Chlorine-resistant material, chlorine-resistant PP-R pipe and preparation method thereof

Abstract

The invention discloses a chlorine-resistant material, a chlorine-resistant PP-R pipeline and a preparation method thereof, and belongs to the technical field of polymer pipes; the chlorine-resistant material provided by the invention comprises the following raw materials in parts by mass: 1-5 parts of diatomaceous earth, 1-4 parts of imidazole ester skeleton, 0.2-0.5 parts of coupling agent, and 1.2-1.8 parts of antioxidant. The chlorine-resistant material provided by the invention has an excellent effect of chlorine adsorption. When it is added to the preparation of the PP-R pipeline, the tolerance of the PP-R pipeline to chloride ions can be improved, thereby extending the service life of the PP-R pipeline; and the preparation method of the chlorine-resistant material and the chlorine-resistant PP-R pipeline provided by the invention is simple to operate, and the raw materials are easily available, which is conducive to actual production.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer pipes, and in particular relates to a chlorine-resistant material, a chlorine-resistant PP-R pipe and a preparation method thereof. Background Art

[0002] PP-R pipe is the abbreviation of random copolymer polypropylene pipe, which is a random copolymer formed by the copolymerization of propylene and another olefin monomer; the molecular structure of polypropylene is changed due to the irregular distribution of its copolymer monomer and polypropylene chain, thus forming the excellent physical and chemical properties of this pipe. Due to its light weight, corrosion resistance, smooth inner wall without scaling, simple construction and maintenance, and long service life, it is widely used in building water supply and drainage, urban and rural drainage, municipal administration and other fields, and has quickly gained market recognition. In the actual water supply process, some PP-R pipes have been damaged prematurely. Foreign academic studies have found that chlorine-containing disinfectants in drinking water have strong oxidizing properties. When the pipe is in the process of long-term transportation of drinking water, it will cause the antioxidant in the plastic pipe to be consumed prematurely, causing the pipe to fail before reaching its expected life.

[0003] There are tertiary carbon atoms in the structure of polypropylene, and its antioxidant and aging resistance are worse than those of polyethylene. With the continuous promotion and application of PP-R pipes in water supply systems in buildings, there is an urgent need for a chlorine-resistant PP-R pipe to ensure the safe and stable operation of the pipeline system under the actual working conditions of chlorine-containing disinfectants in tap water, improve the chlorine resistance of the original PP-R pipeline system, and at the same time, the pipeline is safe and harmless, easy to produce and manufacture, and has stable performance. Summary of the invention

[0004] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a chlorine-resistant material, a chlorine-resistant PP-R pipe and a preparation method thereof having good chlorine resistance, oxidation resistance and excellent mechanical properties.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: a chlorine-resistant material, which includes the following raw materials in parts by weight: 1-5 parts of diatomaceous earth, 1-4 parts of imidazole ester skeleton, 0.2-0.5 parts of coupling agent, and 1.2-1.8 parts of antioxidant.

[0006] The chlorine-resistant material provided by the present invention has excellent oxidation resistance and good chlorine adsorption effect. When it is added into the preparation of PP-R pipes, the oxidation resistance and tolerance to chloride ions of the PP-R pipes can be improved, thereby extending the service life of the PP-R pipes.

[0007] Specifically, in the first aspect, the antioxidant in the chlorine-resistant material provided by the present invention can be stably and long-term combined in the chemically bonded diatomite and imidazolate skeleton, and can be stably, effectively and long-term released, thereby exerting its antioxidant effect, preventing the free chloride ions from oxidizing the PP-R material in the PP-R pipe, and playing a barrier and protective role on the PP-R resin; and because the antioxidant can form a stable chemical connection with the chemically bonded diatomite and imidazolate skeleton, it can also prevent the antioxidant from migrating to the liquid due to the flushing of the liquid in the pipe during the subsequent addition to the PP-R pipe preparation, resulting in a decrease in the content, thereby reducing the antioxidant effect and reducing the ability to adsorb and eliminate chloride ions. In the second aspect, the chlorine-resistant material provided by the present invention has a porous structure. In the actual preparation of the PP-R pipe and the subsequent use process, the chlorine-resistant material can also adsorb chloride ions, and eliminate the adsorbed chloride ions through the antioxidant inside the chlorine-resistant material, which more effectively avoids the accelerated aging of the PP-R pipe by chloride ions. On the third aspect, the chlorine-resistant material provided by the present invention also includes a coupling agent, which can not only effectively couple diatomaceous earth, imidazolate skeleton and antioxidant, but also the surface coating formed by the coupling agent can effectively reduce the surface energy of the chlorine-resistant material, so that when it is subsequently applied to PP-R pipes, it has excellent compatibility with PP-R resin, can be evenly dispersed in the PP-R pipes, and improve the mechanical properties of the PP-R pipes.

[0008] As a preferred embodiment of the chlorine-resistant material of the present invention, the synthesis method of the imidazole ester skeleton comprises the following steps: adding a 2-methylimidazole aqueous solution dropwise to a zinc nitrate hexahydrate aqueous solution under stirring and continuing stirring to obtain a milky white suspension, followed by centrifugation, collecting the solid, washing, and drying to obtain the imidazole ester skeleton;

[0009] The molar ratio of the zinc nitrate hexahydrate to 2-methylimidazole is 1:(50-70).

[0010] Exemplarily, the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole may be any point value or any range value between 1:(50-70), such as 1:50, 1:55, 1:60, 1:65, 1:70, etc.

[0011] The present invention has found that when the synthesis method of the imidazolate skeleton in the chlorine-resistant material is further selected to adopt the above method, and the molar ratio of zinc nitrate hexahydrate and 2-methylimidazole in the raw material is within the above range, when the obtained chlorine-resistant material is applied to the preparation of PP-R pipes, the obtained PP-R pipes have better chlorine resistance and better mechanical properties.

[0012] Preferably, the synthesis method of the imidazolate skeleton comprises the following steps:

[0013] (1) Weigh zinc nitrate hexahydrate, add it to deionized water and dissolve it by ultrasonication to obtain an aqueous solution of zinc nitrate hexahydrate with a molar concentration of 2.0-4.0 mmol / L;

[0014] (2) Weigh 2-methylimidazole, add it to deionized water and dissolve it by ultrasonication to obtain a 2-methylimidazole aqueous solution with a molar concentration of 200-350 mmol / L;

[0015] (3) Add the 2-methylimidazole aqueous solution dropwise to the zinc nitrate hexahydrate aqueous solution under stirring and continue stirring to obtain a milky white suspension, which is then centrifuged and the solid is collected, washed and dried to obtain an imidazole ester skeleton.

[0016] Preferably, in step (3), the dripping rate is 30-40 mL / min.

[0017] Preferably, in step (3), the stirring rate is 800-1200 r / min.

[0018] Preferably, in step (3), the stirring rate is continued at 800-1200 r / min for 2.5-3.5 h.

[0019] Preferably, in step (3), the centrifugal speed is 8000-12000 r / min, and the centrifugal time is 8-12 min.

[0020] Preferably, in step (3), the drying temperature is 35-45° C. and the drying time is 8-16 hours.

[0021] The present invention has found that the imidazolate skeleton prepared by the preparation method provided by the present invention is of nanometer level, and the average particle size of the obtained imidazolate skeleton is 100-300nm. In the subsequent preparation process, it can be well mixed and reacted with other components, thereby forming a chlorine-resistant material with excellent chlorine resistance and antioxidant properties.

[0022] As a preferred embodiment of the chlorine-resistant material of the present invention, the specific surface area of ​​the diatomaceous earth is 22-30m 2 / g.

[0023] It should be noted that the specific surface area of ​​diatomaceous earth is obtained by BET potential method.

[0024] The present invention has found that the specific surface area of ​​diatomite will affect the performance of chlorine-resistant materials to a certain extent, thereby affecting the comprehensive performance of the PP-R pipe prepared by adding it into the PP-R pipe. When the specific surface area of ​​diatomite is further selected to be 22-30m 2 / g, the comprehensive performance of the PP-R pipe prepared subsequently is better.

[0025] As a preferred embodiment of the chlorine-resistant material of the present invention, the antioxidant includes at least one of a hindered amine antioxidant and a phosphite antioxidant.

[0026] Preferably, the hindered amine antioxidant includes at least one of antioxidant 1010 , antioxidant 1024 , and antioxidant 1330 .

[0027] Preferably, the phosphite antioxidant includes at least one of antioxidant 168 and antioxidant 9228.

[0028] As a preferred embodiment of the chlorine-resistant material of the present invention, the coupling agent includes at least one of silane coupling agent KH-550, silane coupling agent KH-570, and aluminate coupling agent DL-411.

[0029] In a second aspect of the present invention, the present invention provides a method for preparing the chlorine-resistant material, the method comprising the following steps: mixing the components uniformly and then stirring to obtain the chlorine-resistant material.

[0030] As a preferred embodiment of the preparation method of the present invention, the stirring speed is 3000-4000 r / min and the time is 15-25 min.

[0031] In the third aspect of the present invention, the present invention provides the use of the chlorine-resistant material of the present invention in the preparation of chlorine-resistant PP-R pipes.

[0032] In a fourth aspect of the present invention, the present invention provides a chlorine-resistant PP-R pipe, the PP-R pipe comprising an inner layer and an outer layer;

[0033] The inner layer comprises a first PP-R resin and the chlorine-resistant material of the present invention, and the mass ratio of the first PP-R resin to the chlorine-resistant material is (92-96):(4-8).

[0034] The chlorine-resistant PP-R pipe provided by the present invention is compounded with the first PP-R resin and the chlorine-resistant material of the present invention in an appropriate mass ratio, so that the PP-R pipe can achieve good oxidation resistance and chlorine resistance while ensuring its mechanical properties, thereby extending the service life of the PP-R pipe and achieving good mechanical properties of the PP-R pipe.

[0035] Exemplarily, the mass ratio of the first PP-R resin to the chlorine-resistant material may be any point value or any two point range values ​​between (92-96):(4-8), such as 92:4, 92:6, 92:8, 94:4, 94:6, 94:8, 96:4, 96:6, 96:8, etc.

[0036] As a preferred embodiment of the chlorine-resistant PP-R pipe of the present invention, the outer layer includes a second PP-R resin and / or a PP-RCT resin.

[0037] Preferably, the first PP-R resin and the second PP-R resin have a melt index of 0.15-0.5 g / 10 min when tested at 230° C. and 2.16 kg according to GB / T 3682-2000.

[0038] For example, the first PP-R resin may be at least one of Borouge Chemical RA150E and Daqing Refining and Chemical PA14D-2.

[0039] Illustratively, the PP-RCT resin may be at least one of Yanshan Petrochemical 3120 and Borealis RA7050.

[0040] As a preferred embodiment of the chlorine-resistant PP-R pipe of the present invention, the thickness of the inner layer is 0.8-1.5 mm, and the thickness of the outer layer is 1-2 mm.

[0041] The chlorine-resistant PP-R pipe provided by the present invention has excellent oxidation resistance and chlorine resistance, and has good mechanical properties. When transporting drinking water containing chlorine disinfectant, it can avoid the existing PP-R pipe from being damaged or deformed prematurely, and effectively prolongs the service life.

[0042] In a fifth aspect of the present invention, the present invention provides a method for preparing the chlorine-resistant PP-R pipe, the preparation method comprising the following steps:

[0043] (1) Preparation of inner layer material: the first PP-R resin and the chlorine-resistant material are mixed and then extruded and granulated to obtain the inner layer material;

[0044] (2) Preparation of chlorine-resistant PP-R pipes: The inner layer material and the outer layer material are co-extruded to obtain chlorine-resistant PP-R pipes.

[0045] As a preferred embodiment of the preparation method of the present invention, in the step (1), the temperature of the extrusion granulation is 190-220°C and the rotation speed is 30-120r / min.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The chlorine-resistant PP-R pipe prepared by mixing the provided chlorine-resistant material with the PP-R resin in a specific mass ratio has excellent chlorine resistance, antioxidant performance and mechanical properties, and has good stability and service life when transporting water containing chlorine disinfectants; and the preparation method of the chlorine-resistant material and the chlorine-resistant PP-R pipe provided by the present invention is simple to operate, and the raw materials are easily available, which is conducive to actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the scanning electron microscope observation result of the inner layer of the chlorine-resistant PP-R pipe after the chlorine resistance test in Application Example 1;

[0049] Figure 2 This is the scanning electron microscope observation result of the inner layer of the chlorine-resistant PP-R pipe after the chlorine resistance test of comparative application example 4. DETAILED DESCRIPTION

[0050] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0051] The reagents, methods and equipment used in the present invention are all conventional reagents, methods and equipment in the art unless otherwise specified. Unless otherwise specified, the components used in the parallel experiments of the examples of the present invention and the comparative examples are from the same source.

[0052] The raw materials used in the present invention are as follows:

[0053] PP-R-1: random copolymer polypropylene, melt index at 230℃ / 2.16kg is 0.25g / 10min, RA150E, Borouge Chemicals;

[0054] PP-R-2: random copolymer polypropylene, melt index at 230°C / 2.16kg is 0.17 g / 10 min, 200P, Hyosung;

[0055] PP-RCT: random copolymer polypropylene with improved crystallization, melt index of 0.38 g / 10 min at 230 °C / 2.16 kg, 3120, Yanshan Petrochemical;

[0056] PE: high-density polyethylene, melt index at 190°C / 2.16kg is 0.16g / 10min, 6100M, Yangzi Petrochemical;

[0057] Diatomaceous earth 1: specific surface area is 25, Aladdin, K131670;

[0058] Diatomaceous earth 2: specific surface area is 40, Aladdin, K131668;

[0059] Coupling agent 1: coupling agent KH-570, commercially available;

[0060] Coupling agent 2: coupling agent KH-550, commercially available;

[0061] Antioxidant 1: a mixture of antioxidant 1024 and antioxidant 168 in a mass ratio of 1:1, commercially available;

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

[0063] Imidazole ester skeleton 1: homemade, the preparation method comprises the following steps:

[0064] At a speed of 1000 r / min, a 2-methylimidazole aqueous solution with a molar concentration of 280 mol / L after ultrasonic dissolution was added dropwise at a drop rate of 35 mL / min to a zinc nitrate hexahydrate aqueous solution with a molar concentration of 3.0 mol / L after ultrasonic dissolution, wherein the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole was 1:60, and after the addition was completed, stirring was continued at a speed of 1000 r / min at room temperature for 3 h to obtain a milky white suspension, and then centrifuged at a speed of 10000 r / min for 10 min, the white solid was collected and washed three times by centrifugation with anhydrous methanol, and then the washed product was placed in a vacuum drying oven at 40° C. and dried for 12 h to obtain an imidazole ester skeleton 1;

[0065] Imidazole ester skeleton 2: homemade, the only difference in the preparation method from the imidazolate skeleton is that the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:50;

[0066] Imidazole ester skeleton 3: homemade, the only difference in the preparation method from the imidazolate skeleton is that the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:70;

[0067] Imidazole ester skeleton 4: homemade, the only difference in the preparation method from the imidazolate skeleton is that the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:40;

[0068] Imidazole ester skeleton 5: homemade, the only difference in the preparation method from the imidazolate skeleton is that the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:80.

[0069] Examples 1-9 and Comparative Examples 1-3

[0070] The embodiments and comparative examples of the present invention provide a chlorine-resistant material, and the component contents (parts by weight) of the chlorine-resistant material are as shown in Table 1-2 below; the chlorine-resistant materials obtained in Embodiments 1-9 are named AI, and the chlorine-resistant materials obtained in Comparative Examples 1-3 are named ac;

[0071] Table 1

[0072]

[0073] The preparation method of the chlorine-resistant material provided in Example 1 is as follows: the components are mixed according to the mass parts in Table 1 and added into a high-speed stirrer, and stirred at a speed of 3500 r / min at room temperature for 20 min to obtain the chlorine-resistant material;

[0074] The preparation methods of Examples 2-9 and Comparative Examples 1-3 are the same as that of Example 1, except that no relevant components are added.

[0075] Application Examples 1-4 and Comparative Application Examples 1-4

[0076] The application examples of the present invention and the comparative application examples provide a chlorine-resistant PP-R pipe, and the inner layer components (mass parts) and outer layer components (mass parts) of the PP-R pipe are shown in Table 2;

[0077] Table 2

[0078]

[0079] The preparation method of the chlorine-resistant PP-R pipe provided in Application Example 1 comprises the following steps:

[0080] (1) Preparation of inner layer material: PP-R-1 and chlorine-resistant material A are added to a high-speed mixer and mixed uniformly at a speed of 2000 r / min, and then added to a twin-screw extruder and extruded and granulated at 190-220°C. The speed of the twin-screw extruder is 80 r / min, thereby obtaining the inner layer material;

[0081] (2) Preparation of chlorine-resistant PP-R pipe: The inner layer material and the outer layer material are added into a molding machine and single-screw co-extruded at 190-220°C, wherein the thickness of the inner layer is 0.8 mm and the thickness of the outer layer is 1 mm; thus, a chlorine-resistant PP-R pipe is obtained.

[0082] The preparation methods of Application Examples 2-4 and Comparative Application Examples 1-4 are the same as that of Application Example 1, and if there are no related components, they may not be added.

[0083] Application Example 5

[0084] The application example of the present invention provides a chlorine-resistant PP-R pipe. The only difference between the chlorine-resistant PP-R pipe and the application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material B.

[0085] Application Example 6

[0086] The application example of the present invention provides a chlorine-resistant PP-R pipe, and the only difference between the chlorine-resistant PP-R pipe and the application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material C.

[0087] Application Example 7

[0088] The application example of the present invention provides a chlorine-resistant PP-R pipe, and the only difference between the chlorine-resistant PP-R pipe and the application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material D.

[0089] Application Example 8

[0090] The application example of the present invention provides a chlorine-resistant PP-R pipe, and the only difference between the chlorine-resistant PP-R pipe and the application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material E.

[0091] Application Example 9

[0092] The application example of the present invention provides a chlorine-resistant PP-R pipe, and the only difference between the chlorine-resistant PP-R pipe and the application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material F.

[0093] Application Example 10

[0094] The application example of the present invention provides a chlorine-resistant PP-R pipe. The only difference between the chlorine-resistant PP-R pipe and the application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material G.

[0095] Application Example 11

[0096] The application example of the present invention provides a chlorine-resistant PP-R pipe, and the only difference between the chlorine-resistant PP-R pipe and the application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material H.

[0097] Application Example 12

[0098] The application example of the present invention provides a chlorine-resistant PP-R pipe, and the only difference between the chlorine-resistant PP-R pipe and the application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material I.

[0099] Comparative Application Example 5

[0100] The comparative application example of the present invention provides a chlorine-resistant PP-R pipe, the only difference between the chlorine-resistant PP-R pipe and application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material a.

[0101] Comparative Application Example 6

[0102] The comparative application example of the present invention provides a chlorine-resistant PP-R pipe, the only difference between the chlorine-resistant PP-R pipe and application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material b.

[0103] Comparative Application Example 7

[0104] The comparative application example of the present invention provides a chlorine-resistant PP-R pipe, and the only difference between the chlorine-resistant PP-R pipe and application example 1 is that the chlorine-resistant material A is replaced by the chlorine-resistant material C.

[0105] Effect example

[0106] The effect example of the present invention verifies the performance of the chlorine-resistant PP-R pipes prepared by application examples 1-12 and comparative application examples 1-7, specifically: the prepared chlorine-resistant PP-R pipes are subjected to a chloride ion solution immersion experiment, specifically, a 200 ppm chloride ion solution is prepared, and under the conditions of a constant temperature of 50°C and a pH value of 7±0.5, a 30±0.5 cm multi-segment pipe section is immersed in the chloride ion solution to obtain a chlorine-resistant PP-R pipe soaked in the chloride ion solution; then the chlorine-resistant PP-R pipes that have not been soaked in the chloride ion solution and the chlorine-resistant PP-R pipes that have been soaked in the chloride ion solution are tested, including the following aspects:

[0107] 1) Oxidation Induction Time (OIT) test: Take the inner layer of the chlorine-resistant PP-R pipe before being soaked in chloride ion solution and the inner layer of the chlorine-resistant PP-R pipe after being soaked in chloride ion solution for 120 days, refer to the standard GB / T 19466.6-2009 for testing and record in Table 3;

[0108] 2) Hydrostatic test: Take the inner layer of the chlorine-resistant PP-R pipe before being soaked in chloride ion solution and the inner layer of the chlorine-resistant PP-R pipe after being soaked in chloride ion solution for 120 days, refer to the standard GB / T18742.2-2017 for testing and record in Table 3;

[0109] 3) Electron microscope (SEM) test: Take the inner layer of the chlorine-resistant PP-R pipe before being soaked in chloride ion solution and the inner layer of the chlorine-resistant PP-R pipe after being soaked in chloride ion solution for 120 days for SEM test;

[0110] Table 3

[0111]

[0112] It can be seen from Table 3 that the chlorine-resistant PP-R pipe provided by the present invention has excellent comprehensive performance, wherein the oxidation induction time before being soaked in the chloride ion solution is more than 42.2 min, the pressure can be increased by more than 5% in the hydrostatic test, and the pressure can be maintained for 10 h at 5%, and can even be maintained for 4 h at 20%. The oxidation induction time after being soaked in the chloride ion solution for 120 days is more than 32.1 min, and the standard 1.43 MPa in the hydrostatic test can be pressurized by 5% for 1 h, and can even be pressurized by 10% for 2 h;

[0113] It can be seen from Application Example 1 and Comparative Application Example 1 that when no chlorine-resistant material is added, the oxidation induction time of the obtained product is significantly reduced, and the chlorine resistance is significantly reduced. After being immersed in a chloride ion solution for 120 days, the standard 1.43MPa can only be maintained for 18 hours in the static pressure test; it can be seen from Application Example 1 and Comparative Application Example 2 that when PE resin is used instead of PP-R resin, the chlorine resistance of the obtained product also shows a certain downward trend; it can be seen from Application Examples 1-3 and Comparative Application Examples 3-4 that the mass ratio of PP-R resin and chlorine-resistant material in the inner layer will affect the comprehensive performance of the product. When the mass ratio of PP-R resin and chlorine-resistant material in Comparative Application Examples 3-4 is not within the range given in the present invention, the chlorine resistance of the obtained product is significantly reduced. After being immersed in a chloride ion solution for 120 days, the standard 1.43MPa is maintained for less than 8 hours in the static pressure test;

[0114] It can be seen from Application Example 1, Application Examples 5-12 and Comparative Application Examples 5-7 that chlorine-resistant materials will also affect the comprehensive performance of the product; when the mass ratio between the raw materials in the chlorine-resistant materials used in Comparative Application Examples 5-7 is not within the range given in the present invention, the chlorine resistance of the obtained products shows a certain downward trend;

[0115] In addition, the scanning electron microscopic observation results of the inner layer of the chlorine-resistant PP-R pipes prepared in Application Example 1 and Comparative Application Example 4 after chlorine resistance test are as follows: Figure 1 and Figure 2 As shown, from Figure 1 and Figure 2 It can be clearly seen that the product prepared by the technical solution of the present invention has no obvious corrosion phenomenon on the inner surface after the chlorine resistance test, that is, the chlorine resistance is excellent.

[0116] Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A chlorine-resistant PP-R pipe, characterized in that: The PP-R pipe comprises an inner layer and an outer layer; The inner layer comprises a first PP-R resin and a chlorine-resistant material, wherein the mass ratio of the first PP-R resin to the chlorine-resistant material is (92-96): (4-8); The chlorine-resistant material comprises the following raw materials in parts by weight: 1-5 parts of diatomaceous earth, 1-4 parts of imidazole ester skeleton, 0.2-0.5 parts of coupling agent, and 1.2-1.8 parts of antioxidant; The synthesis method of the imidazole ester skeleton comprises the following steps: adding a 2-methylimidazole aqueous solution dropwise to a zinc nitrate hexahydrate aqueous solution under stirring and continuing stirring to obtain a milky white suspension, followed by centrifugation, collecting the solid, washing and drying it, and obtaining the imidazole ester skeleton; The molar ratio of the zinc nitrate hexahydrate to 2-methylimidazole is 1:(50-70).

2. The chlorine-resistant PP-R pipe according to claim 1, characterized in that: The specific surface area of ​​the diatomaceous earth is 22-30m 2 / g.

3. The chlorine-resistant PP-R pipe according to claim 1, characterized in that: The antioxidant includes at least one of a hindered amine antioxidant and a phosphite antioxidant; And / or, the coupling agent includes at least one of silane coupling agent KH-550, silane coupling agent KH-570, and aluminate coupling agent DL-411.

4. The chlorine-resistant PP-R pipe according to claim 1, characterized in that: The preparation method of the chlorine-resistant material comprises the following steps: mixing the components uniformly and then stirring to obtain the chlorine-resistant material.

5. The chlorine-resistant PP-R pipe according to claim 1, characterized in that: The outer layer includes a second PP-R resin and / or a PP-RCT resin.

6. The method for preparing a chlorine-resistant PP-R pipe according to claim 1 or 5, characterized in that: The preparation method comprises the following steps: (1) Preparation of inner layer material: the first PP-R resin and the chlorine-resistant material are mixed and then extruded and granulated to obtain the inner layer material; (2) Preparation of chlorine-resistant PP-R pipes: The inner layer material and the outer layer material are co-extruded to obtain chlorine-resistant PP-R pipes.

7. The preparation method according to claim 6, characterized in that: In the step (1), the temperature of the extrusion granulation is 190-220°C and the rotation speed is 30-120 r / min.

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