Flame-retardant and pressure-resistant PVC (polyvinyl chloride) electric pipe and preparation method thereof

Abstract

The invention discloses a flame-retardant and compression-resistant PVC (polyvinyl chloride) electric tube and a preparation method thereof, and the flame-retardant and compression-resistant PVC electric tube is prepared from the following raw materials in parts by weight: 50-60 parts of compression-resistant polyvinyl chloride, 20-30 parts of acrylonitrile-butadiene-styrene terpolymer and 20-30 parts of mixed raw materials, the mixed raw materials comprise the following components in parts by weight: 10-15 parts of a phosphazene composite flame retardant, 3-5 parts of an epoxidized soybean oil plasticizer, 5-8 parts of a calcium-zinc stabilizer, 0.1-0.5 part of lubricant paraffin and 1-5 parts of glass fibers; the phosphazene composite flame retardant has the advantages of being high in flame retardant efficiency, green and flame-retardant, polyvinyl chloride is modified with hexa (3-glycidyl ether phenoxy) tripolyphosphazene, and the compression resistance of the pipe is improved by means of the multi-benzene-ring structure of organophosphorus resin.

Description

Technical Field

[0001] The invention relates to the technical field of PVC pipes, and in particular to a flame-retardant and pressure-resistant PVC electric power pipe and a preparation method thereof. Background Art

[0002] The electric power industry is the most important basic energy industry in the development of the national economy. In the past, optical cables were mostly transmitted overhead. With the increasing requirements for cable reliability and safety, more and more optical cables are transmitted underground. There are many types of plastic cable conduits on the market. Polyvinyl chloride has good electrical properties and corrosion resistance, and is widely used in the manufacture of low-voltage cable materials.

[0003] However, as a flammable and combustible polymer material, polyvinyl chloride will release a large amount of smoke when it is thermally cracked or burned, becoming the main source and fuse of fire. When preparing polyvinyl chloride pipes, in order to improve the flexibility, transparency and processing performance of polyvinyl chloride, an appropriate amount of plasticizer will be added. The addition of plasticizers will further improve the smoke suppression of polyvinyl chloride pipes. Therefore, how to improve the flame retardancy of polyvinyl chloride and ensure the safety of power transmission is a technical problem that needs to be solved urgently. In addition, power pipes need to withstand pressure during construction and need to have a high compressive resistance.

[0004] Patent application CN103923421A discloses a CPVC for high-vicat power cable sheath and a preparation method thereof, including CPVC resin, PVC resin, filler, pigment and related additives. The above-mentioned CPVC power pipe has the advantages of high mechanical strength and good flame retardancy. However, the chlorine content of the above-mentioned CPVC resin is extremely high, and it is easy to release a large amount of toxic smoke when burned, and it is not an environmentally friendly resin.

[0005] Patent application CN116239842A discloses a pressure-resistant pipe and a preparation method thereof, including a pressure-resistant layer, wherein the pressure-resistant layer includes PPR, POE, attapulgite, white carbon black, calcium carbonate and a silane coupling agent, and the organic material POE and the inorganic fillers such as attapulgite and white carbon black are matched with each other to improve the compressive resistance of the pipe; although the inorganic filler is modified with a coupling agent, compared with the chemically modified organic substrate, the inorganic filler still has the technical defects of poor uniformity and further increased difficulty in processing the pipe material with distributed inorganic fillers. Summary of the invention

[0006] The object of the present invention is to provide a flame-retardant and pressure-resistant PVC electric power pipe and a preparation method thereof, so as to solve the technical problems in the prior art that in order to improve the flame-retardant and pressure-resistant properties of PVC electric power pipes, the added organic flame retardants are highly polluting and have poor environmental protection, the inorganic reinforcing materials and polyvinyl chloride are poorly incompatible, and the processing difficulty of the pipe materials distributed with inorganic fillers is further increased.

[0007] The purpose of the present invention can be achieved by the following technical scheme: A flame-retardant and pressure-resistant PVC electric power pipe, comprising, by weight, 50-60 parts of pressure-resistant polyvinyl chloride, 20-30 parts of acrylonitrile-butadiene-styrene terpolymer and 20-30 parts of mixed raw materials;

[0008] In parts by weight, the mixed raw materials include 10-15 parts of phosphazene composite flame retardant, 3-5 parts of epoxy soybean oil plasticizer, 5-8 parts of calcium zinc stabilizer, 0.1-0.5 parts of lubricant paraffin and 1-5 parts of glass fiber;

[0009] The method for preparing the phosphazene composite flame retardant comprises the following steps:

[0010] A1, hexachlorocyclotriphosphazene and tetrahydrofuran are mixed, stirred and dissolved to obtain a hexachlorocyclotriphosphazene solution; sodium hydride and tetrahydrofuran are mixed, stirred and dissolved under a nitrogen atmosphere to obtain a sodium hydride solution; allyl alcohol is then added dropwise to the sodium hydride solution at a rate of 1 mL / min, and the hexachlorocyclotriphosphazene solution is then added dropwise at a rate of 1 mL / min; after the addition is completed, the reaction is refluxed at 40-50° C. for 2-3 hours to obtain a product; the product is subjected to a post-process treatment to obtain an organic liquid polyallylphosphazene;

[0011] Hexachlorocyclotriphosphazene and allyl alcohol undergo nucleophilic substitution reaction to prepare polyallylphosphazene, the reaction formula of which is as follows:

[0012]

[0013] A2. Nitrogen is introduced into a laboratory reactor to replace the air in the reactor; toluene is then added into the laboratory reactor and heated in a water bath to 50-60°C; initiators azobisisobutyronitrile and diphenylparaphenylphosphine are added into the reactor, and polyallylphosphazene is then added dropwise into the reactor. After the addition is complete, the reactor is heated to 90-100°C and kept warm for reaction for 3-6 hours to obtain a phosphazene composite flame retardant.

[0014] The reaction formula of the phosphazene composite flame retardant obtained by the addition reaction of polyallyl phosphazene and diphenyl phosphine is as follows:

[0015]

[0016] Furthermore, in step A1, the ratio of hexachlorocyclotriphosphazene to tetrahydrofuran is 25-30 g:50 mL; the ratio of sodium hydride to tetrahydrofuran is 10-13 g:50 mL; the amount of allyl alcohol added dropwise is 20-30 mL, and the amount of hexachlorocyclotriphosphazene solution added dropwise is 60-70 mL.

[0017] Furthermore, in step A1, the post-process treatment includes: the product is naturally cooled to room temperature, and then the organic solvent tetrahydrofuran is removed by rotary evaporation to obtain a crude product; the crude product is washed with a 5-6%wt NaOH aqueous solution, a 2-3%wt HCl aqueous solution and distilled water in sequence to obtain an organic liquid; the organic liquid is dried with anhydrous sodium sulfate, and the anhydrous sodium sulfate is filtered to obtain an organic liquid polyallylphosphazene.

[0018] Furthermore, in step A2, the amounts of toluene, azobisisobutyronitrile, diphenyl phenylphosphine and polyallylphosphazene are 200 mL: 1-3 g: 20-25 g: 35-40 mL.

[0019] Furthermore, in step A1, the method for preparing the compression-resistant polyvinyl chloride comprises the following steps:

[0020] According to weight parts, 100 parts of polyvinyl chloride, 0.1-0.2 parts of catalyst zinc acetylacetonate and 5-15 parts of hexa(3-glycidyl ether phenoxy)triphosphazene are mixed and added into an internal mixer for internal mixing; wherein, the temperature of the internal mixer is 130-140° C., the speed of the internal mixer is 60-100 rpm, and the internal mixing time is 10-20 min.

[0021] Zinc acetylacetonate is used as a catalyst for the ring-opening reaction of hexa(3-glycidyl ether phenoxy) trimerphosphazene. Under high-temperature mixing conditions, the epoxy groups in polyvinyl chloride and the halogen of hexa(3-glycidyl ether phenoxy) trimerphosphazene undergo electrophilic addition reaction to prepare compression-resistant polyvinyl chloride.

[0022] Furthermore, the method for preparing the mixed raw materials comprises the following steps:

[0023] The phosphazene composite flame retardant, epoxy soybean oil plasticizer, calcium zinc stabilizer, lubricant and glass fiber are added into a mixer for mixing, and hot mixing and cold mixing are performed in sequence; wherein, the hot mixing temperature is 125-130° C., the hot mixing time is 20-30 seconds, the cold mixing time is 15-20 minutes, and the mixture is discharged at 25-35° C. to obtain the mixed raw material.

[0024] As another aspect of the present invention, the present invention also provides a method for preparing a flame-retardant and pressure-resistant PVC electric power pipe, comprising the following steps:

[0025] The pressure-resistant polyvinyl chloride, acrylonitrile-butadiene-styrene terpolymer and the mixed raw materials are added into a twin-screw extruder for melt extrusion, mixing and granulation, wherein the melt extrusion temperature is 170-190° C. and the melt pressure is 20-22 MPa.

[0026] Phosphazene composite flame retardant, epoxy soybean oil plasticizer, reinforcing auxiliary glass fiber and related auxiliary agents are pre-added in a mixer for mixing to obtain mixed raw materials. The mixed raw materials are then melt-extruded with an organic substrate to obtain flame-retardant and pressure-resistant PVC power pipes.

[0027] The present invention has the following beneficial effects:

[0028] 1. The flame-retardant and compression-resistant PVC electric power pipe prepared by the present invention includes an organic base material compression-resistant polyvinyl chloride, acrylonitrile-butadiene-styrene terpolymer, a phosphazene composite flame retardant, glass fiber, epoxy soybean oil plasticizer, calcium zinc stabilizer and lubricant paraffin. Among them, the phosphazene composite flame retardant, as a polymer, has a large number of benzene ring structures, thereby increasing its own melting point; in order to improve the melt dispersion of the phosphazene composite flame retardant and related additives, the present invention pre-adds the phosphazene composite flame retardant, glass fiber, epoxy soybean oil plasticizer, calcium zinc stabilizer and lubricant paraffin into a mixer for mixing to obtain the mixed raw material. The mixed raw material and the modified compression-resistant polyvinyl chloride and acrylonitrile-butadiene-styrene terpolymer organic base material are then melt-extruded to prepare the flame-retardant and compression-resistant PVC electric power pipe.

[0029] 2. The phosphazene composite flame retardant prepared by the present invention has high flame retardancy. Hexachlorocyclotriphosphazene is used as a monomer with a benzene ring structure, and then allyl alcohol is introduced to obtain a polyallyl phosphazene containing multiple double bonds; then, diphenyl paraphenyl phosphine with multiple benzene rings is introduced through an addition reaction, thereby preparing a phosphazene composite flame retardant with high benzene ring content and high nitrogen and phosphorus. The flame retardant mechanism of the phosphazene composite flame retardant designed by the present invention is similar to that of an intumescent flame retardant. When the composite flame retardant is decomposed by heat, it can produce nitrogen, nitrogen oxides and other flame-retardant gases, so that the combustible gas and oxygen on the surface of the material are diluted, and the surface temperature of the material can be reduced, thereby suppressing combustion. At the same time, the small amount of phosphorus contained in the phosphazene composite flame retardant can generate a certain amount of strong dehydrating agent at high temperature, and the flame-retardant material will form an expanded foam insulation layer after dehydration and carbonization. The phosphazene flame retardant prepared by the present invention does not contain halogen elements and heavy metal elements, has a low phosphorus content, and meets the requirements of halogen-free flame retardancy and green flame retardancy. The phosphazene composite flame retardant, which is an organic substance, is highly compatible with pressure-resistant polyvinyl chloride and acrylonitrile-butadiene-styrene terpolymer, so that the prepared PVC power pipe has uniform flame retardancy.

[0030] 3. As an organic phosphorus resin, hexa(3-glycidyl ether phenoxy) tripolyphosphazene contains a large amount of rigid benzene ring structure, which can significantly improve the rigidity of polyvinyl chloride by cross-linking with polyvinyl chloride, and prepare a high-strength compression-resistant polyvinyl chloride. In addition, hexa(3-glycidyl ether phenoxy) tripolyphosphazene contains a certain amount of phosphorus element, which can improve the flame retardant properties of compression-resistant polyvinyl chloride resin. In order to alleviate the drawbacks of poor toughness and impact performance caused by the high rigidity of compression-resistant polyvinyl chloride and phosphazene composite flame retardant, the electric power pipe prepared by the present invention also adds a certain amount of acrylonitrile-butadiene-styrene terpolymer, thereby improving the flexibility of the electric power pipe.

[0031] 4. In order to weaken the interaction between the molecular chains of polyvinyl chloride, a certain amount of plasticizer needs to be added when preparing PVC power pipes, thereby improving the processing performance of PVC pipes. In order to avoid the harm of traditional plasticizers to the natural environment and human health, epoxy soybean oil can be used as a plasticizer for polyvinyl chloride; adding a small amount of glass fiber can improve the compression resistance and aging resistance of PVC power pipes. The flame-retardant and compression-resistant PVC power pipes prepared by the present invention have the characteristics of high compression resistance, high flame retardancy and excellent mechanical properties. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing a phosphazene composite flame retardant for flame-retardant and pressure-resistant PVC electric power pipe, comprising the following steps:

[0035] A1. Mix 25g of hexachlorocyclotriphosphazene and 100mL of tetrahydrofuran, stir and dissolve to obtain a hexachlorocyclotriphosphazene solution. A 250mL, double-necked flat-bottomed flask is connected to a reflux device, a stirrer is added, and then nitrogen is filled so that the double-necked flat-bottomed flask is placed in a nitrogen atmosphere; then 10g of sodium hydride and 50mL of tetrahydrofuran are added to the double-necked flat-bottomed flask, and the stirrer is mixed and stirred at 100r / min until the sodium hydride is completely dissolved in tetrahydrofuran to obtain a sodium hydride solution. 20mL of allyl alcohol is added dropwise to the double-necked flat-bottomed flask at a rate of 1mL / min, and then 60mL of hexachlorocyclotriphosphazene solution is added dropwise at a rate of 1mL / min; after the addition is completed, an electric heating jacket is set on the outside of the double-necked flat-bottomed flask, accompanied by a stirring speed of 100r / min, and reflux reaction is carried out at 40°C for 2h to obtain the product.

[0036] A2. Remove the electric heating jacket from the double-necked flat-bottomed flask, cool naturally and let stand to room temperature, then remove the organic dissolved tetrahydrofuran by rotary evaporation to obtain a crude product. The crude product is washed with a 5%wt NaOH aqueous solution, a 2%wt HCl aqueous solution and distilled water in sequence to obtain an organic liquid. The organic liquid is dried over anhydrous sodium sulfate, and the anhydrous sodium sulfate solid is filtered to obtain an organic liquid polyallylphosphazene.

[0037] A3, 500mL laboratory reactor connected with thermometer, stirrer, dropping funnel, reflux condenser and inert gas inlet tube. Nitrogen is used to replace the air in the reactor through the inert gas inlet tube, and then 200mL of toluene is added to the laboratory reactor as the base material, and heated to 50°C in a water bath.

[0038] A4. Add 1 g of initiator azobisisobutyronitrile and 20 g of diphenyltriphenylphosphine into the reactor, and then add 35 mL of polyallylphosphazene dropwise through the dropping funnel of the reactor. After the addition is completed, heat the reactor to 90° C. and keep the temperature for 6 hours to obtain a phosphazene composite flame retardant.

[0039] Example 2

[0040] This embodiment provides a method for preparing a phosphazene composite flame retardant for flame-retardant and pressure-resistant PVC electric power pipe, comprising the following steps:

[0041] A1. Mix 28g of hexachlorocyclotriphosphazene and 100mL of tetrahydrofuran, stir and dissolve to obtain a hexachlorocyclotriphosphazene solution. A 250mL, double-mouthed flat-bottomed flask is connected to a reflux device, a stirrer is added, and then nitrogen is filled so that the double-mouthed flat-bottomed flask is placed in a nitrogen atmosphere; then 11g of sodium hydride and 50mL of tetrahydrofuran are added to the double-mouthed flat-bottomed flask, and the stirrer is mixed and stirred at 150r / min until the sodium hydride is completely dissolved in tetrahydrofuran to obtain a sodium hydride solution. 25mL of allyl alcohol is added dropwise to the double-mouthed flat-bottomed flask at a rate of 1mL / min, and then 65mL of hexachlorocyclotriphosphazene solution is added dropwise at a rate of 1mL / min; after the addition is completed, an electric heating jacket is set on the outside of the double-mouthed flat-bottomed flask, accompanied by a stirring speed of 130r / min, and reflux reaction is carried out at 45°C for 2.3h to obtain the product.

[0042] A2. Remove the electric heating jacket from the double-necked flat-bottomed flask, cool naturally and let stand to room temperature, then remove the organic dissolved tetrahydrofuran by rotary evaporation to obtain a crude product. The crude product is washed with a 5%wt NaOH aqueous solution, a 2%wt HCl aqueous solution and distilled water in sequence to obtain an organic liquid. The organic liquid is dried over anhydrous sodium sulfate, and the anhydrous sodium sulfate solid is filtered to obtain an organic liquid polyallylphosphazene.

[0043] A3, 500mL laboratory reactor connected with thermometer, stirrer, dropping funnel, reflux condenser and inert gas inlet tube. Nitrogen is used to replace the air in the reactor through the inert gas inlet tube, and 200mL of toluene is added to the laboratory reactor as the base material, and heated to 55°C in a water bath.

[0044] A4. Add 2 g of initiator azobisisobutyronitrile and 22 g of diphenyltriphenylphosphine into the reactor, and then add 36 mL of polyallylphosphazene dropwise through the dropping funnel of the reactor. After the addition is completed, heat the reactor to 95°C and keep the temperature for 5 hours to obtain a phosphazene composite flame retardant.

[0045] Example 3

[0046] This embodiment provides a method for preparing a phosphazene composite flame retardant for flame-retardant and pressure-resistant PVC electric power pipe, comprising the following steps:

[0047] A1. Mix 30g of hexachlorocyclotriphosphazene and 100mL of tetrahydrofuran, stir and dissolve to obtain a hexachlorocyclotriphosphazene solution. A 250mL, double-necked flat-bottomed flask is connected to a reflux device, a stirrer is added, and then nitrogen is filled so that the double-necked flat-bottomed flask is placed in a nitrogen atmosphere; then 13g of sodium hydride and 50mL of tetrahydrofuran are added to the double-necked flat-bottomed flask, and the stirrer is mixed and stirred at 200r / min until the sodium hydride is completely dissolved in tetrahydrofuran to obtain a sodium hydride solution. 30mL of allyl alcohol is added dropwise to the double-necked flat-bottomed flask at a rate of 1mL / min, and then 70mL of hexachlorocyclotriphosphazene solution is added dropwise at a rate of 1mL / min; after the addition is completed, an electric heating jacket is set on the outside of the double-necked flat-bottomed flask, accompanied by a stirring speed of 200r / min, and reflux reaction is carried out at 50°C for 3h to obtain the product.

[0048] A2. Remove the electric heating jacket from the double-necked flat-bottomed flask, cool naturally and let stand to room temperature, then remove the organic dissolved tetrahydrofuran by rotary evaporation to obtain a crude product. The crude product is washed with a 5%wt NaOH aqueous solution, a 2%wt HCl aqueous solution and distilled water in sequence to obtain an organic liquid. The organic liquid is dried over anhydrous sodium sulfate, and the anhydrous sodium sulfate solid is filtered to obtain an organic liquid polyallylphosphazene.

[0049] A3, 500mL laboratory reactor connected with thermometer, stirrer, dropping funnel, reflux condenser and inert gas inlet tube. Nitrogen is used to replace the air in the reactor through the inert gas inlet tube, and then 200mL of toluene is added to the laboratory reactor as the base material, and heated to 60℃ in a water bath.

[0050] A4. Add 3 g of initiator azobisisobutyronitrile and 25 g of diphenyltriphenylphosphine into the reactor, and then add 40 mL of polyallylphosphazene dropwise through the dropping funnel of the reactor. After the addition is completed, heat the reactor to 100° C. and keep the temperature for 3 hours to obtain a phosphazene composite flame retardant.

[0051] Example 4

[0052] This embodiment provides a method for preparing a compression-resistant polyvinyl chloride for a flame-retardant and compression-resistant PVC electric power pipe, comprising the following steps:

[0053] According to weight parts, 100 parts of polyvinyl chloride, 0.1 parts of catalyst zinc acetylacetonate and 5 parts of hexa(3-glycidyl ether phenoxy)triphosphazene were mixed and added to an internal mixer for internal mixing, and the internal mixing parameters of the internal mixer were set to 130° C., the internal mixing time was 10 minutes, and the speed of the internal mixer was 60 r / min. After the internal mixing was completed, the material was taken to obtain compressive polyvinyl chloride.

[0054] Example 5

[0055] This embodiment provides a method for preparing a compression-resistant polyvinyl chloride for a flame-retardant and compression-resistant PVC electric power pipe, comprising the following steps:

[0056] According to parts by weight, 100 parts of polyvinyl chloride, 0.15 parts of catalyst zinc acetylacetonate and 10 parts of hexa(3-glycidyl ether phenoxy)triphosphazene were mixed and added to an internal mixer for internal mixing, and the internal mixing parameters of the internal mixer were set to 135° C., the internal mixing time was 16 minutes, and the speed of the internal mixer was 80 r / min. After the internal mixing was completed, the material was taken to obtain a compression-resistant polyvinyl chloride.

[0057] Example 6

[0058] This embodiment provides a method for preparing a compression-resistant polyvinyl chloride for a flame-retardant and compression-resistant PVC electric power pipe, comprising the following steps:

[0059] According to weight parts, 100 parts of polyvinyl chloride, 0.2 parts of catalyst zinc acetylacetonate and 15 parts of hexa(3-glycidyl ether phenoxy)triphosphazene were mixed and added to an internal mixer for internal mixing, and the internal mixing parameters of the internal mixer were set to 140° C., the internal mixing time was 20 minutes, and the speed of the internal mixer was 100 r / min. After the internal mixing was completed, the material was taken to obtain compression-resistant polyvinyl chloride.

[0060] Example 7

[0061] This embodiment provides a method for preparing a flame-retardant and pressure-resistant PVC electric power pipe, comprising the following steps:

[0062] 1. According to parts by weight, 10 parts of the phosphazene composite flame retardant prepared in Example 3, 3 parts of epoxy soybean oil plasticizer, 5 parts of calcium zinc stabilizer, 0.1 parts of lubricant paraffin, and 1 part of glass fiber are added to a mixer in sequence for mixing; the hot mixing temperature of the mixer is controlled at 125°C and the hot mixing time is 20s; then the heating is stopped and cold mixing is performed for 15min. The mixture is discharged when the temperature is 35°C to obtain the mixed raw materials, and the mixed raw materials are allowed to stand for 12h.

[0063] 2. According to weight parts, 50 parts of the compression-resistant polyvinyl chloride prepared in Example 6, 20 parts of acrylonitrile-butadiene-styrene terpolymer and 20 parts of the mixed raw materials are added to a twin-screw extruder for melt extrusion, mixing and granulation. The screw type is a high-efficiency low-calcium twin-screw, the screw diameter is 80 mm, the screw speed is 15 r / min, the melt extrusion temperature is 170°C, and the melt pressure is 20 MPa.

[0064] Example 8

[0065] This embodiment provides a method for preparing a flame-retardant and pressure-resistant PVC electric power pipe, comprising the following steps:

[0066] 1. According to parts by weight, 12 parts of the phosphazene composite flame retardant prepared in Example 3, 4 parts of epoxy soybean oil plasticizer, 6 parts of calcium zinc stabilizer, 0.35 parts of lubricant paraffin, and 3 parts of glass fiber are added to a mixer in sequence for mixing; the hot mixing temperature of the mixer is controlled at 128°C and the hot mixing time is 25s; then the heating is stopped and cold mixing is performed for 18min. The mixture is discharged when the temperature is 30°C to obtain the mixed raw materials, and the mixed raw materials are allowed to stand for 12h.

[0067] 2. According to weight parts, 55 parts of the compression-resistant polyvinyl chloride prepared in Example 6, 25 parts of acrylonitrile-butadiene-styrene terpolymer and 25 parts of the mixed raw materials are added to a twin-screw extruder for melt extrusion, mixing and granulation. The screw type is a high-efficiency low-calcium twin-screw, the screw diameter is 80 mm, the screw speed is 20 r / min, the melt extrusion temperature is 180°C, and the melt pressure is 20 MPa.

[0068] Example 9

[0069] This embodiment provides a method for preparing a flame-retardant and pressure-resistant PVC electric power pipe, comprising the following steps:

[0070] 1. According to parts by weight, 15 parts of the phosphazene composite flame retardant prepared in Example 3, 5 parts of epoxy soybean oil plasticizer, 8 parts of calcium zinc stabilizer, 0.5 parts of lubricant paraffin, and 5 parts of glass fiber are added to a mixer in sequence for mixing; the hot mixing temperature of the mixer is controlled at 130°C and the hot mixing time is 30s; then the heating is stopped and cold mixing is performed for 20min. The mixture is discharged when the temperature is 25°C to obtain the mixed raw materials, and the mixed raw materials are allowed to stand for 12h.

[0071] 2. According to weight parts, 60 parts of the compression-resistant polyvinyl chloride prepared in Example 6, 30 parts of acrylonitrile-butadiene-styrene terpolymer and 30 parts of the mixed raw materials are added to a twin-screw extruder for melt extrusion, mixing and granulation. The screw type is a high-efficiency low-calcium twin-screw, the screw diameter is 80 mm, the screw speed is 30 r / min, the melt extrusion temperature is 190°C, and the melt pressure is 22 MPa.

[0072] Comparative Example 1

[0073] The present invention is based on the flame-retardant and compression-resistant PVC power pipe prepared in Example 9, and replaces the compression-resistant polyvinyl chloride with polyvinyl chloride of equal quality.

[0074] Comparative Example 2

[0075] Based on the flame-retardant and pressure-resistant PVC electric power pipe prepared in Example 9, the present invention uses organic liquid polyallylphosphazene to replace the phosphazene composite flame retardant when preparing the phosphazene composite flame retardant.

[0076] Comparative Example 3

[0077] The present invention is based on the flame-retardant and pressure-resistant PVC electric power pipe prepared in Example 9, and when preparing the mixed raw materials, the plasticizer epoxy soybean oil is replaced by dioctyl phthalate of equal mass.

[0078] Performance Test:

[0079] 1. The flame-retardant and compression-resistant PVC electric power pipes prepared in Examples 7-9 and Comparative Examples 1-3 were cut into 4×75 dumbbell samples with a thickness of 1 mm. According to GB / T1040-2018 "Determination of Tensile Properties of Plastics", the tensile strength and elongation at break of the flame-retardant and compression-resistant PVC electric power pipes prepared in Examples 7-9 and Comparative Examples 1-3 were tested using a universal mechanical testing machine, wherein the tensile speed was 250 mm / min.

[0080] 2. Cut the flame-retardant and compression-resistant PVC electric power pipes prepared in Examples 7-9 and Comparative Examples 1-3 into samples with a specification of 100mm×13mm×3mm. According to ASTM3801-10 "Plastic Vertical Burning Test", a vertical burning test was performed on the flame-retardant and compression-resistant PVC electric power pipes prepared in Examples 7-9 and Comparative Examples 1-3 using a CZF-3 vertical burning tester to detect whether they meet the UL-94 grade requirements.

[0081] 3. The flame-retardant and compression-resistant PVC power pipes prepared in Examples 7-9 and Comparative Examples 1-3 were prepared into pipe test specimens, and the compression resistance of the flame-retardant and compression-resistant PVC power pipes prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with GB / T5350-2005 "Test Method for Axial Compression Performance of Fiber-Reinforced Thermosetting Plastics". A 200T ordinary pressure testing machine was used, and a graded loading method was adopted. After each level of loading was completed, data was collected at intervals of 1 minute, and then the next level was loaded to determine the value of its average breaking stress. The specific test results are shown in Table 1:

[0082] Table 1- Sample performance test data table

[0083]

[0084] Data Analysis:

[0085] By comparing and analyzing the data in Table 1, the flame-retardant and compression-resistant PVC electric power pipes prepared in Examples 7-9 of the present invention have excellent mechanical properties and compression resistance, which are reflected in the high values ​​of tensile strength, elongation at break and average breaking stress. However, in Comparative Example 1, polyvinyl chloride is used instead of compressive polyvinyl chloride, and its tensile strength, elongation at break and average breaking stress values ​​are all reduced.

[0086] The flame-retardant and compression-resistant PVC electric power pipes prepared in Examples 7-9 of the present invention have excellent flame retardancy, as shown by their vertical burning ratings all reaching UL-94 rating. However, in Comparative Example 2, since the organic liquid polyallyl phosphazene is used to replace the phosphazene composite flame retardant, its own flame retardancy is reduced, which is manifested as failure to pass the vertical burning rating test.

[0087] In Comparative Example 3, the plasticizer epoxy soybean oil was replaced with dioctyl phthalate of equal mass. The mechanical properties, compressive properties and flame retardant properties of the flame-retardant and compression-resistant PVC power pipe prepared in Comparative Example 3 were similar to those of Examples 7-9, indicating that the environmentally friendly plasticizer epoxy soybean oil has excellent plasticizing properties for PVC power pipes and can replace commonly used chemical plasticizers.

[0088] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0089] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0090] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A flame-retardant and pressure-resistant PVC power pipe, characterized in that: The invention comprises, by weight, 50-60 parts of compression-resistant polyvinyl chloride, 20-30 parts of acrylonitrile-butadiene-styrene terpolymer and 20-30 parts of the mixed raw materials; In parts by weight, the mixed raw materials include 10-15 parts of phosphazene composite flame retardant, 3-5 parts of epoxy soybean oil plasticizer, 5-8 parts of calcium zinc stabilizer, 0.1-0.5 parts of lubricant paraffin and 1-5 parts of glass fiber; The method for preparing the phosphazene composite flame retardant comprises the following steps: A1, hexachlorocyclotriphosphazene and tetrahydrofuran are mixed, stirred and dissolved to obtain a hexachlorocyclotriphosphazene solution; sodium hydride and tetrahydrofuran are mixed, stirred and dissolved under a nitrogen atmosphere to obtain a sodium hydride solution; allyl alcohol is added dropwise to the sodium hydride solution at a rate of 1 mL / min, and then the hexachlorocyclotriphosphazene solution is added dropwise at a rate of 1 mL / min; after the addition is completed, reflux reaction is carried out at 40-50° C. for 2-3 hours to obtain a product; the product is subjected to post-process treatment to obtain an organic liquid polyallylphosphazene; A2. Nitrogen is introduced into the reactor to replace the air in the reactor; toluene is then added into the reactor and heated in a water bath to 50-60°C; initiators azobisisobutyronitrile and diphenylparaphenylphosphine are added into the reactor, and polyallylphosphazene is then added dropwise into the reactor. After the addition is complete, the reactor is heated to 90-100°C and kept warm for reaction for 3-6 hours to obtain a phosphazene composite flame retardant.

2. The flame-retardant and pressure-resistant PVC electric power pipe according to claim 1, characterized in that: In step A1, the amount ratio of hexachlorocyclotriphosphazene to tetrahydrofuran is 25-30 g:50 mL; the amount ratio of sodium hydride to tetrahydrofuran is 10-13 g:50 mL; the amount of allyl alcohol added dropwise is 20-30 mL, and the amount of hexachlorocyclotriphosphazene solution added dropwise is 60-70 mL.

3. The flame-retardant and pressure-resistant PVC electric power pipe according to claim 2, characterized in that: In step A1, the post-process treatment includes: the product is naturally cooled to room temperature, and then the organic solvent tetrahydrofuran is removed by rotary evaporation to obtain a crude product; the crude product is washed with a 5-6%wt NaOH aqueous solution, a 2-3%wt HCl aqueous solution and distilled water in sequence to obtain an organic liquid; the organic liquid is dried with anhydrous sodium sulfate, and the anhydrous sodium sulfate is filtered to obtain an organic liquid polyallylphosphazene.

4. The flame-retardant and pressure-resistant PVC electric power pipe according to claim 1, characterized in that: In step A2, the usage ratio of toluene, azobisisobutyronitrile, diphenyl phenylphosphine and polyallylphosphazene is 200 mL: 1-3 g: 20-25 g: 35-40 mL.

5. The flame-retardant and pressure-resistant PVC electric power pipe according to claim 1, characterized in that: In step A1, the method for preparing the pressure-resistant polyvinyl chloride comprises the following steps: According to weight parts, 100 parts of polyvinyl chloride, 0.1-0.2 parts of catalyst zinc acetylacetonate and 5-15 parts of hexa(3-glycidyl ether phenoxy)triphosphazene are mixed and added into an internal mixer for internal mixing; wherein, the temperature of the internal mixer is 130-140° C., the speed of the internal mixer is 60-100 rpm, and the internal mixing time is 10-20 min.

6. The flame-retardant and pressure-resistant PVC electric power pipe according to claim 1, characterized in that: The method for preparing the mixed raw materials comprises the following steps: Add phosphazene composite flame retardant, epoxy soybean oil plasticizer, calcium zinc stabilizer, lubricant paraffin and glass fiber into a mixer, and perform hot mixing and cold mixing in sequence; wherein, the hot mixing temperature is 125-130°C, the hot mixing time is 20-30s, and the cold mixing time is 15-20min; the mixed material is discharged at 25-35°C to obtain the mixed raw material.

7. A method for preparing the flame-retardant and pressure-resistant PVC electric power pipe according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: adding pressure-resistant polyvinyl chloride, acrylonitrile-butadiene-styrene terpolymer and mixed raw materials into a twin-screw extruder for melt extrusion and mixing and granulation, wherein the melt extrusion temperature is 170-190° C. and the melt pressure is 20-22 MPa.

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