Polypropylene fiber and method for manufacturing the same

Abstract

To provide a fiber capable of being formed by high-speed spinning, having both high elastic modulus and tensile elongation, and a manufacturing method for the same.SOLUTION: The fiber is formed of a propylene-based polymer composition containing 1-15 pts.mass of a propylene-based polymer (A) and 85-99 pts.mass of a propylene-based polymer (B) (where a sum of the polymer (A) and the polymer (B) is 100 pts.mass). The temperature of the propylene-based polymer (A) is 135°C. A content of a propylene-based polymer (a1), having an intrinsic viscosity [η] measured in a tetralin solvent of 10-12dl / g, is 20-50 mass%, and the content of a propylene-based polymer (a2), having the intrinsic viscosity [η] measured under the above condition of 0.5-3dl / g, is 50-80 mass% [where a total amount of the propylene-based polymer (a1) and the propylene-based polymer (a2) is 100 mass%]. The temperature of the propylene-based polymer (B) is 230°C. A melt flow rate measured at a load of 2.16 kg is 15 g / 10 min to 80 g / 10 min, and (Mw / Mn) is 5.0 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to polypropylene fibers and a method for producing the same. [Background technology]

[0002] Propylene polymers are widely used as materials for various molded products, and the required properties vary depending on the molding method and application. For example, films made from propylene polymers are widely used as packaging films for food and general merchandise, as well as as raw materials for fibers, taking advantage of their excellent mechanical properties such as rigidity and optical properties such as gloss. For example, Patent Document 1 discloses a polyolefin composition comprising (A) 100 parts by weight of a crystalline isotactic propylene polymer resin having a molecular weight distribution (Mn / Mw) of less than 3, a low percentage of reverse-inserted propylene units based on 2,1 insertion of propylene monomers in total propylene insertions, i.e., a percentage of 2,1 insertions, and a melt flow rate (MFR) of 20 to 60 g / 10 min; and (B) 0.1 to 1 part by weight of a high molecular weight propylene polymer having a melt strength of 5 to 40 cN; and a fiber prepared using this composition. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Special Publication No. 2008-523231 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Conventionally, there has been a trade-off relationship between the modulus of elasticity and elongation of polypropylene fibers, making it difficult to improve both simultaneously. While the fibers prepared using the composition disclosed in Patent Document 1 exhibit a good balance between tenacity (strength) and elongation at the breaking point, no consideration has been given to improving the modulus of elasticity.

[0005] One embodiment of the present invention aims to solve the problem of providing fibers and composite spun fibers that can be spun at high speed and have both high elastic modulus and tensile elongation. Another embodiment of the present invention aims to solve the problem of providing a method for manufacturing fibers that can be spun at high speed and have both high elastic modulus and tensile elongation. [Means for solving the problem]

[0006] The means for solving the above problems include the following embodiments. <1> Fibers comprising a propylene polymer composition containing 1 to 15 parts by mass of the following propylene polymer (A) and 85 to 99 parts by mass of propylene polymer (B) (the total of polymer (A) and polymer (B) being 100 parts by mass); Propylene polymer (A): comprising a propylene polymer (a1) having an intrinsic viscosity [η] measured at 135°C in tetralin solvent in the range of 10 to 12 dl / g, and a propylene polymer (a2) having an intrinsic viscosity [η] measured at 135°C in tetralin solvent in the range of 0.5 to 3 dl / g, wherein the content of the propylene polymer (a1) is in the range of 20 to 50% by mass, and the content of the propylene polymer (a2) is in the range of 50 to 80% by mass [provided that the total amount of the propylene polymer (a1) and the propylene polymer (a2) is 100% by mass]; Propylene polymer (B): The melt flow rate measured at 230°C and a load of 2.16 kg is 15 g / 10 min to 80 g / 10 min, and the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is 5.0 or less. <2> The ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the propylene polymer (A) is 20 or more. <1> The fibers described above. <3> In the measurement of the dynamic viscoelasticity of the propylene-based polymer composition at 210°C, the ratio of the storage modulus G'(100) at an angular frequency of 100 rad / s to the storage modulus G'(10) at an angular frequency of 10 rad / s (G'(100) / G'(10)) is 4.5 to 10.0, and the ratio of the storage modulus G'(0.1) at an angular frequency of 0.1 rad / s to the storage modulus G'(0.01) at an angular frequency of 0.01 rad / s (G'(0.1) / G'(0.01)) is 3 to 20. <1> or <2> The fibers described above. <4> The melt flow rate of the propylene polymer composition, measured at 230°C and a load of 2.16 kg, is between 10 and 60. <1> ~ <3> The fiber listed in any one of the following. <5> <1> ~ <4> A composite spun fiber containing any one of the fibers described in one of the following. <6> <1> ~ <4> A method for manufacturing fibers as described in any one of the following: A method for producing fibers, comprising the step of melt-spinning the propylene polymer composition. [Effects of the Invention]

[0007] According to one embodiment of the present invention, fibers and composite spun fibers with high elastic modulus and tensile elongation are provided. Furthermore, according to one embodiment of the present invention, a method for producing fibers with high elastic modulus and tensile elongation is provided. [Modes for carrying out the invention]

[0008] The contents of the present invention will be described in detail below. The description of the constituent elements described below may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, the "~" symbol indicating a numerical range is used to mean that the numbers before and after it are included as the lower and upper limits, respectively. In this specification, the "~" symbol indicating a numerical range means that the units listed before or after it refer to the same unit unless otherwise specified. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. Hereinafter, the present invention will be described in detail. In this specification, high-speed spinning means that the spinning speed is 4000 m / min or more.

[0009] (Fiber) The fiber according to the present invention is composed of a propylene-based polymer composition containing 1 to 15 parts by mass of the following propylene-based polymer (A) and 85 to 99 parts by mass of the following propylene-based polymer (B) (the total of polymer (A) and polymer (B) is 100 parts by mass). Propylene-based polymer (A): It includes a propylene-based polymer (a1) having an intrinsic viscosity [η] measured in a tetralin solvent at 135°C in the range of 10 to 12 dl / g and a propylene-based polymer (a2) having an intrinsic viscosity [η] measured in a tetralin solvent at 135°C in the range of 0.5 to 3 dl / g. The content of the propylene-based polymer (a1) is in the range of 20 to 50% by mass, and the content of the propylene-based polymer (a2) is in the range of 50 to 80% by mass [however, the total amount of the propylene-based polymer (a1) and the propylene-based polymer (a2) is taken as 100% by mass]. Propylene-based polymer (B): The melt flow rate measured at 230°C under a load of 2.16 kg is 15 g / 10 min to 80 g / 10 min, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 5.0 or less.

[0010] Conventionally, the elastic modulus and elongation rate of polypropylene fibers have a trade-off relationship, and it has been difficult to improve both the elastic modulus and the elongation rate. As a result of intensive studies by the present inventors, it has been found that the fiber having the above configuration enables high-speed spinning molding and has both a high elastic modulus and a high tensile elongation rate. Although the reason is not clear, it is presumed as follows. In the propylene-based polymer composition according to the present invention, by containing an appropriate amount of a propylene-based polymer (A) having a higher molecular weight than the propylene-based polymer (B) in the propylene-based polymer (B), the viscoelastic properties and crystallization properties necessary for melt spinning formability are not inhibited, and the modulus of elasticity is improved by the orientation effect of the propylene-based polymer (A) which is a high molecular weight component. At the same time, the effect of suppressing the drawing fracture during tension of long extended molecular chains is exhibited. Therefore, it is estimated that high-speed spinning is possible, and fibers having both a high modulus of elasticity and a high tensile elongation rate can be obtained. Fibers capable of high-speed spinning are fibers in which when the polymer composition is extruded into the atmosphere at a discharge rate of 3.00 g / min from a spinneret die having a diameter of 1 mm at a temperature of 230 °C, the fibers made of the polymer composition are stably formed, and the limit take-up speed of the fibers is 4000 m / min or more. Hereinafter, the details of the fibers according to the present invention will be described.

[0011] <Propylene-based polymer composition> The propylene-based polymer composition contains 1 to 15 parts by mass of a propylene-based polymer (A) and 85 to 99 parts by mass of a propylene-based polymer (B) (the total of the polymer (A) and the polymer (B) is 100 parts by mass). The details of the measurement conditions for each requirement are described in the column of the examples.

[0012] <<Propylene-based polymer (A)>> The propylene-based polymer (A) includes a propylene-based polymer (a1) having an intrinsic viscosity [η] (hereinafter, also simply referred to as "intrinsic viscosity [η]") measured in a tetralin solvent at 135 °C in the range of 10 to 12 dl / g and a propylene-based polymer (a2) having an intrinsic viscosity [η] measured in a tetralin solvent at 135 °C in the range of 0.5 to 3 dl / g. The content of the propylene-based polymer (a1) is in the range of 20 to 50% by mass, and the content of the propylene-based polymer (a2) is in the range of 50 to 80% by mass. However, the total amount of the propylene-based polymer (a1) and the propylene-based polymer (a2) is 100% by mass.

[0013] [Propylene polymer (a1)] The propylene polymer (a1) is not particularly limited and may be a homopolymer of propylene or a copolymer of propylene and an α-olefin other than propylene. Examples of α-olefins other than propylene include α-olefins having 2 to 8 carbon atoms. Examples of the above α-olefins having 2 to 8 carbon atoms include ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Ethylene is preferred among these α-olefins. The above α-olefins having 2 to 8 carbon atoms may be used individually or in combination of two or more.

[0014] When the propylene polymer (a1) is a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, the content of structural units derived from propylene is usually 90% by mass or more, preferably 95% by mass or more, and more preferably 98% by mass or more, relative to the total structural units of the copolymer. The content of structural units derived from α-olefins having 2 to 8 carbon atoms (excluding propylene) is usually 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less, relative to the total structural units of the copolymer. From the viewpoint of enabling high-speed spinning and obtaining fibers with both high elastic modulus and tensile elongation, a propylene homopolymer is preferred for the propylene polymer (A). The content of the above constituent units is, 13 It can be measured by 13C-NMR (nuclear magnetic resonance).

[0015] The intrinsic viscosity [η] of the propylene polymer (a1) is in the range of 10 to 12 dl / g. When the intrinsic viscosity [η] of the propylene polymer (a1) is in the range of 10 to 12 dl / g, the fibers obtained from the propylene polymer composition can be spun at high speed and have both high elastic modulus and tensile elongation. From the above viewpoint, the intrinsic viscosity [η] of the propylene polymer (a1) is preferably in the range of 10.5 to 11.5 dl / g. The intrinsic viscosity [η] is determined by the measurement method described in the examples below.

[0016] Furthermore, the content of the propylene polymer (a1) is in the range of 20 to 50% by mass, preferably 20 to 45% by mass, more preferably 20 to 40% by mass, and even more preferably 22 to 40% by mass, based on the total amount of propylene polymer (a1) and the propylene polymer (a2) described later, per 100% by mass. When the content of the propylene polymer (a1) is in the range of 20 to 50% by mass, the fibers obtained from the propylene polymer composition can be spun at high speed and have both high elastic modulus and tensile elongation. The propylene polymer (a1) may be a single type or two or more types may be used in combination.

[0017] [Propylene polymer (a2)] There are no particular restrictions on the propylene polymer (a2), and it may be a homopolymer of propylene or a copolymer of propylene and an α-olefin other than propylene. Examples of α-olefins other than propylene include ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Ethylene is preferred among these α-olefins. The α-olefins having 2 to 8 carbon atoms may be used individually or in combination of two or more.

[0018] When the propylene polymer (a2) is a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, the content of structural units derived from propylene is preferably 90% by mass or more, more preferably 93% by mass or more, and even more preferably 94% by mass or more, relative to the total structural units of the copolymer. The content of structural units derived from an α-olefin having 2 to 8 carbon atoms (excluding propylene) is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 6% by mass or less, relative to the total structural units of the copolymer. The content of the above structural units is 13 It can be measured by 13C-NMR.

[0019] The intrinsic viscosity [η] of the propylene polymer (a2) is in the range of 0.5 to 3 dl / g. When the intrinsic viscosity [η] of the propylene polymer (a2) is in the range of 0.5 to 3 dl / g, the fibers obtained from the propylene polymer composition can be spun at high speed and have high elastic modulus and tensile elongation. From the above viewpoint, the intrinsic viscosity [η] of the propylene polymer (a2) is preferably in the range of 0.6 to 1.5 dl / g, and more preferably in the range of 0.8 to 1.5 dl / g.

[0020] Furthermore, the content of propylene polymer (a2) in propylene polymer (A) is in the range of 50 to 80% by mass relative to the total amount of propylene polymer (a1) and propylene polymer (a2) as described above. When the content of propylene polymer (a2) is in the range of 50 to 80% by mass, the fibers obtained from the propylene polymer composition can be spun at high speed and have high elastic modulus and tensile elongation. From the above viewpoint, the content of propylene polymer (a2) is preferably in the range of 55 to 80% by mass, more preferably 60 to 80% by mass, and even more preferably 60 to 78% by mass relative to the total amount of propylene polymer (a1) and the propylene polymer (a2) described below as described above as 100% by mass. One or more types of propylene polymers (a2) can be used.

[0021] [Additives] In addition to propylene polymer (a1) and propylene polymer (a2), propylene polymer (A) may contain additives such as antioxidants, neutralizing agents, flame retardants, and crystal nucleating agents as needed. The additives may be used individually or in combination of two or more. The proportion of additives is not particularly limited and can be adjusted as appropriate.

[0022] The melt flow rate (MFR) of the propylene polymer (A), measured at 230°C and a load of 2.16 kg, is preferably 0.01 to 5 g / 10 min, more preferably 0.05 to 4 g / 10 min, and even more preferably 0.1 to 3 g / 10 min. When the MFR of the propylene polymer (A) is within the above range, high-speed spinning is possible, and fibers with high elastic modulus and tensile elongation can be obtained.

[0023] The weight-average molecular weight (Mw) of the propylene polymer (A) is preferably 800,000 to 3,000,000, and more preferably 820,000 to 2,000,000. The weight-average molecular weight is determined by the method described in the examples.

[0024] The number-average molecular weight (Mn) of the propylene polymer (A) is preferably 1,400 to 80,000, and more preferably 2,000 to 18,000. The weight-average molecular weight is determined by the method described in the examples.

[0025] From the viewpoint of enabling high-speed spinning and obtaining fibers with high elastic modulus and tensile elongation, it is preferable that the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) (Mw / Mn) of the propylene polymer (A) is 20 or more, and more preferably 50 or more.

[0026] <Method for producing propylene polymer (A)> As for the method of producing the propylene polymer (A), various known production methods can be cited. For example, method (1) involves producing propylene polymer (a1) and propylene polymer (a2) that satisfy the above physical properties, and then mixing or melt-kneading the propylene polymer (a1) and propylene polymer (a2) within the above range to obtain the propylene polymer (A); and method (2) involves producing propylene polymer (a1) and propylene polymer (a2) that satisfy the above physical properties using one polymerization system or two or more polymerization systems to obtain the propylene polymer (A).

[0027] In method (1), for example, propylene polymer (a1), propylene polymer (a2), and additives as needed are mixed using a Henschel mixer, V-type blender, tumbler blender, ribbon blender, etc., and then melt-kneaded using a single-screw extruder, multi-screw extruder, kneader, Banbury mixer, etc. to obtain a high-quality propylene polymer (A) in which the above components are uniformly dispersed and mixed. The resin temperature during melt-kneading is usually 180 to 280°C, preferably 200 to 260°C.

[0028] In method (2), a propylene polymer (A) containing a relatively high molecular weight propylene polymer (a1) and a relatively low molecular weight propylene polymer (a2) can be obtained by multi-stage polymerization of two or more stages. Additives may be added to the obtained propylene polymer (A) as needed.

[0029] A preferred method for producing the propylene polymer (A) is method (2) described above, which includes, for example, a method in which propylene is polymerized in two or more multi-stage polymerization in the presence of a catalyst for producing highly stereoregular polypropylene, either alone or in combination with other monomers.

[0030] In the above method (2), specifically, in the first stage of polymerization, propylene or propylene and an α-olefin having 2 to 8 carbon atoms are polymerized in substantially the absence of hydrogen to produce a propylene polymer (a1) with an intrinsic viscosity [η] of 10 to 12 dl / g (preferably 10.5 to 11.5 dl / g) and a relative molecular weight to the propylene polymer (a2) in an amount of 20 to 50% by mass (preferably 20 to 45% by mass, more preferably 20 to 40% by mass, and even more preferably 22 to 40% by mass) of the propylene polymer (A), and in the second and subsequent stages of polymerization, a propylene polymer (a2) with a relative molecular weight to the propylene polymer (a1) is produced.

[0031] The intrinsic viscosity [η] of the propylene polymer (a2), which has a relatively low molecular weight compared to the propylene polymer (a1) produced in the second and subsequent polymerization stages, is 0.5 to 3 dl / g (preferably 0.6 to 1.5 dl / g, more preferably 0.8 to 1.5 dl / g). Note that this intrinsic viscosity [η] is the intrinsic viscosity [η] of the propylene polymer produced in that stage alone, and not the total intrinsic viscosity [η] including the propylene polymers up to the stage preceding that stage.

[0032] Furthermore, in the polymerization from the second stage onward, the MFR of the final obtained propylene polymer (A), measured at 230°C and a load of 2.16 kg, is preferably adjusted to be 0.01 to 5 g / 10 min, more preferably 0.05 to 4 g / 10 min, and even more preferably 0.1 to 3 g / 10 min. There are no particular limitations on the method for adjusting the intrinsic viscosity [η] of the propylene polymer (A) produced in the second stage and beyond, but it is preferable to use a method that uses hydrogen as a molecular weight modifier.

[0033] The preferred order of production (polymerization order) for propylene polymer (a1) and propylene polymer (a2) is to first produce a propylene polymer (a1) with a relatively high molecular weight relative to propylene polymer (a2) in substantially the absence of hydrogen in the first step, and then, in the second step and beyond, produce a propylene polymer (a2) with a relatively low molecular weight relative to propylene polymer (a1), for example, in the presence of hydrogen.

[0034] In a method for producing propylene polymer (A), propylene polymer (a2) may be produced in the first step, and then propylene polymer (a1) may be produced in the second step or later (i.e., the production order of propylene polymer (a1) and propylene polymer (a2) may be reversed). In order to produce a propylene polymer (a2) with a relatively low molecular weight relative to the propylene polymer (a1) in the first stage, and then produce a propylene polymer (a1) with a relatively high molecular weight relative to the propylene polymer (a2) in the second and subsequent stages, it is necessary to remove as much as possible of molecular weight adjusting agents such as hydrogen contained in the reaction product of the first stage before the start of polymerization in the second and subsequent stages. This makes the polymerization apparatus complex, and the intrinsic viscosity [η] in the second and subsequent stages does not increase easily. For these reasons, it is preferable to produce the propylene polymer (a1) in the first stage, and then produce the propylene polymer (a2) in the second and subsequent stages.

[0035] In multi-stage polymerization, each stage of polymerization can be carried out continuously or in a batch manner, but it is preferable to carry it out in a batch manner. The propylene polymer (A) obtained by multi-stage polymerization in a batch manner, which contains propylene polymer (a1) and propylene polymer (a2), has the propylene polymer (a1), which is an ultra-high molecular weight component, well dispersed relative to propylene polymer (a2), allowing for high-speed spinning and forming, and yielding fibers with high elastic modulus and tensile elongation.

[0036] In the production of propylene polymers (a1) and (a2), the homopolymerization of propylene or the polymerization of propylene with α-olefins having 2 to 8 carbon atoms can be carried out by known polymerization methods such as slurry polymerization or bulk polymerization. Furthermore, it is preferable to use a catalyst for polypropylene production, as described later, during polymerization.

[0037] The propylene polymer (a1) is preferably produced by bulk polymerization of the raw material monomers in the absence of hydrogen, with a polymerization temperature of preferably 20 to 80°C, more preferably 40 to 70°C, and a polymerization pressure of generally atmospheric pressure to 9.8 MPa, preferably 0.2 to 4.9 MPa.

[0038] The propylene polymer (a2) is preferably produced by polymerizing the raw material monomers under conditions where the polymerization temperature is preferably 20 to 80°C, more preferably 40 to 70°C, the polymerization pressure is generally atmospheric pressure to 9.8 MPa, preferably 0.2 to 4.9 MPa, and hydrogen is present as a molecular weight adjusting agent.

[0039] <<Catalyst for Polypropylene Manufacturing>> A catalyst for polypropylene production (hereinafter also simply referred to as "catalyst") that can be used to produce propylene polymer (a1), propylene polymer (a2), and propylene polymer (A) can be formed from, for example, a solid catalyst component comprising magnesium, titanium, and halogen, an organometallic compound catalyst component such as an organoaluminum compound, and an electron-donating compound catalyst component such as an organosilicon compound. Typical catalyst components that can be used include the following.

[0040] [Solid catalyst component] As the support constituting the solid catalyst component, a support obtained from metallic magnesium, an alcohol, and a halogen and / or halogen-containing compound is preferred.

[0041] As metallic magnesium, magnesium in granular, ribbon, or powder form can be used. Furthermore, it is preferable that the metallic magnesium does not have a coating of magnesium oxide or the like on its surface.

[0042] As the alcohol, it is preferable to use a lower alcohol having 1 to 6 carbon atoms, and in particular, using ethanol yields a support that significantly improves the catalytic performance. The amount of alcohol used is preferably 2 to 100 moles, more preferably 5 to 50 moles, per mole of metallic magnesium. One or more types of alcohol can be used.

[0043] Preferred halogens include chlorine, bromine, and iodine, with iodine being more preferred. Preferred halogen-containing compounds include MgCl2 and MgI2. The amount of halogen or halogen-containing compound used is typically 0.0001 grams or more, preferably 0.0005 grams or more, and more preferably 0.001 grams or more, per gram of metallic magnesium. One or more halogens and halogen-containing compounds can be used.

[0044] One method for obtaining a support by reacting metallic magnesium, an alcohol, and a halogen and / or halogen-containing compound is to react the metallic magnesium, the alcohol, and the halogen and / or halogen-containing compound under reflux (e.g., at about 79°C) until no hydrogen gas is observed (usually 20 to 30 hours). The reaction is preferably carried out under an inert gas atmosphere such as nitrogen gas or argon gas.

[0045] When the support obtained by the above method is used in the synthesis of solid catalyst components, it may be used in a dried state, or it may be used after filtration and washing with an inert solvent such as heptane. The support obtained in this way is nearly granular and has a sharp particle size distribution. Furthermore, even when considering each individual particle, the variation in particle shape is small. In this case, the sphericity (S) represented by the following formula (I) is preferably less than 1.60, particularly preferably less than 1.40, and the particle size distribution index (P) represented by the following formula (II) is preferably less than 5.0, particularly preferably less than 4.0.

[0046] S=(E1 / E2) 2 ...(I) In equation (I), E1 represents the contour length of the particle projection, and E2 represents the circumference of a circle equal to the projected area of ​​the particle.

[0047] P=D 90 / D 10 ...(II) In formula (II), D 90refers to the particle diameter corresponding to a mass cumulative fraction of 90%. That is, it indicates that the sum of the masses of the particle group smaller than the particle diameter represented by D 90 is 90% of the total mass sum of all particles. D 10 refers to the particle diameter corresponding to a mass cumulative fraction of 10%.

[0048] The solid catalyst component is usually obtained by contacting at least a titanium compound with the above carrier. The contact with the titanium compound may be carried out in multiple times. Examples of the titanium compound include titanium compounds represented by the general formula (III).

[0049] TiX 1 n(OR 1 )4-n···(III) In formula (III), X 1 is a halogen atom, particularly preferably a chlorine atom, R 1 is a hydrocarbon group having 1 to 10 carbon atoms, preferably a linear or branched alkyl group. When there are a plurality of R 1 , they may be the same or different from each other, and n is an integer of 0 to 4.

[0050] Specific examples of the titanium compound include Ti(O-i-C3H7)4, Ti(O-C4H9)4, TiCl(O-C2H5)3, TiCl(O-i-C3H7)3, TiCl(O-C4H9)3, TiCl2(O-C4H9)2, TiCl 2( O-i-C3H7)2, TiCl4, and TiCl4 is preferred. One or more titanium compounds can be used.

[0051] The solid catalyst component is usually obtained by further contacting an electron-donating compound with the above carrier. Examples of the electron-donating compound include di-n-butyl phthalate. One or more electron-donating compounds can be used.

[0052] When contacting the above-mentioned carrier with a titanium compound and an electron-donating compound, a halogen-containing silicon compound such as silicon tetrachloride can be brought into contact with it. One or more halogen-containing silicon compounds can be used.

[0053] Solid catalyst components can be prepared by known methods. For example, an inert hydrocarbon such as pentane, hexane, heptane, or octane is used as a solvent, and the above-mentioned carrier, electron-donating compound, and halogen-containing silicon compound are added to the solvent, and the titanium compound is added while stirring. Typically, 0.01 to 10 moles, preferably 0.05 to 5 moles, of the electron-donating compound are added per mole of carrier in terms of magnesium atoms, and 1 to 50 moles, preferably 2 to 20 moles, of the titanium compound are added per mole of carrier in terms of magnesium atoms, and the catalytic reaction is carried out at 0 to 200°C for 5 minutes to 10 hours, preferably at 30 to 150°C for 30 minutes to 5 hours. After the reaction is complete, it is preferable to wash the generated solid catalyst components with an inert hydrocarbon such as n-hexane or n-heptane.

[0054] Furthermore, the solid catalyst component may be a component obtained by contacting a liquid magnesium compound and a liquid titanium compound in the presence of an electron-donating compound. Contact with the liquid titanium compound may be carried out in multiple steps.

[0055] Liquid magnesium compounds are obtained, for example, by contacting a known magnesium compound and an alcohol, preferably in the presence of a liquid hydrocarbon medium, to make them liquid. Examples of magnesium compounds include magnesium halides such as magnesium chloride and magnesium bromide. Examples of alcohols include aliphatic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and 2-ethylhexyl alcohol. Examples of liquid hydrocarbon mediums include hydrocarbon compounds such as heptane, octane, and decane. The amount of alcohol used when preparing a liquid magnesium compound is usually 1.0 to 25 moles, preferably 1.5 to 10 moles, per mole of magnesium compound. One or more liquid magnesium compounds can be used.

[0056] Examples of liquid titanium compounds include the titanium compound represented by the general formula (III) described above. The amount of liquid titanium compound used per mole of magnesium atoms (Mg) contained in the liquid magnesium compound is usually 0.1 to 1000 moles, preferably 1 to 200 moles. One or more types of liquid titanium compounds can be used.

[0057] Examples of electron-donating compounds include dicarboxylic acid ester compounds such as phthalates, acid anhydrides such as phthalic anhydride, organosilicon compounds such as dicyclopentyl dimethoxysilane, dicyclohexyl dimethoxysilane, and cyclohexylmethyl dimethoxysilane, polyethers, acid halides, acid amides, nitriles, and organic acid esters. The amount of electron-donating compound used per mole of magnesium atoms (Mg) in the liquid magnesium compound is usually 0.01 to 5 moles, preferably 0.1 to 1 mole. One or more electron-donating compounds can be used. The temperature at which contact occurs is typically -70 to 200°C, preferably 10 to 150°C.

[0058] [Organometallic compound catalyst component] Among the catalyst components, organoaluminum compounds are preferred as organometallic compound catalyst components. Examples of organoaluminum compounds include those represented by general formula (IV).

[0059] AlR 2 nX 2 3-n ...(IV) In formula (IV), R 2 X is an alkyl group, cycloalkyl group, or aryl group having 1 to 10 carbon atoms. 2 n is a halogen atom or an alkoxy group, preferably a chlorine atom or a bromine atom, and n is an integer from 1 to 3.

[0060] Examples of organoaluminum compounds include trialkylaluminum compounds such as trimethylaluminum, triethylaluminum, and triisobutylaluminum, as well as diethylaluminum monolide, diisobutylaluminum monolide, diethylaluminum monoethoxide, and ethylaluminum sesquichloride.

[0061] One or more organoaluminum compounds may be used. The amount of organometallic compound catalyst component used is typically 0.01 to 20 moles, preferably 0.05 to 10 moles, per mole of titanium atoms in the solid catalyst component.

[0062] [Electron-donating compound catalyst component] Among the catalyst components, organosilicon compounds are preferred as the electron-donating compound component for the polymerization system. Examples of organosilicon compounds include dicyclopentyl dimethoxysilane, cyclohexylmethyl dimethoxysilane, diethylaminotriethoxysilane, diisopropyl dimethoxysilane, and cyclohexyl isobutyl dimethoxysilane.

[0063] One or more organosilicon compounds may be used. The amount of electron-donating compound component used is typically 0.01 to 20 moles, preferably 0.1 to 5 moles, per mole of titanium atoms in the solid catalyst component.

[0064] -Pre-treatment- It is preferable to use the above-mentioned solid catalyst components in polymerization after pretreatment such as prepolymerization. For example, an inert hydrocarbon such as pentane, hexane, peptane, or octane is used as the solvent, and the above-mentioned solid catalyst components, organometallic compound catalyst components, and optionally electron-donating compound components are added to the solvent, and propylene is supplied while stirring to allow the reaction to proceed. It is preferable to supply the propylene under a partial pressure of propylene higher than atmospheric pressure and pretreat it at 0 to 100°C for 0.1 to 24 hours. After the reaction is complete, it is preferable to wash the pretreated material with an inert hydrocarbon such as n-hexane or n-heptane.

[0065] <Propylene-based polymer (B)> The propylene polymer composition contains a propylene polymer (B). The propylene polymer (B) includes a propylene homopolymer and a copolymer of propylene and α-olefin (excluding propylene). Examples of the copolymer include propylene-α-olefin random copolymer, block-type propylene copolymer (a mixture of propylene homopolymer or propylene-α-olefin random copolymer and amorphous or low-crystallinity propylene-α-olefin random copolymer), and random block polypropylene.

[0066] Examples of α-olefins other than propylene include 2-12 carbon olefins such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 4-methyl-1-pentene, and 3-methyl-1-pentene. Among these α-olefins, ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene are preferred. One or more α-olefins can be used.

[0067] When the propylene polymer (B) is a copolymer of propylene and α-olefin (excluding propylene), the content of constituent units derived from propylene is usually 90 to 99.9% by mass, preferably 92 to 99.5% by mass, and more preferably 94 to 99% by mass, relative to the total constituent units of the copolymer. The content of constituent units derived from α-olefin (excluding propylene) is usually 0.1 to 10% by mass, preferably 0.5 to 8% by mass, and more preferably 1 to 6% by mass, relative to the total constituent units of the copolymer. The content of constituent units derived from propylene is 13 It can be measured by 13C-NMR.

[0068] As the propylene polymer (B), a homopolymer of propylene is preferred from the viewpoint of enabling high-speed spinning and producing fibers with both high elastic modulus and tensile elongation. The propylene polymer (B) may be obtained by polymerizing propylene using a catalyst or copolymerizing propylene with another α-olefin, or it may be a commercially available polypropylene resin. Examples of catalysts used in the method for producing the propylene polymer (B) include catalysts formed from the above-mentioned solid catalyst components comprising magnesium, titanium, and halogen, organometallic compound catalyst components such as organoaluminum compounds, and electron-donating compound catalyst components such as organosilicon compounds; and metallocene catalysts using metallocene compounds as one component of the catalyst.

[0069] The propylene polymer (B) has a melt flow rate (MFR) of 15 g / 10 min to 80 g / 10 min, measured at 230°C and a load of 2.16 kg, and a ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) of 5.0 or less. When the MFR of the propylene polymer (B) is 15-80 g / 10 min, high-speed spinning is possible, and fibers with high elastic modulus and tensile elongation can be obtained. From the above viewpoint, the MFR is preferably 18-60 g / 10 min, and more preferably 20-30 g / 10 min.

[0070] The weight-average molecular weight (Mw) of the propylene polymer (B) is preferably 100,000 to 300,000, and more preferably 150,000 to 250,000, from the viewpoint of enabling high-speed spinning and ensuring high elastic modulus and tensile elongation of the fibers.

[0071] The number-average molecular weight (Mn) of the propylene polymer (B) is preferably 20,000 to 80,000, and more preferably 40,000 to 60,000, from the viewpoint of enabling high-speed spinning and obtaining fibers with high elastic modulus and tensile elongation. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the propylene polymer (B) can be measured by the measurement method described in the examples below.

[0072] The ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the propylene polymer (B) is 5.0 or less. When the (Mw / Mn) of the propylene polymer (B) is 5.0 or less, high-speed spinning is possible, and fibers with high elastic modulus and tensile elongation can be obtained. From the above viewpoint, the (Mw / Mn) of the propylene polymer (B) is preferably 2 to 5, and more preferably 3 to 5. The weight-average molecular weight (Mw), number-average molecular weight (Mn), and the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) of the propylene polymer (B) are determined from values ​​measured by gel permeation chromatography (GPC), specifically by the measurement method described in the examples below. Furthermore, the (Mw / Mn) ratio of the propylene polymer (B) can be adjusted by the composition of the propylene polymer (B).

[0073] The intrinsic viscosity [η] of the propylene polymer (B), measured at 135°C in a tetralin solvent, is preferably greater than 1.5 dl / g and less than or equal to 5.0 dl / g, more preferably greater than 1.5 dl / g and less than or equal to 4.5 dl / g, and even more preferably greater than 1.5 dl / g and less than or equal to 4.0 dl / g. When a propylene polymer (B) with an intrinsic viscosity [η] within the above range is used, high-speed spinning and forming are possible, and both the elastic modulus and tensile elongation of the fiber are high.

[0074] <<Other ingredients (additives)>> In addition to the propylene polymers (A) and (B), the propylene polymer composition may contain additives such as weather stabilizers, heat stabilizers, antistatic agents, slip agents, antiblocking agents, antifogging agents, nucleating agents, decomposing agents, pigments, dyes, plasticizers, hydrochloric acid absorbers, antioxidants, crosslinking agents, crosslinking accelerators, reinforcing agents, fillers, softeners, processing aids, activators, hygroscopic agents, adhesives, flame retardants, and mold release agents, to the extent that they do not impair the objectives of the present invention. One or more additives may be used.

[0075] Propylene polymer compositions may contain nucleating agents to improve transparency, heat resistance, and other properties. Examples of nucleating agents include sorbitol compounds such as dibenzylidenesorbitol, organophosphate ester compounds, rosinate compounds, C4-C12 aliphatic dicarboxylic acids and their metal salts. Of these, organophosphate ester compounds are preferred.

[0076] The nucleating agent content is preferably 0.05 to 0.5 parts by mass, more preferably 0.1 to 0.3 parts by mass, per 100 parts by mass of the total of propylene polymer (A) and propylene polymer (B). One or more nucleating agents can be used.

[0077] In the propylene polymer composition, the content of propylene polymer (A) is 1 to 15 parts by mass, preferably 3 to 12 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of the total of propylene polymer (A) and propylene polymer (B). When the content of propylene polymer (A) is within the above range, high-speed spinning is possible, and fibers with high elastic modulus and tensile elongation can be obtained. The content of propylene polymer (B) is 85 to 99 parts by mass, preferably 88 to 97 parts by mass, and more preferably 90 to 97 parts by mass, based on 100 parts by mass of the total of propylene polymer (A) and propylene polymer (B). When the content of propylene polymer (B) is within the above range, high-speed spinning is possible, and both the elastic modulus and tensile elongation of the fibers are high.

[0078] From the viewpoint of enabling high-speed spinning and obtaining fibers with high elastic modulus and tensile elongation, it is preferable that, in the measurement of the dynamic viscoelasticity of the propylene polymer composition at 210°C, the ratio of the storage modulus G'(100) at an angular frequency of 100 rad / sec to the storage modulus G'(10) at an angular frequency of 10 rad / sec (G'(100) / G'(10)) is 4.5 to 10.0, and the ratio of the storage modulus G'(0.1) at an angular frequency of 0.1 rad / sec to the storage modulus G'(0.01) at an angular frequency of 0.01 rad / sec (G'(0.1) / G'(0.01)) is 3 to 20.

[0079] From the viewpoint of enabling high-speed spinning and obtaining fibers with high elastic modulus and tensile elongation, in the dynamic viscoelastic evaluation of the propylene polymer composition at 210°C, (G'(100) / G'(10)) is preferably 4.5 to 8.0, and more preferably 5.0 to 6.0. From the viewpoint of enabling high-speed spinning and obtaining fibers with high elastic modulus and tensile elongation, (G'(0.1) / G'(0.01)) is preferably 5 to 18, and more preferably 8 to 16. The measurement conditions for dynamic viscoelasticity are the same as those described in the examples below, and (G'(100) / G'(10)) and (G'(0.1) / G'(0.01)) are determined by the measurement method described in the examples below.

[0080] From the viewpoint of enabling high-speed spinning and obtaining fibers with high elastic modulus and tensile elongation, the melt flow rate (MFR) of the propylene polymer composition, measured at 230°C and a load of 2.16 kg, is preferably 10 to 60 g / 10 min, and more preferably 15 to 30 g / 10 min.

[0081] The propylene polymer composition can be produced by any known method, for example, by mixing the above-mentioned propylene polymer (A) and the above-mentioned propylene polymer (B), and other components as needed, using a Henschel mixer, V-blender, ribbon blender, tumbler blender, etc., or by melt-kneading the mixture after mixing using a single-screw extruder, twin-screw extruder, kneader, Banbury mixer, rolls, etc., followed by granulation or pulverization.

[0082] In the present invention, the propylene polymer composition is preferably prepared by mixing a propylene polymer (A) containing propylene polymer (a1) and propylene polymer (a2), obtained by batch-type multi-stage polymerization, with a propylene polymer (B), from the viewpoint of obtaining fibers that can be spun at high speed and have both high elastic modulus and tensile elongation.

[0083] The propylene polymer (A) and propylene polymer (B) of the present invention may contain at least one biomass-derived monomer (propylene). For example, the monomers of the same type constituting the above polymer may consist only of biomass-derived monomers, or they may contain both biomass-derived monomers and fossil fuel-derived monomers. Biomass-derived monomers are monomers made from any renewable natural raw materials and their residues, including fungi, yeasts, algae, and bacteria, which are plant-derived or animal-derived, and are carbon-based. 14 10 C isotopes -12It is preferable that it contains a certain proportion and that the biomass carbon concentration (pMC: Percentage of Modern Carbon) measured in accordance with ASTM D 6866 is about 100 pMC. The biomass-derived monomer (propylene) is obtained by conventionally known methods. It is preferable from the viewpoint of reducing environmental impact that the propylene polymer (A) and propylene polymer (B) of the present invention contain biomass-derived monomers. In the case of propylene polymers, if the polymer production conditions such as polymerization catalyst and polymerization temperature are the same, even if the raw material olefin contains biomass-derived olefins, 14 10 C isotopes -12 Aside from the proportions it contains, the molecular structure of propylene polymers made from biomass-derived monomers is equivalent to that of propylene polymers made from fossil fuel-derived monomers. Therefore, their performance is considered to be the same.

[0084] The fiber according to the present invention is a fiber made from the above-mentioned propylene polymer composition. The apparent fineness of the fiber is not particularly limited and can be appropriately selected according to the application and required characteristics, but is preferably 0.5 to 50 dtex, and more preferably 5 to 20 dtex. When the apparent fineness is within the above range, the fiber has good spinning operability and process passability in higher-order processing, enables high-speed spinning and forming, and has high elastic modulus and tensile elongation. The apparent fineness is determined by the measurement method described in the examples below.

[0085] The tensile strength of the fiber is not particularly limited and can be appropriately selected according to the application and required characteristics, but is preferably 5 to 30 cN / dtex, and more preferably 10 to 25 cN / dtex. When the tensile strength is within the above range, there is less yarn breakage in spinning, drawing, weaving, and knitting processes, the fiber passes through the processes well, and high-speed spinning and forming are possible, and the fiber has both high elastic modulus and tensile elongation.

[0086] The tensile elongation of the fiber is not particularly limited and can be appropriately selected according to the application and required characteristics, but is preferably 1000 to 1500%, and more preferably 1100 to 1300%. If the fiber is an undrawn yarn, a tensile elongation of 1500% or less provides good handling during drawing and makes it easy to improve the mechanical properties by drawing. The tensile elongation is determined by the measurement method described in the examples below.

[0087] The initial tensile resistance (modulus of elasticity) of the fiber is preferably 0.01 N / dtex to 5.0 N / dtex, more preferably 0.5 N / dtex to 3.0 N / dtex, and even more preferably 1.0 N / dtex to 2.0 N / dtex. The initial tensile resistance of the fiber is determined by the measurement method described in the examples below.

[0088] The composite spun fiber according to the present invention preferably contains fibers made of the above-mentioned propylene-based polymer composition. The composite spun fiber may also contain fibers other than those made of the above-mentioned propylene-based polymer composition. Examples of fibers other than those made of the above-mentioned propylene-based polymer composition include fibers containing 4-methyl-1-pentene polymer, polyethylene-based polymer, etc. There are no particular restrictions on the form of the composite spun fiber; examples include side-by-side composite fibers and eccentric core-sheath type fibers.

[0089] There are no particular restrictions on the cross-sectional shape of the fiber; it can be appropriately selected according to the application and required characteristics, and examples include circular, flattened, rounded, multi-lobed, and polygonal shapes.

[0090] <<Fiber manufacturing method>> The method for producing fibers according to the present invention preferably includes a step of melt-spinning a propylene-based polymer composition. Fibers obtained by melt-spinning a propylene-based polymer composition are capable of high-speed spinning and exhibit high elastic modulus and tensile elongation. Known melt-spinning methods can be employed.

[0091] The extruder used in melt spinning can be a known extruder such as a single-screw extruder or a twin-screw extruder. The diameter of the extruder nozzle is appropriately determined based on the required fiber diameter (yarn diameter) and the relationship between the extruder's discharge speed and take-up speed, but is preferably around 0.1 to 3.0 mm. Stretching of the fibers after spinning is not always necessary, but if stretching is performed, the fibers may be stretched to 1.1 to 10 times, preferably 2 to 8 times. The fiber diameter (average diameter) is preferably 0.5 to 40 denier.

[0092] The method for producing the fibers may further include steps other than the step of melt-spinning the propylene polymer composition (other steps). Examples of other steps include a step of mixing the raw materials for the propylene polymer composition and a step of melt-kneading the propylene polymer composition. [Examples]

[0093] The present invention will be further described below with reference to examples. However, the present invention is not limited to these examples.

[0094] The following polymers were used as polymers in the propylene polymer compositions used in the examples and comparative examples. The various properties of the polymers and fibers obtained below were measured and evaluated as follows.

[0095] (1) Content of the first-stage propylene polymer component [propylene polymer (a1)] and the second-stage propylene polymer component [propylene polymer (a2)] This was determined from the mass balance using the integrated flow meter readings of propylene continuously supplied during polymerization.

[0096] (2) Intrinsic viscosity [η] (dl / g) The intrinsic viscosity [η] was measured at 135°C in tetralin solvent. Furthermore, the intrinsic viscosity [η]² of the propylene polymer (a2) is calculated using the following formula. [η]2=([η]total×100-[η]1×W1) / W2 [η]total: Intrinsic viscosity of propylene polymer (A) [η]1: Intrinsic viscosity of propylene polymer (a1) W1: Content of propylene polymer (a1) (%) W2: Content of propylene polymer (a2) (%)

[0097] (3) Melt Flow Rate (MFR) (g / 10 min) Measurements were taken in accordance with JIS K7210-1:2014, at a measurement temperature of 230°C and a load of 2.16 kgf (21.2 N).

[0098] (4) The ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) The ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn), calculated from the molecular weight distribution curve measured by gel permeation chromatography (GPC) under the following apparatus and conditions, was evaluated as an indicator of the breadth of the molecular weight distribution. -GPC measurement device- Column: TOSO GMHHR-H(S)HT Detector: Waters liquid chromatograph detector RI detector WATERS150C (product name) -Measurement conditions- Solvent: 1,2,4-Trichlorobenzene Temperature: 145℃

[0099] (5) Storage modulus G' Dynamic viscoelasticity was measured using the following apparatus and conditions to determine the storage modulus G'. The ratio of the storage modulus G'(100) at an angular frequency of 100 rad / sec to the storage modulus G'(10) at an angular frequency of 10 rad / sec (G'(100) / G'(10)) and the ratio of the storage modulus G'(0.1) at an angular frequency of 0.1 rad / sec to the storage modulus G'(0.01) at an angular frequency of 0.01 rad / sec (G'(0.1) / G'(0.01)) were determined. Equipment: Physica MCR301 (product name), manufactured by Anton Paar. Temperature: 210℃ Distortion: 10% Angular frequency: 0.01~100rad / sec

[0100] (6) Melt spinning Pellet-shaped propylene polymers (A) and / or (B) were melt-extruded at 230°C using a single-screw extruder with a screw diameter of 20 mm. The flow rate was then adjusted with a gear pump, and the resulting material was extruded into the atmosphere at a temperature of 230°C through a 1 mm diameter spinning die at a discharge rate of 3.00 g / min. Polypropylene fibers were obtained by winding the filamentous resin while sequentially increasing the take-up speed to 500 m / min, 1000 m / min, and 2000 m / min. Subsequently, the take-up speed was increased in increments of 1000 m / min, and the maximum take-up speed at which stable molding could be achieved was evaluated as the "limit take-up speed." If the limit take-up speed is 4000 m / min or higher, it can be said that high-speed spinning and molding is possible.

[0101] (7) Tensile properties of the fiber (tensile strength, tensile elongation, and initial tensile resistance (modulus of elasticity)) Using fibers wound at take-up speeds of 500 m / min and 2000 m / min obtained under the conditions of (6) above, the tensile strength (cN / dtex) and tensile elongation (%) were measured in accordance with the method conforming to JIS L 1013 (2010). In Comparative Example 1, described later, spinning was not possible due to poor spinnability when the take-up speed exceeded 2000 m / min. Therefore, the upper limit of the take-up speed for the tensile properties of the fiber was set to 2000 m / min as a condition that could be compared with the physical properties of Comparative Example 1. Tensile tests were conducted using a constant-speed elongation testing machine, with a gripping distance of 4 cm between the chucks and a tensile speed of 4 cm / min. A sample size of 10 was used, and the average value was calculated. The average values ​​of the obtained tensile strength (cN / dtex) and tensile elongation (%) are shown in Table 1. Furthermore, the elastic modulus was evaluated by measuring the initial tensile resistance (N / dtex). The initial tensile resistance (N / dtex) was calculated by plotting a stress-elongation curve using the above measurement method, and determining the maximum value of the load change (the point of maximum tangent angle) for load changes that elongate near the origin from this curve. Tri = P / (l' / l) × F Tri: Initial tensile resistance (N / tex) P: Load (N) at the point of maximum tangent angle F0: Correct fiber density (tex) l: Test length (mm) l': In the load-elongation curve, the length (in mm) between the perpendicular line from the load at the point of maximum tangent angle to the horizontal axis and the intersection point of the tangent line and the horizontal axis.

[0102] (8) Apparent fineness of fibers The fibers obtained as described below were measured using the vibration method in accordance with JIS L 1015 (2010). A sample size of 10 was used, and the average value was calculated.

[0103] <Propylene-based polymer (A)> <<Manufacturing Example 1>> (1) Preparation of magnesium compounds A reaction vessel with a stirrer (internal volume 500 liters) was thoroughly purged with nitrogen gas, and 97.2 kg of ethanol, 640 g of iodine, and 6.4 kg of metallic magnesium were added. The reaction was carried out under reflux conditions with stirring until no more hydrogen gas was generated in the system, yielding a solid reaction product. The reaction solution containing this solid reaction product was dried under reduced pressure to obtain the target magnesium compound (support for the solid catalyst).

[0104] (2) Preparation of solid catalyst components In a stirrer-equipped reaction vessel (internal volume 500 liters) thoroughly purged with nitrogen gas, 30 kg of the above magnesium compound (unpulverized), 150 liters of purified heptane (n-heptane), 4.5 liters of silicon tetrachloride, and 5.4 liters of di-n-butyl phthalate were added. Maintaining the system temperature at 90°C, 144 liters of titanium tetrachloride were added while stirring, and the mixture was reacted at 110°C for 2 hours. After that, the solid components were separated and washed with purified heptane at 80°C. Furthermore, 228 liters of titanium tetrachloride were added, and the mixture was reacted at 110°C for 2 hours, after which it was thoroughly washed with purified heptane to obtain the solid catalyst component.

[0105] (3) Production of prepolymerization catalyst 10 mmol of triethylaluminum, 2 mmol of dicyclopentyl dimethoxysilane, and 1 mmol (in terms of titanium atoms) of the solid catalyst component obtained in (2) above were added to 200 mL of heptane. The internal temperature was maintained at 20°C, and propylene was continuously introduced while stirring. After 60 minutes, stirring was stopped, and a prepolymerization catalyst was obtained in which 4.0 g of propylene was polymerized per 1 g of solid catalyst.

[0106] (4) This polymerization 336 liters of propylene were placed in a 600-liter autoclave and heated to 60°C. Then, 8.7 mL of triethylaluminum, 11.4 mL of dicyclopentyl dimethoxysilane, and 2.9 g of the prepolymerization catalyst obtained in (3) above were added, and polymerization was started. 75 minutes after the start of polymerization, the temperature was lowered to 50°C over 10 minutes (completion of the first stage of polymerization). The intrinsic viscosity [η] of the propylene polymer (a1) polymerized under the same conditions as the first stage was 11 dl / g. After cooling, hydrogen was continuously added to maintain a constant pressure of 3.3 MPaG, and polymerization was carried out for 151 minutes. Next, the vent valve was opened, and the unreacted propylene (propylene polymer (a2)) was purged through an integrated flow meter (completion of the second stage of polymerization). Thus, 51.8 kg of powdered propylene polymer (A) was obtained. The intrinsic viscosity of propylene polymer (A) was 3.49 dl / g.

[0107] The propylene polymer (A) obtained above was mixed with 2000 ppm of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.), 2000 ppm of Irgaphos 168 (manufactured by Ciba Specialty Chemicals Co., Ltd.), and 1000 ppm of Sandstab P-EPQ (manufactured by Clariant Japan Co., Ltd.) as antioxidants, and 1000 ppm of calcium stearate as a neutralizing agent. The mixture was then melt-kneaded in a twin-screw extruder to obtain pelletized propylene polymer (A). The final propylene polymer (A) obtained in this manner had a molecular weight (MFR) of 1.2 g / 10 min, measured at 230°C and a load of 2.16 kg. Furthermore, the content of the propylene polymer (a1) produced in the first polymerization stage, calculated from the mass balance, was 25% by mass, and the content of the propylene polymer (a2) produced in the second polymerization stage was 75% by mass. Furthermore, the intrinsic viscosity [η] of the propylene polymer (a2) was calculated according to the above formula and was found to be 0.99 dl / g.

[0108] <Propylene-based polymer (B)> • (B-1): Manufactured by Prime Polymer Co., Ltd.: Product name "Y-2005GP", Propylene homopolymer (HomoPP), MFR = 20g / 10min, Mw / Mn = 4.8 (B-2): Propylene homopolymer (homoPP), MFR = 3.0 g / 10 min, Mw / Mn = 9.8 • (B-3): Manufactured by Prime Polymer Co., Ltd.: Product name "F133A", Propylene homopolymer (HomoPP) MFR=3.1g / 10min, Mw / Mn=5.3

[0109] [Example 1] The propylene polymer (A) obtained in Production Example 1 and the propylene polymer (B):(B-1) were melt-kneaded at 200°C using a twin-screw extruder (model: TEX30α) manufactured by Japan Steel Works Ltd. in a mass ratio of 3:97, and melt-spinning was performed under the molding conditions of (6) above to prepare the fibers.

[0110] [Example 2] The propylene polymer (A) obtained in Production Example 1 and the propylene polymer (B):(B-1) were melt-kneaded in a mass ratio of 5:95 in the same manner as in Example 1, and melt-spinning was performed under the molding conditions of (6) above to prepare the fibers.

[0111] [Example 3] The propylene polymer (A) obtained in Production Example 1 and the propylene polymer (B):(B-1) were melt-kneaded in a mass ratio of 10:90 in the same manner as in Example 1, and melt-spinning was performed under the molding conditions of (6) above to prepare the fibers.

[0112] [Comparative Example 1] The propylene polymer (A) obtained in Production Example 1 and the propylene polymer (B):(B-1) were melt-kneaded in a mass ratio of 20:80 in the same manner as in Example 1, and melt-spinning was performed under the molding conditions of (6) above to prepare the fibers. The ratio G'(100) / G'(10) between the storage modulus G'(100) at an angular frequency of 100 rad / s and the storage modulus G'(10) at an angular frequency of 10 rad / s was small at 4.15, causing the critical take-up rate in melt spinning to decrease to 2000 m / min and impairing high-speed spinning performance.

[0113] [Comparative Example 2] Propylene polymer (B):(B-1) alone was melt-spun under the molding conditions described in (6) above to prepare fibers. Since it did not contain propylene polymer (A), the elongation rate and initial tensile resistance of the fibers were at conventional levels.

[0114] [Comparative Example 3] Fibers were prepared by melt spinning using a propylene polymer (B):(B-3) under the molding conditions described in (6) above. The ratio G'(100) / G'(10) of the storage modulus G'(10) at an angular frequency of 100 rad / s to the storage modulus G'(10) at an angular frequency of 10 rad / s was small at 3.54, and the limiting take-up rate in melt spinning molding was limited to 1000 m / min.

[0115] [Comparative Example 4] The propylene polymer (B):(B-2) is a two-stage polymer consisting of a propylene polymer with an intrinsic viscosity [η] of 8 dl / g and a component content of 20% by mass, and a propylene polymer with an intrinsic viscosity [η] of 1.44 dl / g and a component content of 80% by mass. This propylene polymer (B):(B-2) and the propylene polymer (B):(B-1) were melt-kneaded in a mass ratio of 10:90 in the same manner as in Example 1, and melt-spinning was performed under the molding conditions of (6) above to prepare fibers. In Comparative Example 4, the dispersion of the ultra-high molecular weight component, propylene polymer (B):(B-2), was insufficient, and the limiting take-up rate in melt spinning was limited to 3000 m / min.

[0116] [Table 1]

[0117] In Table 1, "-" indicates that the component is not present or that a value could not be obtained for the corresponding measurement item. As shown in Table 1, the fibers of the present invention in Examples 1 to 3 are capable of high-speed spinning and forming, and exhibit higher elastic modulus and tensile elongation compared to the fibers of Comparative Examples 1 to 4. Furthermore, as shown in Table 1, the fibers of the present invention exhibit high elastic modulus and tensile elongation even in thick fibers obtained at a low take-up speed of 500 m / min, suggesting that the fibers of the present invention can also be used as raw materials for multi-stage stretching.

Claims

1. The process includes a step of melt-spinning a propylene polymer composition containing 3 to 10 parts by mass of the following propylene polymer (A) and 90 to 97 parts by mass of the propylene polymer (B) (the total of polymer (A) and polymer (B) being 100 parts by mass), A method for producing fibers, wherein the propylene polymer composition has a melt flow rate (MFR) of 15 to 30 g / 10 min, measured at 230°C and a load of 2.16 kg; Propylene polymer (A): comprising a propylene polymer (a1) having an intrinsic viscosity [η] measured at 135°C in tetralin solvent in the range of 10 to 12 dl / g, and a propylene polymer (a2) having an intrinsic viscosity [η] measured at 135°C in tetralin solvent in the range of 0.5 to 3 dl / g, wherein the content of the propylene polymer (a1) is in the range of 20 to 50% by mass, and the content of the propylene polymer (a2) is in the range of 50 to 80% by mass [provided that the total amount of the propylene polymer (a1) and the propylene polymer (a2) is 100% by mass]; Propylene polymer (B): The melt flow rate measured at 230°C and a load of 2.16 kg is 15 g / 10 min to 80 g / 10 min, and the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is 5.0 or less.

2. The method for producing fibers according to claim 1, wherein the ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the propylene polymer (A) is 20 or more.

3. A method for producing a fiber according to claim 1 or claim 2, wherein, in the measurement of the dynamic viscoelasticity of the propylene polymer composition at 210°C, the ratio of the storage modulus G'(100) at an angular frequency of 100 rad / s to the storage modulus G'(10) at an angular frequency of 10 rad / s (G'(100) / G'(10)) is 4.5 to 10.0, and the ratio of the storage modulus G'(0.1) at an angular frequency of 0.1 rad / s to the storage modulus G'(0.01) at an angular frequency of 0.01 rad / s (G'(0.1) / G'(0.01)) is 3 to 20.

4. The method for producing fibers according to any one of Claims 1 to 3, wherein the melt spinning step includes winding up the extruded propylene polymer composition, and the limiting draw speed in the winding is 4000 m / min or more.

5. The method for producing fibers according to any one of Claims 1 to 4, wherein the melt spinning step includes extruding the propylene polymer composition into the air at a temperature of 230°C from a spinning die with a diameter of 1 mm at a discharge rate of 3.00 g / min.

6. A method for producing composite spun fibers, according to any one of claims 1 to 5.

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