FI79126B - A POLYMER BODY CONDITIONING FOR OVERSTREAM OF OILS, FOERFARANDE FOR DERAS FRAMSTAELLNING OCH DERAS TILLAEMPNING VID TILLVERKNING AV KABLAR FOER ELEKTRISK STROEM. - Google Patents

Abstract

1. Crosslinked material, having improved properties, obtained from copolymers of ethylene and of at least one alpha-olefine, characterized in that its gel factor is between about 95 and 99% and in that the said copolymers are chosen from amongst : (a) ethylene/propylene copolymers which comprise, if appropriate, up to 4 mol% of units derived from another alpha-olefine, have a density of between 0.905 and 0.930 g/cm**3 and a melt index of between about 0.4 and 3 dg/min, possessing from 32 to 62 methyl groups per 1,000 carbon atoms and are such that their density rho, expressed in g/cm**3 , and the proportion m of methyl groups therein are related to one another as follows : 0.9530 =< rho + 0.83 m =< 0.9568, (b) copolymers of ethylene and of at least one alpha-olefine containing at least 4 carbon atoms, the said copolymers having a density of between 0.905 and 0.940 g/cm**3 , a melt index of between 0.2 and 20 dg/min and an average proportion of alpha-olefine units of between 1 and 8 mol%, comprising crystalline fractions and amorphous fractions and having a heterogeneous distribution of the alpha-olefine units, and having a proportion of alpha-olefine units varying between 0.2 and 5 times their average proportion, depending on the fractions in question, (c) compositions comprising up to 40% by weight of an ethylene polymer prepared by free radical polymerization and at least 60% by weight of a copolymer of type (a) and/or of a copolymer of type (b), (d) copolymers of ethylene and of at least one alpha-olefine having from 3 to 12 carbon atoms, the said copolymers comprising from 0.5 to 10 mol% of units derived from the alpha-olefine, modified by the introduction of long-chain branches in such a quantity that their measured limiting viscosity is between 1.3 and 10 times their limiting viscosity calculated from the molecular weight distribution, (e) compositions comprising at least 60% by weight of at least one copolymer of type (a) and/or of type (b) and up to 40% by weight of an ethylene polymer having a specific gravity of between 0.956 and 0.970 and a melt index of between 0.1 and 1 dg/min, (f) compositions containing a mixture of at least one copolymer of type (a) and at least one copolymer of type (b), and (g) compositions containing several copolymers of type (b), more particularly several copolymers having markedly different melt indices, it being possible for the copolymers of types (a) and (b) to be obtained by copolymerization of ethylene and at least one alpha-olefine in at least one reactor comprising at least one zone, at a temperature of between 180 degrees and 320 degrees C and under a pressure of between 300 and 2,500 bars, by means of a Ziegler-type catalyst system comprising, on the one hand, at least one activator chosen from amongst the hydrides and organometallic compounds of the metals of groups I to III of the Periodic Table, and, on the other hand, at least one transition metal halogen.

Description

1 79126

Crosslinked polymer blends of ethylene and at least one olefin, method for their preparation and their application in the manufacture of electrically conductive cables

Tvärbundna polymeratblandningar av ethylen min minst en <= * - olefin, förfarande för deras framställning och derill till vidming with a switch for electric power

The invention relates to crosslinked polymer mixtures of ethylene and at least one α-olefin, to a process for their preparation and to their application in the manufacture of electrically conductive cables.

French Patent No. 2,432,535 discloses highly crosslinked polymer blends containing a linear copolymer of ethylene having a density before crosslinking of less than 0.940 g / cm 3 and less than 30 attached CH 3 groups / 1000 carbon atoms, with long chains practically absent. . The degree of crosslinking of these polymer blends, expressed as a gel ratio, is at least 40% and can be 95%.

U.S. Patent No. 3,105,057 discloses blends of a copolymer of ethylene and butene-1 containing 5 to 30% by weight of butene-1, a finely divided filler, and organic peroxide as a crosslinking agent. U.S. Pat. No. 3,173,903 discloses crosslinking of copolymers of ethylene and propylene having copolymers having a specific gravity of less than 0.92 and containing 7 to 20 mole percent propylene and prepared in a homogeneous liquid phase at a pressure of less than 100 bar and 85 ° C at a lower temperature with a mixture of peroxide and carbon black.

The applicant has found that replacing the materials known in the crosslinking process with a copolymer of ethylene and at least one 2 79126 ex'-olefin containing a large proportion of ethylene-derived units, as defined below, increases the gel ratio of the crosslinked polymer obtained.

The invention relates to crosslinked polymer blends with improved properties obtained from copolymers of ethylene and at least one cX olefin, characterized in that their gel ratio is between> 95 and 99%, and that these copolymers are selected from the following a) copolymers of ethylene and propylene, optionally containing up to 4 mol% of units derived from another o <.- olefin, which polymers have been prepared at a temperature of about 180 to 320 ° C and about 300 ... At a pressure of 2500 bar and having a polymer density in the range of 0.905 to 0.930 g / cm3 and a melt index in the range of about 0.4 to 3 dg / min, with 32 to 62 methyl groups / 1000 carbon atoms, and which are such that their density f *, expressed in g / cm3, and the number m of methyl groups in them are in the following proportions: 0,9530 <_ f * + 0,83 m 0,9568, (b) ethylene and at least one carbon-containing at least 4 carbon atoms οΖ-olefin mixed polymers which have been prepared at a temperature of about 180 to 320 ° C and a pressure of about 300 to 2500 bar and which have a density in the range from 0.905 to 0.940 g / cm3, a melt index in the range from 0.2 to 20 dg / min and the average content of α-olefin units is in the range of 1 to 8 mol%, and which contain crystalline fractions and amorphous fractions, and in which the ε-olefin units are heterogeneously distributed and in which the proportion of οί-olefin units varies within 0, 2 to 5 times their average proportion, depending on the fractions in question, 3 79126 and that they are crosslinked by reacting the copolymer with an amount of 0.5 to 2.5% by weight of the peroxy di compound.

The copolymers of type a) include other α-olefins and the α-olefins used to prepare the copolymers of type b) contain from 4 to 10 carbon atoms. They are selected, for example, from butene-1, 4-methylpentene-1, hexene-1, octene-1 and desene-1.

The copolymers of types a) and b) are preferably prepared by copolymerizing ethylene and at least one α-olefin in at least one reactor having at least one zone at a temperature in the range of 180 ° C to 320 ° C and a pressure in the range of 300 ° C. ..2500 bar, by means of a Ziegler-type catalyst system containing, on the one hand, at least one activator selected from the group consisting of hydrides and organo-metallic compounds of groups I to III of the Periodic Table and, on the other hand, at least one transition metal halide compound.

The molecular weight of the number of copolymers of type a) is in the range of 10,000 to 28,000 and the polydispersity index (the ratio of the weight average molecular weight to the number average molecular weight, both determined by gel permeation chromatography) is in the range of 7 to 14. They are preferably prepared by copolymerizing ethylene and propylene in at least one reactor with at least one zone, at a temperature in the range from 180 ° C to 320 ° C and at a pressure in the range from 300 to 2500 bar, in a Ziegler-type catalyst. by means of a system comprising on the one hand at least one activator selected from the group consisting of hydrides and organometallic compounds of groups I to III of the Periodic Table and on the other hand at least one transition metal halogen compound, the reactor feed stream containing 65 to 85% by weight in continuous operation ethylene and 15 ...

4 79126 35% by weight of propylene, and the transition metal halogen compound is a complex compound of the following formula (MCla) (MgX2) y - (AlCl3) z (RMgX) wherein M is a metal selected from titanium and vanadium, X is halogen, R is hydrocarbon radical 2 <ά <2, 2 <y <2Q, 0 <z <A / 3 and CKtKl.

The average molecular weight according to the number of copolymers according to type b) is preferably in the range from 15,000 to 60,000 and the polydispersity index is in the range from 3 to 9. Their crystalline fractions may have a single melting peak in the range of 118 ° C to 130 ° C, determined by differential thermal analysis, and may represent 20 to 50% by weight of the total weight of the copolymer of type b). The copolymers of type b) may have units derived from two o <.- olefins with corresponding average proportions of 0.25 to 4. In the latter cases, the polydispersity index of the copolymers of type b) is preferably in the range 6 to 12. Copolymers of type b) are preferably prepared by copolymerizing ethylene and at least one cX-olefin having at least 4 carbon atoms in at least one reactor with at least one zone at a temperature in the range of 180 to 320 ° C and a pressure of is in the range of 300 to 2500 bar by means of a Ziegler-type catalyst system comprising, on the one hand, an activator selected from the group consisting of hydrides and organo-metallic compounds of groups I to III of the Periodic Table and, on the other hand, at least one transition metal halogen compound, the metal in the activator the atomic ratio to the transition metal is in the range of 1 to 10, and the average residence time of the catalyst system in the polymerization reactor is in the range of 2 to 100 seconds, and the gas stream feeding to the reactor contains 10 to 80% by weight of ethylene and 20 to 90% by weight. o <-olefin, and the catalyst system has a high reactivity to ethylene greater than its reactivity to c <-olefins.

j

II

A non-limiting example of such a compound has the formula (TiCl 3, 1/3 AlCl 3) (MX 3) x (MgCl 2) y wherein 0.3 <.x <.3, 0 y _ <20, M is the group of the Periodic Table VB, VIB and VIII are a selected transition metal, and X is halogen. The composition of the gas stream fed to the reactor in continuous operation must be understood as the average composition throughout the reactor, bearing in mind that this composition is not necessarily uniform but may vary along the reactor, especially in the case where there are several zones. This composition varies depending on the nature of the cyolefin in question. Thus, for a binary copolymer, the proportion by weight of O <-olefin is preferably in the range of 15 to 70% for butene-1 and in the range of 35 to 90% for hexene-1. If the reactor used in the process of the invention comprises several zones, it is in most cases advantageous to spray the majority of the cy-olefins into the first zones operating at temperatures in the range of 180 to 240 ° C, while the last zone operates at a temperature in the range of 240 ° C. .320 ° C and is not sprayed with any significant amount of o <-olefins.

The crosslinked compositions of the invention may, as is known, contain fillers such as carbon black, metal oxides, carbonates or sulfates, antioxidants, lubricants and pigments.

They are prepared by reacting with ethylene copolymers used as starting materials and at least one olefin, a peroxide compound selected from benzoyl peroxide, dicumyl peroxide, 1,3-bis- (tert-butylperoxyisopropyl) -benzene, ditert-butylperoxide, amyl peroxide, lauroyl peroxide and mixtures thereof, in an amount of 0.5 to 2.5% by weight based on the weight of the crosslinkable polymer.

6 79126

Crosslinking is usually performed at 180-250 ° C for 5-20 minutes. It can be performed under pressure or in molten salt baths.

The crosslinked mixtures according to the invention are preferably used in the manufacture of electrically conductive cables.

The following non-limiting examples are intended to illustrate the invention. All parts are by weight unless otherwise indicated.

The following measurements are made for crosslinked mixtures: the proportion of insoluble materials (gel ratio) is determined according to ASTM D 2765/72, expressed as a percentage by weight, the creep ratio is determined according to UTE Standard Specification 33 209 and the percentage elongation at break EB is determined according to NFC-Standard-Specifica expressed as a percentage, the percentage residual elongation is determined according to HN Standard Specification 33523 and CEI Standard Specification 538.

Example 1 A copolymer of ethylene and propylene of type a) having the following properties was used: E = 0.905 g / cm 3 MI = 3 dg / min mol% of propylene units = 12 number of methyl groups = 60/1000 carbon atoms.

The copolymer was prepared by copolymerizing ethylene and propylene in a cylindrical autoclave reactor with an operating pressure of 1200 bar and an internal stirrer and metal screens forming three zones of equal volume 7,79,126. Zone 1 was maintained at 220 ° C and fed a stream of 40 kg / h ethylene and 30 kg / h propylene. A catalyst system comprising purple titanium trichloride T1Cl3- (1/3) AlCl3 on the one hand and aluminum trioctyl on the other hand was added to the zone to such an extent that the atomic ratio Al / Ti was 3. The zone was maintained at 240 ° C and fed with a stream of 20 kg / h ethylene but no catalyst. Zone 3 was maintained at 260 ° C and fed with a stream of 20 kg / h ethylene and a catalyst system of a complex of TiCl 3 (1/3) AlCl 3, 6 MgCl 2 prepared by grinding purple titanium trichloride and anhydrous magnesium chloride, on the one hand, and dimethylethyldiethylsiloxalane, on the other hand, to such an extent that the atomic ratio Al / Ti was 3. The reaction mixture containing the copolymer was removed from the starting end of zone 3 to a separation and recycle apparatus. The copolymerization was performed in the presence of 0.1% by volume of hydrogen.

100 parts of the obtained copolymer and 50 parts of carbon black were mixed in a mixer for 3 minutes at 80 ° and then 1 part of 2,2,4-trimethyl-1,2-dihydroquinoline polymer (oxidation inhibitor A) was added in a mixer at 120 ° C for 5 minutes. ) and 5 parts (1,3-phenylene-bis- (1-methyl-ethylidene)) - bis- (1,1-dimethylethyl) -peroxide) (peroxide P) containing 40% by weight of active substance, that is, 2 parts of pure peroxide.

The resulting mixture was crosslinked at 35 bar for 12 minutes at 180 ° C.

The percentages of insoluble materials were measured within 12 minutes after crosslinking at 180 ° C, the creep ratio was measured at 150 ° C for 15 minutes at 2, 4 and 7 bar and the percentage residual elongation was measured. The length of time t required to reach 90% crosslinking at 185 ° C (using an I.F.C type M.I.E optimizer) was also measured in seconds.

Example 2 A heterogeneous copolymer of ethylene and butene-1 of type b) was used, the properties of which were as follows: P = 0.918 g / cm 2 MI = 0.8 dg / min mol% of butene-1 units = 3, 4%

number average molecular weight = 43,000 polydispersity index = Mw / Mn = 3.6 number of side methyl groups = 17/1000 carbon atoms melting point of crystalline fraction = 122 ° C

heterogeneity of the butene-1 distribution = 0.5 times ... 2.2 times the mean amount, depending on the fractions in question.

This copolymer was prepared in a cylindrical autoclave reactor with an operating pressure of 900 bar and an internal stirrer and metal screens delimiting the three zones. The volume of zone 1, which was maintained at 210 ° C, was twice the volume of both subsequent zones, and a mixture of 36% by weight of butene-1 and 64% by weight of butene-1 was fed to this zone. % ethylene and a catalyst system comprising dimethylethyldiethylsiloxalane on the one hand and a compound of formula TiCl3.1 / 3AlCl3 on the other hand in such an amount that the atomic ratio Al / Ti was = 3. Zone 2 maintained at 240 ° C was fed with a flow of 55 kg / h the same mixture as above and the same catalyst system. Finally, zone 3, from the exit end of which the copolymer-containing reaction mixture was removed to a separation and recycle apparatus, was maintained at 280 ° C and no monomer or catalyst was fed into it. The average residence time of the catalyst system in the reactor was 43 seconds.

The resulting copolymer was crosslinked under the conditions of Example 1.

Example 3 A terpolymer of ethylene, propylene and butene-1 of type a) was used, prepared under the conditions of Example 1, in which part of the propylene gas stream was replaced by butene-1. The properties of this terpolymer were as follows: ^ = 0.906 g / cm3

MI = 0.7 dg / min mole% of propylene units = 7 mole% of butene-1 units = 2.4 proportion of side alkyl groups 47/1000 C

This terpolymer was crosslinked under the conditions of Example 1,

The results of the measurements related to Examples 1 ... 3 are shown in Table I.

Table I

Solubility-Creep ratio 150 ° C: Residual elongation% in mats, 15 min.

Eg t material. 247 bars 247 bars. share 1,250 96 4 8 28 0 8 28 2 192 97.8 0 12 12 0 0 12 3 184 97 088 084 10 791 26

Examples 4 and 5

The copolymer described in Example 2 and the terpolymer described in Example 3j were crosslinked under the following conditions:

In the mixer, 100 parts of polymer were mixed for 5 minutes at 120 ° C, 0.55 parts of antioxidant A and 32 parts of peroxide (P), titration with 40% of active material (i.e. 1.28 parts of pure peroxide P). The mixture was crosslinked at 35 bar for 12 minutes at 180 ° C.

The results of the measurements are shown in Table II.

Table II

Solubility-Creep ratio 150 ° C: Residual elongation% in mats, 15 min.

Eg t material. 2 4 bars 2 4 Bars.

share 4,186 97.3 4 24 04 5 182 95.7 8 20 00

Examples 6 and 7

To 100 parts of the copolymer of type a) described in Example 1 under the conditions of Examples 4 and 5 were added 0.5 part of antioxidant A and the amounts of pure peroxide P mentioned by weight in Table III.

Crosslinking was performed at 180 ° C with a contact time of 12 minutes. The properties of the obtained crosslinked compounds were measured. The creep was measured at a pressure of 2 bar at 200 ° C.

The results of the measurements are shown in Table III.

11 79126

Table III

the dissolution

Non-Peroxified Creep Fractures

Eg slide P material. ratio% elongation% t share 6 0.935 96.6 15 688 223 7 1.25 98.2 10 602 214 l

Claims (11)

12,791 26 Crosslinked polymer blends with improved properties obtained from copolymers of ethylene and at least one Ctf olefin, characterized in that their gel ratio is between> 95 and 99%, and that these copolymers are selected from a) copolymers of ethylene and propylene , possibly containing not more than 4 mol% of units derived from another O <-olefin, polymers prepared at a temperature of about 180 to 320 ° C and a pressure of about 300 to 250 ° C and with a density of polymers in the range 0.905 to 0.930 g / cm3 and a melt index in the range of about 0.4 to 3 dg / min with 32 to 62 methyl groups / 1000 carbon atoms and such that their density p, expressed as g / cm3, and the number m of methyl groups in them is in the following ratio: 0.9530 £ p + 0.83 m 0.9568, b) copolymers of ethylene and at least one O <-olefin containing at least 4 carbon atoms, which polymers are prepared planted at a temperature of about 180 to 320 ° C and a pressure of about 300 to 2500 bar and having a polymer density in the range of 0.905 to 0.940 g / cm3, a melt index in the range of 0.2 to 20 dg / min, and The average proportion of Q <.olefin units is in the range of 1 to 8 mol%, and which contain crystalline fractions and amorphous fractions, and in which the <<-olefin units are heterogeneously distributed, and in which the proportion of 0 <-olefin units varies within the range 0, 2 to 5 times their average proportion, depending on the fractions in question, and that they are crosslinked by reacting the copolymer with an amount of 0.5 to 2.5% by weight of the peroxy di compound. 13,791 26 Mixtures according to Claim 1, characterized in that (X-olefin contains 4 to 10 carbon atoms. Mixtures according to Claim 1 or 2, characterized in that the molecular weight according to the number of copolymers of type a) is from 10,000 to 28,000. Mixtures according to Claim 1 or 2, characterized in that the average molecular weight according to the number of copolymers of type b) is from 15,000 to 60,000. Mixtures according to one of Claims 1 to 3, characterized in that the copolymers of type a) have a polydispersity index of 7 to 14. Mixtures according to one of Claims 1, 2 and 4, characterized in that the copolymers of type b) have a polydispersity index of 3 to 9. Mixtures according to one of Claims 1, 2, 4 or 6, characterized in that the crystalline fractions of the copolymers of type b) have a single melting peak in the range from 118 to 130 ° C and represent 20 to 50 % by weight of the total amount of copolymer of type b). Mixtures according to one of Claims 1, 2, 4, 6 or 7, characterized in that the copolymers of type b) contain units derived from two o <-olefins having respective mean proportions of 0.25. . . 4. Mixtures according to Claim 8, characterized in that the copolymers of type b) have a polydispersity index of 6 to 12. i4 791 26 Process for the preparation of mixtures according to one of Claims 1 to 9, characterized in that the peroxide compound acts on the copolymer of ethylene and at least one o-olefin in an amount of 0.5 to 2.5 parts by weight of the copolymer. 100 parts by weight. Application of mixtures according to one of Claims 1 to 9 for the production of electric cables.