A polyethylene material, a method for producing the same, and a polyethylene product

Abstract

The application relates to the technical field of general polymer material modification, in particular to a polyethylene material, a preparation method thereof and a polyethylene product, which comprises the following raw materials in mass fractions: first polyethylene, 70-85 parts; second polyethylene, 5-15 parts; third polyethylene, 5-10 parts; silicone auxiliary agent, 1-5 parts; coupling agent, 1-5 parts, wherein the first polyethylene has a weight average molecular weight of 240,000-350,000 g / mol, a butene comonomer content of 1-4%, and a melt flow rate of 0.2-0.5 g / 10 min; the second polyethylene has a weight average molecular weight of 600,000-3,000,000 g / mol, wherein the weight average molecular weight of 1,000,000 and above accounts for 25-50%, and a molecular weight distribution index of 30-300; and the third polyethylene has a weight average molecular weight of 5,000-50,000 g / mol; through the collocation of the above components, the polyethylene material not only has high anti-sagging performance, but also has excellent processing fluidity, which meets the actual production requirements of large-diameter pipe materials in the pipe material industry.

Description

Technical Field

[0001] This application relates to the field of general polymer material modification technology, specifically to a polyethylene material, its preparation method, and polyethylene products. Background Technology

[0002] Polyethylene (PE) pipes possess excellent chemical corrosion resistance, good toughness, and non-polluting properties, making them widely used in urban water supply and drainage pipes, gas pipes, and other fields. Furthermore, PE pipes are increasingly used in marine engineering, chemical and pharmaceutical industries, and mining, with applications such as marine aquaculture cages and floating recreational platforms gaining market favor. As the application scope of PE pipes continues to expand, the demand for large-diameter PE pipes is gradually increasing, leading to growing research attention on materials used in large-diameter PE pipes.

[0003] In addition to meeting the basic physical properties of conventional polyethylene materials, materials used for large-diameter PE pipes must also meet the anti-sagging characteristics required for large-diameter pipe production. Currently, there are three main categories of methods for preparing anti-sagging high-density polyethylene (HDPE): reaction synthesis, chemical cross-linking, and the addition of ultra-high molecular weight polyethylene (UHMWPE). Reaction synthesis is limited by catalysts and reaction processes, and its effect on improving HDPE's anti-sagging performance is usually limited. Chemical cross-linking can significantly improve HDPE's anti-sagging properties, but the cross-linked network structure of the HDPE restricts its processing and recycling. The method of adding UHMWPE is usually limited by the difficult processing of UHMWPE, making it impossible to achieve an effective balance between good processing performance and high anti-sagging performance.

[0004] Ordinary HDPE has poor anti-sagging properties, which limits its application in large-diameter pipes and large-capacity containers. Ultra-high molecular weight polyethylene (UHMWPE), on the other hand, has exceptionally long molecular chains with numerous physical entanglement points that act as "crosslinking points," significantly improving the anti-sagging properties of ordinary HDPE pipes. However, this severe molecular chain entanglement also results in extremely poor processability. Therefore, technological innovation is needed to address the challenge of simultaneously achieving good processability and anti-sagging properties when blending UHMWPE with ordinary HDPE. Summary of the Invention

[0005] Therefore, the technical problem to be solved by this application is to overcome the problem that the processing performance and anti-sagging performance cannot be simultaneously achieved when ultra-high molecular weight polyethylene is blended with ordinary HDPE in the prior art.

[0006] This application provides a polyethylene material comprising the following parts by weight of raw materials:

[0007] First polyethylene, 70-85 parts; the weight-average molecular weight of the first polyethylene is 240,000-350,000 g / mol, the butene comonomer content is 1%-4%; the melt flow rate is 0.2-0.5 g / 10 min;

[0008] The second polyethylene, 5-15 parts; the weight-average molecular weight of the second polyethylene is 600,000-3,000,000 g / mol, of which the weight-average molecular weight of 1,000,000 and above accounts for 25%-50%, and the molecular weight distribution index is 30-300.

[0009] Third polyethylene, 5-10 parts; the weight-average molecular weight of the third polyethylene is 5000 g / mol-50000 g / mol, and the molecular weight distribution index is 3-15;

[0010] Silicone additive, 1-5 parts;

[0011] Coupling agent, 1-5 parts.

[0012] In some preferred embodiments, the first polyethylene has a weight-average molecular weight of 300,000-350,000 g / mol, a butene comonomer content of 1.5%-2.5%, and a melt flow rate of 0.2-0.3 g / 10 min.

[0013] The first polyethylene, second polyethylene, third polyethylene, and coupling agent in this application can all be synthesized using conventional methods or are commercially available. The first polyethylene can be, for example, polyethylene with grades WH23050 and WH4731B provided by Wanhua Chemical Group Co., Ltd. Polyethylene with grade WH23050 is preferred.

[0014] The polyethylene with grade WH23050 has a weight-average molecular weight of 310,000 g / mol, a butene comonomer content of 1.5%, and a density of 0.950 g / cm³. 3 The melt flow rate is 0.24 g / 10 min, the melt flow ratio is 27, the melt strength is 236 mN, and the zero shear viscosity is 331794 Pa·s.

[0015] The polyethylene with grade WH4731B has a weight-average molecular weight of 240,000 g / mol, a butene comonomer content of 2%, and a density of 0.947 g / cm³. 3 The melt flow rate is 0.47 g / 10 min, the melt flow ratio is 20, the melt strength is 182 mN, and the zero shear viscosity is 331794 Pa·s.

[0016] The weight-average molecular weight of polyethylene was determined by GPC testing. The first polyethylene in this application is a copolymer of ethylene and 1-butene, and the butene comonomer content refers to the mass percentage of the butene comonomer in the first polyethylene. This was determined using online gel permeation chromatography-infrared spectroscopy (GPC-IR).

[0017] The density of polyethylene is tested according to the density gradient column method in accordance with the GB / T 1033.2-2010 standard.

[0018] The term melt mass flow rate (MFR), also known as melt index (MI), is the number of grams of molten resin that flow through a standard capillary tube within a certain time (typically 10 minutes) under specific temperature and load conditions in a standardized melt flow rate meter. The unit is g / 10min. Melt flow rate is measured according to ISO 1133 and GB / T 3682 using a melt flow rate meter at 190°C and a 5kg load. The melt flow ratio is obtained by dividing the melt flow rate at 190°C and a 21.6kg load by the melt flow rate at 190°C and a 5kg load. Melt strength is tested according to ISO 16790 using a Rheotens melt strength meter.

[0019] Zero-shear viscosity was measured using a rotational rheometer according to the ATM D4440 standard. Measurements were taken at 200°C with a strain of 1% and a range of 628 to 0.0628 rad / s using the rotational rheometer, and the zero-shear viscosity was calculated using the Carreau-Yasuda model.

[0020] The second polyethylene can be, for example, polyethylene with grades 4112 and 4122 provided by Celanese Corporation of the United States, polyethylene with grade 145M provided by Mitsui Chemicals of Japan, and polyethylene with grades MII-2, L1004F, and X3004F provided by Yanshan Petrochemical Company. Polyethylene with grades 4112 provided by Celanese Corporation of the United States and MII-2 provided by Yanshan Petrochemical Company are preferred.

[0021] The polyethylene with grade 4112 has a weight-average molecular weight of 920,000 g / mol, of which 27% has a weight-average molecular weight of 1 million or more, and a molecular weight distribution index of 43.

[0022] The polyethylene with grade 4122 has a weight-average molecular weight of 1.94 million g / mol, of which 46% has a weight-average molecular weight of 1 million or more, and a molecular weight distribution index of 222.

[0023] The weight-average molecular weight of polyethylene with grade 145M is 910,000 g / mol, of which 26% have a weight-average molecular weight of 1 million or more, and the molecular weight distribution index is 35.

[0024] The weight-average molecular weight of polyethylene with the grade MII-2 is 1.88 million g / mol, of which 50% have a weight-average molecular weight of 1 million or more, and the molecular weight distribution index is 82.

[0025] The weight-average molecular weight of polyethylene with the grade L1004F is 1.06 million g / mol, of which 31% have a weight-average molecular weight of 1 million or more and a molecular weight distribution index of 59.

[0026] The weight-average molecular weight of polyethylene with the grade X3004F is 1.94 million g / mol, of which 49% have a weight-average molecular weight of 1 million or more, and the molecular weight distribution index is 176.

[0027] In this application, the weight-average molecular weight and molecular weight distribution index of polyethylene are both tested by GPC. The molecular weight distribution index = weight-average molecular weight / number-average molecular weight.

[0028] The percentage of individuals with a weight-average molecular weight of 1 million or higher was obtained through GPC testing and data grading.

[0029] The third type of polyethylene can be, for example, polyethylene wax A-C6A from Honeywell or Licowax PE 190 from Clariant. The preferred grade is Licowax PE 190 from Clariant.

[0030] The weight-average molecular weight of polyethylene wax A-C6A is 6700 g / mol, and the molecular weight distribution index is 13.1.

[0031] Licowax PE 190 has a weight-average molecular weight of 22,600 g / mol and a molecular weight distribution index of 3.9.

[0032] In some preferred embodiments, the density of the first polyethylene is 0.9–1.0 g / cm³. 3 The melt flow ratio is 20–30, the melt strength is 180–220 mN, and the zero-shear viscosity is 200,000–500,000 Pa·s; preferably, the density of the first polyethylene is 0.94–0.96 g / cm³. 3 The melt flow ratio is 25–30; the melt strength is 200–220 mN; and the zero-shear viscosity is 300,000–500,000 Pa·s.

[0033] In some preferred embodiments, the weight-average molecular weight of the second polyethylene is 900,000 to 1,200,000 g / mol, of which 25% to 35% have a weight-average molecular weight of 1,000,000 or more, and the molecular weight distribution index is 40 to 50.

[0034] In some preferred embodiments, the silicone additive comprises one or more of SILIMER 9100, SILIMER 9200, SILIMER 9300, and SILIMER 5090. These silicone additives are available from Chengdu Silike Technology Co., Ltd. The weight-average molecular weight of these silicone additives is 100,000 g / mol to 200,000 g / mol. These silicone additives have long-chain saturated alkyl groups.

[0035] In some preferred embodiments, the coupling agent has the molecular formula: Wherein R1 is selected from C1-C10 alkyl groups, R2 and R3 are independently selected from C1-C10 alkyl groups or C1-C10 alkoxy groups, and R4 is selected from C5-C25 alkyl groups or C5-C10 cycloalkyl groups; preferably, the coupling agent includes one or more of octyltrimethoxysilane, cyclohexylmethyldimethoxysilane, dodecyltrimethoxysilane, dodecylmethyldimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane, more preferably including one or more of hexadecyltrimethoxysilane and octadecyltrimethoxysilane.

[0036] In some preferred embodiments, the raw materials of the polyethylene material further include 0.05-2 parts by weight of antioxidant and / or 0.05-0.15 parts by weight of deacidifying agent.

[0037] In some preferred embodiments, the antioxidant includes one or more of antioxidant 1076, antioxidant 168, and antioxidant 1010; and / or, the acid remover includes one or more of zinc stearate and calcium stearate.

[0038] This application also provides a method for preparing any of the above-mentioned polyethylene materials, wherein the raw materials for polyethylene materials are mixed, melt-extruded, and polyethylene materials are obtained.

[0039] In some preferred embodiments, the melt extrusion temperature is 180-230°C and the rotation speed is 180-240 r / min.

[0040] In some preferred embodiments, the mixing step first involves mixing all raw materials except for the first and third polyethylene to obtain mixture A. Then, mixture A is mixed with the first and third polyethylene at 50-60°C to obtain mixture B. The second polyethylene has a high molecular weight, is prone to thermal oxidative fracture, and is difficult to process. Therefore, it is preferentially mixed with coupling agents and silicone additives to maintain its chemical stability and improve its dispersibility and processing performance.

[0041] In some preferred embodiments, the preparation method includes the following steps:

[0042] (1) The second polyethylene, the silicone additive, the coupling agent, the antioxidant and the deacidifying agent are placed in a high-speed mixer and stirred for 10-25 minutes to obtain mixture A;

[0043] (2) Heat the mixture A to 50-60°C, then add the first polyethylene and the third polyethylene, and continue stirring and mixing for 10-25 minutes to obtain mixture B;

[0044] (3) The mixture B is added to a twin-screw extruder for melt blending, extrusion, cooling and granulation. The blending and extrusion temperature of the twin-screw extruder is 180-230℃ and the screw speed is 180-240r / min.

[0045] This application also provides a polyethylene article made from any of the polyethylene materials described above or polyethylene materials prepared by the above preparation methods; optionally, the polyethylene article is a polyethylene pipe.

[0046] The technical solution of this application has the following advantages:

[0047] 1. The polyethylene material provided in this application comprises the following raw materials in parts by weight: first polyethylene, 70-85 parts; second polyethylene, 5-15 parts; third polyethylene, 5-10 parts; silicone additive, 1-5 parts; coupling agent, 1-5 parts, wherein the first polyethylene has a weight-average molecular weight of 240,000-350,000 g / mol, and a butene comonomer content of 1%-4%; the melt flow rate is 0.2-0.5 g / 10 min; the second polyethylene has a weight-average molecular weight of 600,000-3,000,000 g / mol, wherein a weight-average molecular weight of 1,000,000 or higher accounts for 25%-50%. The molecular weight distribution index is 30-300; the weight average molecular weight of the third polyethylene is 5000g / mol-50000g / mol, and the molecular weight distribution index is 3-15; through the synergistic effect of the first polyethylene with specific molecular weight, butene comonomer content and melt flow rate, the second polyethylene with specific molecular weight and proportion and specific molecular weight distribution index, the third polyethylene with specific molecular weight and molecular weight distribution index and silicone additives in a specific ratio, the problem of difficult processing caused by the improvement of the anti-sagging performance of polyethylene materials is avoided, and the balance between high anti-sagging performance and good processing performance is achieved. The second polyethylene, with its specific molecular weight, proportion, and molecular weight distribution index, acts as a physical cross-linking point due to its abundant molecular chain entanglement points, forming an effective network structure that greatly improves the anti-sagging performance of the first polyethylene. The lower molecular weight third polyethylene acts as a common lubricant, facilitating the expansion of the first and second polyethylenes, preventing excessive molecular chain entanglement, and improving the fluidity of the mixture. Due to the low coefficient of friction of silicone molecules, when the silicone additive is uniformly dispersed in the resin matrix, the third polyethylene exhibits a synergistic effect, increasing the melt flow rate of the resin matrix and effectively improving the processing fluidity of the system. Through the combined use of these components, this polyethylene material not only possesses high anti-sagging performance but also excellent processing fluidity, meeting the actual production needs of large-diameter pipes in the pipe industry.

[0048] 2. The polyethylene material provided in this application, by limiting the weight average molecular weight of the first polyethylene to 300,000-350,000 g / mol, the butene comonomer content to 1.5%-2.5%, and the melt flow rate to 0.2-0.3 g / 10 min, can provide more balanced processing fluidity and anti-sagging properties.

[0049] 3. The polyethylene material provided in this application specifies that the density of the first polyethylene is 0.9–1.0 g / cm³. 3 The melt flow ratio is 20–30, the melt strength is 180–220 mN, and the zero-shear viscosity is 200,000–500,000 Pa·s; preferably, the density of the first polyethylene is 0.94–0.96 g / cm³. 3It has a melt flow ratio of 25 to 30, a melt strength of 200-220 mN, and a zero-shear viscosity of 300,000 to 500,000 Pa·s, which can provide more balanced processing fluidity and anti-sagging properties.

[0050] 4. The polyethylene material provided in this application, by limiting the weight average molecular weight of the second polyethylene to 900,000-1,200,000 g / mol, wherein the proportion of weight average molecular weight of 1,000,000 or above is 25%-35%, and the molecular weight distribution index is 40-50, can provide more balanced processing fluidity and anti-sagging properties.

[0051] 5. The polyethylene material provided in this application includes one or more of SILIMER 9100, SILIMER 9200, SILIMER 9300, and SILIMER 5090 as silicone additives, with a weight-average molecular weight of 100,000 g / mol to 200,000 g / mol. When the molecular weight of the silicone additive is too low (<100,000 g / mol), it is oily with high viscosity and is difficult to disperse. When the molecular weight is too high (>300,000 g / mol), due to its strong polarity, large intermolecular interactions, and numerous entanglements, it is also difficult to disperse, thus failing to achieve an effective lubrication effect. When the molecular weight is moderate, it possesses both good dispersibility and a low coefficient of friction, thereby achieving a better lubrication effect. These silicone additives have long-chain saturated alkyl groups, similar in molecular chain structure to the first and second polyethylene, improving the compatibility of silicone with the first and second polyethylene, further enhancing the dispersibility of silicone during actual processing, thereby maintaining a good lubrication-promoting effect.

[0052] Using a coupling agent with the specific molecular formula of this application can further enhance the interaction between silicone, the first polyethylene and the second polyethylene. Not only is the compatibility of the three greatly improved, but the coupling agent, as a chemical crosslinking point, also further improves the anti-sagging performance of the combined system. Detailed Implementation

[0053] The following embodiments are provided to better understand this application and are not limited to the preferred embodiments described herein. They do not constitute a limitation on the content and scope of protection of this application. Any product that is the same as or similar to this application, derived by anyone under the guidance of this application or by combining features of this application with other prior art, falls within the scope of protection of this application.

[0054] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0055] Example 1

[0056] This embodiment provides a polyethylene material, the raw materials of which are shown in Table 1 according to parts by mass:

[0057] Table 1. Raw materials and mass fractions of polyethylene materials

[0058] raw material Specific types Number of parts by weight / part First polyethylene Wanhua WH23050 80 Second polyethylene Celanese 4112 10 Third polyethylene Licowax PE 190 7 Silicone additives SILIMER 5090 2 Coupling agent Octadecyltrimethoxysilane 1 antioxidants Antioxidant 1076 0.1 Acid remover Calcium stearate 0.05

[0059] The preparation method of this polyethylene material includes the following steps:

[0060] 1. Weigh out each raw material of polyethylene material according to the above proportions.

[0061] 2. Place the second polyethylene, silicone additive, coupling agent, antioxidant and deacidifying agent into a high-speed mixer and stir for 15 minutes to obtain mixture A;

[0062] 3. Heat mixture A to 55°C, then add the first polyethylene and the third polyethylene, and continue stirring and mixing for 20 minutes to obtain mixture B;

[0063] 4. Add mixture B to a twin-screw extruder, controlling the temperature of the first zone to be 180-190℃, the second zone to be 190-200℃, the third zone to be 200-210℃, the fourth zone to be 200-230℃, the fifth zone to be 200-230℃, the sixth zone to be 210-230℃, and the seventh zone to be 210-230℃. The screw speed is 180 r / min. Perform melt blending, extrusion, cooling, and granulation to obtain polyethylene material (i.e., polyethylene anti-melting pipe material).

[0064] Example 2

[0065] This embodiment provides a polyethylene material, the raw materials of which are shown in Table 2 according to parts by mass:

[0066] Table 2 Raw materials and mass fractions of polyethylene materials

[0067]

[0068] The preparation method is the same as in Example 1.

[0069] Example 3

[0070] This embodiment provides a polyethylene material, the raw materials of which are shown in Table 3 according to parts by mass:

[0071] Table 3 Raw materials and mass fractions of polyethylene materials

[0072]

[0073]

[0074] The preparation method is the same as in Example 1.

[0075] Example 4

[0076] This embodiment provides a polyethylene material, the raw materials of which are shown in Table 4 according to parts by mass:

[0077] Table 4. Raw materials and mass fractions of polyethylene materials

[0078] raw material Specific types Number of parts by weight / part First polyethylene Wanhua WH23050 80 Second polyethylene Celanese 4112 8 Third polyethylene Licowax PE 190 10 Silicone additives SILIMER 5090 1 Coupling agent Octadecyltrimethoxysilane 1 antioxidants Antioxidant 1010 0.1 Acid remover Calcium stearate 0.1

[0079] The preparation method is the same as in Example 1.

[0080] Example 5

[0081] This embodiment provides a polyethylene material, the raw materials of which are shown in Table 5 according to parts by mass:

[0082] Table 5. Raw materials and mass fractions of polyethylene materials

[0083]

[0084] The preparation method is the same as in Example 1.

[0085] Example 6

[0086] This embodiment provides a polyethylene material, the raw materials of which are shown in Table 6 according to parts by mass:

[0087] Table 6. Raw materials and mass fractions of polyethylene materials

[0088]

[0089]

[0090] The preparation method is the same as in Example 1.

[0091] Example 7

[0092] This embodiment provides a polyethylene material that is basically the same as that in Embodiment 6, except that the type of the first polyethylene is different. In this embodiment, Wanhua WH4731B of the same mass is used instead of Wanhua WH23050 in Embodiment 6.

[0093] Example 8

[0094] This embodiment provides a polyethylene material that is basically the same as that in Example 6, except that the type of the second polyethylene is different. In this embodiment, Yanshan Petrochemical L1004F of the same mass is used instead of Yanshan Petrochemical MII-2 in Example 6.

[0095] Example 9

[0096] This embodiment provides a polyethylene material that is basically the same as that in Example 1, except that the type of the second polyethylene is different. In this embodiment, polyethylene of grade X3004F provided by Yanshan Petrochemical Company of the same quality is used instead of Celanese 4112 in Example 1.

[0097] Example 10

[0098] This embodiment provides a polyethylene material that is basically the same as that in Example 1, except that the type of the third polyethylene is different. In this embodiment, polyethylene wax A-C6A of the same mass is used instead of Licowax PE 190 in Example 1.

[0099] Comparative Example 1

[0100] This comparative example provides a polyethylene material that is basically the same as that in Example 1, except that the raw material composition is different. The silicone additive and coupling agent are omitted in the raw material of this comparative example.

[0101] Comparative Example 2

[0102] This comparative example provides a polyethylene material that is basically the same as that in Example 1, except that the raw material composition is different. The coupling agent is omitted from the raw material of this comparative example.

[0103] Comparative Example 3

[0104] This comparative example provides a polyethylene material that is basically the same as that in Example 1, except that the raw material composition is different. The third polyethylene is omitted from the raw material of this comparative example.

[0105] Comparative Example 4

[0106] This comparative example provides a polyethylene material that is basically the same as that in Example 1, except that the raw material composition is different. The second polyethylene, third polyethylene, silicone additives and coupling agents are omitted in the raw materials of this comparative example.

[0107] Comparative Example 5

[0108] This comparative example provides a polyethylene material that is basically the same as that in Example 1, except that the second polyethylene is different. In this comparative example, the same mass of polyethylene of grade U090 provided by Korea Petrochemical Corporation is used instead of Celanese 4112 in Example 1. The weight average molecular weight of this polyethylene is 3.39 million g / mol, of which 67% have a weight average molecular weight of 1 million or more and a molecular weight distribution index of 338.

[0109] Comparative Example 6

[0110] This comparative example provides a polyethylene material that is basically the same as that in Example 1, except that the second polyethylene is different. In this comparative example, the same mass of polyethylene with the grade 23050-S provided by Wanhua Chemical Group Co., Ltd. is used instead of Celanese 4112 in Example 1. The weight-average molecular weight of this polyethylene is 340,000 g / mol, of which 9% have a weight-average molecular weight of 1 million or more and a molecular weight distribution index of 36.

[0111] Comparative Example 7

[0112] This comparative example provides a polyethylene material that is essentially the same as that in Example 1, except that the first polyethylene is different. In this comparative example, the same mass of polyethylene of grade 7042 provided by Wanhua Chemical Group Co., Ltd. is used instead of Wanhua WH23050 in Example 1. This polyethylene has a weight-average molecular weight of 100,000 g / mol, a butene comonomer content of 9%, a melt flow rate of 10.2 g / 10 min, and a density of 0.950 g / cm³. 3 The melt flow ratio is 5, the melt strength is 12 mN, and the zero shear viscosity is 2000 Pa·s.

[0113] Comparative Example 8

[0114] This comparative example provides a polyethylene material that is essentially the same as that in Example 1, except that the first polyethylene is different. In this comparative example, the same mass of polyethylene of grade 5731K provided by Wanhua Chemical Group Co., Ltd. is used instead of Wanhua WH23050 in Example 1. This polyethylene has a weight-average molecular weight of 90,000 g / mol, a butene comonomer content of 0.4%, a melt flow rate of 3.38 g / 10 min, and a density of 0.956 g / cm³. 3 The melt flow ratio is 3, the melt strength is 25 mN, and the zero shear viscosity is 3710 Pa·s.

[0115] Experimental Example 1

[0116] The polyethylene materials prepared in each embodiment and comparative example were tested as follows.

[0117] Melt flow rate: Measured according to ISO 1133 GB / T 3682 standard, using a melt flow rate meter at 190℃ and with a 5kg load.

[0118] Melt strength: Tested according to ISO 16790 standard using a Rheotens melt strength tester at 200°C and at a rate of 60 mm / sec. 2 The tension is applied at a constant acceleration.

[0119] Zero-shear viscosity: According to the ATM D4440 standard, the zero-shear viscosity was measured using a rotational rheometer at 200°C with a strain of 1% and a range of 628 to 0.0628 rad / s. The zero-shear viscosity was then calculated using the Carreau-Yasuda model.

[0120] Shear thinning ratio: Tested according to ATM D4440 standard, the ratio of shear viscosity at 628 rad / s to shear viscosity at 0.0628 rad / s.

[0121] The results are shown in the table below:

[0122] Table 7 Processing fluidity test results

[0123]

[0124] Table 8 Results of anti-sagging test

[0125]

[0126]

[0127] As shown in the table above, the polyethylene anti-sagging pipe materials prepared in Examples 1-10 not only possess high melt flow rate and shear thinning ratio, i.e., good processing fluidity, but also meet the high melt strength requirements for anti-sagging of large-diameter pipes. Therefore, the implementation schemes of this application can achieve the production of anti-sagging polyethylene pipe materials with good processing performance. Compared with Examples 6, 8, and 9, Example 1, by using a second polyethylene with a weight-average molecular weight of 1 million or higher and a molecular weight index within the preferred range, provides polyethylene materials with better processing fluidity and higher anti-sagging performance.

[0128] Compared with Example 7, Example 1 provides polyethylene material with better processing fluidity and higher anti-sagging performance by using a first polyethylene with a weight-average molecular weight, butene comonomer content and melt flow rate within the preferred range.

[0129] The melt flow rates of Comparative Examples 1-3 were less than 0.2 g / 10 min, indicating insufficient processing fluidity. Comparative Example 4 had low melt strength and zero-shear viscosity, indicating insufficient resistance to melt sagging.

[0130] Comparative Example 5 used a second polyethylene with an excessively high weight-average molecular weight (MAM) of 1 million or higher, resulting in severe physical entanglement. This prevented it from being fully plasticized and thus lacked the capability for extrusion processing, ultimately rendering it unprocessable.

[0131] Comparative Example 6 showed insufficient resistance to sag due to the use of secondary polyethylene with an excessively low weight-average molecular weight and a low proportion of weight-average molecular weights of 1 million or higher.

[0132] Comparative Examples 7 and 8 used a first polyethylene with a low weight-average molecular weight, butene comonomer content, and melt flow rate that were not within the limits of this application. Due to the low molecular weight, high melt flow rate, and strong plasticizing ability, the matrix material and the second polyethylene were too different in the molten state. The molecular chains of the first polyethylene matrix could move freely and fully, and could not effectively form a physical cross-linked three-dimensional network with the second polyethylene, resulting in insufficient resistance to sag.

[0133] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A polyethylene material, characterized in that, The raw materials include the following parts by weight: The first polyethylene comprises 70-85 parts; the weight-average molecular weight of the first polyethylene is 240,000-350,000 g / mol, and the mass content of butene comonomer is 1%-4%; the melt flow rate is 0.2-0.5 g / 10 min, and the density of the first polyethylene is 0.9-1.0 g / cm³. 3 The melt flow ratio is 20~30, the melt strength is 180-220mN, and the zero shear viscosity is 200000~500000 Pa·s; The second polyethylene, 5-15 parts; the weight-average molecular weight of the second polyethylene is 600,000-3,000,000 g / mol, of which the mass percentage of weight-average molecular weight of 1,000,000 or above is 25%-50%, and the molecular weight distribution index is 30-300. Third polyethylene, 5-10 parts; the weight-average molecular weight of the third polyethylene is 5000 g / mol-50000 g / mol, and the molecular weight distribution index is 3-15; Silicone additive, 1-5 parts; the weight-average molecular weight of the silicone additive is 100,000 g / mol to 200,000 g / mol; Coupling agent, 1-5 parts; the molecular formula of the coupling agent is: R1 is selected from C1-C10 alkyl groups, R2 and R3 are independently selected from C1-C10 alkyl groups or C1-C10 alkoxy groups, and R4 is selected from C5-C25 alkyl groups; the melt flow rate is measured at 190°C with a 5kg load, and the melt flow ratio is the ratio obtained by dividing the melt flow rate at 190°C with a 21.6kg load by the melt flow rate at 190°C with a 5kg load.

2. The polyethylene material according to claim 1, characterized in that, R4 in the coupling agent is selected from C5-C10 cycloalkyl groups.

3. The polyethylene material according to claim 1, characterized in that, The first polyethylene has a weight-average molecular weight of 300,000-350,000 g / mol, a butene comonomer content of 1.5%-2.5%, and a melt flow rate of 0.2-0.3 g / 10 min.

4. The polyethylene material according to claim 1, characterized in that, The density of the first polyethylene is 0.94~0.96 g / cm³. 3 The melt flow ratio is 25~30; the melt strength is 200-220mN; and the zero shear viscosity is 300000~500000 Pa·s.

5. The polyethylene material according to claim 1 or 2, characterized in that, The second polyethylene has a weight-average molecular weight of 900,000 to 1,200,000 g / mol, of which 25% to 35% have a weight-average molecular weight of 1,000,000 or higher, and a molecular weight distribution index of 40 to 50.

6. The polyethylene material according to claim 1 or 2, characterized in that, The silicone additives include one or more of SILIMER9100, SILIMER 9200, SILIMER 9300, and SILIMER 5090.

7. The polyethylene material according to claim 1 or 2, characterized in that, The coupling agent includes one or more of octyltrimethoxysilane, cyclohexylmethyldimethoxysilane, dodecyltrimethoxysilane, dodecylmethyldimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane.

8. The polyethylene material according to claim 7, characterized in that, The coupling agent includes one or more of hexadecyltrimethoxysilane and octadecyltrimethoxysilane.

9. The polyethylene material according to claim 1 or 2, characterized in that, The raw materials for the polyethylene material also include 0.05-2 parts by weight of antioxidant and / or 0.05-0.15 parts by weight of deacidifying agent.

10. The polyethylene material according to claim 9, characterized in that, The antioxidant includes one or more of antioxidants 1076, 168 and 1010; and / or, the acid remover includes one or more of zinc stearate and calcium stearate.

11. A method for preparing a polyethylene material according to any one of claims 1-10, characterized in that, Polyethylene material is produced by mixing raw materials, melting and extruding them.

12. The method for preparing polyethylene material according to claim 11, characterized in that, The temperature of melt extrusion is 180-230ºC, and the rotation speed is 180-240 r / min.

13. The method for preparing polyethylene material according to claim 11, characterized in that, In the mixing step, the raw materials other than the first polyethylene and the third polyethylene are first mixed to obtain mixture A. Then, mixture A is mixed with the first polyethylene and the third polyethylene at 50-60°C to obtain mixture B.

14. A polyethylene product, characterized in that, It is prepared from the polyethylene material described in any one of claims 1-10 or the polyethylene material prepared by any one of claims 11-13.

15. The polyethylene article according to claim 14, characterized in that, The polyethylene product is a polyethylene pipe.

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