Preparation process for de-entangled ultra-high molecular weight isotactic polypropylene

Abstract

Summary of the Invention Preparation process of deentangled ultra-high molecular weight isotactic polypropylene The present invention relates to a process for preparing deentangled ultra-high molecular weight isotactic polypropylene. The deentangled ultra-high molecular weight isotactic polypropylene of the present invention exhibits low entanglement density, low bulk density, and spherical morphology. Furthermore, the deentangled ultra-high molecular weight isotactic polypropylene of the present invention does not require energy-intensive and expensive post-production treatment to reduce the entanglement density.

Description

[Technical Field]

[0001] Field of Invention This invention relates to a process for preparing de-entangled ultra-high molecular weight isotactic polypropylene.

[0002] Definition of Terms The following terms used in this invention are intended to have the meanings defined below in general, unless otherwise specified in the context. Isotactic polypropylene: Polypropylene in which all methyl groups are stereochemically oriented along the same side of the polymer backbone. Storage modulus and loss modulus: The storage modulus of viscoelastic materials such as polymers relates to the elastic component and measures the material's capacity to elastically conserve energy. The storage modulus can be defined as the ratio of the stress-elastic component to the strain. The loss modulus relates to the viscous portion of the material and measures the material's ability to dissipate stress as heat. The loss modulus can be defined as the ratio of the stress-viscous component to the strain. Vibratory flow measurement method: Used to analyze the viscous and elastic properties of materials on different time scales. It is a useful tool for understanding the structural and dynamic properties of viscous and elastic materials. The basic principle of a vibratory flow measurement device is to induce sinusoidal shear deformation in the sample and measure the resulting stress response. The time scale sampled is determined by the amplitude frequency (ω) and the shear deformation frequency. De-entanglement polymer: A polymer in which the polymer chains resist the tendency to become entangled with each other. [Background technology]

[0003] Background of the invention The following background information pertains to the present invention and does not necessarily pertain to prior art. Ultra-high molecular weight polymers are used in engineering applications such as ballistic missiles, medical prosthetics, and high-strength tapes. Ultra-high molecular weight isotactic polypropylene (UHMWiPP) is low-density, has excellent heat resistance, high rigidity, is inherently biocompatible, and possesses outstanding fatigue resistance. Potential applications include those in biomedical, aerospace, and automotive industries where fatigue is a major requirement. In UHMWiPP, the physical properties are strongly related to the molecular weight (M). UHMWiPP is generally processed in a molten state, where the polymer chains react with each other, leading to confounding. Such confounding is defined as a physical constraint or friction point that hinders the flowability of the polymer. Therefore, the probability of confounding increases with high molecular weight, as in the case of UHMWiPP. The relationship between molten viscosity (η0) and molecular weight is shown below: η0∝ M 3.4

[0004] Due to the relationship between the molecular weight and molten viscosity of UHMWiPP, processing UHMWiPP using conventional methods is impossible. As a result, alternative processing methods have been studied to reduce the confounding density of UHMWiPP while maintaining high mechanical properties. Conventional methods for reducing confounding density have been expensive and energy-intensive. Therefore, it seems necessary to have a preparation process for de-contangled ultra-high molecular weight isotactic polypropylene that mitigates the aforementioned disadvantages. [Overview of the project] [Problems that the invention aims to solve]

[0005] Purpose of the invention Some of the objectives of the present invention can be adequately expressed by at least one example described herein, which is as follows: The object of the present invention is to improve one or more problems of the prior art or to provide at least a useful alternative. Another object of the present invention is to provide a method for preparing de-entanglement type ultra-high molecular weight isotactic polypropylene exhibiting low entanglement density, low bulk density, and a spherical morphology. Another objective of the present invention is to provide a de-entanglement type ultra-high molecular weight isotactic polypropylene exhibiting low entanglement density, low bulk density, and a spherical morphology. Other purposes and advantages of the present invention will become even clearer by the following explanation, which is not intended to limit the scope of the invention.

[0006] Summary of the Invention This invention relates to a process for preparing de-entanglement type ultra-high molecular weight isotactic polypropylene. In this process, at least one scavenging agent is added to a reactor containing at least one hydrocarbon solvent maintained in an inert atmosphere, and the mixture is stirred to obtain a mixture. The mixture is first stirred under predetermined conditions to obtain a first solution. Next, propylene gas at a pressure range of 1 bar to 3 bar is introduced into the reactor, and a second solution is obtained by maintaining second predetermined conditions. A predetermined amount of a pre-activated catalyst family is added to the second solution. The pre-activated catalyst family is obtained by reacting one type of catalyst with an activator, where the catalyst has the structural formula shown in Formula 1.

[0007] [ka] Here, R1, R2, and R3 are isopropyl.

[0008] The reactor is maintained under third predetermined conditions to obtain a third solution containing crude de-entanglement type ultra-high molecular weight isotactic polypropylene (UHMWiPP). The third solution is cooled in the reactor to obtain a cooled third solution containing a precipitate of crude UHMWiPP. The cooled third solution containing the precipitate of crude UHMWiPP is removed from the reactor and filtered to obtain a residue of wet crude UHMWiPP. The residue of wet crude UHMWiPP is washed with ethanol and dried to obtain de-entanglement type UHMWiPP.

[0009] The present invention further relates to a pre-activated catalyst group used for the preparation of UHMWiPP. The pre-activated catalyst group is composed of a catalyst compound of formula 1 and an activator in a ratio ranging from 1:1 to 1:10. The catalyst has a structural formula represented by formula 1. Furthermore, the present invention relates to a crosslink-disengaged ultra-high molecular weight isotactic polypropylene having the following characteristics: · Molecular weight range 500,000 - 4,000,000 g / mol · Bulk density range 0.07 g / cm 3 ~0.7 g / cm 3 · Spherical shape with a diameter range of 300 μm and 600 μm · Melting point range 155 °C - 160 °C · The storage modulus (G') and loss modulus (G'') increased stepwise by at least 20% as a function of time during the oscillatory shear strain time sweep experiment under viscoelastic control at 190 °C, 10 rad / s, and an axial force range of 0.1 N - 1 N. · The processing temperature is below the melting point of the ultra-high molecular weight isotactic polypropylene. · Compression molding and rolling temperature range 125 °C - 150 °C

Brief Description of the Drawings

[0010] The present invention will be described with reference to the accompanying drawings. The drawings are as follows: [Figure 1] Figure 1-a shows the bulk density measurement results of UHMWiPP prepared according to Example 1 of the present invention. Figure 1-b shows the bulk density measurement results of UHMWiPP prepared according to Example 2 of the present invention. Figure 1-c shows the bulk density measurement results of UHMWiPP prepared according to Example 3 of the present invention. Figure 1-d shows the bulk density measurement results of UHMWiPP prepared by using a Ziegler-Natta catalyst system (comparative example). [Figure 2] Figure 2 shows a scanning electron micrograph of UHMWiPP prepared according to Example 2 of the present invention (scale bar: 500 microns). [Figure 3]Figure 3 shows the 13C NMR measurement results of UHMWiPP prepared according to Example 2 of the present invention after proton decoupling treatment. [Figure 4] Figure 4-a shows the differential scanning calorimeter measurement results for UHMWiPP prepared according to Example 2 of the present invention to analyze the effect of confounding density on isothermal crystallization. Figure 4-b shows the results of the dynamic oscillatory flow measurement method (time scanning), i.e., the measurement results of the storage modulus as a function of time for UHMWiPP prepared according to Examples 1, 2, and 3 of the present invention to analyze the effect of residency time, which is the molten state, on the formation of confounding. Figure 4-c shows the results of the dynamic oscillatory flow measurement method (time scanning), i.e., the measurement results of the loss modulus as a function of time for UHMWiPP prepared according to Examples 1, 2, and 3 of the present invention to analyze the effect of residency time, which is the molten state, on the formation of confounding. [Figure 5] Figure 5-a shows the measurement results of the dynamic oscillatory fluid assay (frequency scanning) used to obtain the estimated molecular weight of UHMWiPP prepared according to Example 1 of the present invention. Figure 5-b shows the measurement results of the dynamic oscillatory fluid assay (frequency scanning) used to obtain the estimated molecular weight of UHMWiPP prepared according to Example 2 of the present invention. Figure 5-c shows the measurement results of the dynamic oscillatory fluid assay (frequency scanning) used to obtain the estimated molecular weight of UHMWiPP prepared according to Example 3 of the present invention. Figure 5-d shows the results of the superposition measurement of the dynamic oscillatory fluid assay (frequency scanning) used to obtain the estimated molecular weight of UHMWiPP prepared according to Examples 1, 2, and 3 of the present invention. [Figure 6] Figure 6 shows the measurement results of a dynamic oscillatory fluid measurement method (frequency scanning) used to obtain the estimated molecular weight of UHMWiPP prepared according to Example 4 of the present invention. [Modes for carrying out the invention]

[0011] Detailed description of the invention Embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiments described herein will allow a person skilled in this art to fully and completely grasp the scope of the present invention. Numerous details relating to individual components will allow for a complete understanding of the embodiments of the present invention. It will be clear to a person skilled in this art that the details described in the embodiments cannot be interpreted as limiting the scope of the present invention. Some embodiments do not describe in detail well-known processes, well-known apparatus structures, or well-known techniques. In this invention, the terms used herein are used solely to describe specific embodiments and should not be considered to limit the scope of the invention. Nouns used herein include multiple things unless the context requires them to be treated as singular. Terms such as "consisting of," "including," "composed of," and "consisting of" are transitional phrases that may include other things and thus define the existence of functions, features, integers, procedures, operations, elements, modules, units, or components described herein, but do not exclude the existence or addition of other functions, integers, procedures, operations, elements, components, or groups of components. The order of specific procedures disclosed in the methods and processes of this invention should be interpreted as meaning that the performance described or illustrated is not necessarily an essential element. It should also be understood that additional or alternative procedures may be used.

[0012] The physical properties of UHMWiPP depend on its molecular weight. When UHMWiPP reaches a molten state during processing, its polymer chains become entangled with each other, hindering the polymer's fluidity. For ultra-high molecular weight polyolefins such as isotactic polypropylene, the probability of entanglement increases with increasing molecular weight, and therefore the viscosity of the molten UHMWiPP increases exponentially as its molecular weight increases. Due to the relationship between the molecular weight and molten viscosity of UHMWiPP, processing UHMWiPP using conventional methods is impossible. Therefore, an alternative processing method is needed to reduce the confounding density of UHMWiPP while preserving its high level of mechanical properties. In recent years, gelation, crystallization, and gel-like spherulite pressing (GSP) methods have been used commercially to produce low-entanglement-density ultra-high molecular weight polyethylene (UHMWPE) fibers. However, these methods are primarily post-production processes and are expensive and energy-intensive. This invention provides a preparation process for a de-contangled UHMWiPP having low contangle density, low bulk density, and spherical morphological characteristics. The de-contangled UHMWiPP of this invention eliminates the need for costly and time-wasting post-production processing required to reduce contangle density.

[0013] In a first embodiment of the present invention, a process for preparing de-entangled ultra-high molecular weight isotactic polypropylene is provided. This process will be explained in detail below. First, a reactor containing at least one hydrocarbon solvent is maintained in an inert atmosphere, at least one scavenging agent is added thereto to obtain a mixture, and this mixture is stirred under first predetermined conditions to obtain a first solution.

[0014] According to embodiments of the present invention, the hydrocarbon solvent is selected from at least one of toluene and heptane. In one embodiment, the hydrocarbon solvent is heptane. According to embodiments of the present invention, the erasing agent is selected from methylalmoxane (MAO) and triisobutylaluminum (TiBA). In one embodiment, the erasing agent is triisobutylaluminum (TiBA). Typically, eliminators function as evidence of impurities. Examples include oligomers and polymeric aluminumoxanes such as methyl aluminum (MAO), and alkylated metals such as triisobutylaluminum (TiBA). The preparation process for de-entangled ultra-high molecular weight isotactic polypropylene is carried out in an inert atmosphere. In one embodiment, the inert atmosphere is maintained by the use of nitrogen gas.

[0015] According to embodiments of the present invention, the first given conditions include a temperature range of 10°C to 70°C, a time range of 10 minutes to 30 minutes, and a stirring speed range of 150 rpm to 350 rpm to obtain the first solution. In one embodiment, the temperature is 40°C, the time is 20 minutes, and the stirring speed is 250 rpm. Next, propylene gas at a pressure range of 1 bar to 3 bar is introduced into the reactor, and the second solution is obtained while maintaining the second predetermined conditions. In one embodiment, the pressure of the propylene gas is 1.1 bar. It was found that propylene pressure conditions can enhance the morphological characteristics of the de-entangled UHMWiPP. According to embodiments of the present invention, the second given conditions include a temperature range of 10°C to 70°C and a stirring rotation speed range of 650 rpm to 850 rpm. In one embodiment, the temperature is 40°C and the stirring rotation speed is 750 rpm.

[0016] Next, a predetermined amount of the pre-activated catalyst is added to the second solution. Then, the reactor is maintained under third predetermined conditions to obtain a third solution containing coarsely de-entangled ultra-high molecular weight isotactic polypropylene (UHMWiPP). The pre-activated catalyst group is obtained by reacting the catalyst with an activator, and the catalyst has the structure shown in formula 1.

[0017] [ka]

[0018] In one embodiment of the present invention, the alkyl groups R1, R2, and R3 are isopropyl. When R3 = hydrogen atom (H) is evaluated in relation to the polymerization of propylene, the thermal properties of the obtained polymer are lower than when R3 = isopropyl. According to embodiments of the present invention, the activator is at least one selected from N,N'-dimethylanilinium tetrakiss(pentafluorophenyl) borate, trityltetrakiss(pentafluorophenyl) borate, tris(allyl-substituted) borane, and derivative compounds thereof. In one embodiment, the activator is N,N'-dimethylanilinium tetrakiss(pentafluorophenyl) borate. According to embodiments of the present invention, the catalyst-to-activator ratio is in the range of 1:1 to 1:10. In one embodiment, this ratio is 1:1. In other embodiments, this ratio is 1:2. According to embodiments of the present invention, the third given conditions include a temperature range of 10°C to 70°C, a time range of 1 hour to 3 hours, and a stirring rotation speed range of 650 rpm to 850 rpm. In one embodiment, the temperature is 40°C, the time is 1 hour, and the stirring rotation speed is 750 rpm. In another embodiment, the time is 2 hours. In yet another embodiment, the time is 3 hours.

[0019] For the production of ultra-high molecular weight propylene with reduced confounding density and delicate spherical morphological characteristics, hafnium complex-based catalysts require an activation step. Typically, the catalyst is activated by binding with a suitable activator, which completes the activation in the presence of propylene monomers. Generally, a wide variety of activators are used, including almoxanes, Lewis acids, Brønsted acids, and possible combinations. Preferred activators are anions (Brønsted acids) and M(C6F5)4, which have the ability to cleave the H-Me bond by simple protonolysis. - It is assumed that the anions include non-coordinating / weakly coordinating anions such as (M: B, Al). According to embodiments of the present invention, the catalyst-to-scattering agent ratio is in the range of 1:50 to 1:100. In one embodiment, this ratio is 1:70. The third solution is cooled in a reactor to obtain a cooled third solution containing a precipitate of the coarsely de-entangled UHMWiPP. In one embodiment, this cooling is carried out using ethanol.

[0020] The cooled third solution containing the precipitate of the crude de-entanglement type UHMWiPP is removed from the reactor, and the cooled third solution is filtered to obtain the residue of the wet crude UHMWiPP. The residue of the wet crude de-entanglement type UHMWiPP is washed and dried to obtain the de-entanglement type UHMWiPP. Furthermore, the present invention relates to a group of pre-activated catalysts used in the production of UHMWiPP. The group of pre-activated catalysts consists of a catalyst having the structure of Formula 1 and an activator in a ratio in the range of 1:1 to 1:10. The catalyst has the structure shown in Formula 1.

[0021] [ka]

[0022] In one embodiment, the activator is N,N'-dimethylanilinium tetrakis(pentafluorophenyl) borate, and the catalyst-to-activator ratio is 1:1. In one embodiment, the preparation process for de-contangled ultra-high molecular weight isotactic polypropylene includes the following steps: First, at least one scavenging agent is added to a reactor containing at least one hydrocarbon solvent maintained in an inert atmosphere, and the mixture is stirred to obtain a first solution. This mixture is stirred at a temperature of 40 °C and a rotation speed of 250 rpm for 20 minutes. Next, propylene gas is introduced into the reactor at a pressure of 1.1 bar and a temperature of 40 °C, and stirring is continued at a rotation speed of 750 rpm to obtain a second solution. A predetermined amount of pre-activated catalysts is added to the second solution. The pre-activated catalysts are obtained by reacting one type of catalyst with an activator, and the catalyst has the structural formula shown in Equation 1.

[0023] [ka] Here, R1, R2, and R3 are isopropyl.

[0024] Next, while maintaining the reactor at 40°C, stir at a stirring rotation speed of 750 rpm for a time range of 1 hour to 3 hours to obtain a third solution containing a crude crosslink-disengaged ultra-high molecular weight isotactic polypropylene (UHMWiPP). Cool the third solution in the reactor to obtain a cooled third solution containing a precipitate of crude UHMWiPP. Remove the cooled third solution containing the precipitate of crude UHMWiPP from the reactor, and filter the cooled third solution to obtain a residue of wet crude UHMWiPP. Wash the residue of wet crude UHMWiPP with ethanol and dry it to obtain crosslink-disengaged UHMWiPP. According to an embodiment of the present invention, the average molecular weight of the crosslink-disengaged ultra-high molecular weight isotactic polypropylene is in the range of 500,000 to 4,000,000 g / mol. In one embodiment, the average molecular weight is 800,000 g / mol. In other examples, the average molecular weight is 2,400,000 g / mol. In still other examples, the average molecular weight is 3,000,000 g / mol.

[0025] According to an embodiment of the present invention, the bulk density range of the crosslink-disengaged ultra-high molecular weight isotactic polypropylene is 0.05 g / cm 3 ~0.12 g / cm 3 . In one embodiment, the bulk density is 0.065 g / cm 3 . In other examples, the bulk density is 0.095 g / cm 3 . In still other examples, the bulk density is 0.105 g / cm 3 . According to an embodiment of the present invention, the crosslink-disengaged ultra-high molecular weight isotactic polypropylene is spherical particles with a diameter range of 300 μm to 600 μm. In one embodiment, the diameter is 500 μm. In other examples, the diameter is 600 μm. According to embodiments of the present invention, the storage modulus (G') and loss modulus of unentangled ultra-high molecular weight isotactic polypropylene exhibit a stepwise increase of 20% or more as a function of time during vibration-shear-strain time scanning experiments under viscoelastic control at 190 °C, 10 rad / s, and an axial force range of 0.1 N to 1 N. In one embodiment, during vibration-shear-strain time scanning experiments under viscoelastic control at 190 °C, 10 rad / s, and an axial force of 0.1 N, the storage modulus and loss modulus increased stepwise by 20% as a function of time. In other embodiments, during vibration-shear-strain time scanning experiments under viscoelastic control at 190 °C, 10 rad / s, and an axial force of 1 N, the storage modulus and loss modulus increased stepwise by 36% and 39%, respectively, as a function of time. In further embodiments, the storage modulus and loss modulus increased in stepwise manner by 31% and 32%, respectively, as a function of time, during vibration-shear-strain time scanning experiments under viscoelastic control at 190 °C, 10 rad / s, and an axial force of 1 N.

[0026] According to embodiments of the present invention, the melting point of the de-entangled ultra-high molecular weight isotactic polypropylene is in the range of 155 °C to 160 °C. In one example, the melting point is 158 °C. In another example, the melting point is 159 °C. In yet another example, the melting point is 160 °C. According to embodiments of the present invention, the processing temperature of the de-entanglement type UHMWiPP is below the melting point of the ultra-high molecular weight isotactic polypropylene. According to embodiments of the present invention, the compression molding and rolling temperatures are in the range of 125 °C to 150 °C. In one embodiment, the compression molding and rolling temperatures are 135 °C. In another embodiment, the molding and rolling temperatures are 130 °C.

[0027] Furthermore, the present invention provides a de-entanglement type ultra-high molecular weight isotactic polypropylene having the following properties: Molecular weight range: 500,000 to 4,000,000 g / mol • Bulk density range: 0.09 g / cm³ 3 ~0.12 g / cm3 • Spherical shape with diameters ranging from 300 μm to 600 μm. Melting point range: 155°C to 160°C • The storage modulus, modulus of elasticity, and loss modulus of elasticity increased in steps of at least 20% as a function of time during vibration-shear-strain time scanning experiments under viscoelastic control at 190 °C, 10 rad / s, and an axial force range of 0.1 N to 1 N. • The processing temperature is below the melting point of the ultra-high molecular weight isotactic polypropylene. • Compression molding and rolling temperature range is 125°C to 150°C.

[0028] In the examples, the de-entanglement type ultra-high molecular weight isotactic polypropylene has the following properties: ·Molecular weight 800,000 g / mol • Bulk density: 0.065 g / cm³ 3 Particle size 600 μm, melting point 159°C During a vibration-shear-strain time-scan experiment under viscoelastic control at 190°C, 10 rad / s, and an axially acting force of 0.1 N, the storage modulus and loss modulus increased in 20% steps as a function of time. • The processing temperature is below the melting point of the ultra-high molecular weight isotactic polypropylene. • The molding and rolling temperature is 130°C.

[0029] In another embodiment, the de-entangled ultra-high molecular weight isotactic polypropylene has the following properties: ·Molecular weight 2,400,000 g / mol • Bulk density: 0.095 g / cm³ 3 ·Particle size 500μm • Melting point 158℃ During vibration-shear-strain time-scanning experiments under viscoelastic control at 190°C, 10 rad / s, and an axial force of 1N, the storage modulus and loss modulus increased in steps of 36% and 39%, respectively, as a function of time. • The processing temperature is below the melting point of the ultra-high molecular weight isotactic polypropylene. • The molding and rolling temperature is 130°C.

[0030] Furthermore, in one embodiment, the de-entangled ultra-high molecular weight isotactic polypropylene has the following properties: ·Molecular weight 3,000,000 g / mol • Bulk density: 0.105 g / cm³ 3 ·Diameter 500μm • Melting point 158℃ During vibration-shear-strain time-scanning experiments under viscoelastic control at 190°C, 10 rad / s, and an axial force of 1N, the storage modulus and loss modulus increased in steps of 31% and 32%, respectively, as a function of time. • The processing temperature is below the melting point of the ultra-high molecular weight isotactic polypropylene. • The molding and rolling temperature is 130°C.

[0031] This invention provides a preparation process for a de-contangled UHMWiPP having low contangle density, low bulk density, and spherical morphological characteristics. The de-contangled UHMWiPP of this invention eliminates the need for costly and time-wasting post-production processing required to reduce contangle density. The foregoing description of embodiments is for illustrative purposes only and is not intended to limit the scope of the invention to that description alone. Individual components of a particular embodiment are generally not limited to that particular embodiment and are interchangeable. Such variations cannot be considered different from the invention, and all such variations are considered to be within the scope of the invention. The present invention will be further illustrated by the following non-limiting embodiments. However, the following examples are provided for illustrative purposes only and should not be construed as limiting the scope of the invention. The following experiments can be scaled up to an industrial / commercial scale, and the results obtained can be extrapolated to an industrial scale. [Examples]

[0032] Experiment details Preparation and qualitative process of de-entanglement type ultra-high molecular weight isotactic polypropylene according to the present invention. The de-entanglement type ultra-high molecular weight isotactic polypropylene of the present invention was qualitatively analyzed using the following method / procedure: Bulk density measurement: 0.2 g of decontamination-free UHMWiPP was weighed out and placed in a 5 mL graduated cylinder. The density was identified by calculating the ratio between the amount of polymer (g) and the volume it occupied in the cylinder (ml). Measurement of the percentage of isotactic physical properties: The percentage of isotactic properties is expressed in percent pentads (% mmmm). 13 Identified by 13C NMR spectroscopy. Proton decoupling treatment. 13 C{ 1 ¹H} NMR measurements were performed using a Bruker Avance Neo 400 NMR spectrometer, and the chemical shift was internally referenced to the methyl signal of the isostatic pentad (mmmm) at ~21.85 ppm. Typically, 50–60 mg of decontamination-free UHMWiPP samples were dissolved in C6D5Br at high temperature. % mmmm was quantified by integrating the methyl region from 22.0–19.7 ppm and reported as fractional moles in percent. Polymers synthesized by the route disclosed in this invention exhibit high isostatic properties (>90%).

[0033] Measurement of crystallinity: The percentage of crystallinity was determined by differential scanning calorimeter (DSC). The percentage of crystallinity was identified using commercially available DSC instruments such as the TA Instruments Q250 and TRIOS software. The percentage of crystallinity was calculated using the first melt endotherm (100-180 °C) and a heating rate of 10 °C / min to determine the normalized heat of fusion (ΔH) of the sample. f This was determined by calculating theoretical values ​​for ) and 100% crystalline iPP (204 J / g).

[0034] Differential scanning calorimeter (DSC): 1. Prepared according to the present invention Confounding-removing type Qualitative analysis of confounding density in UHMWiPP:Differential scanning calorimetry was performed using commercially available equipment (such as TA Instruments' Q250 DSC) to identify the effect of the molten state residency time on crystallization dynamics under isothermal conditions (related to the formation of confounding due to annealing of the sample in the molten material). Samples were prepared using Tzero® aluminum pans and lids. 1.5 mg of polymer sample was placed in the pan and sealed using a commercially available micropress (TA Instruments). After sealing the pan, the intrinsic heat treatment procedure was applied to the sample according to (Liu, K.; De Boer, EL; Yao, Y.; Romano, D.; Ronca, S.; Rastogi, S., Macromolecules 2016, 49 (19), 7497-7509, referenced in this document). The sample was heated to 50 °C in a nitrogen atmosphere, then heated at a constant rate of 10 °C / min to 200 °C until equilibrium was reached. At 200 °C, different isothermal durations (3 minutes, 1 hour, 24 hours) were applied to evaluate the effect on confounding density. After this time, the sample was cooled to 135 °C at a constant rate of 10 °C / min. The resident time under isothermal conditions (135 °C) was set to 3 hours. Finally, the sample was cooled to 50 °C at a constant rate of 10 °C / min.

[0035] 2. Melting point measurement of UHMWiPP after untangling: DSC was also used to determine the melting point of the untangled UHMWiPP prepared according to the present invention. The melting point varied depending on the polymerization conditions and was in the range of 150-160 °C. Measurement by the vibrational fluid dynamics method: Qualitative analysis of confounding density was performed using the oscillatory fluid measurement method, and dynamic frequency scanning and time scanning experiments were conducted using commercially available equipment (such as the Anton-Paar MCR 702 multi-drive rheometer) to determine the effects of time, temperature, frequency, and combinations thereof on the loss modulus and storage modulus (which belong to the formation of confounding). Typically, 0.5 g of de-conjugated UHMWiPP was placed in a 25 mm diameter circular stainless steel mold and subsequently compressed at 125 °C for 30 minutes using a maximum load of 30 bar. The sample was cooled at a rate of 10 °C / min under constant pressure of 30 bar. The sample was then placed between rheometer plates at 110 °C and subsequently heated at a constant rate to 190 or 220 °C. Next, amplitude intensity scanning was performed at a constant frequency T (ω = 10 rad / s) and axial force in the range of 0.25 N to 4 N. Finally, amplitude frequency scanning was performed at a constant strain rate (selected from the previous procedure), frequency (ω = 10 rad / s), and axial force (0.25 N).

[0036] Furthermore, in accordance with the present invention, the effect of the time spent in the molten material on entanglement formation was evaluated using dynamic vibrational flow measurement (time scanning experiment). As described above, to prepare a viscous sample, entanglement-removing UHMWiPP was compressed at a high temperature below its melting point. This sample was heated from 110°C to 190°C (10°C / min). The sample was allowed to equilibrate for 3 minutes, and the vibration time experiment was conducted under linear viscoelastic control (10 rad / s, strain 0.1%). The storage modulus and loss modulus were calculated using the dynamic vibration-flow measurement method (time-scanning experiment) described above. As given by the following equation, the storage modulus of the decontamination type UHMWiPP is the confounding modulus (M) in the equilibrium elastic flat region. e ) is related to the molecular weight of each. G n 0 = g N ρRT / <M e >, here g N ρ is a numerical factor (1 or 4 / 5 depending on convection), ρ is density, R is the gas constant, and T is the absolute temperature. If the confounding density is low, M e Taking into account the high value, and since the other terms in the above equation are usually constants, the resulting elastic response (non-equilibrium) is G' <G n 0 Therefore, the stepwise increase of the storage modulus G' as a function of time in the molten material is due to the confounding density (low M e This suggests a gradual increase in ).

[0037] Based on the results of the vibration-shear-strain time scanning experiment of the present invention, UHMWiPP was classified as a decontamination type if, during the vibration-shear-strain time scanning experiment under viscoelastic control at 190 °C, 10 rad / s, and an axial force range of 0.1 N to 1 N, the storage modulus (G') and loss modulus (G'') increased stepwise by at least 20% as a function of time. Molecular weight measurement: Dynamic oscillatory fluid dynamics measurement experiments and gel permeation chromatography were used to determine the mass-average molecular weight (M) of the decontamination-free UHMWiPP sample. w ) and polydispersity (M w / M n The value of the confounding-removing UHMWiPP of the present invention was evaluated. w It was found that the value was in the range of 800,000 to 4,000,000. The polydispersity of the confounding-removing UHMWiPP of the present invention was found to be in the range of 2.0 to 15.0.

[0038] The reagents for the preparation of the confounding-free ultra-high molecular weight isotactic polypropylene of the present invention were qualitatively prepared using the following procedure: The activator and scavenger reagent solutions were prepared in a glove box under a pure nitrogen atmosphere using the standard Schlenk technique. All solvents used were anhydrous, deoxygenated, and purified using a solvent purification system (SPS). Preparation of activator reagent solution The weight of N,N′-dimethylanilinium tetrakis(pentafluorophenyl) borate (10 μmol, 8.16 mg) was measured using an antistatic funnel in a glove box. The compound was transferred to a 25 mL glass Schlenk vat and then dissolved using a magnetic bar with 5 mL of dry toluene from SPS. The compound was stirred at a constant temperature of 20 °C for 1 hour. Preparation of the elimination agent reagent solution: Inside the glove box, 0.55 mL of triisobutylaluminum (TiBA) solution (in 25 wt.% toluene) was placed in a 25 mL Schlenk vial. TiBA solution (700 μmol, 0.55 mL) was transferred from the stock solution container to the vial using a 1 mL plastic syringe and needle.

[0039] Preparation of de-contangled ultra-high molecular weight isotactic polypropylene: Example 1 : Polypropylene polymerization was carried out in a 1.5 L Bucky-Glasster batch reactor with a three-blade propeller, one thermocouple, and oil temperature control. The reactor was purged with 7 cycles of dry nitrogen (P: 2.5 bar) and vacuum (-1.0 bar). The purged reactor was filled with nitrogen and continuously heated to 125 °C. After temperature equilibrium, a high vacuum was maintained for at least 8–12 hours to purge the nitrogen and residual vapors. Next, the reactor temperature was set to the target value and the polymerization reaction was started at 40 °C. After the temperature stabilized, 750 mL of heptane was added to the reactor. The reactor was continuously stirred at 250 rpm under a dry nitrogen atmosphere. After the temperature stabilized, 700 μmol (0.55 mL) of the scavenging reagent prepared as described above, i.e., TiBA solution, was injected into the reactor while continuously flowing nitrogen, and stirred at 250 rpm for 20 minutes to obtain the first solution. The catalyst:scavenging ratio was 1:70. Next, a high vacuum was applied until the reactor pressure reached -0.9 bar. Once the pressure stabilized, the vacuum was stopped, and the propylene monomer was added to the mixture and introduced into the reactor with continuous stirring (750 rpm) at a constant absolute pressure of 1.1 bar to obtain the second solution.

[0040] Separately, 10 μmol (7.19 mg) of the N-[2,6-bis(1-methylethyl)phenyl]-α-[2-(1-methylethyl)-phenyl]-6-(1-naphthalenyl-κC2)-2-pyridinemethamine(2-)-κN1,κN2]dimethylhafnium catalyst (compound of formula 1) was weighed out using an antistatic funnel from a glove box. This catalyst was dissolved in a Schlenk tube using 4 mL of dry toluene from a magnetic bar and solvent purification system (SPS) and added to the tube. After continuous mixing for 1 minute, 5 mL of the N,N′-dimethylanilinium tetrakis (pentafluorophenyl) borate solution (10 μmol, 8.16 mg) prepared as described above was reacted with the catalyst solution to obtain a solution containing the pre-activated catalyst group. The catalyst:scavenger ratio was maintained at 1:1. The solution containing the pre-activated catalyst group was continuously stirred for 5 minutes. The polymerization reaction was initiated by adding 9 mL of a pre-activated catalyst to the second solution for 10 minutes under continuous flow of propylene monomer and constant stirring (750 rpm). After 1 hour of reaction, a third solution containing untangled ultra-high molecular weight crude isotactic polypropylene (UHMWiPP) was obtained.

[0041] The third solution was cooled by injecting 5 mL of ethanol (70% v / v) into the third solution in the reactor to release the residual propylene monomer in the reactor, yielding a cooled third solution containing a precipitate of crude de-entangled UHMWiPP. After the polymerization cooled, the reactor temperature was set to 23 °C, and after the temperature stabilized, the reactor was opened and the cooled third solution containing the precipitate of de-entangled crude UHMWiPP was collected. Next, the cooled third solution containing the precipitate of de-entangled crude UHMWiPP was washed twice with excess ethanol and filtered under reduced pressure to obtain wet crude UHMWiPP. Next, the wet crude UHMWiPP was dried at room temperature for at least 7 days. UHMWiPP can also be obtained by drying the wet crude UHMWiPP at 40 °C and under reduced pressure for 12 hours. Example 2 Example 2 was carried out in the same manner as Experiment 1, except that the polymerization reaction was performed for 2 hours. Example 3 Example 3 was carried out in the same manner as Experiment 1, except that the polymerization reaction was performed for 3 hours. The physical properties of the untangled UHMWiPP obtained from Examples 1, 2, and 3 are shown in Table 1 below.

[0042] [Table 1] The bulk density measurements of decontamination-free UHMWiPP prepared according to Examples 1, 2, and 3 are shown in Figures 1-a, 1-b, and 1-c. As shown in Figure 1-d, the bulk density of UHMWiPP prepared using the Ziegler-Natta catalytic system was 0.669 g / cm³. 3 This was higher than the bulk density of the de-entangled UHMWiPP prepared according to the present invention. The size of the de-entangled UHMWiPP measured using a scanning electron microscope is shown in Figure 2. The size of the de-entangled UHMWiPP prepared according to Example 2 was 500 microns. The percentage of isostatic properties of the de-entangled UHMWiPP prepared according to the present invention was calculated using proton decoupling carbon NMR as shown in Figure 3 (Example 2). For the de-entangled UHMWiPP prepared by the above example, the percentage of isostatic properties was found to be >90%. The molecular weight of the de-entangled UHMWiPP obtained from Examples 1, 2, and 3 was measured by dynamic oscillatory flow spectroscopy. The results are shown in Figures 5-a, 5-b, and 5c. Figure 5-d shows a superposition of the oscillatory flow spectroscopy measurement results for the de-entangled UHMWiPP obtained from Examples 1, 2, and 3. Measurements were recorded using different frequency scanning techniques, and then analyzed to obtain estimated molecular weight and polydispersity values.

[0043] Differential scanning calorimetry was performed on the de-entangled UHMWiPP obtained in Example 2, and the entanglement density was evaluated as shown in Figure 4-a. The effect of the time spent in the molten material under isothermal conditions on the crystallization time is summarized in Table 2 below.

[0044] [Table 2] As shown in Figure 4-a, the residency times in the molten state (200 °C) were set to 3 minutes, 1 hour, and 24 hours. When the sample was kept in the molten state for a relatively short time (3 minutes, black line), nucleation and crystal growth proceeded rapidly, as shown at the start of the curve (~1 minute) and the maximum height (~20 minutes), respectively. Conversely, as the residency time of the molten material increased (e.g., 1 hour and 24 hours), the start time increased (5 minutes and 10 minutes), and the overall curve shape broadened (red and blue curves, respectively). These results revealed the presence of a low confounding density in the untangled UHMWiPP prepared according to Example 2 of the present invention. Furthermore, when the sample was kept in the molten state for a longer period, the chains began to tangle again in a stepwise manner. The confounding inhibited nucleation and, as a result, acted as a mobility restrictor, prolonging the crystallization process of the material. As shown in Table 2, the increased time spent in the molten state resulted in a delay in nucleation (initiation) and crystal growth, which are identified by the maximum enthalpy value expressed as a function of time.

[0045] As shown in Figures 4-b and 4-c, the confounding density of the de-contangled UHMWiPP prepared according to Examples 1, 2, and 3 was evaluated by measuring the storage modulus and loss modulus as a function of time using dynamic vibrational flow measurement. Figure 4-b shows that the storage modulus of the de-contangled UHMWiPP prepared according to Examples 1, 2, and 3 of the present invention increased by at least 20% by the end of the experiment. Similarly, as shown in Figure 4-c, the loss modulus of the de-contangled UHMWiPP prepared according to Examples 1, 2, and 3 of the present invention increased by at least 20% by the end of the experiment. These results were determined to be due to the heterogeneous (non-equilibrium) distribution of confounding in the molten state. Therefore, Figures 4-b and 4-c suggest that the confounding density of the UHMWiPP prepared according to Examples 1, 2, and 3 was low at the start of the experiment, and that the confounding density increased gradually, as evidenced by the stepwise increase in the storage modulus and loss modulus as a function of time in the molten material. Figures 4b and 4c (green graphs marked with downward-pointing triangles) also show that the storage modulus and loss modulus of the UHMWiPP prepared using the Ziegler-Natta catalyst system (comparative example) increased by only 10% as a function of time, indicating that the UHMWiPP prepared using the Ziegler-Natta catalyst system was not decontangled when compared to the decontangled UHMWiPP prepared according to Examples 1, 2, and 3 of the present invention.

[0046] Example 4 Example 4 was carried out in the same manner as Experiment 2, except that 20 μmol of N,N′-dimethylanilinium tetrakis(pentafluorophenyl) borate was used. The catalyst-to-scattering ratio was maintained at 1:2. The polymerization results are shown in Table 3 below:

[0047] [Table 3] Table 3 shows that the de-confounding UHMWiPP synthesized using a catalyst-to-activator ratio of 1:2 has a gel-like morphology, demonstrating that the 1:1 sample also exhibits a fine gel-like morphology.

[0048] As shown in Figure 5-d, the molecular weight and polydispersity of the de-contradiction type UHMWiPP prepared according to Examples 1, 2, and 3 were calculated from measurements using the vibrational flow spectroscopy method. Furthermore, the thermophysical properties of the decontamination-free UHMWiPP prepared according to Examples 1, 2, 3, and 4 were measured using DSC, and the results are summarized in Table 4 below:

[0049] [Table 4]

[0050] As is clear from the table, the melting point range of the de-entanglement type UHMWiPP of the present invention is 158 °C to 160 °C, and the degree of crystallinity of the de-entanglement type UHMWiPP prepared according to Examples 1, 2, 3, and 4 is 55 to 60%. The present invention provides a method for preparing a contangle-free UHMWiPP characterized by low contangle density, low bulk density, and a spherical shape, and which does not require post-processing to reduce contangle density.

[0051] Technological advancements and economic significance The process of the present invention described above has several technical advantages in achieving the following (but is not limited to): A process for preparing de-entangled ultra-high molecular weight isotactic polypropylene characterized by low entanglement density, low bulk density, and a spherical morphology. • The entanglement-removing ultra-high molecular weight isotactic polypropylene has a low entanglement density and does not require post-treatment to reduce entanglement density.

[0052] The embodiments described above, as well as embodiments that do not limit the details of their various features and advantages, will be described below. Throughout this specification, the terms “to constitute,” “to constitute,” and their synonyms “to compose,” or “to make up,” include, but do not exclude, other elements, integers, or procedures or other elements, integers, or procedures described herein. The use of the expression "at least" or "at least one" suggests the use of one or more elements, components, or quantities, as they may be used in the embodiments of the invention to obtain one or more target substances or results.

[0053] The above-described specific embodiments sufficiently illustrate the general nature of embodiments of the present invention; by applying the existing knowledge, others can modify and / or adapt the above-described specific embodiments for different uses without deviating from the above-described general concept. Accordingly, such adaptations and modifications should and are intended to be understood in the sense and scope of being equivalent to embodiments of the present invention. The usage of phrases and terms used herein is for illustrative purposes only and not for limitation. Accordingly, the embodiments described herein are based on the preferred embodiments, and it is recognized that the embodiments described herein can be practiced even if modified in the intent and scope of the embodiments described herein. Furthermore, it is necessary to be clearly understood that the above-described description should be interpreted only as a disclosure and not as limiting thereto.

[0054] The principles of the present invention will be explained and illustrated with reference to embodiments already described, so that it can be recognized that the described embodiments can be modified in terms of arrangement and details without deviating from the principles of the present invention. While we have emphasized the different components and parts of the preferred embodiments, many embodiments are possible, and many modifications can be made to the preferred embodiments without deviating from the principles of the invention. It will be obvious to those with expertise in the art that the characteristics of the present invention, the preferred embodiments, and other embodiments can be modified, and it is important to understand that the above explanatory matters are merely for the purpose of illustrating the present invention and should not be interpreted as limiting.

Claims

1. A process for preparing decontamination-free ultra-high molecular weight isotactic polypropylene having a mass-average molecular weight of 500,000 g / mol to 4,000,000 g / mol, wherein the process comprises the following steps: a) A mixture obtained by adding at least one scavenging agent to a reactor containing at least one hydrocarbon solvent, maintained in an inert atmosphere, under first predetermined conditions: temperature range 10°C to 70°C, stirring speed 150 rpm to 350 rpm, and time range 0 to 30 minutes, and stirring is performed to obtain the first solution. b) Propylene gas at a pressure range of 1 bar to 3 bar is introduced into the reactor, and a second solution is obtained by maintaining second predetermined conditions in which the temperature range is 10°C to 70°C and the stirring speed is in the range of 650 rpm to 850 rpm. c) A predetermined amount of pre-activated catalyst group is added to the second solution. Here, the pre-activated catalyst group is formed by reacting the catalyst of structural formula 1 with an activator to obtain the pre-activated catalyst group. 【Chemistry 1】 Here, R 1 , R 2 , R 3 : is isopropyl d) Maintain the reactor under third predetermined conditions, where the temperature range is 10°C to 70°C, the stirring speed range is 650 rpm to 850 rpm, and the time range is 1 hour to 3 hours, to obtain a third solution containing coarsely entangled ultra-high molecular weight isotactic polypropylene. e) Cool the third solution in the reactor to obtain a cooled third solution containing the precipitate of the coarsely de-entangled ultra-high molecular weight isotactic polypropylene. f) Obtain the cooled third solution containing the precipitate from the reactor, filter the cooled third solution to obtain a residue of wet-type coarse-de-entangled ultra-high molecular weight isotactic polypropylene, g) Wash and dry the residue of the wet-processed, coarsely de-entangled ultra-high molecular weight isotactic polypropylene to obtain the de-entangled ultra-high molecular weight isotactic polypropylene. The aforementioned activators are selected from at least one of N,N'-dimethylanilinium tetrakis(pentafluorophenyl) borate, trityltetrakis(pentafluorophenyl) borate, tris(allyl-substituted) borane, and their derivatives.

2. The process claimed in claim 1, wherein the ratio range of the catalyst to the activator is 1:1 to 1:

10.

3. The process claimed in claim 1, wherein the ratio of the catalyst to the activator is 1:

1.

4. A process as claimed in claim 1, wherein the erasing agent is at least one erasing agent selected from the group consisting of methylalmoxane (MAO) and triisobutylaluminum (TiBA).

5. A process as claimed in claim 1, wherein the ratio of the catalyst to the activator reacted to form a pre-activated catalyst group is in the range of 1:100 to 1:

50.

6. A process as claimed in claim 1, wherein the ratio of the catalyst to the activator reacted to form a pre-activated catalyst group is in the range of 1:

70.

7. The process claimed in claim 1, wherein the hydrocarbon solvent is at least one selected from toluene and heptane.

8. The process claimed in claim 1, wherein the process comprises the following steps: a) A mixture obtained by adding at least one elimination agent to a reactor containing at least one hydrocarbon solvent, maintained in an inert atmosphere, is mixed and stirred at a temperature of 40°C and a stirring speed of 250 rpm for 20 minutes to obtain the first solution. b) Propylene gas is introduced into the reactor at 1.1 bar, and the mixture is stirred at a rotation speed of 750 rpm while maintaining the temperature at 40°C to obtain the second solution. c) A predetermined amount of pre-activated catalyst group is added to the second solution. Here, the pre-activated catalyst group is formed by reacting the catalyst of structural formula 1 with an activator to obtain the pre-activated catalyst group. 【Chemistry 2】 Here, R 1 , R 2 , R 3 : is isopropyl d) Maintain the reactor at 40°C for 1 to 3 hours at a stirring speed of 750 rpm to obtain a third solution containing coarsely entangled ultra-high molecular weight isotactic polypropylene. e) Cool the third solution in the reactor to obtain a cooled third solution containing the precipitate of the coarsely de-entangled ultra-high molecular weight isotactic polypropylene. f) Obtain the cooled third solution containing the precipitate from the reactor, filter the cooled third solution to obtain a residue of wet-type coarse-de-entangled ultra-high molecular weight isotactic polypropylene, g) The wet-processed, coarsely de-entangled ultra-high molecular weight isotactic polypropylene is washed and dried to obtain the de-entangled ultra-high molecular weight isotactic polypropylene.

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