Random propylene-1-butene copolymers

Abstract

A random propylene 1-butene copolymers characterized by the following features: - Melt Flow Rate (MFR 230°C 2,16kg) ranging from 2.0 g / 10 min to 35 g / 10 min; - 1-butene derived units, measured by 13C-NMR content of between 4.2 wt% and 15.5 wt%; - 1-butene derived units content of the fraction insoluble in xylene at 25°C, measured by 13C- NMR ranging from 3.9 wt% to 15.0 wt%; - 1-butene derived unit of the fraction soluble in xylene at 25°C, measured by 13C-NMR ranging from 17.0 wt% to 24.0 wt%; - - molecular weight distribution (MWD), expressed in terms of Mw / Mn, greater than 6.7; - the difference between the melting point and the crystallization temperature, Tm-Tc, being lower than 46.0.

Description

RANDOM PROPYLENE-l-BUTENE COPOLYMERSFIELD OF THE INVENTION

[0001] The present disclosure relates to random propylene / 1 -butene copolymers especially fit for the production of films, in particular metallized films having excellent properties in terms of mechanical properties.BACKGROUND OF THE INVENTION

[0002] Random copolymers of propylene 1 -butene are widely used in the production of various types of films. These copolymers offer a unique combination of properties that make them suitable for specific film applications.

[0003] Random copolymers of propylene 1 -butene are widely used in the production of various types of films. These copolymers offer a unique combination of properties that make them suitable for specific film applications. Random copolymers of propylene 1 -butene can be formulated to create specialty films tailored to specific requirements. For example, they can be modified to enhance puncture resistance, tear strength, or heat-sealing capabilities, depending on the desired application. These films find use in various industries, including medical packaging, hygiene products, and electronics.

[0004] W02020 / 099566 relates to a multimodal propylene 1 -butene rando copolymer having a 1 -butene content ranging from 1.5 and 8.0 wt% being obtained with metallocene based catalyst fit for films.SUMMARY OF THE INVENTION

[0005] Now it has surprisingly been found improved random propylene / 1 -butene copolymers, obtained by heterogeneous catalysts, having broad distribution of molecular weight and high crystallization temperature and good mechanical properties.

[0006] The random propylene 1 -butene copolymers of the present disclosure are characterized by the following features:Melt Flow Rate (MFR 230°C 2,16kg) ranging from 2.0 g / 10 min to 35 g / 10 min;1 -butene derived units , measured by13C-NMR content of between 4.2 wt% and 15.5 wt%;1 -butene derived units content of the fraction insoluble in xylene at 25°C, measured by13C-NMR ranging from 3.9 wt% to 15.0 wt%;1 -butene derived unit of the fraction soluble in xylene at 25°C, measured by13C-NMR ranging from 17.0 wt% to 24.0 wt%;The 1 -butene sequence PB, measured by13C-NMR ranging from 10.0 mol% to 16.0 mol%;The 1 -butene sequence PB of the fraction soluble in xylene at 25°C, measured by13C- NMR ranging from 22.0 mol% to 28.5 mol%; molecular weight distribution (MWD), expressed in terms of Mw / Mn, greater than 6.7; the difference between the melting point and the crystallization temperature, Tm-Tc, being lower than 46.0.DETAILED DESCRIPTION OF THE INVENTION

[0007] The random propylene 1 -butene copolymers of the present disclosure are characterized by the following features:Melt Flow Rate (MFR 230°C 2,16kg) ranging from 2.0 g / 10 min to 35 g / 10 min; preferably from 5.2 g / 10 min to 25.4 g / 10 min, more preferably from 8.3 g / 10 min to 18.3 g / 10 min;1 -butene derived units , measured by13C-NMR content of between 4.2 wt% and 15.5 wt%; preferably comprised between 6.4 wt% and 13.5 wt% more preferably comprised between 8.3 wt% and 11.5 wt%;1 -butene derived units content of the fraction insoluble in xylene at 25°C, measured by 13C-NMR ranging from 3.9 wt% to 15.0 wt%; preferably comprised between 6.1 wt% and 12.6 wt% more preferably comprised between 8.2 wt% and 11.3 wt%1 -butene derived unit of the fraction soluble in xylene at 25°C, measured by13C-NMR ranging from 17.0 wt% to 24.0 wt%; preferably ranging from 18.0 wt% to 23.0 wt%; more preferably ranging from 19.0 wt% to 21.5 wt%The 1-butene sequence PB, measured by13C-NMR ranging from 10.0 mol% to 16.0 mol%; preferably from 11.0 mol% to 15.0 mol%; more preferably from 11.5 mol% to 14.2 mol%;The 1-butene sequence PB of the fraction soluble in xylene at 25°C, measured by13C- NMR ranging from 22.0 mol% to 28.5 mol%; preferably from 23.2 mol% to 27.7 mol%; more preferably from 24.2 mol% to 26.5 mol%;molecular weight distribution (MWD), expressed in terms of Mw / Mn, greater than 6.7; preferably greater than 7.2; more preferably greater than 7.5, the highest value being preferably 15 ; the difference between the melting point and the crystallization temperature, Tm-Tc, being lower than 46.0; preferably lower than 45.0; more preferably lower than 44.0; the lowest value being preferably 35.

[0008] The propylene 1 -butene copolymer of the present disclosure is defined as containing only propylene and 1 -butene comonomers.

[0009] The term random in the present disclosure has to be intended as a copolymer having a 1 -butene sequence PB, measured by13C-NMR lower than 20 mol%.

[0010] The propylene 1 -butene copolymer of the present disclosure is particularly fit for the production of films such as cast, BOPP and blow film. In particular the propylene 1 -butene copolymer of the present disclosure is fit for the production of metallized film. In particular the dart impact test measured on 50 pm cast film measured according to ASTM D 1709 is higher than 115 g; preferably higher than 120 g; more preferably higher than 148 g, the highest value being preferably 1000 g.. The puncture test measured on a on 50 pm cast film of at least 12.2 N ; preferably at least 12.5 N; more preferably at least 13.0 N the highest value being preferably 50 N (ASTM D 5748).

[0011] Preferably the fraction soluble in xylene at 25°C of the random propylene 1 -butene copolymer of the present disclosure ranges from 2.1 wt% to 7.2 wt%; preferably from 2.5 wt% to 6.0 wt%, more preferably from 2.8 wt% to 5.0 wt%.

[0012] The propylene 1 -butene copolymer herein disclosed is obtainable by a process comprising polymerizing propylene with 1 -butene, in the presence of a solid catalyst component for the polymerization of olefins comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least an electron donor of formula (I)in which R1and R2are, independently, C1-C5 alkyl groups, X is Si or C, R3and R4groups, independently, are selected from hydrogen, C1-C10 hydrocarbon groups and halogens with the proviso that at least two R3are not hydrogen.

[0013] Preferably, R1and R2are the same and are selected from C1-C4 linear or branched alkyl groups and more preferably from methyl groups.

[0014] Preferably, R4groups, independently, are selected from hydrogen, C1-C4 linear or branched alkyl groups and halogens. More preferably, only one or two of R4groups are C1-C4 linear or branched alkyl groups or halogen. Preferred alkyl groups are methyl, isopropyl or t-butyl, while preferred halogens are Cl and F. The structures in which all R4groups are hydrogen are also preferred.

[0015] When R3is a hydrocarbon group it is preferably selected from C1-C4 linear or branched alkyl groups and more preferably from methyl groups.

[0016] When R3is a halogen it is preferably selected from Cl and F. More preferably it is F.

[0017] According to a preferred embodiment, X is carbon and R3is a hydrogen or hydrocarbon group preferably selected from C1-C4 linear or branched alkyl groups more preferably from methyl. Most preferred are the structures in which one R3is selected from hydrogen and the remaining two from methyl groups.

[0018] Another group of preferred structures are those in which X is carbon and R3is hydrogen or a halogen group preferably selected from Cl and F more preferably from F. Most preferred are the structures in which at least two of R3are selected from F and more preferably those in which all the R3groups are F.According to another preferred embodiment, X is Si and R3is a hydrogen or hydrocarbon grouppreferably selected from C1-C4 linear or branched alkyl groups more preferably from methyl or ethyl. Most preferred are the structures in which all R3groups are selected from methyl.Preferably the electron donor of formula (I) is 2-cyclohexyl-2-isopentyl-l,3-dimethoxypropane; or 2- cyclohexyl-2-(3 ,3 ,3 -trifluoro-n-propyl)- 1 ,3 -dimethoxypropane.By using the described catalyst component is possible to obtain The propylene ethylene copolymer herein disclosed having the reported particular properties.

[0019] The preparation of the solid catalyst component can be carried out according to several methods.According to one method the solid catalyst component can be prepared by reacting a titanium compound of formula Ti(OR)q-yXy, where q is the valence of titanium and y is a number between 1 and q, preferably TiCh, with a magnesium chloride deriving from an adduct of formula MgCh’pROH, where p is a number between 0.1 and 6, preferably from 2 to 3.5, and R is a hydrocarbon radical having 1-18 carbon atoms. The adduct can be suitably prepared in spherical form by mixing alcohol and magnesium chloride, operating under stirring conditions at the melting temperature of the adduct (100-130°C). Then, the adduct is mixed with an inert hydrocarbon immiscible with the adduct thereby creating an emulsion which is quickly quenched causing the solidification of the adduct in form of spherical particles. Examples of spherical adducts prepared according to this procedure are described in USP 4,399,054 and USP 4,469,648. The so obtained adduct can be directly reacted with Ti compound or it can be previously subjected to thermal controlled dealcoholation (80-130°C) so as to obtain an adduct in which the number of moles of alcohol is generally lower than 3, preferably between 0.1 and 2.5. The reaction with the Ti compound can be carried out by suspending the adduct (dealcoholated or as such) in cold TiCh (generally 0°C); the mixture is heated up to 80-130°C and kept at this temperature for 0.5-2 hours. The treatment with TiCh can be carried out one or more times. The electron donor compound can be added in the desired ratios during the treatment with TiCk

[0020] Suitable external electron-donor compounds include silicon compounds, ethers, esters, amines, heterocyclic compounds and particularly 2,2,6,6-tetramethylpiperidine and ketones.

[0021] A preferred class of external donor compounds is that of silicon compounds of formula (R6)a(R7)bSi(ORs)c, where a and b are integers from 0 to 2, c is an integer from 1 to 4 and the sum (a+b+c) is 4; Re, R7, and Rs, are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms optionally containing heteroatoms. Particularly preferred are the silicon compounds in which a is 1, b is 1, cis 2, at least one of Rs and R7 is selected from branched alkyl, cycloalkyl or aryl groups with 3-10 carbon atoms optionally containing heteroatoms and Rs is a C1-C10 alkyl group, in particular methyl. Examples of such preferred silicon compounds are methylcyclohexyldimethoxysilane (C donor), diphenyldimethoxysilane, methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane (D donor), diisopropyldimethoxysilane, (2-ethylpiperidinyl)t-butyldimethoxysilane, (2- ethylpiperidinyl)thexyldimethoxysilane, (3,3,3-trifluoro-n-propyl)-(2-ethylpiperidinyl)- dimethoxysilane, methyl(3,3,3-trifluoro-n-propyl)dimethoxysilane. Moreover, the silicon compounds in which a is 0, c is 3, R7 is a branched alkyl or cycloalkyl group, optionally containing heteroatoms, and Rs is methyl are also preferred. Examples of such preferred silicon compounds are cyclohexyltrimethoxysilane, t-butyltrimethoxysilane and thexyltrimethoxysilane.

[0022] The electron donor compound (iii) is used in such an amount to give a weight ratio between the organoaluminum compound and said electron donor compound (iii) of from 2.5 to 500, preferably from 3 to 300 and more preferably from 3.5 to 100.

[0023] The polymerization process can be carried out according to known techniques for example slurry polymerization using as diluent an inert hydrocarbon solvent, or bulk polymerization using the liquid monomer (for example propylene) as a reaction medium. Moreover, it is possible to carry out the polymerization process in gas-phase operating in one or more fluidized or mechanically agitated bed reactors.

[0024] The polymerization is generally carried out at temperature of from 20 to 120°C, preferably of from 40 to 80°C. When the polymerization is carried out in gas-phase the operating pressure is generally between 0.5 and 5 MPa, preferably between 1 and 4 MPa. In the bulk polymerization the operating pressure is generally between 1 and 8 MPa, preferably between 1.5 and 5 MPa. Hydrogen is typically used as a molecular weight regulator.

[0025] The following examples are given in order to better illustrate the invention and are not intended to limit it in any way.EXAMPLESDetermination of X.LThe Xylene Soluble fraction was measured according to ISO 16152, 2005 %Molecular weight distribution (Mw / Mn)Molecular weights and molecular weight distribution were measured at 150°C using a Waters Alliance GPCV / 2000 instrument equipped with four mixed-bed columns PLgel Olexis having a particle size of 13 pm. The dimensions of the columns were 300 x 7.8 mm. The mobile phase used was vacuum distilled 1, 2, 4-tri chlorobenzene (TCB) and the flow rate was kept at 1.0 ml / min. The sample solution was prepared by heating the sample under stirring at 150°C in TCB for one to two hours. The concentration was 1 mg / ml. To prevent degradation, 0.1 g / 1 of 2,6-di- / c / 7-butyl- / ?-cresol were added. 300 pl (nominal value) of solution were injected into the column set. A calibration curve was obtained using 10 polystyrene standard samples (EasiCal kit by Agilent) with molecular weights in the range from 580 to 7 500000. It was assumed that the K values of the Mark-Houwink relationship were:K = 1.21 x 10'4dl / g and a = 0.706 for the polystyrene standards, K= 1.90 x 10'4dl / g and a = 0.725 for the experimental samples. A third order polynomial fit was used for interpolate the experimental data and obtain the calibration curve. Data acquisition and processing was done by using Waters Empowers 3 Chromatography Data Software with GPC option.Melt flow rate (MIL)The melt flow rate MIL of the polymer was determined according to ISO 1133 (230°C, 2.16 Kg).Melting temperature (Tm) and crystallization temperature (Tc) via Differential Scanning Calorimetry (DSC)

[0026] .Measured according to ISO 11357-3, at scanning rate of 20°C / min both in cooling and heating, on a sample of weight between 5 and 7 mg., under inert N2 flow. Instrument calibration made with Indium.Flexural modulusFlexural Modulus is measured according to ISO 178, and supplemental conditions according to ISO 1873-2.Charpy impact test at 23°CCharpy impact test measured according to ISO 179-leA, e ISO 1873-2.Head deflection temperature (HDT) measured at 0.45 MPa according to ASTM D 648.Dart impact test measured on a 50 pm cast film measured according to ASTM D 1709.ElmendorfMeasured on 50 m cast film, in the machine direction according to ASTM 1922The puncture test measured on a on 50 pm cast film according to ASTM D 574813C NMR OF PROPYLENE 1BUTENET COPOLYMER13C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with cryoprobe, operating at 160.91 MHz in the Fourier transform mode at 120°C.The peak of the Ppp carbon (nomenclature according to C. J. Carman, R. A. Harrington and C. E. Wilkes, Macromolecules, 10, 3, 536 (1977)) was used as internal reference at 21.8 ppm. The samples were dissolved in 1 , 1 ,2,2-tetrachloroethane-<72 added with 0.1 mg / ml of Irganox 1010 (AO 1010) as antioxidant at 120°C with a 8 % wt / v concentration. Each spectrum was acquired with a 90° pulse, 15 seconds of delay between pulses and CPD to removeJH-13C coupling. 512 transients were stored in 32K data points using a spectral window of 9000 Hz.The assignments of the spectra was made according to Cheng [H.N. Cheng, Journal of Polymer Science, Polymer Physics Edition, 21, 573 (1983))]Composition was obtained from diad distribution (possible overlaps of the AO1010 peaks were taken into account) calculated as follow:PP = 100 Ii / SPB = 100 I2 / SBB = 100 E / SWhere S= 11+ 12+ 13 and I are the areas of the peaks reported in table 1Molar composition was calculated from triad distribution as:B(m%)= BB+0.5PBP(m%)= PP+0.5 PBMolar composition was used to calculate weight composition using monomers molecular weights.Table A: assignments of Sococ carbons in C3C4 copolymersCatalyst systemThe catalyst used in examples is described in example 16 of PCT / EP2023 / 068696.Propylene / 1 butene copolymerization Example 1Prepolymerization treatment

[0027] Before introducing it into the polymerization reactors, the solid catalyst component described above have been contacted with triethyl aluminum (TEAL) and i-cyclopentyldimethoxy silane (donor D) in a ratio reported on table 1.. Then the resulting mixture is subjected to prepolymerization by maintaining it in suspension in liquid propylene at 20 °C for about 5 minutes before introducing it into the polymerization reactor.Polymerization

[0028] Copolymer are prepared by polymerising propylene and 1 -butene in the presence of the catalyst described above in continuous in loop reactor under the conditions reported in Table 1 After the reported polymerization time the polymer obtained is discharged from the reactor, separated from the unreacted monomer and dried. The so obtained polymer was then pelletized and subject to mechanical measurements. The polymerization data are reported on table 1, the characterization of the copolymer are reported on table 2 and table 3 reports13C NMR data of the copolymer of example 1Table 1C4= 1-butene; C3=propylene; H2=hydrogenTable 2Comparative exampel 2 is RC213M a commercial grade sold by LyondellbasellTable 3

Claims

CLAIMSWhat is claimed is:

1. A random propylene 1 -butene copolymer characterized by the following features:Melt Flow Rate (MFR 230°C 2,16kg) ranging from 2.0 g / 10 min to 35 g / 10 min;1 -butene derived units , measured by13C-NMR content of between 4.2 wt% and 15.5 wt%;1 -butene derived units content of the fraction insoluble in xylene at 25°C, measured by13C-NMR ranging from 3.9 wt% to 15.0 wt%;1 -butene derived unit of the fraction soluble in xylene at 25°C, measured by13C-NMR ranging from 17.0 wt% to 24.0 wt%;The 1 -butene sequence PB, measured by13C-NMR ranging from 10.0 mol% to 16.0 mol%;The 1 -butene sequence PB of the fraction soluble in xylene at 25°C, measured by13C- NMR ranging from 22.0 mol% to 28.5 mol%; molecular weight distribution (MWD), expressed in terms of Mw / Mn, greater than 6.7; the difference between the melting point and the crystallization temperature, Tm-Tc, being lower than 46.0.

2. The random propylene 1 -butene copolymer according to claim 1 wherein the 1 -butene content is comprised between 6.4 wt% and 13.5 wt%.

3. The random propylene 1 -butene copolymer according to claims 1 or 2 wherein the 1- butene derived units content of the fraction insoluble in xylene at 25°C, measured by13C-NMR ranges from 6.1 wt% and 12.6 wt%.

4. The random propylene 1 -butene copolymer according to anyone of claims 1-3 wherein the 1-butene sequence PB, measured by13C-NMR ranges from 11.0 mol% to 15.0 mol%5. The random propylene 1-butene copolymer according to anyone of claims 1-4 wherein the melt flow rate (MFR 230°C 2,16kg) ranges from 5.2 g / 10 min to 25.4 g / 10 min.

6. The random propylene ethylene copolymer according to anyone of claims 1-5 wherein the 2,1 propylene insertions cannot be detected via C13NMR.

7. The random propylene 1 -butene copolymer according to anyone of claims 1-6 wherein the molecular weight distribution (MWD), expressed in terms of Mw / Mn, is greater than 7.2.

8. The random propylene 1 -butene copolymer according to anyone of claims 1-7 wherein the difference between the melting point and the crystallization temperature, Tm-Tc, is lower than 45.0.

9. The random propylene 1 -butene copolymer according to anyone of claims 1-8 wherein the fraction soluble in xylene at 25°C ranges from 2.1 wt% to 7.2 wt%.

10. The random propylene 1 -butene copolymer according to anyone of claims 1-9 wherein the fraction soluble in xylene at 25°C ranges from 2.5 wt% to 6.0 wt%.

11. A process for preparing the random propylene 1 -butene copolymer according to anyone of claims 1-10 comprising the step of polymerizing propylene with ethylene, in the presence of a solid catalyst component for the polymerization of olefins comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least an electron donor of formula (I)in which R1and R2are, independently, C1-C5 alkyl groups, X is Si or C, R3and R4groups, independently, are selected from hydrogen, C1-C10 hydrocarbon groups and halogens with the proviso that at least two R3are not hydrogen.

12. The random propylene 1 -butene copolymer according to claim 11 wherein in the compound of formula (I) R1and R2are the same and are selected from C1-C4 linear or branched alkyl groups.

13. The random propylene 1 -butene copolymer according to claims 11 or 12 wherein in the compound of formula (I) R4groups, independently, are selected from hydrogen, C1-C4 linear or branched alkyl groups and halogens.14 The random propylene 1 -butene copolymer according to claims 11 or 12 wherein in the compound of formula (I) R3is selected from C1-C4 linear or branched alkyl groups.

15. A film comprising the random propylene 1 -butene copolymer according to claims 1-14

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