KR20070029703A - Impact resistant polyolefin compositions - Google Patents

Abstract

A heterophasic polyolefin composition comprising (percent by weight): (A) 50-0% of a crystalline propylene polymer having a polydispersity index value from 5.2 to 10 and a content of isotactic pentads (mmmm) higher than 97.5 molar%; said polymer containing at least 95% of recurring units deriving from propylene; (B) 5- 20% of a first elastomeric copolymer of ethylene with at least a C3-C8 alpha-olefin comonomer, said copolymer containing from 25 to less than 40% of ethylene, and being soluble in xylene at room temperature in an amount from higher 85 to 95 wt% the intrinsic viscosity [eta] of the xylene soluble fraction ranging from 2.5 to 4.5 dL/g; and (C) 10-45% of a second elastomeric copolymer of ethylene with at least a C3-C8 alpha-olefin comonomer, said copolymer containing from 50 up to 75% of ethylene, and being soluble in xylene at room temperature in an amount from 50 to 85 wt%, the intrinsic viscosity [eta] of the xylene soluble fraction ranging from 1.8 to 4.0 dL/g; wherein the sum of amounts of copolymer (B) and copolymer (C) ranges from 20 to 50% based on the total amount of components (A) to (C), the total amount of ethylene based on the total amount of components (A) to (C) is up to 23% by weight and the ratio between the ethylene content of the fraction insoluble in xylene at room temperature (C2xif) multiplied by the weight percentage of the fraction insoluble in xylene at room temperature (%XIF) and the ethylene content of the fraction soluble in xylene at room temperature (C2xsf) multiplied by the weight percentage of fraction soluble in xylene at room temperature (%SXF), i.e. (C2 xif %XIF)/(C2xsf À%SXF), satisfies the following relation (I), wherein x is the total amount of ethylene. ® KIPO & WIPO 2007

Description

Impact Resistant Polyolefin Composition {IMPACT RESISTANT POLYOLEFIN COMPOSITIONS}

The present invention relates to a polyolefin composition having a good balance of stiffness and impact resistance and high elongation, and to the composition and to a process for producing the composition.

As is known, isotactic polypropylene has good stiffness but has poor impact resistance and elongation values. Impact resistance properties at low temperatures can be improved by adding rubber to isotactic polypropylene. A disadvantage with the polymer compositions thus obtained is that the stiffness is significantly reduced compared to isotactic polypropylene alone.

Japanese Laid-Open Patent Publication No. 162621/1983 discloses 20 to 70 parts by weight of highly crystalline propylene polymer, 5 to 30 parts by weight of propylene-ethylene random copolymer having less than 8 to 30% by weight of ethylene, and 30 to 85 weight of ethylene. Olefin block copolymers made from denier 10 to 75 parts by weight of propylene-ethylene random copolymers are described. The copolymer composition has good impact resistance at low temperatures and has high flexibility.

Accordingly, there is a need for more rigid polyolefin compositions that maintain high stiffness and good impact resistance properties at room temperature and low temperature, and also have high elongation values.

The Applicant has found a heterophasic polyolefin composition having a particularly good balance of properties, in particular high strength of impact strength and recovery properties at low temperatures, in particular not reducing impact resistance.

The present invention also has high tensile strength and elongation at break.

In the compositions of the present invention, the crystalline polymer fraction typically has a wide distribution of molecular weight.

Compositions having the above properties are obtained through operation in three or more polymerization stages. In the first stage, propylene is polymerized or copolymerized with a small amount of copolymer (s) and in the second and third stages the ethylene / α-olefin (s) mixture is present in the presence of the propylene polymer obtained in the stage (s). Copolymerized.

Accordingly, the present invention relates to heterophasic polyolefin compositions and comprises (% by weight):

(A) 50 to 80%, with polydispersity readings of 5.2 to 10, of isotactic pentad (mmmm) measured in fractions insoluble in xylene at 25 ° C. by ¹³ C-NMR. Crystalline propylene polymers; The polymer is a propylene homopolymer and a copolymer of propylene and at least one comonomer selected from ethylene and an alpha-olefin of formula H ₂ C═CHR, wherein R is a C ₂ comprising at least 95% of repeating units derived from propylene ₆ is a linear or branched alkyl radical;

(B) propylene) and (H ₂ C = CHR of another one or more selected from α- olefin co-monomer in the first elastomeric copolymer of ethylene from 5 to 20%, wherein R is C _{2 -6} straight or branched alkyl Radical; The first elastomeric copolymer comprises less than 25-40%, preferably 25-38% of ethylene, is more than 85-95% by weight soluble in xylene at room temperature, and the intrinsic viscosity of the xylene soluble fraction [η] Is in the range of 2.5 to 4.5 dL / g; And

(C) 10 to 40% of a second elastomeric copolymer of ethylene with at least one comonomer selected from propylene and another α-olefin of formula H ₂ C═CHR; Wherein R is a C _2-6 linear or branched alkyl radical; The second elastomeric copolymer comprises 50 to 75%, preferably 55 to 70 ethylene, is 50 to 85% by weight, preferably 55 to 85% soluble in xylene at room temperature, inherent in the xylene soluble fraction Viscosity [η] ranges from 1.8 to 4.0 dL / g.

The sum of the amounts of copolymer (B) and copolymer (C) in the heterophasic polyolefin composition ranges from 20 to 45%, preferably from 22 to 45%, relative to the total amount of components (A) to (C), The total amount of ethylene, relative to the total amount of) to (C), is 23% by weight or less, the content of fractional ethylene insoluble in xylene at room temperature multiplied by the weight percent (% XIF) of the insoluble fraction in xylene at room temperature (C ₂ xif) and the ratio between the fractional ethylene content (C ₂ xsf) soluble in xylene at room temperature multiplied by the weight percent (% SXF) of the xylene soluble fraction at room temperature, ie, (C ₂ xif *% XIF) / (C ₂ xsf *% SXF) satisfies the following relation (I):

[Wherein x is the total amount of ethylene].

로 표현되고, 이를 GPC 로 측정했을 때 9 이상, 특히 9.5 내지 20 이다. Typically, the compositions of the present invention show a molecular weight distribution of component (A), wherein the ratio between the weight average molecular weight and the number average molecular weight, ie

It is expressed as, and when measured by GPC, it is 9 or more, especially 9.5 to 20.

의 수치를 GPC 로 측정했을 때 4.5 이상, 바람직하게 5 이상, 예를 들어 5 내지 10 이다. Typically the compositions of the present invention have a z average molecular weight to weight average molecular weight ratio in component (A), ie

When the value of is measured by GPC, it is 4.5 or more, Preferably it is 5 or more, for example, 5-10.

Typically the melt flow rate (MFR) value of the composition of the present invention is from 2 to 30 g / 10 minutes.

Preferably, the copolymer comprises repeating units derived from ethylene and / or one or more C ₄ -C ₈ α-olefin (s) such as butene-1, pentene-1,4-methylpentene-1, hexene-1 and Octene-1 or combinations thereof. Preferred comonomers are ethylene.

The intrinsic viscosity [η] of the elastomeric copolymer (B) may be the same as or different from the intrinsic viscosity [η] of the elastomeric copolymer (C).

Crystalline polymer (A) typically has an MFR value in the range of 10 to 200 g / 10 minutes. Elastomeric copolymers (B) and (C) are composed of repeating units derived from conjugated or unconjugated dienes such as butadiene, 1,4-hexadiene, 1,5-hexadiene and ethylidene-norbornene-1 May optionally include. When diene is present, it is present at 0.5 to 10% by weight relative to the copolymer.

Typically, the compositions of the present invention have flexural modulus values of at least 600 MPa, such as 600 to 1400 MPa, preferably 700 to 1300 MPa, and the impact resistance values measured at 23 ° C. are typically 11 kJ / m. Greater than ² , preferably greater than 19 kJ / m ² . The impact resistance value measured at -20 ° C is usually at least 6 kJ / m ² , preferably at least 7 kJ / m ² . Elongation at break is usually at least 100%, preferably at least 150%. The energy level is usually above 10 J, preferably above 12. Ductile / brittleness transition temperatures are typically below -50 ° C.

Thus, the present invention further relates to a process for the preparation of a polyolefin composition as described above, wherein the process consists of three or more successive polymerization stages, each subsequent polymerization of the polymeric material formed in the immediately preceding polymerization stage. In the presence, wherein the crystalline polymer fraction (A) is prepared in at least one first step, and the elastomeric fractions (B) and (C) are prepared in a subsequent step. The polymerization step can be carried out in the presence of a Ziegler-Natta catalyst.

According to a preferred embodiment, all the polymerization steps are carried out of a solid catalyst comprising a solid catalyst component comprising a trialkylaluminum compound, optionally an electron donor, a halide or halogen-alcolate of Ti and an electron-donor compound supported with anhydrous magnesium chloride. Carried out in the presence. Catalysts having this property are known from the patent literature; Particularly advantageous are those described in USP 4,399,054 and EP-A-45 977. Other examples can be found in USP 4,472,524.

Preferably the polymerization catalyst is a Ziegler-Natta catalyst comprising a solid catalyst component comprising:

a) Mg, Ti and an electron donor selected from halogen and succinate, preferably succinate of formula (I) or formula (II):

[Formula I]

[Wherein, the same or different radicals R ₁ And R ₂ silver C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups optionally containing heteroatoms; Radicals R ₃ to R _{6, which} are the same or different from each other, are C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups optionally containing hydrogen or heteroatoms; The radicals R ₃ to R ₆ linked to the same carbon atom may be bonded to each other to form a ring, provided that when R ₃ to R ₅ are hydrogen at the same time, R ₆ is a primary branched, secondary having 3 to 20 carbon atoms. Or tertiary alkyl group, cycloalkyl, aryl, arylalkyl or alkylaryl group;

[Formula II]

[Wherein, the same or different radicals R ₁ And R ₂ Is a C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group optionally containing heteroatoms and is a radical R ₃ Is a linear alkyl group of 4 or more carbon atoms optionally containing heteroatoms;

b) alkylaluminum compounds, optionally (but preferably),

c) one or more electron-donor compounds (external donors).

Al-alkyl compounds used as cocatalysts are O or N atoms, or SO ₄ or Al-trialkyl comprising two or more Al atoms linked via a SO ₃ group, such as Al-triethyl, Al-triisobutyl, Al-tri-n-butyl, and linear or cyclic Al-alkyl compounds. Al-alkyl compounds are generally used in amounts having an Al / Ti ratio of 1 to 1000.

The external donor (c) may be the same or different than the succinate of formula (I) or (II). Suitable external electron-donor compounds are silicon compounds, ethers, esters such as phthalates, benzoates, succinates, amines, heterocyclic compounds and also in particular having a structure different from that of the formula (I) or (II) and especially 2,2, 6,6-tetramethylpiperidine, ketone and 1,3-dieter of general formula (III):

[Formula III]

^{Wherein the} same or different R ^I and R ^II are C ₁ -C ₁₈ alkyl, C ₃ -C ₁₈ cycloalkyl or C ₇ -C ₁₈ aryl radicals; R ^III and R ^IV is the same or different and is a C ₁ -C ₄ alkyl radical; Or the carbon atom in the 2 position is 1,3-dieter which belongs to a cyclic or polycyclic structure having 5, 6 or 7 carbon atoms and having 2 or 3 unsaturations.

Ethers of this type are described in European patent applications 361493 and 728769. Electron-donor compounds that can be used as external donors include aromatic acid esters such as alkyl benzoates, and in particular silicon compounds having at least one Si-OR (wherein R is a hydrocarbon radical) bond. Particularly preferred external donor compound series are those of the silicon compounds of the formula R _a ⁷ R _b ⁸ Si (OR ⁹ ) _c , wherein a and b are integers from 0 to 2, integers from c 1 to 3, and sum (a + b + c) is 4; R ⁷ , R ⁸ , and R ⁹ are Cl-C ₁₈ hydrocarbon groups optionally containing heteroatoms. Especially preferably, a is a silicon compound in which a is 1, b is 1, c is 2, and R ⁷ And ^At least one of R ⁸ is selected from branched alkyl, alkenyl, alkylene, cycloalkyl or aryl groups of 3 to 10 carbon atoms optionally containing hetero atoms, and R ⁹ is C ₁ -C ₁₀ Alkyl groups, especially methyl. Examples of such a preferred silicon compound include cyclohexyltrimethoxysilane, t-butyltrimethoxysilane, t-hexyltrimethoxysilane, cyclohexylmethyldimethoxysilane, 3,3,3-trifluoropropyl-2 -Ethylpiperidyl-dimethoxysilane, diphenyldimethoxysilane, methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-t-butyldimethoxysilane, (1 , 1,1-trifluoro-2-propyl) -methyldimethoxysilane and (1,1,1-trifluoro-2-propyl) -2-ethylpiperidinyldimethoxysilane. Furthermore, preference is also given to a being 0, c to 3, R ⁸ being branched alkyl or cycloalkyl optionally containing heteroatoms, R ⁹ Is a silicon compound which is methyl. Particularly preferred examples of silicon compounds include (tert-butyl) ₂ Si (OCH ₃ ) ₂ , (cyclohexyl) (methyl) Si (OCH ₃ ) ₂ , (phenyl) ₂ Si (OCH ₃ ) ₂ and (Cyclopentyl) ₂ Si (OCH ₃ ) ₂ .

Preferably, the electron donor compound (c) is used in an amount such that the molar ratio between the organoaluminum compound and the electron donor compound (c) is 0.1 to 500, more preferably 1 to 300, in particular 3 to 100.

As mentioned above, the solid catalyst component includes Ti, Mg and halogen in addition to the electron donor. In particular, the catalyst component comprises a titanium compound having at least one Ti-halogen bond and the aforementioned Mg halide supported electron donor compound. Magnesium halides are preferably MgCl ₂ in active form, which is known in the patent literature as a support for Ziegler-Natta catalysts. Patent USP 4,298,718 and USP 4,495,338 describe for the first time the use of such compounds in Ziegler-Natta catalysis. In this patent, the active form of magnesium dihalide, which is used as a support or known support for the catalyst component for olefin polymerization, reduces the intensity of the strongest diffraction lines appearing in the spectrum of non-active halides in the X-ray spectrum. It is known that it is characterized in that it is replaced by a halo of varying positions of maximum intensity toward smaller angles rather than stronger lines.

Preferred titanium compounds are TiCl ₄ and TiCl ₃ ego; Further also Ti-halo of the formula Ti (OR) n-yXy, where n is the valence of titanium, y is a number between 1 and n, X is a halogen, and R is a hydrocarbon radical of 1 to 10 carbon atoms. Alcoholates can be used.

The preparation of the solid catalyst component can be carried out according to various methods known and described in the art.

According to a preferred method, the solid catalyst component comprises a titanium compound of formula Ti (OR) n-yXy, wherein n is the valence of titanium and y is a number between 1 and n, preferably TiCl _4. It can be prepared by reacting with magnesium chloride derived from an adduct of _{2 ·} pROH, wherein p is a number between 0.1 and 6, preferably between 2 and 3.5, and R is a hydrocarbon radical having 1 to 18 carbon atoms. The adduct can be suitably prepared in spherical form by mixing the alcohol with magnesium chloride in the presence of an incompatible hydrocarbon which is immiscible with the adduct and stirring under conditions of melting temperature of the adduct (100-130 ° C.). The emulsion is then quenched quickly, allowing the adduct to solidify in the form of sphere particles.

Examples of spherical adducts prepared according to this process are described in USP 4,399,054 and USP 4,469,648. The adduct thus obtained is reacted directly with the Ti compound or firstly subjected to heat-controlled dealcoholization (80-130 ° C.) to obtain an adduct having a molar number of alcohols generally less than 3, preferably between 0.1 and 2.5. do. Reaction with the Ti compound suspends the adduct (dealcoholized or as such) in cold TiCl ₄ (generally 0 ° C.); The mixture is heated to 80-130 ° C. and maintained at this temperature for 0.5-2 hours. Such TiCl ₄ The treatment can be performed one or more times. The electron donating compound (s) is TiCl ₄ It can be added during the treatment.

Regardless of the preparation method used, the final content of the electron donor compound (s) is preferably from 0.01 to 1, more preferably from 0.05 to 0.5, molar ratio to MgCl ₂ .

Such catalyst components and catalysts are described in WO 00/63261, WO 01/57099 and WO 02/30998.

Other catalysts that can be used in the process according to the invention are metallocene-type catalysts as described in USP 5,324,800 and EP-A-O 129 368; Particularly advantageous are the crosslinked bis-indenyl metallocenes described, for example, in USP 5,145,819 and EP-A-O 485 823. Other classes of suitable catalysts are the so-called constrained geometry as described in EP-AO 416 815 (Dow), EP-AO 420 436 (Exxon), EP-AO 671 404, EP-AO 643 066 and WO 91/04257. ) Catalyst.

The catalyst can be contacted in advance with a small amount of olefin (prepolymerisation), maintaining the suspension of the catalyst in a hydrocarbon solvent and polymerizing at temperatures from room temperature to 60 ° C. to prepare the polymer in 0.5 to 3 times the catalyst. This operation can be carried out in a liquid monomer, in which case the polymer is produced in 1000 times the catalyst weight.

By using the catalyst, the polyolefin composition is obtained in the form of spheroidal particles having an average diameter of about 250 to 7,000 microns and a flowability and bulk density (compressed) of less than 30 seconds are greater than 0.4 g / mL.

The polymerization step can be carried out in liquid phase, gas phase or liquid-gas phase. Preferably, the polymerization of the crystalline polymer fraction (A) is carried out in a liquid monomer (e.g. using liquid propylene as the diluent), whereas in the elastomeric copolymers (B) and (C) without intermediate steps except partial degassing of propylene The copolymerization steps are carried out in gas phase. According to the most preferred embodiment, all three successive polymerization stages are carried out in gas phase.

The reaction temperature in the polymerization step for the preparation of the crystalline polymer fraction (A) and for the preparation of the elastomeric copolymers (B) and (C) may be the same or different, which preferably has a reaction temperature range of 40 to 100 ° C. ; More preferably, it is 50-80 degreeC in the preparation of fraction (A), and 50-90 degreeC in the manufacture of components (B) and (C).

If the polymerization step for preparing fraction (A) is carried out in a liquid monomer, its pressure competes with the vapor pressure of the liquid propylene at the operating temperature used, which is via the vapor pressure of the small amount of inert diluent used to feed the catalyst. , Through the overpressure of the optical monomer, and through hydrogen used as molecular weight modifier.

The polymerization pressure is preferably in the range from 33 to 43 bar if carried out in the liquid phase and from 5 to 30 bar if carried out in the gas phase. The residence time for the two steps depends on the required ratio between fractions (A) and (B) and (C), which can mainly range from 15 minutes to 8 hours. Conventional molecular weight regulators known in the art such as chain transfer agents (eg hydrogen or ZnEt ₂ ) can be used.

Conventional additives, fillers and pigments mainly used in olefin polymers can be added, such as nucleating agents, extender oils, mineral fillers and other organic and inorganic pigments. In particular, addition of inorganic fillers such as talc, calcium carbonate and mineral fibers can also achieve some improvement in flexural modulus and some mechanical properties such as HDT. Talc also has a nucleating effect.

The nucleating agent is preferably added to the composition of the present invention in the range of 0.05 to 2% by weight, more preferably 0.1 to 1% by weight relative to the total weight.

Specifically, the following examples are presented, which are intended to illustrate the invention without limitation.

The following assay was used to determine the properties reported in the description and in the examples.

Ethylene : Measured by IR spectroscopy.

Fraction soluble and insoluble in xylene at 25 ° C . : 2.5 g of polymer is dissolved in 250 mL of xylene with stirring at 135 ° C. After 20 minutes, the solution is left to cool to 25 ° C with continuous stirring, and then left for 30 minutes. The precipitate is filtered through filter paper, the solution is evaporated in a nitrogen stream and dried under vacuum at 80 ° C. until the residue reaches a constant weight. And the weight% of the polymer which is soluble and insoluble at room temperature (25 degreeC) is measured.

Intrinsic viscosity [η] : Measured in 135 ° C tetrahydronaphthalene.

): 1,2,4-트리클로로벤젠 중에서 겔 투과 크로마토그래피 (GPC) 를 사용하여 측정한다.-Molecular weight (

): Measured using gel permeation chromatography (GPC) in 1,2,4-trichlorobenzene.

Isotactic Determination of pentad content : 50 mg of each xylene insoluble fraction is dissolved in 0.5 mL of C ₂ D ₂ Cl ₄ .

¹³ C NMR spectra are measured with Bruker DPX-400 (100.61 Mhz, 90 ° pulses, 12 sec delay between pulses). About 3000 transients were stored in each spectrum; mmmm pentad peak (21.8 ppm) was used as reference.

Microstructure analysis was performed as described in the literature (Polymer, 1984, 25, 1640, Inoue Y. et al., And Polymer, 1994, 35, 339, Chujo R. et al.).

- a polydispersity of: using a parallel plate viscometer Model RMS-800 available from RHEOMETRICS (USA), is measured by performing, at a frequency which increases in temperature, 0.1 rad / sec of 200 ℃ to 100 rad / second. The PI can be derived from the crossover modulus by the following equation:

[Wherein G '= G' '(G' is storage modulus and G '' is loss modulus) (expressed in Pa) is defined as cross modulus Gc].

This method is used for polymers with MRF levels of 20 g / 10 min or less.

Polydispersity : Measure the molecular weight distribution of the polymer. In order to measure the PI value, the elastic modulus separation, for example, at a loss modulus value of 500 Pa, was carried out at 0.01 rad / sec. Measure at the frequency increasing up to / sec. The PI can be derived from the elastic modulus separation value by the following equation:

,

,

Elastic modulus separation (MS) is defined as follows:

[Wherein G 'is storage modulus and G' 'is loss modulus].

This method is used for polymers with MFR values greater than 20 g / 10 min.

Melt flow rate : measured according to ISO method 1133 (230 ° C., 2.16 kg).

Flexural modulus : measured according to ISO method 178.

-Izod impact resistance : measured according to ISO method 180 / 1A.

- breaking (break) energy is determined in accordance with the internal MA 17324 method. The same test specimens and test methods as the soft / brittle transition temperature (described below) measurement method were used, in which case the energy required for fracture of the sample was measured at −20 ° C.

Soft / brittle transition temperature: measured according to internal method MA 17324 (available on request).

According to this method, biaxial impact resistance is measured through the impact of an automated, computerized striking hammer.

A circular test specimen is obtained by cutting with a circular hand punch (38 mm diameter). It was conditioned at 23 ° C., 50 RH for at least 12 hours and placed in a thermostatic bath set to the test temperature for 1 hour.

In the impact of the striking hammer (5.3 kg, 1.27 mm diameter hemisphere punch), a force-time curve is derived for the circular specimen placed on the ring support. The machine used was CEAST 6758/000 model No. 2.

The D / B transition temperature means the temperature at which 50% of the samples easily break when subjected to the impact test.

Plaques having dimensions of 127 × 127 × 1.5 mm for D / B measurements were prepared according to the following method.

The injection press is a Negri Bossi type (NB 90) with a holding force of 90 tons. The mold is a rectangular plaque (127 x 127 x 1.5 mm).

The main process variables are as follows:

Back pressure (bar): 20

Injection time (seconds): 3

Max injection pressure (MPa): 14

Hydraulic Injection Pressure (MPa): 6-3

1st fixed hydraulic pressure (MPa): 4 ± 2

1st fixed time (seconds): 3

2nd fixed hydraulic pressure (MPa): 3 ± 2

2nd fixed time (seconds): 7

Cooling time (seconds): 20

Mold temperature (℃): 60

The melting point is between 220 and 280 ° C.

Yield and tensile strength at break : measured according to ISO method 527;

Yield and elongation at break : measured according to ISO method 527;

Vicat softening temperature : measured according to ASTM standard D method 1525.

Example  One

Preparation of Solid Catalyst Components

Into a 500 mL four-necked round flask, which was purged with nitrogen, 250 mL of TiCl ₄ was incorporated at 0 ° C. With stirring, 10.0 g of microspheres MgCl ₂ .9 C ₂ H ₅ OH (prepared according to the method described in example 2 of USP 4,399,054, except that it was carried out at 3000 rpm instead of 10000 rpm) and 9.1 mmol of diethyl 2 , 3- (diisopropyl) succinate is added. The temperature is raised to 100 ° C. and maintained for 120 minutes. After stirring is stopped, the solid product is allowed to settle and the supernatant is removed with siphon. Then 250 mL of fresh TiCl ₄ is added. The mixture is allowed to react at 120 ° C. for 60 minutes, and then the supernatant is removed with a siphon. The solid was washed 6 times (6 × 100 mL) with anhydrous hexane at 60 ° C.

Catalytic System and Prepolymerization Treatment

Prior to introduction into the polymerization reactor, the solid catalyst component was contacted with aluminum triethyl (AlEt ₃ ) and dicyclopentyldimethoxysilane (DCPMS) at 12 ° C. for 24 minutes, the amount of AlEt ₃ versus the solid catalyst component The weight ratio is the same to 11 times, and the weight ratio of AlEt ₃ / DCPMS is the same to 4.4.

 Prior to introduction into the first polymerization reactor, the catalyst system is prepolymerized by maintaining suspension for about 5 minutes in 20 ° C. liquid propylene.

polymerization

The polymerization run is carried out continuously in a series of four reactors equipped with a device to transport the product from one reactor to the next. The first two reactors are liquid phase reactors and the third and fourth reactors are fluid bed gas phase reactors. Component (A) is produced in the first and second reactors, while components (B) and (C) are produced in the third and fourth reactors, respectively.

Temperature and pressure remain constant throughout the reaction. Hydrogen is used as molecular weight regulator.

The gas phase (propylene, ethylene and hydrogen) is analyzed continuously via gas chromatography.

At the end of the run the powder is drained and dried under nitrogen flow.

The polymer particles are then introduced into an extruder, where they are mixed with nucleated with 8500 ppm talc, 1500 ppm Irganox B 215 (made of 1 part Irganox 1010 and 2 parts Irgafos 168) and 500 ppm Ca stearate. ) To obtain a composition. Irganox 1010 is pentaerythritol tetrakis 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propanoate, while Irgafos 168 is tris (2,4-di-tert-butylphenyl ) Phosphite and both are commercially available from Ciba-Geigy. The polymer particles were extruded through a twin screw extruder under a nitrogen atmosphere, with a rotational speed of 250 rpm and a melting temperature of 200-250 ° C.

Example  2

The polymerization run is carried out in a series of three reactors, and Example 1 is repeated except that only the first one is a liquid phase reactor.

Analytical data for the main polymerization conditions and the polymer produced in the reactors are reported in Table 1.

The single components, amounts and properties of the polyolefin compositions, and the properties of the entire polyolefin composition are reported in Tables 2 and 3, respectively.

Comparative example  One

Example 1 is repeated in the same manner, except that elastomeric polyolefins of the same type as produced in the first gas phase reactor are produced in the second gas phase reactor.

Comparative example  2 and 3 (2c and 3c)

Except for including diisobutylphthalate instead of diethyl 2,3- (diisopropyl) succinate, except that elastomeric polyolefins of the same type as produced in the first gas phase reactor are produced in the second gas phase reactor And repeating Example 1 in the same manner by replacing the catalyst component with the same catalyst component as described above.

TABLE 1

Polymerization process

TABLE 2

Composition analysis

continue

TABLE 3

Characteristics of the whole composition

Claims (4)

Heterophasic polyolefin compositions comprising (% by weight): (A) 50 to 80%, with polydispersity readings of 5.2 to 10, of isotactic pentad (mmmm) measured in fractions insoluble in xylene at 25 ° C. by ¹³ C-NMR. Crystalline propylene polymers; The polymer is a propylene homopolymer and a copolymer of propylene and propylene and at least one comonomer selected from α-olefins of the formula H ₂ C═CHR, wherein R is a C ₂ comprising at least 95% of repeating units derived from propylene Linear or branched alkyl radicals which are _-6 ; (B) propylene) and (H ₂ C = CHR of another one or more selected from α- olefin co-monomer in the first elastomeric copolymer of ethylene from 5 to 20%, wherein R is C _{2 -6} straight or branched alkyl Radical; The first elastomeric copolymer comprises less than 25-40% ethylene, is more than 85-95 wt% soluble in xylene at room temperature, and the intrinsic viscosity [η] of the xylene soluble fraction is 2.5-4.5 dL / g Range; And (C) 10 to 40% of a second elastomeric copolymer of ethylene with at least one comonomer selected from propylene and another α-olefin of formula H ₂ C═CHR; Wherein R is C _{2 -6} straight or branched alkyl radical being; The second elastomeric copolymer comprises 50 to 75% of ethylene, is 50 to 85% by weight soluble in xylene at room temperature, and the intrinsic viscosity [η] of the xylene soluble fraction ranges from 1.8 to 4.0 dL / g. ; Wherein the sum of the amounts of copolymer (B) and copolymer (C) ranges from 20 to 45% relative to the total amount of components (A) to (C) and the total amount of ethylene relative to the total amount of components (A) to (C) Is up to 23% by weight, the content of fraction ethylene insoluble in xylene at room temperature (C ₂ xif) multiplied by the weight percent (% XIF) of xylene insoluble at room temperature, and the fraction soluble in xylene at room temperature The ratio between fractional ethylene content (C ₂ xsf) soluble in xylene at room temperature multiplied by% by weight (% SXF) of ie, (C ₂ xif x% XIF) / (C ₂ xsf x% SXF) is given by Satisfies relation (I):

[Wherein x is the total amount of ethylene]. 2. A component according to claim 1, wherein component (A) shows a molecular weight distribution in component (A), which is the ratio between the weight average molecular weight and the number average molecular weight, ie

Expressed in terms of GPC, which is greater than or equal to 9 and the z mean molecular weight to weight average molecular weight ratio,

The composition which is 4.5 or more when the value of is measured by GPC. A process for preparing an olefin polymer composition according to claim 1 comprising at least three sequential steps, wherein components (A), (B) and (C) are prepared in separate successive steps, Wherein each step is carried out in the presence of the polymer formed in the previous step and the catalyst used. The process of claim 3, wherein the polymerization catalyst is a Ziegler-Natta catalyst comprising a solid catalyst component comprising: a) Mg, Ti and an electron donor selected from halogen and succinate, preferably succinate of formula (I) or formula (II): [Formula I]

[Wherein, the same or different radicals R ₁ And R ₂ silver C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups optionally containing heteroatoms; Radicals R ₃ to R _{6, which} are the same or different from each other, are C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups optionally containing hydrogen or heteroatoms; The radicals R ₃ to R ₆ linked to the same carbon atom may be bonded to each other to form a ring, provided that when R ₃ to R ₅ are hydrogen at the same time, R ₆ is a primary branched, secondary having 3 to 20 carbon atoms. Or a tertiary alkyl group, cycloalkyl, aryl, arylalkyl or alkylaryl group or a linear alkyl group having 4 or more carbon atoms optionally including heteroatoms; [Formula II]

[Wherein, the same or different radicals R ₁ And R ₂ Is a C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group optionally containing heteroatoms and is a radical R ₃ Is a linear alkyl group of 4 or more carbon atoms optionally containing heteroatoms; b) alkylaluminum compounds and, optionally, c) one or more electron-donor compounds (external donors).