KR20240135380A - Polypropylene resin composition and polypropylene fiber prepared using the same - Google Patents

Abstract

The present invention provides a polypropylene resin composition suitable for an ultra-low basis weight, high strength nonwoven fabric, and a polypropylene fiber manufactured therefrom, by using a polypropylene resin manufactured in the presence of a metallocene compound having a specific structure and a molecular weight regulator within a predetermined range to optimize melting index, melting point, and crystallization temperature together with a narrow molecular weight distribution.

Description

Polypropylene resin composition and polypropylene fiber prepared therefrom {POLYPROPYLENE RESIN COMPOSITION AND POLYPROPYLENE FIBER PREPARED USING THE SAME}

The present invention relates to a polypropylene resin composition suitable for an ultra-low basis weight, high strength nonwoven fabric and a polypropylene fiber produced therefrom.

In general, nonwoven fabrics are fabrics made by bonding or entangling fiber aggregates through mechanical operation, heat bonding, or other mechanical or chemical treatments without going through spinning, weaving, or knitting processes. Felt, resin-bonded nonwoven fabrics, needle-punched, spunbond, spunlace, embossed film, and wet-laid nonwoven fabrics fall into this category. In a narrow sense, it refers to using a web that is randomly overlapped and the contact points of fibers are bonded with resin to use as a lining, etc. It is also called bonded fabric or bonded fabric. Such nonwoven fabrics can be manufactured by various methods, and the known methods are needle-punching, chemical bonding, thermal bonding, melt-blown, spunlace, stitchbond, and spunbond.

Spunbond nonwoven fabrics made from polyolefin resins are widely used in filters, packaging materials, bedding, clothing, medical supplies, sanitary supplies, automobile interiors, and building materials due to their superior texture, flexibility, breathability, and insulation properties. In particular, polypropylene staple fibers are processed into thermal bond nonwoven fabrics through calendar bonding or air-through bonding due to their unique low melting point and excellent chemical resistance, and are mainly used as surface materials for sanitary products such as diapers and sanitary pads.

Meanwhile, due to the recent eco-friendly trend, there is a growing demand for reducing the use of plastic in diapers, etc., and the need for improving strength is increasing so that the weight of spunbond nonwoven fabrics in diaper composition can be reduced. Accordingly, homopolypropylene products based on metallocene catalysts are applied to conventional spunbond nonwoven fabrics to improve strength.

In general, the catalyst systems mainly used for polypropylene polymerization can be classified into Ziegler-Natta and metallocene catalyst systems, and these two highly active catalyst systems have been developed according to their respective characteristics. Since its invention in the 1950s, Ziegler-Natta catalysts have been widely applied to existing commercial processes, but since they are multi-site catalysts with multiple active sites, they are characterized by a wide molecular weight distribution of the polymer, and there is a problem that the composition distribution of the comonomer is not uniform, which limits securing the desired properties.

In addition, the metallocene catalyst is composed of a combination of a main catalyst mainly composed of a transition metal compound and a cocatalyst mainly composed of an organometallic compound composed of aluminum, and such a catalyst is a homogeneous complex catalyst and a single site catalyst, and according to the single site characteristics, a narrow molecular weight distribution is obtained, a polymer having a uniform composition distribution of the comonomer is obtained, and it has the characteristics of being able to change the stereoregularity, copolymerization characteristics, molecular weight, crystallinity, etc. of the polymer depending on the modification of the ligand structure of the catalyst and the change in polymerization conditions.

In the case of polypropylene resin, which is mainly used in the manufacture of spunbond nonwoven fabrics, the strength of the filament is determined by the orientation and degree of crystallization of the polypropylene polymer chain, and in general, in the case of homopolypropylene resin, the strength of spunbond nonwoven fabrics can also increase as the weight average molecular weight increases.

However, as the molecular weight of homopolypropylene resin increases, the risk of single yarns during spinning due to phenomena such as melt fracture and draw resonance increases, and there has been a limitation in securing stable processability during spinning.

In particular, in order to further improve the strength of polypropylene resin for use in manufacturing ultra-low-weight, high-strength nonwoven fabrics in line with recent trends compared to products using conventional technology, the molecular weight distribution must be further narrowed; however, there is a limit to improving the level due to limitations in catalyst technology, and thus it is impossible to improve the fiber strength compared to the current level.

Accordingly, in line with recent environmental issues, there is a need for the development of polypropylene resin compositions and fibers suitable for ultra-low-weight, high-strength nonwoven fabrics that can reduce the use of plastic in diapers and other products.

The present invention aims to provide a polypropylene resin composition in which melting index, melting point, and crystallization temperature are all optimized together with a narrow molecular weight distribution by using polypropylene manufactured in the presence of a metallocene compound of a specific structure and a molecular weight regulator within a predetermined range.

The present invention also seeks to provide a method for producing the above-described polypropylene resin composition.

The present invention also seeks to provide fibers and spunbond nonwoven fabrics manufactured using the above-described polypropylene resin composition.

The present invention provides a polypropylene resin composition having a molecular weight distribution (Mw/Mn) of 1.7 or more and 2.35 or less, a melting index (MI _2.16 , melting index measured at 230°C, 2.16 kg load) of 18 g/10 min or more and 36 g/10 min or less, a melting point (Tm) of 135°C or more, and a crystallization temperature (Tc) of 115°C or less.

In addition, the present invention provides a method for producing the polypropylene resin composition described above.

In addition, the present invention provides polypropylene fibers and spunbond nonwoven fabrics comprising the above-described polypropylene resin composition.

The polypropylene resin composition according to the present invention is advantageous in producing a spunbond nonwoven fabric having high strength together with ultra-low basis weight characteristics so that the weight can be minimized when used in diapers, etc., by optimizing the melt index, melting point, and crystallization temperature together with a narrow molecular weight distribution by using polypropylene manufactured in the presence of a metallocene compound having a specific structure and a molecular weight regulator within a predetermined range.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the invention.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this specification, the terms “comprise,” “include,” or “have” are intended to describe a feature, number, step, component, or combination thereof implemented, but do not exclude the possibility of one or more other features, numbers, steps, components, combinations, or additions thereof.

Additionally, in this specification, when each layer or element is referred to as being formed “on” or “over” each of the layers or elements, it means that each layer or element is formed directly over each of the layers or elements, or that other layers or elements may be additionally formed between each of the layers, on the object, or on the substrate.

The present invention may have various modifications and may take various forms, and specific embodiments are exemplified and described in detail below. However, this does not limit the present invention to a specific disclosed form, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

Hereinafter, a polypropylene resin composition according to a specific embodiment of the invention, a method for producing the same, and fibers including the same will be described.

Polypropylene resin composition

A polypropylene resin composition according to one embodiment of the invention is characterized in that it satisfies all of the conditions of having a molecular weight distribution (Mw/Mn) of 1.7 or more and 2.35 or less, a melting index (MI _2.16 , melting index measured at 230°C, 2.16 kg load) of 18 g/10 min or more and 36 g/10 min or less, a melting point (Tm) of 135°C or more, and a crystallization temperature (Tc) of 115°C or less.

In the present invention, when producing a polypropylene resin composition useful for producing fibers, particularly high-strength yarns, suitable for ultra-low basis weight, high-tenacity nonwoven fabrics capable of reducing the amount of plastic used in diapers and the like in line with recent environmentally friendly issues, the resin composition having optimized properties, including melting index, melting point, and crystallization temperature, together with a narrow molecular weight distribution, by using polypropylene produced in the presence of a metallocene compound having a specific structure and a molecular weight regulator within a predetermined range, can significantly increase the elongation ratio during fiber processing, thereby exhibiting high strength and excellent processability suitable for ultra-low basis weight, high-tenacity nonwoven fabrics capable of reducing the amount of plastic used in diapers and the like in line with recent environmentally friendly issues.

Specifically, the polypropylene resin composition has a molecular weight distribution (Mw/Mn, MWD) of 1.7 or more and 2.35 or less. More specifically, the molecular weight distribution (Mw/Mn, MWD) of the polypropylene resin composition may be 1.75 or more, or 1.78 or more, or 1.8 or more, or 1.82 or more, or 1.85 or more, or 1.88 or more, or 1.9 or more, or 1.92 or more, or 1.95 or more, and 2.34 or less, or 2.33 or less, or 2.32 or less, or 2.31 or less, or 2.3 or less, or 2.28 or less. The polypropylene resin composition has a narrow molecular weight distribution of 2.35 or less, and thus has increased rigidity, and can exhibit excellent mechanical properties when manufacturing a fiber product for multifilament or spunbond. In addition, if the molecular weight distribution of the polypropylene resin composition becomes too small, less than 1.7, a problem of reduced processability due to poor spinning during fiber manufacturing may occur.

In one embodiment of the invention, the molecular weight distribution can be obtained by measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polypropylene resin composition using gel permeation chromatography (GPC), and calculating the ratio of the weight average molecular weight to the number average molecular weight (Mw/Mn) as the molecular weight distribution.

Specifically, a Waters PL-GPC220 gel permeation chromatography (GPC) device can be used, and a Polymer Laboratories PLgel MIX-B 300 mm long column can be used. At this time, the measurement temperature is 160 ℃, 1,2,4-trichlorobenzene can be used as a solvent, and a flow rate of 1 mL/min can be applied. Each polypropylene sample can be pretreated by dissolving it in 1,2,4-trichlorobenzene containing 0.0125% BHT at 160 ℃ for 10 hours using a GPC analysis device (PL-GP220), preparing it at a concentration of 10 mg/10 mL, and then supplying it in an amount of 200 μL for measurement. In addition, the values of Mw and Mn can be derived using a calibration curve formed using a polystyrene standard specimen. The weight average molecular weight of polystyrene standard specimens can be used in nine types: 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.

In addition, the polypropylene resin composition may have a weight average molecular weight of 150,000 g/mol or more, or from 150,000 g/mol to 230,000 g/mol. Specifically, the weight average molecular weight of the polypropylene resin composition may be 155,000 g/mol or more, or 160,000 g/mol or more, or 165,000 g/mol or more, or 170,000 g/mol or more, and 225,000 g/mol or less, or 220,000 g/mol or less, or 215,000 g/mol or less, or 210,000 g/mol or less.

Meanwhile, the polypropylene resin composition exhibits an optimized melt index along with a narrow molecular weight distribution (MWD), thereby enabling the production of fibers suitable for spunbond nonwoven fabrics having high strength and ultra-low basis weight characteristics that enable the content to be minimized relative to the application volume when used in diapers, etc.

Specifically, the polypropylene resin composition has a melt index (MI _2.16 , melt index measured at 230° C., 2.16 kg load) of 18 g/10 min or more and 36 g/10 min or less, as measured at 230° C., 2.16 kg load, in accordance with the American Society for Testing and Materials standard ASTM D 1238. More specifically, the melting index (MI _2.16 ) of the polypropylene resin composition may be 19 g/10min or more, or 20 g/10min or more, or 22 g/10min or more, or 24 g/10min or more, or 25 g/10min or more, or 28 g/10min or more, and 35.5 g/10min or less, or 35 g/10min or less, or 34.5 g/10min or less, or 34 g/10min or less, or 33.5 g/10min or less, or 33 g/10min or less, or 32.5 g/10min or less, or 32 g/10min or less. Here, in order to exhibit high strength during fiber production, the melting index (MI _2.16 ) of the polypropylene resin composition should be 18 g/10min or more. However, if the melting index (MI _2.16 ) of the polypropylene resin composition exceeds 36 g/10 min and becomes too large, the viscosity and molecular weight of the resin composition may decrease, resulting in a problem of reduced strength during fiber manufacturing.

For example, the polypropylene resin composition may have a melt index (MI _2.16 , melt index measured at 230° C., 2.16 kg load) of 22 g/10 min or more to 27 g/10 min or less, or 23.5 g/10 min or more to 26.5 g/10 min or less, or 24 g/10 min or more to 25 g/10 min or less, and a molecular weight distribution (Mw/Mn) of 1.85 or more to 2.35 or less, or 1.88 or more to 2.34 or less, or 1.9 or more to 2.33 or less. In addition, the polypropylene resin composition may have a melt index (MI _2.16 , melt index measured at 230° C., 2.16 kg load) of 30 g/10 min or more to 36 g/10 min or less, or 32 g/10 min or more to 35.5 g/10 min or less, or 33 g/10 min or more to 35 g/10 min or less, and a molecular weight distribution (Mw/Mn) of 1.7 or more to 2.3 or less, or 1.75 or more to 2.28 or less, or 1.85 or more to 2.26 or less.

Meanwhile, the polypropylene resin composition has an optimized molecular weight distribution (MWD) and melting index as described above, and has both a melting point (Tm) and a crystallization temperature (Tc) within an optimal range, thereby enabling the production of fibers suitable for spunbond nonwoven fabrics having high strength and ultra-low basis weight characteristics that enable the use of plastic to be minimized when used in diapers, etc.

Specifically, the polypropylene resin composition has a melting point (Tm) of 135°C or higher or 135°C or higher to 155°C, and a crystallization temperature (Tc) of 115°C or lower or 95°C or higher to 115°C or lower.

More specifically, the melting point (Tm) of the polypropylene resin composition may be 136° C. or higher, or 138° C. or higher, or 140° C. or higher, or 142° C. or higher, or 145° C. or higher, or 148° C. or higher, or 150° C. or higher, and 154.5° C. or lower, or 154° C. or lower, or 153.5° C. or lower, or 153° C. or lower, or 152.5° C. or lower, or 152° C. or lower. In particular, in terms of securing excellent mechanical properties such as high strength and excellent heat resistance during fiber manufacturing, the melting point (Tm) of the polypropylene resin composition should be 135° C. or higher.

In addition, the crystallization temperature (Tc) of the polypropylene resin composition may be 113.5° C. or less, or 113° C. or less, or 112.5° C. or less, or 112° C. or less, or 111.5° C. or less, or 111° C. or less, or 111.5° C. or less, or 110° C. or less, and 96° C. or more, or 98° C. or more, or 100° C. or more, or 102° C. or more, or 105° C. or more. In particular, in terms of preventing a rapid viscosity increase and spinning defects due to excessive solidification of the spinning filament during fiber manufacturing, the crystallization temperature (Tc) of the polypropylene resin composition should be 115° C. or less.

In one embodiment of the invention, the melting point (Tm) and the crystallization temperature (Tc) can be measured using a differential scanning calorimeter (DSC, for example, DSC 2920, manufactured by TA instrument). Specifically, the temperature is increased, the polypropylene polymer is heated to 200°C, maintained at that temperature for 5 minutes, then decreased to 30°C, and the temperature is increased again, and the temperature corresponding to the top of the DSC (Differential Scanning Calorimeter, manufactured by TA Instrument) curve is taken as the melting point (Tm). Thereafter, when the temperature is lowered again to 30°C, the top of the curve is taken as the crystallization temperature (Tc). At this time, the speed of the temperature increase and decrease is 10°C/min, and the melting point (Tm) and the crystallization temperature (Tc) are expressed as the results measured in the section where the second temperature increases and decreases.

As described above, the polypropylene resin composition of the present invention has high rigidity along with excellent process stability and processability compared to conventional Ziegler-Natta catalyst-applied polypropylene or conventional metallocene catalyst-applied homopolypropylene or propylene copolymer, polybutene, etc., while at the same time securing properties suitable for ultra-low basis weight, high rigidity nonwoven fabrics that can reduce the amount of plastic used in diapers, etc. in line with recent environmentally friendly issues.

The resin composition of the present invention may contain one or more additives, such as an antioxidant, a lubricant, a UV stabilizer, a neutralizer, a dispersant, a weathering agent, an antistatic agent, a UV stabilizer, a slip agent, an antiblocking agent, talc, a nucleating agent, etc., within a range that does not impair the properties of the resin composition. More specifically, as the additive, at least one selected from the group consisting of an antioxidant, a lubricant, a UV stabilizer, and a neutralizer may be additionally used.

Method for producing polypropylene resin composition

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

In the present invention, the method for producing the polypropylene resin composition comprises the steps of: polymerizing a propylene monomer in the presence of a catalyst composition including at least one metallocene compound represented by the following chemical formula 1 and hydrogen gas to produce a polypropylene resin; and melt-extruding a mixture including the polypropylene resin and a molecular weight regulator under conditions of 120° C. or higher to 300° C. or lower, wherein the molecular weight regulator is included in an amount of 210 ppm to 940 ppm relative to the weight of the polypropylene resin.

[Chemical Formula 1]

In the above chemical formula 1,

A is carbon, silicon or germanium,

M is zirconium, or hafnium,

X ₁ and X ₂ are each independently a halogen,

R ₁ and R ₅ are each independently C _6-20 aryl substituted with C _1-20 alkyl,

R ₂ to R ₄ and R ₆ to R ₈ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 alkoxysilyl, C _1-20 ether, C _1-20 silylether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,

R ₉ is C _1-20 alkyl which is unsubstituted or substituted with C _1-20 alkoxy,

R ₁₀ is C _1-20 alkyl or C _2-20 alkenyl.

Meanwhile, in this specification, unless otherwise specifically limited, the following terms may be defined as follows:

A halogen can be fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

The alkyl having 1 to 20 carbon atoms, i.e., C _1-20 , can be a straight-chain, branched-chain or cyclic alkyl. Specifically, the alkyl having 1 to 20 carbon atoms can be a straight-chain alkyl having 1 to 20 carbon atoms; a straight-chain alkyl having 1 to 15 carbon atoms; a straight-chain alkyl having 1 to 5 carbon atoms; a branched-chain or cyclic alkyl having 3 to 20 carbon atoms; a branched-chain or cyclic alkyl having 3 to 15 carbon atoms; or a branched-chain or cyclic alkyl having 3 to 10 carbon atoms. For example, the alkyl having 1 to 20 carbon atoms (C _1-20 ) may include, but is not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and the like.

Alkenyl having 2 to 20 carbon atoms, i.e., C _2-20, includes straight-chain or branched alkenyl, and specifically includes, but is not limited to, allyl, allyl, ethenyl, propenyl, butenyl, pentenyl, etc.

Alkoxy having 1 to 20 carbon atoms, i.e., C _1-20 , includes, but is not limited to, a methoxy group, ethoxy, isopropoxy, n-butoxy, tert-butoxy, phenyloxy, and cyclohexyloxy groups.

An alkoxyalkyl group having 2 to 20 carbon atoms, i.e., C _2-20 , is a functional group in which at least one hydrogen of the above-mentioned alkyl is replaced with alkoxy, and specifically, examples thereof include alkoxyalkyl such as methoxymethyl, methoxyethyl, ethoxymethyl, iso-propoxymethyl, iso-propoxyethyl, iso-propoxypropyl, iso-propoxyhexyl, tert-butoxymethyl, tert-butoxyethyl, tert-butoxypropyl, tert-butoxyhexyl; or aryloxyalkyl such as phenoxyhexyl, but is not limited thereto.

Alkylsilyl having 1 to 20 carbon atoms, that is, a C _1-20 alkoxysilyl group, or a C _1-20 alkoxysilyl group is a functional group in which 1 to 3 hydrogens of -SiH ₃ are replaced with 1 to 3 of the above-described alkyl or alkoxy groups, and specifically, examples thereof include, but are not limited to, alkylsilyl such as methylsilyl, dimethylsilyl, trimethylsilyl, dimethylethylsilyl, diethylmethylsilyl, or dimethylpropylsilyl; alkoxysilyl such as methoxysilyl, dimethoxysilyl, trimethoxysilyl, or dimethoxyethoxysilyl; and alkoxyalkylsilyl such as methoxydimethylsilyl, diethoxymethylsilyl, or dimethoxypropylsilyl.

Silylalkyl having 1 to 20 carbon atoms, i.e., C _1-20 , is a functional group in which one or more hydrogens of the above-described alkyl are replaced with silyl, and specifically, examples thereof include, but are not limited to, -CH ₂ -SiH ₃ , methylsilylmethyl, or dimethylethoxysilylpropyl.

In addition, alkylene having 1 to 20 carbon atoms, i.e., C _1-20 , is the same as the alkyl described above except that it is a divalent substituent, and specifically includes methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, etc., but is not limited thereto.

Aryl having 6 to 20 carbon atoms, i.e., C _6-20 , can be a monocyclic, bicyclic or tricyclic aromatic hydrocarbon. By way of example, the aryl can include, but is not limited to, phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, fluorenyl, and the like.

Alkylaryl having 7 to 20 carbon atoms, i.e., C _7-20 , may refer to a substituent in which at least one of the hydrogens of the aromatic ring is substituted by the above-described alkyl. As examples, the alkylaryl may include, but is not limited to, methylphenyl, ethylphenyl, methylbiphenyl, methylnaphthyl, etc.

In addition, arylalkyl having 7 to 20 carbon atoms, i.e., C _7-20 , may refer to a substituent in which one or more hydrogens of the above-described alkyl are replaced by the above-described aryl. As examples, the arylalkyl may include, but is not limited to, phenylmethyl, phenylethyl, biphenylmethyl, naphthylmethyl, and the like.

In addition, arylene having 6 to 20 carbon atoms, i.e., C _6-20 , is the same as the aryl described above except that it is a divalent substituent, and specifically includes, but is not limited to, phenylene, biphenylene, naphthylene, anthracenylene, phenanthrenylene, fluorenylene, etc.

And, the group 4 transition metal may be titanium (Ti), zirconium (Zr), hafnium (Hf), or rutherfordium (Rf), specifically titanium (Ti), zirconium (Zr), or hafnium (Hf), more specifically zirconium (Zr) or hafnium (Hf), but is not limited thereto.

Additionally, the group 13 element may be boron (B), aluminum (Al), gallium (Ga), indium (In), or thallium (Tl), specifically, but not limited to, boron (B) or aluminum (Al).

The above-described substituents may be optionally substituted with one or more substituents selected from the group consisting of a hydroxy group; a halogen; an alkyl or alkenyl, an aryl, an alkoxy; an alkyl or alkenyl, an aryl, an alkoxy containing one or more heteroatoms of groups 14 to 16; a silyl; an alkylsilyl or alkoxysilyl; a phosphine group; a phosphide group; a sulfonate group; and a sulfone group, within a range that exhibits the same or similar effect as the desired effect.

A catalyst composition used in the production of a polypropylene resin composition according to one embodiment of the invention is characterized by including a metallocene compound represented by the chemical formula 1. In particular, when a metallocene catalyst having a specific substituent in a bridging group connecting two ligands including an indenyl group is used, polypropylene having optimized molecular weight distribution, melting index, melting point, and crystallization temperature all to suit the desired properties can be produced.

Furthermore, the compound of the above chemical formula 1 includes a divalent functional group A substituted with two identical alkyl groups having 2 or more carbon atoms as a bridging group connecting two ligands including an indenyl group, thereby increasing the atomic size and increasing the available angle, thereby facilitating the approach of monomers and exhibiting better catalytic activity.

In addition, in the compound of the above chemical formula 1, since both indenyl groups, which are ligands, are substituted with methyl groups at position 2 and position 4 (i.e., R ₁ and R ₅ ) each include alkyl-substituted aryl groups, superior catalytic activity can be exhibited due to the inductive effect capable of supplying sufficient electrons.

More specifically, in the chemical formula 1, R ₁ and R ₅ can each independently be C _6-12 aryl substituted with C _1-10 alkyl, and even more specifically, phenyl substituted with C _3-6 branched-chain alkyl such as tert-butyl phenyl. In addition, the substitution position of alkyl with respect to phenyl can be, that is, the 4-position corresponding to the indenyl bonding position and the para position of R ₁ and R ₅ bonded to indenyl.

For example, R ₁ and R ₅ are phenyl substituted with tert-butyl. More preferably, R ₁ and R ₅ are 4-tert-butyl-phenyl.

In addition, in the chemical formula 1, R ₂ to R ₄ and R ₆ to R ₈ can each independently be hydrogen, and X ₁ and X ₂ can each independently be chloro (Cl).

In addition, in the chemical formula 1, A may be silicon (Si). In addition, each of the substituents R ₉ and R ₁₀ of A may be In terms of improving the loading efficiency by increasing the solubility, R ₉ may be a C _1-10 alkyl group which is unsubstituted or substituted with C _3-6 alkoxy, and R ₁₀ may be a C _1-10 alkyl group. Specifically, R ₉ may be 6-tert-butoxy-hexyl, R ₁₀ may be methyl, or both R ₉ and R ₁₀ may be ethyl.

In addition, in the chemical formula 1, M may be zirconium (Zr). In particular, when zirconium (Zr) is included as a central metal in the compound of the chemical formula 1, it has more orbitals capable of accepting electrons compared to when it includes other Group 14 elements such as hafnium (Hf), so it can easily bind to a monomer with higher affinity, and as a result, it can exhibit a better catalytic activity improvement effect.

And, the metallocene compound may be, specifically, for example, any one of the compounds having the following structural formula:

, .

The compound of the above structural formula is only an example for explaining the present invention, and the present invention is not limited thereto.

In addition, the metallocene compound represented by the chemical formula 1 can be prepared by a known method for synthesizing organic compounds, and is described in more detail in the examples described below.

Meanwhile, in the present specification, with respect to a method for producing a metallocene compound or a catalyst composition used for producing a polypropylene resin according to one embodiment of the invention, equivalent (eq) means molar equivalent (eq/mol).

In the catalyst composition used for producing a polypropylene resin composition according to one embodiment of the invention, the metallocene compound of the chemical formula 1 may be used in the form of a supported catalyst supported on a carrier, or may also be used in the form of an unsupported catalyst. In particular, it is more preferable to use it in the form of a supported catalyst in terms of securing the stability of the polymerization process using the catalyst composition and the uniformity of the physical property control.

As the carrier, a carrier having a highly reactive hydroxyl group or siloxane group on the surface can be used, and preferably, a carrier having a highly reactive hydroxyl group and siloxane group that has been dried and has moisture removed from the surface can be used.

For example, silica, silica-alumina, and silica-magnesia dried at high temperatures can be used, and these can typically contain oxide, carbonate, sulfate, and nitrate components such as Na ₂ O, K ₂ CO ₃ , BaSO ₄ , and Mg(NO ₃ ) ₂ .

The drying temperature of the carrier is preferably about 200° C. to about 800° C., more preferably about 300° C. to about 600° C., and most preferably about 300° C. to about 400° C. If the drying temperature of the carrier is less than about 200° C., the moisture content is too high, causing the moisture on the surface to react with the cocatalyst, and if it exceeds about 800° C., the pores on the surface of the carrier merge, reducing the surface area, and also reducing many hydroxyl groups on the surface, leaving only siloxane groups, reducing the reaction sites with the cocatalyst, which is not preferable.

For example, the amount of hydroxyl groups on the surface of the carrier is preferably about 0.1 mmol/g to about 10 mmol/g, and more preferably about 0.5 mmol/g to about 5 mmol/g. The amount of hydroxyl groups on the surface of the carrier can be controlled by the manufacturing method and conditions of the carrier or the drying conditions, such as temperature, time, vacuum or spray drying. If the amount of hydroxyl groups is less than about 0.1 mmol/g, there are few reaction sites with a cocatalyst, etc., and if it exceeds about 10 mmol/g, it is not preferable because there is a possibility that the reaction is caused by moisture other than the hydroxyl groups present on the surface of the carrier particles.

When the metallocene compound of the above chemical formula 1 is supported on a carrier, the weight ratio of the total transition metal included in the metallocene compound represented by the above chemical formula 1 to the carrier may be about 1:1 to about 1:1000. When the carrier and the metallocene compound are included at the above weight ratio, appropriate supported catalytic activity may be exhibited, which may be advantageous in terms of maintaining the activity of the catalyst and economic efficiency. More specifically, the weight ratio of the compound of the above chemical formula 1 to the carrier may be 1:10 to 1:30, and even more specifically, 1:15 to 1:20.

In addition, the catalyst composition may additionally include a cocatalyst in addition to the metallocene compound of the chemical formula 1 and the carrier to improve high activity and process stability.

Specifically, the cocatalyst may include at least one compound represented by the following chemical formula 2.

[Chemical formula 2]

-[Al(R ²¹ )-O] _m -

In the above chemical formula 2,

R ²¹ are the same or different and each independently represent halogen, C _1-20 alkyl or C _1-20 haloalkyl;

m is an integer greater than or equal to 2.

Examples of compounds represented by the above chemical formula 2 include aluminoxane compounds such as methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, or butylaluminoxane, and one or a mixture of two or more of these may be used.

In addition, the cocatalyst may include at least one compound represented by the following chemical formula 3.

[Chemical Formula 3]

J(R ³¹ ) ₃

In the above chemical formula 3,

R ³¹ are the same or different and each independently represent halogen, C _1-20 alkyl or C _1-20 haloalkyl;

J is aluminum or boron.

Examples of the compound represented by the above chemical formula 3 include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylchloroaluminum, triisopropylaluminum, tri-s-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylaluminum methoxide, dimethylaluminum ethoxide, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, and the like, and more specifically, the compound may be selected from trimethylaluminum, triethylaluminum, and triisobutylaluminum. there is.

In addition, the cocatalyst may include at least one compound represented by the following chemical formula 4.

[Chemical Formula 4]

[EH] ⁺ [ZQ ₄ ] ^-

In the above chemical formula 4,

E is a neutral or cationic Lewis base;

H is a hydrogen atom;

Z is a group 13 element;

Q is, same or different, each independently C _6-20 aryl or C _1-20 alkyl, wherein said C _6-20 aryl or C _1-20 alkyl is unsubstituted or substituted with one or more substituents selected from the group consisting of halogen, C _1-20 alkyl, C _1-20 alkoxy and C _6-20 aryloxy.

Specifically, in the above chemical formula 4, E can be an amine containing one or more nitrogen atoms, and the amine can be substituted with C _6-20 aryl or C _1-20 alkyl. For example, E can be an amine containing one or two nitrogen atoms, and the amine group can be substituted with two or more C _6-20 aryl or C _1-20 alkyl. Alternatively, the amine can be substituted with two or three C _6-18 aryl or C _6-12 aryl, or C _1-12 alkyl or C _1-6 alkyl.

For example, in the chemical formula 4, [EH] ⁺ may be a Bronsted acid.

Specifically, in the chemical formula 4, Z can be aluminum or boron.

Specifically, in the chemical formula 4, Q may be C _6-18 aryl or C _6-12 aryl, which is substituted or unsubstituted as described above, or C _1-12 alkyl or C _1-6 alkyl, respectively.

Examples of compounds represented by the above chemical formula 4 include triethylammonium tetraphenylboron, tributylammonium tetraphenylboron, trimethylammonium tetraphenylboron, tripropylammonium tetraphenylboron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, trimethylammonium tetra(p-trifluoromethylphenyl)boron, tributylammonium tetrapentafluorophenylboron, N,N-diethylanilinium tetraphenylboron, N,N-diethylanilinium tetrapentafluorophenylboron, diethylammonium tetrapentafluorophenylboron, triphenylphosphonium tetraphenylboron, trimethylphosphonium tetraphenylboron, triethylammonium tetraphenylaluminum, tributylammonium tetraphenylaluminum, trimethylammonium tetraphenylaluminum, Tripropylammonium tetraphenylaluminum, trimethylammonium tetra(p-tolyl)aluminum, tripropylammonium tetra(p-tolyl)aluminum, triethylammonium tetra(o,p-dimethylphenyl)aluminum, tributylammonium tetra(p-trifluoromethylphenyl)aluminum, trimethylammonium tetra(p-trifluoromethylphenyl)aluminum, tributylammonium tetrapentafluorophenylaluminum, N,N-diethylanilinium tetraphenylaluminum, N,N-diethylanilinium tetrapentafluorophenylaluminum, diethylammonium tetrapentatetraphenylaluminum, triphenylphosphonium tetraphenylaluminum, trimethylphosphonium tetraphenylaluminum, tripropylammonium tetra(p-tolyl)boron, triethylammonium tetra(o,p-dimethylphenyl)boron, Examples thereof include tributylammonium tetra(p-trifluoromethylphenyl)boron, triphenylcarbonium tetra(p-trifluoromethylphenyl)boron, or triphenylcarbonium tetrapentafluorophenylboron, and one or a mixture of two or more thereof may be used.

When the above-described cocatalyst is further included, the weight ratio of the metallocene compound of the above chemical formula 1 to the cocatalyst may be about 1:1 to about 1:20. When the cocatalyst and the metallocene compound are included at the above-described weight ratio, appropriate supported catalytic activity may be exhibited, which may be advantageous in terms of maintaining the activity of the catalyst and economic efficiency. More specifically, the weight ratio of the compound of the above chemical formula 1 to the cocatalyst may be about 1:5 to about 1:20, or about 1:5 to about 1:15.

The above-mentioned cocatalyst may be supported in an amount of about 3 mmol or more or about 5 mmol or more per weight of the carrier, for example, based on 1 g of silica, and may also be supported in an amount of about 20 mmol or less or about 15 mmol or less. When included in the above-mentioned content range, an effect of improving catalytic activity due to the use of the cocatalyst may be exhibited.

When the above catalyst composition includes both the above-described carrier and the cocatalyst, the catalyst composition can be manufactured by a manufacturing method including a step of supporting a cocatalyst compound on the carrier, and a step of supporting a compound represented by the chemical formula 1 on the carrier. In this case, the order of supporting the cocatalyst and the metallocene compound of the chemical formula 1 can be changed as needed.

At this time, when preparing the catalyst composition, a hydrocarbon solvent such as pentane, hexane, heptane, etc., or an aromatic solvent such as benzene, toluene, etc. can be used as a reaction solvent.

Meanwhile, a polypropylene resin composition according to one embodiment of the invention can be manufactured by a method including a step of manufacturing a polypropylene resin by polymerizing a propylene monomer in the presence of a catalyst composition, including at least one metallocene compound represented by the chemical formula 1.

For example, the propylene polymerization reaction can be carried out using a continuous slurry polymerization reactor, a loop slurry reactor, a gas phase reactor or a solution reactor.

In particular, a polypropylene resin composition according to one embodiment of the invention can be manufactured by including a step of homopolymerizing propylene in the presence of at least one metallocene compound represented by the chemical formula 1.

For example, a polypropylene resin composition according to one embodiment of the invention can be manufactured by a bulk slurry process in the presence of a catalyst composition including at least one metallocene compound represented by the chemical formula 1 described above.

At this time, the polymerization process may be a loop reactor, for example, a Spheripol process reactor including two loop reactors.

Specifically, the polymerization process may be comprised of a reaction system including a plurality of loop reactors, and may be a process of continuously polymerizing a liquid propylene monomer in the presence of a catalyst and hydrogen gas within the reaction system including a plurality of loop reactors to produce a propylene homopolymer.

The production of the above polypropylene resin can be carried out through a polymerization process in which a propylene monomer is contacted in the presence of hydrogen gas in the presence of the above-described catalyst composition.

The above hydrogen gas activates the inactive site of the metallocene catalyst and causes a chain transfer reaction, thereby controlling the molecular weight. The metallocene compound of the present invention has excellent hydrogen reactivity, and therefore, by controlling the amount of hydrogen gas used during the polymerization process, a polypropylene having a desired level of molecular weight and melting index can be effectively obtained.

The hydrogen gas may be introduced in an amount of 10 to 360 ppm based on the total mole number of propylene monomers. By supplying hydrogen gas in this amount and proceeding with polymerization, a polypropylene resin having an optimal range of weight average molecular weight together with the above-described physical property requirements, particularly a narrow molecular weight distribution and a low melting index, can be manufactured. If the amount of hydrogen gas introduced is less than 10 ppm, the melting index of the polypropylene resin to be manufactured is greatly reduced, so that the flowability and ejection property of the final polypropylene resin composition deteriorate, making the spinning process impossible. On the other hand, if the amount of hydrogen gas introduced exceeds 360 ppm, the melting index of the polypropylene resin becomes excessively high, so that the fiber rigidity of the final polypropylene resin composition may deteriorate. More specifically, the hydrogen gas may be introduced in an amount of 30 ppm or more, or 40 ppm or more, or 50 ppm or more, and 300 ppm or less, or 250 ppm or less, or 230 ppm or less, based on the total mole number of propylene monomers.

The above polymerization process can be carried out as a continuous polymerization process, and various polymerization processes known as polymerization reactions of olefin monomers, such as a continuous solution polymerization process, a bulk polymerization process, a suspension polymerization process, a slurry polymerization process, or an emulsion polymerization process, can be employed. In addition, the polymerization reaction can be carried out by homopolymerizing a propylene monomer using one or two continuous slurry polymerization reactors, a loop slurry reactor, a gas phase reactor, or a solution reactor. In particular, a continuous bulk-slurry polymerization process may be preferable in terms of obtaining a uniform molecular weight distribution and commercial production of the product.

And, the polymerization temperature may be 25 ℃ to 200 ℃, preferably 40 ℃ to 150 ℃, more preferably 60 ℃ to 100 ℃. In addition, the polymerization pressure may be 1 kgf/cm2 to 100 kgf/cm2, preferably 1 kgf/cm2 to 80 Kgf/cm2, more preferably 5 kgf/cm2 to 50 kgf/cm2. Polymerization proceeds under such temperature and pressure, so that homo polypropylene having desired properties can be manufactured in a high yield.

In addition, the polymerization process can be performed by selectively adding at least one aluminum-based compound represented by the following chemical formula 5 when polymerizing a propylene monomer in the presence of a catalyst composition including at least one metallocene compound represented by the chemical formula 1 and hydrogen gas.

[Chemical Formula 5]

Al(R ⁵¹ ) ₃

In the above chemical formula 5,

R ⁵¹ are the same or different and each independently is halogen, C _1-20 alkyl or C _1-20 haloalkyl.

Specifically, examples of the aluminum-based compound represented by the chemical formula 5 include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylchloroaluminum, triisopropylaluminum, tri-s-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylaluminum methoxide, and dimethylaluminum ethoxide, and more specifically, the aluminum-based compound may be at least one selected from trimethylaluminum, triethylaluminum, and triisobutylaluminum.

In addition, when adding and introducing an aluminum-based compound represented by the chemical formula 5 to the polymerization reaction, it can be used in an amount of 0.001 wt% or more to 1.2 wt% or less based on the total weight of the propylene monomer. Specifically, the aluminum-based compound represented by the chemical formula 5 can be introduced in an amount of 0.01 wt% or more, or 0.02 wt% or more, or 0.05 wt% or more, or 0.08 wt% or more, or 0.1 wt% or more, and 1 wt% or less, or 0.8 wt% or less, or 0.5 wt% or less.

In particular, when manufacturing a polypropylene resin by polymerizing a propylene monomer, if moisture or impurities exist in the polymerization reactor, part of the catalyst will be decomposed. Accordingly, the aluminum-based compound represented by the chemical formula 5 acts as a scavenger that catches moisture or impurities existing in the reactor in advance, so that the activity of the catalyst used in manufacturing can be maximized, and as a result, a polypropylene resin satisfying the above-mentioned physical property requirements can be manufactured more efficiently. If such an aluminum-based compound is not used, the structural characteristics of the catalyst may change, such as the activity being lowered due to the catalyst poisoning caused by moisture or impurities in the polymerization process, so that the desired physical properties may not be satisfied.

Meanwhile, in the present invention, by manufacturing a polypropylene resin by the method described above and then mixing a molecular weight regulator under optimized conditions as described below and melt-extruding the polypropylene resin, it is possible to manufacture a polypropylene resin composition having high rigidity along with excellent process stability and processability compared to conventional Ziegler-Natta catalyst-applied polypropylene or conventional metallocene catalyst-applied polypropylene resin, i.e., homopolypropylene or propylene copolymer, while at the same time having properties suitable for ultra-low basis weight, high-rigidity nonwoven fabrics that can reduce the amount of plastic used in diapers, etc. in line with recent environmentally friendly issues.

Meanwhile, the polypropylene resin may have a melting index, melting point, and crystallization temperature in an optimized range along with a molecular weight distribution.

For example, the polypropylene resin may have a molecular weight distribution (Mw/Mn, MWD) of 2.0 or more and 3.0 or less. Specifically, the molecular weight distribution (Mw/Mn, MWD) of the polypropylene resin may be 2.1 or more, or 2.15 or more, or 2.2 or more, or 2.25 or more, or 2.3 or more, or 2.35 or more, or 2.38 or more, or 2.4 or more, or 2.45 or more, and 2.95 or less, or 2.9 or less, or 2.85 or less, or 2.8 or less, or 2.75 or less, or 2.7 or less, or 2.65 or less, or 2.6 or less.

In addition, the polypropylene resin may have an optimized molecular weight distribution and a high weight average molecular weight. Specifically, the polypropylene resin may have a weight average molecular weight of 210,000 g/mol or more, or from 210,000 g/mol to 375,000 g/mol. More specifically, the weight average molecular weight of the polypropylene resin may be 220,000 g/mol or more, or 230,000 g/mol or more, or 240,000 g/mol or more, or 250,000 g/mol or more, and 370,000 g/mol or less, or 360,000 g/mol or less, or 355,000 g/mol or less, or 350,000 g/mol or less.

In another embodiment of the invention, the molecular weight distribution and the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polypropylene resin can be measured using a gel permeation chromatography (GPC) device, and the specific measurement method is as described above.

In addition, the polypropylene resin may have a melt index (MI _2.16 , melt index measured at 230° C., 2.16 kg load) of 2 g/10 min or more and 11 g/10 min or less, as measured at 230° C., 2.16 kg load, in accordance with the American Society for Testing and Materials standard ASTM D 1238. Specifically, the melting index (MI _2.16 ) of the polypropylene resin is 2.2 g/10min or more, or 2.5 g/10min or more, or 2.8 g/10min or more, or 3 g/10min or more, or 3.2 g/10min or more, or 3.5 g/10min or more, or 3.8 g/10min or more, or 4 g/10min or more, or 4.3 g/10min or more, or 4.5 g/10min or more, or 4.8 g/10min or more, or 5 g/10min or more, and 10.5 g/10min or less, or 10 g/10min or less, or 9.8 g/10min or less, or 9.5 g/10min or less, or 9.2 g/10min or less, or 9 g/10min or less, or 8.8 g/10min or less, or 8.5 g/10 min or less, or 8.2 g/10 min or less, or 8 g/10 min or less, or 7.8 g/10 min or less

Meanwhile, the polypropylene resin may be optimized for melting point (Tm) and crystallization temperature (Tc) along with molecular weight distribution, weight average molecular weight, and melting index.

For example, the polypropylene resin may have a melting point (Tm) of 135°C or higher or 135°C or higher to 155°C and a crystallization temperature (Tc) of 115°C or lower or 95°C or higher to 115°C or lower.

Specifically, the melting point (Tm) of the polypropylene resin may be 136° C. or higher, or 138° C. or higher, or 140° C. or higher, or 142° C. or higher, or 145° C. or higher, or 148° C. or higher, or 150° C. or higher, and 154.5° C. or lower, or 154° C. or lower, or 153.5° C. or lower, or 153° C. or lower, or 152.5° C. or lower, or 152° C. or lower. In particular, in terms of securing excellent mechanical properties such as high strength and excellent heat resistance during fiber manufacturing, the melting point (Tm) of the polypropylene resin may be 135° C. or higher.

In addition, the crystallization temperature (Tc) of the polypropylene resin may be 113.5° C. or less, or 113° C. or less, or 112.5° C. or less, or 112° C. or less, or 111.5° C. or less, or 111° C. or less, or 111.5° C. or less, or 110° C. or less, and 96° C. or more, or 98° C. or more, or 100° C. or more, or 102° C. or more, or 105° C. or more. In particular, in terms of preventing a rapid viscosity increase and spinning defects due to excessive solidification of the spinning filament during fiber manufacturing, the crystallization temperature (Tc) of the polypropylene resin may be 115° C. or less.

In another embodiment of the invention, the melting point (Tm) and crystallization temperature (Tc) of the polypropylene resin can be measured using a differential scanning calorimeter (DSC, for example, device name DSC 2920, manufacturer TA instrument), and the specific measurement method is as described above.

Next, a method for producing a polypropylene resin composition according to one embodiment of the invention includes a step of melt-extruding a mixture comprising a polypropylene resin produced through the above-described polymerization process and a molecular weight regulator under conditions of 120° C. or higher and 300° C. or lower.

Specifically, the polypropylene resin can be produced by mixing a molecular weight regulator and then extruding and pelletizing.

In addition, the molecular weight regulator may be a linear bicyclic organic peroxide compound,

Specifically, the molecular weight regulator may be a bicyclic organic peroxide compound having 4 to 32 carbon atoms, or 6 to 24 carbon atoms, or 8 to 16 carbon atoms.

For example, the molecular weight regulator may be at least one selected from the group consisting of 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane (DHBP, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane), 2,5-di(tert-butylperoxy)-2,5-dimethyl-3-hexyne (DYBP, 2,5-Di(tert-butylperoxy)-2,5-dimethyl-3-hexyne), and di-tert-butyl peroxide (DTBP, Di-tert-butyl peroxide).

In addition, the extrusion and pelletizing process of the mixture including the polypropylene resin and the molecular weight regulator can be performed according to a conventional extrusion method, such as controlling the temperature for melting the mixture composition to a temperature range of 120° C. or higher to 300° C. or lower and using a twin-screw extruder.

In addition, when the pressure is further controlled together with the die temperature, the die pressure may be 20 bar or more, or 30 bar or more, and 50 bar or less, or 35 bar or less. When the pressure is controlled within this range, the shape and properties of the polypropylene resin composition can be more easily implemented.

Meanwhile, the mixture containing the polypropylene resin and the molecular weight regulator may further contain one or more additives, such as an antioxidant, a lubricant, a UV stabilizer, a neutralizer, a dispersant, a weathering agent, an antistatic agent, a UV stabilizer, a slip agent, an antiblocking agent, talc, a nucleating agent, etc. More specifically, the additive may further contain one or more selected from the group consisting of an antioxidant, a lubricant, a UV stabilizer, and a neutralizer. Any such additive may be used without limitation as long as it is a component known to be applicable in the production of a polypropylene resin composition, and thus a specific description of the types and amounts of the additives described above will be omitted.

However, the optimal combination of properties of the polypropylene resin can be achieved by controlling the catalyst and polymerization conditions during the production of the polypropylene resin.

The polypropylene resin composition according to one embodiment of the invention manufactured by the above-described manufacturing method can be particularly useful in the manufacture of spunbond nonwoven fabrics having high strength together with ultra-low basis weight characteristics so that the fibers can be manufactured with high strength while having a narrow molecular weight distribution and high melting index, thereby minimizing the weight when used in diapers, etc.

Polypropylene fibers and spunbond nonwovens

Accordingly, according to another embodiment of the present invention, polypropylene fibers and spunbond nonwoven fabrics comprising the above-described polypropylene resin composition are provided.

For example, the polypropylene fiber according to the present invention may have a tenacity of 6.95 gf/denier or greater as measured according to ASTM D 638.

In addition, the spunbond nonwoven fabric according to the present invention may be made of fibers comprising the polypropylene resin composition described above.

The polypropylene fiber of the present invention and the spunbond nonwoven fabric manufactured using the same can be manufactured by a conventional method, except that the polypropylene resin composition described above is used.

Hereinafter, the operation and effect of the invention will be described in more detail through specific examples of the invention. However, these examples are presented only as examples of the invention, and the scope of the invention's rights is not determined thereby.

[Example]

<Production of metallocene catalyst>

Catalyst manufacturing example 1

Step 1) Preparation of (6-t-butoxyhexyl)dichloromethylsilane

100 mL of t-butoxyhexyl magnesium chloride solution (approximately 0.14 mol, ether) was slowly added dropwise to 100 mL of trichloromethylsilane solution (approximately 0.21 mol, hexane) over 3 hours at -100 °C, and then stirred at room temperature for 3 hours.

After separating the transparent organic layer from the above mixed solution, the separated transparent organic layer was vacuum-dried to remove the excess trichloromethylsilane. As a result, (6-t-butoxyhexyl)dichloromethylsilane in a transparent liquid state was obtained (yield 84%).

¹ H NMR (500 MHz, CDCl ₃ , 7.24 ppm): 0.76 (3H, s), 1.11 (2H, t), 1.18 (9H, s), 1.32-1.55 (8H, m), 3.33 (2H, t) .

Step 2) Preparation of (6-t-butoxyhexyl)(methyl)-bis(2-methyl-4-phenylindenyl)silane

To 77 mL of 2-methyl-4-phenylindene toluene/THF=10/1 solution (34.9 mmol), 15.4 mL of n-butyllithium solution (2.5 M, hexane solvent) was slowly added dropwise at 0 °C, stirred at 80 °C for 1 hour, and then stirred at room temperature for 1 day. Then, 5 g of (6-t-butoxyhexyl)dichloromethylsilane prepared in step 1) above was slowly added dropwise to the mixed solution at -78 °C, stirred for about 10 minutes, and then stirred at 80 °C for 1 hour. Then, water was added to separate the organic layer, purified through a silica column, and dried under vacuum to obtain a sticky yellow oil in a yield of 78% (racemic:meso = 1:1).

¹ H NMR (500 MHz, CDCl ₃ , 7.24 ppm): 0.10 (3H, s), 0.98 (2H, t), 1.25 (9H, s), 1.36-1.50 (8H, m), 1.62 (8H, m) , 2.26(6H, s), 3.34(2H, t), 3.81(2H, s), 6.87(2H, s), 7.25(2H, t), 7.35(2H, t), 7.45(4H, d), 7.53(4H, t), 7.61(4H, d).

Step 3) Preparation of [(6-t-butoxyhexylmethylsilane-diyl)-bis(2-methyl-4-phenylindenyl)]zirconium dichloride

In Step 2), 3.0 mL of n-butyllithium solution (2.5 M in hexane) was slowly added dropwise to 50 mL of (6-t-butoxyhexyl)(methyl)bis(2-methyl-4-phenyl)indenylsilane ether/hexane = 1/1 solution (3.37 mmol) prepared above, at -78 °C, stirred at room temperature for about 2 hours, and then vacuum-dried. Then, the salt was washed with hexane, filtered, and vacuum-dried to obtain a yellow solid. In a glove box, the synthesized ligand salt and bis(N,N'-diphenyl-1,3-propanediamido)dichlorozirconium bis(tetrahydrofuran) [Zr(C ₅ H ₆ NCH ₂ CH ₂ CH ₂ NC ₅ H ₆ )Cl ₂ (C ₄ H ₈ O) ₂ ] were weighed in a Schlenk flask, and ether was slowly added dropwise at -78 ℃, followed by stirring at room temperature for one day. Afterwards, the red reaction solution was separated by filtration, and 4 equivalents of HCl ether solution (1 M) were slowly added dropwise at -78 ℃, followed by stirring at room temperature for 3 hours. This was followed by filtration and vacuum drying to obtain an ansa-metallocene compound as an orange solid in a yield of 85% (racemic:meso = 10:1).

¹ H NMR (500 MHz, C ₆ D ₆ , 7.24 ppm): 1.19 (9H, s), 1.32 (3H, s), 1.48-1.86 (10H, m), 2.25 (6H, s), 3.37 (2H, t), 6.95(2H, s), 7.13(2H, t), 7.36(2H, d), 7.43(6H, t), 7.62(4H, d), 7.67(2H, d)

Step 4) Preparation of supported catalyst

After weighing 3 g of silica in a shrink flask in advance, 52 mmol of methylaluminoxane (MAO) was added and reacted at 90°C for 24 hours. After precipitation, the upper layer was removed and washed twice with toluene. 240 μmol of the ansa-metallocene compound synthesized in step 3) above was dissolved in toluene and reacted at 40°C for 5 hours. After the reaction and precipitation were complete, the upper layer solution was removed, and the remaining reaction product was washed with toluene, then again with hexane, and then vacuum-dried to obtain 5 g of a silica-supported metallocene catalyst in the form of solid particles.

Catalyst manufacturing example 2

Step 1) Preparation of (diethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)silane

2-Methyl-4-tert-butyl-phenylindene (20.0 g) was dissolved in a mixed solvent of toluene and tetrahydrofuran (toluene/THF volume ratio 10/1, 220 mL), and n-butyllithium solution (2.5 M, hexane solvent, 22.2 g) was slowly added dropwise at 0 °C, and the mixture was stirred at room temperature for one day. Then, diethyldichlorosilane (6.2 g) was slowly added dropwise to the mixed solution at -78 °C, stirred for about 10 minutes, and then stirred at room temperature for one day. After that, water was added to separate the organic layer, and the solvent was distilled under reduced pressure to obtain (diethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)silane.

Step 2) Preparation of [(diethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)]zirconium dichloride

In the above step 1, (diethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)silane prepared was dissolved in a mixed solvent of toluene/THF (120 mL) with a volume ratio of 5/1, and then n-butyllithium solution (2.5 M, hexane solvent, 22.2 g) was slowly added dropwise at -78°C, and stirred at room temperature for one day. Zirconium chloride (8.9 g) was diluted in toluene (20 mL) to the reaction solution, and then slowly added dropwise at -78°C, and stirred at room temperature for one day. The solvent in the reaction solution was removed under reduced pressure, dichloromethane was added, filtered, and the filtrate was distilled under reduced pressure to remove it. Recrystallization was performed using toluene and hexane to obtain a high-purity product. rac-[(diethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)]zirconium dichloride (10.1 g, yield: 34%, rac:meso molar ratio 20:1) was obtained.

Step 3) Preparation of supported catalyst

In a 3 L reactor, 100 g of silica and 10 wt% of methylaluminoxane (670 g) were added and reacted at 90°C for 24 hours. After precipitation, the upper layer was removed and washed twice with toluene. The ansa-metallocene compound rac-[(diethylsilane-diyl)-bis((2-methyl-4-tert-butyl-phenylindenyl)]zirconium dichloride (5.8 g), prepared in step 2, was diluted in toluene and added to the reactor, followed by reaction at 70°C for 5 hours. After the reaction and precipitation were complete, the upper layer solution was removed, and the remaining reaction product was washed with toluene, then again with hexane, and dried under vacuum to obtain 150 g of a silica-supported metallocene catalyst in the form of solid particles.

Catalyst Comparative Manufacturing Example 1

Step 1) Preparation of ligand compound (2-Methyl-4-(3’,5’-ditertbutylphenyl)Indacenyl) dimethyl (2,3,4,5-tetramethyl cyclopentadienyl) silane

2,3,4,5-Tetramethylcyclopentadiene (TMCP) was dissolved in tetrahydrofuran (THF), and n-BuLi (1.05 eq) was slowly added dropwise at -25 ℃, and the mixture was stirred at room temperature for 3 hours. After that, dichloro dimethyl silane (1.05 eq) was added at -10 ℃, and the mixture was stirred at room temperature overnight. In another reactor, 2-Methyl-4-(3',5'-di(tert-butyl)phenyl) indacene (1 eq) was dissolved in a mixed solvent of toluene/tetrahydrofuran (volume ratio 3/2, 0.5 M). n-BuLi (1.05 eq) was slowly added dropwise at -25 ℃, and the mixture was stirred at room temperature for 3 h. After that, CuCN (2 mol%) was added, stirred for 30 min, and then the first reactant, mono-Si solution, was added. The mixture was stirred overnight at room temperature, worked up with water, and dried to obtain the ligand.

Step 2) Preparation of transition metal compound Dimethylsilanediyl(2-Methyl-4-(3’,5’-ditertbutylphenyl)Indacenyl)(2,3,4,5-tetramethyl cyclopentadienyl) zirconium dichloride

The ligand prepared above was dissolved in toluene/Ether (volume ratio 2/1, 0.53 M), n-BuLi (2.05 eq) was added at -25 ℃, and stirred at room temperature for 5 hours. In a separate flask, a slurry was prepared by mixing ZrCl ₄ (1 eq) in toluene (0.17 M), and added to the ligand solution, followed by stirring at room temperature overnight. Upon completion of the reaction, the solvent was dried in vacuum, dichloromethane was re-introduced, and LiCl was removed through a filter, etc., the filtrate was dried in vacuum, and dichloromethane/hexane was added to recrystallize at room temperature. Thereafter, the generated solid was filtered and dried in vacuum to obtain the title metallocene compound.

For the transition metal compounds obtained in this manner, NMR data were measured using Bruker AVANCE III HD 500 MHz NMR/ PABBO (1H/19F/Broad band) probe: 1H, solvent: CDCl ₃ .

¹ H-NMR (500 MHz, CDCl ₃ ): 7.73 (s, 2H), 7.56 (s, 1H), 7.42 (s, 1H), 6.36 (s, 1H), 2.85-2.80 (m, 4H), 2.12 (s, 6H), 1.95 (m, 2H), 1.79 (s, 9H), 1.31 (s, 18H), 1.00 (s, 6H) ppm

Step 3) Preparation of supported catalyst

In a 3 L reactor, 100 g of silica and 10 wt% of methylaluminoxane (670 g) were added and reacted at 90°C for 24 hours. After precipitation, the upper layer was removed and washed twice with toluene. The transition metal compound Dimethylsilanediyl(2-Methyl-4-(3',5'-ditertbutylphenyl)Indacenyl)(2,3,4,5-tetramethyl cyclopentadienyl) zirconium dichloride (5.8 g), prepared in step 2, was diluted in toluene and added to the reactor, followed by reaction at 70°C for 5 hours. After the reaction and precipitation were complete, the upper layer solution was removed, and the remaining reaction product was washed with toluene, then again with hexane, and dried under vacuum to obtain 150 g of a silica-supported metallocene catalyst in the form of solid particles.

<Manufacture of homopolypropylene>

Manufacturing example 1

Bulk-slurry polymerization of propylene was carried out using two continuous loop reactors in the presence of a silica-supported metallocene catalyst prepared according to Catalyst Preparation Example 1.

Specifically, triethylaluminum (TEAL) and hydrogen gas were each introduced using a pump, and the silica-supported metallocene catalyst was used in the form of a mud catalyst mixed with oil and grease so as to have a content of 20 wt%. Here, the triethylaluminum (TEAL) introduction amount was 50 ppm in weight value (ppm) based on the total weight of the monomer for forming homo-polypropylene, and the hydrogen introduction amount was 140 ppm in molar ratio value (ppm) based on the total mole number of the monomer for forming homo-polypropylene. In addition, the temperature of the reactor was 70 ℃, and the hourly production amount was approximately 40 kg/h. At this time, the polymerization pressure was maintained at 35 kg/cm ² , and propylene was introduced at 40 kg/h.

The results of property measurement for the homopolypropylene of Manufacturing Example 1 obtained through the bulk-slurry polymerization process of propylene described above are as shown in Table 1 below.

Manufacturing example 2

Bulk-slurry polymerization of propylene was performed in the same manner as in Manufacturing Example 1, but the hydrogen input amount was changed to 50 ppm, thereby producing homopolypropylene of Manufacturing Example 2.

Manufacturing example 3

Bulk-slurry polymerization of propylene was performed in the same manner as in Manufacturing Example 1, but the amount of hydrogen input was changed to 230 ppm in the presence of a silica-supported metallocene catalyst manufactured according to Catalyst Manufacturing Example 2, thereby manufacturing homopolypropylene of Manufacturing Example 3.

Manufacturing example 4

Bulk-slurry polymerization of propylene was performed in the same manner as in Manufacturing Example 3, but the hydrogen input amount was changed to 100 ppm, thereby producing homopolypropylene of Manufacturing Example 4.

Comparative manufacturing example 1

Bulk-slurry polymerization of propylene was performed in the same manner as in Manufacturing Example 1, but the hydrogen input amount was changed to 260 ppm, thereby manufacturing homopolypropylene of Comparative Manufacturing Example 1.

Comparative manufacturing example 2

Bulk-slurry polymerization of propylene was performed in the same manner as in Manufacturing Example 3, but the hydrogen input amount was changed to 50 ppm, thereby manufacturing homopolypropylene of Comparative Manufacturing Example 2.

Comparative manufacturing example 3

H5300™ (manufactured by LG Chemical Co., Ltd.), a commercially available homopolypropylene manufactured using a Ziegler-Natta catalyst (Z/N), was prepared as the homopolypropylene of Comparative Manufacturing Example 3.

Comparative manufacturing example 4

Bulk-slurry polymerization of propylene was performed in the same manner as in Comparative Manufacturing Example 1, but the hydrogen input amount was changed to 380 ppm, thereby producing homopolypropylene of Comparative Manufacturing Example 4.

Comparative manufacturing example 5

Bulk-slurry polymerization of propylene was performed in the same manner as in Manufacturing Example 1, but the polymerization process was performed in the presence of a silica-supported metallocene catalyst manufactured according to the catalyst comparative Manufacturing Example 1, and the hydrogen input amount was changed to 400 ppm, thereby manufacturing homopolypropylene of Comparative Manufacturing Example 5.

<Test Example 1: Evaluation of properties of homo polypropylene>

The physical properties of the homopolypropylene of Manufacturing Examples 1 to 4 and Comparative Manufacturing Examples 1 to 5 were evaluated using the following method, and the measurement results are shown in Table 1 below.

(1) Melt index

The melt index (MI _2.16 ) was measured at 230°C under a load of 2.16 kg according to the American Society for Testing and Materials standard ASTM D 1238, and was expressed as the weight (g) of the polymer melted for 10 minutes.

(2) Weight average molecular weight (Mw) and molecular weight distribution (MWD, polydispersity index)

The weight average molecular weight (Mw) and number average molecular weight (Mn) of homopolypropylene according to the manufacturing examples and comparative manufacturing examples were measured using gel permeation chromatography (GPC, manufactured by Water Corp.), and the molecular weight distribution (MWD, Mw/Mn) was calculated by dividing the weight average molecular weight by the number average molecular weight.

Specifically, a Waters PL-GPC220 gel permeation chromatography (GPC) device was used, and a Polymer Laboratories PLgel MIX-B 300 mm column was used. The measurement temperature was 160°C, 1,2,4-trichlorobenzene was used as a solvent, and the flow rate was 1 mL/min. The homopolypropylene samples according to the Manufacturing Examples and Comparative Manufacturing Examples were each pretreated by dissolving in trichlorobenzene (1,2,4-trichlorobenzene) containing 0.0125% butylated hydroxytoluene (BHT) at 160°C for 10 hours, preparing a concentration of 10 mg/10 mL, and then supplying in an amount of 200 μL. The values of Mw and Mn were derived using a calibration curve formed using polystyrene standard specimens. The weight-average molecular weights of the polystyrene standard specimens were 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, nine types.

(3) Melting point (Tm) and crystallization temperature (Tc)

The melting point (Tm) and crystallization temperature (Tc) of homo polypropylene according to the Manufacturing Examples and Comparative Manufacturing Examples were measured using a differential scanning calorimeter (DSC, device name: DSC 2920, manufacturer: TA instrument). Specifically, the homo polypropylene was heated to 200 ℃, maintained at that temperature for 5 minutes, then decreased to 30 ℃, and the temperature was increased again. The top of the DSC (Differential Scanning Calorimeter, manufactured by TA Instrument) curve was measured as the melting point (Tm), and when the temperature was decreased again to 30 ℃, the top of the curve was measured as the crystallization temperature (Tc). At this time, the speed of the temperature increase and decrease was 10 ℃/min, and the melting point (Tm) and crystallization temperature (Tc) were used the results measured in the section where the second temperature increased and decreased.

The results of measuring the melting index (MI _2.16 ), and the weight average molecular weight (Mw), molecular weight distribution (MWD, Mw/Mn), melting point (Tm), and crystallization temperature (Tc) of the homopolypropylene of Manufacturing Examples 1 to 4 and Comparative Manufacturing Examples 1 to 5 are as shown in Table 1 below.

Manufacturing example
1 Manufacturing example
2 Manufacturing example
3 Manufacturing example
4 comparison
Manufacturing example
1 comparison
Manufacturing example
2 comparison
Manufacturing example
3 comparison
Manufacturing example
4 comparison
Manufacturing example
5 MI (2.16kg, g/10min) 7 3 9 3 12 1 3 25 25 Mw (x1000 g/mol) 280 349 250 340 210 375 340 209 201 MWD (Mw/Mn) 2.8 2.8 2.4 2.4 2.8 2.4 3.8 2.8 2.4 Melting point
(Tm, ℃) 151 151 151 151 151 154 160 151 156 Crystallization temperature (Tc, ℃) 109 109 109 109 109 110 109 114 118

<Production of polypropylene resin composition>

Example 1

In the above manufacturing example 1, the homo polypropylene, 500 ppm of the phenol-based antioxidant Irganox™ 1010 (manufactured by BASF) and 1000 ppm of the phosphorus-based antioxidant Irgafos™ 168 (manufactured by BASF) as antioxidants, and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexan (DHBP, 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexan, (CH ₃ ) ₃ COOC(CH ₃ ) ₂ CH ₂ -CH ₂ (CH ₃ ) ₂ COOC(CH ₃ ) ₃ ] as a molecular weight regulator were mixed in the contents shown in Table 2 below. For the mixture thus obtained, a 25 mm twin-screw extruder (manufactured by JSW) was used, and the temperatures in the feeding, mixing, and compression sections were set to 230 ℃, 270 ℃, A masterbatch was prepared by reaction extrusion at 215°C for a residence time of 25 seconds, and then pelletized to prepare a pellet-shaped polypropylene resin composition (average pellet diameter: 4 mm). Meanwhile, the input amounts of the antioxidant and molecular weight regulator are weight values (ppm) based on the total weight of the homo polypropylene resin composition.

Examples 2 to 8

As described in Table 2 below, pellet-shaped polypropylene resin compositions of Examples 2 to 8 were each manufactured in the same manner as in Example 1, except that the type of homopolypropylene and the content of the molecular weight regulator were changed.

Comparative examples 1 to 6

As described in Table 2 below, pellet-shaped polypropylene resin compositions of Comparative Examples 1 to 6 were each manufactured in the same manner as in Example 1, except that the type of homopolypropylene and the content of the molecular weight regulator were changed.

Comparative Example 7

MR2001™ (manufactured by Total) commercially available was used as a pellet-shaped polypropylene resin composition containing homopolypropylene manufactured by a metallocene catalyst (commercial product 1, MR2001 by Total).

Comparative Example 8

As a pellet-shaped polypropylene resin composition containing homopolypropylene manufactured with a metallocene catalyst, commercially available MH7700S™ (manufactured by LG Chemical Co., Ltd.) was used (commercial product 2, LG Chemical MH7700S).

Comparative Example 9

As described in Table 2 below, a pellet-shaped polypropylene resin composition of Comparative Example 9 was manufactured in the same manner as in Example 1, except that the homopolypropylene of Comparative Manufacturing Example 4 was used alone and no molecular weight regulator was used.

Comparative Example 10

As described in Table 2 below, a pellet-shaped polypropylene resin composition of Comparative Example 10 was manufactured in the same manner as in Example 1, except that the homopolypropylene of Comparative Manufacturing Example 5 was used alone and no molecular weight regulator was used.

Comparative Example 11

As described in Table 2 below, instead of homopolypropylene as the polypropylene resin, a propylene-ethylene random copolymer, a low-crystallization polypropylene resin, and a propylene copolymer mixture including a polyethylene resin were used, and the content of the molecular weight regulator was changed to 400 ppm, and the same method as in Example 1 was performed to produce a pellet-shaped polypropylene resin composition of Comparative Example 11.

Specifically, the propylene copolymer mixture includes 85 parts by weight of a propylene-ethylene random copolymer, 5 parts by weight of a low-crystallization polypropylene resin, and 10 parts by weight of a polyethylene resin, based on 100 parts by weight of the total weight of the entire mixture. Here, the propylene-ethylene random copolymer used was a product (manufactured by Lotte Chemical) having an ethylene content of 5 mol%, a melting index (measured at 230° C., under a load of 2.16 kg) of 28 g/10 min, and a molecular weight distribution (Mw/Mn) of 3.5. The above low-crystallinity polypropylene resin is a commercial low-crystallinity polypropylene resin manufactured using a metallocene catalyst, and has a [mmmm] value of 40 to 50%, a melt index (measured at 230°C, under a load of 2.16 kg) of 50 g/10 min, and a molecular weight distribution (Mw/Mn) of 2.5 (manufactured by Idemitsu). The above polyethylene resin is an ethylene/1-butene copolymer, and has a 1-butene content of 3 mol%, a density of 0.960 g/cm3, a melt index (measured at 190°C, under a load of 2.16 kg) of 18 g/10 min, and a molecular weight distribution (Mw/Mn) of 5.0 (manufactured by Lotte Chemical).

<Test Example 2: Evaluation of physical properties of polypropylene resin composition>

For the polypropylene resin compositions of Examples 1 to 8 and Comparative Examples 1 to 11, the melting point (Tm) and crystallization temperature (Tc), melting index (MI _2.16 ), weight average molecular weight (Mw), and molecular weight distribution (MWD, Mw/Mn) of the polypropylene resin compositions were measured using the same method as in Test Example 1, and the results are shown in Table 2 below.

polypropylene resin Molecular weight
Regulator
Content
(ppm) Melting point
(Tm, ℃) crystallization
temperature
(Tc, ℃) MI
(2.16kg, g/10min) Mw
(x1000 g/mol) MWD
(Mw/Mn) homo
Polypropylene Propylene copolymer
mixture Example 1 Manufacturing example 1 - 350 151 109 25 201 2.33 Example 2 Manufacturing example 1 - 570 151 109 34 181 2.26 Example 3 Manufacturing example 2 - 700 151 109 25 190 2.28 Example 4 Manufacturing example 2 - 900 151 109 34 177 2.22 Example 5 Manufacturing example 3 - 225 151 109 25 189 2.04 Example 6 Manufacturing example 3 - 390 151 109 34 175 1.95 Example 7 Manufacturing example 4 - 650 151 109 25 182 1.93 Example 8 Manufacturing example 4 - 900 151 109 34 170 1.85 Comparative Example 1 Manufacturing example 1 - 200 151 109 16 230 2.57 Comparative Example 2 Manufacturing example 1 - 950 151 109 55 149 2.19 Comparative Example 3 Comparative manufacturing example
1 - 110 151 109 25 209 2.6 Comparative Example 4 Comparative manufacturing example
2 - 1300 154 110 25 176 1.6 Comparative Example 5 Comparative manufacturing example
3 - 750 160 109 25 209 2.7 Comparative Example 6 Comparative manufacturing example
3 - 980 160 109 34 186 2.6 Comparative Example 7 -
(Commercial product 1) -
(Commercial product 1) -
(Commercial product 1) 154 111 25 188 2.4 Comparative Example 8 -
(Commercial product 2) -
(Commercial product 2) -
(Commercial product 2) 154 110 25 190 2.4 Comparative Example 9 Comparative manufacturing example
4 - 0 151 114 25 209.5 2.8 Comparative Example 10 Comparative manufacturing example
5 - 0 156 118 25 201 2.4 Comparative Example 11 - Mixture containing propylene-ethylene random copolymer 400 151 109 Over 28 less than 150 2.8 or more

As shown in Table 2 above, it can be seen that the polypropylene resin compositions of Examples 1 to 8 can be implemented in an optimized range in which the molecular weight distribution (MWD, Mw/Mn) is 1.85 to 2.33, the melting index (MI _2.16 ) is 25 to 34 g/10 min, the melting point (Tm) is 135 ℃ or higher, and the crystallization temperature (Tc) is 115 ℃ or lower.

However, the polypropylene resin compositions of Comparative Examples 1 to 11 had a wide molecular weight distribution (MWD, Mw/Mn), too high or low melting index (MI _2.16 ), or non-optimized melting point (Tm) or crystallization temperature (Tc). In particular, Comparative Example 1 had a wide molecular weight distribution (MWD, Mw/Mn) of 2.57, and also had a too low melting index (MI _2.16 ) of 16 g/10 min. In Comparative Example 2, the molecular weight distribution (MWD, Mw/Mn) was narrowed to 2.19 by increasing the amount of molecular weight regulator used, but the melting index (MI _2.16 ) increased to 55 g/10 min, and the weight average molecular weight also significantly decreased to 149,000 g/mol. The polypropylene resin compositions of Comparative Examples 3 to 9 exhibited melting indices (MI _2.16 ) of 25 g/10 min and 34 g/10 min, but in the case of Comparative Example 4, the molecular weight distribution (MWD, Mw/Mn) was too narrow at 1.6, and in the cases of Comparative Examples 3 and 5 to 9, the molecular weight distribution (MWD, Mw/Mn) was too wide at 2.4 to 2.8. In particular, in the case of Comparative Example 9, the melting index was implemented as 25 g/10 min during the manufacture of the polypropylene resin, but the molecular weight distribution (MWD, Mw/Mn) was maintained wide at 2.8 without using a molecular weight regulator. Meanwhile, the polypropylene resin composition of Comparative Example 10, when manufacturing the polypropylene resin, implemented a melting index of 25 g/10 min and a molecular weight distribution (MWD, Mw/Mn) of 2.4, but the crystallization temperature (Tc) was too high at 118 ℃. In addition, in the case of Comparative Example 11, even though a molecular weight regulator was used, the molecular weight distribution (MWD, Mw/Mn) exceeded 2.8 and was too wide, and the weight average molecular weight was also significantly reduced to less than 150,000 g/mol.

<Test Example 3: Manufacturing and property evaluation of polypropylene fiber>

Fibers were manufactured using the polypropylene resin compositions of the above examples and comparative examples, and the strength and elongation of the manufactured fibers were evaluated.

Manufacturing of textiles

The polypropylene resin compositions manufactured in the above examples and comparative examples were spun using a spin-draw spinner.

Specifically, a polypropylene resin composition was injected into a filament yarn, and the molten resin composition was discharged from a die into a filament, and then cooled and solidified by a cooling air stream. The resulting untwisted yarn was stretched by passing it through a first roller and a second roller, and a polypropylene fiber having a fineness of 2 denier (DPF, denier per filament) was manufactured. For reference, denier is an international unit used to express the thickness of yarn, and 1 denier is defined as 1 g of unit weight at a standard length of 9,000 m.

In addition, the above-described radiation process was performed using a nozzle diameter of 0.25 pi/24 Fila Die, and the gear pump speed during the radiation was 19 rpm, the discharge amount per hole was 2.5 g/min/hole, the radiation temperature (extrusion temperature) was 230°C, the pipe temperature was 220°C, the die temperature was 210°C, the cooling temperature (Quenching Air temperature) was approximately 20°C, the first roller temperature was 60°C, the roller speed was 1000 m/min, the second roller temperature was 120°C, and the roller speed was 3000 m/min.

Evaluation of fiber properties

The physical properties of polypropylene fibers manufactured using the polypropylene resin compositions manufactured in the examples and comparative examples were evaluated using the following method, and the results are shown in Table 3 below.

(1) Tenacity of fiber (unit: gf/denier)

Strength refers to the breaking point strength of the yarn and was measured according to ASTM D 638. The test speed was 200 mm/min, and six measurements were taken for each specimen, and the average was taken. For reference, denier is an international unit used to indicate the thickness of yarn, and 1 denier is 1 g of unit weight in a standard length of 9,000 m.

(2) Processability of filament

The processability of the filament was evaluated according to the following criteria depending on whether or not single fibers occurred during filament manufacturing.

Specifically, in evaluating the fiber processability, if there was no fiber breakage during drawing, it was marked as “good,” and if fiber breakage occurred during drawing, it was marked as “poor.”

Extension fee Strength (gf/denier) Processability Example 1 3.0 7.10 Good Example 2 3.0 7.03 Good Example 3 3.0 7.15 Good Example 4 3.0 7.09 Good Example 5 3.0 7.25 Good Example 6 3.0 7.19 Good Example 7 3.0 7.36 Good Example 8 3.0 7.30 Good Comparative Example 1 3.0 - error Comparative Example 2 3.0 6.05 Good Comparative Example 3 3.0 - error Comparative Example 4 3.0 -
(non-radioable) -
(non-radioable) Comparative Example 5 3.0 - error Comparative Example 6 3.0 - error Comparative Example 7 3.0 6.80 Good Comparative Example 8 3.0 6.78 Good Comparative Example 9 3.0 - error Comparative Example 10 3.0 - error Comparative Example 11 3.0 - error

Referring to Table 3 above, the polypropylene resin compositions according to Examples 1 to 8 of the present invention are polypropylene resins manufactured in the presence of a metallocene compound having a specific structure, and by using a propylene homopolymer and a molecular weight regulator in a predetermined range, the compositions optimize the melt index (MI _2.16 ), melting point (Tm), and crystallization temperature (Tc) along with a narrow molecular weight distribution (MWD, Mw/Mn), thereby showing excellent elongation stability and orientation effect during fiber spinning compared to Comparative Examples 1 to 11, thereby realizing stable processability during spinning while enabling improvement of strength, and it can be seen that it is very advantageous in manufacturing a spunbond nonwoven fabric having high strength together with ultra-low basis weight characteristics so that the weight can be minimized when used in diapers, etc.

On the other hand, the polypropylene resin compositions of Comparative Examples 1 to 11 have a wide molecular weight distribution (MWD, Mw/Mn) and the melt index (MI _2.16 ), melting point (Tm), and crystallization temperature (Tc) are not all optimized, so it is difficult to manufacture high-strength fibers suitable for ultra-low basis weight, high-strength nonwoven fabrics with stable processability without the risk of fiber singlet during spinning. In particular, Comparative Example 1 showed poor spinning processability due to the wide molecular weight distribution and too low melt index, which caused fiber singlet during stretching. In the case of Comparative Example 2, the molecular weight distribution was optimized so that fiber singlet did not occur during stretching, but the melt index increased significantly and the fiber strength decreased to 6.05 gf/denier, so it was difficult to secure fibers suitable for ultra-low basis weight, high-strength nonwoven fabrics. The polypropylene resin compositions of Comparative Examples 3 to 11 had their melt index adjusted to a predetermined range, but their molecular weight distributions were too narrow or too broad, were not optimized, and had high crystallization temperatures, making it difficult to manufacture high-strength fibers suitable for ultra-low basis weight, high-tenacity nonwoven fabrics without spinning defects. In particular, the polypropylene resin compositions of Comparative Examples 3, 5, 6, and 9 exhibited spinning defects due to single fibers occurring during stretching due to their broad molecular weight distributions. In the case of Comparative Example 4, spinning was impossible due to its too narrow molecular weight distribution. The polypropylene resin compositions of Comparative Examples 7 and 8 had their melt index adjusted and their molecular weight distributions lowered to a predetermined range so that single fibers did not occur during stretching, but their fiber strengths were only 6.80 gf/denier and 6.78 gf/denier, making them unsuitable for manufacturing ultra-low basis weight, high-tenacity nonwoven fabrics. The polypropylene resin composition of Comparative Example 10 exhibited poor spinning properties due to fiber breakage during drawing caused by a rapid increase in viscosity due to excessive solidification of fiber filaments caused by a high crystallization temperature. The polypropylene resin composition of Comparative Example 11 exhibited poor spinning properties due to fiber breakage during drawing caused by a low viscosity caused by a high melting index and a wide molecular weight distribution.

As described above, the polypropylene resin composition according to the present invention uses a polypropylene resin manufactured in the presence of a metallocene compound having a specific structure and a molecular weight regulator within a predetermined range, thereby optimizing the melt index, melting point, and crystallization temperature together with a narrow molecular weight distribution, thereby enabling stable processability during spinning while improving strength, and effectively manufacturing a polypropylene fiber suitable for an ultra-low basis weight, high-strength nonwoven fabric so that the weight can be minimized when used in diapers, etc.

Claims (20)

The molecular weight distribution (Mw/Mn) is 1.7 or more and 2.35 or less,
The melting index (MI _2.16 , melting index measured at 230 ℃, 2.16 kg load) is 18 g/10 min or more and 36 g/10 min or less,
The melting point (Tm) is 135 ℃ or higher,
Having a crystallization temperature (Tc) of 115 ℃ or less,
Polypropylene resin composition.
In the first paragraph,
The above polypropylene resin composition has a molecular weight distribution (Mw/Mn) of 1.85 or more and 2.33 or less.
Polypropylene resin composition.
In the first paragraph,
The above polypropylene resin composition has a weight average molecular weight of 150,000 g/mol or more.
Polypropylene resin composition.
In the first paragraph,
The above polypropylene resin composition has a melting index (MI _2.16 , melting index measured at 230°C, 2.16 kg load) of 25 g/10 min or more and 34 g/10 min or less.
Polypropylene resin composition.
In the first paragraph,
The above polypropylene resin composition has a melting point (Tm) of 135°C or more and 155°C or less.
Polypropylene resin composition.
In the first paragraph,
The above polypropylene resin composition has a crystallization temperature (Tc) of 95 ℃ or more and 115 ℃ or less.
Polypropylene resin composition.
In the first paragraph,
The above polypropylene resin composition comprises a propylene homopolymer.
Polypropylene resin composition.
A step of producing a polypropylene resin by polymerizing a propylene monomer in the presence of a catalyst composition comprising at least one metallocene compound represented by the following chemical formula 1 and hydrogen gas; and
Comprising a step of melt extruding a mixture containing the polypropylene resin and a molecular weight regulator under conditions of 120° C. or higher and 300° C. or lower,
The above molecular weight regulator is included in an amount of 210 ppm to 940 ppm based on the weight of the polypropylene resin.
Method for producing a polypropylene resin composition according to Article 1:
[Chemical Formula 1]

In the above chemical formula 1,
A is carbon, silicon or germanium,
M is zirconium, or hafnium,
X ₁ and X ₂ are each independently a halogen,
R ₁ and R ₅ are each independently C _6-20 aryl substituted with C _1-20 alkyl,
R ₂ to R ₄ and R ₆ to R ₈ are each independently hydrogen, halogen, C _1-20 alkyl, C _2-20 alkenyl, C _1-20 alkylsilyl, C _1-20 silylalkyl, C _1-20 alkoxysilyl, C _1-20 ether, C _1-20 silylether, C _1-20 alkoxy, C _6-20 aryl, C _7-20 alkylaryl, or C _7-20 arylalkyl,
R ₉ is C _1-20 alkyl which is unsubstituted or substituted with C _1-20 alkoxy,
R ₁₀ is C _1-20 alkyl or C _2-20 alkenyl.
In Article 8,
R ₁ and R ₅ are phenyl substituted with tert-butyl,
A method for producing a polypropylene resin composition.
In Article 8,
R ₉ is 6-tert-butoxy-hexyl and R ₁₀ is methyl, or
R ₉ and R ₁₀ are both ethyl,
A method for producing a polypropylene resin composition.
In Article 8,
The above polypropylene resin is a propylene homopolymer,
A method for producing a polypropylene resin composition.
In Article 8,
The above polypropylene resin has a molecular weight distribution (Mw/Mn) of 2.0 or more and 3.0 or less.
A method for producing a polypropylene resin composition.
In Article 8,
The above polypropylene resin has a melting index (MI _2.16 , melting index measured at 230°C, 2.16 kg load) of 2 g/10 min or more and 11 g/10 min or less.
Method for producing polypropylene resin composition
In Article 8,
The above polypropylene resin has a melting point (Tm) of 135°C or higher and a crystallization temperature (Tc) of 115°C or lower.
A method for producing a polypropylene resin composition.
In Article 8,
The above molecular weight regulator is a linear bicyclic organic peroxide compound,
A method for producing a polypropylene resin composition.
In Article 8,
The above molecular weight regulator is at least one selected from the group consisting of 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-di(tert-butylperoxy)-2,5-dimethyl-3-hexyne, and di-tert-butyl peroxide.
A method for producing a polypropylene resin composition.
In Article 8,
The above mixture further comprises at least one selected from the group consisting of an antioxidant, an anti-oxidant, an ultraviolet stabilizer, and a neutralizer.
A method for producing a polypropylene resin composition.
A polypropylene fiber comprising a polypropylene resin composition according to claim 1.
In Article 18,
A tenacity of 6.95 gf/denier or greater as measured according to ASTM D 638.
Polypropylene fiber.
A spunbond nonwoven fabric comprising polypropylene fibers according to claim 18.