DE2151138A1 - PROCESS FOR CHLORINATION OF POLYMERIZATES OR COPOLYMERIZED BY ALPHA-OLEFINS - Google Patents

Description

(Addition to P 20 62 123)

Patent application P 20 62 123 describes a process for the post-chlorination of pulverulent polymers or copolymers of vinyl chloride by reacting the polymer powder in a fluidized bed or in a fluidized bed with gaseous Chlorine described at temperatures between about 30 and 110 C, its characteristic is that one has to discharge the share the amount of heat released during the reaction that is not required to maintain the respective reaction temperature becomes, a liquid inert to chlorine, evaporating in the range between -50 and + 80 C, but in particular Introduces liquid chlorine itself, continuously or discontinuously, into the reaction chamber and measures its amount in such a way that that in every unit of time negative heat of evaporation and excess heat of reaction balance each other out.

It has now been shown that you can work with this special Success also in the chlorination of polymers or copolymers made exclusively of carbon and Hydrogen generated oC-olefins, especially polyethylenes, can apply, whereby the temperatures can be up to 160 ° C.

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ÖAD

Λ fs / I IvIO

HOE 71 / F BIO (Ge. 455)

The present invention therefore relates to the further development of that described in patent application P 20 62 123 Process for the post-chlorination of powdered polymers or copolymers of vinyl chloride by reacting the polymer powder in a fluidized or fluidized bed with gaseous Chlorine at temperatures between about 30 and 16O C, whereby one has to discharge the portion that during the implementation amount of heat released that is not required to maintain the respective reaction temperature, one that is inert towards chlorine, in the range between -50 and + 8OC evaporating liquid, but especially liquid chlorine itself, continuously or discontinuously into the reaction chamber brings in and their amount is measured in such a way that in every unit of time Compensate negative heat of evaporation and excess amount of heat of reaction, which are characterized by this is that instead of the vinyl chloride polymers or copolymers powdery polymers or copolymers of ° k-01efinen built up exclusively from carbon and hydrogen with a crystallite melting point end between and 160 C chlorinated.

It was not foreseeable that the transfer of the method of the main application to those to be used according to the invention Olefin polymers, especially when using liquid chlorine as a heat-dissipating agent, because ^ the prototypes of the two groups of substances, namely polyvinyl chloride and polyethylene behave very differently when chlorinated. For example, it is known that poly, When it comes into contact with liquid chlorine, ethylene powder can react so vigorously that it becomes charred. On the other hand, however, e.g. polyethylene chlorination, if the products for the current main area of application, namely the elasticization of PVC take place at such a high temperature that the crystalline segments in the polymer chain are largely broken down,

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ORIGINAL BATHROOM

⁴ X HOE 71 / F 810 (Ge.

while PVC post-chlorinates at relatively lower temperatures is going to be thermally stable. Products. In the case of polyethylene chlorination, the chlorination temperature should therefore be after reaching a chlorine content of approx. $ 30 at the latest, are raised so far that the last crystallites melt. In the case of low-pressure polyethylene, the upper temperature limit is of the melting range, the It. differential thermal analysis (DTA) is approx. 1 35 ° C, which is decisive for the chlorination process. The need for such temperature control complicates the polyethylene chlorination according to the usual fluidized bed or fluidized bed process, since on the other hand a Exceeding the temperature only slightly because of the increasing softening of the polymer, leading to immediate clumping of the Approaches leads.

In order to be able to adhere to the temperature ranges with the required accuracy from this point of view, it is necessary to an effective cooling of the reaction area with as little inertia as possible to strive for. It is known, for example, to use wall or internal cooling or to increase the inert gas throughput to get to the goal. All of these methods have major drawbacks. By increasing the inert gas throughput, for example, the chlorination rate is increased and the degree of conversion of the chlorine is considerably reduced. The dissipation of heat via the wall or through Internal cooling is very sluggish, internal cooling by means of built-in components also has an undesirable flow resistance result. With the use according to the invention of easily evaporating inert liquids, but in particular However, liquid chlorine as a carrier for the excess amount of heat can all avoid the disadvantages mentioned will.

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HOE 71 / F 810 (Ge. 455)

Powdery low-pressure and high-pressure polyethylenes are preferably suitable as starting materials for the chlorination, furthermore the copolymers of ethylene with C "bis" obtained on the course of the low-pressure or high-pressure synthesis CV-oO-olefins, as well as the mono- and copolymers of C- bis C -'-C-C olefins. A special criterion for suitability is that the end of the crystalline melting point of the polymer in question is between 100 and 160, preferably 130 to 145.degree. Provided Low-pressure polyethylenes are chlorinated, those come with an Eta-red value of 0.5 to 20, in particular 1.0 to 5i in question, the latter range being a molecular weight corresponds to from about 34,000 to 270,000. The individual grain size of the polymers should expediently be in the range between 40 and 500 ^ t. lie.

Among fluids resistant to chlorine, their boiling points but must always be below the chlorination temperature chosen in each case, those are understood that evaporate in the range between about -50 and + 80 ° C, preferably between -35 ° C and + 30 ° C. Examples are Carbon tetrachloride and fluorine derivatives of halomethanes and ethanes. A particularly advantageous and therefore preferred one The mode of operation results from the use of liquid chlorine as a heat-absorbing medium. Through the material identity of chlorinating agents and heat-absorbing agents, not only the possibly undesirable dilution of the ^ Reaction gas avoided, resulting in a slower reaction rate as a consequence, but also simplifies the processing or further use of the resulting exhaust gas mixture. The exhaust gases can then be reused, for example, in such a way that they are used for liquefaction or partial liquefaction of the chlorine is compressed and the resulting condensate is fed back into the chlorination process. In case of use of fluoro-chloro-alkanes as cooling liquids can be these freeze out and / or adsorb in a closed circuit on activated carbon and after desorption and subsequent recondensation insert again.

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S HOE 71 / F 810 (Ge. 455)

The chlorination of the powdery feedstock is carried out in carried out in a known manner in a fluidized bed or at temperatures between 30 and 160 C, the movement of the material can take place by means of the optionally inert gas-containing reaction gas and / or mechanically. The chlorination is also based on a vortex process, as it is, for example, in the German Offenlegungsschriften 1.667-048 and 1.811.059 is feasible. Another possible one Embodiment is mixtures of polyolefin and substances indifferent to chlorine, such as talc, silica gel, To use barium sulfate, among others. It is still possible to suppress the reaction by high-energy radiation, such as UV rays, or by adding substances which produce radicals, such as peroxides and azo compounds, for example benzoyl- to catalyze peroxide or azodiisobutyronitrile. In many cases it is also advisable to remove the bulk material before the start of the Reaction according to the procedure of the German Offenlegungsschrift I.72O.8OO to be thermally pretreated. The use of such Starting materials leads to especially in connection with fluorine-chlorine-hydrocarbons as heat acceptors bright, stable products. The reaction can optionally be carried out in such a way that one with a single gas throughput or works with recirculation of part of the resulting waste gas containing hydrogen chloride. With the latter An embodiment which leads to an increased degree of conversion of the chlorine is usually channeled on the exhaust gas side as much gas mixture as to keep the volume constant within the closed reaction system with inclusion the amount of inert liquid evaporating in each case is just required is. This can be easily accomplished by a pressure-controlled gas withdrawal. In case of Using liquid chlorine as a heat acceptor, the reaction can be started after thermal equilibrium has been reached also continue with liquid chlorine alone.

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(θ HOE ηΛ / F 810 (Ge. 455)

It goes without saying that this is also the case with the present chlorination process possible to dilute the reaction gas with limited amounts of inert gas. In addition to hydrogen chloride, inert gases can be used for example also use nitrogen and carbon dioxide.

The inventive measure of temperature control by evaporation of inert liquids within the reaction space or reaction material takes place in such a way that always only such a large amount of them introduced into the reaction space as is required to set the temperature.

The amount of heat to be dissipated and thus the amount of heat acceptor to be evaporated depends on several im The course of the chlorination depends on changing factors, such as the gas flow rate,. Radiation loss of the the respective chlorination apparatus and the speed of the exothermic chlorination reaction, which in turn are temperature-dependent is. It is therefore advisable to supply the Värmeaeceptor in a temperature-controlled manner.

The addition of the liquid to be evaporated to the reaction mixture is possible in the most varied of ways. You can add them to a single point or to several additional points Inject distributed within the pneumatically or mechanically generated fluidized bed. In the case of chlorination in tower-like For reactors, injection using nozzles distributed over several levels is recommended. In special cases, for example when using the chlorine generation process of the German Offenlegungsschrift 1.667.048, it is advisable to distribute the inert liquid on the surface of the fluidized material. At all Embodiments are both a continuous and a discontinuous addition in the required time intervals. booths possible.

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HOE 71 / F 810 (Ge.

According to the procedure according to the invention, chlorination products can with a chlorine content of up to 70 / ° and one particularly low residual crystallinity can be obtained. the Low residual crystallinity is particularly important when the process products - preferably to 30 to ^ O $ chlorinated polyethylenes - as elasticizers for PVC can be used.

In the following, the claimed mode of operation is shown using a few examples.

example 1

In a chlorination apparatus consisting of a cylindrical glass tube with a diameter of 70 mm vmä. a height of 1100 mm, which tapers conically at the bottom, with a temperature measuring point in the reaction chamber, 500 g of low-pressure polyethylene (Bta-red-Vert 1.1, grain size 125 to 315 // C »heat of fusion according to differential thermal analysis A1.8 cal / g) were introduced. The product was then tempered in accordance with the information in German Offenlegungsschrift I.72O.8OO, namely by heating in a stream of nitrogen over the course of 1 3 / h hours to 122 ° C., holding it for 1.5 hours at this temperature and cooling 25 C. Now the mixture of 1 part by volume of chlorine gas and h parts by volume of hydrogen chloride (approx. 2.3 m / h) introduced at the lowest point of the cone was gassed while swirling, the temperature of originally 25 ° within an hour C rose to 70 ° C. The supply of hydrogen chloride was then

/ 3 / \ turned off and whirled with chlorine gas alone (1.5 m / day). An internal temperature of 90 ° C. had been set after 20 minutes. In order to maintain this temperature, every 15

3 seconds 10 minutes each time about 1cm of liquid chlorine a nozzle located above the gas supply in the product injected, a total of 65 g. The supply of Gas chlorine remained unchanged at 1.5 m / h. When the addition of liquid chlorine was complete, the temperature then rose within

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J HOE 71 / F 810 (Ge. 455)

from 5 minutes to 120 C and was also at this stage Held for 15 minutes by injecting 145 g of liquid

3
chlorine in 1 era portions every 10 seconds. The chlorination was stopped 3 minutes after the supply of liquid chlorine had been switched off at a temperature of 135 ° C. and the chloropolyethylene powder obtained was blown out with nitrogen and blown cold. A white powder with a chlorine content of 34.65 9o was obtained.

Heat of fusion according to DTA (differential thermal analysis) 0.13 cal / g MpA: 127.5 ° C Fpmax: 129 ° C MpE: 132 ° C.

With a chlorination time of 1 hour, 48 minutes the following was consumed:

3
Gaseous chlorine approx. 1.8 ° m Liquid chlorine approx. 210 g.

For comparison, the experiment was modified in such a way that hydrogen chloride was added to the reaction gas as an inert gas or chlorination inhibitor in order to maintain the temperature levels. To get a comparable chlorine content of 34.95 / °, the chlorination of the chlorinating step 2nd had to be extended by 12 minutes so that the Gesamtchlorierzeit was 2 hours.

The product obtained had the following properties: Heat of fusion (DTA) 0.7 cal / g
Mp 127.5 ° C Fpmax 129 ° C MpE 134 ° C

Approx. 2.063 m of chlorine gas and 2.5 πι hydrogen chloride were consumed, Despite long-term thermal stress, the residual crystallinity is higher than in the previous product.

Example 2

In the apparatus described in Example 1, a Niederdruclcpolyäthyleii of Tjred 1.1, grain size 40 to 500 / L · and the heat of fusion 40.0 cal / g under the conditions specified in Example 1 initially tempered, then with a chlorine / hydrogen chloride mixture 1: 4 and finally treated with chlorine alone until the reaction product has a temperature of 102 C had set, which was the case after a chlorination time of 50 minutes. There were then in the course of

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9 HOE 71 / F 810 (Ge. 455)

15 minutes 37O g 1,1,2,2-tetrafluorodichloroethane (bp 3.5 c) injected into the reaction zone such that 1 ml evaporated about every 4 seconds. After finished Addition allowed the temperature to rise to 125 C (4 minutes) whereupon the same amount of chlorofluorocarbon again was metered in over the course of 15 minutes, as a result of which the temperature had to be kept at 125.degree. 3 minutes after finishing When the tetrafluorodichloroethane was added, the temperature in the reaction mixture had risen to 137.9. The chlorination was canceled and the product was blown out with nitrogen and cold.

Total chlorination time 1 hour 23 minutes, chlorine content 38 ^ a, heat of fusion (DTA): Cannot be determined because the product is amorphous. Were consumed: approx. 1.42 m chlorine gas and 74θ g 1,1,2,2-

Tetx ^ af luordichloroethane.

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Claims (2)

HOE 71 / F 810 (Ge. 455) Patent claims: IJ) i). ) Further in formation of the patent application P 2O procedure described for 62. 123 postchlorination of powdered polymers or copolymers of vinyl chloride by reaction of the polymer powder in the fluidised bed with gaseous chlorine at temperatures between about 30 and I60.C to give for discharging the Part of the amount of heat released during the reaction that is not required to maintain the respective reaction temperature, a liquid that is inert to chlorine and evaporates in the range between -50 and +80 C, but in particular liquid chlorine itself, continuously or discontinuously introduces into the reaction chamber and the amount of which is such that the negative heat of evaporation and excess heat of reaction are balanced out in each unit of time, characterized in that instead of the vinyl chloride polymers or copolymers, powdered polymers or copolymers of exclusively carbon and hydrogen are used f built-up oC-olefins with a crystallite melting point between 100 and 160 ° C are chlorinated. 2.) The method according to claim 1, characterized in that low-pressure polyethylene with reduced specific Vi skosities T ^ red from 0.5 to 20 can be chlorinated. 309816/0978