Chlorine-resistant polyolefin pipe and method for producing the same

Abstract

The application discloses an anti-chlorine polyolefin pipe and a preparation method thereof, and belongs to the technical field of polymer pipes. The anti-chlorine polyolefin pipe comprises an inner layer and an outer layer, and the inner layer comprises the following components in parts by mass: 92-97 parts of a first PP-R resin and 3-8 parts of an anti-chlorine agent. The anti-chlorine polyolefin pipe provided by the application introduces the anti-chlorine agent into the inner layer, the anti-chlorine agent is prepared by compounding molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and an antioxidant, the antioxidant in the inner layer can be effectively prevented from migrating into tap water, the inner layer of the pipe can continuously release the antioxidant, the released antioxidant plays a barrier and protection role on the inner layer of the pipe, so that the polyolefin pipe provided by the application has good anti-chlorine performance, and the pipeline system of the polyolefin pipe can stably operate under the actual working condition of the tap water containing chlorine.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polymer pipes, and particularly relates to a chlorine-resistant polyolefin pipe and a preparation method thereof. BACKGROUND

[0002] PP-R pipe refers to a random copolymer polypropylene pipe, is a random copolymer of propylene and another olefin monomer, and changes the molecular structure of polypropylene due to the random distribution of the copolymer monomer and the polypropylene chain, thereby forming excellent physical and chemical properties of the pipe.

[0003] At present, the PP-R pipe has been widely used in building water supply and drainage, urban and rural drainage, municipal and other fields due to its light weight, corrosion resistance, smooth inner wall without fouling, simple construction and maintenance, and long service life. However, foreign academic research has found that chlorine disinfectants in drinking water have strong oxidizing properties. With the continuous popularization and application of PP-R pipes in building water supply systems, if the PP-R pipe is used for long-term transportation of drinking water, the antioxidants in the pipe will be consumed prematurely, causing the pipe to fail before reaching the expected service life.

[0004] Therefore, at present, it is urgent to develop a chlorine-resistant polyolefin pipe to ensure that the pipe system of the pipe can operate stably under the actual working conditions of chlorine-containing tap water. SUMMARY

[0005] The application aims to overcome the shortcomings of the prior art and provide a chlorine-resistant polyolefin pipe and a preparation method thereof. The polyolefin pipe has good chlorine resistance, and the pipe system of the pipe can operate stably under the actual working conditions of chlorine-containing tap water.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0007] In a first aspect, the application provides a chlorine-resistant polyolefin pipe, which comprises an inner layer and an outer layer, and the inner layer comprises the following components by mass fraction: 92-97 parts of a first PP-R resin, 3-8 parts of an anti-chlorine agent.

[0008] The preparation raw material of the anti-chlorine agent comprises aminoethyl mercaptan, dicyclohexyl carbodiimide, an antioxidant and molybdenum disulfide, and the mass ratio of the molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: aminoethyl mercaptan: dicyclohexyl carbodiimide: antioxidant = (2-4): (1-3): (0.5-1.5): 1.3.

[0009] The anti-chlorine polyolefin pipe provided by the application introduces an anti-chlorine agent in the inner layer, the anti-chlorine agent includes molybdenum disulfide, aminoethyl mercaptan and dicyclohexyl carbodiimide and an antioxidant, through the complex modification of aminoethyl mercaptan and dicyclohexyl carbodiimide, a chemical bond between molybdenum disulfide and the antioxidant is formed, which effectively prevents a large amount of antioxidant from migrating into a solution due to the flushing of the inner layer by a chlorine-containing solution (such as chlorine-containing tap water), and maximizes the role of the antioxidant; during use, the anti-chlorine agent in the inner layer can continuously release the antioxidant, preventing the oxidation of the inner layer material by free chlorine ions, and playing a barrier and protection role on the inner layer. In addition, the organic layer formed by aminoethyl mercaptan and dicyclohexyl carbodiimide on the surface of molybdenum disulfide reduces the surface energy of the anti-chlorine agent and improves the compatibility of the anti-chlorine agent with the PP-R resin, so that the anti-chlorine agent can be uniformly dispersed in the inner layer, and the mechanical properties of the polyolefin pipe are improved.

[0010] Exemplarily, in the inner layer, the mass fraction of the first PP-R resin can be 92 parts, 93 parts, 94 parts, 95 parts, 96 parts, 97 parts or a range formed by any two of the above-mentioned values, the mass fraction of the anti-chlorine agent can be 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts or a range formed by any two of the above-mentioned values, and the mass ratio of the molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and antioxidant can be 3:1:0.5:1.3, 2:2:1:1.3, 4:1:1.5:1.3, 2:1:0.5:1.3, 4:3:1.5:1.3 or a range formed by any two of the above-mentioned mass ratios.

[0011] Preferably, the specific surface area of the molybdenum disulfide is 20-40 m 2 / g, and the particle size of the molybdenum disulfide is 40-100 nm.

[0012] Exemplarily, the specific surface area of the molybdenum disulfide can be 20 m 2 / g, 25 m 2 / g, 30 m 2 / g, 35 m 2 / g, 40 m 2 / g or a range formed by any two of the above-mentioned values, and the particle size of the molybdenum disulfide can be 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm or a range formed by any two of the above-mentioned values.

[0013] Preferably, the preparation method of the molybdenum disulfide includes the following steps:

[0014] Sodium molybdate dihydrate and thiourea are added to a reaction solvent to react, and then the molybdenum disulfide is obtained through cooling, washing and drying; wherein the reaction temperature is 160-220°C, and the reaction time is 12-30 h.

[0015] Further preferably, the reaction solvent comprises ethanol and water, the volume ratio of the ethanol and water is (0.5~2):1, the molar ratio of the sodium molybdate dihydrate and the thiourea is 1:(4~6), and the ratio between the total mass of the sodium molybdate dihydrate and the thiourea and the total volume of the reaction solvent is (0.5~2)g:10mL.

[0016] The inventors have found that the molybdenum disulfide prepared by the solvothermal method has a porous structure, which makes the molybdenum disulfide have a larger specific surface area and more reaction sites. On the one hand, the porous molybdenum disulfide is more likely to form a stronger covalent bond with the aminoethyl mercaptan and the dicyclohexyl carbodiimide when preparing the chlorine-resistant agent. On the other hand, the molybdenum disulfide in the chlorine-resistant agent can adsorb chloride ions in the inner layer surface or inner layer gap during use, and eliminate the adsorbed chloride ions through the antioxidant in the inner layer, thereby improving the chlorine resistance of the inner layer and inhibiting the aging of the chlorine-resistant polyolefin pipe under the working condition of chlorine-containing tap water.

[0017] For example, the reaction temperature can be 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, or a range formed by any two of the above values. The reaction time can be 12h, 15h, 18h, 20h, 22h, 25h, 28h, 30h, or a range formed by any two of the above values.

[0018] Preferably, the antioxidant comprises at least one of a hindered phenolic antioxidant and a phosphite antioxidant, the hindered phenolic antioxidant comprises at least one of antioxidant 300, antioxidant 1076, antioxidant 1024, and the phosphite antioxidant comprises at least one of antioxidant 168, antioxidant 9228.

[0019] Further preferably, the antioxidant comprises a hindered phenolic antioxidant and a phosphite antioxidant, and the mass ratio of the hindered phenolic antioxidant to the phosphite antioxidant is (0.5~1):1.

[0020] Preferably, the inner layer comprises the following components in parts by mass: 94.2~95.5 parts of a first PP-R resin, and 4.5~5.8 parts of a chlorine-resistant agent. The inventors have found that when the mass parts of each component in the inner layer are within the above preferred range, the comprehensive performance of the polyolefin pipe is better.

[0021] Preferably, the mass ratio of the molybdenum disulfide, aminoethanethiol, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexyl carbodiimide: antioxidant = (2-3): (1-2): (0.5-1): 1.3. The inventors have found that when the mass ratio of the molybdenum disulfide, aminoethanethiol, dicyclohexyl carbodiimide and antioxidant is within the preferred range, the comprehensive performance of the polyolefin pipe is better.

[0022] Preferably, the preparation method of the anti-chlorine agent comprises the following steps:

[0023] The molybdenum disulfide and aminoethanethiol are added to an organic solvent and subjected to ultrasonic treatment, and then filtered, washed to obtain a mixture;

[0024] The antioxidant and dicyclohexyl carbodiimide are added to an organic solvent for dissolution to obtain a mixed solution;

[0025] The mixture is added to the mixed solution for stirring treatment, and then centrifuged, washed, and dried to obtain the anti-chlorine agent.

[0026] Further preferably, the organic solvent comprises at least one of isopropyl alcohol and diethyl ether.

[0027] Further preferably, the ratio between the sum of the mass of the antioxidant and dicyclohexyl carbodiimide and the volume of the organic solvent is (0.5-2) g: 10 mL.

[0028] Further preferably, the temperature of the ultrasonic treatment is 0-5°C, and the time of the ultrasonic treatment is 3-10 h.

[0029] Further preferably, the temperature of the stirring treatment can be 50-70°C, the stirring speed of the stirring treatment can be 500-1000 r / min, and the time of the stirring treatment can be 36-72 h.

[0030] Illustratively, the temperature of the ultrasonic treatment can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, or a range formed by any two of the above values, and the time of the ultrasonic treatment can be 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, or a range formed by any two of the above values.

[0031] Exemplarily, the temperature of the stirring treatment can be 50℃, 55℃, 60℃, 65℃, 70℃ or a range formed by any two of the above values, the rotating speed of the stirring treatment can be 500r / min, 600r / min, 700r / min, 800r / min, 900r / min, 1000r / min or a range formed by any two of the above values, and the time of the stirring treatment can be 36h, 42h, 48h, 50h, 56h, 60h, 66h, 72h or a range formed by any two of the above values.

[0032] Preferably, the outer layer comprises at least one of a second PP-R resin and a PP-RCT resin.

[0033] In a second aspect, the application provides a method for preparing the chlorine-resistant polyolefin pipe according to the first aspect, comprising the following steps:

[0034] S1, mixing the first PP-R resin and the chlorine-resistant agent, and then performing extrusion granulation to obtain an inner layer material;

[0035] S2, co-extruding the inner layer material and an outer layer material, vacuumizing and sizing, and cooling to obtain a pipe semi-finished product;

[0036] S3, annealing and cooling the pipe semi-finished product to obtain the chlorine-resistant polyolefin pipe.

[0037] Preferably, in step S1, the temperature of the extrusion granulation is 190-220℃, and the rotating speed of the screw rod is 30-120r / min.

[0038] Preferably, in step S3, the temperature of the annealing treatment is 100-110℃.

[0039] Compared with the prior art, the application has the following beneficial effects:

[0040] The chlorine-resistant polyolefin pipe provided by the application introduces a chlorine-resistant agent into the inner layer, and the chlorine-resistant agent is prepared by compounding molybdenum disulfide, aminoethyl mercaptan and dicyclohexyl carbodiimide, which can effectively prevent the migration of the antioxidant in the inner layer to tap water, and can also enable the inner layer of the pipe to continuously release the antioxidant, and the released antioxidant can play a barrier and protection role on the inner layer of the pipe, so that the polyolefin pipe provided by the application has good chlorine resistance, and the pipe system of the polyolefin pipe can stably operate under the actual working condition of tap water containing chlorine. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 Scanning electron microscope images of the inner layer of Example 1 before immersion and after immersion for 120 days;

[0042] Figure 2The scanning electron microscope images of the inner layer of Comparative Example 1 before soaking and after soaking for 120 days. DETAILED DESCRIPTION

[0043] For the purpose of better illustrating the object, technical scheme and advantages of the present application, the present application will be further described in conjunction with specific examples.

[0044] The reagents, methods and equipment used in the present application are all conventional reagents, methods and equipment in the art unless otherwise specified. The components used in the parallel experiments of the examples and comparative examples of the present application are from the same source unless otherwise specified.

[0045] The raw materials used in the examples and comparative examples of the present application are as follows:

[0046] PP-R Resin 1: the brand is 4220, the manufacturer is Maoming Petrochemical, and the melt index at 230℃ under a load of 2.16kg is 0.23g / 10min according to GB / T 3682-2000;

[0047] PP-R Resin 2: the brand is 150E, the manufacturer is Beinuo Chemical, and the melt index at 230℃ under a load of 2.16kg is 0.24g / 10min according to GB / T 3682-2000;

[0048] PP-R Resin 3: the brand is T4401, the manufacturer is Dushanzi Petrochemical, and the melt index at 230℃ under a load of 2.16kg is 0.21g / 10min according to GB / T 3682-2000;

[0049] PP-R Resin 4: the brand is PA14D-2, the manufacturer is Daqing Petrochemical, and the melt index at 230℃ under a load of 2.16kg is 0.28g / 10min according to GB / T 3682-2000;

[0050] PP-RCT Resin: the brand is 3120, the manufacturer is Yanshan Petrochemical, and the melt index at 230℃ under a load of 2.16kg is 0.24g / 10min according to GB / T 3682-2000;

[0051] Polyethylene: the brand is DGDZ3606, the manufacturer is Dushanzi Petrochemical, and the melt index at 190℃ under a load of 2.16kg is 0.30g / 10min according to GB / T 3682-2000;

[0052] Chlorine-resistant agent 1: self-made, and the preparation method is as follows:

[0053] (1) adding sodium molybdate dihydrate and thiourea into a reaction solvent to stir at a rotation speed of 1000 r / min until fully dissolved to obtain a mixed solution, the molar ratio of sodium molybdate dihydrate to thiourea being 1:5, the ratio between the total mass of sodium molybdate dihydrate and thiourea and the total volume of the reaction solvent being 1 g:10 mL, the reaction solvent being a mixed solvent of ethanol and water, the volume ratio of the ethanol to water being 1:2, then transferring the mixed solution into a reaction kettle and placing it in a blast drying oven to react at 180℃ for 24 h, after naturally cooling to room temperature, washing and centrifuging the product after reaction once with distilled water and anhydrous ethanol respectively, and vacuum drying at 40℃ for 12 h to obtain molybdenum disulfide, the average particle size of the molybdenum disulfide being 75 nm, and the specific surface area being 30 m 2 / g;

[0054] (2) preparing molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide, and an antioxidant, wherein the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide, and the antioxidant is molybdenum disulfide:aminoethyl mercaptan:dicyclohexyl carbodiimide:antioxidant = 3:1:0.5:1.3, and the antioxidant is a mixture of antioxidant 300 and antioxidant 9228 at a mass ratio of 1:1;

[0055] adding molybdenum disulfide and aminoethyl mercaptan into isopropyl alcohol and mixing uniformly, the ratio between the sum of the mass of molybdenum disulfide and aminoethyl mercaptan and the volume of isopropyl alcohol being 1:10, and then performing ultrasonic treatment under the condition of an ice water bath (i.e. a temperature of 0℃) for 5 h, followed by filtration and washing, and drying to obtain a mixture of aminated molybdenum disulfide;

[0056] adding the antioxidant and dicyclohexyl carbodiimide into isopropyl alcohol to dissolve, to obtain a mixed solution, wherein the ratio between the sum of the mass of the antioxidant and dicyclohexyl carbodiimide and the volume of isopropyl alcohol is 1:10; adding the mixture of aminated molybdenum disulfide into the obtained mixed solution, stirring at a rotation speed of 800 r / min at 60℃ for 48 h, then cooling to room temperature, taking the precipitate by centrifugation, washing the precipitate with ethanol and centrifuging 5 times, and then placing it in an oven for drying to obtain an anti-chlorine agent;

[0057] The anti-chlorine agent 2 is self-made, and the difference between the anti-chlorine agent 2 and the anti-chlorine agent 1 is that, in the preparation method of the anti-chlorine agent 2, the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide, and the antioxidant is molybdenum disulfide:aminoethyl mercaptan:dicyclohexyl carbodiimide:antioxidant = 2:2:1:1.3;

[0058] The anti-chlorine agent 3 is self-made, and the difference between the anti-chlorine agent 3 and the anti-chlorine agent 1 is that, in the preparation method of the anti-chlorine agent 3, the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide, and the antioxidant is molybdenum disulfide:aminoethyl mercaptan:dicyclohexyl carbodiimide:antioxidant = 4:1:1.5:1.3;

[0059] Anti-chlorine agent 4: self-made, which is different from anti-chlorine agent 1 in that, in the preparation method of anti-chlorine agent 4, the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: aminoethyl mercaptan: dicyclohexyl carbodiimide: antioxidant = 2: 1: 0.5: 1.3;

[0060] Anti-chlorine agent 5: self-made, which is different from anti-chlorine agent 1 in that, in the preparation method of anti-chlorine agent 5, the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: aminoethyl mercaptan: dicyclohexyl carbodiimide: antioxidant = 4: 3: 1.5: 1.3;

[0061] Anti-chlorine agent 6: self-made, which is different from anti-chlorine agent 1 in that, in the preparation method of anti-chlorine agent 6, the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: aminoethyl mercaptan: dicyclohexyl carbodiimide: antioxidant = 1: 1: 0.5: 1.3;

[0062] Anti-chlorine agent 7: self-made, which is different from anti-chlorine agent 1 in that, in the preparation method of anti-chlorine agent 7, the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: aminoethyl mercaptan: dicyclohexyl carbodiimide: antioxidant = 5: 1: 0.5: 1.3;

[0063] Anti-chlorine agent 8: self-made, which is different from anti-chlorine agent 1 in that, in the preparation method of anti-chlorine agent 8, the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: aminoethyl mercaptan: dicyclohexyl carbodiimide: antioxidant = 3: 0.5: 0.2: 1.3;

[0064] Anti-chlorine agent 9: self-made, which is different from anti-chlorine agent 1 in that, in the preparation method of anti-chlorine agent 9, the mass ratio of molybdenum disulfide, aminoethyl mercaptan, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: aminoethyl mercaptan: dicyclohexyl carbodiimide: antioxidant = 3: 4: 2: 1.3;

[0065] Anti-chlorine agent 10: self-made, which is different from anti-chlorine agent 1 in that, in the preparation method of anti-chlorine agent 10, no aminoethyl mercaptan is added, and the mass ratio of molybdenum disulfide, dicyclohexyl carbodiimide and antioxidant is molybdenum disulfide: dicyclohexyl carbodiimide: antioxidant = 3: 0.5: 1.3;

[0066] Anti-chlorine agent 11: self-made, which is different from anti-chlorine agent 1 in that, in the preparation method of anti-chlorine agent 11, no dicyclohexyl carbodiimide is added, and the mass ratio of molybdenum disulfide, aminoethyl mercaptan and antioxidant is molybdenum disulfide: aminoethyl mercaptan: antioxidant = 3: 1: 1.3;

[0067] The antioxidant in the above chlorine-resistant agent is a mixture of commercially available antioxidant 300 and commercially available antioxidant 9228 in a mass ratio of 1:1.

[0068] Examples 1-11 and Comparative Examples 1-10

[0069] Examples 1-11 and Comparative Examples 1-10 of the present application each provide a chlorine-resistant polyolefin pipe, which includes an inner layer and an outer layer; and a method for preparing the chlorine-resistant polyolefin pipe, which includes the following steps:

[0070] S1, according to the component content (mass parts) in Tables 1-3, the components of the inner layer are added to a high-speed mixer and mixed uniformly at a speed of 2000 r / min, then added to a twin-screw extruder and extruded and granulated at 190-220℃, the screw speed of the twin-screw extruder is 80 r / min, and the inner layer material is obtained after drying;

[0071] S2, the inner layer material and the outer layer material are added to a molding machine and subjected to single-screw co-extrusion at 190-220℃, vacuum sizing, cooling, and a pipe semi-finished product is obtained;

[0072] S3, the pipe semi-finished product is annealed at 110℃ for 30 min and naturally cooled to room temperature to obtain a chlorine-resistant polyolefin pipe, wherein the thickness of the inner layer of the pipe is 0.8 mm and the thickness of the outer layer is 1 mm.

[0073] Table 1: Components of the inner layer and their mass parts (unit: parts)

[0074]

[0075] Table 2: Components of the inner layer and their mass parts (unit: parts)

[0076]

[0077] Table 3: Components of the inner layer and their mass parts (unit: parts)

[0078]

[0079] Performance test

[0080] The pipe provided in the above examples and comparative examples is used as a sample to perform a chlorine ion solution immersion experiment: a chlorine ion solution with a concentration of 200 ppm is prepared, and a pipe with a length of 30 cm±0.5 cm is immersed in the chlorine ion solution at a constant temperature of 60℃ and a pH value of 7±0.5; before immersion and after 120 days of immersion, the inner layer of the pipe is scraped as a sample and tested as follows:

[0081] (1) According to the standard GB / T 19466.6-2009, the oxidation induction time test is carried out on the sample, and the test temperature is 210℃;

[0082] (2) According to the standard GB / T 6111-2003, the hydrostatic test of 95℃ / 22h is carried out on the sample, and after the test under the standard pressure, the pressure is increased by 5% of the pressure until the pipe breaks;

[0083] For example, the hydrostatic test is carried out at 95℃ and the standard pressure (1.43MPa), and after 22h of keeping time, the pipe has no rupture phenomenon, and the keeping time under the standard pressure is recorded as 22h; then the pressure is increased by 5% (i.e. 1.05 times of the standard pressure) for the hydrostatic test, and after 22h of keeping time, the pipe has no rupture phenomenon, and the pressure is further increased by 10% (i.e. 1.1 times of the standard pressure) for the hydrostatic test, and after 5h of keeping time, the pipe has rupture phenomenon, and the test is terminated, and the percentage of the increased pressure is recorded as 10%, and the keeping time after the pressure increase is recorded as 5h;

[0084] (3) The inner layer of the pipe is tested by scanning electron microscopy (SEM).

[0085] The test results are shown in Table 4 and Figures 1-2 .

[0086] Table 4

[0087]

[0088] As can be seen from Table 4, the chlorine-resistant polyolefin pipe provided by each embodiment of the present application has excellent comprehensive performance of chlorine resistance and pressure resistance, the oxidation induction time before soaking in the chlorine ion solution is not less than 41.2min, the pressure increase amplitude in the hydrostatic test is not less than 15%, and the keeping time after the pressure increase of 15% is not less than 3h, and even the keeping time after the pressure increase of 25% can be 8h; the oxidation induction time after soaking in the chlorine ion solution for 120 days is not less than 30.2min, the keeping time under the standard pressure in the hydrostatic test is not less than 18h, and even the keeping time after the pressure increase of 15% can be 5h. This shows that the pipe system of the polyolefin pipe prepared by the technical scheme of the present application can stably operate under the actual working condition of the chlorine-containing tap water.

[0089] As can be seen from Examples 1-4 and Comparative Examples 7-8, when the mass ratio of the PP-R resin to the chlorine-resistant agent in the inner layer is different, the chlorine resistance of the polyolefin pipe has certain difference. Compared with Examples 1-4, the mass ratio of the chlorine-resistant agent in the inner layer of Comparative Example 7 is too high, the chlorine resistance of the polyolefin pipe is significantly reduced, and the pressure resistance is also slightly reduced; the mass ratio of the chlorine-resistant agent in the inner layer of Comparative Example 8 is too low, and the chlorine resistance of the polyolefin pipe is obviously reduced.

[0090] Compared with Example 1, the inner layer of Comparative Example 1 does not use PP-R resin, but uses polyethylene as the main component, and the chlorine resistance and pressure resistance of the pipe material are both reduced.

[0091] As can be seen from Example 1, Examples 8-11 and Comparative Examples 2-6, when the mass ratio of the chlorine-resistant agent in the inner layer is fixed, changing the mass ratio of each component in the chlorine-resistant agent causes the performance of the polyolefin pipe material to have certain differences; compared with Comparative Examples 2-6, Examples 1 and Examples 8-11 control the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexyl carbodiimide and antioxidant in the range of molybdenum disulfide: aminoethanethiol: dicyclohexyl carbodiimide: antioxidant = (2-4): (1-3): (0.5-1.5): 1.3, which can effectively improve the chlorine resistance of the polyolefin pipe material while ensuring the pressure resistance of the polyolefin pipe material; compared with Examples 9 and 11, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexyl carbodiimide and antioxidant in Examples 1 and Examples 8 and 10 is in the range of molybdenum disulfide: aminoethanethiol: dicyclohexyl carbodiimide: antioxidant = (2-3): (1-2): (0.5-1): 1.3, and the comprehensive performance of the chlorine resistance and pressure resistance of the polyolefin pipe material is better.

[0092] In addition, the inner layer was observed by scanning electron microscopy before soaking and after soaking in a chloride ion solution for 120 days, and the results are shown in Figure 1 and Figure 2 As can be clearly seen from Figure 1 and Figure 2 , the inner layer surface of the pipe product prepared by the technical scheme of the present application has no obvious corrosion phenomenon after the chlorine resistance experiment, which shows that the polyolefin pipe material prepared by the technical scheme of the present application has excellent chlorine resistance.

[0093] Finally, it should be noted that the above examples are intended to illustrate the technical scheme of the present application, but not to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical scheme of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical scheme of the present application.

Claims

1. A chlorine-resistant polyolefin pipe, characterized in that, It includes an inner layer and an outer layer, wherein the inner layer comprises the following components in parts by weight: 92-97 parts of first PP-R resin and 3-8 parts of chlorine-resistant agent; The raw materials for preparing the antichlorine agent include molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide, and an antioxidant. The mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide, and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = (2~4): (1~3): (0.5~1.5): 1.

3. The method for preparing molybdenum disulfide includes the following steps: Sodium molybdate dihydrate and thiourea were added to a reaction solvent and reacted. After cooling, washing, and drying, molybdenum disulfide was obtained. The reaction temperature was 160-220℃ and the reaction time was 12-30h. The antioxidant includes at least one of hindered phenolic antioxidants and phosphite antioxidants, wherein the hindered phenolic antioxidants include at least one of antioxidant 300, antioxidant 1076, and antioxidant 1024, and the phosphite antioxidants include at least one of antioxidant 168 and antioxidant 9228. The preparation method of the chlorine-resistant agent includes the following steps: Molybdenum disulfide and aminoethanethiol were added to an organic solvent, subjected to ultrasonic treatment, and then filtered and washed to obtain a mixture. The antioxidant and dicyclohexylcarbodiimide were dissolved in an organic solvent to obtain a mixed solution; The mixture is added to the mixed solution and stirred, then centrifuged, washed, and dried to obtain the chlorine-resistant agent; The outer layer includes at least one of a second PP-R resin and a PP-RCT resin.

2. The chlorine-resistant polyolefin pipe as described in claim 1, characterized in that, The specific surface area of ​​the molybdenum disulfide is 20~40 m². 2 / g, wherein the particle size of the molybdenum disulfide is 40~100nm.

3. The chlorine-resistant polyolefin pipe as described in claim 1, characterized in that, The ultrasonic treatment temperature is 0~5℃, and the ultrasonic treatment time is 3~10h; And / or, the temperature of the stirring treatment is 50~70℃, the stirring speed is 500~1000r / min, and the stirring time is 36~72h.

4. A method for preparing chlorine-resistant polyolefin pipe as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. The first PP-R resin and the chlorine-resistant agent are mixed and then extruded and granulated to obtain the inner layer material; S2. Co-extrude the inner and outer layer materials, vacuum sizing, and cool to obtain a semi-finished pipe product. S3. Anneal and cool the semi-finished pipe to obtain chlorine-resistant polyolefin pipe.

5. The method for preparing the chlorine-resistant polyolefin pipe as described in claim 4, characterized in that, In step S1, the extrusion granulation temperature is 190~220℃, and the screw speed of the extrusion granulation is 30~120r / min.

6. The method for preparing the chlorine-resistant polyolefin pipe as described in claim 4, characterized in that, In step S3, the annealing temperature is 100~110℃.

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