DE936719C - Process for continuous interpolymerization - Google Patents

Description

Process for continuous interpolymerization The invention relates to on a multi-stage process for the production of high molecular weight mixed polymers by polymerization according to Friedel-Crafts at low temperature. Typical for that Process is a product made by copolymerization of equal parts by weight Styrene and isobutylene at a temperature of about -8o to -9o0 in the presence of methyl chloride as a diluent and solvent and of aluminum chloride as Catalyst is produced.

Copolymers of this type, e.g. B. copolymers of isobutylene and styrene, as well as their production processes have already been described, for example the preparation by copolymerization below about 0 ° in the presence of an active Halide polymerization catalyst, preferably in the presence of an inert volatile organic liquid that serves as a solvent and coolant. The reaction temperature can be around -io to -1o30 and below. By changing accordingly the proportions of the reactants in the starting material can be copolymers of any desired property such as hardness, melting point, plasticity, etc.

Other aliphatic olefins can be used in place of isobutylene are, suitably with more than 2 carbon atoms, such as propylene, normal butylenes etc., preferably isoolefins with q. up to 8 carbon atoms, such as isopentene (methyl-2-buten-i) or a pentene obtained by dehydration of secondary amyl alcohol will.

Other polymerizable monoolefins can be used in place of styrene which have a cyclic core. Of such connections are preferably to mention vinyl aromatic compounds, especially hydrocarbons. Examples of such Substances are: a-methylstyrene, p-methylstyrene, a-methylp-methyl-styrene, p-chlorostyrene, dichlorostyrenes, indene, coumarone, a-vinylnaphthalene, Dihydronaphthalene, etc.

The interpolymerization is effected by the fact that one of the two reactants with or without an inert diluent or solvent, such as ethylene, propane, Butane, methyl chloride, refined petroleum fractions, etc., mixes and after cooling to the required low temperature with an active halide catalyst offset, for example boron fluoride, or activated boron fluoride (addition of o, i ° / ° ether), aluminum chloride, titanium tetrachloride, aluminum alkoxide-aluminum chloride complex [AIC13 - Al (OC, H5) 3] and the like. The catalyst can be dissolved in a solvent, z. B. a lower alkyl halide, such as methyl chloride or ethyl chloride, or carbon disulfide, a low molecular weight sulfur-free saturated hydrocarbon or a Mixture of methyl chloride with butane, the solution at or below .des Boiling point causes the catalyst solvent. Then the solution of the catalyst cooled, filtered and added to the reaction mixture. Examples of other suitable ones Catalysts are: AIC13 - A1CI, OH, AlBr3 - AlBr20H, AlBr2C1 - AIOCl, AlBrCl2 - AIOBr, TiC14 - AIC120H, 'TiOC12 - TiC14, AlBr3 - Br2 - CSZ, BF, - Isopropyls, alcohol, a solution of B F3 in ethylene, a solution of activated B F3 in ethylene, a solution of activated B F, in methyl chloride. Volatile solvents or thinners, z. B. propane, ethane, ethylene, methyl chloride, carbon dioxide (liquid or solid) etc., can also serve as internal or external coolants. the resulting heat of polymerization derive.

After the copolymerization is completed, the remaining catalyst is replaced by water or alcohol, e.g. B. isopropyl alcohol, destroyed and excess catalyst removed by the fact that the product with. Water, especially with aqueous sodium hydroxide solution, is washed. The consistency of the resulting solid copolymer can range from that of a viscous liquid or a relatively stiff plastic mass to that of a hard or tough thermoplastic resin-like solid. It depends mainly on the polymerization temperature and the proportion of the cyclic component in the starting material, but also partly on the yield of polymer obtained from the active starting material; as well as the type and concentration of the catalyst. The proportions in which the reactants, e.g. B. styrene oil and isobutylene, are copolymerized; can be interpolated from a CH analysis, for example within the following limits Carbon hydrogen Pure styrene ........... 92.3 7.7 Pure isobutylene ....... 85.7 4.3 In general, the Staudinger average molecular weight of the product is above about 800, e.g. B. up to 3000, 5000, 25000, iooooo and much more. If the polymerization is carried out at lower temperatures, e.g. B. -75 to -z03 °, results in higher molecular weights, higher values of the intrinsic viscosity (greater than 0.6) and greater toughness of the polymer at room temperature. On the other hand, at not so low polymerization temperatures of z. B. - 40 or - 2o ° produced copolymers have a lower molecular weight and a lower structural viscosity, they are either viscous liquids, soft adhesive plastic materials or products with a hard, brittle structure.

According to the polymerization process given above, styrene-isobutylene copolymers were successfully prepared which, for. B. contain about 5o to 6o weight percent bound styrene and a high tensile strength of z. B. combine 70 to 14o kg / cmP and even more with a tough thermoplastic texture, whereby these products can be rolled out, pressed or otherwise shaped into thin, self-supporting films or other profiles. One brought the reactants with diluent and sufficient catalyst batchwise into a reaction vessel and allowed the reaction to proceed up to 100% conversion, ie until the polymerizable starting materials had completely reacted. However, when attempts were made to carry out this procedure consistently, the results left much to be desired. One reason for this is that the resulting interpolymer of, for example, 60 percent by weight bound styrene, if enough catalyst is used to achieve 100 percent conversion, has a very low intrinsic viscosity of about 0.25 to 0.3 percent, even if the polymerization is carried out at a relatively low temperature of, for example, -go °. If, on the other hand, such a continuous polymerization process is carried out with less catalyst and in a shorter time in order to end the reaction before the conversion is complete, the resulting copolymer has a significantly higher intrinsic viscosity with the same percentage of styrene in the starting material and the same temperature, e.g. B. about 0.5 at 80 ° / ° conversion, about 0.75 at 50 % conversion, or about 0.95 at] o 0 / ° conversion. But all processes with such a partial conversion have the serious disadvantages of the separation, purification and recycling of unpolymerized starting material. There are also a number of other, minor disadvantages, e.g. B. lower heat transfer coefficients in the reaction vessel.

In comparison, had a copolymer, which batchwise by polymerizing a styrene-isobutylene starting material with 60 percent by weight Styrene was made at the same temperature of - go ° and the same Dilution ratio of methyl chloride (about 5 parts by volume) has an intrinsic viscosity of about 1.25 at 30 "/, conversion, about i, i5 at 50 ° / ° conversion,. about i at 80 ° / ° conversion and about o.95 at 100 ° / ° conversion. However, one is such paragraphwise Operation accompanied by a number of disadvantages. A The disadvantage is that, from the point of view of the quality of the product, - the copolymer has an unreasonably wide spread both in terms of molecular weight the individual molecules as well as their chemical composition, d. H. of the relationship from bound styrene to isobutylene. Another disadvantage with the technical Manufacturing is the fact that it is frequent in intermittent operation as a result of the necessary Loading and emptying the reaction vessels is extremely difficult, high Loss of methyl chloride or other volatile solvents through leakage etc. to avoid. Other disadvantages of batch operation are e.g. B. the following: Excessive fluctuation in cooling loads and high maintenance costs of the system, furthermore, a relatively high amount of work, long operating times, are great Reaction spaces required for each individual approach, and also relatively weak active catalysts, then there is an inert gas zone in the reaction vessel for the addition of the catalyst solvent is necessary, and the liquid in the reaction vessel kept under pressure during the reaction cycle, etc.

It has now been found that most of the advantages of both the paragraph-wise as well as the steady operation and at the same time the disadvantages of both methods can be largely avoided by carrying out a continuous polymerization process, in which one reactants of the starting material, diluent and catalyst continuously mixed with one another in a first reaction vessel until partial conversion from about 3o to 7o, preferably about 4o to 6o percent by weight is achieved, whereupon one the reaction mixture, which the polymer and unconverted raw materials contains, continuously either by overflow, by pumping or by other suitable Funds funds in one or more additional reaction vessels. With two-stage The working method in the second stage is of course the conversion down to about 97 driven up to 100 per cent, while in a three-stage process the second Stage about 6o to 9o, preferably about 65 to 850 /, converts, followed in the third Level the conversion should be as high as possible, e.g. B. 97 to 100 per cent. As desired you can turn on a fourth level, with the third level about 8o to 95, preferably about 85 to 9o% converts and the reaction in the fourth Stage as completely as possible.

If one uses a multi-step steady process like this, it becomes practical To convert zoo%, the resulting end product is essentially a mixture from a number of different, relatively more homogeneous, in the individual stages produced copolymers. As a result, the product is not as homogeneous as a something that is continuously produced in a one-step process, but it has as high a molecular weight or intrinsic viscosity as any Product, which with a degree of conversion of about 5o to 6o0 /, in a one-step steady process is gained. The product is relatively much more homogeneous, both in terms of the spread of the molecular weight and the chemical Composition, as a product which at 100% conversion in batchwise Operation was established.

In the following table I some examples are provided for the degrees of conversion expediently to be observed in the individual stages in two-, three- and four-stage continuous process management of the polymerization according to the invention: Table I. % Conversion step 3! 4th a 5o to 65 97 to ioo b 6o 97 - 100 c 50 97--100 d 3o to 7o 6o - 90 97 to ioo e 40 - 8o 65 - 85 97 - 100 f 50 - 55 7o - 8o 98 - ioo g 50 80 97 - 100 h 6o 9o 97 - 100 i 2o to 6o 80 9o 97 to ioo j 40 70 90 97 - 100 k 30 6o go 97 - 100 The invention is not limited to the use of a specific reaction vessel in the various stages of the process, the design of these reaction vessels can rather be considerable in terms of size, shape, cooling device, type and extent of stirring, supply of reactants, diluent and catalyst and discharge of the polymerization mixture the reaction vessel can be modified. In the meantime, several multistage systems that can be used alternately are shown diagrammatically in the drawing to explain the invention. In these, FIG. 1 means a two-stage, FIG. 2 a three-stage and FIG. 3 a four-stage system.

In each figure, like reference numerals designate like parts.

In the figures, 1, 2, 3 and 4 reaction vessels of the first, second, third and fourth stage respectively. Each reaction vessel comes with one Stirrer 5 equipped, preferably one for high stirring speeds, which is able to quickly mix the liquid contents of the reaction vessel. Each reaction vessel is also equipped with suitable cooling devices, which are represented in the drawing by the outer cooling jacket 6, in which a suitable coolant is supplied through inlet 7 and withdrawn through outlet 8 will. Each reaction vessel is also provided with an inlet 9 for feeding all of them liquid reactant equipped except for the catalyst. The latter is fed through pipeline io. The liquid reaction mixture is normally removed from each reaction vessel through overflow vent ii, although also below a drainage port 12 intended for emptying the contents of the vessel is when the procedure is either for an occasional cleaning, or repair interrupted for other reasons.

Furthermore, an opening 13 can either be used as a safety valve or for Removal and recirculation of gases or vapors may be provided, what if in use an internal coolant is necessary. The pipes 14 connect the outlet ii, each reaction vessel with the inlet g of the next following reaction vessel.

Although the multistage continuous process according to the invention can be applied to a certain extent to the relatively low molecular weight copolymers which are z. B. have an intrinsic viscosity of 0.1 to 0.5 , which can be obtained at temperatures of about -12 to about -46 ° or a little lower. the method according to the invention offers the greatest advantage when it is applied to the copolymerization at lower temperatures of about -73 to = g6 °. in particular for the production of copolymers whose intrinsic viscosity is at least 0.5, preferably 0.7 to 1.5 , and whose content of bound styrene or corresponding cyclic compounds is about 50 to 65 percent by weight.

The following are used to further illustrate the invention Examples. Examples i to 3 In the laboratory, a plant for three-stage continuous polymerization built up, with three reaction vessels of one capacity of 51 used. Each reaction vessel had an external cooling jacket. in which liquid ethylene was used as a coolant, moreover it was equipped with a stirrer equipped.

The three reaction vessels were connected in series and through Overflow channels connected to each other.

Three different experiments were carried out continuously in this apparatus. A mixture of 50 percent by weight styrene and 50 percent by weight isobutylene and methyl chloride as a diluent was used as the starting material in each experiment. A solution of A1C13 in methyl chloride, the concentration of which was about oig per 100 ccm, was used as the catalyst.

In Examples r and 2, a starting material was used which 25 percent by weight polymerizable and 75% methyl chloride as diluent contains, in example 3, a more dilute starting material, the proportion of which is polymerizable was only 15 percent by weight. The reaction temperature was in all three experiments in the range from about -75 to -100 °, in the first two attempts at - 75 to - go ° and in attempt 3 at - go to - ioo °. This resulted in experiment 3 to a somewhat higher intrinsic viscosity of the reaction product.

In all three examples the feed rates were for The starting material and the catalyst are relatively high (about 500 or 35 ccm per minute), until equilibrium was reached. Then the feed rates reduced to the values given in Table II below. These also contains the percentage conversion, the percentage of the copolymer of bound styrene and the intrinsic viscosity of the copolymer, which is within increased at each level from experiment i to experiment 3.

The residence time of the liquid polymerization mixture in each reaction vessel was about 15 to 25 minutes. Table II Feed catalizer- 6% Step speed- speed- around- `` ° / o structure- No. speed 'wall-styrene viscosity ccm / min. ccm / min. lun g Example i 25 weight percent feed material 1 200 20 50 4r, 5 i, o 2 220 70 80 50.0 0 93 3 290 ioo ioo 5.3 o.83 Example 2 25 weight percent feed material 1 200 _ 14 - 50 45.0 i, i9_ 2 214 30 70 47, oi, o8 3,244 75 100 55.0 0.84 Example 3 15 weight percent feed 1 200 23 57 38, o 445 2 223 40 79 47.0 I, 2_ 3 263 49.0 8o ioo i, OB It can be seen from Example i that the percentage conversion (after equilibrium was reached in each case in the reaction vessel in question) was 50% in the first reaction vessel, 80% in the second and 100% in the third. The percentage of bound styrene in the first reaction vessel was 41.5, in the second 50 and in the third 51.5. The corresponding values for the intrinsic viscosity in the three reaction vessels were i, 0.93 and 0.38. This shows that in this three-step continuous process, in which the polymerization was carried out to a final conversion of 100%, the resulting copolymer has an average styrene content of 51.5% and an average intrinsic viscosity of 0.83. The main variable operating condition in achieving these various degrees of conversion in the three reaction vessels is the catalyst rate, which in the first reaction vessel was 20, the second 70 and the third 100 cc per minute.

The overall results from example e were roughly comparable with those which were obtained according to Example i, but the percentage bound is here Styrene slightly higher in the copolymer.

In Example 3, as previously indicated, a temperature was used which was about 10 ° below that selected in Examples 1 and 2. The intrinsic viscosity for the fractions obtained in the first, second and third stage was in each case somewhat higher, a direct result of the lower polymerization temperature. Five more experiments were carried out to illustrate the invention. In Examples 4 to 7, the reaction temperature was about -83 ° or slightly below. In all of Examples 4 through 8, styrene and isobutylene were used as the polymerizable reactants and methyl chloride was used as the diluent. A solution of aluminum chloride in methyl chloride in a concentration of about 0.07 to 0.2o g per zoo ccm served as the catalyst. The feed rate in example 4 to 7 was 20 to zoo ccm per minute. Example 4 It was carried out in two stages. The starting material from the first stage contained 15 percent by weight of polymerizable material, the styrene content of which was 50 percent by weight. 57 ° / o was converted. The reaction product had an average styrene content of about 40 percent by weight and an intrinsic viscosity of 1.18. In the second stage, the polymerization was brought to completion (conversion: 98%). The product had an average styrene content of 57.5 percent by weight and an intrinsic viscosity of 0.335. The total mixture of the products produced in the first and in the second stage had an average bound styrene content of about 47.5 percent by weight and an intrinsic viscosity of 0.82. This experiment shows that the advantages of the procedure according to the invention can be achieved fairly well even with a two-stage continuous process. The product essentially consisted of a mixture of two different products with the specified proportions, properties and the specified composition. Example 5 It corresponded to Example 14 with the difference that here a 25 percent by weight starting material (instead of 15) /,) was used and the process was operated in three stages. In the first stage the conversion was 46 "/", the product had an average styrene content of 35.50 /, and an intrinsic viscosity of 1.40. In the second stage the total conversion was 75.30 / ". The product produced in this second stage had an average styrene content of 45% and an intrinsic viscosity of 1.29. In the third stage, in which the conversion was practically complete, the average styrene content was 67.5% and the intrinsic viscosity was 0.42. The total mixture of the products produced in all three stages had an average styrene content of 47.2% and an intrinsic viscosity of about 1.12.

These results show that the three-stage procedure according to Example s gave better results (intrinsic viscosity 1.12 compared to 0.82) than the two-stage system according to Example 4. Example 6 This example corresponded to Examples 4 and 5, but here a starting material was used, which consisted of 35 weight percent polymerizable hydrocarbon material and 65 weight percent methyl chloride as a diluent. In the first stage the conversion was 43.5 ° / o. The product had a bound styrene content of 39.5% and an intrinsic viscosity of 1.14. In the second stage, the conversion was an additional 57 ß / u of the present, not yet converted reactants, so that the total conversion rose to 75.7 0 / u. The product of the second stage had a bound styrene content of 53% and an intrinsic viscosity of 1.23. In the third stage, the conversion progressed up to 98%, that is, it was essentially complete. The product produced in this stage had a bound styrene content of 710% and an intrinsic viscosity of 0.35.

The total mixture of the products made in the three stages had a bound styrene content of 510 /, and an intrinsic viscosity of o.97.

A comparison of Examples 4, 5 and 6, all using of a starting material were carried out, whose polymerizable 5o weight percent Styrene and 50 percent by weight isobutylene and contained 15, 25 and 35% in the starting material was included shows that Example s in which 25 weight percent hydrocarbon was good were used in the starting material, an overall product of the highest intrinsic viscosity (I, 12). So although the entire range from 15 to 35 percent by weight of polymerizable delivers very good results in the starting material, the preferred range is around 2o to 3o percent by weight of polymerizable in the starting material or at about 2 to 4 parts by weight of methyl chloride as a diluent per part by weight of styrene-isobutylene. Example 7 This experiment corresponded to the example insofar as the starting material Contained 15 percent by weight polymerizable hydrocarbon material, but existed here this polymerizable fraction of 60% styrene and 40% isobutylene, the process was carried out in three instead of two stages.

In the first stage the conversion was 66%. The product had a content of 56% bound styrene with an intrinsic viscosity of 1.07. In the second stage, the conversion was 78% of the reactants present, so that the total conversion here was 92.5%. The product produced in the second stage had a styrene content of about 680 / with an intrinsic viscosity of 0.70. In the third stage the reaction proceeded to about complete conversion (98%). The product of this stage was not examined for its styrene content, but had an intrinsic viscosity of 0.27.

The total mixture of the products produced in these three stages had a bound styrene content of about 60.80 /, with an intrinsic viscosity of o.g1. If one compares these results with those obtained with batch processing of a starting material with 60% styrene, the product having an intrinsic viscosity of about 1.15 at 50% conversion and about 1 and at 100% conversion of about 0.95 , it can be seen that if the process is carried out continuously in three stages using a starting material with 60% styrene, an overall product is obtained which has an almost equally good average intrinsic viscosity, without that the molecular weight and styrene content of the molecules of the copolymer in the mixed product vary excessively. In addition, this three-stage process has the many advantages of continuous operation over batchwise operation, which were mentioned above.

Example 8 This example was carried out in the same way as Examples 4 to 7, except that a different apparatus was used. This represented a three-stage plant for continuous operation, in which the initial polymerization material contained 60 % styrene and 40% isobutylene. The concentration of these monomeric hydrocarbons in the starting material was 25 percent by weight, the remainder 75% methyl chloride. In all three stages the temperature was about -go4. The catalyst was fed in the three stages at a rate of 17, 17.2 and 31 parts by weight per 100 parts by weight of hydrocarbon material. In the first stage amounted to. the conversion to 440/0; the product had a styrene content of 48 % with an intrinsic viscosity of 1.22. In the second stage, the conversion was 580% of the polymerizable constituents present, so that the total conversion here was 76.5%. The product produced in the second stage had a styrene content of 65.2% and an intrinsic viscosity of 0.93. In the third stage the reaction proceeded to essentially 100% conversion. The bound styrene content was calculated to be 79.4%, the intrinsic viscosity was 0.4. A total mixture of these three products gives an average intrinsic viscosity of 0.87 with a styrene content of 61. This value compares very well with the value of o, gi for the average intrinsic viscosity, which is shown in the example? for a similar production of a copolymer was obtained which contains 60% / a bound styrene, but from a starting material. starts out, whose content of polymerisable is 15 percent by weight compared to 25 ° / p in Example B.

Claims (8)

PATENT CLAIMS: i. Process for the continuous interpolymerization of a Mixture of aliphatic monoolefins and cyclic monoolefins of high structural viscosity at -i2 to - = o7 ° in the presence of "a Friedel-Crafts catalyst and a diluent, characterized in that there are reactants, diluents and catalyst in a first reaction vessel at the desired temperature under such conditions constantly -mixed with each other, that a partial polymerization takes place, that one of the reaction product, Unreacted starting material, catalyst and diluent Reaktiönsgut withdraws steadily from the first reaction vessel and through one or more further series-connected reaction vessels, in each of which one further Partial polymerization takes place until finally in the last reaction vessel as the end product a copolymer of the desired overall degree of polymerization is produced. 2. Process according to Claim i, characterized in that the reaction is carried out in the first Step up to a conversion of 20 to 70, advantageously 40 to 60% and in the subsequent stages one after the other up to a total conversion of 97 to 100 ° / o carried out in the last stage. 3. The method according to claim i and 2, characterized characterized in that each of the subsequent stages to the first stage further Catalyst feeds. 4. The method according to claim 3, characterized in that one at least as much catalyst is added to each subsequent stage as in the first Stage is used. 5. The method according to claim i to 4; characterized, that as an aliphatic monoolefin one of more than 2, advantageously of 4 to 8 carbon atoms, in particular isobutylene, are used. 6. The method according to claim i to 5, characterized in that the cyclic monoolefin is a vinyl aromatic Link; such as B. styrene or a monoalkyl or dialkyl or halogen substituted one Derivative of the same, e.g. B. indene, coumarone, a-vinylnaphthalene or dihydronaphthalene, used. 7. The method according to claim i to 6, characterized in that as Catalyst an active metal halide, such as boron fluoride, activated boron fluoride, Aluminum chloride, titanium tetrachloride or aluminum alkoxide = aluminum chloride complex, used. 8. The method according to claim 7, characterized in that the catalyst is dissolved in a solvent which consists of a lower alkyl halide. or a low molecular weight sulfur-free saturated hydrocarbon or a mixture thereof. _.g: Process according to claim i to 8, characterized in that the diluent is also used as an internal coolant in order to absorb the heat generated during the copolymerization. = o. Process according to Claims 1 to 9, characterized in that the diluent used is propane, ethane, ethylene, methyl chloride or liquid or solid carbon dioxide. = i. Process according to Claims i to = o, characterized in that the diluent is used in an amount of from 1 to 5 parts by volume per part by volume of reactants. 12. The method according to claim i to = i, characterized in that isobutylene and styrene are used as starting materials. 13. Process according to claims r to 12, characterized in that a starting material with 40 to 7o percent by weight of cyclic monoolefins is used. = 4. Process according to Claims z to i3, characterized in that the reaction is carried out at a temperature of -73 to -6 °. Cited pamphlets: French patents nos. 834 o18, 838 o64; British Patent Nos. 502 730, 503 755.