PE recycled material for municipal pipelines and preparation method of PE recycled material

Abstract

The invention relates to the technical field of high polymer materials, and particularly discloses a PE recycled material for municipal pipelines and a preparation method of the PE recycled material. The toughening modifier and the filler master batch are introduced into the formula of the PE recycled material. Through synergistic cooperation of the filler master batch and the toughening modifier, the PE recycled material can have high impact strength, the performance of the PE recycled material is superior to that of a commercially available regenerated PE product, the requirements of municipal pipelines for the performance such as pressure resistance, impact resistance and long-term service stability can be fully met, resource utilization of the waste PE material is fully achieved, and the economic benefit is increased. The obvious green and environment-friendly significance is realized.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and more specifically, it relates to a recycled PE material for municipal pipelines and its preparation method. Background Technology

[0002] Polyethylene (PE) is an important synthetic material. Due to its excellent corrosion resistance, lightweight, chemical stability, and processing performance, it has been widely used in packaging, agricultural films, pipes, cable sheaths, and other fields. Especially in municipal gas engineering, polyethylene (PE) pipes have gradually replaced traditional metal pipes since the 1950s, becoming the core material of the "plastic-for-steel" technological revolution, and are widely used in water conservancy projects, urban pipe networks, and other fields.

[0003] Currently, the recycling of polyethylene has become an important direction for alleviating resource pressure and reducing environmental pollution. However, existing recycled polyethylene technologies are mostly concentrated on low-end products (such as packaging materials and miscellaneous items), and the molecular chains of the material are prone to breakage and degradation during the recycling process, leading to a significant decline in performance. Related studies show that the processing stability and mechanical properties of recycled polyethylene are difficult to meet the requirements of complex working conditions, and its recycling methods are mostly limited to the simple physical recycling stage.

[0004] Regarding the aforementioned technologies, the inventors believe that the impact strength of recycled polyethylene is generally lower than that of virgin materials, which cannot meet the stringent requirements of municipal pipelines for pressure resistance, impact resistance, and long-term service stability. In practical applications, it is prone to structural failure, making it difficult for recycled polyethylene to be used in municipal pipeline systems such as gas and water supply, which seriously restricts its resource utilization. Summary of the Invention

[0005] In related technologies, the impact strength of recycled polyethylene is generally lower than that of virgin materials, making it difficult to use in municipal pipeline systems such as gas and water supply. To overcome this deficiency, this application provides a recycled PE material for municipal pipelines and its preparation method.

[0006] Firstly, this application provides a recycled PE material for municipal pipelines, employing the following technical solution: A recycled PE material for municipal pipelines, comprising the following components by weight: 100-110 parts waste PE material, 7-9 parts toughening modifier, 15-20 parts filler masterbatch, 0.8-1.5 parts color masterbatch, and 0.6-0.8 parts processing aid; the toughening modifier comprises POE elastomer and waste tire rubber powder; the filler masterbatch comprises PE resin, inorganic filler, and resin acid, wherein the inorganic filler content in the filler masterbatch is 70-75%.

[0007] By adopting the above technical solution, this application introduces a toughening modifier and filler masterbatch into the formulation of recycled PE material. The main component of the filler masterbatch is inorganic filler. The PE resin in the filler masterbatch can increase the compatibility between the filler masterbatch and waste PE material, while the resin acid can assist in the dispersion of inorganic filler. After recycling, the inorganic filler in the filler masterbatch can be uniformly dispersed in the recycled PE material, and the resin acid can fully bond the inorganic filler with PE molecules, thereby strengthening the PE molecules using the mechanical properties of the inorganic filler. The main components of the toughening modifier are PE elastomer and waste tire rubber powder. These two elastomer materials can absorb impact energy when subjected to external impact, allowing the impact energy to be uniformly dispersed within the material, and then shared by the inorganic filler and PE molecules. Through the synergistic effect of filler masterbatch and toughening modifier, the PE recycled material of this application can have high impact strength and outperform commercially available recycled PE products. It can fully meet the requirements of municipal pipelines for pressure resistance, impact resistance and long-term service stability, and fully realize the resource utilization of waste PE material, which has significant green and environmental protection significance.

[0008] Preferably, the resin acid accounts for 5-7% of the total weight of the filler masterbatch.

[0009] By adopting the above technical solution, this application optimizes the dosage range of resin acid, promotes the uniform dispersion of inorganic fillers, and facilitates the inorganic fillers and PE molecules to jointly bear the dispersed impact load, thereby obtaining PE recycled material with high impact strength.

[0010] Preferably, the inorganic filler in the filler masterbatch also includes one of gypsum whiskers and sericite powder.

[0011] By adopting the above technical solution, this application has selected the type of inorganic filler. In the formulation system of this application, the inorganic filler can fully share and absorb impact energy, which helps to improve the impact strength of recycled PE material.

[0012] Preferably, the inorganic filler in the filler masterbatch also includes fly ash, wherein the fly ash is Class F, Grade I fly ash.

[0013] By adopting the above technical solution, the particle size of Class F Grade I fly ash is smaller and the microstructure is more regular, which helps to reduce stress concentration and improve the impact strength of PE recycled material.

[0014] Preferably, the fly ash is pretreated according to the following method before use: Fly ash is added to deionized water and mechanically stirred to obtain a fly ash suspension. Hydrogen peroxide solution is added dropwise to the fly ash suspension, and the mechanical stirring reaction continues. After the reaction is completed, the mixture is filtered, and the filter residue is washed, dried, and ground to complete the pretreatment of fly ash.

[0015] By adopting the above technical solution, this application pretreats fly ash with hydrogen peroxide. After hydrogen peroxide treatment, the hydroxyl content on the surface of the fly ash increases, thereby enabling it to combine more fully with resin acids and improving the dispersion effect of the fly ash. The microstructure of the fly ash is mainly spherical microspheres, which can avoid stress concentration caused by irregular shapes or sharp edges. Moreover, thanks to the good dispersion effect of inorganic fillers, fly ash can significantly improve the impact strength of PE recycled materials.

[0016] Preferably, the filler masterbatch is prepared according to the following method: PE resin and inorganic filler are mixed, preheated, and then resin acid and PE wax are added. After stirring and mixing, the mixture is discharged and processed by extruder to obtain filler masterbatch.

[0017] By adopting the above technical solution, this application blends PE resin, inorganic fillers, resin acid, and PE wax to obtain filler masterbatch. Using this filler masterbatch can effectively improve the impact strength of recycled PE materials.

[0018] Preferably, the toughening modifier is prepared according to the following method: (1) Mix waste tire rubber powder and solubilizer, and after static aging, obtain pretreated rubber powder for later use; mix LLDPE resin and solubilizer to obtain pretreated LLDPE for later use. (2) Mix the pretreated rubber powder, pretreated LLDPE and POE elastomer to obtain a mixture, melt extrusion granulation of the mixture, and then dry it to obtain a toughening modifier.

[0019] By adopting the above technical solution, this application first treats waste tire rubber powder and LLDPE resin separately with a solubilizer, and then blends them with POE elastomer to obtain a toughening modifier. The LLDPE resin in the toughening modifier can improve the compatibility between the toughening modifier and waste PE material, which helps to improve the impact strength of recycled PE material.

[0020] Preferably, the POE elastomer is pretreated according to the following method before use: The POE elastomer is mixed with glycidyl methacrylate and dicumyl peroxide, and the resulting mixture is melt-extruded in an extruder, then pelletized and air-dried to complete the pretreatment of the POE elastomer.

[0021] By adopting the above technical solution, this application uses dicumyl peroxide as an initiator and glycidyl methacrylate as a grafting monomer to pretreat POE elastomer, thereby increasing the content of short-chain branches in the POE elastomer. Short branches increase the possibility of molecular chains contacting each other, which is beneficial for the formation of a network structure. This allows the elastomer to absorb more impact energy when subjected to external impact, thus helping to improve the impact strength of recycled PE materials.

[0022] Preferably, in the method of pretreating the POE elastomer, 1-octene is also added to the extruder.

[0023] By adopting the above technical solution, this application further introduces octene as a grafting monomer. Through the joint grafting of glycidyl methacrylate and 1-octene, the POE elastomer in the toughening modifier can produce a good adhesion effect with PE molecules, which helps to improve the impact strength of recycled PE materials.

[0024] Secondly, this application provides a method for preparing recycled PE material for municipal pipelines, using the following technical solution.

[0025] A method for preparing recycled PE material for municipal pipelines includes the following steps: (1) The waste PE material is washed and dried, and then the waste PE material and filler masterbatch are mixed and extruded to granulate to obtain an intermediate. (2) The intermediate, toughening modifier, color masterbatch and processing aid are mixed and then extruded and granulated to obtain recycled PE material for municipal pipelines.

[0026] By adopting the above technical solution, this application first uses waste PE material and filler masterbatch to mix and granulate, so that the inorganic filler and PE recycled material are uniformly mixed to obtain an intermediate. Then, the intermediate is mixed with toughening modifier, color masterbatch and processing aid and then extruded again to obtain PE recycled material for municipal pipelines with good impact resistance.

[0027] In summary, this application has the following beneficial effects: 1. The PE recycled material of this application has high impact strength and its performance is superior to commercially available recycled PE products. It can fully meet the requirements of municipal pipelines for pressure resistance, impact resistance and long-term service stability, and fully realize the resource utilization of waste PE material, which has significant green and environmental protection significance.

[0028] 2. This application uses hydrogen peroxide to pretreat fly ash, increasing the hydroxyl content on the fly ash surface, thereby enabling it to bind more fully with resin acids and improving the dispersion effect of fly ash. Fly ash can avoid stress concentration caused by irregular shapes or sharp edges, and thanks to the good dispersion effect of inorganic fillers, fly ash can significantly improve the impact strength of PE recycled materials. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the embodiments, preparation examples and comparative examples. The raw materials involved in the present application can all be obtained commercially.

[0030] Example of filler masterbatch preparation The following explanation uses Preparation Example 1 as an example.

[0031] Preparation Example 1 In this preparation example, the inorganic filler is gypsum whiskers (average diameter 1.8 μm, aspect ratio 50), and the weight of the inorganic filler accounts for 70% of the total weight of the filler masterbatch; the weight of the resin acid accounts for 5% of the total weight of the filler, the weight of the PE wax accounts for 1% of the total weight of the filler, and the balance is made up to 100% by PE resin.

[0032] In this preparation example, the filler masterbatch was prepared according to the following method: PE resin and inorganic filler were added to a high-speed mixer and mixed. After preheating at 105℃ for 10 minutes, resin acid and PE wax were added and stirred for 2 minutes before being discharged. The mixture was then processed by a twin-screw extruder to obtain filler masterbatch. The temperatures of zones one through seven were 150℃, 190℃, 190℃, 190℃, 180℃, and 170℃, respectively.

[0033] As shown in Table 1, the difference between preparation examples 1-3 lies in the different raw material ratios of the filler masterbatch.

[0034] Table 1 Raw material ratio of filler masterbatch Preparation Example 4 The difference between this preparation example and preparation example 3 is that the inorganic filler used is 200-mesh sericite powder.

[0035] Preparation Example 5 The difference between this preparation example and preparation example 4 is that the inorganic filler also includes fly ash, which is Class F, Grade II fly ash, and the weight of fly ash accounts for 50% of the total weight of the inorganic filler.

[0036] Preparation Example 6 The difference between this preparation example and preparation example 5 is that the fly ash used is Class I fly ash of type F.

[0037] Preparation Example 7 The difference between this preparation example and Preparation Example 6 is that the fly ash is pretreated according to the following method before use: Fly ash is added to deionized water at a weight ratio of 1:1 and mechanically stirred to obtain a fly ash suspension. Hydrogen peroxide solution is added dropwise to the fly ash suspension at a dosage of 200g of 30wt% hydrogen peroxide solution per kilogram of fly ash. The reaction is then continued with mechanical stirring. After 5 hours, the mixture is filtered, and the filter residue is washed, dried, and ground to complete the pretreatment of fly ash.

[0038] Preparation example of toughening modifier The following explanation uses Preparation Example 8 as an example.

[0039] Preparation Example 8 In this preparation example, the solubilizer is 26# white oil, the weight ratio of waste tire rubber powder, POE elastomer and LLDPE resin is 3:2:2, the LLDPE resin is DFDA 7042, the waste tire rubber powder is 80 mesh, and the POE elastomer is Engage 8150 (DOW Chemicals, Inc., USA).

[0040] In this preparation example, the toughening modifier was prepared according to the following method: (1) Mix waste tire rubber powder and solubilizer (3% of waste tire rubber powder) and allow it to stand for 5 days to age to obtain pretreated rubber powder for later use; mix LLDPE resin and solubilizer (0.5% of LLDPE resin weight) to obtain pretreated LLDPE for later use. (2) The pretreated rubber powder, pretreated LLDPE and POE elastomer are mixed to obtain a mixture. The mixture is melt-extruded and granulated, and then dried at 75℃ for 10h to obtain a toughening modifier. In this step, the process conditions of twin-screw extrusion granulation are as follows: the temperatures of each zone of the heating section are 165℃, 170℃, 170℃, 175℃, 175℃, 170℃, and 170℃ respectively, and the die head temperature is 175℃; the main screw speed is 120r / min; and the feeding speed is 20r / min.

[0041] Preparation Example 9 The difference between this preparation example and preparation example 8 is that the POE elastomer is pretreated according to the following method before use: POE elastomer is mixed with glycidyl methacrylate and dicumyl peroxide in a weight ratio of 100:4.3:0.2. The resulting mixture is melt-extruded in an extruder, then pelletized and air-dried to complete the pretreatment of POE elastomer. The extruder temperatures are 165℃, 185℃, 188℃, and 170℃.

[0042] Preparation Example 10 The difference between this preparation example and preparation example 9 is that, in the method of pretreating the POE elastomer, 1-octene is added to the extruder, and the molar ratio of 1-octene to glycidyl methacrylate is 1:1. Example

[0043] Examples 1-5 The following description uses Example 1 as an example.

[0044] Example 1 In this embodiment, the recycled PE material is composed of a first component with a melt flow index of 2.5 g / 10 min and a second component with a melt flow index of 5 g / 10 min mixed in a 1:1 weight ratio, and the particle size of the recycled PE material is 5-15 mm.

[0045] In this embodiment, the filler masterbatch was prepared according to the method of Preparation Example 1, and the toughening modifier was prepared according to the method of Preparation Example 8. The processing aid used in this preparation example was a mixture of vinyltrimethoxysilane, DCPO, manganese dioxide, copper oxide, antioxidant 168, antioxidant 1010, EBS, stearic acid, and zinc stearate in a weight ratio of 0.3:0.02:0.01:0.01:0.015:0.015:0.03:0.1:0.1.

[0046] This embodiment provides a recycled PE material for municipal pipelines. The recycled PE material includes the following components by weight: 100 kg of waste PE material, 7 kg of toughening modifier, 15 kg of filler masterbatch, 0.8 kg of color masterbatch, and 0.6 kg of processing aid.

[0047] This embodiment provides a method for preparing recycled PE material for municipal pipelines, including the following steps: (1) The waste PE material is washed and dried, and then the waste PE material and filler masterbatch are mixed and extruded and granulated at 190°C and 200 rpm screw speed to obtain the intermediate. (2) The intermediate, toughening modifier, color masterbatch and processing aid are mixed and then extruded and granulated at 190°C and screw speed of 200 rpm to obtain PE recycled material for municipal pipelines.

[0048] As shown in Table 2, the main difference between Examples 1-5 is that the raw material ratio of recycled PE is different.

[0049] Table 2 Raw material ratio of recycled PE sample Example 1 Example 2 Example 3 Example 4 Example 5 Waste PE material / kg 100 102 105 108 110 Toughening modifier / kg 7 7.5 8 8.5 9 Filler masterbatch / kg 15 16 18 19 20 Masterbatch / kg 0.8 1.0 1.2 1.3 1.5 Processing aids / kg 0.6 0.65 0.7 0.75 0.8 Examples 5-11 As shown in Table 3, the difference between Examples 5-11 is that the preparation examples of the filler masterbatch are different.

[0050] Table 3 Examples of filler masterbatch preparation sample Preparation Example Example 5 Preparation Example 1 Example 6 Preparation Example 2 Example 7 Preparation Example 3 Example 8 Preparation Example 4 Example 9 Preparation Example 5 Example 10 Preparation Example 6 Example 11 Preparation Example 7 Examples 11-13 As shown in Table 4, the difference between Examples 11-13 is that the preparation examples of the toughening modifier are different.

[0051] Table 4 Examples of Toughening Modifier Preparation sample Preparation Example Example 11 Preparation Example 8 Example 12 Preparation Example 9 Example 13 Preparation Example 10 Comparative Example Comparative Example 1 The difference between this comparative example and Example 1 is that the components of the recycled PE material do not include toughening modifiers and filler masterbatches.

[0052] Comparative Example 2 The difference between this comparative example and Example 1 is that the PE recycled material does not include a toughening modifier.

[0053] Comparative Example 3 The difference between this comparative example and Example 1 is that the PE recycled material does not include filler masterbatch.

[0054] Comparative Example 4 The difference between this comparative example and Example 1 is that the filler masterbatch does not contain resin acid.

[0055] Performance testing methods The impact strength of recycled PE was tested according to the method described in ASTM D256, and the results are shown in Table 5.

[0056] Table 5 Impact Strength Test Results As can be seen from Examples 1-5 and Comparative Example 1, and in conjunction with Table 5, the impact strength measured in Examples 1-5 is higher. This is because this application introduces inorganic fillers through a filler masterbatch containing resin acid and introduces elastomers through a toughening modifier. The mechanical properties of the inorganic fillers reinforce the PE molecules, and the elastomer material enables the impact energy to be uniformly dispersed within the material, where it is then shared by the inorganic fillers and PE molecules. Through the synergistic effect of the filler masterbatch and the toughening modifier, the recycled PE material of this application can possess higher impact strength, outperforming commercially available recycled PE products.

[0057] As can be seen from Example 1 and Comparative Example 2 and Table 5, the impact strength measured in Example 1 is higher than that in Comparative Example 2. This is because Comparative Example 2 lacks a toughening modifier, which results in the inability to effectively absorb and disperse the impact force, thus leading to a lower overall impact strength.

[0058] Combining Example 1 and Comparative Examples 3-4 with Table 5, it can be seen that the impact strength measured in Example 1 is higher than that in Comparative Examples 3-4. This is because Comparative Example 3 lacks filler masterbatch, while the inorganic filler in Comparative Example 4 cannot achieve uniform dispersion through the action of resin acid. Therefore, Comparative Examples 3-4 cannot effectively absorb impact energy through the synergistic effect of PE molecules and inorganic fillers, resulting in a lower overall impact strength.

[0059] As can be seen from Examples 5-8 and Table 5, within the range of inorganic filler type, resin acid content and inorganic filler content defined in this application, the PE recycled material with added filler masterbatch has higher impact strength.

[0060] As can be seen from Examples 8 and 9-11, combined with Table 5, the improvement in impact strength of the PE recycled material by Class II fly ash (F type) in Example 9 is limited. However, the addition of Class I fly ash (F type) in Example 10 effectively improves the impact strength of the PE recycled material. This is because Class I fly ash has a smaller particle size and more regular microstructure, which helps reduce stress concentration. After hydrogen peroxide modification, the hydroxyl content on the fly ash surface increases, allowing it to bind more fully with the resin acid and improving the dispersion effect of the fly ash. Therefore, the impact strength measured in Example 11 is higher than that in Example 10.

[0061] As can be seen from Examples 11-13 and Table 5, the impact strength of recycled PE increases after grafting pretreatment of the POE elastomer in the toughening modifier. This is because the grafting pretreatment increases the content of short branches in the POE elastomer. Short branches increase the possibility of molecular chains contacting each other, which is conducive to the formation of a network structure and can absorb more impact energy when subjected to external impact.

[0062] The above embodiments are merely explanations of this application and are not intended to limit it. After reading this specification, those skilled in the art can make modifications to the embodiments of this application without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of this application.

Claims

1. A type of recycled PE material for municipal pipelines, characterized in that, The recycled PE material comprises the following components in parts by weight: 100-110 parts waste PE material, 7-9 parts toughening modifier, 15-20 parts filler masterbatch, 0.8-1.5 parts color masterbatch, and 0.6-0.8 parts processing aid; the toughening modifier comprises POE elastomer and waste tire rubber powder; the filler masterbatch comprises PE resin, inorganic filler, and resin acid, and the inorganic filler content in the filler masterbatch is 70-75%.

2. The recycled PE material for municipal pipelines according to claim 1, characterized in that, The resin acid accounts for 5-7% of the total weight of the filler masterbatch.

3. The recycled PE material for municipal pipelines according to claim 1, characterized in that, The inorganic filler in the filler masterbatch also includes one of gypsum whiskers and sericite powder.

4. The recycled PE material for municipal pipelines according to claim 3, characterized in that, The inorganic filler in the filler masterbatch also includes fly ash, which is Class F, Grade I fly ash.

5. The recycled PE material for municipal pipelines according to claim 4, characterized in that, The fly ash is pretreated according to the following method before use: Fly ash is added to deionized water and mechanically stirred to obtain a fly ash suspension. Hydrogen peroxide solution is added dropwise to the fly ash suspension, and the mechanical stirring reaction continues. After the reaction is completed, the mixture is filtered, and the filter residue is washed, dried, and ground to complete the pretreatment of fly ash.

6. The recycled PE material for municipal pipelines according to claim 2, characterized in that, The filler masterbatch is prepared according to the following method: PE resin and inorganic filler are mixed, preheated, and then resin acid and PE wax are added. After stirring and mixing, the mixture is discharged and processed by extruder to obtain filler masterbatch.

7. The recycled PE material for municipal pipelines according to claim 1, characterized in that, The toughening modifier is prepared according to the following method: (1) Waste tire rubber powder and solubilizer are mixed and allowed to stand for aging to obtain pretreated rubber powder for later use; LLDPE resin and solubilizer are mixed to obtain pretreated LLDPE for later use; (2) Mix the pretreated rubber powder, pretreated LLDPE and POE elastomer to obtain a mixture, melt extrude and granulate the mixture, and then dry it to obtain a toughening modifier.

8. The recycled PE material for municipal pipelines according to claim 7, characterized in that, The POE elastomer is pretreated according to the following method before use: The POE elastomer is mixed with glycidyl methacrylate and dicumyl peroxide, and the resulting mixture is melt-extruded in an extruder, then pelletized and air-dried to complete the pretreatment of the POE elastomer.

9. The recycled PE material for municipal pipelines according to claim 8, characterized in that, In the method of pretreating the POE elastomer, 1-octene is also added to the extruder.

10. The method for preparing recycled PE material for municipal pipelines according to any one of claims 1-9, characterized in that, Includes the following steps: (1) The waste PE material is washed and dried, and then the waste PE material and filler masterbatch are mixed and extruded to granulate to obtain the intermediate. (2) The intermediate, toughening modifier, color masterbatch and processing aid are mixed and then extruded and granulated to obtain PE recycled material for municipal pipelines.

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