A PPR composite material with chlorine resistance, its preparation method and application

Abstract

This invention discloses a chlorine-resistant PPR composite material, its preparation method, and its application, relating to the technical field of polypropylene materials. A chlorine-resistant PPR composite material comprises the following components in parts by weight: 92-97 parts of random copolymer polypropylene; 0.1-3 parts of chlorine-resistant agent; 0.05-1 part of antioxidant; and 0.5-2 parts of lubricant. The chlorine-resistant agent is a polyethylene glycol-bridged hindered phenolic antioxidant, wherein the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant is 4500-6000 g·mol⁻¹. ‑1 The weight-average molecular weight of the random copolymer polypropylene is 64-69 W. The PPR composite material described in this invention has excellent chlorine resistance, and its addition to PPR pipes can give the PPR pipes excellent migration resistance.

Description

Technical Field

[0001] This invention relates to the technical field of polypropylene materials, and more particularly to a PPR composite material with chlorine resistance, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP) materials are widely used in various industries due to their high cost-effectiveness. However, most PP materials contain unsaturated bonds or groups such as carbonyl and hydroxyl groups, making them susceptible to external factors during processing and use. This can lead to polymer chain breakage, cross-linking, and group detachment, resulting in aging phenomena such as hardening, stickiness, powdering, cracking, yellowing, and decreased transparency, significantly shortening their service life. Therefore, to extend the service life of PP materials and enhance their performance during processing and use, antioxidants are typically added to inhibit or delay oxidation reactions. Even low concentrations of antioxidants can suppress PP oxidation without altering the manufacturing process. Commonly used antioxidants include phenolic antioxidants, phosphite antioxidants, and thioester (ether) antioxidants.

[0003] Currently, in the pipeline industry, with the trend of replacing steel with plastics, plastic pipes account for an increasingly larger proportion of drinking water pipes. To ensure stable product quality, the industry has proposed a 50-year lifespan concept in standard setting, which has also promoted the rapid market acceptance of plastic pipes. However, some plastic pipes transporting drinking water containing chlorine disinfectants have experienced premature failure. This is mainly because active chlorine causes traditional antioxidants 1010 and 168 to be prematurely degraded, rendering them ineffective in providing protection. Therefore, developing a PPR drinking water pipe that meets chlorine resistance requirements is of paramount importance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a PPR composite material with chlorine resistance, its preparation method, and its application. The PPR composite material of this invention exhibits excellent chlorine resistance; adding it to PPR pipes enables the PPR pipes to possess excellent migration resistance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention also provides a chlorine-resistant PPR composite material, comprising the following components in parts by weight:

[0007] Random copolymer polypropylene (PPR) 92-97 parts; chlorine resistant agent 0.1-3 parts; antioxidant 0.05-1 part; lubricant 0.5-2 parts;

[0008] The chlorine-resistant agent is a polyethylene glycol-bridged hindered phenolic antioxidant, wherein the molecular weight of the polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant is 4500-6000 g·mol⁻¹. -1 The weight-average molecular weight of the random copolymer polypropylene is 64-69W.

[0009] In this invention, due to the excellent migration resistance of polyethylene glycol-bridged hindered phenolic antioxidants, adding them as an antichlorine agent to PPR pipes effectively solves the problem of antioxidant detachment caused by prolonged flushing of the inlet pipe. Furthermore, the polyethylene glycol molecular chains in the polyethylene glycol-bridged hindered phenolic antioxidants can form a hydrophilic protective layer, preventing contact between active chlorine and the pipe, effectively improving the pipe's chlorine resistance. Simultaneously, by controlling the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidants within the aforementioned range, this invention further enhances the migration resistance of the composite material.

[0010] This invention uses polypropylene with a specific molecular weight and polyethylene glycol to bridge hindered phenolic antioxidants, which is beneficial to improving the chlorine resistance of PPR composites. Furthermore, by controlling the molecular weight of polypropylene within the above-mentioned range, this invention also makes the processing performance and heat-resistant processing stability of PPR composites less susceptible to impact.

[0011] Preferably, the polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant has a molecular weight of 4500 g·mol⁻¹. -1 5000g·mol -1 5500g·mol -1 6000g·mol -1 The range of any one or both of them.

[0012] Preferably, the random copolymer polypropylene has a melt flow rate of 0.27-0.32 g / 10 min at 230°C and 2.16 kg load.

[0013] More preferably, the melt flow rate of the random copolymer polypropylene at 230°C and 2.16 kg load is any one or a combination of 0.27 g / 10 min, 0.28 g / 10 min, 0.29 g / 10 min, 0.30 g / 10 min, 0.31 g / 10 min, and 0.32 g / 10 min.

[0014] The test standard for the melt flow rate of the random copolymer polypropylene is GB / T 3682-2000.

[0015] Preferably, the antioxidant includes hindered amine antioxidants and phosphite antioxidants.

[0016] More preferably, the hindered amine antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1330; and the phosphite antioxidant is at least one of antioxidant 168 and antioxidant 626.

[0017] Preferably, the lubricant includes at least one of white oil, calcium stearate, and ethylene bis-stearamide (EBS), which can promote the adhesion between the components in the composite material and improve the blending effect.

[0018] Preferably, the preparation method of the polyethylene glycol-bridged hindered phenolic antioxidant includes the following steps:

[0019] (1) Dissolve polyethylene glycol in chloroform, stir until homogeneous, add β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride and triethylamine dropwise under an inert atmosphere, and react at 40-45℃ for 20-24h to obtain a mixture;

[0020] (2) After the reaction is complete, remove triethylamine and chloroform from the mixture, then add ice-cold ether dropwise, stir to precipitate, let stand, filter, wash and dry to obtain polyethylene glycol bridged hindered phenol antioxidant.

[0021] This invention uses polyethylene glycol as a bridging group and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride as an antioxidant functional group to synthesize polyethylene glycol-bridged hindered phenolic antioxidants through the alcoholysis reaction of acyl chloride.

[0022] Preferably, in step (1), the molar ratio of polyethylene glycol, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride, and triethylamine is 1:(4-6):6.

[0023] Secondly, the present invention also provides a method for preparing a chlorine-resistant PPR composite material, comprising the following steps:

[0024] Random copolymer polypropylene, chlorine resistant agent, antioxidant and lubricant are mixed evenly in proportion, dried and then melt-blended in an extruder to obtain chlorine resistant PPR composite material.

[0025] Preferably, the temperature of the extruder is 195-230℃ and the rotation speed is 15-100 r / min.

[0026] Thirdly, the present invention also provides a PPR pipe with chlorine resistance, the PPR pipe including a chlorine-resistant layer, the chlorine-resistant layer including a chlorine-resistant PPR composite material.

[0027] Preferably, the PPR pipe further includes a composite layer, a barrier layer, and a coloring layer sequentially disposed around the outer periphery of the chlorine-resistant layer.

[0028] Preferably, the thickness of the chlorine-resistant layer is 1-3 mm, the thickness of the composite layer is 1-3 mm, the thickness of the barrier layer is 0.1-0.3 mm, and the thickness of the coloring layer is 1-3 mm.

[0029] Preferably, the composite layer comprises PPR and glass fiber, wherein the mass ratio of PPR to glass fiber is (80-85):(15-20).

[0030] More preferably, the length of the glass fiber is 10-20 μm.

[0031] Preferably, the coloring layer comprises PPR and color masterbatch, wherein the mass ratio of PPR to color masterbatch is 100:(1-2).

[0032] Preferably, the barrier layer comprises ethylene-vinyl alcohol copolymer (EVOH), wherein the ethylene content of the ethylene-vinyl alcohol copolymer is 38%, and the molecular weight of the ethylene-vinyl alcohol copolymer is 8-13W.

[0033] Fourthly, the present invention also provides a method for preparing a PPR pipe with chlorine resistance, comprising the following steps:

[0034] (1) Mix PPR and glass fiber in the composite layer evenly to obtain mixture A, and mix PPR and color masterbatch in the color layer evenly to obtain mixture B;

[0035] (2) Chlorine-resistant PPR composite material, mixture A, ethylene-vinyl alcohol copolymer and mixture B are added to the feeding equipment in sequence and extruded through four single screw extruders. Then, four layers are co-extruded at the die head to obtain a heat pipe blank. Finally, the heat pipe blank is sized and cooled in a vacuum to obtain a PPR pipe with chlorine resistance.

[0036] Preferably, in step (2), the temperature of the single screw extruder is 190-225℃ and the rotation speed is 30-120r / min.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] (1) The polyethylene glycol-bridged hindered phenol antioxidant described in this invention has excellent migration resistance as an antichlorine agent. Adding it to PPR pipes can effectively solve the problem of antioxidant detachment caused by long-term water inlet pipe flushing.

[0039] (2) This invention uses polyethylene glycol-bridged hindered phenolic antioxidants, which can capture the active groups of PPR molecular chains and adhere to the surface of PPR pipe molecular chains, reducing the damage of free chlorine to PPR pipes. In addition, the polyethylene glycol molecular chain segments in the polyethylene glycol-bridged hindered phenolic antioxidants can form a hydrophilic protective layer, which will block the contact between active chlorine and the pipe, effectively improving the chlorine resistance of the pipe. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the PPR pipe described in this invention.

[0041] Figure 2 These are scanning electron microscope (SEM) images of the PPR tube. a and b are SEM images of the PPR tube before and after immersion in Example 1. c and d are SEM images of the PPR tube before and after immersion in Example 3. e and f are SEM images of the PPR tube before and after immersion in Comparative Example 9.

[0042] Figure 3 The image shows the infrared spectrum of the polyethylene glycol-bridged hindered phenolic antioxidant described in Example 1. Detailed Implementation

[0043] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the scope of protection and implementation of the present invention are not limited thereto.

[0044] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0045] Preparation Example 1

[0046] A method for preparing a polyethylene glycol-bridged hindered phenolic antioxidant includes the following steps:

[0047] 1g of polyethylene glycol (molecular weight 4500 g·mol⁻¹) -1Dissolve PEG4500 in 20 mL of chloroform and stir magnetically for 10 min to completely dissolve it. Under ice bath, magnetic stirring, and N2 environment, slowly add 30 mL of chloroform solution of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride (1.1873 g, 4.00 mmol) and 10 mL of chloroform solution of triethylamine (0.56 mL, 4.00 mmol) to the chloroform solution of PEG4500. After the addition is complete, stir for 30 min and slowly raise the temperature to 40 °C. React at this temperature for 24 h. After the reaction was completed, triethylamine and chloroform in the reaction mixture were removed by rotary evaporation at 60°C. A suitable amount of toluene was added, and the mixture was stirred to precipitate triethylamine hydrochloride. The precipitate was removed by vacuum filtration under reduced pressure. Then, most of the toluene was removed by rotary evaporation at 70°C. The remaining reaction mixture was slowly added dropwise to 100 mL of ice-cold diethyl ether while stirring vigorously. A white precipitate was precipitated. The precipitate was allowed to stand until it was completely precipitated. The solid obtained by vacuum filtration under reduced pressure was washed three times with 20 mL of ice-cold diethyl ether. The white solid obtained by filtration was dried under vacuum at 30°C for 12 h. The solid obtained was the target product, polyethylene glycol-bridged hindered phenolic antioxidant.

[0048] The infrared spectrum of polyethylene glycol-bridged hindered phenolic antioxidants is as follows: Figure 3 As shown, this invention successfully synthesizes a polyethylene glycol-bridged hindered phenolic antioxidant.

[0049] Preparation Example 2

[0050] The difference from Preparation Example 1 is that the molecular weight of the polyethylene glycol is 5000 g·mol⁻¹. -1 Everything else is the same as in Preparation Example 1.

[0051] Preparation Example 3

[0052] The difference from Preparation Example 1 is that the molecular weight of the polyethylene glycol is 6000 g·mol⁻¹. -1 Everything else is the same as in Preparation Example 1.

[0053] Preparation Example 4

[0054] The difference from Preparation Example 1 is that the molecular weight of the polyethylene glycol is 4000 g·mol⁻¹. -1 Everything else is the same as in Preparation Example 1.

[0055] Preparation Example 5

[0056] The difference from Preparation Example 1 is that the molecular weight of the polyethylene glycol is 6500 g·mol⁻¹. -1 Everything else is the same as in Preparation Example 1.

[0057] Example 1

[0058] This embodiment provides a chlorine-resistant PPR composite material, comprising the following components in parts by weight:

[0059] Random copolymer polypropylene 95 parts; chlorine resistant agent 2 parts; antioxidant 1 part; lubricant 2 parts;

[0060] The weight-average molecular weight of the random copolymer polypropylene is 66W; the melt flow rate of the random copolymer polypropylene at 230℃ and 2.16kg load is 0.27g / 10min. The grade of the random copolymer polypropylene is Borealis RA140e.

[0061] The chlorine-resistant agent is the polyethylene glycol-bridged hindered phenolic antioxidant prepared in Preparation Example 1, wherein the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant is 4500 g·mol⁻¹. -1 .

[0062] The antioxidant is a mixture of commercially available antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0063] The lubricant is white oil, purchased from Beijing Yinghaiqing Industrial Lubricating Oil Co., Ltd.

[0064] This embodiment also provides a method for preparing a chlorine-resistant PPR composite material, including the following steps:

[0065] Random copolymer polypropylene, chlorine resistant agent, antioxidant and lubricant are mixed evenly in proportion, dried and then melt-blended in a twin-screw extruder to obtain chlorine resistant PPR composite material. The temperature of the twin-screw extruder is 195-230℃ and the speed is 15-100r / min.

[0066] This embodiment also provides a PPR pipe with chlorine resistance. The PPR pipe includes a four-layer structure, such as... Figure 1 As shown, the PPR pipe includes, from the inside out, an anti-chlorine layer, a composite layer, a barrier layer, and a coloring layer.

[0067] The thickness of the chlorine-resistant layer is 1 mm, and the thicknesses of the composite layer, barrier layer, and coloring layer are 1 mm, 0.2 mm, and 1 mm, respectively.

[0068] The chlorine-resistant layer includes a chlorine-resistant PPR composite material.

[0069] The composite layer consists of PPR and glass fiber, with a mass ratio of 80:20 and a glass fiber length of 10 μm.

[0070] The coloring layer consists of PPR and color masterbatch, with a mass ratio of 100:2. The color masterbatch is grade SZ19281 and is manufactured by Chongqing Aocai New Material Co., Ltd.

[0071] The barrier layer consists of EVOH with a molecular weight of 8W and an ethylene content of 38%.

[0072] This embodiment also provides a method for preparing a PPR pipe with chlorine resistance, including the following steps:

[0073] (1) After drying the PPR and glass fiber in the composite layer, the PPR is fed through the main feed port and the glass fiber is fed through the side feed port, and they are melt-blended in a twin-screw extruder to obtain mixture A; the PPR and color masterbatch in the color layer are mixed evenly, dried, and then melt-blended in a twin-screw extruder to obtain mixture B; the temperature of the twin-screw extruder is 195-230℃ and the rotation speed is 15-100r / min;

[0074] (2) Chlorine-resistant PPR composite material, mixture A, ethylene-vinyl alcohol copolymer and mixture B are added to the feeding equipment in sequence and extruded through four single screw extruders. Then, four layers are co-extruded at the die head to obtain a heat pipe blank. Finally, the heat pipe blank is sized and cooled in a vacuum to obtain a PPR pipe with chlorine resistance. The temperature of the single screw extruder is 190-225℃ and the rotation speed is 30-120r / min.

[0075] Example 2

[0076] This embodiment provides a chlorine-resistant PPR composite material, comprising the following components in parts by weight:

[0077] Random copolymer polypropylene 95 parts; chlorine resistant agent 2 parts; antioxidant 1 part; lubricant 2 parts;

[0078] The weight-average molecular weight of the random copolymer polypropylene is 66W; the melt flow rate of the random copolymer polypropylene at 230℃ and 2.16kg load is 0.32g / 10min. The grade of the random copolymer polypropylene is Yanshan Petrochemical 4220.

[0079] The chlorine-resistant agent is the polyethylene glycol-bridged hindered phenolic antioxidant prepared in Preparation Example 2, wherein the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant is 5000 g·mol⁻¹. -1 .

[0080] The antioxidant is a mixture of commercially available antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0081] The lubricant is white oil, purchased from Beijing Yinghaiqing Industrial Lubricating Oil Co., Ltd.

[0082] This embodiment also provides a method for preparing a chlorine-resistant PPR composite material, including the following steps:

[0083] Random copolymer polypropylene, chlorine resistant agent, antioxidant and lubricant are mixed evenly in proportion, dried and then melt-blended in a twin-screw extruder to obtain chlorine resistant PPR composite material. The temperature of the twin-screw extruder is 195-230℃ and the speed is 15-100r / min.

[0084] This embodiment also provides a PPR pipe with chlorine resistance. The PPR pipe includes, from the inside out, an chlorine-resistant layer, a composite layer, a barrier layer, and a coloring layer.

[0085] The thickness of the chlorine-resistant layer is 1 mm, and the thicknesses of the composite layer, barrier layer, and coloring layer are 1 mm, 0.2 mm, and 1 mm, respectively.

[0086] The chlorine-resistant layer includes a chlorine-resistant PPR composite material.

[0087] The composite layer consists of PPR and glass fiber, with a mass ratio of 80:20 and a glass fiber length of 20 μm.

[0088] The coloring layer consists of PPR and color masterbatch, with a mass ratio of 100:2. The grade is SZ19281 and it is manufactured by Chongqing Aocai New Materials Co., Ltd.

[0089] The barrier layer consists of EVOH with a molecular weight of 13W and an ethylene content of 38%.

[0090] This embodiment also provides a method for preparing a PPR pipe with chlorine resistance, including the following steps:

[0091] (1) After drying the PPR and glass fiber in the composite layer, the PPR is fed through the main feed port and the glass fiber is fed through the side feed port, and they are melt-blended in a twin-screw extruder to obtain mixture A; the PPR and color masterbatch in the color layer are mixed evenly, dried, and then melt-blended in a twin-screw extruder to obtain mixture B; the temperature of the twin-screw extruder is 195-230℃ and the rotation speed is 15-100r / min;

[0092] (2) Chlorine-resistant PPR composite material, mixture A, ethylene-vinyl alcohol copolymer and mixture B are added to the feeding equipment in sequence and extruded through four single screw extruders. Then, four layers are co-extruded at the die head to obtain a heat pipe blank. Finally, the heat pipe blank is sized and cooled in a vacuum to obtain a PPR pipe with chlorine resistance. The temperature of the single screw extruder is 190-225℃ and the rotation speed is 30-120r / min.

[0093] Example 3

[0094] The only difference from Example 1 is that the chlorine-resistant agent is the polyethylene glycol-bridged hindered phenolic antioxidant prepared in Preparation Example 3, wherein the polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant has a molecular weight of 6000 g·mol⁻¹. -1 .

[0095] Example 4

[0096] The only difference from Example 1 is that the weight-average molecular weight of the random copolymer polypropylene is 64W.

[0097] Example 5

[0098] The only difference from Example 1 is that the weight-average molecular weight of the random copolymer polypropylene is 69W.

[0099] Example 6

[0100] The only difference from Example 1 is that the chlorine-resistant PPR composite material comprises the following components in parts by weight: 92 parts of random copolymer polypropylene; 3 parts of chlorine-resistant agent; 0.05 parts of antioxidant; and 2 parts of lubricant.

[0101] Comparative Example 1

[0102] The only difference from Example 1 is that polyethylene glycol-bridged hindered phenolic antioxidants are not added to the PPR composite material.

[0103] Comparative Example 2

[0104] The only difference from Example 1 is that an equal mass of antioxidant 1024 is used instead of polyethylene glycol-bridged hindered phenolic antioxidant.

[0105] Comparative Example 3

[0106] The only difference from Example 1 is that the chlorine-resistant agent is the polyethylene glycol-bridged hindered phenolic antioxidant prepared in Preparation Example 4, wherein the polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant has a molecular weight of 4000 g·mol⁻¹. -1 .

[0107] Comparative Example 4

[0108] The only difference from Example 1 is that the chlorine-resistant agent is the polyethylene glycol-bridged hindered phenolic antioxidant prepared in Preparation Example 5, wherein the polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant has a molecular weight of 6500 g·mol⁻¹. -1 .

[0109] Comparative Example 5

[0110] The only difference from Example 1 is that the weight-average molecular weight of the random copolymer polypropylene is 60W, and the grade of the random copolymer polypropylene is Dushanzi T4401.

[0111] Comparative Example 6

[0112] The only difference from Example 1 is that the weight-average molecular weight of the random copolymer polypropylene is 70W, and the grade of the random copolymer polypropylene is Daqing Petrochemical PA14D-1.

[0113] Comparative Example 7

[0114] The only difference from Example 1 is that the amount of chlorine-resistant agent used in the PPR composite material is 0.05 parts.

[0115] Comparative Example 8

[0116] The only difference from Example 1 is that the amount of chlorine-resistant agent used in the PPR composite material is 4 parts.

[0117] Comparative Example 9

[0118] The only difference from Example 1 is that an equal mass of polyethylene is used instead of polypropylene, and the polyethylene grade is POE8180 (Dow).

[0119] Performance testing

[0120] The PP pipes prepared in the above embodiments and comparative examples were subjected to the following performance tests:

[0121] The test method for the chlorine resistance of PPR pipes includes the following steps:

[0122] (1) Prepare tap water with high active chlorine content, seal both ends of the PPR pipe to prevent active chlorine leakage, and immerse the PPR pipe in a 40℃ insulated water tank.

[0123] (2) Samples were taken every ten days to test the oxidation induction time (OIT) and hydrostatic pressure resistance of the PPR pipe inside and outside, and to observe the changes in microstructure. The part of the pipe wall in contact with water was defined as the inner layer, and the part in contact with air was defined as the outer layer. The sample thickness was 650±100μm.

[0124] Oxidation induction time was tested according to GB / T19466.6-2009; hydrostatic test was tested according to GB / T6111 standard; microstructural changes were tested by scanning electron microscopy; after the pipe sample was immersed in liquid chlorine and then fractured, gold was sprayed on the fracture surface for 120s, and then the cross-sectional morphology was observed by scanning electron microscopy (SEM) with an accelerating voltage of 10kV.

[0125] The test results are shown in Table 1-2.

[0126] Table 1. Changes in oxidation induction time (OIT) (min) with aging time

[0127]

[0128]

[0129] Table 2. Hydrostatic Pressure of PPR Pipes

[0130]

[0131]

[0132] According to the comparison between Comparative Examples 1-2 and Example 1 in Table 1, it can be seen that Comparative Example 1 did not add polyethylene glycol-bridged hindered phenol antioxidant, and Comparative Example 2 used a common antichlorine agent to replace polyethylene glycol-bridged hindered phenol antioxidant. The antichlorine effect of Comparative Examples 1-2 was not as good as that of Example 1. This shows that by adding polyethylene glycol-bridged hindered phenol antioxidant as an antichlorine agent to PPR pipe, the present invention is beneficial to improving the antichlorine performance of PPR pipe.

[0133] According to the comparison between Comparative Examples 3-4 and Example 1 in Table 1, the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidants in Comparative Examples 3-4 is not within the range defined by the present invention, and the antichlorine effect in Comparative Examples 3-4 is not as good as that in Example 1. This shows that by controlling the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidants, the antichlorine performance of PPR pipes can be improved.

[0134] As shown in Table 2, the PPR pipe prepared in Example 1 burst after 12.5 hours of hydrostatic testing following a 10% pressurization after 180 days of anti-chlorine treatment. In contrast, Comparative Example 3 burst after 11.5 hours of hydrostatic testing following a 10% pressurization; and Comparative Example 4 burst after 2 hours of hydrostatic testing following a 10% pressurization after 90 days of anti-chlorine treatment. The hydrostatic test results of Comparative Examples 3 and 4 were all inferior to those of Example 1, indicating that by controlling the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenolic antioxidant within the range defined by this invention, the anti-chlorine performance of the PPR pipe can be improved.

[0135] According to the comparison between Comparative Examples 5-6 and Example 1 in Table 1, the molecular weight of polypropylene in Comparative Examples 5-6 is too small or too large, which affects the chlorine resistance of the PPR pipe. Furthermore, according to Table 2, the hydrostatic test results of Comparative Examples 5-6 are not as good as those of Example 1. This indicates that by controlling the molecular weight of polypropylene and compounding it with polyethylene glycol-bridged hindered phenolic antioxidant, the present invention is beneficial to improving the chlorine resistance of PPR composite materials.

[0136] According to the comparison between Comparative Examples 7-8 and Example 1 in Table 1, both insufficient and excessive amounts of polyethylene glycol-bridged hindered phenolic antioxidant in Comparative Examples 7-8 will affect the chlorine resistance of PPR pipes. Furthermore, according to Table 2, the hydrostatic test results of Comparative Examples 7-8 are not as good as those of Example 1. This indicates that only by controlling the amount of polyethylene glycol-bridged hindered phenolic antioxidant within the range defined by this invention can the chlorine resistance of PPR pipes be guaranteed not to decrease.

[0137] According to the comparison between Comparative Example 9 and Example 1 in Table 1, the use of polyethylene instead of polypropylene in Comparative Example 9 resulted in a decrease in the chlorine resistance of the PPR pipe. Furthermore, according to Table 2, the hydrostatic test results of Comparative Example 9 were not as good as those of Example 1, indicating that only by adding polyethylene glycol-bridged hindered phenolic antioxidant to polypropylene can the chlorine resistance of the PPR pipe be significantly improved.

[0138] As can be seen from Examples 1-6 in Table 1, the present invention uses polypropylene of a specific molecular weight and a specific polyethylene glycol-bridged hindered phenolic antioxidant, which is beneficial to improving the chlorine resistance of PPR pipes.

[0139] according to Figure 2 It is evident that scanning electron microscopy (SEM) was used to assess the degree of degradation of PPR pipe samples exposed to free chlorine. SEM provides magnified images of the sample surface, allowing observation of surface defects such as microcracks. A light, glossy layer forms on the surface of samples immersed in a chlorine-containing solution. SEM images of the inner surfaces of PPR pipe samples that were not immersed in chlorine solution and those that underwent 180-day chlorine immersion are shown.

[0140] like Figure 2 As shown in Figure af, the roughness of the inner surface of the resin increases due to the corrosion of the inner surface by free chlorine. Figure 2 Images a, c, and e show photographs of the inner surface of the PPR pipe before aging; no cracks are observed, and the inner surface is smooth. Conversely, Figure 2 The changes in the inner surface of PPR pipes exposed to free chlorine (types b, d, and f) for 180 days are shown. It is evident that the inner surface of the PPR pipe using polyethylene instead of polypropylene is rough and exhibits obvious cracks. This indicates that adding polyethylene glycol-bridged hindered phenolic antioxidants to any material does not necessarily achieve the effects of this invention. Figure 2 It is known that the polyethylene glycol-bridged hindered phenolic antioxidant described in this invention has the ability to withstand free chloride ions and has a good protective effect on polypropylene materials (PPR) at high chloride concentrations.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A PPR composite material having resistance to chlorine, characterized in that, The composition comprises the following components by weight: random copolymerized polypropylene 92-97 parts; anti-chlorine agent 0.1-3 parts; antioxidant 0.05-1 part; lubricant 0.5-2 parts; The anti-chlorine agent is a polyethylene glycol bridged hindered phenol antioxidant, wherein the molecular weight of the polyethylene glycol in the polyethylene glycol bridged hindered phenol antioxidant is 4500-6000 g·mol -1 ; the weight average molecular weight of the random copolymerized polypropylene is 64-69 W.

2. The PPR composite material with anti-chlorine performance according to claim 1, characterized in that, The random copolymerized polypropylene has a melt flow rate of 0.27-0.32 g / 10 min at 230 ℃ under a load of 2.16 kg.

3. The PPR composite material with anti-chlorine performance according to claim 1, characterized in that, The antioxidant comprises hindered amine antioxidant and phosphite antioxidant.

4. The PPR composite material with anti-chlorine performance according to claim 3, characterized in that, The hindered amine antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1330. The phosphite antioxidant is at least one of antioxidant 168 and antioxidant 626.

5. The PPR composite material with anti-chlorine performance according to claim 1, wherein, The lubricant comprises at least one of white oil, calcium stearate, and ethylene bis-stearamide.

6. The PPR composite material having resistance to chlorine according to claim 1, wherein, The preparation method of the polyethylene glycol bridged hindered phenol antioxidant comprises the following steps: (1) dissolving polyethylene glycol in chloroform, stirring uniformly, adding β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride and triethylamine dropwise under an inert atmosphere, reacting at 40-45 ℃ for 20-24 h to obtain a mixture; (2) after the reaction is completed, removing triethylamine and chloroform in the mixture, then adding ice ethyl ether dropwise, stirring to precipitate, standing, suction filtration, washing, and drying to obtain the polyethylene glycol bridged hindered phenol antioxidant.

7. The method of producing a PPR composite material having resistance to chlorine according to any one of claims 1 to 6, wherein The method comprises the following steps: mixing the random copolymerized polypropylene, the anti-chlorine agent, the antioxidant, and the lubricant uniformly in proportion, drying, and then melt blending in an extruder to obtain the anti-chlorine PPR composite material.

8. A PPR pipe having resistance to chlorine, characterized by, The PPR pipe comprises an anti-chlorine layer, and the anti-chlorine layer comprises the anti-chlorine PPR composite material according to any one of claims 1-6.

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