FI71160C - DEACTIVATION OF A CATALYST VIDE POLYMERIZATION OF ALPHA-OLEFINER I LOESNING - Google Patents

Description

1 71160

In the solution polymerization of catalyst deactivation olefins

The invention relates to a solution polymerization process for the preparation of high molecular weight β-olefin polymers which are homopolymers of ethylene or copolymers of ethylene and C3-12-ol olefins, in which the coordination catalyst used is deactivated but the deactivated catalyst does not need to be deactivated.

Polymers of ethylene, for example homopolymers of ethylene and copolymers of ethylene and higher molecular weight β-olefins, are used in large quantities for a variety of purposes, for example, films, fibers, molded or thermoformed bodies, tubes, coatings, and the like.

Methods for preparing homopolymeric ethylene and copolymers of ethylene and higher molecular weight β-olefins are known. Such processes include processes in which the monomers are polymerized in the presence of a coordination catalyst, for example, a catalyst containing a transition metal compound of Groups IVB-VIB of the Periodic Table or an organometallic compound of a metal of Groups I-IIIA of the Periodic Table.

A particularly preferred process for the polymerization of β-olefins is the hot or solution polymerization process, for example the process described in CA Patent 660,869 (A.W. Anderson, E.L. Fallwell and J.M. Bruce, published April 9, 1963). In the solution process, the process parameters are selected so that both the monomer and the polymer are soluble in the reaction medium. Under such conditions, the degree of polymerization and the molecular weight of the polymer thus prepared can be precisely controlled, for example, by controlling the reaction temperature.

In the solution polymerization process, the polymerization reaction is usually terminated by adding the so-called a deactivating agent, for example a fatty acid or an alcohol. The fatty acid is mixed with a hydrocarbon solvent, usually the polymerization reaction solvent, and fed to the polymerization mixture, usually immediately after the mixture leaves the reactor.

The deactivator-treated polymerization mixture contains catalyst residues which can be removed by treating the mixture with an adsorbent, for example aluminum. A deactivation and catalyst removal process such as that described is described in CA Patent 732,279, B.B. Baker, K.M. Brauner and A.N. Oemler, published April 12, 1966.

A process for deactivating a coordination catalyst in a solvent-free high pressure polymerization process for A-olefins is disclosed in U.S. Patent 4,105,609, J-P. Machon, B. Levresse and P. Gloriod, published August 8, 1978. The process comprises injecting an alkali or alkaline earth metal salt of a carboxylic acid, for example sodium stearate, calcium stearate or sodium benzoate, into the polymerization reaction mixture.

Vanadium-containing coordination catalysts can be readily deactivated by treating the polymerization mixture with a solution of a salt of an aliphatic monocarboxylic acid and an alkaline earth metal or zinc dissolved in the hydrocarbon solvent used in the polymerization process. Such deactivation of the vanadium-containing coordination catalyst results in a better colored polymer, as disclosed in EP 62 127, 25 V.G. Zboril, issued May 2, 1935. However, this deactivation does not improve the color of the polymers when the catalyst is a titanium-based coordination catalyst, including catalysts containing small amounts of vanadium. In addition, the presence of iron and other heavy metals, usually as impurities, tends to adversely affect the color of the polymer when such catalyst deactivation is used.

It has now been found that the titanium-based coordination catalysts used in the solution polymerization process can be deactivated to give a polymer of better color by sequentially treating the polymerization mixture with a small amount of 3,71160 water followed by a solution of polyalcohol to the solvent used in the immersion process.

The solution polymerization process according to the invention for the preparation of high molecular weight d-olefin polymers is characterized in that the monomer which is ethylene or a mixture of ethylene or at least one α-olefin, a coordination catalyst and an inert carbon-10 hydrogen solvent is fed to the reactor? the monomer is polymerized at a temperature below 320 ° C and a pressure below 25 MPa? the catalyst in the resulting solution is deactivated by stirring a small amount of water and then a solution of a salt of an alkaline earth metal and an aliphatic mono-carboxylic acid dissolved in a hydrocarbon solvent; the hydrocarbon solvent and other volatile matter are separated from the resulting solution; and recovering the solution containing said high molecular weight polymer, wherein the amount of water does not exceed 2.5 moles of water per mole of halogen plus alkyl groups in the coordination catalyst.

In a preferred embodiment of the process of this invention, a water-soluble metal chelating agent is dissolved in water.

In another preferred embodiment of the process of this invention, the carboxylic acid is a C8 carboxylic acid and the alkaline earth metal is calcium.

In another embodiment, the coordination catalyst is a titanium-based coordination catalyst. , 1-hexene, 1-octene or bicyclo [2.2.1] -2-heptene, copolymers. In addition, cyclic endomethylene dienes can be fed to the process with ethylene or a mixture of ethylene and a mixture of C 1-6 α-olefin, as described in CA Patent 980,498, C.T. Elston, published December 23, 1975.

In the solution polymerization process of this invention, the ε-olefin monomer, the coordination catalyst and the inert hydrocarbon solvent are fed to the reactor. The coordination catalysts used in the solution polymerization processes are known, e.g. AN Mollison and V. G. Zboril, published March 2, 1982, and CA Patent 1171065, 15 V. G. Zboril and M. A. Hamilton, issued July 17, 1984.

The -olefin monomer may be exclusively ethylene or a mixture of ethylene and one or more higher molecular weight α-olefins.

Solution polymerization processes can be carried out at temperatures below 20,320 ° C, especially in the temperature range 105-310 ° C, with the lower temperature being higher than the lowest temperature at which the polymer remains in solution, as will be apparent to those skilled in the art of solution polymerization processes. The pressures used in the process of this invention are conventionally used in solution polymerization processes, namely less than 25 MPa and especially about 4-25 MPa. The pressure and temperature are controlled so that both the unreacted monomers and the polymers formed remain in solution.

The hydrocarbon solvent used in the polymerization process is a solvent that is inert to the coordination catalyst. Such solvents are known and include hexane, heptane, octane, cyclohexane, methylcyclohexane and hydrogenated naphtha. The solvent used in the polymerization-35 process is preferably also used in the preparation of the coordination catalyst. The hydrocarbon solvent is the main component in the polymerization mixture fed to the reactor, usually comprising at least 80% of the reaction mixture. In the process (Ti-olefin is dissolved in 5 solvents.

The mixture exiting the polymerization reactor contains a polymer, an unreacted monomer, a coordination catalyst, some of which is in the active state, and a hydrocarbon solvent. A deactivating agent 10 is added to the mixture to terminate the polymerization.

In the process of the present invention, the deactivating agent is added in two steps. In the first step, a small amount of water is added to the polymerization mixture. The amount of water to be added is less than 2.5 moles of water per mole of halogen plus alkyl groups in the coordination catalyst. Preferably 0.25 to 1.5 moles of water are added per mole of halogen plus alkyl groups.

In a preferred embodiment, the water contains a water-soluble chelating agent in solution. Said substance 20 is added to chelate heavy metals which may be present in the polymerization mixture as impurities, for example as a result of corrosion of the equipment used in the polymerization process. Typical such impurity metals are iron and / or manganese. Alkali metal fluorides are preferably used to chelate said metals.

In the second step, the deactivating agent is a solution containing a salt of an alkaline earth metal and an aliphatic monocarboxylic acid dissolved in a hydrocarbon solvent. In particular, the same solvent as in the polymerization process is used as the hydrocarbon solvent of the deactivating agent. If a different solvent is used, it must be compatible with the solvent used in the polymerization process, must not cause precipitation of any component of the polymerization mixture and must not interfere with the solvent recovery associated with the polymerization process.

6 71160

The salt of the second deactivation solution must be dissolved in the solvent in order to achieve close contact between the deactivating agent and any remaining active catalyst, and to provide deactivating agent and catalyst residues, i.e. after deactivation of the catalyst form, uniform dispersion throughout the polymer and thus enabling the production of a polymer with uniform properties.

The metal in the salt of the deactivation solution is an alkaline earth metal, especially calcium.

The remainder of the salt is derived from an aliphatic carboxylic acid, especially an acid having 6 to 20 carbon atoms. In a preferred embodiment, the acid contains 8 to 12 carbon atoms. The acid is preferably a branched aliphatic acid, although straight chain and cyclic aliphatic acids may be used. In addition, the acids may be saturated or unsaturated. However, the acid must be such that its salt used in the process of this invention is soluble in the solvent used therein.

In a most preferred embodiment, the salt is calcium 2-ethylhexanolate.

The temperatures at which the first and second deactivating agents are added to the polymerization mixture can affect the color of the resulting polymer (cf. examples). Preferably, the first deactivating agent is added when the temperature of the solution is below 235 ° C and the second deactivating agent is added to the solution at a temperature below 120 ° C. If deactivating agents are added at higher temperatures, the color of the polymer, depending on, for example, the amount of catalyst in the polymerization mixture, may not be suitable for commercial purposes.

In the process of this invention, the deactivated polymerization mixture is fed to a separator, which may be a multi-stage separator, to separate the unreacted monomer, the hydrocarbon solvent and any other volatile material from the polymer. Contrary to the usual practice in solution processes, no measures are taken to remove catalyst residues and / or deactivating agent from the polymer using adsorbents or other methods. After separation from the solvent and the unreacted monomer, the polymer is extruded into water and cut into pellets or other suitable small forms. Dyes, antioxidants and other additives may be added to the polymer, especially just prior to preparation of the pellets or other compact forms.

The polymer prepared by the process of this invention can be used for a variety of purposes, as is known in the case of homopolymers of ethylene and copolymers of ethylene and higher molecular weight β-olefins.

The use of the deactivation method of the present invention can lead to a reduction in corrosion in those parts of the process equipment which are located downstream of the deactivating agent inlet. The use of the deactivation process of this invention 20 may also result in the production of a polymer of better color, especially when the coordination catalyst used in the process is a titanium-based coordination catalyst.

The present invention is illustrated by the following examples.

25 Example I

The polymerization catalyst was prepared by mixing (in-line) a solution of titanium tetrachloride in cyclohexane (6.0 mmol / liter) and a solution of diethylaluminum chloride in cyclohexane (6.0 mmol / liter).

The resulting mixture was kept at room temperature for about 15 hours, after which it was heated to 225 ° C by spraying with cyclohexane preheated to 300 ° C. The combined stream was maintained at 225 ° C for one minute before being fed to the stirred polymerization-35 reactor. A solution of ethylene in cyclohexane and a solution of triethyl-8,71160 aluminum in cyclohexane (20 mmol / liter) were also fed to the reactor. The ratio of triethylaluminum to titanium in the catalyst was adjusted to achieve the best conversion of ethylene to polymer; the ratio calculated as atoms ranged from 1.5 to 3.0. The heat-5 state in the reactor was 230 ° C, pressure 7.5 MPa, flow rate through the catalyst 0.33-0.40 min, conversion of ethylene to polymer more than 50% and titanium content in terms of atoms 0.3-1.0 mmol / liter.

The first deactivating agent was continuously added to the reaction mixture as soon as it left the reactor. The solution thus treated was passed through a layer of 2 mm diameter glass beads to facilitate mixing. The flow rate through the bed was 2.2 min ^ calculated according to the empty bed. The second deactivating agent was then added continuously to the mixture. The resulting solution was maintained at 130-140 ° C. The pressure of the solution was then reduced to 110 kPa (abs), after which the polymer precipitated to form a suspension with the solvent. The suspension was evaporated to dryness using a steam bath. The polymer 20 thus obtained was ground and compressed at 190 ° C into 2 mm thick slabs. The yellowness index of the tiles was determined by the method according to ADTM D 1925.

The results obtained using different amounts of deactivating agent were as follows: 25 ______

Driving No. 1 23456

Deactivating agent (a) Water

Ratio * 0 0.58 0.78 1.18 0.59 0.68 30 (b) Calcium -2-ethylhexanoate

Ratio ** 0.75 0.75 0.75 0.63 0.94 0.83

Yellowness index 38.0 25.8 30.9 22.1 12.0 -2.2 * moles of water per mole of halogen (Cl) plus 35 alkyl (ethyl) ** ratio of calcium to halogen (Cl) calculated as atoms 9 71160

Note. Run No. 1 is not in accordance with the present invention, it is included for comparison.

This example demonstrates the beneficial effect of the deactivation method of this invention on the color of the resulting polymer. No run without calcium 2-ethylhexanoate was attempted, as it was expected that a polymer would be formed that would corrode the equipment being used too much.

Example II

The procedure of Example I was repeated with the exception that calcium 2-ethylhexanoate was used as the first deactivating agent and water as the second. The results obtained using different amounts of deactivating agent were as follows: _ 15 Run No.___7_8__

Deactivating agent (a) Calcium 2-ethylhexanoate

Ratio * 0.62 0.56 2Q (b) Water

Ratio ** 0.29 0.82

Yellowness index_29.7_18.6_ _ * ratio of calcium to halogen (Cl) in atoms ** moles of water per mole of halogen (Cl) plus 25 alkyl (ethyl) This example shows that the order of addition of the two de-activators used is important. In particular, the results of Run No. 8 of this example were substantially worse than the results of Run No. 6 of Example I, with the order of addition being reversed.

Example III

The procedure of Example I was repeated with the exception that the titanium component of the catalyst was replaced with a mixture of 85 mol% of titanium tetrachloride 35 and 15 mol% of vanadium oxytichloride.

10 71160 __The results obtained were as follows:

Aio no__9 10 11 12_13 14 15_

Deactivating agent (a) Water 5 Ratio * 0 0.54 1.07 2.14 0.52 1.04 1.56 (b) Potassium 2-ethylhexanoate

Ratio ** 0.77 0.85 0.85 0.85 0.99 0.99 0.99

Yellowness index 16.2 22.8 1.4 5.6 3.6 2.4 5.5 10 * moles of water per mole of halogen (Cl) plus alkyl (ethyl) ** ratio of calcium to halogen (Cl) calculated as atoms Note . Run No. 9 is not in accordance with the present invention, it is included for comparison.

This example illustrates the deactivation of a coordination catalyst containing titanium and vanadium.

Example IV

The procedure of Example I was repeated with the exception of 2q that a 1 M solution of t-butanol in cyclohexane was used as the first deactivating agent.

_The results obtained were as follows:

Driving No. 16 17 18 19 20 21

Deactivating agent ~ 25 (a) t-butanol

Ratio * 0.65 0.65 0.65 0.39 0.39 0.39 (b) Calcium 2-ethyl hexanoate

Ratio ** 0.94 1.30 0.56 0.56 0.94 1.30

Yellowness index 35.7 34.0 32.6 26.2 33.2 16.2 * moles of t-butanol per mole Halogen TCT) plus alkyl (ethyl) ** ratio of calcium to halogen (Cl) calculated as atoms This example shows that that using alcohol as the first deactivating agent is a worse option than using water alone.

n 71160

Example V

The procedure of Example I was repeated with the exception that the corrosion products of the equipment were present in the mixture leaving the reactor. An aqueous solution of 100 g of potassium fluoride per liter of the whole solution was used as the first deactivating agent. All polymer samples contained more than 10 ppm iron.

The results were as follows; color was assessed visually by examination using a scale from 0 (not 10 colors) to 5 (yellow hue):

Driving No. 22 23 24

Deactivating agent (a) Potassium fluorine. c diliuos 15

Ratio * 0.45 0.84 1.25 (b) Calcium 2-ethyl hexanoate

Ratio ** 0.99 0.99 0.99 Color 10 5 20 - * moles of water per mole of halogen (Cl) plus alkyl (ethyl) ** Ratio of calcium to halogen (Cl) in atoms This example shows a chelating agent. namely, the beneficial effect of using potassium fluoride in the first deactivating agent on the color of the polymer when corrosion products, such as iron, are present in the polymer solution. The example also shows that there is an optimum amount of chelating agent, and that amounts in excess of it, e.g., run No. 24, may have little beneficial effect on the color of the polymer.

Example VI

The procedure of Example I was repeated with the exception that the titanium component of the catalyst was replaced with a mixture of titanium tetrachloride and vanadium oxytichloride (molar ratio 85:15) in cyclohexane, 12,71160, containing a total of 4.0 mmol titanium tetrachloride and vanadium oxitrile chloride. The concentrations of the diethylaluminum chloride and triethylaluminum solutions were 4.0 and 8.0 mmol / liter, respectively, and the combined concentration of titanium and vanadium in the reactor, calculated as atoms, was 0.2-1.0 mmol / liter.

The polymerization mixture leaving the reactor was deactivated as follows: the first deactivating agent, water, was added to the polymerization mixture as soon as the mixture left the reactor. The water temperature was varied and is reported in more detail below. Water was sprayed at a rate of one mole of water per mole of chloride plus alkyl through a 0.25 mm diameter tube into the center of a 0.62 mm diameter tube at a liquid velocity of 15 cm / s in the latter tube. The temperature of the polymerization mixture formed was maintained for about 25 seconds, and then lowered to the temperature at which the second deactivating agent was to be added and maintained for 160 seconds. Another deactivating agent, calcium -2-ethylhexanoate) was then added at a calcium: chloride ratio of 0.83 (calculated as atoms). The temperature was maintained for another 20 seconds and then adjusted to 130-140 ° C. The deactivated mixture was then treated as described in Example I.

25 The results obtained were as follows:

Driving No. 25 26 27 28 29 30

Addition temperature

The first 149 160 176 202 238 253 3Q deactivation agent

Another 109 113 112 110 HO 118 deactivating agent

Yellowness Index 0.68 1.78 -4.58 1.88 7.16 28.4 35 This example shows that when the first deactivating agent is added at relatively high temperatures, 71160 especially above 235 ° C *, the resulting polymer tends to be more strongly colored .

Example VII

The procedure of Example VI was repeated with the 5 exception that the addition temperature of the second deactivating agent was changed. The results obtained were as follows: __

Driving number_31 32 33_34 35 36

Addition temperature 10 First 202 202 212 219 219 215 deactivating agent

Second 104 110 125 144 168 198 Deactivating agent 15 Yellowness index 1.22 1.88 18.9 15.3 22.8 19.6 This example shows that when adding a second deactivating agent at relatively high temperatures, in particular above 120 ° C , the resulting polymer 20 tends to be more strongly colored.

Claims (12)

A solution polymerization process for the preparation of high molecular weight o-olefin polymers which are homopolymers of ethylene or copolymers of ethylene and olefin characterized by feeding a monomer which is ethylene or a mixture of ethylene and at least one C 2 Olefin, a coordination catalyst and an inert hydrocarbon solvent for a reactor; polymerizes the monomer at a temperature below 320 ° C and a pressure below 25 MPa; deactivating the catalyst in the obtained solution by admixing the solution with a smaller amount of water and then a solution comprising a alkaline earth metal and an aliphatic monocarboxylic acid solution dissolved in a hydrocarbon solvent; separating the hydrocarbon solvent and other volatile materials from the resulting solution; and utilizing the solution comprising said high molecular weight polymer, the amount of water increasing at most to 2.5 moles of water per mole of halogen plus alkyl groups in the coordination catalyst. Process according to claim 1, characterized in that the water is present as an aqueous solution of a water-soluble metal chelating agent. Process according to claim 2, characterized in that the metal chelating agent is an alkali metal fluoride. 4. A process according to claims 1-3, characterized in that the polymerization temperature is in the range 105-310 ° C. 5. A process according to claims 1-4 characterized in that the coordination catalyst is a titanium based coordination catalyst. 35