Polypropylene compositions containing novel charge stabilizers for use in electret meltblown wire

Abstract

A polypropylene composition (PC) comprising: a. 95.0 to 99.99 wt.-% of a polypropylene (PP), preferably a propylene homopolymer (HPP); and b. 0.01 to 5.0 wt.-% of a compound according to formula (I) wherein each R is independently selected from C1 to C6 alkylene, C2 to C6 alkenylene and a single bond, each R' is independently selected from H and C1 to C6 alkyl, each R" is independently selected from H and C1 to C 22 alkyl, wherein each alkylene, alkenylene and alkyl can optionally be substituted with deuterium or fluorine, and the two substituents on the central phenyl ring can be positioned in ortho, meta or para relationship; wherein the polypropylene composition (PC) has a MFR2 of 400 to 5000 g / 10min and a melting temperature Tm of 140 to 170 °C.

Description

Technical Field

[0001] The present invention relates to a polypropylene composition comprising a specific charge stabilizer, a meltblown mesh and an electret meltblown mesh made from said composition, a method for preparing said meltblown mesh and electret meltblown mesh, and the use of the specific charge stabilizer for stabilizing the charge of electret materials. Background Technology

[0002] Meltblown fabric is a nonwoven structure composed of meltblown fibers, typically manufactured in a one-step process where high-speed air blows molten thermoplastic resin from an extruder die tip onto a conveyor belt or winding screen to form a fine-fiber self-adhesive web. Although many types of polymers can be used for meltblown fibers and fabrics, polypropylene is one of the most commonly used polymers.

[0003] Meltblown fabric is frequently used due to its filtration properties. While optimized filtration performance has been important in many long-established fields, it has become increasingly important since the spread of the COVID-19 pandemic, with face shields possessing beneficial filtration properties being particularly valuable. In this context, and indeed in most applications, beneficial filtration properties include high filtration efficiency (i.e., removal of a high proportion of particles) and low pressure drop (i.e., allowing gases such as air to pass through the filter relatively easily, thus enabling the wearer of the face shield to breathe more easily).

[0004] Face masks with exceptionally high filtration efficiency (such as N95 masks) typically contain electrostatically charged polypropylene meltblown mesh. Polypropylene is a natural electret, meaning that due to its dielectric properties, it can support permanent electric dipoles. Electrostatically charged filters offer significantly improved filtration efficiency without a corresponding increase in voltage drop.

[0005] Factors known to affect the filtration performance of such meltblown mesh include the selection of appropriate polypropylene substrate, optimization of charging method, and use of charge stabilizing additives.

[0006] Charge-stabilizing additives are particularly important because adding even small amounts of a compound that has a significant impact on the final performance is very economical.

[0007] Many charge-stabilizing additives are known in the art.

[0008] Exemplary charge-stabilizing additives include magnesium stearate (RSC Advance, 2018, 8, 7932), triamide derivatives (EP 2 294 257 A2), hydroxyamides (EP 2 005 453 A1), F-free heterocyclic imides (EP 2 414573 A2), arylamino-substituted benzoic acid / salts (EP 2 986 354 A2), and substituted-mercaptobenizidyolate salts (EP 2 938 420 A1), as well as multi-component systems (EP2 609 238 A1).

[0009] While many of these additives are useful charge stabilizers, some also have other functions (such as viscous cracking agents), which limits the choice of polypropylene substrates.

[0010] Given the importance of these additives, there has been a strong desire to develop novel charge stabilizers, especially those that provide improved filtration performance (indicating good charge retention) both immediately after charging and over a period of time. Summary of the Invention

[0011] This invention is based on the discovery that certain charge stabilizers, previously known only as heat and UV / light stabilizers for polyamides (especially for nylon), surprisingly act as effective charge stabilizers for polypropylene-based electrets.

[0012] The present invention therefore relates to a polypropylene composition (PC) comprising:

[0013] i) 95.0 to 99.99% by weight of polypropylene (PP), preferably propylene homopolymer (HPP), based on the total weight of the composition; and

[0014] ii) 0.01 to 5.0% by weight of the compound according to formula (I) based on the total weight of the composition.

[0015]

[0016] Each R is independently selected from C1 to C6 alkylene, C2 to C6 alkenyl, and single bond; each R' is independently selected from H and C1 to C6 alkyl; and each R” is independently selected from H and C1 to C6 alkyl. 22 Alkyl group, wherein each alkylene group, alkenyl group and alkyl group may optionally be substituted with deuterium or fluorine, and the two substituents on the central benzene ring may be positioned in an ortho, meta or para relationship;

[0017] Based on the total weight of the composition, the total content of polypropylene (PP), more preferably propylene homopolymer (HPP), and the compound according to formula (I) is at least 98.0% by weight, more preferably at least 99.0% by weight, and

[0018] The melt flow rate (MFR2) of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined according to ISO 1133 at 230°C and under a load of 2.16 kg, is in the range of 400 to 5000 g / 10 min, and the melt temperature (Tm) of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined according to ISO 11357 by differential scanning calorimetry (DSC), is in the range of 140 to 170°C.

[0019] In another aspect, the present invention relates to meltblown mesh made from the polypropylene composition (PC) of the present invention.

[0020] The present invention also relates to a method for preparing the meltblown mesh of the present invention, comprising the following steps:

[0021] (ai) provides polypropylene (PP1), more preferably propylene homopolymer (HPP1);

[0022] or

[0023] (a.ii) or provide polypropylene (PP2), more preferably propylene homopolymer (HPP2) and a viscous cracking agent, preferably a peroxide radical generator;

[0024] and

[0025] (b) Provide a compound according to formula (I);

[0026] (c) The mixture of components provided in steps (a) and (b) is granulated in a granulator to obtain a polypropylene composition (PC) comprising 95.0 to 99.9% by weight of polypropylene (PP), more preferably propylene homopolymer (HPP), and 0.01 to 5.0% by weight of a compound according to formula (I) based on the total weight of the composition.

[0027] (d) Melt-blown the blended granules obtained in step (c); and

[0028] (e) Preferably, the meltblown mesh obtained in step (d) is electrostatically charged to obtain an electret meltblown mesh.

[0029] In a final aspect, the present invention relates to the use of a compound according to formula (I) for stabilizing the charge in an electret meltblown mesh made of a polypropylene composition (PC), the polypropylene composition (PC) comprising:

[0030] i) 95.0 to 99.99% by weight of polypropylene (PP), preferably propylene homopolymer (HPP), based on the total weight of the composition; and

[0031] ii) 0.01 to 5.0% by weight of the compound according to formula (I) based on the total weight of the composition.

[0032]

[0033] Each R is independently selected from C1 to C6 alkylene, C2 to C6 alkenyl, and single bond; each R' is independently selected from H and C1 to C6 alkyl; and each R” is independently selected from H and C1 to C6 alkyl. 22 Alkyl group, wherein each alkylene group, alkenyl group and alkyl group may optionally be substituted with deuterium or fluorine, and the two substituents on the central benzene ring may be positioned in an ortho, meta or para relationship;

[0034] Based on the total weight of the composition, the total content of polypropylene (PP), more preferably propylene homopolymer (HPP), and the compound according to formula (I) is at least 98.0% by weight, more preferably at least 99.0% by weight, and

[0035] The melt flow rate (MFR2) of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined according to ISO 1133 at 230°C and under a load of 2.16 kg, is in the range of 400 to 5000 g / 10 min, and the melt temperature (Tm) of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined according to ISO 11357 by differential scanning calorimetry (DSC), is in the range of 140 to 170°C.

[0036] definition

[0037] Propylene homopolymers are polymers essentially composed of propylene monomer units. Due to impurities, especially those introduced during commercial polymerization processes, propylene homopolymers may contain up to 1.0 mol% of comonomer units, preferably up to 0.5 mol% of comonomer units, more preferably up to 0.1 mol% of comonomer units, even more preferably up to 0.05 mol% of comonomer units, and most preferably up to 0.01 mol% of comonomer units. Particularly preferred is that propylene is the only detectable monomer. Propylene random copolymers are copolymers of propylene monomer units and comonomer units (preferably selected from ethylene and C4-C12 α-olefins), wherein the comonomer units are randomly distributed along the polymer chain. Propylene random copolymers may contain comonomer units from one or more comonomers that differ in their carbon atomic weights. Hereinafter, unless otherwise specified, amounts are given in % (wt%).

[0038] An electret is a dielectric material having a quasi-permanent electrostatic charge or dipole polarization. It can be conceived as the electrostatic equivalent of a permanent magnet. In the context of this invention, an electret is identified as any material carrying a quasi-permanent electrostatic charge (i.e., electrostatically charged). When used in the context of this invention, the phrase "electrostatically charged" does not refer to how the charge is generated, but rather to the fact that the material has an electrostatic charge, as opposed to a charge generated by ionic components in a polyolefin (such as metal salts or cationic or anionic comonomers). Electrostatic charge can be introduced by many methods known to those skilled in the art, including but not limited to electrospinning, corona charging, tribocharging, hydrocharging, or in an electric field. Detailed Implementation

[0039] Polypropylene (PP)

[0040] Polypropylene (PP) is a basic component of a polypropylene composition (PC).

[0041] Polypropylene (PP) can be selected from propylene homopolymer (HPP), propylene random copolymer (RPP), and multiphase propylene copolymer (HECO). Preferably, polypropylene (PP) is propylene homopolymer (HPP).

[0042] The melt flow rate (MFR2) of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined according to ISO 1133 at 230°C and under a load of 2.16 kg, is in the range of 400 to 5000 g / 10 min, more preferably in the range of 500 to 3000 g / 10 min, even more preferably in the range of 600 to 2000 g / 10 min, and most preferably in the range of 700 to 1800 g / 10 min.

[0043] The melting temperature Tm of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined by differential scanning calorimetry (DSC) according to ISO 11357, is in the range of 140 to 170 °C.

[0044] In one embodiment, polypropylene (PP) has been polymerized in the presence of a Ziegler-Natta catalyst. Ziegler-Natta catalyzed polypropylene is characterized by a relatively high melting point and the absence of 2,1 erythmic region defects.

[0045] Therefore, in this embodiment, polypropylene (PP), more preferably propylene homopolymer (HPP), does not contain [the following]. 13 Defects in the 2,1 reddish region were determined by C-NMR spectroscopy.

[0046] In this same embodiment, the melting temperature Tm of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined by differential scanning calorimetry (DSC) according to ISO 11357, is in the range of 155 to 170°C, more preferably in the range of 157 to 167°C, and most preferably in the range of 159 to 165°C.

[0047] In an alternative embodiment, polypropylene (PP), more preferably propylene homopolymer (HPP), has been polymerized in the presence of a single active site catalyst (SSC). SSC-catalyzed polypropylene is characterized by a relatively low melting point and the presence of 2,1 erythromorphic defects, as well as a typically high concentration of isotactic pentamelids (mmmm).

[0048] Therefore, in this alternative embodiment, polypropylene (PP), more preferably propylene homopolymer (HPP), is used... 13 The content of defects in the 2,1 red region, as determined by C-NMR spectroscopy, is preferably in the range of 0.01 to 1.5 mol%, more preferably in the range of 0.10 to 1.2 mol%, even more preferably in the range of 0.20 to 1.0 mol%, still more preferably in the range of 0.30 to 0.80 mol%, and most preferably in the range of 0.40 to 0.70 mol%.

[0049] In this same alternative embodiment, the melting temperature Tm of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined by differential scanning calorimetry (DSC) according to ISO 11357, is preferably in the range of 140 to 160°C, more preferably in the range of 148 to 159°C, and most preferably in the range of 152 to 158°C.

[0050] In this same alternative embodiment, it is particularly preferred that the propylene homopolymer (HPP) is passed through 13 The content of defects in the 2,1 red region, as determined by C-NMR spectroscopy, is in the range of 0.50 to 1.5 mol%, more preferably in the range of 0.50 to 1.2 mol%, even more preferably in the range of 0.50 to 1.0 mol%, still more preferably in the range of 0.50 to 0.80 mol%, and most preferably in the range of 0.50 to 0.70 mol%.

[0051] In this same alternative embodiment, it is also preferred that the propylene homopolymer (HPP) is passed through 13 The concentration (mmmm) of isotactic pentads determined by C-NMR spectroscopy is in the range of 95.0 to 100.0%, more preferably in the range of 97.0 to 99.99%, and most preferably in the range of 98.0 to 99.9%.

[0052] Polypropylene (PP) is also characterized by its molecular weight properties.

[0053] Preferably, the molecular weight distribution of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined by gel permeation chromatography, is in the range of 1.0 to 6.0, more preferably in the range of 1.5 to 5.0, and most preferably in the range of 2.0 to 4.5.

[0054] In embodiments in which polypropylene (PP), more preferably propylene homopolymer (HPP), has been polymerized in the presence of a Ziegler-Natta catalyst, preferably, the molecular weight distribution of the polypropylene (PP), more preferably propylene homopolymer (HPP), as determined by gel permeation chromatography, is in the range of 1.5 to 6.0, more preferably in the range of 2.0 to 5.0, and most preferably in the range of 2.5 to 4.5.

[0055] In embodiments in which polypropylene (PP), more preferably propylene homopolymer (HPP), has been polymerized in the presence of a single active site catalyst, preferably, the molecular weight distribution (Mw / Mn) of the polypropylene (PP), more preferably the propylene homopolymer (HPP), as determined by gel permeation chromatography, is in the range of 1.0 to 5.0, more preferably in the range of 1.5 to 4.5, and most preferably in the range of 2.0 to 4.0.

[0056] Preferably, the weight-average molecular weight (Mw) of polypropylene (PP), more preferably propylene homopolymer (HPP), as determined by gel permeation chromatography, is in the range of 25,000 to 85,000, more preferably in the range of 35,000 to 80,000, and most preferably in the range of 45,000 to 75,000.

[0057] Preferably, the xylene soluble content (XCS) of the propylene homopolymer (HPP), as determined according to ISO 16152 at 25°C, is in the range of 0.1 to 4.0% by weight, more preferably in the range of 0.2 to 3.0% by weight, and most preferably in the range of 0.5 to 2.0% by weight.

[0058] All given properties of polypropylene (PP) refer to the polypropylene (PP) in its presence in a polypropylene composition (PC). In some cases, the properties of the polypropylene (PP) may differ from those of the precursor polypropylene used to prepare the polypropylene composition (i.e., before mixing or blending with the compound according to formula (I) and any other components). Significant differences have been observed as a result of a viscosity-reducing cracking process, which is clearly understood by those skilled in the art as a method for adjusting the rheological properties of the post-polypropylene reactor.

[0059] In the simplest case, polypropylene (PP) is not subjected to viscosity-reducing cracking. Therefore, polypropylene (PP), more preferably propylene homopolymer (HPP), is essentially the same as polypropylene (PP1), more preferably propylene homopolymer (HPP1), used to prepare polypropylene compositions (PC).

[0060] Regarding the polymer properties of polypropylene (PP), more preferably propylene homopolymer (HPP), namely the concentration, molecular weight and molecular weight distribution of MFR2, Tm, 2,1 erythromorphic region defects, range and preferred embodiments, applicable to polypropylene (PP1), more preferably propylene homopolymer (HPP1), used to prepare polypropylene compositions (PC).

[0061] In another embodiment, the polypropylene (PP) according to the invention, more preferably the propylene homopolymer (HPP), can be the product of reducing the viscosity of the precursor polypropylene (PP2), more preferably the precursor propylene homopolymer (HPP2), using a viscosity-reducing cracking agent.

[0062] Preferably, the viscosity-reducing cracking agent used in this process is a peroxide free radical generator.

[0063] Typical peroxide radical generators are 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DHBP) (e.g., sold under the trade names Luperox 101 and Trigonox 101), 2,5-dimethyl-2,5-bis(tert-butylperoxy)3-hexyne (DYBP) (e.g., sold under the trade names Luperox 130 and Trigonox 145), dicumyl peroxide (DCUP) (e.g., sold under the trade names Luperox DC and Perkadox BC), di-tert-butyl peroxide (DTBP) (e.g., sold under the trade names Trigonox B and Luperox Di), tert-butylcumyl peroxide (BCUP) (e.g., sold under the trade names Trigonox T and Luperox 801), and bis(tert-butylperoxyisopropyl)benzene (DIPP) (e.g., sold under the trade names Perkadox 14S and Luperox DC).

[0064] Preferred peroxides are 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane (DHBP) and tert-butylperoxide (BCUP).

[0065] The use of a specific peroxide or a mixture of different peroxides is within the scope of this invention.

[0066] Regarding polypropylene (PP), and more preferably propylene homopolymer (HPP), the Tm and the concentration, range, and preferred embodiments of the 2,1 erythromorphic region defects are applicable to precursor polypropylene (PP2), and more preferably precursor propylene homopolymer (HPP2). This means that precursor polypropylene (PP2), and more preferably precursor homopolymer (HPP2), can be polymerized in the presence of a Ziegler-Natta catalyst or in the presence of a single active site catalyst, possessing the relevant properties described above.

[0067] Other properties of polypropylene are known to change significantly as a result of viscosity-reducing cracking.

[0068] Preferably, the melt flow rate (MFR2) of the precursor polypropylene (PP2), more preferably the precursor propylene homopolymer (HPP2), as determined according to ISO 1133 at 230°C and a load of 2.16 kg, is in the range of 50 to 399 g / 10 min, more preferably in the range of 65 to 300 g / 10 min, and most preferably in the range of 75 to 250 g / 10 min.

[0069] Preferably, the molecular weight distribution (Wn / Mn) of the precursor polypropylene (PP2), more preferably the precursor propylene homopolymer (HPP2), as determined by gel permeation chromatography, is in the range of 2.0 to 10.0, more preferably in the range of 2.0 to 9.0, and most preferably in the range of 2.0 to 8.5.

[0070] In embodiments in which the precursor polypropylene (PP2), more preferably the precursor propylene homopolymer (HPP2), has been polymerized in the presence of a Ziegler-Natta catalyst, preferably, the molecular weight distribution (Wn / Mn) of the precursor polypropylene (PP2), more preferably the precursor propylene homopolymer (HPP2), as determined by gel permeation chromatography, is in the range of 3.0 to 10.0, more preferably in the range of 4.5 to 9.5, and most preferably in the range of 5.5 to 9.0.

[0071] In embodiments in which precursor polypropylene (PP2), more preferably precursor propylene homopolymer (HPP2), has been polymerized in the presence of a single active site catalyst, preferably, the molecular weight distribution (Wn / Mn) of the precursor polypropylene (PP2), more preferably precursor propylene homopolymer (HPP2), as determined by gel permeation chromatography, is in the range of 2.0 to 6.0, more preferably in the range of 2.0 to 5.0, and most preferably in the range of 2.0 to 4.5.

[0072] Preferably, the precursor polypropylene (PP2), more preferably the precursor propylene homopolymer (HPP2), has a weight-average molecular weight (Mw) in the range of 50,000 to 140,000 as determined by gel permeation chromatography, more preferably in the range of 70,000 to 130,000, and most preferably in the range of 80,000 to 120,000.

[0073] By subjecting the polypropylene according to the invention to viscosity-reducing cracking, the molar mass distribution (Mw / Mn) becomes narrower because the long molecular chains are more easily broken or sheared and the molar mass M will decrease, corresponding to an increase in MFR2.

[0074] Therefore, a further preferred material is polypropylene (PP), and more preferably propylene homopolymer (HPP) with a molecular weight (M). w M with precursor polypropylene (PP2), more preferably precursor propylene homopolymer (HPP2) w molecular weight (M) w ) compared to [M w (PP) / M w [(PP2)] is <1, preferably ≤0.90, more preferably ≤0.85, and still more preferably ≤0.80.

[0075] Similarly, the ratio of the molecular weight distribution (Mw / Mn or MWD) of polypropylene (PP), more preferably propylene homopolymer (HPP), to the molecular weight distribution (Mw / Mn or MWD) of precursor polypropylene (PP2), more preferably precursor propylene homopolymer (HPP2) [MWD(PP) / MWD(PP2)] is <1, preferably ≤0.95, more preferably ≤0.90, still more preferably ≤0.85, and most preferably ≤0.80.

[0076] The viscosity reduction cracking ratio is defined as the melt flow rate MFR2 of polypropylene (PP), more preferably propylene homopolymer (HPP), divided by the melt flow rate MFR2 of precursor polypropylene (PP2), more preferably precursor propylene homopolymer (HPP2), wherein each melt flow rate MFR2 is determined according to ISO 1133 at 230°C and a load of 2.16 kg.

[0077] Preferably, the viscosity reduction cracking ratio is in the range of 3.0 to 40, more preferably in the range of 3.5 to 20, and most preferably in the range of 4.0 to 10.

[0078] Polypropylene (PP1), more preferably propylene homopolymer (HPP1) or precursor polypropylene (PP2), used to prepare polypropylene compositions (PC), can be selected from commercially available polypropylene grades, or can be polymerized according to the following methods.

[0079] Methods for forming polypropylene (PP1) or precursor polypropylene (PP2)

[0080] Polypropylene (PP1 or PP2), more preferably propylene homopolymer (HPP1 or HPP2), is preferably prepared by single-stage or multi-stage polymerization of propylene (such as bulk polymerization, gas-phase polymerization, slurry polymerization, solution polymerization, or a combination thereof). Preferably, polypropylene (PP1 or PP2), more preferably propylene homopolymer (HPP1 or HPP2), can be prepared in a combination of a loop reactor and a gas-phase reactor. These processes are well known to those skilled in the art.

[0081] A preferred multi-stage process is the "loop-gas phase" process, such as the one developed by Borealis (called...). (Technology), for example, described in patent documents such as EP 0 887 379, WO 92 / 12182, WO 2004 / 000899, WO 2004 / 111095, WO 99 / 24478, WO 99 / 24479 or WO 00 / 68315.

[0082] Another suitable slurry-gas phase process is Basell's Process.

[0083] The catalyst used in the polymerization process can be any suitable catalyst used for polypropylene polymerization.

[0084] In one embodiment, polypropylene (PP1 or PP2), more preferably propylene homopolymer (HPP1 or HPP2), is preferably obtained by using a catalyst system comprising a Ziegler-Natta catalyst, wherein the Ziegler-Natta catalyst preferably comprises a magnesium halide support, a titanium component, and an inert donor.

[0085] In an alternative embodiment, polypropylene (PP1 or PP2), more preferably propylene homopolymer (HPP1 or HPP2), is preferably obtained by using a catalyst system containing a single active site catalyst, and more preferably by using a metallocene catalyst complex and a co-catalyst.

[0086] Preferred metallocene catalyst complexes include:

[0087] Racemic-dimethylsilylbis[2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride

[0088] Racemic-trans-dimethylsilyl[2-methyl-4-(4'-tert-butylphenyl)-inden-1-yl][2-methyl-4-(4'-tert-butylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

[0089] Racemic-trans-dimethylsilyl[2-methyl-4-(4'-tert-butylphenyl)-inden-1-yl][2-methyl-4-phenyl-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride,

[0090] Racemic-trans-dimethylsilyl[2-methyl-4-(3',5'-tert-butylphenyl)-1,5,6,7-tetrahydro-symmetric indarsen-1-yl][2-methyl-4-(3',5'-dimethyl-phenyl)-5-methoxy-6-tert-butylindene-1-yl]zirconium dichloride,

[0091] Racemic-trans-dimethylsilyl[2-methyl-4,8-bis-(4'-tert-butylphenyl)-1,5,6,7-tetrahydro-symmetric indarsen-1-yl][2-methyl-4-(3',5'-dimethyl-phenyl)-5-methoxy-6-tert-butylindene-1-yl]zirconium dichloride,

[0092] Racemic-trans-dimethylsilyl[2-methyl-4,8-bis-(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-symmetric-indarsen-1-yl][2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylindene-1-yl]zirconium dichloride,

[0093] Racemic-trans-dimethylsilyl[2-methyl-4,8-bis-(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-symmetric-indarsen-1-yl][2-methyl-4-(3',5'-5-di-tert-butyl-phenyl)-5-methoxy-6-tert-butylindene-1-yl]zirconium dichloride.

[0094] Particularly preferred is racemic-trans-dimethylsilyl[2-methyl-4,8-bis-(3',5'-dimethylphenyl)-1,5,6,7-tetrahydro-symmetric indane-1-yl][2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylindene-1-yl]zirconium dichloride.

[0095] In order to form an active catalytic substance, a co-catalyst well known in the art is usually required.

[0096] According to the present invention, a cocatalyst system comprising a boron-containing cocatalyst and an aluminoxane cocatalyst is used in combination with the metallocene catalyst complex defined above.

[0097] The aluminum oxane co-catalyst can be one of formula (II):

[0098]

[0099] Where n is between 6 and 20, and R has the following meanings.

[0100] Aluminoxanes are formed upon partial hydrolysis of organoaluminum compounds (e.g., those of formula AlR3, AlR2Y, and Al2R3Y3), wherein R can be, for example, C1-C10-alkyl, preferably C1-C5-alkyl, or C3-C10-cycloalkyl, C7-C12-aralkyl, or alkylaryl and / or phenyl or naphthyl, and wherein Y can be hydrogen, halogen (preferably chlorine or bromine), or C1-C10-alkoxy (preferably methoxy or ethoxy). The resulting oxyaluminoxane is typically not a pure compound, but a mixture of oligomers of formula (II).

[0101] The preferred aluminoxane is methylaluminoxane (MAO). Since the aluminoxanes used as cocatalysts according to the present invention are prepared by means other than pure compounds, the molar concentrations of the aluminoxane solutions mentioned below are based on their aluminum content.

[0102] Preferred boron-containing cocatalysts used in this invention include borates, particularly borates containing triphenylmethyl (i.e., triphenylcarbium) ions. Therefore, the use of Ph3CB(PhF5)4 or its analogues is particularly advantageous.

[0103] The catalyst system of this invention is used in a supported form. The particulate support material used is silica or a mixture of oxides, such as silica-alumina, particularly silica. The use of silica support is preferred. Those skilled in the art understand the procedures required for supported metallocene catalysts.

[0104] Charge stabilizer

[0105] Another essential component of the polypropylene composition (PC) is a compound according to formula (I):

[0106]

[0107] Each of the cases of R, R', and R” can be the same as or different from each of the other cases of R, R', and R”, as reflected by the phrase “choose independently”.

[0108] Each R is independently selected from C1 to C6 alkylene, C2 to C6 alkenyl, and single bond, more preferably from C1 to C6 alkylene and single bond. Further preferably, each R is independently selected from C1 to C3 alkylene and single bond, more preferably methylene and single bond. In a particularly preferred embodiment, both Rs are single bonds.

[0109] Each R' is independently selected from H and C1 to C6 alkyl groups, more preferably from H and C1 to C4 alkyl groups. Further preferably, each R' is independently selected from H, methyl, and ethyl, more preferably from methyl and ethyl. In a particularly preferred embodiment, all R's are identical, selected from methyl and ethyl, more preferably all R's are methyl.

[0110] Each R is independently selected from H and C1 to C 22 Alkyl groups, more preferably selected from H, methyl, and ethyl. Further preferably, each R” is independently selected from H and methyl. In a particularly preferred embodiment, both R” are H.

[0111] In the above description of substitutions at R, R' and R”, the definitions of “alkylene,” “alkenyl,” and “alkyl” should be understood to include straight-chain or branched groups, optionally substituted with deuterium or fluorine.

[0112] The two substituents on the central benzene ring can be positioned in an ortho, meta, or para relationship. Preferably, the two substituents on the central benzene ring are positioned in a meta relationship.

[0113] In a particularly preferred combination, each R is independently selected from methylene and single bond, each R' is independently selected from C1 to C4 alkyl, each R" is H and the two substituents on the central benzene ring can be positioned in a meta-relation.

[0114] Most preferably, the compound according to formula (I) is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide, with CAS number 42774-15-2.

[0115] Polypropylene (PC) composition

[0116] The polypropylene composition (PC) according to the present invention comprises:

[0117] i) 95.0 to 99.99% by weight of polypropylene (PP), preferably propylene homopolymer (HPP), based on the total weight of the composition; and

[0118] ii) 0.01 to 5.0% by weight of the compound according to formula (I) based on the total weight of the composition.

[0119] More preferably, the polypropylene composition (PC) according to the present invention comprises:

[0120] i) 98.0 to 99.98% by weight of polypropylene (PP), preferably propylene homopolymer (HPP), based on the total weight of the composition; and

[0121] ii) 0.02 to 2.0% by weight of the compound according to formula (I) based on the total weight of the composition.

[0122] More preferably, the polypropylene composition (PC) according to the present invention comprises:

[0123] i) 99.0 to 99.95% by weight of polypropylene (PP), preferably propylene homopolymer (HPP), based on the total weight of the composition; and

[0124] ii) 0.05 to 1.0% by weight of the compound according to formula (I) based on the total weight of the composition.

[0125] Most preferably, the polypropylene composition (PC) according to the present invention comprises:

[0126] i) 99.5 to 99.90% by weight of polypropylene (PP), preferably propylene homopolymer (HPP), based on the total weight of the composition; and

[0127] ii) 0.10 to 0.5% by weight of the compound according to formula (I) based on the total weight of the composition.

[0128] The total content of polypropylene (PP), more preferably propylene homopolymer (HPP), and the compound according to formula (I) is at least 98.0% by weight, more preferably at least 99.0% by weight, even more preferably at least 99.5% by weight, and most preferably at least 99.7% by weight.

[0129] The polypropylene compositions of the present invention may contain other components; however, it is preferred that the polypropylene compositions of the present invention contain only polypropylene (PP) as defined in the present invention, and more preferably propylene homopolymer (HPP) as a polymer component.

[0130] The remaining portion, up to 100.0% by weight, can be achieved by other additives known in the art; however, relative to the total weight of the polypropylene composition (PC), this remaining portion should not exceed 2.0% by weight, more preferably not more than 1.0% by weight, even more preferably not more than 0.5% by weight, and most preferably not more than 0.3% by weight.

[0131] The polypropylene compositions of the present invention may contain small amounts of additives selected from the group consisting of antioxidants, stabilizers, fillers, colorants, nucleating agents, and antistatic agents. Typically, these are incorporated during the granulation of the powdered product obtained in the polymerization process.

[0132] Such additives are generally commercially available and are described, for example, in Hans Zweifel's "Plastic Additives Handbook", pp. 871-873, 5th edition, 2001.

[0133] meltblown mesh

[0134] The present invention also relates to meltblown mesh made of polypropylene composition (PC).

[0135] In the context of this invention, the term "made of" means feeding polypropylene and optional other components into a meltblown apparatus to form a meltblown web.

[0136] In particular, preferably, based on the total weight of the meltblown mesh, the meltblown mesh comprises at least 80.0% by weight, preferably at least 85.0% by weight, more preferably at least 90.0% by weight, still more preferably at least 95.0% by weight of a polypropylene composition (PC) as defined above, and most preferably consists of a polypropylene composition (PC) as defined above.

[0137] Therefore, other components may be present in the meltblown fabric according to the invention. Such other components are other polymers, which are preferably also polypropylene-based polymers.

[0138] Selecting appropriate adjunct polymers in a manner that does not negatively impact the desired performance of the meltblown mesh is within the skill level of those skilled in the art.

[0139] In a particularly preferred embodiment of the invention, the meltblown mesh is an electret meltblown mesh.

[0140] Uncharged meltblown mesh can be electrostatically charged to prepare electret meltblown mesh. The electrostatic charging of the meltblown mesh can be any electrostatic charging method known to those skilled in the art. Preferably, the meltblown mesh is charged via electrospinning, corona charging, triboelectric charging, water charging, or in an electric field; more preferably, via corona charging or in an electric field; and most preferably, electrostatic charging is performed in an electric field.

[0141] Preferably, the meltblown mesh of the present invention, more preferably the electret meltblown mesh, is used according to EN 1822-3 at a length of 400 cm, as measured 168 hours after charging. 2 The filtration efficiency determined by the test filter area is at least 75%, more preferably at least 80%, and most preferably at least 85%.

[0142] Furthermore, it is preferred that the quality factor of the meltblown mesh of the present invention, more preferably the electret meltblown mesh, measured 168 hours after charging is at least 2.20, more preferably at least 2.50, and most preferably at least 2.70.

[0143] Further preferred is a meltblown mesh, more preferably an electret meltblown mesh, measured according to EN1822-3 using 400cm [material] 168 hours after charging. 2 The filtration efficiency value determined by the test filter area is at least 98.0% of the filtration efficiency value measured 1 hour after charging, more preferably at least 99.0%, and most preferably at least 100.0%.

[0144] Preferably, the weight per unit area of ​​the meltblown mesh according to the invention is between 1 and 1000 g / m². 2 More preferably, it is within the range of 4 to 500 g / m 2 Within the range of 7 to 250 g / m 2 Within the range, it is still more preferable to be between 8 and 200 g / m 2 Within the range, the optimal value is between 15 and 150 g / m³. 2 Within the range.

[0145] Methods for forming meltblown mesh

[0146] The present invention also relates to a method for preparing a meltblown mesh according to the present invention, comprising the following steps:

[0147] (ai) provides polypropylene (PP1), more preferably propylene homopolymer (HPP1);

[0148] or

[0149] (a.ii) or provide polypropylene (PP2), more preferably propylene homopolymer (HPP2), and a viscosity-reducing cracking agent, preferably a peroxide radical generator;

[0150] and

[0151] (b) Provide a compound according to formula (I);

[0152] (c) The mixture of components provided in steps (a) and (b) is granulated in a granulator to obtain a polypropylene composition (PC) comprising 95.0 to 99.9% by weight of polypropylene (PP), more preferably propylene homopolymer (HPP), and 0.01 to 5.0% by weight of a compound according to formula (I) based on the total weight of the composition.

[0153] (d) Melt-blown the blended granules obtained in step (c); and

[0154] (e) Preferably, the meltblown mesh obtained in step (d) is electrostatically charged to obtain an electret meltblown mesh.

[0155] In one embodiment, the method prepares a non-electrified meltblown mesh, and the method includes the following steps:

[0156] (ai) provides polypropylene (PP1), more preferably propylene homopolymer (HPP1);

[0157] or

[0158] (a.ii) or provide polypropylene (PP2), more preferably propylene homopolymer (HPP2), and a viscosity-reducing cracking agent, preferably a peroxide radical generator;

[0159] and

[0160] (b) Provide a compound according to formula (I);

[0161] (c) The mixture of components provided in steps (a) and (b) is granulated in a granulator to obtain a polypropylene composition (PC) comprising 95.0 to 99.9% by weight of polypropylene (PP), more preferably propylene homopolymer (HPP), based on the total weight of the composition, and 0.01 to 5.0% by weight of a compound according to formula (I) based on the total weight of the composition; and

[0162] (d) Melt-blown the blended granules obtained in step (c).

[0163] In a preferred embodiment, the method prepares an electret meltblown mesh, and the method includes the following steps:

[0164] (ai) provides polypropylene (PP1), more preferably propylene homopolymer (HPP1);

[0165] or

[0166] (a.ii) or provide polypropylene (PP2), more preferably propylene homopolymer (HPP2), and a viscosity-reducing cracking agent, preferably a peroxide radical generator;

[0167] and

[0168] (b) Provide a compound according to formula (I);

[0169] (c) The mixture of components provided in steps (a) and (b) is granulated in a granulator to obtain a polypropylene composition (PC) comprising 95.0 to 99.9% by weight of polypropylene (PP), more preferably propylene homopolymer (HPP), and 0.01 to 5.0% by weight of a compound according to formula (I) based on the total weight of the composition.

[0170] (d) Melt-blown the blended granules obtained in step (c); and

[0171] (e) Electrostatically charge the meltblown mesh obtained in step (d) to obtain an electret meltblown mesh.

[0172] The electrostatic charging of the meltblown mesh in step (e) can be any electrostatic charging method known to those skilled in the art. Preferably, the meltblown mesh is charged by electrospinning, corona charging, triboelectric charging, water charging, or in an electric field; more preferably, by corona charging or in an electric field; and most preferably, by electrostatic charging in an electric field.

[0173] There are no particular restrictions on the meltblowing process for step (d), and it can be any meltblowing procedure known to those skilled in the art.

[0174] The options used for the selection between steps (a.i) and (a.ii) reflect the choice between non-viscosity cracked polypropylene and viscosity cracked polypropylene, respectively.

[0175] If the polypropylene composition (PC) is a viscosity-reducing cracking composition, then step (a.ii) is preferred over step (a.ii). More preferably, a peroxide radical generator is used as the viscosity-reducing cracking agent.

[0176] Typical peroxide radical generators are 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DHBP) (e.g., sold under the trade names Luperox 101 and Trigonox 101), 2,5-dimethyl-2,5-bis(tert-butylperoxy)3-hexyne (DYBP) (e.g., sold under the trade names Luperox 130 and Trigonox 145), dicumyl peroxide (DCUP) (e.g., sold under the trade names Luperox DC and Perkadox BC), di-tert-butyl peroxide (DTBP) (e.g., sold under the trade names Trigonox B and Luperox Di), tert-butylcumyl peroxide (BCUP) (e.g., sold under the trade names Trigonox T and Luperox 801), and bis(tert-butylperoxyisopropyl)benzene (DIPP) (e.g., sold under the trade names Perkadox 14S and Luperox DC).

[0177] Preferred peroxides are 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane (DHBP) and tert-butylperoxide (BCUP).

[0178] The use of a specific peroxide or a mixture of different peroxides is within the scope of this invention.

[0179] Peroxides can be part of the masterbatch.

[0180] In the context of this invention, "masterbatch" refers to a concentrated premix of propylene polymer and additives (in this case, free radical forming agents (peroxides)).

[0181] Based on the total composition of the masterbatch, the peroxide compound may preferably be included in the peroxide masterbatch composition in the range of 1 to 50% by weight, such as 5 to 40% by weight.

[0182] The compound according to formula (I) can be part of the masterbatch.

[0183] In the context of this invention, "masterbatch" refers to a concentrated premix of propylene polymer and additives (in this case, compounds according to formula (I)).

[0184] Based on the total composition of the masterbatch, the compound according to formula (I) may preferably be included in the masterbatch composition in the range of 1 to 50% by weight, such as 5 to 40% by weight.

[0185] use

[0186] In a final aspect, the present invention relates to the use of a compound according to formula (I) for stabilizing the charge in an electret meltblown mesh made of a polypropylene composition (PC), the polypropylene composition (PC) comprising:

[0187] i) 95.0 to 99.99% by weight of polypropylene (PP), preferably propylene homopolymer (HPP), based on the total weight of the composition; and

[0188] ii) 0.01 to 5.0% by weight of the compound according to formula (I) based on the total weight of the composition.

[0189]

[0190] Each R is independently selected from C1 to C6 alkylene, C2 to C6 alkenyl, and single bond; each R' is independently selected from H and C1 to C6 alkyl; and each R” is independently selected from H and C1 to C6 alkyl. 22 Alkyl group, wherein each alkylene group, alkenyl group and alkyl group may optionally be substituted with deuterium or fluorine, and the two substituents on the central benzene ring may be positioned in an ortho, meta or para relationship;

[0191] Based on the total weight of the composition, the total content of polypropylene (PP), more preferably propylene homopolymer (HPP), and the compound according to formula (I) is at least 98.0% by weight, more preferably at least 99.0% by weight, and

[0192] The melt flow rate (MFR2) of the polypropylene composition (PC), as determined according to ISO 1133 at 230°C and under a load of 2.16 kg, is in the range of 400 to 5000 g / 10 min, and the melt temperature (Tm) of the polypropylene composition (PC), as determined according to ISO 11357 by differential scanning calorimetry (DSC), is in the range of 140 to 170°C.

[0193] The charge stability in the electret meltblown mesh is preferably defined as a filtration efficiency value measured 168 hours after charging being at least 98.0% of the filtration efficiency value measured 1 hour after charging, more preferably at least 99.0%, and most preferably at least 100.0%.

[0194] All preferred embodiments and technical features discussed in the foregoing sections are applicable to the uses of the invention.

[0195] Example

[0196] 1. Definition / Measurement Method

[0197] Unless otherwise defined, the following definitions and determination methods apply to the above general description of the invention and the following embodiments.

[0198] MFR2 (230℃) is measured according to ISO 1133 (230℃, 2.16kg load).

[0199] Quantitative analysis of microstructure using NMR spectroscopy

[0200] Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymer. (This is relevant to the following sentence about NMR spectroscopy and its application.) 1 H and 13 A Bruker Advance III 400 NMR spectrometer, operating at 400.15 and 100.62 MHz respectively, recorded quantitative data in solution. 13 C{ 1 ¹H NMR spectroscopy. Nitrogen gas was used for all pneumatic devices at 125°C. 13 All spectra were recorded using a C-optimized 10mm extended temperature probe. Approximately 200 mg of the material, along with chromium acetylacetone (Cr(acac)3), was dissolved in 3 ml of 1,2-tetrachloroethane-d2(TCE- d2In this process, a 65 mM solution of the relaxation agent in the solvent was generated (Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogeneous solution, after initial sample preparation in a heating block, the NMR tube was further heated in a rotary oven for at least 1 hour. After insertion into the magnet, the tube was rotated at 10 Hz. This setup was chosen primarily for high resolution, and it is necessary for accurate ethylene content quantification. A standard single-pulse excitation without NOE was used, employing an optimized tipangle, a 1-second cyclic delay, and a two-stage WALTZ16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128). A total of 6144 (6k) transient signals were acquired for each spectrum.

[0201] Using proprietary computer programs for quantitative analysis 13 C{ 1 The ¹H NMR spectra were processed, integrated, and the relevant quantitative properties were determined from the integration. Using the chemical shifts of the solvent, all chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm. This method allows for comparable references even if this structural unit is not present. Characteristic signals corresponding to the incorporation of ethylene were observed (Cheng, HN, Macromolecules 17 (1984), 1950).

[0202] Because characteristic signals corresponding to 2,1-type red region defects were observed (as described in L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 2000, 100(4), 1253, in Cheng, HN, Macromolecules 1984, 17, 1950, and in WJ. Wang and S. Zhu, Macromolecules 2000, 33, 1157), it is necessary to correct for the effect of region defects on the measured properties. No characteristic signals corresponding to other types of region defects were observed.

[0203] Using the method of Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157), by... 13 C{ 1 The comonomer fraction is quantified by integrating multiple signals across the entire spectral region of the H spectrum. This method was chosen because of its robustness and ability to indicate the presence of regional defects when needed. Slight adjustments were made to the integration region to improve applicability across the entire range of comonomer contents encountered.

[0204] For systems where only isolated ethylene is observed in the PPEPP sequence, the method of Wang et al. is modified to reduce the influence of non-zero integrals from sites that are known to be absent. This method reduces the overestimation of ethylene content in such systems and is achieved by reducing the number of sites used to determine the absolute ethylene content to:

[0205] E=0.5(Sββ+Sβγ+Sβδ+0.5(Sαβ+Sαγ))

[0206] By using this set of sites, the corresponding integral equation becomes:

[0207] E = 0.5(I H +I G +0.5(I C +I D ))

[0208] The same notation was used in the article by Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157). The equation for the absolute propylene content was not changed.

[0209] The molar percentage of comonomer incorporated is calculated from the mole fraction:

[0210] E[mol%] = 100 * fE

[0211] The weight percentage of comonomer incorporated is calculated as a mole fraction:

[0212] E[weight%]=100*(fE*28.06) / ((fE*28.06)+((1-fE)*42.08))

[0213] The analytical method of Kakugo et al. (Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15 (1982) 1150) was used to determine the distribution of comonomer sequences at the ternary group level. This method was chosen for its robustness and for slightly adjusting the integration region to increase applicability to a wider range of comonomer contents.

[0214] Xylene solubles (XCS, wt%): The content of xylene cold solubles (XCS) was determined at 25°C according to ISO 16152; First Edition; 2005-07-01.

[0215] Number average molecular weight (M n ), weight-average molecular weight (M) w ) and molecular weight distribution (M w / M n The ) was determined by gel permeation chromatography (GPC) according to the following method:

[0216] Weight-average molecular weight M w and molecular weight distribution (M w / M n (where M) n It is the number average molecular weight and M w The weight-average molecular weight (MA) was measured using methods based on ISO 16014-1:2003 and ISO 16014-4:2003. A Waters Alliance GPCV 2000 instrument equipped with a refractive index detector and an online viscometer was used, with 3x TSK-gel columns (GMHXL-HT) from TosoHaas and 1,2,4-trichlorobenzene (TCB, stabilized with 200 mg / L of 2,6-di-tert-butyl-4-methylphenol) as the solvent, at 145 °C and a constant flow rate of 1 mL / min. 216.5 μL of sample solution was injected for each analysis. The column set was calibrated using relative calibration with 19 narrow MWD polystyrene (PS) standards ranging from 0.5 kg / mol to 11,500 kg / mol and a set of well-characterized broad polypropylene standards. All samples were prepared by dissolving 5–10 mg of polymer in 10 mL of stabilized TCB (same as the mobile phase) at 160 °C and maintaining the solution under continuous shaking for 3 hours before injection into the GPC instrument.

[0217] DSC analysis, melting temperature (T) m ) and heat of fusion (H f ), crystallization temperature (T) c ) and heat of crystallization (H cMeasurements were performed on samples ranging from 5 to 7 mg using a TAInstrument Q2000 differential scanning calorimeter (DSC). The DSC was operated according to ISO 11357 / Part 3 / Method C2, with a scan rate of 10 °C / min over a temperature range of -30 to +225 °C, in a heating / cooling / heating cycle. The crystallization temperature and heat of crystallization (H₂O) were determined from the cooling step. c The melting temperature and heat of fusion (H) are determined from the second heating step. f ).

[0218] Glass transition temperature T g It was determined by dynamic mechanical analysis according to ISO 6721-7. Measurements were taken at a heating rate of 2°C / min and a frequency of 1Hz between -100°C and +150°C on a compression-molded sample (40x10x1 mm). 3 The above is performed in a twisting mode.

[0219] Net weight: in g / m 2 The unit weight (grams) of the net is determined according to ISO 536:1995.

[0220] Filtration efficiency: The air filtration efficiency is based on EN 1822-3 for flat sheet filter media, using 400cm... 2 The test filter area was determined. Particle rejection was measured using a common aerosol test for diethylhexyl sebacate (DEHS), calculated from the efficiency of a fraction with a diameter of 0.4 μm using a 0.1 μm graduated scale. A 16m filter was used. 3 ·h -1 The airflow corresponds to 0.11 m·s. -1 The air speed.

[0221] Pressure drop (Δp): Pressure drop is measured according to DIN ISO 9237 at an air velocity (permeability) of 500 mm / s.

[0222] Quality Factor: The quality factor (QF) is calculated based on the following formula:

[0223]

[0224] Where FE is the filtration efficiency for particles of 0.4 μm, and Δp is the measured pressure drop (in Pa).

[0225] 2. Example

[0226] The catalyst used in the polymerization process of the precursor propylene homopolymer (HPP2) used in the inventive examples and comparative examples is trans-dimethylsilyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-symmetric-indarsen-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylindene-1-yl]zirconium dichloride, as disclosed as MC-2 in WO 2019 / 179959 A1 (hereinafter referred to as "metallocene"), and is prepared as follows:

[0227] Preparation of MAO-silica support

[0228] The steel reactor, equipped with a mechanical stirrer and filter, was flushed with nitrogen, and the reactor temperature was set to 20°C. Next, 5.0 kg of pre-calcined silica (DM-L-303) from AGC Si-Tech Co., calcined at 600°C, was added from the feed tank, followed by careful pressurization and depressurization with nitrogen using a manual valve. Then, 22 kg of toluene was added. The mixture was stirred for 15 minutes. Next, a 30% by weight solution (9.0 kg) of MAO in toluene from Lanxess was added to the top of the reactor via the feed line over 70 minutes. The reaction mixture was then heated to 90°C and stirred at 90°C for another two hours. The slurry was allowed to settle, and the mother liquor was filtered off. The catalyst was washed twice with toluene (22 kg) at 90°C, followed by settling and filtration. The reactor was cooled to 60°C, and the solids were washed with heptane (22.2 kg). Finally, the MAO-treated SiO2 was dried at 60°C for 2 hours under a nitrogen stream, and then dried under vacuum (-0.5 barg) for 5 hours with stirring. The MAO-treated support was collected as a free-flowing white powder, which was found to contain 12.2% Al by weight.

[0229] Catalyst Synthesis

[0230] 30% by weight MAO (0.7 kg) in toluene was added via a burette to a steel nitrogen-sealed reactor at 20 °C. Then, toluene (5.4 kg) was added with stirring. Metallocene (93 g) was added from a metal cylinder, followed by rinsing with 1 kg of toluene. The mixture was stirred at 20 °C for 60 minutes. Triphenylmethyltetra(pentafluorophenyl)borate was then added from the metal cylinder, followed by rinsing with 1 kg of toluene. The mixture was stirred at room temperature for 1 hour. The resulting solution was added to a cake of MAO-silica support prepared as described above within 1 hour. The cake was allowed to stand for 12 hours, then dried at 60 °C under N2 for 2 hours and then further dried under vacuum (-0.5 barg) with stirring for 5 hours.

[0231] The dried catalyst was sampled as a pink, free-flowing powder containing 13.9% Al and 0.11% Zr.

[0232] HPP2 polymerization and subsequent compounding / viscosity reduction cracking

[0233] The polymerization conditions of HPP2 used in the invention examples are shown in Table 1. Polymerization was carried out in the presence of the above-mentioned catalyst in a Borstar pilot plant, wherein a prepolymerizer, a loop reactor, and a first gas-phase reactor were connected in sequence. The pellet properties given in Table 1 are for the following pellets: wherein the polymer powder produced by the polymerization reactor was compounded and granulated with 1000 ppm of Irganox 1010 (pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, CAS No. 6683-19-8, an antioxidant commercially available from BASF SE(DE)) and 500 ppm of calcium stearate (CAS No. 1592-23-0, commercially available from Faci, IT) using a ZSK 57 twin-screw extruder at a melt temperature of 190°C.

[0234] Table 1: Preparation of precursor propylene homopolymer (HPP2)

[0235] HPP2 Prepolymer reactor temperature [℃] 20 pressure [kPa] 4693 Duration of stay [h] 0.38 Loop reactor temperature [℃] 70 pressure [kPa] 4916 <![CDATA[MFR2]]> [g / 10min] 117 XCS [weight%] 0.5 <![CDATA[Feed H2 / C3 ratio]]> [mol / kmol] 0.41 Split ratio [weight%] 64 GPR temperature [℃] 75 pressure [kPa] 2400 <![CDATA[MFR2]]> [g / 10min] 156 <![CDATA[H2 / C3 ratio]]> [mol / kmol] 3.7 Flow split ratio [weight%] 36 Granular <![CDATA[MFR2]]> [g / 10min] 158 XCS [weight%] 0.9 <![CDATA[T m ]]> [℃] 155 <![CDATA[T c ]]> [℃] 114 <![CDATA[M w ]]> [kg / mol] 103500 <![CDATA[M w / M n ]]> [-] 3.5 mmmm [％] 98.5 2,1 Red-shaped area defects [Moles%] 0.6 Tg below -20℃ [℃] nd Tg above -20℃ [℃] 0

[0236] For the preparation of comparative and inventive examples, a ZSK 57 twin-screw extruder was used to blend and granulate polymer powder produced by the polymerization reactor with 1700 ppm of Trigonox 101 (2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, CAS No. 78-63-7, a peroxide-based viscous cracking agent commercially available from AkzoNobel, NL) and certain additives at a melt temperature of 190°C.

[0237] For Comparative Example 1 (CE1), the additives chosen were 1000 ppm of Irganox 1010 (pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, CAS No. 6683-19-8, an antioxidant commercially available from BASF SE(DE)) and 500 ppm of calcium stearate (CAS No. 1592-23-0, commercially available from Faci, IT). The measured MFR2 for viscous cracking was 656 g / 10 min, the measured Mw was 63700, and the measured MWD (Mw / Mn) was 2.74.

[0238] The additives used in Comparative Example 2 (CE2) were 1000 ppm Irganox 1010, 500 ppm calcium stearate, and 5000 ppm magnesium stearate (CAS No. 557-04-0, commercially available from Faci, IT). The measured MFR2 of viscous cracking was 718 g / 10 min, the measured Mw was 62700, and the measured MWD (Mw / Mn) was 2.74.

[0239] The additive used in Invention Example 1 (IE1) was 500 ppm calcium stearate and 2000 ppm NYLOSTAB S-EED (N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide, CAS No. 42774-15-2, commercially available from Clariant AG, CH). The chemical structure of NYLOSTAB S-EED is given by Formula III.

[0240]

[0241] The measured MFR2 of viscosity-reducing cracking was 822 g / 10 min, the measured Mw was 62550, and the measured MWD (Mw / Mn) was 2.72.

[0242] Then, on the Reicofil MG250 production line, using a spinneret with 460 outlet orifices of 0.4 mm diameter and 35 orifices per inch, the viscous cracked and granulated composition is converted into meltblown wire. The production rate is 45 kg / h / m, the DCD (die-to-collector distance) is 200 mm, the melt temperature is 290°C, and the weight of the produced wire is 25 g / m. 2 .

[0243] The resulting meltblown mesh was charged directly in an electric field after the collector. The generator used was a KNH35 / BNKO2 (manufactured and supplied by Eltex Elektrostatik GmbH) and operated at 20 kV, with electrodes of type R131A3A / 0975 (manufactured and supplied by Eltex Elektrostatik GmbH).

[0244] Figure 1 shows the filtration efficiency of the electret meltblown mesh thus obtained. CE1 represents the case without the use of a charge stabilizer, and it can be clearly seen that the filtration efficiency decays over the measured 168-hour period. CE2 uses magnesium stearate (a known charge stabilizer), while IE1 uses the charge stabilizer of the present invention according to formula (I). As can be seen from the filtration efficiency values ​​on the curves, the use of the charge stabilizer of the present invention results not only in improved filtration efficiency immediately after charging (1 hour), but also in improved charge stability. For IE1, the value measured after 168 hours (87.09) is comparable to the value measured after 1 hour (86.85), while for CE2, the value has decayed from 85.32 to 83.10 over the same time period (a decrease of approximately 3%).

[0245] The quality factor of CE1 (measured after 168 hours) is 1.94, while the quality factor of CE2 is 2.52 and the quality factor of IE1 is 2.79.

Claims

1. A polypropylene composition (PC) comprising: i) 95.0 to 99.99% by weight of polypropylene (PP) based on the total weight of the polypropylene composition; and ii) 0.01 to 5.0% by weight of the compound according to formula (I) based on the total weight of the polypropylene composition. （I） Each R is independently selected from C1 to C6 alkylene, C2 to C6 alkenyl, and single bond; each R' is independently selected from H and C1 to C6 alkyl; and each R” is independently selected from H and C1 to C6 alkyl. 22 Alkyl group, wherein each alkylene group, alkenyl group and alkyl group is optionally substituted with deuterium or fluorine, and the two substituents on the central benzene ring are positioned in an ortho, meta or para relationship; Based on the total weight of the polypropylene composition, the total content of the polypropylene (PP) and each of the compounds according to formula (I) is at least 98.0% by weight, and The polypropylene (PP) wherein the melt flow rate MFR2, as determined according to ISO 1133 at 230°C and under a load of 2.16 kg, is in the range of 400 to 5000 g / 10 min, and the melt temperature Tm, as determined according to ISO 11357 by differential scanning calorimetry (DSC), is in the range of 140 to 170°C.

2. The polypropylene composition (PC) according to claim 1, wherein the polypropylene (PP) is a propylene homopolymer (HPP).

3. The polypropylene composition (PC) according to claim 1 or 2, wherein the total content of the polypropylene (PP) and the various compounds according to formula (I) is at least 99.0% by weight, based on the total weight of the polypropylene composition.

4. The polypropylene composition (PC) according to claim 1 or 2, wherein each R is independently selected from methylene and single bond, each R' is independently selected from C1 to C6 alkyl, each R" is H and the two substituents on the central benzene ring are positioned in a meta-relationship.

5. The polypropylene composition (PC) according to claim 1 or 2, wherein the molecular weight distribution (Mw / Mn) of the polypropylene (PP) as determined by gel permeation chromatography is in the range of 1.0 to 6.

0.

6. The polypropylene composition (PC) according to claim 1 or 2, wherein the weight-average molecular weight (Mw) of the polypropylene (PP) as determined by gel permeation chromatography is in the range of 25,000 to 85,000.

7. The polypropylene composition (PC) according to claim 1 or 2, wherein the polypropylene (PP) is... 13 The content of defects in the 2,1 red region, as determined by C-NMR spectroscopy, is in the range of 0.01 to 1.5 mol% and / or the melting temperature Tm of the polypropylene (PP), as determined by differential scanning calorimetry (DSC) according to ISO 11357, is in the range of 151 to 160 °C.

8. The polypropylene composition (PC) according to claim 1 or 2, wherein the polypropylene (PP) is free from... 13 The defects in the 2,1 reddish region, as determined by C-NMR spectroscopy, and / or the melting temperature Tm of the polypropylene (PP), as determined by differential scanning calorimetry (DSC) according to ISO 11357, are in the range of 155 to 170 °C.

9. The polypropylene composition (PC) according to claim 1 or 2, wherein the polypropylene (PP) is the product of viscous cracking of precursor polypropylene (PP2) using a viscous cracking agent.

10. The polypropylene composition (PC) according to claim 9, wherein the precursor polypropylene (PP2) is a precursor propylene homopolymer (HPP2).

11. The polypropylene composition (PC) according to claim 9, wherein the viscosity-reducing cracking agent is a peroxide radical generator.

12. The polypropylene composition (PC) according to claim 9, wherein the viscosity reduction cracking ratio calculated by dividing the melt flow rate MFR2 of the polypropylene (PP) by the melt flow rate MFR2 of the precursor polypropylene (PP2) is in the range of 3.0 to 40, wherein each melt flow rate MFR2 is determined according to ISO 1133 at 230°C and a load of 2.16 kg.

13. The polypropylene composition (PC) according to claim 9, wherein the melt flow rate (MFR2) of the precursor polypropylene (PP2), as determined according to ISO 1133 at 230°C and under a load of 2.16 kg, is in the range of 50 to 399 g / 10 min.

14. A meltblown mesh made from a polypropylene composition (PC) according to any one of claims 1 to 13.

15. The meltblown mesh according to claim 14, wherein it is an electret meltblown mesh.

16. A method for preparing the meltblown mesh according to claim 14 or 15, comprising the following steps: (ai) Provides polypropylene (PP1) for preparing polypropylene compositions (PC); or (a.ii) or provide precursor polypropylene (PP2) and viscosity-reducing cracking agent; and (b) Provide the compound according to formula (I); (c) The mixture of components provided in steps (a) and (b) is granulated in a granulator to obtain the polypropylene composition (PC) comprising 95.0 to 99.9% by weight of polypropylene (PP) based on the total weight of the polypropylene composition, and 0.01 to 5.0% by weight of the compound according to formula (I) based on the total weight of the polypropylene composition. (d) Melt-blown the blended granules obtained in step (c).

17. The method of claim 16, wherein the polypropylene (PP1) used to prepare the polypropylene composition (PC) is a propylene homopolymer (HPP1) used to prepare the polypropylene composition (PC).

18. The method of claim 16, wherein the precursor polypropylene (PP2) is a precursor propylene homopolymer (HPP2).

19. The method according to claim 16 or 18, wherein the viscosity-reducing cracking agent is a peroxide radical generator.

20. The method according to any one of claims 16 to 18, further comprising: The meltblown mesh obtained in step (d) is electrostatically charged to obtain an electret meltblown mesh.

21. The method according to any one of claims 16 to 18, wherein the meltblown mesh has been electrostatically charged via triboelectricity or in an electric field.

22. The method according to any one of claims 16 to 18, wherein the meltblown mesh has been electrostatically charged by electrospinning, corona charging or water charging.

23. Use of the compound according to formula (I) for stabilizing the charge in an electret meltblown mesh made of a polypropylene composition (PC), said polypropylene composition (PC) comprising: i) 95.0 to 99.99% by weight of polypropylene (PP) based on the total weight of the polypropylene composition; and ii) 0.01 to 5.0% by weight of the compound according to formula (I) based on the total weight of the polypropylene composition. （I） Each R is independently selected from C1 to C6 alkylene, C2 to C6 alkenyl, and single bond; each R' is independently selected from H and C1 to C6 alkyl; and each R” is independently selected from H and C1 to C6 alkyl. 22 Alkyl group, wherein each alkylene group, alkenyl group and alkyl group is optionally substituted with deuterium or fluorine, and the two substituents on the central benzene ring are positioned in an ortho, meta or para relationship; Based on the total weight of the polypropylene composition, the total content of the polypropylene (PP) and each of the compounds according to formula (I) is at least 98.0% by weight, and The polypropylene (PP) wherein the melt flow rate MFR2, as determined according to ISO 1133 at 230°C and under a load of 2.16 kg, is in the range of 400 to 5000 g / 10 min, and the melt temperature Tm, as determined according to ISO 11357 by differential scanning calorimetry (DSC), is in the range of 140 to 170°C.

24. The use according to claim 23, wherein the polypropylene (PP) is a propylene homopolymer (HPP).

25. The use according to claim 23 or 24, wherein the total content of the polypropylene (PP) and each of the compounds according to formula (I) is at least 99.0% by weight, based on the total weight of the polypropylene composition.

26. The use according to claim 23 or 24, wherein stabilizing the charge in the electret meltblown mesh is defined as measured 168 hours after charging using 400 cm according to EN 1822-3. 2 The filtration efficiency value determined by the test filter area is at least 98.0% of the filtration efficiency value measured 1 hour after charging.

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