DE1445303A1 - Process for the production of polyethylene - Google Patents

Description

Process for the production of polyethylene Addition to patent (application C 16 784 IVb / 39 c)

Subject of the patent. (Registration C 16 784 IVb / 39 c) is

a process for the production of polyethylene by low pressure polymerization with the help of mixed catalysts made from halogen-ortho-titanic acid esters on the one hand and organometallic compounds of aluminum on the other hand, expediently in the presence of diluents. This

Procedure is supported by the patents (application C 16 812 IVb / 39 c)

and (Application C 17 553 IVb / 39 c). by one

instead of the pure halogen-ortho-titanic acid esters, the crude, halogen- -ortho-titanic acid ester containing reaction products of titanium tetrahalide used with organic compounds containing hydroxyl groups or with orthotitanic acid esters. Another further training, namely the ripening of the mixed catalysts before the polymerization in a relatively concentrated solution at elevated temperature

Subject of the patent (registration C 19 197 IVb / 39 c). That

Molecular weight of the polymers can according to patent. .,. ... (Application C 19 621 IVb / 39 c) by adding hydrogen to the gaseous olefin and / or according to the patent. .,. ... (Registration C 19 999 IVb / 39 c) can be regulated and in particular reduced by adding hydrogen and hydrogen chloride to the gaseous olefin. The polyethylenes produced by this process are characterized by their linear structure and, associated therewith, a high degree of crystallinity and are therefore better suited for numerous purposes than the products produced by previously known processes. Can be used for the production of very large injection molded parts

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INSPECTED

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however, the high crystallinity and warping of the disturbing effect Justify molded parts.

It has been found that one can use the process for the manufacture of polyethylene according to patent (application C 16 784 IVb / 39 c)

Low pressure polymerization of ethylene with the help of mixed catalysts from halogen-ortho-titanic acid star on the one hand and organometallic compounds of aluminum on the other hand, expediently in The presence of diluents can advantageously develop further if an ethylene is used that contains 0.05 to 20 percent by volume of propylene and / or a-butylene and optionally 0.01 to 30 percent by volume Contains hydrogen,

Preference is given to using ethylene with 0 _s 2 to 10 percent by volume of propylene or else a-butylene. The hydrogen content, which serves to reduce the molecular weight, is expediently within the limits of 0.1 to 5 percent by volume.

The polymerization takes place in a manner known per se by one or Passing the ethylene mixture into or over the mixed catalyst containing inert diluents. Used as mixed catalysts the reaction products of halogen-ortho-titanic acid esters, such as monochloro-ortho-titanic acid-tri-methyl-, -ethyl-, -η- or -iso-propyl -n- or -isobutyl ester, dichloro-ortho-titanic acid-dimethyl-, -ethyl-, -n- or -iso-propyl-, -n- or -iso-butyl ester and trichloro-ortho- -titanic acid alkyl ester, on the one hand, and organometallic compounds of aluminum, such as diethyl or diisobutyl aluminum monochloride. Ethyl or isobutyl aluminum sesqui- or di-chloride, on the other hand, the aluminum compound to the titanium compound in a molar ratio from 0.1 to 10 to 1 and preferably in a molar ratio of 0.5 up to 5 to 1 is used. The amount of mixed catalysts, based on to 1000 parts by weight of diluent, is usually 0.5 to

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10 parts. The polymerization can take place without pressure, at a slight negative pressure down to about 0.5 atm or even at overpressure up to about 20 atm. Normal pressure is usually sufficient. The polymerization temperature is between - 20 and + 200 ⁰ C, preferably between 20 and 100 ⁰ C. During the polymerization, it is convenient to keep the polymerization by suitable stirring devices or by circulation of the reaction gas in motion. The polymerization can be carried out either in individual batches or continuously. It is advisable to choose the polymerization conditions so that all of the polymerizable components of the ethylene mixture polymerize in one pass through the polymerization batch. A constant ratio of ethylene to propylene or butylene is achieved in the resulting polymer if, which is easy to achieve, the monomeric starting materials are added in a constant ratio.With continuous operation, it is also possible to circulate the ethylene mixture and only those claimed To supplement monomers.

The regulation of the degree of polymerization and molecular weight and In particular, it can be reduced in a simple manner by the hydrogen content of the ethylene mixture. With continuous How it works, it is possible to control the hydrogen level in the circuit, which is usually higher than the hydrogen level originally used Ethylene mixture, to be kept constant.

The heat of polymerization is generated by external cooling with suitable coolants, like water, and / or also by evaporative cooling, d. H. by evaporation of the present in the polymerization, in the Polytnerization temperature boiling diluents ^, such as butane, Pentane, hexane, mixtures of aliphatic hydrocarbons as described in the gasoline fractions of the petroleum are present, also cyclohexane or benzene, discharged.

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The polymerization is carried out in a known manner after completion by destroying the mixed catalysts by means of a suitable decomposition agent terminated, in the case of discontinuous polymerization, as a rule, when the batch is no longer sufficiently mixed can be. Working up is carried out in a known manner by washing out the mixed catalyst residues with alcohols, water, with aqueous or alcoholic acids or alkalis or treatment with, complexing compounds, etc. and then filtering off or spinning and drying.

The polymers obtained differ from those mentioned above Patents manufactured products have a higher methyl group content. According to the UR spectroscopic determination of fractions obtained by solution or precipitation fractionation, these are largely around copolymers of ethylene with propylene and / or a-butylene. Surprisingly, these copolymers still have a very narrow molecular weight distribution. This is the reason for the very good application properties of the products like them can be seen from the following examples.

example 1

In a stirrer-equipped reaction vessel C and constant stirring, to a L ^J are dissolution of 4.95 parts by weight of ethyl aluminum sesquichloride in 100 parts by volume of isopropyl cyclohexane (IPCH) 50 parts by volume of a Chlortitansäureesterlösung in IPCH under dry nitrogen at 3O ^{0 is} given, the äquiniolarer quantities by mixing 1 molar titanium tetrachloride and titanium tetra-isobutylatlösung and 2 hours of heating at 60 ⁰ C and then diluting with IPCH to a concentration of 0.4 mol Ti / l is prepared. The nitrogen N _ac h 15 minutes of induction time at 30 ^e C is diluted with 1100 Volumteilefn IPCH and heated to 65 "C. By Äthylenstrom that contains 0.25 percent by volume propylene / is displaced from the apparatus. Then, the exhaust pipe is blocked, and so much hydrogen gassed that in the gas phase

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24 percent by volume are included. The stirring speed is then regulated such that 835 parts by volume of the ethylene containing 0.25 percent by volume of propylene enter the reactor per minute. The polymerization temperature is removed by external cooling and the temperature is kept at 65 ° C. After a polymerization time of 3 hours, the catalyst is decomposed by adding 200 parts by volume of butanol. The polymer is worked up in a known manner with methanol or water or mixtures thereof. After drying, 180 parts by weight of a white powder are obtained with the reduced viscosity (RSV - measured in 0.1% p-xylene solution at 110 ^° C.) of 1.19, the density: 0.9 496 and the molecular non-uniformity 1.7 (solution fractionation: -rr— - 1 - ■ ■ - 1). The absorptions of the IR spectrum

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suggest the presence of <0.02 intermediate trans, 0.13 vinyl and 0.07 vinylidene double bonds per 1000 carbon atoms and I ₃ 3 methyl groups per 100 -CH- (according to SlowinsM), from the polymer produced press plates show the following application technology

ο see test data: flow strength 263 kg / cm, flow elongation: 17 %, tear strength

2

strength: 178 kg / cm, elongation at break: 818%, notched impact: 6., 2 cmkg / cm and melt index (J): 19.1 (according to ASTM standard D 1238-52 T, but with a load of 5 kg instead of 2.16).

Example 2

According to the procedure of Example 1 are propylatlösungen titanium tetra-in-filled with dry nitrogen apparatus at 3O ⁰ C to a solution of 4.95 parts by weight of ethyl-aluminum-sesquiehlarid in 130 parts by volume of IPCH 20 parts by volume of a molar 1 by mixing titanium tetrachloride and "optionally C prepared solution, and stirred for 15 minutes at 30 ⁰ C. The concentrated mixed catalyst suspension is diluted by adding 1100 parts by volume IPCH and at 50" in IPCH heated at 60 C. The nitrogen is displaced by a vigorous gas stream of ethylene, to which 2 percent by volume of propylene has been added. Then the exhaust pipe is closed and enough hydrogen is gassed in until the gas phase contains 19 percent by volume. Afterward

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the stirring speed is regulated so that 835 parts by volume of the gas mixture of ethylene with a propylene content of 2 percent by volume enter the reactor. The polymer temperature is kept at 5 (TC) by external cooling. After a polymerization time of 3 hours, the polymerization is initiated by decomposition of the mixed catalyst terminated with 50 parts by volume of η-butanol. After working up in the usual Thus, about 170 parts by weight of white polymer are obtained reduced viscosity RSV = 1.12 and the molecular non-uniformity

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ability 1.5 (solution fractionation -rj— - 1 = ■ ■ ■■ - I) ₁ that after the

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IR analysis <0.02 intermediate trans, 0.03 vinyl and 0.02 vinylidene double bonds per 1000 C atoms and 5.9 methyl groups per 100 -CH ₀ - (according to SlowinsM) corresponding to 1.5 methyl groups per 100 C. - Contains atoms according to the compensation method. Press plates made from them show the following application test values! Yield strength:

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207 kg / cm, yield elongation! 23%, tear strength: 162 kg / cm, tear strength

2 elongation: 633%, notched impact 8.7 cm kg / cm and melt index (J '): 19.2,

Example 3

Proceed as described in Example 1, but instead 0.25 percent by volume propylene 2.5 percent by volume cx-butylene used, in this way, after a polymerization time of 2.5 hours, approx. 150 weight is obtained share white polymer of reduced viscosity RSV = 0.90, which according to the IR analysis 0.04 intermediate trans, 0.09 vinyl and 0.04 Vinylidene double bonds per 1000 carbon atoms and 4.0 methyl groups per 100 -CH- (according to Slowinski) contains. Press plates produced therefrom show the following application-technical test values:

2

strength: 182 kg / cm, yield elongation: 27%, tensile strength: 101 kg / cm., elongation at break: 92%, notched impact; 7.1 cm kg / cm " ¹ and melt index (J-): over 70.

Claims (1)

Claim Further development of the process for the production of polyethylene according to Patent (application C 16 784 IVb / 39 c) through low-pressure 809811/1048 - ⁷ - OZ 1462 27. 7, 61 Polymerization of ethylene with the help of mixed catalysts made from halogen-ortho-titanic acid esters on the one hand and organometallic esters On the other hand, compounds of aluminum, expediently in the presence of diluents, characterized in that an ethylene is used which contains 0.05 to 20 percent by volume of propylene and or or α-butylene and optionally 0.01 to 30 percent by volume hydrogen contains. 809811/1048