WO2011064119A1

WO2011064119A1 - Polyolefin compositions having a low seal temperature and improved hot tack

Info

Publication number: WO2011064119A1
Application number: PCT/EP2010/067479
Authority: WO
Inventors: Spencer S. Hirata; Michele Grazzi; Giampaolo Pellegatti; Andrea Felisati; Dean J. Spencer
Original assignee: Basell Poliolefine Italia S.R.L.
Priority date: 2009-11-24
Filing date: 2010-11-15
Publication date: 2011-06-03

Abstract

Polyolefin compositions comprising, all percentages being by weight: A) from 60 to 94% of one or more copolymers of propylene containing from 5 to 25% of comonomer(s); B) from 2 to 20% of one or more homo or copolymers of butene-1; C) from 1 to 20% of an elastomeric or plastomeric polyolefin or polyolefin composition.

Description

POLYOLEFIN COMPOSITIONS HAVING A LOW SEAL TEMPERATURE AND IMPROVED HOT TACK.

The present invention relates to polyolefm compositions useful in the preparation of heat- sealable films, containing propylene copolymers and other polyolefm components.

Copolymers of propylene with other olefins (mainly ethylene, butene-1 or both), or mixtures of such copolymers with other olefin polymers are known in the prior art as heat-sealable materials.

These copolymers are obtained by polymerizing propylene with minor amounts of other olefin comonomers in the presence of coordination catalysts.

The polymerized comonomer units are statistically distributed in the resulting copolymer and the melting point of said copolymers results to be lower than the melting point of crystalline propylene homopolymers. Also the seal initiation temperature (as later defined in detail) of the said copolymers results to be favorably low.

However, particularly demanding applications of films, like form and fill packaging, require not only a low seal initiation temperature (hereinafter called "S.I.T."), but also a good "hot tack". As explained in US4725505, hot tack is the bonding strength measurable while the polymer in the heat sealed portion of a film is still in the semimolten/solidifying state.

Said form and fill packaging is commonly applied in the food packaging, especially for the production of bags to be used for solid and/or liquid products. The bags are produced with packaging machines that simultaneously seal the bottom seam of the bag and fills it while it is in the vertical or horizontal position. Thus the sealing, while still in the semimolten/solidifying state, must be able to withstand the weight of the product introduced in the bag and generally also the pressure of air used to assist in transport of the product. According to the said US4725505, the hot tack is improved by adding at least 40%by weight of a butene-1 -propylene copolymer to a propylene-ethylene copolymer. The hot tack strength values so obtained, measured by carrying out the test under air pressure, are in the range of 10-15 inch of water.

According to US2005/0142367, relatively high values of hot tack strength are achieved by blending a propylene-butene-1 -ethylene terpolymer with a metallocene catalyzed ethylene polymer. The terpolymer used in the examples contains relatively high amounts of comonomers, namely 1.7 mol% of ethylene and 16.2 mol% of butene-1. The hot tack strength values obtained are lower than 250 g (about 2.5 N). At 210°F (about 99°C) it is lower than 200. It appears to be insufficient at temperatures lower than 200°F (about 93°C). It has now surprisingly been found that a particularly valuable balance of heat-sealability (very low S.I.T.), hot tack and optical properties (in particular a low Haze) is obtained by blending a major amount of specific propylene copolymers with a butene-1 polymer and an elastomeric or plastomeric polyolefm or polyolefm composition.

Therefore the present invention provides polyolefm compositions comprising (by weight):

A) from 60 to 94%, preferably from 70 to 93%, more preferably from 75 to 93% of one or more copolymers of propylene with one or more comonomers selected from ethylene, a C4-C8 α-olefm and combinations thereof, where the comonomer, or comonomers, content in (A) is from 5 to 25%, preferably from 7 to 20%;

B) from 2 to 20%, preferably from 5 to 15%, of one or more homo or copolymers of butene-1 ;

C) from 1 to 20%, preferably from 2 to 15%, more preferably from 2 to 12, of an elastomeric or plastomeric polyolefm or polyolefm composition.

The said amounts of A), B) and C) are referred to the total weight of A) + B) + C).

From the above definitions of propylene copolymer(s) A), it is evident that the term

"copolymer" includes polymers containing more than one kind of comonomers.

The C4-C8 a-olefms, as well as all the a-olefms hereinafter reported as comonomers in olefin copolymers, are selected from olefins having formula CH2=CHR wherein R is an alkyl radical, linear or branched, or an aryl radical, having the appropriate number of carbon atoms; thus, for instance, from 1 to 8 carbon atoms for C3-C10 α-olefms, or from 2 to 8 carbon atoms for C4-C10 a-olefms.

Specific examples of C3-C10 α-olefms are propylene, butene-1, pentene-1, 4-methylpentene-l, hexene-1 and octene-1.

Preferred examples of component A) are the compositions comprising (by weight):

A¹) 15-80%, preferably 20-60 %, more preferably 20-50%, of one or more copolymers of propylene selected from the group consisting of (A^!l) propylene/ethylene copolymers containing 1-7% of ethylene; (A¹ 2) copolymers of propylene with one or more C4-C8 alpha-olefms, containing from 2 to less than 14% of the C4-C8 alpha-olefms; (A¹ 3) copolymers of propylene with ethylene and one or more C4-C8 alpha-olefms, containing 0.5-4.5% of ethylene and 2-6% of C4-C8 alpha-olefms, provided that the total content of ethylene and C4-C8 alpha-olefms in (A¹ 3) be equal to or lower than 6.5%;

A¹¹) 20-85%, preferably 40-80 %, more preferably 50-80%, of one or more copolymers of propylene selected from the group consisting of (A¹¹ 1) copolymers of propylene with one or more C4-C8 alpha-olefms, containing from 14% to 30%, preferably from 14.5% to 25% of C4-C8 alpha-olefms; (A¹¹ 2) copolymers of propylene with ethylene and one or more C4-C8 alpha-olefms, containing 0.5-5% of ethylene and 9-30%> of C4-C8 alpha-olefms.

Particularly preferred examples of component A) are the compositions comprising (by weight):

A¹) from 15% to 60%, preferably from 20% to 60%, more preferably from 20% to 50%, of a copolymer of propylene with C4-C8 alpha-olefm(s), preferably butene, containing more than 10%, preferably 1 1% or more, but less than 14%, more preferably up to 13%- 13.5%), of said C4-C8 alpha-olefm(s);

A¹¹) from 40% to 85%, preferably from 40% to 80%, more preferably from 50% to 80%, of a copolymer of propylene with C4-C8 alpha-olefm(s), preferably butene, containing from 14% to 30%, preferably from 14.5% to 25%, more preferably from 14.5% to 22%, of said C4-C8 alpha-olefm(s), and optionally from 0.5%> to 3% of ethylene;

provided that the total content of C4-C8 alpha-olefm(s) in the propylene polymer composition be higher than 10%.

Such compositions and their preparation are disclosed in WO03/031514.

The preferred comonomers in the said copolymers or of propylene are ethylene and butene- 1.

Preferably the MFR (Melt Flow Rate) values for propylene copolymers or propylene copolymer compositions A) range from 0.5 to 15 g/10 min., more preferably 2 to 15 g/10 min., most preferably from 2.5 to 10 g/10 min, measured at 230°C, with 2.16 kg load.

The said MFR values can be obtained directly in polymerization, or by subjecting to degradation (for instance by using organic peroxides according to known methods) a precursor polymer or polymer composition having lower MFR values.

All the said copolymers of propylene can be prepared by using a Ziegler-Natta catalyst in the polymerization process.

The said catalysts and the polymerization processes are known in the art.

Conventional molecular weight regulators known in the art, such as chain transfer agents (e.g. hydrogen or ZnEt₂), may be used.

Preferred examples of Ziegler-Natta catalysts are the supported catalyst systems comprising a trialkylaluminium compound, optionally an electron donor, and a solid catalyst component comprising a halide or halogen-alcoholate of Ti and optionally an electron-donor compound supported on anhydrous magnesium chloride. Catalysts having the above-mentioned characteristics and polymerization processes employing such catalysts are well known in the patent literature; particularly advantageous are the catalysts and polymerization processes described in USP 4,399,054 and EP-A-45 977. Other examples can be found in USP 4,472,524.

The so obtained copolymers of propylene can be blended in the molten state, with conventional apparatuses and techniques, to obtain the previously defined compositions. In alternative, the said compositions can be obtained directly in polymerization, by carrying it out in at least two sequential steps, wherein the copolymer components are prepared in separate subsequent steps, operating in each step in the presence of the polymer formed and the catalyst used in the preceding step.

The homo- or copolymers B) of butene-1 are well known in the art, particularly for their good properties in terms of pressure resistance and creep resistance. Such homo or copolymers are generally prepared by polymerizing butene-1 in the presence of certain Ziegler/Natta catalyst systems.

Suited homoplymers B) of butene-1 are linear, semicrystalline, higly isotactic homopolymers (having in particular an isotacticity from 96 to 99%, measured both as mmmm pentads/total pentads using NMR, and as quantity by weight of matter soluble in xylene at 0°C). Preferably they have a melting point Tm(II) of crystalline form 2 (the first to form, being favoured kinetically) from 81 to 109°C.

Suitable copolymers B) of butene-1 are the copolymers preferably containing up to 30 mol. % of olefmic comonomers (in particular ethylene, propylene and Cs-Cs a-olefms, like pentene-1 , hexene-1 and octene-1).

All these homo- or copolymers of butene-1 can be obtained with polymerization processes and catalysts well known in the art, like low-pressure Ziegler-Natta polymerization of butene- 1, for example by polymerizing butene-1 (and any comonomers) with catalysts based on T1CI₃, or supported catalysts systems of the same kind as described above for the preparation of the copolymers of propylene.

Other preferred features of the copolymers B) are:

- amounts of comonomers from 1 to 20% by weight, more preferably from 1 to 15% by weight;

- a flexural modulus of 80 MPa or higher, in particular 80 to 300 MPa, even more preferably 150 to 300 MPa;

- MFR at 190°C, 2.16 kg, of 0.5 - 20 g/10 min., in particular 0.5 - 10 g/10 min.;

- Tm(II) of 80 - 109 °C.

Preferred comonomers in the copolymers B) are ethylene and propylene. High MFR values can be obtained by successive treatment of the polymer with organic peroxides.

The elastomeric or plastomeric polyolefm or polyolefm composition C) can be any elastomeric or plastomeric polymer or polymer composition commonly used to modify the mechanical properties of polyolefins.

The term "plastomeric" in the definition of the present invention is used to include the particular class of materials having properties intermediate to those of thermoplastic and elastomeric materials, generally called "plastomers". Said plastomers can have a broad range of densities (up to about 0.925 g/cm³) and a higher crystallinity than the traditional elastomers. Be it an elastomeric or plastomeric material, the said component C) typically has at least one of the following features:

- Flexural modulus (ISO 178A) equal to or less than 200 MPa, preferably equal to or less than 170 MPa, most preferably equal to or less than 100 MPa;

- Shore D hardness equal to or less than 50 points, more preferably equal to or less than 45 points and most preferably equal to or less than 32 points;

- Shore A hardness equal to or less than 90 points;

- X-ray crystallinity from 0 to 40%, more preferably from 0 to 30%.

Preferred examples of C) are:

1) ethylene copolymers containing up to 45% by weight, in particular from 10 to 42% by weight, of an olefin comonomer, preferably a C3-C10 a-olefm, in particular butene-1 or octene-1, and having Shore A hardness of 90 points or less.

2) propylene copolymers containing up to 40% by weight of an olefin comonomer, preferably ethylene or a C4-C10 a-olefm, and having Shore A hardness of 90 points or less.

The said ethylene copolymers 1) have typically a density from 0.86 to 0.925 g/cm³.

A specific example of copolymers 1) is a copolymer containing 62 wt% of ethylene and 38 wt% of octene-1 (IR analysis), having a hardness of 21 Shore D points and 75 Shore A points, a melting point of 60°C, a MFR of 5 g/10 min. (ASTM D 1238, 190°C/2.16 kg) and a density of 0.87 g/ml according to method ASTM D 792.

It is marketed by Dow Chemical with the trademark Engage 8200.

Other polymer materials of this kind, sold by Dow under the trademark Affinity can also be conveniently used.

Another specific example of copolymers 1) is a copolymer containing 61 wt% of ethylene and 39 wt% of octene-1 (IR analysis), having a hardness of 20 Shore D points and 75 Shore A points, a melting point of 55°C, a density of 0.868 g/cm³ according to method ASTM D 792 and MFR of 0.5 g/10 min (ASTM D 1238, 190°C/2.16 kg).

It is marketed by Dow Chemical with the trademark Engage 8150.

Another specific example of copolymers 1) is a copolymer of ethylene and butene-1, having a hardness of 30 Shore D points, 85 Shore A points, flexural modulus of 22.8 MPa (ASTM D 790), melting point of 60°C and a density of 0.88 g/cm³ according to method ASTM D 792. It is marketed by Exxon Chemical with the trademark Exact 4033.

Preferred examples of propylene copolymers 2) are the propylene copolymers containing from 0.1 to 40% by weight, more preferably from 0.1 to 25% by weight of olefin comonomers, in particular ethylene.

The said propylene copolymers 2) have typically a density from 0.850 to 0.890 g/cm³, in particular from 0.855 to 0.885 g/cm³. They generally display no or relatively low degree of crystallinity, indicatively from 0 to 25% when measured as X- ray crystallinity.

Other typical properties of propylene copolymers 2) are:

- Shore A hardness equal to or less than 90 points, preferably equal to or less than 88 points, more preferably equal to or less than 75 points;

- melting point, measured with differential scanning calorimetry (DSC) at a heating /cooling rate of 10-20°C, of 105°C or less, preferably of 90°C or less;

- heat of fusion, measured with DSC under the said conditions, of 75 J/g or less;

- molecular weight distribution, in terms of Mw/Mn (Mw = weight average molecular weight and Mn = number average molecular weight, both measured by gel permeation chromatography in trichlorobenzene at 135 °C) from 1.5 to 5, more preferably from 1.5 to 3.5. Suitable propylene copolymers 2) are the plastomers Vistamaxx® and Versify® made available on the market by ExxonMobil Chemical and Dow Chemical, and the Notio® polymers, made available on the market by Mitsui Petrochemical.

The said copolymers 1) and 2) are typically produced by polymerization in the presence of metallocene catalysts.

As previously said, the compositions of the present invention have low seal initiation temperatures (preferably lower than 70 °C), high values of hot tack strength (higher than 2.5 N, in particular higher than 2.8 N, at temperatures of 75°C or higer) and good values of haze and gloss.

The compositions of the present invention are obtainable by melting and mixing the components, and the mixing is effected in a mixing apparatus at temperatures generally of from 180 to 310°C, preferably from 190 to 280°C, more preferably from 200 to 250°C. Any known apparatus and technology can be used for this purpose.

Useful melt-mixing apparatus in this context are in particular extruders or kneaders, and particular preference is given to twin-screw extruders. It is also possible to premix the components at room temperature in a mixing apparatus.

During the preparation of the compositions, besides the main components A), B) and C), it is possible to introduce additives commonly employed in the art, such as stabilizing agents (against heat, light, U.V.), plasticizers, antiacids, antistatic and water repellant agents, slip agents, antiblocking agents.

As previously said, the compositions of the present invention are particularly useful for the preparation of films.

Films are generally characterized by a thickness of less than 100 μιη and can be mono- or multilayer.

In the case of multilayer films, at least one layer comprises the compositions of the present invention. Each layer that does not comprise the compositions of the present invention can be composed of other olefin polymers, such as polypropylene or polyethylene.

Generally speaking, the films of this invention can be prepared by known techniques, such as extrusion and calendering. Specific examples of films containing the compositions of the present invention are disclosed hereinafter in the test for determining the seal initiation temperature (S.I.T.) and the hot tack.

The particulars are given in the following examples, which are given to illustrate, without limiting, the present invention.

The following analytical methods are used to determine the properties reported in the description and in the examples.

Ethylene, butene-1 and octene-1 content of the polymers

Determined by I.R. spectroscopy.

Melt Flow Rate MFR

Determined according to ASTM D 1238, at 230°C, 2.16 kg load for propylene polymers, at 190°C, 2.16 kg load for butene-1 and ethylene polymers.

Flexural modulus

Measured according to ISO 178.

Melting temperature (Tm) - (ISO 11357-3)

Determined by differential scanning calorimetry (DSC). A sample weighting 6 + 1 mg, is heated to 200 ± 1° C at a rate of 20 °C/min and kept at 200 + F C for 2 minutes in nitrogen stream and it is thereafter cooled at a rate of 20° C/min to 40 ± 2° C, thereby kept at this temperature for 2 min to crystallise the sample. Then, the sample is again heated at a temperature rise rate of 20° C/min up to 200° C ± 1. The heating scans are recorded, thermograms are obtained, and, from this, temperatures corresponding to peaks are read. The melting point can be determined either in the first or in the second heating run, or in both the two runs. It is preferably determined in the first heating run for butene-1 homopolymers and copolymers, and in the second for propylene polymers. The temperature corresponding to the most intense melting peak recorded during the relevant heating run is taken as the melting temperature.

Xylene soluble fraction - Propylene polymers

Determined as follows.

2.5 g of polymer and 250 cm³ of xylene are introduced in a glass flask equipped with a refrigerator and a magnetical stirrer. The temperature is raised in 30 minutes up to the boiling point of the solvent. The so obtained clear solution is then kept under reflux and stirring for further 30 minutes. The closed flask is then kept for 30 minutes in a bath of ice and water and in thermostatic water bath at 25 °C for 30 minutes as well. The so formed solid is filtered on quick filtering paper. 100 cm³ 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. The container is then kept in an oven at 80 °C under vacuum until constant weight is obtained.

Xylene soluble fraction - Butene-1 polymers

Determined as follows.

2.5 g of polymer are dissolved in 250 ml of xylene, at 135°C, under agitation. After 20 minutes, the solution is cooled to 0°C under stirring, and then it is allowed to settle for

30 minutes. The precipitate is filtered with filter paper; the solution is evaporated under a nitrogen current, and the residue dried under vacuum at 140°C until constant weight.

The weight percentage of polymer soluble in xylene at 0°C is then calculated. The percent by weight of polymer insoluble in xylene at room temperature is considered the isotactic index of the polymer.

¹³C-NMR Isotacticity Index - Butene-1 polymers

50 mg of each sample are dissolved in 0.5 mL of C2D2CI4.

The ¹³C NMR spectra are acquired on a Bruker DPX-400 (100.61 Mhz, 90° pulse, 12s delay between pulses). About 3000 transients are stored for each spectrum; mmmm pentad peak (27.73 ppm) is used as reference. The microstructure analysis is carried out as described in literature (Macromolecules 1991, 24, 2334-2340, by Asakura T. et Al. and Polymer, 1994, 35, 339, by Chujo R. et AL).

The percentage value of pentad tacticity (mmmm%) 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 27.73 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 alfa- olefin comonomer .

Determination of the hot tack strength and of the seal strength (S.I.T.)

For the hot tack strength measurements, the following two methods are used.

Method 1

The film to be tested is first formed into a tube 76 mm (3 inches) long by 76 mm (3 inches) flat, wherein the test composition is in the inside layer.

The test is carried out according to the test method described in the experimental section of US4725505. Namely, the open end of the film tube is inserted into a Sentinel heat sealer. The seals are made at increasing temperatures under the following conditions:

- sealing pressure of 0.14 MPa (20 psi);

- dwell time of 2 seconds.

While the tube is being sealed, air is introduced in the tube. After the heat sealing is completed, the sample is removed from the heat sealer and then inspected. The hot tack strength is given by the maximum pressure, in inches of water, at which the seal under testing does not peel or creep more than 0.32 cm (1/8 inch).

Method 2 - (ASTM F 1921)

For each test film specimens 15 mm wide are superimposed in alignment, the adjacent layers being layers of the particular test composition.

The seals are made at increasing temperatures (5°C steps) with a J&B Hot tack tester 3000 sealer, equipped with brass teflon coated sealing bars, at one end of the said superimposed specimens along the 15 mm side and the hot tack strength is measured by peeling the specimens at a speed of 100 mm sec.

The sealing conditions are:

- sealing pressure of 0.1 MPa (14.5 psi);

- dwell time of 0.5 sec The test is carried out immediately after sealing (0.2 sec). The hot tack strength is given by the load required to separate the sealed specimens.

For the seal strength measurements, the superimposed specimens are sealed along one of the 15 mm sides with a RDM HSE-3 five bars sealer type. Sealing time is 0.5 seconds at a pressure of 0.1 MPa (14.5 psi). The sealing temperature is increased for each seal with steps of 5°C, starting from a sufficiently low temperature to make it possible to determine a significant level of sealing force. The sealed samples are left to cool for 24 hours and then their unsealed ends are attached to an Instron machine (4301 model) where they are tested at a crosshead speed of 100 mm/min (grip distance 50 mm). Reference is standard ASTM F 88.

The S.I.T. is the minimum sealing temperature at which the seal shows a sealing force of 2.0 Newtons in the said test conditions.

Haze on film

The measurement is carried out on a 50 x 50 mm portion cut from the central zone of the film.

The instrument used for the test is a Gardner photometer with Haze-meter UX-10 equipped with a G.E. 1209 lamp and filter C. The instrument calibration is made by carrying out a measurement in the absence of the sample (0% Haze) and a measurement with intercepted light beam (100% Haze).

Gloss on film

Determined on the same specimens as for the Haze.

The instrument used for the test is a model 1020 Zehntner photometer for incident measurements. The calibration is made by carrying out a measurement at incidence angle of 60 ° on black glass having a standard Gloss of 96.2% and a measurement at an incidence angle of 45 ° on black glass having a standard Gloss of 55.4%>.

Examples 1 and 2 and Comparison Example 1

The following materials are used as components A), B) and C).

Component A)

Propylene copolymer composition having a MFR of 5.5 g/10 min., prepared according to Example 6 of WO03/031514 and comprising, by weight:

A¹) 30%), of a copolymer of propylene with butene-1, containing 12%> by weight of butene- i;

A¹¹) 70% of a copolymer of propylene with ethylene and butene-1, containing 1% by weight of ethylene and 16%> by weight of butene-1. The MFR of 5.5 g/10 min. is obtained by thermal treatment with peroxide of the as- polymerized composition, having starting MFR of about 1 g/10 min.

Component B)

Copolymer of butene-1 with 2.5% by weight of ethylene, having MFR of 3 g/10 min at 190°C/2.16kg and fiexural modulus of 140 MPa.

Component C)

Engage 8200 as previously described.

The following additional materials are used for the preparation of the films.

PP-1

A propylene homopolymer having a content of fraction insoluble in xylene at room temperature of 96% and a MFR value of 2 g/10 min.

PP-2

Copolymer of propylene with ethylene and butene-1, containing 2.5% by weight of ethylene and 6% by weight of butene-1, having a MFR of 6 g/10 min. and melting temperature of 132°C, containing also 1000 ppm of silica as antiblocking agent.

Film preparation

Triple-layer films are prepared by coextrusion (using three Bruckner extruders, operating at temperatures of 260°C [melt temperature of the main extruder] and 235°C [melt temperature of the side extruders] and connected to a flat die), said films having an a/b/c structure, wherein layer (b) consists of PP-1, while layer (a) in the films of Examples 1 and 2 consists a blend of components A), B) and C), pre-blended in the solid state, and in the film of Comparison Example 1 of the pure component A), and layer c) consists of PP-2. The film obtained is then bioriented by stretching it 5 times the original length in the machine direction and 8 times in the transversal direction, operating in an oven at 170 °C. The final thickness of the film is 20 μιη and the thickness ratio of the layers is 5/90/5.

The properties of the films so obtained are reported in Table 1, together with the relative proportions of components A), B) and C) for Examples 1 and 2. Table 1

Note to the table:

* measured according to HOT TACK method 1 ;

** measured according to HOT TACK method 2. From Table 1 it is evident that the compositions of the present invention provide a satisfactory value of hot tack strength already at 75°C, and that such value undergoes only minor variations in a temperature range from at least 80 to 100°C.

The absence of data relating to hot tack strength and seal strength means that no acceptable values are obtained.

Claims

Polyolefm compositions comprising, all percentages being by weight:

A) from 60 to 94% of one or more copolymers of propylene with one or more comonomers selected from ethylene, a C4-C8 α-olefm and combinations thereof, where the comonomer, or comonomers, content in (A) is from 5 to 25%, preferably from 7 to 20%;

B) from 2 to 20% of one or more homo or copolymers of butene-1 ;

C) from 1 to 20% of an elastomeric or plastomeric polyolefm or polyolefm composition.

The polyolefm compositions of claim 1, wherein component A) comprises, all percentages being by weight:

A¹) 15-80%, preferably 20-60 %, more preferably 20-50%, of one or more copolymers of propylene selected from the group consisting of (A¹ 1) propylene/ethylene copolymers containing 1-7% of ethylene; (A¹ 2) copolymers of propylene with one or more C4-C8 alpha-olefms, containing from 2 to less than 14% of the C4-C8 alpha-olefms; (A¹ 3) copolymers of propylene with ethylene and one or more C₄- C8 alpha-olefms, containing 0.5-4.5% of ethylene and 2-6% of C4-C8 alpha- olefms, provided that the total content of ethylene and C4-C8 alpha-olefms in (A¹ 3) be equal to or lower than 6.5%>;

A¹) from 15% to 60%, preferably from 20% to 60 %, more preferably from 20% to 50%), of a copolymer of propylene with C4-C8 alpha-olefm(s), preferably butene, containing more than 10%, preferably 11% or more, but less than 14%, more preferably up to 13%- 13.5%, of said C4-C8 alpha-olefm(s);

A¹¹) from 40% to 85%, preferably from 40% to 80 %, more preferably from 50% to 80%), of a copolymer of propylene with C4-C8 alpha-olefm(s), preferably butene- 1, containing from 14% to 30%, preferably from 14.5% to 25%, more preferably from 14.5% to 22%, of said C4-C8 alpha-olefm(s), and optionally from 0.5%> to 3%) of ethylene;

4. The polyolefm compositions of claim 1, wherein component A) has MFR values from 0.5 to 10 g/10 min..

5. The polyolefm compositions of claim 1, wherein component B) is selected from butene- 1 homoplymers and copolymers of butene- 1 with up to 30 mol.% of olefmic comonomers.

6. The polyolefm compositions of claim 1, wherein component B) is a copolymer of butene- 1 having flexural modulus of 80 MPa or higher.

7. The polyolefm compositions of claim 1, wherein component C) has at least one of the following properties:

- Flexural modulus (ISO 178 A) equal to or less than 200 MPa, preferably equal to or less than 170 MPa, most preferably equal to or less than 100 MPa;

- Shore A hardness equal to or less than 90 points;

- X-ray crystallinity from 0 to 40%, more preferably from 0 to 30%.

8. Mono- or multilayer films, wherein at least one layer comprises the polyolefm compositions of claim 1.