Low-sag polyethylene composition as well as preparation method and application thereof
By introducing functional polyethylene materials into polyethylene pipes, the reversible reaction between furyl groups and maleimide groups is used to solve the problem of melting and sagging of large-diameter polyethylene pipes during processing, the wall thickness uniformity and tensile yield strength are improved, and the defects introduced by heterogeneous components are avoided. It is suitable for the production and recycling of large-diameter polyethylene pipes.
Patent Information
- Application Number
- CN202510492366.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2025-08-12
AI Technical Summary
During the processing of large-diameter polyethylene pipes, the sagging phenomenon leads to uneven wall thickness of the pipe, affecting the product's geometric accuracy and mechanical properties. The introduction of heterogeneous materials in the prior art can easily cause interface defects and mechanical properties to decrease when the sagging phenomenon is introduced in the prior art.
Functional polyethylene materials are used as anti-sagging additives, and the reversible Diels-Alder reaction of furan groups and maleimide groups is used to plasticize at high temperatures to reduce the melt flow rate, and form a crosslinking network structure at low temperatures to suppress the melting sagging and improve the tensile yield strength.
It effectively reduces the sag effect, improves the wall thickness uniformity and tensile yield strength of the pipe, and avoids interface defects caused by the introduction of heterogeneous components. It is suitable for the production of different types of pipes and does not affect the utilization of thermoplastic materials during the recycling process.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of polyethylene material modification, and in particular to a low-sag polyethylene composition, a preparation method thereof and an application thereof. Background Art
[0002] During the extrusion process of large-diameter polyethylene pipe, gravity-driven radial flow of the molten resin results in an asymmetric structure along the pipe's circumferential cross-section, with the top section thinner and the bottom thicker. This rheological phenomenon is known as the "sag effect." Research shows that when the nominal outer diameter of the pipe exceeds 800mm, sag can reach 15-30% of the initial wall thickness, severely compromising the product's geometric accuracy. This sag during pipe processing can lead to a range of problems, including pipe wall thickness tolerances exceeding the product standard and thin-walled areas susceptible to damage when the pipe is under pressure.
[0003] CN 114702744 A discloses a low-sag reinforced large-diameter polyethylene water supply pipe using lignin as a functional carrier. Lignin is introduced into the PE matrix to improve sag. However, the introduction of heterogeneous materials into large-diameter high-density polyethylene (HDPE) water supply pipes can easily lead to multiple interface defects. Heterogeneous systems experience interfacial slip under stress, resulting in a decrease in the pipe's mechanical properties, primarily manifested as a decrease in tensile yield strength. Therefore, a core challenge urgently needed to be overcome in the current technical field is how to reduce sag during the processing of large-diameter pipes without introducing heterogeneous components, while also maintaining a decrease in tensile yield strength. Summary of the Invention
[0004] In order to solve the problems existing in the above-mentioned prior art, the primary purpose of the present invention is to provide an application of functional polyethylene as an anti-sag additive for polyethylene.
[0005] Another object of the present invention is to provide a low sag polyethylene composition.
[0006] Another object of the present invention is to provide use of the low sag polyethylene composition in the preparation of polyethylene pipes.
[0007] Another object of the present invention is to provide a large-diameter polyethylene pipe.
[0008] In order to achieve the above object, the present invention provides the following technical solutions:
[0009] A functional polyethylene is used as an anti-sag additive for polyethylene. The functional polyethylene is obtained by reacting polyethylene grafted with glycidyl methacrylate, a maleimide derivative containing a monocarboxyl group, and a furan derivative containing a monocarboxyl group as raw materials. In the raw materials, the molar ratio of maleimide groups to furan groups is 1:1, and the molar ratio of glycidyl ester groups to carboxyl groups is (1 to 1.5):1.
[0010] The present invention uses functional polyethylene material as an anti-sag additive for polyethylene. The furan group and maleimide group connected to the functional polyethylene give it a temperature-responsive dynamic transition characteristic. When the processing temperature is higher than 120°C, the functional polyethylene undergoes a reverse Diels-Alder reaction, and the furan group and maleimide group are in a dissociated state. At this time, the polyethylene melt mass flow rate is high, which is equivalent to the introduction of a plasticizer, which is beneficial for reducing the temperature of pipeline processing, reducing processing energy consumption, reducing the temperature difference that needs to be overcome for pipeline cooling, and alleviating the sag caused by radial heat transfer lag in thick-walled pipes. When cooled to below 80°C, the functional polyethylene undergoes a Diels-Alder reaction, and the furan group and maleimide group undergo a cycloaddition reaction to combine. The cross-linked network structure formed can construct a steric hindrance effect, which can inhibit the sag effect formed by the gravity-induced polyethylene pipe melt flow and reduce the pipe wall thickness deviation. In addition, the cross-linked structure formed by the DA bond helps to improve the tensile yield strength of the pipe.
[0011] Specifically, the amount of the functional polyethylene added is 3 to 6 parts per 100 parts of polyethylene resin.
[0012] A low-sag polyethylene composition comprises the following components in parts by mass: 100 parts of polyethylene resin and 3 to 6 parts of functional polyethylene; the functional polyethylene is obtained by reacting polyethylene grafted with glycidyl methacrylate, a maleimide derivative containing a monocarboxyl group, and a furan derivative containing a monocarboxyl group as raw materials; in the raw materials, the molar ratio of maleimide groups to furan groups is 1:1, and the molar ratio of glycidyl ester groups to carboxyl groups is (1 to 1.5):1.
[0013] The molar ratio of glycidyl ester groups to carboxyl groups is (1-1.5):1, which means that the molar ratio of glycidyl ester groups to carboxyl groups is any value in the range of (1-1.5):1, including 1:1, 1.2:1, 1.3:1 and 1.5:1, but is not limited thereto.
[0014] Specifically, the polyethylene resin is high-density polyethylene. According to the standard GB / T 3682.1-2018, the melt flow rate at 190° C. and 5 kg is 0.2 to 0.5 g / 10 min.
[0015] Specifically, the maleimide derivative containing a monocarboxyl group is at least one of 3-maleimidopropionic acid, 2-maleimidoacetic acid, 6-maleimidocaproic acid, 11-maleimidoundecanoic acid, and 4-(N-maleimido)benzoic acid.
[0016] Specifically, the furan derivative containing a monocarboxyl group is at least one of 5-methylfuran-2-carboxylic acid, 3-(2-furan)propionic acid, 3-furancarboxylic acid, and 3-methyl-2-furancarboxylic acid.
[0017] Specifically, the grafting rate of the glycidyl methacrylate grafted polyethylene is 6 to 12%.
[0018] Specifically, according to the standard GB / T3682.1-2018 test, the melt flow rate of the glycidyl methacrylate grafted polyethylene at 190° C. and 2.16 kg is 2 to 8 g / 10 min.
[0019] Specifically, the polyethylene composition further includes 0.05 to 1 parts of an antioxidant and 0.2 to 3 parts of a colorant.
[0020] More specifically, the antioxidant is at least one of hindered phenols, thioesters or phosphites.
[0021] More specifically, the colorant may be at least one of an inorganic pigment, an organic pigment, and an organic dye.
[0022] Specific examples include titanium oxide, carbon black, phthalocyanine compounds, azo compounds, quinacridone compounds, perylene compounds, anthraquinone compounds, and diketopyrrolopyrrole compounds.
[0023] The colorant is preferably pre-mixed with a small amount of resin and melt-extruded to form a colorant masterbatch. The specific preparation method is conventional in the art and will not be described in detail. The colorant content in the colorant masterbatch is preferably 10-80%.
[0024] Specifically, the preparation method of the functional polyethylene includes:
[0025] The maleimide derivative containing carboxyl group and the furan derivative containing carboxyl group are heated, melted and mixed, cooled, and then mixed with glycidyl methacrylate grafted polyethylene, and extruded and granulated to obtain the functional polyethylene.
[0026] More specifically, the extrusion temperature is 170-200°C.
[0027] More specifically, the extrusion screw speed is 20 to 30 revolutions per minute.
[0028] More specifically, the residence time during extrusion is 5 to 8 minutes.
[0029] The present invention also protects the use of the low sag polyethylene composition in the preparation of polyethylene pipes.
[0030] A large-diameter polyethylene pipe comprises the low-sag polyethylene composition.
[0031] The large-diameter polyethylene pipe refers to a pipe with a nominal outer diameter ≥ 400mm, for example, polyethylene pipes with a nominal outer diameter of 400mm, 800mm, 1000mm, 1800mm, 2500mm and above.
[0032] The cross-linked structure in polyethylene pipes will not dissociate under normal service conditions of the pipes. During the recycling process of polyethylene pipes, the cross-linked structure can dissociate and will not affect the recycling of thermoplastic materials.
[0033] Preferably, the extrusion temperature is 180-200°C, and the cooling temperature is 25-30°C.
[0034] Specifically, the nominal outer diameter of the large-diameter polyethylene pipe is 400 mm to 3000 mm.
[0035] Specifically, the nominal wall thickness of the large-diameter polyethylene pipe is 30 to 200 mm.
[0036] Compared with the prior art, the present invention has the following technical effects:
[0037] The present invention uses a functional polyethylene material as a polyethylene anti-sag additive and introduces the functional polyethylene material into a polyethylene composition. The functional polyethylene is connected with a furan group and a maleimide group. The reversible Diels-Alder reaction of the furan group and the maleimide group is utilized to give the functional polyethylene a dynamic transition characteristic of temperature response, thereby suppressing the sag effect caused by the melt flow of the polyethylene pipe caused by gravity and improving the tensile yield strength of the pipe.
[0038] The low-sag polyethylene composition provided by the present invention can be flexibly adapted to the production of different pipe types through formula adjustment. It can be uniformly dispersed in polyethylene resin without interfacial defects or phase separation. During the polyethylene pipe recycling process, its cross-linked structure can be dissociated, without affecting the recycling of thermoplastic materials. DETAILED DESCRIPTION
[0039] The present invention is further described below with reference to the examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples where specific conditions are not specified are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed in the present invention.
[0040] Glycidyl methacrylate grafted polyethylene 1, manufacturer: Sumitomo Chemical, brand: BF-2C, grafting ratio: 6%. Tested according to standard GB / T3682.1-2018, the melt flow rate is 2.8 g / 10 min at 190°C and 2.16 kg.
[0041] Glycidyl methacrylate grafted polyethylene 2, manufacturer: Sumitomo Chemical, brand: BF-E, grafting ratio: 12%. Tested according to standard GB / T3682.1-2018, the melt flow rate is 3.2 g / 10 min at 190°C and 2.16 kg.
[0042] High-density polyethylene, manufacturer: Sinopec, brand: PN049; density: 0.949g / cm 3 According to the standard GB / T3682.1-2018 test, the melt mass flow rate at 190°C and 5kg is 0.3g / 10min.
[0043] The above melt mass flow rates are measured values.
[0044] Carbon black masterbatch, manufacturer: Gaoming Caiyingfu, model: 2826-5.
[0045] Antioxidant, Manufacturer: BASF, Model: BASF B 225.
[0046] The preparation method of functional polyethylene 1 is as follows:
[0047] S1. 3-Maleimidopropionic acid and 5-methylfuran-2-carboxylic acid are heated and melted in a molar ratio of 1:1, and stirred to completely melt and mix the two. The mixture is then cooled to below 40°C and mechanically crushed and sieved to obtain a 300-mesh powder.
[0048] S2: The powder obtained in S1 was mixed with glycidyl methacrylate grafted polyethylene 1 (grafting rate was 6%) at a molar ratio of glycidyl methacrylate group to carboxyl group of 1.2:1, and then mixed and extruded into granules through a twin-screw extruder. The temperature of the twin-screw extruder was 180-190°C, the screw speed was 20 rpm, and the residence time of the material in the extruder was 6 minutes, thereby obtaining functional polyethylene 1.
[0049] The preparation method of functional polyethylene 2 differs from that of functional polyethylene 1 in that glycidyl methacrylate grafted polyethylene 1 is replaced by glycidyl methacrylate grafted polyethylene 2 (grafting rate is 12%), and the rest is the same as the preparation method of functional polyethylene 1.
[0050] The preparation method of functional polyethylene 3 differs from that of functional polyethylene 1 in that 3-maleimidopropionic acid is replaced by 11-maleimidoundecanoic acid, and 5-methylfuran-2-carboxylic acid is replaced by 3-methyl-2-furancarboxylic acid. The rest is the same as the preparation method of functional polyethylene 1.
[0051] A large-diameter polyethylene pipe, the preparation method of which comprises the following steps:
[0052] A masterbatch containing high-density polyethylene, functional polyethylene, antioxidant and carbon black is added to a screw extruder for plasticization and extrusion of a tube billet, and then vacuum sizing, cooling to, and cutting to obtain a polyethylene pipe with a nominal outer diameter of 1800 mm and a nominal wall thickness of 105.9 mm. The screw extrusion temperature is 180-200°C, and the traction rate is controlled at 0.6 m / min; the water tank cooling time is 6 minutes, and the water tank cooling temperature is 25°C.
[0053] The formulations of Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 1.
[0054] Table 1
[0055]
[0056] Example 6
[0057] This embodiment provides a large-diameter polyethylene pipe, the nominal outer diameter of the large-diameter polyethylene pipe is 400 mm, the nominal wall thickness is 44.7 mm, and the formula and preparation method are the same as those in Example 1.
[0058] Example 7
[0059] This embodiment provides a large-diameter polyethylene pipe, the nominal outer diameter of the large-diameter polyethylene pipe is 3000 mm, the nominal wall thickness is 142.8 mm, and the formula and preparation method are the same as those in Example 1.
[0060] Comparative Example 4
[0061] This comparative example provides a large-diameter polyethylene pipe, which differs from Example 1 only in that the functional polyethylene is replaced with the modified lignin in Example 1 of CN 114702744 A. A polyethylene pipe with a nominal outer diameter of 1800 mm and a nominal wall thickness of 105.9 mm is prepared by the same preparation method as in Example 1, using 100 parts of polyethylene resin, 3 parts of modified lignin, 0.1 parts of antioxidant, and 5 parts of carbon black masterbatch.
[0062] Test method:
[0063] The wall thickness tolerance test standard is GB / T 13663.2—2018.
[0064] The wall thickness tolerance is a positive deviation, that is, the deviation between the wall thickness at any point and the nominal wall thickness.
[0065] The tensile yield strength test standard is GB / T 1040.1—2018.
[0066] The melt mass flow rate test standard is GB / T 3682.1-2018, and the test conditions are 5kg and 190°C.
[0067] The test results are shown in Table 2.
[0068] Table 2
[0069]
[0070] As can be seen from Table 2, the wall thickness tolerance of Examples 1 to 7 is less than 10% of the nominal wall thickness, while the wall thickness tolerance of Comparative Examples 1 to 3 is greater than 10% of the nominal wall thickness. This shows that the functional polyethylene can effectively suppress the sag effect caused by the flow of the polyethylene pipe melt due to gravity through the reversible DA bond.
[0071] As shown in Example 4 and Comparative Example 3, when the functional polyethylene addition level is too high, the pipe wall thickness tolerance actually increases. This is because the excessive amount of functional polyethylene added to the polyethylene matrix increases the melt mass flow rate of the polyethylene material, which in turn exacerbates the sag effect of the polyethylene material, resulting in a weakening of the functional polyethylene's ability to suppress the sag effect. Furthermore, the excessive addition of functional polyethylene increases the cross-linking structure in the polyethylene material, thereby improving the material's tensile yield strength.
[0072] It can be seen from Example 1 and Comparative Example 4 that although the introduction of heterogeneous components into the polyethylene matrix can suppress the sag effect of the pipe, the tensile yield strength of the material is significantly reduced due to the introduction of the heterogeneous components to modify the lignin.
[0073] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.
Claims
1. A use of functional polyethylene as a polyethylene anti-sag additive, characterized in that: The functional polyethylene is obtained by reacting polyethylene grafted with glycidyl methacrylate, a maleimide derivative containing a monocarboxyl group, and a furan derivative containing a monocarboxyl group as raw materials; in the raw materials, the molar ratio of the maleimide group to the furan group is 1:1, and the molar ratio of the glycidyl ester group to the carboxyl group is (1 to 1.5):
1.
2. The application according to claim 1, characterized in that The added amount of the functional polyethylene is 3 to 6 parts per 100 parts of polyethylene resin.
3. A low sag polyethylene composition, characterized in that The invention comprises the following components in parts by mass: 100 parts of polyethylene resin and 3 to 6 parts of functional polyethylene; the functional polyethylene is obtained by reacting polyethylene grafted with glycidyl methacrylate, a maleimide derivative containing a monocarboxyl group, and a furan derivative containing a monocarboxyl group as raw materials; in the raw materials, the molar ratio of maleimide group to furan group is 1:1, and the molar ratio of glycidyl ester group to carboxyl group is (1 to 1.5):
1.
4. The low sag polyethylene composition according to claim 3, wherein The maleimide derivative containing a monocarboxyl group is at least one of 3-maleimidopropionic acid, 2-maleimidoacetic acid, 6-maleimidocaproic acid, 11-maleimidoundecanoic acid, and 4-(N-maleimido)benzoic acid.
5. The low sag polyethylene composition according to claim 3, wherein The furan derivative containing a monocarboxyl group is at least one of 5-methylfuran-2-carboxylic acid, 3-(2-furan)propionic acid, 3-furancarboxylic acid, and 3-methyl-2-furancarboxylic acid.
6. The low sag polyethylene composition according to claim 3, wherein The glycidyl methacrylate grafted polyethylene has a melt flow rate of 2 to 8 g / 10 min at 190° C. and 2.16 kg.
7. The low sag polyethylene composition according to claim 3, wherein The polyethylene composition further comprises 0.05 to 1 parts of an antioxidant and 0.2 to 3 parts of a colorant.
8. The low sag polyethylene composition according to claim 3, wherein The polyethylene resin is high-density polyethylene, and its melt flow rate at 190° C. and 5 kg is 0.2-0.5 g / 10 min.
9. Use of the low sag polyethylene composition according to any one of claims 3 to 8 in the preparation of polyethylene pipes.
10. A large diameter polyethylene pipe, characterized in that: The low sag polyethylene composition comprises the low sag polyethylene composition according to any one of claims 3 to 8.