Chlorine-resistant polyolefin pipe and method for processing the same

Abstract

The present application relates to a kind of chlorine-resistant polyolefin pipes and its processing method, belong to pipeline processing technical field.To solve the problem of poor chlorine resistance of existing, provide a kind of chlorine-resistant polyolefin pipe and its processing method, the pipe includes outer layer and inner layer, inner layer is made of chlorine-resistant polyolefin material, chlorine-resistant polyolefin material includes the following mass percentage of component composition:PPRCT:98%~99.9%;Modified magnesium-aluminum hydrotalcite composite material:0.1%~2.0%;The crystallinity of the beta crystal of PPRCT is 60%~80%, the method includes that after the above-mentioned material is mixed, inner layer material is co-extruded with the outer layer material, after cooling, it is placed in the condition that temperature is 100 ℃~110 ℃ and is annealed to obtain chlorine-resistant polyolefin pipe.Effectively improve the erosion of material itself to chlorine water and other chlorine-containing liquids, prevent the migration of antioxidant, improve chlorine resistance.

Description

TECHNICAL FIELD

[0001] The application relates to a chlorine-resistant polyolefin pipeline and a processing method thereof, and belongs to the technical field of pipeline processing. BACKGROUND

[0002] With the reconstruction of urban drinking water pipelines, plastic pipes have a high proportion in water pipes for transporting drinking water due to their light weight, corrosion resistance, environmental protection and other advantages. In particular, PPRCT pipes have the advantages of energy saving, environmental protection, light weight, high strength, smooth inner wall, easy scaling, simple construction and maintenance, long service life and the like, and are widely used in the field of drinking water pipelines. In addition, people have higher and higher requirements for the quality of drinking water, and in order to prevent water-borne diseases, drinking water is generally disinfected by chlorination. However, according to relevant research, it has been found that a chlorine-containing aqueous solution can accelerate the aging of polyolefin materials, and the greater the concentration, the faster the aging speed. Therefore, the chlorine component in tap water can cause the inner wall of polypropylene and other polyolefin pipes to age, form fine cracks, cause the inner wall of the pipe to be attacked by more oxidative substances, accelerate the aging of the pipe material, and cause brittle rupture, thereby greatly reducing the service life. At the same time, the antioxidants added to the pipeline raw material to slow down the aging of the material have a migration property in the polyolefin body, and the rupture of the pipeline also makes part of the antioxidants migrate to the surface of the pipe material before they can play their role, and are lost under the action of water flow. Therefore, the research on the chlorine resistance of plastic pipes has also attracted widespread attention.

[0003] The existing chlorine-resistant polypropylene pipes generally use antioxidants, acid removers, chlorine-resistant polymers and the like to improve the chlorine resistance of the pipes. For example, Chinese Patent Application (Publication No. CN116444898A) discloses forming a chlorine-resistant agent by grafting polypropylene with sodium benzenesulfonate, and then blending the chlorine-resistant agent with polypropylene to produce a chlorine-resistant pipe; and Chinese Patent Application (Publication No. CN111100348B) discloses using a long-chain ether aromatic compound as a chlorine-resistant agent, and blending the chlorine-resistant agent with polyolefin to produce a chlorine-resistant polyolefin pipe. Although these methods can improve the chlorine resistance of the inner layer material of the pipe to some extent, the ordinary PPRCT used in the existing PPRCT pipes is an alpha crystal, which has large crystal grains and relatively low crystallinity, so that the amorphous region is more susceptible to attack by active chlorine, the chlorine resistance is poor, the antioxidants are consumed quickly, the durability of the material is reduced, the polypropylene base material itself is still susceptible to attack by chlorine-containing compounds, and the migration of antioxidants after the pipe is eroded by chlorine also causes the pipe to lose its overall anti-aging performance, and the overall chlorine resistance is also insufficient. SUMMARY

[0004] The application provides a chlorine-resistant polyolefin pipeline and a processing method thereof, and solves the problem of improving the chlorine resistance of the pipeline.

[0005] One of the purposes of the present application is achieved by the following technical solution, a chlorine-resistant polyolefin pipeline, the pipeline comprising an outer layer and an inner layer, the inner layer being made of a chlorine-resistant polyolefin material, characterized in that the chlorine-resistant polyolefin material comprises the following mass percentage composition:

[0006] PPRCT: 98% to 99.9%; modified magnesium-aluminum hydrotalcite composite material: 0.1% to 2.0%, the modified magnesium-aluminum hydrotalcite composite material being formed by anion surfactant and antioxidant intercalated magnesium-aluminum hydrotalcite, the mass ratio of magnesium-aluminum hydrotalcite: anion surfactant: antioxidant in the modified magnesium-aluminum hydrotalcite composite material being 1.0 to 1.5: 0.25 to 0.5: 2; the crystallinity of the β crystal of the PPRCT being 60% to 80%.

[0007] The present application is found in the research on the chlorine resistance of the pipeline that by controlling the crystallinity of the β crystal (β crystal form) in the PPRCT base material used to be 60% to 80%, the relative area of the amorphous region is reduced, that is, the probability of the material itself being attacked by active chlorine is reduced, the destruction speed of the molecular structure of the material itself is slowed down, the erosion of the material itself by chlorine water and other chlorine-containing liquids is effectively improved, the loss phenomenon caused by the rupture of the inner wall of the pipeline and other factors due to the erosion of the antioxidant is effectively reduced, the overall effective time is improved, and the service life is improved. As a more preferred solution, the crystallinity of the β crystal (β crystal form) is controlled to be 65% to 75%; at the same time, by modifying the magnesium-aluminum hydrotalcite with antioxidant and anion surfactant, the antioxidant is intercalated into the interlayer of the magnesium-aluminum hydrotalcite, the chemical bond between the antioxidant and the magnesium-aluminum hydrotalcite is formed, the intercalation in the interlayer is more stable, the migration of the antioxidant is effectively prevented to avoid loss, and the role of the antioxidant can be maximized; the chlorine-containing components adsorbed on the surface of the pipe material or in the interlayer can also be adsorbed by the modified magnesium-aluminum hydrotalcite, and the adsorbed chlorine-containing components can be eliminated by the internal antioxidant, thereby more effectively avoiding the erosion of chlorine, thereby improving the chlorine resistance of the inner layer of the pipeline; at the same time, by intercalating the anion surfactant, the surface energy of the aluminum-magnesium hydrotalcite can be effectively reduced, which is beneficial to the uniform dispersion of the aluminum-magnesium hydrotalcite in the polyolefin base material, and the chlorine ion attack resistance of the polyolefin base material is more effectively assisted, thereby improving the overall chlorine resistance.

[0008] In the above chlorine-resistant polyolefin pipe, as a preferred, the antioxidant is selected from one or two of antioxidant 1010 and antioxidant 1076. By using the effective component 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid group in the above antioxidant to bond to the interlayer of magnesium-aluminum hydrotalcite, the binding stability in the interlayer is improved, the above characteristics of intercalation structure can effectively avoid the migration of antioxidant, prevent its rapid loss, and cooperate with the chlorine ion adsorption performance of magnesium-aluminum hydrotalcite itself, which can further assist the chlorine ion attack resistance of polyolefin material and improve the overall chlorine resistance.

[0009] In the above chlorine-resistant polyolefin pipe, as a preferred, the anionic surfactant is selected from one or several of sodium naphthenate, sodium dodecylbenzenesulfonate, sodium hexadecanoate and sodium silicate. The use of long-chain anionic surfactants can more effectively reduce the surface energy of magnesium-aluminum hydrotalcite, so that the modified material can be more uniformly dispersed in the polyolefin matrix material, and the auxiliary function of improving chlorine resistance is more beneficial.

[0010] In the above chlorine-resistant polyolefin pipe, as a preferred, the magnesium-aluminum hydrotalcite is pre-calcined at a temperature of 400-500°C. By pre-calcining, the magnesium-aluminum hydrotalcite has a structure memory effect, and after intercalation of antioxidants and anionic surfactants, a double-layer structure can be re-acquired, avoiding changes in the structure after intercalation affecting performance. The calcination treatment can also more effectively improve the intercalation effect and the overall chlorine adsorption performance of the material, improve the ability to eliminate chlorine ions, and improve the chlorine resistance.

[0011] In the above chlorine-resistant polyolefin pipe, as a preferred, the crystal grain size of the PPRCT is controlled to be 0.9-10 μm. Small crystal grain size can better improve the uniformity of the crystal, thereby reducing the relative area of the non-crystalline region, more effectively avoiding the destruction of the PPRCT matrix material by active chlorine attack, and better improving the chlorine resistance.

[0012] In the above chlorine-resistant polyolefin pipe, as a preferred, the outer layer is mainly made of PPR, PE or PERT material. By using the above materials, the inner and outer layers can be better formed by co-extrusion during processing to form the corresponding chlorine-resistant polyolefin composite pipe.

[0013] The second object of the present application is achieved by the following technical scheme, a processing method of a chlorine-resistant polyolefin pipe, the pipe is co-extruded by inner layer material and outer layer material, characterized in that, the method further comprises the following steps:

[0014] A, mixing the antioxidant and anionic surfactant in alkaline aqueous solution, and controlling the pH value of the system to 9-11 to form an anionic surfactant solution; then adding and mixing magnesium-aluminum hydrotalcite to obtain modified magnesium-aluminum hydrotalcite composite material after intercalation and compounding of the anionic surfactant and the antioxidant, the mass ratio of the magnesium-aluminum hydrotalcite:anionic surfactant:antioxidant being 1.0-1.5:0.25-0.5:2;

[0015] B, mixing the obtained modified magnesium-aluminum hydrotalcite composite material with PPRCT, and controlling the temperature at 190-210℃ to perform extrusion granulation to obtain the inner layer material, the mass ratio of the PPRCT to the modified magnesium-aluminum hydrotalcite composite material being 98-99.9:0.1-2.0;

[0016] C, adding the inner layer material and the outer layer material to perform co-extrusion in a pipe forming device, and cooling to obtain the corresponding composite pipe semi-finished product;

[0017] D, annealing the composite pipe semi-finished product at a temperature of 100-110℃, and cooling after the end to obtain the corresponding chlorine-resistant polyolefin pipe.

[0018] The antioxidant and the anionic surfactant can enter the interlayer of the magnesium-aluminum hydrotalcite by modifying the magnesium-aluminum hydrotalcite first, mixing the antioxidant and the anionic surfactant with the magnesium-aluminum hydrotalcite, and controlling the pH value of the system in the alkaline condition of 9-11, and the effective component 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid group in the antioxidant can form a chemical bond bonding structure with the magnesium-aluminum hydrotalcite, so that the migration of the antioxidant is effectively prevented, the loss is avoided, and the function of the antioxidant can be maximally exerted; meanwhile, the addition of the anionic surfactant can more effectively improve the surface energy of the magnesium-aluminum hydrotalcite, which is beneficial to the uniform dispersion of the magnesium-aluminum hydrotalcite in the polyolefin matrix material and improves the overall chlorine resistance; then, the inner layer material of the pipeline is obtained by blending and extruding the PPRCT main base material, the inner layer material and the outer layer material are co-extruded to form a pipeline semi-finished product by a molding equipment, and the pipeline is cooled after being formed by co-extrusion to complete the overall processing of the pipeline; however, it is found in the research process that, due to the fast cooling process of the pipe material in the molding process, the chlorine resistance of the pipe material cannot meet the requirements due to the imperfect crystallization of the PPRCT. Therefore, the semi-finished pipeline is annealed by heating, and the temperature is controlled at 100-110 DEG C, so as to change the crystal form of the PPRCT material and make the crystallization of the material change, so that the beta crystal form is formed, the overall crystallinity can reach 60-80%, and the grain size is relatively fine, so that the chlorine resistance of the material itself is improved, the chlorine-resistant polyolefin pipeline formed by processing has excellent chlorine resistance, and the migration and loss of the antioxidant can be better avoided, and the stability and service life of the chlorine resistance are improved.

[0019] The alkaline aqueous solution in step A can be a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, and the system is controlled in the alkaline condition, and the pH value of the system can be adjusted by using the above-mentioned alkaline aqueous solution, or a sodium carbonate aqueous solution or a potassium carbonate aqueous solution can be used for adjusting.

[0020] In the processing method of the chlorine-resistant polyolefin pipeline, as preferred, the magnesium-aluminum hydrotalcite in step A is obtained by the following method:

[0021] The soluble aluminum salt and the soluble magnesium salt are dissolved in water, the molar ratio of Al 3+ and (Al 3+ + Mg 2+ ) in the solution is 1:4-1:2, and urea is added. 3+ 2+ ​The molar ratio of the soluble aluminum salt and the soluble magnesium salt is 3:1 to 4:1, the reaction is carried out at a temperature of 100°C to 120°C, after the reaction, the product is filtered, washed and dried to obtain nanoscale magnesium-aluminum hydrotalcite. The magnesium-aluminum hydrotalcite prepared in this way is nanoscale, has excellent interlayer structure effect, and is more conducive to the intercalation of the antioxidant and the anionic surfactant, thereby improving the chlorine resistance and durability. The soluble aluminum salt and the soluble magnesium salt can be soluble inorganic salts such as aluminum chloride and magnesium chloride. As a further preferred embodiment, the reaction time is 35h to 40h.

[0022] In the above method for processing the chlorine-resistant polyolefin pipe, as a preferred embodiment, the magnesium-aluminum hydrotalcite is subjected to a calcination treatment at a temperature of 400°C to 500°C for 2h to 4h. By pre-calcination, the magnesium-aluminum hydrotalcite has a structure memory effect, and after the intercalation of the antioxidant and the anionic surfactant, the double-layer structure can be re-acquired. The calcination treatment can more effectively improve the intercalation effect and the chlorine adsorption performance of the material as a whole, improve the chlorine ion elimination capacity, and achieve the chlorine resistance. As a further preferred embodiment, the calcination temperature is 450°C to 480°C.

[0023] In the above method for processing the chlorine-resistant polyolefin pipe, as a preferred embodiment, the annealing treatment in step D is as follows:

[0024] The composite pipe semi-finished product is subjected to a heat preservation treatment at a temperature of 100°C to 102°C for 30min to 40min, and then subjected to a heat preservation treatment at a temperature of 110°C to 115°C for 30min to 60min, and after the treatment, the product is naturally cooled to room temperature. By the more precise annealing treatment, the crystal form in the PPRCT can be more effectively improved, and more effectively converted into the β crystal form. The overall β crystal crystallinity can reach 60% to 80%, and the crystal grain size is relatively fine, thereby improving the chlorine resistance of the material itself.

[0025] In summary, compared with the prior art, the present application has the following advantages:

[0026] 1. By controlling the β crystal crystallinity in the PPRCT matrix material to be 60% to 80%, the relative area of the amorphous region is reduced, the probability of the polyolefin material itself being attacked by active chlorine is reduced, the molecular structure damage speed is slowed down, the material itself is effectively improved to resist the erosion of chlorine water and other chlorine-containing liquids, and the chlorine resistance is improved.

[0027] 2. By modifying the magnesium-aluminum hydrotalcite with the antioxidant and the anionic surfactant, the antioxidant can form a chemical bond with the hydrotalcite in the interlayer of the magnesium-aluminum hydrotalcite, effectively preventing the migration of the antioxidant, maximizing its effect, avoiding loss, and improving the chlorine resistance.

[0028] 3. In the method of the present invention, by re-annealing the formed semi-finished pipe and controlling the temperature at 100℃~110℃, the crystal form of PPRCT material can be changed again, so that it can form a β crystal form, and the overall crystallinity can reach 60%~80%, and the grain size is also finer, thereby improving the chlorine resistance of the material itself. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below through specific embodiments, but the present invention is not limited to these embodiments.

[0030] Example 1

[0031] This chlorine-resistant polyolefin pipe comprises an outer layer and an inner layer, which are co-extruded using molding equipment. The inner layer is made of chlorine-resistant polyolefin material, and more importantly, the chlorine-resistant polyolefin material comprises the following components by mass percentage:

[0032] PPRCT: 99.6%; Modified magnesium-aluminum hydrotalcite composite material: 0.4%. The modified magnesium-aluminum hydrotalcite composite material is composed of anionic surfactant and antioxidant intercalated magnesium-aluminum hydrotalcite. The mass ratio of magnesium-aluminum hydrotalcite: anionic surfactant: antioxidant in the modified magnesium-aluminum hydrotalcite composite material is 1:0.25:2. The crystallinity of the β crystals of the above PPRCT is 75%. The anionic surfactant is sodium dodecylbenzenesulfonate, and the antioxidant is antioxidant 1010. The magnesium-aluminum hydrotalcite is nanoscale and has been calcined at 400℃~500℃ beforehand.

[0033] The chlorine-resistant polyolefin pipes described above can be manufactured using the following processing methods:

[0034] Preparation of magnesium aluminum hydrotalcite by urea method: Aluminum chloride and magnesium chloride are dissolved in ultrapure water in a certain proportion to form a corresponding solution, so that the Al in the solution... 3+ With (Al) 3+ +Mg 2+ The molar ratio of urea to (Al) is 1:4 to 1:2 (equivalent to 0.25 to 0.45), and then urea is added to make the urea react with (Al) in a certain way. 3+ +Mg 2+ The molar ratio of the two components is 3:1 to 4:1 (equivalent to 3 to 4). The mixture is then heated to 100℃ to 120℃ and refluxed for 35 to 40 hours. After reflux, the mixture is filtered and washed with ultrapure water to remove residual chlorides. The resulting wet filter cake is dried to constant weight under vacuum at 60℃ to obtain nano-sized magnesium aluminum hydrotalcite.

[0035] Preparation of modified Mg-Al hydrotalcite composite: The obtained nano-sized Mg-Al hydrotalcite was calcined in a muffle furnace at 400-500°C for 4h and was ready for use;

[0036] According to the above-mentioned component dosage ratio in the chlorine-resistant polyolefin material, the antioxidant 1010 was dissolved in 0.1 mol / L sodium hydroxide aqueous solution, then the long-chain anionic surfactant sodium dodecyl benzene sulfonate was added, and the mixture was uniformly mixed to form an anionic aqueous solution. The pH value of the system was adjusted to 9-11, and then the above-mentioned pre-calcined nano-sized Mg-Al hydrotalcite was added. The mixture was stirred at room temperature for 36h, filtered, washed with purified water, and then the obtained solid wet product was dried to constant weight at 60°C under vacuum to obtain the modified Mg-Al hydrotalcite composite after intercalation of surfactant and antioxidant.

[0037] Inner layer material of chlorine-resistant polyolefin pipe: The modified Mg-Al hydrotalcite composite with a mass percentage of 0.4% and PPRCT raw material with a mass percentage of 99.6% were added to a granulator and uniformly mixed under high-speed stirring (800r / min-1200r / min), and the temperature was controlled at 190°C-210°C for extrusion granulation. After drying, the inner layer material of chlorine-resistant polyolefin pipe was obtained.

[0038] Polyolefin pipe processing: The above-mentioned inner layer material and outer layer material were added to a molding machine for co-extrusion to form a double-layer composite pipe, i.e. the outer layer material of the pipe was PPR or PE or PERT, and the inner layer material of the pipe was the above-mentioned inner layer material of chlorine-resistant polyolefin pipe. The co-extrusion molding temperature was controlled between 190°C and 210°C, and the inner layer thickness was controlled between 0.6 and 1mm to obtain the corresponding composite pipe semi-finished product.

[0039] Annealing and crystallization: The obtained composite pipe semi-finished product was placed in an oven with uniform temperature and controllable temperature rise and fall (the equipment temperature difference was not more than 5°C). The temperature was uniformly raised to 100°C within 30min, and the temperature was controlled at this temperature for 20min. Then the temperature was uniformly raised to 110°C within 10min, and the temperature was controlled at this temperature for 60min. After the end, the oven was removed and naturally cooled to room temperature to obtain the annealed chlorine-resistant polyolefin pipe. The crystallinity of the β crystal of the inner layer PPRCT was 75%.

[0040] Example 2

[0041] The chlorine-resistant polyolefin pipe includes an outer layer and an inner layer. The outer layer and the inner layer of the pipe are co-extruded by a molding device. The inner layer is made of chlorine-resistant polyolefin material. More importantly, the chlorine-resistant polyolefin material includes the following components in the following mass percentages:

[0042] PPRCT: 99.9%; modified Mg-Al hydrotalcite composite material: 0.1%, the modified Mg-Al hydrotalcite composite material is prepared by intercalating Mg-Al hydrotalcite with anionic surfactant and antioxidant, the mass ratio of Mg-Al hydrotalcite: anionic surfactant: antioxidant in the modified Mg-Al hydrotalcite composite material is 1.2:0.5:2; the crystallinity of β crystal of the above PPRCT is 80%, wherein the anionic surfactant is sodium silicate, the antioxidant is antioxidant 1076, the Mg-Al hydrotalcite is nanoscale, and is pre-calcined at 400-500°C.

[0043] The above chlorine-resistant polyolefin pipe can be prepared by the following processing method:

[0044] Preparation of modified Mg-Al hydrotalcite composite material: the nanoscale Mg-Al hydrotalcite obtained in Example 1 is pre-calcined in a muffle furnace at 400-500°C for 4h, and is ready for use;

[0045] According to the proportion of the amount of each component in the above chlorine-resistant polyolefin material, the antioxidant 1076 is dissolved in 0.1 mol / L sodium hydroxide aqueous solution, then the long-chain anionic surfactant sodium silicate is added, and the mixture is uniformly mixed to form an anionic aqueous solution, the pH value of the system is adjusted to 9-11, then the above pre-calcined nanoscale Mg-Al hydrotalcite is added, and stirred at room temperature for 34h, then filtered, washed with purified water, and the obtained solid wet product is dried to constant weight under vacuum at 60°C to obtain the modified Mg-Al hydrotalcite composite material intercalated with surfactant and antioxidant.

[0046] Inner layer material of chlorine-resistant polyolefin pipe: 0.1% by mass of the modified Mg-Al hydrotalcite composite material and 99.9% by mass of PPRCT raw material are added to a granulator and uniformly mixed under high-speed (1200r / min) stirring, and extrusion granulation is carried out at a temperature of 190-210°C, and after drying, the inner layer material of chlorine-resistant polyolefin pipe is obtained.

[0047] Processing of polyolefin pipe: the above inner layer material and outer layer material are added to a molding machine to form a double-layer composite pipe by co-extrusion, i.e. the outer layer material of the pipe is PPR, the inner layer material of the pipe is the above obtained inner layer material of chlorine-resistant polyolefin pipe, the co-extrusion molding temperature is controlled between 190-210°C, and the thickness of the inner layer is controlled between 0.6-1mm, and the corresponding composite pipe semi-finished product is obtained.

[0048] Annealing crystallization: the obtained composite pipe semi-finished pipe material is placed into an oven (the temperature difference of the equipment is not more than 5°C) with uniform temperature and controllable rise and fall, the temperature is uniformly raised to 102°C within 30 min, and is controlled to be treated at the temperature for 40 min, then the temperature is uniformly raised to 115°C within 10 min, and is controlled to be treated at the temperature for 40 min, after the end, it is removed from the oven, and is naturally cooled to room temperature, to obtain the annealing treated chlorine-resistant polyolefin pipe, and the test shows that the crystallinity of the β crystal of the inner layer PPRCT is 80%.

[0049] Example 3

[0050] The chlorine-resistant polyolefin pipe includes an outer layer and an inner layer, the pipe outer layer and the pipe inner layer are formed by co-extrusion through a forming device, the inner layer is made of chlorine-resistant polyolefin material, and more importantly, the chlorine-resistant polyolefin material includes the following components in mass percentage:

[0051] PPRCT: 98%; modified magnesium-aluminum hydrotalcite composite material: 2%, the modified magnesium-aluminum hydrotalcite composite material is obtained by anion surfactant and antioxidant composite intercalation magnesium-aluminum hydrotalcite, the mass ratio of magnesium-aluminum hydrotalcite: anion surfactant: antioxidant in the modified magnesium-aluminum hydrotalcite composite material is 1.5:0.4:2; the crystallinity of the β crystal of the PPRCT is 70%, the anion surfactant is sodium naphthenate, the antioxidant is antioxidant 1076, the magnesium-aluminum hydrotalcite is nanoscale, and is pre-treated by calcination at 400-500°C.

[0052] The chlorine-resistant polyolefin pipe can be made by the following processing method:

[0053] Preparation of the modified magnesium-aluminum hydrotalcite composite material: the nanoscale magnesium-aluminum hydrotalcite obtained in Example 1 is pre-calcined in a muffle furnace at 400-500°C for 4 h, and is ready for use;

[0054] According to the amount proportion of each component in the chlorine-resistant polyolefin material, the antioxidant 1076 is dissolved in 0.1 mol / L sodium hydroxide aqueous solution, then the long-chain anion surfactant sodium naphthenate is added, the mixture is uniformly mixed to form an anion aqueous solution, the pH value of the system is adjusted to 9-11, then the nanoscale magnesium-aluminum hydrotalcite pre-calcined above is added, and is stirred at room temperature for 35 h, then is filtered, washed with purified water, and the obtained solid wet product is dried to constant weight under vacuum at 60°C, to obtain the modified magnesium-aluminum hydrotalcite composite material after the surfactant and antioxidant composite intercalation.

[0055] The inner layer material of the chlorine-resistant polyolefin pipe: the modified magnesium-aluminum hydrotalcite composite material with a mass percentage of 2% and the PPRCT raw material with a mass percentage of 98% are added into a granulator and uniformly mixed under high-speed (1000 r / min) stirring, and extrusion granulation is carried out at a temperature of 190-210 ℃, and the chlorine-resistant polyolefin pipe inner layer material is obtained after drying.

[0056] The processing of the polyolefin pipe: the above-mentioned inner layer material and outer layer material are added into a molding machine to form a double-layer composite pipe by co-extrusion, i.e., the outer layer material of the pipe is PERT, the inner layer material of the pipe is the chlorine-resistant polyolefin pipe inner layer material obtained above, the molding temperature of co-extrusion is controlled to be between 190-210 ℃, the thickness of the inner layer is controlled to be 0.6-1 mm, and the corresponding composite pipe semi-finished product is obtained.

[0057] Annealing and crystallization: the obtained pipe semi-finished product is placed into an oven with uniform temperature and controllable temperature rise and fall (the equipment temperature difference is not more than 5 ℃), the temperature is uniformly raised to 101 ℃ within 30 min, and isothermal treatment is carried out at this temperature for 30 min, then the temperature is uniformly raised to 112 ℃ within 10 min, and isothermal treatment is carried out at this temperature for 30 min, after the end, the oven is removed, and natural cooling to room temperature is carried out, and the chlorine-resistant polyolefin pipe after annealing treatment is obtained, and the crystallinity of the β crystal of the inner layer PPRCT is 70% after testing.

[0058] Randomly select the pipes obtained in the above-mentioned examples 1-3 to carry out corresponding performance tests, and the specific test methods and results are as follows:

[0059] Chlorine water immersion experiment: 5 mg / l chlorine water solution is configured, and 5 cm±0.5 cm pipe segments are immersed in the chlorine water solution under the conditions of constant temperature of 60 ℃ and pH value of 7±0.1.

[0060] Oxidation induction time (OTI) detection: the inner layer of the chlorine-resistant polyolefin pipe is scraped off from the pipe segments before immersion and after immersion for 2000 h, and detection is carried out according to the standard GB / T19466.6-2009.

[0061] Comparative test group:

[0062] 1. No modified hydrotalcite is added, and the PPRCT inner layer is not annealed;

[0063] 2. No modified hydrotalcite is added, and the PPRCT inner layer is annealed (the crystallinity is about 73%);

[0064] 3. The inner layer of the chlorine-resistant polyolefin pipe in example 1 is used (0.4% modified magnesium-aluminum hydrotalcite is added, and the PPRCT inner layer after annealing treatment (the crystallinity is 75%);

[0065] The OTI comparison results show that:

[0066] 1. Without adding modified hydrotalcite and unannealed PPRCT inner layer: time is reduced from 46.9 min to 28.2 min.

[0067] 2. Without adding modified hydrotalcite and annealed PPRCT inner layer (crystallinity of about 73%): time is reduced from 47.2 min to 35.8 min,

[0068] 3. Adding 0.4% modified hydrotalcite and annealed PPRCT inner layer (crystallinity of 75%): time is reduced from 56.3 min to 48.6 min.

[0069] From the above results, it can be seen that by adding modified magnesium-aluminum hydrotalcite composite material and annealing treatment, the overall chlorine resistance can be effectively improved.

[0070] And the corresponding chlorine-resistant polyolefin pipe in Example 2 is tested for performance, and the results show that excellent chlorine resistance can be achieved, and the time change before and after soaking is reduced from 56.5 min to 50.4 min through the above oxidation induction time (OTI) detection.

[0071] And the corresponding chlorine-resistant polyolefin pipe in Example 3 is tested for performance, and the results show that excellent chlorine resistance can be achieved, and the time change before and after soaking is reduced from 56.1 min to 44.2 min through the above oxidation induction time (OTI) detection.

[0072] The specific embodiments described in the present application are only illustrative of the spirit of the present application. Those skilled in the art to which the present application belongs can make various modifications or supplements to the described specific embodiments or replace them with similar ways, but will not deviate from the spirit of the present application or exceed the scope defined by the appended claims.

[0073] Although the present application has been described in detail and some specific embodiments have been cited, it is obvious to those skilled in the art that various changes or modifications can be made without departing from the spirit and scope of the present application.

Claims

1. A chlorine resistant polyolefin pipe, said pipe comprising an outer layer and an inner layer, said inner layer being made of a chlorine resistant polyolefin material, characterized in that, The chlorine-resistant polyolefin material comprises the following mass percentage of ingredients: PPRCT: 98%~99.9%; modified magnesium-aluminum hydrotalcite composite material: 0.1%~2.0%, the modified magnesium-aluminum hydrotalcite composite material is formed by anion surfactant and antioxidant intercalated magnesium-aluminum hydrotalcite, the mass ratio of magnesium-aluminum hydrotalcite: anion surfactant: antioxidant in the modified magnesium-aluminum hydrotalcite composite material is 1.0~1.5: 0.25~0.5: 2; the crystallinity of β crystal in the PPRCT is 60%~80%; the crystal grain size of the PPRCT is controlled in 0.9μm~10μm.

2. The chlorine resistant polyolefin pipe according to claim 1, wherein, The antioxidant is selected from one or both of antioxidant 1010 and antioxidant 1076.

3. The chlorine-resistant polyolefin pipe according to claim 1, wherein The anion surfactant is selected from one or several of sodium naphthenate, sodium dodecyl benzene sulfonate, sodium hexadecanoate and sodium silicate.

4. The chlorine-resistant polyolefin pipe according to claim 1, wherein The magnesium-aluminum hydrotalcite is previously calcined at a temperature of 400℃~500℃.

5. The chlorine-resistant polyolefin pipe according to claim 1 or 2 or 3 or 4, wherein, The outer layer is mainly processed from PPR, PE or PERT material.

6. A process for the processing of a chlorine resistant polyolefin pipe, said pipe being coextrusion processed from an inner layer material and an outer layer material, characterized in that, The method further comprises the following steps: A. mixing the antioxidant and the anion surfactant in an alkaline aqueous solution, and controlling the pH value of the system to 9~11 to form an anion surfactant solution; then adding magnesium-aluminum hydrotalcite for mixing to obtain modified magnesium-aluminum hydrotalcite composite material after intercalation and compounding of the anion surfactant and the antioxidant, the mass ratio of magnesium-aluminum hydrotalcite: anion surfactant: antioxidant is 1.0~1.5: 0.25~0.5: 2; B. mixing the obtained modified magnesium-aluminum hydrotalcite composite material with PPRCT, and controlling the temperature at 190℃~210℃ to perform extrusion granulation to obtain the inner layer material, the mass ratio of PPRCT to modified magnesium-aluminum hydrotalcite composite material is 98~99.9: 0.1~2.0; C. co-extruding the inner layer material and the outer layer material in a pipe forming device to obtain a corresponding composite pipe semi-finished product; D. annealing the composite pipe semi-finished product at a temperature of 100℃~110℃, and after the annealing is completed, cooling to obtain a corresponding chlorine-resistant polyolefin pipe; the crystallinity of β crystal in the component PPRCT of the chlorine-resistant polyolefin pipe is 60%~80%; the crystal grain size of the PPRCT is controlled in 0.9μm~10μm.

7. The process for processing the chlorine-resistant polyolefin pipe according to claim 6, characterized by, The magnesium-aluminum hydrotalcite in step A is obtained by the following method: A soluble aluminum salt and a soluble magnesium salt are dissolved in water, so that the molar ratio of Al 3+ to (Al 3+ + Mg 2+ ) in the solution is 1:4 to 1:2, urea is added, the molar ratio of urea to (Al 3+ + Mg 2+ ) is 3:1 to 4:1, and the reaction is carried out under the condition that the temperature is controlled at 100°C to 120°C. After the reaction is completed, filtration, washing, and drying are carried out to obtain nanoscale magnesium-aluminum hydrotalcite.

8. The process for processing the chlorine-resistant polyolefin pipe according to claim 6, characterized by, The magnesium-aluminum hydrotalcite is previously calcined at a temperature of 400℃~500℃ for 2h~4h.

9. The process for processing the chlorine-resistant polyolefin pipe according to claim 6 or 7 or 8, characterized by, The annealing in step D is specifically: placing the composite pipe semi-finished product in a temperature of 100℃~102℃ for heat preservation for 20min~40min; then increasing the temperature to 110℃~115℃ for heat preservation for 30min~60min, after the annealing is completed, naturally cooling to room temperature to complete the annealing.