DK145667B - PROCEDURE FOR POLYMERIZATION OF ETHYLENE - Google Patents

Description

(19) DENMARK Queue)

É | (12) PUBLICATION WRITE OR 1 ^ 5667 B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 2960/75 (51) | nt.CI.3 Q 08 F 110/02 (22) filing date 30 Jun. 1975 C 08 F 4/64 (24) Race day 30 Jun. 1975 (41) Aim. available Jan 2 1976 (44) Presented 17 «Jan. 1983 (86) International Application No. - (86) International Filing Day - (85) Continuation Day - (62) Master Application No. -

(30) Priority 1 Jul. 1974, 24660/74, IT

(71) Applicant SNAMFROGETTI S.P.A., Milan, IT.

(72) Inventor Margherita Corbellini, IT: Agostino Baldueci, IT.

(74) International Patent Bureau.

(54) Process for Polymerization of Ethylene.

The present invention relates to a process for the polymerization of ethylene in which the reaction is carried out in the presence of a catalyst system comprising trivalent titanium halides and an aluminum compound of a polyiminic nature.

From British Patent Specification No. 1,131,258 such a method is known, using an aluminum compound having [s] _ formula LO -ΓαΙ - N-- I * "2 H R n

-i - J

wherein R is an alkyl, cycloalkyl or aryl group and n is numbers from 4 to 50. Furthermore, a process for polymerizing ethylene is known by means of a titanium trichloride catalyst system and aluminum compounds of the type AIR ^. However, the known methods undergo very large yield reductions when carried out in the presence of hydrogen acting as a molecular weight regulator.

It has also been known that attempts have been made to overcome this disadvantage by using a special catalyst system supported on suitable materials which require pre-treatments which sometimes have to be carried out using cumbersome and expensive methods.

It has now been found that using a special catalyst system, it is possible to polymerize ethylene in the presence of hydrogen as a molecular weight regulator in good yield without any catalyst support.

The process according to the invention is characterized in that hydrogen is used as a molecular weight regulator and as said aluminum compound uses one of the formula

Alh O®> k HjYj wherein R represents an alkyl group of 1-6 carbon atoms, H is hydride-hydrogen, Y represents a halogen atom, k is in the range of 2-50, h / k> 1, (i + jVh> 1, wherein the reaction is carried out at temperatures in the range of 0-150 ° C, preferably from 70-100 ° C, and at pressures in the range of 1-50 atmospheres, preferably from 6-20 atmospheres, and in presence of a solvent selected from aliphatic, aromatic and cycloaliphatic hydrocarbons.

The aluminum compound used in the process of the invention, hereinafter referred to as "PIAPE", is a modified polyiminoalan and is the subject of Danish Patent Application No. 2958/75.

This aluminum compound is, as the formula clearly shows, characterized by an N / Al atomic ratio of less than 1 and by an (H act + Y) / Al atomic ratio of more than 1, wherein the term "active hydrogen (H act)" refers to the hydride hydrogen atoms directly bonded to aluminum and can be determined analytically by known methods.

The process of the invention enables the obtaining of polyethylene in high yields relative to titanium, so that no washing step is necessary to purify the polymer from the catalyst residues.

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The titanium amounts in the final polymer are less than 15 ppm. This property and working conditions will become more apparent from the following exemplary embodiments.

Example 1 - Comparative Example In a 5 liter autoclave, dried under vacuum at 85 ° C, 2.5 liters of anhydrous n-heptane, which was further free of air, which contained a modified polyiminoalan in an amount sufficient to give 20 mg atom of active hydrogen per liter of mixture. The compound used had the formula Al 2 (N-isopropyl) gHgCl. The whole was maintained at 95 ° C in a thermostat (the best temperature for this catalyst) and then 60 mg of TiClg of type AA (AA means aluminum activated), suspended in 300 ml of n-heptane, was added. Ethylene was added at 6 atmospheres, the purity being 99.7% (C 2 <20 ppm, C 2 H 2 <2 ppm, E 2 O <20 ppm) and this pressure value was maintained by an ethylene flow regulated by the the course of the polymerization reaction.

After 6 hours of reaction, the autoclave was opened, the suspension was centrifuged and the polymer dried under vacuum at 60 ° C and then weighed. g titanium at a 2 pressure of 6 kg / cm for 6 hours.

Example 2 - Comparative Example

Proceed as in Example 1, however, the cocatalyst consisted of 20 mg atom / l of AlEtg. The polymerization temperature was 85 ° C, the best temperature for the catalyst pair used. 68 kg of 2 polymer per g Ti at 6 kg / cm ethylene pressure for 6 hours.

Example 3

Proceed as in Example 1 with the same catalyst. The only difference consisted in the presence of hydrogen added after the addition of the catalyst: P "= 3 kg / cm 2 a2 2" -6 kg / cm C2 H4

Ph / PC2H4 = 0.5

Yield = 54 kg of polymer per g Ten for 6 hours. The polymer does not flow.

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Example 4 - Comparative Example Proceed as in Example 2, however, with hydrogen added: = 3 kg / cm 2

PP TT = 6 kg / cm2 c2h2

Ph2 / Pc2H4 = ° 5

Yield = 23 kg polymer per g Ten for 6 hours. The polymer does not flow.

Example 5

Proceed as in Example 3, however, the hydrogen pressure being 26 kg / cm.

ph / Pc2h4 = 1

Yield = 47 kg polymer per g Ten for 6 hours. Melting sound index at 2.1 kg (MFI) = 0.05.

Example 6 - Comparative Example

Proceed as in Example 4, however, 2 2 = 6 kg / cm 2 VPc 2 H 4 - 1

Yield = 10 kg polymer per g Ten for 6 hours.

MFI = 0.01.

Example 7

Proceed as in Example 3, however, with Ps2 / PC2H4 = 2.

Yield = 35 kg polymer per g Ten for 6 hours.

MFI = 1.3.

Example 8 - Comparative Example Proceed as in Example 4, however the pressure ratio was 2. Yield = 5 kg of polymer per g Ten for 6 hours.

MFI = 2.8.