Patent Description:
Thermoplastic polyolefin compositions having low flexural modulus and shore hardness values have been used in many application fields, due to the valued properties which are typical of polyolefins, such as chemical inertia, mechanical properties and nontoxicity.

In particular, flexible polymer materials are widely used in extrusion coating, electrical wires and cables covering, as well as for packaging and in the medical field.

Mineral fillers, such as aluminum and magnesium hydroxides or calcium carbonate, are commonly used at high concentration levels in said polyolefin compositions for several reasons, for instance to impart self-extinguishing properties or to improve application-related physical properties, such as soft touch and printability.

The major disadvantage of these mineral fillers, in particular when used as flame retardants, is the very high loading needed. Depending on the class of fire-retardancy requested, up to <NUM>-<NUM>% by weight of filler can be necessary in order to reach adequate effectiveness in polyolefins. Normally, this has a highly negative influence on the processing of the polymer, with difficulties in adding and dispersing such high levels of filler, and on the physical-mechanical properties of compounds, namely providing lower elongation at break, lower tensile strength and higher brittleness.

<CIT> discloses a composition comprising <NUM> to 65wt% of a heterophasic polyolefin composition, <NUM> to 80wt% of an inorganic filler and <NUM> to 25wt% of a <NUM>-butene copolymer. According to <CIT>, such problem is addressed by combining <NUM> to <NUM>% by weight of a heterophasic polyolefin composition with <NUM> to <NUM>% by weight of an inorganic filler and <NUM> to <NUM>% by weight of an elastomeric polymer, which can be a heterophasic composition as well.

In the examples an amount of heterophasic composition of about <NUM>% by weight or higher is used, made of at least three heterophasic components with different intrinsic viscosities of the fraction soluble in xylene at <NUM> of the elastomeric component.

It has now been found that by combining specific butene-<NUM> copolymers and high amounts of mineral fillers with defined weight ratios between the two, it is possible to obtain a flexible polyolefin composition having an excellent and unusual set of properties, without requiring the addition of a heterophasic composition, which needs a multistage polymerization process for its preparation and adds complexity to the polymeric portion of the final composition, with consequent recycling issues.

If a heterophasic composition is used, it is added in low amounts and there is no need of having the previously said three components.

Moreover, the present polyolefin composition achieves an improved processability and better mechanical properties with respect to compositions wherein an ethylene or propylene plastomer is used instead of the butene-<NUM> copolymers.

The present disclosure provides for a polyolefin composition comprising:.

wherein the amounts of a) and b) refer to the total weight of a) + b) and the DSC second heating scan is carried out at a heating rate of <NUM> per minute.

Preferably the present polyolefin composition contains <NUM>% by weight or more, more preferably <NUM>% by weight or more of A) with respect to the total weight of the composition.

Most preferred amounts of A) are from <NUM>% to <NUM>% by weight, or from <NUM>% to <NUM>% by weight, with respect to the total weight of the polyolefin composition.

Most preferred amounts of B) are from <NUM>% to <NUM>% by weight, with respect to the total weight of the polyolefin composition.

Preferred values of MIE for the present polyolefin composition are of equal to or higher than <NUM>/<NUM>. , or equal to or higher than <NUM>/<NUM>. , in particular from <NUM> to <NUM>/<NUM>. , or from <NUM> to <NUM>/<NUM>. , or from <NUM> to <NUM>/<NUM>. , where MIE is the melt flow index at <NUM> with a load of <NUM>, determined according to ISO <NUM>-<NUM>:<NUM>.

Preferred values of Flexural Elastic Modulus for the said composition are equal to or lower than <NUM> MPa, more preferably equal to or lower than <NUM> MPa, the lower limit being preferably of <NUM> MPa, measured according to norm ISO <NUM>, <NUM> days after molding.

Preferred Shore D values for the said composition are equal to or or lower than <NUM>, in particular from <NUM> to <NUM>.

The tensile elongation at break for the said composition, measured according to ISO <NUM>, is preferably equal to or higher than <NUM>%, more preferably equal to or higher than <NUM>%, the upper limit being preferably of <NUM>%.

The butene-<NUM> copolymer component A) just after it has been melted and cooled does not show a melting peak at the second heating scan. However it is crystallizable, i.e. after about <NUM> days that it has been melted the polymer shows a measurable melting point and a melting enthalpy measured by Differential Scanning Calorimetry (DSC). In other words the butene-<NUM> copolymer shows no melting temperature attributable to polybutene-<NUM> crystallinity (TmII) DSC, measured after cancelling the thermal history of the sample, according to the DSC method described in the experimental section of the present application.

Moreover, the butene-<NUM> copolymer component A) can have at least one of the following additional features:.

The butene-<NUM> copolymer component A) can be obtained by polymerizing the monomer(s) in the presence of a metallocene catalyst system obtainable by contacting:.

Preferably the stereorigid metallocene compound belongs to the following formula (I):
<CHM>
wherein:.

Preferably the compounds of formula (I) have the general formula (Ia):
<CHM>
Wherein:.

Specific examples of metallocene compounds are dimethylsilanediyl{(<NUM>-(<NUM>,<NUM>,<NUM>-trimethylindenyl)-<NUM>-(<NUM>,<NUM>-dimethyl-cyclopenta[<NUM>,<NUM>-b:<NUM>,<NUM>-b']-dithiophene)} Zirconium dichloride and dimethylsilanediyl{(<NUM>-(<NUM>,<NUM>,<NUM>-trimethylindenyl)-<NUM>-(<NUM>,<NUM>-dimethyl-cyclopenta[<NUM>,<NUM>-b:<NUM>,<NUM>-b']-dithiophene) (Zirconium dimethyl.

Examples of alumoxanes are methylalumoxane (MAO), tetra-(isobutyl)alumoxane (TIBAO), tetra-(<NUM>,<NUM>,<NUM>-trimethyl-pentyl)alumoxane (TIOAO), tetra-(<NUM>,<NUM>-dimethylbutyl)alumoxane (TDMBAO) and tetra-(<NUM>,<NUM>,<NUM>-trimethylbutyl)alumoxane (TTMBAO).

Examples of compounds able to form an alkylmetallocene cation are compounds of formula D+E-, wherein D+ is a Brønsted acid, able to donate a proton and to react irreversibly with a substituent X of the metallocene of formula (I) and E- is a compatible anion, which is able to stabilize the active catalytic species originating from the reaction of the two compounds, and which is sufficiently labile to be able to be removed by an olefinic monomer. Preferably, the anion E- comprises of one or more boron atoms.

Examples of organo-aluminum compounds are trimethylaluminum (TMA), triisobutylaluminium (TIBAL), tris(<NUM>,<NUM>,<NUM>-trimethyl-pentyl)aluminum (TIOA), tris(<NUM>,<NUM>-dimethylbutyl)aluminium (TDMBA) and tris(<NUM>,<NUM>,<NUM>-trimethylbutyl)aluminum (TTMBA).

Examples of the said catalyst system and of polymerization processes employing such catalyst system can be found in <CIT> and <CIT>.

In general, the polymerization process for the preparation of the butene-<NUM> copolymer component A) can be carried out according to known techniques, for example slurry polymerization using as diluent a liquid inert hydrocarbon, or solution polymerization using for example the liquid butene-<NUM> as a reaction medium. Moreover, it may also be possible to carry out the polymerization process in the gas-phase, operating in one or more fluidized bed or mechanically agitated reactors. The polymerization carried out in the liquid butene-<NUM> as a reaction medium is preferred.

As a general rule, the polymerization temperature is generally of from - <NUM> to <NUM>, preferably from <NUM> to <NUM>, more preferably from <NUM> to <NUM>, most preferably from <NUM> to <NUM>.

The polymerization pressure is generally comprised between <NUM> bar and <NUM> bar. The polymerization can be carried out in one or more reactors that can work under same or different reaction conditions such as concentration of molecular weight regulator, comonomer concentration, temperature, pressure etc..

In applications where self-extinguishing properties are required, preferred flame-retardant inorganic fillers B) are hydroxides, hydrated oxides, salts or hydrated salts of metals, preferably of Ca, Al or Mg, such as, for example: magnesium hydroxide Mg(OH)<NUM>, aluminum hydroxide A1(OH)<NUM>, alumina trihydrate Al<NUM>O<NUM>. <NUM><NUM>O, magnesium carbonate hydrate, magnesium carbonate MgCO<NUM>, magnesium calcium carbonate hydrate, magnesium calcium carbonate, or mixtures thereof.

Mg(OH)<NUM>, Al(OH)<NUM>, Al<NUM>O<NUM>. <NUM><NUM>O and mixtures thereof are particularly preferred.

The metal hydroxides, in particular the magnesium and aluminium hydroxides, are preferably used in the form of particles with sizes which can range between <NUM> and <NUM>, preferably between <NUM> and <NUM>.

One inorganic filler which is particularly preferred is a precipitated magnesium hydroxide, having specific surface area of from <NUM> to <NUM><NUM>/g, preferably from <NUM> to <NUM><NUM>/g, an average particle diameter ranging from <NUM> to <NUM>, preferably from <NUM> to <NUM>.

The Precipitated magnesium hydroxide generally contains very low amounts of impurities deriving from salts, oxides and/or hydroxides of other metals, such as Fe, Mn, Ca, Si, V, etc. The amount and nature of such impurities depend on the origin of the starting material. The degree of purity is generally between <NUM> and <NUM>% by weight.

The filler can be advantageously used in the form of coated particles. Coating materials preferably used are saturated or unsaturated fatty acids containing from <NUM> to <NUM> carbon atoms, and metal salts thereof, such as, oleic acid, palmitic acid, stearic acid, isostearic acid, lauric acid, and magnesium or zinc stearate or oleate.

Other examples of inorganic oxides or salts are preferably CaO, TiO<NUM>, Sb<NUM>O<NUM>, ZnO, Fe<NUM>O<NUM>, CaCO<NUM>, BaSO<NUM> and mixtures thereof.

The polyolefin b) is preferably selected from the following polymers and polymer compositions.

The said C<NUM>-C<NUM> alpha-olefins are selected from olefins having formula CH<NUM>=CHR wherein R is an alkyl radical, linear or branched, or an aryl radical, having from <NUM> to <NUM> carbon atoms.

Specific examples of C<NUM>-C<NUM> alpha-olefins are butene-<NUM>, pentene-<NUM>, <NUM>-methylpentene-<NUM>, hexene-<NUM> and octene-<NUM>.

The preferred comonomers are ethylene, butene-<NUM> and hexene-<NUM>.

The propylene homopolymers <NUM>) are preferably crystalline homopolymers, having in particular a stereoregularity of isotactic type.

They preferably have a content of fraction soluble in xylene at <NUM> of <NUM>% by weight or less, in particular from <NUM>% to <NUM>% by weight or from <NUM>% to <NUM>% by weight, referred to the total weight of the propylene homopolymer.

The propylene copolymers <NUM>) are preferably crystalline, random copolymers , having in particular a stereoregularity of isotactic type.

They preferably have a content of fraction soluble in xylene at <NUM> of <NUM>% by weight or less, in particular from <NUM>% to <NUM>% by weight, referred to the total weight of the propylene copolymer.

Both the propylene homopolymers <NUM>) and the propylene copolymers <NUM>) have preferably MIL values of from <NUM> to <NUM>/<NUM>, more preferably from <NUM> to <NUM>/<NUM>. , where MIL is the melt flow index at <NUM> with a load of <NUM>, determined according to ISO <NUM>-<NUM>:<NUM>.

Both the said propylene homopolymers <NUM>) and the propylene copolymers <NUM>) are known in the art and commercially available.

Examples of commercially available homopolymers and copolymers of propylene are the polymer products sold by the LyondellBasell Industries with the trademark Moplen.

They can be prepared by using a Ziegler-Natta catalyst or a metallocene-based catalyst system in the polymerization process.

Typically a Ziegler-Natta catalyst comprises the product of the reaction of an organometallic compound of group <NUM>, <NUM> or <NUM> of the Periodic Table of elements with a transition metal compound of groups <NUM> to <NUM> of the Periodic Table of Elements (new notation). In particular, the transition metal compound can be selected among compounds of Ti, V, Zr, Cr and Hf and is preferably supported on MgCl<NUM>.

Particularly preferred catalysts comprise the product of the reaction of said organometallic compound of group <NUM>, <NUM> or <NUM> of the Periodic Table of elements, with a solid catalyst component comprising a Ti compound and an electron donor compound supported on MgCl<NUM>.

Preferred organometallic compounds are the aluminum alkyl compounds.

Thus preferred Ziegler-Natta catalysts are those comprising the product of reaction of:.

The solid catalyst component (<NUM>) contains as electron-donor a compound generally selected among the ethers, ketones, lactones, compounds containing N, P and/or S atoms, and mono- and dicarboxylic acid esters.

Catalysts having the above mentioned characteristics are well known in the patent literature; particularly advantageous are the catalysts described in <CIT> and <CIT>.

Particularly suited among the said electron-donor compounds are phthalic acid esters, preferably diisobutyl phthalate, and succinic acid esters.

Other electron-donors particularly suited are the <NUM>,<NUM>-diethers, as illustrated in published European patent applications <CIT>and<CIT>.

As cocatalysts (<NUM>), one preferably uses the trialkyl aluminum compounds, such as Al-triethyl, Al-triisobutyl and Al-tri-n-butyl.

The electron-donor compounds (<NUM>) that can be used as external electron-donors (added to the Al-alkyl compound) comprise the aromatic acid esters (such as alkylic benzoates), heterocyclic compounds (such as the <NUM>,<NUM>,<NUM>,<NUM>-tetramethylpiperidine and the <NUM>,<NUM>-diisopropylpiperidine), and in particular silicon compounds containing at least one Si-OR bond (where R is a hydrocarbon radical).

Examples of the said silicon compounds are those of formula R<NUM>aR<NUM>bSi(OR<NUM>)c, where a and b are integer numbers from <NUM> to <NUM>, c is an integer from <NUM> to <NUM> and the sum (a+b+c) is <NUM>; R<NUM>, R<NUM> and R<NUM> are alkyl, cycloalkyl or aryl radicals with <NUM>-<NUM> carbon atoms optionally containing heteroatoms.

Useful examples of silicon compounds are (tert-butyl)<NUM>Si(OCH<NUM>)<NUM>, (cyclohexyl)(methyl)Si (OCH<NUM>)<NUM>, (phenyl)<NUM>Si(OCH<NUM>)<NUM> and (cyclopentyl)<NUM>Si(OCH<NUM>)<NUM>.

The previously said <NUM>,<NUM>- diethers are also suitable to be used as external donors. In the case that the internal donor is one of the said <NUM>,<NUM>-diethers, the external donor can be omitted.

The catalysts may be precontacted with small quantities of olefin (prepolymerization), maintaining the catalyst in suspension in a hydrocarbon solvent, and polymerizing at temperatures from room to <NUM>, thus producing a quantity of polymer from <NUM> to <NUM> times the weight of the catalyst.

The operation can also take place in liquid monomer, producing, in this case, a quantity of polymer up to <NUM> times the weight of the catalyst.

The polymerization process, which can be continuous or batch, is carried out in the presence of said catalysts following known techniques and operating in liquid phase, in the presence or not of inert diluent, or in gas phase, or by mixed liquid-gas techniques.

Polymerization reaction time, pressure and temperature are not critical, however it is best if the temperature is from <NUM> to <NUM>. The pressure can be atmospheric or higher.

The regulation of the molecular weight, resulting into the said MIL values, is carried out by using known regulators, hydrogen in particular.

Preferred examples of metallocene-based catalyst systems are disclosed in <CIT> and <CIT>.

The polymerization conditions for preparing the homopolymers or copolymers of propylene with metallocene-based catalyst systems in general do not need to be different from those used with Ziegler-Natta catalysts.

Preferred examples of heterophasic polyolefin composition <NUM>) are compositions comprising:.

Particularly preferred examples of said heterophasic polyolefin composition are those containing from <NUM> to <NUM>% by weight of component i) and <NUM> to <NUM>% by weight of component ii), referred to the total weight of i) + ii).

The heterophasic composition preferably has a MIL ranging from <NUM> to <NUM>/<NUM> minutes, more preferably from <NUM> to <NUM>/<NUM> minutes.

The elongation at break of the heterophasic composition is preferably from <NUM>% to <NUM>%.

The flexural modulus of the heterophasic composition is preferably from500 to <NUM> MPa, more preferably from <NUM> to <NUM> MPa.

The copolymer or composition of copolymers (ii) has preferably a solubility in xylene at <NUM> of from <NUM>% to <NUM>% by weight, more preferably from <NUM>% to <NUM>% by weight, referred to the total weight of (ii).

Said heterophasic compositions are known in the art and commercially available.

Examples of commercially available heterophasic compositions are the polymer products sold by the LyondellBasell Industries with the trademark Moplen.

They can be prepared by blending components (i) and (ii) in the molten state, that is to say at temperatures greater than their softening or melting point, or more preferably by sequential polymerization in the presence of a highly stereospecific Ziegler-Natta catalyst as previously described.

Other catalysts that may be used are metallocene-type catalysts, as described in <CIT> and <CIT>; particularly advantageous are bridged bis-indenyl metallocenes, for instance as described in <CIT> and <CIT>. These metallocene catalysts may be used in particular to produce the component (ii). The above mentioned sequential polymerization process for the production of the heterophasic composition comprises at least two stages, where in one or more stage(s) propylene is polymerized, optionally in the presence of the said C<NUM>-C<NUM> alpha-olefin comonomer(s), to form component (i), and in one or more additional stage(s) mixtures of ethylene with propylene and/or a C<NUM>-C<NUM> alpha-olefin, and optionally diene, are polymerized to form component (ii).

The polymerization processes are carried out in liquid, gaseous, or liquid/gas phase. The reaction temperature in the various stages of polymerization can be equal or different, and generally ranges from <NUM> to <NUM>, preferably from <NUM> to <NUM> for the production of component (i), and from <NUM> to <NUM> for the production of component (ii). Examples of sequential polymerization processes are described in European patent applications <CIT> and <CIT>and in <CIT>.

In order to enhance the compatibility between the inorganic filler and the polymer components, a coupling agent c) may be added in the present polyolefin composition.

Said coupling agents may be made of or comprise saturated silane compounds or silane compounds containing at least one ethylenic unsaturation, epoxides containing an ethylenic unsaturation, organic titanates, mono-or dicarboxylic acids containing at least one ethylenic unsaturation, or derivatives thereof such as anhydrides or esters.

Preferred coupling agents c) are homopolymers and copolymers of alpha-olefins (for example butene-<NUM> homopolymers or copolymers of butene-<NUM> with an alpha-olefin, ethylene homopolymers or copolymers of ethylene with an alpha-olefin) containing polar groups, in particular carboxyl, hydroxyl, or ester groups.

Said coupling agents can be obtained by grafting mono-or dicarboxylic acids containing at least one ethylenic unsaturation, or derivatives thereof (for example, maleic acid, fumaric acid, citraconic acid, itaconic acid, acrylic acid, methacrylic acid and the anhydrides or esters derived therefrom, or mixtures thereof) on the said homopolymers and copolymers of alpha-olefins.

Homopolymers and copolymers of alpha-olefins grafted with maleic anhydride are particularly preferred.

Grafting can be obtained by means of a radical reaction (as described for instance in <CIT>).

The amount of coupling agent c) is preferably of <NUM>% to <NUM>% by weight, referred to the total weight of a) + b) +c).

The present polyolefin composition can be prepared by mixing the polymer components, the filler and the other optional components according to methods known in the state of the art. For instance, the components may be mixed in an internal mixer having tangential rotors (such as Banbury mixers) or having interpenetrating rotors, or alternatively in continuous mixers (such as Buss mixers) or co- rotating or counter-rotating twin-screw extruders.

Mixing or extrusion temperatures generally applied are from <NUM> to <NUM>.

In fields where self-extinguishing properties are required, the present polyolefin composition may be used in applications such as electrical wires and cables covering, for instance as inner filling for industrial cables, reinforced and non- reinforced roofing membranes and adhesive tapes.

Where flame-retardancy is not requested, the present polyolefin composition may be advantageously used in non flame-retardant soft membranes, coupled or non-coupled with a reinforcement (e. in publicity banners, liners, tarpaulin, sport-wear and safety clothing) and as synthetic leather.

Moreover, the present polyolefin composition may be used in packaging and extrusion coating.

Conventional additives commonly used in the state of the art may be added to the present polyolefin composition.

Depending on the properties needed for the different applications, the present polyolefin composition may be used in combination with elastomeric polymers such as ethylene/propylene copolymers (EPR), ethylene/propylene/diene terpolymers (EPDM), copolymers of ethylene with C<NUM>-CI2 alpha-olefins (e. ethylene/octene-<NUM> copolymers, such as the ones commercialized under the name Engage) and mixtures thereof.

Conventional additives such as processing aids, lubricants, nucleating agents, extension oils, organic and inorganic pigments, anti-oxidants and UV-protectors, commonly used in olefin polymers, may be added.

Processing aids usually added to the polymer material are, for example, calcium stearate, zinc stearate, stearic acid, paraffin wax, synthetic oil and silicone rubbers.

Examples of suitable antioxidants are pentaerythritol tetrakis(<NUM>-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl)propionate and <NUM>,<NUM>-bis(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyhydrocinnamoyl)hydrazine.

Other fillers which can be used are, for example, glass particles, glass fibers, calcinated kaolin and talc.

The practice and advantages of the various embodiments, compositions and methods as provided herein are disclosed below in the following examples. These Examples are illustrative only, and are not intended to limit the scope of the invention in any manner whatsoever.

The following analytical methods are used to characterize the polymer compositions.

Determined by Differential Scanning Calorimetry (DSC) on a Perkin Elmer DSC-<NUM> instrument.

The melting temperature (TmII) of the butene-<NUM> copolymer A) was determined according to the following method:.

The butene-<NUM> copolymer component A) of the present polyolefin composition does not have a TmII peak.

Determined according to norm ISO <NUM>-<NUM>:<NUM> with a load of <NUM> at <NUM>.

According to norm ISO <NUM>:<NUM>, measured <NUM> days after molding.

Determined at <NUM> via DMTA analysis according to ISO <NUM>-<NUM>:<NUM> on <NUM> thick compression molded plaque.

According to norm ISO <NUM>-<NUM>:<NUM> on compression molded plaques, measured <NUM> days after molding.

Determined according to norm ASTM D <NUM>-<NUM> in tetrahydronaphthalene at <NUM>.

Determined according to norm ISO <NUM>-<NUM>:<NUM> at <NUM>.

Determined by IR spectroscopy or by NMR.

Particularly for the butene-<NUM> copolymers the amount of comonomer is calculated from the <NUM>C-NMR spectra of the copolymers. Measurements were performed on a polymer solution (<NUM>-<NUM> wt%) in dideuterated <NUM>,<NUM>,<NUM>,<NUM>-tetrachloro-ethane at <NUM>. The <NUM>C NMR spectra were acquired on a Bruker AV-<NUM> spectrometer operating at <NUM> in the Fourier transform mode at <NUM> using a <NUM>° pulse, <NUM> seconds of delay between pulses and CPD (WALTZ16) to remove <NUM>H-<NUM>C coupling. About <NUM> transients were stored in <NUM> data points using a spectral window of <NUM> ppm (<NUM>-<NUM> ppm).

Diad distribution is calculated from <NUM>C NMR spectra using the following relations:.

I<NUM>, I<NUM>, I<NUM>, <NUM><NUM>, I<NUM>, I<NUM>, I<NUM>, I<NUM>, I<NUM>, I<NUM>, I<NUM> are integrals of the peaks in the <NUM>C NMR spectrum (peak of EEE sequence at <NUM> ppm as reference). The assignments of these peaks are made according to<NPL>),<NPL>), and<NPL>). They are collected in Table A (nomenclature according to <NPL>)).

For the propylene copolymers the comonomer content is determined by infrared spectroscopy by collecting the IR spectrum of the sample vs. an air background with a Fourier Transform Infrared spectrometer (FTIR). The instrument data acquisition parameters are:.

Using a hydraulic press, a thick sheet is obtained by pressing about g <NUM> of sample between two aluminum foils. If homogeneity is in question, a minimum of two pressing operations are recommended. A small portion is cut from this sheet to mold a film. Recommended film thickness ranges between <NUM>-:<NUM> (<NUM> - <NUM> mils).

Pressing temperature is <NUM>±<NUM> (<NUM>°F) and about <NUM>/cm<NUM> (<NUM> PSI) pressure for about one minute. Then the pressure is released and the sample is removed from the press and cooled the room temperature.

The spectrum of a pressed film of the polymer is recorded in absorbance vs. wavenumbers (cm-<NUM>). The following measurements are used to calculate ethylene and butene-<NUM> content:.

In order to calculate the ethylene and butene-1content, calibration straight lines for ethylene and butene-<NUM> obtained by using samples of known amount of ethylene and butene-<NUM> are needed.

The determination of the means Mn and Mw, and Mw/Mn derived therefrom was carried out using a Waters GPCV <NUM> apparatus, which was equipped with a column set of four PLgel Olexis mixed-gel (Polymer Laboratories) and an IR4 infrared detector (PolymerChar). The dimensions of the columns were <NUM> × <NUM> and their particle size <NUM> µm. The mobile phase used was <NUM>-<NUM>-<NUM>-trichlorobenzene (TCB) and its flow rate was kept at <NUM>/min. All the measurements were carried out at <NUM>. Solution concentrations were <NUM>/dl in TCB and <NUM>/l of <NUM>,<NUM>-diterbuthyl-p-chresole were added to prevent degradation. For GPC calculation, a universal calibration curve was obtained using <NUM> polystyrene (PS) standard samples supplied by Polymer Laboratories (peak molecular weights ranging from <NUM> to <NUM>). A third order polynomial fit was used for interpolating the experimental data and obtaining the relevant calibration curve. Data acquisition and processing was done using Empower (Waters). The Mark-Houwink relationship was used to determine the molecular weight distribution and the relevant average molecular weights: the K values were KPS = <NUM> × <NUM>-<NUM> dL/g and KPB = <NUM> × <NUM>-<NUM> dL/g for PS and PB respectively, while the Mark-Houwink exponents α = <NUM> for PS and α = <NUM> for PB were used.

For butene-<NUM>/ethylene copolymers, as far as the data evaluation is concerned, it is assumed that the composition is constant in the whole range of molecular weight and the K value of the Mark-Houwink relationship is calculated using a linear combination as reported below: <MAT> where KEB is the constant of the copolymer, KPE (<NUM> × <NUM>-<NUM>, dL/g) and KPB (<NUM> × <NUM>-<NUM> dl/g) are the constants of polyethylene and polybutene and xE and xB are the ethylene and the butene-<NUM> weight% content. The Mark-Houwink exponents α = <NUM> is used for all the butene-<NUM>/ethylene copolymers independently of their composition.

<NUM> of the polymer sample are dissolved in <NUM> of xylene at <NUM> under agitation. After <NUM> minutes the solution is allowed to cool to <NUM>, still under agitation, and then placed in a water and ice bath to cool down to <NUM>. Then, the solution is allowed to settle for <NUM> hour in the water and ice bath. The precipitate is filtered with filter paper. During the filtering, the flask is left in the water and ice bath so as to keep the flask inner temperature as near to <NUM> as possible. Once the filtering is finished, the filtrate temperature is balanced at <NUM>, dipping the volumetric flask in a water-flowing bath for about <NUM> minutes and then, divided in two <NUM> aliquots. The solution aliquots are evaporated in nitrogen flow, and the residue dried under vacuum at <NUM>° C until constant weight is reached. The weight difference in between the two residues must be lower than <NUM>%; otherwise the test has to be repeated. Thus, one calculates the percent by weight of polymer soluble (Xylene Solubles at <NUM> = XS <NUM>) from the average weight of the residues. The insoluble fraction in o-xylene at <NUM> (xylene Insolubles at <NUM> = XI%<NUM>) is: <MAT>.

<NUM> of polymer are dissolved in <NUM> of xylene at <NUM>° C under agitation. After <NUM> minutes the solution is allowed to cool to <NUM>° C, still under agitation, and then allowed to settle for <NUM> minutes. The precipitate is filtered with filter paper, the solution evaporated in nitrogen flow, and the residue dried under vacuum at <NUM>° C until constant weight is reached. Thus, one calculates the percent by weight of polymer soluble (Xylene Solubles - XS) and insoluble at room temperature (<NUM>° C).

The percent by weight of polymer insoluble in xylene at room temperature (<NUM>) is considered the isotactic index of the polymer. This value corresponds substantially to the isotactic index determined by extraction with boiling n-heptane, which by definition constitutes the isotactic index of polypropylene polymers.

<NUM> of each sample were dissolved in <NUM> of C<NUM>D<NUM>Cl<NUM>.

The <NUM>C NMR spectra were acquired on a Bruker DPX-<NUM> (<NUM>, <NUM>° pulse, <NUM> delay between pulses). About <NUM> transients were stored for each spectrum; the mmmm pentad peak (<NUM> ppm) was used as the reference.

The microstructure analysis was carried out as described in the literature (<NPL> et al. and <NPL>et al.

The percentage value of pentad tacticity (mmmm%) for butene-<NUM> copolymers is the percentage of stereoregular pentads (isotactic pentad) as calculated from the relevant pentad signals (peak areas) in the NMR region of branched methylene carbons (around <NUM> ppm assigned to the BBBBB isotactic sequence), with due consideration of the superposition between stereoirregular pentads and of those signals, falling in the same region, due to the comonomer.

The X-ray crystallinity was measured with an X-ray Diffraction Powder Diffractometer using the Cu-Kα1 radiation with fixed slits and collecting spectra between diffraction angle 2Θ = <NUM>° and 2Θ = <NUM>° with step of <NUM>° every <NUM> seconds.

Measurements were performed on compression molded specimens in the form of disks of about <NUM>-<NUM> of thickness and <NUM>-<NUM> of diameter. These specimens are obtained in a compression molding press at a temperature of <NUM> ± <NUM> without any appreciable applied pressure for <NUM> minutes, then applying a pressure of about <NUM>/cm<NUM> for about few second and repeating this last operation <NUM> times.

The diffraction pattern was used to derive all the components necessary for the degree of crystallinity by defining a suitable linear baseline for the whole spectrum and calculating the total area (Ta), expressed in counts/sec·2Θ, between the spectrum profile and the baseline. Then a suitable amorphous profile was defined, along the whole spectrum, that separate, according to the two phase model, the amorphous regions from the crystalline ones. Thus it is possible to calculate the amorphous area (Aa), expressed in counts/sec·2Θ, as the area between the amorphous profile and the baseline; and the crystalline area (Ca), expressed in counts/sec·2Θ, as Ca = Ta- Aa.

The degree of crystallinity of the sample was then calculated according to the formula: <MAT>.

The said materials are melt-blended in a co-rotating twin screw extruder Leistritz Micro <NUM>, with screw diameter of <NUM> and screw length/diameter ratio of <NUM>/D, under the following conditions:.

The amounts of the components and the properties of the so obtained final compositions are reported in Table <NUM>.

Claim 1:
A polyolefin composition comprising:
a) from <NUM>% to <NUM>% by weight, preferably from <NUM>% to <NUM>% by weight, of a composition comprising:
A) a copolymer of butene-<NUM> with ethylene having a copolymerized ethylene content of up to <NUM>% by mole and no melting peak detectable at the DSC at the second heating scan; and
B) an inorganic filler, preferably selected from flame-retardant inorganic fillers;
the B)/A) weight ratio being from <NUM> to <NUM>, preferably from <NUM> to <NUM>, more preferably from <NUM> to <NUM>, in particular from <NUM> to <NUM>;
b) from <NUM>% to <NUM>% by weight, preferably from <NUM> % to <NUM>% by weight, of an additional polyolefin different from A);
wherein the amounts of a) and b) refer to the total weight of a) + b) and the DSC second heating scan is carried out at a heating rate of <NUM> per minute.