Chlorine-resistant polyolefin pipe and preparation method thereof

Abstract

The invention discloses an anti-chlorine polyolefin pipe and a preparation method thereof, and belongs to the technical field of polymer pipes. The chlorine-resistant polyolefin pipe comprises an inner layer and an outer layer, wherein the inner layer comprises the following components in parts by mass: 92-97 parts of first PP-R resin and 3-8 parts of an anti-chlorine agent; according to the anti-chlorine polyolefin pipe provided by the invention, the anti-chlorine agent is introduced into the inner layer, and the anti-chlorine agent is prepared by compounding molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and the antioxidant, so that the antioxidant in the inner layer can be effectively prevented from being migrated into tap water, and the inner layer of the pipe can continuously release the antioxidant; the released antioxidant plays a role in blocking and protecting the inner layer of the pipe, so that the polyolefin pipe provided by the invention has better chlorine resistance, and a pipeline system of the polyolefin pipe can stably operate under the actual working condition of chlorine-containing tap water.

Description

Technical Field

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

[0002] PP-R pipe is the abbreviation of random copolymer polypropylene pipe (also known as random copolymer polypropylene pipe), which is a random copolymer formed by the copolymerization of propylene and another olefin monomer. The irregular distribution of its comonomer and polypropylene chain changes the molecular structure of polypropylene, thus forming the excellent physical and chemical properties of this pipe.

[0003] Currently, PP-R pipes are widely used in building water supply and drainage, urban and rural drainage, municipal services, and other fields due to their lightweight, corrosion-resistant, smooth, scale-free inner wall, easy construction and maintenance, and long service life. However, international academic research has found that chlorine-containing disinfectants in drinking water are highly oxidizing. With the increasing promotion and application of PP-R pipes in building water supply systems, if PP-R pipes are used for long-term drinking water transportation, the antioxidants in the pipes will be consumed prematurely, causing the pipes to fail before their expected service life.

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

[0005] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a chlorine-resistant polyolefin pipe and a preparation method thereof. The polyolefin pipe has good chlorine resistance and the piping system of the pipe can operate stably under the actual working conditions of chlorinated tap water.

[0006] To achieve the above object, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a chlorinated polyolefin pipe comprising an inner layer and an outer layer, wherein the inner layer comprises the following components in parts by weight: 92 to 97 parts of a first PP-R resin and 3 to 8 parts of a chlorine-resistant agent; The raw materials for preparing the anti-chlorine agent include aminoethanethiol, dicyclohexylcarbodiimide, an antioxidant and molybdenum disulfide. 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.

[0007] The chlorine-resistant polyolefin pipe provided by the present invention incorporates an anti-chlorine agent into its inner layer. The anti-chlorine agent comprises molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide, and an antioxidant. Through composite modification with aminoethanethiol and dicyclohexylcarbodiimide, a chemical bond is formed between the molybdenum disulfide and the antioxidant, effectively preventing large amounts of the antioxidant from migrating into the solution when flushing the inner layer with a chlorine-containing solution (such as chlorine-containing tap water), maximizing its effectiveness. During use, the anti-chlorine agent in the inner layer continuously releases the antioxidant, preventing free chloride ions from oxidizing the inner layer material and providing a barrier and protective effect. Furthermore, the organic layer formed by aminoethanethiol and dicyclohexylcarbodiimide on the surface of the molybdenum disulfide reduces the surface energy of the anti-chlorine agent, improves its compatibility with the PP-R resin, and enables the anti-chlorine agent to be evenly dispersed in the inner layer, thereby enhancing the mechanical properties of the polyolefin pipe.

[0008] Exemplarily, in the inner layer, the mass parts of the first PP-R resin can be 92 parts, 93 parts, 94 parts, 95 parts, 96 parts, 97 parts or a range consisting of any two groups of values ​​therein, the mass parts of the anti-chlorine agent can be 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts or a range consisting of any two groups of values ​​therein, and the mass ratio of the molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide 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 consisting of any two groups of mass ratios therein.

[0009] Preferably, the specific surface area of ​​the molybdenum disulfide is 20 to 40 m 2 / g, and the particle size of the molybdenum disulfide is 40~100nm.

[0010] For example, the specific surface area of ​​the molybdenum disulfide can be 20 m 2 / g, 25m 2 / g、30m 2 / g、35m 2 / g, 40m 2 / g or a range consisting of any two groups of values ​​therein; the particle size of the molybdenum disulfide can be 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm or a range consisting of any two groups of values ​​therein.

[0011] Preferably, the preparation method of molybdenum disulfide comprises the following steps: Sodium molybdate dihydrate and thiourea are added to a reaction solvent for reaction, and molybdenum disulfide is obtained after cooling, washing, and drying. The reaction temperature is 160-220° C., and the reaction time is 12-30 hours.

[0012] Further preferably, the reaction solvent comprises ethanol and water, the volume ratio of the ethanol to water is (0.5-2):1, the molar ratio of the sodium molybdate dihydrate to thiourea is 1:(4-6), and the ratio between the total mass of the sodium molybdate dihydrate and thiourea and the total volume of the reaction solvent is (0.5-2) g:10 mL.

[0013] The inventors have discovered through research that the molybdenum disulfide prepared by the solvent thermal method of the present invention has a porous structure. The porous structure gives the molybdenum disulfide a larger specific surface area and more reaction sites. On the one hand, the molybdenum disulfide with a porous structure is more likely to form a stronger covalent bond with aminoethanethiol and dicyclohexylcarbodiimide when preparing the anti-chlorine agent; on the other hand, the molybdenum disulfide in the anti-chlorine agent can adsorb chloride ions on the surface of the inner layer or in the gaps of the inner layer 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 chlorine-containing tap water conditions.

[0014] Illustratively, the reaction temperature can be 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, or a range consisting of any two groups of values ​​therein, and the reaction time can be 12h, 15h, 18h, 20h, 22h, 25h, 28h, 30h, or a range consisting of any two groups of values ​​therein.

[0015] Preferably, the antioxidant includes at least one of a hindered phenol antioxidant and a phosphite antioxidant, the hindered phenol antioxidant includes at least one of antioxidant 300, antioxidant 1076, and antioxidant 1024, and the phosphite antioxidant includes at least one of antioxidant 168 and antioxidant 9228.

[0016] Further preferably, the antioxidant comprises a hindered phenol antioxidant and a phosphite antioxidant, and the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is (0.5-1):1.

[0017] Preferably, the inner layer comprises the following components in parts by weight: 94.2-95.5 parts of the first PP-R resin and 4.5-5.8 parts of the chlorine-resistant agent. The inventors have found that when the parts by weight of the components in the inner layer are within this preferred range, the overall performance of the polyolefin pipe is better.

[0018] Preferably, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide, and antioxidant is (2-3): (1-2): (0.5-1): 1.3. The inventors have discovered that when the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide, and antioxidant falls within this preferred range, the overall performance of the polyolefin pipe is improved.

[0019] Preferably, the preparation method of the chlorine-resistant agent comprises the following steps: Molybdenum disulfide and aminoethanethiol are added to an organic solvent, subjected to ultrasonic treatment, and then filtered and washed to obtain a mixture; adding an antioxidant and dicyclohexylcarbodiimide into an organic solvent and dissolving them to obtain a mixed solution; The mixture is added into the mixed solution and stirred, and then centrifuged, washed and dried to obtain the anti-chlorine agent.

[0020] More preferably, the organic solvent includes at least one of isopropyl alcohol and diethyl ether.

[0021] More preferably, the ratio of the sum of the masses of the antioxidant and dicyclohexylcarbodiimide to the volume of the organic solvent is (0.5-2) g:10 mL.

[0022] More preferably, the temperature of the ultrasonic treatment is 0-5° C., and the time of the ultrasonic treatment is 3-10 h.

[0023] More preferably, the stirring temperature may be 50-70° C., the stirring speed may be 500-1000 r / min, and the stirring time may be 36-72 h.

[0024] Exemplarily, the temperature of the ultrasonic treatment can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C or a range consisting of any two groups of values ​​therein, and the time of the ultrasonic treatment can be 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or a range consisting of any two groups of values ​​therein.

[0025] Exemplarily, the temperature of the stirring treatment can be 50°C, 55°C, 60°C, 65°C, 70°C or a range consisting of any two groups of values ​​therein, the speed of the stirring treatment can be 500r / min, 600r / min, 700r / min, 800r / min, 900r / min, 1000r / min or a range consisting of any two groups of values ​​therein, and the time of the stirring treatment can be 36h, 42h, 48h, 50h, 56h, 60h, 66h, 72h or a range consisting of any two groups of values ​​therein.

[0026] Preferably, the outer layer comprises at least one of a second PP-R resin and a PP-RCT resin.

[0027] In a second aspect, the present invention provides a method for preparing the chlorine-resistant polyolefin pipe as described in the first aspect, comprising the following steps: S1, mixing a first PP-R resin and a chlorine-resistant agent and then extruding and granulating the mixture to obtain an inner layer material; S2, co-extruding the inner layer material and the outer layer material, vacuuming and sizing, and cooling to obtain a semi-finished pipe; S3. Annealing and cooling the semi-finished pipe to obtain a chlorine-resistant polyolefin pipe.

[0028] Preferably, in step S1, the temperature of the extrusion granulation is 190-220° C., and the screw speed of the extrusion granulation is 30-120 r / min.

[0029] Preferably, in step S3, the temperature of the annealing treatment is 100-110°C.

[0030] Compared with the prior art, the present invention has the following beneficial effects: The chlorine-resistant polyolefin pipe provided by the present invention introduces an anti-chlorine agent into the inner layer. The anti-chlorine agent is prepared by compounding molybdenum disulfide, aminoethanethiol and dicyclohexylcarbodiimide. The anti-chlorine agent can effectively prevent the antioxidant in the inner layer from migrating into tap water, and can also enable the inner layer of the pipe to continuously release the antioxidant. The released antioxidant has a barrier and protective effect on the inner layer of the pipe, so that the polyolefin pipe provided by the present invention has good chlorine resistance. The pipeline system of the polyolefin pipe can operate stably under actual working conditions of chlorine-containing tap water. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 These are scanning electron microscope images of the inner layer of Example 1 before immersion and after immersion for 120 days; Figure 2 These are scanning electron microscope images of the inner layer of Comparative Example 1 before immersion and after immersion for 120 days. DETAILED DESCRIPTION

[0032] 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.

[0033] The reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art unless otherwise specified. Unless otherwise specified, the components used in the parallel experiments of the examples and comparative examples are of the same origin.

[0034] The raw materials used in the embodiments and comparative examples of the present invention are as follows: PP-R resin 1: Brand 4220, manufactured by Maoming Petrochemical, with a melt index of 0.23 g / 10 min at 230°C and a load of 2.16 kg, as measured according to GB / T 3682-2000. PP-R resin 2: Brand 150E, manufactured by Borealis, with a melt index of 0.24 g / 10 min at 230°C and a load of 2.16 kg, as measured according to GB / T 3682-2000. PP-R resin 3: brand T4401, manufactured by Dushanzi Petrochemical, with a melt index of 0.21 g / 10 min at 230°C and a load of 2.16 kg, as measured according to GB / T 3682-2000. PP-R resin 4: brand PA14D-2, manufactured by Daqing Petrochemical, with a melt index of 0.28 g / 10 min at 230°C and a load of 2.16 kg, as measured according to GB / T 3682-2000. PP-RCT resin: Brand 3120, manufactured by Yanshan Petrochemical, with a melt index of 0.24 g / 10 min at 230°C and a load of 2.16 kg, as measured according to GB / T 3682-2000. Polyethylene: Brand: DGDZ3606, manufactured by Dushanzi Petrochemical, with a melt index of 0.30 g / 10 min at 190°C and a load of 2.16 kg, as measured according to GB / T 3682-2000; Anti-chlorine agent 1: homemade, its preparation method is: (1) Sodium molybdate dihydrate and thiourea are added to a reaction solvent and stirred at a speed of 1000 r / min until fully dissolved to obtain a mixed solution, wherein the molar ratio of sodium molybdate dihydrate and thiourea is 1:5, and the ratio between the total mass of sodium molybdate dihydrate and thiourea and the total volume of the reaction solvent is 1 g:10 mL. The reaction solvent is a mixed solvent of ethanol and water, and the volume ratio of ethanol to water is 1:2. The mixed solution is then transferred to a reactor and placed in a forced air drying oven to react at 180°C for 24 hours. After naturally cooling to room temperature, the reaction product is washed and centrifuged once with distilled water and anhydrous ethanol respectively, and vacuum dried at 40°C for 12 hours to obtain molybdenum disulfide, wherein the average particle size of the molybdenum disulfide is 75 nm and the specific surface area is 30 m 2 / g; (2) preparing molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide, and an antioxidant, wherein the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide, and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 3:1:0.5:1.3, and the antioxidant is prepared by mixing antioxidant 300 and antioxidant 9228 in a mass ratio of 1:1; Molybdenum disulfide and aminoethanethiol are added to isopropyl alcohol and mixed evenly, with the ratio between the sum of the mass of molybdenum disulfide and aminoethanethiol and the volume of isopropyl alcohol being 1:10, and ultrasonically treated for 5 hours in an ice-water bath (i.e., at a temperature of 0°C), and then filtered, washed, and dried to obtain a mixture of amination molybdenum disulfide; An antioxidant and dicyclohexylcarbodiimide are added to isopropyl alcohol for dissolution to obtain a mixed solution, wherein the ratio between the sum of the mass of the antioxidant and the dicyclohexylcarbodiimide and the volume of the isopropyl alcohol is 1:10; amination of the mixture with molybdenum disulfide is added to the obtained mixed solution, and the mixture is stirred at 800 r / min at 60° C. for 48 hours, and then cooled to room temperature, and a precipitate is collected by centrifugation. The precipitate is washed with ethanol and centrifuged 5 times, and then dried in an oven to obtain an antichloride agent; Antichlorine agent 2: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 2, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 2:2:1:1.3; Antichlorine agent 3: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 3, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 4:1:1.5:1.3; Antichlorine agent 4: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 4, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 2:1:0.5:1.3; Antichlorine agent 5: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 5, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 4:3:1.5:1.3; Antichlorine agent 6: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 6, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 1:1:0.5:1.3; Antichloride 7: Homemade. The difference between it and antichloride 1 is that in the preparation method of antichloride 7, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 5:1:0.5:1.3; Antichlorine agent 8: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 8, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 3:0.5:0.2:1.3; Antichlorine agent 9: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 9, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = 3:4:2:1.3; Antichlorine agent 10: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 10, aminoethanethiol is not added, and the mass ratio of molybdenum disulfide, dicyclohexylcarbodiimide and antioxidant is molybdenum disulfide: dicyclohexylcarbodiimide: antioxidant = 3:0.5:1.3; Antichlorine agent 11: homemade. The difference between it and antichlorine agent 1 is that in the preparation method of antichlorine agent 11, no dicyclohexylcarbodiimide is added, and the mass ratio of molybdenum disulfide, aminoethanethiol and antioxidant is molybdenum disulfide: aminoethanethiol: antioxidant = 3:1:1.3; The antioxidant in the above-mentioned anti-chlorine agent is prepared by mixing commercially available antioxidant 300 and commercially available antioxidant 9228 in a mass ratio of 1:1.

[0035] Examples 1 to 11 and Comparative Examples 1 to 10 Examples 1 to 11 of the present invention and comparative examples 1 to 10 respectively provide a chlorine-resistant polyolefin pipe, wherein the chlorine-resistant polyolefin pipe comprises an inner layer and an outer layer; and the preparation method of the chlorine-resistant polyolefin pipe is as follows: S1. According to the component contents (parts by mass) in Tables 1 to 3, the components of the inner layer were added to a high-speed mixer and mixed uniformly at a speed of 2000 r / min. The mixture was then added to a twin-screw extruder and extruded into granules at 190-220°C at a screw speed of 80 r / min. The mixture was dried to obtain the inner layer material. S2. Add the inner layer material and the outer layer material into a molding machine and perform single-screw co-extrusion at 190-220° C., vacuumize and size, and cool to obtain a semi-finished pipe; S3. Annealing the semi-finished pipe at 110° C. for 30 minutes and naturally cooling it to room temperature to obtain a chlorine-resistant polyolefin pipe, wherein the inner layer thickness of the pipe is 0.8 mm and the outer layer thickness is 1 mm.

[0036] Table 1 Components of the inner layer and their mass parts (the unit of mass parts is: part) Table 2 Components of the inner layer and their mass parts (the unit of mass parts is: part) Table 3 Components of the inner layer and their mass parts (the unit of mass parts is: parts) Performance Testing The pipes provided in the above examples and comparative examples were used as samples for a chloride ion solution immersion test: a chloride ion solution with a concentration of 200 ppm was prepared. Under the conditions of a constant temperature of 60°C and a pH value of 7±0.5, pipes with a length of 30 cm±0.5 cm were immersed in the chloride ion solution. Before immersion and after 120 days of immersion, the inner layer of the pipe was scraped as a sample and the following tests were performed: (1) The oxidation induction time of the sample was tested according to the standard GB / T 19466.6-2009 at a test temperature of 210°C; (2) According to the standard GB / T 6111-2003, the sample is subjected to a hydrostatic test at 95°C for 22 hours. After the test at the standard pressure, the pressure is increased by 5% until the pipe ruptures; For example, a hydrostatic test is conducted at 95°C and standard pressure (1.43MPa). If no cracks appear on the pipe after 22 hours, the holding time at standard pressure is recorded as 22 hours. Then, a hydrostatic test is conducted at 5% pressure (i.e., 1.05 times the standard pressure). If no cracks appear on the pipe after 22 hours, the hydrostatic test is conducted at 10% pressure (i.e., 1.1 times the standard pressure). If cracks appear on the pipe after 5 hours, the test is terminated and the pressurization percentage is recorded as 10%. The holding time after pressurization is recorded as 5 hours. (3) Scanning electron microscope (SEM) is used to test the inner layer of the pipe.

[0037] The test results are shown in Table 4 and Figures 1 and 2 shown.

[0038] Table 4 As shown in Table 4, the chlorine-resistant polyolefin pipes provided by various embodiments of the present invention exhibit excellent comprehensive performance, including chlorine resistance and pressure resistance. Before immersion in a chloride ion solution, the oxidative induction time was no less than 41.2 minutes. During a hydrostatic test, the pressure was increased by no less than 15%, and the pressure was maintained at 15% for no less than 3 hours, with even 25% pressure maintained for 8 hours. After immersion in a chloride ion solution for 120 days, the oxidative induction time was no less than 30.2 minutes. During a hydrostatic test, the pressure was maintained at standard pressure for no less than 18 hours, with even 15% pressure maintained for 5 hours. This demonstrates that a piping system using the polyolefin pipes prepared using the technical solutions of the present invention can operate stably under actual operating conditions with chlorinated tap water.

[0039] Examples 1-4 and Comparative Examples 7-8 show that the chlorine resistance of polyolefin pipes varies depending on the mass ratio of PP-R resin to chlorine resistance agent in the inner layer. Compared with Examples 1-4, Comparative Example 7, where the mass ratio of chlorine resistance agent in the inner layer is too high, significantly reduces the chlorine resistance of the polyolefin pipe and also slightly decreases its pressure resistance. Comparative Example 8, where the mass ratio of chlorine resistance agent in the inner layer is too low, significantly reduces the chlorine resistance of the polyolefin pipe.

[0040] 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 are reduced.

[0041] It can be seen from Example 1, Examples 8 to 11 and Comparative Examples 2 to 6 that, when the mass proportion of the anti-chlorine agent in the inner layer is fixed, changing the mass proportion of each component in the anti-chlorine agent makes the performance of the polyolefin pipe have certain differences; compared with Comparative Examples 2 to 6, Examples 1 and Examples 8 to 11 control the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant to molybdenum disulfide: aminoethanethiol: dicyclohexylcarbodiimide: antioxidant = (2 to 4): (1 to 3): (0.5 to 1 .5):1.3, which can effectively improve the chlorine resistance of the polyolefin pipe while ensuring the pressure resistance of the polyolefin pipe; compared with Examples 9 and 11, the mass ratio of molybdenum disulfide, aminoethanethiol, dicyclohexylcarbodiimide and antioxidant in Examples 1 and Examples 8 and 10 is in the range of molybdenum disulfide:aminoethanethiol:dicyclohexylcarbodiimide:antioxidant = (2~3): (1~2): (0.5~1):1.3, and the comprehensive performance of chlorine resistance and pressure resistance of the polyolefin pipe is better.

[0042] In addition, the inner layer was observed by scanning electron microscopy before immersion and after immersion in chloride ion solution for 120 days. Figure 1 and Figure 2 As shown. Figure 1 and Figure 2 It can be clearly seen that the pipe product prepared by the technical solution of the present invention has no obvious corrosion phenomenon on the inner surface after the chlorine resistance test, which shows that the polyolefin pipe prepared by the technical solution of the present invention has excellent chlorine resistance.

[0043] Finally, it should be noted that the above embodiments are intended to illustrate the technical solutions 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 preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

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

3.

2. The chlorine-resistant polyolefin pipe according to claim 1, characterized in that: The specific surface area of ​​the molybdenum disulfide is 20~40m 2 / g, and the particle size of the molybdenum disulfide is 40~100nm.

3. The chlorine-resistant polyolefin pipe according to claim 1, characterized in that: The preparation method of molybdenum disulfide comprises the following steps: Sodium molybdate dihydrate and thiourea are added to a reaction solvent for reaction, and molybdenum disulfide is obtained after cooling, washing, and drying. The reaction temperature is 160-220° C., and the reaction time is 12-30 hours.

4. The chlorine-resistant polyolefin pipe according to claim 1, characterized in that: The antioxidant includes at least one of a hindered phenol antioxidant and a phosphite antioxidant. The hindered phenol antioxidant includes at least one of antioxidant 300, antioxidant 1076, and antioxidant 1024. The phosphite antioxidant includes at least one of antioxidant 168 and antioxidant 9228.

5. The chlorine-resistant polyolefin pipe according to claim 1, characterized in that: The preparation method of the chlorine-resistant agent comprises the following steps: Molybdenum disulfide and aminoethanethiol are added to an organic solvent, subjected to ultrasonic treatment, and then filtered and washed to obtain a mixture; adding an antioxidant and dicyclohexylcarbodiimide into an organic solvent and dissolving them to obtain a mixed solution; The mixture is added into the mixed solution and stirred, and then centrifuged, washed and dried to obtain the anti-chlorine agent.

6. The chlorine-resistant polyolefin pipe according to claim 5, characterized in that: The temperature of the ultrasonic treatment is 0-5°C, and the time of the ultrasonic treatment is 3-10 hours; And / or, the temperature of the stirring treatment is 50-70° C., the rotation speed of the stirring treatment is 500-1000 r / min, and the time of the stirring treatment is 36-72 h.

7. The chlorine-resistant polyolefin pipe according to claim 1, characterized in that: The outer layer includes at least one of a second PP-R resin and a PP-RCT resin.

8. A method for preparing the chlorine-resistant polyolefin pipe according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, mixing a first PP-R resin and a chlorine-resistant agent and then extruding and granulating the mixture to obtain an inner layer material; S2, co-extruding the inner layer material and the outer layer material, vacuuming and sizing, and cooling to obtain a semi-finished pipe; S3. Annealing and cooling the semi-finished pipe to obtain a chlorine-resistant polyolefin pipe.

9. The method for preparing the chlorine-resistant polyolefin pipe according to claim 8, characterized in that: In step S1, the temperature of the extrusion granulation is 190-220° C., and the screw speed of the extrusion granulation is 30-120 r / min.

10. The method for preparing the chlorine-resistant polyolefin pipe according to claim 8, characterized in that: In step S3, the annealing temperature is 100-110°C.

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