Polyolefin polymer, and system and method for polyolefin polymerization

Abstract

The present invention relates to a polyolefin polymer, and a system and method for polymerizing same, the polymer having a density of 0.868 to 0.897 g / cm3, a melt flow index (MIE, 190°C with a load of 2.16 kg) of 0.1 g / 10 min to 20.0 g / 10 min, a PDI of 1 to 5, a number average molecular weight (Mn) of 20,000 to 70,000 g / mol, a weight average molecular weight (Mw) of 50,000 to 150,000 g / mol, and two or more melting temperatures (Tm).

Description

Polyolefin polymer, polyolefin polymerization system and polymerization method

[0001] Cross-citation with related applications

[0002] The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0124786 dated September 12, 2024 and the benefit of priority based on Korean Patent Application No. 10-2025-0129745 dated September 11, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of the specification.

[0003] Technology field

[0004] The present invention relates to a polyolefin polymer, a polymerization system of polyolefins, and a polymerization method.

[0005] Linear Low-Density Polyethylene (LLDPE) is widely known to be produced through a gas-phase process using a fluidized bed reactor, specifically by copolymerizing an ethylene monomer and a comonomer in the presence of a catalyst.

[0006] Here, when manufacturing polymers such as linear low-density polyethylene, large comonomers with four or more carbon atoms are used relative to ethylene monomers. Because comonomers have low vapor pressure, they condense in the polymerization reactor and are absorbed into the polymer, causing the polymer to swell. Polymers containing large amounts of comonomers have low crystallinity and low melting points, resulting in sticky, wet resins within the polymerization reactor. Such adhesive polymers hinder fluidization due to their sticky properties within the reactor, which has a negative impact on the continuous operation of the gas-phase polymerization reactor.

[0007] U.S. Patent Publication 4,994,534 describes a process for producing sticky polymers, such as ethylene / propylene rubber, by adding silica or clay during polymerization. Adding these materials to a reactor not only produces polymers that cannot be used in various applications but can also cause contamination in heat exchangers, compressors, and other reactor systems.

[0008] Similarly, U.S. Patent 4,970,279 and International Patent WO 88 / 02379 describe a method of adding pulverized inorganic materials, such as silica or alumina, to a reactor. Additionally, U.S. Patents 5,100,979 and 5,106,926 describe a process for producing ethylene / 1-octene copolymers using specific titanium-based catalyst systems or specific vanadium-based catalyst systems that are not commercially available. Furthermore, U.S. Patent 5,017,665 describes a method for producing polymers with very low molecular weight and low density by producing ethylene / 1-butene / 1-4,hexadiene under a metallocene / aluminoxane catalyst system. Additionally, U.S. Patent 5,712,353 describes a method for producing relatively high molecular weight and low density elastomers using a metallocene catalyst. This method produced elastomers with high molecular weight and low density at temperatures above 50°C, but due to the characteristics of the elastomers, such as their low melting point and sticky nature, there was a very high possibility of process problems occurring that made continuous operation difficult when produced at high temperatures.

[0009] In addition, conventionally, when polymer materials manufactured in granular form (powder, pellets, etc.) are stored for a long period or exposed to high temperatures and humidity, a phenomenon known as caking frequently occurs, in which individual particles stick together to form agglomerates. When caking occurs, the free flowability of the particles is reduced, causing blockages or uneven supply during transfer and feeding processes, which impairs the stability of subsequent processing processes such as extrusion, injection, and molding. Furthermore, there were problems such as difficulty in uniform mixing due to fusion between particles and a decrease in product quality.

[0010] Furthermore, conventionally, a jacket was installed on the exterior of the reactor to remove internal heat, and heat was removed through heat exchange with cooling water supplied to the jacket. However, to ensure sufficient removal of reaction heat, the surface area where heat exchange occurs must be large, which inevitably led to the problem of the external jacket becoming excessively long.

[0011] [Prior Art Literature]

[0012] [Patent Literature]

[0013] (Patent Document 1) 1. U.S. Published Patent 4,994,534

[0014] (Patent Document 2) 2. U.S. Published Patent 4,970,279

[0015] (Patent Document 3) 3. International Published Patent WO 88 / 02379

[0016] (Patent Document 4) 4. U.S. Published Patent 5,100,979

[0017] (Patent Document 5) 5. U.S. Published Patent 5,106,926

[0018] (Patent Document 6) 6. U.S. Published Patent 5,017,665

[0019] (Patent Document 7) 7. U.S. Published Patent 5,712,353

[0020] The present invention aims to prevent the problem of reduced process stability caused by stickiness when the surface of a polymer has a low density, which was a problem of the prior art.

[0021] The present invention has a density of 0.868 to 0.897 g / cm³ 3 And,

[0022] The melt flow index (MIE (2.16 kg load, 190℃)) is 0.1 g / 10 min to 20.0 g / 10 min, and

[0023] PDI is 1 to 5, and

[0024] The number average molecular weight (Mn) is 20,000 to 70,000 g / mol, and

[0025] The weight-average molecular weight (Mw) is 50,000 to 150,000 g / mol, and

[0026] Two or more melting temperatures (T m Provides a polyolefin polymer having ).

[0027] The above polyolefin polymer may be manufactured through a continuous process involving two or more reactions.

[0028] The above two or more reactions may include one or more gas-phase polymerization reactions.

[0029] The above melt flow index (MIE (2.16 kg load, 190°C)) may be 0.5 g / 10 min to 17.0 g / 10 min.

[0030] The above melting temperature (T m ) is the first melting temperature (T m1 ) and the second melting temperature (T m2 Having ), the first melting temperature (T m1 ) may be 45 ℃ to 85 ℃, and the second melting temperature may be 70 ℃ to 125 ℃.

[0031] The above first melting temperature (T m1) may be 55 ℃ to 75 ℃, and the second melting temperature may be 70 ℃ to 90 ℃.

[0032] The above first melting temperature (T m1 ) and the second melting temperature (T m2 The difference in ) may be between 10 ℃ and 40 ℃.

[0033] The above polyolefin polymer may have a melt flow index ratio (SR) of 15 to 25.

[0034] The above polyolefin polymer may show two or more peaks at a temperature of 31°C or higher in the temperature rising elution fraction (TREF) chromatogram, and the percentage value obtained by dividing the graph area at 60°C or higher by the total graph area may be 5% or higher.

[0035] The present invention has the effect of increasing the polymer production amount and ensuring process stability by manufacturing a polyolefin polymer having specific physical properties and including two or more reactions, particularly one or more gas-phase polymerization reactions.

[0036] In addition, the polyolefin polymer of the present invention has two distinct melting temperatures (T m1 and T m2 It is characterized by representing ). One of the two melting temperatures mentioned above (T m2 ) is higher T compared to the same density m It takes on a value, and such high T m Due to the value, the polyolefin polymer of the present invention prevents caking, making pellet processing and storage easier.

[0037] In addition, the polyolefin polymer of the present invention has a high melting temperature (T m2 By having ), it is possible to stably maintain a solid state compared to products of the same density, so it can be effectively applied to products that require maintaining a solid state.

[0038] FIG. 1 is a diagram showing the structure of a slurry polymerization reactor according to one embodiment of the present invention.

[0039] FIG. 2a is a figure showing the structure of a first slurry polymerization reactor and a first gas phase polymerization reactor according to one embodiment of the present invention.

[0040] FIG. 2b is a figure showing the structure of a first and second slurry polymerization reactor and a first gas phase polymerization reactor according to one embodiment of the present invention.

[0041] FIG. 2c is a figure showing the structure of a first slurry polymerization reactor and first and second gas phase polymerization reactors according to one embodiment of the present invention.

[0042] FIG. 2d is a figure showing the structure of a first and second slurry polymerization reactor and a first and second gas phase polymerization reactor according to one embodiment of the present invention.

[0043] FIG. 3 is a diagram showing the structure of a shell-and-tube heat exchanger according to one embodiment of the present invention.

[0044] Figure 4a is a cross-sectional SEM image of the prepolymer prepared in Example 2.

[0045] Figure 4b is a cross-sectional SEM image of the final polymer prepared in Example 2.

[0046] Figure 4c is an SEM image of the final polymer prepared in Example 2 before and after xylene dissolution.

[0047] Figure 5 is a temperature-raising elution fraction (TREF) chromatogram showing the TREF values ​​measured according to temperature for the final polymers prepared in Example 5 and Comparative Example 3.

[0048] Terms and words used in the description and claims of the present invention shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor may appropriately define the concept of the terms to best describe his invention.

[0049] In the present invention, the term 'stream' may refer to the flow of fluid within a process, and may also refer to the fluid itself flowing within the piping. Specifically, the 'stream' may simultaneously refer to the fluid itself flowing within the piping connecting each device and the flow of the fluid. Furthermore, the fluid may refer to a gas or a liquid, and does not exclude the inclusion of a solid component in the fluid.

[0050] The following embodiments are described in detail so that those skilled in the art can easily implement them. However, the embodiments may be implemented in various different forms and are not limited to the embodiments described herein.

[0051]

[0052] The present invention has a density of 0.868 to 0.897 g / cm³ 3 and, the melt flow index (MIE (2.16 kg load, 190°C)) is 0.1 g / 10 min to 20.0 g / 10 min, the PDI is 1 to 5, the number average molecular weight (Mn) is 20,000 to 70,000 g / mol, the weight average molecular weight (Mw) is 50,000 to 150,000 g / mol, and two or more melting temperatures (T m Provides a polyolefin polymer having ).

[0053] In one embodiment, the density of the polyolefin polymer is 0.868 to 0.897 g / cm³ 3 and preferably 0.870 to 0.893 g / cm³ 3 , more preferably 0.875 to 0.890 g / cm³ 3It may be. The above density may refer to the density of the polyolefin polymer measured by the density gradient method according to ASTM D1505. By having a density within the above range, a low-density polyolefin polymer can be provided.

[0054] In one embodiment, the melt flow index (MIE (2.16 kg load, 190°C)) of the polyolefin polymer may be 0.1 g / 10 min to 20.0 g / 10 min, preferably 0.5 g / 10 min to 17.0 g / 10 min, more preferably 0.6 g / 10 min to 10.0 g / 10 min, and most preferably 0.63 g / 10 min to 6.0 g / 10 min. The melt flow index (MIE (2.16 kg load, 190°C)) may refer to the melt flow index value of the polyolefin polymer measured according to ASTM D1238 under conditions of 190°C and a 2.16 kg load. By having a melt flow index within the above range, excellent process stability and processability may be achieved.

[0055] In one embodiment, the PDI of the polyolefin polymer is 1 to 5, preferably 1.2 to 4.8, and more preferably 1.5 to 4.5. The Polydispersity Index (PDI) refers to the value obtained by dividing the weight-average molecular weight (Mw) by the number-average molecular weight (Mn) (Mw / Mn). The PDI value is an indicator representing the molecular weight distribution of the polymer, and a value closer to 1 indicates a narrower molecular weight distribution. The PDI value can be measured using methods such as gel permeation chromatography (GPC), but is not limited thereto.

[0056] In addition, in one embodiment, the number average molecular weight (Mn) of the polyolefin polymer is 20,000 to 70,000 g / mol and the weight average molecular weight (Mw) is 50,000 to 150,000 g / mol, preferably the number average molecular weight (Mn) is 22,000 to 68,000 g / mol and the weight average molecular weight (Mw) is 62,000 to 138,000 g / mol, and more preferably the number average molecular weight (Mn) is 23,000 to 65,000 g / mol and the weight average molecular weight (Mw) is 65,000 to 135,000 g / mol.

[0057] In one embodiment, the polyolefin polymer has two or more melting temperatures (T m It has the melting temperature (T m ) may refer to the melting temperature of the polyolefin polymer measured in accordance with ASTM 3417-83. The polyolefin polymer has two or more melting temperature distributions; for example, the polyolefin polymer may have two to four, two to three, or two melting temperature distributions. Furthermore, the polyolefin polymer prepared by the method described herein, as well as the polyolefin polymer that is melted and processed or extruded into the form of pellets, still has two or more melting temperatures.

[0058] Specifically, the above melting temperature (T m ) is the first melting temperature (T m1 ) and the second melting temperature (T m2 Can have ).

[0059] The above first melting temperature (T m1 ) may be 45 ℃ to 85 ℃, preferably 50 ℃ to 80 ℃, more preferably 55 ℃ to 75 ℃. In addition, the second melting temperature (T m2 ) can be 70 ℃ to 125 ℃, preferably 70 ℃ to 120 ℃, more preferably 70 ℃ to 119 ℃.

[0060] The second melting temperature mentioned above is influenced by the density of the polymer synthesized in the slurry polymerization reaction, and the preferred range of the second melting temperature may vary depending on the density of the polymer. For example, the density of the polymer produced in the slurry polymerization reaction is 0.9 g / cm³ 3 If exceeded, the second melting temperature may preferably be 80°C to 125°C, more preferably 80°C to 120°C, and most preferably 80°C to 119°C, and the density of the polymer produced in the slurry polymerization reaction may be 0.9 g / cm³ 3 In the case of the following, the second melting temperature may preferably be 70°C to 90°C, more preferably 70°C to 85°C, and most preferably 70°C to 80°C.

[0061] The above first melting temperature (T m1 ) and the second melting temperature (T m2 The difference of ) can be 10 ℃ to 40 ℃, and as an example, 11 ℃ to 38 ℃, 12 ℃ to 35 ℃, and 13 ℃ to 33 ℃.

[0062] In one embodiment, the crystallization temperature (T) of the polyolefin polymer c ) may refer to the crystallization temperature of the polyolefin polymer measured in accordance with ASTM 3417-83, similar to the melting temperature mentioned above. The polyolefin polymer may have two or more crystallization temperature distributions. For example, the polyolefin polymer may have two to four, two to three, or two crystallization temperature distributions.

[0063] Specifically, the polyolefin polymer has a first crystallization temperature (T c1 ) and the second crystallization temperature (T c2It may have ). Here, the first crystallization temperature may be 40 ℃ to 100 ℃, 43 ℃ to 97 ℃, or 44 ℃ to 50 ℃. Also, the second crystallization temperature may be 70 ℃ to 110 ℃, 72 ℃ to 109 ℃, or 74 ℃ to 87 ℃.

[0064] The above polyolefin polymer may have a melt flow index ratio (SR) of 15 to 25, preferably 16 to 23.

[0065] The above polyolefin polymer may exhibit two or more peaks at a temperature of 31°C or higher in a temperature-raising elution fraction (TREF) chromatogram, and the percentage value obtained by dividing the graph area at 60°C or higher by the total graph area may be 5% or higher. The peaks may exhibit two or more, for example, two to five or two peaks, at a temperature of 31°C or higher, preferably 35°C or higher. In the temperature-raising elution fraction (TREF) chromatogram, the percentage value obtained by dividing the graph area at 60°C or higher by the total graph area may be 5% or higher, 5% to 55%, or 5% to 50%. As described above, it can be confirmed that the polyolefin polymer has a density gradient by showing two or more peaks in the temperature rise elution fraction (TREF) chromatogram, and the percentage value obtained by dividing the graph area above 60°C by the total graph area is 5% or more, confirming that a relatively high-density shell portion formed through the slurry polymerization reaction and eluted at high temperatures is well formed.

[0066] The above temperature rise elution fractionation (TREF) chromatogram may be obtained by analyzing the polyolefin polymer using cross-fractionation chromatography (CFC, PolymerChar CFC-2) equipment.

[0067] A polyolefin polymer according to one embodiment comprises a core portion and a shell portion, and the density of the core portion is 0.857 g / cm³ 3 Up to 0.910 g / cm³ 3 and the density of the shell portion is 0.890 g / cm³ 3 Up to 0.940 g / cm³ 3 And, the density of the shell portion may be higher than the density of the core portion.

[0068] As described above, the polyolefin polymer has a core-shell structure having a core portion and a shell portion surrounding the core portion, wherein the core portion and the shell portion have the density ranges described above, and the polyolefin polymer has a relatively high density in the shell portion, that is, on the surface of the polymer, so that when manufacturing a low-density polymer, if the surface density of the polymer is low during the polymerization stage, it prevents fluidization in the gas phase polymerization reactor due to stickiness, clumping between polymers, or easy clogging of surrounding devices such as pipes or heat exchangers, thereby enabling stable continuous operation.

[0069] In one embodiment, the shell portion may be formed through a slurry polymerization reaction in a polyolefin polymerization system or polymerization method described later. Specifically, in the polyolefin polymer, a shell portion having a hollow structure and relatively high density may be formed first.

[0070] The density of the above shell part is, for example, 0.890 g / cm³ 3 Up to 0.940 g / cm³ 3 , 0.895 g / cm 3 Up to 0.930 g / cm³ 3 or 0.900 g / cm³ 3 Up to 0.922 g / cm³ 3 It could be.

[0071] The melt flow index (MIE (2.16 kg load, 190°C)) of the shell portion above may be, for example, 0.01 g / 10 min to 5.0 g / 10 min, 0.05 g / 10 min to 3.5 g / 10 min, or 0.05 g / 10 min to 2.0 g / 10 min.

[0072] The melting temperature of the shell portion may be, for example, 80°C to 125°C, 90°C to 120°C, or 95°C to 110°C.

[0073] In the temperature rise elution fraction (TREF) chromatogram of the shell portion above, one peak may be present at a temperature of 60°C or higher.

[0074] The polyolefin polymer according to one embodiment may be in various forms such as powder or granules, and may also be provided in the form of pellets through a molding process as needed. This pellet form is advantageous in that it increases ease of handling and storage and enables uniform supply when subsequently introduced into a reaction device. In addition, the polyolefin polymer of the present invention still possesses specific physical properties, such as two or more melting temperatures, even in the various forms mentioned above.

[0075] In one embodiment, the core portion may be formed through a gas-phase polymerization reaction in a polyolefin polymerization system or polymerization method described below. Specifically, in the polyolefin polymer, the core portion may be formed with a structure that fills the hollow of the shell portion formed through the slurry polymerization reaction with a product of relatively low density.

[0076] The density of the above core part is, for example, 0.857 g / cm³ 3 Up to 0.910 g / cm³ 3 , 0.857 g / cm 3 Up to 0.900 g / cm³ 3 or 0.857 g / cm³ 3 Up to 0.898 g / cm³ 3 It could be.

[0077] The melting temperature of the core portion may be, for example, 45°C to 85°C, 50°C to 85°C, or 60°C to 70°C.

[0078] The weight ratio of the core portion to the shell portion may be 40:60 to 97:3, 40:60 to 90:10, 50:50 to 80:20, or 50:50 to 70:30. By forming the core portion and the shell portion with a weight ratio within the above range, a low-density polyolefin polymer is provided, and at the same time, the process stability can be further improved by preventing the relatively low-density core portion from leaking out to the surface of the polymer.

[0079] As described above, the polyolefin polymer formed with a core and a shell having different physical properties not only has low density characteristics, but also has a relatively high-density hollow shell forming the surface and a relatively low-density core filling the hollow of the shell, thereby preventing the problem of process stability being compromised due to sticky and wet characteristics when the density of the polymer surface is low.

[0080] In one embodiment, the polyolefin polymer of the present invention may be manufactured through a continuous process comprising two or more reactions, wherein the two or more reactions may include one or more gas-phase polymerization reactions. For example, it may include one slurry polymerization reaction process and one gas-phase polymerization reaction process, two slurry polymerization reaction processes and one gas-phase polymerization reaction process, one slurry polymerization reaction process and two gas-phase polymerization reaction processes, two slurry polymerization reaction processes and two gas-phase polymerization reaction processes, but is not limited thereto.

[0081] A polymerization system for a polyolefin according to one embodiment comprises one or more slurry polymerization reactors that polymerize a feed stream supplied in the presence of a catalyst to produce a slurry reaction product comprising a prepolymer, wherein the feed stream comprises a monomer and a comonomer, and the slurry polymerization reactor may comprise a loop comprising one or more reactors; one or more polymer discharge ports; one or more monomer inlet ports; one or more heat exchangers; and one or more circulation pumps.

[0082] A shell portion can be formed through the above slurry polymerization reactor.

[0083] The heat exchanger can effectively remove the heat of polymerization from the reactor by cooling the slurry and returning the cooled slurry to the reactor. One or more of the heat exchangers may be included in each slurry polymerization reactor system, for example, two or three may be included.

[0084] The above heat exchanger may be selected from double pipe, shell and tube, plate, plate, and shell and spiral heat exchangers, but a shell and tube heat exchanger is preferred. Despite its compact installation configuration, the shell and tube heat exchanger has a large heat transfer surface area and satisfies a sufficient heat removal capacity for use in confined spaces at the site.

[0085] Specifically, an example of the above shell-and-tube heat exchanger is illustrated in FIG. 3. As shown in FIG. 3, the shell-and-tube heat exchanger is in a vertically extended form, with a head, tube sheet, and nozzle formed at the upper and lower ends, respectively, and tubes, shells, and baffles formed in the middle.

[0086] The head forms the zone where the heat medium flows into or out of the heat exchanger. The tube sheet plays a crucial role in maintaining the structural stability of the heat exchanger by securing multiple tubes and maintaining airtightness between the tubes and the shell. The nozzle provides a passage for the cooling water to enter and exit the heat exchanger and controls the fluid flow.

[0087] The heat exchanger described above may be composed of a plurality of tubes, and cooling water passes through the tubes to effectively transfer heat from inside the reactor to the outside. The plurality of tubes are arranged parallel to each other and may be configured in a dense form to maximize the heat transfer area.

[0088] The aforementioned shell is an external structure that encloses multiple tubes and serves as a protective layer for the heat exchanger; additionally, a space is provided inside the shell through which cooling water can circulate. Heat from inside the reactor is released to the outside through this space.

[0089] Multiple baffles are installed inside the shell and are spaced apart from each other, alternating in a zigzag pattern. Due to this arrangement of baffles, the flow of cooling water is intermittently blocked, increasing the contact time between the tubes and the cooling water, thereby improving heat exchange efficiency.

[0090] The above heat exchanger has a cooling water flow rate of 1 m / s or more, preferably 3 m / s or more, and a heat transfer efficiency of 0.3 Mcal / m² 2 ⅹhrⅹK or higher, preferably 0.6 Mcal / m² 2 It can be greater than × hr × K. Here, hr means time, and K means absolute temperature.

[0091] The slurry polymerization reactor of the present invention includes one or more circulation pumps for recovering the reactor contents and circulating the reactor contents through a heat exchanger. The circulation pump may preferably be placed upstream of the heat exchanger, that is, between the outlet of the polymerization reactor and the heat exchanger, but is not limited thereto.

[0092] The polymerization system may additionally include one or more gas-phase polymerization reactors that receive the slurry reaction product, or the slurry reaction product and a feed stream, and perform a gas-phase polymerization reaction to produce a gas-phase reaction product including a final polymer.

[0093] A core part can be formed through the above-mentioned gas phase polymerization reactor.

[0094] The final polymer has two or more density distributions, including a core portion and a shell portion with a higher density than the core portion, and the operating temperature of the slurry polymerization reactor is 20°C to 70°C and may be higher than the operating temperature of the gas phase polymerization reactor.

[0095] The above-mentioned polyolefin polymerization system may be a system for producing a final polymer, that is, the polyolefin polymer described above.

[0096] In one embodiment, each of the one or more slurry polymerization reactors and one or more gas phase polymerization reactors may be connected in series.

[0097] In one embodiment, the catalyst may be a metallocene single catalyst. The metallocene may be represented by the chemical formula LnMQp, where M is a metal of group IIIB, group IVB, group VB, or group VIB; Q is a hydrocarbyl group or halogen having 1 to 20 carbon atoms; p is the valence of M -2; and L is a ligand bonded to the metal M.

[0098] These metallocene catalysts are known as catalytic systems that produce polyolefins with excellent physical properties due to their high activity and high copolymerization reactivity compared to conventional Ziegler-Natta catalysts, and metallocene catalysts can be used as homogeneous catalysts by being supported on a suitable support. For example, the support may be silicon and / or aluminum oxide, and as a specific example, silica having OH groups or other functional groups containing active hydrogen atoms, and may be in the form of porous spherical particles.

[0099] The metallocene catalyst may be supported on a support together with a co-catalyst, and the co-catalyst may be an alkylaluminoxane. The alkylaluminoxane comprises a straight-chain and / or cyclic alkylaluminoxane oligomer, and if the alkylaluminoxane is a straight-chain alkylaluminoxane oligomer, the chemical formula R-(Al(R)-O) n Represented as -AlR2, and in the case of a cyclic alkylaluminoxane oligomer, the chemical formula is (-Al(R)-O-) m It is represented as such, where R is a C1-C8 alkyl group, preferably methyl, n is 1-40, preferably 10-20, and m is 3-40, preferably 3-20. The alkylaluminoxane is a mixture of oligomers with a very wide molecular weight distribution, and typically the average molecular weight can be 800 to 1200.

[0100] In one embodiment, the feed stream may include a monomer and a comonomer.

[0101] The above monomer may be ethylene.

[0102] The above comonomer may be one or more selected from the group consisting of 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and 1-octene. As a specific example, the above comonomer may be one or more of 1-butene and 1-hexene.

[0103] The above feed stream may further include a diluent. The diluent may be one or more of an inert gas and an alkane. Here, the inert gas may include nitrogen, helium, neon, etc., and the alkane may include butane, propane, isobutane, isopentane, hexane, and isomers thereof. Thus, the method may include the step of producing a polyolefin polymer by contacting a catalyst with monomers and comonomers in a slurry polymerization reactor and a gas phase polymerization reactor using the diluent.

[0104] Polyolefin polymers, specifically polyolefin elastomers, and more specifically low-density polyethylene can be produced by polymerizing a feed stream containing ethylene and a comonomer in the presence of the above catalyst using a system in which one or more slurry polymerization reactors and one or more gas phase polymerization reactors are sequentially arranged.

[0105] In one embodiment, the operating temperature of the slurry polymerization reactor may be 20°C to 70°C or 40°C to 60°C. Additionally, the operating temperature of the gas phase polymerization reactor may be lower than the operating temperature of the slurry polymerization reactor, for example, 30°C to 50°C or 35°C to 48°C. By lowering the operating temperature of each reactor in this way to produce the final polymer as described above, the portion where the sticky and wet resin hinders the fluidization of the reactor can be minimized, thereby further improving process stability.

[0106] In one embodiment, the operating pressure of the slurry polymerization reactor may be 5 K / G to 30 K / G, 10 K / G to 25 K / G, or 20 K / G to 25 K / G. Additionally, the operating pressure of the gas phase polymerization reactor may be adjusted to be lower than or equal to the operating pressure of the slurry polymerization reactor; for example, the pressure of the gas phase polymerization reactor may be operated at 10 K / G to 20 K / G or 10 K / G to 15 K / G depending on the temperature of the slurry reactor. By lowering the operating pressure of each reactor in this manner to produce the final polymer as described above, the portion where the sticky and wet resin hinders the fluidization of the reactor is minimized, thereby further improving process stability. Here, the pressure unit K / G is kg / cm² 2 It means.

[0107] In one embodiment, through multi-stage polymerization in one or more slurry polymerization reactors and one or more gas phase polymerization reactors, a prepolymer having a relatively high density and forming a hollow shell structure was prepared in the slurry polymerization reaction, and a final polymer was prepared by filling the hollows of the prepolymer particles with a polyolefin polymer, i.e., a polyolefin elastomer (POE), in the gas phase polymerization reactor, wherein the final polymer may have the physical properties of a polyolefin elastomer.

[0108] In one embodiment, the molar ratio of ethylene to the comonomer alpha-olefin in each reactor can be adjusted to 0.01 to 0.3 depending on the type of comonomer. For example, in the slurry polymerization reactor, the molar ratio of the comonomer to the total amount of the monomer and comonomer may be 0.01 to 0.3, 0.05 to 0.3, or 0.07 to 0.27, and in the gas phase polymerization reactor, the molar ratio of the comonomer to the total amount of the monomer and comonomer may be 0.01 to 0.2 or 0.05 to 0.18. By varying the comonomer ratio in each reactor, a polymer having properties such as two or more melting temperatures or two or more crystallinity temperatures can be produced, and a polymer having a high melting temperature and a low glass transition temperature (Tg) can exhibit significant advantages in terms of processing and physical properties.

[0109] The prepolymer produced in the above-described slurry polymerization reactor may account for 3% to 60% by weight, or 10% to 60% by weight, of the total amount of the final polymer produced. For example, the prepolymer may account for 20% to 50% by weight or 30% to 50% by weight of the total amount of the final polymer. By controlling the weight ratio of the prepolymer to the total amount of the final polymer within the above range, the overall density is increased without impairing the physical properties of the final polymer, and a relatively high-density shell portion is firmly formed so that the polymer produced in the gas phase polymerization reactor is almost absent from the outside, thereby improving process stability.

[0110] In one embodiment, the vapor phase polymerization reactor is MIT measured according to ASTM 3417-83 15 It can be operated at a temperature below the (15 wt% melting initiation temperature). Specifically, the above MIT 15The temperature below is intended to set the process operating temperature while operating each reactor at a low temperature to ensure process stability, and the above MIT 15 Temperatures below this level were measured using a DSC instrument according to the ASTM 3417-83 method, based on the area where 15 wt% melt area percent appeared in the 1st Scan from 25 ℃ to 200 ℃ under a condition of 10 ℃ / min.

[0111] For example above, in the gas phase polymerization reactor, MIT 15 The temperature below may be 40 ℃ to 80 ℃, 40 ℃ to 70 ℃, or 40 ℃ to 65 ℃. The above MIT 15 Controlling the gas-phase polymerization reactor at a temperature identical to the temperature conditions can cause polymer aggregation and reduce process stability. On the other hand, operating the reactor at too low a temperature to ensure process stability has the disadvantage of significantly lower production yield. Furthermore, in the manufacturing process of polyolefin polymers with high comonomer content, increasing production volume can lead to localized high comonomer ratios; this results in increased polymer adhesiveness, leading to the formation of heterogeneous polymers that can become a source of process trouble, whereas MIT within the aforementioned range 15 Temperatures below this level can be prevented by controlling the temperature of the gas phase polymerization reactor.

[0112] In one embodiment, if the slurry polymerization reactor is placed upstream of the gas phase polymerization reactor, it is possible to prevent the metallocene catalyst from being directly exposed to the conditions of the gas phase polymerization reactor, and the size of the polymer can be increased through the slurry polymerization reaction, which helps with process stability. In addition, if a low-density prepolymer is produced in the slurry polymerization reactor, there may be a problem where the polymer having the properties of a polyolefin elastomer on the outside becomes excessive, and the polymer as a whole has sticky characteristics that impair process stability.

[0113] The final polymer according to one embodiment may be the polyolefin polymer described above.

[0114] As one example, the polymerization system of the polyolefin may include one slurry polymerization reactor and one gas phase polymerization reactor. In this case, the polymerization system of the polyolefin may include a first slurry polymerization reactor (100) that polymerizes a feed stream supplied in the presence of a catalyst to produce a slurry reaction product containing a prepolymer; and a first gas phase polymerization reactor (300) that receives the slurry reaction product, or the slurry reaction product and the feed stream, and polymerizes it to produce a gas phase reaction product containing a final polymer.

[0115] As another example, the polymerization system of the polyolefin may include one slurry polymerization reactor and two gas phase polymerization reactors. In this case, the polyolefin polymerization system may include: a first slurry polymerization reactor (100) that polymerizes a feed stream supplied in the presence of a catalyst to produce a slurry reaction product containing a prepolymer; a first gas phase polymerization reactor (300) that receives the slurry reaction product, or the slurry reaction product and feed stream from the first slurry polymerization reactor (100), and polymerizes it in a gas phase to produce a first gas phase reaction product containing a final polymer; and a second gas phase polymerization reactor (400) that receives the first gas phase reaction product, or the first gas phase reaction product and feed stream from the first gas phase polymerization reactor (300), and polymerizes it in a gas phase to produce a second gas phase reaction product containing a final polymer.

[0116] As another example, the polymerization system of the polyolefin may include two slurry polymerization reactors and two gas phase polymerization reactors. In this case, the polyolefin polymerization system comprises: a first slurry polymerization reactor (100) that polymerizes a feed stream supplied in the presence of a catalyst to produce a first slurry reaction product containing a prepolymer; a second slurry polymerization reactor (200) that receives the first slurry reaction product, or the first slurry reaction product and a feed stream from the first slurry polymerization reactor (100), polymerizes the feed stream to polymerize the feed stream to produce a second slurry reaction product containing a prepolymer; and a first gas phase polymerization reactor (300) that receives the second slurry reaction product, or the second slurry reaction product and a feed stream from the second slurry polymerization reactor (200), polymerizes the feed stream to polymerize the feed stream to produce a first gas phase reaction product containing a final polymer. and a second gas phase polymerization reactor (400) that receives a first gas phase reaction product, or the first gas phase reaction product and a feed stream from the first gas phase polymerization reactor (300), and performs a gas phase polymerization reaction to produce a second gas phase reaction product including a final polymer.

[0117] In one embodiment, the first gas phase reaction product generated in the first gas phase polymerization reactor (300) separates unreacted gas and polymer in a filter, supplies the separated polymer to the second gas phase polymerization reactor (400), and the unreacted gas can be recirculated to the first slurry polymerization reactor (100) and / or the second slurry polymerization reactor (200) via a purification tower.

[0118] Operating the above-mentioned gas phase polymerization reactor at too low a temperature has the disadvantage of resulting in very low production yield. Furthermore, in the manufacturing process of polyolefin polymers with high comonomer content, increasing production yield can lead to localized high comonomer ratios. This results in increased polymer tackiness, which in turn generates heterogeneous polymers and can become a source of process trouble. In this invention, a method is applied to reduce polymer tackiness under high-concentration comonomer conditions by utilizing a high-adhesion mode.

[0119] As a specific example, the first gas phase polymerization reactor (300) may not be operated in a high sorption mode, and the second gas phase polymerization reactor (400) may be operated in a high sorption mode. The second gas phase polymerization reactor (400) may be operated under conditions where the injected gas is condensed at a temperature and pressure, and the gas discharged from the reactor is not condensed at a temperature and pressure.

[0120] For reference, the polyolefin polymerization system may include a circulation line extending from the upper part of the gas phase polymerization reactor and connected to the lower part of the gas phase polymerization reactor to circulate a circulating gas stream, a compressor provided in the circulation line, and a heat exchanger provided downstream of the compressor with respect to the flow direction of the circulating gas stream in the circulation line, wherein in the high adsorption mode, the adsorbent may be used in an amount of 0.1 to 30 parts by weight, 2 to 20 parts by weight, or 3 to 15 parts by weight per 100 parts by weight of the total circulating gas stream.

[0121] When the second gas phase polymerization reactor (400) is operated in a high adsorption mode, the adsorbent used may include propane, isobutane, isopentane, and hexane.

[0122]

[0123] A method for polymerizing a polyolefin according to one embodiment comprises: a slurry polymerization step of polymerizing a feed composition containing a monomer and a comonomer in the presence of a catalyst one or more times to produce a slurry reaction product containing a prepolymer; and a gas phase polymerization step of polymerizing the slurry reaction product obtained above, or the slurry reaction product and the feed composition one or more times to produce a gas phase reaction product containing a final polymer; wherein the reaction temperature of the slurry polymerization step is 20°C to 70°C and is performed at a temperature higher than the reaction temperature of the gas phase polymerization step, and the final polymer may have two or more density distributions including a core portion and a shell portion having a higher density than the core portion.

[0124] The above-described method for polymerizing polyolefins may be a method for producing a final polymer, i.e., the above-described polyolefin polymer, using the above-described polyolefin polymerization system.

[0125] In one embodiment, the catalyst may be a metallocene single catalyst. The metallocene may be represented by the chemical formula LnMQp, where M is a metal of group IIIB, group IVB, group VB, or group VIB; Q is a hydrocarbyl group or halogen having 1 to 20 carbon atoms; p is the valence of M -2; and L is a ligand bonded to the metal M.

[0126] These metallocene catalysts are known as catalytic systems that produce polyolefins with excellent physical properties due to their high activity and high copolymerization reactivity compared to conventional Ziegler-Natta catalysts, and metallocene catalysts can be used as homogeneous catalysts by being supported on a suitable support. For example, the support may be silicon and / or aluminum oxide, and as a specific example, silica having OH groups or other functional groups containing active hydrogen atoms, and may be in the form of porous spherical particles.

[0127] The metallocene catalyst may be supported on a support together with a co-catalyst, and the co-catalyst may be an alkylaluminoxane. The alkylaluminoxane comprises a straight-chain and / or cyclic alkylaluminoxane oligomer, and if the alkylaluminoxane is a straight-chain alkylaluminoxane oligomer, the chemical formula R-(Al(R)-O) n Represented as -AlR2, and in the case of a cyclic alkylaluminoxane oligomer, the chemical formula is (-Al(R)-O-) m It is represented as such, where R is a C1-C8 alkyl group, preferably methyl, n is 1-40, preferably 10-20, and m is 3-40, preferably 3-20. The alkylaluminoxane is a mixture of oligomers with a very wide molecular weight distribution, and typically the average molecular weight can be 800 to 1200.

[0128] In one embodiment, the feed stream may include a monomer and a comonomer.

[0129] The above monomer may be ethylene.

[0130] The above comonomer may be one or more selected from the group consisting of 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and 1-octene. As a specific example, the above comonomer may be one or more of 1-butene and 1-hexene.

[0131] The above feed stream may further include a diluent. The diluent may be one or more of an inert gas and an alkane. Here, the inert gas may include nitrogen, helium, neon, etc., and the alkane may include butane, propane, isobutane, isopentane, hexane, and isomers thereof. Thus, the method may include the step of producing a polyolefin polymer by contacting monomers and comonomers in a slurry polymerization reactor and a gas phase polymerization reactor using the diluent.

[0132] Polyolefin polymers, specifically polyolefin elastomers, and more specifically low-density polyethylene can be produced by polymerizing a feed stream containing ethylene and a comonomer in the presence of the above catalyst using a system in which one or more slurry polymerization reactors and one or more gas phase polymerization reactors are sequentially arranged.

[0133] In one embodiment, the temperature of the slurry polymerization reaction may be 20°C to 70°C or 40°C to 60°C. Additionally, the temperature of the gas phase polymerization reaction may be lower than the temperature of the slurry polymerization reaction, for example, 30°C to 50°C or 35°C to 48°C. By lowering the operating temperature of each reaction in this way to produce the final polymer as described above, the portion where the sticky and wet resin hinders the fluidization of the reactor can be minimized, thereby further improving process stability.

[0134] In one embodiment, the pressure of the slurry polymerization reaction may be 5 K / G to 30 K / G, 10 K / G to 25 K / G, or 20 K / G to 25 K / G. Additionally, the pressure of the gas phase polymerization reaction may be controlled to a temperature lower than or equal to the operating pressure of the slurry polymerization reaction, for example, it may be operated at 10 K / G to 20 K / G or 10 K / G to 15 K / G depending on the temperature. By lowering the pressure of each reactor in this way to produce the final polymer as described above, the portion where the sticky and wet resin hinders the fluidization of the reactor can be minimized, thereby further improving process stability.

[0135] In one embodiment, through multi-stage polymerization of one or more slurry polymerization reactions and one or more gas phase polymerization reactions, a prepolymer having a relatively high density and forming a hollow shell portion was prepared in the slurry polymerization reaction, and a final polymer was prepared by filling the hollows of the prepolymer particles with a polyolefin polymer, i.e., a polyolefin elastomer (POE), in the gas phase polymerization reaction, wherein the final polymer may have the physical properties of a polyolefin elastomer.

[0136] In one embodiment, the molar ratio of ethylene to the comonomer alpha-olefin in each reaction can be adjusted to 0.01 to 0.3 depending on the type of comonomer. For example, in the slurry polymerization reaction, the molar ratio of the comonomer to the total amount of the monomer and comonomer may be 0.01 to 0.3, 0.05 to 0.3, or 0.07 to 0.27, and in the gas phase polymerization reaction, the molar ratio of the comonomer to the total amount of the monomer and comonomer may be 0.01 to 0.2 or 0.05 to 0.18. By varying the ratio of the comonomer in each reaction, a polymer having properties such as two or more melting temperatures or two or more crystallinity temperatures can be produced, and a polymer having a high melting temperature and a low glass transition temperature (Tg) can exhibit significant advantages in terms of processing and physical properties.

[0137] The prepolymer produced in the above slurry polymerization reaction may account for 3% to 60% by weight, or 10% to 60% by weight, of the total amount of the final polymer produced. For example, the prepolymer may account for 20% to 50% by weight or 30% to 50% by weight of the total amount of the final polymer. By controlling the weight ratio of the prepolymer to the total amount of the final polymer within the above range, the overall density is increased without impairing the physical properties of the final polymer, and a relatively high-density shell portion is firmly formed so that the polymer produced in the gas phase polymerization reactor is almost absent from the outside, thereby improving process stability.

[0138] In one embodiment, the vapor phase polymerization reaction is MIT measured according to ASTM 3417-83 15 It can be performed at a temperature below the (15 wt% melting initiation temperature). Specifically, the above MIT 15 The temperature below is intended to control the temperature of each reaction low to ensure process stability while establishing an appropriate temperature range, and the above MIT 15 Temperatures below this level were measured using a DSC instrument according to the ASTM 3417-83 method, based on the area where 15 wt% melt area percent appeared in the 1st Scan from 25 ℃ to 200 ℃ under a condition of 10 ℃ / min.

[0139] For example above, in the above gas-phase polymerization reaction, MIT 15 The temperature below may be 40 ℃ to 80 ℃, 40 ℃ to 70 ℃, or 40 ℃ to 65 ℃. The above MIT 15Controlling the vapor phase polymerization reaction at the same temperature as the temperature can lead to polymer aggregation and reduce process stability. On the other hand, operating the reactor at too low a temperature to ensure process stability has the disadvantage of significantly lower production yield. Furthermore, in the manufacturing process of polyolefin polymers with high comonomer content, increasing production volume can result in localized high comonomer ratios; this leads to increased polymer tackiness and the formation of heterogeneous polymers, which can become a source of process trouble. Regarding MIT within the aforementioned range 15 Temperatures below this level can prevent such problems by controlling the temperature of the gas phase polymerization reaction.

[0140] In one embodiment, if the slurry polymerization reaction is placed upstream of the gas-phase polymerization reactor, it is possible to prevent the metallocene catalyst from being directly exposed to the gas-phase polymerization reaction conditions, and the size of the polymer can be increased through the slurry polymerization reaction, which helps with process stability. On the other hand, if a low-density prepolymer is produced in the slurry polymerization reaction, there is an increase in the polymer having the properties of a polyolefin elastomer on the outside, and the polymer as a whole has sticky characteristics, which may cause problems that impair process stability.

[0141] In one embodiment, the slurry polymerization reaction may produce a prepolymer having a hollow structure to form the shell portion of the final polymer, and the gas phase polymerization reaction may fill the hollow of the prepolymer with a product having a higher density than the prepolymer to form the core portion of the final polymer.

[0142] Here, the final polymer may be the polyolefin polymer described above. Specifically, through the slurry polymerization step, the density is 0.890 g / cm³ 3 Up to 0.940 g / cm³ 3 The above shell portion is formed, and through the above vapor phase polymerization step, the density is 0.857 g / cm³ 3 Up to 0.910 g / cm³3 It can form an in-core part.

[0143] As one example, the polymerization method of the polyolefin may include: a slurry polymerization step of polymerizing a feed composition comprising a monomer and a comonomer in the presence of the catalyst to produce a slurry reaction product comprising a prepolymer; and a gas phase polymerization step of polymerizing the slurry reaction product obtained above, or the slurry reaction product and the feed composition in a gas phase to produce a final polymer.

[0144] FIG. 2a below illustrates a method for polymerizing a polyolefin according to one embodiment. Specifically, as shown in FIG. 2a below, the polyolefin polymerization method may sequentially perform a slurry polymerization reaction and a gas phase polymerization reaction.

[0145] As another example, the polymerization method of the polyolefin may comprise: a first slurry polymerization step of polymerizing a feed composition comprising a monomer and a comonomer in the presence of a catalyst to produce a slurry reaction product comprising a prepolymer; a first gas phase polymerization step of polymerizing the slurry reaction product obtained above, or the slurry reaction product obtained above and the feed composition in a first gas phase polymerization reaction to produce a first gas phase reaction product comprising a final polymer; and a second gas phase polymerization step of polymerizing the first gas phase reaction product obtained above, or the first gas phase reaction product obtained above and the feed composition in a second gas phase polymerization reaction to produce a second gas phase reaction product comprising a final polymer.

[0146] As another example, the polymerization method of the polyolefin described above may comprise: a first slurry polymerization step of primary slurry polymerizing a feed composition comprising a monomer and a comonomer in the presence of a catalyst to produce a first slurry reaction product comprising a prepolymer; a second slurry polymerization step of secondary slurry polymerizing the first slurry reaction product obtained above, or the first slurry reaction product and the feed composition, to produce a second slurry reaction product comprising a prepolymer; a first gas phase polymerization step of primary gas phase polymerizing the second slurry reaction product obtained above, or the second slurry reaction product obtained above and the feed composition, to produce a first gas phase reaction product comprising a final polymer; and a second gas phase polymerization step of secondary gas phase polymerizing the first gas phase reaction product obtained above, or the first gas phase reaction product and the feed composition, to produce a second gas phase reaction product comprising a final polymer.

[0147] FIG. 2d below illustrates a method for polymerizing a polyolefin according to one embodiment. Specifically, as shown in FIG. 2d below, the polyolefin polymerization method may sequentially perform a first slurry polymerization reaction, a second slurry polymerization reaction, a first gas phase polymerization reaction, and a second gas phase polymerization reaction.

[0148] In one embodiment, the first gas phase reaction product generated in the first gas phase polymerization reaction is separated into unreacted gas and polymer through filtration in a filter, and a second gas phase polymerization reaction is performed using the separated polymer, and the unreacted gas can be reused in the first slurry polymerization reaction and / or the second slurry polymerization reaction.

[0149] Operating the above-mentioned vapor phase polymerization reaction at too low a temperature has the disadvantage of resulting in very low production yield. Furthermore, in the manufacturing process of polyolefin polymers with high comonomer content, increasing production yield can lead to localized high comonomer ratios. This results in increased polymer tackiness, which in turn generates heterogeneous polymers and can become a source of process trouble. In this invention, a method is applied to reduce polymer tackiness under high-concentration comonomer conditions by utilizing a high-adhesion mode.

[0150] As a specific example, the first gas phase polymerization reaction may not be operated in a high sorption mode, and the second gas phase polymerization reaction may be operated in a high sorption mode. The second gas phase polymerization reaction may be operated under conditions where the injected gas condenses at a temperature and pressure, and the gas discharged from the reactor does not condense at a temperature and pressure.

[0151] For reference, the above gas phase polymerization reaction can be carried out using a circulation line that extends from the top of the gas phase polymerization reactor and is connected to the bottom of the gas phase polymerization reactor to circulate a circulating gas stream, a compressor provided in the circulation line, and a heat exchanger provided downstream of the compressor with respect to the flow direction of the circulating gas stream in the circulation line, and in the high adsorption mode, the adsorbent can be used in an amount of 0.1 to 30 parts by weight, 2 to 20 parts by weight, or 3 to 15 parts by weight per 100 parts by weight of the total circulating gas stream.

[0152] When the above second gas phase polymerization reaction is operated in a high adsorption mode, the adsorbent used may include propane, isobutane, isopentane, and hexane.

[0153] When polymerizing a polyolefin including the above two slurry polymerization steps and two gas-phase polymerization steps, the density through the two slurry polymerization steps is 0.890 g / cm³ 3 Up to 0.940 g / cm³3 The above shell portion is formed, and through the first vapor phase polymerization step, the density is 0.887 g / cm³ 3 Up to 0.898 g / cm³ 3 The above-mentioned core portion is formed, and through the second vapor phase polymerization step, the density is 0.857 g / cm³ 3 Up to 0.886 g / cm³ 3 The above-mentioned core part can be formed.

[0154] Through the above two slurry polymerization steps, the density is, for example, 0.890 g / cm³ 3 Up to 0.940 g / cm³ 3 , 0.895 g / cm 3 Up to 0.930 g / cm³ 3 or 0.900 g / cm³ 3 Up to 0.922 g / cm³ 3 It can form a shell part.

[0155] Through the above first vapor phase polymerization step, the density is 0.887 g / cm³ 3 Up to 0.898 g / cm³ 3 or 0.888 g / cm³ 3 Up to 0.897 g / cm³ 3 It can form an in-core part.

[0156] Through the above second vapor phase polymerization step, the density is 0.857 g / cm³ 3 Up to 0.886 g / cm³ 3 or 0.857 g / cm³ 3 Up to 0.884 g / cm³ 3 It can form an in-core part.

[0157] In this way, a polyolefin polymer can be manufactured by forming a shell portion with a relatively high density through a slurry polymerization reaction, forming a core portion with a lower density than that of the slurry polymerization reaction through a first gas-phase polymerization reaction, and forming a core portion with an even lower density than that of the first gas-phase polymerization reaction through a second gas-phase polymerization reaction. This difference in density gradient allows the catalyst to produce a prepolymer with a relatively higher density in the slurry polymerization reaction compared to the gas-phase polymerization reaction, thereby improving process stability when proceeding to the first and second gas-phase polymerization reactions. The manufactured polyolefin polymer may have two or more melting temperatures—a high melting temperature and a low melting temperature—due to the density gradient, and may have a low glass transition temperature. Due to these characteristics of the polyolefin polymer, the turnover rate during molding increases, thereby increasing processing productivity, and physical properties such as rebound elasticity may be improved due to the low glass transition temperature.

[0158]

[0159] Specific embodiments of the present invention are presented below. However, the embodiments described below are merely for the purpose of specifically illustrating or explaining the present invention and should not be limited thereto. Furthermore, details not described herein can be sufficiently technically inferred by a person skilled in the art, so their description is omitted.

[0160] (Manufacture of polyolefin polymers)

[0161] Examples 1 to 4 and Comparative Examples 1 to 2

[0162] Polyolefin polymers, specifically linear low-density polyethylene, were manufactured using one slurry polymerization reactor and one gas phase polymerization reactor. At this time, the operating conditions of each reactor are as shown in Table 1 below.

[0163] Polymerization was carried out in a batch polymerization reactor by simulating slurry polymerization and gas phase polymerization conditions using a catalyst composition prepared with a basic combination of a metallocene catalyst, methylaluminoxan (MAO), and a porous support.

[0164] To control the polymerization temperature, a 2L stainless steel autoclave reactor equipped with a jacket capable of supplying external cooling water was heated from room temperature to 110°C, purged with nitrogen, and then purged using 400ml of isobutane.

[0165] After adjusting the temperature, 1.5 ml of 0.2 M triethylaluminum (TEAL), 2.5 ml of antistatic agent (Statsafe® 6000, Innospec product) (1.1 mmol in hexane), and 1 L of isobutane were added to the reactor.

[0166] Subsequently, ethylene, 1-hexene (weight%, amount of 1-hexene input relative to input ethylene), and hydrogen (mg / kg C2, amount of hydrogen input relative to 1 kg of input ethylene (mg)) were introduced, and a supported catalyst was introduced into the reactor. The slurry polymerization reaction was carried out according to the polymerization conditions shown in Table 1 below. During the polymerization, the partial pressure of ethylene was maintained constant, and 1-hexene and hydrogen were continuously introduced in conjunction with ethylene. After the slurry polymerization was completed, unreacted 1-hexene and isobutane were discharged.

[0167] For the gas phase polymerization reaction, nitrogen was injected into the gas phase polymerization reactor at 100 psi as a diluent, 250 ppm of antistatic agent was injected, and the temperature was controlled to 48 ℃.

[0168] After temperature control, the gas phase polymerization reaction was carried out according to the polymerization conditions shown in Table 1 below. After the reaction was completed, unreacted gas was discharged and the reactor was opened to obtain a linear low-density polyethylene (LLDPE) resin with free flowability as the final polymer, and its physical properties were measured and presented.

[0169]

[0170] Classification Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Slurry Polymerization Reactor Catalyst injection amount (g) 0.18 0.18 0.18 0.18 0.18 0.12 Reactor temperature (°C) 60 60 60 60 60 47 Reactor pressure (K / G) 13.1 13.1 13.1 13.1 13.1 10.8 0.2 M TEAL (ml) 1.5 1.5 1.5 1.5 1.5 1.5 Ethylene partial pressure (K / G) 5.4 5.4 5.4 5.4 5.4 Hydrogen injection amount (ppm) 40 40 30 30 40 10 1-Hexene Injection Volume (Weight%) 10 10 10 10 10 35 MIE (g / 10 min) 1.4 1 1.3 0 1.3 0 1.3 0 1.3 0 2.15 Density (D) (g / cm³) 0.9 20 6 0.9 15 5 0.9 15 5 0.9 15 5 0.9 15 5 0.8 9 75 T m (℃)113.1115.4115.4115.4115.4N / AT c (°C) 99.8 101.8 101.8 101.8 101.8 N / A Gas-phase Polymerization Reactor Reactor Temperature (°C) 48 48 48 48 60 55 Reactor Pressure (K / G) 11.7 11.7 11.7 11.7 11.7 13 Ethylene Partial Pressure (K / G) 4.8 4.8 4.8 4.8 4.8 6.2 Hydrogen Injection Amount (ppm) 0 0 0 0 0 1-Hexene Injection Amount (WH%) 35 5 5 60 70 5 5 50 MIE (g / 10 min) 1) 1.680.680.630.89N / A1.00SR(F / E)19.822.523.924.7N / A19.7Density (D)(g / ㎤)0.89660.88230.87860.8739N / A0 .8816Mn50,73458,66259,976N / AN / AN / AMw113,965144,863148,235N / AN / AN / APDI2.252.472.47N / AN / AN / AT m (℃)82.2 / 113.557.9 / 115.957.6 / 116.551.3 / 118.9N / A56.4T c (℃)96.2 / 108.386.5 / 108.484.9 / 107.484.6 / 106.2N / A40.6 / 96.7T g (℃)-45-52.7-54.0-58.2N / A-53.0MIT 15(℃) 68.66 0.16 1.85 9.6 N / AN / A Single Density (D) (g / cm³) 0.873 80.868 80.863 70.85 72 N / A 0.875 50 Fraction (Weight%) 50 70 70 70 70 70 B.D 0.39 0.40 0.39 0.36 N / A 0.32 60 ℃ or higher TREF Fraction (%) 50 25 25 23 N / AN / A

[0171] 1) MIE in a gas-phase polymerization reactor is a measurement of the final polymer.

[0172]

[0173] In Table 1 above and Table 2 below, the measurement method for each characteristic is shown below.

[0174] Melt flow index (MIE, MI2.16): Measured according to ASTM D1238 under conditions of 190℃ and a 2.16 kg load.

[0175] High-load melt flow index (MIF, MI21.6): Measured according to ASTM D1238 under conditions of 190℃ and a 21.6 kg load.

[0176] The melt flow index ratio (SR, MFRR) was calculated as MIF / MIE (F / E).

[0177] Density: Measured using the density gradient method according to ASTM D1505.

[0178] BD: Bulk density (apparent density) was measured according to ASTM D1895.

[0179] Molecular weight and molecular weight distribution: Measurements were performed as follows using a gel permeation chromatography-RI (GPC-RI; Polymer Laboratory Inc. 220 System) equipped with a refractive index detector (RI Detector). Two Olexis columns and one Guard column were used, and the column temperature was maintained at 160°C. Calibration was performed using a standard polystyrene set from Polymer Laboratory Inc. Trichlorobenzene containing 0.0125 wt% of an antioxidant (BHT) was used as the eluent, the sample concentration was 1.0 mg / mL, and measurements were taken for 27 minutes under conditions of an injection volume of 0.2 mL and a pump flow rate of 1.0 mL / min. The number-average molecular weight (Mn), weight-average molecular weight (Mw), and Z-average molecular weight (Mz) were calculated by performing universal calibration using polystyrene standard materials Easical A and Easical B (Agilent products) and then converting them to polyethylene.

[0180] Dissolution temperature (T m ), crystallization temperature (T c ) : Measured using a DSC instrument according to the ASTM 3417-83 method, and the values ​​obtained from the 2nd scan in the temperature range of 25 to 200℃ under the condition of 10℃ / min were used.

[0181] Glass transition temperature (T g ) : Measured using a DSC instrument according to the ASTM 3417-83 method, and the values ​​obtained from the 2nd scan in the temperature range of -80 to 200℃ under the condition of 40℃ / min were used.

[0182] MIT 15: Measured using a DSC instrument according to ASTM 3417-83 method, based on the area where 15 wt% melt area percent appeared in the 1st Scan from 25 to 200℃ under a condition of 10℃ / min.

[0183] Comonomer (wt%): Analyzed and calculated via 13C NMR according to ASTM D5017.

[0184] Temperature-Rising Elution Fractionation (TREF): Analysis was performed as follows using Cross-Fraction Chromatography (CFC; PolymerChar CFC-2) equipment. Two Olexis columns and one Guard column were used, the column temperature was maintained at 150 ℃, and calibration was performed using a standard polystyrene set from Polymer Laboratory Inc. Trichlorobenzene containing 0.0125 wt% of an antioxidant (BHT) was used as the eluent, the sample concentration was 75 mg / mL, and the pump flow rate was 1.0 mL / min. After sample injection, the oven and sample temperatures were raised to 150 ℃ at a heating rate of 40 ℃ / min, maintained at 150 ℃ for 60 minutes, and then the sample temperature was lowered to 95 ℃ at a cooling rate of 40 ℃ / min. After maintaining at 95 ℃ for 45 minutes, the sample was cooled to 30 ℃ at a cooling rate of 0.5 ℃ / min and maintained for 30 minutes. Subsequently, the sample temperature was raised from 35 ℃ to 120 ℃, dividing the sample into 22 temperature-specific fractions at 4 ℃ intervals. 0.5 mL of the sample was injected into each fraction, and the eluted fractions were passed through a TREF column and an Olexis column to obtain TREF values ​​and molecular weights simultaneously. Molecular weights were calculated by performing universal calibration using polystyrene standards Easical A and Easical B (Agilent products) and converting the results to polyethylene. Data processing was performed using the instrument's accompanying analysis program "CFC Calibration." The analysis took approximately 600 minutes, and an infrared spectrometer was used as the detector.

[0185] Single density: Calculated using Equation 1 below.

[0186] [Equation 1]

[0187]

[0188]

[0189] In the above Equation 1, d is the density of the final polymer, d1 and m1 are the homodensity and fraction (weight%) of the polymer produced in the first slurry polymerization reactor, respectively, d2 and m2 are the homodensity and fraction (weight%) of the polymer produced in the second slurry polymerization reactor, respectively, d3 and m3 are the homodensity and fraction (weight%) of the polymer produced in the first gas phase polymerization reactor, respectively, d4 and m4 are the homodensity and fraction (weight%) of the polymer produced in the second gas phase polymerization reactor, respectively, and m1+m2+m3+m4 = 1.

[0190] Here, in the case of Examples 1 to 4 and Comparative Examples 1 to 2 using one slurry polymerization reactor and one gas phase polymerization reactor, it was assumed that the first slurry polymerization reactor and the second gas phase polymerization reactor were used, and factors related to the second slurry polymerization reactor and the first gas phase polymerization reactor were excluded from the formula and calculated.

[0191] Examples 5 to 9 and Comparative Example 3

[0192] Polyolefin polymers, specifically linear low-density polyethylene, were produced using two slurry polymerization reactors and two gas-phase polymerization reactors with a catalyst composition (M-Cat') prepared using a basic combination of a metallocene catalyst, methylaluminoxan (MAO), and a porous support. At this time, the operating conditions of each reactor are as shown in Table 2 below.

[0193] The fluidized beds of the first slurry polymerization reactor and the second slurry polymerization reactor consist of polymer particle granules. 1-Butene, ethylene, and hydrogen were mixed together in the piping and injected into the circulation line, and the composition injected and the properties of the resulting prepolymer are listed in Table 2 below.

[0194] The injection concentrations of ethylene, hydrogen, and 1-butene in the first and second gas-phase polymerization reactors were controlled to maintain the composition as shown in Table 2 below. In addition, the prepolymer was supplied in an amount of 5% to 10% by weight of the total weight of the polymerization composition (prepolymer + ethylene + 1-butene), and the mole percentage of the remainder other than ethylene, hydrogen, and 1-butene in the component concentrations of the first and second gas-phase polymerization reactors in Table 2 below is propane, which is a diluent.

[0195] The concentration of all gases was measured by online gas chromatography of the gases within the circulating gas stream. The reaction product discharged from the first gas-phase polymerization reactor passed through a filter separating unreacted gases and polymers; the polymer was then transferred to the second gas-phase polymerization reactor, while the separated unreacted gases passed through a purification tower and were injected into the first slurry polymerization reactor. Propane was used as a diluent for both the slurry polymerization reactor and the gas-phase polymerization reactor, and the copolymer of ethylene and 1-butene produced by the catalytic reaction was continuously discharged to maintain a constant fluidized bed height in the gas-phase polymerization reactor. To maintain a constant operating temperature, heat generated by the polymerization reaction was removed by controlling the temperature of the circulating gas using a heat exchanger.

[0196] Subsequently, the reaction product was discharged from the second gas phase polymerization reactor, and linear low-density polyethylene (LLDPE) resin was obtained as the final polymer through processes such as degassing and drying, and its physical properties were measured and shown in Table 2.

[0197]

[0198] Classification Example 5 Example 6 Example 7 Example 8 Example 9 Comparative Example 3 First Slurry Polymerization Reactor Catalyst Injection Amount (kg / h) 3.5 3.1 3.1 1.0 1.0 - Reactor Temperature (°C) 50 47 47 43 43 - Reactor Pressure (K / G) 25.4 25 425 425 25 - Ethylene Injection Amount (kg / h) 60 60 0 55 0 60 0 600 - Hydrogen Injection Amount (g / h) 0 0 20 44 - Comonomer Molar Ratio 0.15 80.26 80.19 20.25 0.25 - MIE (g / 10 min) 0.5 20.07 1.93 1.01.0 - Density (D) (g / cm³) 0.9 180 0.90 680.90 980.89 90.89 9 - Second Slurry Polymerization Reactor Reactor Temperature (°C) 50 46 46 43 43 - Reactor Pressure (K / G) 24 24 24 24 24 - Ethylene Injection (kg / h) 30 30 25 0 35 0 35 0 - Hydrogen Injection (g / h) 0 0 0 0 - Comonomer Molar Ratio 0.07 30.1 50 0.1 25 0.2 30.2 3 - MIE (g / 10 min) 0.7 20.4 21.5 30.7 0.7 - Density (D) (g / cm³) 0.9 1 75 0.9 0 70 0.9 0 84 0.8 9 7 0.8 7 - First Gas Phase Polymerization Reactor Reactor Temperature (°C) 4 3 4 1 4 1 4 2 4 2 - Reactor Pressure (K / G) 1 4 1 2.8 1 2.6 1 3 1 3 - Ethylene Injection Rate (kg / h) 1 5 0 1 5 5 0 1 5 5 1 3 0 0 3 0 0 3 - Ethylene Concentration (mol%) 4.6 3.7 4.4 7.0 6.1 - Hydrogen Concentration (mol ppm) 1 7 3 3 9 9 6 1 3 1 - Comonomer Molar Ratio 0.07 40.10 20.09 60.12 0.12 - MIE (g / 10 min) 0.95 1.14 3.115 0.11 0 - SR (F / E) 17.4 17.7 16.9 17.0 17.0 - Density (D) (g / cm³) 0.90 460.89 520.89 730.88 900.88 90 - Single Density (D) (g / cm³) 0.89 700.88 830.89 140.88 650.88 65 - Second Gas Phase Polymerization Reactor Reactor Temperature (°C) 43 41 41 41 41 - Reactor Pressure (K / G) 14 13.7 13.1 13 13 - Ethylene Injection volume (Kg / h) 5 2 2 5 5 0 1 5 7 2 8 6 7 0 6 4 0 0 - Ethylene concentration (mol%) 7.6 8.4 7.4 1 5.3 1 3.2 - Hydrogen concentration (mol ppm) 5 6 7 9 1 1 0 2 2 4 2 7 3 - Comonomer molar ratio 0.1 4 8 0.1 5 0 0.1 5 0 0.1 4 0.1 3 - MIE (g / 10min) 1)0.95 1.07 3.04 5.01 4.01 1.01 SR(F / E) 15.9 16.8 16.9 18 20 40.4 Density (D) (g / cm³) 0.89 0 0.88 5 10.88 5 60.88 40.88 20.88 73 Single Density (D) (g / cm³) 0.88 3 40.88 50.88 90.88 160.87 81 - Mn 63,802 58,804 44,21 239,368 25,208 N / AM w 133,985 123,984 91,888 81,331 58,493 N / AP 2.10 2.1 12.08 2.07 2.32 N / AT m (℃)68.9 / 105.662.2 / 95.363.6 / 98.764.3 / 74.865.6 / 7473.6T c (℃)49.3 / 87.044.7 / 74.944.3 / 77.660.260.660.1 / 72.7T g (℃)-42.7-44.1-44.5---40.9MIT 15 (℃) 52.6 48.5 46.1 46.5 45.5 N / A Comonomer (WH%) 17.9 19.6 20.2 20.021 N / A Fraction (WH%) 68 68 71 6764 - 60℃ or higher TREF Fraction (%) 18 108 N / AN / A 3

[0199] 1) The MIE in the second gas phase polymerization reactor is a measurement of the final polymer.

[0200]

[0201] In Table 2 above, the comonomer refers to 1-butene, and the comonomer molar ratio refers to the molar ratio of 1-butene to the total amount of ethylene and 1-butene.

[0202]

[0203] As shown in Tables 1 and 2 above, the polyolefin polymers of Examples 1 to 9 of the present invention have two T m Value (T m1 and T m2 It was confirmed that it has ). In this way, two T mWhen a specific value exists, only certain regions can be selectively melted when the polymer is heated, thereby enabling the removal of unnecessary components or the enhancement of desired physical properties. Therefore, the polyolefin polymer of the present invention has the advantage of being able to flexibly control mechanical or thermal properties depending on processing conditions.

[0204]

[0205] (Experimental Example)

[0206] Experimental Example 1: Confirmation of the structure of a polyolefin polymer

[0207] 1. Cross-section of the prepolymer

[0208] A cross-section of the prepolymer contained in the reaction product produced in the slurry polymerization reactor in Example 2 was captured using a scanning electron microscope (SEM), and the captured image is shown in Fig. 4a below.

[0209] Looking at Fig. 4a, it was seen that a prepolymer having a hollow structure was produced through the above slurry polymerization reaction to form the shell portion of the final polymer.

[0210] 2. Cross-section of the final polymer

[0211] A cross-section of the final polymer contained in the reaction product produced in the gas-phase polymerization reactor in Example 2 was captured using a scanning electron microscope (SEM), and the captured image is shown in Fig. 4b below. Here, the densities of the shell and core portions are shown in the image.

[0212] Looking at Fig. 4b, it was confirmed that a relatively low-density core portion was formed in the hollow of the prepolymer through the above-mentioned vapor phase polymerization reaction.

[0213] 3. Cross-section of the final polymer before and after dissolution in xylene

[0214] Using scanning electron microscopy (SEM), cross-sections of the final polymer contained in the reaction product produced in the gas phase polymerization reactor in Example 2 and cross-sections of the final polymer after dissolving it in a xylene solution were captured, and the captured images are shown in Fig. 4c below. Specifically, the left image of Fig. 4c is an image taken before dissolving the final polymer in a xylene solution, and the right image is an image after dissolving the final polymer in a xylene solution.

[0215] The xylene dissolution experiment described above is an experiment that confirms that the part with low density and high MI is dissolved and eluted in xylene. As shown in Fig. 4c, when the final polymer is dissolved in xylene, it can be confirmed that only the core part with relatively low density dissolves out, while the shell part with a high density of 0.916 remains undissolved. Through this, it can be confirmed that the final polymer according to the present invention has a core-shell structure in which a core part having low density is formed internally and a shell part having high density is formed externally surrounding the core part.

[0216] Experimental Example 2: Confirmation of TREF of Polyolefin Polymer

[0217] For the final polymers prepared in Examples 1 to 9 and Comparative Example 3, the TREF values ​​according to temperature were measured using the method described above to derive a temperature-raising elution fraction (TREF) chromatogram, which can be confirmed through Tables 1 and 2. Meanwhile, the temperature-raising elution fraction (TREF) chromatogram derived for the final polymers prepared in Example 5 and Comparative Example 3 can also be confirmed through Figure 5 below.

[0218] Looking at Tables 1 and 2 and Figure 5, it can be seen that the final polymer according to the embodiments of the present invention shows two peaks at a temperature of 31°C or higher, and the percentage value obtained by dividing the graph area at 60°C or higher by the total graph area is 5% or higher. On the other hand, it can be seen that the final polymer according to Comparative Example 3 shows one peak at a temperature of 31°C or higher, and the percentage value obtained by dividing the graph area at 60°C or higher by the total graph area is 3%.

[0219] [Explanation of the symbol]

[0220] 100: First slurry polymerization reactor

[0221] 110: Catalyst injection

[0222] 120: Feedstream Injection

[0223] 130: Circulation pump

[0224] 140: Heat exchanger

[0225] 150: Polymer extrusion

[0226] 151: First prepolymer discharge

[0227] 200: Second slurry polymerization reactor

[0228] 210: Injection of the first prepolymer

[0229] 220: Feedstream Injection

[0230] 230: Circulation pump

[0231] 240: Heat exchanger

[0232] 250: Second prepolymer discharge

[0233] 300: First gas phase polymerization reactor

[0234] 310: Prepolymer injection

[0235] 320: Feedstream Injection

[0236] 330: Compressor

[0237] 340: Heat exchanger

[0238] 350: Feedstream Injection

[0239] 360: First final polymer extrusion

[0240] 400: Second gas phase polymerization reactor

[0241] 410: First final polymer injection

[0242] 420: Feedstream Injection

[0243] 430: Compressor

[0244] 440: Heat exchanger

[0245] 450: Feedstream Injection

[0246] 460: Second final polymer extrusion

Claims

1. Density of 0.868 to 0.897 g / cm³ 3 And, The melt flow index (MIE (2.16 kg load, 190℃)) is 0.1 g / 10 min to 20.0 g / 10 min, and PDI is 1 to 5, and The number average molecular weight (Mn) is 20,000 to 70,000 g / mol, and The weight-average molecular weight (Mw) is 50,000 to 150,000 g / mol, and Two or more melting temperatures (T m A polyolefin polymer having ).

2. In Paragraph 1, The above polyolefin polymer is a polyolefin polymer manufactured through a continuous process comprising two or more reactions.

3. In Paragraph 2, A polyolefin polymer in which the two or more reactions above include one or more gas-phase polymerization reactions.

4. In Paragraph 1, A polyolefin polymer having a melt flow index (MIE (2.16 kg load, 190°C)) of 0.5 g / 10 min to 17.0 g / 10 min.

5. In Paragraph 1, The above melting temperature (T m ) is the first melting temperature (T m1 ) and the second melting temperature (T m2 Having ), the first melting temperature (T m1 A polyolefin polymer having a melting temperature of 45°C to 85°C and a second melting temperature of 70°C to 125°C.

6. In Paragraph 5, The above first melting temperature (T m1 A polyolefin polymer having a melting temperature of 55°C to 75°C and a second melting temperature of 70°C to 90°C.

7. In Paragraph 5, The above first melting temperature (T m1 ) and the second melting temperature (T m2 A polyolefin polymer in which the difference is 10 ℃ to 40 ℃.

8. In Paragraph 1, The above polyolefin polymer is a polyolefin polymer having a melt flow index ratio (SR) of 15 to 25.

9. In Paragraph 1, The above polyolefin polymer is a polyolefin polymer that exhibits two or more peaks at a temperature of 31°C or higher in a temperature-raising elution fraction (TREF) chromatogram, and has a percentage value of 5% or more obtained by dividing the graph area at 60°C or higher by the total graph area.

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