Polyethylene material, preparation method thereof and polyethylene product

Abstract

The invention relates to the technical field of modification of universal high polymer materials, in particular to a polyethylene material, a preparation method of the polyethylene material and a polyethylene product, and the polyethylene material comprises the following raw materials in parts by mass: 70-85 parts of first polyethylene; 5 to 15 parts of second polyethylene; 5 to 10 parts of third polyethylene; 1-5 parts of a silicone auxiliary agent; the weight-average molecular weight of the first polyethylene is 240,000-350,000 g / mol, and the content of the butene comonomer is 1%-4%; the melt flow rate is 0.2 to 0.5 g / 10min; the weight-average molecular weight of the second polyethylene is 600,000-3,000,000 g / mol, the proportion of the second polyethylene with the weight-average molecular weight of 1,000,000 or above is 25%-50%, and the molecular weight distribution index is 30-300; the weight-average molecular weight of the third polyethylene ranges from 5000 g / mol to 50000 g / mol; through the matching use of the components, the polyethylene material not only has high sag resistance, but also has excellent processing fluidity, and meets the actual production requirements of large-diameter pipes in the pipe industry.

Description

Technical Field

[0001] The present application relates to the technical field of general polymer material modification, and in particular to a polyethylene material and a preparation method thereof, and a polyethylene product. Background Art

[0002] Polyethylene (PE) pipes have the advantages of excellent chemical corrosion resistance, good toughness and no pollution to the conveying medium. They are widely used in urban water supply and drainage pipes, gas pipes and other fields. In addition, the application of PE pipes in marine engineering, chemical medicine, mining and other fields is also gradually increasing. For example, marine aquaculture cages and water leisure platforms are gradually gaining favor in the market. As the application scope of PE pipes continues to expand, the demand for large-diameter PE pipes is gradually increasing, and the research on materials for large-diameter PE pipes has received more and more attention.

[0003] In addition to meeting the basic physical properties of conventional polyethylene materials, the materials used for large-diameter PE pipes should also meet the anti-sag characteristics in the production of large-diameter pipes. At present, there are three major methods for preparing anti-sag high-density polyethylene (HDPE): reaction synthesis method, chemical cross-linking method and adding ultra-high molecular weight polyethylene. Among them, the reaction synthesis method is subject to the influence of catalysts and reaction processes, and usually has limited effect on improving the anti-sag performance of HDPE; the chemical cross-linking method can significantly improve the anti-sag properties of HDPE, but the cross-linked HDPE forms a cross-linked network structure, which limits its processing and recycling; the method of adding ultra-high molecular weight polyethylene is usually subject to the difficult processing of ultra-high molecular weight polyethylene, and cannot achieve an effective balance between good processing performance and high anti-sag performance.

[0004] Ordinary HDPE has poor anti-sag performance, which limits its application in large-diameter pipes, large-capacity containers, etc., while ultra-high molecular weight polyethylene has particularly long molecular chains and abundant physical entanglement points as the "cross-linking points" of the system, which greatly improves the anti-sag performance of ordinary HDPE pipe materials. However, due to the serious entanglement of molecular chains, its processing performance is extremely poor. Therefore, in order to solve the problem that processing performance and anti-sag performance cannot be taken into account when ultra-high molecular weight polyethylene is mixed with ordinary HDPE, technical innovation work is carried out. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present application is to overcome the problem in the prior art that when ultra-high molecular weight polyethylene is blended with ordinary HDPE, both processing performance and anti-sag performance cannot be taken into account.

[0006] The present application provides a polyethylene material, comprising the following raw materials in parts by weight:

[0007] The 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 / 10min;

[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% to 50%, and the molecular weight distribution index is 30 to 300;

[0009] 5-10 parts of a third polyethylene; 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 certain preferred embodiments, the weight average molecular weight of the first polyethylene is 300,000-350,000 g / mol, the butene comonomer content is 1.5%-2.5%, and the melt flow rate is 0.2-0.3 g / 10 min.

[0013] The first polyethylene, the second polyethylene, the third polyethylene and the coupling agent of the present application can be synthesized by conventional synthesis methods or purchased commercially. The first polyethylene can be, for example, polyethylene with the brand WH23050 and WH4731B provided by Wanhua Chemical Group Co., Ltd. The preferred polyethylene is WH23050.

[0014] The weight average molecular weight of polyethylene with the brand name WH23050 is 310,000 g / mol, the butene comonomer content is 1.5%; the density is 0.950 g / cm 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 weight average molecular weight of polyethylene with the brand name WH4731B is 240,000 g / mol, the butene comonomer content is 2%; the density is 0.947 g / cm 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 is tested by GPC, the first polyethylene in the present application is a copolymer of ethylene and 1-butene, and the content of butene comonomer refers to the mass percentage of butene comonomer in the first polyethylene. It is tested by gel permeation chromatography-infrared spectrometer (GPC-IR) online combination.

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

[0018] The term melt flow rate (MFR), also referred to as melt index (MI), is the number of grams of melt that flows out of a resin melt through a standard capillary in a certain time (generally 10 minutes) at a certain temperature and load in a standardized melt flow rate meter, and the unit is g / 10min. The melt flow rate is measured in accordance with ISO 1133GB / T 3682 by a melt flow rate meter at a temperature of 190°C and a load of 5kg. The melt flow ratio is the ratio of the melt flow rate at 190°C and a load of 21.6kg divided by the melt flow rate at 190°C and a load of 5kg. Melt strength is tested by a Rheotens melt strength meter in accordance with ISO 16790.

[0019] The zero shear viscosity is measured by a rotational rheometer according to ATM D4440. The zero shear viscosity is calculated by the Carreau-Yasuda model after measuring the zero shear viscosity at 200°C, 1% strain, and 628 to 0.0628 rad / s.

[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, polyethylene with grades MII-2, L1004F, and X3004F provided by Yanshan Petrochemical Company, preferably polyethylene with grade 4112 provided by Celanese Corporation of the United States and polyethylene with grade MII-2 provided by Yanshan Petrochemical Company.

[0021] The weight average molecular weight of polyethylene with grade 4112 is 920,000 g / mol, of which the weight average molecular weight of 1 million and above accounts for 27%, and the molecular weight distribution index is 43.

[0022] The weight average molecular weight of polyethylene with grade 4122 is 1.94 million g / mol, of which the weight average molecular weight of 1 million and above accounts for 46%, and the molecular weight distribution index is 222.

[0023] The weight average molecular weight of polyethylene with brand name 145M is 910,000 g / mol, of which the weight average molecular weight of 1 million and above accounts for 26%, 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 the weight average molecular weight of 1 million and above accounts for 50%, and the molecular weight distribution index is 82.

[0025] The weight average molecular weight of polyethylene with brand name L1004F is 1.06 million g / mol, of which the weight average molecular weight of 1 million and above accounts for 31%, and the molecular weight distribution index is 59.

[0026] The weight average molecular weight of polyethylene with brand name X3004F is 1.94 million g / mol, of which the weight average molecular weight of 1 million and above accounts for 49%, and the molecular weight distribution index is 176.

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

[0028] The weight average molecular weight of 1 million and above is obtained by GPC testing and grading the data.

[0029] The third polyethylene can be, for example, polyethylene wax A-C6A provided by Honeywell or Licowax PE 190 provided by Clariant. The preferred brand is Licowax PE 190 provided by 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] The weight average molecular weight of Licowax PE 190 is 22600 g / mol, and the molecular weight distribution index is 3.9.

[0032] In certain preferred embodiments, the density of the first polyethylene is 0.9-1.0 g / cm 3 , melt flow ratio is 20-30, melt strength is 180-220mN, zero shear viscosity is 200000-500000Pa·s; preferably, the density of the first polyethylene is 0.94-0.96g / cm 3 , melt flow ratio is 25-30; melt strength is 200-220mN, and zero shear viscosity is 300000-500000Pa·s.

[0033] In certain preferred embodiments, the weight average molecular weight of the second polyethylene is 900,000-1.2 million g / mol, of which the weight average molecular weight of 1 million and above accounts for 25%-35%, and the molecular weight distribution index is 40-50.

[0034] In certain preferred embodiments, the silicone additive comprises one or more of SILIMER 9100, SILIMER 9200, SILIMER 9300, and SILIMER 5090. These silicone additives can be purchased from Chengdu Silike Technology Co., Ltd. The weight average molecular weight of these silicone additives is 100000 g / mol to 200000 g / mol. These silicone additives have long-chain saturated alkyl groups.

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

[0036] In certain preferred embodiments, the raw material of the polyethylene material further comprises 0.05-2 parts by mass of an antioxidant and / or 0.05-0.15 parts by mass of an acid scavenger.

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

[0038] The present application also provides a method for preparing any of the above-mentioned polyethylene materials, comprising mixing raw materials of the polyethylene materials, and melt-extruding to prepare the polyethylene material;

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

[0040] In certain preferred embodiments, in the mixing step, the raw materials other than the first polyethylene and the third polyethylene are first mixed to obtain a mixture A, and then the mixture A is mixed with the first polyethylene and the third polyethylene at 50-60° C. to obtain a mixture B. The second polyethylene has a high molecular weight, is prone to thermal oxidation fracture, and is not easy to process, so it is preferentially mixed with a coupling agent and a silicone additive, etc., which is beneficial to maintaining its chemical properties stable and improving its dispersibility and processing performance.

[0041] In certain preferred embodiments, the preparation method comprises the following steps:

[0042] (1) placing the second polyethylene, the silicone additive, the coupling agent, the antioxidant and the acid scavenger into a high-speed mixer, stirring and mixing for 10-25 minutes to obtain a mixture A;

[0043] (2) heating the mixture A to 50-60° C., then adding the first polyethylene and the third polyethylene, and continuing to stir and mix for 10-25 minutes to obtain a mixture B;

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

[0045] The present application also provides a polyethylene product, which is made from any of the polyethylene materials described above or the polyethylene material prepared by the above preparation method; optionally, the polyethylene product is a polyethylene tube.

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

[0047] 1. The polyethylene material provided in the present application comprises the following raw materials in parts by weight: 70-85 parts of the first polyethylene; 5-15 parts of the second polyethylene; 5-10 parts of the third polyethylene; 1-5 parts of a silicone additive; and 1-5 parts of a coupling agent, wherein the weight average molecular weight of the first polyethylene is 240,000-350,000 g / mol, the butene comonomer content is 1% to 4%; and the melt flow rate is 0.2 to 0.5 g / 10 min; 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% to 50%, The molecular weight distribution index is 30 to 300; the weight average molecular weight of the third polyethylene is 5000 g / mol-50000 g / mol, and the molecular weight distribution index is 3 to 15; through the synergistic effect of the first polyethylene with a specific molecular weight, butene comonomer content and melt flow rate, the second polyethylene with a specific molecular weight and proportion and a specific molecular weight distribution index, the third polyethylene with a specific molecular weight and molecular weight distribution index, and the silicone additive in a specific ratio, the problem of difficult processing caused by the improvement of the anti-sag performance of the polyethylene material is avoided, and the high anti-sag performance and good processing performance are achieved. The second polyethylene with a specific molecular weight, proportion and specific molecular weight distribution index, with its abundant molecular weight chain entanglement points, acts as a physical cross-linking point to form an effective network structure, which greatly improves the anti-sag performance of the first polyethylene. The third polyethylene with a lower molecular weight acts as a common lubricant, which facilitates the stretching of the first polyethylene and the second polyethylene, avoids excessive molecular chain entanglement, and improves the fluidity of the mixed system. Due to the low friction coefficient of the silicone molecule itself, when the silicone additive is evenly dispersed in the resin matrix, the third polyethylene produces a synergistic effect, improves the melt flow rate of the resin matrix, and can greatly improve the processing fluidity of the system. Through the use of the above components, the polyethylene material not only has high anti-sag performance, but also has excellent processing fluidity, which meets the actual production needs of large-diameter pipes in the pipe industry.

[0048] 2. The polyethylene material provided in the present application can provide more balanced processing fluidity and anti-sag performance 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 / 10min.

[0049] 3. The polyethylene material provided in this application is characterized by limiting the density of the first polyethylene to 0.9 to 1.0 g / cm 3 The melt flow ratio is 20-30, the melt strength is 180-220 mN, and the zero shear viscosity is 200000-500000 Pa·s; preferably, the density of the first polyethylene is 0.94-0.96 g / cm 3, melt flow ratio is 25-30; melt strength is 200-220mN, and zero shear viscosity is 300000-500000Pa·s, which can provide more balanced processing fluidity and anti-sag performance.

[0050] 4. The polyethylene material provided in the present application, by limiting the weight average molecular weight of the second polyethylene to 900,000-1.2 million g / mol, of which the weight average molecular weight of 1 million and above accounts for 25% to 35%, and the molecular weight distribution index is 40 to 50, can provide more balanced processing fluidity and anti-sag performance.

[0051] 5. The polyethylene material provided by the present application, the silicone additive comprises one or more of SILIMER 9100, SILIMER 9200, SILIMER 9300, and SILIMER 5090, and the weight average molecular weight of these silicone additives is 100000g / mol to 200000g / mol; when the molecular weight of the silicone additive is too low (<100000g / mol), it is oily, has a large viscosity, and is not easy to disperse. When the molecular weight is too large (>300000g / mol), due to strong polarity, large intermolecular action, and many entanglements, it is also not easy to disperse, so that an effective lubrication effect cannot be achieved. When the molecular weight is moderate, it has both good dispersibility and low friction coefficient, thereby achieving a better lubrication effect. These silicone additives have long-chain saturated alkyl groups, which are similar to the molecular chain structures of the first polyethylene and the second polyethylene, improve the compatibility of silicone in the first polyethylene and the second polyethylene, and further improve the dispersibility of silicone in the actual processing process, thereby maintaining a good lubrication promotion effect.

[0052] The use of a coupling agent having a specific molecular formula of the present application can further enhance the interaction between silicone, the first polyethylene and the second polyethylene, not only greatly improving the compatibility of the three, but also the coupling agent, as a chemical cross-linking point, further improves the anti-sag performance of the combined system. DETAILED DESCRIPTION

[0053] The following examples are provided for a better understanding of the present application, but are not limited to the best implementation mode described, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the protection scope of the present application.

[0054] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0055] Example 1

[0056] This embodiment provides a polyethylene material, and its raw materials are shown in Table 1 in terms of mass fraction:

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

[0058] raw material Specific types Mass parts / parts First Polyethylene Wanhua WH23050 80 Second polyethylene Celanese 4112 10 The third polyethylene Licowax PE 190 7 Silicone additives SILIMER 5090 2 Coupling agent Octadecyltrimethoxysilane 1 Antioxidants Antioxidant 1076 0.1 Acid scavengers Calcium stearate 0.05

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

[0060] 1. According to the above ratio, weigh the raw materials of polyethylene material.

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

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

[0063] 4. Add mixture B into a twin-screw extruder, control the temperature of the first zone to 180-190°C, the temperature of the second zone to 190-200°C, the temperature of the third zone to 200-210°C, the temperature of the fourth zone to 200-230°C, the temperature of the fifth zone to 200-230°C, the temperature of the sixth zone to 210-230°C, the temperature of the seventh zone to 210-230°C, the screw speed to 180r / min, carry out melt blending, extrusion, cooling and granulation to obtain a polyethylene material (i.e., a polyethylene anti-melt vertical pipe material).

[0064] Example 2

[0065] This embodiment provides a polyethylene material, and its raw materials are shown in Table 2 in terms of mass fraction:

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

[0067]

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

[0069] Example 3

[0070] This embodiment provides a polyethylene material, and its raw materials are shown in Table 3 in terms of mass fraction:

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

[0072]

[0073]

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

[0075] Example 4

[0076] This embodiment provides a polyethylene material, and its raw materials are shown in Table 4 in terms of mass fraction:

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

[0078] raw material Specific types Mass parts / parts First Polyethylene Wanhua WH23050 80 Second polyethylene Celanese 4112 8 The third polyethylene Licowax PE 190 10 Silicone additives SILIMER 5090 1 Coupling agent Octadecyltrimethoxysilane 1 Antioxidants Antioxidant 1010 0.1 Acid scavengers Calcium stearate 0.1

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

[0080] Example 5

[0081] This embodiment provides a polyethylene material, and its raw materials are shown in Table 5 in terms of mass fraction:

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

[0083]

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

[0085] Example 6

[0086] This embodiment provides a polyethylene material, and its raw materials are shown in Table 6 in terms of mass fraction:

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

[0088]

[0089]

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

[0091] Example 7

[0092] This embodiment provides a polyethylene material, which is basically the same as that of Embodiment 6, except that the type of the first polyethylene is different. This embodiment uses Wanhua WH4731B of the same quality to replace Wanhua WH23050 in Embodiment 6.

[0093] Example 8

[0094] This embodiment provides a polyethylene material, which is basically the same as that of Embodiment 6, except that the type of the second polyethylene is different. This embodiment uses the same quality of Yanshan Petrochemical L1004F to replace the Yanshan Petrochemical MII-2 of Embodiment 6.

[0095] Example 9

[0096] This embodiment provides a polyethylene material, which is basically the same as that of embodiment 1, except that the type of the second polyethylene is different. This embodiment uses polyethylene of the same quality and grade X3004F provided by Yanshan Petrochemical Company to replace Celanese 4112 in embodiment 1.

[0097] Example 10

[0098] This embodiment provides a polyethylene material, which is basically the same as that of Embodiment 1, except that the type of the third polyethylene is different. This embodiment uses polyethylene wax A-C6A of the same mass to replace Licowax PE 190 of Embodiment 1.

[0099] Comparative Example 1

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

[0101] Comparative Example 2

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

[0103] Comparative Example 3

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

[0105] Comparative Example 4

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

[0107] Comparative Example 5

[0108] This comparative example provides a polyethylene material, which is basically the same as Example 1, except that the second polyethylene is different. This comparative example uses a polyethylene with a brand name of U090 provided by Korea Petrochemical Corporation of the same quality to replace Celanese 4112 in Example 1. The weight average molecular weight of the polyethylene is 3.39 million g / mol, of which the weight average molecular weight is 1 million and above accounts for 67%, and the molecular weight distribution index is 338.

[0109] Comparative Example 6

[0110] This comparative example provides a polyethylene material, which is basically the same as Example 1, except that the second polyethylene is different. This comparative example uses a polyethylene with a brand number of 23050-S provided by Wanhua Chemical Group Co., Ltd. of the same mass to replace Celanese 4112 in Example 1. The weight average molecular weight of the polyethylene is 340,000 g / mol, of which the weight average molecular weight of 1 million and above accounts for 9%, and the molecular weight distribution index is 36.

[0111] Comparative Example 7

[0112] This comparative example provides a polyethylene material, which is basically the same as Example 1, except that the first polyethylene is different. This comparative example uses a polyethylene with a brand number of 7042 provided by Wanhua Chemical Group Co., Ltd. of the same quality to replace Wanhua WH23050 in Example 1. The weight average molecular weight of the polyethylene is 100,000 g / mol, the butene comonomer content is 9%; the melt flow rate is 10.2 g / 10 min, and the density is 0.950 g / cm 3 , melt flow ratio is 5, melt strength is 12mN, and zero shear viscosity is 2000Pa·s.

[0113] Comparative Example 8

[0114] This comparative example provides a polyethylene material, which is basically the same as Example 1, except that the first polyethylene is different. This comparative example uses a polyethylene with a brand of 5731K provided by Wanhua Chemical Group Co., Ltd. of the same quality to replace Wanhua WH23050 in Example 1. The weight average molecular weight of the polyethylene is 90,000 g / mol, the butene comonomer content is 0.4%; the melt flow rate is 3.38 g / 10 min, and the density is 0.956 g / cm 3 , melt flow ratio is 3, melt strength is 25mN, and zero shear viscosity is 3710Pa·s.

[0115] Experimental Example 1

[0116] The polyethylene materials prepared in the examples and comparative examples were subjected to the following tests.

[0117] Melt flow rate: According to ISO 1133GB / T 3682 standard, the melt flow rate is measured by a melt flow rate meter at a temperature of 190°C and a load of 5 kg.

[0118] Melt Strength: Tested according to ISO 16790 standard, tested by Rheotens melt strength tester, measured at 200℃ and 60mm / sec 2 Stretching is performed at a constant acceleration.

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

[0120] Shear Thinning Ratio: The ratio of the shear viscosity at 628 rad / s to the shear viscosity at 0.0628 rad / s, tested according to ATM D4440 standard.

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

[0122] Table 7 Processing fluidity test results

[0123]

[0124] Table 8 Anti-sag test results

[0125]

[0126]

[0127] As can be seen from the above table, the polyethylene anti-sag pipe materials prepared in Examples 1-10 not only have high melt flow rate and shear thinning ratio, that is, have good processing fluidity, but also meet the high melt strength of large-diameter pipe anti-sag, that is, through the implementation scheme of the present application, the production of anti-sag polyethylene pipe materials with good processing performance can be achieved. Example 1 is compared with Examples 6, 8, and 9. Example 1 adopts a second polyethylene with a weight average molecular weight of 1 million or more and a molecular weight index within a preferred range to provide the polyethylene material with better processing fluidity and higher anti-sag performance.

[0128] Compared with Example 7, Example 1 can provide the polyethylene material with better processing fluidity and higher anti-sag performance by adopting the 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 are lower than 0.2 g / 10 min, and the processing fluidity is obviously insufficient. The melt strength and zero shear viscosity of Comparative Example 4 are low, that is, the anti-sag property is insufficient.

[0130] Comparative Example 5 uses a second polyethylene with a weight-average molecular weight that is too large, a large proportion of which is 1 million or above, and a molecular weight index that is too large, which leads to severe physical entanglement, inability to be fully plasticized, lack of extrusion processing capability, and ultimately failure to be processed.

[0131] Comparative Example 6 has insufficient anti-sag properties because it uses a second polyethylene with an excessively small weight average molecular weight and an excessively small proportion of a second polyethylene with a weight average molecular weight of 1 million or more.

[0132] Comparative Examples 7 and 8 use a first polyethylene with a relatively low weight-average molecular weight, a butene comonomer content and a melt flow rate that are no longer within the range specified in the present application. Due to the low molecular weight, high melt flow rate, and strong plasticizing ability, the base material and the second polyethylene in the molten state are too different. The molecular chains of the first polyethylene base material can move fully and freely, and cannot effectively form a physically cross-linked three-dimensional network with the second polyethylene, resulting in insufficient anti-sag properties.

[0133] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. A polyethylene material, characterized in that: Including the following raw materials by mass: The first polyethylene, 70-85 parts; the weight average molecular weight of the first polyethylene is 240,000-350,000 g / mol, the mass content of butene comonomer is 1%-4%; the melt flow rate is 0.2-0.5 g / 10min; 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% to 50%, and the molecular weight distribution index is 30 to 300; 5-10 parts of a third polyethylene; 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; Coupling agent, 1-5 parts.

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

3. The polyethylene material according to claim 1 or 2, characterized in that: The density of the first polyethylene is 0.9-1.0 g / cm 3 , melt flow ratio is 20-30, melt strength is 180-220mN, zero shear viscosity is 200000-500000Pa·s; preferably, the density of the first polyethylene is 0.94-0.96g / cm 3 , melt flow ratio is 25-30; melt strength is 200-220mN, and zero shear viscosity is 300000-500000Pa·s.

4. The polyethylene material according to any one of claims 1 to 3, characterized in that: The weight average molecular weight of the second polyethylene is 900,000-1.2 million g / mol, of which the weight average molecular weight of 1 million and above accounts for 25% to 35%, and the molecular weight distribution index is 40 to 50.

5. The polyethylene material according to any one of claims 1 to 4, characterized in that: The silicone additive includes one or more of SILIMER 9100, SILIMER 9200, SILIMER 9300, and SILIMER 5090.

6. The polyethylene material according to any one of claims 1 to 5, characterized in that: The molecular formula of the coupling agent is Wherein R1 is selected from C1-C10 alkyl, R2 and R3 are independently selected from C1-C10 alkyl or C1-C10 alkoxy, and R4 is selected from C5-C25 alkyl or C5-C10 cycloalkyl; preferably, the coupling agent includes one or more of octyltrimethoxysilane, cyclohexylmethyldimethoxysilane, dodecyltrimethoxysilane, dodecylmethyldimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane, and more preferably includes one or more of hexadecyltrimethoxysilane and octadecyltrimethoxysilane.

7. The polyethylene material according to any one of claims 1 to 6, characterized in that: The raw material of the polyethylene material also includes 0.05-2 parts by weight of an antioxidant and / or 0.05-0.15 parts by weight of an acid scavenger.

8. The polyethylene material according to claim 7, characterized in that The antioxidant includes one or more of antioxidant 1076, antioxidant 168 and antioxidant 1010; and / or the acid scavenger includes one or more of zinc stearate and calcium stearate.

9. A method for preparing the polyethylene material according to any one of claims 1 to 8, characterized in that: The raw materials of the polyethylene material are mixed and melt-extruded to obtain the polyethylene material; Optionally, the temperature of melt extrusion is 180-230°C and the rotation speed is 180-240r / min; Optionally, in the mixing step, the raw materials except the first polyethylene and the third polyethylene are first mixed to obtain a mixture A, and then the mixture A is mixed with the first polyethylene and the third polyethylene at 50-60° C. to obtain a mixture B.

10. A polyethylene product, characterized in that: Made from the polyethylene material described in any one of claims 1-8 or the polyethylene material prepared by the preparation method of claim 9; optionally, the polyethylene product is a polyethylene tube.

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