The method of obtaining ultra-high molecular weight polyethylene

 

(57) Abstract:

The invention relates to methods of producing ultra-high molecular weight polyethylene (UHMWPE), synthesized in powder form in the conditions of suspension polymerization of ethylene in the environment of a hydrocarbon diluent at temperatures of 40-70oWith the use of supported catalysts ziperovich type. The invention solves the task of getting the UHMWPE powder with high bulk density when carrying out the polymerization at a temperature of 50-60oWith the desired high molecular weight. The essence of the invention consists in carrying out polymerization upon receipt of UHMWPE in two stages, with the first stage (terpolymerization) process is carried out at a temperature of 70-80oC and a pressure of 3 ATM ethylene and contact time of 20 min, and the second stage bulk polymerization is carried out at a lower temperature of 60oC and a pressure of 3 ATM ethylene. Carrying out polymerization by the proposed method allows to obtain a powder of UHMWPE at temperatures of 50-60oWith increased bulk density, while maintaining the required values of the molecular weight of UHMWPE (> 3 106). table 2.

The invention relates to methods of producing the polarization of the ethylene in the environment of a hydrocarbon diluent at temperatures of 40-70oC using supported catalysts ziperovich type.

The most important characteristic of UHMWPE is its molecular weight; under ultra-high molecular weight polyethylene is understood to mean a polymer with a molecular weight M > 1106many applications require UHMWPE with molecular weight of > 3106. Another important characteristic of the UHMWPE powder is its morphology (particle size, distribution of particle size and bulk density of the powder). For most applications of UHMWPE required powders with an average particle size in the region of 100-200 microns, a narrow distribution of particle size and high bulk density of the powder in the region of 350-450 g/L.

The molecular weight of UHMWPE and its morphology depends on many parameters and primarily on the composition and morphology of the used catalyst. For UHMWPE, the most widely used catalysts ziperovich type, in particular high level applied catalysts ziperovich type.

For example, in U.S. patent N 4962167, MKI5C 08 F 4/654, 1990, describes a method for UHMWPE deposited on the catalyst, which is the product of interaction of magnesium dichloride (medium) with Tetra is the catalyst in the 70oC get the UHMWPE powder with a characteristic viscosity = 16,6 DL/g, a bulk density of 340 g/l and an average particle size of 245 μm.

In U.S. patent N 4972035, MKI5C 08 F 2/14, 1990, describes a method for UHMWPE powder and ultrafine particle size (average particle size less than 80 microns). For this purpose, the catalyst obtained by the interaction of a solution of a complex of magnesium chloride with alcohol with titanium tetrachloride in the presence of ethylbenzoic. In the polymerization of ethylene on this catalyst at a temperature of 70oC get the UHMWPE powder with a characteristic viscosity = 23 DL/g, an average particle size of 26 μm and a bulk density of 280 g/l

A significant influence on the molecular weight and morphology of UHMWPE are also conditions of the polymerization process, in particular the temperature of polymerization. When using supported catalysts ziperovich type to obtain UHMWPE polymerization of ethylene is usually carried out at temperatures no higher than 70oC. it is Known that the molecular weight of the polyethylene increases, when the temperature of polymerization, therefore, to obtain UHMWPE with molecular weight of more than 3106it is necessary to conduct the polymerization at dost is unwanted effects. In particular, this reduces the catalyst activity. We also found that when the temperature of polymerization of the 70oC to 50oC decreases the bulk density of the powder of UHMWPE. This result is illustrated by the data of examples 1-3 (table. 1). It is seen that, when the temperature of polymerization of the 70oC to 50oC bulk density of the powder of UHMWPE is markedly reduced (from 420 to 320 g/l). While UHMWPE with the desired molecular weight (3106) is formed only at temperatures above 60oC, however, the bulk density of the powder of UHMWPE obtained at temperatures 60-50oC, significantly lower than the polymerization temperature of 70oC.

UHMWPE can be obtained with the use of supported catalysts ziperovich type, prepared by different methods and having different composition and morphology.

Closest to the present invention is a method for UHMWPE, described in the patent of Russian Federation N 2064836, MPK7 B 01 J 31/38, 10.08.96. According to example 10 of the patent to obtain UHMWPE use caused the catalyst prepared by the interaction of the solution magyarkanizsa connection structure MgPh2nMgCl2mR2O, where n = 0.37 to 0.7 and the m and allows you to get the UHMWPE powder with an average particle size of 150 μm, a narrow distribution of particle size, bulk density of 380 g/l and a molecular weight 1,8106(the temperature of polymerization of the 70oC). A disadvantage of the known solutions is the inability to obtain polyethylene with high bulk density when carrying out the polymerization at a temperature of 50-60oC.

The invention solves the task of getting the UHMWPE powder with high bulk density when carrying out the polymerization at a temperature of 50-60oC, with the desired high molecular weight.

In the literature it is well known that the initial conditions of the polymerization significantly affect the morphology of the powder polyethylene and polypropylene, in particular the bulk density of the polymer powder [F. J. Karol et. al., New catalysis and process for ethylene polymerization, Advances in Polyolefins, Plenum Publ.Corp., 1987, p.p.337-353; L. L. Bohm, et. al. The Microreactor as a Model for the Description of the Ethylene Polymerization with Heterogeneous Catalysts in transition Metals and Organometallics as Catalysts for Olefine Polymerization, Springer-Verlag, 1988, p.p.391-403; G. A. H. Nooijen, On the Importance of Diffusion of Cocatalyst Molecules Through Heterogeneous Ziegler/Natta Catalysts, Eur. Polym. J., 30, N 1, 1994, p.p. 11-15; G. A. H. Nooijen Ziegler/Natta catalysts in particle form ethylene polymerization: The effect of polymerization start-up on catalyst activity and morphology of the produced polymer, Catalysis Today, 11, 1991, p.p.35-46; Q. Wu et. al. Homo - and copolymerization of ethylene with prepolymerized Ti-Mg supported catalyst, Makromol.Chem., The Rapid Scsii in many cases, introducing preliminary polymerization (terpolymerization), held in conditions that differ from the main polymerization. Holding terpolymerization most widely accepted for the case of gas-phase polymerization of ethylene and propylene Patents of the Russian Federation N 2114125, C 08 F 10/00, 1998; N 2043150, B 01 J 37/00, 1995; N 2051923, C 08 F 10/02, 1996; N 2108344, C 08 F 210/02, 1998]. Terpolymerization carried out at lower temperatures (20-40oC) and a lower pressure compared to the main polymerization, which is carried out at temperatures 70-110oC. We have tested these conditions terpolymerization upon receipt of the UHMWPE powder and found that these modes of carrying out terpolymerization not allow to increase the bulk density of the powder SVPMA obtained at temperatures of 50-60oC. moreover, we have unexpectedly found that the desired result is an increase in the bulk density of the powder of UHMWPE is achieved by completely different conditions of terpolymerization, namely during the initial stage of polymerization (terpolymerization) at a higher temperature than the temperature of the main phase polymerization. According to our results the desired effect - the increase in the bulk density of the powder of UHMWPE while maintaining ultra-high molecular weight is achieved, if terpolymerization carried out at mnost of the present invention is to carry out polymerization upon receipt of UHMWPE in two stages, moreover, in the first stage (terpolymerization) process is carried out at a temperature of 70-80oC and a pressure of ethylene of 3 atmospheres and a contact time of 20 min, and the second stage bulk polymerization is carried out at a lower temperature of 60oC and a pressure of ethylene of 3 ATM.

The main distinguishing feature of the invention is the higher temperature at the stage of terpolymerization (70-80oC) compared to the temperature during the main stage of polymerization.

Examples 1-3 illustrate the effect of polymerization temperature on the properties of SVPMA. The data are shown in table 1.

Example 1.

Caused the catalyst was prepared according to the method described in the patent of Russian Federation N 2064836 (example 4). The carrier for the catalyst obtained by the interaction magyarkanizsa connection structure MgPh2of 0.5 MgCl2located in the solution mixture of chlorobenzene and dibutylamino ether with carbon tetrachloride at a temperature of -5oC and a molar ratio of CCl4/Mg = 2. The catalyst was prepared by processing a medium titanium tetrachloride at a temperature of 60oC and a molar ratio of TiCl4/Mg = 1. The resulting catalyst has an average particle size of 6.5 μm and contains 2.3 wt.% Ti.

Polymerization attitiude shirt. The polymerization is carried out in an environment of heptane (250 ml) at a temperature of 70oC and a pressure of ethylene of 3 ATM for 1 hour; socialization triisobutylaluminum (CHIBA) with a concentration of 5 mmol/L. Using 0.01 g of catalyst, obtain 110 g of a powder of UHMWPE. The polymer yield is 11 kg/g cat. The obtained powder of UHMWPE has a bulk density of 420 g/L. the Characteristic viscosity of the polymer, defined in decaline at 135oC is 11 DL/g, which corresponds to the molecular weight of the polymer 1,6106.

Example 2.

Using the catalyst of example 1. Polymerization of ethylene was carried out analogously to example 1, except that the polymerization temperature is 60oC.

Get 65 grams of powder of UHMWPE; the polymer yield is 6.5 kg/g cat. The obtained powder of UHMWPE has a bulk density of 370 g/l of the Characteristic viscosity of the polymer is 23 DL/g, which corresponds to the molecular mass 4,5106.

Example 3.

Using the catalyst of example 1. Polymerization of ethylene was carried out analogously to example 1, except that the polymerization temperature is 50oC and a pressure of 6 ATM ethylene.

Get 50 g of the powder of UHMWPE; the polymer yield is their the essence of the invention.

Example 4.

Using the catalyst of example 1. Polymerization of ethylene was carried out analogously to example 1, but with the following changes.

Using 0.07 g of catalyst; socialization - triethylaluminium (tea) with a concentration of 5 mmol/l, a pressure of 6 ATM ethylene. The polymerization is carried out in two stages. The first stage (terpolymerization) is conducted at a temperature of 80oC, a pressure of ethylene of 3 ATM for 5 minutes and Then the temperature of polymerization is reduced to 60oC, and the pressure of ethylene is increased to 6 ATM and conduct the polymerization under these conditions for 1 hour. Obtain 112 g of powder of UHMWPE; the polymer yield is 16 kg/g cat. The obtained powder of UHMWPE has a bulk density of 430 g/l

Example 5.

Using the catalyst of example 1. The polymerization of ethylene is carried out in two stages as in example 4, except that at the stage of terpolymerization temperature is 70oC.

Obtain 91 g of powder of UHMWPE; the polymer yield is 13 kg/g cat. The obtained powder of UHMWPE has a bulk density of 420 g/l

Example 6.

Using the catalyst of example 1. The polymerization of ethylene is carried out in two stages as in example 4, except that the 70oC.

Obtain 84 g of powder of UHMWPE; the polymer yield is 12 kg/g cat. The obtained powder of UHMWPE has a bulk density of 410 g/L. the Characteristic viscosity of the polymer is 23 DL/g, which corresponds to the molecular mass 4,7106.

Example 7.

Using the catalyst of example 1. The polymerization of ethylene is carried out in two stages as in example 4, except that the polymerization temperature in the second stage is 50oC.

Get 56 grams of powder of UHMWPE; the polymer yield is 8 kg/g cat. The obtained powder of UHMWPE has a bulk density of 390 g/L. the Characteristic viscosity of the polymer is 25 DL/g, which corresponds to the molecular mass 5.3106.

Thus, the results of examples 4-7 (table. 2) show that polymerization of the proposed method allows to obtain a powder of UHMWPE at temperatures of 50-60oC with high bulk density, while maintaining the required values of the molecular weight of UHMWPE (> 3106).

The method of obtaining ultra-high molecular weight polyethylene using the deposited catalyst ziperovich type containing a chloride of titanium on superfine chloride mA is terpolymerization carried out at a temperature of 70-80oWith the pressure of ethylene of 3 ATM and a reaction time of 20 min, and the main polymerization is at a temperature of 60oC and a pressure of 3 ATM ethylene.

 

Same patents:

The invention relates to methods of producing polymers-olefins, effectively reducing the hydrodynamic resistance of hydrocarbon liquids and can be used for transporting petroleum products in pipelines

The invention relates to a multistage process for the polymerization of olefins of the formula CH2= CHR where R is hydrogen or alkyl, cycloalkyl or aryl group with 1-10 carbon atoms), carried out in two or more reactors

- olefins and method of reception" target="_blank">

The invention relates to precatalytic compositions suitable for Homo - and copolymerization of olefins and to a method for producing such composition precatalytic

The invention relates to precatalytic component of the catalytic composition of the Ziegler-Natta, suitable for the production of polymers of ethylene

The invention relates to a ball of solid catalytic components for the polymerization of olefins containing compound of titanium deposited on a magnesium halide containing more than one relationship Ti-halogen and, optionally, containing groups other than halogen, in the amount of less than 0.5 mol per 1 mol Ti
The invention relates to a method for producing polyethylene by the method of radical polymerization under high pressure and can be used in the chemical and petrochemical industry

The invention relates to the disproportionation of unsaturated acids in rosin, tall oil, or a mixture thereof and can be used in the manufacture of synthetic rubber emulsion polymerization to obtain emulsifiers

The invention relates to the disproportionation of unsaturated acids in rosin, tall oil, or a mixture thereof and can be used in the manufacture of synthetic rubber emulsion polymerization to obtain emulsifiers

The invention relates to stapling protective colloids, method of polymerization ethanobotany monomers with the use of stitched protective colloids, as well as to get their assistance to the polymers, respectively dispersions of polymers and their application

The invention relates to a method of radical (co)polymerization of Monomeric vinyl ether, vinylchloride, diene, Acrylonitrile, and-optional olefin with one or more monomers Ethylenediamine

The invention relates to the production of polymers, the synthetic rubber industry, namely the method of production of ethylene-propylene or ethylene propylene-diene copolymer and device for its implementation

The invention relates to the production of polymers, the synthetic rubber industry, namely the method of production of ethylene-propylene or ethylene propylene-diene copolymer and device for its implementation

The invention relates to compositions of (co)polymer of olefins and method of reception and catalyst for (co)polymerization of olefins and method thereof
Up!