Patent Description:
The underside of carpets generally comprises several layers having the function of securing the tufts and of giving the carpet additional strength and dimensional stability. Most carpets have a double backing: the primary backing where the yarn is fixed, and a secondary backing which provides the required dimensional stability. The primary and secondary baking are glued by latex, emulsions of synthetic rubbers or hot melt adhesive compositions.

Highly flowable compositions containing ex-reactor butene-<NUM> copolymers having MFR in the range from <NUM> to <NUM>,<NUM>/<NUM> are known from the International patent application <CIT>. Said compositions are suitable for gluing the tuft to the primary carpet backing in tufted or needle-punched carpets.

The carpet secondary backing can be made from different materials, such as compositions comprising bitumen and inorganic filler as described in the <CIT>. Said carpets have limited recyclability at the end of their service life due to difficult delamination of the bitumen-containing layer.

It is also known in the art, in particular from the <CIT>, that butene-<NUM> polymer compositions containing butene-<NUM> polymers having melt flow rate values up to <NUM>/<NUM>. , a large amount of filler and hydrocarbon oils can be used as backing materials of carpets to substitute bitumen-based compositions. However, the presence of hydrocarbon oils in the composition may compromise the elasticity of the backing layer and oil blooming may alter the aesthetic appearance of the carpet.

In this context, it is still felt the need of polyolefin-based compositions with sufficiently high fluidity and good elastic properties at room temperature, which can be used in carpet backing.

The Applicant has now found a polyolefin composition having high melt flow rate and good elastic properties.

The filled polyolefin composition of the present disclosure comprises:.

wherein the amounts of (A) and (B) are referred to the total weight of (A) + (B).

The polyolefin composition of the instant disclosure are also endowed with a good balance between crystallinity, viscosity and adhesive properties.

The present disclosure refers also to a method of manufacturing a carpet comprising a step of applying to the underside of a primary carpet backing at least one layer comprising the polyolefin composition as described above.

In a further aspect, the present disclosure refers also to a carpet comprising at least one backing layer comprising the polyolefin composition as described above.

The claimed subject matter may be understood by reference to the following description taken in conjunction with the accompanying figures in which:.

In the context of the present disclosure, the term "room temperature" indicates a temperature of <NUM>±<NUM> measured at <NUM>% of relative humidity.

An object of the present disclosure is a filled polyolefin composition comprising:.

wherein the amounts of (A) and (B) are referred to the total weight of (A) + (B), the total weight of (A)+(B) amounting to <NUM>%.

In one embodiment, the butene-<NUM> copolymer component (A) may have a MFR measured according to ISO <NUM> (<NUM>, <NUM>) of from <NUM> to <NUM>,<NUM>/<NUM>, preferably of from <NUM> to <NUM>,<NUM>/<NUM>.

In one embodiment, the butene-<NUM> copolymer component (A) may have a MFR measured according to ISO <NUM> (<NUM>, <NUM>) of from <NUM>,<NUM> to <NUM>,<NUM>/lOmin.

The at least one comonomer is selected from ethylene, propylene, C5-C10 alpha-olefins and mixtures thereof.

Preferably said at least one comonomer can be selected from among ethylene, propylene, hexene-<NUM>, octene-<NUM> and mixture thereof.

More preferably the at least one comonomer can be ethylene.

In one embodiment, the butene-<NUM> copolymer component (A) may have a copolymerized comonomer content, in particular a copolymerized ethylene content, of <NUM>-<NUM> wt. %, preferably of <NUM>-<NUM> wt. %, more preferably of <NUM>-<NUM> wt.

In one further embodiment, the butene-<NUM> component (A) may be a butene-<NUM> copolymer composition comprising:.

The relative amount of component (A1) and (A2) may range from <NUM>% to <NUM>% by weight, in particular from <NUM>% to <NUM>% by weight of (A1) and from <NUM>% to <NUM>% by weight, in particular from <NUM>% to <NUM>% by weight of (A2), said amounts being referred to the sum of (A1)+(A2).

Examples of said butene-<NUM> copolymer composition are described in the patent application <CIT>,.

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

In one embodiment, the butene-<NUM> copolymer (A) may have all the additional features (a)-(f).

Preferably, the butene-<NUM> copolymer component (A) may also have at least one of the following additional features:.

wherein the glass transition temperature and the storage modulus are measured by Dynamic Mechanical Thermal Analysis (DMTA).

More preferably, the butene-<NUM> copolymer component (A) may have both the additional feature (g) and (h).

Optionally, the butene-<NUM> copolymer component (A) may additionally have at least one of the further following features:.

In one embodiment, the butene-<NUM> copolymer (A) may have both the additional features (i) and (ii).

In a further embodiment, the butene-<NUM> copolymer (A) may have all the additional features (a)-(h) and also all the additional features (i) and (ii).

The butene-<NUM> copolymer component (A) can be obtained by copolymerizing butene-<NUM> and the at least one comonomer in the presence of a catalyst system obtainable by contacting:.

The patent applications <CIT>, <CIT> and <CIT>, describe a process and a catalysts system suitable for producing the butene-<NUM> copolymer component (A).

The butene-<NUM> copolymer component (A) can be obtained by a polymerization process carried out in one or more reactors connected in series. In the latter case, the catalyst can be added in the first reactor only, or in more than one reactor. As explained in <CIT>, the polymerization process can be carried out in the liquid phase, optionally in the presence of an inert hydrocarbon solvent, or in the gas phase, using fluidized bed or mechanically agitated gas phase reactors. Preferably, the polymerization process is carried out by using liquid butene-<NUM> as polymerization medium. The polymerization temperature ranges from <NUM> to <NUM>, preferably from <NUM> to <NUM>, more preferably it is from <NUM> to <NUM>.

As explained in <CIT>, hydrogen can be advantageously used to regulate the molecular weight of butene-<NUM> copolymers. The concentration of hydrogen during the polymerization reaction carried out in the liquid phase is higher than <NUM> molar ppm and lower than <NUM> molar ppm, preferably it ranges from <NUM> molar ppm to <NUM> molar ppm.

Butene-<NUM> copolymers having low melting point can be obtained by properly selecting the copolymerized comonomer content, in particular ethylene content. Thus, the butene-<NUM> copolymer component (A) can be obtained with a polymerization process wherein the (total) amount of the comonomer, in particular of ethylene, in the liquid phase ranges from <NUM>. %, preferably from <NUM> wt. % to <NUM> wt. %, with respect to the total weight of butene-<NUM> monomer present in the polymerization reactor.

When the butene-<NUM> copolymer (A) is a butene-<NUM> copolymer composition comprising the component (A1) and (A2) as described above, the polymerization process comprises at least two polymerization stages, carried out in two or more reactors connected in series. When component (A1) is a copolymer, for the preparation of component (A1) the amount of comonomer in the liquid phase can be from <NUM> wt. % to <NUM> wt. %, while it can be from <NUM> wt. % to <NUM> wt. % for the preparation of component (A2).

In one embodiment, the at least one inorganic filler (B) can be selected from the group consisting of carbonates of alkali metals or alkaline-earth metals, sulfates of alkali metals or alkaline-earth metals, hydroxides of alkali metals or alkaline-earth metals, silicate minerals, synthetic silica, synthetic zeolites, glass, carbon black, inorganic pigments, and mixtures thereof.

The carbonates, sulfates and/or hydroxides of alkali metals and of alkaline-earth metals can be of natural or synthetic origin.

In a preferred embodiment, the at least one inorganic filler (B) can be selected from the group consisting of calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate, magnesium hydroxides and mixtures thereof.

More preferably, the at least one inorganic filler (B) can be calcium carbonate.

In one embodiment, the at least one inorganic filler (B) can have a particle size distribution in which the d(<NUM>) value is equal to or lower than <NUM>.

Preferably, the inorganic filler (B) can have a particle size distribution in which the d(<NUM>) value is from <NUM> to <NUM>, in particular from <NUM> to <NUM>, the d(<NUM>) value is from <NUM> to <NUM> and d(<NUM>) value is from <NUM> to <NUM>.

In one embodiment, the at least one inorganic filler (B) may be calcium carbonate having a particle size distribution ad described above.

In one embodiment, the filled polyolefin composition may comprise from <NUM> to <NUM> wt. %, preferably from <NUM> to <NUM> wt. %, of at the least one inorganic filler (B). In this embodiment, the filled polyolefin composition may comprise from <NUM> to <NUM> wt. %, preferably from <NUM> to <NUM> wt. % of the butene-<NUM> copolymer (A). The composition of this embodiment is particularly, but not exclusively, suitable for forming the secondary backing of carpets.

In addition to the above-mentioned components (A) and (B), the filled polyolefin composition of the present disclosure can further optionally comprise additives selected from antioxidants, UV stabilizers, aging protection agents, nucleating agents and mixtures thereof. Preferably, the total amount of the additives may be from <NUM> to <NUM> wt. %, with respect to the total weight of the filled polyolefin composition.

The filled polyolefin composition of the present disclosure may be further characterized in that it does not comprise hydrocarbon oils.

The filled polyolefin composition of the present disclosure can be prepared by known methods and equipment, such as blending of the component in the molten state in a single- or twin screw extruder. The inorganic component (B) can be added to the butene-<NUM> copolymer in powder form or, preferably, as a masterbatch.

Accordingly, the filled polyolefin composition of the present disclosure may comprise the component (A) and a masterbatch composition comprising the at least one inorganic filler (B), wherein the amount of the masterbatch composition in the filled polyolefin composition secures the presence of up to <NUM> wt. % of the inorganic filler (B) in the filled polyolefin composition.

The filled polyolefin composition described above is particularly suitable for the use in carpet backing.

The butene-<NUM> copolymer (A) is endowed with good elastic properties at room temperature, resulting in a carpet backing having good resistance to high mechanical loads.

Accordingly, a further object of the present disclosure is a method of manufacturing a carpet comprising a step of applying to the underside of a primary carpet backing at least one layer comprising the filled polyolefin composition as described above.

The method may be preferably for the manufacturing of a carpet selected from the group consisting of tufted, needle-punched, woven, knotted and bonded carpets, preferably for the manufacturing of a tufted carpet.

The carpets described above comprise a primary backing, where the face yarn is fixed, a backcoat material adhered to, or coated onto, the primary backing which binds, or anchors, the yarn to the primary backing and optionally, but preferably, at least one secondary backing adhered to the backcoat material, which provides dimensional stability to the carpet. A carpet comprising a plurality of secondary backings further comprise adhesive layers to adhere the secondary layers.

The carpet, preferably but not exclusively tufted carpet, may have a unitary backing, which is a heavy application of a backcoat material applied to the carpet's primary backing both to fix the yarns and provide dimensional stability, without using a secondary backing.

The filled polyolefin composition of the present disclosure can be comprised in at least one layer selected between the backcoat material and the at least one secondary backing.

The step of applying the to the underside of a primary carpet backing at least one layer comprising the filled polyolefin composition can be carried out using conventional application techniques, such as extrusion coating, roller coating or lamination, depending on the thickness and viscosity of the layer comprising the filled polyolefin composition.

A further object of the present disclosure is a carpet comprising at least one backing layer comprising the filled polyolefin composition as described above.

The carpet may preferably be selected from the group consisting of tufted, needle-punched, woven, knitted and bonded carpets, preferably it may be a tufted carpet.

In one embodiment the carpet may be a tufted carpet tile.

The carpet of the present disclosure may be further characterized in that it does not comprise bitumen.

In one embodiment, the at least one backing layer has thickness ranging from <NUM> to <NUM>, preferably from <NUM> to <NUM>.

In one preferred embodiment, the carpet may comprise:.

wherein at least one selected among the backcoat material (ii) and the one or more secondary backings (iii) comprises the filled polyolefin composition as described above.

The primary backing (i) comprises a yarn protruding from the front side of the primary backing and may be made, or comprise, a woven or non-woven fabric comprising natural or synthetic fibers selected among jute, wool, rayon, polyamides, polyesters, propylene polymers, ethylene polymers and mixtures thereof.

Alternatively, the primary backing (i) may be a film comprising a polymer material selected from the group consisting of propylene polymers, ethylene polymers and mixtures thereof.

The backcoat material (ii) may comprise the filled polyolefin composition of the present disclosure. In this embodiment, the filled polyolefin composition assists in binding the yarn to the primary backing (i) and also provides stiffness to the carpet.

The layer comprising the backcoat material (ii) comprising the filled polyolefin composition may have thickness ranging from <NUM> to <NUM>, preferably from <NUM> to <NUM>.

Alternatively, the backcoat material (ii) may comprise an adhesive material selected among latex, natural or synthetic rubber, eg. styrene-butadiene rubber, hot melt adhesives, the butene-<NUM> copolymer component (A) of the filled polyolefin composition of the present disclosure and mixtures thereof.

In one preferred embodiment, the backcoat material (ii) may comprise latex.

One or more of the secondary backing layers (iii) may comprise materials used in the art in carpet secondary backing, such as: woven or non-woven fabrics comprising natural fibers selected among jute, wool, rayon and mixtures thereof; woven or non-woven fabrics comprising synthetic fibers selected among polyamides, polyesters, propylene polymers, ethylene polymers and mixtures thereof; films or foams comprising olefin polymers, preferably propylene polymers, ethylene polymers, polyurethane, latex and mixtures thereof.

One or more of the secondary backing layers (iii) may comprise the filled polyolefin composition of the present disclosure.

In a first embodiment, the carpet may comprise:.

wherein at least one of the secondary backing layers (iii) comprises the filled polyolefin composition as described above.

In a further embodiment, the carpet may comprise:.

The carpet of this further embodiment is a carpet having a unitary backing.

The carpet of the present disclosure is endowed with a favorable balance of properties: the backcoat material (ii), and optionally the one or more secondary backing layers (iii), are strongly fixed to the primary backing, so that no delamination problems arises during the service life of the carpet. At the same time said layers delaminate easily enough from the primary backing (i), thereby improving the recyclability of the carpet at the end of its service life, if compared to carpets comprising bituminous secondary backings.

The carpet of the present disclosure is also endowed with high resistance to load, excellent dimensional stability and good adhesion to the floor, preventing wrinkling and/or buckling during the service life of the carpet.

The following 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 determine the properties reported in the description and in the examples.

Melt flow rate (MFR) was measured according to ISO <NUM>-<NUM>:<NUM> (<NUM>, <NUM>, except where different load and temperatures are specified).

Comonomer content (wt. %) measured via IR spectroscopy.

The spectrum of a pressed film of the polymer was recorded in absorbance vs. wavenumbers (cm-<NUM>). The following measurements were used to calculate the ethylene content: a) area (At) of the combination absorption bands between <NUM> and <NUM>-<NUM> which is used for spectrometric normalization of film thickness;.

A Fourier Transform Infrared spectrometer (FTIR) was used, which is capable of providing the spectroscopic measurements above reported. A hydraulic press with platens heatable to <NUM> (Carver or equivalent) was used.

A calibration straight line is obtained by plotting %(BEB + BEE)wt vs. FCRC2/At. The slope Gr and the intercept Lr are calculated from a linear regression.

A calibration straight line is obtained by plotting %(EEE)wt vs. AC2,block/At. The slope GH and the intercept IH are calculated from a linear regression.

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>. The pressing temperature is <NUM> ± <NUM>. A crystalline phase modification takes place with time, therefore it is recommended to collect the IR spectrum of the sample film as soon as it is molded.

The instrument data acquisition parameters are as follows:.

Calculate the concentration by weight of the BEE + BEB sequences of ethylene units: <MAT>.

Calculate the residual area (AC2,block) after the subtraction described above, using a baseline between the shoulders of the residual band.

Calculate the concentration by weight of the EEE sequences of ethylene units: <MAT>.

Calculate the total amount of ethylene percent by weight: <MAT>.

Mw/Mn determination. Measured by way of Gel Permeation Chromatography (GPC) in <NUM>,<NUM>,<NUM>-trichlorobenzene (TCB). Molecular weight parameters (Mn, Mw, Mz) and molecular weight distributions Mw/Mn for all the samples were measured by using a GPC-IR apparatus by PolymerChar, which was equipped with a column set of four PLgel Olexis mixed-bed (Polymer Laboratories) and an IR5 infrared detector (PolymerChar). The dimensions of the columns were <NUM> × <NUM> and their particle size was <NUM>. The mobile phase flow rate was kept at <NUM>/min. All the measurements were carried out at <NUM>. Solution concentrations were <NUM>/mL (at <NUM>) 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 PolymerChar (peak molecular weights ranging from <NUM> to <NUM>). A third-order polynomial fit was used for interpolate the experimental data and obtain the relevant calibration curve. Data acquisition and processing was done by using Empower <NUM> (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 polybutene (PB) respectively, while the Mark-Houwink exponents α = <NUM> for PS and α = <NUM> for PB were used.

For butene/ethylene copolymers, as far as the data evaluation is concerned, it was assumed for each sample that the composition was constant in the whole range of molecular weight and the K value of the Mark-Houwink relationship was calculated using a linear combination as reported below: KEB = xEKPE + xBKPB
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 (PE) and PB, xE and xB are the ethylene and the butene weight relative amount with xE + xB = <NUM>. The Mark-Houwink exponents α = <NUM> was used for all the butene/ethylene copolymers independently on their composition. End processing data treatment was fixed for all samples to include fractions up at <NUM> in terms of molecular weight equivalent. Fractions below <NUM> were investigated via GC.

The melting point was determined by Differential Scanning Calorimetry (D. ) on a Perkin Elmer DSC-<NUM> instrument. The melting temperatures of butene-<NUM> copolymers and of the HMA compositions were determined according to the following method:.

Glass transition temperature (Tg) and Storage Modulus (E') via Dynamic Mechanical Thermal Analysis (DMTA). Molded specimens (conditioned after molding for <NUM> at <NUM>°±<NUM> and <NUM>% relative humidity) of <NUM> by <NUM> by <NUM> are fixed to the DMTA machine for tensile stress. The frequency of the tension and relies of the sample is fixed at <NUM>. The DMTA translates the elastic response of the specimen starting from -<NUM> to <NUM>, using a heating rate of <NUM>/min. In this way it is possible to plot the elastic response versus temperature. The elastic modulus for a viscoelastic material is defined as E=E'+iE". The DMTA can split the two components E' and E" by their resonance and plot E' vs temperature and E/E" = tan (δ) vs temperature. The glass transition temperature Tg is assumed to be the temperature at the maximum of the curve E/E" = tan (δ) vs temperature.

Rotational (Brookfield) viscosity is measured at <NUM> and a deformation rate of and <NUM>-<NUM>, using a RheolabQC instrument, which is a rotational rheometer, consisting of a high-precision encoder and a dynamic EC motor. It is possible to select between controlled shear rate (CR) and controlled shear stress (CS) test settings. It is suitable for investigations on the mixing and stirring behavior of emulsions and dispersions and pastes using concentric cylinder systems, double gap systems and different vane geometries and spindles. During the test, the sample is subjected at a deformation rate sweep from <NUM>-<NUM> to <NUM>-<NUM>. The torque is measured for each deformation rate and the corresponding viscosity is calculated by the instrument software.

Crystallinity was measured by X-Ray diffraction according to the following method: The instrument used to measure crystallinity is a X-ray Diffraction Powder Diffractometer (XDPD) that uses the Cu-Kα1 radiation with fixed slits and able to collect spectra between diffraction angle 2Θ = <NUM>° and 2Θ = <NUM>° with step of <NUM>° every <NUM> seconds.

The samples are diskettes of about <NUM>-<NUM> of thickness and <NUM>-<NUM> of diameter made by compression molding. The diskettes are aged at <NUM> for <NUM> hours.

After this preparation the specimen is inserted in the XDPD sample holder. Set the XRPD instrument in order to collect the XRPD spectrum of the sample from diffraction angle 2Θ = <NUM>° to 2Θ = <NUM>° with step of <NUM>° by using counting time of <NUM> seconds, at the end the final spectrum is collected.

Defining Ta as the total area between the spectrum profile and the baseline expressed in counts/sec·2Θ. ; and Aa as the total amorphous area expressed in counts/sec·2Θ. Ca is total crystalline area expressed in counts/sec·2Θ.

The spectrum or diffraction pattern is analyzed in the following steps:.

Intrinsic viscosity: determined in tetrahydronaphthalene at <NUM> according to norm ASTM D <NUM> - <NUM>.

Density: Determined according to norm ISO <NUM>-<NUM>:<NUM>, method A, Part <NUM>: immersion method. Test specimens were obtained by compression moulded plaques. Density is measured after <NUM> days conditioning.

Fractions soluble and insoluble in xylene at <NUM>: <NUM> of polymer composition and <NUM><NUM> of o-xylene are introduced in a glass flask equipped with a refrigerator and a magnetic stirrer. The temperature is raised in <NUM> minutes up to the boiling point of the solvent. The so obtained clear solution is then kept under reflux and stirring for further <NUM> minutes. The closed flask is then cooled to <NUM> in air for <NUM> to <NUM> minute under stirring and then kept for <NUM> minutes in thermostatic water bath at <NUM> for <NUM> minutes as well. The so formed solid is filtered on quick filtering paper at <NUM>. <NUM><NUM> of the filtered liquid is poured in a previously weighed aluminum container which is heated on a heating plate under nitrogen flow, to remove the solvent by evaporation. Thus, the fraction (percent by weight) of polymer soluble in xylene (XS) is calculated from the average weight of the residues. The polymer fraction insoluble in o-xylene at <NUM> (XI) is calculated as: XI (%) = <NUM> - XS (%).

Flexural modulus was measured according to ISO <NUM>:<NUM>. Specimens for flexural test were cut from compression molded plaques pressed at <NUM> and aged via autoclave at RT for <NUM> at 2kbar. Specimens thickness was of <NUM>.

Particle size distribution is measured by laser diffraction according to ISO <NUM>:<NUM>.

Preparation of catalyst components: Dimethylsilyl{(<NUM>,<NUM>,<NUM>-trimethyl-<NUM>-indenyl)-<NUM>-(<NUM>,<NUM>-dimethyl-cyclopenta[<NUM>,<NUM>-b:<NUM>,<NUM>-b']-dithiophene)} zirconium dichloride (metallocene A-<NUM>) was prepared according to Example <NUM> of <CIT>.

Preparation of the catalytic solution: Under nitrogen atmosphere, <NUM> of a <NUM>/L solution of TIBA in isododecane and <NUM> of <NUM>% wt/wt solution of MAO in toluene are loaded in a <NUM> j acketed glass reactor, stirred by means of an anchor stirrer, and allowed to react at room temperature for about <NUM> hour under stirring.

After this time, <NUM> of metallocene A-<NUM> is added and dissolved under stirring for about <NUM> minutes.

The final solution is discharged from the reactor into a cylinder through a filter to remove eventual solid residues.

The composition of the solution resulted to be:.

Polymerization of the butene-<NUM> copolymer. The polymerization was carried out in two stirred reactors operated in series, in which liquid butene-<NUM> constituted the liquid medium. The catalyst system described above was fed in both reactors. The polymerization conditions are reported in Table <NUM>. The butene-<NUM> copolymer was recovered as melt from the solution and cut in pellets. The copolymer was further characterized and the data are reported in Table <NUM>.

<FIG> illustrates the variation of viscoelastic properties (E', E" and Tan δ) of the butene-<NUM> copolymer with the temperature measured by DMTA.

Filled polyolefin compositions were prepared by blending in the molten state the butene-<NUM> copolymer described above and different amounts of calcium carbonate having particle size distribution in which d(<NUM>) is <NUM>, d(<NUM>) is <NUM> and d(<NUM>) is <NUM>. The amount of component (A) and (B), the MFR values and storage modulus of the compositions of the examples are indicated in table <NUM>. The variation of viscoelastic properties of the compositions with temperature is illustrated in <FIG>.

Claim 1:
A filled polyolefin composition comprising:
(A) a copolymer of butene-<NUM> with at least one comonomer selected from the group consisting of ethylene, propylene, C5-C10 alpha-olefins and mixtures thereof, having copolymerized comonomer content of <NUM>-<NUM> wt.%, Melt Flow Rate (MFR) values measured according to ISO <NUM> (<NUM>, <NUM>) of from <NUM> to <NUM>,<NUM>/<NUM>, a molecular weight distribution (Mw/Mn) lower than <NUM>, X-ray crystallinity comprised in the range <NUM>-<NUM>%, and
(B) up to <NUM> wt.% of at least one inorganic filler,
wherein the amounts of (A) and (B) are referred to the total weight of (A) + (B).