Polyethylene with excellent heat resistance

Abstract

A polyethylene according to the present invention is characterized by having an oxidative induction time of 10 minutes or more at a temperature of 210 to 230°C when measured by a rotational rheometer, and having a peak corresponding to polypropylene when measured by NMR.

Description

Polyethylene with excellent heat resistance

[0001] The present invention relates to polyethylene with excellent heat resistance. More specifically, the present invention relates to polyethylene with excellent heat resistance and adhesive properties.

[0002]

[0003] Due to the nature of the process, polyethylene resins for radiation applications require a high melt index (MI) of 15 g / 10 min or higher. To increase the melt index of polyethylene, efforts are being made to increase the proportion of relatively low molecular weight polyethylenes. Such polyethylenes with a high proportion of low molecular weights offer advantages in extrusion processability (extrusion load) and post-processing (web formation).

[0004] However, the melt spinning process is carried out at high temperatures of over 200 degrees, and in the case of low molecular weight polyethylene, there is a problem that the resin is oxidized and carbonized or gels are generated, causing single fibers (fiber breakage) due to low heat resistance.

[0005] Therefore, it is necessary to develop a polyethylene resin that has both excellent melt spinning processability and heat resistance.

[0006] Related prior art includes domestic patent No. KR10-2022-0076357.

[0007]

[0008] The purpose of the present invention is to provide polyethylene having excellent melt spinning processability and heat resistance, and a method for producing the same.

[0009] Another object of the present invention is to provide polyethylene having excellent adhesiveness and tensile strength and a method for producing the same.

[0010] Another object of the present invention is to provide polyethylene and a method for producing the same, which significantly reduces gel formation in a melt spinning process.

[0011] Another object of the present invention is to provide fibers and nonwoven fabrics formed by melt spinning the polyethylene.

[0012] Another object of the present invention is to provide a method for preventing single yarn during melt spinning of polyethylene.

[0013] The above and other objects of the present invention can all be achieved by the present invention described below.

[0014]

[0015] 1. One aspect of the present invention relates to polyethylene. The polyethylene is characterized by having an oxidative induction time of about 10 minutes or more, for example, about 10 to 20 minutes, and in a specific example, about 10 to 15 minutes, as measured by a rotational rheometer at a temperature of about 210 to about 230°C, and a peak corresponding to polypropylene is present in NMR measurement.

[0016] 2. In the above 1 specific example, the polyethylene may have a weight average molecular weight of about 40,000 g / mol to about 60,000 g / mol, for example, about 41,000 to about 45,000 g / mol, about 45,000 to about 49,000 g / mol, about 49,000 to about 53,000 g / mol, or about 53,000 to about 59,000 g / mol, and may have a polydispersity index (PDI) of about 7 or more.

[0017] 3. In the above 1-2 specific examples, the polyethylene may include from about 0 to about 5 wt%, for example, from about 1 to about 3 wt%, preferably from about 1.1 to about 2 wt%, of polypropylene.

[0018] 4. In the above 1-3 specific examples, the polyethylene is 1 m 2The number of gels having a maximum diameter of about 400 μm or more may be less than about 150, for example, about 1 to about 40, about 40 to about 80, or about 80 to about 140.

[0019] 5. In the above 1-4 specific examples, the polyethylene may have a melting index (ASTM D 1238, 190°C, 2.16 kg) of about 15 to about 40 g / 10 min, for example, about 15.5 to about 20 g / 10 min, about 20 to about 25 g / 10 min, about 25 to about 30 g / 10 min, or about 30 to about 38.5 g / 10 min.

[0020] 6. In the above 1-5 specific examples, the polyethylene has a melt flow rate (MFR, 190°C, MI) 21.6 / MI 2.16 ) may be from about 20 to about 30, for example, from about 20.5 to about 23.5, from about 23.5 to about 26.5, from about 26.5 to about 29.5.

[0021] 7. In the above 1-6 specific examples, the polyethylene has a density of about 0.948 to about 0.965 g / cm 3 , for example, about 0.950 to about 0.953 g / cm 3 , About 0.953 to about 0.956 g / cm 3 , about 0.956 to about 0.960 g / cm 3 , about 0.960 to about 0.963 g / cm 3 It could be.

[0022] 8. In the above 1-7 specific examples, the polyethylene may have a melt spin index (MSI) of about 30 to about 200, for example, about 32 to about 74, about 74 to about 116, about 116 to about 158, or about 158 ​​to about 198 according to the following formula 1:

[0023] [Formula 1]

[0024]

[0025] (In Equation 1, MI is the melting index of polyethylene (ASTM D 1238, 190℃, 2.16kg) (unit: g / 10 min), OIT is the oxidative induction time (unit: min) at a temperature of 210 to 230℃ by a rotational rheometer, P is the content of polypropylene (weight %), and G is 1 m 2 (The number of gels larger than 400 ㎛)

[0026] 9. In the above 1-8 specific examples, the polyethylene is 1 m 2 The number of gels of about 400 μm or more may be less than about 150, for example, about 1 to about 40, about 40 to about 80, or about 80 to about 140.

[0027] 10. In the above 1-9 specific examples, the polyethylene has a tensile strength of about 270 Kg / cm as measured by ASTM D638 standard. 2 For example, About 272 to about 278 kg / cm 2 , about 278 to about 284 Kg / cm 2 , About 284 to about 290 kg / cm 2 , About 290 to about 298 Kg / cm 2 It could be.

[0028] 11. In the above 1-10 specific examples, the polyethylene is characterized in being used for melt spinning.

[0029] 12. Another aspect of the present invention relates to a polyethylene fiber. The polyethylene fiber is formed by melt spinning the polyethylene of any one of the above-mentioned embodiments 1-11.

[0030] 13. In the above 12 specific examples, the polyethylene fiber may have a diameter of greater than about 0 and less than about 100 μm, for example, from about 1 to about 25 μm, from about 25 to about 50 μm, from about 50 to about 75 μm, or from about 75 to about 99 μm.

[0031] 14. Another aspect of the present invention relates to a nonwoven fabric. The nonwoven fabric may be formed from the polyethylene fibers of the 12 specific examples.

[0032] 15. Another aspect of the present invention relates to a method for producing polyethylene. The method comprises a step of polymerizing ethylene in the presence of a Ziegler-Natta catalyst.

[0033] 16. In the above 15 specific examples, the method is characterized in that the polymerization is performed by controlling the particle size of the Ziegler-Natta catalyst to less than about 60 ㎛, for example, about 1 to about 15 ㎛, about 15 to about 30 ㎛, about 30 to about 45 ㎛, or about 45 to about 59 ㎛.

[0034] 17. In the above 15-16 specific examples, the method may be to polymerize by adding propylene monomer in an amount of about 0 to about 5 wt%, for example, about 1 to about 3 wt%, preferably about 1.1 to about 2 wt%, of the total monomer content.

[0035] 18. Another aspect of the present invention relates to a method for preventing single-filament yarns during melt spinning of polyethylene. The method is characterized by using polyethylene polymerized by controlling the particle size of a Ziegler-Natta catalyst.

[0036] 19. In the above 18 specific examples, the polyethylene may have an oxidative induction time of 10 minutes or more, for example, about 10 to 20 minutes, and in a specific example, about 10 to 15 minutes, at a temperature of about 210 to about 230°C using a rotational rheometer.

[0037] 20. In the above 18-19 specific examples, the polyethylene has a weight average molecular weight of about 40,000 g / mol to about 60,000 g / mol, for example, about 41,000 to about 45,000 g / mol, about 45,000 to about 49,000 g / mol, about 49,000 to about 53,000 g / mol, or about 53,000 to about 59,000 g / mol, and may have a polydispersity index (PDI) of 7 or more.

[0038]

[0039] The present invention provides polyethylene having excellent melt spinning processability, heat resistance, adhesiveness and tensile strength, and significantly reducing gel formation in the melt spinning process, and a method for producing the same, and fibers and nonwoven fabrics formed by melt spinning the polyethylene, and has the effect of providing a method for preventing single yarns during melt spinning of polyethylene.

[0040]

[0041] Figure 1 is a surface photograph of a polyethylene nonwoven fabric manufactured in Example 1-3 and Comparative Example 1-2.

[0042] Figure 2 shows the gel permeation chromatography (GPC) measurement results of polyethylene manufactured in Example 1-3 and Comparative Example 1-2.

[0043] Figure 3 shows the results of measuring the oxidation induction time of polyethylene manufactured in Example 1-3 and Comparative Example 1-2.

[0044] Figure 4 shows the NMR measurement results of Example 1.

[0045] Figure 5 shows the NMR measurement results of Comparative Example 1.

[0046]

[0047] Hereinafter, the present invention will be described in more detail. In the present specification, where the terms "includes," "has," and "consists of," are used, other parts may be added, unless "only" is used. When a component is expressed in the singular, it also includes the plural, unless otherwise explicitly stated.

[0048] When interpreting a component, it is interpreted as including the error range even if there is no separate explicit description.

[0049]

[0050] polyethylene

[0051] One aspect of the present invention relates to polyethylene. The polyethylene may have an oxidative induction time of about 10 minutes or more, for example, about 10 to 20 minutes, and in a specific example, about 10 to 15 minutes, at a temperature of about 210 to about 230°C as measured by a rotational rheometer. Within this range, the polyethylene has excellent heat resistance and processability, and does not cause single fibers during melt spinning.

[0052] The polyethylene may exhibit a peak corresponding to polypropylene in NMR measurements. In specific examples, the polyethylene may comprise from about 0 to about 5 wt%, for example, from about 1 to about 3 wt%, and preferably from about 1.1 to about 2 wt%, of polypropylene. Within this range, the polyethylene may exhibit excellent heat resistance and processability.

[0053] In a specific example, the polyethylene may have a weight average molecular weight of about 40,000 g / mol to about 60,000 g / mol, in a specific example, about 42,000 to about 56,000 g / mol, for example, about 41,000 to about 45,000 g / mol, about 45,000 to about 49,000 g / mol, about 49,000 to about 53,000 g / mol, or about 53,000 to about 59,000 g / mol. Within the above range, the polyethylene may have a balance of heat resistance and melting spinnability.

[0054] In a specific example, the polyethylene is 1 m 2 The number of gels having a maximum diameter of about 400 ㎛ or more may be less than about 150, in specific examples about 1 to about 140, preferably about 1 to about 100, for example about 1 to about 40, about 40 to about 80, or about 80 to about 140. In addition, the polyethylene may have a diameter of 1 m 2 The total number of gels may be less than about 1600, for example, about 1 to about 1,000, in specific examples, about 1 to about 400, about 400 to about 800, about 800 to about 1200, or about 1200 to about 1600. In this range, no single yarn occurs during melt spinning.

[0055] The polyethylene may have a melt index (ASTM D 1238, 190°C, 2.16 kg) of about 15 to about 40 g / 10 min, preferably about 20 to about 38 g / 10 min, for example, about 15.5 to about 20 g / 10 min, about 20 to about 25 g / 10 min, about 25 to about 30 g / 10 min, or about 30 to about 38.5 g / 10 min. In the above range, the extrusion processability is excellent and web formation is advantageous.

[0056] In a specific example, the polyethylene has a melt flow rate (MFR, 190°C, MI 21.6 / MI 2.16) may be from about 20 to about 30, for example from about 22 to about 25. In a specific example, the melt flow rate (MFR, 190°C, MI 21.6 / MI 2.16 ) can be from about 20.5 to about 29.5, for example, from about 20.5 to about 23.5, from about 23.5 to about 26.5, from about 26.5 to about 29.5. It has excellent processability in the above range.

[0057] In a specific example, the polyethylene has a density of about 0.948 to about 0.965 g / cm 3 , preferably about 0.950 to about 0.960 g / cm 3 It can be. In a specific example, the density is about 0.950 to about 0.963 g / cm 3 , For example, about 0.950 to about 0.953 g / cm 3 , About 0.953 to about 0.956 g / cm 3 , about 0.956 to about 0.960 g / cm 3 , about 0.960 to about 0.963 g / cm 3 It could be.

[0058] In addition, the melt spin index (MSI) according to the following formula 1 may be about 30 to about 200, preferably about 35 to about 150. In a specific example, the melt spin index (MSI) may be about 32 to about 198, for example, about 32 to about 74, about 74 to about 116, about 116 to about 158, or about 158 ​​to about 198:

[0059] [Formula 1]

[0060]

[0061] (In Equation 1, MI is the melting index of polyethylene (ASTM D 1238, 190℃, 2.16kg) (unit: g / 10 min), OIT is the oxidative induction time (unit: min) at a temperature of 210 to 230℃ by a rotational rheometer, P is the content of polypropylene (weight %), and G is 1 m 2 (The number of gels larger than 400 ㎛)

[0062]

[0063] In addition, the polyethylene has a tensile strength of about 270 Kg / cm as measured by ASTM D638 standard. 2 Ideally, for example, about 270 to about 300 Kg / cm 2 It can be. In a specific example, the tensile strength is about 272 to about 298 Kg / cm 2 , for example, About 272 to about 278 kg / cm 2 , about 278 to about 284 Kg / cm 2 , About 284 to about 290 kg / cm 2 , About 290 to about 298 Kg / cm 2 It could be.

[0064] Polyethylene according to the above specific example can be manufactured by the following manufacturing method.

[0065]

[0066] Polyethylene manufacturing method

[0067] The above polyethylene comprises a step of polymerizing ethylene in the presence of a Ziegler-Natta catalyst.

[0068] In one specific example, the Ziegler-Natta catalyst comprises (i) a Ziegler-Natta pro-catalyst for olefin polymerization comprising a titanium compound represented by the following formula 1, a magnesium compound represented by the following formula 2, and an internal electron donor; (ii) an organoaluminum compound represented by the following formula 7; and (iii) an external electron donor represented by the following formula 3, wherein the internal electron donor comprises a mixture of a first internal electron donor represented by the following formula 4; a second internal electron donor represented by the following formula 5; and a third internal electron donor represented by the following formula 6, wherein a molar ratio of the external electron donor to the mixture is about 115 to about 130. In specific examples, the molar ratio may be from about 117 to about 128, for example, from about 117 to about 121, from about 121 to about 125, from about 125 to about 128:

[0069] [Chemical Formula 1]

[0070] TiX n (OR 1 ) 4-n

[0071] (In the above chemical formula 1,

[0072] R 1 C1-C substituted or unsubstituted 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One species selected from the group consisting of aryl groups,

[0073] X is a halogen atom,

[0074] n is an integer from 0 to 4, and

[0075] In the above substitution or non-substitution, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group.

[0076] [Chemical Formula 2]

[0077] Mg(OR 2 ) k X 2-k

[0078] (In the above chemical formula 2,

[0079] R 2 C1-C substituted or unsubstituted 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One species selected from the group consisting of aryl groups,

[0080] X is a halogen atom,

[0081] k is an integer from 0 to 2, and

[0082] In the above substitution or non-substitution, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group.

[0083] [Chemical Formula 3]

[0084]

[0085] (In the above chemical formula 3,

[0086] L1 and L2 are each independently substituted or unsubstituted C1-C 20 An alkyl group, and in the above substituted or unsubstituted, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group,

[0087] L3 and L4 are each independently substituted or unsubstituted C1-C 20 Alkyl group and substituted or unsubstituted C3-C 20 One species selected from the group consisting of cycloalkyl groups,

[0088] In the above substitution or non-substitution, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group.

[0089] [Chemical Formula 4]

[0090]

[0091] (In the above chemical formula 4,

[0092] R 3 C1-C substituted or unsubstituted 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One selected from the group consisting of aryl groups, and in the above substituted or unsubstituted, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group,

[0093] R 4 and R 5 are each independently branched C1-C 20 alkyl group,

[0094] m is an integer from 0 to 4)

[0095] [Chemical Formula 5]

[0096]

[0097] (In the above chemical formula 5,

[0098] R 6 is independently, substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One selected from the group consisting of aryl groups, and in the above substituted or unsubstituted, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group,

[0099] R 7 is a straight chain C1-C 20 alkyl group,

[0100] R 8 C1-C of branched chain 20 alkyl group,

[0101] n is an integer from 0 to 4)

[0102] [Chemical Formula 6]

[0103]

[0104] (In the above chemical formula 6,

[0105] R 9 are each independently substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One selected from the group consisting of aryl groups, and in the above substituted or unsubstituted, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group,

[0106] R 10 and R 11 are each independently straight-chain C1-C 20 alkyl group,

[0107] p is an integer from 0 to 4),

[0108] [Chemical Formula 7]

[0109] Al(R 13 ) p X 3-p

[0110] (In the above chemical formula 7,

[0111] R 13 Silver hydrogen atom, substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One species selected from the group consisting of aryl groups,

[0112] X is a halogen atom,

[0113] p is an integer from 0 to 3, and

[0114] In the above substitution or non-substitution, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group.

[0115] According to one embodiment, the catalyst may include one type of external electron donor represented by the chemical formula 3, i.e., the first external electron donor alone or the second external electron donor alone.

[0116] According to one embodiment, the catalyst may be a mixture comprising two types of external electron donors represented by the above chemical formula 3. In one specific embodiment, the catalyst may be a mixture of the first external electron donor and the second external electron donor. For example, in 10 moles of the mixture, the first external electron donor: the second external electron donor may be included in a molar ratio of about 3:7 to about 7:3, a molar ratio of about 4:6 to about 6:4, or a molar ratio of about 5:5.

[0117] In one specific embodiment, L1 and L2 are each independently substituted or unsubstituted C1-C 10 An alkyl group, for example, a substituted or unsubstituted C1-C5 alkyl group.

[0118] In one specific example, the first external electron donor may be represented by the following chemical formula 3-1, and the second external electron donor may be represented by the following chemical formula 3-2:

[0119] [Chemical Formula 3-1]

[0120]

[0121] [Chemical Formula 3-2]

[0122]

[0123] According to one embodiment, the external electron donor may be included in an amount of about 30 wt% to about 50 wt%, based on 100 wt% of the total Ziegler-Natta catalyst for olefin polymerization. In a specific example, the amount may be about 32 wt% to about 48 wt%, for example, about 32 wt% to about 36 wt%, about 36 wt% to about 40 wt%, about 40 wt% to about 44 wt%, or about 44 wt% to about 48 wt%. In the above amount range, the stability of the catalyst active site may be high, and there may be no problem of activity reduction due to poisoning of the catalyst active site.

[0124] According to one embodiment, the external electron donor represented by the above chemical formula 3 may be included in an amount of about 95 wt% or more, preferably about 99 wt% to about 100 wt%, and more preferably about 100 wt%, based on 100 wt% of the total external electron donor contained in the Ziegler-Natta catalyst. Within this range, the effect of the present invention may be easily achieved. Here, the 'total external electron donor' may refer to a compound that is independently included compared to the main catalyst in the olefin Ziegler-Natta catalyst, and is known to those skilled in the art to play a role in stabilizing the catalytic active site of the titanium compound.

[0125] The internal electron donor is selected so that, when the external electron donor is included in the olefin-Ziegler-Natta catalyst, the polyolefin with excellent processability, i.e., satisfies a specific range of density, melt index, and melt index ratio. The internal electron donor provides various active sites when the external electron donor is applied, thereby enabling the production of a polyolefin resin with excellent processability.

[0126] In the present invention, the external electron donor comprises a mixture of a first internal electron donor represented by the chemical formula 4; a second internal electron donor represented by the chemical formula 5; and a third internal electron donor represented by the chemical formula 6, and the molar ratio of the external electron donor to the mixture is about 115 to about 130. In a specific example, the molar ratio may be about 117 to about 128, for example, about 117 to about 121, about 121 to about 125, or about 125 to about 128.

[0127] In one specific example, in the chemical formula 4, R 4 and R 5 is independently, branched-chain C3-C 10 An alkyl group, a C3-C5 alkyl group. For example, in the above chemical formula 4, R 4 and R 5 is independently branched C3-C 10 It may be an alkyl group, a C3-C5 alkyl group. The first internal electron donor represented by the above chemical formula 4 may include at least one compound represented by any one of the chemical formulas 4-1 to 4-3 below:

[0128] [Chemical Formula 4-1]

[0129]

[0130] [Chemical Formula 4-2]

[0131]

[0132] [Chemical Formula 4-3]

[0133]

[0134] In one specific example, in the chemical formula 5, R 7 is a straight chain C1-C 10 It may be an alkyl group, or a straight-chain C1-C5 alkyl group. In the above chemical formula 5, R 8 C2-C of branched chain 10It may be an alkyl group, a C2-C5 alkyl group. For example, in the above chemical formula 5, R 8 C2-C, branched at the terminal end 10 It may be an alkyl group, a C2-C5 alkyl group. For example, the second internal electron donor represented by the above chemical formula 5 may include at least one compound represented by any one of the chemical formulas 5-1 to 5-4 below:

[0135] [Chemical Formula 5-1]

[0136]

[0137] [Chemical Formula 5-2]

[0138]

[0139] [Chemical Formula 5-3]

[0140]

[0141] [Chemical Formula 5-4]

[0142]

[0143] In one specific example, in the chemical formula 6, R 10 and R 11 are each independently straight-chain C1-C 10 An alkyl group may be a straight-chain C1-C5 alkyl group. For example, the third internal electron donor represented by the above chemical formula 6 may include at least one compound represented by any one of the chemical formulas 6-1 to 6-3 below:

[0144] [Chemical Formula 6-1]

[0145]

[0146] [Chemical Formula 6-2]

[0147]

[0148] [Chemical Formula 6-3]

[0149]

[0150] According to one embodiment, the mixture of the first internal electron donor, the second internal electron donor, and the third internal electron donor may be included in an amount of about 95 wt% or more, preferably about 99 wt% to about 100 wt%, and more preferably about 100 wt%, based on 100 wt% of the total internal electron donors contained in the Ziegler-Natta catalyst.

[0151] The titanium compound and the external electron donor may be included in a molar ratio of about 1:3 to about 1:9, preferably, a molar ratio of about 1:4 to about 1:8. In specific examples, the molar ratio may be about 1:3.2 to about 1:8.8, for example, about 1:3.2 to about 1:4.6, about 1:4.6 to about 1:6, about 1:6 to about 1:7.4, or about 1:7.4 to about 1:8.8. In the above molar ratio range, the stability of the catalytic active site may be excellent, and there may be no problem of the catalytic activity being reduced due to poisoning of the catalytic active site.

[0152] According to another specific example, the Ziegler-Natta catalyst comprises a Ziegler-Natta pro-catalyst for olefin polymerization, comprising a titanium compound represented by the above formula 1, a magnesium compound represented by the above formula 2, and an internal electron donor; an organoaluminum compound represented by the following formula 7; and an external electron donor represented by the following formula 3, wherein the internal electron donor is a mixture of a first internal electron donor selected from among the following formulas 8, 5, and 9; and a second internal electron donor selected from among the above formulas 8, 5, and 9 and different from the first internal electron donor, wherein the first internal electron donor: the second internal electron donor is included in a molar ratio of about 3:7 to about 7:3 in 10 mol of the mixture. In specific examples, the molar ratio may be about 3.5:6.5 to about 6.5:3.5, for example, about 4:6 to about 6:4, about 4.5:5.5 to about 5.5:4.5, about 5:5:

[0153] [Chemical Formula 8]

[0154]

[0155] (In the above chemical formula 8,

[0156] R 31 , R 32 , R 33 and R 34 are each independently hydrogen, substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One selected from the group consisting of aryl groups, or R 31 and R 33 are linked to each other, substituted or unsubstituted C3-C 20 Can form a cycloalkyl group,

[0157] R 4 and R5 is independently, substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One species selected from the group consisting of aryl groups,

[0158] In the above substitution or non-substitution, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group.

[0159] [Chemical Formula 5]

[0160]

[0161] (In the above chemical formula 5,

[0162] R 6 , R 7 and R 8 is independently, substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One species selected from the group consisting of aryl groups,

[0163] n is an integer from 0 to 4, and

[0164] In the above substitution or non-substitution, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group.

[0165] [Chemical Formula 9]

[0166]

[0167] (In the above chemical formula 9,

[0168] R 9 and R 10 are each independently hydrogen, substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20One selected from the group consisting of aryl groups, or R 9 and R 10 are connected to each other, substituted or unsubstituted C3-C 20 Can form a cycloalkyl group,

[0169] R 11 and R 12 are each independently substituted or unsubstituted C1-C 20 Alkyl group, substituted or unsubstituted C3-C 20 Cycloalkyl group, and substituted or unsubstituted C3-C 20 One species selected from the group consisting of aryl groups,

[0170] In the above substitution or non-substitution, the substituent is independently at least one selected from the group consisting of a halogen group, a cyano group, a nitro group, and a C1-C8 alkyl group.

[0171] In specific examples, the first internal electron donor: the second internal electron donor may be included in a molar ratio of about 3:7, about 3.5:6.5, about 4:6, about 4.5:5.5, about 5:5, about 5.5:4.5, about 6:4, about 6.5:3.5, or about 7:3.

[0172] In a specific example, the compound of the above chemical formula 8 is a diethyl diester compound and may include at least one of the compounds represented by any one of the chemical formulas 8-1 to 8-7 below:

[0173] [Chemical Formula 8-1]

[0174]

[0175] [Chemical Formula 8-2]

[0176]

[0177] [Chemical Formula 8-3]

[0178]

[0179] [Chemical Formula 8-4]

[0180]

[0181] [Chemical Formula 8-5]

[0182]

[0183] [Chemical Formula 8-6]

[0184]

[0185] [Chemical Formula 8-7]

[0186]

[0187]

[0188] The compound of the above chemical formula 9 is a diethyl diester compound, and may include at least one compound represented by any one of the chemical formulas 9-1 to 9-4 below:

[0189] [Chemical Formula 9-1]

[0190]

[0191] [Chemical Formula 9-2]

[0192]

[0193] [Chemical Formula 9-3]

[0194]

[0195] [Chemical Formula 9-4]

[0196]

[0197]

[0198] According to one embodiment, for 1 mole of the external electron donor, the internal electron donor, i.e., the mixture, may be included in an amount of about 0.002 to about 0.008 moles, preferably about 0.003 to about 0.004 moles or about 0.007 to about 0.008 moles. Within this range, polyethylene satisfying the above-described density, melt index, and melt index ratio may be easily produced.

[0199] In a specific example, the polymerization can be performed by controlling the particle size of the catalyst to less than 60 μm. The particle size refers to the particle diameter measured using a scanning electron microscope (SEM). In a specific example, the particle diameter is greater than about 0 and less than about 60 μm, preferably about 0.01 to about 50 μm, for example, about 0.01 to about 2 μm, about 2 to about 14 μm, about 14 to about 26 μm, about 26 to about 38 μm, or about 38 to about 50 μm. By controlling the particle size within the above range and performing polymerization, heat resistance, melt processability, and adhesive performance can be secured.

[0200] Specifically, the propylene monomer can be polymerized together in an amount of about 0 to about 5 wt%, for example, about 1 to about 3 wt%, preferably about 1.1 to about 2 wt%, of the total monomers. Within the above range, excellent heat resistance and processability can be secured simultaneously.

[0201] Additionally, as needed, conventional additives may be added before / after polymerization within a range that does not impede the purpose of the invention.

[0202] The polyethylene manufactured above can be manufactured into a fiber form by melt spinning. The polyethylene of the present invention has an oxidative induction time of about 10 minutes or more, for example, about 10 to 20 minutes, and in a specific example, about 10 to 15 minutes, at a temperature of about 210 to about 230°C by a rotational rheometer, and a peak corresponding to polypropylene exists in NMR measurement, so that the melt spinnability is excellent and single yarns do not occur. Since the melt spinnability is excellent in this way, fibers having a diameter of more than about 0 and less than about 100 ㎛, for example, about 1 to about 25 ㎛, about 25 to about 50 ㎛, about 50 to about 75 ㎛, and about 75 to about 99 ㎛ can also be manufactured.

[0203] The above polyethylene fiber can be used to manufacture a non-woven fabric, and according to a specific example, the non-woven fabric can minimize fluffing and have excellent adhesive properties.

[0204] Another aspect of the present invention relates to a method for preventing single yarn during melt spinning of polyethylene. Conventionally, a method of increasing the low molecular weight ratio was used for melt spinning, but this had the problem of single yarn occurring. In the present invention, single yarn can be prevented during melt spinning by using polyethylene polymerized by controlling the particle size of the Ziegler-Natta catalyst. In a specific example, the polyethylene has an oxidative induction time of about 10 minutes or more, for example, about 10 to 20 minutes, and in a specific example, about 10 to 15 minutes, as determined by a rotational rheometer, and has the characteristics of the presence of a peak corresponding to polypropylene when measured by NMR.

[0205]

[0206] Hereinafter, the present invention will be described in more detail through examples, but these examples are for the purpose of explanation only and should not be construed as limiting the present invention.

[0207]

[0208] Example

[0209] Manufacturing example: Synthesis of Ziegler-Natta catalyst

[0210] 4 g of magnesium compound Mg(OC2H5)2 carrier and 48 ml of titanium compound TiCl were added to 12 ml of toluene, and a mixture of internal electron donors, including compounds of chemical formula 4-1 (4.5 mmol), chemical formula 5-1 (0.45 mmol), chemical formula 6-1 (0.45 mmol), chemical formula 6-2 (0.45 mmol), and chemical formula 6-3 (0.45 mmol), was added to prepare a main catalyst. Then, 0.18 ml of chemical formula 3-2 as an external electron donor and 2 mmol of triethylaluminum (2 ml of 1 M hexane solution), which is an organoaluminum compound (cocatalyst), were additionally added, and a Ziegler-Natta catalyst was prepared while stirring at 300 rpm.

[0211]

[0212] Examples 1-3

[0213] The Ziegler-Natta catalyst manufactured in the above manufacturing example was selected to have a particle size of less than 60㎛, and ethylene was polymerized, and propylene monomer was added in the amount shown in Table 1 to polymerize polyethylene. The manufactured polyethylene was melt-spun under extrusion conditions of 230-250℃ to manufacture polyethylene fiber. The properties of the manufactured polyethylene fiber were measured using the following property evaluation method, and the results are shown in Table 1:

[0214]

[0215] Comparative examples 1-2

[0216] The same procedure as Example 1 was followed except that propylene was not added.

[0217]

[0218] Comparative Example 3

[0219] The same procedure as Example 1 was followed, except that the particle size of the catalyst manufactured in the manufacturing example was not controlled. The particle size distribution of the catalyst was D10 of 10 μm, D50 of 62 μm, and D90 of 100 μm.

[0220]

[0221] Sample name Units Comparative example 1 Comparative example 2 Comparative example 3 Example 1 Example 2 Example 3 MI (190℃) g / 10 min 19 20 1.1 20 24 35 MFR (190℃) -26 21 25 24 24 23 Density g / cm 3 0.9560.9570.9540.9540.9550.956NMRPP content (wt%)--1.51.51.21.4Tm℃132131134129130130Tc℃117113118118118118Mwg / mol65,67154,873124,50055,91452,84445,065PDI-6.74.58.57.47.39.4UTM tensile strengthKg / cm 2 266273-282295270OIT(Oxidation stability)min7.750.759.511.011.810.3Gel>400㎛, 1m 2 ea17979512810236136Total, 1m 2 ea1,1229,6463,4201,5158991,457 Thermal Adhesive XXXOOO Melt Spread Index (MSI) -001.1635.6111.438.2

[0222]

[0223] Physical property evaluation method

[0224] (1) Melting index (MI, g / 10min): Melting index (MI) at 190℃ with a load of 2.16kg according to ASTM D 1238 2.16 ) was measured.

[0225] (2) Melt Flow Index (MFR): Melt flow index (MI) at 190℃ with a load of 21.6 kg according to ASTM D 1238 21.6 ) after measuring MI 21.6 / MI 2.16 was saved by

[0226] (3) Density: Density of polyethylene (g / cm) according to ASTM D 1505 standard 3 ) was measured.

[0227] (4) NMR: The presence and content of peaks corresponding to polypropylene were confirmed by measuring NMR of polyethylene. The NMR results of Example 1 and Comparative Example 1 are shown in Figures 4 and 5, respectively.

[0228] (5) Tm and Tc: The melting point and crystallization temperature were obtained using differential scanning calorimetry (DSC), respectively.

[0229] (6) Weight average molecular weight and PDI: 5 mg of the sample was dissolved in 2 ml of chloroform as a solvent, and the weight average molecular weight and number average molecular weight were measured using gel permeation chromatography (GPC). Then, the molecular weight distribution (PDI, Mw / Mn) was calculated by dividing the weight average molecular weight by the number average molecular weight. The GPC measurement results are shown in Fig. 2.

[0230] (7) Tensile strength (Kg / cm) 2 ) : Measured according to ASTM D638 standard.

[0231] (8) OIT (Oxidative Induction Time): Oxidative induction time was measured at a temperature of 210 to 230°C using a rotational rheometer. The time sweep results are shown in Fig. 3.

[0232] (9) Gel: After extruding the evaluation resin with a T-die, use a gel foreign matter detector to detect 1 m 2 The number of gels with a maximum diameter of 400 ㎛ or more and the total number of gels were obtained.

[0233] (10) Thermal adhesiveness: After radiation, when thermally bonding, the presence or absence of separation of the boundary surface was judged using SEM. If separation of the boundary surface occurred, it was evaluated as X, and if separation of the boundary surface did not occur, it was evaluated as O.

[0234] (11) Melt Spinning Index (MSI): The calculated value was obtained using Equation 1 below.

[0235] [Formula 1]

[0236]

[0237] (In Equation 1, MI is the melting index of polyethylene (ASTM D 1238, 190℃, 2.16kg) (unit: g / 10 min), OIT is the oxidative induction time (unit: min) at a temperature of 210 to 230℃ by a rotational rheometer, P is the content of polypropylene (weight %), and G is 1 m 2 (The number of gels larger than 400 ㎛)

[0238]

[0239] From the results in Table 1 above, it can be seen that the polyethylene of the present invention has a balance of heat resistance, excellent melt spinnability, adhesiveness, and tensile strength compared to Comparative Examples 1-3.

[0240]

[0241] A nonwoven fabric was produced using the polyethylene fibers of Example 1-3 and Comparative Example 1-2, and a surface photograph is shown in Fig. 1. As shown in Fig. 1, it can be confirmed that a large amount of fluff was generated on the surface of Comparative Example 1-2 compared to Example 1-3.

[0242]

[0243] Simple modifications or changes of the present invention can be easily implemented by a person having ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

[0244]

[0245] The present invention provides polyethylene having excellent melt spinning processability, heat resistance, adhesiveness and tensile strength, and significantly reducing gel formation in the melt spinning process, and a method for producing the same, and fibers and nonwoven fabrics formed by melt spinning the polyethylene, and has the effect of providing a method for preventing single yarns during melt spinning of polyethylene.

Claims

1. The oxidation induction time is 10 minutes or more at a temperature of 210 to 230℃ using a rotational rheometer, Polyethylene that exhibits peaks corresponding to polypropylene in NMR measurements.

2. In the first paragraph, the polyethylene has a weight average molecular weight of 40,000 g / mol to 60,000 g / mol and a polydispersity index (PDI) of 7 or more.

3. In the first paragraph, the polyethylene is polyethylene containing more than 0 and less than 5 wt% of polypropylene.

4. In the first paragraph, the polyethylene is 1 m 2 Polyethylene having less than 150 gels each having a maximum diameter of 400 ㎛ or more.

5. In the first paragraph, the polyethylene has a melting index (ASTM D 1238, 190°C, 2.16 kg) of 15 to 40 g / 10 min.

6. In the first paragraph, the polyethylene has a melt flow rate (MFR, 190°C, MI) 21.6 / MI 2.16 ) polyethylene having a molecular weight of 20 to 30.

7. In the first paragraph, the polyethylene has a density of 0.948 to 0.965 g / cm. 3 in polyethylene.

8. In the first paragraph, the polyethylene is polyethylene having a melt spin index (MSI) of 30 to 200 according to the following formula 1: [Formula 1] (In Equation 1, MI is the melting index of polyethylene (ASTM D 1238, 190℃, 2.16kg) (unit: g / 10 min), OIT is the oxidative induction time (unit: min) at a temperature of 210 to 230℃ by a rotational rheometer, P is the content of polypropylene (weight%), and G is 1 m 2 (The number of gels larger than 400 ㎛) 9. In the first paragraph, the polyethylene is 1 m 2 Polyethylene having less than 150 gels of 400 ㎛ or more in size.

10. In the first paragraph, the polyethylene has a tensile strength of 270 Kg / cm as measured by ASTM D638 standard. 2 Ideal polyethylene.

11. In the first paragraph, the polyethylene is polyethylene used for melt spinning.

12. A polyethylene fiber formed by melt spinning the polyethylene of any one of claims 1 to 11.

13. In the 12th paragraph, the polyethylene fiber is a polyethylene fiber having a diameter of more than 0 and less than 100 ㎛.

14. Nonwoven fabric formed from polyethylene fibers of clause 12.

15. A method for producing polyethylene according to any one of claims 1 to 11, wherein the method comprises a step of polymerizing ethylene in the presence of a Ziegler-Natta catalyst.

16. In the 15th paragraph, the method is a method for producing polyethylene by controlling the particle size of the Ziegler-Natta catalyst to less than 60㎛.

17. In clause 15, the method is a method for producing polyethylene by polymerizing propylene monomer by adding more than 0 wt% and less than 5 wt% of the total monomer content.

18. A method for preventing single-filament spun during melt spinning of polyethylene, wherein the method is: A method characterized by using polyethylene polymerized by controlling the particle size of a Ziegler-Natta catalyst.

19. In paragraph 18, the polyethylene is, The oxidation induction time is 10 minutes or more at a temperature of 210 to 230°C by a rotational rheometer, A method wherein a peak corresponding to polypropylene exists in NMR measurement.

20. A method according to claim 18, wherein the polyethylene has a weight average molecular weight of 40,000 g / mol to 60,000 g / mol and a polydispersity index (PDI) of 7 or more.

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