The method of obtaining alpha-olefins of high molecular weight polymers

 

(57) Abstract:

The invention relates to a method for producing alpha-olefins of high molecular weight polymers in solution by polymerization of ethylene or mixtures of ethylene and at least one higher olefin C3-C12in the presence of a coordination catalyst, consisting of two components: the first contains Ti, Mg, Al, and the second mixture alkylamine and alkoxyalkane, when heated to 180-320oC, and the formation of the first and second catalyst components and their mixing is carried out in the stream at a temperature lower than the 30oC. the Method is simple and allows the use of catalysts with high activity at temperatures above 180oC. 8 C.p. f-crystals, 4 PL.

The present invention relates to a process and catalyst for polymers of ethylene, especially homopolymers of ethylene and copolymers of ethylene and higher alpha-olefins. In particular, this invention relates to a method of polymerization in solution to obtain such polymers, in which the process is operated at a temperature of at least 180oC and the catalyst is activated akoxicillin connection.

Polymers of ethylene, for example, homopolymers end use, for example in the form of films, fibers, injection molding or termoformovannyh products, coatings, pipes and the like.

There are two ways to obtain polyethylene, which include the polymerization of the monomers in an inert liquid medium in the presence of a coordination catalyst, namely those that operate at temperatures below the melting temperature or solubilize the polymer, and such, which operate at temperatures above the melting temperature or solubilize the polymer. The latter relate to processes in solution", an example of which is described in the patent Canada N 660869 A. W. Anderson, E. L. Fallwell and J. M. Bruce, published on 9 April 1963. The process solution is operated so that the monomer and the polymer dissolved in the reaction medium. Precise control of the degree of polymerization and hence the control of the molecular weight of the obtained polymer can be achieved by adjusting the reaction temperature.

The polymerization process in solution it is advantageous to carry out at very high temperatures, e.g. above 250oC, and use the heat of polymerization to remove solvent from the resulting solution of the polymer.

Although the process can be provided a stage for removing the polarization in solution stages without removal of the catalyst. Thus, the catalyst remains in the polymer. This catalyst, which will be called "residual catalyst, can give color to the obtained polymer and to cause decomposition of the polymer during processing. The amount of residual catalyst is due, at least partially, with a total activity of the catalyst used in the polymerization stage of the process, because, the higher the overall activity of the catalyst, the less is required of the catalyst for polymerization with acceptable speed. Therefore, catalysts with relatively high total activity are preferred in the processes of polymerization in solution.

In determining the total activity of the catalyst, the two important factors are the instant catalytic activity and stability of catalyst in the process conditions, especially at the operating temperature. Many of the catalysts which have been installed, are very active in the low-temperature polymerization processes, also exhibit high instantaneous activity at elevated temperatures used in the process in solution, but they tend to decompose in a very short time in the process which are of interest for industrial processes in solution. Other catalysts may have acceptable overall activity at elevated process temperatures in solution, but tend to give polymers with a broad molecular weight distribution, or too low in molecular weight so that they were useful for industrial production of a wide set of valuable products. Thus, the process requirements and characteristics of the catalyst of the polymerization process in solution are quite different from the requirements for catalysts for polymerization at a low temperature, which is obvious to experts in the field of technology.

Obtaining polymers of ethylene in the polymerization processes in the solution described in published on 14 November 1991 the patent application PCT N WO 91/17193 D. J. Gillis, M. C. Hughson and V. G. Zboril and in the related patent applications. The catalysts activated by siloxanes that can polimerizuet ethylene at very high temperatures. However, remnants of the siloxanes of these catalysts have a tendency to adversely affect the operation of the adsorbers used for cleaning solvent in the associated stages of the recovery and recycling of the polymerization process.

There is an extensive level is talization Ziegler-Natta for low temperature (below than 90oC) polymerization of ethylene and other alpha-olefins in order to increase the activity and/or stereospecificity catalyst. Esters of aromatic acids, for example towelboy or benzoic acid, ethers, and alcohols are often used for this purpose. However, the majority of electron donors that are applicable at low temperatures, inhibit the activity of the catalyst, which increases the temperature of polymerization. As an example of the use of electron donors in the U.S. patent N 4097659 H. M. J. C. Creemers et al on June 27, 1978 describes a low temperature polymerization process operating in an inert solvent at temperatures in the range of 20-100oC, in which a list of examples of activators include dimethylaminopropylamine, monetarypolicy chloride and monomethylethanolamine hydride.

As will be shown in subsequent examples, the substitution of even part trialkylamine on akoxicillin type used in U.S. patent N 4097659, leads to a significant reduction of catalytic activity, even if the temperature is only 130oC, that is, when the minimum temperature interval of operation of the polymerization process in solution. Now suddenly b is grown, and catalysts activated by akoxicillin, have a high activity at temperatures above approximately 180oC.

Accordingly the present invention provides an improved method of producing alpha-olefins of high molecular weight polymers in solution selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and higher alpha-olefins of C3-C12through polymerization of ethylene and/or mixtures of ethylene and higher alpha-olefins of C3-C12in the presence of catalytic amounts of titanium containing coordination catalyst in an inert solvent at a temperature of over 105oC. This improvement characterized in that:

(a) activate the catalyst solution alkoxyalkane in an inert solvent; and

(b) the process is operated at least partly, at a temperature of at least 180oC.

The present invention is also a method of obtaining alpha-olefins of high molecular weight polymers in solution selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and higher alpha-olefins of C3-C12moreover , this method includes p the alpha-olefins of C3-C12coordination catalyst and inert hydrocarbon solvent to a reactor, the polymerization of the specified monomer and the allocation of the thus obtained polymer, characterized in that the monomer is polymerized at a temperature in the range of 180-320oC, and referred to the coordination catalyst is formed from the first component and the second component, the first component containing titanium, and the second component are selected from the group consisting of akoxicillin and mixtures alkylamine and alkoxyalkane, and specified alkylamine has the shape AlRnX3-nand the specified alkoxysilane has the formula in which each R, R' and R" may be the same or different and independently selected from alkyl or aryl with 1 to 20 carbon atoms, X is halogen, n is 1-3 and m is 0-2.

In a preferred variant embodiment of the present invention R is alkyl of 2-8 carbon atoms and n = 3 and each of R' And R" is alkyl of 2-8 carbon atoms and m = 2.

In a variant embodiment of the method of the invention the second component is in the form of a mixture trialkylamine and alcohol in which the alcohol content is less than stekhiometricheskom an AlR33where each R3is an alkyl group having 1-10 carbon atoms and the alcohol has the formula R4OH, in which R4is alkyl or aryl with 1 to 20 carbon atoms, especially alkyl with 1-16 carbon atoms.

In another variant embodiment of the method, the first component consists of:

i) a mixture MgR12and AlR23in which each of R1and R2is the same or different and independently selected from alkyl groups having 1-10 carbon atoms;

ii) a reactive chloride component; and

iii) of titanium tetrachloride.

Alternatively, the first component can be obtained by rapid mixing of a solution of tetrachloride titanium, optionally containing oxytrichloride vanadium, with alyuminiiorganicheskikh connection, for example, trialkylaluminium or dialkylaminoalkyl at a temperature lower than the 30oC, and heating the resulting mixture to a temperature of 150-300oC for a period of 5 - 60 minutes

In an additional variant embodiment of the formation of the first and second catalyst components and their mixing is carried out in the stream at a temperature lower than the 30oC.

Infusion is emery intended for the manufacture of products by extrusion, injection molding, thermoforming, rotational molding, etc., In particular, polymers of alpha-olefins are homopolymers of ethylene and copolymers of ethylene and higher alpha-olefins, i.e. alpha-olefins of the ethylene series, especially such higher alpha-olefins which have from 3 to 12 carbon atoms, i.e. alpha-olefins of C3-C12, examples of which include 1-butene, 1-hexene and 1-octene. Preferred higher alpha-olefins have 4-10 carbon atoms. In addition, in the process with ethylene or a mixture of ethylene and alpha-olefin C3-C12may be involved cyclic endometreosis diene. Such polymers are known.

In the method of the present invention, a monomer, a coordination catalyst and inert hydrocarbon solvent, and optional hydrogen serves in the reactor system. The monomer may be ethylene or a mixture of ethylene and at least one higher alpha olefin C3-C12preferably ethylene or a mixture of ethylene and at least one higher alpha olefin C4-C10. Assume that alpha-olefins are hydrocarbons.

The coordination catalyst is formed from two components, namely, the first and second component. xymalos, valence is the ORGANOMETALLIC component of the type generally used in polymerization processes in solution. The first component may be in the solid phase. Examples of the first component of the above.

The second component is a solution alkylamine or mixture alkylamine and alkoxyalkane in an inert solvent; the ratio alkylamine to akoxicillin in this mixture can be used to control the process. Alkylamine has the formula AlRnX3-nand alkoxyamine has the formula in which each R, R' and R" are independently selected from alkyl or aryl with 1 to 20 carbon atoms, X is halogen, especially fluorine, chlorine and bromine, n is 1-3 and m is 2. The preferred halogen is chlorine.

Alkoxyamine can be prepared by mixing the appropriate alkylamine with the appropriate alcohol, in order to form alkylalkoxysilane. Preferably, alkylamino represents what alkylamine in the second component. In fact, the preferred method of forming the second component is the addition of alcohol to alkylamine in number, smaller stachion the like can be carried out in a stream at a temperature below than 30oC, allowing the reaction to proceed for some minimum time. This time depends on the type and reactivity of the components that are used for specific catalyst. As will be shown in subsequent examples, the supply of alcohol directly into the solution during polymerization adversely affect the polymerization process.

The ratio of alcohol to alkylation, which is used to achieve regulation of the process of polymerization is in the range of 0.1-1 (alcohol : aluminum).

The concentration of components in solutions used for the preparation of the catalyst is not critical and is usually guided by practical considerations. Can be used in such low concentrations as 25 parts per 1 million based on weight, however, increased concentrations of, for example, 100 parts per million and above are preferred.

As will be shown in subsequent examples, the sequence of stages of preparation of the catalyst is important for the preparation of the catalyst with high activity.

Described here, the coordination catalyst used in the method of the present sobria, no hard part to its delivery into the reactor. In addition, the catalyst and its components are not suspensions. All components are easy to handle, stable when stored liquids.

The solvent used in the preparation of a coordination catalyst, an inert hydrocarbon, in particular a hydrocarbon that is inert in relation to the coordination catalyst. Such solvents are well known and include, for example hexane, heptane, octane, cyclohexane, methylcyclohexane and hydrogenated gasoline. The solvent used in the preparation of the catalyst, is preferably the same, which is fed into the reactor for the polymerization process.

The first component described here, the catalyst may be used in accordance with the method of the present invention in a wide temperature range, which can be used in the polymerization of alpha-olefins employed in the process in solution. For example, the polymerization temperature can be in the range 105-320oC and especially in the range 105-310oC. However, as will be shown in subsequent examples, the activator is particularly effective when Temperatu, at such elevated temperatures.

The pressure used in the process of the present invention are as such known processes for polymerization in solution, for example a pressure in the range of from about 4 to 20 MPa.

In the method of the present invention alpha-olefin monomers are polymerized in a reactor in the presence of a catalyst. Pressure and temperature are regulated so that the resulting polymer remained in solution.

Small amounts of hydrogen, for example, 1-100 parts per million by weight, based on the entire solution entering the reactor, can be added in one or more commodity flow reactor system in order to improve regulation of the melt index and/or molecular weight distribution, and thus contribute to a more uniform product, as disclosed in the patent Canada N 703704.

The solution emerging from the reactor polymerization, usually processed in order to deactivate any catalyst remaining in the solution. There are many deactivators catalyst, examples of which include fatty acids, salts of alkaline earth metals and aliphatic carboxylic kilometer, used for deactivator is preferably the same solvent used in the polymerization process. If you are using another solvent, it must be compatible with the solvent used in the polymerization mixture, and not to affect the regeneration of the solvent associated with the polymerization process.

After deactivation of the catalyst solution containing the polymer may be passed through the layer of activated alumina or bauxite, which removes part or all of the remainder of the deactivated catalyst and/or other mixtures. However, it is preferable that the process worked without removing deactivated catalyst residues. Then the solvent can be evaporated from the polymer, which subsequently may be subjected to extrusion into the water and cut into pellets or other suitable powdered form. The selected polymer can then be treated with saturated steam at atmospheric pressure, for example, in order to reduce the amount of volatile substances and to improve the color of the polymer. This processing may be performed for about 1 to 16 hours, after which the polymer can be dried and cooled air flow in techenie amines, and other additives can be added to the sample either before or after the initial molding of the polymer in granules or other powdered form.

Antioxidant introduced into the polymer, which is obtained by the method of the present invention, can be, in variants of the embodiment, the individual antioxidants, for example, difficult phenolic antioxidant or mixture of antioxidants, for example, difficult phenolic antioxidant in combination with a secondary antioxidant, for example, postiton. Both types of antioxidants known from the prior art. For example, the ratio of phenolic antioxidant to the secondary antioxidant may be in the range from 0.1:1 to 5:1, and the total amount of antioxidant is in the range from 200 to 3000 parts per million.

The method of the present invention can be used to produce homopolymers of ethylene and copolymers of ethylene and higher alpha-olefins having a density in the range of, for example, approximately 0.900 for 0,970 g/cm3and especially 0,915-0,965 g/cm3; and polymers of higher density, for example approximately 0,960 g/cm3and above are homopolymers. Such polymers may have a melt index, measured p is sustained fashion 0.1 to 120 DG/min These polymers can be produced with narrow or wide distribution of molecular weight. For example, the polymers can have a stress exponent (a measure of molecular weight distribution) in the range of about 1.1 to 2.5, and especially in the range of approximately 1.3 to 2.0.

Load the exponent is determined by measuring the output of the melt indexer at two loads (2160 g and 6480 g) using the testing methods of melt index according to the US standard ASTM and the following formula:

< / BR>
The values of the stress exponent is less than approximately 1,40 testify narrow molecular weight distribution, while values above approximately 1.70 to indicate the wide molecular weight distribution.

The polymers obtained by the method of the present invention, can be converted into a wide range of products that are known for homopolymers of ethylene and copolymers of ethylene and higher alpha-olefins.

Unless otherwise stated, the following examples use the following methods.

The reactor consisted of a device for high pressure, free volume 81 ml (right inner form with priblizitelino blade propellers turbine type, a heating jacket, regulators of pressure and temperature, three supply lines and one output line. The supply lines were located on the top of the apparatus, each was at a radial distance of 40 mm from the axis, while the output line is arranged along the axis of the mixing shaft. Precursors of catalysts and other reagents were prepared as solutions in cyclohexane, which was purified by passing through layers of activated alumina, molecular sieves and silica gel to purge it with nitrogen.

Ethylene was fed to the reactor in the form of a solution in cyclohexane, prepared by dissolving the purified gaseous ethylene in a purified solvent. The feed rate of the catalyst components were placed in such a way as to obtain the desired reactor conditions. The desired residence time in the catalytic lines was achieved by adjusting the length of pipelines, through which the components. The residence time in the reactor was maintained constant by regulating the flow of solvent into the reactor so that the total flow remained constant. The pressure in the reactor was maintained equal to 7.5 MPa, and the temperature and flow was supported by a post which was 3-4 wt.%. The deactivator solution, namely triisopropanolamine or nonanalog acid, cyclohexane was injected into the stream exiting the reactor on the output line. Then the pressure in the flow was reduced to approximately 110 to kPa (absolute), and the unreacted monomer was continuously analyzed by gas chromatography. Catalytic activity was determined by the formula:

Kp= (Q/1-Q)(1/VP)(1/concentration of the catalyst),

where Q represents the fraction of ethylene (monomer), converted into a polymer, EAP - time in the reactor, expressed in minutes, and the concentration of the catalyst is the concentration in the reaction apparatus, expressed in mmol/l adjusted for impurities. The concentration of the catalyst is calculated on the amount of transition metals. Was calculated polymerization activity (Kp).

The present invention is illustrated by the following examples. Unless otherwise noted, in each example, the used solvent was cyclohexane, the monomer was ethylene and the residence time in the reactor was maintained constant and equal to 3 minutes

Example I

The catalyst was prepared by mixing in a stream at room temperature (approximately 30oC) in cyclohexane of each of the combining additional solution triethylaluminum in cyclohexane. Concentrations and fluxes of each of the compounds was determined in such a way as to obtain the following molar ratios:

chlorine (from the tertiary butyl chloride/magnesium = 2,4;

the magnesium/titanium = 5,0;

aluminium (first triethylaluminium)/titanium = 0,9;

aluminum (second triethylaluminium)/titanium = 3,0.

The polymerization reactor operated at a temperature of 230oC, which was measured in the reactor. Coming out of the reactor solution was disabled, and the polymer was isolated as described above. Expected catalytic activity (Kp), the obtained results are presented in Table I. the Ratios shown for Cl/Mg and Al2/Mg represent the optimized values necessary for obtaining the maximum catalytic activity at the indicated ratios of Mg/Ti and Al1/Mg.

In experiments 2 and 3 the catalyst was prepared as above except that 1 molar equivalent of a tertiary butyl alcohol (mol Al2added to the second aliquot of triethylamine (so was the alkoxide).

Experiments 1, 2 and 3 illustrate that the ratio of the catalyst components for alkoxide systems have a significant impact on increased activity, Kotoriba process, however, however, demonstrates that it is possible to obtain an increase in the catalytic activity of more than 2 times. Comparison of experiments 3 and 2 illustrates that the catalytic activity is sensitive to ratios of components that can be used to control the process.

Experiments 4, 5, 6 and 7 illustrate the use of other alcohols, different from the tertiary butanol.

Experience 8 demonstrates the negative impact of the addition of alcohol directly into the reactor and not in the stream of secondary triethylaluminum. This indicates the need for primary education particles alkoxyalkane.

Example II

As a comparison with other known activators for high temperature polymerization technique of Example I was repeated using activators and the reaction temperature indicated in Table II. Were obtained the results given in Table II.

This example illustrates the relative increase in the activity of the catalyst at a higher temperature, which is for t-butoxyaniline compared with other activators.

Example III

The catalyst was prepared from solutions tetrachromacy thermally at 205-210oC for 110-120 with by mixing with hot solvent is cyclohexane. Then add the activator to activate the catalyst. The polymerization reactor was operated at temperatures shown in Table III. Coming out of the reactor solution was disabled, and the polymer was isolated as described above. Expected activity of the catalyst. The following results were obtained; in each experiment the molar ratio of Ti/V=1.

This example illustrates the improvement obtained by using t-butoxyaniline as activator.

Example IV

In order to compare the use alkoxyalkane with other activators, the method of Example III was repeated using the reactor temperature is equal to 130oC. Were obtained the results given in Table IV.

This example illustrates the poor activity of the catalyst at low temperature, when the activator is applied alkoxyalkane, and so reached unexpectedly good activity at high temperature.

1. The method of obtaining alpha-olefins of high molecular weight polymers in solution by polymerization of ethylene or mixtures of this is ora, consisting of two components, the first component containing titanium, magnesium and aluminum, and the second component comprises a mixture of alkylamine General formula I

AlRnX3-n,

where R is alkyl, C1-C20;

X is halogen;

n = 1 - 3,

and alkoxyalkane General formula II

AlR'mOR"3-m,

where R' and R" may be the same or different and denote alkyl;

n = 1 - 3,

m = 0 - 2,

in inert hydrocarbon solvent under heat and high pressure, characterized in that the polymerization is carried out at a temperature of 180 to 320oC, and the formation of the first and second catalyst components and their mixing is carried out in the stream at a temperature lower than the 30oC.

2. The method according to p. 1, characterized in that as a coordination catalyst using a coordination catalyst, in which the second component contains alkylamine formula I, in which R is alkyl with 2 to 10 carbon atoms, n = 3 and each of R' and R" is alkyl with 2 to 10 carbon atoms, m = 2.

3. The method according to p. 2, characterized in that as the coordination of the coordination catalyst used catalyst, the first component of which is opened vanadium, and alyuminiiorganicheskikh compounds at a temperature lower than the 30oC, and heating the resulting mixture to a temperature of 150 - 300oC for a period of 5 - 60 minutes

4. The method according to p. 2, characterized in that as the coordination of the coordination catalyst used catalyst, the second component which is produced by mixing the respective alkylamine with the corresponding alcohol in a ratio of alcohol to alkylamino of 0.1:1 to 1:1.

5. The method according to p. 2, characterized in that as the coordination of the coordination catalyst used catalyst, the second component which is a mixture trialkylamine and alcohol in which the alcohol content is less than stoichiometric, to form dialkylhydroxylamines.

6. The method according to p. 5, characterized in that as trialkylamine use alkylamine AlR33where each R3is an alkyl group having 1 to 10 carbon atoms and the alcohol has the formula R4OH, in which R4is alkyl (C1-C20.

7. The method according to p. 2, characterized in that as the coordination of the coordination catalyst used ka is Roy each of R12and R23is the same or different and independently selected from alkyl groups having 1 to 10 carbon atoms;

ii) a reactive chloride component;

iii) of titanium tetrachloride.

8. The method according to p. 3, characterized in that as alyuminiiorganicheskikh connections use trialkylaluminium or dialkylamino-halide.

9. The method according to any of paragraphs. 1 to 7, characterized in that as the coordination of the coordination catalyst used catalyst without releasing any of its components.

 

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