanger conditional difference.

The diluted, heated polymer solution comes from the last heat exchanger 2 under a pressure that is necessary to maintain the liquid state through Line 27 in a preheater 28, in which the temperature is increased further, preferably up to or above the boiling point under the prevailing pressure. the end The diluted polymer solution flows into the prewarming device 28 into a depressurization reservoir 29, in which the diluent and the remaining unpolymerized unsaturated Compounds mostly evaporated and through line 31 to a fractionation system 32, which consists of the bubble tray column 33, are emptied. That’s about there methyl chloride used as a solvent for the catalyst largely for the Preparing new solution of the catalyst recovered.

The residue or lower outlet of the column 33, which is mainly consists of solvent-diluents and unsaturated compounds is then forwarded for storage and can be reinforced by adding isobutylene and polyene to return to pipe i as mixed feed.

For evaporating solvents and removing volatile components quickly in template 29 is a circulation pump 35, the warm polymer solution at the bottom of the Sucks template 29 and conveys it via a cooker 36 to the top of template 29; there A substantial part evaporates, the rest flows off at the bottom of the template. pump 37, which is connected to the bottom of the template 29, sucks a substantial part the warm solution and promotes this in a second withdrawal template 38. This is with a circulation pump 39 and a suitable steam-heated cooker or heat exchanger 41 connected. It should be noted that the heat of vaporization is largely due to steam is supplied in the heat exchanger 41, a circulating stream of the polymer heats up and drives off most of the steam to be extracted. The evaporation takes place thus mainly in submission 38. This second template, the worm exchanger and the circulation pump concentrate the polymer solution up to the highest still flowable one Consistency. The hot vapors released in template 38 flow through a line 42r to the heating vessels 36 and 28 back. The thick residue solution is taken from the template 38 through line 43 and mouthpiece 45 into a filling tube 46, in which there is also a steam tube 47 opens, and emptied from there into a projection 44. Steam line 47 runs into a The nozzle in the filling tube 46 is off. The steam is used for breaking up, atomizing and more Heating up the stream of the focused. Polymerisats and reduced the partial pressure of the solvent vapor due to its dilution.

The mouthpiece is expediently equipped with a nozzle for introducing the polymer stream provided, which mixes with the steam jet .under considerable pressure. Of the The polymer jet can be converted into a concentric steam jet or the polymer can be introduced through a ring of nozzles lying tangentially. Steam jets is surrounded; this achieves the highest degree of turbulence and temperature in the nozzle unit. This system vaporizes practically all volatile substances from the polymer solution and drives the polymer over into particles, which are swirled through by the existing stream of steam and in-.The filling pipe '46 introduced water is humidified and be promoted.

The solution of the hot polymer is highly viscous. In order to obtain an easily flowable, lump-free slurry, the stream of polymer solution must be broken up into relatively small drops at such a high temperature that the remaining volatile constituents are essentially driven off; these particles must be placed in warm water in receiver 44 before they can combine to form larger dressings. Hence the steam jet is off. Pipe 47 supplemented by a water jet from pipe .4o , which is expediently supplied in the form of tangential partial jets. The water comes purposefully. from template 44 and is pumped back from there .by a pump, not shown. The water flowing in through the pipes 4o and / or 5o can be fresh water or a. Be reflux stream of warm water and slurried polymer.

Template 44 is about half filled .mit a slurry of the polymer in water, which enters freshly prepared from tube 46; this template also serves to remove vapors of the solvent and unpolymerized unsaturated compounds from the water and polymer. The vapors from the separating receiver 44 pass into a condenser 48, where the remaining diluent and the remaining monomers are condensed: the dirt in receiver 44 is kept so high that this stream is condensed by means of cooling water.

Most of the process steps described herein can be carried out under considerable pressure. There is a greater leeway for the pressures in the first heat exchangers, the final coolers and the polymerization system; because the boiling points are . both. required low polymerization temperatures below the. Normal boiling points. In the. Various heat exchangers, to which the polymer solution flows through line 27, are fitted with higher overpressures. Pump 25 is used to generate the required pressure. The pressure is appropriately adjusted so that the expelled vapors in template 29 this template, leaving under such a pressure; @ that they are condensed in column 33 at usual temperatures, approximately near room temperature or at cooling water temperature. Accordingly, the methyl chloride distillate can easily be liquefied and used to prepare the catalyst solution and the liquid reflux can be drawn off for further processing. In a similar way, the second stream of the return, which is taken from the heat exchanger 28, can be under such a pressure that it is liquid at the appropriate temperature, for example close to room or cooling water temperature.

The distillate from separator 44 can be kept under such pressure that it is practically complete by cooling water in the heat exchanger 48 is condensed with water under pressure through pipe 51 and liquid hydrocarbons can be discharged through pipe 52 to the separating column 55. If the corresponding Pressures can be used to compress and liquefy the various compressors Gases stay away; the pressures required are easily obtained by pumping liquids generated; the required cooling and thus also the one to be compressed and cooled Coolant quantities are reduced to a minimum.

If a solvent-diluent is used, its boiling point significantly above the boiling points of the catalyst solvent and isobutylene_ is, the last two substances are practically completely in the Templates 29 and 38 evaporated and for the circuit with the exclusion of water in the fractionation column 32 recovered. Practically only that Solvent-diluent and the polyene will volatilize. Needed in these circumstances there is only a moderate cooling effect in the condenser, 48; a mixture of water and solvent leaves the condenser 48 and flows into the sump 49. There the water sinks to the bottom and is removed through the drain pipe 51. The solvent passes over as an upper layer through pipe 52 and is fed by a pump 53 via line 54 fed to a fractionation column 55.

Residual water dissolved in the solvent is passed through in column 55 Tube 56 distilled off. The lower drain made from practically anhydrous original C - and C4-hydrocarbons is, through pipe 57 irr a second fractionating column 58 Discharged: There all butenes and some n-butane are distilled through a pipe 59 into column 61 for the recovery of methyl chloride. The distillate of column 61 consists of methyl chloride, which is not in the templates 29 and 38 had evaporated, and some C4 compounds and runs into the container for preparation the mixed feed for pipe i. The lower outlet of column 61 is through Line 63 emptied into another column 64. The distillate from column 64 consists from C4 compounds with a lot of butene-i, a reactive poison, which through tube 65 be excreted, the lower drain, which consists of relatively pure butane and Isobutylene is made as a return through pipe 66 to the mixer to prepare the Feeding supplied. The lower outlet of fractionating column 58, which is practically all isoprene and the bulk of Contains n-butane, comes through Tube 67 into fractionation tower 68; there are high-boiling impurities as lower drain excreted through pipe 71. Pull the purified isoprene and n-butane up through pipe 69 into the feed mixer as a return for pipe i.

The jet of steam in the filling tube 46, the last traces of the volatile Expels constituents from the polymer, also moisturizes the polymer and breaks it up into relatively small particles, which are slurried in template 44 will. These particles are significantly lighter than water and therefore form on the Water a blanket. By vigorously stirring and circulating the contents of the Template 44 by means of a stirrer, not shown, can be a practical Maintain an even suspension of the polymerizate in water. The slurry is discharged through pipe 72 into a second template 73, in which there are still residues Unsaturated compounds are driven out and emptied through a drain pipe 74. Template 73 is also with an effective agitator to maintain the Slurry fitted; through pipe 75 slurry is constantly fed into the plant discharged to the completion of the polymer.

The latter is not shown in the drawing because it is the usual one Finishing device is; it consists of a drainage system, for example a rotary suction filter, a vibrating sieve or some other separating device or filtering device. A filter press that may be useful in and of itself is less suitable because of the frequent closing and opening of the press; preferably a continuous filter is used. The loose, moist, solid polymer is then advantageously transferred to a dryer by means of a conveyor belt. The latter can be of any type; preferably one uses one with Hot air operated tunnel dryer with a conveyor chain with an anti-adhesive treated, e.g. B. is sprayed with castor oil. The polymer falls onto the belt at the inlet end and runs through the hot air tunnel to the outlet end. The drying temperature is close to the calibration point of the product. The material to be dried is therefore more or less sticky and clumped at the outlet end. The emerging plate from Sintered solid polymer is then cut into transverse strips, which on a Falling conveyor and fed to a press in which the temperature of the Polymerization through mechanical processing up to above the boiling point of water increases and the product becomes plastic, so that the last traces of moisture easily removed.

The polymer leaves the filter device usually with a moisture content of 20 to 80%. The tunnel furnace lowers the moisture content of the emerging polymer to below 1 0/0. Occasionally the moisture content may be less than 0.1%, depending on the needs of the subsequent treatment. Such low values can only be achieved under favorable conditions; In general, it is advisable to use a press which lowers the moisture content below 0.5% , which is sufficient for all known fields of application. The press passes the polymer on to a double roller mill via a conveyor belt, which forms a rolling bead there and from where a practically water- and air-free skin is removed. The latter arrives on a cooling belt; it is cut into square pieces and packed in cardboard boxes, suitably coated on the inside with an anti-adhesive to avoid difficulties in unpacking prior to kneading, mixing and processing into the final shape.

In this embodiment, the raw charge is, as described above, preferably made from about 95 to 98% isobutylene and 2 to 5% isoprene. The mixture is then mixed with the solvent-diluent, preferably unsaturated Compounds free butane, as it comes from the cleaning system, diluted. As has already been noted, it does not matter whether n-butane or isobutane is used for this will; but it should contain as little butene-1 or butene-2 as possible.

At the same time, a solution of the catalyst, preferably aluminum chloride, in methyl chloride in a concentration of around 0.1 to 2.0%; occasionally can also use more concentrated solutions, even to the point of saturation will. Naturally, there is no cold load at the start of operation in the heat exchangers 2 to 6; the feed then has to go through the ethereal cooler ii and 12 are running, which do all of the cooling work at times.

When the circulation system 9 is filled with the charge and the temperature has fallen to the desired degree of cold, which is preferably between -95 and -103 °, the catalyst is fed in through pipe 24 and mixing nozzle 17. The polymerization begins as soon as the concentration of the catalyst reaches the critical minimum or the threshold value and cold polymer solution flows through pump 25, receiver 26 and heat exchangers 6, 5, 4, 3 and 2. The cooling of the incoming charge by the flowing polymer solution in countercurrent brings about a very significant saving, namely from 45 to 55 % of the energy expenditure otherwise required for the cooling. The cooling required is limited to the interception of the heat of reaction in the circulation system 9 (in addition to the usual cold losses due to leakage).

As has already been shown, that is achievable by liquid ethylene Polymerization temperature preferred; it enables the use of less pure ones Isobutylene. If isobutylene and isoprene of slightly higher purity or a a little more concentrated monomer are available, liquid athan can be used for Final cooling can be used; it provides an operating temperature of -88 to about - 8o °. Enable even more highly purified reagents or higher concentrations the use of carbon dioxide, which has a working temperature of about -78 to results in about - 68 °. Substances of the highest degree of purity and highest concentration provide a usable polymer with liquid propane as a coolant at working temperatures of about -4o to about -35 °.

The polymerization reaction takes place mainly in the reaction vessel i9 and in the presence of abundant solvent, which the polymer formed should keep in solution instead. Sometimes small portions of the polymer remain adhere to the inner surface of the reaction vessel i9. But this is irrelevant because no heat exchange takes place through the wall of the reaction vessel Deposition of the polymer does not affect the operation and at long time intervals can be removed.

The amount of catalyst solution required to interpolymerize a given quantity of mixed olefins varies greatly with the purity and physical state of the charge and the solvent for the catalyst. The charging range is about 0.45 kg of aluminum chloride to about 136 to 1135 kg of polymer produced. The reason for these fluctuations is not yet fully understood. Perhaps these are due to trace amounts of contaminants such as hydrogen chloride, moisture, and many other substances that may be present in small amounts even with the most careful cleaning of the mixed feed components and catalyst solvent. As stated, the polymer solution leaves the last heat exchange at a temperature which comes very close to that of the incoming mixed charge, which can be between room temperature and the boiling point of the mixed charge.

The diluted polymer solution heated to almost boiling point is fed via a preheater to a withdrawal receiver in which the diluent and the unsaturated residual monomers are largely driven off to about% to '/ b.

It should be mentioned that this evaporation takes place with the exclusion of water and that the more volatile catalyst solvent in the first separation work of the Evaporator is selectively evaporated, leaving a pure catalyst solvent can be displayed with the least amount of additional cleaning work and no dewatering stage needs to be switched on. Furthermore, the C4 material largely anhydrous obtained during the second separation work and runs to mix with the feed without further treatment after condensation in the first digester 36 and preheater 28 back.

The combination of countercurrent heat exchange and anhydrous concentration under pressure results in a very significant saving in energy for cooling and Feeding and cleaning and fractionated separation of the return material, Also highlights the need for compression of gases and costly drying of the return streams with chemical adsorbents. Limit cleaning measures relying on the steam flow from the separators, which is only a small part of the total return flow.

The strongly concentrated solution is made from the last evaporator, which advantageously contains at least 15%, better 20 to 25% polymer, one added dispersing steam jet in the filling tube 46 and thereby practically complete freed of volatile components and by condensed steam or water of others Origin, which maintains the dispersion, moisturizes. The steam jet and the circulating water carry the moistened solid polymer in the form of the smallest Particles in a template of hot water in the separation vessel from where the largest Part of the solvent and traces of unpolymerized unsaturated compounds removed. The remaining solvent from the separator is natural contaminated with a lot of water vapor from the hot water and therefore not easily usable in the return system. By condensation of the distillate from the separator most of the water can be separated in a settling tank; this makes the difficulty largely remedied by cleaning, and the very low tendency of hydrocarbons for the formation of hydrates allows final purification only by distillation, after which the hydrocarbons by fractionation in butane. Isobutylene and isoprene in pure form, suitable for return and remixing, separated from each other will.

The broken stream of polymer drips into a water reservoir in the separation vessel 44 and there forms a permanent slurry, the, at the bottom discharged, a withdrawal vessel for further removal of volatile components and then under the pressure of a pump through pipes of a drainage device as mentioned above, such as an Oliver filter, a vibrating sieve, a Sieve belt or another dewatering device. The screen drying is reduced the water content down to 50 ° / a or less. The polymer is then a fed to a steam-heated tunnel dryer, in which the moisture content is reduced to 10 /, or less, and from there a twin rolling mill or press, to bring the moisture content below 0.5%.

The method together with the device according to the invention enables the polymerization and copolymerization of isoolefins and polyenes in the range from o to -164 °, preferably in the range of -40 or -35 and -1o3 °, with only for absorption the heat of reaction and the heat quantum needs to be cooled, which by the product of the specific heat of the polymer mixture and the temperature gradient the heat exchange is shown in the building material; This is only a relatively small part of the amount needed to cool the material and absorb it the total heat required for the heat of reaction.

According to the invention, a relatively small volume is mixed Olefin with a considerably larger volume of solvent, such as butane, cools the mixture in countercurrent in heat exchangers with cold polymer and leads the cold mixture in a recycle polymerization system in which the cold mixture from olefin and solvent by means of heat exchangers with a jacket for are equipped with liquid coolant, further cooled will and which also comprises a nozzle for injecting the catalyst and a reaction vessel; the heat exchangers serve alternately as final coolers for the feed and as a cooler for the polymerization mixture. The polymer solution running off from this system is after passing the countercurrent heat exchanger for the purpose of evaporation of the The bulk of the solvent is heated further. What remains is a warm, more concentrated one Solution, which is then mixed with steam and hot water with brisk agitation is to make the solution of the polymer in the solvent in a slurry of the polymer in water, from which the polymer is filtered off and is dried. The first evaporated part of the solvent is excluded evaporated from water and is therefore readily usable as a return. The second Part of the solvent evaporated by means of steam is condensed and separated from the water and fractionally distilled to remove undesired residue; the desired Shares serve as a return.

The method of operation and the device described according to the invention are particularly suitable for the use of butane as a solvent-diluent for the polymerization reaction. On a higher boiling solvent such as isopentane, can be used, especially for processing butadiene as polyene. Therefor a heat exchange cooling system that is essentially identical to the one described is used, which is shown in FIG. The cooling system, which consists of feed line i and Heat exchangers 2, 3, 4, 5 and 6, and if necessary with a calcium chloride tower 7 cooperates, discharges the chilled charge through pipe 8 into a like Polymerization circulation system g. The latter comprises ethylene cooler ii and 12, which alternate by means of lines 14 and 15 via a circulation line 16 with an injection nozzle 17 for the catalyst to an inlet line 18, a polymerization vessel i9 and a Circulation pump 21 are connected, corresponding to the system shown in Fig. I. The polymer solution flows through pump 25, receiver 26 and heat exchanger 6, 5, 4, 3 and 2 to the emptying line 27 and from there to the preheater 28, cooker 36 and Kocher template 29. The modification can be made here that the pipeline 31 for the volatilized material through the preheater 28 and from there into a condenser 131 and pump 132 is running.

When using n-butane or isobutane as the solvent diluent, most of the methyl chloride is removed from the catalyst solution, most of the isobutylene and most of the butadiene, if the latter is used, from the polymer solution in receiver 29; about 3/4 of the diluent is evaporated; the mixture is discharged through line 133 into a fractionation tower 134, the lower outlet of which is admixed directly with the feed as return. The distillate, which consists essentially of pure methyl chloride, is readily suitable for preparing the catalyst solution. From the bottom of the template 29, the thickened polymer solution is fed through the pump 37 and pipe 43 to a nozzle 45 in the filling tube 46, which is connected to a separating template 44. Steam line 47 is provided with a nozzle which is connected to the nozzle 45 for the polymer solution and a tangential nozzle for fresh water or water flowing back from the receiver 44. This nozzle assembly breaks up the polymer solution into relatively small particles, quickly drives the rest of the volatile constituents out of the solid polymer and at the same time converts the solution into a suspension of the polymer in water. The latter is dehydrated in a filter to about 50% residual water and then introduced into a tunnel dryer, where the moisture content is reduced to a value suitable for mixing on the rolling mill. The distillate from initial charge 44 consisting of residual pentane, unsaturated compounds, traces of methyl chloride and water is compressed in the condenser 48. The condensate runs into a separating vessel 49, where the water settles and is removed through a discharge pipe 51. The pentane condensate flows through line 52, pump 53 and line 54 into a fractionation tower 55, from which the residual water is distilled off at the top through pipe 56 and the lower outlet is transferred through pipe 57 into a second tower 58. The remaining methyl chloride is distilled from this; the lower outlet is emptied through pipe 67 into a third fractionation column 68, the lower outlet of which is introduced into a fourth fractionation column 169. There pentane distills over and serves as reflux, while the lower drain is removed. The distillate from the third column 68 is fed to a fifth column 171 in which butadiene is separated off from the C 1 purification stream by extraction distillation with acetone. You can also use other methods, e.g. B. the extraction with a copper salt solution, operate. The lower outlet from column 171 comes through line 172 into a sixth column 173, the lower outlet of which, composed of acetone and water, returns to column 171 as reflux. The distillate is fed to a butadiene scrubber 174 from which high-grade butadiene is withdrawn at the top and is returned directly to the feed mixer. The lower drain of water and impurities is poured away. The distillate from column 171 contains C4 impurities and is disposed of.

The differences between Figs. I and 2 are approximate the deviations in the process and equipment-related relationship that are related to Adaptation of the system to the use of different types of polymerization substances and solvents are attached.

Method and device according to the invention are particularly useful for more difficult Polymerizations used. Produced by polymerization according to known methods a copolymer of isobutylene and isoprene, their copolymerizability ratio is approximately equal to one; a mixture of 95 to 98 parts of isobutylene with 5 to 2 parts Isoprene provided a copolymer with 1 to 2.5 or 3 mol percent copolymerized Isoprene. This material is a valuable substitute for Rubber, In particular for the production of motor vehicle hoses and impermeable articles as well as for many other areas of application.

The poisoning effect of isoprene or of isoprene-introduced impurities on the reaction has been found to be significant; if more than about 10, 12 or 15% isoprene is used, it is difficult to achieve a sufficiently high molecular weight. Butadiene is a much weaker reactive poison, but the ratio for the interpolymerizability is far lower. If polymers containing 3 to 5 mol percent polyene are to be produced using butadiene, 30 to 75% of the latter must be used (remainder isobutylene). The mixture of unsaturated compounds is diluted with a large amount of diluent. The relatively high proportion of butadiene solvates the polymer in a suspension in methyl chloride. As a result, the polymer can only be removed from the polymerization vessel with difficulty because it tends to form clumps and clings to the vessel wall. Up to now, a reaction vessel for the polymerization of butadiene as a polyene could not be operated continuously because of the very considerable manufacturing difficulties. The present method overcomes these difficulties. The polymer always remains dissolved, and consequently no deposit problems arise.

According to the present process, polymers can be made from isobutylene and produce butadiene, which the copolymerized butadiene to 10 to 50 mol percent with a correspondingly high iodine number of up to 175.

The method according to the invention also overcomes most of the difficulties in the production of other copolymers from isobutylene with numerous Polyenes have so far appeared.

The method and apparatus of the invention are particular for manufacture of hard resin suitable, that of butadiene as the main component and one less light copolymerizable monoolefin, such as isooctane, referred to as the dimer (shown by dimerization of isobutylene), is obtained as a minor component.

In general, the method described is used together with the device for Production of polymers used at low temperature, which are permanently in solution be kept to contamination of the reaction vessel as well as cold losses and to avoid the resulting higher costs for energy and materials.

Thus, according to the method according to the invention, unsaturated compounds are obtained at low temperature by means of a Friedel-Crafts catalyst using a solvent for the unsaturated compounds and for the finished polymer copolymerized, with the cold content of the cold polymer solution for cooling made use of the monomer and solvent feed and the heat of reaction by direct cooling in a circulation system for the polymer solution absorbed will. The solvent is used in such amounts during the polymerization applied that the solution is kept flowable at the low temperature. The solution is heated to reduce its viscosity. This is the solvent at a higher temperature, namely above the polymerization temperature, for the most part evaporated and a reflux product obtained immediately with the exclusion of water. The concentrated polymer solution is kept flowable by means of a higher temperature. Then the remaining volatile constituents are expelled with steam, and the dissolved polymer is slurried in solid form in water for the purpose of recovery. The remaining unsaturated compounds are caused by condensation, settling and mechanical separation dehydrated; the drying is done by fractional distillation finished, and the various constituents of the volatile evaporated by steam Materials are fractionated for recirculation and mixing with the feed separated.

Only a few embodiments of the method have been described Device according to the invention. However, other embodiments can also be used without departing from the scope of the invention. '

Claims (3)

PATENT CLAIMS: i. Process for the preparation of copolymerization products, characterized in that a cold mixture of unsaturated organic compounds and a solvent for this and the polymer is circulated, a polymerization catalyst is added during the circulation, and a continuous stream of polymer solution is drawn off from the circulation system, the viscosity of which is in the range the flowability is, the withdrawn polymer solution is replaced by a constant stream of a cold mixture of unsaturated compounds and solvent and the stream of fresh feed is replaced by the withdrawing stream of the polymer solution in the. Countercurrent cools. 2. The method according to claim i, characterized in that the circulating solution of the monomers is absorbed by the polymer solution which is drawn off Polymerization temperature cools and this brings the polymer stream approximately to the The incoming feed temperature is heated, followed by the bulk of the diluent and the unpolymerized unsaturated substances from the warm polymer solution evaporates, their viscosity under the simultaneous action of residual solvent and higher temperature kept within the range of flowability. 3. Procedure according to claims i and 2, characterized in that the warm flowable Polymer solution converted into warm water by means of steam to remove the remaining Remove solvents and unsaturated substances and the solid polymer muddy in water. 4. The method according to claims i and 2, characterized in that the warm, flowable polymer solution by means of dispersing water vapor is transferred to hot water to remove residual solvent and to remove unsaturated substances and to suspend the solid polymer in water. 5. Process according to claims i to 4, characterized in that the solid Polymer is filtered off from the '' water and dries and the evaporated substances fractionated to obtain a return to mix with the feed separates. 6. Process according to claims i and 2, characterized in that one the cooled mixture of unsaturated compounds, solvent and catalyst circulated through a cooling zone for the purpose of cooling and the feed in one of the first cooling zone corresponding cooling zone subjected to final cooling and the two The cooling zone switches over when the zone in which the polymer has been deposited has been cleaned shall be. Method according to claims i and 2, characterized in that the catalyst at -1o3 to -35 ° of the mixture of unsaturated compounds and Solvent is added during circulation. B. Method according to the claims i and 2, characterized in that the polymerization temperature by cooling with liquid ethylene, liquid ethane, liquid carbon dioxide or liquid propane is set. G. Method according to claims i and 2, characterized in that that the cold mixture of unsaturated compounds and solvent at -1o3 can rotate down to -35 °. ok Process according to claims i to g, characterized in that that the warm flowable polymer solution with dispersing water vapor and Hot water currents converted into hot water. ii. Device for executing the Process according to claims i to io, characterized by a polymerization system from a reaction receiver, a circulation pump and a cooling device, by means for introducing a stream of polymerizable unsaturated substances in one Solvent in the polymerization system, through means of draining a flowable Polymer solution from this system and through heat exchangers to cool the incoming Charging by the withdrawing stream of the polymer solution and to the simultaneous Heating the stream of polymer solution with the sensible heat of the feed stream. 12. The device according to claim ii, characterized by an evaporator which consists of a cooker template and a heating device for evaporating the majority of the Solvent and the unpolymerized substances from the warm polymer stream consists, so much solvent remains in the polymer solution that their Viscosity is kept in the range of flowability. 13. Device according to claims i i and 12, characterized by a separator with a warm slurry of the polymer in water, which with a polymer nozzle and a steam nozzle for simultaneous introduction of a stream of polymer and a stream of dispersing Steam is fitted into the warm slurry. around the polymer solution in transferring a slurry of solid polymer in water. 14. Device according to claims io to 13, characterized in that the separator also with a water nozzle for introducing water into the warm slurry at the same time Is provided.