PPR (polypropylene random copolymer) composite material with chlorine resistance as well as preparation method and application of PPR composite material

Abstract

The invention discloses a PPR composite material with chlorine resistance as well as a preparation method and application thereof, and relates to the technical field of polypropylene materials. The chlorine-resistant PPR composite material comprises the following components in parts by weight: 92-97 parts of polypropylene random copolymer; 0.1 to 3 parts of an anti-chlorine agent; 0.05 to 1 part of an antioxidant; 0.5-2 parts of a lubricant; the anti-chlorine agent is a polyethylene glycol bridged hindered phenol antioxidant, and the molecular weight of polyethylene glycol in the polyethylene glycol bridged hindered phenol antioxidant is 4500-6000 g.mol <-1 >; and the weight-average molecular weight of the polypropylene random copolymer is 64-69W. The PPR composite material has excellent chlorine resistance, and when the PPR composite material is added into a PPR pipe, the PPR pipe can have excellent migration resistance.

Description

Technical Field

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

[0002] Polypropylene materials are widely used in various industries due to their high cost performance. However, most polypropylenes contain unsaturated bonds or groups such as carbonyl and hydroxyl groups, which are easily affected by external factors during processing and use, resulting in the breakage, cross-linking, and detachment of polymer chains, and the material shows aging phenomena such as hardening, sticking, powdering, cracking, yellowing, and poor transparency, greatly shortening the service life. Therefore, in order to extend the service life of polypropylene materials and enhance various properties of the materials during processing and use, antioxidants are usually added to the materials to inhibit or delay the occurrence of oxidation reactions. Without changing the material production process, antioxidants present at a lower concentration can inhibit the oxidation of polypropylene. Generally speaking, commonly used antioxidant phenolic antioxidants, phosphite antioxidants, thioester (ether) antioxidants, etc.

[0003] Currently in the field of pipelines, with the trend of replacing steel with plastic, the proportion of plastic pipes in drinking water pipes is increasing. To ensure the stability of product quality, the industrial community has put forward the concept of a 50-year long-term life in formulating standards, which has also promoted the rapid recognition of plastic pipes in the market. However, some plastic pipes for transporting drinking water containing chlorine disinfectant have shown premature damage, mainly because active chlorine causes premature loss of traditional antioxidants 1010 and 168, making it difficult to achieve the protection effect. Therefore, it is of great significance to develop a PPR drinking water pipe that meets the chlorine resistance requirements. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a PPR composite material with chlorine resistance, its preparation method and application. The PPR composite material of the present invention has excellent chlorine resistance. When added to a PPR pipe, it can make the PPR pipe have excellent migration resistance.

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

[0006] In the 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 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 64-69W.

[0009] In the present invention, due to the excellent migration resistance of the polyethylene glycol bridged hindered phenol antioxidant, adding it as an anti-chlorine agent to the PPR pipe can effectively solve the situation that the antioxidant detaches due to the long-term scouring of the water inlet pipe; moreover, the polyethylene glycol molecular chain segment in the polyethylene glycol bridged hindered phenol antioxidant can form a hydrophilic protective layer, which will block the contact between the active chlorine and the pipe, effectively improving the anti-chlorine performance of the pipe. At the same time, by controlling the molecular weight of the polyethylene glycol in the polyethylene glycol bridged hindered phenol antioxidant within the above range in the present invention, it is beneficial to further improve the migration resistance of the composite material.

[0010] The present invention uses polypropylene with a specific molecular weight and polyethylene glycol bridged hindered phenol antioxidant in combination, which is beneficial to improving the anti-chlorine performance of the PPR composite material. And by controlling the molecular weight of the polypropylene within the above range in the present invention, the processing performance and heat-resistant processing stability of the PPR composite material are not easily affected.

[0011] Preferably, the molecular weight of the polyethylene glycol in the polyethylene glycol bridged hindered phenol antioxidant is 4500 g·mol -1 、5000 g·mol -1 、5500 g·mol -1 、6000 g·mol -1 or any range value of one or both of them.

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

[0013] More preferably, the melt flow rate of the random copolymerized polypropylene at 230 °C under a load of 2.16 kg is any range value 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, 0.32 g / 10 min.

[0014] The test standard for the melt flow rate of the random copolymerized polypropylene is GBT3682-2000.

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

[0016] More preferably, 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.

[0017] Preferably, the lubricant includes at least one of white oil, calcium stearate, and ethylene bisstearamide (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 phenol antioxidant includes the following steps:

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

[0020] (2) After the reaction is completed, remove triethylamine and chloroform from the mixture, then dropwise add ice ether, stir to precipitate a solid, and after standing, filtering, washing, and drying, the polyethylene glycol bridged hindered phenol antioxidant is obtained.

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

[0022] Preferably, in the 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] In a second aspect, the present invention also provides a preparation method of a chlorine-resistant PPR composite material, including the following steps:

[0024] Mix random copolymer polypropylene, a chlorine-resistant agent, an antioxidant, and a lubricant in proportion and evenly, dry them, and then melt-blend them in an extruder to obtain the chlorine-resistant PPR composite material.

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

[0026] In a third aspect, the present invention also provides a PPR pipe with chlorine-resistant performance. The PPR pipe includes a chlorine-resistant layer, and the chlorine-resistant layer includes the chlorine-resistant PPR composite material.

[0027] Preferably, the PPR pipe further includes a composite layer, a barrier layer, and a coloring layer sequentially arranged on 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 color layer is 1-3 mm.

[0029] Preferably, the composite layer comprises PPR and glass fiber, and 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 color layer comprises PPR and masterbatch, and the mass ratio of PPR to masterbatch is 100:(1-2).

[0032] Preferably, the barrier layer comprises ethylene-vinyl alcohol copolymer (EVOH), wherein the ethylene content in the ethylene-vinyl alcohol copolymer is 38%, and the molecular weight of the ethylene-vinyl alcohol copolymer is 80,000-130,000.

[0033] Fourthly, the present invention also provides a preparation method of a PPR pipe with chlorine-resistant performance, comprising the following steps:

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

[0035] (2) Add the chlorine-resistant PPR composite material, mixture A, ethylene-vinyl alcohol copolymer, and mixture B to the feeding equipment in sequence, extrude them respectively through four single-screw extruders, then perform four-layer co-extrusion at the head to obtain a hot pipe blank, and finally subject the hot pipe blank to sizing and cooling in a vacuum to obtain a PPR pipe with chlorine-resistant performance.

[0036] Preferably, the temperature of the single-screw extruder in step (2) is 190-225 °C, and the rotation speed is 30-120 r / 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 of the present invention has excellent migration resistance as a chlorine-resistant agent. Adding it to the PPR pipe can effectively solve the problem that the antioxidant detaches due to the long-term scouring of the water inlet pipe.

[0039] (2) The present invention adopts a polyethylene glycol bridged hindered phenol antioxidant, which can capture the active groups of the PPR molecular chain and attach to the surface of the PPR pipe molecular chain, reducing the damage of free chlorine to the PPR pipe. In addition, the polyethylene glycol molecular chain segment in the polyethylene glycol bridged hindered phenol antioxidant 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic structural diagram of the PPR pipe described in the present invention.

[0041] Figure 2 is a scanning electron microscope image of the PPR pipe. a and b are the scanning electron microscope images of the PPR pipe described in Example 1 before and after soaking, c and d are the scanning electron microscope images of the PPR pipe described in Example 3 before and after soaking, and e and f are the scanning electron microscope images of the PPR pipe described in Comparative Example 9 before and after soaking.

[0042] Figure 3 is an infrared spectrum diagram of the polyethylene glycol bridged hindered phenol antioxidant described in Preparation Example 1. DETAILED DESCRIPTION OF THE INVENTION

[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 protection scope and implementation manner of the present invention are not limited thereto.

[0044] The materials, reagents, etc. used in the following examples are commercially available reagents and materials without special instructions.

[0045] Preparation Example 1

[0046] A preparation method of a polyethylene glycol bridged hindered phenol antioxidant includes the following steps:

[0047] Dissolve 1 g of polyethylene glycol (molecular weight 4500 g·mol -1 ) in 20 mL of chloroform, stir magnetically for 10 min to completely dissolve PEG4500, and under ice bath, magnetic stirring, N 2Under the environment, a chloroform solution of 30 mL of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride (1.1873 g, 4.00 mmol) and a chloroform solution of 10 mL of triethylamine (0.56 mL, 4.00 mmol) were simultaneously and slowly added dropwise to a chloroform solution of PEG4500. After the addition was completed, the mixture was stirred for 30 min, and then slowly heated to 40 °C and reacted at a constant temperature for 24 h at this temperature. After the reaction was completed, triethylamine and chloroform in the reaction mixture were removed by rotary evaporation at 60 °C; an appropriate amount of toluene was added, and the mixture was stirred to precipitate triethylamine hydrochloride precipitate, which was removed by suction filtration under reduced pressure; then most of the toluene was removed by rotary evaporation at 70 °C, and the remaining reaction mixture was slowly added dropwise to 100 mL of ice-cold diethyl ether while stirring vigorously to precipitate a white precipitate. After standing until the precipitation was complete, the solid obtained by suction filtration under reduced pressure was washed 3 times with 20 mL of ice-cold diethyl ether, and the white solid obtained by filtration was placed in a vacuum dryer at 30 °C for 12 h. The resulting solid was the target product, polyethylene glycol-bridged hindered phenol antioxidant.

[0048] The infrared spectrum of the polyethylene glycol-bridged hindered phenol antioxidant is as Figure 3 shown. It can be seen that the polyethylene glycol-bridged hindered phenol antioxidant was successfully synthesized in this invention.

[0049] Preparation Example 2

[0050] The difference from Preparation Example 1 is that the molecular weight of polyethylene glycol is 5000 g·mol -1 , and the others are the same as Preparation Example 1.

[0051] Preparation Example 3

[0052] The difference from Preparation Example 1 is that the molecular weight of polyethylene glycol is 6000 g·mol -1 , and the others are the same as Preparation Example 1.

[0053] Preparation Example 4

[0054] The difference from Preparation Example 1 is that the molecular weight of polyethylene glycol is 4000 g·mol -1 , and the others are the same as Preparation Example 1.

[0055] Preparation Example 5

[0056] The difference from Preparation Example 1 is that the molecular weight of polyethylene glycol is 6500 g·mol -1 , and the others are the same as Preparation Example 1.

[0057] Example 1

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

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

[0060] The weight-average molecular weight of the random copolymer polypropylene is 660,000; the melt flow rate of the random copolymer polypropylene under a load of 2.16 kg at 230 °C is 0.27 g / 10 min. The grade of the random copolymer polypropylene is Borealis RA140e.

[0061] The chlorine-resistant agent is the polyethylene glycol-bridged hindered phenol antioxidant prepared in Preparation Example 1. Among them, the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenol antioxidant is 4500 g·mol -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 example also provides a method for preparing a chlorine-resistant PPR composite material, including the following steps:

[0065] Mix the random copolymer polypropylene, chlorine-resistant agent, antioxidant and lubricant evenly in proportion, dry them, and then melt-blend them in a twin-screw extruder to obtain the chlorine-resistant PPR composite material. The temperature of the twin-screw extruder is 195 - 230 °C, and the rotation speed is 15 - 100 r / min.

[0066] This example also provides a PPR pipe with chlorine-resistant performance. The PPR pipe includes a four-layer structure, as Figure 1 shown. The PPR pipe includes a chlorine-resistant layer, a composite layer, a barrier layer, and a coloring layer arranged in sequence from the inside to the outside.

[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 the chlorine-resistant PPR composite material.

[0069] The composite layer includes PPR and glass fiber. The mass ratio of PPR to glass fiber is 80:20, and the length of the glass fiber is 10 μm.

[0070] The coloring layer includes PPR and masterbatch. The mass ratio of PPR to masterbatch is 100:2, and the grade of the masterbatch is SZ19281, Chongqing Aocai New Materials Co., Ltd.

[0071] The barrier layer includes EVOH with a molecular weight of 80,000 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 coloring 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 °C, and the rotation speed is 15 - 100 r / min;

[0074] (2) The chlorine-resistant PPR composite material, mixture A, ethylene-vinyl alcohol copolymer, and mixture B are sequentially added to the feeding equipment, extruded through four single-screw extruders respectively, and then four-layer co-extrusion is carried out at the die head to obtain a hot pipe blank. Finally, the hot 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 °C, and the rotation speed is 30 - 120 r / min.

[0075] Example 2

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

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

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

[0079] The chlorine-resistant agent is the polyethylene glycol-bridged hindered phenol antioxidant prepared in Preparation Example 2, wherein the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenol antioxidant is 5000 g·mol -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] Mix random copolymer polypropylene, chlorine-resistant agent, antioxidant and lubricant evenly in proportion, dry them, and then melt-blend them in a twin-screw extruder to obtain a chlorine-resistant PPR composite material. The temperature of the twin-screw extruder is 195 - 230 °C, and the rotation speed is 15 - 100 r / min.

[0084] This embodiment also provides a PPR pipe with chlorine-resistant performance. The PPR pipe includes a chlorine-resistant layer, a composite layer, a barrier layer, and a coloring layer arranged in sequence from inside to outside.

[0085] The thickness of the chlorine-resistant layer is 1 mm, and the thicknesses of the composite layer, the barrier layer, and the 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 includes PPR and glass fiber. The mass ratio of PPR to glass fiber is 80:20, and the length of the glass fiber is 20 μm.

[0088] The coloring layer includes PPR and masterbatch. The mass ratio of PPR to masterbatch is 100:2, with the brand number SZ19281, Chongqing Aocai New Materials Co., Ltd.

[0089] The barrier layer includes EVOH with a molecular weight of 130,000 and an ethylene content of 38%.

[0090] This embodiment also provides a preparation method of a PPR pipe with chlorine-resistant performance, including the following steps:

[0091] (1) After drying the PPR and glass fiber in the composite layer, the PPR is fed through the main feeding port, and the glass fiber is fed through the side feeding port, and melt-blended in a twin-screw extruder to obtain mixture A; mix the PPR and masterbatch in the coloring layer evenly, dry them, and then melt-blend them in a twin-screw extruder to obtain mixture B; the temperature of the twin-screw extruder is 195 - 230 °C, and the rotation speed is 15 - 100 r / min;

[0092] (2) Add the chlorine-resistant PPR composite material, mixture A, ethylene-vinyl alcohol copolymer, and mixture B to the feeding equipment in sequence, extrude them through four single-screw extruders respectively, and then perform four-layer co-extrusion at the die head to obtain a hot pipe blank. Finally, subject the hot pipe blank to sizing and cooling in a vacuum to obtain a PPR pipe with chlorine-resistant performance; the temperature of the single-screw extruder is 190 - 225 °C, and the rotation speed is 30 - 120 r / min.

[0093] Example 3

[0094] It is only different from Example 1 in that the anti-chlorine agent is the polyethylene glycol-bridged hindered phenol antioxidant prepared in Preparation Example 3, wherein the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenol antioxidant is 6000 g·mol -1 .

[0095] Example 4

[0096] It is only different from Example 1 in that the weight-average molecular weight of the random copolymerized polypropylene is 64W.

[0097] Example 5

[0098] It is only different from Example 1 in that the weight-average molecular weight of the random copolymerized polypropylene is 69W.

[0099] Example 6

[0100] It is only different from Example 1 in that the anti-chlorine PPR composite material comprises the following components in parts by weight: 92 parts of random copolymerized polypropylene; 3 parts of anti-chlorine agent; 0.05 part of antioxidant; 2 parts of lubricant.

[0101] Comparative Example 1

[0102] It is only different from Example 1 in that the polyethylene glycol-bridged hindered phenol antioxidant is not added to the PPR composite material.

[0103] Comparative Example 2

[0104] It is only different from Example 1 in that an equal mass of antioxidant 1024 is used to replace the polyethylene glycol-bridged hindered phenol antioxidant.

[0105] Comparative Example 3

[0106] It is only different from Example 1 in that the anti-chlorine agent is the polyethylene glycol-bridged hindered phenol antioxidant prepared in Preparation Example 4, wherein the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenol antioxidant is 4000 g·mol -1 .

[0107] Comparative Example 4

[0108] It is only different from Example 1 in that the anti-chlorine agent is the polyethylene glycol-bridged hindered phenol antioxidant prepared in Preparation Example 5, wherein the molecular weight of polyethylene glycol in the polyethylene glycol-bridged hindered phenol antioxidant is 6500 g·mol -1 .

[0109] Comparative Example 5

[0110] It is only different from Example 1 in that the weight-average molecular weight of the random copolymerized polypropylene is 60W, and the grade of the random copolymerized polypropylene is Dushanzi T4401.

[0111] Comparative Example 6

[0112] The difference from Example 1 is only that the weight-average molecular weight of the random copolymerized polypropylene is 700,000, and the grade of the random copolymerized polypropylene is Daqing Refining & Chemical PA14D-1.

[0113] Comparative Example 7

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

[0115] Comparative Example 8

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

[0117] Comparative Example 9

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

[0119] Performance Testing

[0120] The following performance tests were respectively carried out on the PPR pipes prepared in the above examples and comparative examples:

[0121] The test method for the anti-chlorine performance of the PPR pipe includes the following steps:

[0122] (1) Prepare tap water with a high content of active chlorine, block both ends of the PPR pipe to prevent the leakage of active chlorine, and immerse the PPR pipe in a 40°C heat preservation water tank;

[0123] (2) Take samples every ten days, test the oxidation induction time OIT inside and outside the PPR pipe and the change of the hydrostatic pressure resistance of the PPR pipe, and observe the change of the microstructure. The part of the inner wall of the pipe in contact with water is defined as the inner layer, and the part in contact with air is defined as the outer layer. The sampling thickness is 650 ± 100 μm.

[0124] The oxidation induction time was tested in accordance with GB / T19466.6-2009; the hydrostatic test was tested in accordance with the GB / T6111 standard; the change of the microstructure was tested by a scanning electron microscope; after the pipe sample was immersed in liquid chlorine and brittle fractured, the fracture surface was sputtered with gold for 120 s, and then the cross-sectional morphology was observed by scanning with an electron microscope (SEM) at an accelerating voltage of 10 kV.

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

[0126] Table 1 Change of oxidation induction time OIT (min) with aging time

[0127]

[0128]

[0129] Table 2 Hydrostatic pressure of PPR pipes

[0130]

[0131]

[0132] It can be obtained by comparing Comparative Examples 1-2 with Example 1 in Table 1 that in Comparative Example 1, no polyethylene glycol bridged hindered phenol antioxidant is added, and in Comparative Example 2, a common anti-chlorine agent is used to replace the polyethylene glycol bridged hindered phenol antioxidant. The anti-chlorine effects of Comparative Examples 1-2 are both inferior to that of Example 1, indicating that by adding the polyethylene glycol bridged hindered phenol antioxidant as an anti-chlorine agent to the PPR pipe, it is beneficial to improve the anti-chlorine performance of the PPR pipe.

[0133] It can be obtained by comparing Comparative Examples 3-4 with Example 1 in Table 1 that the molecular weights of polyethylene glycol in the polyethylene glycol bridged hindered phenol antioxidants in Comparative Examples 3-4 are not within the range defined in the present invention. The anti-chlorine effects of Comparative Examples 3-4 are both inferior to that of Example 1, indicating that by controlling the molecular weight of polyethylene glycol in the polyethylene glycol bridged hindered phenol antioxidant, the anti-chlorine performance of the PPR pipe can be improved.

[0134] According to Table 2, after 180 days of anti-chlorine treatment, the PPR pipe prepared in Example 1 burst after 12.5 h under a 10% pressure increase during the hydrostatic test. While in Comparative Example 3, it burst after 11.5 h under a 10% pressure increase during the hydrostatic test; in Comparative Example 4, after 90 days of anti-chlorine treatment, it burst after 2 h under a 10% pressure increase during the hydrostatic test. The hydrostatic test effects of Comparative Examples 3-4 are both inferior to that of Example 1, indicating that by controlling the molecular weight of polyethylene glycol in the polyethylene glycol bridged hindered phenol antioxidant within the range defined in the present invention, the anti-chlorine performance of the PPR pipe can be improved.

[0135] It can be obtained by comparing Comparative Examples 5-6 with Example 1 in Table 1 that the molecular weight of polypropylene in Comparative Examples 5-6 is too small or too large, and the anti-chlorine performance of the PPR pipe is affected. Moreover, according to Table 2, the hydrostatic test effects of Comparative Examples 5-6 are both inferior to that of Example 1, indicating that by controlling the molecular weight of polypropylene and compounding it with the polyethylene glycol bridged hindered phenol antioxidant, it is beneficial to improve the anti-chlorine performance of the PPR composite material.

[0136] Comparing Comparative Examples 7 - 8 with Example 1 in Table 1 respectively, it can be seen that too little or too much amount of polyethylene glycol - bridged hindered phenol antioxidant in Comparative Examples 7 - 8 will affect the chlorine resistance of PPR pipes. And, according to Table 2, the hydrostatic test results of Comparative Examples 7 - 8 are not as good as those of Example 1, indicating that only by controlling the amount of polyethylene glycol - bridged hindered phenol antioxidant within the range defined in the present invention can the chlorine resistance of PPR pipes be ensured not to decline.

[0137] Comparing Comparative Example 9 with Example 1 in Table 1, it can be obtained that when polyethylene is used to replace polypropylene in Comparative Example 9, the chlorine resistance of PPR pipes decreases. And, according to Table 2, the hydrostatic test effect of Comparative Example 9 is not as good as that of Example 1, indicating that only by adding polyethylene glycol - bridged hindered phenol antioxidant to polypropylene can the chlorine resistance of PPR pipes be greatly improved.

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

[0139] According to Figure 2 it can be known that a scanning electron microscope (SEM) is used to evaluate the degradation degree of PPR pipe samples exposed to a free - chlorine environment. The scanning electron microscope provides a magnified view of the sample surface and can observe surface defects such as microcracks. A light - colored layer is formed on the surface area of the sample immersed in the chlorine - containing solution. Scanning electron microscope (SEM) images of the inner surface of PPR pipe samples without chlorine - solution immersion and after 180 - day chlorine - solution immersion are shown.

[0140] As Figure 2 shown in a - f, due to the corrosion of the inner surface of the resin by free chlorine, the inner - surface roughness increases. Figure 2 a, c, e show the photos of the inner surface of the PPR pipe before aging, with no crack phenomenon and a smooth inner surface. On the contrary, Figure 2 b, d, f show the changes in the inner surface of the PPR pipe after being exposed to a free - chlorine environment. After 180 - day immersion, it can be seen that the inner surface of the PPR pipe using polyethylene to replace polypropylene is rough and obvious cracks appear. This indicates that adding the polyethylene glycol - bridged hindered phenol antioxidant to any material cannot achieve the effect of the present invention. Through Figure 2 it can be known that the polyethylene glycol - bridged hindered phenol antioxidant described in the present invention has the ability to withstand free chloride ions and has a good protective effect on polypropylene - based PPR materials at a relatively high chlorine concentration.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A PPR composite material with chlorine resistance, characterized in that: The composition comprises the following components in parts by weight: Random copolymer polypropylene 92-97 parts; anti-chlorine agent 0.1-3 parts; antioxidant 0.05-1 parts; 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 copolymer polypropylene is 64-69W.

2. The PPR composite material with chlorine resistance according to claim 1, characterized in that: The random copolymer polypropylene has a melt flow rate of 0.27-0.32 g / 10 min at 230° C. and a load of 2.16 kg.

3. The PPR composite material with chlorine resistance according to claim 1, characterized in that: The antioxidants include hindered amine antioxidants and phosphite antioxidants.

4. The PPR composite material with chlorine resistance according to claim 3, characterized in that: The hindered amine antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1330; And / or, the phosphite antioxidant is at least one of antioxidant 168 and antioxidant 626.

5. The PPR composite material with chlorine resistance according to claim 1, characterized in that: The lubricant includes at least one of white oil, calcium stearate, and ethylene bisstearamide.

6. The PPR composite material with chlorine resistance according to claim 1, characterized in that: The preparation method of the polyethylene glycol bridged hindered phenol antioxidant comprises the following steps: (1) dissolving polyethylene glycol in chloroform, stirring evenly, adding β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride and triethylamine dropwise under an inert atmosphere, reacting at 40-45° C. for 20-24 hours to obtain a mixture; (2) After the reaction is completed, triethylamine and chloroform are removed from the mixture, and then glacial ether is added dropwise, stirred to precipitate, and the precipitate is allowed to stand, filtered, washed, and dried to obtain a polyethylene glycol-bridged hindered phenol antioxidant.

7. The method for preparing the PPR composite material with chlorine resistance according to any one of claims 1 to 6, characterized in that: The following steps are involved: The random copolymer polypropylene, the chlorine-resistant agent, the antioxidant and the lubricant are uniformly mixed in proportion, dried and melt-blended in an extruder to obtain the chlorine-resistant PPR composite material.

8. A PPR pipe with chlorine resistance, characterized in that: The PPR pipe comprises a chlorine-resistant layer, and the chlorine-resistant layer comprises the chlorine-resistant PPR composite material according to any one of claims 1 to 6.

9. The chlorine-resistant PPR pipe according to claim 8, characterized in that: The PPR pipe also includes a composite layer, a barrier layer, and a coloring layer which are sequentially arranged on the periphery of the chlorine-resistant layer. The composite layer includes PPR and glass fiber; the coloring layer includes PPR and masterbatch; and the barrier layer includes ethylene-vinyl alcohol copolymer.

10. The method for preparing a PPR pipe with chlorine resistance according to claim 9, characterized in that: The following steps are involved: (1) The PPR and glass fiber in the composite layer are mixed evenly to obtain a mixture A; the PPR and the masterbatch in the coloring layer are mixed evenly to obtain a mixture B; (2) The chlorine-resistant PPR composite material, mixed material A, ethylene-vinyl alcohol copolymer, and mixed material B are sequentially added to a feeding device, extruded through four single-screw extruders, and then four-layer co-extruded at the die head to obtain a hot tube billet. Finally, the hot tube billet is sized and cooled in a vacuum to obtain a PPR tube with chlorine resistance.

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