DE2738436A1 - PREPARATION OF A HOT HYDROCARBON SOLUTION FROM AETHYLENE POLYMERS - Google Patents

Description

DR. KURT JACOBSOHN PATENT ADVOCATE

POST BOX / P. OB 58 FREISINGER STR. 29 D-8O42 OBERSCHLEISSHEIM TELEFON IO89) 3 15Ο4 5Θ

26th of August. 1977

MY CHARACTER / MY REF .:

3 HF

H-6

GULF OIL CORPORATION Pittsburgh, Pennsylvania 15230, USA

Production of a hot hydrocarbon solution of ethylene polymers

Addition to patent application P 27 16 256.7

The priority for this application is November 22, 1976 from the USA patent application Serial No. 7 ^ 3 335 to complete

taken.

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ORfG (NAL INSPECTED

GB-PS 1 372 116 describes the production of fibrous materials which are suitable for the production of water separated leaves are suitable. Such products are made from high molecular weight ethylene polymers and called fibrils. In making these fibrils, the high molecular weight ethylene polymer becomes the one inherent viscosity of at least 3 »5, all in one Hydrocarbon dissolved at a temperature of at least about 130 C, and this solution is the starting material for the manufacture of the fibrils.

However, the production of such solutions of ethylene polymers presents technical difficulties. Because of the very high Molecular weight of the ethylene polymers used in the process, the polymer solutions have even at low concentrations high viscosities. The high viscosities of these polymer solutions make it difficult to obtain adequate solutions to stir to bring all of the ethylene polymer particles into solution. This is a serious problem because it has been shown that the grade of the finally obtained fibrils is impaired if in the one used in the process Ethylenpolymerlösung undissolved solid polymer is contained.

The production of such ethylene polymer solutions is costly and consumes a lot of energy, since very large amounts of hydrocarbons are required to dissolve the ethylene polymer. Typically, 96 parts by weight of hydrocarbon solvent are required to bring k parts by weight of ethylene polymer into solution. When the fibrils are made, the heated polymer solution is then cooled to precipitate the ethylene polymer therefrom. In the cycle, the hydrocarbon then has to be reheated.

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if

In view of these circumstances, it would be advantageous if a hot hydrocarbon solution of the ethylene polymer by polymerizing ethylene in the hydrocarbon could produce as a solvent. This would reduce the energy required to manufacture the intended end product Fibrils can be reduced because the ethylene polymer then does not need to be cooled and reheated. Furthermore could the heat of polymerization of ethylene can be used to provide a substantial part of the energy required to produce the hot ethylene polymer solution. Up to now, however, it has not been possible to produce such hot solutions of ethylene polymers of high molecular weight directly by polymerizing ethylene in a hydrocarbon solvent. The difficulty lay in the familiar The fact that the molecular weight of an ethylene polymer decreases as the polymerization temperature is increased. With the previously known catalysts, it was not possible to produce ethylene polymers with an inherent viscosity of at least 3.5 in a hydrocarbon as a solvent by direct polymerization at temperatures above 100 C.

The invention provides a method for making hot hydrocarbon solutions of ethylene polymers having inherent viscosities of at least 3.5. the Invention is based on the finding that it is possible to produce ethylene polymers with an inherent viscosity of at least 3.5 to produce, even if the polymerization is carried out at temperatures of at least about 130 ° C, provided you the ethylene is polymerized in a hydrocarbon solution in the presence of a polymerization catalyst according to patent 27 16 256.

The main patent relates to polymerization catalysts which are produced by using an aluminum alkyl compound

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dung rait a chemically modified one located on a carrier Transition metal chloride reacts that for their part according to a multi-stage process

1. suspending a finely divided polymer such as polyethylene, in the alkanol solution of a magnesium compound, e.g. a solution of magnesium chloride in methanol,

2. the evaporation of the alkanol with the deposition of a complex compound from magnesium compound and alkanol on the carrier,

3. Suspending the product of step (2) in a liquid Hydrocarbon and reacting with an aluminum alkyl compound, such as diethyl aluminum chloride, and

4. the reaction of the product of step (3) with a transition metal chloride compound, like titanium tetrachloride,

has been made.

As stated in the main patent, such polymerization catalysts are suitable for the production of ethylene polymers according to the so-called particle polymerization process, in which the polymerization takes place in a liquid hydrocarbon is carried out, the ethylene polymer formed under the conditions prevailing in the polymerization of Temperature and pressure do not dissolve.

Claim 11 of the main patent relates to the use of this catalyst for the polymerization of ethylene by man

(a) the catalyst suspended in a liquid hydrocarbon,

(b) through the slurry obtained in step (a) gaseous ethylene for a period of less than 5 minutes about atmospheric pressure and a temperature of less than about 20 C and

(c) the catalyst treated according to step (b) for polymerizing of ethylene used at temperatures well above 20 ° C and pressures well above atmospheric pressure.

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The polymerization of ethylene is carried out by suspending the polymerization catalyst in a suitable high-boiling liquid hydrocarbon, heating the hydrocarbon to the desired reaction temperature and feeding ethylene of polymerization grade to the reaction zone. If the polymerization is carried out batchwise, it is continued until the concentration of the ethylene polymer has reached the desired level. Usually, the polymerization is continued until the ethylene polymers have a concentration of at least 3 wt.%, Preferably from h to 7 wt.%, Is reached. Usually the polymerization cannot proceed beyond the point where the concentration of the ethylene polymer in the reaction mixture is greater than about 7% by weight. This process limitation is based on the practical point of view that solutions with higher solids concentrations are too viscous for easy handling; the high viscosity is due to the very high molecular weight of the ethylene polymer produced in the process. The polymerization is preferably carried out in a continuous process by continuously feeding ethylene, the polymerization catalyst used according to the invention and the hydrocarbon to the reaction zone and continuously withdrawing the polymer solution from the reaction zone. The feed and withdrawal speeds are chosen so that the residence time of the ethylene in the reaction zone is such that the polymer solution withdrawn from the reactor has an ethylene polymer content in the range given above.

The hydrocarbon used in the process should have a boiling range such that its vapor pressure is 130 ° C is not higher than 0.5 MPa (megapascals) [5 at] and is preferably less than 0.2 MPa. Used preferably a mixture of predominantly aliphatic hydrocarbons, such as luminous oil; however, the hydrocarbons can

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moderate contents of aromatic and cycloaliphatic !! Hydrocarbons without affecting the process. The hydrocarbon should be carefully dried because water is known to act as a poison on Ziegler catalysts. Depending on the origin of the hydrocarbon Additional treatments may be required to remove organic compounds that are nitrogen, oxygen or Contain sulfur atoms, since these compounds are also known to be deactivating on Ziegler catalysts works.

In the process, the polymerization catalyst should be in a concentration in the range from 0.01 to 4 g / l reactor volume can be applied. The polymerization is carried out at a temperature of at least about 130 C; by application No further advantages are achieved at polymerization temperatures above about 150 ° C. Usually the polymerization at an overpressure of at least about 0.2 and preferably carried out by at least about 3 MPa, so that the ethylene concentration in the reaction medium is sufficient to be useful To achieve polymerization rates.

The polymerization temperature, the concentration of the polymerization catalyst and the ethylene concentration (controlled by the partial pressure of the ethylene) are kept in such a balance that an ethylene polymer with an inherent viscosity of at least 3.5 is formed. Methods for determining the inherent viscosity of ethylene polymers are described in GB-PS 1,372,116. The most surprising and salient feature of the process according to the invention is that ethylene polymers of such high inherent viscosity can be produced at such high temperatures. In fact, it is known that increasing the polymerization temperature usually leads to a reduction in the molecular weight and inherent viscosity of the resulting ethylene polymers.

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Furthermore, most of the Ziegler catalysts become inactive at the temperatures used in the process according to the invention.

The method according to the invention yields very high polymer isate yields, based on the polymerization catalyst used. Minimum yields are typical for the process in the order of magnitude of about 1200 g polymer per g titanium per hour. As a result of the high yields, the resulting polymers contain so few catalyst residues that none Post-treatment after polymerization is required to remove such residues.

The process according to the invention is primarily aimed at the production of homopolymers of ethylene; however, copolymers of ethylene with C ₅ and higher monoolefins, such as propylene and butylene, can also be produced. However, the concentration of such higher olefins in the monomer mixture is preferably limited to a maximum of 25 molar of the ethylene used in the process. Lower concentrations of hydrogen can be used in the process to modify the molecular weight of the ethylene polymers produced in the process.

Examples 1 to 5

There are three catalysts for the polymerization of ethylene prepared by the process according to the invention.

Part A Manufacture of the carrier

An A-liter reaction vessel equipped with an old stirrer, reflux condenser, dropping funnel and devices for heating and cooling is charged with a solution of 75 g of magnesium chloride in 1 l of methanol. In this solution 670 g of a fine powder of low-pressure polyethylene become old

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ή 273Ö436

slurried with an average particle diameter of less than 40 µm. The slurry is heated to 55 ° C. in the course of 30 minutes and then stirred at this temperature for a further 30 minutes. The absolute pressure is then reduced to 1333 Pa to drive off methanol. The mixture is heated under these for a further 2 hours Conditions to remove all the methanol which is not in the complex compound deposited on the polyethylene support entered with the magnesium chloride. The powder is removed from the reaction vessel and cut to such particle sizes grind so that it passes through a sieve with a mesh size of 0.425 mm.

Part D.

Preparation of the chemically modified transition metal chloride compound

200 g of the so prepared, treated with magnesium chloride polyethylene powder, a suitable amount of heptane and one A suitable amount of diethylaluminum chloride is placed in a 4 liter reaction vessel equipped as described above. The reaction mixture is stirred at 25 ° C. for one hour. Gas develops in the process. It is believed that too at this point the added diethylaluminum chloride to the polymeric carrier or one of the chemical on it Ties. The reaction mixture is then heated to 80 ° C. and removed from the dropping funnel over the course of one hour mixed with a suitable amount of TiCl ^. Then the reaction mixture is stirred for a further 16 to 20 hours at 80 ° C, about the reaction between the TiClr and those on the carrier Components to complete. Before adding the TiCl. the solids in the slurry show a light yellow color which turns purple shortly after the addition of the TiCl ^. The liquid of the slurry is decanted, and the solids are washed several times with heptane

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1 738436

see until the heptane no longer reacts to chloride. The solids are then filtered off and dried in vacuo at room temperature.

Part C. Preparation of the polymerization catalyst

2 parts of a product prepared according to Part B are suspended in 500 parts of heptane. Then 36 parts of aluminum triethyl are used (as a 25% solution in heptane) in the course of 10 min with stirring. This dispersion of the polymerization catalyst is under strictly anhydrous conditions for the polymerization of ethylene is preserved.

In all of the work steps described above, care is taken ensure that all reactions are carried out under strictly anhydrous conditions. All respondents have been cleaned and do not contain any detectable concentrations of water or reactive hydrogen compounds, which are known to have an adverse effect on Ziegler catalysts.

In the table below, Part A shows the amounts of reactants used in the reactions described above in Part B of this Example. Part B of the table gives the chemical analysis of the chemically modified transition metal chloride compounds prepared according to Part B of this example at.

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Table part A

Production of the chemically modified transition metal

chloride compound

example

1
2
3

Catalyst·
carrier, g

200
200
200

Heptane, ml

400 300 300

DAAC », g

72 36 36

663 345 345

DÄAC «diethyl aluminum chloride.

part B

Magnesium,
Weight % Analysis of the Catalyst 4th Titanium,
Weight * Total on
organic
Fabrics,
Weight * example 1.7 Aluminum,
Weight% Chlorine,
Weight * 2.0 13.7 1 2.0 0.3 9.7 2.6 24.6 2 1.7 4.1 15.9 2.8 22.3 3 2.7 15.1 example

In a 1 liter reaction vessel equipped according to Example 1, 67 g of linear low-pressure polyethylene with a particle size of less than 40 μm are suspended in 100 ml of methanol containing 7.5 g of magnesium chloride in solution. Then added to 250 ml of heptane and heated the reaction mixture to obtain a distillate fraction old a boiling point of 59-60 ° C is withdrawn. After removal of 175 al distillate the Destillationetemperatur rises to the boiling point of the ataoaphlriachen heptanes.

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The reaction vessel is cooled to room temperature, whereupon a solution of 12.7 g of diethylaluminum chloride is obtained in the course of 15 minutes added dropwise in 70 ml of heptane. A colorless gas develops, which is let off. Then will the reaction mixture is heated to 80 ° C., and 138 g of TiCl ^ are added dropwise. At the beginning of the addition of the TiCl ^ this has Reaction mixture a straw yellow color, but about 15 min after the addition of the TiCl ^ suggests the color of the solids in the Reaction mixture in purple around. The mixture is then heated for a further 16 hours while stirring. The reaction vessel is thereupon cooled and the solid catalyst filtered off. The filter residue is mixed with individual portions of dry heptane washed until the heptane used for washing gives a negative test for soluble chlorides.

A total of 0.2 g of the catalyst component described above is suspended in 50 ml of heptane in which 0.36 g of aluminum triethyl is dissolved.

Example 5

A 19 l stirred reactor is charged with 12.3 kg of luminous oil and a slurry of 2 g of the catalyst prepared according to Example 2 in 40 ml of heptane. The reactor is heated for one hour at 145 ° C, being opened from time to time, a vent in the reactor, to withdraw small amounts of imported into the reactor heptane. Ethylene of a polymerization grade is then introduced into the reactor until the overpressure has risen to 1.4 MPa, control elements are then set so that the ethylene is fed to the reactor at a rate of 136 g / h. The introduction of gaseous ethylene into the reactor takes 3.5 hours. After stopping the Äthylenzufuhr nan stirred for one hour at 145 ° C, in order to transfer the remaining ethylene in the polymer. The final reaction product

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consists of a hydrocarbon solution containing 3% by weight of polyethylene contains.

The polymer solution is cooled to room temperature to precipitate the polyethylene. The solid polyethylene obtained is washed several times with heptane and dried overnight in a vacuum oven at 50 ° C. The inherent viscosity of polyethylene, determined according to the method of GB-PS 1 372 116, is greater than 3.5. According to ASTM test standard 1238-70 (Cindition F) under The melt index of polyethylene, which is certain to be exposed to high loads, is less than 0.02.

Example 6

Example 5 is used and the hot polymer solution is used directly to produce fibrils according to the method of GB-PS 1,372,116. The fibrils obtained are of a better quality than a comparison batch of fibrils made from a 3-strength solution of ethylene polymer with essentially the same inherent viscosity as that described in Example 5 Luminous oil was dissolved.

Because the two polymers have the same inherent viscosity and in the luminous oil in the same concentration are present, it can be assumed that the improved quality of the solution prepared according to the invention obtained fibrils is based on the fact that in the preparation of the hydrocarbon solution used for the comparison sample small amounts of polyethylene have not completely dissolved and imperfections in the fibrils have caused.

Examples 7-10

There are three more solutions of ethylene polymer of high molecular weight following the procedure of the example

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produced with the difference that the catalyst produced according to Example 1, 3 or k is used as the polymerization catalyst. In all cases, the polymerization proceeds smoothly and results in the formation of ethylene polymers having an inherent viscosity of greater than 3 _f 5, is determined by the method of GB-PS 1,372,116.

End of description.

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Claims (3)

Patent claims i1 / Use of a polymerization catalyst according to Patent 27 16 256 in the polymerization of ethylene according to claim 11 of patent 27 16 256 for the production of a hot Hydrocarbon solution of ethylene polymers with an inherent viscosity of at least 3.5, characterized in that that the polymerization at a temperature of at least 130 ° C in a high-boiling liquid hydrocarbon which has a boiling range such that its vapor pressure at 130 ° C is not higher than 0.5 MPa. 2. Use according to claim 1, characterized in that the polymerization is carried out at about 145 ° C. 3. Use according to claim 1 or 2, characterized in that luminous oil is used as the high-boiling liquid hydrocarbon is used. 809821/0561