Multilayer nonwoven structure

Abstract

A nonwoven fabric (NF) comprising a multilayer structure, the multilayer structure comprising: i) at least one meltblown layer (M) comprising meltblown fibers (MBF) comprising a first propylene polymer (PP1) having: a) an amount of 2,1- region defects in the range of 0.0 to 0.1 mol%; and b) a melting temperature T in the range of 155 to 170°C. m ii) at least one spunbond layer comprising spunbond fiber (SBF) comprising a second propylene polymer (PP2) having: a) an amount of 2,1- region defects in the range of 0.4 to 1.5 mol%; and b) a melt temperature T in the range of 145 to 160 °C. m The melting temperature T of the first polypropylene polymer m (PP1) has a higher melting temperature than the first polypropylene polymer (T). m (PP2) at least 5.0°C.

Description

Technical Field

[0001] This invention relates to a nonwoven fabric (NF) comprising at least one meltblown layer (M) and at least one spunbond layer (S), wherein the layer (M) comprises meltblown fibers and the layer (S) comprises spunbond fibers, wherein the meltblown fibers and the spunbond fibers comprise a propylene polymer. The invention also relates to articles comprising the nonwoven fabric (NF). Background Technology

[0002] Nonwoven polypropylene mesh is widely used in filtration and hygiene applications. In the field of nonwoven polypropylene mesh, multi-layer structures, such as spunbond / meltblown / spunbond (SMS) multi-layer structures, are often used to meet different requirements. For example, in the classic SMS structure used in hygiene products, the spunbond layer acts as a support and provides mechanical properties, while the meltblown layer is much thinner and primarily serves as a functional layer. A good SMS structure should possess a combination of good mechanical properties and good barrier properties. Due to its excellent performance at low production costs, the SMS structure is widely used in hygiene products.

[0003] SMS structures are currently produced using a continuous process, in which a first spunbond layer is manufactured via a first spinneret, followed by the deposition of a meltblown layer on top of the spunbond layer using a meltblown bundle, and then a second spunbond layer is deposited on top of the meltblown layer using a second spinneret, thus bonding the three layers together to obtain the SMS structure. Because these process steps are quite challenging, the properties of the polypropylene used for the spunbond and meltblown layers must be adjusted accordingly.

[0004] In recent years, reducing the environmental impact of plastic waste has received increasing attention. In many cases, this can be achieved by recycling waste polyolefins to produce new products in a circular economy. Since SMS structures are commonly used in hygiene products, recycling and / or reuse of these products is impractical. Therefore, it is desirable to reduce the impact of these products by reducing the amount of polymer present, i.e., by producing SMS structures with particularly low basis weights (weight per unit area of ​​fabric).

[0005] For example, WO 2018 / 104388 A1 discloses a multilayer nonwoven fabric comprising meltblown (M) layers and spunbond (S) layers in an SMMS structure, all layers containing polypropylene based on a Ziegler-Natta (ZN) catalyst. However, the resulting fabric still exhibits insufficient hydrohead strength. Furthermore, both WO 2011 / 092092 A1 and WO 2015 / 082379A1 disclose meltblown fibers and webs made from polypropylene homopolymers and copolymers based on a Ziegler-Natta (ZN) catalyst, which can be considered to have similarly insufficient performance in multilayer nonwoven fabrics.

[0006] Therefore, there is a need in the art for polypropylene-containing SMS structures that exhibit good barrier properties while maintaining high levels of mechanical properties. Furthermore, the basis weight should be advantageously low without compromising these properties.

[0007] Therefore, the object of the present invention is to provide nonwoven fabrics (NF) characterized by excellent barrier properties, mechanical properties and low basis weight. Summary of the Invention

[0008] The discovery of this invention is that the SMS structure comprising a spunbond layer made of polypropylene prepared in the presence of a single active site catalyst and a meltblown layer made of polypropylene produced in the presence of a Ziegler-Natta catalyst is characterized by increased hydrostatic pressure and improved mechanical properties.

[0009] Therefore, the present invention relates to a nonwoven fabric (NF) comprising a multilayer structure, the multilayer structure including

[0010] i) at least one meltblown layer (M) comprising meltblown fibers (MBF), the meltblown fibers (MBF) comprising a first propylene polymer (PP1), the first propylene polymer (PP1) having:

[0011] a) Through the range of 0.0 to 0.1 mol%. 13 The amount of defects in the 2,1-region determined by C-NMR spectroscopy; and

[0012] b) Melting temperature T, determined by differential scanning calorimetry (DSC), in the range of 155 to 170 °C. m ,

[0013] ii) At least one spunbond layer comprising spunbond fiber (SBF), the spunbond fiber (SBF) comprising a second propylene polymer (PP2), the second propylene polymer (PP2) having:

[0014] a) Passing within the range of 0.4 to 1.5 mol%. 13 The amount of defects in the 2,1-region determined by C-NMR spectroscopy; and

[0015] b) Melting temperature T, determined by differential scanning calorimetry (DSC), in the range of 145 to 160 °C. m ,

[0016] The melting temperature T of the first polypropylene polymer m (PP1) has a higher melting temperature than the first polypropylene polymer (T). m (PP2) at least 5.0°C.

[0017] In other embodiments, the present invention relates to a method for producing the nonwoven fabric of the present invention, the method comprising the following steps:

[0018] a) The first spunbond layer (S1) is produced by depositing spunbond fibers (SBF) through a spinneret.

[0019] b) Optionally, at least one additional spunbond layer (S) is produced by depositing spunbond fibers (SBF) onto the first spunbond layer (S1) obtained in step a) through at least one additional spinneret, thereby obtaining a multilayer structure comprising two or more, such as two or three spunbond layers (S).

[0020] c) A first meltblown layer (M1) is produced by depositing meltblown fibers (MBF) onto the first spunbond layer (S1) obtained in step a) or the outermost spunbond layer (S) obtained in step b) using an extruder, thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S) and a meltblown layer (M).

[0021] d) Optionally, at least one additional meltblown layer (M) is produced by depositing meltblown fibers (MBF) onto the first meltblown layer (M1) obtained in step c) using at least one additional extruder, thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S), and two or more, such as two or three meltblown layers (M).

[0022] e) A second spunbond layer (S2) is produced by depositing spunbond fibers (SBF) through a spinneret onto the first meltblown layer (M1) obtained in step c) or onto the outermost meltblown layer (M) obtained in step d), thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S), or one or more, such as one, two, or three meltblown layers (M) and one spunbond layer (S), and

[0023] f) Optionally, at least one additional spunbond layer (S) is produced by depositing spunbond fibers (SBF) onto the second spunbond layer (S2) obtained in step e) through at least one additional spinneret, thereby obtaining a multilayer structure comprising one or more, such as one, two or three spunbond layers (S), one or more, such as one, two or three meltblown layers (M), and two or more, such as one, two or three spunbond layers (S).

[0024] The present invention also relates to an article comprising a nonwoven fabric (NF) as described above, wherein the article is selected from filter media (filters), diapers, sanitary napkins, panty liners, adult incontinence products, protective clothing, surgical drapes, surgical gowns and surgical garments.

[0025] definition

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although any methods and materials similar to or equivalent to those described herein may be used in practice to test the invention, preferred materials and methods are described herein. In describing and claiming protection for this invention, the following terms will be used according to the definitions stated below.

[0027] Unless otherwise expressly stated, the use of the terms “a”, “an”, etc., refers to one or more.

[0028] According to the present invention, the term "propylene homopolymer" refers to polypropylene that is substantially composed of propylene units, i.e., polypropylene composed of at least 99.0 mol%, more preferably at least 99.5 mol%, even more preferably at least 99.8 mol%, such as at least 99.9 mol%. In another embodiment, only propylene units are detectable, i.e., only propylene has been polymerized.

[0029] 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 number of carbon atoms. Unless otherwise specified, the following amounts are given in mole percent.

[0030] For propylene homopolymers and propylene random copolymers, there is typically only one glass transition temperature. Detailed Implementation

[0031] Nonwoven fabrics (NF)

[0032] The nonwoven fabric (NF) according to the present invention comprises at least one meltblown layer (M) and at least one spunbond layer (S).

[0033] Preferably, the nonwoven fabric (NF) is a multilayer structure such as an SMS-web, which includes a spunbond layer (S), a meltblown layer (M), and another spunbond layer (S).

[0034] According to the present invention, the terms “SMS-web” or “SMS structure” are interchangeable and represent a multilayer structure comprising at least one meltblown layer (M) and at least one spunbond layer (S), the multilayer structure being obtained by depositing each layer on top of the subsequent layers.

[0035] Alternatively, the multilayer structure may also include multiple meltblown web layers (M) and spunbond web layers (S), such as an SSMMS structure.

[0036] Therefore, preferably, the multilayer structure includes the following layers in a given order, and more preferably consists of the following layers in a given order:

[0037] i) At least one spunbond layer (S) comprising spunbond fibers (S);

[0038] ii) at least one meltblown layer (M) comprising meltblown fibers (M); and

[0039] iii) At least one spunbond layer (S) comprising spunbond fibers (S),

[0040] Each instance of the spunbond layer (S) may be the same or different, and each instance of the meltblown layer (M) may be the same or different.

[0041] Particularly preferred is that the nonwoven fabric (NF) has an SSMMS structure, i.e., it consists of two meltblown layers (M) surrounded by three spunbond layers (S). Therefore, it is particularly preferred that the multilayer structure consists of the following layers in a given order:

[0042] i) Two spunbond layers (S) containing spunbond fibers (S);

[0043] ii) Two meltblown layers (M) containing meltblown fibers (M); and

[0044] iii) A spunbond layer (S) containing spunbond fibers (S),

[0045] Each instance of the spunbond layer (S) may be the same or different, and each instance of the meltblown layer (M) may be the same or different.

[0046] Particularly preferred is that the instances of the spunbond layer (S) are identical and / or the instances of the meltblown layer (M) are identical. In one embodiment, the instances of the spunbond layer (S) are identical, and the instances of the meltblown layer (M) are also identical.

[0047] As summarized above, the nonwoven fabric (NF) according to the invention is characterized by high barrier properties. Therefore, it is preferred that the hydrostatic pressure of the nonwoven fabric (NF) is at least 100 mbar, more preferably at least 130 mbar, and even more preferably 160 mbar.

[0048] The weight per unit area of ​​nonwoven fabrics (NF) depends largely on the end use; however, it is preferred that the nonwoven fabric has a weight per unit area of ​​6.0 to 100 g / m². 2 More preferably, it is within the range of 9.0 to 50 g / m 2 Within the range, the most preferred value is 12 to 20 g / m³. 2 The weight per unit area (i.e., grams) within the range determined according to ISO 536:1995.

[0049] As outlined above, the nonwoven fabric (NF) according to the invention is characterized by high mechanical properties. Therefore, it is preferred that the tensile strength of the nonwoven fabric (NF) in the machine transverse (F-CD) direction is at least 100 N / 5 cm, more preferably at least 150 N / 5 cm, and even more preferably 180 N / 5 cm.

[0050] Nonwoven fabrics (NF) can be obtained in a continuous process including the following steps.

[0051] a) The first spunbond layer (S1) is produced by depositing spunbond fibers (SBF) through a spinneret.

[0052] b) Optionally, at least one additional spunbond layer (S) is produced by depositing spunbond fibers (SBF) onto the first spunbond layer (S1) obtained in step a) through at least one additional spinneret, thereby obtaining a multilayer structure comprising two or more, such as two or three spunbond layers (S).

[0053] c) A first meltblown layer (M1) is produced by depositing meltblown fibers (MBF) onto the first spunbond layer (S1) obtained in step a) or the outermost spunbond layer (S) obtained in step b) using an extruder, thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S) and a meltblown layer (M).

[0054] d) Optionally, at least one additional meltblown layer (M) is produced by depositing meltblown fibers (MBF) onto the first meltblown layer (M1) obtained in step c) using at least one additional extruder, thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S), and two or more, such as two or three meltblown layers (M).

[0055] e) A second spunbond layer (S2) is produced by depositing spunbond fibers (SBF) through a spinneret onto the first meltblown layer (M1) obtained in step c) or onto the outermost meltblown layer (M) obtained in step d), thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S), or one or more, such as one, two, or three meltblown layers (M) and one spunbond layer (S), and

[0056] f) Optionally, at least one additional spunbond layer (S) is produced by depositing spunbond fibers (SBF) onto the second spunbond layer (S2) obtained in step e) through at least one additional spinneret, thereby obtaining a multilayer structure comprising one or more, such as one, two or three spunbond layers (S), one or more, such as one, two or three meltblown layers (M), and two or more, such as one, two or three spunbond layers (S).

[0057] As outlined above, preferably, the nonwoven fabric (NF) consists of two meltblown layers (M) surrounded by three spunbond layers (S).

[0058] Therefore, it is particularly preferred that the nonwoven fabric (NF) is obtained in a continuous process including the following steps.

[0059] a) The first spunbond layer (S1) is produced by depositing spunbond fibers (SBF) through a spinneret.

[0060] b) Another spunbond layer (S1a) is produced by depositing spunbond fibers (SF) onto the first spunbond layer (S1) obtained in step a) through a spinneret, thereby obtaining a multilayer structure comprising two spunbond layers (S).

[0061] c) The first meltblown layer (M1) is produced by depositing meltblown fibers (MBF) onto the additional spunbond layer (S1a) obtained in step b) using an extruder, thereby obtaining a multilayer structure comprising two spunbond layers (S) and one meltblown layer (M) in sequence.

[0062] d) A second meltblown layer (M2) is produced by depositing meltblown fibers (MBF) onto the first meltblown layer (M1) obtained in step c) using a separate extruder, thereby obtaining a multilayer structure comprising two spunbond layers (S) and two meltblown layers (M) in sequence.

[0063] e) A second spunbond layer (S2) is produced by depositing spunbond fiber (SBF) onto the second meltblown layer (M2) obtained in step d) through a spinneret, thereby obtaining a multilayer structure comprising two spunbond layers (S), two meltblown layers (M), and one spunbond layer (S) in sequence.

[0064] The present invention also relates to a method for producing nonwoven fabrics (NF) as described above and as described below, the method comprising, more preferably, the following steps:

[0065] a) The first spunbond layer (S1) is produced by depositing spunbond fibers (SBF) through a spinneret.

[0066] b) Optionally, at least one additional spunbond layer (S) is produced by depositing spunbond fibers (SBF) onto the first spunbond layer (S1) obtained in step a) through at least one additional spinneret, thereby obtaining a multilayer structure comprising two or more, such as two or three spunbond layers (S).

[0067] c) A first meltblown layer (M1) is produced by depositing meltblown fibers (MBF) onto the first spunbond layer (S1) obtained in step a) or the outermost spunbond layer (S) obtained in step b) using an extruder, thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S) and a meltblown layer (M).

[0068] d) Optionally, at least one additional meltblown layer (M) is produced by depositing meltblown fibers (MBF) onto the first meltblown layer (M1) obtained in step c) using at least one additional extruder, thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S), and two or more, such as two or three meltblown layers (M).

[0069] e) A second spunbond layer (S2) is produced by depositing spunbond fibers (SBF) through a spinneret onto the first meltblown layer (M1) obtained in step c) or onto the outermost meltblown layer (M) obtained in step d), thereby obtaining a multilayer structure comprising one or more, such as one, two, or three spunbond layers (S), or one or more, such as one, two, or three meltblown layers (M) and one spunbond layer (S), and

[0070] f) Optionally, at least one additional spunbond layer (S) is produced by depositing spunbond fibers (SBF) onto the second spunbond layer (S2) obtained in step e) through at least one additional spinneret, thereby obtaining a multilayer structure comprising one or more, such as one, two or three spunbond layers (S), one or more, such as one, two or three meltblown layers (M), and two or more, such as one, two or three spunbond layers (S).

[0071] As outlined above, preferably, the nonwoven fabric (NF) consists of two meltblown layers (M) surrounded by three spunbond layers.

[0072] Therefore, it is particularly preferred that the method for producing the nonwoven fabric (NF) of the present invention includes the following steps, more preferably consisting of the following steps:

[0073] a) The first spunbond layer (S1) is produced by depositing spunbond fibers (SBF) through a spinneret.

[0074] b) Another spunbond layer (S1a) is produced by depositing spunbond fibers (SF) onto the first spunbond layer (S1) obtained in step a) through a spinneret, thereby obtaining a multilayer structure comprising two spunbond layers (S).

[0075] c) The first meltblown layer (M1) is produced by depositing meltblown fibers (MBF) onto the additional spunbond layer (S1a) obtained in step b) using an extruder, thereby obtaining a multilayer structure comprising two spunbond layers (S) and one meltblown layer (M) in sequence.

[0076] d) A second meltblown layer (M2) is produced by depositing meltblown fibers (MBF) onto the first meltblown layer (M1) obtained in step c) using a separate extruder, thereby obtaining a multilayer structure comprising two spunbond layers (S) and two meltblown layers (M) in sequence.

[0077] e) A second spunbond layer (S2) is produced by depositing spunbond fiber (SBF) onto the second meltblown layer (M2) obtained in step d) through a spinneret, thereby obtaining a multilayer structure comprising two spunbond layers (S), two meltblown layers (M), and one spunbond layer (S) in sequence.

[0078] The meltblown layer (M) and spunbond layer (S) will be described in more detail below.

[0079] Meltblown layer (M)

[0080] As outlined above, the nonwoven fabric (NF) according to the invention comprises at least one meltblown layer (M) comprising meltblown fibers (MBF).

[0081] Preferably, meltblown fibers (MBF) constitute at least 80% by weight of the meltblown layer (M), more preferably at least 90% by weight, and even more preferably at least 95% by weight. Particularly preferred is that the meltblown layer (M) is composed of meltblown fibers (MBF).

[0082] Meltblown fiber (MBF) is obtained from a first propylene polymer (PP1).

[0083] The first propylene polymer (PP1) can be a propylene copolymer or a propylene homopolymer, the latter being preferred.

[0084] In the case where the first propylene polymer (PP1) is a propylene copolymer, the first propylene polymer (PP1) comprises monomers that can be copolymerized with propylene, such as comonomers of ethylene and / or C4 to C8 α-olefins, particularly ethylene and / or C4 to C6 α-olefins, such as 1-butene and / or 1-hexene. Preferably, the first propylene polymer (PP1) according to the invention comprises monomers that can be copolymerized with propylene selected from the group consisting of ethylene, 1-butene, and 1-hexene, particularly composed of monomers that can be copolymerized with propylene selected from the group consisting of ethylene, 1-butene, and 1-hexene. More particularly, the first propylene polymer (PP1) of the invention (in addition to propylene) also comprises units that can be derived from ethylene and / or 1-butene. In a preferred embodiment, the first propylene polymer (PP1) comprises only units derived from ethylene and propylene.

[0085] The comonomer content of the first propylene polymer (PP1) is preferably in the range of 0.0 to 5.0 mol%, more preferably in the range of 0.0 to 3.0 mol%, even more preferably in the range of 0.0 to 1.0 mol%, and most preferably in the range of 0.0 to 0.5 mol%.

[0086] Particularly preferred is that the first propylene polymer (PP1) is a first propylene homopolymer (H-PP1).

[0087] A preferred requirement for the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is its relatively high melt flow rate, which differs from other polymers used, for example, in meltblown technology for the production of fibers. Therefore, it is preferred that the propylene homopolymer in this invention has a melt flow rate MFR2 (final) (230°C / 2.16 kg) measured according to ISO 1133 in the range of 450 to 2000 g / 10 min. More preferably, the propylene homopolymer has a melt flow rate MFR2 (final) (230°C / 2.16 kg) measured according to ISO 1133 in the range of 700 to 1800 g / 10 min, even more preferably in the range of 900 to 1600 g / 10 min, and most preferably in the range of 1100 to 1500 g / 10 min.

[0088] Unless otherwise stated, in this invention, the melt flow rate (230°C / 2.16kg) of the term first propylene polymer (PP1) (such as first propylene homopolymer (H-PP1)) refers to the melt flow rate (230°C / 2.16kg) after de-thickening cracking.

[0089] Therefore, it is preferred that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has been de-thickened and cracked.

[0090] Therefore, the melt flow rate MFR2(initial) (230°C / 2.16 kg) (i.e., the melt flow rate before viscous cracking) of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is much lower, such as 15 to 150 g / 10 min. For example, the melt flow rate MFR2(initial) (230°C / 2.16 kg) of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) before viscous cracking is 30 to 120 g / 10 min, such as 50 to 100 g / 10 min.

[0091] In one embodiment of the invention, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has been subjected to viscosity-reducing cracking, wherein the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) satisfies inequality (I):

[0092]

[0093] MFR(final) is the melt flow rate MFR2 (230°C) after viscosity reduction cracking, as determined according to ISO 1133, and MFR(initial) is the melt flow rate MFR2 (230°C) before viscosity reduction cracking, as determined according to ISO 1133.

[0094] More preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) satisfies inequality (Ia):

[0095]

[0096] More preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) satisfies inequality (Ib):

[0097]

[0098] Most preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) satisfies inequality (Ic):

[0099]

[0100] More preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) satisfies inequality (II):

[0101]

[0102] Wherein, MWD (final) is the molecular weight distribution (Mw / Mn) determined by gel permeation chromatography after viscosity reduction cracking, and MWD (initial) is the molecular weight distribution (Mw / Mn) determined by gel permeation chromatography before viscosity reduction cracking.

[0103] More preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) satisfies inequality (IIa):

[0104]

[0105] More preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) satisfies inequality (IIb):

[0106]

[0107] Most preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) satisfies inequality (IIc):

[0108]

[0109] As mentioned above, a characteristic of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has been subjected to viscosity reduction cracking. Preferred mixing equipment suitable for viscosity reduction cracking includes discontinuous and continuous kneaders, twin-screw extruders and single-screw extruders with special mixing sections, as well as co-kneaders.

[0110] By subjecting the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) to viscous cracking with heat or under more controlled conditions, the molar mass distribution (MWD) becomes narrower because the long molecular chains are more easily broken or sheared, and the molar mass M decreases, corresponding to an increase in MFR2. MFR2 increases with increasing peroxide dosage.

[0111] This viscosity-reducing cracking can be carried out in any known manner, such as by using a peroxide viscosity-reducing cracking agent. Typical viscosity-reducing cracking agents 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)hexyn-3 (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-butylperoxide (DTBP) (e.g., sold under the trade names Trigonox B and Luperox Di), tert-butyl-cumyl-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). The appropriate amount of peroxide used according to the present invention is known in principle to those skilled in the art and can be readily calculated based on the amount of the first propylene polymer (PP1) to be viscous-reduced (e.g., the first propylene homopolymer (H-PP1)), the MFR2 (230°C / 2.16 kg) value of the first propylene polymer (PP1) to be viscous-reduced (e.g., the first propylene homopolymer (H-PP1)), and the desired target MFR2 (230°C / 2.16 kg) of the product to be obtained. Therefore, based on the total amount of the first propylene polymer (PP1) used (e.g., the first propylene homopolymer (H-PP1)), the typical amount of the peroxide viscous-reducing cracking agent is 0.005 to 0.7 wt%, more preferably 0.01 to 0.4 wt%.

[0112] Typically, the viscosity-reducing cracking according to the invention is carried out in an extruder, thus, under suitable conditions, an increase in melt flow rate is obtained. During viscosity-reducing cracking, the higher molar mass chains of the starting product break down statistically more frequently than the lower molar mass molecules, resulting in an overall decrease in average molecular weight and an increase in melt flow rate as described above.

[0113] Preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is obtained by viscous cracking of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)), and more preferably by viscous cracking of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) using peroxide.

[0114] More precisely, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) can be obtained by de-viscosifying and cracking the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) in an extruder, preferably by using a peroxide as described above.

[0115] Preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is isotactic. Therefore, it is preferred that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has a considerably high pentamelid concentration (mmmm%), i.e., greater than 92.0%, more preferably greater than 92.5%, such as greater than 92.5 to 98.5%, and even more preferably at least 93.0%, such as in the range of 93.0 to 97.5%.

[0116] Another characteristic of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is the low amount of misinserted propylene in the polymer chain. This indicates that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is produced in the presence of a Ziegler-Natta catalyst, preferably in the presence of a Ziegler-Natta catalyst (ZN-C) as defined in more detail below. Therefore, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is characterized by a low amount of misinserted propylene in the polymer chain. 13 2,1 erythroline defects were measured by C-NMR spectroscopy, specifically within the range of 0.0 to 0.1 mol%. In a particularly preferred embodiment, no 2,1 erythroline defects were detected.

[0117] Preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is characterized by a xylene cold soluble content (XCS) in the range of 2.0 to 8.0% by weight. Therefore, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) preferably has a xylene cold soluble content (XCS) in the range of 3.0 to 7.0% by weight, more preferably in the range of 4.0 to 6.0% by weight, and even more preferably in the range of 4.5 to 5.5% by weight.

[0118] The amount of xylene cold solubles (XCS) also indicates that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) preferably does not contain any elastomeric polymer components, such as ethylene propylene rubber. In other words, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) should not be a multiphase polypropylene, i.e., a system consisting of a polypropylene matrix in which an elastomeric phase is dispersed.

[0119] The amount of xylene cold solubles (XCS) also indicates that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) preferably does not contain an elastomeric (co)polymer forming inclusions as a second phase for improving mechanical properties. Conversely, polymers containing elastomeric (co)polymers as second-phase inserts will be referred to as multiphase and are preferably not part of this invention. The presence of a second phase, or so-called inclusion, is visible, for example, by high-resolution microscopy (such as electron microscopy or atomic force microscopy) or by dynamic mechanical thermal analysis (DMTA). In particular, in DMTA, the presence of a multiphase structure can be determined by the presence of at least two distinct glass transition temperatures.

[0120] Therefore, it is preferred that the first propylene polymer (PP1) according to the present invention (such as the first propylene homopolymer (H-PP1)) does not have a glass transition temperature below -30°C, preferably below -25°C, and more preferably below -20°C.

[0121] In another preferred embodiment, the glass transition temperature of the first propylene polymer (PP1) according to the invention (such as the first propylene homopolymer (H-PP1)) is in the range of -12 to 5°C, more preferably in the range of -10 to 2°C.

[0122] Furthermore, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is characterized by a relatively high molecular weight. Therefore, it is preferred that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has a weight-average molecular weight Mw (initial) of higher than 100,000 kg / mol before viscous cracking, more preferably in the range of 100,000 to 200,000 kg / mol, and even more preferably in the range of 110,000 kg / mol to 150,000 kg / mol.

[0123] In addition or alternatively relative to the preceding paragraph, it is preferred that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has an initial molecular weight distribution (Mw(initial) / Mn(initial)) higher than 4.0, more preferably in the range of 4.0 to 10.0, and even more preferably in the range of 5.0 to 8.0 before viscous cracking.

[0124] As outlined above, preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has been de-thickened and cracked.

[0125] Therefore, it is preferred that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has a final molecular weight distribution (Mw(final) / Mn(final)) in the range of 2.5 to 5.0, more preferably in the range of 3.0 to 4.5, and most preferably in the range of 3.5 to 4.0 after viscous cracking.

[0126] Furthermore, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is preferably a crystalline propylene homopolymer. The term "crystalline" indicates that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has a relatively high melting temperature. Therefore, in this invention, unless otherwise stated, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is considered to be crystalline.

[0127] The first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has a melting temperature T measured by differential scanning calorimetry (DSC) in the range of 155 to 170°C, more preferably in the range of 156 to 165°C, and most preferably in the range of 157 to 163°C. m .

[0128] In addition, the melting temperature T of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) m The melting temperature T of the second propylene polymer (PP2) m The melting temperature T of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is at least 5.0°C, more preferably at least 6.0°C, still more preferably at least 7.0°C, even more preferably at least 8.0°C, and most preferably at least 9.0°C. m Preferably, the melting temperature T of the second propylene polymer (PP2) is higher. m The temperature should not exceed 30.0℃.

[0129] Furthermore, preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has a crystallization temperature Tc measured by differential scanning calorimetry (DSC) of 115°C or greater, more preferably in the range of 115 to 130°C, and even more preferably in the range of 120 to 125°C.

[0130] The first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is preferably characterized by high stiffness. Therefore, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) preferably has a considerably high tensile modulus. Therefore, it is preferred that the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) has a tensile modulus of at least 1200 MPa, more preferably in the range of 1200 to 2000 MPa, and even more preferably in the range of 1300 to 1800 MPa, measured at 23°C according to ISO 527-1 (crosshead speed 1 mm / min).

[0131] Preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is obtained by polymerizing propylene in the presence of a Ziegler-Natta catalyst as defined below. More preferably, the first propylene polymer (PP1) according to the invention (such as the first propylene homopolymer (H-PP1)) is obtained by using a Ziegler-Natta catalyst via a method defined in detail below.

[0132] The first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) may include two fractions, more preferably it may consist of two fractions, namely a first fraction (PP1a) of the first propylene polymer and a second fraction (PP1b) of the first propylene polymer. Preferably, the weight ratio [(PP1a):(PP1b)] between the first fraction (PP1a) of the first propylene polymer and the second fraction (PP1b) of the first propylene homopolymer is 70:30 to 40:60, more preferably 65:35 to 45:55.

[0133] The melt flow rates of the first fraction (PP1a) of the first propylene polymer and the second fraction (PP1b) of the first propylene homopolymer may be different. However, it is preferred that the melt flow rates MFR2 (230°C) of the first fraction (PP1a) of the first propylene polymer and the second fraction (PP1b) of the first propylene homopolymer are almost identical, i.e., the difference calculated based on the lower of the two values ​​does not exceed 15%, preferably not more than 10%, such as not more than 7%.

[0134] The first propylene polymer (PP1) of the present invention (such as the first propylene homopolymer (H-PP1)) may contain other components. However, it is preferred that the first propylene polymer (PP1) of the present invention (such as the first propylene homopolymer (H-PP1)) contains only the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) as defined in the present invention as a polymer component. Therefore, based on the total first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)), the amount of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) may not reach 100.0% by weight. Therefore, the remaining portion to reach 100% by weight can be achieved by other additives known in the art; however, within the total first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)), this remaining portion should not exceed 5.0% by weight, such as not exceeding 3.0% by weight. For example, the first propylene polymer (PP1) of the present invention (such as the first propylene homopolymer (H-PP1)) may contain additional small amounts of additives selected from the group consisting of antioxidants, stabilizers, fillers, colorants, nucleating agents, and antistatic agents. Typically, these are added during the granulation process of the powdered product obtained from polymerization. Therefore, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) constitutes at least 95.0% by weight, more preferably at least 97.0% by weight, of the total first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)).

[0135] When the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) contains an α-nucleating agent, it is preferable that it does not contain a β-nucleating agent. Preferably, the α-nucleating agent is selected from the group consisting of the following:

[0136] (i) Salts of monocarboxylic and polycarboxylic acids, such as sodium benzoate or aluminum tert-butylbenzoate, and

[0137] (ii) Dibenzyl sorbitol (e.g., 1,3:2,4-dibenzyl sorbitol) and C1-C8-alkyl-substituted dibenzyl sorbitol derivatives, such as methyl dibenzyl sorbitol, ethyl dibenzyl sorbitol, or dimethyl dibenzyl sorbitol (e.g., 1,3:2,4-di(methyl benzyl)sorbitol), or substituted nonitol derivatives, such as 1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol, and

[0138] (iii) Salts of diesters of phosphate, such as sodium 2,2'-methylenebis(4,6'-di-tert-butylphenyl)phosphate or aluminum bis[2,2'-methylene-bis(4,6'-di-tert-butylphenyl)phosphate]hydroxy, and

[0139] (iv) Vinylcycloalkane polymers and vinylalkane polymers (discussed in more detail below), and

[0140] (v) Their mixture.

[0141] Such additives are generally commercially available and are described, for example, in Hans Zweifel's "Plastic Additives Handbook", pp. 871-873, 5th edition, 2001.

[0142] Preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) contains up to 5.0% by weight of an α-nucleating agent. In a preferred embodiment, the propylene homopolymer contains no more than 500 ppm, more preferably 0.025 to 200 ppm, more preferably 0.1 to 200 ppm, even more preferably 0.3 to 200 ppm, and most preferably 0.3 to 100 ppm of an α-nucleating agent, which is particularly selected from dibenzyl sorbitol (e.g., 1,3:2,4-dibenzyl sorbitol), dibenzyl sorbitol derivatives, preferably dimethyl dibenzyl sorbitol (e.g., 1,3:2,4-di(methylbenzyl)sorbitol), or substituted nonitol-derived compounds such as 1,2,3-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol, sodium 2,2'-methylenebis(4,6,-di-tert-butylphenyl)phosphate, vinylcycloalkane polymers, vinylalkane polymers, and mixtures thereof.

[0143] As outlined above, the meltblown layer (M) according to the invention comprises meltblown fibers (MBF) obtained from a first propylene polymer (PP1). Preferably, based on the total weight of the meltblown fibers, the meltblown fibers (MBF) contain at least 95% by weight of the first propylene polymer (PP1) as described above (such as a first propylene homopolymer (H-PP1)). Particularly preferred is that the meltblown fibers (MBF) are composed of a first propylene polymer (PP1) (such as a first propylene homopolymer (H-PP1)).

[0144] More preferably, the meltblown layer (M) according to the invention comprises a meltblown mesh (MBW) made of meltblown fibers (MBF) as described above. Preferably, the total basis weight (M) of one or more meltblown layers (M), as determined according to ISO 536:1995, is between 0.8 and 30 g / m². 2 More preferably, within the range of 1.0 to 20 g / m 2 Within the range, the most preferred value is 1.2 to 10 g / m³. 2 Within the range.

[0145] Further preferred are the examples of the meltblown layer (M), and more preferably, each meltblown mesh (MBW) has a density of 0.4 to 15 g / m². 2 Within the range of 0.5 to 10 g / m 2 Within the range of 0.6 to 5.0 g / m 2 Weight within the range determined according to ISO 536:1995.

[0146] According to the present invention, preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is produced in the presence of the following substances.

[0147] a) Ziegler-Natta catalyst (ZN-C) comprising a compound of a transition metal from Group 4 to 6 of IUPAC (TC), a compound of a Group 2 metal (MC), and an internal donor (ID);

[0148] b) Optional co-catalyst (Co), and

[0149] c) Optional external donor (ED).

[0150] Preferably, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is produced in a single reactor, i.e., it is unimodal.

[0151] Methods for the polymerization of PP1

[0152] The methods for preparing propylene homopolymers and Ziegler-Natta catalysts (ZN-C) will be described in further detail below.

[0153] As noted above, the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) is preferably produced in a single polymerization method.

[0154] In an alternative implementation, a sequence aggregation method can be used.

[0155] The term "sequential polymerization system" indicates that a first propylene polymer (PP1) (such as a first propylene homopolymer (H-PP1)) is produced in at least two reactors connected in series. Therefore, the polymerization system of the present invention comprises at least a first polymerization reactor (R1) and a second polymerization reactor (R2), and optionally a third polymerization reactor (R3). The term "polymerization reactor" should indicate that the main polymerization occurs. Therefore, in the case where the method consists of two polymerization reactors, this definition does not exclude the option of including, for example, a prepolymerization step in a prepolymerization reactor. The term "consisting of" is only a closed description with respect to the main polymerization reactor.

[0156] The first reactor (R1) is preferably a slurry reactor (SR), and can be any continuous or simple batch stirred tank reactor or loop reactor operating in bulk or slurry. Bulk refers to polymerization in a reaction medium containing at least 60% (w / w) monomer. According to the invention, the slurry reactor (SR) is preferably a (bulk) loop reactor (LR). Therefore, based on the total weight of the polymer slurry within the loop reactor (LR), the average concentration of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) or the first fraction (PP1a) of the first propylene polymer (if a sequential method is used) in the polymer slurry within the loop reactor (LR) is typically from 15% to 55% by weight. In a preferred embodiment of the invention, based on the total weight of the polymer slurry in the loop reactor (LR), the average concentration of the first propylene polymer (PP1) (such as the first propylene homopolymer (H-PP1)) or the first fraction (PP1a) of the first propylene polymer (if a sequential method is used) in the polymer slurry in the loop reactor (LR) is 20% to 55% by weight, and more preferably 25% to 52% by weight.

[0157] If other reactors are present, these reactors (e.g., an optional second polymerization reactor (R2) and an optional third polymerization reactor (R3)) are gas-phase reactors (GPRs), namely a first gas-phase reactor (GPR1) and a second gas-phase reactor (GPR2). The gas-phase reactor (GPR) according to the invention is preferably a fluidized bed reactor, a fast fluidized bed reactor, or a settling bed reactor, or any combination thereof.

[0158] If a sequential method is used, the propylene polymer (i.e., the first fraction (PP1a) of the first propylene polymer) from the first polymerization reactor (R1), more preferably the polymer slurry from the loop reactor (LR) containing the first fraction (PP1a) of the first propylene polymer, is directly fed into the second polymerization reactor (R2), i.e., into the (first) gas-phase reactor (GPR1), without a flash evaporation step between stages. This direct feeding is described in EP 887379A, EP 887380A, EP 887381A and EP991684A. "Direct feeding" refers to a method of directly guiding the contents of the first polymerization reactor (R1) (i.e., the loop reactor (LR)) containing the first fraction (PP1a) of the first propylene homopolymer into the next stage gas-phase reactor.

[0159] Optionally, the propylene polymer (i.e., the first fraction of the propylene polymer (PP1a)) from the first polymerization reactor (R1), and more preferably the polymer slurry containing the first propylene homopolymer fraction (PP1a) from the loop reactor (LR), may be directed to a flash evaporation step or through a further concentration step before being fed to the second polymerization reactor (R2) (i.e., the gas phase reactor (GPR)). Therefore, this "indirect feed" refers to a method of feeding the contents (i.e., polymer slurry) of the first polymerization reactor (R1) and the loop reactor (LR) to the second polymerization reactor (R2) and to the first gas phase reactor (GPR1) via a reaction medium separation unit, wherein the reaction medium is a gas from the separation unit.

[0160] More specifically, the optional second polymerization reactor (R2) and any subsequent reactor (e.g., the third polymerization reactor (R3)) are preferably gas-phase reactors (GPRs). Such a gas-phase reactor (GPR) can be any mechanically mixed or fluidized bed reactor. Preferably, the gas-phase reactor (GPR) comprises a mechanically stirred fluidized bed reactor with an airflow velocity of at least 0.2 m / s. Therefore, it should be understood that the gas-phase reactor is a fluidized bed reactor optionally equipped with a mechanical stirrer.

[0161] Therefore, when using a sequential polymerization method, it is preferred that the first polymerization reactor (R1) is a slurry reactor (SR) (e.g., a loop reactor (LR)), while the second polymerization reactor (R2) and any optional subsequent reactor (e.g., a third polymerization reactor (R3)) are gas-phase reactors (GPR). Thus, in the method of the present invention, at least two polymerization reactors connected in series are used, preferably two polymerization reactors (R1) and (R2) or three polymerization reactors (R1), (R2), and (R3), namely the slurry reactor (SR) (e.g., a loop reactor (LR)) and the (first) gas-phase reactor (GPR1) and the optional second gas-phase reactor (GPR2). If desired, a pre-polymerization reactor can be placed before the slurry reactor (SR).

[0162] The Ziegler-Natta catalyst (ZN-C) is fed into a first polymerization reactor (R1) and transferred together with the polymer (slurry) obtained in the first polymerization reactor (R1) to a subsequent reactor, if any subsequent reactor is used. If the method further includes a prepolymerization step, it is preferable to feed all of the Ziegler-Natta catalyst (ZN-C) into a prepolymerization reactor. Subsequently, the prepolymer product containing the Ziegler-Natta catalyst (ZN-C) is transferred to the first polymerization reactor (R1).

[0163] The preferred multi-stage process is the "loop-gas phase" process, such as the one developed by Borealis A / S of Denmark (known as...). The technology is a process described in, for example, 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.

[0164] Another suitable slurry-gas phase process is Basell. Process.

[0165] Especially good results were obtained by carefully selecting the temperature in the reactor.

[0166] Therefore, it is preferred that the operating temperature in the first polymerization reactor (R1) is in the range of 62 to 85°C, more preferably in the range of 65 to 82°C, and even more preferably in the range of 67 to 80°C.

[0167] Relative to the preceding paragraph, it is preferred that the operating temperatures in the optional second polymerization reactor (R2) and optional third reactor (R3) are in the range of 62 to 95°C, more preferably in the range of 67 to 92°C.

[0168] Preferably, the operating temperature in the optional second polymerization reactor (R2) is equal to or higher than the operating temperature in the first polymerization reactor (R1). Therefore, it is preferable that...

[0169] (a) The operating temperature in the first polymerization reactor (R1) is in the range of 62 to 85°C, more preferably in the range of 65 to 82°C, and even more preferably in the range of 67 to 80°C, such as 70 to 80°C; and

[0170] (b) The operating temperature in the optional second polymerization reactor (R2) is in the range of 75 to 95°C, more preferably in the range of 78 to 92°C, and even more preferably in the range of 78 to 88°C.

[0171] The condition is that the operating temperature in the optional second polymerization reactor (R2) is equal to or higher than the operating temperature in the first polymerization reactor (R1).

[0172] Typically, the pressure in the first polymerization reactor (R1), preferably the loop reactor (LR), is in the range of 20 to 80 bar, preferably in the range of 30 to 70 bar, such as 35 to 65 bar, while the pressure in the optional second polymerization reactor (R2) (i.e., the (first) gas phase reactor (GPR1)) and any optional subsequent reactor (such as the third polymerization reactor (R3), for example the second gas phase reactor (GPR2)) is in the range of 5 to 50 bar, preferably in the range of 15 to 40 bar.

[0173] Preferably, hydrogen is added to each polymerization reactor to control the molecular weight, i.e., the melt flow rate MFR2.

[0174] Preferably, the average residence time in polymerization reactors (R1) and (R2) is relatively long. Typically, the average residence time (τ) is defined as the reaction volume (V). R ) and the reactor volumetric outflow rate (Q) o The ratio of V to V R / Q o ), that is, τ=V R / Q o [τ=V R / Q o In the case of a loop reactor, the reaction volume (V) R () equals the reactor volume.

[0175] Therefore, the average residence time (τ) in the first polymerization reactor (R1) is preferably at least 15 min, more preferably in the range of 15 to 80 min, even more preferably in the range of 20 to 60 min, such as in the range of 24 to 50 min, and / or the average residence time (τ) in the second polymerization reactor (R2) (if present) is preferably at least 70 min, more preferably in the range of 70 to 220 min, even more preferably in the range of 80 to 210 min, still more preferably in the range of 90 to 200 min, such as in the range of 90 to 190 min. Preferably, the average residence time (τ) in the third polymerization reactor (R3) (if present) is preferably at least 30 min, more preferably in the range of 30 to 120 min, even more preferably in the range of 40 to 100 min, such as in the range of 50 to 90 min.

[0176] As described above, in addition to the (primary) polymerization of propylene homopolymer in at least one polymerization reactor (R1 and optionally R2 and R3), the preparation of propylene polymer may also include prepolymerization in a prepolymerization reactor (PR) upstream of the first polymerization reactor (R1).

[0177] Polypropylene (pre-PP) is produced in a prepolymerization reactor (PR). Prepolymerization is carried out in the presence of a Ziegler-Natta catalyst (ZN-C). According to this embodiment, the Ziegler-Natta catalyst (ZN-C), a co-catalyst (Co), and an external donor (ED) are introduced into the prepolymerization step. However, this does not preclude the option of adding additional co-catalyst (Co) and / or external donor (ED) at a later stage, such as in the polymerization process, for example in the first reactor (R1). In one embodiment, if prepolymerization is applied, the Ziegler-Natta catalyst (ZN-C), co-catalyst (Co), and external donor (ED) are added only to the prepolymerization reactor (PR).

[0178] The prepolymerization reaction is typically carried out at a temperature of 0 to 60°C, preferably 15 to 50°C, and more preferably 20 to 45°C.

[0179] The pressure in the prepolymerization reactor is not critical, but it must be high enough to keep the reaction mixture in the liquid phase. Therefore, the pressure can be 20 to 100 bar, for example, 30 to 70 bar.

[0180] In a preferred embodiment, prepolymerization is carried out as a bulk slurry polymerization in liquid propylene, i.e., the liquid phase mainly comprises propylene, optionally with inert components dissolved therein. Furthermore, according to the invention, as described above, ethylene feed is used during prepolymerization.

[0181] Other components can also be added to the prepolymerization stage. Therefore, as is known in the art, hydrogen can be added to the prepolymerization stage to control the molecular weight of polypropylene (pre-PP). Furthermore, antistatic additives can be used to prevent particles from adhering to each other or to the reactor wall.

[0182] Precise control of prepolymerization conditions and reaction parameters is within the scope of the art.

[0183] Due to the process conditions defined above in the prepolymerization, a mixture (MI) of Ziegler-Natta catalyst (ZN-C) and polypropylene (pre-PP) produced in the prepolymerization reactor (PR) is preferably obtained. Preferably, the Ziegler-Natta catalyst (ZN-C) is (well) dispersed in the polypropylene (pre-PP). In other words, the Ziegler-Natta catalyst (ZN-C) particles introduced into the prepolymerization reactor (PR) are broken into smaller fragments that are uniformly distributed in the grown polypropylene (pre-PP). The size of the introduced Ziegler-Natta catalyst (ZN-C) particles and the resulting fragments are not necessarily relevant to the present invention and are within the knowledge of those skilled in the art.

[0184] As described above, if prepolymerization is used, after the prepolymerization, a mixture (MI) of the Ziegler-Natta catalyst (ZN-C) and the polypropylene (pre-PP) produced in the prepolymerization reactor (PR) is transferred to the first reactor (R1). Typically, the total amount of polypropylene (pre-PP) in the final propylene copolymer (R-PP) is quite low, usually not exceeding 5.0% by weight, more preferably not exceeding 4.0% by weight, and even more preferably in the range of 0.5% to 4.0% by weight, such as in the range of 1.0% to 3.0% by weight.

[0185] Without using prepolymerization, propylene and other components (such as Ziegler-Natta catalyst (ZN-C)) are directly introduced into the first polymerization reactor (R1).

[0186] Therefore, propylene polymers are produced under the conditions described above in a method comprising the following steps.

[0187] (a) In the first polymerization reactor (R1), i.e., in the loop reactor (LR), propylene is polymerized to obtain the first fraction of propylene polymer (PP1a).

[0188] (b) The first fraction (PP1a) of the propylene polymer is transferred to the second polymerization reactor (R2).

[0189] (c) In the second polymerization reactor (R2), propylene is polymerized in the presence of a first fraction (PP1a) of propylene polymer to obtain a second fraction (PP1b) of propylene homopolymer, wherein the first fraction (PP1a) and the second fraction (PP1b) of propylene polymer form a propylene polymer.

[0190] Preferably, the propylene polymer is produced under the conditions stated above in a method comprising the following steps:

[0191] (a) In the first polymerization reactor (R1), i.e., in the loop reactor (LR), propylene is polymerized to obtain the first propylene polymer (PP1).

[0192] (b) Remove the first propylene polymer (PP1) from the first polymerization reactor.

[0193] The prepolymerization described above can be completed before step (a).

[0194] The catalyst used in this invention is a solid Ziegler-Natta catalyst (ZN-C), which comprises a compound of a Group 4 to 6 transition metal (such as titanium) of IUPAC (TC), a compound of a Group 2 metal (such as magnesium) (MC), and an internal donor (ID) of a non-phthalic acid compound, preferably a non-phthalic acid ester, and more preferably a non-phthalic acid dicarboxylic acid, as described in more detail below. Therefore, the catalyst is completely free of undesirable phthalic acid compounds. Furthermore, the solid catalyst does not contain any external supporting material (such as silica or MgCl2), but the catalyst is self-supported. Self-supported catalysts contain magnesium halides because magnesium halides are formed during the reaction between the magnesium compound and TiCl4; however, magnesium halides are excluded as an external support medium.

[0195] Ziegler-Natta type catalysts (ZN-C) can be further defined by the manner in which they are obtained. Therefore, Ziegler-Natta type catalysts (ZN-C) are preferably obtained by a method comprising the following steps:

[0196] a)

[0197] a1) Provide a solution of at least a group 2 metal alkoxy compound (Ax), which is the product of the reaction of a group 2 metal compound (MC) and an alcohol (A) optionally in an organic liquid reaction medium, wherein the alcohol (A) contains at least one ether moiety in addition to the hydroxyl moiety;

[0198] or

[0199] a2) A solution of at least a Group 2 metal alkoxy compound (Ax'), which is the product of the reaction of a Group 2 metal compound (MC) with an alcohol (A) and a monohydric alcohol (B) of formula ROH in an organic liquid reaction medium.

[0200] or

[0201] a3) Provide a solution of a mixture of a group 2 alkoxy compound (Ax) and a group 2 metal alkoxy compound (Bx), wherein the group 2 metal alkoxy compound (Bx) is a group 2 metal compound (MC) and a monohydric alcohol (B).

[0202] The reaction products, optionally in an organic liquid reaction medium; and

[0203] b) Add the solution from step a) to at least one compound (TC) of a transition metal from group 4 to 6, and

[0204] c) Obtain solid catalyst component particles.

[0205] And add a non-phthalic acid internal electron donor (ID) in any step prior to step c).

[0206] Preferably, the internal donor (ID) or its precursor is added to the solution in step a).

[0207] According to the above procedure, Ziegler-Natta catalyst (ZN-C) can be obtained by precipitation or by emulsion (liquid / liquid two-phase system)-solidification method, depending on the physical conditions, especially the temperature used in steps b) and c).

[0208] In both methods (precipitation or emulsion-solidification), the catalyst chemistry is the same.

[0209] In the precipitation method, the solution of step a) is combined with at least one transition metal compound (TC) in step b), and the entire reaction mixture is maintained at at least 50°C, more preferably in the temperature range of 55 to 110°C, and even more preferably in the temperature range of 70 to 100°C, to ensure that the catalyst component is completely precipitated in the form of solid particles (step c).

[0210] In the emulsion-curing method, in step b), the solution from step a) is typically added to at least one transition metal compound (TC) at a low temperature, such as -10 to below 50°C, preferably -5 to 30°C. During emulsion stirring, the temperature is typically maintained at -10 to below 40°C, preferably -5 to 30°C. Droplets of the dispersed phase of the emulsion form the active catalyst component. Curing of the droplets (step c) is suitably carried out by heating the emulsion to 70 to 150°C, preferably 80 to 110°C.

[0211] The catalyst prepared by the emulsion-curing method is preferably used in this invention.

[0212] In a preferred embodiment, in step a), the solution of a2) or a3) is used, i.e., a solution of (Ax') or a mixture of (Ax) and (Bx).

[0213] Preferably, the Group 2 metal (MC) is magnesium.

[0214] The alkoxymagnesium compounds (Ax), (Ax') and (Bx) can be prepared in situ by reacting a magnesium compound with one or more of the above-mentioned alcohols in the first step (step a) of the catalyst preparation method, or the alkoxymagnesium compounds can be prepared separately, or they can even be commercially available as ready-made alkoxymagnesium compounds and used as is in the catalyst preparation method of the present invention.

[0215] An illustrative example of alcohol (A) is a monoether of a diol (diol monoether). Preferred alcohol (A) is a C2 to C4 diol monoether, wherein the ether moiety comprises 2 to 18 carbon atoms, preferably 4 to 12 carbon atoms. Preferred examples are 2-(2-ethylhexyloxy)ethanol, 2-butoxyethanol, 2-hexyloxyethanol, and 1,3-propanediol-monobutyl ether, 3-butoxy-2-propanol, wherein 2-(2-ethylhexyloxy)ethanol, 1,3-propanediol-monobutyl ether, and 3-butoxy-2-propanol are particularly preferred.

[0216] The illustrative monohydric alcohol (B) has the formula ROH, where R is a straight-chain or branched C6-C group. 10 Alkyl residue. The most preferred monohydric alcohol is 2-ethyl-1-hexanol or octanol.

[0217] Preferably, a mixture of alkoxy Mg compounds (Ax) and (Bx) or a mixture of alcohols (A) and (B) is used, with the molar ratio of Bx:Ax or B:A being 8:1 to 2:1, more preferably 5:1 to 3:1.

[0218] Alkoxymagnesium compounds can be reaction products of one or more alcohols as defined above and magnesium compounds selected from dialkylmagnesium, alkylalkoxymagnesium, dialkoxymagnesium, haloalkoxymagnesium, and haloalkylmagnesium. The alkyl group can be similar or different C1-C. 20 Alkyl groups, preferably C2-C 10 Alkyl groups. Typical alkyl-alkoxy magnesium compounds, when used, are ethylbutoxy magnesium, butylpentoxy magnesium, octylbutoxy magnesium, and octyloctoxy magnesium. Dialkyl magnesiums are preferred. The most preferred dialkyl magnesiums are butyloctyl magnesium or butylethyl magnesium.

[0219] It is also possible that magnesium compounds, in addition to reacting with alcohols (A) and (B), can react with formula R"(OH). m The polyol (C) is reacted to obtain the alkoxymagnesium compound. If used, the preferred polyol is one in which R” is a straight-chain, cyclic, or branched C2 to C3 group. 10 Alcohols containing hydrocarbon residues, where m is an integer from 2 to 6.

[0220] Therefore, the alkoxymagnesium compound in step a) is selected from the group consisting of magnesium dialkoxy, magnesium diaryloxy, magnesium halide, magnesium halide, magnesium alkylalkoxy, magnesium arylalkoxy, and magnesium alkylaryloxy. Alternatively, a mixture of magnesium dihalides and magnesium dialkoxy can be used.

[0221] The solvent used to prepare this catalyst can be selected from aromatic and aliphatic straight-chain, branched, and cyclic hydrocarbons or mixtures thereof having 5 to 20 carbon atoms, more preferably 5 to 12 carbon atoms. Suitable solvents include benzene, toluene, cumene, xylene, pentane, hexane, heptane, octane, and nonane. Hexane and pentane are particularly preferred.

[0222] Magnesium compounds are typically provided as solutions of 10 to 50% by weight in the aforementioned solvents. Typical commercially available magnesium compounds, especially dialkylmagnesium solutions, are solutions of 20 to 40% by weight in toluene or heptane.

[0223] The reaction for preparing alkoxymagnesium compounds can be carried out at temperatures ranging from 40°C to 70°C. The most suitable temperature is selected based on the magnesium compound and one or more alcohols used.

[0224] Preferably, the transition metal compounds of groups 4 to 6 are titanium compounds, and most preferably titanium halides, such as TiCl4.

[0225] The internal donor (ID) used to prepare the catalyst of the present invention is preferably a diester selected from non-phthalic acid carboxylic acid diesters, 1,3-diethers, derivatives, and mixtures thereof. Particularly preferred donors are diesters of monounsaturated dicarboxylic acids, particularly esters belonging to the group consisting of malonic acid esters, maleic acid esters, succinic acid esters, citrate esters, glutaric acid esters, cyclohexene-1,2-dicarboxylic acid esters and benzoic acid esters and any derivatives and / or mixtures thereof, with citrate esters being the most preferred.

[0226] In emulsion processes, a two-phase liquid-liquid system can be formed by simple stirring and optionally adding (additional) solvents and additives, such as turbulence minimizing agents (TMAs) and / or emulsifiers and / or emulsion stabilizers, such as surfactants, which are used in a manner known in the art to promote emulsion formation and / or stabilize the emulsion. Preferably, the surfactant is an acrylic or methacrylic acid polymer. Particularly preferred are unbranched C... 12 To C 20 (Meth)acrylates, such as poly(hexadecyl) methacrylate and poly(octadecyl) methacrylate and mixtures thereof. If used, the turbulence minimizing agent (TMA) is preferably selected from α-olefin polymers of α-olefin monomers having 6 to 20 carbon atoms, such as polyoctene, polynonene, polydecene, polyundecene, or polydodecene or mixtures thereof. Polydecene is most preferred.

[0227] Solid particulate products obtained by precipitation or emulsion-solidification methods can be washed at least once, preferably at least twice, and most preferably at least three times with aromatic and / or aliphatic hydrocarbons, preferably with toluene, heptane, or pentane. The catalyst can be further dried, such as by evaporation or rinsing with nitrogen, or it can be slurried into an oily liquid without any drying step.

[0228] The resulting Ziegler-Natta catalyst is ideally in particulate form, typically with an average particle size ranging from 5 to 200 μm, preferably from 10 to 100 μm. The particles are dense, with low porosity and a surface area of ​​less than 20 g / m². 2 More preferably below 10g / m 2 Typically, the catalyst composition contains 1 to 6 wt% Ti, 10 to 20 wt% Mg, and 10 to 40 wt% donors.

[0229] Detailed descriptions of the preparation of the catalyst are disclosed in WO 2012 / 007430, EP2610271, EP 261027 and EP2610272, which are incorporated herein by reference.

[0230] The Ziegler-Natta catalyst (ZN-C) is preferably used in conjunction with an alkylaluminum co-catalyst and an optional external donor.

[0231] As another component in the polymerization method of the present invention, an external donor (ED) is preferably present. Suitable external donors (EDs) include certain silanes, ethers, esters, amines, ketones, heterocyclic compounds, and blends of these compounds. Particularly preferred is the use of silanes. Most preferred is the use of silanes having the following general formula:

[0232] R a p R b q Si(OR c ) (4-p-q)

[0233] Where R a R b and R c R represents a hydrocarbon group, particularly an alkyl or cycloalkyl group, where p and q are numbers in the range of 0 to 3, and their sum p + q is equal to or less than 3. a R b and R c They can be chosen independently of each other and can be the same or different. Specific examples of such silanes are (tert-butyl)2Si(OCH3)2 and (cyclohexyl)(methyl)Si(OCH3). 2 (phenyl)2Si(OCH3)2 and (cyclopentyl)2Si(OCH3)2, or having the following general formula

[0234] Si(OCH2CH3)3(NR 3 R 4 )

[0235] Where R 3 and R 4 They can be the same or different, and represent hydrocarbon groups having 1 to 12 carbon atoms.

[0236] R 3 and R 4 It is independently selected from the group consisting of straight-chain aliphatic hydrocarbon groups having 1 to 12 carbon atoms, branched aliphatic hydrocarbon groups having 1 to 12 carbon atoms, and cyclic aliphatic hydrocarbon groups having 1 to 12 carbon atoms. Particularly preferred is R. 3 and R 4 It is independently selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decyl, isopropyl, isobutyl, isopentyl, tert-butyl, tert-pentyl, neopentyl, cyclopentyl, cyclohexyl, methylcyclopentyl, and cycloheptyl.

[0237] More preferably, R 3 and R 4 The two are the same, but more preferably, R 3 and R 4 Both are ethyl groups.

[0238] Particularly preferred external donors (EDs) are dicyclopentyldimethoxysilane donors (D-donors) or cyclohexylmethyldimethoxysilane donors (C-donors).

[0239] In addition to the Ziegler-Natta catalyst (ZN-C) and optional external donor (ED), a co-catalyst may be used. Preferably, the co-catalyst is a compound of Group 13 of the periodic table (IUPAC), such as an organoaluminum compound, such as an aluminum compound, like an alkylaluminum, aluminum halide, or an alkylaluminum halide. Thus, in one specific embodiment, the co-catalyst (Co) is a trialkylaluminum, such as triethylaluminum (TEAL), dialkylaluminum chloride, or alkylaluminum dichloride, or a mixture thereof. In one specific embodiment, the co-catalyst (Co) is triethylaluminum (TEAL).

[0240] Preferably, the ratio between the cocatalyst (Co) and the external donor (ED) [Co / ED] and / or the ratio between the cocatalyst (Co) and the transition metal (TM) [Co / TM] should be carefully selected.

[0241] therefore,

[0242] (a) The molar ratio of the co-catalyst (Co) to the external donor (ED) [Co / ED] must be in the range of 5 to 45, preferably in the range of 5 to 35, more preferably in the range of 5 to 25; and optionally...

[0243] (b) The molar ratio of the co-catalyst (Co) to the titanium compound (TC) [Co / TC] must be in the range of 80 to 500, preferably in the range of 100 to 350, and even more preferably in the range of 120 to 300.

[0244] As outlined above, the first propylene polymer (PP1) can be nucleated, preferably α-nucleated. As a nucleating agent, a polymer nucleating agent can be used, preferably a polymer of a vinyl compound, more preferably a polymer nucleating agent obtained by polymerizing vinyl cycloalkane monomers or vinyl alkane monomers.

[0245] More preferably, the polymer nucleating agent is a vinyl compound polymerized according to the following formula.

[0246] H2C = CH-CHR 11 R 12

[0247] Where R 11 and R 12 Together they form a 5- or 6-membered saturated, unsaturated, or aromatic ring, optionally containing substituents, or independently representing an alkyl group comprising 1 to 4 carbon atoms, thereby in R 11 and R12 In the case of the formation of an aromatic ring, -CHR does not exist. 11 R 12 Some hydrogen atoms.

[0248] Even more preferably, the polymer nucleating agent is selected from: vinyl cycloalkane polymers, preferably vinyl cyclohexane (VCH) polymers, vinyl cyclopentane polymers, 3-methyl-1-butene polymers and vinyl-2-methylcyclohexane polymers.

[0249] The preferred nucleating agent is vinylcyclohexane (VCH) polymer.

[0250] As described above, in a preferred embodiment, the nucleating agent is a polymeric nucleating agent, more preferably a polymer of a vinyl compound according to the formula defined above, and even more preferably a vinylcyclohexane (VCH) polymer.

[0251] Based on the total weight (100 wt%) of the first propylene polymer (PP1), the amount of nucleating agent preferably does not exceed 10,000 ppm by weight (meaning parts per million based on the total weight (100 wt%) of the polypropylene composition, also referred to herein as ppm), more preferably not more than 6,000 ppm, and even more preferably not more than 5,000 ppm.

[0252] Based on the total weight (100% by weight) of the first propylene polymer (PP1), the amount of nucleating agent is more preferably not more than 500 ppm, preferably 0.025 to 200 ppm, more preferably 0.1 to 200 ppm, more preferably 0.3 to 200 ppm, and most preferably 0.3 to 100 ppm.

[0253] In a preferred embodiment, the nucleating agent is a polymeric nucleating agent, most preferably a polymer of a vinyl compound according to formula (III) as defined above, even more preferably a vinylcyclohexane (VCH) polymer as defined above, and the amount of the nucleating agent (B) is no more than 200 ppm based on the total weight (100 wt%) of the first propylene polymer (PP1), more preferably 0.025 to 200 ppm, more preferably 0.1 to 200 ppm, more preferably 0.3 to 200 ppm, and most preferably 0.3 to 100 ppm.

[0254] The nucleating agent can be introduced into the first propylene polymer (PP1) for example during the polymerization process of the first propylene polymer (PP1), or it can be incorporated into the first propylene polymer (PP1) by mechanical blending with a nucleating polymer containing a polymer nucleating agent (so-called masterbatch technology) or by mechanical blending the first propylene polymer (PP1) with the nucleating agent itself.

[0255] Therefore, a nucleating agent can be introduced into the first propylene polymer (PP1) during the polymerization process. Preferably, the nucleating agent is introduced into the first propylene polymer (PP1) by the following steps: first, in the presence of a catalyst system as described above, polymerize a vinyl compound as defined above according to formula (II), or even more preferably vinylcyclohexane (VCH), the catalyst system comprising a solid Ziegler-Natta catalyst component, a co-catalyst, and an optional external donor; then, the resulting polymer of the vinyl compound as defined above according to formula (III), or even more preferably vinylcyclohexane (VCH), is used in a reaction mixture with the catalyst system to produce the first propylene polymer (PP1).

[0256] The polymerization of vinyl compounds (such as VCH) can be carried out in an inert fluid in which the polymer formed (such as polyVCH) does not dissolve. It is important to ensure that the viscosity of the final catalyst / polymerized vinyl compound / inert fluid mixture is high enough to prevent catalyst particles from settling during storage and transportation.

[0257] The viscosity of the mixture can be adjusted before or after the polymerization of the vinyl compound. For example, polymerization can be carried out in a low-viscosity oil, and the viscosity can be adjusted by adding a high-viscosity substance after the polymerization of the vinyl compound. This high-viscosity substance can be a "wax," such as an oil or a mixture of oil and a solid or high-viscosity substance (grease). The viscosity of this viscous substance is typically 1000 to 15000 cP at room temperature. The advantage of using wax is improved catalyst storage and feeding. Catalyst activity is maintained because washing, drying, sieving, and transfer are not required. The weight ratio between the oil and the solid or high-viscosity polymer is preferably less than 5:1. In addition to viscous substances, liquid hydrocarbons (such as isobutane, propane, pentane, and hexane) can also be used as a medium in the modification step.

[0258] Polypropylene produced using catalysts modified with polymerized vinyl compounds is essentially free of free (unreacted) vinyl compounds. This means that the vinyl compounds will be completely reacted during the catalyst modification step.

[0259] Furthermore, the reaction time for modifying the catalyst by polymerizing vinyl compounds should be sufficient to allow the vinyl monomers to react completely, i.e., polymerization should continue until the amount of unreacted vinyl compounds in the reaction mixture (including the polymerization medium and reactants) is less than 0.5% by weight, particularly less than 2000 ppm by weight (as shown by analysis). Therefore, when the prepolymerized catalyst contains at most about 0.1% by weight of vinyl compounds, the final vinyl compound content in the polypropylene will be below the limit determined by GC-MS (<0.01 ppm by weight). Typically, when operating on an industrial scale, a polymerization time of at least 30 minutes is required, preferably at least 1 hour, particularly at least 5 hours. Polymerization times in the range of 6 to 50 hours can even be used. Modification can be carried out at temperatures of 10 to 70°C, preferably 35 to 65°C.

[0260] This catalyst modification step, known as BNT technology, is carried out in the aforementioned prepolymerization step to introduce a polymer nucleating agent.

[0261] The general preparation of vinyl compounds (II) of such modified catalyst systems is disclosed in, for example, EP 1 028 984 or WO 00 / 6831.

[0262] In another embodiment, a polymer nucleating agent is added using a so-called masterbatch technique, wherein a nucleated polymer, preferably a propylene homopolymer, containing the polymer nucleating agent (masterbatch), is blended with a first propylene polymer (PP1). This masterbatch is preferably prepared by polymerizing propylene in a sequential polymerization process.

[0263] The propylene homopolymer produced containing a polymer nucleating agent is a so-called carrier polymer. If the nucleating agent is added together with the carrier polymer in the form of a masterbatch, the concentration of the nucleating agent in the masterbatch is at least 10 ppm, typically at least 15 ppm. Preferably, the nucleating agent is present in the masterbatch in the range of 10 to 2000 ppm, more preferably greater than 15 to 1000 ppm, such as 20 to 500 ppm.

[0264] As described above, the support polymer is preferably a propylene homopolymer, which is produced using the catalyst system for the first propylene polymer (PP1) as described above, and has an MFR2 (230°C, 2.16 kg) in the range of 1.0 to 800 g / 10 min, preferably in the range of 1.5 to 500 g / 10 min, more preferably in the range of 2.0 to 200 g / 10 min, and most preferably in the range of 2.5 to 150 g / 10 min.

[0265] More preferably, the carrier polymer is an isotactic propylene homopolymer having a melting point very similar to that of the propylene homopolymer defined above as the first propylene polymer (PP1). Therefore, the carrier polymer has a melting temperature T measured by differential scanning calorimetry (DSC) of 150°C or greater, i.e., 150 to 168°C or greater, more preferably at least 155°C, i.e., in the range of 155 to 166°C. m .

[0266] If the nucleating agent is added in the form of a masterbatch, the amount of masterbatch added is in the range of 1.0 to 10% by weight, preferably in the range of 1.5 to 8.5% by weight, and more preferably in the range of 2.0 to 30% by weight, based on the total weight of the first propylene polymer (PP1).

[0267] Spunbond layer (S)

[0268] As outlined above, the nonwoven fabric (NF) according to the invention comprises at least one spunbond layer (S) comprising spunbond fibers (SBF).

[0269] Preferably, spunbond fiber (SBF) accounts for at least 80% by weight of the spunbond layer (S), more preferably at least 90% by weight, and even more preferably at least 95% by weight. Particularly preferred is that the spunbond layer (S) is composed of spunbond fiber (SBF).

[0270] Spunbond fiber (SBF) is obtained from a second propylene polymer (PP2).

[0271] The second propylene polymer (PP2) can be a propylene copolymer or a propylene homopolymer.

[0272] In the case where the second propylene polymer (PP2) is a propylene copolymer, the second propylene polymer (PP2) comprises monomers that can be copolymerized with propylene, such as comonomers, such as ethylene and / or C4 to C8 α-olefins, particularly ethylene and / or C4 to C6 α-olefins, such as 1-butene and / or 1-hexene. Preferably, the second propylene polymer (PP2) according to the invention comprises monomers that can be copolymerized with propylene selected from the group consisting of ethylene, 1-butene, and 1-hexene, particularly composed of monomers that can be copolymerized with propylene selected from the group consisting of ethylene, 1-butene, and 1-hexene. More particularly, in addition to propylene, the second propylene polymer (PP2) of the invention also comprises units that can be derived from ethylene and / or 1-butene. In a preferred embodiment, the second propylene polymer (PP2) comprises only units that can be derived from ethylene and propylene.

[0273] The comonomer content of the second propylene polymer (PP2) is in the range of 0.0 to 5.0 mol%, more preferably in the range of 0.0 to 3.0 mol%, and even more preferably in the range of 0.0 to 1.0 mol%.

[0274] In one embodiment, the second propylene polymer (PP2) is a second propylene homopolymer (H-PP2). For the term "propylene homopolymer," refer to the definition provided above.

[0275] Preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is characterized by a moderate melt flow rate. Therefore, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a melt flow rate MFR2 (final) (230°C / 2.16 kg) measured according to ISO 1133 in the range of 5.0 to 50 g / 10 min, more preferably in the range of 10 to 45 g / 10 min, even more preferably in the range of 15 to 40 g / 10 min, still more preferably in the range of 20 to 35 g / 10 min, such as in the range of 25 to 32 g / 10 min.

[0276] Unless otherwise stated, in this invention, the melt flow rate (230°C / 2.16 kg) of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is preferably the melt flow rate (230°C / 2.16 kg) after viscous cracking (if viscous cracking has been applied).

[0277] Therefore, it is preferred that the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has been de-thickened and cracked.

[0278] Therefore, the melt flow rate MFR2(initial) (230°C / 2.16 kg) of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) (i.e., the melt flow rate before viscous cracking) is much lower, such as 0.1 to 5 g / 10 min. For example, before viscous cracking, the melt flow rate MFR2(initial) (230°C / 2.16 kg) of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is 1 to 4 g / 10 min, such as 2 to 3.5 g / 10 min.

[0279] In one embodiment of the invention, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has been subjected to viscosity-reducing cracking, wherein the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) satisfies inequality (III):

[0280]

[0281] MFR(final) is the melt flow rate MFR2 (230°C) after viscosity reduction cracking, as determined according to ISO 1133, and MFR(initial) is the melt flow rate MFR2 (230°C) before viscosity reduction cracking, as determined according to ISO 1133.

[0282] More preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) satisfies inequality (Ia):

[0283]

[0284] More preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) satisfies inequality (Ib):

[0285]

[0286] Most preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) satisfies inequality (Ic):

[0287]

[0288] More preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) satisfies inequality (IV):

[0289]

[0290] Wherein, MWD (final) is the molecular weight distribution (Mw / Mn) determined by gel permeation chromatography after viscosity reduction cracking, and MWD (initial) is the molecular weight distribution (Mw / Mn) determined by gel permeation chromatography before viscosity reduction cracking.

[0291] More preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) satisfies inequality (IVa):

[0292]

[0293] More preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) satisfies inequality (IVb):

[0294]

[0295] Most preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) satisfies inequality (IVc):

[0296]

[0297] For the viscosity-reducing cracking conditions and viscosity-reducing cracking agents of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)), refer to the definition of the first propylene polymer (PP1) provided above.

[0298] Preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is isotactic. However, it is preferred that the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a five-unit group concentration (mmmm%) in the range of 95.00 to 99.99%, more preferably in the range of 97.00 to 99.97%, and even more preferably in the range of 98.50 to 99.90%.

[0299] Another characteristic of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is the misinsertion of propylene within the polymer chain, indicating that the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is produced in the presence of a single active site catalyst, preferably in the presence of a single active site catalyst (SSC) as defined in more detail below. Therefore, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is characterized by a preferred 0.40 to 1.50 mol%, more preferably 0.45 to 1.50 mol%, even more preferably 0.45 to 1.40 mol%, still more preferably 0.50 to 1.00 mol%, and most preferably 0.50 to 0.85 mol% of the polymer. 13 The amount of defects in the 2,1 erythromorphic region was determined by C-NMR spectroscopy.

[0300] Preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is characterized by a relatively low content of cold xylene solubles (XCS) in the range of 0.1 to 2.0% by weight. Therefore, preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a xylene cold solubles content (XCS) in the range of greater than 0.3 to 1.5% by weight, more preferably in the range of 0.4 to 1.2% by weight, and even more preferably in the range of 0.5 to 1.0% by weight.

[0301] The amount of xylene cold solubles (XCS) also indicates that the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) preferably does not contain any elastomeric polymer components, such as ethylene propylene rubber. In other words, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) should not be a multiphase polypropylene, i.e., a system consisting of a polypropylene matrix in which an elastomeric phase is dispersed. Such a system is characterized by a relatively high xylene cold soluble content.

[0302] The amount of xylene cold solubles (XCS) also indicates that the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) preferably does not contain an elastomeric (co)polymer that forms inclusions as a second phase for improving mechanical properties. Conversely, polymers containing elastomeric (co)polymers as second-phase inserts will be referred to as multiphase and are preferably not part of this invention. The presence of a second phase, or so-called inclusion, is visible, for example, by high-resolution microscopy (such as electron microscopy or atomic force microscopy) or by dynamic mechanical thermal analysis (DMTA). In particular, in DMTA, the presence of a multiphase structure can be determined by the presence of at least two distinct glass transition temperatures.

[0303] Therefore, it is preferred that the second propylene polymer (PP2) according to the present invention (such as the second propylene homopolymer (H-PP2)) does not have a glass transition temperature below -30°C, preferably below -25°C, and more preferably below -20°C.

[0304] In another preferred embodiment, according to the invention, the glass transition temperature of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is in the range of -12 to 5°C, more preferably in the range of -10 to 4°C.

[0305] Furthermore, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is characterized by a relatively low molecular weight. Therefore, it is preferred that the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a weight-average molecular weight Mw (initial) of less than 500 kg / mol before viscous cracking, more preferably in the range of 100 to 400 kg / mol, and even more preferably in the range of 250 kg / mol to 350 kg / mol.

[0306] Relative to the preceding paragraph, additionally or optionally, it is preferred that the initial molecular weight distribution (Mw(initial) / Mn(initial)) of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) before viscous cracking is in the range of 2.0 to 5.0, more preferably in the range of 2.3 to 4.0, and even more preferably in the range of 2.5 to 3.5.

[0307] As outlined above, preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has been de-thickened and cracked.

[0308] Therefore, it is preferred that the final molecular weight distribution (Mw(final) / Mn(final)) of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) after viscosity reduction cracking is in the range of 2.0 to 4.5, in the range of 2.1 to 3.5, and more preferably in the range of 2.2 to 3.0.

[0309] The second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a relatively low melting temperature. Therefore, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a melting temperature T measured by differential scanning calorimetry (DSC) in the range of 145 to 160°C, i.e., in the range of 148°C to 157°C, more preferably in the range of 149°C to 155°C. m .

[0310] Furthermore, it is preferred that the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a crystallization temperature Tc measured by differential scanning calorimetry (DSC) of 100°C or greater, more preferably in the range of 105 to 115°C, and even more preferably in the range of 107 to 113°C.

[0311] Preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is characterized by low stiffness. Therefore, preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a low tensile modulus. Therefore, preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) has a tensile modulus measured at 23°C according to ISO 527-1 (crosshead speed 1 mm / min) in the range of less than 1600 MPa, more preferably in the range of 1000 to 1500 MPa, and even more preferably in the range of 1100 to 1400 MPa.

[0312] Preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is obtained by polymerizing propylene in the presence of a single active site catalyst (SSCC) as defined below. More preferably, the second propylene polymer (PP2) according to the invention (such as the second propylene homopolymer (H-PP2)) is obtained by using a single active site catalyst (SSC) via a method defined in detail below.

[0313] The second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) may include two fractions, more preferably it may consist of two fractions, namely a first fraction (PP2a) of the second propylene polymer and a second fraction (PP2b) of the second propylene polymer. Preferably, the weight ratio [(PP2a):(PP2b)] between the first fraction (PP2a) of the second propylene polymer and the second fraction (PP2b) of the second propylene polymer is 70:30 to 40:60, more preferably 65:35 to 45:55.

[0314] The melt flow rates of the first fraction (PP2a) and the second fraction (PP2b) of the second propylene polymer can be different. However, it is preferred that the melt flow rate MFR2 (230°C) of the first fraction (PP2a) and the melt flow rate MFR2 (230°C) of the second fraction (PP2b) of the second propylene polymer are almost the same, i.e., the difference calculated based on the lower of the two values ​​does not exceed 15%, preferably not more than 10%, such as not more than 7%.

[0315] The second propylene polymer (PP2) of the present invention (such as the second propylene homopolymer (H-PP2)) may contain other components. However, it is preferred that the second propylene polymer (PP2) of the present invention (such as the second propylene homopolymer (H-PP2)) contains only the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) as defined in the present invention as a polymer component. Therefore, based on the total second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)), the amount of the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) may not reach 100.0% by weight. Therefore, the remaining portion to reach 100% by weight can be achieved by other additives known in the art; however, in the total second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)), this remaining portion should not exceed 5.0% by weight, such as not exceeding 3.0% by weight. For example, the second propylene polymer (PP2) of the present invention (such as the second propylene homopolymer (H-PP2)) may contain additional small amounts of additives selected from the group consisting of antioxidants, stabilizers, fillers, colorants, nucleating agents, and antistatic agents. Typically, these are added during the granulation process of the powdered product obtained from polymerization. Therefore, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) constitutes at least 95.0% by weight, more preferably at least 97.0% by weight, of the total second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)).

[0316] When the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) contains an α-nucleating agent, it is preferable that it does not contain a β-nucleating agent. Preferably, the α-nucleating agent is selected from the group consisting of the following:

[0317] (i) Salts of monocarboxylic and polycarboxylic acids, such as sodium benzoate or aluminum tert-butylbenzoate, and

[0318] (ii) Dibenzyl sorbitol (e.g., 1,3:2,4-dibenzyl sorbitol) and C1-C8-alkyl-substituted dibenzyl sorbitol derivatives, such as methyl dibenzyl sorbitol, ethyl dibenzyl sorbitol, or dimethyl dibenzyl sorbitol (e.g., 1,3:2,4-di(methyl benzyl)sorbitol), or substituted nonitol derivatives, such as 1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol, and

[0319] (iii) Salts of diesters of phosphate, such as sodium 2,2'-methylenebis(4,6'-di-tert-butylphenyl)phosphate or aluminum bis[2,2'-methylene-bis(4,6'-di-tert-butylphenyl)phosphate]hydroxy, and

[0320] (iv) Vinylcycloalkane polymers and vinylalkane polymers (discussed in more detail below), and

[0321] (v) Their mixture.

[0322] Such additives are generally commercially available and are described, for example, in Hans Zweifel's "Plastic Additives Handbook", pp. 871-873, 5th edition, 2001.

[0323] Preferably, the propylene homopolymer contains up to 5.0% by weight of an α-nucleating agent. In a preferred embodiment, the propylene homopolymer contains no more than 500 ppm, more preferably 0.025 to 200 ppm, more preferably 0.1 to 200 ppm, even more preferably 0.3 to 200 ppm, and most preferably 0.3 to 100 ppm of an α-nucleating agent, which is particularly selected from dibenzyl sorbitol (e.g., 1,3:2,4-dibenzyl sorbitol), dibenzyl sorbitol derivatives, preferably dimethyl dibenzyl sorbitol (e.g., 1,3:2,4-di(methylbenzyl)sorbitol), or substituted nonitol-derived compounds such as 1,2,3-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol, sodium 2,2'-methylenebis(4,6,-di-tert-butylphenyl)phosphate, vinylcycloalkane polymers, vinylalkane polymers, and mixtures thereof.

[0324] As outlined above, the spunbond layer (S) according to the invention comprises spunbond fibers (SBF) obtained from a second propylene polymer (PP2). Preferably, based on the total weight of the meltblown fibers, the spunbond fibers (SBF) contain at least 95% by weight of the second propylene polymer (PP2) as described above (such as a second propylene homopolymer (H-PP2)). Particularly preferred is that the spunbond fibers (SBF) are composed of a second propylene polymer (PP2) (such as a second propylene homopolymer (H-PP2)).

[0325] More preferably, the spunbond layer (S) according to the invention comprises a spunbond web (SBW) made of spunbond fibers (SBF) as described above. Preferably, the total basis weight of one or more spunbond layers (S), as determined according to ISO 536:1995, is between 5.0 and 100 g / m². 2 More preferably, it is within the range of 8.0 to 50 g / m 2 Within the range, the most preferred value is between 10.0 and 20 g / m³. 2 Within the range.

[0326] Further preferred are the various examples of the spunbond layer (S), and more preferably each spunbond web (SBW) has a g / m² content of 2.0 to 30 g / m². 2 Within the range of 2.5 to 15 g / m 2 Within the range of 3.0 to 6.0 g / m 2 Weight within the range determined according to ISO 536:1995.

[0327] Preferably, the second propylene polymer (PP2) according to the invention (such as the second propylene homopolymer (H-PP2)) is produced in the presence of a single active site catalyst, more preferably in the presence of a single active site catalyst (SSC) as described below.

[0328] Preferably, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is produced in a sequential polymerization method comprising at least two reactors (R1) and (R2) as further described below, wherein a first fraction (PP2a) of the second propylene polymer is produced in the first reactor (R1) and subsequently transferred to the second reactor (R2), wherein a second fraction (PP2b) of the second propylene polymer is produced in the second reactor (R2) in the presence of the first fraction (PP2a) of the second propylene polymer.

[0329] Methods for the polymerization of PP2

[0330] The methods for preparing propylene polymers and single active center catalysts (SSCs) will be described in further detail below.

[0331] As noted above, the second propylene polymer (PP2) (such as the second propylene homopolymer (H-PP2)) is preferably produced in a sequential polymerization method.

[0332] The term "sequential polymerization system" indicates that a second propylene polymer (PP2) (such as a second propylene homopolymer (H-PP2)) is produced in at least two reactors connected in series. Therefore, the polymerization system of the present invention comprises at least a first polymerization reactor (R1) and a second polymerization reactor (R2), and optionally a third polymerization reactor (R3). The term "polymerization reactor" should indicate that the main polymerization occurs. Therefore, in the case where the method consists of two polymerization reactors, this definition does not exclude the option of including, for example, a prepolymerization step in a prepolymerization reactor. The term "consisting of" is only a closed description with respect to the main polymerization reactor.

[0333] Preferably, at least one of the two polymerization reactors (R1) and (R2) is a gas-phase reactor (GPR). More preferably, the second polymerization reactor (R2) and optionally the third polymerization reactor (R3) are gas-phase reactors (GPRs), namely the first gas-phase reactor (GPR1) and the second gas-phase reactor (GPR2). The gas-phase reactor (GPR) according to the invention is preferably a fluidized bed reactor, a fast fluidized bed reactor, or a settling bed reactor, or any combination thereof.

[0334] Therefore, the first polymerization reactor (R1) is preferably a slurry reactor (SR), and can be any continuous or simple batch stirred tank reactor or loop reactor operating in bulk or slurry. Bulk refers to polymerization in a reaction medium containing at least 60% (w / w) monomer. According to the invention, the slurry reactor (SR) is preferably a (bulk) loop reactor (LR). Therefore, based on the total weight of the polymer slurry in the loop reactor (LR), the average concentration of the first fraction (first F) (i.e., the first fraction (PP2a) of the second propylene polymer) in the polymer slurry in the loop reactor (LR) is typically 15% to 55% by weight. In a preferred embodiment of the invention, based on the total weight of the polymer slurry in the loop reactor (LR), the average concentration of the first fraction (PP2a) of the second propylene polymer in the polymer slurry in the loop reactor (LR) is 20% to 55% by weight, and more preferably 25% to 52% by weight.

[0335] Preferably, the propylene homopolymer (i.e., the first fraction (PP2a) of the second propylene polymer) from the first polymerization reactor (R1), and more preferably, the polymer slurry from the loop reactor (LR) containing the first fraction (PP2a) of the second propylene polymer, is directly fed into the second polymerization reactor (R2), i.e., into the (first) gas-phase reactor (GPR1), without a flash evaporation step between stages. This direct feeding is described in EP 887379 A, ​​EP 887380 A, EP 887381 A, and EP 991684 A. "Direct feeding" refers to a method of directly guiding the contents of the first polymerization reactor (R1) (i.e., the loop reactor (LR)) containing the first fraction (PP2a) of the second propylene polymer into the next stage gas-phase reactor.

[0336] Optionally, the propylene homopolymer (i.e., the first fraction (PP2a) of the second propylene polymer) from the first polymerization reactor (R1), and more preferably the polymer slurry containing the first fraction (PP2a) of the second propylene polymer from the loop reactor (LR), may be directed to a flash evaporation step or through a further concentration step before being fed to the second polymerization reactor (R2) (i.e., the gas phase reactor (GPR)). Therefore, this "indirect feed" refers to a method of feeding the contents (i.e., polymer slurry) of the first polymerization reactor (R1) and the loop reactor (LR) to the second polymerization reactor (R2) and to the first gas phase reactor (GPR1) via a reaction medium separation unit, wherein the reaction medium is a gas from the separation unit.

[0337] More specifically, the second polymerization reactor (R2) and any subsequent reactors (e.g., the third polymerization reactor (R3)) are preferably gas-phase reactors (GPRs). Such a gas-phase reactor (GPR) can be any mechanically mixed or fluidized bed reactor. Preferably, the gas-phase reactor (GPR) comprises a mechanically stirred fluidized bed reactor with an airflow velocity of at least 0.2 m / s. Therefore, it should be understood that the gas-phase reactor is a fluidized bed reactor optionally equipped with a mechanical stirrer.

[0338] Therefore, in a preferred embodiment, the first polymerization reactor (R1) is a slurry reactor (SR) (such as a loop reactor (LR)), while the second polymerization reactor (R2) and any optional subsequent reactor (such as a third polymerization reactor (R3)) are gas-phase reactors (GPR). Thus, for the method of the present invention, at least two polymerization reactors connected in series are used, preferably two polymerization reactors (R1) and (R2) or three polymerization reactors (R1), (R2) and (R3), namely the slurry reactor (SR) (such as a loop reactor (LR)) and the (first) gas-phase reactor (GPR1) and optionally the second gas-phase reactor (GPR2). If desired, a pre-polymerization reactor is placed before the slurry reactor (SR).

[0339] A single active site catalyst (SSC) is fed into a first polymerization reactor (R1) and transferred together with the polymer (slurry) obtained in the first polymerization reactor (R1) to a subsequent reactor. If the method further includes a prepolymerization step, it is preferable to feed all the single active site catalyst (SSC) into a prepolymerization reactor. Subsequently, the prepolymer product containing the single active site catalyst (SSC) is transferred to the first polymerization reactor (R1).

[0340] The preferred multi-stage process is the "loop-gas phase" process, such as the one developed by Borealis A / S of Denmark (known as...). The technology is a process described in, for example, 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.

[0341] Another suitable slurry-gas phase process is Basell. Process.

[0342] Especially good results were obtained by carefully selecting the temperature in the reactor.

[0343] Therefore, it is preferred that the operating temperature in the first polymerization reactor (R1) is in the range of 62 to 85°C, more preferably in the range of 65 to 82°C, and even more preferably in the range of 67 to 80°C.

[0344] Relative to the preceding paragraph, it is preferred that the operating temperatures in the second polymerization reactor (R2) and the optional third reactor (R3) are in the range of 75 to 95°C, more preferably in the range of 78 to 92°C.

[0345] Preferably, the operating temperature in the second polymerization reactor (R2) is equal to or higher than the operating temperature in the first polymerization reactor (R1). Therefore, it is preferable that...

[0346] (a) The operating temperature in the first polymerization reactor (R1) is in the range of 62 to 85°C, more preferably in the range of 65 to 82°C, and even more preferably in the range of 67 to 80°C, such as 70 to 80°C; and

[0347] (b) The operating temperature in the second polymerization reactor (R2) is in the range of 62 to 95°C, more preferably in the range of 65 to 92°C, and even more preferably in the range of 67 to 88°C.

[0348] The condition is that the operating temperature in the second polymerization reactor (R2) is equal to or higher than the operating temperature in the first polymerization reactor (R1).

[0349] Typically, the pressure in the first polymerization reactor (R1), preferably the loop reactor (LR), is in the range of 20 to 80 bar, preferably in the range of 30 to 70 bar, such as 35 to 65 bar, while the pressure in the second polymerization reactor (R2) (i.e., the (first) gas phase reactor (GPR1)) and any optional subsequent reactor (such as the third polymerization reactor (R3), for example the second gas phase reactor (GPR2)) is in the range of 5 to 50 bar, preferably in the range of 15 to 40 bar.

[0350] Preferably, hydrogen is added to each polymerization reactor to control the molecular weight, i.e., the melt flow rate MFR2.

[0351] Preferably, the average residence time in polymerization reactors (R1) and (R2) is relatively long. Typically, the average residence time (τ) is defined as the reaction volume (V). R ) and the reactor volumetric outflow rate (Q) o The ratio of V to V R / Q o ), that is, τ=V R / Q o [τ=V R / Q o In the case of a loop reactor, the reaction volume (V) R () equals the reactor volume.

[0352] Therefore, the average residence time (τ) in the first polymerization reactor (R1) is preferably at least 15 min, more preferably in the range of 15 to 80 min, even more preferably in the range of 20 to 60 min, such as in the range of 24 to 50 min, and / or the average residence time (τ) in the second polymerization reactor (R2) is preferably at least 70 min, more preferably in the range of 70 to 220 min, even more preferably in the range of 80 to 210 min, still more preferably in the range of 90 to 200 min, such as in the range of 90 to 190 min. Preferably, the average residence time (τ) in the third polymerization reactor (R3) (if present) is preferably at least 30 min, more preferably in the range of 30 to 120 min, even more preferably in the range of 40 to 100 min, such as in the range of 50 to 90 min.

[0353] As described above, in addition to the (primary) polymerization of propylene homopolymer in at least two polymerization reactors (R1, R3 and optional R3), the preparation of propylene homopolymer may also include prepolymerization in a prepolymerization reactor (PR) upstream of the first polymerization reactor (R1).

[0354] Polypropylene (pre-PP) is produced in a prepolymerization reactor (PR). Prepolymerization is carried out in the presence of a single active site catalyst (SSC). According to this embodiment, the single active site catalyst (SSC) is introduced into the prepolymerization step. However, this does not preclude the option of adding an additional cocatalyst at a later stage, such as in the polymerization process, for example in the first reactor (R1). In one embodiment, if prepolymerization is applied, all components of the single active site catalyst (SSC) are added only to the prepolymerization reactor (PR).

[0355] The prepolymerization reaction is typically carried out at a temperature of 0 to 60°C, preferably 15 to 50°C, and more preferably 20 to 45°C.

[0356] The pressure in the prepolymerization reactor is not critical, but it must be high enough to keep the reaction mixture in the liquid phase. Therefore, the pressure can be 20 to 100 bar, for example, 30 to 70 bar.

[0357] In a preferred embodiment, prepolymerization is carried out as a bulk slurry polymerization in liquid propylene, i.e., the liquid phase mainly comprises propylene, optionally with inert components dissolved therein. Furthermore, according to the invention, as described above, ethylene feed is used during prepolymerization.

[0358] Other components can also be added to the prepolymerization stage. Therefore, as is known in the art, hydrogen can be added to the prepolymerization stage to control the molecular weight of polypropylene (pre-PP). Furthermore, antistatic additives can be used to prevent particles from adhering to each other or to the reactor wall.

[0359] Precise control of prepolymerization conditions and reaction parameters is within the scope of the art.

[0360] Due to the process conditions defined above in the prepolymerization, a mixture (MI) of single active site catalyst (SSC) and polypropylene (pre-PP) produced in the prepolymerization reactor (PR) is preferably obtained. Preferably, the single active site catalyst (SSC) is (well) dispersed in the polypropylene (pre-PP). In other words, the single active site catalyst (SSC) particles introduced into the prepolymerization reactor (PR) are broken into smaller fragments that are uniformly distributed in the grown polypropylene (pre-PP). The size of the introduced single active site catalyst (SSC) particles and the resulting fragments are not necessarily relevant to the present invention and are within the knowledge of those skilled in the art.

[0361] As described above, if prepolymerization is used, after the prepolymerization, a mixture (MI) of the single active site catalyst (SSC) and the polypropylene (pre-PP) produced in the prepolymerization reactor (PR) is transferred to the first reactor (R1). Typically, the total amount of polypropylene (pre-PP) in the final propylene copolymer (R-PP) is quite low, usually not exceeding 5.0% by weight, more preferably not exceeding 4.0% by weight, and even more preferably in the range of 0.5% to 4.0% by weight, such as in the range of 1.0% to 3.0% by weight.

[0362] Without using prepolymerization, propylene and other components (such as single active center catalyst (SSC)) are directly introduced into the first polymerization reactor (R1).

[0363] Therefore, preferably, the propylene homopolymer is produced in a method comprising the steps described above under the conditions set forth above.

[0364] (a) In the first polymerization reactor (R1), i.e., in the loop reactor (LR), propylene is polymerized to obtain the first fraction (PP2a) of the second propylene polymer.

[0365] (b) The first fraction (PP2a) of the second propylene polymer is transferred to the second polymerization reactor (R2).

[0366] (c) In the second polymerization reactor (R2), propylene is polymerized in the presence of the first fraction (PP2a) of the second propylene polymer to obtain the second fraction (PP2b) of the second propylene polymer, the first fraction (PP2a) of the second propylene polymer and the second first fraction (PP2b) of the second propylene polymer forming the second propylene polymer (PP2).

[0367] The prepolymerization described above can be completed before step (a).

[0368] As noted above, a single active site catalyst (SSC) should be used in the specific methods for preparing propylene homopolymers as defined above. Therefore, the single active site catalyst (SSC) will now be described in more detail.

[0369] The single-active-site catalyst according to the present invention can be any supported metallocene catalyst suitable for the production of highly isotactic polypropylene.

[0370] Preferably, the single active site catalyst (SSC) comprises a metallocene complex, a cocatalyst system containing a boron-containing cocatalyst and / or an aluminoxane cocatalyst, and a silica support.

[0371] In particular, preferably, the single active site catalyst (SSC) contains

[0372] (i) Metallocene complexes having the general formula (V)

[0373]

[0374] Each X is independently a σ-donor ligand.

[0375] L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2-, and -R'2Ge-, wherein each R' is independently a hydrogen atom or optionally contains one or more heteroatoms or fluorine atoms from groups 14 to 16 of the periodic table. 20 - A hydrocarbon group, or optionally two R' groups together, can form a ring.

[0376] Each R 1 Independently identical or capable of being different, and being hydrogen, straight-chain or branched C1-C6-alkyl, C 7-20 -Aryl group, C 7-20 -alkylaryl or C 6-20 -Aryl or OY group, where Y is C 1-10 - hydrocarbon group, and optionally two adjacent R 1 The groups can be part of a ring containing the phenyl carbon to which they are bonded.

[0377] Each R 2 Independently identical or capable of being different, and being CH2-R 8 Group, wherein R 8 C is H or a straight chain or a branched chain 1-6 -alkyl, C 3-8 -cycloalkyl, C 6-10 -Aryl

[0378] R3 It is a straight-chain or branched C1-C6-alkyl, C 7-20 -Aryl group, C 7-20 -Alkaryl or C6-C 20 -Aryl

[0379] R 4 For C(R) 9 )3 groups, of which R 9 It is a straight-chain or branched C1-C6-alkyl group.

[0380] R 5 It is aliphatic C1-C atoms, which are hydrogen or optionally contain one or more heteroatoms from groups 14 to 16 of the periodic table. 20 -Hydrocarbon group;

[0381] R 6 It is aliphatic C1-C atoms, which are hydrogen or optionally contain one or more heteroatoms from groups 14 to 16 of the periodic table. 20 -hydrocarbon group; or

[0382] R 5 and R 6 They can form a 5-membered saturated carbon ring, which is optionally bound by n groups R. 10 Replacement, where n is 0 to 4;

[0383] Each R 10 Same or different, and can be C1-C 20 - A hydrocarbon group, or optionally a C1-C group containing one or more heteroatoms belonging to groups 14 to 16 of the periodic table. 20 -Hydrocarbon group;

[0384] R 7 It is an H or a straight-chain or branched C1-C6-alkyl group or optionally surrounded by 1 to 3 R groups. 11 Substituted aryl or heteroaryl groups having 6 to 20 carbon atoms,

[0385] Each R 11 Independently identical or capable of being different, and being hydrogen, straight-chain or branched C1-C6-alkyl, C 7-20 -Aryl group, C 7-20 -alkylaryl or C 6-20 -Aryl or OY group, where Y is C 1-10 -Hydrocarbon group,

[0386] (ii) a cocatalyst system comprising a boron-containing cocatalyst and / or an aluminoxane cocatalyst, and

[0387] (iii) Silica carrier.

[0388] The term "σ-donor ligand" is well known to those skilled in the art, referring to a group that bonds to a metal via a σ bond. Therefore, the anionic ligand "X" can be independently a halogen or selected from the group consisting of R', OR', SiR'3, OSiR'3, OSO2CF3, OCOR', SR', NR'2, or PR'2, wherein R' is independently hydrogen, straight-chain or branched, cyclic or acyclic, C1 to C2 groups. 20 Alkyl, C2 to C 20 alkenyl, C2 to C 20 alkynyl group, C3 to C 12 cycloalkyl, C6 to C 20 Aryl, C7 to C 20 Aryl alkyl, C7 to C 20 Alkyl, C8 to C 20 Arylene group, wherein the R' group may optionally contain one or more heteroatoms belonging to groups 14 to 16. In a preferred embodiment, the anionic ligand "X" is identical and may be a halogen, such as Cl, or a methyl or benzyl group.

[0389] Preferred monovalent anionic ligands are halogens, especially chlorine (Cl).

[0390] More preferably, the metallocene catalyst has the formula (Va)

[0391]

[0392] Where R 1 Independently identical or may be different, and is hydrogen or a straight-chain or branched C1-C6 alkyl group, thereby having at least one phenyl group R. 1 It is not hydrogen.

[0393] R′ is C1-C 10 Hydrocarbon group, preferably C1-C4 hydrocarbon group, and more preferably methyl group, and

[0394] X can be independently a hydrogen atom, a halogen atom, a C1-C6 alkoxy group, a C1-C6 alkyl group, a phenyl group, or a benzyl group.

[0395] Most preferably, X is chlorine, benzyl, or methyl. Preferably, the two X groups are identical. The most preferred options are two chlorides, two methyl groups, or two benzyl groups, especially two chlorides.

[0396] Preferred complexes for metallocene catalysts include:

[0397] Racemic-dimethylsilylbis[2-methyl-4-(3',5'-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride

[0398] 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,

[0399] 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,

[0400] 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,

[0401] 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,

[0402] 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,

[0403] 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.

[0404] Particularly preferred is 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-butylinden-1-yl]zirconium dichloride (Vb).

[0405]

[0406] The ligands required to form the complexes of the present invention and thus the catalysts of the present invention can be synthesized by any method, and skilled organic chemists are capable of designing various synthetic schemes to produce the necessary ligand materials. For example, WO2007 / 116034 discloses the necessary chemistry. Synthetic schemes can also generally be found in WO 2002 / 02576, WO 2011 / 135004, WO 2012 / 084961, WO 2012 / 001052, WO 2011 / 076780, WO 2015 / 158790 and WO 2018 / 122134. Particular reference is made to WO 2019 / 179959, which describes the most preferred catalyst of the present invention.

[0407] According to the present invention, a cocatalyst system comprising a boron-containing cocatalyst and / or an aluminoxane cocatalyst is used in combination with the metallocene catalyst complex defined above.

[0408] Aluminoxane cocatalysts can be the aluminoxane cocatalysts of formula (VI):

[0409]

[0410] Where n is between 6 and 20 and R has the following meanings.

[0411] Aluminoxanes are formed during the partial hydrolysis of organoaluminum compounds, such as compounds having the formulas AlR3, AlR2Y, and Al2R3Y3, where R can be, for example, C1-C2. 10 -alkyl, preferably C1-C5-alkyl, or C3-C 10 -Cycloalkyl, C7-C 12 Aryl or C7-C 12 Alkyl aryl and / or phenyl or naphthyl, wherein Y can be hydrogen, halogen, preferably chlorine or bromine, or C1-C 10 -alkoxy, preferably methoxy or ethoxy. The resulting oxyaluminoxane is usually not a pure compound, but a mixture of oligomers of formula (VI).

[0412] The preferred aluminoxane is methylaluminoxane (MAO). Since the aluminoxanes used as cocatalysts according to the present invention are prepared by means of their own process rather than as pure compounds, the molar concentrations of the aluminoxane solutions mentioned below are based on their aluminum content.

[0413] According to the present invention, a boron-containing cocatalyst can be used instead of an aluminum oxane cocatalyst, or an aluminum oxane cocatalyst can be used in combination with a boron-containing cocatalyst.

[0414] Those skilled in the art will understand that, in the case of using a boron-based cocatalyst, the complex is typically pre-alkylated by reacting it with an alkylaluminum compound (such as TIBA). This procedure is well known, and any suitable alkylaluminum, such as Al(C)2, can be used. 1-6 -alkyl)3. Preferred alkylaluminum compounds are triethylaluminum, triisobutylaluminum, triisohexylaluminum, tri-n-octylaluminum, and triisooctylaluminum.

[0415] Alternatively, when using a borate cocatalyst, the metallocene catalyst complex is in its alkylated form, i.e., a dimethyl or dibenzyl metallocene catalyst complex can be used, for example.

[0416] The boron-containing cocatalysts of interest include cocatalysts of formula (VII).

[0417] BY3(VII)

[0418] Wherein Y is the same or different and is a hydrogen atom, an alkyl group having 1 to about 20 carbon atoms, an aryl group having 6 to about 15 carbon atoms, an alkylaryl group, an aralkyl group, a haloalkyl group, or a haloaryl group, each group having 1 to 10 carbon atoms in the alkyl group and 6 to 20 carbon atoms in the aryl group, or each group having fluorine, chlorine, bromine, or iodine. Preferred embodiments of Y are methyl, propyl, isopropyl, isobutyl, or trifluoromethyl, unsaturated groups (such as aryl or haloaryl groups (e.g., phenyl, tolyl, benzyl, p-fluorophenyl, 3,5-difluorophenyl, pentachlorophenyl, pentafluorophenyl, 3,4,5-trifluorophenyl, and 3,5-bis(trifluoromethyl)phenyl)). Preferred options are trifluoroborane, triphenylborane, tri(4-fluorophenyl)borane, tri(3,5-difluorophenyl)borane, tri(4-fluoromethylphenyl)borane, tri(2,4,6-trifluorophenyl)borane, tri(pentafluorophenyl)borane, tri(tolyl)borane, tri(3,5-dimethyl-phenyl)borane, tri(3,5-difluorophenyl)borane and / or tri(3,4,5-trifluorophenyl)borane.

[0419] Tris(pentafluorophenyl)borane is particularly preferred.

[0420] However, borates, i.e., compounds containing borate 3+ ions, are preferred. This ionic cocatalyst preferably contains a noncoordinate anion, such as tetra(pentafluorophenyl)borate and tetraphenylborate. Suitable counterions are protonated amines or aniline derivatives, such as methylammonium, aniline, dimethylammonium, diethylammonium, N-methylaniline, diphenylammonium, N,N-dimethylaniline, trimethylammonium, triethylammonium, tri-n-butylammonium, methyldiphenylammonium, pyridinium, p-bromo-N,N-dimethylaniline, or p-nitro-N,N-dimethylaniline.

[0421] Preferred ionic compounds that can be used according to the present invention include:

[0422] Triethylammonium tetra(phenyl)borate

[0423] Tributylammonium tetra(phenyl)borate,

[0424] Trimethylammonium tetra(tolyl)borate

[0425] Tributylammonium tetra(tolyl)borate

[0426] Tributylammonium tetra(pentafluorophenyl)borate

[0427] Tripropylammonium tetra(dimethylphenyl)borate

[0428] Tributylammonium tetra(trifluoromethylphenyl)borate

[0429] Tributylammonium tetra(4-fluorophenyl)borate,

[0430] N,N-dimethylcyclohexylammonium tetra(pentafluorophenyl)boronic acid

[0431] N,N-dimethylbenzylammonium tetra(pentafluorophenyl)boronic acid

[0432] N,N-dimethylphenylammonium tetra(phenyl)boronic acid

[0433] N,N-diethylphenylammonium tetra(phenyl)boronic acid

[0434] N,N-dimethylphenylammonium tetra(pentafluorophenyl)boronic acid

[0435] N,N-di(propylammonium) tetra(pentafluorophenyl)borate,

[0436] di(cyclohexyl)ammonium tetra(pentafluorophenyl)borate,

[0437] Triphenylphosphonium tetra(phenyl)borate,

[0438] Triethylphosphonium tetra(phenyl)borate,

[0439] Diphenylphosphonium tetra(phenyl)borate,

[0440] Tris(methylphenyl)phosphonium tetra(phenyl)borate,

[0441] Tris(dimethylphenyl)phosphonium tetra(phenyl)borate,

[0442] Triphenylcarbenium tetrakis(pentafluorophenyl)borate

[0443] Or ferrocenium tetrakis(pentafluorophenyl)borate.

[0444] Preferably, it is triphenylcarbomonium tetra(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetra(pentafluorophenyl)borate, or N,N-dimethylbenzylammonium tetra(pentafluorophenyl)borate.

[0445] Surprisingly, certain boron cocatalysts have been found to be particularly preferred. Therefore, preferred borates used in this invention include triphenylmethyl ions. Thus, N,N-dimethylammonium tetrapentafluorophenyl borate and Ph3CB(PhF5)4 and their analogues are particularly preferred.

[0446] According to the present invention, the preferred cocatalyst is an aluminum oxane, more preferably a methyl aluminum oxane, a combination of an aluminum oxane with an alkyl aluminum, boron or borate cocatalyst, and a combination of an aluminum oxane with a boron-based cocatalyst.

[0447] The appropriate amount of catalyst is well known to technicians.

[0448] The molar ratio of boron to metallocene ions can be in the range of 0.5:1 to 10:1 mol / mol, preferably in the range of 1:1 to 10:1, and especially in the range of 1:1 to 5:1 mol / mol.

[0449] The molar ratio of Al to metal ions in aluminoxane can be in the range of 1:1 to 2000:1 mol / mol, preferably in the range of 10:1 to 1000:1, and more preferably in the range of 50:1 to 500:1 mol / mol.

[0450] The catalyst can be used in supported or unsupported form, preferably in supported form. The particulate support material used is preferably an organic or inorganic material, such as silica, alumina, or zirconium oxide, or a mixed oxide, such as silica-alumina, particularly silica, alumina, or silica-alumina. Silica support is preferred. Those skilled in the art know the procedures required for supporting metallocene catalysts.

[0451] Particularly preferred is that the carrier is a porous material so that the complex can be loaded into the pores of the carrier, for example using methods similar to those described in WO94 / 14856 (Mobil), WO95 / 12622 (Borealis) and WO2006 / 097497.

[0452] The average particle size of silica supports is typically 10 to 100 μm. However, it has been shown that if the support has an average particle size d50 of 15 to 80 μm, preferably 18 to 50 μm, it can yield particular advantages.

[0453] The average pore size of the silica support can be in the range of 10 to 100 nm, and the pore volume is 1 to 3 mL / g.

[0454] Examples of suitable support materials include, for example, ES757 manufactured and sold by PQ Corporation, Sylopol 948 manufactured and sold by Grace Corporation, or SUNSPERA DM-L-303 silica manufactured by AGC Si-Tech Corporation. The support may optionally be calcined prior to its use in catalyst preparation to achieve optimal silanol group content.

[0455] The use of these carriers is common practice in this field.

[0456] Products

[0457] The present invention also relates to articles comprising the nonwoven fabric (NF) as described above, wherein articles selected from the group consisting of filter media (filters), diapers, sanitary napkins, panty liners, adult urinary incontinence products, protective clothing, surgical drapes, surgical gowns and surgical garments comprise the nonwoven fabric (NF) of the present invention.

[0458] Preferably, the amount of nonwoven fabric (NF) contained in the article of the present invention is in the range of 90 to 100% by weight relative to the total weight of the article, more preferably in the range of 95 to 100% by weight, and most preferably in the range of 99 to 100% by weight.

[0459] All preferred embodiments described above can be applied to the articles of the present invention with necessary modifications.

[0460] Example

[0461] A. Measurement Method

[0462] Unless otherwise defined, the following definitions of terms and measurement methods apply to the above general description of the invention, including the claims, and the following embodiments.

[0463] Quantitative analysis of microstructure using NMR spectroscopy

[0464] Quantitative nuclear magnetic resonance (NMR) spectroscopy was used to quantify the isotactic regularity and regional regularity of propylene homopolymers.

[0465] Adopt for 1 H and 13 A Bruker Advance III 400 NMR spectrometer, operating at 400.15 MHz and 100.62 MHz respectively, recorded quantitative data in solution. 13 C{ 1 H⁺ NMR spectroscopy. All spectra were used. 13The optimized 10mm extended temperature probe recorded at 125°C, and nitrogen was used for all pneumatic devices.

[0466] For the propylene homopolymer, approximately 200 mg of material was dissolved in 1,2-tetrachloroethane-d2 (TCE-d2). To ensure solution homogeneity, the NMR tube was further heated in a rotary oven for at least 1 hour after the initial sample preparation in the heating block. After being inserted into the magnet, the tube was rotated at 10 Hz. This setup was chosen primarily for the high resolution required for quantification of stereoregularity distribution (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443; Busico, V.; Cipullo, R., Monaco, G., Vacatello, M., Segre, AL, Macromolecules 30 (1997) 6251). Standard single-pulse excitation was used, employing a NOE 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, 11289). A total of 8192 (8k) transient signals were acquired for each spectrum.

[0467] 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. For propylene homopolymers, all chemical shifts were internally referenced at 21.85 ppm for the methyl isotactic pentamematic group (mmmm).

[0468] Characteristic signals were observed corresponding to regional defects (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253; Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157; Cheng, HN, Macromolecules 17 (1984), 1950) or comonomers.

[0469] Stereoregularity distribution was quantified by integrating the methyl region between 23.6 and 19.7 ppm, correcting for any sites unrelated to the stereo sequence of interest (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443; Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, AL, Macromolecules 30 (1997) 6251).

[0470] Specifically, the quantitative influence of regional defects and comonomers on stereoregularity distribution was corrected by subtracting representative regional defect and comonomer integrals from specific integral regions of the stereo sequence. Isosteretic regularity was determined at the quintet level and reported as the percentage of isosteretic quintet (mmmm) sequences out of all quintet sequences:

[0471] [mmmm]% = 100 * (mmmm / sum of all five-unit groups).

[0472] The presence of the 2,1-erythromeric regional defect was indicated by the presence of two methyl sites at 17.7 and 17.2 ppm, and was confirmed by other characteristic sites. No characteristic signals corresponding to other types of regional defects were observed (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253).

[0473] The amount of defects in the 2,1 erythrocyanine region was quantified by averaging the integrals of the two characteristic methyl sites at 17.7 and 17.2 ppm.

[0474] P 21e =(I e6 +I e8 ) / 2.

[0475] The number of primary inserted propenes (1,2) was quantified based on the methyl region, with corrections made for sites within this region that are unrelated to primary insertions and for primary insertion sites not included in this region.

[0476] P 12 =I CH3 +P 12e

[0477] The total amount of propylene was quantified as the sum of primary inserted propylene and all other present regional defects:

[0478] P 总 =P 12 +P 21e

[0479] Quantify the molar percentage of defects in the 2,1 erythroline region relative to all propylene:

[0480] [21e] mole% = 100*(P) 21e / P 总 ).

[0481] MFR2 (230℃) is measured according to ISO 1133 (230℃, 2.16kg load).

[0482] Number average molecular weight (M n ), weight-average molecular weight (M) w ) and molecular weight distribution (MWD)

[0483] The average molecular weight (Mw, Mn) and molecular weight distribution (MWD) (i.e., Mw / Mn (where Mn is the number-average molecular weight and Mw is the weight-average molecular weight)) were determined by gel permeation chromatography (GPC) according to ISO 16014-4:2003 and ASTM D 6474-99. A PolymerChar GPC instrument equipped with an infrared (IR) detector, 3x Olexis and 1x Olexis Guard columns from Polymer Laboratories, and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg / L 2,6-di-tert-butyl-4-methylphenol) as solvent at a constant flow rate of 1 mL / min at 160 °C. 200 μL of sample solution was injected for each analysis. The column set was calibrated using a universal calibration (according to ISO 16014-2:2003) with at least 15 narrow MWD polystyrene (PS) standards ranging from 0.5 kg / mol to 11,500 kg / mol. The Mark Houwink constants for PS, PE, and PP used were as described according to ASTM D 6474-99. All samples were prepared by dissolving 5.0 to 9.0 mg of polymer in 8 mL of stable TCB (same as the mobile phase) at 160 °C with continuous gentle shaking in the autosampler of the GPC instrument for a maximum of 2.5 h (for PP) or a maximum of 3 h (for PE).

[0484] Xylene soluble fraction at room temperature (XS, wt%): The amount of polymer soluble in xylene was determined at 25°C according to ISO 16152; 5th edition; 2005-07-01.

[0485] DSC analysis, melting temperature (T) m ) and heat of fusion (H f Crystallization temperature (T) c ) and heat of crystallization (H c): Samples of 5 to 7 mg were measured using a TAInstrument Q200 Differential Scanning Calorimeter (DSC). The DSC was operated according to ISO 11357 / Part 3 / Method C2 with heating / cooling / heating cycles at a scan rate of 10 °C / min over a temperature range of -30 to +225 °C. Crystallization temperature (T c The heat of crystallization (Hc) and the heat of crystallization (T) are determined by the cooling step, while the melting temperature (T) m The heat of fusion (Hf) and the heat of melting (Hf) are determined by the second heating step.

[0486] Glass transition temperature T g The results were determined by dynamic mechanical analysis according to ISO 6721-7. The sample (40×10×1mm) was subjected to a heating rate of 2℃ / min and a frequency of 1Hz between -100℃ and +150℃. 3 Measurements were taken in torsion mode.

[0487] Weight of nonwoven fabrics

[0488] The unit weight (gram weight) of nonwoven fabrics, expressed in g / m² 2 The unit is determined according to ISO 536:1995.

[0489] filament fineness

[0490] Filament fineness (in denier) is calculated from the average fiber diameter using the following formula:

[0491] Fiber diameter (in centimeters) = (4.444 × 10⁻⁶ × denier / 0.91 × π)¹ / ²

[0492] Mechanical properties of nonwoven fabrics

[0493] The mechanical properties of nonwoven fabrics were determined according to EN 29073-3(1989) "Test methods for nonwovens - Determination of tensile strength and elongation".

[0494] The tensile modulus was measured according to ISO 527-2 (crosshead speed = 1 mm / min; test speed 50 mm / min at 23°C) using injection-molded specimens (dog bone shape, 4 mm thickness) as described in EN ISO 1873-2. Measurements were performed after a 96-hour conditioning period for the specimens.

[0495] Average fiber diameter in nonwoven fabrics

[0496] The number-average fiber diameter was determined using scanning electron microscopy (SEM). A representative portion of the web was selected and SEM micrographs at an appropriate magnification were recorded. The diameters of 20 fibers were then measured, and the number-average diameter was calculated.

[0497] hydrostatic pressure

[0498] The hydrostatic pressure or water resistance determined by hydrostatic pressure testing is measured according to WSP 80.6(09), the WSP (Global Strategic Partner) standard published in December 2009. This industry standard is further based on ISO 811:1981 and uses 100 cm at 23°C. 2 The sample was tested with pure water, and the water pressure was increased at a rate of 10 cm / min.

[0499] B. Example

[0500] The catalyst used in the polymerization process of the second propylene polymer (PP2) of the present invention for the spunbond layer (S) used in Embodiment (E2) of the present invention is 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, as disclosed as MC-2 in WO 2019 / 179959 A1. The production of the supported metallocene catalyst is similar to that of IE2 in WO 2019 / 179959 A1.

[0501] The catalysts used in the polymerization processes of the comparative second propylene polymer (PP2) for the spunbond layer (S) used in Comparative Example (E1) and the first propylene polymer (PP1) used as the meltblown layer in all Examples (E3) are prepared as follows:

[0502] Chemicals used:

[0503] A 20% solution of butyl ethyl magnesium (Mg(Bu)(Et), BEM) in toluene provided by Chemitura

[0504] 2-Ethylhexanol supplied by Amphochem

[0505] 3-Butoxy-2-propanol-(DOWANOL) supplied by Dow TM PnB)

[0506] Bis(2-ethylhexyl)citridine ester provided by SynphaBase

[0507] TiCl4 supplied by Millenium Chemicals

[0508] Toluene supplied by Aspokem

[0509] Provided by Evonik 1-254

[0510] heptane supplied by Chevron

[0511] Preparation of magnesium alkoxy compounds

[0512] An alkoxymagnesium solution was prepared in a 20-liter stainless steel reactor by adding a mixture of 4.7 kg of 2-ethylhexanol and 1.2 kg of butoxypropanol to a 20% by weight solution (11 kg) of butyl ethyl magnesium (Mg(Bu)(Et)) in toluene under stirring (70 rpm). The reactor contents were maintained below 45°C during the addition. After the addition was complete, the reaction mixture was continued to mix at 60°C (70 rpm) for 30 min. After cooling to room temperature, 2.3 kg of the donor bis(2-ethylhexyl) citrate was added to the alkoxymagnesium solution while maintaining a temperature below 25°C. Mixing was continued for 15 min under stirring (70 rpm).

[0513] Preparation of solid catalyst components

[0514] 20.3 kg of TiCl4 and 1.1 kg of toluene were added to a 20-liter stainless steel reactor. Mixing was carried out at 350 rpm and the temperature was maintained at 0°C. 14.5 kg of the alkoxymagnesium compound prepared in Example 1 was added over 1.5 hours. 1.7 liters were then added. 1-254 and 7.5 kg of heptane were mixed at 0°C for 1 hour, and the temperature of the resulting emulsion was raised to 90°C over 1 hour. After 30 minutes, mixing was stopped, the catalyst droplets were solidified, and the formed catalyst particles were allowed to settle. After settling (1 hour), the supernatant was siphoned off. The catalyst particles were then washed with 45 kg of toluene at 90°C for 20 minutes, followed by two heptane washes (30 kg, 15 min each). During the first heptane wash, the temperature was lowered to 50°C, and during the second wash, the temperature was lowered to room temperature.

[0515] The catalyst thus obtained is used in conjunction with triethylaluminum (TEAL) as a co-catalyst and dicyclopentyldimethoxysilane (D-donor) as an E1 donor or cyclohexylmethyldimethoxysilane (C-donor) as an E3 donor.

[0516] The ratios of aluminum to donor, aluminum to titanium, and polymerization conditions are shown in Table 1.

[0517] Table 1: Preparation of basic polymers E1, E2 and E3

[0518]

[0519] Polymers E1, E2 and E3 were mixed with 400 ppm calcium stearate (CAS No. 1592-23-0) and 1000 ppm Irganox 1010 (pentaerythritol tetrakis(3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate, CAS No. 6683-19-8) supplied by BASF AG of Germany.

[0520] In the second step, polymers E1, E2, and E3 were subjected to viscosity-reducing cracking using a co-rotating twin-screw extruder at 200 to 230°C with an appropriate amount of (tert-butylperoxy)-2,5-dimethylhexane (Trigonox 101, sold by Akzo Nobel, Netherlands) to achieve the target MFR2. The properties of the propylene homopolymer after viscosity-reducing cracking are summarized in Table 2.

[0521] Table 2: Performance of the embodiments and comparative examples of the present invention after viscosity reduction cracking

[0522]

[0523] nd = Not detected

[0524] na = Not applicable

[0525] Nonwoven fabrics in The Reicofil RF5 is produced on a semi-commercial production line equipped with spunbond (S-extruder 1) - spunbond (S-extruder 2) - meltblown (M-extruder 1) - meltblown (M-extruder 2) - spunbond (S-extruder 3) beams. The machine was adjusted by those skilled in the art to achieve the target settings. Table 3 lists the key parameters. Each product has a yield of 11.0 g / m³. 2 The spunbond layer and 2.0 g / m 2 The meltblown layer has a basis weight of 3.67 g / m² for each individual spunbond layer. 2 The weight of each individual meltblown layer is 1.0 g / m². 2 .

[0526] Table 3: Process conditions used for production and properties of nonwoven fabrics

[0527]

[0528]

[0529] The resulting multilayer nonwoven fabric is then passed through calendering rolls to bond the layers together. Numerous comparative nonwoven fabrics and numerous nonwoven fabrics of the present invention are processed at different calendering temperatures, and the properties of these nonwoven fabrics are then evaluated as a function of calendering temperature.

[0530] As shown in Figure 1, the hydrostatic pressure (HH) and machine transverse tensile strength (F-CD) of the nonwoven fabrics exhibit a correlation with calendering temperature. While HH decreases significantly at higher calendering temperatures, the nonwoven fabric of the present invention maintains a high HH at relatively high calendering temperatures before finally beginning to decrease at calendering temperatures exceeding 165°C (in contrast to the control nonwoven fabric, which begins to decrease significantly at temperatures exceeding 150°C). For both embodiments, the F-CD of both compositions increases with increasing calendering temperature; however, the measurements of the nonwoven fabric of the present invention are superior to those of the control nonwoven fabric at all temperatures.

[0531] Therefore, it can be concluded that the nonwoven fabrics of the present invention have superior mechanical and barrier properties compared to those of comparative nonwoven fabrics, especially at higher calendering temperatures. Furthermore, the low basis weight of the nonwoven fabrics helps to avoid undue environmental impact when used in hygiene products.

Claims

1. A nonwoven fabric comprising a multilayer structure, said multilayer structure comprising: i) at least one meltblown layer comprising meltblown fibers, the meltblown fibers comprising a first propylene polymer having: a) Through the range of 0.0 to 0.1 mol%. 13 The amount of defects in the 2,1-region determined by C-NMR spectroscopy; and b) Melting temperature T, determined by differential scanning calorimetry, in the range of 155 to 170 °C. m , ii) at least one spunbond layer comprising spunbond fibers, the spunbond fibers comprising a second propylene polymer, the second propylene polymer having: a) Passing within the range of 0.45 to 1.5 mol%. 13 The amount of defects in the 2,1-region determined by C-NMR spectroscopy; and b) Melting temperature T, determined by differential scanning calorimetry, in the range of 145 to 160 °C. m , Wherein the melting temperature T of the first propylene polymer m The melting temperature T of the second propylene polymer m The temperature is at least 5.0°C, and the first propylene polymer has been polymerized in the presence of: a) A Ziegler-Natta catalyst comprising a compound of a transition metal from Group 4 to 6 of IUPAC, a Group 2 metal compound, and an internal donor, wherein the internal donor is a non-phthalic acid compound. b) Optional co-catalysts, and c) Optional external donor, and The second propylene polymer has been polymerized in the presence of a single active site catalyst.

2. The nonwoven fabric according to claim 1, wherein the total basis weight of one or more meltblown layers, as determined according to ISO 536:1995, is between 0.8 and 30 g / m². 2 Within the range, and / or the total basis weight of one or more spunbond layers, as determined according to ISO 536:1995, is between 5.0 and 100 g / m². 2 Within the range.

3. The nonwoven fabric according to claim 1 or claim 2, wherein the first propylene polymer and / or the second propylene polymer are propylene homopolymers or propylene-ethylene copolymers, wherein... 1 The ethylene content determined by H-NMR spectroscopy is less than 0.5 mol.

4. The nonwoven fabric according to claim 1 or claim 2, wherein the first propylene polymer has at least one of the following properties: a) Melt flow rate MFR2, measured according to ISO 1133 at 230 °C and 2.16 kg, in the range of 450 to 2000 g / 10 min; and b) Molecular weight distribution (Mw / Mn) determined by gel permeation chromatography in the range of 2.5 to 5.

0.

5. The nonwoven fabric according to claim 1 or claim 2, wherein the second propylene polymer has at least one of the following properties: a) Melt flow rate MFR2, measured according to ISO 1133 at 230 °C and 2.16 kg, in the range of 5.0 to 50 g / 10 min; and b) Molecular weight distribution (Mw / Mn) determined by gel permeation chromatography in the range of 2.0 to 4.

5.

6. The nonwoven fabric according to claim 1 or claim 2, wherein the second propylene polymer has a xylene cold-soluble content in the range of 0.1 to 2.0% by weight, as determined according to ISO 16152.

7. The nonwoven fabric according to claim 1 or claim 2, wherein the first propylene polymer has been subjected to viscosity-reducing cracking, and wherein the first propylene polymer satisfies any one or both of inequality (I) or inequality (II). MFR 最终 It is the melt flow rate MFR2 measured at 230°C according to ISO 1133 after viscosity-reducing cracking, and MFR 初始 It is the melt flow rate MFR2 measured at 230°C according to ISO 1133 before viscosity-reducing cracking; and Among them MWD 最终 The molecular weight distribution (Mw / Mn) after viscosity reduction cracking, determined by gel permeation chromatography, and the MWD... 初始 It is the molecular weight distribution Mw / Mn determined by gel permeation chromatography before viscosity reduction cracking.

8. The nonwoven fabric according to claim 1 or claim 2, wherein the second propylene polymer has been subjected to viscosity-reducing cracking, and wherein the second propylene polymer satisfies any one or both of inequality (III) or inequality (IV). MFR 最终 It is the melt flow rate MFR2 measured at 230°C according to ISO 1133 after viscosity-reducing cracking, and MFR 初始 It is the melt flow rate MFR2 measured at 230°C according to ISO 1133 before viscosity-reducing cracking; and Among them MWD 最终 The molecular weight distribution (Mw / Mn) after viscosity reduction cracking, determined by gel permeation chromatography, and the MWD... 初始 It is the molecular weight distribution Mw / Mn determined by gel permeation chromatography before viscosity reduction cracking.

9. The nonwoven fabric according to claim 1 or claim 2, The internal donor is a non-phthalate ester.

10. The nonwoven fabric according to claim 1 or claim 2, wherein the single-active-center catalyst comprises (i) Metallocene complexes of general formula (V) Formula (V) Each X is independently a σ-donor ligand. L is a divalent bridge selected from -R'2C-, -R'2C-CR'2-, -R'2Si-, -R'2Si-SiR'2-, and -R'2Ge-, where each R' is independently a hydrogen atom or a C1-C atom. 20 -Hydrocarbon group, the C1-C 20 -The hydrocarbon group optionally contains one or more heteroatoms or fluorine atoms from groups 14 to 16 of the periodic table, or the two R' groups together can form a ring. Each R 1 Independently identical or capable of being different, and being hydrogen, straight-chain or branched C1-C6-alkyl, C 7-20 -Aryl group, C 7-20 -alkylaryl or C 6-20 -Aryl or OY group, where Y is C 1-10 - hydrocarbon group, and optionally two adjacent R 1 The groups can be part of a ring containing the phenyl carbon to which they are bonded. Each R 2 Independently identical or capable of being different, and being CH2-R 8 Group, wherein R 8 C is H or a straight chain or a branched chain 1-6 -alkyl, C 3-8 -cycloalkyl, C 6-10 -Aryl, R 3 It is a straight-chain or branched C1-C6-alkyl, C 7-20 -Aryl group, C 7-20 -Alkaryl or C6-C 20 -Aryl, R 4 For C(R) 9 )3 groups, of which R 9 It is a straight-chain or branched C1-C6-alkyl group. R 5 It is aliphatic C1-C atoms, which are hydrogen or optionally contain one or more heteroatoms from groups 14 to 16 of the periodic table. 20 -Hydrocarbon group; R 6 It is aliphatic C1-C atoms, which are hydrogen or optionally contain one or more heteroatoms from groups 14 to 16 of the periodic table. 20 -hydrocarbon group; or R 5 and R 6 They can form a 5-membered saturated carbon ring, which is optionally bound by n groups R. 10 Replacement, where n is 0 to 4; Each R 10 Same or different, and for C1-C 20 - A hydrocarbon group, or optionally a C1-C group containing one or more heteroatoms belonging to groups 14 to 16 of the periodic table. 20 -Hydrocarbon group; R 7 It is an H or a straight-chain or branched C1-C6-alkyl group or optionally surrounded by 1 to 3 R groups. 11 Substituted aryl or heteroaryl groups having 6 to 20 carbon atoms, Each R 11 Independently identical or capable of being different, and being hydrogen, straight-chain or branched C1-C6-alkyl, C 7-20 -Aryl group, C 7-20 -alkylaryl or C 6-20 -Aryl or OY group, where Y is C 1-10 -Hydrocarbon group, (ii) a cocatalyst system comprising a boron-containing cocatalyst and / or an aluminoxane cocatalyst, and (iii) Silica carrier.

11. The nonwoven fabric according to claim 1 or claim 2, wherein the multilayer structure comprises the following layers in a given order: i) At least one spunbond layer containing spunbond fibers; ii) at least one meltblown layer comprising meltblown fibers; and iii) At least one spunbond layer containing spunbond fibers, The instances of the spunbond layer may be the same or different, and the instances of the meltblown layer may be the same or different.

12. A method for producing the nonwoven fabric according to claim 11, comprising the following steps: a) The first spunbond layer is produced by depositing spunbond fibers through a spinneret. b) Optionally, at least one additional spunbond layer is produced by depositing spunbond fibers onto the first spunbond layer obtained in step a) through at least one additional spinneret, thereby obtaining a multilayer structure comprising two or more spunbond layers in sequence. c) A first meltblown layer is produced by depositing meltblown fibers onto the first spunbond layer obtained in step a) or the outermost spunbond layer obtained in step b) using an extruder, thereby obtaining a multilayer structure comprising one or more spunbond layers and meltblown layers in sequence. d) Optionally, at least one additional meltblown layer is produced by depositing meltblown fibers onto the first meltblown layer obtained in step c) using at least one additional extruder, thereby obtaining a multilayer structure comprising one or more spunbond layers and two or more meltblown layers in sequence. e) A second spunbond layer is produced by depositing spunbond fibers onto the first meltblown layer obtained in step c) or the outermost meltblown layer obtained in step d) through a spinneret, thereby obtaining a multilayer structure comprising one or more spunbond layers, one or more meltblown layers, and a spunbond layer in sequence. f) Optionally, at least one additional spunbond layer is produced by depositing spunbond fibers onto the second spunbond layer obtained in step e) through at least one additional spinneret, thereby obtaining a multilayer structure comprising one or more spunbond layers, one or more meltblown layers, and two or more spunbond layers in sequence.

13. The nonwoven fabric according to any one of claims 1 to 11, obtained by the method of claim 12.

14. An article comprising a nonwoven fabric according to any one of claims 1 to 11 or 13, wherein the article is selected from filter media, diapers, sanitary napkins, panty liners, adult incontinence products, protective clothing, surgical drapes, and surgical gowns.

15. An article comprising a nonwoven fabric according to any one of claims 1 to 11 or 13, wherein the article is selected from filters and surgical gowns.

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