Fluorine-free polymer processing aid and use thereof

Abstract

The present application provides a fluorine-free polymer processing aid and a use thereof. The fluorine-free polymer processing aid comprises a polyurethane-based polymer and a synergist. The synergist comprises any one of or a combination of at least two of polyethylene glycol, polypropylene glycol, polycaprolactone, and poly(butylene adipate-co-terephthalate). The fluorine-free polymer processing aid provided by the present application comprises a polyurethane-based polymer and a synergist. The combined action of the polyurethane-based polymer and the synergist can effectively reduce melt fracture and mold accumulation, improve the flow stability of a polyolefin melt, ensure a smooth surface of an extruded product, and is suitable for a variety of processing environments. The processing aid has not only excellent processing performance, but also relatively low production costs and good environmentally friendly characteristics, and provides an efficient and sustainable solution for the polyolefin processing industry.

Description

A fluoropolymer processing aid and its application Technical Field

[0001] This application belongs to the field of polyolefin processing technology and relates to a fluorine-free polymer processing aid and its application. Background Technology

[0002] In the polyolefin processing industry, the stability of melt extrusion is crucial for the quality of the final product and production efficiency. However, under high shear rate conditions, polyolefin melts often experience problems such as melt fracture, surface defects, and die buildup, affecting the appearance and mechanical properties of the product. To address these issues, traditional industries widely use fluoropolymer processing aids (PPAs), such as polytetrafluoroethylene (PTFE) and its copolymers. These materials exhibit excellent performance in reducing melt rheological resistance and melt fracture. However, fluoropolymer processing aids are subject to strict environmental regulations because they may contain persistent organic pollutants such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).

[0003] Currently, the industry has made some progress in the research of processing aids for fluoropolymers and has proposed several alternatives. For example, companies such as Novartis (Switzerland) and ExxonMobil have developed a series of processing aids based on polyethylene glycol and polyalkylene glycols. These substances can play a certain role in lubrication and dispersion in the melt, helping to reduce melt fracture. However, low molecular weight polyethylene glycols tend to migrate to the surface of the product, affecting its stability, while high molecular weight polyethylene glycols, although effective in some systems, have poor compatibility with polyolefins. In addition, Novartis's poly(ether-block-amide) copolymer (PEBA) processing aid has also shown the ability to reduce melt defects. However, its synthesis process is relatively complex and costly. Other studies use surfactants, such as polysorbate esters. These aids can improve the flowability of polymers under certain conditions, but their heat resistance is low, and prolonged processing may lead to degradation, affecting the quality of the final product.

[0004] With increasingly stringent global environmental regulations and growing demand for high-performance processing aids, developing a fluoropolymer processing aid that can effectively improve melt rheological properties while meeting environmental requirements has become a pressing challenge for the industry. An ideal fluoropolymer processing aid should possess good melt lubricity, reduce extrusion pressure, and minimize surface defects, while avoiding impacting the inherent properties of the final product (such as melting point, thermal decomposition temperature, and rheological properties). Furthermore, its preparation process should be industrially feasible and cost-effective to ensure its widespread application in various polyolefin processing procedures. Summary of the Invention

[0005] In view of the shortcomings of existing technologies (including the high migration and stability problems of polyethylene glycol additives, the high cost and complex process of block copolymer additives, and the insufficient heat resistance of surfactant additives), the purpose of this application is to provide an improved fluoropolymer processing aid and its application.

[0006] The following technical solution is adopted in this application:

[0007] In a first aspect, this application provides a fluoropolymer processing aid, which includes a polyurethane-based polymer and a synergist.

[0008] The synergist includes any one or a combination of at least two of polyethylene glycol, polypropylene glycol, polycaprolactone, and poly(butylene adipate-co-terephthalate), PBAT.

[0009] The fluoropolymer processing aid provided in this application comprises a polyurethane-based polymer and a synergist. Working together, they effectively reduce melt fracture and die buildup, improve the flow stability of polyolefin melts, ensure a smooth surface of extruded products, and are suitable for various processing environments. This processing aid not only possesses excellent processing performance but also low production costs and good environmental characteristics, providing an efficient and sustainable solution for the polyolefin processing industry. Furthermore, the addition of this fluoropolymer processing aid does not affect the inherent properties of the base polymer (such as melting point, thermal decomposition temperature, rheological properties, etc.) as well as its transparency, mechanical properties, and stability.

[0010] In one specific implementation, the polyurethane-based polymer is a thermoplastic polyurethane elastomer (TPU).

[0011] Thermoplastic polyurethane elastomers are linear block copolymers composed of soft segments (such as oligomeric polyols) and hard segments (such as diisocyanates).

[0012] In one specific embodiment, the polyurethane-based polymer comprises soft segments and hard segments.

[0013] In one specific embodiment, the soft segment comprises any one or a combination of at least two of polytetrahydrofuran, polyethylene glycol, polypropylene glycol, and polycaprolactone.

[0014] In one specific embodiment, the hard segment comprises any one or a combination of at least two of diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), and toluene diisocyanate (TDI).

[0015] In one specific embodiment, the soft segments in the polyurethane-based polymer account for 10 wt.%-90 wt.% of the polyurethane-based polymer, for example, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, 75 wt.%, 80 wt.%, 85 wt.%, 90 wt.%, etc., and the hard segments in the polyurethane-based polymer account for 10 wt.%-90 wt.% of the polyurethane-based polymer, for example, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, 75 wt.%, 80 wt.%, 85 wt.%, 90 wt.%, etc. The soft-to-hard segment ratio can be adjusted according to application requirements to optimize the performance of the processing aid, including shear stability, lubrication, and interfacial migration effects.

[0016] In this application, the polyurethane-based polymer can be purchased commercially or prepared using existing methods. The raw materials used in preparing the polyurethane-based polymer may include chain extenders.

[0017] In one specific embodiment, the chain extender includes any one or a combination of at least two of the following: 1,4-butanediol, 1,6-hexanediol, 1,3-propanediol, ethylene glycol, bisphenol A, ethylenediamine, etc.

[0018] In one specific embodiment, the polyurethane-based polymer includes, but is not limited to, the following commercially available polymers: Elastollan 1085A, Elastollan 1154D, Elastollan 1160D, Elastollan 1174D, Elastollan 1175A, Elastollan 1185A, Elastollan 1190A, Elastollan 1195A, Elastollan 560D, Elastollan 564D, Elastollan 590A, Elastollan 598A, Elastollan 664, Elastollan 670, Elastollan 685, Elastollan 685A, Elastollan 690A, Elastollan 695A, Elastollan 880AN, Elastollan 890AN, Elastollan B60A, Elastollan B60D, Elastollan B64D, Elastollan B80A, Elastollan B85A, Elastollan B90A, Elastollan B95A, Elastollan C65A, Elastollan C70A, Elastollan C75A, Elastollan 85A, Elastollan C88A, Elastollan C98A, Elastollan C60D, Elastollan C64D, Elastollan C78A, Elastollan C80A, Elastollan C85A, Elastollan C90A, Elastollan C95A, Elastollan S50A, Elastollan S60A, Elastollan S60D, Elastollan S70A, Elastollan S80A, Elastollan S85A, Elastollan S90A, Elastollan S95A, Elastostat 15-01, Elastostat 10-02, Elastostat 10-01, Estonia 2102-55D, Estane 2102-75A, Estane 2103-55D, Estane 2103-65D, Estane 2103-70A, Estane 2103-90A, Estane 2355-75A, Estane 54600, Estonia 54610, Estonia 54640, Estonia 58070, Estonia 58123, Estonia 58130, Estonia 58133, Estonia 58137, Estonia 58142, Estonia 58202, Estonia 58206, Estonia 58211, Estonia 58212, Estonia 58213, Estonia 58215, Wanthane WHT-1164IC, Wanthane WHT-1172IC, Wanthane WHT-1180, Wanthane WHT-1180D, Wanthane WHT-1185EC, Wanthane WHT-1185F, Wanthane WHT-1190, Wanthane WHT-1190B, Wanthane WHT-1195, Wanthane WHT-1198IC, Wanthane WHT-1398, Wanthane WHT-1485RV, Wanthane WHT-1495EC, Wanthane WHT-1570IC, Wanthane WHT-1580, Wanthane WHT-1585, Wanthane WHT-1590, Wanthane WHT-1685AB, Wanthane WHT-1690AB, Wanthane WHT-4185T, Wanthane WHT-50965, Wanthane WHT-50975, Wanthane WHT-6232, Wanthane WHT-6236, Wanthane WHT-6420, Wanthane WHT-M870, Wanthane WHT-M880, Wanthane WHT-M885, Wanthane WHT-M890 and its mixture.

[0019] In one specific embodiment, the number-average molecular weight (Mn) of the polyethylene glycol is 1000-100000 g / mol, for example 1000 g / mol, 2000 g / mol, 3000 g / mol, 4000 g / mol, 5000 g / mol, 6000 g / mol, 7000 g / mol, 8000 g / mol, 9000 g / mol, 10000 g / mol, 11000 g / mol, 12000 g / mol, 13000 g / mol, 14000 g / mol, 15000 g / mol, 16000 g / mol, 17000 g / mol, 18000 g / mol, 19000 g / mol, 20000 g / mol, 30000 g / mol, 40000 g / mol, 50000 g / mol, 60000 g / mol, 70000 g / mol. The concentrations of g / mol, 80000 g / mol, 90000 g / mol, and 100000 g / mol were adjusted to optimize its compatibility and lubrication properties in the polyolefin matrix and improve the melt rheological stability.

[0020] In one specific embodiment, the fluoropolymer processing aid includes polyurethane-based polymers and polyethylene glycol.

[0021] In one specific embodiment, the mass ratio of the polyurethane-based polymer to polyethylene glycol is 1:(0.005-200), wherein 0.005-200 can be, for example, 0.005, 0.008, 0.01, 0.03, 0.05, 0.07, 0.08, 0.1, 0.2, 0.3, 0.5, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, etc., preferably 1:(0.05-20), more preferably 1:(0.1-10), and even more preferably 1:(0.25-4).

[0022] In a second aspect, this application provides a thermoplastic composition comprising a polyolefin and a fluoropolymer processing aid;

[0023] The fluoropolymer processing aids include those described in the first aspect.

[0024] In one specific embodiment, the fluoropolymer processing aid includes polyurethane-based polymers and polyethylene glycol.

[0025] In one specific embodiment, based on the weight of the polyolefin, the amount of polyurethane-based polymer in the fluoropolymer processing aid is 100-4000 ppm, for example, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1200 ppm, 1400 ppm, 1600 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2600 ppm, 2800 ppm, 3000 ppm, 3200 ppm, 3400 ppm, 3600 ppm, 3800 ppm, 4000 ppm, etc., and the amount of polyethylene glycol is 100-4000 ppm, for example, 100 ppm, 200 ppm, 300 ppm, etc. ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1200 ppm, 1400 ppm, 1600 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2600 ppm, 2800 ppm, 3000 ppm, 3200 ppm, 3400 ppm, 3600 ppm, 3800 ppm, 4000 ppm, etc. When the amount of fluoropolymer processing aid added is within this range, it can ensure its uniform dispersion in the polyolefin matrix and improve processing stability.

[0026] In one specific embodiment, based on 100% by weight of the polyolefin, the amount of polyurethane-based polymer and polyethylene glycol in the fluoropolymer processing aid is 200-2000 ppm.

[0027] In one specific implementation, the polyolefin includes polyethylene and / or polypropylene.

[0028] In one specific embodiment, the polyethylene includes linear low-density polyethylene (LLDPE, such as ExxonMobil). TM 1001.32, etc.), any one or a combination of at least two of low-density polyethylene and high-density polyethylene.

[0029] The thermoplastic composition provided in this application is suitable for high-shear extrusion processing, capable of processing at shear rates of 300 s⁻¹. -1 It reduces or eliminates melt fracture under higher extrusion conditions, thereby improving the surface quality of polyolefin extruded products and providing excellent processing stability without relying on fluoropolymers.

[0030] Thirdly, this application provides a method for preparing the thermoplastic composition as described in the second aspect, the method comprising the following steps:

[0031] The thermoplastic composition is obtained by physically mixing polyolefin and fluorine-free polymer processing aids, followed by melt blending and granulation.

[0032] In one specific implementation, prior to physical mixing, the following steps are included: drying the polyolefin and the fluoropolymer processing aid separately to remove trace amounts of moisture from the materials and prevent decomposition or uneven distribution during melt blending.

[0033] In one specific implementation, the drying temperature is 50-70℃, such as 50℃, 55℃, 60℃, 65℃, 70℃, etc., and the drying time is 10-15 hours, such as 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, etc.

[0034] In one specific implementation, the drying method includes vacuum drying.

[0035] In one specific embodiment, the melt blending is carried out in a twin-screw extruder.

[0036] In one specific implementation, the twin-screw extruder operates at a speed of 100-200 rpm, such as 100 rpm, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm, 200 rpm, etc., to ensure good mixing results.

[0037] In one specific embodiment, the physical mixing of polyolefin and fluoropolymer processing aid, followed by melt blending, specifically includes: first, preparing a masterbatch with a fluoropolymer processing aid content of 5-15 wt.% (e.g., 5 wt.%, 5.5 wt.%, 6 wt.%, 6.5 wt.%, 7 wt.%, 7.5 wt.%, 8 wt.%, 8.5 wt.%, 9 wt.%, 9.5 wt.%, 10 wt.%, 10.5 wt.%, 11 wt.%, 11.5 wt.%, 12 wt.%, 12.5 wt.%, 13 wt.%, 13.5 wt.%, 14 wt.%, 14.5 wt.%, 15 wt.%, etc.); then, using a stepwise dilution method, further blending the masterbatch with the polyolefin to finally prepare a fluoropolymer processing aid content of 200-8000 ppm (e.g., 200 ppm, 400 ppm, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, etc.). Thermoplastic compositions of ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm, 6000 ppm, 6500 ppm, 7000 ppm, 7500 ppm, 8000 ppm, etc. (based on 100% by weight of polyolefin).

[0038] In one specific implementation, the granulation is carried out in a granulator.

[0039] In one specific embodiment, the particle size of the product obtained after granulation is 1-2 mm, such as 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.8 mm, 2 mm, etc.

[0040] This application employs a twin-screw extruder for melt fracture testing to systematically evaluate the performance of fluoropolymer processing aids at high shear rates (400 s⁻¹). -1 The study investigated the improvement effect of processing aids on polymer melt flow stability under certain conditions. Specifically, the prepared blended particles were subjected to melt extrusion tests in an extruder, and the melt flow behavior and surface quality of the extrudate were observed under high shear rate conditions. The experiment focused on the following parameters: 1. Melt fracture phenomenon: The presence of melt fracture, including "sharkskin" melt fracture, was assessed through visual observation and scanning electron microscopy, and the improvement in surface quality was recorded. 2. Melt fracture disappearance time: For different processing aid formulations, the time point at which the melt fracture phenomenon completely disappeared during processing was determined to quantitatively characterize the effectiveness of the processing aids.

[0041] The above tests were used to evaluate the effect of the fluorine-free polymer processing aid formulation of this application on improving polymer melt flow under high shear conditions, and to compare and analyze existing fluorine-containing and fluorine-free processing aid formulations. The fluorine-free processing aid formulation developed in this application can effectively improve the melt rheological stability of polyolefin materials, reduce or eliminate melt fracture, thereby improving the quality and efficiency of polymer processing.

[0042] This application achieves effective improvement in the melt flow properties of polyolefins (linear low-density polyethylene, low-density polyethylene, high-density polyethylene, etc.) by designing a formulation for a fluorinated polymer processing aid and a preparation process for the thermoplastic composition, thereby improving the processing stability of the polymer and the surface quality of the finished product. Compared with existing fluorinated polymer processing aids, this application uses a polyurethane-based polymer and a synergist (such as any one or a combination of at least two of polyethylene glycol (PEG), polypropylene glycol, polycaprolactone, and polybutylene terephthalate) as a composite processing aid. Combined with a twin-screw melt blending method, the aid forms a well-dispersed phase in the polyolefin matrix, improving the lubricity of the melt and the interfacial migration effect during processing, thereby achieving the technical effect of optimizing melt flow behavior and reducing or eliminating melt fracture.

[0043] Fourthly, this application provides the application of a fluoropolymer processing aid as described in the first aspect or a thermoplastic composition as described in the second aspect in film extrusion (e.g., blown film, cast film, etc.), pipe extrusion, cable sheathing, coating processes (e.g., thermoplastic coating, etc.), and other polyolefin processing processes.

[0044] Compared with the prior art, this application has the following advantages:

[0045] The fluoropolymer processing aid provided in this application includes a polyurethane-based polymer and a synergist. The two work together to effectively reduce melt fracture and die buildup, improve the flow stability of polyolefin melts, ensure a smooth surface of extruded products, and are suitable for various processing environments. This processing aid not only has excellent processing performance but also low production costs and good environmental characteristics, providing an efficient and sustainable solution for the polyolefin processing industry. Attached Figure Description

[0046] Figures 1-6 show the melt fracture test results of the thermoplastic composition provided in Example 1.

[0047] Figures 7-13 show the melt fracture test results of the thermoplastic composition provided in Example 2.

[0048] Figures 14-19 show the melt fracture test results of linear low-density polyethylene with fluorinated processing aids provided in Comparative Example 1.

[0049] Figure 20 shows the storage modulus test results of the thermoplastic compositions provided in Examples 1-2, the linear low-density polyethylene with fluorine processing aid provided in Comparative Example 1, and the linear low-density polyethylene provided in Comparative Example 2.

[0050] Figure 21 shows the loss modulus test results of the thermoplastic compositions provided in Examples 1 and 2, the linear low-density polyethylene with fluorine processing aid provided in Comparative Example 1, and the linear low-density polyethylene provided in Comparative Example 2. Detailed Implementation

[0051] The technical solution of this application will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of this application and should not be construed as specific limitations thereof.

[0052] Example 1

[0053] This embodiment provides a thermoplastic composition comprising a polyolefin and a fluoropolymer processing aid;

[0054] The polyolefin is linear low-density polyethylene, brand name ExxonMobil. TM 1001.32; The fluoropolymer processing aid is a polyurethane-based polymer (Elastollan). 1085A) and polyethylene glycol (Mn=2000); based on the weight of polyolefin as 100%, the amount of polyurethane-based polymer is 1000 ppm and the amount of polyethylene glycol is 1000 ppm.

[0055] The preparation method includes the following steps:

[0056] (1) The polyurethane-based polymer, polyethylene glycol and linear low-density polyethylene were vacuum dried at 60˚C for 12 hours.

[0057] (2) The components after vacuum drying in step (1) are physically mixed and then added to a twin-screw extruder for melt blending. The screw speed is set to 150 rpm to obtain a masterbatch with a fluorine-free polymer processing aid content of 10 wt.%. Then, the masterbatch is further blended with linear low-density polyethylene by stepwise dilution to finally prepare a blend containing 0.2 wt% processing aid. After blending, the melt is processed by a granulator to produce blended particles with a particle size of about 1.5 mm, that is, the thermoplastic composition is obtained.

[0058] Example 2

[0059] This embodiment provides a thermoplastic composition comprising a polyolefin and a fluoropolymer processing aid;

[0060] The polyolefin is linear low-density polyethylene, brand name ExxonMobil. TM 1001.32; The fluoropolymer processing aid is a polyurethane-based polymer (Elastollan). 1195A) and polyethylene glycol (Mn=2000); based on the weight of polyolefin as 100%, the amount of polyurethane-based polymer is 1000 ppm and the amount of polyethylene glycol is 1000 ppm.

[0061] The preparation method is the same as in Example 1.

[0062] Example 3

[0063] This embodiment provides a thermoplastic composition comprising a polyolefin and a fluoropolymer processing aid;

[0064] The polyolefin is linear low-density polyethylene, brand name ExxonMobil. TM 1001.32; The fluoropolymer processing aid is a polyurethane-based polymer (Elastollan). 1085A) and polyethylene glycol (Mn=2000); based on 100% by weight of polyolefin, the amount of polyurethane-based polymer is 500 ppm and the amount of polyethylene glycol is 500 ppm.

[0065] The preparation method is the same as in Example 1.

[0066] Example 4

[0067] This embodiment provides a thermoplastic composition comprising a polyolefin and a fluoropolymer processing aid;

[0068] The polyolefin is linear low-density polyethylene, brand name ExxonMobil. TM 1001.32; The fluoropolymer processing aid is a polyurethane-based polymer (Elastollan). 1195A) and polyethylene glycol (Mn=2000); based on 100% by weight of polyolefin, the amount of polyurethane-based polymer is 500 ppm and the amount of polyethylene glycol is 500 ppm.

[0069] The preparation method is the same as in Example 1.

[0070] Comparative Example 1

[0071] This comparative example provides an ExxonMobil product manufactured by ExxonMobil. TM 1001x26 Fluorine-containing processing aid grade linear low-density polyethylene (LLDPE).

[0072] Comparative Example 2

[0073] This comparative example provides a linear low-density polyethylene, designated ExxonMobil. TM 1001.32.

[0074] Comparative Example 3

[0075] The only difference between this comparative example and Example 1 is that the polyurethane-based polymer is replaced with an equal weight of polyethylene glycol, that is, the fluorine-free polymer processing aid consists only of polyethylene glycol, and its dosage is 2000 ppm.

[0076] Comparative Example 4

[0077] The only difference between this comparative example and Example 2 is that polyethylene glycol is replaced with an equal weight of polyurethane-based polymer. That is, the fluorine-free polymer processing aid consists only of polyurethane-based polymer, and its dosage is 2000 ppm.

[0078] Performance testing

[0079] This application employs a twin-screw extruder to conduct melt fracture tests on the thermoplastic compositions provided in the above-described embodiments and comparative examples to evaluate the improvement effect of different processing aid formulations on the melt flow behavior of polyolefins. During the experiment, the screw speed was set to 100 rpm, and the apparent shear rate of the extrusion die was maintained at 400 s⁻¹ by controlling the feed rate. The experimental time was recorded as 0 minutes when LLDPE with added polymer processing aids was introduced and a strip with sharkskin defects was extruded. Subsequently, extruded strips were collected every 5 minutes, and the melt fracture defects on the extrudate surface were continuously observed. The time when the melt fracture phenomenon began to disappear and the time when the melt fracture phenomenon was completely eliminated were recorded. When the extrudate surface became smooth and free of "sharkskin" defects, the melt fracture phenomenon was considered to be completely eliminated. To determine the effectiveness of the processing aid, if the melt fracture phenomenon was eliminated within 70 minutes, the processing aid was considered to have good processing modification performance; if the melt fracture phenomenon was eliminated within 90 minutes, the processing modification performance of the processing aid was considered to meet general requirements.

[0080] The melt fracture test results of the thermoplastic composition provided in Example 1 are shown in Figures 1-6. It can be seen that Example 1, at a shear rate of 400 s⁻¹, showed good melt fracture performance. -1 Under the extrusion conditions, the "sharkskin" melt fracture elimination phenomenon begins to appear within 20 to 30 minutes. That is, in Example 1, the "sharkskin" melt fracture elimination phenomenon begins to appear within about 25 minutes, and the "sharkskin" melt fracture phenomenon is completely eliminated within 50 to 60 minutes. In other words, Example 1 can almost completely eliminate the melt fracture phenomenon within about 60 minutes.

[0081] The melt fracture test results of the thermoplastic composition provided in Example 2 are shown in Figures 7-13. It can be seen that Example 2, at a shear rate of 400 s⁻¹, showed good melt fracture performance. -1 Under the extrusion conditions, the "sharkskin" melt fracture elimination phenomenon begins to appear within 30 minutes, and the "sharkskin" melt fracture phenomenon is completely eliminated within 60 to 70 minutes. That is, Example 2 can almost completely eliminate the melt fracture phenomenon within about 70 minutes.

[0082] The melt fracture test results of linear low-density polyethylene with fluorinated processing aid provided in Comparative Example 1 are shown in Figures 14-19. It can be seen that the fluorinated polymer processing aid does not perform well under high shear rate extrusion conditions. At high shear rates, the sample does not show any melt fracture elimination phenomenon.

[0083] Compared to Comparative Example 1, Examples 1-2 showed better performance in clearing melt fracture under high shear rate conditions. This indicates that the fluorine-free polymer processing system used in this application can effectively improve the melt flow behavior of polymers under high shear rate conditions, and outperforms the processing performance of traditional fluorinated processing aids (Comparative Example 1), exhibiting superior processing modification effects.

[0084] For LLDPE without added processing aids (Comparative Example 2), at shear rates exceeding 100 s⁻¹... -1 The "sharkskin" phenomenon begins to appear immediately, and it becomes more pronounced when the shear rate exceeds 500 s⁻¹. -1 At this time, surface defects are further aggravated, manifesting as severe melt fracture and even melt delamination. However, under the same processing conditions, the addition of 1000ppm TPU + 1000ppm PEG composite processing aid significantly suppressed melt fracture, and even at high shear rates (400 s⁻¹), the melt fracture phenomenon was significantly reduced. -1 It can still maintain a good surface smoothness of the melt under certain conditions.

[0085] The time when melt fracture began to disappear and the time when it was completely removed were summarized for the thermoplastic compositions provided in this embodiment and the comparative example. The stability of the extruded products was observed (if processing aids were observed to precipitate on the surface of the extruded products with the naked eye, they were considered "unstable"; otherwise, they were considered "stable"). At the same time, the yellowing of the extruded products was observed with the naked eye. The results are shown in Table 1 below.

[0086]

[0087] As can be seen from Table 1, compared with the comparative example, the fluoropolymer processing system used in the embodiments of this application can effectively improve the melt flow behavior of the polymer under high shear rate conditions.

[0088] For linear low-density polyethylene (exxonMobil) without processing aids TM The properties of the thermoplastic compositions provided in the embodiments of this application (1001.32) and the present application were tested using the following methods:

[0089] (1) The melting point of the material was determined by differential scanning calorimetry;

[0090] (2) Thermogravimetric analysis was used to test the thermal decomposition point of the material;

[0091] (3) The storage modulus and loss modulus of the material were tested using a rotational rheometer.

[0092] The test results for melting point and thermal decomposition point are shown in Table 2.

[0093]

[0094] The test results of the storage modulus and loss modulus of the thermoplastic compositions provided in Examples 1-2, the linear low-density polyethylene with fluorine processing aid provided in Comparative Example 1, and the linear low-density polyethylene provided in Comparative Example 2 are shown in Figures 20 and 21, respectively.

[0095] As can be seen from Table 2, Figure 20, and Figure 21, the addition of the fluorine-free polymer processing aid provided in this application does not affect the inherent properties of the base polymer. In summary, the technical solution of this application can significantly optimize the performance of the fluorine-free processing aid, enabling it to maintain polymer processing fluidity and reduce melt fracture without affecting the inherent properties of the base polymer, while also possessing advantages such as good environmental performance, low addition amount, and high processing stability. Therefore, this application provides a fluorine-free polymer processing aid formulation with greater industrial application value, which can be widely used in the processing of polyolefin materials such as LLDPE and HDPE, improving the overall quality and production efficiency of extruded products.

[0096] The applicant declares that this application illustrates the fluoropolymer processing aid and its application through the above embodiments, but this application is not limited to the above embodiments, that is, it does not mean that this application must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent substitutions of the raw materials selected in this application, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this application.

Claims

1. A fluoropolymer processing aid comprising a polyurethane-based polymer and a synergist; The synergist includes any one or a combination of at least two of polyethylene glycol, polypropylene glycol, polycaprolactone, and polybutadiene terephthalate.

2. The fluoropolymer processing aid according to claim 1, wherein, The polyurethane-based polymer comprises soft segments and hard segments; Preferably, the soft segment comprises any one or a combination of at least two of polytetrahydrofuran, polyethylene glycol, polypropylene glycol, and polycaprolactone; Preferably, the hard segment comprises any one or a combination of at least two of diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate; Preferably, the soft segments in the polyurethane-based polymer account for 10 wt.%-90 wt.% of the polyurethane-based polymer, and the hard segments in the polyurethane-based polymer account for 10 wt.%-90 wt.% of the polyurethane-based polymer.

3. The fluoropolymer processing aid according to claim 1 or 2, wherein, The number-average molecular weight of the polyethylene glycol is 1000-100000 g / mol.

4. The fluoropolymer processing aid according to any one of claims 1-3, wherein, The fluorine-free polymer processing aids include polyurethane-based polymers and polyethylene glycol; Preferably, the mass ratio of the polyurethane-based polymer to polyethylene glycol is 1:(0.005-200), more preferably 1:(0.05-20), further preferably 1:(0.1-10), and even more preferably 1:(0.25-4).

5. A thermoplastic composition comprising a polyolefin and a fluoropolymer processing aid as described in any one of claims 1-4.

6. The thermoplastic composition according to claim 5, wherein, The fluorine-free polymer processing aids include polyurethane-based polymers and polyethylene glycol; Preferably, based on the weight of the polyolefin, the amount of polyurethane-based polymer in the fluoropolymer processing aid is 100-4000 ppm, and the amount of polyethylene glycol is 100-4000 ppm. Preferably, based on the weight of the polyolefin, the amount of polyurethane-based polymer and the amount of polyethylene glycol in the fluoropolymer processing aid are 200-2000 ppm.

7. The thermoplastic composition according to claim 5 or 6, wherein, The polyolefin includes polyethylene and / or polypropylene; Preferably, the polyethylene includes any one or a combination of at least two of linear low-density polyethylene, low-density polyethylene, and high-density polyethylene.

8. A method for preparing a thermoplastic composition according to any one of claims 5-7, comprising the following steps: The thermoplastic composition is obtained by physically mixing polyolefin and fluorine-free polymer processing aids, followed by melt blending and granulation.

9. The preparation method according to claim 8, wherein, Before physical mixing, the following steps are also included: drying the polyolefin and the fluoropolymer processing aid separately; Preferably, the drying temperature is 50-70°C and the drying time is 10-15 hours; Preferably, the drying method includes vacuum drying; Preferably, the melt blending is carried out in a twin-screw extruder; Preferably, the twin-screw extruder rotates at a speed of 100-200 rpm; Preferably, the physical mixing of polyolefin and fluoropolymer processing aid followed by melt blending specifically includes: first preparing a masterbatch with a fluoropolymer processing aid content of 5-15 wt.%, then further blending the masterbatch with polyolefin using a stepwise dilution method, and finally preparing a thermoplastic composition with a fluoropolymer processing aid content of 200-8000 ppm.

10. The use of a fluoropolymer processing aid as described in any one of claims 1-4 or a thermoplastic composition as described in any one of claims 5-7 in film extrusion, pipe extrusion, cable sheathing, coating processes, and other polyolefin processing processes.

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