RU2451699C2 - Polyolefin compositions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to polyolefin compositions for making films. The composition contains 55-80 wt % propylene homopolymer and 20-45 wt % copolymer of ethylene and one or more C₄-C₁₀-olefins, containing 10-40% of said C₄-C₁₀-olefin(s). The composition has melt flow rate MFR (230°C, 2.16 kg) from 1 to 4 g/10 min, overall content of ethylene from 20 wt % to 40 wt %, overall content of C₄-C₁₀ α-olefin(s) from 6 wt % to 15 wt % and ratio of overall content of ethylene to overall content of C₄-C₁₀ α-olefin(s) equal to or greater than 2.3. The overall content of a fraction which is soluble in xylene at room temperature ranges from 18 wt % to 30 wt %, and the modulus of elasticity in flexure, relating to the reactor-grade composition, is higher than 700 MPa.

EFFECT: disclosed composition is characterised by low melt flow rate values which are suitable for obtaining films cast from a solution, and biaxially oriented films with high gas-permeability (air-permeability), low turbidity (good optical properties) and high modulus of elasticity in flexure (hardness) in addition to said unique balance of properties, impact viscosity at low temperature, lustre and good shrinkage characteristics.

4 cl, 2 tbl, 5 ex

Description

The present invention relates to polyolefin compositions containing a propylene polymer component selected from propylene homopolymers and propylene random copolymers containing ethylene and / or other α-olefins as comonomers and a copolymer of ethylene and C ₄ -C ₁₀ α-olefins.

The compositions of the present invention can be easily converted into various types of end products or semi-finished products. In particular, compositions of the present invention, characterized by high values of the melt flow rate (MFR), are particularly well suited for use in the manufacture of products using injection molding methods, since they essentially do not undergo whitening under loading, which is combined with the presence of rigidity High gloss and low shrinkage. Thus, these compositions can be used for several applications, including toys, cladding and utensils, in particular, in those products that also require resistance to shock loads at low temperatures without destroying the products. In addition, the products mentioned can be advantageously used in applications including contact with food, examples of which are food containers suitable for use in freezers. The compositions of the present invention, characterized by low values of CTP, are suitable for use in the fields of application of films, in particular, films cast from a solution, and biaxially oriented films, characterized by high gas permeability (breathability), low turbidity (good optical properties) and high modulus bending elasticity (rigidity) in addition to the aforementioned unique balance of properties, toughness at low temperature, gloss and good shrink characteristics. Thus, these compositions can be used, in particular, for those applications of films that require breathability, good optical properties and rigidity, such as in the case of packaging for fresh vegetables, laminated sterilized and flexible packaging and transparent sterilized bags.

Compositions containing a crystalline polypropylene matrix and a rubber phase formed by an elastomeric copolymer of ethylene and α-olefins are already known in the art and are described, in particular, in European patents 170 255, 373 660, 603723 and 1135440 and in international application WO 04 / 003073.

The mentioned compositions are characterized by resistance to shock loads and in the case of European patents 373 660, 603723, 1135440 and document WO 04/003073 transparency levels, interesting for many applications. However, given the high market standards, the overall balance of properties is still not entirely satisfactory in the whole spectrum of possible applications. In the case of document WO 04/003073, a valuable balance of properties has been obtained, but the balance of toughness and stiffness is not entirely satisfactory for some applications, the preferred values of the bending modulus are still unsatisfactory, especially considering the use of a brightening nucleating agent (Millad). Therefore, there is still a constant need for compositions of this type having improved properties balanced for specific target applications.

Obtaining an excellent balance of properties has now been achieved using the polyolefin compositions of the present invention, containing, in weight percent, based on the weight of the sum of components 1) and 2):

1) 55-80% of a propylene homopolymer or copolymer, wherein said copolymer contains up to 15% ethylene and / or C ₄ -C ₁₀ α-olefin (olefins);

2) 20-45% of a copolymer of ethylene and one or more C ₄ -C ₁₀ α-olefin (olefins) containing from 10 to 40% of the above C ₄ -C ₁₀ α-olefin (olefins);

at the same time, the mentioned compositions are characterized by values of STR (230ºC, 2.16 kg), reaching up to 20 g / 10 min, a combined ethylene content of 20% or more, a combined level of C ₄ -C ₁₀ α-olefin (olefins) equal to 4.5% or more, the ratio between the total level of ethylene and the total level of C ₄ -C ₁₀ α-olefin (olefins), equal to 2.3 or more, the total level of the fraction soluble in xylene at room temperature, equal to 18% (mass.) and more, and the modulus of elasticity in bending related to the composition and reactor grade greater than 700 MPa.

In particular, preferred features of the compositions of the present invention are:

- the intrinsic viscosity of a fraction soluble in xylene at room temperature of 2 dl / g or less, preferably 1.7 dl / g or less, more preferably in the range of 1.1 to 1.7 dl / g, even more preferably 1.1 to 1.5 dl / g;

bending modulus greater than 770 MPa, more preferably greater than 800 MPa;

- the level of component 2) (the level of the component in the mixture) 25-45%, preferably 25-40%, while the percentages mentioned are mass and are obtained when calculating the mass of the sum of components 1) and 2);

- the level of the polymer insoluble in xylene at room temperature (23 ° C), for component 1), not less than 90%, in particular, not less than 93%, while the percentages mentioned are mass and are calculated based on the weight of component 1 );

- the total level of ethylene content from 20%: up to 40% (mass.);

- the total content of C ₄ -C ₁₀ α-olefin (olefins) from 6% to 15% (mass.);

- the level of the fraction soluble in xylene at room temperature, less than 35%, more preferably less than 30% (mass.);

The temperature of the transition from a plastic to a brittle state is generally equal to or lower than -35 ° C, while the lower limit is approximately -60 ° C.

Throughout the course of the present description of the invention, the term "copolymer" also includes the inclusion of polymers containing, in addition to the basic monomer, more than one type of additional comonomers.

The compositions of the present invention provide, in particular, a combination of high impact resistance (expressed as the transition temperature from plastic to brittle and impact resistance in the Izod test), high gloss, very high whitening resistance under loading and low thermal shrinkage measured for plates, and high gas permeability and good transparency, measured for films. Polyolefin compositions preferred for use in injection molded articles are flexible polyolefin compositions characterized by high fluidity, high resistance to whitening under loading, and low thermal shrinkage, containing, in weight percent, based on the weight of the sum of components 1) and 2) :

1) 55-80%, preferably 55-75%, more preferably 60-70% of a propylene homopolymer or copolymer, wherein said copolymer contains up to 15% ethylene and / or C ₄ -C ₁₀ α-olefin (olefins) and is characterized a CTP value of 15 g / 10 min or more, preferably 30 g / 10 min or more; and

2) 20-45%, preferably 25-45%, more preferably 30-40% of a copolymer of ethylene and one or more C ₄ -C ₁₀ α-olefins (olefin) containing from 15 to 40% of the above C ₄ -C ₁₀ α -olefins (olefin);

while the above compositions are characterized by values of STR (230ºC, 2.16 kg) in the range from 10 to 20 g / 10 min, a combined ethylene content of 20% or more, a combined level of C ₄ -C ₁₀ α-olefin (olefins ), equal to 6% or more, the ratio between the total level of ethylene and the total level of C ₄ -C ₁₀ α-olefin (olefins) equal to 2.3 or more, the total level of the fraction soluble in xylene at room temperature equal to 18% (mass.) And more, preferably at least 20% (mass.), And the modulus is elastic bending related to the composition of the reactor grade greater than 700 MPa.

Particularly advantageous properties are found in the case of obtaining a composition suitable for use in the previously described field of application of injection molding, with the addition of nucleating agents such as Na benzoate (see below). Improved mechanical properties, in particular surprisingly high values in the Izod test, are found without significantly affecting the overall balance of other properties, gloss, whitening resistance during loading, and shrinkage. The aforementioned polyolefin composition, preferred for use in the field of injection molding, is particularly suitable for use as a substitute for ABS plastic.

Polyolefin compositions preferred for use in the fields of application of films, in particular cast films and biaxially oriented films, characterized by high gas permeability, good optical properties and stiffness measured for films, are those that contain in mass percent calculated on mass of the sum of components 1) and 2):

1) 55-80%, preferably 55-75%, more preferably 65-75% of a propylene homopolymer or copolymer, said copolymer containing up to 15% ethylene and / or C ₄ -C ₁₀ α-olefin (olefins); and

2) 20-45%, preferably 25-45%, more preferably 25-35% of a copolymer of ethylene and one or more C ₄ -C ₁₀ α-olefins (olefin) containing from 15 to 40% of the above C ₄ -C ₁₀ α -olefins (olefin);

however, these compositions are characterized by values of STR (230ºC, 2.16 kg), reaching up to 10 g / 10 min, preferably in the range from 1 to 4 g / 10 min, with a combined ethylene content of 20% or more, combined the level of C ₄ -C ₁₀ α-olefin (olefins) equal to 6% or more, the ratio between the total level of ethylene and the total level of C ₄ -C ₁₀ α-olefin (olefins) equal to 2.3 or more, total the level of the fraction soluble in xylene at room temperature equal to 18% (mass.) and more preferably at least 20% (mass.), and a bending modulus greater than 700 MPa. Mentioned C ₄ -C ₁₀ α-olefins which are present or may be present as comonomers in the components and fractions of the compositions of the present invention are described by the formula CH ₂ = CHR, where R is an alkyl radical, linear or branched, containing 2-8 carbon atoms or an aryl (in particular phenyl) radical.

Examples of said C ₄ -C ₁₀ α-olefins are 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene and 1-octene. Particularly preferred is 1-butene.

The compositions of the present invention can be obtained as a result of stepwise polymerization, which includes at least two sequential stages, where components 1) and 2) are obtained in separate sequential stages, performing operations at each stage except for the first stage in the presence of the polymer obtained in the preceding step, and the catalyst used therein. The catalyst is preferably added only in the first stage, however, its activity is such that it is still active for all subsequent stages.

Preferably, component 1) is prepared prior to component 2).

Therefore, the present invention further relates to a method for producing the previously described polyolefin compositions, wherein said method comprises at least two step polymerization steps, each subsequent polymerization being carried out in the presence of a polymer material obtained in the immediately preceding polymerization reaction, where the polymerization step is propylene for for producing the polymer component 1), at least one step is carried out, after which at least one copoly step is carried out merization of mixtures of ethylene and one or more C ₄ -C ₁₀ α-olefins (olefin) to obtain an elastomeric polymer component 2). The polymerization stages can be carried out in the presence of a stereospecific Ziegler-Natta catalyst.

In accordance with one preferred embodiment, all polymerization steps are carried out in the presence of a catalyst containing a trialkyl aluminum derivative, optionally an electron donor and a solid catalyst component containing a Ti halide or alkalohalate and an electron donor compound supported on an support in the form of anhydrous magnesium chloride. Catalysts having the above characteristics are well known in the patent literature; particularly advantageous are the catalysts 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 containing a solid catalyst component comprising:

a) Mg, Ti and halogen and electron donor (internal donor),

b) an aluminum alkyl derivative and optionally (but preferably)

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

The internal donor is preferably selected from esters of mono- or dicarboxylic organic acids, such as benzoates, malonates, phthalates and certain succinates. They are described, for example, in US patent 4522930, European patent 45977 and international patent applications WO 00/63261 and WO 01/57099. Phthalic esters and succinic esters are particularly suitable for use. Alkyl phthalates such as diisobutyl, dioctyl and diphenyl phthalate and benzyl butyl phthalate are preferred.

Among the succinates, the choice is preferably made from succinates described by the following formula (I):

where the radicals R ₁ and R ₂ identical to each other or different from each other, represent a C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms; R ₃ -R ₆ radicals, identical to each other or different from each other, represent hydrogen or a C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms; and R ₃ -R ₆ radicals that are attached to the same carbon atom can be bonded to each other to form a ring; with the proviso that if R ₃ -R ₅ will simultaneously be hydrogen, then R ₆ will be a radical selected from primary branched, secondary or tertiary alkyl groups, cycloalkyl, aryl, arylalkyl or alkylaryl groups containing from 3 up to 20 carbon atoms;

or the following formula (II):

where the radicals R ₁ and R ₂ identical to each other or different from each other, represent a C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms, and the radical R ₃ represents a linear alkyl group containing at least four carbon atoms, optionally containing heteroatoms.

Al-alkyl compounds used as cocatalysts include Al-trialkyls such as Al-triethyl, Al-triisobutyl, Al-tri-n-butyl, and linear or cyclic Al-alkyl compounds containing two or more Al atoms with each other using O or N atoms or SO ₄ or SO ₃ groups. The Al-alkyl compound is generally used in such an amount that the Al / Ti ratio is in the range of 1 to 1000. The external donor (s) may be of the same type as the succinates described by formula (I) or ( II), or it may differ from them. Suitable external electron donor compounds include silicon compounds, ethers, esters such as phthalates, benzoates, succinates, also having a structure different from those described by formulas (I) or (II), amines, heterocyclic compounds, and in particular , 2,2,6,6-tetramethylpiperidine, ketones and 1,3-diesters described by the general formula (III):

where R ^I and R ^II are identical or different and are C ₁ -C ₁₈ alkyl, C ₃ -C ₁₈ cycloalkyl or C ₇ -C ₁₈ aryl radicals; R ^III and R ^IV are identical or different and are C ₁ -C ₄ alkyl radicals; or 1,3-diethers in which the carbon atom in position 2 refers to a cyclic or polycyclic structure formed from 5, 6 or 7 carbon atoms and containing two or three unsaturations. Ethers of this type are described in published European patent applications 361493 and 728769.

Preferred electron donor compounds that can be used as external donors include silicon aromatics containing at least one Si — OR bond, where R is a hydrocarbon radical. A particularly preferred class of external donor compounds is the class of silicon compounds described by the formula R _a ⁷ R _b ⁸ Si (OR ⁹ ) _c , where a and b are an integer in the range from 0 to 2, c is an integer in the range from 1 to 3, and the sum (a + b + c) is 4; R ⁷ , R ⁸ and R ⁹ are C ₁ -C ₁₈ hydrocarbon groups optionally containing heteroatoms. Particularly preferred are silicon compounds in which a is 1, b is 1, c is 2, at least one of R ⁷ and R ^{8 is} selected from branched alkyl, alkenyl, alkylene, cycloalkyl or aryl groups containing 3-10 carbon atoms optionally containing heteroatoms, and R ⁹ represents a C ₁ -C ₁₀ alkyl group, in particular methyl. Examples of such preferred silicon compounds are cyclohexyltrimethoxysilane, tert-butyltrimethoxysilane, tert-hexyltrimethoxysilane, cyclohexylmethyldimethoxysilane, 3,3,3-trifluoropropyl-2-ethylpiperidyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethyldimethylenediodimethysilane in high volume apart from one another wide in size. (1,1,1-trifluoro-2-propyl) methyldimethoxysilane; and (1,1,1-trifluoro-2-propyl) -2-ethylpiperidinyl dimethoxysilane. In addition, silicon compounds are also preferred in which a is 0, c is 3, R ⁸ is a branched alkyl or cycloalkyl group optionally containing heteroatoms, and R ⁹ is methyl. Particularly preferred specific examples of silicon compounds are (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 such an amount as to obtain a molar ratio between the organoaluminum compound and said electron donor compound (c) in the range from 0.1 to 500, more preferably from 1 to 300, and in particular from 3 to 30.

As explained previously, the solid catalyst component in addition to the aforementioned electron donors contains Ti, Mg and halogen. In particular, the catalyst component comprises a titanium compound containing at least a Ti-halogen bond, and the aforementioned electron-donor compounds supported on Mg halide. The magnesium halide is preferably MgCl ₂ in active form, which is well known from the patent literature as a carrier for Ziegler-Natta catalysts. USP 4,298,718 and USP 4,495,338 were the first to describe the use of these compounds in Ziegler-Natta catalysis. As is known from these patents, magnesium dihalides in active form, used as a carrier or an auxiliary carrier in the components of olefin polymerization catalysts, are characterized by X-ray spectra in which the most intense diffraction line that appears in the spectrum of an inactive halide decreases in intensity and is replaced by a halo, the maximum intensity of which shifts in the direction of smaller angles with respect to the angle of a more intense line.

Preferred titanium compounds are TiCl ₄ and TiCl ₃ ; in addition, Ti halogenated, described by the formula Ti (OR) n-yXy, where n represents the valence of titanium, y represents a number in the range from 1 to n, X represents a halogen, and R represents a hydrocarbon radical, can also be used. containing from 1 to 10 carbon atoms.

The preparation of the solid catalyst component can be carried out in accordance with several methods well known and described in the art.

In accordance with one preferred method, a solid catalyst component can be obtained by reacting a titanium compound of the formula Ti (OR) n-yXy, where n is titanium valence and y is a number in the range from 1 to n, preferably TiCl ₄ and magnesium chloride formed from the adduct of the formula MgCl ₂ · pROH, where p is a number in the range from 0.1 to 6, preferably from 2 to 3.5, and R is a hydrocarbon radical containing 1- 18 carbon atoms. In an appropriate case, the adduct can be obtained in spherical form by mixing alcohol and magnesium chloride in the presence of an inert hydrocarbon immiscible with the adduct, performing the operation under stirring conditions at the melting point of the adduct (100-130 ° C). After this, the emulsion is quickly cooled, thereby causing the solidification of the adduct in the form of spherical particles.

Examples of spherical adducts prepared in accordance with this procedure are described in USP 4,399,054 and USP 4,469,648. Thus, the resulting adduct can be directly reacted with the Ti compound, or it can be preliminarily subjected to thermally controlled dealcoholation (80-130 ° C) in order to obtain an adduct in which the number of moles of alcohol is generally less than 3, preferably ranging from 0.1 to 2.5. The reaction with Ti can be carried out by suspending the adduct (subjected to dealcoholation or as such) in cold TiCl ₄ (generally 0 ° C); the mixture is heated up to 80-130ºС and maintained at this temperature for 0.5-2 hours. Processing under the influence of TiCl ₄ can be carried out one or more times. During treatment with TiCl ₄ , an electron-donating compound (s) can be added.

Regardless of the manufacturing method used, the final amount of electron-donating compound (s) is preferably such that the molar ratio between it and MgCl _{2 is} in the range from 0.01 to 1, more preferably from 0.05 to 0.5.

The catalysts can be pre-contacted with small amounts of olefin (prepolymerization) while keeping the catalyst in suspension in a hydrocarbon solvent and carrying out polymerization at temperatures in the range from ambient temperature to 60 ° C, thus obtaining polymer in an amount in the range from 0, 5 to 3 times the mass of the catalyst. The operation can also be carried out in liquid monomer to obtain in this case a polymer in an amount of 1000 times the mass of the catalyst.

Using the above catalysts, polyolefin compositions are obtained in the form of spheroidal particles, the particles having an average diameter in the range of from about 250 to 7000 μm, a flowability of less than 30 seconds, and a bulk density (in the packed state) of more than 0.4 g / ml

The polymerization stages can be carried out in the liquid phase, in the gas phase or in the gas-liquid phase. Preferably, the polymerization to obtain the polymer component 1) is carried out in a liquid monomer (for example, using liquid propylene as a diluent), while the copolymerization steps to obtain an elastomeric copolymer component 2) are carried out in the gas phase. Alternatively, all stages of stepwise polymerization can be carried out in the gas phase.

The reaction temperature at the polymerization stage to obtain the polymer component 1) and upon receipt of the elastomeric copolymer component 2) can be identical or different and preferably is in the range from 40 to 100 ° C; more preferably, the reaction temperature is in the range from 50 to 80 ° C for the production of polymer component 1) and from 70 to 100 ° C for the production of polymer component 2).

The pressure in the polymerization step when producing the polymer component 1) if it is carried out in a liquid monomer, is a pressure that competes with the vapor pressure of liquid propylene at the operating temperature used, and it can be modified with the vapor pressure of a small amount of inert diluent used to supply the catalyst mixture , overpressure of optional monomers and hydrogen, used as a regulator of the degree of polymerization.

The polymerization pressure is preferably in the range from 33 to 43 bar in the case of the operation in the liquid phase and in the range from 5 to 30 bar in the case of the operation in the gas phase. The residence times for the steps depend on the desired ratio between the amounts of the polymer components 1) and 2) and can usually range from 15 minutes to 8 hours. Conventional polymerization degree regulators known in the art can be used, such as kinetic chain transmitters (e.g. hydrogen or ZnEt ₂ ).

The compositions of the present invention can also be obtained by separately obtaining the mentioned components 1) and 2) during the operation using the same catalysts and essentially the same polymerization conditions as previously explained (except that the process is completely stepwise polymerization will not be carried out, and the mentioned components will be obtained in separate stages of polymerization), and after this mechanical mixing of the mentioned components in molten or softened standing. Conventional mixing equipment similar to screw extruders, in particular twin screw extruders, can be used.

The compositions of the present invention may also contain additives commonly used in the art, such as antioxidants, light stabilizers, heat stabilizers, nucleating agents, colorants, and fillers.

In particular, the addition of nucleating agents leads to a significant improvement in important physical and mechanical properties, such as bending elastic modulus, deformation heat resistance (DT), tensile strength at yield strength and transparency.

Typical examples of nucleating agents are Na benzoate, talc and 1,3- and 2,4-dibenzylidene sorbitol.

The nucleating agents in the composition of the present invention are preferably added in amounts in the range from 0.01 to 2% (mass.), More preferably from 0.05 to 1% (mass.), Based on the total weight.

The addition of inorganic fillers, such as talc, calcium carbonate and mineral fibers, also improves some mechanical properties, such as flexural modulus and DT.

Details are given in the following examples, which are presented to illustrate the present invention without limiting it.

Examples 1-2

In the installation, operating continuously in accordance with the method of mixed gas-liquid polymerization, experiments were carried out under the conditions shown in table 1.

The polymerization was carried out in the presence of a catalyst system in a sequence of two reactors equipped with devices for transferring the product from one reactor to another immediately following it.

Obtaining a solid catalyst component

The Ziegler-Natta catalyst was prepared in accordance with Example 5, lines 48-55 of European patent EP728769. Triethylaluminum (TEAL) was used as a cocatalyst, and dicyclopentyldimethoxysilane was used as an external donor at the weight ratios shown in Table 1.

Catalyst system and prepolymerization treatment

The previously described solid catalyst component was contacted with triethylaluminium (TEAL) and dicyclopentyl dimethoxysilane (DCPMS) for 24 minutes at 12 ° C as an external electron-donating component. The mass ratio between TEAL and the solid component of the catalyst and the mass ratio between TEAL and DSPMS are presented in table 1.

After that, the catalyst system is subjected to prepolymerization as a result of keeping it in suspension in liquid propylene at 20 ° C for approximately 5 minutes before it is introduced into the first polymerization reactor.

Polymerization

The polymerization experiment is carried out continuously in a sequence of three reactors equipped with devices for transferring the product from one reactor to another immediately following it. The first reactor is a liquid phase reactor, and the second reactor is a gas phase fluidized bed reactor. The polymer component 1) is obtained in the first reactor, while the polymer component 2) is obtained in the second reactor.

Throughout the course of the reaction, the temperature and pressure are kept constant.

Hydrogen is used as a regulator of the degree of polymerization.

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

At the end of the experiment, the powder is unloaded and dried in a stream of nitrogen.

Data relating to the level of the xylene soluble fraction and comonomer in the final polymer compositions shown in Tables 1 and 2 are obtained from measurements carried out for the polymers thus obtained, if necessary stabilized.

After that, the polymer particles are introduced into the extruder, where they are mixed with 1,500 ppm Irganox B 215 (formed from 1 part Irganox 1010 and 2 parts Irgafos 168) and 500 ppm Ca stearate. The previously mentioned Irganox 1010 preparation is pentaerythritol (tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl)) propanoate), while the Irgafos 168 preparation is tris (2,4-di-tert -butylphenyl) phosphite, both of which are marketed by Ciba-Geigy. In Example 1b, extrusion was carried out in the absence of Ca stearate and in the presence of 900 ppm Na benzoate to obtain a nucleated composition. The polymer particles are extruded in a nitrogen atmosphere in a twin-screw extruder at a rotation speed of 250 rpm and a melt temperature of 200-250 ° C.

Data related to the physicomechanical properties of the final polymer compositions shown in Table 2 are obtained from measurements taken for the extruded polymers in this way.

The data shown in the tables are obtained using the following test methods.

- Molar ratios for gaseous feedstocks

Determined by gas chromatography.

- The level of ethylene and 1-butene in the polymers

Determined by the method of IR spectroscopy.

- Melt flow rate (MFR)

Determined in accordance with ASTM D 1238, condition L (MFR "L").

- The level of fractions soluble and insoluble in xylene

Determined as follows.

2.5 g of polymer and 250 ml of xylene are introduced into a glass flask equipped with a refrigerator and a magnetic stirrer. The temperature is increased for 30 minutes up to the boiling point of the solvent. The clear solution thus obtained is then kept for another 30 minutes by boiling under reflux and stirring. After that, the closed flask is kept at 100ºС for 10-15 minutes, and also in a thermostatic water bath at 25ºС for 30 minutes. The solid thus obtained is filtered on paper for quick filtering. 100 ml of the filtered liquid is poured into a pre-weighed aluminum container, which is heated on a hot plate in a stream of nitrogen to remove the solvent by evaporation. After that, the container is kept in an oven at 80 ° C in vacuum until a constant weight is obtained. Then calculate the mass percentage of the polymer soluble in xylene at room temperature.

- Intrinsic viscosity (H.V.)

Determined in tetrahydronaphthalene at 135 ° C.

- Flexural modulus

Determined in accordance with ISO 178.

- Impact resistance in the Izod test (notched)

Determined in accordance with ISO 180 / 1A.

- Obtaining samples of plates

Plates intended for measuring P / X and resistance to whitening under loading and having dimensions of 127 × 127 × 1.5 mm were obtained as follows.

The injection machine was a Negri Bossi ™ type device (NB 90), characterized by a clamping force of 90 tons. The shape was a rectangular plate (127 × 127 × 1.5 mm).

The main technological parameters are presented below:

Back pressure (bar): twenty Injection Time (sec): 3 Maximum casting pressure (MPa): fourteen Casting Hydraulic Pressure (MPa): 6-3 Hydraulic pressure of the first exposure (MPa): 4 ± 2 First exposure time (sec): 3 Second pressure hydraulic pressure (MPa): 3 ± 2 Second exposure time (s): 7 Cooling time (s): twenty Form temperature (ºС): 60

The melt temperature was in the range from 220 to 280 ° C.

Plates intended for measuring turbidity and having a thickness of 1 mm were obtained by injection molding at an injection time of 1 second, a temperature of 230 ° C, and a mold temperature of 40 ° C.

The injection machine was a Battenfeld ™ type BA 500CD device with a clamping force of 50 tons. The forming insert of the mold led to the formation of two plates (each 55 × 60 × 1 mm).

- Obtaining samples of films cast from a solution

Films having a thickness of 50 μm were obtained by extruding each polymer composition in a Collin single screw extruder (screw length / diameter ratio: 30) at a film drawing speed of 7 m / min and a melt temperature of 210-250 ° C.

- Obtaining a film of biaxially oriented polypropylene intended for measuring PC

The polymer composition was directly pressed on a CARVER installation at 230 ° C to obtain a plate having a thickness of 1 mm and dimensions 60 × 60 mm, and after stretching using a TM-Long installation at an oven temperature of 150 ° C and a stretching ratio of 6 × 6 in both directions to obtain a film biaxially oriented polypropylene having a thickness of 30 μm.

- Temperature transition from plastic to brittle (P / X)

Determined in accordance with the following method. Resistance to biaxial shock loads was determined upon impact by an automatic computerized shock striker.

From the plates obtained as described previously, as a result of cutting using a circular hand punch (diameter 38 mm) received round samples for testing. They were conditioned for at least 12 hours at 23 ° C and RH 50%, and then placed for 1 hour in a thermostatic bath at the test temperature.

During a shock impact strike (5.3 kg, a hemispherical punch with a diameter of 1.27 cm), a force-time curve was recorded on a circular specimen resting on an annular support. The installation used was CEAST 6758/000 type model No. 2.

- The P / X transition temperature denotes the temperature at which 50% of the samples undergo brittle fracture when the impact test is referred to.

- Resistance to whitening under loading

Whitening resistance at ambient temperature (approximately 23 ° C) was determined as a result of exposure to small test polymer disks (diameter 38 mm, thickness 1.5 mm, obtained from plates obtained as described previously) by a pointed load falling from various heights. The pointed load had a diameter of 1.27 mm and a weight of 263 g. The whitening resistance during loading is expressed in terms of the whitening region diameter (average of 10 test specimens at each drop height).

Both the height and the width (diameter) of the whitening region are recorded, which is shown in table 2.

- Longitudinal and transverse thermal shrinkage

Rectangular test specimens having dimensions of 100 × 200 × 2.5 mm were obtained by injection molding using a Sandretto Serie Sette 190 device (where 190 is 190 tons of clamping force). The main technological parameters are presented below:

- Back pressure: 10 bar - Injection time + holding time: 30 s - Cumulative cycle time: 55 s - Form temperature: 40ºС - Melt temperature: 250ºС

The size of the test samples was measured using a three-dimensional measurement system supplied with a “contact sensor” (Microval 3D). Shrinkage is the difference between the initial dimensions of the sample after injection and the dimensions after 48 hours of conditioning at 23 ° C, and it was expressed as a percentage when calculating the initial dimensions of the sample. Longitudinal shrinkage is shrinkage measured in the direction of injection flow; lateral shrinkage is a shrinkage measured across the direction of injection flow.

- Turbidity for the plate

Determined in accordance with the following method. The plates obtained as described previously were conditioned for a period of 12 to 48 hours at a relative humidity of 50 ± 5% and a temperature of 23 ± 1ºС.

The device used for testing was a Gardner photometer with a Haze-meter UX-10 device equipped with a GE 1209 lamp and filter C. The device was calibrated as a result of measurements in the absence of a sample (0% turbidity) and measurements with a blocked light beam (100 % turbidity).

The principles of measurement and calculation are given in ASTM-D 1003. Turbidity was measured for five plates.

- Glitter for the plate

10 rectangular samples (55 × 60 × 1 mm) for each polymer for testing were obtained by the injection molding method using a Battenfeld BA500CD injection machine operating under the following conditions:

Worm rotation speed: 120 rpm Back pressure: 10 bar Mold temperature: 40ºС Melt Temperature: 260ºС Injection time: 3 s First exposure time: 5 s Second exposure time: 5 s Cooling time (after the second exposure): 10 s

The pressure value of the casting should be sufficient to completely fill the form for the aforementioned specified time period.

When using a bright meter, the fraction of the light flux reflected by the surface of the sample under study was measured at an incidence angle of 60 °. The value shown in table 2 corresponds to the average level of gloss for 10 samples of each polymer for testing.

The brightness meter used was a Zehntner model ZGM 1020 or 1022 photometer with an incidence angle of 60 °. The measurement principle is given in Norm ASTM D2457. Calibration of the equipment is carried out using a sample characterized by a known level of gloss.

- Turbidity for the film

Determined for having a thickness of 50 μm films of the composition for testing, obtained as described previously. The measurement was carried out for a portion of 50 × 50 mm cut off from the central zone of the film.

The device used for testing was a Gardner photometer with a Haze-meter UX-10 device equipped with a GE 1209 lamp and filter C. The device was calibrated as a result of measurements in the absence of a sample (0% turbidity) and measurements with a blocked light beam (100 % turbidity).

- Glitter for film

Determined for the same samples as in the case of turbidity.

The instrument used for testing was a model 1020 Zehntner photometer for measuring incident light. Calibration was made as a result of measurements at a dip angle of 60 ° on black glass, characterized by a standard gloss level of 96.2%, and measurements at a dip angle of 45 ° on black glass, characterized by a standard gloss level of 55.4%.

- The passage of oxygen (PC)

Measured using a Mocon OX-TRAN 2/61 apparatus, commercially available from Mocon, Inc., at 23 ° C, a relative humidity (RH) of 0% and 100% O ₂ .

Comparative Example 1c

For comparison, the final properties of the composition of example 3 are given in international application WO 04/003073. Compositions corresponding to the present invention are characterized by increased stiffness (increased modulus of elasticity in bending) while demonstrating the presence of a valuable balance between the characteristics of impact resistance and optical properties and heat resistance even in the form that has not undergone nucleation from Example 1a.

Comparative Example 2c

For comparison purposes, Table 2 shows the final properties of the heterophasic propylene copolymer obtained from Basell under the trade name Moplen 2000 HEX. Moplen 2000HEX is a heterophasic copolymer formed by a crystalline propylene polymer matrix and an ethylene-propylene rubber component (EPA).

Comparative Example 3c

Table 2 also shows the final properties of the mixture, consisting of:

40% (mass.) Of a commercially available heterophasic propylene copolymer formed from approximately 25% of a crystalline propylene polymer matrix and approximately 75% of ethylene-propylene rubber components (EPA),

60% (w / w) of crystalline propylene homopolymer obtained from Basell under the trade name Moplen HP522H.

As shown in the example, heterophasic compositions obtained by mixing propylene polymers intended for the field of application of films and containing amounts of ethylene-propylene rubber components comparable to the amounts of ethylene-alpha-olefin rubber component (2) of the present invention do not demonstrate the presence of a valuable balance properties of the compositions of the invention.

Table 1
Polymerization process Example one 2 TEAL / solid catalyst component Mass ratio twenty 12 TEAL / ICPS Molar ratio 10 8 1st liquid phase reactor: propylene homopolymer matrix Polymerization temperature ºС 67 70 Pressure MPa 38 39 Stay time min 39 61 Feed H ₂ ppm (mol) 4150 910 MFR “L” g / 10 min 34 2 Xylene soluble fraction % (mass.) 1.4 1.7 The content of the component in the mixture % (mass.) 63 67 1st gas phase reactor - rubber ethylene-butene-1 copolymer Polymerization temperature ºС 85 85 Pressure bar twenty eighteen Stay time min 47 23 H ₂ / C ₂ ^- Molar ratio 0,309 0.258 C ₄ ^- / (C ₄ ^- + C ₂ ^- ) Molar ratio 0.607 0.503 The content of the component in the mixture % (mass.) 37 33 The butene-1 content in rubber % (mass.) 26 26

Xylene soluble fraction % (mass.) 23,4 22.9 Notes: supply of H ₂ = obtained when calculating the molar flow of propylene; C ₂ ^- = ethylene; C ₃ ^- = propylene; C ₄ ^- = butene-1.

table 2 Example and comparative example one 2 1s 2s 3s 1a 1b (pre-singing fetus-education) MFR “L” g / 10 min fifteen 16 3.3 19,4 eighteen 3 Xylene soluble fraction % (mass.) 23,4 22.9 22.6 - twenty H.V. xylene soluble fraction dl / g 1.41 1.23 1.09 - 1.9 Ethylene content % (mass.) 27.7 24.3 25,4 - 7 Butene Level 1 % (mass.) 9.6 8.5 8.0 - Flexural modulus MPa 816 995 775 760 997 730 Impact resistance in Izod test At 23ºС kJ / m ² 12,2 40,4 42,2 37.9 17.5 34 At 0ºС kJ / m ² 4.8 16.8 23,4 12.0 7.7 At -20ºС kJ / m ² 4.0 6.2 7.9 8.8 3,1 P / X transition temperature ºС <-50 <-50 -fifty -fifty <-50 Resistance to whitening: diameter (mm) of the whitening region due to the drop of the striker from a height 76 cm mm × 10 120 130 - - 190 30 cm mm × 10 90 90 - - 170 20 cm mm × 10 80 70 - - 140 10 cm mm × 10 fifty 60 - - 110 5 cm mm × 10 10 twenty - - 90 Shrinkage (longitudinal) % 0.67 0.61 - - 1.24 Shrinkage (transverse) % 0.80 0.90 - - 1.40 Turbidity for the plate (1 mm) % 48 60 28 23.7 > 90 53,2 Gloss for a plate (1 mm) at 60º % 95 92 106 - 52 91.8 Turbidity for a film cast from a solution (50 μm) % - - 8 - - 13 Gloss for the film cast from a solution (50 microns), at 45º % - - 62 - - 39.2 Oxygen transmission rate for a biaxially oriented film (30 μm thick) cube cm / m ² / day - - 4939 - - 3817

Claims (4)

1. Polyolefin composition for films, containing in mass percent, based on the weight of the sum of the components 1) and 2):
1) 55-80% propylene homopolymer;
2) 20-45% of a copolymer of ethylene and one or more C ₄ -C ₁₀ α-olefin (olefins) containing from 10 to 40% of the above C ₄ -C ₁₀ α-olefin (olefins);
wherein the said composition is characterized by the values of the melt flow rate STR (230 ° C, 2.16 kg) from 1 to 4 g / 10 min, the total ethylene content from 20 wt.% to 40 wt.%, the total level of C ₄ With ₁₀ α-olefin (olefins) from 6 wt.% To 15 wt.%, The ratio between the total level of ethylene content and the total level of C ₄ -C ₁₀ α-olefin (olefins) equal to 2.3 or more, the total level the content of the fraction soluble in xylene at room temperature, between 18 wt.% and 30 wt.%, and the modulus of elasticity in bending related to Songs reactor grade greater than 700 MPa;
where the specified polyolefin composition is obtained by conducting stepwise polymerization of at least two stages of stepwise polymerization, with each subsequent stage of polymerization is carried out in the presence of a polymer material obtained in the immediately preceding polymerization reaction. 2. The polyolefin composition according to claim 1, where the intrinsic viscosity of the fraction soluble in xylene at room temperature is from 1.1 to 1.7 dl / g. 3. The polyolefin composition according to claim 1, where the modulus of elasticity in bending is greater than 770 MPa. 4. The polyolefin composition according to claim 1, where the level of the copolymer of ethylene and one or more C ₄ -C ₁₀ α-olefin (olefins) is 25-45 wt.% Based on the weight of the total composition.