PP-R cold and hot water pipe and preparation method thereof

Abstract

The application belongs to the technical field of polymer materials, and particularly relates to a PP-R cold and hot water pipe and a preparation method thereof. The PP-R cold and hot water pipe provided by the application comprises PP-R resin, composite nucleating agent, impact agent, filler, gamma-aminopropyl triethoxysilane, polyvinyl alcohol, antioxidant and color masterbatch. The reaction product of benzoic anhydride and p-phenylenediamine is reacted with cerium nitrate to generate a diamide carboxylate, which is compounded with calcium pimelate to form a beta nucleating agent, so that the low-temperature plasticity of the PP-R cold and hot water pipe is improved. The low-impact polypropylene is used to wrap modified nano zeolite powder as the impact agent, so that the impact resistance and high-temperature performance of the PP-R cold and hot water pipe are improved. The cooling rate of the PP-R cold and hot water pipe after extrusion molding is controlled, and heat preservation treatment is performed, so that the internal stress of the PP-R cold and hot water pipe is effectively eliminated, and the beta crystal content and crystallization ability are improved. The carbon nanofiber and nano silicon dioxide are selected to jointly form the filler, so that the mechanical properties of the PP-R cold and hot water pipe are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a PP-R cold and hot water pipe and a preparation method thereof. BACKGROUND

[0002] PP-R pipe, also known as three-propylene polypropylene pipe, random copolymer polypropylene pipe or PPR pipe, is a kind of water supply pipe material using random copolymer polypropylene as raw material. Compared with traditional cast iron pipe, galvanized steel pipe and cement pipe, PPR pipe has many advantages such as energy saving and material saving, environmental protection, light weight and high strength, corrosion resistance, smooth inner wall without scaling, simple construction and maintenance, long service life and the like, and is applied to building water supply and drainage, urban and rural water supply and drainage, city gas, power and optical cable sheath, industrial fluid transportation, agricultural irrigation and the like building, municipal, industrial and agricultural fields.

[0003] PPR pipe material has the characteristics of green environmental protection, long service life and good corrosion resistance, but it has significant brittleness at about 0℃, especially the impact strength is not high under low temperature conditions, and the impact strength and tensile strength are poor at high temperature. At present, there are two common methods to improve the cold brittleness of PPR pipe material, one is to put the pipe material into an oven at 115±5℃ for 4h to improve the crystal form of PPR pipe material by annealing, reduce the difference in crystallinity between the inner and outer layers of the pipe material, and reduce the stress difference between the inner and outer layers, so as to achieve the purpose of enhancing the toughness; the other is to add POE elastomer during the processing of PPR pipe material to improve the low temperature impact resistance of PPR pipe material.

[0004] The Chinese patent application file with the application publication number CN111425671A discloses a three-layer co-extrusion antibacterial PP-R water supply pipe, which comprises an antibacterial inner layer, an impact-resistant middle layer and a protective outer layer. The antibacterial inner layer comprises polypropylene, antibacterial agent and impact-resistant agent. The impact-resistant middle layer comprises polypropylene and impact-resistant agent. The protective outer layer comprises polypropylene and light stabilizer. The impact-resistant agent is polyolefin elastomer POE. This kind of PP-R water supply pipe uses polyolefin elastomer POE as impact-resistant agent, and under a certain ratio, the pipe material prepared with other components can improve the impact resistance of the pipe material without losing the static pressure of the pipe material. POE cannot improve the glass transition temperature of PPR, and PPR pipe material may still be brittle and broken in low temperature environment. Although POE can improve the low temperature resistance, the overall cold brittleness of the prepared PP-R water supply pipe is not improved obviously. In low temperature, the pipe material may be damaged during transportation or installation, and the addition of polyolefin elastomer POE will also reduce the pressure resistance and tensile strength of the PP-R water supply pipe. SUMMARY

[0005] In order to solve the technical problems of low-temperature cold brittleness, poor impact strength and high-temperature performance of the PP-R pipe in the prior art, the application provides a PP-R cold and hot water pipe and a preparation method thereof.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0007] A PP-R cold and hot water pipe comprises the following components in parts by weight:

[0008] PP-R resin 50-60 parts, composite nucleating agent 10-15 parts, impact resistance agent 8-12 parts, filler 10-15 parts, gamma-aminopropyl triethoxysilane 8-10 parts, polyvinyl alcohol 5-8 parts, antioxidant 3-5 parts, color masterbatch 3-5 parts.

[0009] The preparation method of the composite nucleating agent is as follows: benzoic anhydride is mixed with tetrahydrofuran, p-phenylenediamine is added, after the reaction is completed, the filter cake is dried and then added into deionized water, after stirring uniformly, heating to 72-76 DEG C, adjusting the pH value to 6.8-7.2, adding cerium nitrate aqueous solution drop by drop, after the precipitation is generated, heat preservation reaction, filtration, washing, drying, adding calcium pimelate, mixing uniformly, and obtaining the composite nucleating agent.

[0010] In the application, the reaction product of benzoic anhydride and p-phenylenediamine is reacted with cerium nitrate to generate diamide carboxylate as the beta nucleating agent of the PP-R resin, which provides external crystal nucleus for the crystallization of the polymer, significantly reduces the size of the polymer, and increases the crystallization temperature of the polymer, so that more beta crystal forms with higher toughness, impact strength and heat distortion temperature are formed in the polymer, the low-temperature toughness of the PP-R is effectively improved, the crystal grain is refined, and the crystallization rate is accelerated. However, it is found through research that only adding diamide carboxylate as the beta nucleating agent can effectively improve the low-temperature brittleness of the PP-R, but the PP-R still has low-temperature brittleness below-5 DEG C, therefore, in the application, diamide carboxylate is compounded with calcium pimelate, so that the prepared PP-R cold and hot water pipe still has good low-temperature plasticity at-15 DEG C. The addition of gamma-aminopropyl triethoxysilane can improve the compatibility of the filler and the PP-R resin, and the polyvinyl alcohol can effectively mix the filler and the PP-R resin uniformly.

[0011] Further, in the preparation method of the composite nucleating agent, the molar ratio of benzoic anhydride to p-phenylenediamine is 1:5-7, and the molar ratio of benzoic anhydride to cerium nitrate is 15-18:1.

[0012] Further, in the preparation method of the composite nucleating agent, the concentration of the cerium nitrate aqueous solution is 0.30-0.35 mol / L.

[0013] Further, in the preparation method of the composite nucleating agent, the molar ratio of calcium pimelate to benzoic anhydride is 1:3-5.

[0014] Further, the preparation method of the impact-resistant agent is as follows: uniformly mixing nano-zeolite powder and petroleum ether, adding polypropylene, mixing for 1.2-1.5 h, standing for layering, drying the filter cake after filtration, and grinding to obtain the impact-resistant agent.

[0015] The zeolite has a layered structure, can induce the generation of shear bands and crazes when the PP-R cold and hot water pipe is impacted, absorbs impact energy, and limits the movement of the PP-R molecular chain, thereby improving the impact resistance and high-temperature performance of the PP-R cold and hot water pipe.

[0016] Further, in the preparation method of the impact-resistant agent, the mass fractions of the components are as follows: 8-10 parts of nano-zeolite powder, 20-30 parts of petroleum ether, and 12-15 parts of polypropylene.

[0017] Further, in the preparation method of the impact-resistant agent, the relative molecular mass of the polypropylene is 500-700; and the mixing is performed by using a high-speed mixer at a rotation speed of 2500-3000 rpm.

[0018] In the application, the polypropylene with a lower relative molecular mass is more likely to coat and modify the nano-zeolite powder, because the increase of the molecular weight of the polypropylene leads to the increase of the number of crystal lattices occupied by a single molecule, the decrease of the total number of molecules, the decrease of the contribution of mixing entropy to the mixing free energy, and the need for a higher temperature for uniform mixing.

[0019] Further, the filler is composed of carbon nanofibers and nano-silica at a mass ratio of 3-5:8-11.

[0020] In the application, the carbon nanofibers and nano-silica are selected to jointly form the filler component, the carbon nanofibers can improve the tensile and bending strength of the PP-R cold and hot water pipe, and the nano-silica can improve the high-temperature performance of the PP-R cold and hot pipe.

[0021] Further, the antioxidant is one of antioxidant 1010, antioxidant 1076, antioxidant T503, and antioxidant T501.

[0022] The application further provides a preparation method of the PP-R cold and hot pipe, which specifically comprises the following steps:

[0023] S1: uniformly mixing PP-R resin, composite nucleating agent, impact-resistant agent, filler, gamma-aminopropyl triethoxysilane, polyvinyl alcohol, antioxidant, and color masterbatch to obtain a mixture;

[0024] S2: the mixture prepared in step S1 is loaded into a twin-screw extruder for melt extrusion, and the extruded material is molded to obtain the PP-R pipe, wherein the extrusion temperature is set as 150-160 DEG C in zone 1, 180-190 DEG C in zone 2, 210-220 DEG C in zone 3, 210-220 DEG C in zone 4, and 220-225 DEG C in zone 5, and the screw rotation speed is set as 300-350 rpm;

[0025] S3: the PP-R pipe prepared in step S2 is cooled to 110-120 DEG C at a speed of 10-15 DEG C / min, and then naturally cooled after being kept at 110-120 DEG C for 2-2.2 h to obtain the PP-R cold and hot water pipe.

[0026] In the present application, the raw materials of the PP-R cold and hot water pipe are mixed and extruded, and then the cooling rate of the pipe is strictly controlled, which can control the crystallization speed of the PP-R, the size and distribution of the spherulites, and has certain influence on the crystallization of the PP-R crystals. The slower the cooling rate is, the higher the crystallization temperature of the crystals is, and the more the content of the beta crystals is. However, excessive beta crystals have great influence on the mechanical properties of the pipe. Therefore, the cooling rate should be controlled within a certain range. When the cooling rate is too fast, there is a large temperature difference between the inner layer and the surface layer of the pipe, which leads to a large internal stress in the pipe, and the impact resistance, compressive strength and bending strength of the pipe prepared are affected. When the cooling rate is slow, the production cycle is prolonged, and the uniformity of the pipe wall thickness is poor. In addition, the pipe is kept at 110-120 DEG C for 2-2.2 h in the present application, which can promote the secondary crystallization of the PP-R resin, improve the crystallinity of the polymer, make the molecular chains of the pipe enter the ordered crystallization state, improve the crystallization ability, eliminate the internal stress of the PP-R cold and hot water pipe, and further improve the mechanical properties of the pipe.

[0027] Compared with the prior art, the PP-R cold and hot water pipe and the preparation method thereof provided by the present application have the following technical advantages:

[0028] (1) In the present application, the reaction product of benzoic anhydride and p-phenylenediamine is reacted with cerium nitrate to form a diamide carboxylate salt, which is compounded with calcium pimelate to form a beta nucleating agent, so that the PP-R cold and hot water pipe prepared still has good low-temperature plasticity at-15 DEG C.

[0029] (2) In the present application, low relative molecular mass polypropylene is used to wrap modified nano-zeolite powder as an impact resistance agent, which effectively improves the impact resistance and high-temperature performance of the PP-R cold and hot water pipe.

[0030] (3) In the present application, the cooling rate of the PP-R cold and hot water pipe after extrusion molding is controlled, and the pipe is kept warm during the cooling process, which effectively eliminates the internal stress of the PP-R cold and hot water pipe, improves the content of beta crystals and the crystallization ability, and effectively improves the mechanical properties of the pipe.

[0031] (4) The present application selects carbon nanofibers and nanosilica to jointly form a filler, which effectively improves the tensile strength, bending strength and high-temperature performance of the PP-R cold and hot water pipe. DETAILED DESCRIPTION

[0032] The present application will be further described below in conjunction with specific examples, but the present application is not limited to the following examples only. Those skilled in the art can make various modifications according to the basic idea of the present application, but as long as the modifications do not deviate from the basic idea of the present application, they are within the scope of the present application.

[0033] Example 1

[0034] A PP-R cold and hot water pipe comprises the following components in parts by weight:

[0035] PP-R resin 60g, composite nucleating agent 10g, impact agent 8g, filler 10g, gamma-aminopropyl triethoxysilane 8g, polyvinyl alcohol 5g, antioxidant 1010 3g, color master 3g;

[0036] The preparation method of the composite nucleating agent is as follows: 1 mol of benzoic anhydride is mixed with 300 mL of tetrahydrofuran, p-phenylenediamine is added, and the reaction is carried out at room temperature for 6 h, then the solid product on the filter paper after filtration is washed with solvent tetrahydrofuran for 3 times, and then placed in a vacuum drying oven at 60℃ for 12 h until the mass of the product no longer changes, then added into 60 mL of deionized water, stirred uniformly, heated to 72℃, and then added dropwise saturated sodium bicarbonate solution to adjust the pH value to 6.8, then added dropwise cerium nitrate aqueous solution with a concentration of 0.30 mol / L, and after the precipitation is generated, the reaction is carried out for 12 h, then filtered, washed with water for 3 times, and then filtered to obtain the solid product, then placed in a vacuum drying oven at 100℃ for 12 h until the mass of the product no longer changes, then added with calcium pimelate, and mixed uniformly to obtain the composite nucleating agent; the molar ratio of benzoic anhydride to p-phenylenediamine is 1:5, and the molar ratio of benzoic anhydride to cerium nitrate is 15:1; the molar ratio of calcium pimelate to benzoic anhydride is 1:3.

[0037] The preparation method of the impact agent is as follows: 8g of nano-zeolite powder is mixed with 20g of petroleum ether uniformly, then 12g of polypropylene with a relative molecular mass of 500 is added, then placed in a high-speed mixer for mixing at 2500 rpm for 1.2 h, then layered after standing, then the filter cake is dried after suction filtration, then ground to obtain the impact agent.

[0038] The filler is composed of carbon nanofibers and nanosilica in a mass ratio of 3:8.

[0039] The preparation method of the PP-R cold and hot pipe material specifically comprises the following steps:

[0040] S1: PP-R resin, composite nucleating agent, impact modifier, filler, gamma-aminopropyl triethoxysilane, polyvinyl alcohol, antioxidant and color masterbatch were mixed in a high-speed mixer to obtain a mixture;

[0041] S2: The mixture prepared in step S1 was loaded into a twin-screw extruder for melt extrusion, and the mold was shaped to obtain a PP-R pipe, wherein the extrusion temperature was set as 150℃ for zone 1, 180℃ for zone 2, 210℃ for zone 3, 210℃ for zone 4, and 220℃ for zone 5, and the screw speed was set as 300 rpm.

[0042] S3: The PP-R pipe prepared in step S2 was cooled to 110℃ at a rate of 10℃ / min, and then naturally cooled after being kept at 110℃ for 2h to obtain a PP-R cold and hot water pipe.

[0043] Example 2

[0044] A PP-R cold and hot water pipe comprises the following components in parts by weight:

[0045] PP-R resin 50g, composite nucleating agent 15g, impact modifier 12g, filler 15g, gamma-aminopropyl triethoxysilane 10g, polyvinyl alcohol 8g, antioxidant 1076 5g, color masterbatch 5g.

[0046] The preparation method of the composite nucleating agent is as follows: 1mol of benzoic anhydride is mixed with 300mL of tetrahydrofuran, and p-phenylenediamine is added, and the reaction is carried out at room temperature for 6h, then the solid product on the filter paper is obtained after filtration and washing with solvent tetrahydrofuran for 3 times, and then the solid product is placed in a vacuum drying oven at 60℃ for 12h until the mass of the product no longer changes, then it is added into 60mL of deionized water, stirred uniformly, heated to 76℃, and then a saturated sodium bicarbonate solution is added dropwise to adjust the pH value to 7.2, and then a cerium nitrate aqueous solution with a concentration of 0.35mol / L is added dropwise, and after the precipitation is generated, the reaction is kept for 12h, then filtered and washed with water for 3 times to obtain a solid product, and then the solid product is placed in a vacuum drying oven at 100℃ for 12h until the mass of the product no longer changes, then calcium pimelate is added and mixed uniformly to obtain the composite nucleating agent; the molar ratio of benzoic anhydride to p-phenylenediamine is 1:6, and the molar ratio of benzoic anhydride to cerium nitrate is 18:1; the molar ratio of calcium pimelate to benzoic anhydride is 1:5.

[0047] The preparation method of the impact modifier is as follows: 10g of nano-zeolite powder is mixed with 30g of petroleum ether uniformly, 15g of polypropylene with a relative molecular mass of 700 is added, and then the mixture is put into a high-speed mixer for mixing at 3000rpm for 1.5h, and then the mixture is left to separate, and then the filter cake is dried, ground and obtained as the impact modifier.

[0048] The filler is composed of carbon nanofibers and nanosilica in a mass ratio of 5:11.

[0049] The preparation method of the PP-R cold and hot pipe material specifically comprises the following steps:

[0050] S1: PP-R resin, composite nucleating agent, impact agent, filler, gamma-aminopropyl triethoxysilane, polyvinyl alcohol, antioxidant and color masterbatch are mixed in a high-speed mixer to obtain a mixture;

[0051] S2: The mixture obtained in step S1 is loaded into a double-screw extruder for melt extrusion, and a mold is formed to obtain a PP-R pipe material, wherein the extrusion temperature is set as 160 DEG C in zone 1, 190 DEG C in zone 2, 220 DEG C in zone 3, 220 DEG C in zone 4 and 225 DEG C in zone 5, and the screw rotation speed is set as 350 rpm;

[0052] S3: The PP-R pipe material obtained in step S2 is cooled to 120 DEG C at a speed of 15 DEG C / min, and then naturally cooled after being kept at 120 DEG C for 2.2 h to obtain a PP-R cold and hot water pipe.

[0053] Example 3

[0054] A PP-R cold and hot water pipe comprises the following components in parts by weight:

[0055] PP-R resin 56g, composite nucleating agent 13g, impact agent 11g, filler 12g, gamma-aminopropyl triethoxysilane 9g, polyvinyl alcohol 7g, antioxidant T503 4g and color masterbatch 4g;

[0056] The preparation method of the composite nucleating agent is as follows: 1 mol of benzoic anhydride is mixed with 300 mL of tetrahydrofuran, and p-phenylenediamine is added, and the mixture is reacted at room temperature for 6 h, filtered, washed with solvent tetrahydrofuran for 3 times, and then the solid product on the filter paper is obtained, placed in a vacuum drying oven at 60 DEG C for 12 h until the mass of the product no longer changes, then added into 60 mL of deionized water, stirred uniformly, heated to 75 DEG C, and then a saturated sodium bicarbonate solution is added dropwise to adjust the pH value to 7.0, and then a cerium nitrate aqueous solution with a concentration of 0.32 mol / L is added dropwise, and after the precipitation is generated, the reaction is kept for 12 h, filtered, washed with water for 3 times, and then the solid product is obtained, and then placed in a vacuum drying oven at 100 DEG C for 12 h until the mass of the product no longer changes, and then calcium pimelate is added and mixed uniformly to obtain the composite nucleating agent; the molar ratio of benzoic anhydride to p-phenylenediamine is 1:7, and the molar ratio of benzoic anhydride to cerium nitrate is 16:1; the molar ratio of calcium pimelate to benzoic anhydride is 1:4.

[0057] The preparation method of the impact agent is as follows: 9 g of nano-zeolite powder is uniformly mixed with 25 g of petroleum ether, 14 g of polypropylene with a relative molecular mass of 600 is added, and then the mixture is placed in a high-speed mixer and mixed at 2800 rpm for 1.4 h, and then the mixture is allowed to stand and stratify, and then the filter cake is dried, ground and obtained to obtain the impact agent.

[0058] The filler is composed of carbon nanofibers and nanosilica in a mass ratio of 4:9.

[0059] The preparation method of the PP-R cold and hot pipe material specifically comprises the following steps:

[0060] S1: PP-R resin, composite nucleating agent, impact agent, filler, gamma-aminopropyl triethoxysilane, polyvinyl alcohol, antioxidant and color masterbatch are added into a high-speed mixer and uniformly mixed to obtain a mixture;

[0061] S2: The mixture prepared in step S1 is loaded into a twin-screw extruder for melt extrusion, and a mold is formed to obtain a PP-R pipe material, wherein the extrusion temperature is set as 155℃ for zone 1, 185℃ for zone 2, 215℃ for zone 3, 215℃ for zone 4, and 223℃ for zone 5 in sequence, and the screw rotation speed is set as 320 rpm;

[0062] S3: The PP-R pipe material prepared in step S2 is cooled to 117℃ at a speed of 13℃ / min, and then naturally cooled after being kept at 117℃ for 2.1h to obtain a PP-R cold and hot water pipe.

[0063] Comparative Example 1

[0064] The raw material composition and preparation method of the PP-R cold and hot water pipe in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that an equal amount of hexahydrophthalic anhydride is used instead of benzoic anhydride in the preparation method of the composite nucleating agent of the present comparative example.

[0065] Comparative Example 2

[0066] The raw material composition and preparation method of the PP-R cold and hot water pipe in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that an equal amount of calcium adipate is used instead of calcium pimelate in the preparation method of the composite nucleating agent of the present comparative example.

[0067] Comparative Example 3

[0068] The raw material composition and preparation method of the PP-R cold and hot water pipe in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that no calcium pimelate is added in the preparation method of the composite nucleating agent of the present comparative example.

[0069] Comparative Example 4

[0070] The raw material composition and preparation method of the PP-R cold and hot water pipe in the present comparative example are similar to those in Example 3, and the difference between the present comparative example and Example 3 is that an equal amount of petroleum ether is used instead of polypropylene in the preparation method of the impact agent of the present comparative example.

[0071] Comparative Example 5

[0072] The raw material composition and preparation method of the PP-R hot and cold water pipe in the present comparative example are similar to those of Example 3. The difference between the present comparative example and Example 3 is that the filler in the present comparative example is nano-silica.

[0073] Comparative Example 6

[0074] The raw material composition and preparation method of the PP-R hot and cold water pipe in the present comparative example are similar to those of Example 3. The difference between the present comparative example and Example 3 is that the filler in the present comparative example is carbon nanofiber.

[0075] Comparative Example 7

[0076] The raw material composition and preparation method of the PP-R hot and cold water pipe in the present comparative example are similar to those of Example 3. The difference between the present comparative example and Example 3 is that the cooling rate in step S3 of the preparation method of the PP-R hot and cold water pipe in the present comparative example is 30℃ / min.

[0077] Comparative Example 8

[0078] The raw material composition and preparation method of the PP-R hot and cold water pipe in the present comparative example are similar to those of Example 3. The difference between the present comparative example and Example 3 is that the preparation method of the PP-R hot and cold water pipe in the present comparative example does not perform heat preservation treatment in step S3. Specifically, the PP-R pipe material prepared in step S2 is cooled to 117℃ at a rate of 13℃ / min, and then naturally cooled to obtain the PP-R hot and cold water pipe.

[0079] Test Example

[0080] Low-temperature impact resistance performance test: The notched impact strength of the PP-R hot and cold water pipe material prepared in Example 1-Example 3, Comparative Example 1-Comparative Example 3, Comparative Example 7, Comparative Example 8 was tested at -15℃, -5℃ and 0℃ according to ISO 180:2022-05, respectively. The test results are shown in Table 1.

[0081] Mechanical property test: The tensile strength of the PP-R hot and cold water pipe material prepared in Example 1-Example 3, Comparative Example 4-Comparative Example 8 was tested at 25℃ and 70℃ according to GB / T 1040-2006, the impact strength of the PP-R hot and cold water pipe material prepared in Example 1-Example 3, Comparative Example 4-Comparative Example 8 was tested according to GB / T 1043.1-2008, and the bending strength of the PP-R hot and cold water pipe material prepared in Example 1-Example 3, Comparative Example 4-Comparative Example 8 was tested according to GB / T9341-2008. The test results are shown in Table 2.

[0082] Hydrostatic test: rigid performance test was carried out on the PP-R cold and hot water pipes prepared in Example 1-Example 3 according to GB / T 6111-2018, specifically: whether the PP-R pipe was broken or leaked under the conditions of 20℃, 18MPa ring stress for 1h and 95℃, 4.5MPa ring stress for 22h was observed, and the test results are shown in Table 3.

[0083] Table 1 Low-temperature impact resistance test

[0084]

[0085] As can be seen from Table 1, the notched impact strength of the PP-R cold and hot water pipe prepared by the application is 9.3-9.8 kgf cm / cm at-15℃, 67.2-70.4 kgf cm / cm at-5℃, and 143.1-149.5 kgf cm / cm at 0℃, which fully shows that the PP-R cold and hot water pipe provided by the application still has good impact resistance at low temperature.

[0086] Compared with Example 3, the preparation method of the composite nucleating agent in Comparative Example 1 uses an equal amount of hexahydrophthalic anhydride instead of benzoic anhydride, but the low-temperature impact resistance of the pipe prepared has decreased to varying degrees, which shows that the effect of the diamide carboxylate prepared from hexahydrophthalic anhydride as a β nucleating agent is not as good as that of the diamide carboxylate prepared from benzoic anhydride; the preparation method of the composite nucleating agent in Comparative Example 2 uses an equal amount of calcium adipate instead of calcium pimelate, but the low-temperature impact resistance of the pipe prepared has decreased to varying degrees, which shows that the effect of calcium adipate and diamide carboxylate is obviously not as good as that of calcium pimelate and diamide carboxylate; the preparation method of the composite nucleating agent in Comparative Example 3 does not add calcium pimelate, but the impact resistance of the pipe prepared at-15℃ is significantly reduced, which shows that the compounding of calcium pimelate as a β nucleating agent and diamide carboxylate can effectively improve the impact resistance of the pipe at low temperature; the cooling rate in step S3 of the preparation method of the PP-R cold and hot water pipe in Comparative Example 7 is increased, but the impact resistance of the pipe prepared has decreased to varying degrees, which shows that a slower cooling rate can promote the generation of β crystals, reduce the internal stress of the pipe, and thus improve the low-temperature impact resistance; the pipe prepared in Comparative Example 8 does not undergo heat preservation treatment in step S3 of the preparation method of the PP-R cold and hot water pipe, but the impact resistance of the pipe prepared has decreased to varying degrees, which shows that the heat preservation process can improve the crystallinity of the polymer of the pipe and eliminate the internal stress of the pipe, thereby improving the low-temperature impact resistance.

[0087] Table 2 Mechanical property test results

[0088]

[0089] As shown in Table 2, the PP-R cold and hot water pipe provided by the application has good tensile strength, impact strength and bending strength at 25 DEG C and 70 DEG C, which indicates that the PP-R cold and hot water pipe provided by the application has good mechanical properties.

[0090] Compared with Example 3, the preparation method of the impact resistant agent of Comparative Example 4 uses an equal amount of petroleum ether instead of polypropylene, but the impact strength at room temperature and the high-temperature mechanical properties of the pipe material prepared are both poor, because the nano zeolite powder is not coated and modified by polypropylene in this comparative example, which leads to uneven distribution of the nano zeolite powder in the pipe material, and further affects the impact strength and high-temperature mechanical properties; the filler of Comparative Example 5 is nano silicon dioxide, but the mechanical properties of the pipe material prepared at room temperature are poor, and the high-temperature mechanical properties are slightly increased, and the filler of Comparative Example 6 is carbon nanofiber, but the mechanical properties at room temperature are slightly increased, and the high-temperature mechanical properties are poor, which indicates that the carbon nanofiber in the filler can effectively improve the room temperature properties of the pipe material, and the nano silicon dioxide can improve the high-temperature properties of the pipe material; the preparation method of the PP-R cold and hot water pipe of Comparative Example 7 increases the cooling rate in step S3, but the mechanical properties of the pipe material prepared are poor, which is due to the large internal stress of the pipe material caused by the too fast cooling speed; the preparation method of the PP-R cold and hot water pipe of Comparative Example 8 does not perform heat preservation treatment in step S3, but the mechanical properties of the pipe material prepared are poor, which indicates that the heat preservation process can promote the secondary crystallization of the PP-R resin, and eliminate the internal stress of the PP-R cold and hot water pipe, and further improve the mechanical properties of the pipe material.

[0091] Table 3: Static liquid pressure test results

[0092]

[0093] As shown in Table 3, the PP-R cold and hot water pipe provided by the application performs well in the room temperature and high-temperature static liquid pressure test, which indicates that it has good high-temperature pressure resistance.

[0094] The above examples are only examples of the application, and not limit the application. Those skilled in the art can modify the above examples without departing from the spirit and scope of the application. All equivalent modifications or changes made by those skilled in the art without departing from the technical idea of the application still fall within the protection scope of the application.

Claims

1. A PP-R hot and cold water pipe, characterized by, Comprise the following components by weight parts: PP-R resin 50-60 parts, composite nucleating agent 10-15 parts, impact modifier 8-12 parts, filler 10-15 parts, gamma-aminopropyl triethoxysilane 8-10 parts, polyvinyl alcohol 5-8 parts, antioxidant 3-5 parts, color mother 3-5 parts; The preparation method of the composite nucleating agent is: mixing benzoic anhydride and tetrahydrofuran, adding p-phenylenediamine, filtering after reaction, drying the filter cake, adding deionized water, stirring uniformly, heating to 72-76℃, adjusting the pH value to 6.8-7.2, adding cerium nitrate aqueous solution drop by drop, incubating after precipitation, filtering, washing, drying, adding calcium pimelate, mixing uniformly, and obtaining the composite nucleating agent; The preparation method of the PP-R cold and hot water pipe comprises the following steps: S1: uniformly mix PP-R resin, composite nucleating agent, impact modifier, filler, gamma-aminopropyl triethoxysilane, polyvinyl alcohol, antioxidant and color mother to obtain a mixture; S2: melt extrude the mixture prepared in step S1 in a twin-screw extruder, mold forming to obtain a PP-R pipe, and the extrusion temperature is set as follows: 1 zone 150-160℃, 2 zone 180-190℃, 3 zone 210-220℃, 4 zone 210-220℃, 5 zone 220-225℃, and the screw speed is set as 300-350rpm; S3: cool the PP-R pipe prepared in step S2 to 110-120℃ at a speed of 10-15℃ / min, incubate for 2-2.2h, and then naturally cool, to obtain the product; The filler is composed of carbon nanofiber and nanosilica in a mass ratio of 3-5:8-11; The preparation method of the impact modifier is: uniformly mixing nanometer zeolite powder and petroleum ether, adding polypropylene, mixing for 1.2-1.5h, standing for stratification, filtering and drying the filter cake, and grinding to obtain the impact modifier.

2. The PP-R hot and cold water pipe according to claim 1, characterized in that, The molar ratio of benzoic anhydride to p-phenylenediamine in the preparation method of the composite nucleating agent is 1:5-7, and the molar ratio of benzoic anhydride to cerium nitrate is 15-18:

1.

3. The PP-R hot and cold water pipe according to claim 1, characterized in that, The concentration of the cerium nitrate aqueous solution in the preparation method of the composite nucleating agent is 0.30-0.35mol / L.

4. The PP-R hot and cold water pipe according to claim 1, characterized in that, The molar ratio of calcium pimelate to benzoic anhydride in the preparation method of the composite nucleating agent is 1:3-5.

5. The PP-R hot and cold water pipe according to claim 1, characterized in that, The mass parts of each component in the preparation method of the impact modifier are: nanometer zeolite powder 8-10 parts, petroleum ether 20-30 parts, and polypropylene 12-15 parts.

6. The PP-R hot and cold water pipe according to claim 5, characterized in that, The relative molecular mass of the polypropylene is 500-700; the mixing is performed by a high-speed mixer at a speed of 2500-3000rpm.

7. The PP-R hot and cold water pipe according to claim 1, characterized in that, The antioxidant is one of antioxidant 1010, antioxidant 1076, antioxidant T503 and antioxidant T501.

Images