DE2049563C2 - Process for the polymerization of vinyl chloride - Google Patents

Description

30th

35

20th

From the laid out documents of Belgian patent 6 86 068 is a process for polymerisation of vinyl chloride in the presence of a layer of polyvinyl chloride granules and a free radical known forming catalyst, worked in the absence of a liquid phase and the monomeric Vinyl chloride was released into the Roakticnbzone exclusively in the gaseous state.

DE-PS 9 75 823 discloses a process for the polymerization of vinyl chloride in the presence of Polyvinyl chloride powder and known from benzoyl peroxide, in which the vinyl chloride in the liquid state in was mixed with the polyvinyl chloride powder in a closed vessel with the aid of an intensive stirrer.

The invention relates to the subject matter characterized by the claim.

Since in the laid out documents of the Belgian patent 6 86 068 particular emphasis was placed on that no liquid phase was present could not be expected, if one according to the invention introduces the vinyl chloride partly in liquid and partly in gaseous state into the reaction zone, particularly favorable results can be achieved. The presence and maintenance of liquid Monomers in the reaction zone containing a fluidized bed is essential for the process according to the invention necessary because in this way the temperature of the fluidized bed is controlled and kept constant and the concentration of the monomeric vinyl chloride on and / or in the polyvinyl chloride granules is constant is held.

The process of DE-PS 9 75 823, in which only stirred and worked without a fluidized bed, had the disadvantage that polymer deposits were formed on the inner wall of the vessel. In one Comparative experiment, in which example 2 of DE-PS 9 75 823 was reworked, had proved itself after 20 Polymerizations in a vessel with a capacity of 4 l on the inner wall 55 g of polymer deposits formed, while after 30 polymerizations according to Example 1 below, no polymer deposits were observed on the inner wall of the reactor.

The starting material for the process according to the invention consists of granules of polyvinyl chloride, which is suitable as a polymerization carrier for the monomeric vinyl chloride and such a size and Has shape that it is for use in a

45

50

55

60

65

Fluidized bed is suitable.

The polymer granules are by means of a stream of gaseous vinyl chloride, optionally through a Inert gas, diluted, kept in a vortex.

If the pressure of the vinyl chloride in the system is less than the vapor tension of the vinyl chloride at the selected polymerization temperature, a polymer is obtained whose particle porosity is much less reduced compared to the starting polymer than in the case of application of a pressure which is equal to the vapor tension of the vinyl chloride is. It is known that porosity is an extremely important characteristic of a polyvinyl chloride resin because it is related to the capacity of the resin to adsorb particular additives during later conversion phases while maintaining the state of a dry powder. The porosity of a resin can be expressed in cm ³ voids / g resin or by the PAR value (plasticizer adsorption rate), which is a measure of the time it takes for the resin to adsorb the plasticizer; this value increases with decreasing porosity of the resin. In general, the polymerization of vinyl chloride in a fluidized bed on a base material made from commercially available polyvinyl chloride leads not only to an increase in weight compared to the initial weight, but also to a decrease in porosity and thus to an increase in the PAR value. If one works according to the present invention at pressures which are below the saturation voltage of the monomeric vinyl chloride at the selected temperature, then the increase in the PAR value is relatively small.

Table II shows the PAR values in minutes, calculated according to that described in Example 3 Determination method specified for polyvinyl chloride resins (PVC) by polymerization in a fluidized bed of preformed polymer granules, either at pressures equal to or equal to Vapor tension of the vinyl chloride monomer at the chosen reaction temperature, or at lower Pressures when this vapor tension was operated according to the invention.

From the results, it can be seen that for a certain percentage increase in the weight of the polyvinyl chloride resin a considerably smaller increase with respect to the original base material the PAR value occurs when the polyvinyl chloride according to the invention at lower pressures than Vapor tension of the vinyl chloride at the selected temperature was obtained than when at pressures was worked, which were equal to this steam tension.

Because the PAR value of the resin must not exceed certain limits when it is later used should not be endangered, it is easy to see the great advantages of the present invention can be achieved because polyvinyl chloride resins are obtained with superior technological properties can be.

Another and particularly advantageous working condition of the method according to the invention exists in that liquid vinyl chloride is also introduced into the fluidized bed in addition to gaseous vinyl chloride. This measure allows the temperature and the concentration to be effectively controlled in a simple manner of the monomer in the system so as to avoid the drawbacks based on unevenness the temperature and the monomer concentration

tion with reference to the kinetics of polymerization and the technological properties of the product based, and z. B. in a changeable behavior compared to that in later processing stages added additives, a change in the molecular weight, etc.

In fact, liquid vinyl chloride can also be added to the fluidized bed in addition to gaseous vinyl chloride is introduced, the heat of polymerization of vinyl chloride is eliminated in a satisfactory manner so that overheating of the polymer particles and degradation of the polymer itself are avoided.

The problem of the fluidized bed in a uniform. · And continuous manner with the monomers too supply that from the granules not only as a result of polymerization but also as a result of evaporation disappears, and at the same time to control the temperature at every point of the fluidized bed, is according to the invention solved by introducing two different streams of vinyl chloride into the reactor once in the form of a gas through the bottom of the reactor to stir up the layer, and on the other hand through one or more appropriately arranged nozzles in the form of a nebulized liquid, which has the task of regulating the temperature and the monomer / polymer composition of the growing Control grains. The polymerization of the vinyl chloride on the individual granules causes one local temperature increase and thus the evaporation of part of the adsorbed monomer. Everything this leads to an increase in pressure in the fluidized bed, and this pressure is reduced by that some of the gaseous monomer is vented from the reactor until the original pressure is down has set again.

The amount of liquid monomer to be introduced into the fluidized bed is such that the Temperature and the monomer / polymer ratio on the granules kept constant in the reactor will.

Another advantage that is achieved in that according to the invention in the fluidized bed and gaseous monomer is introduced, is that together with the stream of liquid monomer new particles of preformed polymers can be easily introduced into the fluidized bed.

Since the polymerization on a preformed base material leads to a growth in the particle size of the Polymers with increasing weight conditional, it is, if you want to work continuously, necessary in introduce new particles of preformed polymer into the reactor. Otherwise the polymerization would have to take place be interrupted as soon as the polymer granules in the reactor have reached a size in In view of the later use of the polymer must not be exceeded.

The invention of a portion of the monomer in the liquid state according to the invention opens one up simple way on which at the same time with this liquid monomer also particles from preformed Polymers can be introduced into the reactor, which are the basic material for the subsequent polymerization so that the process can be easily converted into a continuous one.

The polymerization temperature depends on the decomposition kinetics of the initiator used; if one uses one of the usual initiators, then one works in the range between 0 and 100 ⁰ C, but preferably between 20 and 75 ° C.

In order to carry out the process according to the invention it is necessary that in the polymer granules In addition to the adsorbed monomers, the polymerization initiator is contained

Such an initiator is of the free radical generating type and may be a peroxide, an azo compound, etc. be. It is obtained in amounts between 0.01 and 2% by weight, preferably between 0.05 and 0.5% by weight

ίο to that which forms the original fluidized bed Polymers, used

The initiator can be added to the particles forming the fluidized bed by various methods will; however, these methods are not a critical factor in the present invention.

For example, the granules of the starting polymer or they are mixed with the initiator in the solid state before they are introduced into the fluidized bed can with the one in vinyl chloride or another

J "Solvent dissolved initiator are treated, this solvent is completely removed before the polymer is introduced into the fluidized bed will.

On the other hand, it is also possible to use those in vinyl chloride monomers dissolved initiator directly into the fluidized bed in the reactor before or during the Introduce polymerization.

If the method according to the invention is used, it is possible. Polymers with a similar one Gain molecular weight as in normal industrial PVC manufacturing processes.

Any desired regulation of the molecular weight can be carried out in a known manner by the polymerization temperature is increased or small amounts of substances are introduced that act as Chain transfer agents act. For this purpose, the chain transfer agents customary in vinyl polymerization, such as B. trichlorethylene, 1,2-dichloroethylene etc. can be used.

The chain transfer agent, when dissolved in vinyl chloride, can go directly into the fluidized bed or introduced during the polymerization, or it may be mixed with the polymer granules which form the original fluidized bed.

However, the addition can take place in any other way.

For the implementation of the method according to the invention, a conventional installation, such as that used for Fluidized bed reactions is used, can be used. Such plants are, compared with those for the Bulk polymerization of vinyl chloride used equipment, very simple and cheap.

In the presence of a solid polymer, mixing devices are generally used for powdery Materials are required that are technically difficult to handle and a great economic burden represent. The method of the invention and the equipment used therein also offer the following advantages: easy thermal control of the polymerization; Obtaining the polymer in the form of particles with a uniform grain size distribution, as will be explained in more detail below; Lack of Deposits on the inner walls of the reactor, and high degree of purity of the polymer formed because of the lack of dispersants, diluents, etc. in the polymerization process, and because of the limited amount of catalyst required. The method of the present invention shows the following

Characteristics:

a) The polyvinyl chloride granules can absorb significant amounts of vinyl monomers and while maintaining the characteristics of a dry powder, which is why they use a carrier gas can be whirled up.

b) The vinyl chloride which is present on the polymer grains containing small amounts of a polymerization initiator is absorbed, polymerizes easily and in good yield when it is on a suitable Temperature is

c) The polymer granules acting as polymer carriers take on a regular basis during the increase in weight and size of the polymerization. Therefore it is possible to adjust the grain size of the enc product either by selecting the grain size of the starting polymer or by Control the weight gain of the granules themselves during the polymerization process too rules. This increase can dui: h Varying the duration of the procedure with reference to the chosen Conditions are controlled.

d) The polymer obtained has a porosity which is a relatively small amount below that of the Starting polymer lies.

e) The control of the temperature and the monomer concentration during the polymerization can be carried out easily and allows it. a polymer with particularly advantageous technological Properties to gain.

f) The process can easily be carried out continuously.

example 1

A polymerization test is carried out in a fluidized bed, with a starting polymer Commercial type PVC obtained by bulk polymerization is used.

In a cylindrical 6 liter glass autoclave that comes with equipped with a discharge device on the bottom and a propeller stirrer dragging against the reactor walls 420 g of PVC are introduced.

The air is removed by repeated purging by reducing the pressure and then applying nitrogen is introduced.

A solution is then introduced which consists of 2.2 g of lauryl peroxide (LPO) as initiator in 1500 g of vinyl chloride (VC). The mixture is kept at 20-25 ⁰ C in motion, and the majority of vinyl chloride is removed by evaporation, until the pressure of the reaction system is 1 ata. In this way a powder is obtained which consists of PVC, LPO (0.50% by weight, based on the polymer) and a small amount of remaining VC. This powder is discharged through the valve into the bottom section of the fluidized bed reactor, in which vinyl chloride is already in a gaseous state.

The fluidized bed reactor consists of a vertical cylindrical tube with an inner diameter of 80 mm, which is provided with a flow jacket for regulating the temperature. The bottom of the The reactor consists of a porous part made of stainless steel for the distribution of the fluidizing gas (VC).

The upper part of the reactor is formed by a tube that has a diameter of 160 mm is broadened so that the flow velocity is reduced and the separation of the gas flow entrained fine particles is made possible. There is a vibrating filter cloth at the exit of the reactor used, which prevents the powder from leaving the reactor. The Wirbelgao is made by means of a Diaphragm compressor returned to the reactor.

All pipes through which the VC flows outside the fluidized bed are heated to temperatures which are equal to or higher than that of the reactor. The converted monomer is then, either as a gas

ίο or as a nebulized liquid directly into the fluidized bed introduced

The polymerization in the fluidized bed is carried out at 60 ° C., the monomer pressure being constant is held at a value between 7.6 and 8 ata. After 6 hours the vinyl chloride is removed first by displacement with nitrogen and then by evacuating the apparatus.

1150 g of polymer are withdrawn from the reactor, which corresponds to a weight increase of 174% with reference on the starting polymer corresponds to The intrinsic viscosity is in cyclohexanone solution at a concentration of 0.1 wt .-% measured at 25 ° C, and the grain size distribution is according to ASTM D. 1921-63 / A certainly.

The intrinsic viscosity of the starting polymer is 0.96 dl / g; that of the discharged polymer 0.95 dl / g. The apparent density of the polymer, measured according to ASTM D. 1895-67 / A. is 0.49 g / cm ^J for the starting polymer and for the discharged polymer

jo polymers 0.57 g / cm ³ . The particle size distribution of the product can be seen from Table I.

Example 2

A polymerization test is carried out according to the procedure of Example 1, but with a lower concentration carried out on initiator.

600 g of the polymer used in Example 1 are mixed with a solution of 1.2 g of LPO in 1200 g of VC (LPO = 0.20 wt% of the resin) and then the VC is evaporated. The powder obtained is in the Fluidized bed introduced. The polymerization is carried out for 6 hours at 57 ° C., a pressure of 8 sustained until 8.2 ata.

1050 g of polymer are discharged, corresponding to a weight increase of 92%, based on the starting polymer. The product is subjected to all the determinations as in Example 1, the the following results can be obtained:

Reduced specific viscosity (RSV), measured in terms of cyclohexanone at 25 ° C. and 0.1% by weight polymer concentration: 1.07 dl / g; apparent density: 0.48 g / cm ³ . The particle size distribution can be seen from Table I.

Example 3

A polymerization test is carried out in a fluidized bed according to the method of Example 1, wherein however, the mixing of the initiator with the starting polymer is varied.

2 g of finely powdered LPO are mixed with 20 g of polymer so that the initiator is well distributed in the the polymer is achieved. This mixture is then added to 380 g of the same polymer and in the fluidized bed introduced. The concentration of the initiator is 0.5% by weight of the polymer.

After that, by repeatedly purging with nitrogen and then with gaseous vinyl chloride, the oxygen Having been removed from the reactor, the mixture is kept at 57 ° C for 7 hours and 40 minutes

Example 4

In the apparatus described in Example 1 is a Test carried out using a different starting polymer. To this end 250 g of low molecular weight polyvinyl chloride produced by suspension polymerization (K value 57 to 60) mixed with a solution of 1.25 g of LPO in 800 g of VC (0.5% by weight of the polymer). The VC is evaporated and the powder obtained is introduced into the fluidized bed reactor.

Then the mass is 12h. polymerized at 58 ° C under a pressure of 8.4 ata. 1300 g Polymer obtained, corresponding to an increase in initial weight of 420%. Starting product and End products have the following characteristics:

PVC

End product

Reduced specific 0.60 0.98 viscosity

Apparent density 0.50 0.54 Grain size distribution:

over 0.250 mm - 37.3%

over 0.175 mm - 52.3%

over 0.150 mm - 7%

over 0.125 mm - 2.5%

over 0.110 mm 12.3% 0.7%

over 0.090 mm 51.2% 0.2%

over 0.075 mm 17.0%

below 0.075 mm 19.5%

Example 5

The polymerization experiment of Example 3 is repeated, using a different starting polymer is used. 1 g of finely powdered LPO is carefully mixed with 20 g of one by emulsion polymerization produced low molecular weight polyvinyl chloride (K value 57 to 60) mixed, and that The mixture is then further blended with 280 g of the same polymer 0.33% LPO introduced into the fluidized bed; on this it is polymerized for 8 hours and 45 minutes at 58 ° C. and a pressure of 8 to 8.2 ata

polymerized, with a VC pressure of 7.2 to 7.8 ata is maintained.

1420 g of polymer are discharged, corresponding to a 250% increase on the initial weight. The product discharged has an RSV value of 0.98 dl / g.

After the end of the experiment, the PAR values are determined on this polymer. The PAR value becomes measured by adding the corresponding amount of resin to a certain amount kept at 100 ° C Plasticizer (50 g of 2-ethylene hexyl phthalate for 100 g PVC) and the time measured between the addition of the plasticizer and the final dry point of the plasticized polymer passes. The PAR value for the starting polymer is about 1 Minute 30 seconds, that for the discharged polymer about 9 minutes.

620 g of product are obtained, corresponding to an increase in the initial weight of 107%.

Example 6

The polymerization experiment described in Example 1 is repeated, but with a different one Starting polymer is used. 220 g polyvinyl chloride (suspension PVC with a low Molecular weight, K value 57 to 60, sieved to less than 0.125 mm) with a solution of 1.1 g LPO in 660 g VC treated in an autoclave at 25 ° C.

Then the VC is evaporated with stirring. The powder obtained contains 0.5% by weight of initiator, based on on the polymer, and is introduced into the fluidized bed. Then 7 hours at 57 ° C under a Polymerized at a pressure of 8.4 ata. 550 g of polymer are discharged, corresponding to an increase in weight of 110% on the starting polymer.

The end product and the starting product have the following characteristics:

PVC

«0.125 mm)

End product

Reduced specific
viscosity
Apparent density

over 0.250mm
0.175 mm
0.150 mm
0.125 mm
0.110 mm
0.090 mm

above
above
above
above
above
above

0.075 mm

below 0.075 mm

1.08 dL / g
0.45 g / cm ³

5.8%
50.7%
27%
18.5%

1.13 dl / g

0.45 g / cm ³

0.4%
16%
31.8%
38.5%

8.6%

3.9%

0.6%

0.2%

Example 7

The polymerization experiment described in Example 1 is repeated with a different starting polymer. In an autoclave, 470 g of a polyvinyl chloride produced in bulk are ^{mixed at 25 °} C. with a solution of 2.35 g of LPO in 1100 g of VC. The VC is then evaporated with constant stirring. The powder obtained, which contains 0.5% by weight of LPO, is introduced into the fluidized bed reactor and polymerized there for 7 hours at 57-58 ° C. under a pressure of 6.4-6.8 ata. At the end of the polymerization, 1030 g Polymer discharged, corresponding to an increase in the weight of the starting polymer of 120%. The starting and the end product have the following characteristics:

Starting product

End product

Intrinsic viscosity
Apparent density

Reduced specific
viscosity

0.71 dl / g
0.57 g / cm ³
0.74 dl / g

0.88 dl / g
0.59 g / cm ³ 0.93 dL / g

Initial product

End product

PVC
«0.125 mm)

End product

Grain size distribution:
over 0.250mm
0.175 mm
0.150 mm
0.125 mm
0.110 mm

above
above
above
above
above
above

0.090 mm
0.075 mm

below 0.075 mm

1 %

5.4%

66.5%

23.7%

2.5%

4.8%
30.3%
50.8%
13.0%

1.4%

Example 8

This experiment is carried out according to the method of Example 1, using as the starting polymer a product obtained in a previous fluidized bed polymerization is used.

In an autoclave, 470 g of the polymer obtained in Example 7 are mixed at 25 ° C. with a solution of 2.35 g of LPO in 1200 g of VC. The VC is evaporated with stirring to give a powder containing 0.5% by weight of LPO. After the powder has been introduced into the fluidized bed, it is polymerized for 10 hours and 45 minutes at 56-57 ° C. and a pressure of 7.4 to 7.8 ata. At the end of the polymerization, 1900 g of polymer are discharged, corresponding to a 305% by weight increase. The characteristics of the starting polymer are given in Example 7. The discharged product has an apparent density of 0.62 g / cm ³ and its RSV value is 1.07 dl / g.

Grain size distribution: 0.350 mm example _ above 0.250 mm 76.5% above 0.175 mm 18.5% above 0.150 mm _ above 0.125 mm 5% above 0.110 mm - above 9

The polymerization experiment of Example 3 is repeated with a different starting polymer 1.5 grams of finely powdered LPO is carefully mixed with 20 grams of a low molecular weight suspension PVC (K value 57 to 60, sieved to less than 0.125 mm) 280 g of the same are mixed with this mixture Added to polymers so that a powder is obtained which contains 0.5% by weight of initiator, based on the polymer, contains

After 5 hours of polymerization at 8.2 ata and 58 ° C 1000 g of polymer are discharged (yield: 235%).

PVC

«0.125 mm)

End product

Reduced specific
viscosity

Apparent density

0.74 dl / g
0.70 dl / g

0.95 dl / g
0.92 dl / g

Grain size distribution:

over 0.250mm
over 0.175mm
over 0.150mm
0.125 mm
0.110 mm
0.090 mm
0.075 mm

above
above
above

Ll D Cs Γ \ J ^ \ JI + S I Ulli

below 0.075 mm

16.5%

56.2%

18.3%

9.0%

0.7 "/.

2.4%

36.4%

41.6%

12.2%

5.3%

1.1%

0.3%

Example! 10

The polymerization experiment of Example 8 is repeated, the product obtained in Example 9 as Starting polymer is used. 1.5 g of LPO are carefully mixed with 20 g of polymer, and with this another 280 g of the same polymer are mixed. The powder obtained is in the fluidized bed reactor transferred and polymerized for 7 hours at 58 ° C under a pressure of 8.4 ata. After finished Polymerization are discharged from the reactor 1365 g of product (weight increase on the starting polymer: 355%), which has the following properties:

Reduced spec. viscosity
Apparent density
Grain size distribution:
over 0.250mm
over 0.175mm
over 0.150mm
over 0.125mm
less than 0.125 mm

1.05 dL / g
0.49 g / cm ³

20.9%
74.4%

4.3%

0.4%

0.44 g / cm ³ 0.46 g / cm ³

Example 11

The polymerization experiment of Example 3 is repeated, but using a different starting polymer and a lower concentration of initiator can be used. For this purpose 0.4 g of LPO initiator are used with 20 g polymer (suspension PVC with low molecular weight K value 57 to 60 and grain sizes below 0.135 mm) mixed. A further 230 g of the same polymer are added to the mixture. the Concentration of the initiator with respect to the powder is 0.16% by weight.

This mixture is then in a fluidized bed reactor for 16 hours at 57 ° C and a pressure of 8.2 aia polymerized, 520 g of product being obtained. The properties of the discharged polymer are like follows:

Reduced spec. Viscosity 0.90 dl / g

Apparent density 0.45 g / cm ³

Grain size distribution:

over 0.250 mm 2.5%

over 0.175 mm 9%

over 0.150 mm 22.8%

over 0.125 mm 36.9%

over 0.110 mm 8.8%

over 0.090 mm 7.9%

over 0.075mm. 1.9%

below 0.075 mm 0.2%

Example 12

Example 3 is repeated, but the polymerization in the presence of a chain transfer agent is carried out. A mixture of 300 g of polymer and 1.5 g of LPO initiator (0.5% by weight) is used prepared. The powder is then introduced into the reactor and stored at 58 ° C and a pressure of 8.2 ata in Vortex offset. A solution of 11 g of trichlorethylene is then finely atomized in the fluidized bed Liquid introduced into 50 g of vinyl chloride. While temperature and pressure at the specified values are held, the mixture is polymerized for 6 hours, whereby 680 g of product are obtained; Yield: 125% of the starting product. The product has a reduced specific viscosity of 0.75 dl / g and a PAR value of about 6 minutes.

Example 13

The experiment of Example 9 is repeated, the polymerization in the presence of a chain transfer agent is carried out. For this purpose, a mixture of 300 g of the suspension PVC (K value 57 to 60 and grain sizes below 0.125 mm) and 1 g of LPO (0.33% by weight). The powder is in the Introduced fluidized bed reactor and at 58 ° C and a pressure of 8.2 ata in fluidization. Thereon becomes a solution of 50 g of VC and 11 g of trichlorethylene introduced into the fluidized bed in the form of a finely atomized liquid. While the fluidized bed is kept under the specified conditions, it is polymerized for 7 hours, with 600 g of product can be obtained (bulge 130%). The characteristics of the product are:

Intrinsic viscosity
Apparent density
Grain size distribution:
over 0.250mm
over 0.175mm
over 0.150mm
over 0.125mm
over 0.110mm
over 0.090mm
over 0.075mm
below 0.075 mm

0.67 dl / g
0.50 g / cm ³

• 1.8%
15.0%
20.0%
32.4%
18.1%

8.0%

2.6%

2.10 / q

Example 14

The attempt by example! 1 is repeated, where however, a different initiator is used.

In an autoclave, 600 g of polymer are mixed with a solution of 0.5 g of initiator (diisopropyl peroxycarbonate) mixed in 1000 g of VC. The VC is evaporated with stirring and the powder obtained is poured into the Fluidized bed introduced The mass is 11 hours at 57 ° C polymerized under a pressure of 8.2 ata, 900 g of product are obtained, what a Weight increase of 50% corresponds to the product has the following properties:

Reduced specific
viscosity
Apparent density
Grain size distribution

1.1 dl / g
0.5 g / cm ³
see table I.

Example 15

The experiment described in Example 14 is repeated, but at a different temperature and a different initiator concentration is used. 290 g of polymer are added to an autoclave a solution of 0.88 g of diisopropyl peroxycarbonate mixed in 1000 g of VC. After evaporation of the VC becomes the powder obtained in the fluidized bed reactor

ίο introduced. The polymerization is carried out for 5 hrs. At 5O ⁰ C under a pressure of 7 ata, in which 840 g of product are obtained, corresponding to a weight increase of 190% on the originally used polymer.

Example 16

The experiment of Example 13 is repeated using a different catalyst. For this purpose, 400 g of commercial PVC are mixed with a solution of 12 g of di ^ -tert.-butylcyclohexyO-peroxycarbonate and 15 g of trichlorethylene in 1000 g of VC in an autoclave at 25 ° C. The VC is evaporated with stirring, and the powder thus contains 3.7% trichlorethylene and 0.3% catalyst. The polymerization is carried out in a fluidized bed for 22 hours at 50 ^° C. and a pressure of 6.8 ata. 1600 g of product with the following properties are discharged:

Reduced specific
viscosity

Apparent density
Grain size distribution

1.01 dL / g
0.62 g / cm ³
see table 1

Example 17

The experiment of Example 1 is repeated, the conditions under which the initiator with the Polymers is mixed, can be varied. For this purpose, 800 g of polymer are placed in an autoclave 25 ° C mixed with a solution of 2.4 g LPO in 100 g VC. The mixture is obtained as a powder and can easily in. without prior evaporation of the monomer

so be transferred to the fluidized bed reactor. Thereafter, β hours at 57 ° C and a pressure between 7.3 and 7.6 ata polymerized At the end of the polymerization, advertise from uein i \ .eaiCtGr ι / w g ι rouUKt ^ ΛΐΓΐαιιΐΐΐο from 115% with reference to the starting polymer) with the following properties.

Reduced specific

viscosity

PAR value
Apparent density

Grain size distribution:
over 0.250mm
over 0.175mm
over 0.150mm
over 0.125mm
over 0.110mm
over 0.090mm
below 0.090 mm

1.05 dL / g
5 minutes
0.51 g / cm ³

0.6%
13.8%
51.8%
31.5%

2.1%

0.2%

Example 18

The experiment of Example 1 is repeated using a polymer that was immediately prior to the Fluidized bed polymerization had been prepared by bulk polymerization.

In a stainless steel autoclave with a capacity of approx. ^- g VC polymerized in the presence of 4 g octanoyl peroxide for 2 hours at 55 ° C.

The mixture of polymers and monomers obtained in this way is in a glass autoclave similar to that in Example 1 described transferred. The monomer is evaporated ν until a dry powder is obtained.

The polymerization of 4 kg of VC is repeated in the first autoclave under the same conditions; the polymer / monomer mixture is transferred to the glass autoclave, where the previous polymerisation obtained polymer is located, and the monomer is evaporated until a dry powder is obtained.

The polymerization and evaporation are repeated two more times. The polymer thus obtained is partially (350 g) transferred to the fluidized bed, while the rest for the usual Analysis is used.

The polymerization in the fluidized bed is carried out for 5 hrs. At 57 -59 ⁰ C under a pressure of 6.9 ata, with 1900 g of product are obtained, corresponding to an increase of 450%. The analyzes on the product introduced into the fluidized bed and on the product obtained at the end give the following values:

specific 0.250 mm Ind product In the IO 0.175 mm from the fluidized bed density 0.150mm fluidized bed cingcführles Grain size distribution: 0.125 mm polymer ,. Reduced • χι about 0.110 mm 1.01 dL / g 0.93 dl / g viscosity above 0.090 mm Apparent above 0.090 mm 0.51 g / cm ³ 0.37 g / cm ³ above above 22.6% 13.5% ,- above 24.8% 17.0% under 16.9% 10.5% 12.7% 8th % 13.4% 11% 6.6 "/, 18.5% 3.07, 21.5%

Example 19

A series of polymerisation experiments in a fluidized bed is carried out to reduce the influence of the working pressure, i. H. the monomer / polymer ratio on the porosity properties of the polymer, taking into account the weight gain of the latter to investigate. These porosity properties are determined by the adsorption of the plasticizer measured by the polymer under standard conditions as described in Example 3. as The starting polymer is a commercially available PVC obtained by bulk polymerization with a PAR value of approx. 1 min. 30 sec. Used. At the beginning of the experiment, the initiator is in liquid Vinyl chloride dissolved. This solution is applied to the

jT fluidized bed given, with a homogeneous distribution is achieved on the granules. The experiments are carried out in a reactor with a diameter of 100 mm carried out; During the polymerization, the monomeric vinyl chloride enters the reactor partly as a gas and partly introduced as a nebulized liquid

Table II gives the PAR values and the operating conditions for the comparative tests A and B, for the tests according to the invention C, D, E, F and G as well as for Examples 3, 12 and 17 again.

Table I.

Proportions in% by weight

proportion of
under:

average
under:

(Micron)

Starting polymer product

Example examples example example

16 i, 2, 14 i 2

example

example
16

0.295 297 _ _ _ 0.2 0.3 2.6 0.250 250 - - - 0.8 0.6 2 0.200 210 1 0.2 41.2 5 0.5 90.7 0.175 177 5.4 1.7 40.2 34.3 2.5 4.6 0.150 144 66.5 51.5 14.8 52 ^ 5 25th - 0.125 125 23.7 36.8 1.8 .6.0 57 - 0.110 105 2.5 8.6 2 1 13th - 0.090 88 0.9 2 ■ - 0.1 1.4 - 0.075 74 - - - - 0.2 -

15th

16

Tabel II Working
pressure
ata relationship
Working
pressure!
supply pressure Polymeri
sation time
(H) A
guided
lot
PVC
kg initiator
Type G Received
lot
PVC
kg product
increase
Wt .-% of
Initial
Polymers PAR-Werl
(Minutes) attempt
bziv.
example Tempe
rature
⁰ C 8.8 = 1 4th 3 Octanoyl
peroxide 3.5 1.95 65 4th A *) 55 8.8 - 1 10 3 the same 3.5 3.15 105 15th B *) 55 8.4 0.95 10 -, desgL 3.5 3 100 4.5 C. 55 8.4 0.95 6.5 3.5 DIPC **) 2 3 100 4.5 D. 55 8.4 0.95 6th 2.7 DIPC **) 3 5.15 190 7th E. 55 8.4 0.95 13th 2.3 DIPC **) 2.5 5.1 220 10.5 F. 55 8.4 0.95 8th 4th DIPC **) 2.5 7.5 300 15th G 55 7.5 0.80 7.66 0.4 LPO 2 1.02 250 9 3 57 8.2 0.85 6th 0.30 LPO 1.5 0.38 125 6th ! 2 58 7.5 0.78 6th 0.8 LPO 2.4 0.90 115 5 17th 57

*) Comparison test.
**) Diisopropyl peroxycarbonate.

Claims (1)

Claim: Process for the polymerization of vinyl chloride in the presence of a layer of polyvinyl chloride granules and a free radical initiator in an amount between 0.01 and 2% by weight, based on the originally present polymer, at pressures below the saturation vapor pressure of the Vinyl chloride at the selected polymerization temperature, characterized in that the vinyl chloride is partly in the liquid state and partly in the gaseous state in the Introduces reaction zone and the layer of polyvinyl chloride granules through the flow of the gaseous Keeps vinyl chloride in a vortex.