DE1158263B - Process for the production of polymers from aliphatic olefin hydrocarbons - Google Patents

Description

GERMAN

PATENT OFFICE

B41304IVd / 39c

REGISTRATION DATE: AUGUST 6, 1956

NOTICE THE REGISTRATION ANDOUTPUTE EDITORIAL: NOVEMBER 28, 1963

In the low pressure process for the production of polyolefins, the polymerization of the olefin made in an organic solvent in which the necessary for the formation of the polymer Catalysts are dissolved or suspended. The solvents should not interfere with the organometallic Compounds with the compounds of the elements of the IV. To VIII. Subgroup of the periodic Systems, especially with titanium tetrachloride or tin tetrachloride, or with those from the mixture of the compounds resulting from the two components react. They also need to be cheap, lightweight accessible and easy to work through. For this reason, only aliphatic or hydroaromatic hydrocarbons as solvents for the polymerization and for the catalyst mixture used.

The invention relates to a process for the preparation of polymers from olefin hydrocarbons with a certain average molecular weight in the presence of in diluents suspended catalysts obtained by stirring compounds of the elements of IV. to VIII. Subgroup of the periodic system, in particular of titanium, with organometallic compounds, in particular of aluminum, are produced in a diluent, characterized in that such catalysts are used, which are obtained by stirring the components mentioned in mixtures from saturated aliphatic hydrocarbons and / or hydrogenated alkylbenzenes on the one hand and Cyclohexane, on the other hand, have been produced.

When using mixtures with a high proportion of hydrogenated alkylbenzenes, in particular hydrocumene, and / or of aliphatic, saturated ones. Hydrocarbons such as mineral spirits, mixtures of aliphatic hydrocarbons of the Fischer-Tropsch synthesis having a boiling range between about 140 and 23O ^c C, for agitating the catalyst components to obtain a high molecular weight product at a higher polymerization rate; In addition, during the polymerization of olefins with a carbon number higher than 2, there is also an increase in the crystalline fraction. If, on the other hand, high proportions of cyclohexane are used, the rate of polymerization is noticeably reduced. The molecular weight of the product obtained is also considerably lower, and finally the end product may have an increased proportion of amorphous constituents. This influence of the diluent can probably be explained by the fact that in the case of heterogeneous catalysis and processes for the preparation

of polymers made from aliphatic

Olefinic hydrocarbons

Applicant:

Mining Company Hibernia
Aktiengesellschaft, Herne

Dr. Ermbrecht Rindtorff, Recklinghausen,

Dr. Karl Schmitt and Dr. Günther Keller,

Tub-Eickel,
have been named as inventors

This is what it is about here - the particle size and surface properties of the catalyst play an essential role in the response. As has been established, however, this depends primarily on the choice of the mixing ratio in the mixture used as the diluent. This is it is also at the same time (in contrast to the previous view) explainable that conversely the solvent, in which the polymerization is carried out, no noticeable influence on the course of the polymerization Has.

It is thus possible by choosing the composition of the diluent mixture in which the catalyst is stirred, polymers with the to achieve desired average molecular weight. With a constant ratio of Catalyst components, for example titanium tetrachloride to aluminum diethyl monochloride of 1: 2, any desired molecular weight between, for example, about 150,000 and 800,000. (This information are not absolute values, but only relative values determined on the basis of viscosity measurements Values.)

On the basis of the new findings, one can now use catalyst mixture ratios and Mixing temperatures work at which the molecular weight hardly changes from this depends on both factors. In the known polymerization processes, for. B. one for the later application technology favorable molecular

309 750/435

A weight of 100,000 can only be achieved by using a molar ratio of 1: 1.3 for titanium tetrachloride and aluminum diethyl monochloride polymerized as catalyst components (cf. Documents of the Belgian patent 540 459, p. 6). Reacts in this range of the mixing ratio but the molecular weight is extremely sensitive to only small changes in the ratio of the Catalyst components, because you are right here near the turning point of the curve molecular weight = / (Ti: Al) is located. At a ratio of 1: 2, on the other hand, you are back on the horizontal part of the curve, d. that is, the molecular weights change even with a larger change the catalyst mixture ratio is no longer essential. The significantly higher molecular weight, that would arise in this relationship according to the known method, can be through a according to the invention, selection of the mixing ratio in the diluent mixture again reduce to 100,000. So it is possible by simply varying this mixing ratio the catalyst mixture to influence the average molecular weight of the end product without to be dependent on the previously unavoidable uncertainty factors that lie in the catalyst composition and mixture temperature.

The preferred mixing temperature is 20 to 50 ° C. If the catalyst is at room temperature the molecular weight reacts very sensitively to small temperature fluctuations in the catalyst mixture. If, on the other hand, the catalyst mixture is carried out at 45 ° C., it changes the molecular weight hardly changes with small temperature fluctuations. The fact that it is significant is higher than it may be desired, you can again by choosing the composition compensate for said diluent mixture in the catalyst mixture.

Of course you can also, if it appears appropriate for certain application-technical purposes, vary the catalyst composition.

example 1

2 g titanium tetrachloride and 2.4 g aluminum diet monochloride are stirred at 45 ° C in 100 ecm of a mixture that is made in equal parts η-hexane and cyclohexane. After stirring for 15 minutes, the deep brown suspension is in 900 ecm Given cyclohexane and initiated ethylene. To

Hours, the yield of polyethylene is about g with a molecular weight of 500,000.

The catalyst is stirred in a mixture consisting of 1 part of cyclohexane and 3 parts of n-hexane exists, a molecular weight of about 650,000 is obtained with the same yield.

At a ratio of 3 parts of cyclohexane to part of η-hexane, a molecular weight of about 250,000.

Example 2

In 100 ecm of a mixture that consists in equal parts of cyclohexane and η-hexane g titanium tetrachloride and 5.8 g aluminum triethyl mixed at 45 ° C. After 15 minutes, 900 ecm Cyclohexane was added and propylene was introduced at 10 atm. About 200 g of polypropylene are obtained after 3 hours with a specific viscosity of? y = 2.4 (measured in hydrocumene at 125 ° C).

About 5O ^fl / o of the product are soluble in cyclohexane and 50 ° / o insoluble.

Claims (2)

PATENT CLAIMS: 1. A process for the preparation of polymers from olefin hydrocarbons with a certain average molecular weight in the presence of catalysts suspended in diluents, which are formed by stirring compounds of the elements of subgroups IV to VIII of the Periodic Table, in particular titanium, with organometallic compounds, in particular aluminum , have been prepared in a diluent, characterized in that such catalysts are used which have been prepared by stirring the components mentioned in mixtures of saturated aliphatic hydrocarbons and / or hydrogenated alkylbenzenes on the one hand and cyclohexane on the other hand. 2. The method according to claim 1, characterized in that use such catalysts that have been prepared by stirring the components at temperatures of 20 to 50 ⁰ C. Considered publications:
Published documents of Belgian patents nos. 533 362, 534 792, 534 888, 543 082, 543 912,
941.