propylene terpolymer

Abstract

A terpolymer composition comprising: A) 80 wt% to 97 wt% of a propylene, ethylene, and 1-butene terpolymer having: i) 0.5 wt% to 3.2 wt% ethylene-derived unit content; ii) 7.2 wt% to 14.8 wt% 1-butene-derived unit content; B) 20 wt% to 3 wt% of a propylene, ethylene, and 1-butene terpolymer having: i) 0.5 wt% to 3.2 wt% ethylene-derived unit content; ii) 14.4 wt% to 26.5 wt% 1-butene-derived unit content; and said terpolymer composition having a melt flow rate (MFR) ranging from 3.0 g / 10 min to 20.0 g / 10 min, measured at 230 °C with a load of 2.16 kg according to ISO 1133; the sum of the amounts of A) and B) is 100 wt%.

Description

Technical Field

[0001] This disclosure relates to a composition comprising a terpolymer of propylene, ethylene and 1-butene, which is suitable for obtaining films, particularly BOPP (biaxially oriented polypropylene) films having good seal initiation temperature (SIT) and good optical properties. Background Technology

[0002] As is well known, terpolymers of propylene, ethylene, and 1-butene can be used to obtain films, particularly biaxially oriented polypropylene (BOPP) films widely used in food packaging using automated machinery. In fact, these films are characterized by a particularly good balance of processability (machinability), optical and mechanical properties.

[0003] WO 2017 / 114840 relates to a method for producing a terpolymer composition obtained in two circulating reactors. The second polymer fraction (P2) contains C4 and C6... 10 α-Olefin content / C4 and C4 in the first polymer fraction (P1) 10 The weight ratio of α-olefin content is in the range of 0.35 to 0.65.

[0004] It has now been found that compositions of terpolymers of propylene, ethylene and 1-butene can achieve particularly good seal initiation temperature (SIT) and good haze relative to the melting point of the terpolymer, with one of the terpolymers exhibiting distinctive NMR characteristics. Summary of the Invention

[0005] Therefore, the present invention provides a terpolymer composition comprising:

[0006] A) A terpolymer of propylene, ethylene, and 1-butene, comprising 80 wt% to 97 wt%, having the following properties:

[0007] i) 0.5 wt% to 3.2 wt% ethylene-derived unit content;

[0008] ii) 7.2 wt% to 14.8 wt% of 1-butene-derived units;

[0009] iii) Xylene-soluble fractions at 25°C, ranging from 7.2 wt% to 13.4 wt%;

[0010] iv) Determination of melting point by differential scanning calorimetry (DSC) according to ISO 11357-3, with a heating rate of 20 °C / min, in the range of 123 °C to 138 °C;

[0011] v) C ranging from 0.16 mol% to 0.40 mol%. 13 NMR sequence EEE;

[0012] vi) Melt flow rate (MFR) measured at 230°C with a load of 2.16 kg, in the range of 1.0 g / 10 min to 20.0 g / 10 min, according to ISO 1133;

[0013] B) 20 wt% to 3 wt% of a propylene, ethylene, and 1-butene terpolymer, which has the following properties:

[0014] i) 0.5 wt% to 3.2 wt% ethylene-derived unit content;

[0015] ii) 14.4 wt% to 26.5 wt% of 1-butene-derived units;

[0016] iii) Xylene-soluble fractions at 25°C, ranging from 38.2 wt% to 60.2 wt%;

[0017] The content of 1-butene-derived units in component A) is lower than that in component B); and

[0018] The terpolymer composition has a melt flow rate (MFR) ranging from 3.0 g / 10 min to 20.0 g / 10 min, measured at 230 °C with a load of 2.16 kg according to ISO 1133.

[0019] The sum of quantities A) and B) is 100. Detailed Implementation

[0020] Therefore, the present invention provides a terpolymer composition comprising:

[0021] A) 80 wt% to 97 wt%; preferably, 83 wt% to 95 wt%; more preferably 85 wt% to 93 wt% of a propylene, ethylene, and 1-butene terpolymer, having the following characteristics:

[0022] i) 0.5 wt% to 3.2 wt% of ethylene-derived units; preferably, ranging from 0.7 wt% to 2.8 wt%; more preferably, ranging from 0.9 wt% to 2.2 wt%;

[0023] ii) a 1-butene-derived unit content of 7.2 wt% to 14.8 wt%; preferably, ranging from 8.3 wt% to 13.2 wt%; more preferably, ranging from 9.5 wt% to 12.2 wt%;

[0024] iii) A xylene-soluble fraction at 25°C, ranging from 7.2 wt% to 13.4 wt%; preferably, ranging from 8.3 wt% to 12.2 wt%.

[0025] iv) Determining the melting point by differential scanning calorimetry (DSC) according to ISO 11357-3, at a heating rate of 20°C / min, in the range of 123°C to 138°C; preferably, in the range of 127°C to 134°C; more preferably, in the range of 128°C to 132°C;

[0026] v) C ranging from 0.16 mol% to 0.40 mol%. 13 NMR sequence EEE; preferably, the range is 0.18 mol% to 0.35 mol%; more preferably, the range is 0.20 mol% to 0.30 mol%;

[0027] vi) The melt flow rate (MFR) measured at 230°C with a load of 2.16 kg, according to ISO 1133, in the range of 1.0 g / 10 min to 20.0 g / 10 min; preferably, in the range of 3.0 g / 10 min to 13.0 g / 10 min;

[0028] B) 20 wt% to 3 wt%; preferably, 17 wt% to 5 wt%; more preferably 15 wt% to 7 wt% of a propylene, ethylene, and 1-butene terpolymer, having the following characteristics:

[0029] i) 0.5 wt% to 3.2 wt% of ethylene-derived units; preferably, ranging from 0.7 wt% to 2.8 wt%; more preferably, ranging from 0.9 wt% to 2.2 wt%;

[0030] ii) a 1-butene-derived unit content of 14.4 wt% to 26.5 wt%; preferably, ranging from 16.6 wt% to 23.3 wt%; more preferably, ranging from 17.6 wt% to 21.4 wt%;

[0031] iii) A xylene-soluble fraction at 25°C, ranging from 38.2 wt% to 60.2 wt%; preferably, ranging from 40.3 wt% to 55.7 wt%; more preferably, ranging from 42.1 wt% to 54.8 wt%.

[0032] The content of 1-butene-derived units in component A) is lower than that in component B); and

[0033] The terpolymer composition has a melt flow rate (MFR) ranging from 3.0 g / 10 min to 20.0 g / 10 min, measured at 230 °C with a load of 2.16 kg according to ISO 1133; preferably, ranging from 4.0 g / 10 min to 13.2 g / 10 min.

[0034] The sum of quantities A) and B) is 100.

[0035] For the purposes of this invention, the term "terpolymer" refers to a polymer containing three comonomers, such as propylene, ethylene, and 1-butene.

[0036] The terpolymer composition of the present invention is characterized in particular by component A) having a C content in the range of 0.18 mol% to 0.40 mol%. 13 NMR sequence EEE. This value was obtained through a polymerization process in a reactor with two interconnected polymerization zones, a riser, and a downcomer, wherein the grown polymer particles:

[0037] (a) The first riser of the polymerization zone flows under rapid fluidization conditions in the presence of ethylene, propylene and 1-butene;

[0038] (b) They leave the riser and enter the second one in the polymerization zone, namely the downcomer, through which they flow downward in a densified form in the presence of propylene, ethylene and 1-butene, wherein the ethylene concentration in the downcomer is higher than the ethylene concentration in the riser.

[0039] (c) The polymer is removed from the downcomer and reintroduced into the riser, thereby establishing a polymer circulation between the riser and the downcomer.

[0040] In the first polymerization zone (riser), rapid fluidization conditions are established by feeding a gas mixture comprising one or more α-olefins at a rate higher than the conveying velocity of the polymer particles. The velocity of the gas mixture is typically between 0.5 and 15 m / s, preferably between 0.8 and 5 m / s. The terms "conveying velocity" and "rapid fluidization conditions" are well known in the art; for their definitions, see, for example, "D. Geldart, Gas Fluidisation Technology, pp. 155 ff., J. Wiley & Sons Ltd., 1986".

[0041] In the second polymerization zone (downcomer), polymer particles flow in a densified form under gravity, resulting in a high solids density (polymer mass / reactor volume), which is close to the bulk density of the polymer. Throughout the invention, the "densified form" of the polymer refers to a ratio between the mass of the polymer particles and the reactor volume that is greater than 80% of the resulting "cast bulk density" of the polymer. The "cast bulk density" of the polymer is a parameter well known to those skilled in the art. In summary, it is clear that in the downcomer, the polymer flows downward in a plug flow, with only a small amount of gas entrained in the polymer particles.

[0042] According to the method for obtaining component A), the two interconnected polymerization zones are operated in such a way that the gas mixture from the riser is completely or partially prevented from entering the downcomer by introducing a liquid and / or gas stream, termed a "barrier flow," with a composition different from that present in the riser, into the upper part of the downcomer. To conform to this process characteristic, one or more feed lines for the barrier flow are placed in the downcomer near the upper limit of the volume occupied by the polymer particles flowing downward in a densified form.

[0043] The liquid / gas mixture fed into the upper part of the downcomer partially replaces the gas mixture entrained by the polymer particles entering the downcomer. Partial evaporation of the liquid in the barrier flow generates an airflow in the upper part of the downcomer that moves countercurrently to the descending polymer flow, thus acting as a barrier against the gas mixture originating from the riser and entrained in the polymer particles. The liquid / gas barrier fed into the upper part of the downcomer can be sprayed onto the surface of the polymer particles: the evaporation of the liquid provides the required upward airflow.

[0044] The blocked feed causes differences in monomer and / or hydrogen (molecular weight regulator) concentrations in the riser and downcomer.

[0045] The specific polymerization methods and equipment are described in EP 1012195.

[0046] The method for preparing the propylene-ethylene-1-butene terpolymer component A of the present invention is carried out in the presence of a highly stereooriented, multiphase Ziegler-Natta catalyst. The Ziegler-Natta catalyst suitable for preparing the propylene-ethylene-1-butene terpolymer component A of the present invention comprises a solid catalyst component, said solid catalyst component comprising at least one titanium compound having at least one titanium-halogen bond and at least one electron donor compound (internal donor), both supported on magnesium chloride. The Ziegler-Natta catalyst system also includes an organoaluminum compound as a necessary cocatalyst and an optional external electron donor compound.

[0047] Suitable catalyst systems are described in European patents EP45977, EP361494, EP728769, EP 1272533 and international patent application WO000163261.

[0048] Component B) of the propylene-ethylene-1-butene terpolymer is preferably prepared in a gas-phase process, more preferably in a fluidized bed gas-phase process. Components A) and B) are preferably prepared in a cascade process, wherein component A) is prepared, and then component B) is prepared in a gas-phase reactor in the presence of component A) without the need for the addition of an additional catalyst.

[0049] The terpolymer compositions of the present invention are particularly suitable for the production of films, especially cast or BOPP films. The resulting films are characterized by a particularly high Δ between the melting point and the saturation point (SIT) and good haze. In particular, the difference between the melting point and the SIT of the composition is less than 20°C, preferably less than 23°C, and more preferably less than 26°C.

[0050] The haze measured on a 50 μm cast film is less than 0.7%, preferably less than 0.5%.

[0051] The film obtained using the terpolymer composition of the present invention may also contain additives commonly used in film manufacturing, particularly for films used in automated machine packaging applications, such as antioxidants, processing stabilizers, lubricants, antistatic agents, antiblocking agents, and antifogging agents.

[0052] The following examples are given to illustrate, but not to limit, the invention:

[0053] Example

[0054] Xylene-soluble (XS) fractionation at 25°C

[0055] The xylene-soluble fraction at 25°C was determined according to ISO 16152:2005; when the solution volume was 250 ml, precipitation was carried out at 25°C for 20 minutes, and 10 fractions were stirred together with the solution (magnetic stirrer) and dried at 70°C. The xylene-soluble fraction of component b) was calculated according to the formula XStot=XsAWA+XsBWB.

[0056] Where Xstot is the xylene-soluble fraction of the total composition, XsA is the xylene-soluble fraction of component A, and WA is the amount of component A; XsB is the xylene-soluble fraction of component B and WB is the amount of component B; where Wa+Wb=1.

[0057] Melt flow rate (MFR)

[0058] Measured according to ISO 1133 at 230°C with a load of 2.16 kg, unless otherwise specified.

[0059] Measurement of haze

[0060] Multilayer film samples prepared as described below were used. Haze values ​​were measured using a Gardner photometric unit connected to an equivalent instrument, either a UX-10 haze meter or a GE1209 light source with filter "C". The instrument was calibrated using a reference sample with known haze according to ASTM D1003.

[0061] Determination of ethylene and 1-butene content

[0062] Obtained on a Bruker AV600 spectrometer equipped with a cryogenic probe. 13 C10 NMR spectroscopy was performed at 120 °C in Fourier transform mode at 150.91 MHz.

[0063] S δδ The carbon peak (according to CJ Carman, R.A. Harrington, and C.E. Wilkes, Macromolecules, 10, 3, 536 (1977)) at 29.9 ppm was used as an internal control. Approximately 30 mg of sample was dissolved in 0.5 mL of 1,1,2,2-tetrachloroethane d2 at 120 °C. Each spectrum was obtained with a 90° pulse, and the 15-second delay between the pulse and the CPD was removed. 1 H- 13 C-coupling. 512 transients were stored in 65K data points using a 9000Hz spectral window.

[0064] The trivalent basis distribution is obtained using the following relationship:

[0065] XPX = 100 I8 / ∑

[0066] XPE=100 I5 / ∑

[0067] EPE=100 I4 / ∑

[0068] XBX=100 I3 / ∑

[0069] XBE=I00 I2 / ∑

[0070] XEX=100 I9 / ∑

[0071] XEE=100 I1 / ∑

[0072] EEE=100(0.5I7+0.25I6) / ∑

[0073] Where ∑=I8+I5+I4+I3+I2+I9+I1+0.5I7+0.25I6

[0074] I is the area of ​​the corresponding carbon reported in Table a.

[0075] And X can be propylene or 1-butene

[0076] The molar amounts of ethylene, propylene, and 1-butene are obtained from the trivalent groups using the following relationships:

[0077] P(m%) = XPX + XPE + EPE

[0078] B(m%)=XBX+XBE+EBE

[0079] E(m%)=EEE+XEE+XEX

[0080] The molar content is converted to weight using the monomer molecular weight.

[0081] Table a: Ethylene / propylene / 1-butene terpolymer 13 Distribution of C NMR spectra

[0082] Serial Number Chemical shift (ppm) carbon sequence 1 37.64-37.35 <![CDATA[S αδ ]]> PEE 2 37.35-37.15 <![CDATA[T βδ ]]> XBE 3 35.27-34.92 <![CDATA[T ββ ]]> XBX 4 33.29-33.15 <![CDATA[T δδ ]]> EPE 5 30.93-30.77 <![CDATA[T βδ ]]> XPE 6 30.35-30.26 <![CDATA[S γδ ]]> PEEE 7 29.97-29.85 <![CDATA[S δδ ]]> EEE 8 29.14-28.31 <![CDATA[T ββ ]]> XPX 9 24.88-24.14 <![CDATA[S ββ ]]> XEX

[0083] Example 1 and Comparative Example 2

[0084] Steps for preparing spherical adducts

[0085] Microspherical MgCl2·pC2H5OH adducts were prepared according to the method described in Comparative Example 5 of WO 98 / 44009, except that BiCl3 in powder form at 3 mol% relative to magnesium was added before oil introduction. The adduct contained 11.2 wt% Mg.

[0086] Steps for preparing solid catalyst components

[0087] 200 L of TiCl4 was introduced into a 300 L jacketed reactor equipped with a mechanical stirrer, condenser, and thermocouples at room temperature under a nitrogen atmosphere. After cooling to 0 °C, diisobutyl phthalate and 8 kg of spherical adduct (prepared as described above) were added sequentially with stirring. The amount of internal donor added was such that the Mg / donor molar ratio was 8. The temperature was raised to 100 °C and held for 1 hour. Thereafter, stirring was stopped, the solid product was allowed to settle, and the supernatant was siphoned off at 100 °C. After removing the supernatant, additional fresh TiCl4 was added to return to the initial liquid volume. The mixture was then heated to 120 °C and held at that temperature for 1 / 2 hour. Stirring was stopped again, the solid was allowed to settle, and the supernatant was siphoned off at 120 °C. The treatment with TiCl4 at 120 °C was then repeated in the same manner as before, but the treatment time was reduced to 15 minutes. The solid was washed six times with anhydrous hexane in a temperature gradient down to 60 °C, and once at room temperature. The obtained solid was then dried under vacuum.

[0088] Prepolymerization treatment

[0089] Before introducing it into the polymerization reactor, the above-mentioned solid catalyst components were contacted with triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS, D-donor) in proportions reported in Table 1. The resulting mixture was then subjected to prepolymerization by suspending it in liquid propylene at 20°C for approximately 5 minutes before being introduced into the polymerization reactor.

[0090] polymerization

[0091] As described in European Patent EP 1012195, polymerization is carried out in a gas-phase polymerization reactor comprising two interconnected polymerization zones, a riser, and a downcomer. Specifically, the two interconnected polymerization zones are operated in such a way that a gas mixture from the riser is completely or partially prevented from entering the downcomer by introducing a liquid and / or gas stream, termed a “barrier flow,” with a composition different from the gas mixture present in the riser, into the upper part of the downcomer. In Comparative Example 2, no “barrier flow” was used.

[0092] The polymer produced in the first reactor was discharged as a continuous flow and introduced as a continuous flow, along with a constant flow rate of gaseous hydrogen (when used), 1-butene, ethylene, and propylene, as reported in Table 1, into the second fluidized bed gas-phase polymerization reactor. Samples of the terpolymer from the first reactor were taken for testing and analysis.

[0093] The polymer particles discharged from the polymerization step are steam-treated to remove unreacted monomers and dried under a nitrogen stream.

[0094] The main pre-contact, pre-polymerization, and polymerization conditions, as well as the amounts of monomer and hydrogen fed into the polymerization reactor, are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] C2 = Ethylene; C3 = Propylene; C4 = 1-Butene

[0099] The properties of the polymers of Example 1 and Comparative Example 2 are shown in Table 2.

[0100] Table 2

[0101]

[0102]

[0103] *Calculated

[0104] Table 2 shows that component A) obtained according to the present invention exhibits a higher SIT compared to component A) of the comparative example, but the SIT of the composition of the present invention is lower (103°C) than that of the comparative example.

Claims

1. A terpolymer composition comprising: A) A terpolymer of propylene, ethylene, and 1-butene, comprising 80 wt% to 97 wt%, having the following properties: i) 1.2 wt% to 3.2 wt% ethylene-derived unit content; ii) Content of 1-butene-derived units ranging from 9.8 wt% to 14.8 wt%; iii) Xylene-soluble fraction at 25°C, ranging from 8.3 wt% to 13.4 wt%; iv) The melting point was determined by differential scanning calorimetry (DSC) according to ISO 11357-3 at a heating rate of 20 °C / min, in the range of 123 °C to 138 °C. v) C13 NMR sequences ranging from 0.16 mol% to 0.40 mol% (EEE); vi) Melt flow rate (MFR) measured at 230°C with a load of 2.16 kg, ranging from 1.0 g / 10 min to 20.0 g / 10 min, according to ISO 1133; B) A terpolymer of propylene, ethylene, and 1-butene, comprising 20 wt% to 3 wt%, having the following properties: i) 0.5 wt% to 3.2 wt% ethylene-derived unit content; ii) 14.4 wt% to 26.5 wt% of 1-butene-derived units; iii) Xylene-soluble fraction at 25°C, ranging from 38.2 wt% to 60.2 wt%; The content of the 1-butene-derived unit in component A) is lower than the content of the 1-butene-derived unit in component B); and The terpolymer composition has a melt flow rate (MFR) ranging from 3.0 g / 10 min to 20.0 g / 10 min, measured at 230°C with a load of 2.16 kg according to ISO 1133. The sum of A) and B) is 100 wt%, wherein component A) of the terpolymer is obtained by polymerization in a gas-phase polymerization reactor comprising two interconnected polymerization zones, a riser and a downcomer, wherein the two interconnected polymerization zones are operated in such a way that a gas mixture from the riser is completely or partially prevented from entering the downcomer by introducing a liquid and / or gas stream, which has a different composition from the gas mixture present in the riser, into the upper part of the downcomer.

2. The terpolymer composition according to claim 1, comprising 83 wt% to 95 wt% of component A and 17 wt% to 5 wt% of component B.

3. The terpolymer composition according to claim 1, wherein in component A), the xylene soluble fraction at 25°C is 8.3 wt% to 12.2 wt%.

4. The terpolymer composition according to claim 1, wherein in component A), the melting point is determined to be in the range of 127°C to 134°C by differential scanning calorimetry (DSC) according to ISO 11357-3 at a heating rate of 20°C / min.

5. The terpolymer composition according to claim 1, wherein in component A), the C13 NMR sequence EEE ranges from 0.18 mol% to 0.35 mol%.

6. The terpolymer composition according to claim 1, wherein in component A), the content of the ethylene-derived unit is from 1.2 wt% to 2.8 wt%.

7. The terpolymer composition according to claim 1, wherein in component A), the content of the 1-butene derivative unit is from 9.8 wt% to 13.2 wt%.

8. The terpolymer composition according to claim 1, wherein in component B), the content of the ethylene-derived unit is from 0.7 wt% to 2.8 wt%.

9. The terpolymer composition according to claim 1, wherein in component B), the content of the 1-butene derivative unit is from 16.6 wt% to 23.3 wt%.

10. The terpolymer composition according to claim 1, wherein the melt flow rate (MFR) ranges from 4.0 g / 10 min to 13.2 g / 10 min, as measured according to ISO 1133 at 230°C with a load of 2.16 kg.

11. The terpolymer composition according to claim 1, wherein in component A), the melt flow rate (MFR) ranges from 3.0 g / 10 min to 13.0 g / 10 min, as measured according to ISO 1133 at 230°C with a load of 2.16 kg.

12. The terpolymer composition according to claim 1, wherein in component A), the content of the ethylene-derived unit is from 1.2 wt% to 2.2 wt%.

13. The terpolymer composition according to claim 1, wherein in component A), the content of 1-butene derivative units is from 9.8 wt% to 12.2 wt%.

14. A membrane comprising the terpolymer composition of claim 1.

15. The membrane according to claim 14, wherein the membrane is a BOPP membrane.

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