A flame-retardant PVC power pipe and its production process

Abstract

The present invention relates to a flame-retardant PVC power pipe and its production process, belonging to the technical field of polymer materials. The flame-retardant PVC power pipe comprises, by weight: 20-40 parts of polyvinyl chloride resin, 6-10 parts of a modified flame retardant, 6-10 parts of an anti-aging modifier, 3-7 parts of a lubricant, 3-5 parts of a heat stabilizer, and 2-8 parts of a plasticizer; in the modified flame retardant, cyclohexanehexol phosphate dehydrates upon heating to form phosphoric acid, forming a barrier layer to inhibit the release of combustibles, and the intermediate inhibits the decomposition and combustion of PVC at high temperatures, generating ammonia gas upon heating to dilute combustible gases, and synergistically flame-retards with the phosphorus-oxygen double bond; in the anti-aging modifier, 2,4-dihydroxybenzophenone undergoes thermal vibration and releases energy upon ultraviolet irradiation, and the maleimide group increases the glass transition temperature and melting point, reducing aging caused by high-temperature thermal aging; the flame-retardant PVC power pipe prepared by the present invention not only has excellent flame-retardant effects, but also has good anti-aging performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a flame-retardant PVC power pipe and its production process. Background Art

[0002] With the rapid progress of science and technology and the booming development of industry, polyvinyl chloride (PVC) pipes have good compressive and tensile strengths, and show increasingly wide application potential in pressure-bearing sanitary pipes and fittings in urban construction, building water supply and drainage pipes and fittings, porous sleeves for electricity, high-voltage cable pipes, natural gas pipes, etc.

[0003] However, under high-temperature environments, PVC power pipes may experience softening phenomena, and continuous temperature fluctuations will accelerate the aging process of the pipes. At the same time, during the laying construction process, traditional PVC power pipes will be strongly irradiated by ultraviolet rays under sunlight, resulting in the destruction of the molecular structure and further aging of the material. Therefore, anti-aging performance has also become an essential characteristic of PVC power pipes; in addition, when PVC power pipes burn, although they have a certain flame-retardant effect, with the improvement of actual application requirements, their own flame retardancy can no longer meet the needs. Therefore, researching and developing PVC power pipes with excellent anti-aging and flame-retardant properties has important practical significance and application value. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a flame-retardant PVC power pipe and its production process.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] A flame-retardant PVC power pipe, comprising the following raw materials in parts by weight: 20-40 parts of polyvinyl chloride resin, 6-10 parts of modified flame retardant, 6-10 parts of anti-aging modifier, 3-7 parts of lubricant, 3-5 parts of heat stabilizer, and 2-8 parts of plasticizer;

[0007] The heat stabilizer is zinc stearate;

[0008] The lubricant is butyl stearate;

[0009] The plasticizer is dioctyl phthalate.

[0010] The modified flame retardant is prepared by the following method:

[0011] Step A1: Mix melamine, formaldehyde and deionized water evenly, adjust the pH to 8-9, mechanically stir at 80°C for 40 min, then cool to room temperature, filter, and dry at 80°C to obtain an intermediate;

[0012] Further, the dosage ratio of melamine, formaldehyde, and deionized water is 1.2 - 1.4 g : 1.8 - 2.1 g : 10 - 20 mL;

[0013] First, react the amino group of melamine with formaldehyde to form an intermediate;

[0014] Step A2: Mix and stir the intermediate and cyclohexanehexol phosphate, heat to 60 °C, then add 4-dimethylaminopyridine and stir. Keep the temperature at 60 °C for 3 h, cool to room temperature, and obtain a pre-product;

[0015] Further, the dosage ratio of the intermediate, cyclohexanehexol phosphate, and 4-dimethylaminopyridine is 1.5 - 2.0 g : 1.3 - 1.8 g : 20 - 45 mL;

[0016] Secondly, react the hydroxyl group of the intermediate with the hydroxyl group of cyclohexanehexol phosphate to form a pre-product;

[0017] Step A3: Mix the pre-product, 6-chloro-1-hexene, and methanol, stir for 20 min, heat to 80 °C and react for 1 h. After the temperature drops to room temperature, add 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and N,N-dimethylformamide and mix. Stir at 150 °C for 9 h, filter at room temperature, wash, and dry in vacuum at 60 °C for 24 h to obtain a modified flame retardant;

[0018] Further, the dosage ratio of the pre-product, 6-chloro-1-hexene, methanol, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and N,N-dimethylformamide is 1 - 2 mol : 2 - 4 mol : 5 - 10 mL : 2 - 4 mol : 180 - 200 mL;

[0019] Finally, react the chlorine atom of 6-chloro-1-hexene with the hydroxyl group of the pre-product, and react the carbon-carbon double bond of 6-chloro-1-hexene with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to form a modified flame retardant.

[0020] The anti-aging modifier is prepared by the following method:

[0021] Step B1: Mix maleic anhydride, toluene, and 3-chloroaniline, stir and react for 30 min, then add tetrahydrofuran. Continuously stir in an ice-water bath for 5 min, then add triethylamine and mix. React for 10 min, wash, dry, filter, and rotary evaporate to obtain a compound;

[0022] Further, the dosage ratio of maleic anhydride, toluene, 3-chloroaniline, tetrahydrofuran, and triethylamine is 4.81 - 5.75 g : 40 - 50 mL : 6.2 - 6.4 g : 10 mL : 3.12 - 4.58 g;

[0023] First, react maleic anhydride with the amino group of 3-chloroaniline to form a compound;

[0024] Step B2: Mix 2,4-dihydroxybenzophenone, triethylamine, and tetrahydrofuran evenly, then dropwise add the compound under an ice bath. The dropping time is 1 - 2 h, and react for 5 h under the ice bath. After the reaction, precipitate in ice water, wash, and dry under vacuum to obtain the anti-aging modifier;

[0025] Furthermore, the dosage ratio of 2,4-dihydroxybenzophenone, triethylamine, tetrahydrofuran, and the compound is 2.14 - 5.35 g : 1.7 - 3.5 mL : 20 - 30 mL : 0.01 - 0.05 mol;

[0026] Then, react the hydroxyl group of 2,4-dihydroxybenzophenone with the chlorine atom of the compound to form the anti-aging modifier.

[0027] A production process of a flame-retardant PVC power pipe specifically includes the following steps:

[0028] Step S1: Mix polyvinyl chloride resin, modified flame retardant, anti-aging modifier, and heat stabilizer, and stir for 2 - 2.5 h at a temperature of 175 - 180 °C and a rotation speed of 200 r / min to obtain a mixture;

[0029] Step S2: Add a lubricant and a plasticizer to the mixture, and stir for 3 - 4 h at a temperature of 180 - 190 °C and a rotation speed of 500 r / min to obtain a pre-material;

[0030] Step S3: Add the pre-material to a conical twin-screw extruder, and extrude, shape, and cut at a rotation speed of 30 r / min to obtain the flame-retardant PVC power pipe.

[0031] The beneficial effects of the present invention:

[0032] The flame-retardant PVC power pipe of the present invention uses polyvinyl chloride resin as the matrix, and adds a modified flame retardant and an anti-aging modifier, endowing the material with excellent anti-aging performance and flame retardancy, and effectively extending the service life of the material.

[0033] The cyclohexanehexol phosphate in the modified flame retardant prepared by the present invention, as a biomass renewable resource with a wide range of sources and environmental friendliness, dehydrates into phosphoric acid when heated, promotes surface carbonization to form a barrier layer, effectively isolates air and heat, inhibits the release of combustible volatiles, and achieves the flame retardant effect; the intermediate has high thermal stability and can maintain structural integrity at high temperatures, thus effectively inhibiting the decomposition and combustion of PVC at high temperatures. At the same time, the intermediate will decompose to produce ammonia gas when heated, diluting combustible gases and preventing the further spread of the flame; in addition, the phosphorus-nitrogen flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, as a phosphaphenanthrene compound with high thermal stability, promotes the formation of a dense and continuous carbon layer during combustion, effectively isolates oxygen, blocks the exchange of heat and combustible gases, inhibits combustion, and also synergistically retards the flame with the phosphorus-oxygen double bond, extending its service life; in addition, the composite flame retardant prepared by the present invention is halogen-free, helps to reduce environmental pollution and damage to the ecosystem, is harmless to human health, and realizes sustainable development.

[0034] In the anti-aging modifier prepared by the present invention, a chelate ring can be formed between the hydroxyl hydrogen and the carbonyl oxygen in 2,4-dihydroxybenzophenone through hydrogen bonding. When irradiated by ultraviolet light, the molecules undergo thermal vibration, and the electrons in the molecules will be excited and jump to higher energy levels, and then release energy in the form of emitting weak long waves, thus avoiding the harm of high-energy ultraviolet light. At the same time, the molecular structure of 2,4-dihydroxybenzophenone contains a benzene ring and a methoxy group, which can effectively absorb ultraviolet light; in addition, the maleimide group enhances the intermolecular force, increases the glass transition temperature and melting point of the material, increases the rigidity and heat resistance of the molecular chain, and reduces the aging of the material caused by high-temperature thermal aging; in addition, this anti-aging modifier has high compatibility with polyvinyl chloride, solving the problems of migration, incompatibility and volatilization of traditional anti-aging modifiers. Specific embodiments

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Example 1: A production process of a flame-retardant PVC power pipe specifically includes the following steps:

[0037] Step S1: Weigh the raw materials by weight parts, 20 parts of polyvinyl chloride resin, 6 parts of modified flame retardant (prepared by this embodiment), 6 parts of anti-aging modifier (prepared by this embodiment), 3 parts of lubricant, 3 parts of heat stabilizer, and 2 parts of plasticizer; Mix the polyvinyl chloride resin, modified flame retardant, anti-aging modifier and zinc stearate, and stir for 2 h at a temperature of 175 °C and a rotation speed of 200 r / min to obtain a mixture;

[0038] Step S2: Add butyl stearate and dioctyl phthalate to the mixture, and stir for 3 h at a temperature of 180 °C and a rotation speed of 500 r / min to obtain a pre-material;

[0039] Step S3: Add the pre-material to a conical twin-screw extruder, and carry out extrusion, shaping and cutting at a rotation speed of 30 r / min to obtain a flame-retardant PVC power pipe;

[0040] The modified flame retardant is prepared by the following method:

[0041] Step A1: Mix 1.2 g of melamine, 1.8 g of formaldehyde and 10 mL of deionized water evenly, adjust the pH to 8, mechanically stir at 80 °C for 40 min, then cool to room temperature, filter, and dry at 80 °C to obtain an intermediate;

[0042] Step A2: Mix 1.5 g of the intermediate and 1.3 g of cyclohexanehexol phosphate and stir, heat up to 60 °C, then add 20 mL of 4-dimethylaminopyridine and stir, keep the temperature at 60 °C for 3 h, and cool to room temperature to obtain a pre-product;

[0043] Step A3: Mix 1 mol of the pre-product, 2 mol of 6-chloro-1-hexene and 5 mL of methanol, stir for 20 min, heat up to 80 °C and react for 1 h. After the temperature drops to room temperature, add 2 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 180 mL of N,N-dimethylformamide and mix, stir at 150 °C for 9 h, filter at room temperature, wash, and vacuum dry at 60 °C for 24 h to obtain the modified flame retardant;

[0044] The anti-aging modifier is prepared by the following method:

[0045] Step B1: Mix 4.81 g of maleic anhydride, 40 mL of toluene and 6.2 g of 3-chloroaniline, stir and react for 30 min, then add 10 mL of tetrahydrofuran, continuously stir in an ice-water bath for 5 min, then add 3.12 g of triethylamine and react for 10 min, wash, dry, filter and rotary evaporate to obtain a compound;

[0046] Step B2: Mix 2.14 g of 2,4-dihydroxybenzophenone, 1.7 mL of triethylamine and 20 mL of tetrahydrofuran evenly, then dropwise add 0.01 mol of the compound under an ice bath. The dropping time is 1 h, and react for 5 h under the ice bath. After the reaction, precipitate in ice water, wash, and dry under vacuum to obtain the anti-aging modifier.

[0047] Example 2: A production process of a flame-retardant PVC power pipe specifically includes the following steps:

[0048] Step S1: Weigh the raw materials by weight parts: 30 parts of polyvinyl chloride resin, 8 parts of modified flame retardant (prepared by this example), 8 parts of anti-aging modifier (prepared by this example), 5 parts of lubricant, 4 parts of heat stabilizer, and 5 parts of plasticizer; Mix the polyvinyl chloride resin, modified flame retardant, anti-aging modifier and zinc stearate, and stir for 2.2 h at a temperature of 177 °C and a rotation speed of 200 r / min to obtain a mixture;

[0049] Step S2: Add butyl stearate and dioctyl phthalate to the mixture, and stir for 3.5 h at a temperature of 185 °C and a rotation speed of 500 r / min to obtain a pre-material;

[0050] Step S3: Add the pre-material to a conical twin-screw extruder, and extrude, shape, and cut at a rotation speed of 30 r / min to obtain a flame-retardant PVC power pipe;

[0051] The modified flame retardant is prepared by the following method:

[0052] Step A1: Mix 1.3 g of melamine, 1.95 g of formaldehyde and 15 mL of deionized water evenly, adjust the pH to 8.5, mechanically stir at 80 °C for 40 min, then cool to room temperature, filter, and dry at 80 °C to obtain an intermediate;

[0053] Step A2: Mix 1.75 g of the intermediate and 1.55 g of cyclohexanehexol phosphate and stir, heat up to 60 °C, then add 32.5 mL of 4-dimethylaminopyridine and stir, keep the temperature at 60 °C for 3 h, and cool to room temperature to obtain a pre-product;

[0054] Step A3: Mix 1.5 mol of the pre-product, 3 mol of 6-chloro-1-hexene and 7.5 mL of methanol, stir for 20 min, heat up to 80 °C and react for 1 h. When the temperature drops to room temperature, add 3 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 190 mL of N,N-dimethylformamide and mix, stir at 150 °C for 9 h, filter at room temperature, wash, and dry under vacuum at 60 °C for 24 h to obtain the modified flame retardant;

[0055] The anti-aging modifier is prepared by the following method:

[0056] Step B1: Mix 5.28 g of maleic anhydride, 45 mL of toluene and 6.3 g of 3-chloroaniline, stir and react for 30 min, then add 10 mL of tetrahydrofuran. After continuously stirring for 5 min in an ice-water bath, add 3.85 g of triethylamine and react for 10 min. Wash, dry, filter and rotary evaporate to obtain the compound.

[0057] Step B2: Mix 3.745 g of 2,4-dihydroxybenzophenone, 2.6 mL of triethylamine and 25 mL of tetrahydrofuran evenly, then dropwise add 0.03 mol of the compound under an ice bath, with the dropping time being 1.5 h. React under the ice bath for 5 h. After the reaction ends, precipitate in ice water, wash and vacuum dry to obtain the anti-aging modifier.

[0058] Example 3: A production process of a flame-retardant PVC power pipe, which specifically includes the following steps:

[0059] Step S1: Weigh the raw materials by weight parts, 40 parts of polyvinyl chloride resin, 10 parts of modified flame retardant (prepared in this example), 10 parts of anti-aging modifier (prepared in this example), 7 parts of lubricant, 5 parts of heat stabilizer, 8 parts of plasticizer; Mix the polyvinyl chloride resin, modified flame retardant, anti-aging modifier and zinc stearate, and carry out stirring for 2.5 h under the conditions of a temperature of 180 °C and a rotation speed of 200 r / min to obtain a mixture.

[0060] Step S2: Add butyl stearate and dioctyl phthalate to the mixture, and carry out stirring for 4 h under the conditions of a temperature of 190 °C and a rotation speed of 500 r / min to obtain a pre-material.

[0061] Step S3: Add the pre-material to a conical twin-screw extruder, and carry out extrusion, shaping and cutting at a rotation speed of 30 r / min to obtain the flame-retardant PVC power pipe.

[0062] The modified flame retardant is prepared by the following method:

[0063] Step A1: Mix 1.4 g of melamine, 2.1 g of formaldehyde and 20 mL of deionized water evenly, adjust the pH to 9, mechanically stir at 80 °C for 40 min, then cool to room temperature, filter and dry at 80 °C to obtain an intermediate.

[0064] Step A2: Mix 2.0 g of the intermediate and 1.8 g of cyclohexanehexol phosphate and stir, heat up to 60 °C, then add 45 mL of 4-dimethylaminopyridine and stir, keep the temperature at 60 °C for 3 h of reaction, and cool to room temperature to obtain a pre-product.

[0065] Step A3: Mix 2 mol of the pre-product, 4 mol of 6-chloro-1-hexene, and 10 mL of methanol, stir for 20 min, heat up to 80 °C and react for 1 h. After the temperature drops to room temperature, add 4 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 200 mL of N,N-dimethylformamide and mix. Stir at 150 °C for 9 h, filter at room temperature, wash, and dry in vacuum at 60 °C for 24 h to obtain the modified flame retardant;

[0066] The anti-aging modifier is prepared by the following method:

[0067] Step B1: Mix 5.75 g of maleic anhydride, 50 mL of toluene, and 6.4 g of 3-chloroaniline, stir and react for 30 min, then add 10 mL of tetrahydrofuran. Continuously stir in an ice-water bath for 5 min, then add 4.58 g of triethylamine and mix. React for 10 min, wash, dry, filter, and rotary evaporate to obtain the compound;

[0068] Step B2: Mix 5.35 g of 2,4-dihydroxybenzophenone, 3.5 mL of triethylamine, and 30 mL of tetrahydrofuran evenly, then dropwise add 0.05 mol of the compound under an ice bath. The dropping time is 2 h, and react under the ice bath for 5 h. After the reaction is completed, precipitate in ice water, wash, and dry in vacuum to obtain the anti-aging modifier.

[0069] Comparative Example 1

[0070] This comparative example is a flame-retardant PVC power pipe. The difference from Example 3 is that an equal amount of magnesium hydroxide is used to replace the modified flame retardant prepared in Example 3, and the rest are the same.

[0071] Comparative Example 2

[0072] This comparative example is a flame-retardant PVC power pipe. The difference from Example 3 is that an equal amount of 4,4'-thiobis(6-tert-butyl-3-methylphenol) is used to replace the anti-aging modifier prepared in Example 3, and the rest are the same.

[0073] Performance test: Cut the flame-retardant PVC power pipes prepared in Examples 1-3 and Comparative Examples 1-2 into standard test sizes, and test the vertical burning performance using the plastic combustion performance test method of GB / T2048-1996; Use a UVC-LED disinfection lamp (30 W, 254 nm wavelength) to irradiate at a vertical distance of 10 cm for 40 hours, and detect the color difference before and after UVC-LED irradiation according to the CIE1976L*a*b* standard; Put the samples into a UV aging box, with conditions of 60 °C, 0.86 w / cm2, and ultraviolet light irradiation for 1000 h, and test the change difference of the yellow index. The larger the difference, the worse the anti-aging performance; The test results are shown in Table 1 below:

[0074] Table 1

[0075]

[0076] As can be seen from the data tested in Table 1, the flame-retardant PVC power pipes prepared in Example 1 have excellent flame-retardant properties. It can also be seen from the above table that the flame-retardant PVC power pipes prepared by the present invention have good ultraviolet resistance and aging resistance.

[0077] The above content is only an example and illustration of the concept of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the specific embodiments described or use similar methods for substitution. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims of the present invention, they should fall within the protection scope of the present invention.

Claims

1. A production process of a flame-retardant PVC power pipe, characterized in that, It includes the following steps: Step S1: Weigh the raw materials by weight parts, including 20 - 40 parts of polyvinyl chloride resin, 6 - 10 parts of modified flame retardant, 6 - 10 parts of anti - aging modifier, 3 - 7 parts of lubricant, 3 - 5 parts of heat stabilizer, and 2 - 8 parts of plasticizer; Mix the polyvinyl chloride resin, modified flame retardant, anti - aging modifier, and heat stabilizer, and under the conditions of a temperature of 175 - 180°C and a rotation speed of 200 r / min, stir for 2 - 2.5 h to obtain a mixture. Step S2: Add the lubricant and plasticizer to the mixture, and under the conditions of a temperature of 180 - 190°C and a rotation speed of 500 r / min, stir for 3 - 4 h to obtain a pre - material. Step S3: Add the pre - material to a conical twin - screw extruder, and under a rotation speed of 30 r / min, perform extrusion, shaping, and cutting to obtain a flame - retardant PVC power pipe. The modified flame retardant is prepared by the following method: Step A1: Mix melamine, formaldehyde, and deionized water evenly, adjust the pH to 8 - 9, mechanically stir at 80°C for 40 min, then cool to room temperature, filter, and dry at 80°C to obtain an intermediate. Step A2: Mix the intermediate and cyclohexanehexol phosphate and stir, heat up to 60°C, then add 4 - dimethylaminopyridine and stir, keep the temperature at 60°C for 3 h of reaction, and cool to room temperature to obtain a pre - product. Step A3: Mix the pre - product, 6 - chloro - 1 - hexene, and methanol, stir for 20 min, heat up to 80°C and react for 1 h. After the temperature drops to room temperature, add a mixture of 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide and N,N - dimethylformamide, stir at 150°C for 9 h, filter at room temperature, wash, and vacuum - dry at 60°C for 24 h to obtain the modified flame retardant. The anti - aging modifier is prepared by the following method: Step B1: Mix maleic anhydride, toluene, and 3 - chloroaniline, stir and react for 30 min, then add tetrahydrofuran, continuously stir in an ice - water bath for 5 min, then add triethylamine and mix, react for 10 min, wash, dry, filter, and rotary evaporate to obtain a compound. Step B2: Mix 2,4 - dihydroxybenzophenone, triethylamine, and tetrahydrofuran evenly, then drop - add the compound under an ice bath, the dropping time is 1 - 2 h, react under the ice bath for 5 h, after the reaction ends, precipitate in ice water, wash, and vacuum - dry to obtain the anti - aging modifier.

2. The production process of a flame-retardant PVC power pipe according to claim 1, characterized in that, In step A1, the dosage ratio of melamine, formaldehyde, and deionized water is 1.2 - 1.4 g: 1.8 - 2.1 g: 10 - 20 mL.

3. The production process of a flame-retardant PVC power pipe according to claim 1, characterized in that, In step A2, the dosage ratio of the intermediate, cyclohexanehexol phosphate, and 4 - dimethylaminopyridine is 1.5 - 2.0 g: 1.3 - 1.8 g: 20 - 45 mL.

4. The production process of a flame-retardant PVC power pipe according to claim 1, characterized in that, In step A3, the dosage ratio of the pre - product, 6 - chloro - 1 - hexene, methanol, 9,10 - dihydro - 9 - oxa - 10 - phosphaphenanthrene - 10 - oxide, and N,N - dimethylformamide is 1 - 2 mol: 2 - 4 mol: 5 - 10 mL: 2 - 4 mol: 180 - 200 mL.

5. The production process of a flame-retardant PVC power pipe according to claim 1, characterized in that, In step B1, the dosage ratio of maleic anhydride, toluene, 3-chloroaniline, tetrahydrofuran, and triethylamine is 4.81 - 5.75 g : 40 - 50 mL : 6.2 - 6.4 g : 10 mL : 3.12 - 4.58 g.

6. The production process of a flame-retardant PVC power pipe according to claim 1, characterized in that, In step B2, the dosage ratio of 2,4-dihydroxybenzophenone, triethylamine, tetrahydrofuran, and the compound is 2.14 - 5.35 g : 1.7 - 3.5 mL : 20 - 30 mL : 0.01 - 0.05 mol.

7. The production process of a flame-retardant PVC power pipe according to claim 1, characterized in that, The heat stabilizer is zinc stearate, the lubricant is butyl stearate, and the plasticizer is dioctyl phthalate.

8. A flame-retardant PVC power pipe, characterized in that, Prepared according to the production process described in any one of claims 1 - 7.

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