Flame-retardant noise-reducing polyethylene drain pipe

Abstract

The application discloses a kind of flame-retardant noise reduction polyethylene drain pipes, belong to drain pipe technical field, the drain pipe includes PE flame-retardant outer layer, PE flame-retardant noise reduction middle layer and PE flame-retardant inner layer;The PE flame-retardant noise reduction middle layer is prepared from the following weight parts of raw materials: high-density polyethylene 30-40 parts, composite microparticle 30-40 parts, flame-retardant masterbatch 6-8 parts;In the application, by adding composite microparticle in PE flame-retardant noise reduction middle layer, the composite microparticle is barium sulfate coated with polymer, the polymer is polysiloxane, increases the sound absorption or sound insulation performance of PE flame-retardant noise reduction middle layer, the better the dispersion effect of the composite microparticle and matrix, the more conducive to the improvement of sound insulation performance.In the application, the composite microparticle added in the PE flame-retardant noise reduction middle layer of polyethylene drain pipe introduces polysiloxane, can form good synergistic flame-retardant effect with a small amount of added flame retardant, so that the flame-retardant grade of drain pipe reaches V-0 level.

Description

Technical Field

[0001] This invention belongs to the field of drainage pipe technology, specifically relating to a flame-retardant and noise-reducing polyethylene drainage pipe. Background Technology

[0002] Existing building drainage pipes are mostly made of plastic, such as PVC (polyvinyl chloride) pipes, PE (polyethylene) pipes, and PP (polypropylene) pipes, with PVC pipes being the most common. However, compared to PVC and PP pipes, PE pipes have superior performance in practical applications, such as corrosion resistance, flexibility, and low-temperature resistance. They also have advantages such as long service life, low production energy consumption, low water flow resistance, and ease of installation and disassembly. PE pipes are expected to gradually replace PVC pipes and become the more widely used pipe material. Currently, HDPE pipes are widely used in siphon drainage or gravity drainage systems.

[0003] However, the existing PE pipes have the following problems when used as water supply and drainage pipes, which limit their promotion and application: (1) Poor flame retardant performance of PE pipes; Since PE material is a flammable polymer with an oxygen index of less than 18%, pipes made of PE material generally have poor flame retardant performance. Therefore, in order to improve the safety of PE pipes when used as drainage pipes in high-rise buildings, it is necessary to improve the flame retardant performance of PE drainage pipes. (2) High noise; The noise of building drainage pipes is composed of a combination of air-driven sound transmission and solid-driven sound transmission. That is, the building drainage pipes are filled with air. During drainage, there is both sound wave transmission with air as the medium and noise caused by pipe vibration due to the impact of water and solid impurities on the pipe wall. Especially for water supply and drainage pipes in high-rise buildings, the noise generated during the water supply and drainage process is one of the main sources of noise in the interior of high-rise buildings. Therefore, it is necessary to improve the sound insulation performance of PE pipes when used as water supply and drainage pipes in buildings.

[0004] To reduce noise in plastic drainage pipes, the material or structure of the plastic pipes must be able to absorb the noise generated by sound waves and pipe wall vibration. Currently, to reduce the noise of water supply and drainage in plastic pipes, a multi-layer pipe structure is used, which includes an intermediate sound-absorbing layer. There are currently two common technologies for the intermediate sound-absorbing layer. One is to use inorganic fillers such as light calcium carbonate or barium sulfate to fill the intermediate layer, so that the pipe has a certain sound insulation and noise reduction performance. The other is to use foaming technology to form a microporous structure in the intermediate layer in an attempt to give the pipe a certain sound insulation and noise reduction capability.

[0005] If the flame retardancy of pipes is to be improved, the following technical problems generally exist: (1) Existing pipes are single-layer structures, which can achieve flame retardancy, but cannot achieve sound insulation and noise reduction capabilities; (2) If existing pipes adopt multi-layer structures, the inner and outer layers achieve flame retardancy, while the middle layer only reduces noise and does not retard. According to the standard GB / T2408-2021 Determination of Burning Performance of Plastics by Horizontal and Vertical Methods, the test requires cutting into strips for testing. The middle layer does not have flame retardancy capabilities, so it is impossible to achieve the V0 level flame retardancy rating. Moreover, existing all-PE pipes, whether single-layer or three-layer, are difficult to reach the V0 level. For example, the patent application with publication number CN113845712A describes a flame retardancy... A flame-retardant and noise-reducing high-rise PE drainage pipe and its preparation method are disclosed. The drainage pipe comprises a three-layer structure: a flame-retardant inner PE layer, a foamed intermediate PE layer, and an outer protective layer. Flame retardants are added to the raw materials for the preparation of the flame-retardant inner and outer protective layers. By improving the flame-retardant performance of the inner and outer layers, the flame-retardant rating of the drainage pipe is comprehensively improved, achieving a V-0 rating. In addition, the foamed intermediate PE layer is mainly formed by foaming grade LDPE, which effectively improves the noise reduction performance of the drainage pipe, reducing drainage noise by 32-34 dB. However, the outer layer must be made of PVC material, which significantly increases the processing difficulty and presents compatibility issues between PVC and PE. Summary of the Invention

[0006] The purpose of this invention is to provide a flame-retardant and noise-reducing polyethylene drainage pipe to solve the problem of poor sound insulation performance of polyethylene drainage pipes.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A flame-retardant and noise-reducing polyethylene drainage pipe includes a flame-retardant outer layer, a flame-retardant and noise-reducing middle layer, and a flame-retardant inner layer; the flame-retardant and noise-reducing middle layer is prepared from the following raw materials in parts by weight: 30-40 parts of high-density polyethylene, 30-40 parts of composite microparticles, and 6-8 parts of flame-retardant masterbatch; the composite microparticles are polymer-coated barium sulfate, and the polymer is polysiloxane.

[0009] In some possible implementations, the composite microparticles are prepared by the following steps:

[0010] Barium sulfate was added to an aqueous ethanol solution, and ammonia was added to adjust the pH of the system to 9-10. After adding tetraethyl orthosilicate and other organosilicon compounds, the mixture was stirred at 40-45℃ for 2.5-3 hours. After the reaction was completed, the mixture was washed with anhydrous ethanol and dried at 80℃ to obtain composite microparticles.

[0011] In some possible implementations, the other organosilicon compound is at least one of dimethyldiethoxysilane, methyltriethoxysilane, triethoxypentylsilane, n-octyltriethoxysilane, and n-hexyltriethoxysilane.

[0012] In some possible implementations, the ethanol-water solution is a mixture of ethanol and water at a volume ratio of 2-3:1; the ratio of barium sulfate to the ethanol-water solution is 1g:4-5mL.

[0013] The mass ratio of barium sulfate, tetraethyl orthosilicate, and other organosilicon compounds is 5-6:1-2:1-2.

[0014] The barium sulfate powder has a mesh size of 1200-1300.

[0015] In some possible implementations, the PE flame-retardant outer layer and the PE flame-retardant inner layer are prepared from the following raw materials in parts by weight: 35-60 parts of high-density polyethylene and 40-65 parts of flame-retardant masterbatch.

[0016] In some possible implementations, the flame retardant masterbatch is prepared by melt-shearing blending extrusion granulation from 30-50 parts of high-density polyethylene, 50-70 parts of compounded flame retardant powder, 0.1-0.8 parts of antioxidant, 0.5-2 parts of coupling agent and 0.2-1 parts of lubricant.

[0017] In some possible implementations, the compounded flame retardant powder includes piperazine pyrophosphate, melamine polyphosphate, and hypophosphite, wherein the hypophosphite is one of diethylaluminum hypophosphite, diethylcerium hypophosphite, diethylcalcium hypophosphite, dipropylaluminum hypophosphite, and methylethylaluminum hypophosphite.

[0018] In some possible implementations, the mass ratio of piperazine pyrophosphate, melamine polyphosphate, and hypophosphite is 5-7:3-5:1.

[0019] In some possible implementations, the antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 1076, and antioxidant 626;

[0020] The coupling agent is one of KH550, KH560 and KH570 coupling agents;

[0021] The lubricant is at least one of erucamide, ethylene bis-stearamide, pentaerythritol stearate, and polyethylene wax.

[0022] In some possible implementations, the thickness ratio of the PE flame-retardant outer layer, the PE flame-retardant noise-reducing intermediate layer, and the PE flame-retardant inner layer is (0.8-2):(6-8):(0.8-2).

[0023] The beneficial effects of this invention are:

[0024] This invention provides a flame-retardant and noise-reducing polyethylene drainage pipe, comprising a flame-retardant outer layer, a flame-retardant and noise-reducing intermediate layer, and a flame-retardant inner layer. In this invention, composite microparticles, specifically polymer-coated barium sulfate and polysiloxane, are added to the intermediate layer. This enhances the sound absorption and insulation properties of the intermediate layer. Better dispersion of the composite microparticles with the matrix (PE) improves sound insulation performance. Since the flame-retardant requirements of polyethylene drainage pipes cannot be met solely by the outer and inner layers, the composite microparticles in the intermediate layer introduce polysiloxane, which creates a synergistic flame-retardant effect with a small amount of added flame retardant, achieving a V-0 flame-retardant rating for the drainage pipe. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0027] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structure may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand this application and is not intended to limit the subject matter of the claims.

[0028] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions, and all technical features and optional technical features of this application can be combined to form new technical solutions.

[0029] High-density or high-area-density materials have high sound absorption or sound insulation capabilities. In this invention, composite microparticles are added to the PE flame-retardant and noise-reducing intermediate layer. The composite microparticles are barium sulfate coated with a polymer, and the polymer is polysiloxane, which increases the sound absorption or sound insulation performance of the PE flame-retardant and noise-reducing intermediate layer.

[0030] The following is a detailed description of a flame-retardant and noise-reducing polyethylene drainage pipe according to an embodiment of this application.

[0031] This application proposes a flame-retardant and noise-reducing polyethylene drainage pipe, comprising a flame-retardant outer layer, a flame-retardant and noise-reducing intermediate layer, and a flame-retardant inner layer. The flame-retardant and noise-reducing intermediate layer is prepared from the following raw materials in parts by weight: 30-40 parts high-density polyethylene, 30-40 parts composite microparticles, and 6-8 parts flame-retardant masterbatch. The composite microparticles are polymer-coated barium sulfate, and the polymer is polysiloxane. The better the dispersion effect between the polysiloxane (a porous framework formed by using tetraethyl orthosilicate and other organosilicon compounds as raw materials) on the surface of the composite microparticles and the matrix (PE), the better the sound insulation performance. The cavities corresponding to the porous structure can better capture mid-range sound waves, and achieve sound energy dissipation through cavity resonance, further improving the noise reduction effect.

[0032] In some embodiments, the composite microparticles are prepared by the following steps:

[0033] Barium sulfate was added to an aqueous ethanol solution, and ammonia was added to adjust the pH of the system to 9-10. Tetraethyl orthosilicate and other organosilicon compounds were then added. The mixture was stirred at 40-45℃ for 2.5-3 hours. After the reaction was complete, the mixture was washed with anhydrous ethanol and dried at 80℃ to obtain composite microparticles. The composite microparticles were obtained by hydrolyzing and condensing tetraethyl orthosilicate and other organosilicon compounds onto the surface of barium sulfate to coat it with a polysiloxane containing a three-dimensional porous framework.

[0034] In some embodiments, the other organosilicon compound is at least one selected from dimethyldiethoxysilane, methyltriethoxysilane, triethoxypentylsilane, n-octyltriethoxysilane, and n-hexyltriethoxysilane. Introducing long-chain alkyl groups into other organosilicon compounds increases their similarity to polyethylene and improves compatibility.

[0035] In some embodiments, the ethanol-water solution is prepared by mixing ethanol and water at a volume ratio of 2-3:1. The volume ratio of barium sulfate to ethanol-water solution is 1g:4-5mL.

[0036] The mass ratio of barium sulfate, tetraethyl orthosilicate, and other organosilicon compounds is 5-6:1-2:1-2.

[0037] The barium sulfate powder has a mesh size of 1200-1300.

[0038] In some embodiments, the PE flame-retardant outer layer and the PE flame-retardant inner layer are prepared from the following raw materials in parts by weight: 35-60 parts of high-density polyethylene and 40-65 parts of flame-retardant masterbatch.

[0039] In some embodiments, the flame retardant masterbatch is prepared by melt, shearing, blending, extrusion and granulation of 30-50 parts of high-density polyethylene, 50-70 parts of compound flame retardant powder, 0.1-0.8 parts of antioxidant, 0.5-2 parts of coupling agent and 0.2-1 parts of lubricant, by weight.

[0040] In some embodiments, the compounded flame-retardant powder includes piperazine pyrophosphate, melamine polyphosphate, and hypophosphite, wherein the hypophosphite is one of diethylaluminum hypophosphite, diethylcerium hypophosphite, diethylcalcium hypophosphite, dipropylaluminum hypophosphite, and methylethylaluminum hypophosphite. The flame-retardant performance is improved by combining different types of flame retardants.

[0041] In some embodiments, the mass ratio of piperazine pyrophosphate, melamine polyphosphate, and hypophosphite is 5-7:3-5:1.

[0042] In some embodiments, the antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 1076, and antioxidant 626;

[0043] The coupling agent is one of KH550, KH560 and KH570 coupling agents;

[0044] The lubricant is at least one of erucamide, ethylene bis-stearamide, pentaerythritol stearate, and polyethylene wax.

[0045] In some embodiments, the thickness ratio of the PE flame-retardant outer layer, the PE flame-retardant noise-reducing intermediate layer, and the PE flame-retardant inner layer is (0.8-2):(6-8):(0.8-2). This ratio is based on cost considerations, as well as on maximizing noise reduction performance.

[0046] The method for preparing the polyethylene drainage pipe disclosed in this invention has no special requirements. It can be done by using three screw extruders to extrude and melt the raw materials corresponding to the three layers of PE flame-retardant outer layer, PE flame-retardant noise-reducing middle layer and PE flame-retardant inner layer into a melt. The melt of the three layers of PE flame-retardant outer layer, PE flame-retardant noise-reducing middle layer and PE flame-retardant inner layer flows into the distribution channels of a set width and thickness from the feed end of a die head with three flow channels. After the three layers of melt are compositely formed in the die head mold, they are cooled, drawn and cut to form the pipe.

[0047] The prepared sample to be tested has an inner diameter of 75 mm and a thickness of 3.7 mm ± 0.1 mm.

[0048] The following description is based on specific embodiments.

[0049] Example 1

[0050] This application provides a flame-retardant and noise-reducing polyethylene drainage pipe, comprising a flame-retardant outer layer, a flame-retardant and noise-reducing middle layer, and a flame-retardant inner layer; the thickness ratio of the flame-retardant outer layer, the flame-retardant and noise-reducing middle layer, and the flame-retardant inner layer is 0.8:6:0.8.

[0051] The PE flame-retardant and noise-reducing intermediate layer is prepared from the following raw materials in parts by weight: 30 parts high-density polyethylene, 30 parts composite microparticles, and 6 parts flame-retardant masterbatch; the composite microparticles are polymer-coated barium sulfate, and the polymer is polysiloxane. The composite microparticles are prepared through the following steps:

[0052] Barium sulfate was added to an ethanol-water solution (ethanol and water were mixed in a volume ratio of 2:1). Ammonia was added to adjust the pH to 9. Tetraethyl orthosilicate and n-hexyltriethoxysilane (diluted with n-hexane) were then added. After the addition was complete, the mixture was stirred at 40°C for 2.5 hours. After the reaction was complete, the mixture was washed with anhydrous ethanol and dried at 80°C to obtain composite microparticles. The volume ratio of barium sulfate to ethanol-water solution was 1 g:4 mL; the mass ratio of barium sulfate, tetraethyl orthosilicate, and n-hexyltriethoxysilane was 5:1:1. The barium sulfate powder was 1200 mesh.

[0053] The flame-retardant outer and inner layers of PE are made from the following raw materials in parts by weight: 35 parts of high-density polyethylene and 40 parts of flame-retardant masterbatch.

[0054] The above-mentioned flame retardant masterbatch is prepared by melt, shearing, blending, extrusion and granulation of 30 parts of high-density polyethylene, 50 parts of compound flame retardant powder, 0.1 parts of antioxidant 10100, 0.5 parts of KH570 coupling agent and 0.2 parts of polyethylene wax.

[0055] The compound flame retardant powder includes piperazine pyrophosphate, melamine polyphosphate and aluminum diethylphosphite, with a mass ratio of 5:3:1.

[0056] The high-density polyethylene used was PE100 grade, with a melt index of 0.5 g / 10 min, and the test conditions were 190℃ and 5 kg.

[0057] Example 2

[0058] This application provides a flame-retardant and noise-reducing polyethylene drainage pipe, comprising a flame-retardant outer layer, a flame-retardant and noise-reducing middle layer, and a flame-retardant inner layer; the thickness ratio of the flame-retardant outer layer, the flame-retardant and noise-reducing middle layer, and the flame-retardant inner layer is 0.8:6:0.8.

[0059] The PE flame-retardant and noise-reducing intermediate layer is prepared from the following raw materials in parts by weight: 30 parts high-density polyethylene, 30 parts composite microparticles, and 6 parts flame-retardant masterbatch; the composite microparticles are polymer-coated barium sulfate, and the polymer is polysiloxane. The composite microparticles are prepared through the following steps:

[0060] Barium sulfate was added to an ethanol-water solution (ethanol and water were mixed in a volume ratio of 3:1). Ammonia was added to adjust the pH to 10. Tetraethyl orthosilicate and n-hexyltriethoxysilane (diluted with n-hexane) were then added. After the addition was complete, the mixture was stirred at 45°C for 3 hours. After the reaction was complete, the mixture was washed with anhydrous ethanol and dried at 80°C to obtain composite microparticles. The volume ratio of barium sulfate to ethanol-water solution was 1 g: 5 mL; the mass ratio of barium sulfate, tetraethyl orthosilicate, and n-hexyltriethoxysilane was 3:1:1. The barium sulfate powder was 1200 mesh.

[0061] The flame-retardant outer and inner layers of PE are made from the following raw materials in parts by weight: 60 parts of high-density polyethylene and 65 parts of flame-retardant masterbatch.

[0062] The above-mentioned flame retardant masterbatch is prepared by melt, shearing, blending, extrusion and granulation of 50 parts of high-density polyethylene, 70 parts of compound flame retardant powder, 10100.8 parts of antioxidant, 2 parts of KH570 coupling agent and 1 part of polyethylene wax.

[0063] The compound flame retardant powder includes piperazine pyrophosphate, melamine polyphosphate and aluminum diethylphosphite, with a mass ratio of 7:5:1.

[0064] The high-density polyethylene used was PE100 grade, with a melt index of 0.5 g / 10 min, and the test conditions were 190℃ and 5 kg.

[0065] Example 3

[0066] The difference between this embodiment and Embodiment 1 is that the raw material ratio of the PE flame-retardant and noise-reducing intermediate layer is different. Specifically, this embodiment is prepared from the following raw materials in parts by weight: 40 parts of high-density polyethylene, 30 parts of composite microparticles, and 6 parts of flame-retardant masterbatch; the remaining raw materials and preparation process are the same as in Embodiment 1.

[0067] Example 4

[0068] The difference between this embodiment and Embodiment 1 is that the raw material ratio of the PE flame-retardant and noise-reducing intermediate layer is different. Specifically, this embodiment is prepared from the following raw materials in parts by weight: 30 parts of high-density polyethylene, 40 parts of composite microparticles, and 8 parts of flame-retardant masterbatch; the remaining raw materials and preparation process are the same as in Embodiment 1.

[0069] Example 5

[0070] The difference between this embodiment and Embodiment 1 lies in the preparation process of the composite microparticles. Specifically, the composite microparticles are prepared through the following steps:

[0071] Barium sulfate was added to an ethanol-water solution (ethanol and water were mixed in a volume ratio of 2:1). Ammonia was added to adjust the pH to 10. Tetraethyl orthosilicate, dimethyldiethoxysilane, and n-octyltriethoxysilane (diluted with n-hexane) were then added. After the addition was complete, the mixture was stirred at 40°C for 2.5 hours. After the reaction was complete, the mixture was washed with anhydrous ethanol and dried at 80°C to obtain composite microparticles. The volume ratio of barium sulfate to ethanol-water solution was 1 g: 4 mL; the mass ratio of barium sulfate, tetraethyl orthosilicate, dimethyldiethoxysilane, and n-octyltriethoxysilane was 5:1:1:1.

[0072] Example 6

[0073] The difference between this embodiment and Embodiment 1 lies in the preparation process of the composite microparticles. Specifically, the composite microparticles are prepared through the following steps:

[0074] Barium sulfate was added to an ethanol-water solution (ethanol and water were mixed in a volume ratio of 2:1). Ammonia was added to adjust the pH to 10. Orthosilicic acid, ethyl orthosilicate methyltriethoxysilane, and triethoxypentylsilane (diluted with n-hexane) were then added. After the addition was complete, the mixture was stirred at 40°C for 2.5 hours. After the reaction was complete, the mixture was washed with anhydrous ethanol and dried at 80°C to obtain composite microparticles. The volume ratio of barium sulfate to ethanol-water solution was 1 g: 4 mL; the mass ratio of barium sulfate, ethyl orthosilicate, ethyl orthosilicate methyltriethoxysilane, and triethoxypentylsilane was 5:1:1:1.

[0075] Example 7

[0076] The difference between this embodiment and Embodiment 1 lies in the preparation process of the composite microparticles. Specifically, the composite microparticles are prepared through the following steps:

[0077] Barium sulfate was added to an ethanol-water solution (ethanol and water were mixed in a volume ratio of 2:1). Ammonia was added to adjust the pH of the system to 10. Tetraethyl orthosilicate and n-hexyltriethoxysilane were then added. After the addition was complete, the mixture was stirred at 40°C for 2.5 hours. After the reaction was complete, the mixture was washed with anhydrous ethanol and dried at 80°C to obtain composite microparticles. The volume ratio of barium sulfate to ethanol-water solution was 1 g: 4 mL; the mass ratio of barium sulfate, tetraethyl orthosilicate, and n-hexyltriethoxysilane was 5:1:1.

[0078] Example 8

[0079] The difference between this example and Example 1 lies in the preparation process of the composite microparticles. The specific composite microparticles are prepared through the following steps:

[0080] Barium sulfate was added to an ethanol-water solution (ethanol and water were mixed in a volume ratio of 2:1). Ammonia was added to adjust the pH to 10. Tetraethyl orthosilicate and triethoxypentylsilane (diluted with n-hexane) were then added. After the addition was complete, the mixture was stirred at 40°C for 2.5 hours. After the reaction was complete, the mixture was washed with anhydrous ethanol and dried at 80°C to obtain composite microparticles. The volume ratio of barium sulfate to ethanol-water solution was 1 g: 4 mL; the mass ratio of barium sulfate, tetraethyl orthosilicate, and triethoxypentylsilane was 5:1:1.

[0081] Comparative Example 1

[0082] This comparative example differs from Example 1 in that it uses untreated barium sulfate instead of the composite microparticles in Example 1; all other raw materials and preparation processes remain the same as in Example 1.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 1 is that barium sulfate treated with a silane coupling agent is used instead of the composite particles in Example 1; the preparation steps of the barium sulfate treated with the silane coupling agent are as follows:

[0085] A mixed solution of silane coupling agent KH-570 and anhydrous ethanol was prepared at a ratio of 1:100. Barium sulfate was then added to the mixed solution and stirred thoroughly to allow KH-570 to fully adsorb onto the barium sulfate surface. The solution was then dried in a forced-air environment at 100°C for 4 hours to obtain barium sulfate treated with silane coupling agent.

[0086] The remaining raw materials and preparation process are the same as in Example 1.

[0087] Comparative Example 3

[0088] The difference between this comparative example and Example 1 is that the raw material ratio of the PE flame-retardant and noise-reducing intermediate layer is different. Specifically, this example is prepared from the following raw materials in parts by weight: 40 parts of high-density polyethylene, 20 parts of composite microparticles, and 6 parts of flame-retardant masterbatch; the remaining raw materials and preparation process are the same as in Example 1.

[0089] Comparative Example 4

[0090] The difference between this comparative example and Example 1 is that the raw material ratio of the PE flame-retardant and noise-reducing intermediate layer is different. Specifically, this example is prepared from the following raw materials in parts by weight: 50 parts of high-density polyethylene, 10 parts of composite microparticles, and 6 parts of flame-retardant masterbatch; the remaining raw materials and preparation process are the same as in Example 1.

[0091] Performance tests were performed on Examples 1-8 and Comparative Examples 1-4;

[0092] Mechanical properties were tested according to standard GB-T 8804.3-2003, "Determination of Tensile Properties of Thermoplastic Pipes - Part 3"; noise reduction performance was tested according to CJ-T312-2009, "Test Method for Noise in Building Drainage Piping Systems"; flame retardant performance was tested according to UL94 flame retardant rating measurement method; the results are shown in Table 1.

[0093] Table 1

[0094]

[0095]

[0096] As can be seen from Table 1, the drainage pipe prepared by the present invention has strong tensile strength, excellent noise reduction performance, and flame retardant performance that can reach V-0 level.

[0097] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant and noise-reducing polyethylene drainage pipe, characterized in that, It includes a PE flame-retardant outer layer, a PE flame-retardant and noise-reducing intermediate layer, and a PE flame-retardant inner layer; the PE flame-retardant and noise-reducing intermediate layer is prepared from the following raw materials in parts by weight: 30-40 parts high-density polyethylene, 30-40 parts composite microparticles, and 6-8 parts flame-retardant masterbatch; the composite microparticles are polymer-coated barium sulfate, and the polymer is polysiloxane; the composite microparticles are prepared through the following steps: Barium sulfate was added to an aqueous ethanol solution, and ammonia was added to adjust the pH of the system to 9-10. After the addition of tetraethyl orthosilicate and other organosilicon compounds, the mixture was stirred and reacted at 40-45℃ for 2.5-3 hours. After the reaction was completed, the mixture was washed with anhydrous ethanol and dried at 80℃ to obtain composite microparticles. The other organosilicon compounds were at least one of dimethyldiethoxysilane, methyltriethoxysilane, triethoxypentylsilane, n-octyltriethoxysilane, and n-hexyltriethoxysilane. The mass ratio of barium sulfate, tetraethyl orthosilicate, and other organosilicon compounds was 5-6:1-2:1-2. The barium sulfate powder was 1200-1300 mesh.

2. The flame-retardant and noise-reducing polyethylene drainage pipe according to claim 1, characterized in that, The ethanol-water solution is prepared by mixing ethanol and water in a volume ratio of 2-3:

1. The ratio of barium sulfate to ethanol aqueous solution is 1g:4-5mL.

3. The flame-retardant and noise-reducing polyethylene drainage pipe according to claim 1, characterized in that, The flame-retardant outer and inner layers of PE are prepared from the following raw materials in parts by weight: 35-60 parts of high-density polyethylene and 40-65 parts of flame-retardant masterbatch.

4. A flame-retardant and noise-reducing polyethylene drainage pipe according to claim 1 or 3, characterized in that, According to the weight percentage, the flame retardant masterbatch is prepared by melt, shearing, blending, extrusion and granulation of 30-50 parts of high-density polyethylene, 50-70 parts of compound flame retardant powder, 0.1-0.8 parts of antioxidant, 0.5-2 parts of coupling agent and 0.2-1 parts of lubricant.

5. A flame-retardant and noise-reducing polyethylene drainage pipe according to claim 4, characterized in that, The compound flame retardant powder includes piperazine pyrophosphate, melamine polyphosphate and hypophosphite, wherein the hypophosphite is one of diethylaluminum hypophosphite, diethylcerium hypophosphite, diethylcalcium hypophosphite, dipropylaluminum hypophosphite and methylethylaluminum hypophosphite.

6. A flame-retardant and noise-reducing polyethylene drainage pipe according to claim 5, characterized in that, The mass ratio of piperazine pyrophosphate, melamine polyphosphate, and hypophosphite is 5-7:3-5:

1.

7. A flame-retardant and noise-reducing polyethylene drainage pipe according to claim 4, characterized in that, The antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 1076 and antioxidant 626; The coupling agent is one of KH550, KH560 and KH570 coupling agents; The lubricant is at least one of erucamide, ethylene bis-stearamide, pentaerythritol stearate, and polyethylene wax.

8. A flame-retardant and noise-reducing polyethylene drainage pipe according to claim 1, characterized in that, The thickness ratio of the PE flame-retardant outer layer, the PE flame-retardant noise-reducing intermediate layer, and the PE flame-retardant inner layer is (0.8-2):(6-8):(0.8-2).

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