Polypropylene composition with excellent sealing properties

Abstract

The present invention provides a polypropylene composition (I), which comprises: (A) at least 90% by weight of a propylene polymer comprising: (a) 20 to 44% by weight of a propylene-hexene copolymer; (b) 25 to 45% by weight of a propylene-hexene-ethylene terpolymer; and (c) 25 to 50% by weight of a propylene-ethylene copolymer, wherein: - the melt flow rate of components (a)+(b)+(c) is in the range of 3.5 to 12.0 g / 10 min; - the xylene solubles content of the propylene polymer (A) is in the range of 16.4% to 35.3% by weight; and - the melting point of the propylene polymer (A) is in the range of 122°C to 132°C; and (B) not more than 10.0% by weight of polybutene, wherein the amounts of (A) and (B) are based on the combined weight of (A)+(B).

Description

[Technical Field]

[0001] The present disclosure relates to polypropylene compositions comprising copolymers of propylene and 1-hexene, propylene-ethylene-hexene copolymers, and copolymers of propylene and ethylene, blended with polybutene, that are particularly suitable for producing films, such as biaxially oriented polypropylene (BOPP) and cast films, that have low seal initiation temperatures (SIT), high crystallization temperatures, and low fisheye counts. [Background technology]

[0002] Copolymers of propylene and 1-hexene are already known in the art. For example, WO 2006 / 002778 describes a copolymer of propylene and 1-hexene having 0.2% to 5% by weight of units derived from 1-hexene. This copolymer has a monomodal molecular weight distribution and is used in pipe systems.

[0003] WO 2017 / 097579 relates to a composition comprising a copolymer of propylene and 1-hexene and a copolymer of propylene and ethylene, which is particularly suitable for producing films, in particular biaxially oriented polypropylene films (BOPP) and cast films with low seal initiation temperatures (SIT) and high transparency. The seal initiation temperature can be lowered because it is still not sufficient.

[0004] WO 2018 / 202396 relates to a propylene polymer composition containing 35% to 65% by weight of a propylene-1-hexene copolymer containing 10.2 to 13% by weight of units derived from 1-hexene and 35% to 65% by weight of a propylene-ethylene copolymer containing 1.5% to 6.5% by weight of units derived from ethylene. Although the exemplified composition exhibits a low SIT, it has a high xylene soluble content.

[0005] Films comprising a blend of polypropylene and polybutene-1 in the outer sealing layer are known in the art.

[0006] Patent application WO2004 / 048424 discloses a multilayer film with a low seal initiation temperature, the sealing layer of which comprises a combination of polybutene-1 containing 2.1 mol % ethylene and a propylene-butene-ethylene terpolymer.

[0007] WO2012 / 031953 discloses the use of butene-1 homo- or copolymer to reduce the seal initiation temperature of a sealing layer containing propylene copolymer and hexene-1. The number of fisheyes in the film was also reduced.

[0008] The applicant has discovered that by using a polypropylene composition containing propylene-1-hexene copolymer, propylene-1-hexene-ethylene terpolymer, and propylene-ethylene copolymer as component (A) and polybutene as component (B), it is possible to produce a film or sheet having a low seal initiation temperature (SIT), a high crystallization temperature, good optical properties, and a small number of fisheyes. Summary of the Invention

[0009] The present disclosure provides a polypropylene composition (I), (A) at least 90.0 wt. % propylene polymer (based on the weight of (a)+(b)+(c)), said weight being 100%; (a) 20% to 44% by weight of a propylene-hexene copolymer, based on the weight of component (a), containing 5.0% to 8.3% by weight of hexene-derived units and having a melt flow rate (MFR(a)) of 3.5 to 8.5 g / 10 min, as measured in accordance with ISO 1133-1:2011 (230°C / 2.16 kg); (b) 25% to 45% by weight of a propylene-hexene-ethylene terpolymer containing 7.2% to 12.0% by weight of units derived from hexene and 0.5% to 2.5% by weight of units derived from ethylene, and having a melt flow rate (MFR(a+b)) of components a)+b) measured in accordance with ISO 1133-1:2011 (230°C / 2.16 kg) in the range of 3.5 to 8.5 g / 10 min; (c) containing 3.5 wt% to 8.7 wt% of ethylene-derived units; 25% to 50% by weight of a propylene-ethylene copolymer, wherein the melt flow rate (230°C / 2.16 kg) of components (a)+(b)+(c) measured in accordance with ISO 1:2011 is in the range of 3.5 to 12.0 g / 10 min; The propylene polymer (A) is (i) a xylene solubles at 25°C in the range of 13.0% to 25.0% based on the weight of (a) + (b) + (c); and (ii) a propylene polymer having a melting point in the range of 122°C to 132°C; (B) 10.0 wt. % or less of polybutene selected from butene homopolymers, butene copolymers containing 5.0 wt. % or more of units derived from ethylene and / or propylene, based on the weight of component (B), and mixtures thereof; The amounts of (A) and (B) are based on the total weight of (A)+(B), which total weight is 100% to provide polypropylene composition (I).

[0010] The polypropylene composition (I) of the present disclosure has excellent thermal properties, sealing properties, and optical properties, and is therefore suitable for producing films or sheets.

[0011] Therefore, a further object of the present disclosure is a film or sheet comprising the polypropylene composition (I).

[0012] While multiple embodiments are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description. As will be apparent, the particular embodiments disclosed herein can be modified in various obvious aspects without departing from the spirit and scope of the claims presented herein. Accordingly, the following detailed description is to be regarded as illustrative in nature and not restrictive. DETAILED DESCRIPTION OF THE INVENTION

[0013] In the context of this disclosure: -Percentages are expressed by weight unless otherwise specified. - Unless otherwise specified, the total weight of the polymer composition is 100%. The term "comprises" when referring to a polymer, plastic material, polymer composition, mixture or blend is to be interpreted as meaning "comprises or consists essentially of." The term "consisting essentially of" means that in addition to the essential components, other components may also be present in the material, so long as the essential properties of the material are not substantially affected by their presence. Examples of components that, when present in normal amounts, do not substantially affect the properties of the polymer or polyolefin composition, mixture, or blend include catalyst residues, antistatic agents, processing aids, melt stabilizers, light stabilizers, antioxidants, and antacids. - The term "copolymer" refers to a polymer resulting from the deliberate polymerization of two different comonomers, i.e. the term "copolymer" does not include terpolymers. - The term "terpolymer" refers to a polymer resulting from the deliberate polymerization of three different comonomers. The term "hexene" refers to hexene-1. The term "butene" refers to butene-1, and the term "polybutene" refers to polymers of butene-1. - "Film" means a thin layer of material having a thickness of 2000 μm or less. - "sheet" means a layer of material having a thickness greater than 2000 μm; The term "skin layer" refers to the outermost layer of a multilayer film. The term "base layer" refers to the innermost layer of a multilayer film.

[0014] The present disclosure provides: at least 90.0% by weight, preferably 90.0% by weight to 99.5% by weight, more preferably 93.0% by weight to 99.0% by weight, and even more preferably 95.0% by weight to 98.0% by weight of propylene polymer (A); -% by weight or less of polybutene (B), preferably 0.5% to 10.0%, more preferably 1.0% to 7.0%, and even more preferably 2.0% to 5.0%, The amounts of (A) and (B) are based on the total weight of (A)+(B), which total weight is 100% to provide polypropylene composition (I).

[0015] The individual components of the polypropylene composition (I) are defined in more detail below. The individual components may be contained in the polypropylene composition (I) in any combination.

[0016] Propylene polymer (A) is (based on the weight of (a) + (b) + (c), this weight being 100%) (a) 20% to 44% by weight, preferably 27% to 40% by weight, more preferably 29% to 35% by weight, of a propylene-hexene copolymer, based on the weight of component (a), which contains 5.0% to 8.3% by weight, preferably 6.3% to 7.8% by weight, more preferably 6.5% to 7.4% by weight of hexene-derived units, based on the weight of component (a), and which has a melt flow rate (MFR(a)) measured in accordance with ISO 1133-1:2011 (230°C / 2.16 kg) in the range of 3.5 to 8.5 g / 10 min, preferably 4.4 to 8.0 g / 10 min, more preferably 5.0 to 7.0 g / 10 min; (b) 25% by weight to 45% by weight, preferably 35% by weight to 40% by weight, more preferably 36% by weight to 39% by weight of a propylene-hexene-ethylene terpolymer, which contains 7.2% by weight to 12.0% by weight, preferably 7.5% by weight to 9.5% by weight, more preferably 8.2% by weight to 9.1% by weight of hexene-derived units and 0.5% by weight to 2.5% by weight, preferably 0.7% by weight to 2.2% by weight, more preferably 0.8% by weight to 2.0% by weight of ethylene-derived units, and a propylene-hexene-ethylene terpolymer, wherein the melt flow rate (MFR(a+b)) of components a)+b) measured in accordance with ISO 1133-1:2011 (230°C / 2.16 kg) is in the range of 3.5 to 8.5 g / 10 min, preferably 4.4 to 8.0 g / 10 min, more preferably 5.0 to 7.0 g / 10 min, and the amount of hexene and ethylene is based on the weight of (b); (c) 25% to 50%, preferably 27% to 40%, more preferably 29% to 35% by weight of a propylene-ethylene copolymer containing 3.5% to 8.7%, preferably 4.5% to 8.4% by weight of ethylene-derived units, based on the weight of (c); the melt flow rate of components (a)+(b)+(c), measured according to ISO 1133-1:2011 (230°C / 2.16 kg), is in the range of 3.5 to 12.0 g / 10 min, preferably 4.4 to 8.0 g / 10 min, and more preferably 5.0 to 8.5 g / 10 min; The propylene polymer (A) is (i) a xylene soluble content at 25°C in the range of 13.0 wt% to 25.0 wt%, preferably 14.0 wt% to 23.0 wt%, more preferably 15.0 wt% to 20.0 wt%, and (ii) It has a melting point of 122°C to 132°C, preferably 125°C to 131°C, and more preferably 126°C to 130°C.

[0017] Preferably, the propylene polymer (A) is a reactor blend of components (a), (b), and (c). The process for producing the propylene polymer (A) is preferably carried out in the presence of a highly stereospecific heterogeneous Ziegler-Natta catalyst. A Ziegler-Natta catalyst suitable for producing the propylene-ethylene copolymer of the present disclosure comprises a solid catalyst component containing at least one titanium compound having at least one titanium-halogen bond and at least one electron donor compound (internal donor), both of which are supported on magnesium chloride. The Ziegler-Natta catalyst system further comprises an organoaluminum compound as an essential cocatalyst, and optionally an external electron donor compound.

[0018] Suitable catalyst systems are described in European Patents EP 45977, EP 361494, EP 728769, EP 1272533 and International Patent Application WO000163261.

[0019] The organoaluminum compound is preferably an alkyl-Al selected from trialkylaluminum compounds such as triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, etc. It is also possible to use mixtures of trialkylaluminum with alkylaluminum halides, alkylaluminum hydrides, or alkylaluminum sesquichlorides (e.g., AlEtCl and AlEtCl).

[0020] Preferred external electron donor compounds include silicon compounds, ethers, esters such as ethyl 4-ethoxybenzoate, amines, heterocyclic compounds, especially 2,2,6,6-tetramethylpiperidine, ketones and 1,3-diethers. Another class of preferred external donor compounds is the compounds of formula R a 5 R b 6 Si(OR 7 ) cwherein a and b are integers from 0 to 2, c is an integer from 1 to 3, and the sum (a+b+c) is 4; R 5 , R 6 , and R 7 is an alkyl, cycloalkyl, or aryl radical having 1 to 18 carbon atoms, optionally containing heteroatoms. Particularly preferred are methylcyclohexyldimethoxysilane, diphenyldimethoxysilane, methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-t-butyldimethoxysilane, as well as 1,1,1,trifluoropropyl-2-ethylpiperidinyl-dimethoxysilane and 1,1,1,trifluoropropyl-methyl-dimethoxysilane. The external electron donor compound is used in an amount such that the molar ratio of the organoaluminum compound to the electron donor compound is 0.1 to 500, preferably 1 to 100, and more preferably 2 to 50.

[0021] The polymerization process may be continuous or batchwise and is preferably carried out according to known techniques operating in the gas or liquid phase, optionally in the presence of an inert diluent, or by the mixed liquid gas technique.

[0022] The gas phase polymerization is preferably carried out in three reactors, with each component being produced in a different reactor, and more preferably, components (a) and (b) are obtained in the first two reactors, respectively, and component (c) is obtained in the third and last reactor.

[0023] The polymerization reaction time, pressure, and temperature are not critical, but the polymerization temperature is preferably in the range of 20° C. to 100° C. The polymerization pressure is atmospheric pressure or, if possible, higher.

[0024] The molecular weight of components (a), (b) and (c) can be controlled by using known molecular weight control agents, particularly hydrogen.

[0025] Preferably, component (B) is a butene-ethylene copolymer. More preferably, component (B) is a butene-ethylene copolymer having at least one, and preferably all, of the following properties:

[0026] - the content of ethylene-derived units is in the range of 1.0% by weight to 4.5% by weight, preferably 1.5% by weight to 4.5% by weight, more preferably 2.0% by weight to 4.0% by weight, and even more preferably 2.5% by weight to 3.5% by weight, based on the weight of (B); and / or

[0027] the melting point Tm(I) of Form I, measured by DSC according to ISO 11357-3:2018, is less than 100°C, preferably in the range of from 80°C to less than 100°C, more preferably in the range of from 90°C to 97°C; and / or

[0028] a melt flow rate, measured according to ISO 1133-1:2011 (190°C / 2.16 kg), in the range of 1.0 to 6.0 g / 10 min, preferably 2.0 to 5.0 g / 10 min, and more preferably 3.0 to 4.5 g / 10 min; and / or

[0029] - A flexural modulus measured in accordance with ISO 178:2010 of at least 80 MPa, preferably in the range of 80 to 250 MPa, more preferably 100 to 210 MPa.

[0030] In a preferred embodiment, in addition to one or more of the above properties, the butene-ethylene copolymer (B) has a molecular weight distribution Mw / Mn in the range of 4.0 to 9.0, preferably 4.0 to 8.0, more preferably 4.0 to 7.0, and even more preferably more than 4.5 and less than 6.0.

[0031] In some embodiments, the polybutene (B) is obtained using a metallocene-based catalyst system.

[0032] In a preferred embodiment, the polybutene (B) is obtained by polymerizing the relevant monomers in the presence of a Ziegler-Natta catalyst system, as described above.

[0033] The polymerization process can be carried out according to known techniques, for example, slurry polymerization using a liquid inert hydrocarbon as diluent, or solution polymerization using, for example, liquid butene as the reaction medium. It is also possible to carry out the polymerization process in the gas phase, operating in one or more fluidized bed reactors or mechanically stirred bed reactors. Solution polymerization carried out using liquid butene as the reaction medium is highly preferred.

[0034] The polymerization is usually carried out at a temperature of 20° C. to 120° C., preferably 40° C. to 90° C. The polymerization can be carried out in one or more reactors which can operate under the same or different reaction conditions, such as molecular weight regulator concentration, comonomer concentration, temperature, pressure, etc.

[0035] Suitable catalyst systems and polymerization processes for obtaining polybutenes (B) are disclosed in patent document WO 2004 / 048424 A1.

[0036] Polybutene (B) is commercially available, for example under the trade name Toppyl, sold by LyondellBasell.

[0037] In one embodiment, the polypropylene composition (I) comprises 5.0 wt % or less, more preferably 0.01 wt % to 5.0 wt %, of at least one additive (C) selected from the group consisting of nucleating agents, antistatic agents, antioxidants, light stabilizers, slip agents, antacids, melt stabilizers, and combinations thereof, the amount of additive being based on the total weight of the polypropylene composition (I) including the additives, the total weight being 100%.

[0038] In one embodiment, the polyolefin composition (I) consists of component (A), component (B) and optionally additive (C) as described above.

[0039] The polyolefin composition (I) is obtained by mixing components (A), (B) and, optionally, (C) in conventional melt mixing equipment, such as a twin-screw extruder, operated under conventional conditions.

[0040] The polypropylene composition (I) has excellent thermal and sealing properties and can be advantageously used to produce films or sheets. The relatively high melting point improves the processability of the composition when used to produce films or sheets. The low SIT value makes the films and sheets suitable for sealing applications. The polyolefin composition (I) also results in films or sheets with a low number of fisheyes.

[0041] Advantageously, ΔTm-SIT (the difference between the Tm of the polypropylene composition (I) and the SIT measured for the BOPP film) is broad, thereby allowing good processability of the film.

[0042] Preferably, the SIT measured on the BOPP film is in the range of 70°C to 85°C, more preferably 72°C to 83°C.

[0043] In a preferred embodiment, the ΔTm-SIT value measured for the BOPP film is in the range of 40.0°C to 60.0°C, preferably 45.0°C to 55°C, and the Tm of the polypropylene composition (I) and the SIT on the BOPP film are measured as shown below.

[0044] In a further aspect, the present disclosure relates to a film or sheet comprising or consisting of the polypropylene composition (I) according to any one of the above embodiments.

[0045] The film or sheet may be single-layer or multi-layer, preferably a multi-layer film or sheet in which the polypropylene composition (I) is contained in at least one skin layer, more preferably in both skin layers.

[0046] The features describing the subject matter of this disclosure are not closely related to each other, and thus a preferred range of one feature may be combined with a more preferred or less preferred range of another feature, regardless of the level of preference. Example

[0047] The following examples are offered to illustrate the invention without limiting it.

[0048] Characterization Methods: The following methods are used to determine the properties set forth in the specification, claims, and examples.

[0049] Melt flow rate: Measured according to the ISO 1133-1:2011 method (230°C / 2.16 kg for propylene polymers, 190°C / 2.16 kg for polybutene).

[0050] Solubility of propylene polymers in xylene at 25°C: Place 2.5 g of polymer sample and 250 ml of xylene in a glass flask equipped with a refrigerator and magnetic stirrer. The temperature is increased to 135°C over 30 minutes. The resulting clear solution is stirred under reflux for an additional 30 minutes. The solution is cooled in two stages. In the first stage, the temperature is decreased to 100°C in air over 10-15 minutes with stirring. In the second stage, the flask is transferred to a thermostatically controlled water bath at 25°C for 30 minutes. The temperature is decreased to 25°C without stirring for the first 20 minutes, and maintained at 25°C for the last 10 minutes with stirring. The formed solid is filtered through fast-drying filter paper (e.g., Whatman filter paper grade 4 or 541). 100 ml of the filtered solution (S1) is poured into a pre-weighed aluminum container and heated to 140°C on a heating plate under a nitrogen stream to evaporate off the solvent. The container is then placed in an oven at 80°C under vacuum until the weight becomes constant. The amount of polymer that dissolves in xylene at 25°C is then calculated. The XS(I) and XSA values ​​are determined experimentally. The proportion of component (B) that dissolves in xylene at 25°C (XSB) can be calculated using the following formula: XS = W(A) × (XS A ) + W(B) × (XS B ) where W(A) and W(B) are the relative amounts of components (A) and (B), respectively, and W(A)+W(B)=1.

[0051] Hexene content of propylene-hexene copolymer by NMR: 13 C NMR spectra are obtained on an AV-600 spectrometer operating at 150.91 MHz in Fourier transform mode at 120 °C. The propylene C-H peak is used as an internal reference at 28.83. 13 C NMR spectra are acquired using the following parameters:

[0052] [Table 1]

[0053] The total amount of 1-hexene, as a mole percent, is calculated from diad using the following relationship: [P]=PP+0.5PH [H]=HH+0.5PH

[0054] Propylene / 1-hexene copolymer 13 C NMR spectral assignments are calculated according to the following table:

[0055] [Table 2]

[0056] Ethylene content of propylene-ethylene copolymer by NMR: 13 C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with a cryoprobe operating at 160.91 MHz in Fourier transform mode at 120 °C. The peak of the Sββ carbon ( 13 C Monomer sequence distribution of ethylene propylene rubber measured by NMR. "3. Using Reaction Probability Mode," CJ Carman, RA Harrington, and CE Wilkes, Macromolecules, 1977, 10, 536 (nomenclature according to the methodology) is used as the internal reference at 29.9 ppm. Samples are dissolved in 1,1,2,2-tetrachloroethane-d2 at 120 °C, with a concentration of 8% wt / v. Each spectrum is acquired using a 90° pulse, a 15-second delay between pulses, and CPD to remove 1H-13C coupling. 512 transients are saved to 32K data points using a 9000 Hz spectral window. Spectral assignments, evaluation of triad distributions, and compositions are performed according to Kakugo ("Carbon-13 NMR Measurement of Monomer Sequence Distribution in Ethylene-Propylene Copolymers Prepared with δ-Titanium Trichloride-Diethylaluminum Chloride," M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 1982, 15, 1150) using the following equation: PPP=100Tββ / S PPE=100Tβδ / S EPE=100Tδδ / S PEP=100Sββ / S PEE=100Sβδ / S EEE=100(0.25 Sγδ+0.5 Sδδ) / S S=Tββ+Tβδ+Tδδ+Sββ+Sβδ+0.25 Sγδ+0.5 Sδδ

[0057] The mole percentage of ethylene content is estimated using the following formula: E%mol=100*[PEP+PEE+EEE]

[0058] The weight percentage of ethylene content is estimated using the following formula:

[0059]

number

[0060] where P%mol is the molar percentage of propylene content and MW E and M.W. P are the molecular weights of ethylene and propylene, respectively.

[0061] The product of the reactivity ratios r1r2 is calculated according to Carman (CJ Carman, RA Harrington and CE Wilkes, Macromolecules, 1977; 10, 536) as follows:

number

[0062] The stereoregularity of the propylene sequence is PPP mmT ββ (28.90-29.65 ppm) and overall T ββ The content is calculated as mm from the ratio (29.80 to 28.37 ppm).

[0063] Hexene and ethylene content of propylene-hexene-ethylene terpolymer: 13 C NMR spectra are acquired on an AV-600 spectrometer operating at 120 °C, in Fourier transform mode, and at 150.91 MHz. The propylene C peak at 28.83 is used as an internal reference. 13 C NMR spectra are acquired using the following parameters: Spectral width (SW): 60 ppm Spectral center (O1): 30 ppm Decoupling sequence: WALTZ 65_64pl Pulse Program (1): ZGPG Pulse length (P1)(2): 90° Total score (TD): 32K Relaxation Delay (2): 15 seconds Number of transients (3): 1500

[0064] The total amount of 1-hexene and ethylene, as a mole percent, is calculated from the dyad using the following relationship: [P]=PP+0.5PH+0.5PE [H]=HH+0.5PH [E]=EE+0.5PE

[0065] Propylene / 1-hexene / ethylene copolymer 13 The C NMR spectral assignments are calculated according to the following table:

[0066] [Table 3]

[0067] Comonomer content of polybutene: 13 C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with a cryoprobe operating in Fourier transform mode at 120 °C. Samples were dissolved in 1,1,2,2-tetrachloroethane-d2 at 8% wt / v concentration at 120 °C. Each spectrum was acquired with a 90° pulse and a 15-second delay between the pulse and the CPD to remove 1H-13C coupling. The spectrometer was operated at 160.91 MHz. The Sδδ carbon peak (" 13 Monomer sequence distribution of ethylene propylene rubber by C NMR. 3. Using reaction probability mode" by CJ Carman, RA Harrington and CE Wilkes, Macromolecules, 1977, 10, 536. An internal reference at 29.9 ppm was used, and 512 transients were saved to 32K data points using a 9000 Hz spectral window.

[0068] Spectral assignments, triad distribution evaluations, and compositions are determined using the following formulas according to Kakugo [M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 16, 4, 1160 (1982)] and Randall [J.C. Randall, Macromol. Chem Phys., C30, 211 (1989)]: BBB=100T ββ / S BBE=100T βδ / S EBE=100P δδ / S BEB=100S ββ / S BEE=100S αδ / S EEE=100(0.25 S γδ +0.5 S δδ ) / S S=T ββ +T βδ +P δδ +S ββ +S αδ +0.25 S γδ +0.5 S δδ

[0069] The total amount of 1-butene and ethylene (in mole percent) is calculated from the triad using the following relationship: [E]=EEE+BEE+BEB [B]=BBB+BBE+EBE

[0070] The weight percentage of ethylene content (E %wt) is calculated using the following formula:

[0071]

number

[0072] Molecular weight distribution Mw / Mn: Measurements of the average Mn and Mw, and the resulting Mw / Mn, are carried out using a Waters GPCV 2000 instrument equipped with a column set of four PLgel Olexis mixed gels (Polymer Laboratories) and an IR4 infrared detector (Polymer Char). The column dimensions are 300 (7.5 mm) and the particle size is 13 μm. The mobile phase is 1,2,4-trichlorobenzene (TCB), the flow rate is kept at 1.0 ml / min, and all measurements are performed at 150 °C. The solution concentration is 0.1 g / dL in TCB, and 0.1 g / L of 2,6-ditert-butyl-p-cresol is added to prevent decomposition. For GPC calculations, a universal calibration curve is obtained using 10 polystyrene (PS) standard samples (peak molecular weight range: 580–8,500,000) provided by Polymer Laboratories. The experimental data are interpolated and a third-order polynomial fit is used to obtain the relevant calibration curve. Data acquisition and processing are performed using Empower (Waters). The Mark-Houck relationship is used to determine the molecular weight distribution and the associated average molecular weight. The K values ​​are KPS = 1.21 (10) for PS and PB, respectively. -4 dL / g and KPB = 1.78(10 -4 The Mark-Houwink exponent is α = 0.706 for PS and α = 0.725 for PB. For butene-1 / ethylene copolymers, the data evaluation assumes a constant composition over the entire range of molecular weights, and the K value of the Mark-Houwink relationship is calculated using a linear combination as shown below:

[0073]

number

[0074] Melting point: Measured according to the method of ISO 11357-3:2018. Polypropylene and polypropylene compositions The scanning speed during cooling and heating was 20°C / min under a nitrogen flow, with a sample weight of 5-7 mg. The instrument was calibrated using indium. Polybutene To measure the melting point (Tm(I)) of polybutene crystalline form I, a sample is melted and held at 200°C for 5 minutes, then cooled to 20°C at a cooling rate of 10°C / min, and then stored at room temperature for 10 days. After 10 days, the sample is subjected to DSC, cooled to -20°C, and then heated to 200°C at a scan rate of 10°C / min. In this heating experiment, the first peak temperature from the low temperature side of the thermogram is taken as the melting point Tm(I).

[0075] Flexural modulus: is determined according to method ISO 178:2010 on injection-molded specimens (80 x 10 x 4 mm) (obtained according to ISO 1873-2:2007) for propylene polymers and on compression-molded specimens for butene polymers. Specimens for butene copolymers are conditioned for 10 days at 23°C before testing.

[0076] Preparation of BOPP film specimens: Each test composition was extruded using a single-screw Corin extruder (screw length / diameter ratio 1:25) at a film drawing speed of 7 m / min and a melt temperature of 210-250 °C to prepare a 50 μm-thick film. Each film was then superimposed on a 1000 μm-thick film of propylene homopolymer with a xylene insoluble content of 97 wt% and a MFR (ISO 1133-1:2011, 230 °C / 2.16 kg) of 2.0 g / 10 min. The superimposed film was then placed on a 35 kg × cm 2The laminates are bonded to each other by a flat press at 200°C under a load of 0.05g and maintained in this state for 5 minutes. The resulting laminate is stretched 7 times simultaneously in the machine and transverse directions, i.e., biaxially, at 160°C using a Karo 4 Brueckener film stretcher to obtain a 20 μm thick BOPP film (18 μm homopolymer + 2 μm test composition).

[0077] Seal initiation temperature for BOPP film: A 6 cm wide, 35 cm long film strip is cut from the center of a BOPP film and overlapped with a PP homopolymer BOPP film. The overlapped specimen is sealed along one of the 2 cm edges using a Brugger Feinmechanik Sealer, Model HSG-ETK745. The seal time is 5 seconds at 20 psi (0.14 MPa) pressure. The seal initiation temperature is approximately 10°C below the melting point of the test composition. The sealed strip is cut into six 15 mm wide specimens long enough to fit into the grips of a tensile tester. Seal strength is tested using a load cell capacity of 100 N, a cross speed of 100 mm / min, and a grip distance of 50 mm. Results are expressed as the average of the maximum seal strength (N). The specimen is then cooled, after which the unsealed end is attached to an Instron machine and tested at a pull speed of 50 mm / min.

[0078] The test is then repeated at the following temperature changes:

[0079] If the seal strength is less than 1.5N, increase the temperature.

[0080] If the seal strength exceeds 1.5N, reduce the temperature.

[0081] The temperature change should be adjusted in steps, with 1°C steps selected if the seal strength is close to the target, and 2°C steps selected if the seal strength is far from the target.

[0082] The target seal strength (SIT) is defined as the lowest temperature at which a seal strength of 1.5 N or greater is achieved.

[0083] raw materials

[0084] Irganox 1010 : Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), sold by BASF.

[0085] Irgafos168 : Tris(2,4-di-tert-butylphenyl)phosphite, sold by BASF.

[0086] PB1(B) A copolymer of butene-1 and ethylene with an ethylene content of 3.5 wt%, a Tm(I) of 94°C, a molecular weight distribution Mw / Mn of 5.6, a melt flow rate of 3.1 g / 10 min (ISO 1133-1:2011, 190°C / 2.16 kg), and a flexural modulus (ISO 178:2010) of 120 MPa was obtained by sequential polymerization in two reactors using butene-1 as the liquid medium and a Ziegler-Natta catalyst system according to Example 11 of patent WO 2004 / 048424. The polymerization conditions in the first reactor were a temperature of 75°C and a hydrogen / butene feed ratio of 1000 ppmV. After 2.5 hours, the contents of the first reactor were transferred to the second reactor, and the copolymerization continued under the same conditions except that the ethylene feed was discontinued. The polymerization was terminated after 2 hours.

[0087] PB2(B) : A copolymer of butene-1 and ethylene with an ethylene content of 3.5% by weight, a Tm(I) of 65°C, a molecular weight distribution Mw / Mn of 2.2, a melt flow rate of 3.3 g / 10 min (ISO 1133-1:2011, 190°C / 2.16 kg), and a flexural modulus (ISO 178:2010) of 130 MPa.

[0088] Propylene polymer (A)

[0089] Preparation procedure for spherical adduct: Microspherical MgCl2·pC2H5OH adduct is prepared according to the method described in Comparative Example 5 of WO98 / 44009, except that powdered BiCl3 is added in an amount of 3 mol % relative to magnesium before feeding the oil.

[0090] Preparation procedure for the solid catalyst component: The solid catalyst component is prepared according to Example 1 of EP728769, except as follows.

[0091] The second and third titanations are carried out at 110°C (instead of 120°C).

[0092] -MgCl in the form of spherical solid particles with a maximum diameter of 65 microns or less (instead of 50 microns) 2.3 ·C2H5OH is used.

[0093] Catalyst system and prepolymerization treatment: Before being introduced into the polymerization reactor, the above solid catalyst components are contacted with aluminum triethyl (TEAL) and dicyclopentyldimethoxysilane (DCPMS) as external donors at 15° C. for about 6 minutes.

[0094] The catalyst system is then prepolymerized by keeping it suspended in liquid propylene at 20° C. for about 20 minutes, before being introduced into the polymerization reactor.

[0095] Polymerization: A propylene-hexene copolymer (component (a)) is produced by continuously supplying a prepolymerized catalyst system, hydrogen, propylene, and 1-hexene in a gaseous state at a constant flow rate to a first gas-phase polymerization reactor. The propylene copolymer produced in the first reactor is discharged as a continuous flow and introduced into a second gas-phase polymerization reactor as a continuous flow together with quantitatively constant flows of gaseous hydrogen, hexene, ethylene, and propylene. The propylene terpolymer produced in the second reactor is discharged as a continuous flow and, after removal of unreacted monomers, introduced into a third gas-phase polymerization reactor as a continuous flow together with quantitatively constant flows of gaseous hydrogen, hexene, and propylene. The polymerization conditions are shown in Table 1.

[0096] Table 1 [Table 4]

[0097] The polymers obtained from the polymerization experiments were pelletized with 0.05 wt% Irganox 1010, 0.1 wt% Irgafos 168, and 0.05% calcium stearate, where the amounts of additives are based on the total weight of the polymer including the additives. Table 2 shows the characteristics of the propylene polymers.

[0098] Table 2 [Table 5]

[0099] Examples E1 to E3

[0100] Propylene polymer (A) and polybutene (B) are melt-mixed in the proportions shown in Table 3 in a twin-screw extruder (Werner 58, model WPZSK-58) with a rotation speed of 220 rpm and an extruder output of 220 kg / h.

[0101] The thermal and sealing properties of the polypropylene compositions are shown in Table 3. The polypropylene compositions also showed significantly lower fisheye counts on the cast films.

[0102] Table 3 [Table 6]

Claims

1. A polypropylene composition (I), (A) at least 90.0 wt. % propylene polymer (based on the weight of (a) + (b) + (c)): (a) 20% to 44% by weight of a propylene-hexene copolymer containing 5.0% to 8.3% by weight of hexene-derived units, based on the weight of component (a), and having a melt flow rate (MFR(a)) in the range of 3.5 to 8.5 g / 10 min, as measured in accordance with ISO 1133-1:2011 (230°C / 2.16 kg); (b) 25% to 45% by weight of a propylene-hexene-ethylene terpolymer comprising 7.2% to 12.0% by weight of units derived from hexene and 0.5% to 2.5% by weight of units derived from ethylene, wherein the melt flow rate (MFR(a+b)) of components a)+b) measured in accordance with ISO 1133-1:2011 (230°C / 2.16 kg) is in the range of 3.5 to 8.5 g / 10 min; (c) contains 3.5 wt% to 8.7 wt% ethylene-derived units; 25% to 50% by weight of a propylene-ethylene copolymer, wherein the melt flow rate of components (a)+(b)+(c) is in the range of 3.5 to 12.0 g / 10 min, measured in accordance with ISO 1133-1:2011 (230°C / 2.16 kg); The propylene polymer (A) is (i) a xylene solubles at 25°C in the range of 13.0% to 25.0% by weight, based on the weight of (a) + (b) + (c); and (ii) the propylene polymer having a melting point in the range of 122°C to 132°C; (B) 10.0 wt. % or less of polybutene selected from butene homopolymers, butene copolymers containing 5.0 wt. % or more of units derived from ethylene and / or propylene, based on the weight of component (B), and mixtures thereof; The amount of (A) and (B) is based on the total weight of (A) + (B).

2. - at least 90.0 wt. %, preferably 90.0 wt. % to 99.5 wt. %, more preferably 93.0 wt. % to 99.0 wt. %, and even more preferably 95.0 wt. % to 98.0 wt. % of the propylene polymer (A); -10.0 wt% or less, preferably 0.5 wt% to 10.0 wt%, more preferably 1.0 wt% to 7.0 wt%, and even more preferably 2.0 wt% to 5.0 wt% of polybutene; The polypropylene composition (I) according to claim 1, wherein the amount of (A) and (B) is based on the total weight of (A) + (B).

3. The propylene polymer (A) is (based on the weight of the (a) + the (b) + the (c)) (a) 20% to 44%, preferably 27% to 40%, and more preferably 29% to 35%, by weight of a propylene-hexene copolymer, based on the weight of said component (a); - contains from 5.0% to 8.3%, preferably from 6.3% to 7.8%, more preferably from 6.5% to 7.4% by weight of hexene-derived units, based on the weight of said component (a); said propylene-hexene copolymer having a melt flow rate (MFR(a)), measured according to ISO 1133-1:2011 (230°C / 2.16 kg), ranging from 3.5 to 8.5 g / 10 min, preferably from 4.4 to 8.0 g / 10 min, more preferably from 5.0 to 7.0 g / 10 min; (b) 25% to 45%, preferably 35% to 40%, more preferably 36% to 39%, by weight of a propylene-hexene-ethylene terpolymer; - 7.2% to 12.0% by weight, preferably 7.5% to 9.5% by weight, more preferably 8.2% to 9.1% by weight of hexene-derived units, and - 0.5% to 2.5% by weight, preferably 0.7% to 2.2% by weight, more preferably 0.8% to 2.0% by weight of units derived from ethylene, where: the melt flow rate (MFR(a+b)) of components (a)+(b), measured according to ISO 1133-1:2011 (230°C / 2.16 kg), is in the range of 3.5 to 8.5 g / 10 min, preferably 4.4 to 8.0 g / 10 min, more preferably 5.0 to 7.0 g / 10 min, the propylene-hexene-ethylene terpolymer, wherein the amount of hexene and ethylene is based on the weight of (b); (c) 25% to 50%, preferably 27% to 40%, more preferably 29% to 35%, by weight of a propylene-ethylene copolymer; - the propylene-ethylene copolymer comprising 3.5% to 8.7% by weight, preferably 4.5% to 8.4% by weight, of units derived from ethylene, based on the weight of (c), where: the melt flow rate of said components (a)+(b)+(c), measured according to ISO 1133-1:2011 (230°C / 2.16 kg), is in the range of from 3.5 to 12.0 g / 10 min, preferably from 4.4 to 8.0 g / 10 min, more preferably from 5.0 to 8.5 g / 10 min; The propylene polymer (A) is (ii) a xylene solubles content at 25°C in the range of 13.0 wt% to 25.0 wt%, preferably 14.0 wt% to 23.0 wt%, more preferably 15.0 wt% to 20.0 wt%, and (ii) The polypropylene composition (I) according to claim 1 or 2, having a melting point of 122°C to 132°C, preferably 125°C to 131°C, more preferably 126°C to 130°C.

4. The polypropylene composition (I) according to any one of claims 1 to 3, wherein the component (B) is a butene-ethylene copolymer.

5. The polypropylene composition (I) according to claim 4, wherein said component (B) is a butene-ethylene copolymer having at least one, preferably all, of the following properties: the content of ethylene-derived units is in the range of 1.0% by weight to 4.5% by weight, preferably 1.5% by weight to 4.5% by weight, more preferably 2.0% by weight to 4.0% by weight, and even more preferably 2.5% by weight to 3.5% by weight, based on the weight of (B); and / or the melting point Tm(I) of Form I, measured by DSC according to the ISO 11357-3:2018 method, is less than 100°C, preferably in the range of from 80°C to less than 100°C, more preferably in the range of from 90°C to 97°C; and / or a melt flow rate, measured according to ISO 1133-1:2011 (190°C / 2.16 kg), in the range of 1.0 to 6.0 g / 10 min, preferably 2.0 to 5.0 g / 10 min, more preferably 3.0 to 4.5 g / 10 min; and / or - A flexural modulus measured according to ISO 178:2010 of at least 80 MPa, preferably in the range of 80 to 250 MPa, more preferably 100 to 210 MPa.

6. The polypropylene composition (I) according to any one of claims 1 to 5, further comprising at least one additive (C) selected from the group consisting of a nucleating agent, an antistatic agent, an antioxidant, a light stabilizer, a slip agent, an antacid, a melt stabilizer, and combinations thereof in an amount of 5.0 wt% or less, more preferably 0.01 wt% to 5.0 wt%, wherein the amount of the additive is based on the total weight of the polypropylene composition (I) including the additive.

7. Polypropylene composition (I) according to any one of claims 1 to 6, having at least one, preferably all, of the following properties: - a seal initiation temperature (SIT) measured on the BOPP film in the range of 70°C to 85°C, more preferably 72°C to 83°C; and / or The value of -ΔTm-SIT is in the range of 40.0°C to 60.0°C, preferably 45.0°C to 55°C, where Tm is the melting point of the polypropylene composition (I) and SIT is the seal initiation temperature measured on a BOPP film.

8. A film or sheet comprising the polypropylene composition (I) according to any one of claims 1 to 7.

9. 9. The film or sheet of claim 8, wherein the film or sheet is multi-layered and the polypropylene composition (I) is contained in at least one skin layer.

10. 10. The film or sheet of claim 8 or 9, wherein the film is a cast film or a BOPP film.

Images