Polypropylene resin composition and nonwoven fabric prepared using the same

Abstract

In the present invention, a polypropylene resin composition comprising an ethylene propylene copolymer and a nonwoven fabric produced therefrom are provided. In particular, the polypropylene resin composition of the present invention can be produced in the presence of a metallocene compound having a specific structure using a continuous reactor. The polypropylene resin composition of the present invention can maintain high strength as well as excellent processability. Thus, compared to the existing products, the polypropylene resin composition of the present invention can produce a soft nonwoven fabric by optimizing xylene solubles, ethylene content, melt index, crystallization temperature, tensile strength and flexural modulus, and having a narrow molecular weight distribution.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2021-0039665, filed with the Korean Intellectual Property Office on March 26, 2021, and Korean Patent Application No. 10-2022-0037393, filed on March 25, 2022, the disclosures of which are incorporated herein by reference in their entirety.

[0003] This invention relates to a polypropylene resin composition and nonwoven fabrics produced therefrom, wherein the polypropylene resin composition maintains high strength and excellent processability compared to existing products, and is suitable for soft nonwoven fabrics. Background Technology

[0004] Generally, nonwoven fabrics refer to fabrics made by bonding or interlocking aggregates of fibers through mechanical and chemical treatments (such as mechanical manipulation or thermal bonding) without undergoing spunbonding, weaving, or knitting processes. Nonwoven fabrics include felts, resin-bonded nonwovens, needle-punched nonwovens, spunbond nonwovens, spunlace nonwovens, embossed films, wet nonwovens, etc. In a narrower sense, it refers to those used as interwoven nonwovens, etc., by bonding randomly stacked webs and the contact points between fibers together with resin. Nonwoven fabrics are also called bonded fabrics. These nonwoven fabrics can be produced by various methods, including needle punching, chemical bonding, thermal bonding, meltblowing, spunlace, stitch bonding, and spunbonding.

[0005] On the other hand, spunbond nonwoven fabrics made from polyolefin resins excel in terms of touch, flexibility, breathability, and heat insulation, and are therefore widely used in filters, packaging materials, bedding, clothing, medical supplies, hygiene products, automotive interior materials, and building materials. In particular, polypropylene fibers, due to their inherent low melting point and excellent chemical resistance, are processed into thermally bonded nonwoven fabrics through calendering or air bonding methods, and these are primarily used as surface materials for hygiene products such as diapers and sanitary napkins.

[0006] Meanwhile, unlike existing homopolymer polypropylene resins prepared using Ziegler-Natta catalysts, homopolymer polypropylene resins prepared using metallocene catalysts have a narrow molecular weight distribution, thus enabling the production of thin, uniform fibers. This offers the advantage of producing low-basic-weight nonwoven fabrics with excellent strength. However, due to the low xylene solubility or narrow molecular weight distribution, and the low content of low molecular weight molecules, metallocene homopolymer polypropylene resins have the disadvantage of providing a rough tactile feel on the surface of the nonwoven fabric.

[0007] Four techniques are used to provide a soft touch to general-purpose Ziegler-Natta homopolymer polypropylene: two-component processing techniques using homopolymer polypropylene and polyethylene, such as blends using homopolymer polypropylene and propylene-containing polyolefins (C3-POE), blends using homopolymer polypropylene and low-modulus polypropylene (LPP), and blends using homopolymer polypropylene and polypropylene terpolymers (tPP). However, all of these methods use different types of resins besides polypropylene compared to existing methods, which improves the softness (or suppleness). However, these methods have limitations in improving suppleness and inevitably suffer from reduced strength and productivity of the nonwoven fabric due to the presence of single yarns during processing.

[0008] Furthermore, to address the issues with polypropylene prepared using Ziegler-Natta catalysts, propylene-1-butene random copolymers prepared with metallocene catalysts can be used to increase flexibility while maintaining excellent strength properties in the manufacture of nonwoven fabrics. However, compared to products produced using existing Ziegler-Natta type homopolymers and polyethylene, or polyethylene produced through blending techniques using homopolymers and propylene-containing polyolefins (C3-POE), or products produced using two-component processing techniques, the improvement in flexibility is unsatisfactory, and the softness is relatively poor, thus resulting in a rougher tactile feel.

[0009] Therefore, there is a need to develop a polypropylene resin composition that uses a metallocene catalyst, which maintains high strength and excellent processability compared to existing products, and is suitable for soft nonwoven fabrics. Summary of the Invention

[0010] Technical issues

[0011] In this invention, a polypropylene resin composition prepared in the presence of a metallocene compound having a specific structure using a continuous reactor and a method thereof are provided. Compared with existing products, the polypropylene resin composition maintains high strength and excellent processability, and is suitable for soft nonwoven fabrics.

[0012] Technical solution

[0013] According to one embodiment of the present invention, a polypropylene resin composition is provided, wherein the molecular weight distribution (Mw / Mn) is 2.6 to 3.2, the xylene soluble content (XS) is 4.5% to 8.0% by weight, the ethylene content is 1.0% to 5.0% by weight, and the tensile strength measured according to ASTM D 638 is 275 kg / cm². 2 Up to 285kg / cm 2 The flexural modulus, measured according to ASTM D 790 method, is 11500 kg / cm². 2Up to 12500 kg / cm 2 Melt index (MI) 2.16 According to ASTM D 1238, the crystallization temperature (Tc) is 10 g / 10 min to 100 g / 10 min at 230°C under a load of 2.16 kg, and the crystallization temperature (Tc) is 95°C to 115°C.

[0014] Meanwhile, a method for preparing the above-mentioned polypropylene resin composition is also provided. The method for preparing the polypropylene resin composition is used in the presence of a catalyst composition comprising one or more metallocene compounds represented by Formula 1, using a series of reactors comprising at least one first reactor and at least one second reactor, the method comprising the steps of: preparing a propylene homopolymer in the first reactor; and preparing an ethylene-propylene copolymer in the second reactor.

[0015] [Formula 1]

[0016]

[0017] In Equation 1,

[0018] A is carbon, silicon, or germanium.

[0019] M is a group 4 transition metal.

[0020] X1 and X2 are each an independent halogen.

[0021] R1 and R5 are each independently used to replace C. 1-20 C of alkyl 6-20 Aryl,

[0022] R2 to R4 and R6 to R8 are each independently hydrogen, halogen, or C. 1-20 Alkyl, C 2-20 alkenyl, C 1-20 Alkyl silyl, C 1-20 Silylalkyl, C 1-20 Alkoxysilyl, C 1-20 Ether, C 1-20 Silyl ether, C 1-20 Alkoxy, C 6-20 Aryl, C 7-20 alkylaryl or C 7-20 Arylalkyl, and

[0023] R9 and R 10 Each independently is C 1-20 alkyl.

[0024] In Equation 1, A can be silicon, and R1 and R5 can each be C substituted. 3-6 Branched alkyl phenyl groups. Additionally, R9 and R... 10Each can be C 2-4 Straight-chain alkyl groups, wherein R9 and R 10 They can be the same as each other, but are preferably ethyl.

[0025] Furthermore, metallocene compounds can be specifically represented, for example, by the following formula 1-1:

[0026] [Equation 1-1]

[0027]

[0028] The structural formula in Equation 1-1 is merely an example used to explain the present invention, and the present invention is not limited thereto.

[0029] For example, the first reactor can be a reflux reactor, and the second reactor can be a gas-phase reactor.

[0030] In addition, in the second reactor, propylene and ethylene can be supplied in a weight ratio of 7:3 to 6:4.

[0031] Meanwhile, a polypropylene nonwoven fabric is provided, which is composed of fibers made from the aforementioned polypropylene resin composition.

[0032] For example, the average diameter of the fiber can be from 5.7 micrometers to 8.5 micrometers.

[0033] For example, when the basis weight of polypropylene nonwoven fabric is 72 g / m² 2 Up to 76g / m 2 At that time, the softness tester value (Handle-O-meter) of the nonwoven fabric measured according to the NWSP 090.3.R0 standard can be below 24g.

[0034] The terminology used herein is for the purpose of explaining exemplary embodiments only and is not intended to limit the invention.

[0035] Singular expressions can include plural expressions unless the context is different.

[0036] The terms “comprising,” “equipped,” or “having” in this specification are used only to explain the functioning features, numbers, steps, components, or combinations thereof, and do not exclude the presence or possibility of one or more different features, numbers, steps, components, or combinations thereof added beforehand.

[0037] Furthermore, in this specification, when a layer or element is referred to as being formed “on” or “above” a layer or element, it means that each layer or element is formed directly on the layer or element, or that other layers or elements may be formed separately between layers, bodies, or substrates.

[0038] This invention can be modified in various ways and has various forms, and specific embodiments will be described in detail below. However, it should be understood that this specification is not intended to limit the invention to the specific forms disclosed; rather, the invention is intended to cover all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0039] The present invention will now be described in detail.

[0040] Polypropylene resin composition

[0041] The polypropylene resin composition according to one embodiment of the present invention is characterized by satisfying all of the following conditions: a molecular weight distribution (Mw / Mn) of 2.6 to 3.2, a xylene soluble content (XS) of 4.5% to 8.0% by weight, an ethylene content of 1.0% to 5.0% by weight, and a tensile strength of 275 kg / cm² as measured according to ASTM D 638. 2 Up to 285kg / cm 2 The flexural modulus, measured according to ASTM D 790 method, is 11500 kg / cm². 2 Up to 12500 kg / cm 2 The flexural modulus, measured according to ASTM D 790 method, is 11500 kg / cm². 2 Up to 12500 kg / cm 2 Melt index (MI) 2.16 According to ASTM D 1238, the crystallization temperature (Tc) is 10 g / 10 min to 100 g / 10 min at 230°C under a load of 2.16 kg, and the crystallization temperature (Tc) is 95°C to 115°C.

[0042] Propylene copolymers (polymers) prepared by Ziegler-Natta catalysts are characterized by a wide molecular weight distribution and high xylene solubility due to the use of multi-active-site catalysts in which multiple active sites are mixed. The problem is that the composition of the comonomers is not uniform, which limits the ability to ensure the desired physical properties.

[0043] Furthermore, when polypropylene is prepared using existing metallocene catalysts, the resulting nonwoven fabrics exhibit excellent elongation stability and strength due to their low melt temperature (Tm) and narrow molecular weight distribution, but suffer from reduced softness. Therefore, while preparing diblock or triblock copolymers with ethylene or 1-butene can improve the flexibility of the nonwoven fabrics, the degree of improvement is not satisfactory. Moreover, compared to products produced using existing Ziegler-Natta type homopolymer polypropylene and polyethylene bicomponent processing techniques, or products produced using blends of homopolymer polypropylene and propylene-containing polyolefins (C3-POE, such as propylene-ethylene copolymer elastomers), the softness properties are relatively poor, resulting in a rougher feel.

[0044] Therefore, the inventors conducted extensive research on polypropylene resin compositions that, compared with existing products, maintain high strength and excellent processability, and are suitable for soft nonwoven fabrics. Thus, they discovered that when the polypropylene resin compositions are prepared using the metallocene catalyst described below instead of the Ziegler-Natta catalyst and a series of reactors (including a first reactor for polymerizing propylene homopolymer and a second reactor for preparing ethylene-propylene copolymer), the polypropylene resin compositions can meet the above conditions, thereby completing the present invention.

[0045] According to one embodiment of the present invention, a polypropylene resin composition is provided that maintains high strength and excellent processability compared to existing products, and is suitable for the production of flexible nonwoven fabrics.

[0046] More specifically, the molecular weight distribution (Mw / Mn, MWD) of the polypropylene resin composition can be from about 2.6 to about 3.2. As described above, due to the narrow molecular weight distribution, the polypropylene resin composition exhibits increased elongation stability and stiffness, thus demonstrating excellent mechanical properties when producing fiber products for multifilament or nonwoven fabrics. More specifically, the molecular weight distribution (Mw / Mn, MWD) of the polypropylene resin composition can be from about 2.6 to about 3.0, from about 2.6 to about 2.9, or from about 2.6 to about 2.8.

[0047] In this invention, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polypropylene resin composition are measured by gel permeation chromatography (GPC), and the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) is calculated as the molecular weight distribution, thereby determining the molecular weight distribution.

[0048] Specifically, a Waters PL-GPC220 instrument can be used as a gel permeation chromatography (GPC) instrument, and a Polymer Laboratories PLgel MIX-B column with a length of 300 mm can be used. The measurement temperature is 160 °C, 1,2,4-trichlorobenzene can be used as the solvent, and a flow rate of 1 mL / min can be applied. Polypropylene samples are pretreated using the GPC analyzer (PL-GP220) by dissolving them in 1,2,4-trichlorobenzene containing 0.0125% BHT at 160 °C for 10 hours, and prepared at a concentration of 10 mg / 10 mL. Then, 200 μL of the sample can be injected for measurement. A calibration curve obtained using polystyrene standards can be used to determine the values ​​of Mw and Mn. Nine polystyrene standard samples can be used, with weight-average molecular weights of 2000 g / mol, 10000 g / mol, 30000 g / mol, 70000 g / mol, 200000 g / mol, 700000 g / mol, 2000000 g / mol, 4000000 g / mol, and 10000000 g / mol.

[0049] In addition, the xylene-soluble (XS) content of the polypropylene resin composition can be from 4.5% to 8.0% by weight.

[0050] As described above, the characteristic is that the xylene-soluble content (XS) can be effectively controlled and optimized to about 4.5% by weight to about 8.0% by weight, and has a narrow molecular weight distribution of about 2.6 to about 3.2. Specifically, in the case of products comprising compositions of homopolymer polypropylene and ethylene-propylene copolymer, the xylene-soluble content is a value indicating the content of the atactic component and the ethylene-propylene copolymer (i.e., the amorphous polymer) in the whole polymer. By optimizing the xylene-soluble content, polypropylene resin compositions capable of expressing appropriate levels of melting point and mechanical properties can be obtained.

[0051] As described, when the xylene-soluble (XS) content is controlled within an optimal range, processability and elongation properties are improved when producing multifilament or nonwoven products, ensuring excellent web formation or high strength, and exhibiting excellent softness. More specifically, the xylene-soluble (XS) content of the polypropylene resin composition can be more than about 4.5% by weight and less than about 7.8% by weight, or less than about 7.5% by weight, or less than about 7.3% by weight, or less than about 7.0% by weight.

[0052] As used herein, xylene-soluble content refers to the content (wt%) of soluble polymer in crystalline cooled xylene obtained by dissolving a polypropylene resin composition in xylene and allowing the insoluble portion to crystallize from a cooled solution. Xylene-soluble content comprises low stereoregularity, i.e., amorphous polymer chains. Therefore, a low content of xylene-soluble content indicates high stereoregularity, i.e., highly crystalline polymers. The polypropylene resin composition according to one embodiment of the invention has a low content of crystalline polymers, thereby exhibiting excellent softness in the production of nonwoven fabrics. Considering the superior effect of controlling the xylene-soluble content, the xylene-soluble content of the polypropylene resin composition can be maintained within the range described above.

[0053] Furthermore, in this invention, the xylene-soluble component is obtained through the following process: xylene is added to a polypropylene resin composition sample, the composition is completely dissolved by heating at 130°C for more than 1 hour, the sample is cooled at 20°C for more than 1 hour, and the solid and liquid phases are separated by filtration. The xylene component is removed by heating the liquid phase to 130°C, and the weight of the remaining component can be measured.

[0054] More specifically, based on the total weight of all resin compositions, the polypropylene resin composition of the present invention may contain an amount of ethylene in the form of about 1.0 wt% to about 5.0 wt%, or about 1.2 wt% to about 4.8 wt%, or about 1.5 wt% to about 4.5 wt%, or about 1.8 wt% to about 4.0 wt%, or about 1.9 wt% to about 3.5 wt%, or about 2.0 wt% to about 3.2 wt%, or about 2.1 wt% to about 3.0 wt%, or about 2.2 wt% to about 2.7 wt%.

[0055] Since the polypropylene resin composition contains ethylene by controlling the ethylene content in the final polymer, which, within the aforementioned range, is processed through the first and second reactors described below, the heterogeneous comonomers enter between the main chains of the ethylene-propylene copolymer. Therefore, the resulting ethylene-propylene copolymer, due to its high dispersibility within the propylene homopolymer and the absence of significant phase separation, allows for control over the softness of the final resin composition. Furthermore, given that a narrow molecular weight distribution is observed even in polymerizations with high conversion rates using a metallocene catalyst with the specific structure described below, and that excellent elongation stability (processability), softness, and improved strength are also exhibited, it is preferable that the polypropylene resin composition contains ethylene within the aforementioned range.

[0056] Meanwhile, the ethylene content in the polypropylene resin composition of the present invention can be measured by infrared absorption spectroscopy (FT-IR) according to American Society for Testing and Materials (ASTM) D 5576.

[0057] For example, the ethylene content can be calculated by fixing a film or film-type sample of a polypropylene resin composition in a magnetic holder of an FT-IR device, and then measuring the thickness of the sample in the range of 4800-3500 cm⁻¹. -1 The peak height indicates the ethylene component in the IR absorption spectrum at 750-710 cm⁻¹. -1 The peak area. In other words, the ethylene content is calculated by substituting the measured value into a calibration formula, which is obtained by plotting the peak area of ​​each standard sample according to ASTM D 5576, divided by 4800–3500 cm². -1 The value is obtained from the peak height. The method for measuring the ethylene content in a polypropylene resin composition is described in more detail in Test Example 1 below.

[0058] Furthermore, the polypropylene resin composition is characterized by maintaining tensile strength and flexural modulus within the optimal range while simultaneously optimizing molecular weight distribution, xylene soluble content, and ethylene content, as described above.

[0059] Specifically, the polypropylene resin composition has a strength of 275 kg / cm² as measured according to ASTM D 638. 2 Up to 285kg / cm 2 The tensile strength, and 11500 kg / cm² as measured according to ASTM D 790 method. 2 Up to 12500 kg / cm 2 Flexural modulus.

[0060] Preferably, the polypropylene resin composition may have a strength of 276 kg / cm² as measured according to ASTM D 638. 2 Up to 284 kg / cm 2 Or 278kg / cm 2 Up to 283 kg / cm 2 The tensile strength, and 11600 kg / cm² as measured according to ASTM D 790 method. 2 Up to 12400 kg / cm 2 Or 11800kg / cm 2 Up to 12300 kg / cm 2 Flexural modulus.

[0061] In addition, the polypropylene resin composition may have a strength of 375 kg / cm² as measured according to ASTM D 790 method. 2 Up to 385kg / cm 2 or 376kg / cm 2 Up to 384 kg / cm 2 or 378kg / cm 2Up to 383 kg / cm 2 Flexural strength.

[0062] As described, by simultaneously optimizing molecular weight distribution, xylene solubles (XS), ethylene content, tensile strength, and flexural modulus, the polypropylene resin composition of one embodiment of the present invention can exhibit excellent processability and softness as well as high stiffness.

[0063] Furthermore, the melt index (MI) of the polypropylene resin composition, as measured according to ASTM D 1238 at 230°C under a load of 2.16 kg, is... 2.16 The melt index ranges from approximately 10 g / 10 min to approximately 100 g / 10 min. As described, the melt index range can be optimized to obtain polypropylene resin compositions suitable for multifilament or nonwoven fiber products. More specifically, the melt index (MI) of the polypropylene resin composition... 2.16 The amount can be approximately 12g / 10min or more, or approximately 15g / 10min or more, or approximately 18g / 10min or more, or approximately 20g / 10min or more, or approximately 23g / 10min or more, or approximately 25g / 10min or more, and approximately 85g / 10min or less, or approximately 60g / 10min or less, or approximately 45g / 10min or less, or approximately 40g / 10min or less, or approximately 35g / 10min or less, or approximately 30g / 10min or less.

[0064] In addition, the crystallization temperature (Tc) of the polypropylene resin composition can be from 95°C to 115°C.

[0065] The polypropylene resin composition of the present invention is characterized in that, by effectively controlling the xylene-soluble content (XS), ethylene content, tensile strength, flexural modulus, crystallization temperature (Tc), and the aforementioned molecular weight distribution, its crystallization temperature (Tc) can be optimized to about 95°C to about 115°C. Specifically, the xylene-soluble content is a value indicating the content of the atactic component in the entire polymer. By optimizing the xylene-soluble content, a polypropylene resin composition exhibiting appropriate levels of melting point and mechanical properties can be obtained.

[0066] Specifically, the crystallization temperature (Tc) of the polypropylene resin composition can be from about 100°C to about 115°C, or from about 105°C to about 114°C, or from about 107°C to about 113°C, or from about 108°C to about 112°C.

[0067] In addition, the melting temperature (Tm) of the polypropylene resin composition can be from about 150°C to about 158°C, or from about 150°C to about 155°C, or from about 151°C to about 153°C.

[0068] In this invention, a differential scanning calorimeter (DSC, device name: DSC 2920, manufacturer: TAinstrument) can be used to measure the crystallization temperature (Tc) and melting temperature (Tm). Specifically, the polypropylene resin composition is heated to 200°C and held at that temperature for 5 minutes (1 st RUN (heat history elimination). Then, the temperature is cooled to -30°C and then heated again. The temperature at the top of the DSC (differential scanning calorimeter manufactured by TA Instruments) curve is called the melting point (Tm). Then, the temperature is lowered, and the temperature at the top of the DSC (differential scanning calorimeter manufactured by TA Instruments) curve is called the crystallization temperature (Tc). In this paper, the temperature is increased and decreased at a rate of 10°C / min, and the melting temperature (Tm) and crystallization temperature (Tc) are determined by the second heating and cooling stage (2 nd The results of the RUN measurement are expressed.

[0069] As described, unlike existing polypropylene using Ziegler-Natta catalysts or metallocene catalysts, the propylene resin compositions of the present invention can produce thin and uniform fibers during copolymerization while ensuring excellent process stability. They not only provide a softer touch than existing products but also possess high strength for excellent stiffness and are tear-resistant through optimization of molecular weight distribution, xylene solubility, ethylene content, melt index, crystallization temperature, tensile strength, and flexural modulus. Therefore, the polypropylene resin compositions are particularly suitable for producing polypropylene nonwoven fabrics requiring high stiffness and excellent softness.

[0070] Specifically, the polypropylene resin composition comprises a propylene homopolymer and an ethylene-propylene copolymer, wherein the ethylene-propylene copolymer is dispersed in the propylene homopolymer. In particular, the polypropylene resin composition of the present invention may comprise an ethylene-propylene copolymer dispersed in the propylene homopolymer, exhibiting high dispersibility without significant phase separation. This copolymer is produced, as described below, by polymerization processes in a first reactor and a second reactor in the presence of a catalyst composition comprising one or more metallocene compounds represented by Formula 1. Therefore, the final resin composition can exhibit excellent elongation stability (processability) and softness, as well as improved strength.

[0071] The resin composition of the present invention may further include one or more additives, such as antioxidants, neutralizers, dispersants, weathering agents, UV stabilizers, slip agents, anti-blocking agents, and antistatic agents, provided that these additives do not impair the properties of the resin composition. The content of these additives may be from 500 ppm to 3000 ppm based on the total weight of the entire resin composition. Specifically, these additives are added to a polypropylene resin composition obtained after completing all processes in the first and second reactors described below, and additives are not desired during the polymerization process as they may affect catalyst activity during production. Meanwhile, the polypropylene resin composition of the present invention does not include nucleating agents such as dibenzyl sorbitol, di(p-methylbenzyl)sorbitol, aluminum salts of alkylbenzoic acids, and organophosphorus metal salts. When such nucleating agents are added to the polypropylene resin composition of the present invention, the crystallinity becomes excessively high, thus reducing the fiber spinning ability, which may reduce the effect of improving elongation stability and softness.

[0072] Method for preparing polypropylene resin compositions

[0073] Meanwhile, according to another embodiment of the present invention, a method for preparing the above-described polypropylene resin composition having the physical properties described above is provided.

[0074] A method for preparing a polypropylene resin composition is used in the presence of a catalyst composition comprising one or more metallocene compounds represented by Formula 1, using a series of reactors comprising at least one first reactor and at least one second reactor, the method comprising the steps of: preparing a propylene homopolymer in the first reactor; and preparing an ethylene-propylene copolymer in the second reactor.

[0075] [Formula 1]

[0076]

[0077] In Equation 1,

[0078] A is carbon, silicon, or germanium.

[0079] M is a group 4 transition metal.

[0080] X1 and X2 are each an independent halogen.

[0081] R1 and R5 are each independently used to replace C. 1-20 C of alkyl 6-20 Aryl,

[0082] R2 to R4 and R6 to R8 are each independently hydrogen, halogen, or C. 1-20 Alkyl, C 2-20 alkenyl, C1-20 Alkyl silyl, C 1-20 Silylalkyl, C 1-20 Alkoxysilyl, C 1-20 Ether, C 1-20 Silyl ether, C 1-20 Alkoxy, C 6-20 Aryl, C 7-20 alkylaryl or C 7-20 Arylalkyl, and

[0083] R9 and R 10 Each independently is C 1-20 alkyl.

[0084] Meanwhile, unless otherwise stated herein, the following terms may be defined as follows.

[0085] Halogens can be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

[0086] Alkyl groups having 1 to 20 carbon atoms (i.e., C12) 1-20 Alkyl groups can be straight-chain, branched, or cyclic. Specifically, alkyl groups having 1 to 20 carbon atoms can be straight-chain alkyl groups having 1 to 20 carbon atoms; straight-chain alkyl groups having 1 to 15 carbon atoms; straight-chain alkyl groups having 1 to 5 carbon atoms; branched or cyclic alkyl groups having 3 to 20 carbon atoms; branched or cyclic alkyl groups having 3 to 15 carbon atoms; or branched or cyclic alkyl groups having 3 to 10 carbon atoms. For example, (C) alkyl groups having 1 to 20 carbon atoms... 1-20 Alkyl groups can be methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, etc., but are not limited to these.

[0087] Alkenyl groups having 2 to 20 carbon atoms (i.e., C40) 2-20 Alkenyl groups can include straight-chain or branched alkenyl groups, specifically allyl, vinyl, propenyl, butenyl, pentenyl, etc., but are not limited to these.

[0088] Alkoxy groups having 1 to 20 carbon atoms (i.e., C12) 1-20 Alkoxy groups may include, but are not limited to, methoxy, ethoxy, isopropoxy, n-butoxy, tert-butoxy, phenoxy, cyclohexyloxy, etc.

[0089] Alkoxyalkyl groups having 2 to 20 carbon atoms (i.e., C464-2045 ... 2-20Alkoxyalkyl is a functional group in which one or more hydrogen atoms of the aforementioned alkyl group are replaced by alkoxy groups, specifically alkoxyalkyl such as methoxymethyl, methoxyethyl, ethoxymethyl, isopropoxymethyl, isopropoxyethyl, isopropoxypropyl, isopropoxyhexyl, tert-butoxymethyl, tert-butoxyethyl, tert-butoxypropyl, tert-butoxyhexyl, etc.; or aryloxyalkyl such as phenoxyhexyl, etc., but not limited thereto.

[0090] Alkylsilyl groups having 1 to 20 carbon atoms (i.e., C125-20 ... 2-20 Alkyl silyl) or alkoxysilyl (i.e., C10) having 1 to 20 carbon atoms 2-20 Alkoxysilyl is a functional group in which one or three hydrogens of -SiH3 are replaced by one to three alkyl or alkoxy groups, specifically alkylsilyl such as methylsilyl, dimethylsilyl, trimethylsilyl, dimethylethylsilyl, diethylmethylsilyl, dimethylpropylsilyl, etc.; alkoxysilyl such as methoxysilyl, dimethoxysilyl, trimethoxysilyl, dimethoxyethoxysilyl, etc.; alkoxyalkylsilyl such as methoxydimethylsilyl, diethoxymethylsilyl, dimethoxypropylsilyl, etc., but not limited to these.

[0091] Silylalkyl groups having 1 to 20 carbon atoms (i.e., C464-C ... 2-20 Silicylalkyl is a functional group in which one or more hydrogen atoms of the alkyl group described above are replaced by silyl groups, specifically CH2-SiH3, methylsilylmethyl or dimethylethoxysilylpropyl, etc., but not limited thereto.

[0092] In addition, alkylene groups having 1 to 20 carbon atoms (i.e., C464-C ... 1-20 The alkylene group is the same as the alkyl group mentioned above, except that it is a divalent substituent, specifically methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, etc., but not limited to these.

[0093] Aryl groups having 6 to 20 carbon atoms (i.e., C64) 6-20 The aryl group can be a monocyclic, bicyclic, or tricyclic aromatic hydrocarbon. For example, aryl groups can include phenyl, biphenyl, naphthyl, anthracene, phenanthryl, fluorene, etc., but are not limited to these.

[0094] Alkyl aryl groups having 7 to 20 carbon atoms (i.e., C464-C ... 7-20 Alkyl aryl can refer to a substituent in which one or more hydrogen atoms of the aromatic ring are replaced by the aforementioned alkyl group. For example, alkyl aryl can include, but is not limited to, methylphenyl, ethylphenyl, methylbiphenyl, methylnaphthyl, etc.

[0095] In addition, aralkyl groups having 7 to 20 carbon atoms (i.e., C464) 7-20 Aryl group can refer to a substituent in which one or more hydrogen atoms of the alkyl group are replaced by the aryl group. For example, aryl group can include, but is not limited to, phenylmethyl, phenethyl, biphenylmethyl, naphthylmethyl, etc.

[0096] In addition, aryloxy groups with 6 to 20 carbon atoms (i.e., C464) 6-20 Aryloxy groups can include phenoxy, biphenyloxy, naphthoxy, etc., but are not limited to these.

[0097] In addition, arylene groups with 6 to 20 carbon atoms (i.e., C464-C ... 6-20 (Arylidene) is the same as the aryl group mentioned above, except that it is a divalent substituent, specifically phenylene, biphenylene, naphthylene, anthracene, phenanthrene, fluorene, etc., but not limited to these.

[0098] In addition, the Group 4 transition metals can be titanium (Ti), zirconium (Zr), hafnium (Hf), or... Specifically, it is titanium (Ti), zirconium (Zr), or hafnium (Hf), and more specifically zirconium (Zr) or hafnium (Hf), but not limited thereto.

[0099] In addition, Group 13 elements can be boron (B), aluminum (Al), gallium (Ga), indium (In) or thallium (Tl), specifically boron (B) or aluminum (Al), but are not limited to these.

[0100] Within the range of effects that are the same as or similar to the desired effect, the above substituents may optionally be replaced by one or more substituents selected from the group consisting of: hydroxyl; halogen; alkyl or alkenyl, aryl, alkoxy; alkyl or alkenyl, aryl, alkoxy containing one or more heteroatoms from groups 14 to 16; silyl; alkylsilyl or alkoxysilyl; phosphine; phosphide group; sulfonate group; and sulfone group.

[0101] The catalyst composition for preparing a polypropylene resin composition according to one embodiment of the invention is characterized by comprising a metallocene compound represented by Formula 1. In particular, when a metallocene catalyst having specific substituents in the bridging group connecting two ligands containing an indenyl group is used, polypropylene with optimized melting point and molecular weight distribution can be prepared to meet desired physical properties.

[0102] Furthermore, the compounds of Formula 1 include a divalent functional group A that is disubstituted with the same alkyl group having two or more carbon atoms, which acts as a bridging group connecting two ligands containing an indenyl group. Therefore, with larger atomic sizes, the available angles increase, and the entry of propylene or ethylene monomers becomes easier, resulting in superior catalytic activity.

[0103] Furthermore, since the two indenyl groups in the compound of formula 1 are substituted at the 2-position with methyl groups, and at the 4-position (i.e., R... 1 R and R) respectively contain alkyl-substituted aryl groups, so they can exhibit superior catalytic activity through the inductive effect of providing sufficient electrons.

[0104] More specifically, in Equation 1, R1 and R5 are each independently represented by C. 1-10 Alkyl-substituted C 6-12 Aryl, more specifically, is C 3-6 Branched alkyl-substituted phenyl groups, such as tert-butylphenyl. Furthermore, the alkyl substitution position relative to the phenyl group can be the 4-position corresponding to the para-positions R1 and R5 bonded to the indene group.

[0105] Furthermore, in Equation 1, R2 to R7 can each be hydrogen independently, and X1 and X2 can each be chlorine (Cl) independently.

[0106] Furthermore, in Formula 1, A can be silicon (Si). Additionally, regarding improving solubility, R9 and R, as substituents for A, [are suitable]. 10 They can be the same as each other, and can be C. 2-10 Alkyl, specifically C 2-4 Straight-chain alkyl, more specifically ethyl. As mentioned, since the substituents of bridging group A are the same alkyl group, the problem of poor solubility leading to poor loading reactivity during the preparation of supported catalysts when the substituent of the bridging group element is a methyl group having one carbon atom can be solved.

[0107] Furthermore, in Formula 1, M can be zirconium (Zr) or hafnium (Hf), with zirconium (Zr) being preferred. In particular, when the compound of Formula 1 includes zirconium (Zr) as the central metal, it has more electron-accepting orbitals compared to those containing another Group 4 element (e.g., hafnium (Hf)). Therefore, it can bind to the monomer with higher affinity, thereby significantly enhancing catalytic activity.

[0108] Representative examples of metallocene compounds represented by Equation 1 are as follows:

[0109] [Equation 1-1]

[0110]

[0111] The metallocene compounds represented by Formula 1 can be synthesized by applying known methods for synthesizing organic compounds, and will be described in more detail in the examples described below.

[0112] Meanwhile, in the method for preparing the metallocene compound or catalyst composition of the present invention, equivalent (eq) means molar equivalent (eq / mol).

[0113] In the catalyst composition used to prepare the polypropylene resin composition according to one embodiment of the present invention, the metallocene compound of Formula 1 may be used as a supported catalyst (simultaneously supported on a support) or as an unsupported catalyst. In particular, the metallocene compound is more preferably used as a supported catalyst in order to ensure the stability of the polymerization process using the catalyst composition and the uniform control of physical properties.

[0114] As a carrier, a carrier containing highly reactive hydroxyl or siloxane groups on its surface can be used. Preferably, a carrier containing both highly reactive hydroxyl and siloxane groups can be used, which is dried at high temperature to remove moisture from its surface.

[0115] For example, silicon dioxide, silicon dioxide-alumina, silicon dioxide-magnesium oxide, etc., which are dried at high temperatures can be used, and they can typically include oxides, carbonates, sulfates and nitrates, such as Na2O, K2CO3, BaSO4, Mg(NO3)2, etc.

[0116] The drying temperature of the support is preferably from about 200°C to about 800°C, more preferably from about 300°C to about 600°C, and most preferably from about 300°C to about 400°C. When the drying temperature of the support is below about 200°C, excessive moisture remains, and the moisture on the surface may react with the co-catalyst. When the drying temperature is above about 800°C, the pores on the support surface may combine with each other, reducing the surface area, and many hydroxyl groups may be lost from the surface, leaving only siloxane groups. Therefore, the reaction sites with the co-catalyst may be reduced, which is not preferred.

[0117] For example, the amount of hydroxyl groups on the support surface is preferably from about 0.1 mmol / g to about 10 mmol / g, more preferably from about 0.5 mmol / g to about 5 mmol / g. The amount of hydroxyl groups on the support surface can be controlled by the method of preparation and preparation conditions or drying conditions, such as temperature, time, vacuum or spray drying. When the amount of hydroxyl groups is less than about 0.1 mmol / g, the reaction sites with the co-catalyst may be reduced. When the amount of hydroxyl groups is greater than about 10 mmol / g, it may be due to moisture in addition to the hydroxyl groups present on the surface of the support particles, which is undesirable.

[0118] When a metallocene compound of Formula 1 is supported on a support, the weight ratio of all transition metals contained in the metallocene compound represented by Formula 1 to the support can be from about 1:1 to about 1:1000. When the support and the metallocene compound are contained in the above weight ratio, suitable activity of the supported catalyst can be exhibited, which may be advantageous in terms of maintaining catalytic activity and economic feasibility. More specifically, the weight ratio of the compound of Formula 1 to the support can be from 1:10 to 1:30, and more specifically from 1:15 to 1:20.

[0119] In addition to the metallocene compound and support of Formula 1, the catalyst composition may include a co-catalyst for improved activity and process stability.

[0120] Specifically, the co-catalyst may include one or more compounds represented by Formula 2:

[0121] [Equation 2]

[0122] -[Al(R 21 )-O] m -

[0123] In Equation 2,

[0124] R 21 They may be the same as or different from each other, and each is independently a halogen, C 1-20 Alkyl or C 1-20 Halogenated alkyl groups; and

[0125] m is an integer greater than or equal to 2.

[0126] Examples of compounds represented by Formula 2 may include aluminum oxane-type compounds, such as methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, etc., and any one or a mixture of two or more of them may be used.

[0127] In addition, the co-catalyst may include one or more compounds represented by Formula 3:

[0128] [Formula 3]

[0129] J(R 31 )3

[0130] In Equation 3,

[0131] R 31 They may be the same as or different from each other, and each is independently a halogen, C 1-20 Alkyl or C 1-20 Halogenated alkyl groups; and

[0132] J represents aluminum or boron.

[0133] Examples of compounds represented by Formula 3 may include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, trisec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylmethoxide aluminum, dimethylethoxide aluminum, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, etc., and more specifically selected from trimethylaluminum, triethylaluminum and triisobutylaluminum.

[0134] In addition, the co-catalyst may include one or more of the compounds represented by Formula 4:

[0135] [Formula 4]

[0136] [EH] + [ZQ4] -

[0137] In Equation 4,

[0138] E is a neutral or cationic Lewis base;

[0139] H is a hydrogen atom;

[0140] Z is a group 13 element;

[0141] Q are either the same as or different from each other, and each is C independently. 6-20 Aryl or C 1-20 Alkyl, wherein C 6-20 Aryl or C 1-20 The alkyl group is either unsubstituted or substituted with one or more substituents, said substituents being selected from halogens, C... 1-20 Alkyl, C 1-20 Alkoxy and C 6-20 A group composed of aryl groups.

[0142] Specifically, in Equation 4, [EH] + It is Brønsted acid.

[0143] Meanwhile, in Equation 4, E can be an amine comprising one or more nitrogen atoms, wherein the amine can be C 6-20 Aryl or C 1-20 Alkyl substitution. For example, E can be an amine comprising one or two nitrogen atoms, wherein the amine can be substituted with more than two carbon atoms. 6-20 Aryl or C 1-20 Alkyl substitution, or the amine can be replaced by two or three Cs. 6-18 Aryl or C 6-12 Aryl or C 1-12 Alkyl or C 1-6 Alkyl substitution.

[0144] Specifically, in Equation 4, Z can be aluminum or boron.

[0145] Specifically, in Equation 4, Q can be either substituted or unsubstituted C. 6-18 Aryl or C 6-12 Aryl, or C 1-12 Alkyl or C 1-6 alkyl.

[0146] Examples of compounds represented by Formula 4 may include triethylammonium tetraphenylborane, tributylammonium tetraphenylborane, trimethylammonium tetraphenylborane, tripropylammonium tetraphenylborane, trimethylammonium tetra(p-tolyl)borane, trimethylammonium tetra(o,p-dimethylphenyl)borane, tributylammonium tetra(p-trifluoromethylphenyl)borane, trimethylammonium tetra(p-trifluoromethylphenyl)borane, tributylammonium tetra(pentafluorophenyl)borane, N,N-diethylphenylammonium tetraphenylborane, N,N-diethylphenylammonium tetra(pentafluorophenyl)borane, diethylammonium tetra(pentafluorophenyl)borane, triphenylphosphonium tetraphenylborane, trimethylphosphonium tetraphenylborane, triethylammonium tetraphenylaluminum, tributylammonium tetraphenylaluminum, trimethylammonium tetraphenylaluminum, tripropylammonium tetraphenylaluminum, trimethylammonium tetra(p-tolyl)aluminum, triethylammonium tetra(p-tolyl)aluminum, triethylammonium tetraphenyl ...phenylaluminum, triethyl Propylammonium tetra(p-tolyl)aluminum, triethylammonium tetra(o,p-dimethylphenyl)aluminum, tributylammonium tetra(p-trifluoromethylphenyl)aluminum, trimethylammonium tetra(p-trifluoromethylphenyl)aluminum, tributylammonium tetra(pentafluorophenyl)aluminum, N,N-diethylphenylammonium tetraphenylaluminum, N,N-diethylphenylammonium tetra(pentafluorophenyl)aluminum, diethylammonium tetra(pentafluorophenyl)aluminum, triphenylphosphonium tetraphenylaluminum, trimethylphosphonium tetraphenylaluminum, tripropylammonium tetra(p-tolyl)boron, triethylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, triphenylcarbium tetra(p-trifluoromethylphenyl)boron, triphenylcarbium tetra(pentafluorophenyl)boron, etc., wherein any one or a mixture of two or more thereof may be used.

[0147] When a cocatalyst is further included, the weight ratio of the metallocene compound of Formula 1 to the cocatalyst can be from about 1:1 to about 1:20. When the cocatalyst and metallocene compound are included in the above weight ratio, suitable activity of a supported catalyst can be exhibited, which may be advantageous in terms of maintaining catalytic activity and economic feasibility. More specifically, the weight ratio of the compound of Formula 1 to the cocatalyst can be from about 1:5 to about 1:20, or from about 1:5 to about 1:15.

[0148] Based on the weight of the support, such as about 1 g of silica, the loading of the co-catalyst can be more than about 3 mmol, or more than about 5 mmol, and less than about 20 mmol, or less than about 15 mmol. When it is contained within the above-mentioned content range, it can exhibit the effect of improving catalytic activity by using the co-catalyst.

[0149] When the catalyst composition comprises both a support and a cocatalyst, the catalyst composition can be prepared by a method comprising the following steps: loading a cocatalyst compound onto the support, and loading a compound represented by Formula 1 onto the support. In this regard, the loading order of the cocatalyst and the metallocene compound of Formula 1 can be varied as needed.

[0150] In this regard, hydrocarbon solvents such as pentane, hexane, and heptane, or aromatic solvents such as benzene and toluene can be used as reaction solvents for preparing catalyst compositions.

[0151] Meanwhile, according to one embodiment of the present invention, a polypropylene resin composition can be prepared by a method for preparing a polypropylene resin composition, the method being carried out in the presence of a catalyst composition comprising at least one first reactor and at least one second reactor, the catalyst composition comprising one or more metallocene compounds represented by Formula 1, the method comprising the steps of: preparing a propylene homopolymer in a first reactor; and preparing an ethylene-propylene copolymer in a second reactor.

[0152] For example, the method for preparing the polypropylene resin composition of the present invention may include the following steps: preparing a propylene homopolymer in a first reactor; and preparing an ethylene-propylene copolymer to be dispersed in the propylene homopolymer in a second reactor.

[0153] Specifically, in this invention, a polypropylene resin composition can be prepared using a series of reactors comprising at least one first reactor and at least one second reactor in the presence of a catalyst composition comprising one or more metallocene compounds represented by Formula 1. The resulting polypropylene resin composition comprises a propylene homopolymer and an ethylene-propylene copolymer, wherein the ethylene-propylene copolymer is dispersed within the propylene homopolymer. In particular, by optimizing the polymerization process in the first reactor and the copolymerization process in the second reactor in the presence of a catalyst composition comprising one or more metallocene compounds represented by Formula 1, the resulting ethylene-propylene copolymer is contained in the propylene homopolymer with high dispersibility and no significant phase separation. Therefore, the final resin composition can exhibit excellent processability and transparency, as well as high elongation properties, thereby maintaining excellent impact strength.

[0154] According to one embodiment of the present invention, a polypropylene resin composition can be prepared by a bulk slurry process and a gas-phase process in the presence of a catalyst composition comprising one or more metallocene compounds represented by Formula 1.

[0155] In this regard, the first reactor can be a reflux reactor, for example, a Spheripol process reactor comprising two reflux reactors. Furthermore, the second reactor can be a gas-phase reactor.

[0156] Furthermore, in this invention, the polypropylene resin composition is characterized by the preparation of ethylene-propylene copolymers in a continuous reactor (i.e., a gas-phase process) using a bulk slurry process. The polypropylene resin composition of this invention can significantly improve overall process efficiency, unlike conventional polymerization, where solution processes are applied to prepare propylene elastomers with high ethylene content, i.e., polymerization is carried out in a reactor in the presence of a solvent due to the low melting temperature (Tm) of the high content of comonomers such as ethylene.

[0157] Furthermore, in the method for preparing a polypropylene resin composition according to the present invention, a continuous reactor is used for a bulk slurry process and a subsequent gas-phase process in the presence of a catalyst composition comprising one or more metallocene compounds represented by Formula 1, to minimize phase separation between the propylene homopolymer obtained in the first reactor and the ethylene-propylene copolymer obtained in the second reactor, thereby significantly improving the transparency and elongation of the final polypropylene resin composition.

[0158] Specifically, the first reactor comprises a reaction system including multiple reflux reactors. Propylene homopolymer can be produced by continuously polymerizing liquid propylene monomer in the presence of a catalyst and hydrogen in the reaction system comprising multiple reflux reactors. For example, the hydrogen content in each of the multiple reflux reactors can range from 0.07 L to 4 L under reactor conditions of 1 atm, or can be fed at a pressure of 1 bar to 40 bar, or can be introduced at a hydrogen molar content ranging from 150 ppm to 8000 ppm relative to the propylene monomer. The amount of hydrogen input is based on the molar content (ppm) of the propylene input. More specifically, the reaction system for the first reactor used to produce propylene homopolymer includes reflux reactors 1-1 and 1-2, wherein hydrogen can be introduced into reflux reactor 1-1 at a concentration of 150 ppm to 8000 ppm, and hydrogen can be introduced into reflux reactor 1-2 at a concentration equal to or higher than that introduced into reflux reactor 1-1 but below 8000 ppm. Preferably, in the first reactor, the amount of hydrogen input can be 160 ppm or more, or 170 ppm or more, or 180 ppm or more, or 190 ppm or more, or 200 ppm or more, or 250 ppm or more, or 300 ppm or more, or 350 ppm or more, or 380 ppm or more, or 400 ppm or more, or 430 ppm or more, and less than 6000 ppm, or less than 4000 ppm, or less than 2000 ppm, or less than 1800 ppm, or less than 1500 ppm, or less than 1200 ppm, or less than 1000 ppm, or less than 800 ppm, or less than 650 ppm.

[0159] Furthermore, the polymerization reaction in the first reactor can reach 1 kgf / cm². 2 Up to 100 kgf / cm 2 The polymerization reaction is carried out at a temperature of 25°C to 500°C for 1 hour to 24 hours under pressure. In this regard, the polymerization temperature in the first reactor is preferably 25°C to 250°C, or 30°C to 200°C, or 35°C to 180°C, or 40°C to 150°C, or 45°C to 120°C, or 50°C to 100°C, or 60°C to 85°C. Furthermore, the polymerization pressure in the first reactor is preferably 1 kgf / cm². 2 Up to 80 kgf / cm 2 or 1 kgf / cm 2 Up to 70 kgf / cm 2 or 1 kgf / cm 2 Up to 60 kgf / cm 2 or 2kgf / cm 2 Up to 55 kgf / cm 2 or 3kgf / cm 2 Up to 50 kgf / cm 2 or 4 kgf / cm 2 Up to 45 kgf / cm 2 or 5 kgf / cm 2 Up to 40 kgf / cm 2 The polymerization reaction time is preferably 1 to 5 hours.

[0160] In this invention, polypropylene resin compositions with excellent elongation and high transparency can be prepared, for example, by preparing a propylene homopolymer in a first reactor and preparing an ethylene-propylene copolymer to be dispersed in the propylene homopolymer using a continuous reactor in the presence of a metallocene compound of formula 1, wherein phase separation is minimized in a second reactor.

[0161] Specifically, the copolymerization process of preparing an ethylene-propylene copolymer is carried out in a second reactor via a gas-phase reaction, wherein the ethylene-propylene copolymer is dispersed in a propylene homopolymer obtained in the first reactor. The propylene homopolymer prepared in the first reactor is transported and introduced, followed by the additional introduction of propylene and ethylene, thereby carrying out this copolymerization process in the second reactor. Here, when the propylene homopolymer prepared in the first reactor is transported to the second reactor (gas-phase reactor), the residual propylene monomer and hydrogen remaining after the first recovery process in the first reactor are transported together with the propylene homopolymer. Preferably, when the propylene homopolymer prepared in the first reactor is transported to the second reactor (gas-phase reactor), the antistatic treatment used when applying a conventional Ziegler-Natta catalyst can be omitted.

[0162] Furthermore, the polymerization reaction in the second reactor can reach 1 kgf / cm².2 Up to 80 kgf / cm 2 The polymerization reaction is carried out at a temperature of 28°C to 500°C for 1 hour to 24 hours under pressure. In this regard, the polymerization temperature in the first reactor is preferably 30°C to 250°C, or 35°C to 200°C, or 40°C to 180°C, or 45°C to 150°C, or 50°C to 120°C, or 55°C to 100°C, or 65°C to 85°C. Furthermore, the copolymerization pressure in the second reactor is preferably 1 kgf / cm². 2 Up to 65 kgf / cm 2 or 1 kgf / cm 2 Up to 55 kgf / cm 2 or 1 kgf / cm 2 Up to 50 kgf / cm 2 or 2kgf / cm 2 Up to 40 kgf / cm 2 or 3kgf / cm 2 Up to 35 kgf / cm 2 or 4 kgf / cm 2 Up to 30 kgf / cm 2 or 5 kgf / cm 2 Up to 25 kgf / cm 2 The polymerization reaction time is preferably 1 to 5 hours.

[0163] The copolymerization in the second reactor can be carried out with or without the addition of hydrogen. However, when unreacted propylene and hydrogen from the first recovery process are fed to the second reactor along with the propylene homopolymer obtained during polymerization in the first reactor, no additional hydrogen is added, or only trace amounts of hydrogen are added to the second reactor for a gas-phase copolymerization process (where only propylene and ethylene are added separately). Here, when trace amounts of hydrogen are added, the hydrogen can be introduced in an amount of about 0.01 times, or about 0.005 times, or about 0.001 times the amount of hydrogen used in the first reactor. For example, the hydrogen can be introduced in an amount within the range of about 80 ppm, or about 50 ppm, or about 30 ppm, or about 15 ppm, or about 10 ppm, or about 5 ppm of hydrogen molar content relative to the propylene monomer.

[0164] In this invention, the above-mentioned propylene homopolymer is prepared by polymerization reaction, and then an ethylene-propylene copolymer to be dispersed in the propylene homopolymer is prepared by gas-phase reaction, thereby preparing a polypropylene resin composition that exhibits high transparency and excellent elongation. At the same time, by simultaneously optimizing the molecular weight distribution, xylene solubles (XS), ethylene content, melt index and crystallization temperature (Tc), it maintains excellent impact resistance during the manufacturing process of injection molded products.

[0165] Specifically, the melt index (MI) of the propylene homopolymer obtained in the first reactor, as measured according to ASTM D 1238 of the American Society for Testing and Materials (ASTM) at 230°C under a load of 2.16 kg, is... 2.16 The amount can be from about 10g / 10min to about 100g / 10min, more specifically from about 15g / 10min to about 35g / 10min, or from about 25.2g / 10min to about 25.6g / 10min.

[0166] Specifically, the melt index (MI) of the propylene homopolymer obtained in the first reactor 2.16 The melt index (MI) of the final prepared polypropylene resin composition is... 2.16 The melt index (MI) of propylene homopolymers is obtained within the same or similar range. 2.16 ) and the melt index (MI) of the final prepared polypropylene resin composition. 2.16 The difference can be within approximately 5 g / 10 min. Specifically, the melt index (MI) of propylene homopolymers... 2.16 Melt index (MI) of ethylene-propylene copolymers 2.16 The difference can be within approximately 0 to approximately 5 g / 10 min, more specifically within approximately 3 g / 10 min, or approximately 2 g / 10 min, or approximately 1.5 g / 10 min.

[0167] As described above, the propylene homopolymer obtained in the first reactor and the ethylene-propylene copolymer obtained in the second reactor may also have the same or similar melt index (MI). 2.16 Viscosity and molecular weight. In this invention, unlike those using existing Ziegler-Natta catalysts, the rapid increase in molecular weight of the ethylene-propylene copolymer can be prevented by using a continuous reactor in the presence of the metallocene compound of Formula 1.

[0168] By using a continuous reactor in the presence of the metallocene compound of Formula 1, the difference in physical properties between propylene homopolymer and ethylene-propylene copolymer can be optimized, and the ethylene-propylene copolymer is dispersed in the propylene homopolymer with minimal phase separation, thereby solving the problem of reduced transparency and elongation caused by phase separation between the propylene homopolymer and the ethylene-propylene copolymer.

[0169] Simultaneously, in the second reactor, propylene and ethylene can be introduced in a weight ratio of 7:3 to 6:4, or the weight ratio of propylene introduction can be 1.4 to 2.6 times the input weight of ethylene. For example, propylene and ethylene can be introduced in a weight ratio of 7:3, 6.5:4, or 6:4. Alternatively, for another example, the weight ratio of propylene introduction can be more than 1.45 times, or more than 1.5 times, or more than 1.52 times, or more than 1.55 times, or more than 1.58 times, or more than 1.6 times, or more than 1.62 times, and less than 2.5 times, or less than 2.48 times, or less than 2.45 times, or less than 2.4 times, or less than 2.38 times, or less than 2.35 times, or less than 2.34 times the input weight of ethylene.

[0170] For example, in the polypropylene resin composition of the present invention, the amount of ethylene-propylene copolymer may be 3% to 9% by weight, or 3.2% to 8.8% by weight, or 3.3% to 8.6% by weight, or 3.5% to 8.4% by weight, or 4% to 8% by weight, based on the weight of the propylene homopolymer.

[0171] Furthermore, in the method for preparing the polypropylene resin composition, the processes for preparing the propylene homopolymer and the ethylene-propylene copolymer can be carried out in the presence of the above-mentioned catalyst composition by applying common equipment and contact techniques.

[0172] The polypropylene resin composition according to one embodiment of the present invention, prepared by the above-described method, can produce thin and uniform fibers. Furthermore, by optimizing the xylene solubility, ethylene content, tensile strength, flexural modulus, and narrow molecular weight distribution, it not only provides a softer touch than existing products but also possesses high strength to achieve excellent stiffness without being easily torn. Therefore, the polypropylene resin composition is particularly suitable for producing polypropylene nonwoven fabrics requiring high stiffness and excellent softness.

[0173] The polypropylene resin composition of this invention can maintain high stiffness and excellent process stability and processability compared with existing polypropylene using Ziegler-Natta catalysts, or can ensure significantly improved softness properties when producing nonwoven fabrics compared with existing homopolymers or copolymers using metallocene catalysts.

[0174] Polypropylene nonwoven fabric

[0175] Meanwhile, according to another embodiment of the present invention, a resin composition for producing nonwoven fabric and a polypropylene nonwoven fabric produced using the same are provided, the resin composition comprising the aforementioned polypropylene resin composition.

[0176] Resin compositions for the production of nonwoven fabrics and nonwoven fabrics produced using them can be prepared according to common methods, the difference being the use of the polypropylene resin composition described above.

[0177] For example, the polypropylene nonwoven fabric of the present invention may be composed of fibers produced from the polypropylene resin composition described above.

[0178] As described, a series of reactors, including a first reactor for preparing polypropylene homopolymer and a second reactor for preparing ethylene-propylene copolymer, can be used for production. Therefore, by optimizing xylene-soluble content, ethylene content, tensile strength, flexural modulus, melt index, and crystallization temperature, as well as having a narrow molecular weight distribution, the advantages of this polypropylene resin composition are that it maintains high strength and excellent processability in the production of polypropylene nonwoven fabrics, and provides superior softness compared to existing products.

[0179] Specifically, to ensure excellent flexibility and high strength, the handle-O-meter value of polypropylene nonwoven fabric, as measured according to NWSP 090.3.R0 standard, can be below 24 g, or from approximately 1.0 g to approximately 24 g. Maintaining the handle-O-meter value within this range ensures excellent flexibility, thereby reducing the roughness of the polypropylene nonwoven fabric and achieving its soft properties. The handle-O-meter value is based on a nonwoven fabric basis weight of 72 g / m³. 2 Up to 76g / m 2 The value measured at that time.

[0180] In particular, the polypropylene nonwoven fabric of the present invention is characterized by meeting the above-mentioned range of softness tester values, thus maintaining high strength and achieving softness compared with existing products.

[0181] Beneficial effects

[0182] According to the present invention, a polypropylene resin composition comprising an ethylene-propylene copolymer can be provided, which is prepared in a continuous reactor in the presence of a metallocene compound having a specific structure, and exhibits high strength as well as excellent processability and softness by simultaneously optimizing xylene solubility, ethylene content, tensile strength, flexural modulus, melt index and crystallization temperature, and having a narrow molecular weight distribution, thus being advantageous in the production of polypropylene nonwoven fabrics. Attached Figure Description

[0183] Figure 1 A scanning electron microscope (SEM) image showing a cross section of the polypropylene resin composition of Example 1-1 is shown.

[0184] Figure 2A scanning electron microscope (SEM) image showing a polypropylene nonwoven fabric produced according to Example 2-1 is shown.

[0185] Figure 3 A scanning electron microscope (SEM) image showing a polypropylene nonwoven fabric produced according to Examples 2-2 is shown.

[0186] Figure 4 Scanning electron microscope (SEM) images of polypropylene nonwoven fabrics produced according to Comparative Examples 2-4 are shown. Detailed Implementation

[0187] In the following description, the effects and functions of the present invention will be described in more detail with reference to specific exemplary embodiments thereof. However, these exemplary embodiments are for illustrative purposes only, and the scope of the present invention is not limited thereto.

[0188] [Example]

[0189] <Preparation of Metallocene Catalysts>

[0190] Preparation Example 1

[0191]

[0192] Step 1: Preparation of (diethylsilanediyl)-bis((2-methyl-4-tert-butylphenylindenyl)silane

[0193] 2-Methyl-4-tert-butylphenylindene (20.0 g) was dissolved in a mixed solvent of toluene and tetrahydrofuran (toluene / THF volume ratio: 10 / 1, 220 mL). Then, a solution of n-butyllithium (2.5 M, hexane solvent, 22.2 g) was slowly added dropwise at 0 °C, followed by stirring at room temperature for 1 day. Next, diethyldichlorosilane (6.2 g) was slowly added dropwise to the mixed solution at -78 °C, and the mixture was stirred for approximately 10 minutes, followed by stirring at room temperature for 1 day. The organic layer was then removed by adding water, and the solvent was distilled under reduced pressure to obtain (diethylsilanediyl)-bis((2-methyl-4-tert-butylphenylindene)silane.

[0194] Step 2) Preparation of [(diethylsilanediyl)-bis((2-methyl-4-tert-butylphenylindenyl)]zirconium dichloride

[0195] The (diethylsilanediyl)-bis((2-methyl-4-tert-butylphenylindenyl))silane prepared in step 1 was dissolved in a 5 / 1 toluene / THF mixed solvent solution (120 mL). Then, a 2.5 M hexane solution (22.2 g) was slowly added dropwise to the solution at -78 °C, and the mixture was stirred at room temperature for 1 day. Zirconium chloride (8.9 g) diluted in toluene (20 mL) was slowly added dropwise to the reaction solution at -78 °C, and the mixture was stirred at room temperature for 1 day. The solvent in the reaction solution was removed under reduced pressure, dichloromethane was added, and the solution was filtered. The filtrate was removed by distillation under reduced pressure. Recrystallization from toluene and hexane yielded high-purity racemic-[(diethylsilanediyl)-bis((2-methyl-4-tert-butylphenylindenyl)]zirconium dichloride (10.1 g, yield: 34%, racemic:meta-molar ratio = 20:1).

[0196] Step 3) Preparation of supported catalyst

[0197] 100 g of silica and 10 wt% methylaluminoxane (670 g) were added to a 3 L reactor and reacted at 90 °C for 24 hours. After precipitation, the supernatant was removed, and the remaining portion was washed twice with toluene. The bridged metallocene compound prepared in step 2, namely racemic-[(diethylsilanediyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)]zirconium dichloride (5.8 g), was diluted with toluene and added to the reactor, and the solution was then reacted at 70 °C for 5 hours. When precipitation was complete, the supernatant was removed, and the remaining reaction product was washed with toluene, further washed with hexane, and dried under vacuum to obtain 150 g of silica-supported metallocene catalyst in solid particulate form.

[0198] <Preparation of Polypropylene Resin Compositions>

[0199] Examples 1-1 and 1-2

[0200] In the first reactor (bulk slurry process, Spheripol process, including two reflux reactors 1-1 and 1-2), a propylene homopolymer was prepared using the silica-supported metallocene catalyst of Preparation Example 1 under the conditions shown in Table 1 below. The propylene homopolymer thus prepared was then fed to the second reactor (gas phase reactor), where an ethylene-propylene copolymer was prepared under the conditions shown in Table 1 to obtain a polypropylene resin composition.

[0201] In this regard, when the propylene homopolymer prepared in the first reactor is conveyed to the second reactor (gas-phase reactor) as described above, the prepared propylene homopolymer is conveyed to the second reactor together with the unreacted propylene monomers after the first recovery process in the first reactor and hydrogen, and no antistatic agent is used for separate treatment. Furthermore, in the presence of hydrogen conveyed together with the propylene homopolymer, and in the presence of the silica-supported metallocene catalyst of Preparation Example 1, an ethylene-propylene copolymer dispersed in the propylene homopolymer is prepared in the second reactor by a gas reaction process without introducing additional hydrogen or by introducing trace amounts of hydrogen (about 10 ppm or less) into the catalyst composition.

[0202] Furthermore, the polypropylene resin compositions of Examples 1 to 4 comprise only the propylene homopolymer and ethylene-propylene copolymer obtained as described, and do not include additives such as nucleating agents. Specifically, in the polypropylene resin compositions, the content of ethylene-propylene copolymer is 4% to 8% by weight based on the weight of the propylene homopolymer (propylene homopolymer: ethylene-propylene copolymer = 4 to 8:1).

[0203] For reference, Table 1 below summarizes the types of supported catalysts used in each embodiment, the polymerization pressure and temperature of each reactor, the concentration of hydrogen or TEAL introduced into each reactor, and the input amounts of ethylene and propylene gas.

[0204] Comparative Example 1-1

[0205] The polypropylene resin composition of Comparative Example 1-1 was prepared in the same manner as in Examples 1-1, except that the polymerization process was carried out using a catalyst of racemic [(6-tert-butoxyhexylmethylsilanediyl)-bis(2-methyl-4-(4-tert-butylphenyl)indene)] hafnium dichloride, which is a compound represented by the following formula A, instead of the metallocene compound [(diethylsilanediyl)-bis((2-methyl-4-tert-butylphenylindene)] zirconium dichloride used in the preparation of Example 1.

[0206] [Formula A]

[0207]

[0208] Comparative Examples 1-2

[0209] The polypropylene resin compositions of Comparative Examples 1-2 were prepared in the same manner as in Examples 1-1, except that the polymerization process was carried out using a catalyst of racemic [(dimethylsilanediyl)-(2-methyl-4-phenylindenyl)(2-methyl-4-phenyl-5-methoxy-6-tert-butyl)]zirconia, which is a compound represented by the following formula B, instead of the metallocene compound [(diethylsilanediyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)]zirconia used in the preparation of Example 1.

[0210] [Formula B]

[0211]

[0212] For reference, Table 1 below summarizes the types of supported catalysts used in each embodiment, the polymerization pressure and temperature of each reactor, the concentration of hydrogen or TEAL introduced into each reactor, and the input amounts of ethylene and propylene gas.

[0213] Table 1

[0214]

[0215] In Table 1, the input amounts of TEAL and H2 are based on the molar content (ppm) of the propylene input.

[0216] Comparative Examples 1-3

[0217] The propylene homopolymer (Homo PP, LG Chem Co., Ltd., H7700, MI) 2.16 (34g / 10min) and ethylene propylene elastomer (C3 POE, Exxon Vistamaxx 6202, MI) 2.16 The polypropylene resin compositions [HomoPP+C3POE(15%)] of Comparative Examples 1-3 were prepared by mixing 20g / 10min to make the content of the elastomer 15% by weight based on the total weight of the entire composition.

[0218] Comparative Examples 1-4

[0219] The propylene homopolymer (Homo PP, LG Chem Co., Ltd., H7700, MI) 2.16 (34g / 10min) and ethylene propylene elastomer (C3 POE, Exxon Vistamaxx 6202, MI) 2.16 The polypropylene resin compositions [HomoPP+C3POE(20%)] of Comparative Examples 1-4 were prepared by mixing 20g / 10min to make the content of the elastomer 20% by weight based on the total weight of the entire composition.

[0220] Comparative Examples 1-5

[0221] A phosphate metal salt type nucleating agent was further added in an amount of 200 ppm (based on the total weight of the resin composition) to the polypropylene resin composition prepared in Comparative Examples 1-2, and the polypropylene resin compositions of Comparative Examples 1-5 were prepared.

[0222] <Test Example 1>

[0223] The physical properties of the polypropylene resin compositions of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-5 were evaluated using the following methods.

[0224] (1) Melt Index (MI)

[0225] According to ASTM D1238, the melt index is measured at 230°C under a load of 2.16 kg and expressed as the weight (g) of the polymer obtained by melting for 10 minutes.

[0226] (2) Ethylene content (C2, weight %)

[0227] The ethylene content in the polypropylene resin compositions of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-5 was measured by infrared spectroscopy according to American Society for Testing and Materials (ASTM) 5576.

[0228] Specifically, the polypropylene resin compositions of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-5 were prepared in the form of films or film samples and then fixed onto the magnetic holder of an FT-IR device. Next, the thickness of the sample, 4800-3500 cm⁻¹, was measured and calculated. -1 The peak height and the 750-710 cm⁻¹ peak indicating the ethylene component in the IR absorption spectrum. -1 The peak area. Ethylene content is calculated by substituting the measured values ​​into a calibration formula, which is plotted by drawing the peak area of ​​standard samples according to ASTM D 5576 method, specifically the 750-710 cm⁻¹ area. -1 Peak area divided by 4800-3500cm -1 The value is obtained by taking the peak height.

[0229] (3) Xylene-soluble matter (XS, wt%)

[0230] 200 mL of xylene was added to 2 g of each of the polypropylene resin compositions of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5, and the mixture was heated to 130°C for 1 hour to completely dissolve the composition. The mixture was then cooled at 20°C for at least 1 hour and filtered. Thus, the solid and liquid phases were separated. The liquid phase was then heated to 130°C to remove the xylene component. The weight of the remaining components was then measured.

[0231] (4) Melting temperature (Tm)

[0232] According to ASTM D 3418, the melting point and melting temperature (Tm) of the polypropylene resin compositions of Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-5 were measured using a differential scanning calorimeter (DSC, device name: DSC 2920, manufacturer: TA Instrument).

[0233] Specifically, the polypropylene resin composition is heated to 200°C and held at that temperature for 5 minutes (1 st RUN (heat history elimination). Then, the temperature is cooled to -30°C and then heated again. The temperature at the top of the DSC (differential scanning calorimeter manufactured by TA Instruments) curve is called the melting point (Tm). In this paper, the temperature is increased and decreased at a rate of 10°C / min, and the melting temperature (Tm) and crystallization temperature (Tc) are determined by the second heating and cooling stage (2 nd The results of the RUN measurement are expressed.

[0234] (5) Crystallization temperature (Tc)

[0235] According to ASTM D 3418, the temperature is lowered using a differential scanning calorimeter (DSC) under the same conditions as the melting temperature measurement, and the temperature at the top of the DSC curve (using a differential scanning calorimeter manufactured by TA Instruments) is taken as the crystallization temperature (Tc).

[0236] (6) Molecular weight distribution (MWD, polydispersity index)

[0237] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the copolymer were measured using gel permeation chromatography (GPC, manufactured by Water), and the molecular weight distribution (MWD) was determined by dividing the weight-average molecular weight by the number-average molecular weight.

[0238] Specifically, a Waters PL-GPC220 instrument was used as the gel permeation chromatography (GPC) instrument, and a Polymer Laboratories PLgel MIX-B column with a length of 300 mm was used. The measurement temperature was 160 °C, 1,2,4-trichlorobenzene was used as the solvent, and a flow rate of 1 mL / min was applied. The polypropylene resin compositions of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-5 were pretreated using a GPC analyzer (PL-GP220) at a concentration of 10 mg / 10 mL by dissolving them in 1,2,4-trichlorobenzene containing 0.0125% BHT at 160 °C for 10 hours. Then, 200 μL of the composition was fed. Calibration curves obtained using polystyrene standards were used to determine the values ​​of Mw and Mn. Nine polystyrene standard samples were used, with weight-average molecular weights of 2000 g / mol, 10000 g / mol, 30000 g / mol, 70000 g / mol, 200000 g / mol, 700000 g / mol, 2000000 g / mol, 4000000 g / mol, and 10000000 g / mol.

[0239] (7) Tensile strength

[0240] According to ASTM D 638, the tensile strength (kg / cm²) of polypropylene resin compositions is measured using a Universal Testing Machine (UTM, manufactured by Instron). 2 ).

[0241] (8) Bending strength and bending modulus

[0242] The flexural strength (kg / cm) of the polypropylene resin composition was measured according to ASTM D 790. 2 ) and flexural modulus (kg / cm) 2 ).

[0243] Specifically, samples prepared according to ASTM standard D790 were laid and fixed onto a carrier, and then the required strength (kg / cm²) was measured when a load of 28 mm / min was applied through the loading nose. 2 The flexural modulus, which indicates stiffness, is measured based on the initial slope value of the flexural strength (which is the maximum value at which the load nose no longer increases) and the flexural force.

[0244] The evaluation results of the physical properties of the polypropylene resin compositions of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-5 measured by the above method are shown in Table 2 below.

[0245] Table 2

[0246]

[0247] Furthermore, to examine the dispersibility of the ethylene-propylene copolymer in the homopolymer matrix of the polypropylene resin compositions of Examples 1-1 and 1-2, cross-sections of each polypropylene resin composition were observed by scanning electron microscopy (SEM). Specifically, the SEM images showing the cross-sections of the polypropylene resin composition of Example 1-1 are shown in [image missing]. Figure 1 The results are shown in the figure (3000x magnification). Here, by minimizing phase separation between the homopolymer matrix and the ethylene-propylene copolymer, the polypropylene resin composition of Example 1-1 exhibits high dispersibility and significantly improved softness, as well as excellent elongation properties and processability.

[0248] As shown in Table 2, compared to the polypropylene resin compositions of Comparative Examples 1-1 to 1-4, the polypropylene resin compositions comprising Examples 1-1 and 1-2 (which were prepared in a continuous reactor in the presence of the metallocene compounds of the present invention having a specific structure) exhibit high tensile strength and flexural modulus, as well as narrow molecular weight distribution and optimized xylene solubles (XS), and have excellent elongation properties and processability as well as improved softness.

[0249] <Preparation of Nonwoven Fabrics>

[0250] Example 2-1

[0251] Polypropylene nonwoven fabrics were produced using the polypropylene resin compositions obtained in Examples 1-1 under the following spinning equipment and conditions.

[0252] <Spinning Equipment and Conditions>

[0253] - Spinning equipment: Name: Fiberio Cyclone TM L-1000

[0254] - Spinning conditions: Temperature 310℃ / Nozzle size 600μm / 13000RPM

[0255] Example 2-2

[0256] Polypropylene nonwoven fabric was produced in the same manner as in Example 2-1, except that the polypropylene resin composition obtained in Example 1-2 was used.

[0257] Comparative Examples 2-1 to 2-4

[0258] Each polypropylene nonwoven fabric was produced in the same manner as in Example 2-1, except that 15% and 20% polypropylene C3-elastomer blends from Comparative Examples 1-1 to 1-4 were used respectively.

[0259] Comparative Examples 2-5

[0260] Polypropylene nonwoven fabric was produced in the same manner as in Examples 2-1, except that the polypropylene resin compositions of Comparative Examples 1-5 were used. However, a problem of single yarns occurred, making spinning impossible.

[0261] <Test Example 2>

[0262] The physical properties of Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-4 were evaluated using the following methods, and the results are shown in Table 3 below.

[0263] (1) Weight of nonwoven fabric

[0264] Measure the weight of the produced nonwoven fabric and calculate the unit area (g / m²). 2 The weight of the nonwoven fabric.

[0265] (2) Average diameter of individual fibers in nonwoven fabric

[0266] The average diameter (fiber diameter, μm) of the fibers constituting the nonwoven fabric was obtained by measuring 400 nonwoven fabric samples using a scanning electron microscope (SEM).

[0267] (3) Softness of nonwoven fabric

[0268] The softness (HOM; total hand, g) of nonwoven fabrics was measured using a softness testing machine from Thwing-Albert Instrument. The softness tester values ​​(Handle-O-meter) used in this paper have an error of +25% to -25%, which is a known deviation from the manufacturer.

[0269] Table 3

[0270]

[0271] As shown in Table 3, compared with the comparative example, the embodiments of the present invention have lower softness tester values, thereby exhibiting excellent softness through refinement (fine fibers).

[0272] Furthermore, the scanning electron microscope (SEM) images of the nonwoven fabrics of Examples 2-1 and 2-2 and Comparative Example 2-4 are shown in... Figure 2 , 3 As shown in Figures 4 and 4. By comparison Figure 2 , 3 Compared to the nonwoven fabrics of Comparative Examples 2-4, the nonwoven fabrics of Examples 2-1 and 2-2 exhibit significantly finer fiber diameters, indicating that the softness of the nonwoven fabrics can be significantly improved.

[0273] Furthermore, as mentioned above, the problem with Comparative Example 2-1 is that the physical properties of the nonwoven fabric are difficult to measure due to the poor spinning properties caused by the wide molecular weight distribution of the polypropylene composition. Moreover, even with an increase in the xylene-soluble (XS) content of the polypropylene composition and an increase in the average fiber diameter of the nonwoven fabric, Comparative Example 2-2 showed a significant decrease in fiber strength. In contrast, the problem with Comparative Example 2-5 is that the physical properties of the nonwoven fabric are difficult to measure because the increased crystallinity of the polypropylene composition and the high crystallization temperature (Tc) cause rapid solidification, resulting in high stress on the filaments during spinning, leading to the formation of single yarns, thus making spinning impossible.

Claims

1. A polypropylene resin composition, wherein: The molecular weight distribution (Mw / Mn) ranged from 2.6 to 3.

2. The xylene-soluble content (XS) ranges from 4.5% to 7.5% by weight. The ethylene content is from 1.0% to 5.0% by weight. The tensile strength measured according to ASTM D 638 method is 275 kg / cm². 2 Up to 285kg / cm 2 , The flexural modulus, measured according to ASTM D 790 method, is 11500 kg / cm². 2 Up to 12500 kg / cm 2 , The melt index (MI) is measured at 230°C under a load of 2.16 kg according to ASTM D 1238. 2.16 The concentration ranges from 10g / 10min to 100g / 10min. The melting temperature is 150℃ to 158℃, and The crystallization temperature (Tc) is 95℃ to 115℃. The polypropylene resin composition comprises a propylene homopolymer and an ethylene-propylene copolymer, wherein the ethylene-propylene copolymer is dispersed in the propylene homopolymer, and The xylene-soluble content was determined at 130°C.

2. The polypropylene resin composition according to claim 1, wherein, The molecular weight distribution (Mw / Mn) is 2.6 to 2.

8.

3. The polypropylene resin composition according to claim 1, wherein, The xylene solubles (XS) are 4.5% to 7.0% by weight.

4. The polypropylene resin composition of claim 1, wherein, The ethylene content is from 2.0% to 3.2% by weight.

5. The polypropylene resin composition of claim 1, wherein, The tensile strength measured according to ASTM D 638 method is 278 kg / cm². 2 Up to 283 kg / cm 2 .

6. The polypropylene resin composition of claim 1, wherein, The flexural modulus, measured according to ASTM D 790 method, is 11800 kg / cm². 2 Up to 12300 kg / cm 2 .

7. The polypropylene resin composition of claim 1, wherein, The melt index (MI) is measured at 230°C under a load of 2.16 kg according to ASTM D 1238. 2.16 The dosage ranges from 20g / 10min to 45g / 10min.

8. The polypropylene resin composition of claim 1, wherein, The crystallization temperature is between 108°C and 112°C.

9. The polypropylene resin composition of claim 1, wherein, The polypropylene resin composition is prepared by a method comprising a series of reactors including one or more first reactors and one or more second reactors in the presence of a catalyst composition comprising one or more metallocene compounds represented by Formula 1, the method comprising the following steps: Propylene homopolymer was prepared in the first reactor; and Ethylene-propylene copolymer is prepared in the second reactor: [Formula 1] In Equation 1, A is carbon, silicon, or germanium. M is a group 4 transition metal. X1 and X2 are each an independent halogen. R1 and R5 are each independently used to replace C. 1-20 C of alkyl 6-20 Aryl, R2 to R4 and R6 to R8 are each independently hydrogen, halogen, or C. 1-20 Alkyl, C 2-20 alkenyl, C 1-20 Alkyl silyl, C 1-20 Silylalkyl, C 1-20 Alkoxysilyl, C 1-20 Ether, C 1-20 Silyl ether, C 1-20 Alkoxy, C 6-20 Aryl, C 7-20 alkylaryl or C 7-20 Arylalkyl, and R9 and R 10 Each independently is C 1-20 alkyl.

10. A polypropylene nonwoven fabric comprising fibers made of the polypropylene resin composition according to any one of claims 1 to 9.

11. The polypropylene nonwoven fabric as described in claim 10, wherein, The average diameter of the fibers is between 5.7 micrometers and 8.5 micrometers.

12. The polypropylene nonwoven fabric as described in claim 10, wherein, When the basis weight of the nonwoven fabric is 72 g / m 2 Up to 76g / m 2 At that time, the softness tester value (Handle-O-meter) measured according to the NWSP 090.3.R0 standard was below 24g.

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