CS235952B2 - Method of ethylene and alpha-olefins copolymers production - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of ethylene copolymers.

Numerous examples of ethylene-α-olefin copolymers are described in the literature. The catalysts used for the polymerization of ethylene are generally also useful for the capillary polymerization of ethylene and α-olefin. However, the results of said copolymerization are largely dependent on the yellowish type of catalyst and, in particular, in terms of the final product product, on the nature of the α-olefin used. Examples of copolymers that are readily processable into films include copolymers in which the α-olefin contains at least 4 carbon atoms. For such copolymers there is a French patent

No. 1,604,960 mentioned, first, the importance of the narrow distribution of molecular tanoonnotes and, secondly, the importance of distorting the comonommir between the copolymer molecules. Regarding the latter, homogeneous copolymers were better processed into films than heterogeneous copolymers.

It is known that a copolymer of ethylene and α-olefin, intended for film processing, is in fact defined only by the sum of the following seven characteristics:.

1. bulk density

2. character of the comonomeeu

3. melt flow index

4. ooolar content of the comonorner

5 «mean molecular weight

Grade 6 pjlydlsjpezžty, denoting! distribution of mco.ekulové masses! and defined in the following text

7th degree of hot monomer distribution.

In the case of copolymers having the same or equilibrium values - six of the seven properties mentioned above and cast values having the seventh property, different copolymers can be expected for these copolymers (workability for the final film and finally 1 different properties so obtained). foil.

Surprisingly, it has now been found that heterogeneous copolymers of ethylene and α-olefins containing at least 4 carbon atoms, which, contrary to the assertions disclosed in the aforementioned French Patent No. 1,604,980, are suitable for processing non-foil.

In the following description, the term copolymer will refer simultaneously to binary polymers encompassing ethylene and olefin, and the thimeric polymers will contain two η-olefins in addition to ethylene. In a broader formulation, the process of the invention also applies to polymers containing more than two α-olefins in addition to ethylene.

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of copolymers of ethylene and α-olefins having at ^least 4 carbon blacks ^, having a ^{0.940 g /} cm @ 2 bulk tonicity; 2-2 dg / OLN and heterogeneous distribution а- с ^ ^ ^^ ио units in the copolymer, and - tbstlulící lmotZfcí and crystalline fractions, ^beta řičeož Cr ^{y Ké} centrepieces fraction maj ate. ^ oaxiouo "VCI temperatures between 116 and 1 ° ³ ° And is from 20 to 50% of the total monomer of the copolymer, copolymerized with ethylene and an olefin and at least 4 carbon atoms in at least one reactor containing at least one zone. at a temperature of 180 to 320 ° C and a pressure of 30 to 250 MPa by means of a catalytic system of the Zetel type of which:. The principle is that the gaseous stream fed to the rector is in the stationary state 10 to 80% by weight of ethylene and 20 to 90% by weight of ethylene and 20 to 90% by weight of ethylene. ole-linen, while p ^ ^y uužije- kαtll tickéht system obsahuuícího partly activator selected from the group аОитп с ^! hyárldy tzgantktvtvé and metal compounds IE III of the periodic system - and, secondly, at least one halogenated - a transition metal compound of the formula / T1C1 ₃ 1/3 A1C1 ₃ / / ₃ ΜΧ / _χ. (MgCl ₂ )

235 952 in which

X is greater than or equal to 0.3 e less than or equal to 21, y is greater than or equal to 0 e less than or equal to 20,

M is a transition metal from the group consisting of metals VB, VIB. . and VIII. groups

Periodic system of elements a

X is halogen, wherein the atomic ratio of activator metal to transition metal is 1 to 10 and the mean residence time of the catalyst system in the polymerization reactor is 2 to 100 seconds.

Preferably, the activator used is a compound selected from the group consisting of triethylbutyl and alkylsiloxalanes.

The coplymerization is preferably carried out in the presence of at most 2 molar percent hydrogen.

An advantage of the process according to the invention is that the ethylene-olefin-based copolymer containing at least 4 carbon atoms is easy to process into films and has at least an equivalent or better summary of properties than similar or analogous ethylene polymers. By better summary of properties is meant that not all of the properties considered need to be improved, at least some of which are substantially improved in favor of the brightly obtained films and the other remaining properties are either retained or partially deteriorated without however, this has had an adverse effect on the benefits achieved by improving the initially mentioned properties. The term ethylene polymers, analogous or analogous, includes not only ethylene copolymers whose film-forming ability is described in 11,111,111, but also in particular ethylene homopolymers called polyethylenes. low density, produced at high pressure in the presence of a free radical initiator.

The copolymers of the invention may also be characterized by an average molecular weight between 15,000 and 60,000 and / or a degree of polydispersate of between 3 and 9 for binary polymers and between 6 and 12 for terrain polymers. In the pre-stage dilution, the average molecular weight should be understood in the manner customary in the polymer arts as the average number molecular weight Mn and the degree of polydispersity as the ratio of the average molecular weight. The molecular weight to the average number molecular weight of the (Mw) Mn-α-olefloy which is treated in the context of the heterogeneous copolymers produced by the process of the invention may be, for example, 1-butene, 1-hexene. 4-methyl-1-octene and 1-octene. When two c-olefins (i.e. in the case of terpolymers, then their total mean content is already. preferably between 1 and 8 molar percent and their ratio of mean contents to each other is preferably 0.25 to 4. For example, ethylene butene-1-hexene produced by the process of the invention and containing an average of 95% by weight. % of the ethylene units may contain on average 1 to 4 motes; percent of l-butene units and on average 4 to 1 motam! the percentage of V-hexent units.

The copolymers thus defined according to the invention have remarkable properties that are capable of being processed into said films, having a better summary of properties than the ethylene polymers in which the films are generally produced. Ductility and tear resistance are essential in improving these. The copolymers of the present invention exhibit a ductility of about 600 to 1,100. tear resistance (measured according to ASTM D 1922-67 / 150 to 900 gp), depending on the eda's wear in longitudinal or transverse, tertiary (measured according to ASTM D 2 457 // greater than or equal to 70% and impact strength) / as measured according to NF T 54 109 / up to 400 g. It should be noted that in the case of longitudinal curves, it is also necessary to specify the sample to be measured, since these values increase significantly with increasing thickness.

If the metal M. chooses from VB. and VIB groups of the Periodic System of Elements, then said catalysts have the structure of solid binary Ti-M solutions that can. be characterized by the dimensions of their crystallites. It has been found that, with respect to the efficiency of these catalysts, this dimension determined by radiocrystalline analysis (Sherrer) in the direction perpendicular to plane 300 should preferably be less than or equal to 10 nm.

As is apparent from the foregoing formula, said catalysts may optionally be deposited on an inert support of anhydrous magnesium halide if y is greater than 0. M-metals are preferred vanadium, chromium and nickel metals, but 1 molybdenum and tungsten may be used. The magnesium halide halogen and the metal halide halogen M may be identical or differentiated and are selected from the group consisting of fluorine, chlorine, bromine and iodine.

The process for the preparation of these compounds consists in the introduction into the. by contacting titanium double chloride and aluminum chloride with the metal halogen M and optionally with anhydrous magnesium helogenide for the necessary time. This can be achieved by subjecting the three chlorides to grinding, wherein the grinding energy should be at least equal to 3 kWh per kilogram of solid pot to be treated. In fact, it has been found that the potency of these compounds is the higher the energy of the mills. However, in order to achieve a certain compromise between this efficiency and operating costs, it is not generally necessary to:. the grinding energy is greater than about 25 kWh per kilogram of solid mass to be processed. *

The amount of activator and halogen compound of the transition metal is chosen such that the atomic ratio of the activator metal to the transition metal (or in the case described above to the sum of Ti + M) is 1 to 10. The mean residence time of the catalyst system in the polymerization reactor is generally equal to 2 to 100 seconds. This residence time is greater at the reactor temperature, so that the higher the reactor temperature, the lower the residence time. Preferred activators are, on the one hand, the realkynehines and, on the other hand, the α-monosalate disclosed in U.S. Patent No. 3,969,332.

The gaseous feed to the reactor in a stationary state, as set forth in the definition of the invention, is understood to mean the average composition in the reactor, and it is understood that the composition of the feed throughout the reactor will not be uniform and may change as it passes through the reactor. where the reactor comprises several zones. This composition takes days depending on the nature of the n-olefin under consideration. Thus, for a binary copolymer, the swelling content of α-oil in the gas stream is preferably 15 to 70% for 1-butene and 35 to 90% for 1-hexane. When my reactor has several zones in the process according to the invention, it is more often advantageous to inject substantial amounts of α-olefins into the first zones operating at temperatures of 180 to 240 ° C, while the last zone operates at 240 to 320 ° C without substantially introducing additional amounts of α-olefins. ole ^ nů. .

The process according to the invention is carried out continuously using an autoclave or tubular reactor, as is usual in the operation of high pressure ethylene polymerization. In order to accurately control the melt index of the copolymer, it may be advantageous to carry out the copolyuration in the presence of up to 2 molar% hydrogen.

As mentioned above, the heterogeneous copolymers according to the invention find a privileged desert in the production of films having improved properties and a thickness of 5 to 200 .mu.m, in particular less than or equal to 20 .mu.m, i. the thicknesses of the meshes are greater than those achieved in the manufacture of the low density polyethylene films obtained by the radical mechanism. These films are manufactured by the conventional extrusion blow molding technique and offer the exceptional advantage that the much smaller adhesive has the same strength and can be used for the same purposes as the polyethylene films obtained by the radical mechanism. The films produced in this way are not included. numerous deserts, such as for the production of large-capacity sacks, for automotive packaging and for agricultural applications.

In the next section! DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples are illustrative only and are not intended to limit the invention in any way.

He did

Ko.pílymeruje ethylene and 1-hexene in eutoklévovém cylindrical reactor operating at a pressure of 100 MPa, which is inside equipped with stirrer and bars of metal, which vymeeuui tM zones of the same ^b him. Zone 1, maintained at ²²⁰ ° C, is fed with a current of 49 kg / h 1-hexene and 24 kg / h ethylene and contains a catalytic system consisting of dimethylethyldiethylsiloxalan and a compound of formula TiCl 3, 1/3 AlCl 3, 2 VCl 3 in such mutual relationship that the atomic ratio Al / Ti is 3.

Zone 2 maintained at Tg (expressed in degrees Celsius) is fed with a flow of kg / h of ethylene and contains the same caustic system as zone 1.

Finally, zone 3, at the outlet of which the copolymer-containing reaction mixture is discharged to the separation and recycling stages, is maintained at Tj (expressed in CcTsia degrees) and contains neither the catalyst system nor the monomer feed.

The mean weight of 1-hexene in the reactor is 50.5%. The amount of hydrogen was present in 0.12 mol% of hydrogen present. The average catalyst system time in the reactor was 80 seconds.

The copolymer obtained is characterized by the following properties:

(a) the flow index (IF) measured in accordance with ASTM D 1238-73 is expressed in dg / min;

^b) bulk hrnotaost φ retracts ^ADR en -vg ^s / cm;

c) Mean number molecular weight Mn measured by permeation gel chrmomogragra and expressed in thousands;

(d) the degree of polydispersity determined from Mn and from the average mass molecular weight measured by the same method;

(e) the molar percentage content of 1-hexene units in the copolymer and determined from the number of methyl groups per - 1 000 - carbon atoms per molecule by absorption of infrared radiation according to ASTM D 2238-64 T described in French Patent No. 1 604 980;

(f) the degree of homooeent (IH) of the so-called diode of the polymer, determined by the polymer freeze-dryer test and expressed as a multiple or a fraction of the multiple of the mean sites between which the content of 1-hexee units changes;

(g) the melting point of the crystalline fraction of copolymers, expressed in degrees Celsius, as determined by differential enthalpy analysis.

Both the values of these properties and the values of Tg and Tj are given in Table I below.

Example 2

The copolymers are ethylene and 1-hexene at 100 MPa in the same reactor as the one used in the previous example and under the same conditions but with the following exceptions. Zone 1 is fed with a current of 61 kg / h of 1-hexene and 25 kg / h of ethylene. Zone 2 is fed with kg / h ethylene. The mean mass content of 1-hexene in the reactor is therefore 55%. The copolymerization is carried out in the absence of hydrogen. The catalytic yield ^R _e , expressed in kilograms of copolymer per transition metal oil, as well as the properties of the copolymer obtained, are shown in Table I.

Example 1: .. β d 3

Ethylene and 1-hexene are co-gasified at 60 MPa in the same reactor. as . precedes and under the same conditions but with the following exceptions. Each of zones 1 and 2 is fed with a current of 27.5 kg / h of ethylene and 26.5 kg / h of 1-hexene. Thus, the mean 1-hexene content of the reactor was 50.9%. Kopolymereee. is carried out in the presence of 0.06 $ oo1. hydrogen.

The catalytic yield and properties of the copolymer obtained are shown in the table below.

Table I

Example ^T 2 ^T 3 ^R c IF P 1 225 270 5 »’ 0.6 0,929 2 210 255 7.6 0.9 0,920 3 220 245 6.1 1,2 0,934 Table I polcačování Example Mo Mw / Mn 1-hexene IH tt ( ⁰ ° C) 1 21.3 7.5 1.7 0.36 to 3.4 126 2 46.4 3.4 4,5 0.22 to 1.6 125 3 18.6 8.2 2,0 0.20 to 2.5 127

Example 4

Ethylene and 1-octene are co-hydrolyzed at 100 MPa in the same reactor as the bulkhead and under the same conditions as in Example 3 but with the following exceptions. Each of zones 1 and 2 is fed with a current of 24 kg / h ethyls and 29 kg / h of 1-octene. Thus, the mean 1-octene content in the reactor is 55%. '^ e ^ polymer is carried out in nepřítomnootl hydrogen, with the individual temperatures of ^about N 2 E3 ^{Tg. 200} ° ^C and T ^j = ²⁵⁰ ° C. . the official residence time of the catalyst system in the reactor is 80 seconds. The copolymer obtained in Catalyticée yield R _c = 7 kioograms per miliaoom transition metal has the following property:

IF > 0.25 Mo = 57,000 P = 0.933 g / cm Mw / Mn «3,3 1-okten = 11 moo. % m.p. = 127 ° C Pp ík lad 5

Copper with ethylene and 1-butene in a cylindrical eutoclave reactor operating at a pressure of 90 MPa; the reactor is internally equipped with a stirrer and metal partitions delimiting three zones. Zone 1, maintained at 210 [deg.] C., has twice the volume of each of the successive zones and is fed with a current of 200 kg / h with a content of 36% by weight. . 1-butene and 64% ethylene homogeneity, comprising a catalytic system consisting of both a dimerthletheddiline-oorane and a compound of the formula TiCC 1, 1/3 AICC 1, VCC 3 in such a mutual number that the atomic ratio Al / Ti is 3.

Zone 2, maintained at ² 40 ° C, is fed a stream of ⁵⁵ kg / h of the same composition as předeěle and contains the same catalyst system. Finally, zone 3, which outputs the drawn reaction mixture into the copolymer obsshujjcí račního ^ and ^p not recyttlzaČníUo growth is maintained at ^t ^ e ^p lot of ²⁸⁰ ° C and the catalyst is not repeated or accept monomee. The mean residence time of the catalyst system in the reactor is 43 seconds.

The catalytic yield and properties of the copolymer obtained are given in Table II below.

Example 6

In the absence of hydrogen, ter is polymerized with ethylene, 1-butene and 1-hexene in the reactor described in Example 1 and operating at 100 MPa. · Zone 1, maintained at 180 ° C, is supplied with a current of 13 kg / h. 1-hexene, 14 kg / h of ethylene and 6 kg / h of 1-butene, and contains a catalytic system comprising, on the one hand, a dimethylformamide and a compound of the formula TiCl 3, 1/3 AlCl 3, 6 M / glg, 0.5 NIC 1 g in such mutual interactions that the atomic ratio Al / Ti is 3 ·

Zone 2, maintained at a temperature of 225 ° C, is fed with a current of 14 kg / h ethylene and 6 kg / h 1-butene and contains the same catalyst system.

Finally, the zone 3 at the exit of which the reaction mixture containing the terpolymer is withdrawn to the separation and recycling stage is maintained at a temperature of 245 ° C and does not receive either the catalyst or the monomer. Thus, the mean hormone contents in the reactor are 53% ethylene, 24% 1-hexene and 23% 1-bulene. The mean residence time of the catalyst system in the reactor is 85 seconds. The catalytic yield and properties of the obtained ter polymer are shown in Table dále below.

Example 7

In the presence of 0.15 percent hydrogen, ethylene, 1-butene and 1-hexene were terpolymerized in a reactor described in Example 1 operating at 80 MPa.

^{ZO 1, d} u r2 ^ ^{e p} crosslinked with M at ¹⁸⁰ ° C, power is being supplied · ^27.1 kg / ^h of hexane

18.4 kg / h of ethylene, 1.6 kg / h of 1-butene and the catalyst system described in Example 5. ^Z n ^{Y 2} and 3, maintained at that ^{é h pl} rotates ²²⁰ ° C and ²⁶⁰ ° C are ^ yen Prou ^d y U R, 4 ethylene and 1.6 kg / h of 1-butene. The mean residence time of the catalytic system in the reactor is 100 seconds. The catalytic yield and properties of the terpolymer thus obtained are shown in Table II below.

Example8.

In the presence of 0.1 4 hydrogen, ethylene and 1-butene are copolymerized in the reactor described in Example 1, which is fed with a gaseous stream constituting 35% of ethylene and 65% mono-1-bulene in a stationary state. Zones 1, 2 and 3 laboriously at temperatures of 200 ° C, 210 ° C and ²³⁵ ° ^C and ^p sing ^ ^á Dad Uckétio him popsanéto system ^E of example ^1. The mean residence time of the catalyst system in the reactor is 45 s. The catalytic yield and properties of the obtained copolymer are given in the following table II2 35 952

Table II

Example ^R c IF Mn Mw / Mn 5 6.2 0.8 * 0.919 43 3.6 6 4,5 0.5 0,915 15 Dec 10.5 7 4.9 0.6 0,933 21.5 7.6 8 6.8 0.8 0,908 25 5.4

Table II

Example 1-butene 1-hexene IH mp (C) 5 3.2 -. 0.5 to 2.2 122 6 2.6 0.9 0.3 to 3.0 121 7 0.4 1.3 0.2 to 1.8 128 8 6.0 'í --- 0.5 to 2., 0 117

Examples 9 to 14

The copolymers of Examples k to 3, 4, 5 and 7 are extruded-blown to form 50yum film sheets under the following conditions:

- temperature of the platelet: ²³⁰ ° C

- Extrusion screw rotation speed: 80 rpm

FEATURES OF THE FOLLOWING MOVIES TO BE MEASURED:

(a) elongation at break AR (expressed in%) in the longitudinal direction L and the lateral direction T, determined in accordance with ASTM D 882-67;

(b) the breaking resistance RD (expressed in grams) in the longitudinal direction L and the transverse direction T, determined in accordance with ASTM D 1922-67.

The results of these measurements are summarized in Table III, where Examples 9-11 show the copolymers of Examples 1-3 and Examples 12-14 correspond to the topopolymers of Examples 4, 5 and 7.

Table III

Example 9 10 11 12 13 14 L 750 635 635 630 910 760 AR T 860 805 610 660 1 060; 850 L 190 680 160 150 300 200 RD T 775 900 430 500 640 440

In addition, the foil of Example 10 exhibits an impact strength (measured according to NF T 54 109) of 300 g.

Otherwise, all the studied copolymers Mejia industrial applicability as defined tloušlku rtlo unožnuj ^ ^j C tlouělky continuous production sheet. 5 µm by latching for 2 hours without failure.

Example 15

The copolymer of Example 8 was extruded by coextrusion under the same conditions as the preform to a film of 50 µm thickness. The following properties of this film are measured:

- impact density: 400 g;

- longitudinal tear resistance: 600 g;

- lateral tear resistance: 800 g,

Example 16

The films obtained in Examples 10, 13 and 14 are subjected to optical properties measurements of brilliance (ASTM D-2457) and turbidity (ASTM D-1003). T ^y's properties Mejia expressed in percentage values given in Table IV;

Table IV

Foil Example 10 Example 13 Example 14 Br Hance 95 80 85 Haze 10.5 7 13

Claims (3)

OBJECT OF THE INVENTION CLAIMS 1. A process for the preparation of copolymers of ethylene-olefins containing at least 4 carbon atoms having a bulk density of 0.905 g / cm ³ , a mean content of olf-oleic units of 1 to 8 molar percent and a melt flow index of 0.2 to 12 dg / oin and heterogeneous. distribution and-SLF-amino-ACTIVE units in the copolymer containing a torystelické fraction and the crystalline fraction Gen single peak ^t EPLO ^t y ^th thereto between ¹¹⁶ and ^{1 30} ° C., and yet tfvu at 1 ^{20-5 0%} by weight of the total hmoonnoti copolymer , copolymerization of ethylene and α-olefins having at least 4 carbon Uhl ^Cart UVT ^l ESPO ^at one meter REA ^ oru containing ^t LESP ⁱⁿ one zone. at ^{180 F} e ² 0 3 ° C and a pressure of 30 to 250 MPa using a catalyst system Zieglerořa type, characterized in that the gas stream supplied DC reactor consists in steady state, between 10 to the 80th ethylene homogeneity and 20 to 90% α-olefin homoinnitine, using a catalyst system comprising an activator selected from the group of the eclipsing hydrides and organometallic compounds of groups I and III of the Periodic System and at least one halogenated transition metal compound of the formula (TiCl ₃₎ , 1/3 A1C1 ₃ ) (ΜΧ ₃ ) _χ (MgC ^ y in which. X is greater than or equal to 0.3 and less than or equal to 3, y is greater than or equal to 0 and less than or equal to 20, M is. a transition metal from the group of metals VB, VIB. and X is halogen, wherein the atomic ratio of the activator metal to the transition metal is 1 to 10. The mean residence time of the catalyst system in the polymerization reactor is 2 to 100 seconds. 2. Process according to claim 1, characterized in that the activator is a substance selected from the group consisting of trielkylelminine and alkylsiloxelanes. 3. The process of claim 1 wherein the copolymerization is carried out in the presence of at most 2 mole percent hydrogen.