DE1301069B - Method for monitoring the polymerization of hydrocarbons containing terminal C-C double bonds - Google Patents

Description

can be avoided or by terminating the polymerization.
The concentration of solitary electrons can

formation of a metal from I. to III. Group of the peri-io position of products with undesired eigenodic system or an organometallic compound by immediate elimination of the inconsistency of tin or lead, if necessary in the presence
of additives.

In general it is relatively difficult
A chemical reaction with the help of such a 15 can be measured by punching the sub-catalyst to be investigated through the cavity of an electron spin on an industrial scale in such a way that a product results with a constant resonance apparatus. One embodiment forms properties. This is because the catalyst is particularly sensitive to traces of impurities in such an apparatus and the method used for measuring the number of lone electrons is subject to conditions such as moisture and oxygen. In addition, in the dissertation by J. S mi dt, Delft, the action of the catalyst influenced by the 1960, pp. 19 to 40, is also described. Ratio between the applied catalyst- You can measure this on the basis of the catalyst

components, the time during which the liquid contained is carried out, which is fed to the reacting zone of the Re-catalyst components beforehand. Although one leaves in general, and the temperature at which this opinion assumes that the catalytic converter in question is effective. If you polymerize z. B. bring about ethylene with no reactions in which the free radio aid of such a catalyst, so practice low kale play a role, surprisingly, changes in the variables mentioned and the concentration of lone electrons in concentrations of the impurities mentioned can be one of the Measure the reaction zone yourself. The latter has such a great influence that it is extremely difficult to produce 30 the advantage that it not only produces the variables of a polyethylene with constant, so-called melting and impurities, which are the same as the catalyst production number. The changes mentioned are
but mostly so small that they can be used during the
Cannot determine the polymerization process. First
when the product is ready and you have melted the 35
number of the product, you can find out whether
disruptive changes have taken place or not.

The inventive method is now through
characterized in that the concentration of lone electrons in the reaction zone and / or in an advantage that one can see whether the catalyst-containing liquid, which is supplied to the lysator manufacture or - if an alkylene poly reaction zone is fed, is measured and This merged - through the moisture content of the possibly occurring differences between the alkylene fed to the reaction zone, a change measured and the value established in advance - corresponding to the desired concentration of lone electrons in the properties of the polymers - brought about by the actuator. The concentration of lone electrons in the

If the polymerization process is carried out continuously, the reactor does not have to be the same as the one of course, this value is constant. In the case of the one containing the catalyst and the discontinuous process, it can occur with liquid flowing into the reactor. One only has vary. In this case it comes to the value 50 to ensure that the two concentrations the equal to which the concentration in the production have a desired value. It turned out to be one previous load to a corresponding, that one products with better mechanical end Point in time. see properties, the lower the con-

The predetermined value of the concentration concentration of lone electrons during the polyan lone electrons is determined by the fact that 55 merization of terminal C-C double bonds one is in a preliminary test polymers with the substances contained.

desired properties, e.g. B. with the desired In general, you can measure at the

"Melting number", produces and thereby carry out the concentration temperature that the catalyst of lone electrons in the reaction zone and containing liquid or the contents of the reactor or or in the 60 containing the catalyst, so that it does not require liquid for the determination certainly. The method of preparation such is to first cool or to cool a sample Such polymers are then heated in accordance with the invention.

the way that one monitors the concentration of the changes in the concentration of lonely

solitary electron measures and thereby optionally electrons can basically be used as impulses for Deviations of the measured value from the one in front of a noise device or an automatic regulator determined value. Apply such deviations in the chemical reaction. So can show changes in the reaction conditions and z. B. in continuous polymerization thus disturbances in the polymerization process, z. B. of ethylene the ratio of the catalyst components

ment played a role, but also the on is able to monitor impurities introduced into the reaction zone in another way.

However, the concentration of lone electrons is preferably periodically or continuously both in the liquid containing the catalyst which is fed to the reaction zone, as well as measured in the reaction zone itself. This has the

nents regulate automatically in such a way that the measured concentration of solitary electrons holds at a desired value, provided that one is convinced that the other variables and the concentrations of impurities are sufficiently constant.

The following examples illustrate the invention.

example 1

_{50 ml of a solution of TiCl 4} in heptane (0.10 mol / l) and 2 ml of a solution of diethylaluminum chloride in heptane (1.25 mol / l) are placed in a glass vessel filled with nitrogen at room temperature. A circulation line is connected to the vessel and runs through the cavity of an electron spin resonance apparatus. The concentration of lone electrons, which can be determined with the aid of this apparatus, has become constant after 5 minutes and is then 0.20 mmol / l.

After 60 minutes, ethylene is added to the vessel, which forms a powdery polymer. the Change in the concentration of lone electrons depends on the speed with which ethylene is added, in such a way that at a low addition rate the concentration on solitary electrons is higher than at high additional speed. This effect is shown in Table 1. The polymerization time for these experiments is also set at 60 minutes.

Table 1 Example 3

Addition of a solution of ethanol in heptane (0.66 g mol / l) to that described in Example 1 Catalyst solution causes the concentration of lone electrons to decrease (see Table 3).

Table 3

Ethanol concentration
of lonely electrons mmol mmol / 1 0.20 0.053 0.19 0.112 0.17 0.31 0.16 0.64 0.11 1.08 0.06 1.72 0.02 2.4 0.01

Example 4

Addition of a solution of carbon tetrabromide in _ag heptane (0.64 g mol / l) to the catalyst solution described in Example 1 causes the concentration of lone electrons to decrease in the manner mentioned in Table 4.

Table 4

Clogging
from
Ethylene
l / h concentration
of lonely electrons
in mmol / 1
during the polymerization 1.6
9.0 0.53
0.22

Example 2

The amounts of water vapor mentioned in Table 2 are added to the catalyst solution described in Example 1 added by drying the nitrogen above the solution by dampening it Replaced nitrogen. It turns out that the concentration of lone electrons increases initially. If more water than 0.2 mmol is added, then the mentioned concentration drops again afterwards, until it has reached the constant value mentioned in Table 2.

Table 2

Tetrabromous concentration carbon of lonely electrons mmol mmol / 1 __ 0.20 0.12 0.17 0.35 0.12 0.54 0.10 0.77 0.085 1.28 0.060 1.92 0.042 2.52 0.030 2.85 0.024

water concentration
of lonely electrons mmol mmol / 1 0.20 0.1 0.43 0.2 0.58 0.25 0.54 0.50 0.43 0.75 0.29 1.00 0.24 1.25 0.16 1.50 0.05 1.75 0.03 2.00 0.01

Example 5

In the manner described in Example 2, oxygen is added. The concentration of lonely Electrons increase and then decrease as more oxygen is added. After addition of about 1.2 mmol of oxygen this concentration is zero.

The phenomena described in the examples also occur when one with much lower Catalyst concentrations (e.g. 1 to 10 mmol

of the catalyst components per liter) works, and even if you have other catalyst components, such as di-isobutylaluminum chloride, di-isobutylaluminum hydride, Methyl aluminum dichloride, dimethyl aluminum chloride or e.g. B. cyclopentadienyl titanium dichloride, applies.

Claims (1)

Claim: Method for monitoring the polymerization of terminal C-C double bonds containing hydrocarbons, a catalyst being introduced into the polymerization zone that by bringing together little at least a compound of a metal from groups IVa to VII a or VIII. group of the periodic Systems with a metal, an alloy, a metal hydride or a Organometallic compound of a metal from I. to ΠΙ. Group of the Periodic Table or a Organometallic compound of tin or lead, possibly in the presence of additives, has been produced, characterized in that the concentration of lone electrons in the reaction zone and / or in the liquid containing the catalyst which is fed to the reaction zone, measures and any differences between the measured and the - According to the desired properties of the polymers - predetermined value notices.