FI62847C - FOERFARANDE FOER FRAMSTAELLNING AV SUPERHOEGMOLEKYLAER POLYETYLEN - Google Patents

Description

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_. . . . ^ (44) Nihtivilcal panon fa k (mL) unui * un pvm. -. fto PMMtt · ech registerstyrelsen '1 AnsMnn «idagd od» wtl.akrtfnn puMkend 30.H.Ö2 (32) (33) (31) P) 7 * «** r« * »011» «« - Bejird priorttst (71 ) (72) Nina Nikolaevna Severova, ulitsa Tambovskaya 67, kv. 12, Leningrad,

Anatoly Dmitrievich Pechenkin, ulitsa Dimitrova 15, building 2, sq. Km. 111, Leningrad, Svetlana Alexandrovna Shibalovskaya, Prospekt Maklina 38, sq. Km. 11, Leningrad, Elena Veniaminovna Veselovskaya, Vladimirsky Prospekt 8, sq. Km. 17, Leningrad, Zinaida Vladimirovna Arkhipovs ·, B. Porokhovskaya ulitsa 5 ^ / 1, kv. 210, Leningrad, Vladimir Vladimirovich Khodarkevich, Prospekt Stachek, 120, sq. Km. 1 * 5, Leningrad, Vladimir Filimonovich Vasilenko, ulitsa Rubinshteina, 11, kv. lh, Leningrad, Valentina Vasilievna Mischuk, Brjusovskaya ulitsa 12, kv. lU, Leningrad, Jury Nikolaevich Kolesnikov, ulitsa Abaya ll + -a, kv. 19, Guriev,

Jury Ivanovich Dzhulgakov, ulitsa Abaya lU-a, kv. 17, Guriev, USSR (SU) (7I *) Oy Kolster Ab (5 **) Method for producing overweight molecular weight polyethylene - Förfarande för framställning av superhögmölekylär polyethylene

The present invention relates to a process for the production of polyethylene and in particular to a process for the production of overweight molecular weight polyethylene.

Polyethylene with an overweight molecular weight (average molecular weight 2-3 million) can be used in the paper industry to make water sheets and lids for suction boxes, in the textile industry in the manufacture of rolls, in the chemical industry and in medicine.

A process is known in the art for preparing overweight molecular weight polyethylene by polymerizing ethylene in an aliphatic hydrocarbon solvent at a temperature of 50 to 80 ° C at a pressure of up to 10 atmospheres in the presence of a catalyst consisting of 2,62847 alkylaluminum constituents: As the alkylaluminum component, trilacylaluminum AIRg is used, in which R is an alkyl radical having 1 to 20 carbon atoms, preferably 2 to 12 carbon atoms, or a compound of formula AIR2X in which X is a patient, OCH3 or OC2Hg and R is as defined above.

The use of the above prior art process in such high molar ratios of the alkylaluminum component to titanium tetrachloride results in a significant catalyst consumption rate, resulting in an increased ash content of the polymer and increased manufacturing costs.

It is an object of the present invention to obviate the above drawbacks of the prior art.

The present invention is directed to the formation of a modified composition of a kcfcalite system for a process for the production of overweight molecular weight polyethylene, which allows the consumption of catalyst to be reduced and the quality of the product to be improved.

According to the present invention, the present invention is based on the process of a compound of formula AIR2X (I) and a compound of formula A1 (OR) RX (II) wherein R is (^ H), C3H7, iC2Hg; X is (^ Hj-, C3H2, i-Cl4Hg, H used in a molar ratio 15: 1 to 1: 1, respectively, and said alkylaluminum component and titanium tetrachloride are used in a molar ratio of 1: 1 to 2: 1, respectively.

In the preparation of overweight molecular weight polyethylene having an average molecular weight of about 3,000,000, it is preferred to use a mixture of compounds of formulas (I) and (II) in a molar ratio of 10: 1 to 5: 1, respectively, to prepare parts for use in the paper industry.

A polymer suitable for medical use, i.e. Whereas, for the preparation of a polymer with a reduced ash content and an increased whiteness, it is preferable to use as a alkylaluminum component a mixture of a compound of formula (I) in which 3 62847 R is C2Hg, C8H2, wherein R and X are the same groups.

The process of the present invention for producing overweight molecular weight polyethylene is performed as follows.

The production of overweight molecular weight polyethylene (having a molecular weight greater than 1,000,000) is carried out by polymerizing ethylene by a metal pressure process in the presence of a Ziegler-Natta catalyst. The polymerization of ethylene is carried out in an aliphatic hydrocarbon solvent such as naphtha, hexane, heptane at a temperature of 50 to 80 ° C at a pressure of up to 10 atmospheres. The catalyst used is a mixture of titanium tetrachloride and organoaluminum compounds of formulas A1R2X and A1 (OR) RX in a ratio of 15: 1 to 1: 1, respectively, wherein R is O2Ης, CgHy, i-C4Hg; X is C 2 H 2, C 8 H 6, i-C 2 H 9, H. The molar ratio of the alkylaluminum component to titanium tetrachloride ranges from 1: 1-2: 1.

Surprisingly, a molar ratio of A1R2X: A1 (0R) RX of greater than 15: 1 when used in the above conditions in the polymerization of ethylene gives polyethylene having a molecular weight of not more than 600,000 to 800,000.

By reducing the modal ratio A1R2X: A1 (0R) RX to less than 1: 1, the activity of the catalyst system during polymerization decreases, i. the yield of polymer per gram of catalyst decreases.

It is preferred to use a mixture of trialkylaluminum or dialkylaluminum ihydrides with their alkoxy derivatives in a ratio of 10: 1 to 5: 1, respectively. By reducing the molar ratio of the alkylaluminum component to titanium tetrachloride to less than 1: 1, no excess molecular weight polyethylene is obtained in production (the molecular weight of the polymer obtained is at most 500,000 to 700,000).

Excess molecular weight polyethylene is obtained when said ratio is not less than 1: 1. By increasing the molar proportion of the alkylaluminum component above 2: 1, the molecular weight no longer increases substantially even as the ash content of the polymer increases and the commercial appearance deteriorates.

The highest activity is characteristic of catalyst complexes based on dialkylaluminum hydrides of the formula A1R2H in mixtures with the alkoxy derivatives of the formula A1 (OR) RH, where R is -I-C2Hg. High molecular weight polyethylene prepared in the presence of these compounds is characterized by strong whiteness and low ash content.

The polymerization catalyst is prepared in a complexing medium to which said ingredients are continuously fed at predetermined rates. Mixing temperature is 20-30 ° C, mixing time 10-15 minutes. The catalyst complex thus prepared is continuously fed to a reactor into which ethylene is continuously fed.

The resulting polyethylene suspension is continuously removed from the reactor. Separation of the polymer from the reaction medium and its purification from the catalyst residues is carried out either by means of an alcohol-benzene mixture or by washing with water, usually using existing plants for the production of low-pressure polythene.

The properties of polyethylene prepared in the presence of the above catalyst are as follows: 1. Molecular weight of 1,000,000 or more (determined by the critical melt flow or melt index of the polymer, g / 10 min at 190 ° C with a load of 21 kp).

The critical melt index of this polymer is 0.04-0 g / 10 min.

2. The density is 0.94 to 0.95 g / cm 3.

3. High strength (breaking stress at rupture 6 is 32o-420 kp / cm2).

4. The relative elongation is 400-600%.

5. The ash content is 0.05 to 0.01%.

Furthermore, this polymer is characterized by high impact strength, the ability to resist cracking under load in a corrosive and humid medium at elevated temperatures, the ability to resist abrasion and can be used at temperatures in the range of -200 ° C to + 120 ° C.

The present invention uses a catalyst in which the ratio of organoaluminum compound to titanium tetrachloride is 2: 1, which makes it possible to reduce the consumption of the alkylaluminum compound to one-seventh and the consumption of titanium tetrachloride to one-fourth of the prior art methods. In addition, the processability of ethylene during polynerization is improved, the ash content of the polymer is reduced by 0.01% by weight and the commercial appearance of the product is improved.

In order that the present invention may be better understood, the following are some specific examples which illustrate a process for preparing an excess molecular weight polyethylene.

Example 1

Gasoline is continuously fed to a steel, column-type, 60-liter reactor with a catalyst complex prepared in advance in a complexing unit. The feed to it for this purpose is 15 g / h TiCl 2, 4.05 g / h Al (C 2 H 5) and 4.95 g / h Al (O 2 H 2) (C 2 H 5) 2.

The complexation temperature is 25 ° C.

The complexation time is 10 minutes. The molar ratio of the alkylaluminum component to titanium tetrachloride is 1: 1, the molar ratio of A1 (CO 2): Al 1 b (O 2 H 2) (C 2 H 2) 2 is 1: 1. The obtained catalyst complex is fed continuously at a rate of 30 l / h.

Ethylene is introduced into the reactor at a rate of 3 kg / h. The polymerization is carried out at a pressure of 3 atmospheres and a temperature of 65-70 ° C. The resulting polyethylene suspension is continuously removed from the reactor.

The yield of polyethylene is 2.8 kg / h or 311 g / g.h of the alkylaluminum component or 116 g / g.h of the total catalyst. The polyethylene thus obtained has a molecular weight of 2,300,000.

Example 2

Excess molecular weight polyethylene is prepared as described in Example 1.

As the alkylaluminum component, a mixture containing AKC (H 2) 2 and Al (O 3 H 3) (C 3 H 2) 2 in a molar ratio of 3: 1 is used. The molar ratio of the alkylaluminum component to titanium tetrachloride is 1: 1.

To prepare the catalyst, 15 g / h TiCl 4, 3.6 g / h Al (C 3 H 7) 3, 1.32 g / h Al (O 3 H 3) (C 3 H 2)? Are fed to the complexing unit.

The yield of polyethylene is 2.3 kg / h or 218 g / g.h of the alkyl component or 98.5 g / g.h of the total catalyst.

Example 3

Excess molecular weight polyethylene was prepared as described in Example 1.

As the alkylaluminum component, an ee containing Al (i-cl + Hg) 3 and Ali-C (Hg) (i-C4Hg) 2 in a molar ratio of 15: 1 is used. The molar ratio of the alkylaluminum component to titanium tetrachloride is 2: 1. To prepare the catalyst, the complexing unit is fed with 15 g / h TiCl 4, 29.2 g / h AKi-C ^ Hgg and 2.09 g / h Al (i-C ^ Hg) (i-C The yield of polyethylene is 3.03 kg / h or 162 g / g.h based on the alkylaluminum component or 71.3 g / g.h based on the total catalyst.

The polyethylene thus obtained has a molecular weight of 1,100,000.

6 62847

Example 4

Excess molecular weight polyethylene is prepared as described in Example 1 above.

The polymerization is carried out at a pressure of 1 atmosphere and a temperature of 80 ° C.

As the alkylaluminum component, a mixture containing Al (C 2 H 2 O 2 H and Al (C 2 H 2) 2 (C 2 H 2 -) H in a molar ratio of 5: 1 is used.

To prepare the catalyst, 12 g / h TiCl 4, 8.9 g / h Al (C 2 H 5) H and 2.02 g / h Al (OC 3 H 5> (C 2 II 5) M are fed to the complexing unit.

The yield of polyethylene is 3.0 kg / h or 275 g / g.h based on the total catalyst.

The polyethylene thus obtained has a molecular weight of 1,100,000.

Example 5

Polyethylene having an oversized molecular stack is prepared as described in Example 1.

The polymerization is carried out at a pressure of 3 atmospheres and a temperature of 55 ° C in n-hexane.

The alkylaluminum component is used in a mixture of Al (i-Cl + Hg) 2H and Al (i-C2H0) (i-C The molar ratio of the alkylaluminum component to titanium tetrachloride is 2: 1. To prepare the catalyst, 12 g / h TiCl 4, 13.2 g / h Al (iCl 2 HgigH and 1.49 g / h Al (1-C 2 HgO) (1-C 2 Hg) H are introduced into the complexing unit. The yield of the polyethylene thus obtained is 3.5 kg / h or 239 g / g of alkylaluminum component or 209.7 g / gh of total catalyst.

Polyethylene has a molecular weight of 1,800,000.

Example 6

Excess molecular weight polyethylene is prepared as described in Example 1.

The polymerization is carried out at a pressure of 10 atmospheres and a temperature of 70 ° C.

As the alkylaluminum component, a mixture of AKCl 2 H 2 H and Al (O 2 H 2 -) (O 2) H is used in a molar ratio of 3: 1.

The molar ratio of the alkylaluminum component to titanium tetrachloride is

To prepare the catalyst, 13 g / h TiCl 4, 5.3 g / h Al 2 H 2 H and 2.0 g / h Al (O 2 Cl 2) H are fed to the complexing unit. The yield of polymer is 3.3 kg / h or 2.030 g / g.h alkylaluminum component3 or 671 g / g.h per total catalyst.

The resulting polymer has a molecular weight of 1,400,000.

Claims (3)

7 62847 A process for preparing polyethylene having an excess molecular weight of more than 1 x 10 4 by polymerizing ethylene in an aliphatic hydrocarbon solvent at a temperature of 50 to 80 ° C and a pressure of up to 10 atm in the presence of a catalyst consisting of an alkyl aluminum component and titanium tetrachloride, characterized in that consists of compounds of formula (I) AlI-X and formula (II) Al (OR) RX, wherein R is C2H, -, C3H7 'i-C4H9' x is C2H5 'C3H7, iC2Hg, H, in a molar ratio of : 1 and 1: 1 and that the molar ratio of the alkylaluminum component to titanium tetrachloride is between 1: 1 and 2: 1. Process according to Claim 1, characterized in that a mixture containing the compounds of the formulas (I) and (II) in a molar ratio of between 10: 1 and 5: 1 is used as the alkylaluminum component. Process according to Claim 1 or 2, characterized in that the alkylaluminum component contains a compound of the formula (I) in which R is C 2 H, C 3 H 7 or C 1 H 9; X is H and a compound of formula (II) wherein R and X are as defined in formula (I).