Process for the polymerization of olefins
Abstract
ETHYLENE POLYMER WITH AN INFLATION COEFFICIENT (T {SUB, G}) OF AT LEAST 1.4. A LOW TENSION FISSURE RESISTANCE (ESCR) OF AT LEAST 55 H AND A FLUIDITY INDEX (ML {SUB, 5}) OF AT LEAST 0.2G / 10 MIN. PROCEDURES FOR OBTAINING THIS ETHYLENE POLYMER THROUGH DIFFERENT CATALYTIC SYSTEMS, THE FIRST BASED ON TITANIUM AND ZIRCONIUM CARRIED OUT THROUGH POLYMERIZATION IN TWO REACTORS; THE SECOND CONSTITUTED BY A MIXTURE OF A CATALYST OF TITANIUM AND A CATALYST OF TITANIUM AND ZIRCONIUM, CARRIED OUT THROUGH POLYMERIZATION IN TWO REACTORS; THE THIRD CHROME BASED ON A SUPPORT THAT INCLUDES AT LEAST TWO CHOSEN CONSTITUENTS BETWEEN SILICE, ALUMINA AND ALUMINUM PHOSPHATE, CARRIED OUT THROUGH POLYMERIZATION IN ONE OR TWO REACTORS.
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14 claims: 1 independent, 13 dependent
- 1ES 2 138 286 T3 REIVINDICACIONES 1. Polámero de etileno elegido entre los homopolámeros y los copolámeros de etileno que constan, como maáximo, de 5 % en peso de como- 5 noámero que presenta una tasa de hinchamiento (TG) de al menos 1,4, una resistencia a la fisuraciáon bajo tensioán (ESCR) de al menos 55 h y un ándice de fluidez (MI5) de al menos 0,2 g/10 minutos. 10
- 2Polámero de etileno seguán la reivindicacioán 1, que presenta un ándice de fluidez (MI5) expresado en g/10 minutos y una viscosidad dinaámica η expresada en dPa.s y medida a un gradiente de velocidad de 100 s -1 , a 190°C, que responde a la 15 relaciáon log (177470/MI 5 ) - log η 2 - log (2,53 x MI 5 ) 0,55
- 3Polámero de etileno seguán la reivindicacioán 1áo 2, que presenta una masa voluámica estáandar de al menos 945 kg/m 3 .
- 4Polámero de etileno seguán la reivindicaciáon 3, que presenta una masa voluámica estaándar de 952 a 958 kg/m 3 .
- 5Polámero de etileno seguán una cualquiera de las reivindicaciones 1 a 4, que contiene 0,1 a 5% en peso de comonoámero elegido entre buteno, hexeno y sus mezclas.
- 6Procedimiento de preparacioán del polámero de etileno, de acuerdo con una cualquiera de las reivindicaciones 1 a 5, seguán el cual se polimeriza etileno eventualmente con uno o varios comonoámeros, en dos reactores en serie, en presencia de un sáolido catalático que contiene titanio y circonio, en una relacioán molar Zr/Ti de al menos 2 y de un cocatalizador, estando alimentado el primer reactor con etileno, eventualmente con comonáomero y/o con hidráogeno, con sáolido catalático y con cocatalizador, transfiriáendose el medio de reacciáon del primer reactor al segundo reactor, y estando, ademáas, el segundo reactor alimentado con etileno, eventualmente con comonáomero y/o con hidráogeno.
- 7Procedimiento seguán la reivindicaciáon 6, en el cual el sáolido catalático estaá constituido esencialmente por 0,5 a 10% en peso de titanio, 5 a 40 % en peso de circonio, 20 a 80 % en peso de haláogeno, 1 a 30 % en peso de magnesio y 0,5 a 10% en peso de aluminio.
- 8Procedimiento de preparaciáon del polámero de etileno, de acuerdo con una cualquiera de las reivindicaciones 1 a 5, seguán el cual se polimeriza etileno eventualmente con uno o varios comonoámeros, en dos reactores en serie, en presencia de un primer soálido catalático que contiene titanio como uánico elemento activo, de un segundo sáolido catalático que contiene titanio y circonio como elementos activos, y de un cocatalizador, estando alimentado el primer reactor con etileno, eventualmente con comonáomero y/o con hidráoge20 no, con el primero y segundo sáolidos cataláticos y con cocatalizador, transfiriáendose el medio reaccionante del primer reactor al segundo reactor, y estando el segundo reactor alimentado, ademáas, con etileno, eventualmente con comonáomero y/o con hidráogeno.
- 9Procedimiento seguán la reivindicacioán 8, en el que el primer sáolido catalático estáa constituido esencialmente por 10 a 30 % en peso de titanio, 20 a 60 % en peso de haláogeno, 0,5 a 20 % en peso de magnesio y 0,1 a 10% en peso de aluminio, y el segundo soálido catalático estaá constituido esencialmente por 0,5 a 10% en peso de titanio, 5 a 40 % en peso de circonio, 20 a 80 % en peso de haláogeno, 1 a 30 % en peso de magnesio y 0,5 a 10% en peso de aluminio.
- 10Procedimiento seguán una cualquiera de las reivindicaciones 6 a 9, en el que se utiliza un sáolido catalático que se prepara haciendo reaccionar, en una primera etapa, un compuesto oxigenado orgaánico de magnesio con un compuesto oxigenado orgaánico de titanio, y, llegado el caso, con un compuesto oxigenado orgáanico de circonio, hasta la obtencioán de un complejo láquido, y tratando el citado complejo láquido, en una segunda etapa, mediante un compuesto oárgano-alumánico halogenado de fáormula general AlRnX3-n en la que R es un radical hidrocarbonado, X es un haloágeno y n es inferior a 3, para precipitar el complejo láquido dando un complejo catalático sáolido.
- 11Procedimiento de preparacioán del polámero de etileno, de acuerdo con una cualquiera de las reivindicaciones 1 a 5, seguán el cual se polimeriza el etileno, eventualmente con uno o varios comonáomeros, en un solo reactor, en presencia de un sáolido catalático que contiene cromo sobre un soporte que posee al menos dos constituyentes elegidos entre sálice, aluámina y fosfato de aluminio, eventualmente en presencia de un cocatalizador y/o de hidroágeno.
- 12Procedimiento de preparaciáon del polámero de etileno, de acuerdo con una cualquiera de las reivindicaciones 1 a 5, seguán el cual se polimeriza el etileno eventualmente con uno o varios comonoámeros, en dos reactores dispuestos en serie, en presencia de un sáolido catalático que contiene cromo sobre un soporte que posee al menos dos constituyentes elegidos entre sálice, aluámina y fosfato de aluminio, y de un cocatalizador, estando el primer reactor alimentado con etileno, eventualmente con comonáomero y/o con hidráogeno, con sáolido catalático, transfiriáendose el medio de reacciáon del primer reactor al segundo reactor, estando, ademáas, el segundo reactor alimentado con etileno y eventualmente con comonáomero y/o con hidroágeno, y estando presente el cocatalizador en al menos uno de los dos reactores.
- 13Procedimiento seguán la reivindicacioán 11 oá 12, en el que el sáolido catalático contiene 0,05 a 10% en peso de cromo y el soporte contiene sálice (X), aluámina (Y) y fosfato de aluminio (Z), en un porcentaje molar (X):(Y):(Z) igual a (10 ES 2 138 286 T3 a 95):(1 a 80):(1 a 85).
- 14Procedimiento seguón una cualquiera de las reivindicaciones 11 a 13, en el cual el cocatalizador es un trialquil-boro y el radical alquilo contiene hasta 20 óatomos de carbono. NOTA INFORMATIVA:Conforme a la reserva del art. 167.2 del Convenio de Patentes Europeas (CPE) y a la Disposición Transitoria del RD 2424/1986, de 10 de octubre, relativo a la aplicacion del Convenio de Patente Europea, las patentes europeas que designen a España y solicitadas antes del 7-10-1992, no producirán ningún efecto en Espana en la medida en que confieran proteccion a productos quámicos y farmaceuticos como tales. Esta informacioán no prejuzga que la patente estáeo no incluáda en la mencionada reserva.
Independent claims14
171 paragraphs in 4 sections, as filed
IS 2 138 286 T3
DESCRIPTION
Ethylene polymer and procedures to obtain it.
The present invention relates to ethylene polymers that have an advantageous combination of characteristics that make them particularly suitable for their preparation by extrusion and by blown extrusion, with a view to the manufacture of articles (for example tubes) that have excellent mechanical properties and especially high resistance to stress cracking. The invention also relates to various processes for obtaining these ethylene polymers.
It is generally known that resins exhibiting high viscosity versus elongation (resulting in a high swelling rate) lend themselves particularly well for extrusion and blown extrusion preparation. For example, Belgian patent BE 840378 (SOLVAY & CIE) describes polyethylenes obtained by polymerization in a single reactor, in the presence of a catalytic solid that is prepared by reacting an organic magnesium oxygen compound with an organic titanium oxygen compound and a compound orgaonic oxygenation of zirconium, and then treating the reaction product obtained with an aluminum halide. Known polyethylenes have a high swelling rate. However, their mechanical properties are such that the resistance to stress cracking of tubes extruded from these polyethylenes is low.
On the other hand, polyethylenes with improved mechanical properties and in particular with high resistance to cracking under stress are known. For example, patent application EP 603935 (SOLVAY) reports on ethylene polymers obtained by polymerization in at least two reactors in series, in the presence of a titanium catalyst. The ethylene polyomers thus obtained show good mechaonic properties (high resistance to cracking under stress). However, ethylene polyomers have a low swelling rate.
The present invention tries to remedy the aforementioned drawbacks, supplying a new ethylene polymer that exhibits, at the same time, a high swelling rate and a high resistance to cracking under stress, which turn out to be particularly good for preparation by extrusion and for blown extrusion.
Consequently, the invention relates to an ethylene polymer exhibiting a swelling rate (TG) of at least 1.4, a resistance to stress cracking (ESCR) of at least 55 h and a flow onyx (MI5) of at least 0.2 g / 10 min.
One of the essential characteristics of the ethylene polymer according to the invention resides, therefore, in the combination of a high swelling rate with a high resistance to cracking under stress.
The swelling rate of the ethylene polymer according to the invention is measured by extruding, at 190 ° C and at a speed gradient of 100 s<sup>-1</sup>, the ethylene polymer through a 30 mm long, 2 mm diameter die, at a constant extrusion speed, and measuring the piston displacement necessary to extrude a 70 mm spindle length. The swelling rate is defined by the relation T<sub>G</sub> = 0.5707 yfe, where e represents the piston displacement, expressed in mm. The cylinder and piston of the rheometer used for this measurement meet the criteria used for the measurement of the fluidity onyx, according to the ASTM D1238 (1986) standard.
The resistance to cracking under stress of the ethylene polymer is measured according to the following procedure. Ten plates of dimensions 125 mm x 12.7 mm x 3.2 mm are compressed from a sheet of ethylene polymer. Two notches are made, the first at 60 mm from one end of the plate and the second at 15 mm from the other end of said plate. The notched plates are subjected to a constant bending force of 7.36N, which corresponds to a tension lower than the tension at the threshold of plaostic flow, and they are simultaneously immersed in a surfactant solution consisting of 3 ml of nonylphenoxy-poly ( ethyleneoxy) ethanol per liter of water, at a temperature of 60<sup>°</sup>C. The time at the end of which the specimens break is noted and the mean time corresponding to the failure of 50% of said specimens is calculated.
For the purposes of the present invention, ethylene homopolymers are designated by "ethylene polymers", as well as ethylene copolymers with at least one comonomer. Ethylene copolyomers are the most advantageous. Examples of comonomers include alpha-olefins containing 3 to 8 carbon atoms. Butene, hexene, and their mixtures are preferred. The comonomer content in the ethylene polymer is generally at least 0.1% by weight, in particular at least 0.5% by weight, with values of at most 1% by weight being favorable. The comonomer content is at most 5% by weight.
The ethylene polyomers according to the invention usually have a flow rate, measured at 190<sup>°</sup>C under a load of 5 kg, according to ASTM D 1238 - Condition P (1986) (hereinafter referred to as MI5) at least equal to 0.3 g / 10 min, in particular at least equal to 0.6 g /10 minutes. MI5 does not, in general, exceed 10 g / 10 min, being the most frequent 5 g / 10 min, and more especially 2 g / 10 min.
The ethylene polyomers according to the invention, which are preferred, are further characterized by a dynamic viscosity η, expressed in dPa.s and measured at a speed gradient equal to 100 s<sup>-1</sup>, to 190<sup>°</sup>C, such that the relation log (177470 / MI<sub>5</sub>) - log η
- log (2.53 x MI<sub>5</sub>) is at least equal to 0.55. Preferably, this ratio is at least 0.59, with values at least equal to 0.61 being particularly advantageous. In most cases, this ratio is at most 0.73, and the most common is for it to be at most 0.70.
Ethylene polyomers according to the invention
ES 2 138 286 T3 currently have a standard volume mass (or density) measured according to ISO 1183 (1987), at least equal to 945 kg / m<sup>3</sup>, in particular at least equal to 950 kg / m<sup>3</sup>with values of at least 952 kg / m being preferred<sup>3</sup>. The standard volumetric mass does not generally exceed 965 kg / m<sup>3</sup>, more precisely 960 kg / m<sup>3</sup>with values of a maximum of 958 kg / m being more preferred<sup>3</sup>.
The invention also relates to various processes for the preparation of the ethylene polymer described above.
In a first process for the preparation of ethylene polymer according to the invention, a catalytic solid containing titanium and zirconium as active elements is used in a polymerization in two reactors arranged in series.
The first preparation process consists, more particularly, in polymerizing ethylene optionally with one or more comonoamers, in two reactors in series, in the presence of a catalytic solid containing titanium and zirconium, in a Zr / Ti molar ratio at least equal to 2, and a cocatalyst, the first reactor being fed with ethylene, possibly with comonaomer and / or with hydrogen, with catalytic solid and with cocatalyst, the reaction medium being transferred from the first reactor to the second reactor, the second reactor being also fed with ethylene and optionally with comonoamer. Preferably, hydrogen is introduced into at least one of the two reactors.
The catalytic solid used in the first process according to the invention advantageously consists of 0.5 to 10% by weight of titanium (preferably 1 to 6% by weight), 5 to 40% by weight of zirconium (preferably 10 to 25% by weight). by weight), the Zr / Ti molar ratio being at least 2.0 to 80% by weight of halogen (preferably 40 to 60% by weight), 1 to 30% by weight of magnesium (preferably 5 to 15 % by weight), and 0.5 to 10% by weight of aluminum (preferably 1 to 3% by weight). The remainder is made up of residual organic groups that come from the reagents used, in particular alkoxy and alkyl groups. The halogen is preferably chlorine.
The Zr / Ti ratio in the catalytic solid is preferably at least 2.5, with values of at least 3 being particularly preferred. The Zr / Ti ratio does not frequently exceed 10, more precisely 8, preferring values that are at most equal to 6.
In a second procedure for preparing the ethylene polymer according to the invention, a mixture of two catalytic salts is used, the first containing a single active element, namely titanium, and the second two active elements, namely titanium and zirconium, in a polymerization. in two reactors in series, and a cocatalyst, the first reactor being fed with ethylene, optionally with comonoamer and / or hydrogen in the first and second catalytic salts, and with cocatalyst, the reaction medium being transferred from the first reactor to the second reactor, and the second reactor being fed with ethylene and optionally with comonaomer and / or with hydrogen.
The second process for preparing the ethylene polymers according to the invention consists, more particularly, in polymerizing ethylene, optionally with one or more comonoamers, in two reactors in series, in the presence of a first catalytic solid consisting essentially of 10 to 30% by weight of titanium, 20 to 60%. by weight of halogen, 0.5 to 20% by weight of magnesium, and 0.1 to 10% by weight of aluminum; of a second catalytic solid consisting essentially of 0.5 to 10% by weight of titanium, 5 to 40% by weight of zirconium, 20 to 80% by weight of halogen, 1 to 30% by weight of magnesium and 0.5 to 10% by weight of aluminum. Preferably, hydrogen is introduced into at least one of the two reactors.
The two catalytic solids can optionally be mixed, prior to execution, in the polymerization process. The premixing is then advantageously carried out at room temperature.
Preferably, the first catalytic solid consists essentially of 15 to 20% by weight of titanium, 30 to 50% by weight of halogen, 1 to 10% by weight of magnesium and 0.5 to 5% by weight of aluminum. The solid is made up of residual organic groups that come from the reagents used, in particular from alkoxy and alkyl groups. Halogen is usually chlorine.
Most often, the second catalytic solid is essentially made up of 1 to 6% by weight of titanium, 10 to 25% by weight of zirconium, 40 to 60% by weight of halogen, 5 to 15% by weight of magnesium and 1 to 3% by weight of aluminum. The remainder is made up of residual organic groups that come from the reagents used, in particular from the alkoxy and alkyl groups. In most cases the halogen is chlorine.
In the second procedure, following the invention, the two catalytic salts are generally used in amounts such that the molar ratio between the titanium that comes from the first catalytic solid and the titanium that comes from the second catalytic solid is at least equal to 1, in particular at least equal to 1.25, with values of at least 1.50 being preferred. The ratio is usually a maximum of 10, more specifically a maximum of 5, with values of a maximum of 4 being preferred.
The cocatalyst used in the first or second process can be any cocatalyst known in the art, especially organo-alumina compounds. Examples include trialkyl aluminum, in particular those in which the alkyl group consists of up to 20 carbon atoms (preferably 2 to 8 carbon atoms), such as triethyl aluminum and triisobutyl aluminum. Triethylaluminum is preferred.
According to a particular embodiment, the catalytic solid (s) used in the first and second procedures for the preparation of ethylene polymers according to the invention, are prepared by reacting, in a first stage, an organic magnesium oxygenate compound with an oxygenated compound. organic titanium, and, if necessary, with an organic zirconium oxygenated compound, until obtaining a liquid complex, and treating said liquid complex, in a second stage, by means of a halogenated organoaluminum compound, of the formula
ES 2 138 286 T3 general AlRnX3-n in which R is a hydrocarbon radical, X is a halogen and n is less than 3, to precipitate the liquid complex as a catalytic solid.
For the purposes of the present invention, "organic magnesium oxygenates" are designated as compounds that consist of at least one sequence of magnesium-oxygen-organic radical bonds per magnesium atom. The organic radical generally contains up to 20 carbon atoms and, particularly, up to 10 carbon atoms, preferably 2 to 6 carbon atoms. The organic radical can be chosen from alkyl radicals (linear or branched), alkenyl, aryl, cycloalkyl, aryl-alkyl, alkylaryl, acyl and their substituted derivatives. The best results are obtained with magnesium alcioxides. Magnesium dialkoxides are preferred, particularly magnesium diethylate.
By "organic oxygenated titanium or zirconium compounds" are meant compounds which possess at least one sequence of titanium (or zirconium) -oxygen-organic radical bonds per titanium or zirconium atom. The organic radical is in accordance with those defined above for the organic magnesium oxygenates. Tetravalent titanium or zirconium compounds are preferably used. Among the organoxygenated titanium or zirconium compounds, mention may be made of alkoxides, phenoxides, oxyalkoxides, condensed alkoxides, carboxylates and enolates. The best results are obtained with alkoxides. Preferred are titanium or zirconium tetracioxides, in particular titanium or zirconium tetrabutylate.
The first stage of preparation of the catalytic solid (s) consists of preparing a liquid complex, by reacting the organic oxygen compound of magnesium with the organic oxygen compound of titanium and, when the catalytic solid also contains zirconium, with the organic oxygen compound of zirconium. . The reaction can be carried out in the presence of a diluent. The diluent is generally chosen from linear or branched alkanes or cycloalkanes containing up to 20 carbon atoms. Hexane is very suitable.
The amount of the organic titanium oxygenate used is, in general, at least 0.01 moles of titanium per mole of magnesium used, in particular at least 0.02 moles, values of at least 0.05 moles being preferred. The amount is usually at most 20 moles of titanium per mole of magnesium used, more precisely, at most 10 moles, with values equal to a maximum of 5 moles being preferred. The amount of organic zirconium oxygenate used then depends on the desired Zr / Ti molar ratio.
The second stage of preparation of the catalytic solid (s), which is called the precipitation stage, has the function of reducing the valence of the transition metal and, simultaneously, halogenating the organic oxygen compound of magnesium, the organic oxygen compound of titanium and, arrived the case, the organozirconium oxygenated compound, that is, replacing the alkoxy groups present in these compounds with halogens, so that the liquid complex obtained at the end of the first stage precipitates as a catalytic solid. The reduction and halogenation are carried out simultaneously by means of the halogenated mineral-aluminum compound that acted as a reducing-halogenating agent that causes the precipitation of a catalytic solid.
The treatment by means of the halogenated organoaluminum compound, in the precipitation stage, was carried out by contacting the liquid complex from the first stage with the halogenated organoaluminum compound, and preferably, progressively adding the halogenated organoaluminum compound to the liquid complex. .
The halogenated oregano-aluminum compound responds advantageously to the formula AlRnX3-n in which R is a hydrocarbon radical containing up to 20 carbon atoms and, preferably, up to 6 carbon atoms. The best results are obtained when R represents an alkyl radical, linear or branched. X is generally chlorine. Preferably n does not exceed 1.5, especially 1. Ethyl aluminum dichloride or isobutyl aluminum dichloride is preferred.
The amount of halogenated oregano-aluminum compound that is used is, in general, at least 0.5 moles of aluminum per mole of titanium and zirconium used, preferably at least 1 mole, the most common being values of at least 2 moles. ; it is generally a maximum of 50 moles of aluminum per mole of titanium and zirconium used, in particular not more than 30 moles, values equal to a maximum of 20 moles being advantageous.
At the end of the stage of precipitation of the liquid complex, by means of the halogenated organoaluminum compound, a catalytic solid consisting of a homogeneous precipitate is collected (the constituents are co-precipitated from a liquid complex) of an essentially amorphous mixture of a magnesium halide, a titanium halide and, where appropriate, a zirconium halide and, optionally, partially reduced and / or partially halogenated compounds. They are chemically bonded complexes, products of chemical reactions, and not the result of mixtures or adsorption phenomena. Indeed, it is impossible to dissociate one or the other of the constituents of these complexes using purely physical separation methods.
The catalytic solid containing titanium and zirconium, obtained according to the particular method of preparation described above, also allows, when used in an olefin polymerization process in two reactors in series, to obtain polyolefins other than ethylene polymers according to the invention. . Since then, the invention also relates to a process for the polymerization of olefins, according to which the olefin is polymerized, optionally with one or more comonomers, in two reactors in series, in the presence of a catalytic solid containing titanium and zirconium in a ratio. Zr / Ti molar of at least 2, and a cocatalyst, the first reactor being fed with olefin and optionally with comonoimer and / or hydrogen, with catalytic solid and with cocatalyst, transferring the
ES 2 138 286 T3 reaction medium from the first reactor to the second reactor, and the second reactor being fed, in addition, with olefin and optionally with comonomer and / or hydrogen. The catalytic solid is prepared by reacting, in a first stage, an organic magnesium oxygenate with an organic titanium oxygenate and with an organic zirconium oxygenate, until a liquid complex is obtained, and treating said liquid complex, in a second stage, by means of a halogenated organo-alumino compound, of the general formula AlRnX3-n, in which R is a hydrocarbon radical, X is a halogen and n is less than 3, to precipitate the liquid complex, giving a solid catalytic complex. The process makes it possible to obtain, with high productivity, particularly homogeneous polymers.
The olefin can be chosen from olefins containing 2 to 20 carbon atoms, and preferably 2 to 6 carbon atoms, such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene. Ethylene, 1-butene and 1-hexene are suitable. Ethylene is particularly preferred. The comonoamer can be chosen from the olefins mentioned above and from the diolefins containing 4 to 20 carbon atoms. Of course, the comonoamer introduced into the second reactor may be different from that which is introduced into the first reactor.
The mixture of the two catalytic salts used in the second process for preparing an ethylene polymer according to the invention can also be used in other olefin polymerization processes, in a single reactor or in two reactors arranged in series. The invention then relates to a catalytic system for olefin polymerization consisting of:
(a) a first catalytic solid consisting essentially of 10 to 30% by weight of titanium, 20 to 60% by weight of halogen, 0.5 to 20% by weight of magnesium and 0.1 to 10% by weight of aluminum ;
(b) a second catalytic solid consisting essentially of 0.5 to 10% by weight of titanium, 5 to 40% by weight of zirconium, 20 to 80% by weight of halogen, 1 to 30% by weight of magnesium and 0 , 5 to 10% by weight of aluminum, <sup>Y</sup> (c) a cocatalyst.
The use of a mixture of two catalytic salts allows the properties of the polymer obtained to be modified very quickly, adjusting the composition of the aforementioned mixture,
In a third process for preparing ethylene polymers according to the invention, a catalytic solid containing chromium is used as an active element on a support.
The third procedure for preparing the ethylene polymer according to the invention consists, more particularly, in polymerizing the ethylene optionally with one or more comonaomers, in a single reactor, in the presence of a catalytic solid containing chromium on a support that has at least two constituents chosen from salyx, alumina and aluminum phosphate, optionally in the presence of a cocatalyst and / or hydrogen.
A fourth procedure for preparing the ethylene polymer according to the invention consists of polymerizing ethylene, possibly with one or more comonomers, in two reactors arranged in series, in the presence of a catalytic solid containing chromium on a support consisting of at least two constituents chosen from salyx, alumina and aluminum phosphate, and a co catalyst, the first reactor being fed with ethylene, optionally with comonaomer and / or with hydrogen, and with catalytic solid, the reaction medium being transferred from the first reactor to the second reactor, and the second reactor being fed with ethylene and eventually with comonaomer and / or with hydrogen, and the cocatalyst being present in at least one of the two reactors. The cocatalyst is advantageously used only in the second reactor.
The catalytic solid used in the third and fourth processes for the preparation of ethylene polymers according to the invention can be obtained, in a known way, by impregnating the support powder with an aqueous or organic solution of a chromium compound, followed by drying in oxidizing atmosphere. A chromium compound chosen from soluble salts such as oxides, acetate, chloride, sulfate, chromate and dichromate in aqueous solution, or such as acetyl acetonate in organic solution, can be used for this. After impregnation of the support with the chromium compound, the impregnated support is usually activated, heating it at a temperature of 400 to 1000 ° C, to transform at least a part of the chromium into hexavalent chromium. The catalytic solid according to the invention can also be obtained by mechanical mixing of the support powder with a solid chromium compound, for example chromium acetyl acetonate. This mixture can then be pre-activated at a temperature lower than the melting temperature of the chromium compound, before activating it conventionally, as described above. In the catalytic solid used in the third and fourth processes, chromium is generally present in proportions ranging from 0.05 to 10% by weight, preferably 0.1 to 5% by weight, and more particularly 0.25 to 2%. % by weight of chromium, based on the total weight of the catalytic solid.
The cocatalyst that is optionally used in the third procedure and compulsorily in at least one reactor, in the fourth procedure according to the invention, can be chosen from the organometallic aluminum or boron compounds. The best results are obtained with the organo-boaric compounds, since they allow to increase the catalytic activity. Trialkyl borons whose alkyl chains contain up to 20 carbon atoms can be used as oargano-baoric compounds. In general, those whose alkyl chains are straight and contain up to 18 carbon atoms, more particularly 2 to 8 carbon atoms, are preferred. Triethyl boron is preferred. The total amount of catalyst used is, in general, 0.02 to 50 mmol per liter of solvent, diluent or volume of
ES 2 reactor and preferably 0.2 to 2.5 mmol per liter.
The support used in the third and fourth processes for the preparation of an ethylene-ethylene polymer according to the invention, advantageously has a specific surface area of at least 100 μm<sup>2</sup>/ g, in particular at least 180 m<sup>2</sup>/ g, with favorable values of at least 220 m<sup>2</sup>/ g. The specific surface area is most often at most 800 m<sup>2</sup>/ g, and maus precisely as maximum 700 m<sup>2</sup>/ g, the current maus being the values of a maximum of 650 m<sup>2</sup>/ g. The specific surface area (SS) of the support is measured according to the BET volumetric method of the British standard BS 4359/1 (1984).
The support used in the third and fourth procedures generally has a crystallization temperature of at least 700 ° C, such as, for example, at least 1000 ° C. The crystallization temperature of the support is determined by subjecting a sample of the support to a heat treatment, at different temperatures (500 C, 700 ° C, 800 ° C, 950 ° C, 1050 ° C), and then examining, after each thermal treatment, this sample by X-ray diffraction.
The support used in the third and fourth procedures usually has a pore volume of at least 1.5 cm.<sup>3</sup>/ g, especially at least 2 cm<sup>3</sup>/ g, recommending values of at least 2.2 cm<sup>3</sup>/ g. The pore volume is generally a maximum of 5 cm<sup>3</sup>/ g, in particular maximum 4.5 cm<sup>3</sup>/ g, with current values of a maximum of 4 cm<sup>3</sup>/ g. The pore volume (VP) is the sum of the pore volume constituted by the pores with a radius less than or equal to 75 A, measured by the nitrogen penetration method (BET), according to the volumetric technique described in the British standard BS 4359 / 1 (1984), and the pore volume measured by the mercury penetration method, using the PORO 2000 type porosometer, marketed by CARLO ERBA CO, according to the Belgian standard NBN B 05202 (1976). Good results can be obtained when the specific surface (SS) and the pore volume (VP) of the support respond to the following relationship:
SS <(VPx564-358), in which SS and VP are respectively the numerical values of the specific surface, expressed in m<sup>2</sup>/ g, and the pore volume, expressed in cm<sup>3</sup>/ g.
The support used in the third and fourth procedures, when they contain no more than two of the aforementioned constituents, advantageously consists of solid and alumina in molar ratio 0.01 to 99 (preferably 0.05 to 20), solid and aluminum phosphate in molar ratio 0.01 to 99 (preferably 0.05 to 20), alumina and aluminum phosphate in molar ratio 0.01 to 99 (preferably 0.05 to 20). Preferably, the support contains solid (X), alumina (Y) and aluminum phosphate (Z), in a molar percentage (X): (Y): (Z) of (10 to 95) :( 1 to 80): (1 to 85), and especially (20 to 80) :( 1 to 60) :( 5 to 60). The support may eventually
286 T3 10 contain, in addition, titanium. The amount of titanium present in the support, expressed as a molar percentage of TiO2 with respect to the support of the catalytic solid containing solid, alumina, aluminum phosphate and titanium dioxide, is in general at least equal to 0.1% by mole, preferably 0.5% by mole; current values are values of at least 1% by mole. The most common is that the amount of titanium, expressed as a molar percentage of TiO2, does not exceed 40% by moles, more particularly 20% by moles, recommending values of a maximum of 15% by moles.
The support used in the third and fourth processes that use catalytic solids with chromium, is generally presented in the state of powder whose grains have a diameter of 20 to 200 μm. It usually has an apparent specific weight greater than or equal to 50 kg / m<sup>3</sup>, in particular 100 kg / m<sup>3</sup>; generally, it is at most equal to 500 kg / m<sup>3</sup>, typically 300 kg / m<sup>3</sup>. The apparent specific weight is measured by free pouring, according to the following procedure: in a 50 cm cylindrical container<sup>3</sup> capacity, the powder of the support to be analyzed is poured, avoiding compacting it, from a hopper whose lower edge is arranged 20 mm above the upper edge of the container. The container filled with powder is then weighed and made to level with the help of a rectilinear check, the tare is deducted from the recorded weight and the result obtained (expressed in grams) is divided by 50.
A particular procedure for obtaining the support used in the third and fourth procedures consists of mixing, in a first stage, an alcohol, water, a silicon alcoholate and an acid, in quantities such that the water / silicon molar ratio is 2 to 50 , add to the hydrolysis medium thus obtained, in a second stage, an acid solution of an aluminum compound and a solution of a source of phosphate ions and, in a third stage, a precipitating agent to obtain a precipitate, wash with water, in a fourth stage, the precipitate thus obtained, and then wash with an orgaonic liquid, then dry, in a fifth stage, by distillation until a powder is obtained, and calcine the powder obtained.
The silicon alcoholate used in the first stage of the particular process for obtaining the support preferably consists of an alkoxy group with 1 to 20 carbon atoms. Alifaotic type alkoxy groups are recommended, especially saturated, unsubstituted aliphatic type. Suitable silicon alcoholates are silicon tetra-ethylate, tetra-methylate, and tetra-isopropylate. Silicon tetraethylate is preferred.
The alcohol used in the first stage of the particular procedure for obtaining the support has the function of dissolving the silicon alcoholate. Linear aliphatic alcohols are preferred. Examples are ethanol, isopropanol and methanol. Ethanol is preferred. An alcohol is advantageously used whose hydrocarbon group corresponds to that of the alkoxy group of the silicon alcoholate used.
The first stage is advantageously carried out at acidic pH and consists, on the one hand, of the addition of
ES 2 138 286 T3 of water, acid, silicon alcohol and alcohol, the temperature, during the addition, being less than or equal to 30<sup>°</sup>C (in particular less than 20<sup>°</sup>C, typically around 10 ° C, with temperatures above 0 being recommended<sup>°</sup>C); and, on the other hand, a maturation of the reaction medium thus obtained, at a temperature at least equal to 20<sup>°</sup>C and lower than the boiling temperature of the medium (for example 30 to 100<sup>°</sup>C; temperatures from 40 to 80<sup>°</sup>These are common and those from 50 to 70 are recommended.<sup>°</sup>C), so that at least a part of the alkoxy groups of the silicon alcoholate is replaced by hydroxy groups, without causing gelation or precipitation of the salt. In the first stage, the pH of the reaction medium is, in general, less than 3, preferably 0.5 to 2.5, for example approximately equal to 1. The acid used in the first stage can be mineral or organic in nature. . It can be, for example, hydrochloric, natric, phosphaoric or sulfuric acid. Hydrochloric acid is particularly suitable. Preferably, the maturation is carried out at a temperature higher than that of the addition of the reagents. The aging process has the function of allowing a hydrolysis and a partial condensation of the silicon alcoholate.
The second stage of the particular procedure for obtaining the support consists of adding to the medium from the first stage an acidic solution of an aluminum compound and a solution of a source of phosphate ions. The aluminum compound can be chosen from inorganic aluminum salts and aluminum alcoholates. Aluminum alcoholates containing unsubstituted saturated linear aliphatic groups are recommended. The aliphatic groups preferably contain 1 to 20 carbon atoms. Aluminum alcoholates whose alkoxy group corresponds to that of the silicon alcoholate used are particularly suitable. Aluminum nitrate and chloride are especially preferred. For the purposes of the present invention, any compound capable of forming phosphate ions is designated as a source of phosphate ions. Inorganic phosphate salts, phosphate ethers-salts and phosphate acid are especially recommended. Phosphoraic acid is preferably used. In the second stage of the particular procedure for obtaining the support, it is preferred to operate very slowly, to prevent the medium from heating up, for example to a temperature below 30<sup>°</sup>C, typically less than or equal to 20<sup>°</sup>C, for example between 0 and 10<sup>°</sup>C.
The third stage of the particular procedure for obtaining the support consists of forming a precipitate, under the effect of a precipitating agent, which can be chosen from among all the compounds capable of causing a co-precipitation of the reagents used in the first and second stages (alcoholate of silicon, hydrolyzed and partially condensed, from the first stage and defined above, the aluminum compound and the source of phosphate ions) in the form of mixed oxide of silicon, aluminum and phosphorus. Examples of precipitating agents are ethylene oxide, ammonium carbonate and ammonium hydroxide. An aqueous solution of ammonium hydroxide is preferably used. The pH of the coprecipitation medium is generally greater than or equal to 5, typically greater than or equal to 6; it is usually less than 11, recommending values less than 10. Preferably, the pH is kept constant at a value of 6 to 10, for example 8, throughout the duration of the coprecipitation.
In the fourth stage of the particular procedure for obtaining the support, washing with water generally consists of putting the precipitate in contact with a sufficient quantity of water to eliminate the impurities contained in the precipitate, and then eliminating at least a part of this amount of water, by any known and suitable means, for example by centrifugation or filtration. It is preferably operated by centrifugation. Afterwards, the precipitate washed with water is subjected to a washing by means of an organic liquid, whose mission is to eliminate the water that impregnates the precipitate. The organic liquid preferably has a vaporization temperature below 120<sup>°</sup>C, typically less than 100<sup>°</sup>C, for example between 70 and 90<sup>°</sup>C. Usable organic liquids are alcohols, ethers or their mixtures. Alcohols are preferred, particularly those containing 1 to 4 carbon atoms. Isopropanol is appropriate.
The washed precipitate is then subjected, in a fifth stage of the particular procedure for obtaining the support, to drying by atomization or by distillation, preferably azeotrophic, in order to evaporate the water and organic liquid not previously removed, until a support powder.
At the end of drying, a support powder is collected, which is subjected to calcination. The function of calcination is to extract, at high temperature, the organic impurities from the dust. Generally, calcination is continued until the weight of the powder remains constant over time, avoiding a crystallization of said powder. The calcination can be carried out in air (preferably dry air) in a fluidized bed at a temperature below the crystallization temperature of the powder. The temperature varies, in general, between 300 and 1500<sup>°</sup>C, typically 350 to 1000<sup>°</sup>C, preferably 400 to 600<sup>°</sup>C.
When using a support chosen from the binary supports SiO2-AlPO4, Al2O3-AlPO4, and between the ternary supports SiO2-Al2O3-AlPO4 such as those described above in an olefin polymerization process, in two reactors in series, they can also be Obtaining polyolefins other than ethylene polymer follow the invention. Consequently, the invention also deals with an olefin polymerization process, whereby the olefin is polymerized optionally with one or more comonoamers, in two reactors arranged in series, in the presence of a catalytic solid containing chromium on a chosen support. between the binary supports SiO2-AlPO4, Al2O3-AlPO4 and the ternary supports SiO2-Al2O3-AlPO4 and of a cocatalyst, the first reactor being fed with ethylene and possibly with comonaomer and / or with hydrogen, with catalytic solid, transferring the reaction medium from the first reactor to the second
ES 2 138 286 T3 reactor, the second reactor being also fed with ethylene and optionally with comonaomer and / or with hydrogen, the cocatalyst being present in at least one of the two reactors.
The polymerization processes of the invention can be carried out according to any known process, in solution in a solvent that can be the olefin itself in the liquid state, or in suspension in a hydrocarbon diluent, or also in the gas phase. Good results are obtained in suspension polymerizations.
The principle of a polymerization in two reactors arranged in series is that described in patent application EP 603935 (SOLVAY). The installation can obviously consist of more than two reactors connected in series. The polymerization processes in two reactors in series are advantageously carried out in such a way that, in the second reactor, polymerization conditions (temperature, concentration of transfer agent such as hydrogen, concentration of possible co-catalyst, concentration of possible cocatalyst are used. , ...) different from those used in the first reactor. Thus, the polymer produced in the second reactor has a different melt index from that produced in the first reactor. It is therefore possible to act in such a way that the melt index obtained in the first reactor is lower than that obtained in the second reactor. As a variant, a higher melt index can be obtained in the first reactor than that obtained in the second reactor.
The following examples are intended to illustrate the invention. The meaning of the symbols used in these examples, the units that express the mentioned quantities and the measurement methods of these quantities are explained below.
MI2 = melt index of polyethylene, measured at 190 ° C under a load of 2.16 kg, according to ASTM D 1238 (condition E) (1986).
MI5 = melt index of polyethylene, measured at 190<sup>°</sup>C under a load of 5 kg, they will follow ASTM D 1238 (condition P) (1986).
MVS = standard volumetric mass of polyethylene, expressed in kg / m<sup>3</sup> and measurement follow the ISO 1183 (1987) standard.
η = dynamic viscosity of polyethylene, expressed in dPa.s and measured at a velocity gradient of 100 s<sup>-1</sup> to 190<sup>°</sup>C.
ESCR = resistance to stress cracking, expressed in hours and measured by the following method: Ten plates of dimensions 125 mm x 12.7 mm x 3.2 mm are pressed from an ethylene polymer sheet. Two notches are made, the first 60 mm from one end of the plate and the second 15 mm from the other end of said plate. The notched plates are subjected to a constant bending stress of 7.36 N, which corresponds to a tension lower than the tension at the plastic flow threshold and simultaneously immersed in a surfactant solution containing 3 ml of nonyl-phenoxypoly (ethyleneoxy) - ethanol per liter of water, at a temperature of 60<sup>°</sup>C. The time at the end of which the specimens break is noted and the mean time corresponding to the failure of 50% of said specimens is calculated.
TG = swelling rate of the ethylene polymer (unitless). The measurement method is to extrude, at 190<sup>°</sup>C and a velocity gradient of 100 s<sup>-1</sup>, the ethylene polymer passes through a 30 mm long, 2 mm diameter die, at a constant extrusion speed, and in measuring the piston displacement necessary to extrude a 70 mm rod length. The swelling rate is defined by the relation T<sub>G </sub>= 0.5707 © in which e represents the piston displacement, expressed in mm. The cylinder and piston of the rheometer used for this measurement respond to the criteria of the same used for the measurement of the flow index, following the ASTM D 1238 (1986) standard.
P = productivity of the catalytic solid, expressed in kg of polyethylene produced per gram of titanium. used.
Example 1 (reference)
In this example, an ethylene polymer will be prepared, in two reactors in series, with the help of a titanium catalyst, according to the procedure described in patent application EP 603935 and its swelling rate and its resistance to cracking will be measured. under tension.
A. Preparation of the catalytic solid
It was reacted for 4 hours at 150<sup>°</sup>C, magnesium diethylate with titanium tetrabutylate, in amounts such that the molar ratio between titanium and magnesium was equal to 2. The reaction product thus obtained was then chlorinated and precipitated, by placing it in contact with a solution of ethyl dichloride. -aluminum in an amount such that the molar ratio between aluminum and magnesium was equal to 6.5, for 90 minutes at 45<sup>°</sup>C. The solid thus obtained had 15.8% by weight of Ti, 36.0% by weight of Cl, 2.2% by weight of Al and 4.4% by weight of Mg.
B. Polymerization of ethylene in two reactors
Ethylene was polymerized in a facility containing two reactors arranged in series. Hexane, triethyl-aluminum as cocatalyst, ethylene and hydrogen in a hydrogen / ethylene molar ratio = 0.27 were continuously introduced into the first reactor, and the catalytic solid obtained in A. The temperature was kept constant at a 85SC value. The polymerization medium from the first reactor was continuously withdrawn from said first reactor and transferred to the second reactor, which was fed, in addition, with ethylene, hydrogen with a hydrogen / ethylene molar ratio of 0.0085 and with butene at a butene / ethylene molar ratio of 0.31. The temperature in the second reactor was 70<sup>°</sup>C. The productivity P was 200. The polymer obtained presented the following characteristics:
IS 2 138 286 T3
MI5 = 1.3 η = 15400
TG = 1.34
ESCR = 128
MVS = 956.
The obtained polymer presented a swelling rate lower than 1.4, while the ethylene polymers according to the invention presented a swelling rate of at least 1.4. Example 2 (for reference)
In this example, an ethylene polymer was prepared, in a single reactor, with the help of a titanium and zirconium catalyst, following the procedure described in Belgian patent BE 840378 and its swelling rate and resistance to corrosion were measured. cracking under stress.
A. Preparation of the catalytic solid
It was reacted for 4 hours at 150<sup>°</sup>C, magnesium diethylate with titanium tetrabutylate and with zirconium tetrabutylate, in amounts such that the Ti / Mg molar ratio was equal to 0.6 and the Zr / Ti molar ratio was equal to 1.2. Thereaction product obtained was then chlorinated and precipitated, putting it in contact with a solution of isobutyl-aluminum dichloride, in an amount such that the molar ratio Al / Mg was 11, at 45<sup>°</sup>C. The catalytic solid was mixed with titanium tetraisopropylate, at the rate of 150 g per kg of catalytic solid. The solid obtained had 6.4% by weight of Ti, 12.6% by weight of Zr, 55.2% by weight of Cl, 2.5% by weight of Al and 5.8% by weight of Mg.
B. Polymerization of ethylene in a single reactor
Ethylene was polymerized in a single reactor. Hexane, triisobutyl aluminum as cocatalyst, ethylene and hydrogen were introduced, in a hydrogenic / ethylene molar ratio equal to 0.09, and the catalytic solid obtained in A. Butene was introduced in a butene / ethylene molar ratio of 0.07. The temperature was kept constant, at a value of 87<sup>°</sup>C. The productivity P was 100. The obtained polymer presented the following characteristics:
MI5 = 1.1 η = 18300 TG = 1.59
ESCR = 38
MVS = 954
The polymer obtained presented a resistance to cracking under stress of less than 55 h, while the ethylene polyomers according to the invention presented a resistance to cracking under stress of at least 55 h.
Example 3 (reference)
In this example, an ethylene polymer was prepared, in a single reactor, with the help of a solid-supported chromium catalyst, and its swelling rate and its resistance to stress cracking were measured.
A. Preparation of the catalytic solid
The commercial catalyst EP30X from CROSFIELD was used, which contains 1% by weight of chromium supported on solid. The catalyst was calcined in a fluidized bed at 760<sup>°</sup>C, for 12 hours, in dry air, and the catalytic solid was collected.
B. Polymerization of ethylene, in a single reactor
Ethylene was polymerized in a single reactor. Isobutane, ethylene and hexene were introduced in a hexene / ethylene molar ratio = 0.017 and the catalytic solid obtained in A. The total pressure in the reactor and the temperature were kept constant, at a value of 4.2 MPa. and 103<sup>°</sup>C, respectively. The obtained polymer presented the following characteristics:
MI5 = 0.86 η = 17900 TG = 1.67
ESCR = 24
MVS = 954.0
The polymer obtained presented a resistance to cracking under stress of less than 55 h, while the ethylene polyomers according to the invention presented a resistance to cracking under stress of at least 55 h.
Example 4 (according to the invention)
In this example, an ethylene polymer was manufactured according to the invention, by means of the first preparation procedure according to the invention.
A. Preparation of catalytic solid
It was reacted for 4 hours at 150<sup>°</sup>C, magnesium diethylate with titanium tetrabutylate and with zirconium tetrabutylate, in amounts such that the Ti / Mg molar ratio was equal to 0.4 and the Zr / Ti molar ratio was equal to 3. Next, it was chlorinated and The reaction product thus obtained precipitated, putting it in contact at 45<sup>°</sup>C with a solution of isobutylaluminum dichloride, in an amount such that the Al / Mg molar ratio was 8.4. The solid thus obtained had 4.4% by weight of Ti, 14.9% by weight of Zr, 50.2% by weight of Cl, 2.4% by weight of Al and 8.0% by weight of Mg.
B. Polymerization of ethylene in two reactors
Ethylene was polymerized in a facility consisting of two reactors arranged in series. Hexane, triethylaluminum as cocatalyst, ethylene and hydrogen in a molar ratio of hydrogen / ethylene = 0.37 were introduced, continuously, into the first reactor, and the catalytic solid obtained in A. The temperature was kept constant at a value of 85<sup>°</sup>C. The polymerization medium from the first reactor was continuously withdrawn from the first reactor and transferred to the second reactor, which was also fed with ethylene, with hydrogen in a hydrogen / ethylene molar ratio = 0.0125, and with butene in a butene / ethylene molar ratio = 0.2. The temperature in the second reactor was 80<sup>°</sup>C. Productivity P was 213. The weight ratio between the polymer obtained in the first reactor and that obtained in the second reactor was 45.6 / 54.4. The polymer obtained presented the following characteristics:
IS 2 138 286 T3
MI5 = 1.5 η = 12800
TG = 1.49 ESCR = 143
MVS = 955.
Example 5 (following the invention)
In this example, an ethylene polymer was manufactured, according to the invention, by the second preparation procedure according to the invention.
A. Preparation of the mixture of catalytic solids
A.1. Preparation of the first catalytic solid with titanium
Magnesium diethylate was reacted with titanium tetrabutylate for 4 hours at 150 ° C, in amounts such that the molar ratio between titanium and magnesium was equal to 2. Next, the reaction product thus obtained was chlorinated and precipitated. , by putting it in contact with a solution of ethyl-aluminum dichloride in an amount such that the Al / Mg molar ratio was
6.5, for 90 minutes at 45 ° C. The solid thus obtained had 15.8% by weight of Ti, 36.0% by weight of Cl, 2.2% by weight of Al and 4.4% by weight of Mg.
A.2. Preparation of the second catalytic solid with titanium and zirconium
It was reacted for 4 hours at 150<sup>° </sup>C, magnesium diethylate with titanium tetrabutylate and with zirconium tetrabutylate, in amounts such that the Ti / Mg molar ratio was equal to 0.6 and the Zr / Ti molar ratio was equal to 2. Next, it was chlorinated and The reaction product thus obtained was precipitated by putting it in contact with a solution of isobutyl-aluminum dichloride, in an amount such that the molar ratio Al / Mg was equal to 14, initially 45<sup>°</sup>C then a60<sup>°</sup>C. The solid thus obtained had 5.4% by weight of Ti, 16.3% by weight of Zr, 52.6% by weight of Cl, 2.4% by weight of Al and 4.1% by weight of Mg .
A. 3. Preparation of the mixture
The solid obtained in A was mixed with the solid obtained in B, at the rate of such quantities that the molar ratio of titanium from the first catalytic solid to the titanium from the second catalytic solid was equal to 1.5.
B. Polymerization of ethylene in two reactors
Ethylene was polymerized in a facility consisting of two reactors arranged in series. Hexane, triethylaluminum as cocatalyst, ethylene and hydrogen in a hydrogen / ethylene molar ratio equal to 0.32, and the mixture of catalytic solids obtained in A.3, were continuously introduced into the first reactor. The total pressure in the reactor and the temperature were kept constant, at a value of 3.2 MPa and 85<sup>°</sup>C, respectively. The polymerization medium from the first reactor was continuously withdrawn from the first reactor and transferred to the second reactor, which was also fed with ethylene, hydrogen in a molar ratio, hydrogen / ethylene = 0.0185, and butene in a molar ratio. butene / ethylene = 0.35. The total pressure in the reactor was equal to 3.0 MPa. The temperature in the second reactor was 75<sup>°</sup>C. The productivity P was = 111. The polymer obtained presented the following characteristics:
MI2 = 0.32 η = 15300 TG = 1.43 ESCR = 109
MVS = 956.4
Example 6 (according to the invention)
In this example, an ethylene polymer according to the invention was manufactured by the third preparation procedure according to the invention.
A. Preparation of the catalytic solid
A.1. It was added to a solution of silicon tetraethylate and ethanol, at a temperature of 10<sup>°</sup> C, a solution of water and 1M hydrochloric acid, so that a pH = 1 was obtained. The quantities used were:
34.7 g of silicon tetraethylate, 41.7 g of ethanol, 18.9 g of water and 11.5 g of hydrochloric acid. Subsequently, the reaction medium thus obtained was subjected to a maturation at 60<sup>°</sup>C, for 2 hours.
A.2. In parallel, an aqueous solution was prepared containing 62.5 g of hydrated aluminum nitrate, 17.1 g of phosphoric acid and
33.3 g of water. Afterwards, the solution thus obtained was added to the reaction medium obtained in A.1, with vigorous stirring, at 10<sup>°</sup>C.
A.3. To 500 g of an aqueous solution of ammonium hydroxide, pH = 8, thermostatized at 10, was added<sup>°</sup>C, the mixture obtained in A.2, keeping the pH constant at a value of 8, in order to effect gelation. The gel was subjected to a maturation, at pH = 8, for 2 hours, with stirring, at 60<sup>°</sup>C.
A.4. The gel was then washed with water and then with isopropanol, and a suspension of the gel was collected.
TO 5. The gel obtained in A.4 was dried by atomization until powder was obtained.
A.6. The powder obtained in A.5 was calcined in a fluidized bed, sweeping with dry air, for 4 hours, at 500<sup>°</sup>C. A powder was collected that contained:
15.6% by weight of Si,
15.1% by weight of Al,
16.3% by weight of P.
A.7. The support obtained in A.6 was mixed with chromium acetyl acetonate, in an amount such that the mixture had 0.7% by weight of
ES 2 138 286 T3 chrome. Then, the mixture thus obtained will be treated in a fluidized bed at 150 ° C, for 2 hours, with dry air sweeping. Afterwards, it is calcined in the fluidized bed at 600 ° C, for 10 hours, under dry air, and the catalytic solid will be collected, presenting the following characteristics:
specific surface = 407 m<sup>2</sup>/ g, pore volume = 2.20 cm<sup>3</sup>/ g, crystallization temperature higher than 700 C.
B. Polymerization of Ethylene in a Single Reactor
Ethylene will polymerize in a single reactor. Isobutane, ethylene, hydrogen in a hydrogen / ethylene molar ratio or equal to 0.046, and hexene in an ethylene / hexene molar ratio of 0.003, and the catalytic solid obtained in A. The total pressure in the reactor and the temperature remained constant at a value of
3.8 MPa and 107 ° C, respectively. The polymer obtained will have the following characteristics:
MI5 = 0.58 η = 18000 TG> 1.5
ESCR = 111
MVS = 955.8
Example 7 (according to the invention)
In this example, an ethylene polymer was manufactured, according to the invention, by means of the fourth preparation procedure according to the invention.
A. Preparation of the catalytic solid
The catalytic solid from Example 6 will be used, which is calcined in a fluidized bed at 815<sup>°</sup>C, for 16 hours, under dry air.
B. Polymerization of ethylene in two reactors
The polymerization procedure in two successive reactors was simulated in a single reactor, in two stages separated by an intermediate stop and restart of the operating parameters.
Polymerization of a first polymer (i):
108 mg of catalyst were introduced into a 3-liter autoclave, fitted with a stirrer. The polymerization temperature will be brought to 80<sup>°</sup>Cy remained constant during polymerization. Ethylene was then introduced. The partial pressure of ethylene was kept constant at a value of
5.8 bar. 6.7 g of hexene were introduced and then 0.67 g each time, which produced 50 g of PE (to maintain a constant Hexene / Ethylene ratio). The Hexene / Ethylene ratio was 0.11. After 68 minutes, the autoclave was degassed to a pressure of 6 bar. 162 g of polymer (i) were obtained.
Polymerization of a second polymer (ii):
1 liter of isobutane was added to the autoclave.
The temperature was brought to 98<sup>°</sup>C and remained constant during the polymerization time. A single dose of hydrogen was then introduced to obtain a Hydrogen / Ethylene molar ratio in the liquid phase = 0.22. The cocatalyst (triethyl boron) was then introduced into the autoclave, in an amount such that the triethyl boron / chromium molar ratio was equal to 3.8. The partial pressure of ethylene was kept constant, at a value of 3.5 bar until a supplementary quantity of 162 g of polymer (ii) was obtained. After degassing, 324 g of a composition of polymers (i) and (ii) were collected from the autoclave. The catalyst showed an activity of 33000 and 93000, respectively, in blocks (i) and (ii). The activity is expressed in gPE / gcata.h. [C2H4]. The properties of the polymer, after granulation, were the following:
MI5 = 0.49 η = 14000
TG = 1.9
MVS = 954.4.
Contents4
54 members in 18 offices
Priority claims5
| Document | Office | Kind | Date |
|---|---|---|---|
| 19950000397 | Belgium | – | |
| 9500397 | Belgium | A | |
| 9500397 | Belgium | A | |
| 96201016 | – | – | – |
| BE19950000397 | – | – | – |
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| EP0739909A1 | European Patent Office (EPO) | A1 | |
| AU5069896A | Australia | A | |
| CZ122296A3 | Czechia | A3 | |
| JPH08301932A | Japan | A | |
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| BE1009308A3 | Belgium | A3 | |
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| HU9601108A2 | Hungary | A2 | |
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| EP0906922A2 | European Patent Office (EPO) | A2 | |
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| EP0906922A3 | European Patent Office (EPO) | A3 | |
| EP0908474A3 | European Patent Office (EPO) | A3 | |
| EP0739909B1 | European Patent Office (EPO) | B1 | |
| AT183524T | Austria | T | |
| ATE183524T1 | Austria | T1 | |
| DE69603773D1 | Germany | D1 | |
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| DE69625711D1 | Germany | D1 | |
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Numbers
- Publication
- 2138286
- Publication, DOCDB
- 2138286
- Publication, EPODOC
- ES2138286T
- Application
- 96201016
- Application, DOCDB
- 96201016
- Application, EPODOC
- ES19960201016T
Titles2
- Spanish
- POLIMERO DE ETILENO Y PROCEDIMIENTOS PARA SU OBTENCION.
- English
- ETHYLENE POLYMER AND PROCEDURES FOR ITS OBTAINING.
Classification
- CPC, 7
- C08F10/02
- C08F297/08
- C08F10/00
- C08F110/02
- C08F210/16
- C08F2410/04
- C08F4/64
- IPC, 12
- C08F2 00
- C08F4 22
- C08F4 655
- C08F4 658
- C08F4 69
- C08F8 00
- C08F10 00
- C08F10 02
- C08F110 02
- C08F210 00
- C08F210 16
- C08F297 08