Low-temperature-resistant high-strength PVC (polyvinyl chloride) insulating electrical conduit and preparation method thereof

Abstract

The invention belongs to the technical field of PVC (polyvinyl chloride) insulating electrical bushings for buildings, and particularly discloses a low-temperature-resistant high-strength PVC insulating electrical bushing which comprises the following raw materials in parts by weight: 90-110 parts of PVC resin; 2.5 to 4.5 parts of a calcium zinc stabilizer; 0.2 to 0.8 part of an internal lubricant; 0.4 to 1.5 parts of an external lubricant; 0.2 to 0.5 part of a release agent; 0.5 to 2.0 parts of a processing aid; 30-40 parts of an inorganic modified filler; 4-10 parts of a toughening agent; and 0.8 to 2.0 parts of titanium dioxide. The low-temperature-resistant and high-strength PVC insulating electrical conduit provided by the invention has the characteristics of pressure resistance and low-temperature resistance, easiness in production and processing, high strength, excellent low-temperature resistance and the like, and is suitable for production and processing in regions and environments with different seasons and different air temperatures.

Description

Technical Field

[0001] The invention belongs to the technical field of PVC insulating electrical conduits for buildings, and in particular relates to a low-temperature resistant high-strength PVC insulating electrical conduit and a preparation method thereof. Background Art

[0002] PVC insulated electrical conduit is one of the most commonly used conduits inside buildings and is often used for the laying of cables and wires. Compared with traditional buckled thin-walled steel pipes (KBG pipes for short), tight-fitting thin-walled steel pipes (JDG pipes for short) and welded steel pipes, it has the advantages of light material, corrosion resistance, smooth inner and outer walls, leakage prevention, self-flame retardant, excellent insulation, good anti-aging ability, complete varieties and accessories, long service life, easy construction and installation, etc. It is widely used in various places and environments with high temperature, dust, vibration, fire hazards and dangers, and is greatly favored by the market and customers.

[0003] Due to the low toughness and poor impact resistance of PVC materials, PVC insulated electrical conduits are prone to brittle fracture during storage, transportation, installation and use, which is particularly obvious in low temperature environments. In particular, when used in cold areas in winter, PVC insulated electrical conduits are prone to abnormal quality problems such as bending, wrinkling, and brittle fracture, which seriously affects their further promotion and use. In order to solve the above problems, a large amount of elastomer modified toughening agents (such as CPE, ACR, etc.) need to be added to the formula of PVC insulated electrical conduits to be blended and modified with PVC resin. In this case, it often leads to defects such as soft tube blanks affecting production efficiency and poor compression resistance of the conduits (especially in summer and areas with high temperatures) during the production of PVC insulated electrical conduits. Generally, manufacturers also use different formulas for production, storage and sales management according to different seasons, which brings great inconvenience and cost increase to the manufacturing and management of manufacturers. Summary of the invention

[0004] The purpose of the present invention is to overcome the above problems existing in the prior art and provide a low-temperature resistant high-strength PVC insulated electrical conduit, which can take into account both pressure resistance and low-temperature resistance, and has the characteristics of easy production and processing, high strength, and excellent low-temperature resistance. Moreover, the low-temperature resistant high-strength PVC insulated electrical conduit is suitable for production and processing in different seasons, different temperature areas and environments.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides a low-temperature resistant and high-strength PVC insulated electrical conduit, comprising the following raw materials in parts by weight: 90 to 110 parts of PVC resin; 2.5 to 4.5 parts of calcium zinc stabilizer; 0.2 to 0.8 parts of internal lubricant; 0.4 to 1.5 parts of external lubricant; 0.2 to 0.5 parts of release agent; 0.5 to 2.0 parts of processing aid; 30 to 40 parts of inorganic modified filler; 4 to 10 parts of toughening agent; and 0.8 to 2.0 parts of titanium dioxide.

[0007] Furthermore, the PVC resin is SG-5 type resin;

[0008] The viscosity of the PVC resin is 107-118.

[0009] Further, the internal lubricant is any one or more of aliphatic dicarboxylic acid esters, long-chain fatty acid esters, fatty acid metal soaps and polyol fatty acid amides mixed in any proportion;

[0010] The external lubricant is any one or more of polyethylene wax, Fischer-Tropsch wax and paraffin wax mixed in any proportion.

[0011] Furthermore, the release agent is any one or more of high-density oxidized polyethylene wax and ethylene bisstearamide mixed in any proportion.

[0012] Furthermore, the processing aid is acrylonitrile / styrene copolymer, and the viscosity of the acrylonitrile / styrene copolymer is 11-13 cP.

[0013] Furthermore, the toughening agent is any one or more of nitrile rubber, MBS resin, and chlorinated polyethylene mixed in any proportion; further, the nitrile rubber is in powder form, the acrylonitrile content in the nitrile rubber is 25% to 35%, and the particle size of the powdered nitrile rubber is 60 mesh to 100 mesh.

[0014] Furthermore, the titanium dioxide is rutile titanium dioxide.

[0015] Furthermore, the inorganic modified filler is prepared by treating an inorganic filler with a surface treatment agent;

[0016] The inorganic filler is prepared by mixing a stone powder raw material and a calcium carbonate raw material;

[0017] The stone powder raw material is talcum powder or wollastonite powder, the silicon dioxide content of the talcum powder and the wollastonite powder is 40-50%, the whiteness of the talcum powder and the wollastonite powder is not less than 93%, and the D50 of the talcum powder and the wollastonite powder is not greater than 6.5 μm;

[0018] The calcium carbonate raw material is any one or more of heavy calcium carbonate and light calcium carbonate mixed in any proportion;

[0019] The surface treatment agent is a mixture of stearic acid and a silane coupling agent.

[0020] Furthermore, the preparation method of the inorganic modified filler includes the following steps: putting stone powder raw material and calcium carbonate raw material into a high-speed mixer to obtain an inorganic filler; when the temperature rises to 80-85°C, adding a surface treatment agent to the inorganic filler; continuing to heat to 110-115°C; after mixing for 20 minutes, stopping high-speed mixing, cooling the discharged material, and obtaining an inorganic modified filler.

[0021] Furthermore, the mass ratio of the inorganic filler to the surface treatment agent is 100:(2-3).

[0022] In a second aspect, the present invention provides a method for preparing a low-temperature resistant high-strength PVC insulated electrical casing, the preparation method comprising the following steps:

[0023] S1: Add PVC resin, calcium zinc stabilizer, internal lubricant, processing aid, toughening agent and titanium dioxide into a high-speed mixer, mix and stir, fully mix and evenly prepare a mixed material, heat it to 80-85° C., add external lubricant, release agent and inorganic modified filler into the mixed material, continue to mix and prepare a premix, continue to heat it to 120-130° C., send the premix into a cooling mixer and stir at a low speed, cool it to 45-55° C. and discharge it to prepare a cold mix;

[0024] S2: The cold mixed material is screened through a vibrating screen to remove lumps, and then transported to a storage tank for standing and maturing for 2 to 4 hours to obtain a mixed material;

[0025] S3: The mixed materials are conveyed to a twin-screw extruder for plasticization and extrusion. The extruded billet is first shaped by a sizing sleeve on the billet outlet die, then enters a vacuum box, and then enters a water tank for cooling and shaping. Finally, it is printed, measured and cut to obtain a low-temperature resistant and high-strength PVC insulated electrical conduit.

[0026] Furthermore, in step S3, during the process of conveying the mixed materials to the twin-screw extruder for plasticizing and extruding, the barrel processing temperature of the twin-screw extruder is 170-190° C., the mold temperature is 190-210° C., and the main screw speed is 60-75 r / min.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention provides a low-temperature resistant and high-strength PVC insulated electrical conduit. Inorganic modified fillers, nitrile rubber (NBR), methyl methacrylate-butadiene-styrene copolymer (MBS resin), and chlorinated polyethylene (CPE) are added to the raw material formula, and the above additives are reasonably proportioned to achieve a synergistic effect. Specifically, on the one hand, NBR, MBS resin, and CPE form a "sea-island" microstructure with the continuous phase of PVC resin in the form of a dispersed phase, and the low-temperature toughening effect is significant; on the other hand, the talc powder or wollastonite powder in the inorganic modified filler has a needle-like and layered fiber structure, which greatly improves the rigidity and heat resistance of the composite material system. At the same time, this needle-like and layered fiber structure has a large aspect ratio, which also plays a role in improving the toughness of the system; therefore, the effective combination of inorganic modified fillers (inorganic powder modification) and organic elastomer (NBR, MBS resin, CPE) toughening can make the prepared PVC insulated electrical conduit have low-temperature resistance while improving rigidity and heat resistance.

[0029] 2. The inorganic modified filler in the present invention is prepared by selecting talcum powder or wollastonite powder with high whiteness and medium silicon dioxide content, mixing it with heavy calcium carbonate and / or light calcium carbonate, and then surface-treating it with stearic acid and a silane coupling agent. This greatly improves the dispersibility of the inorganic powder and its compatibility with the PVC resin, improves the stress deformation ability and absorption capacity of the composite system at low temperatures, and forms a rigid-tough balance with the organic elastic toughening system.

[0030] 3. In the present invention, high-density oxidized polyethylene wax and ethylene bisstearamide are used as release agents, both of which have good internal and external lubrication and demolding ability, can improve the fluidity and demolding properties of the molten material during extrusion processing, can effectively reduce the negative impact of the use of inorganic modified fillers on the appearance gloss of the product, improve the surface gloss and brightness of the pipe, and at the same time extend the demolding cycle of the mold, improve production efficiency, and reduce production costs.

[0031] 4. The processing aids and lubricants used in the present invention, in addition to improving the overall dispersibility and processing performance of the material system, are also used to improve the adverse effects of using rubber toughening agents on the processing fluidity of the material system, making it easy to extrude and mold, and having high production stability.

[0032] 5. In the present invention, internal lubricants and external lubricants are used to form a complementary lubrication system, which can comprehensively improve the processing performance of the pipe, improve product quality and production efficiency; in addition, high-density oxidized polyethylene wax and ethylene bisstearamide are used as release agents, which also have certain internal and external lubricating effects, and synergize with internal lubricants and external lubricants, and have the advantages of improving processing performance, improving product quality and optimizing production efficiency.

[0033] 6. The internal lubricant and external lubricant used in the present invention are polarly compatible with PVC. The internal lubricant with different melting ranges and structures can ensure that the PVC melt has sufficient melt strength, ductility and fluidity at different stages and forms of processing. Matching with a suitable external lubricant can form a good surface film in different areas of the mold, reduce the shear flow difference between the inside and outside of the PVC melt and the difficulty of production and processing, and improve the appearance of the pipe to a large extent while improving the production efficiency, and the smoothness of the inner and outer surfaces is improved. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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.

[0035] In a first aspect, the present invention provides a low-temperature resistant and high-strength PVC insulated electrical conduit, comprising the following raw materials in parts by weight: 90 to 110 parts of PVC resin; 2.5 to 4.5 parts of calcium zinc stabilizer; 0.2 to 0.8 parts of internal lubricant; 0.4 to 1.5 parts of external lubricant; 0.2 to 0.5 parts of release agent; 0.5 to 2.0 parts of processing aid; 30 to 40 parts of inorganic modified filler; 4 to 10 parts of toughening agent; and 0.8 to 2.0 parts of titanium dioxide.

[0036] Among them, the PVC resin is SG-5 type resin, and the viscosity of the PVC resin used is 107-118;

[0037] Calcium zinc stabilizer is an environmentally friendly calcium zinc stabilizer, its main ingredients are zinc stearate, calcium stearate, etc.

[0038] The internal lubricant is any one or more of aliphatic dicarboxylic acid esters, long-chain fatty acid esters, fatty acid metal soaps and polyol fatty acid amides mixed in any proportion;

[0039] The external lubricant is any one or more of polyethylene wax, Fischer-Tropsch wax and paraffin wax mixed in any proportion;

[0040] The release agent is any one or more of high-density oxidized polyethylene wax and ethylene bisstearamide (EBS) mixed in any proportion;

[0041] The processing aid is acrylonitrile / styrene copolymer; the viscosity of acrylonitrile / styrene copolymer is 11-13 cP;

[0042] The toughening agent is any one or more of nitrile rubber, MBS resin, and chlorinated polyethylene mixed in any proportion;

[0043] Titanium dioxide is rutile titanium dioxide;

[0044] Among them, the inorganic modified filler is prepared by treating the inorganic filler with a surface treatment agent;

[0045] The inorganic filler is prepared by mixing stone powder raw materials and calcium carbonate raw materials;

[0046] The stone powder raw material is talcum powder or wollastonite powder, wherein the silicon dioxide content of the talcum powder or wollastonite powder used is 40-50%, the whiteness is not less than 93%, and the D50 is not greater than 6.5μm;

[0047] The calcium carbonate raw material is any one or more of heavy calcium carbonate and light calcium carbonate mixed in any proportion;

[0048] The surface treatment agent is a mixture of stearic acid and a silane coupling agent; in the surface treatment agent, the ratio of stearic acid to the silane coupling agent can be any ratio; more specifically, in the surface treatment agent, the ratio of stearic acid to the silane coupling agent can be (0.5-1.0): (1.5-2.0);

[0049] Specifically, the preparation method of the inorganic modified filler includes the following steps: putting stone powder raw material and calcium carbonate raw material into a high-speed mixer to obtain an inorganic filler; when the temperature rises to 80-85°C, adding a surface treatment agent to the inorganic filler, wherein the mass ratio of the inorganic filler to the surface treatment agent is 100:(2-3); continuing to heat to 110-115°C, mixing for 20 minutes, stopping high-speed mixing, cooling the discharged material, and obtaining an inorganic modified filler.

[0050] In a second aspect, the present invention provides a method for preparing a low-temperature resistant high-strength PVC insulated electrical casing, characterized in that the preparation method comprises the following steps:

[0051] S1: Add PVC resin, calcium zinc stabilizer, internal lubricant, processing aid, toughening agent and titanium dioxide into a high-speed mixer, mix and stir, fully mix and evenly prepare a mixed material, heat it to 80-85° C., add external lubricant, release agent and inorganic modified filler into the mixed material, continue to mix and prepare a premix, continue to heat it to 120-130° C., send the premix into a cooling mixer and stir at a low speed, cool it to 45-55° C. and discharge it to prepare a cold mix;

[0052] S2: The cold mixed material is screened through a vibrating screen to remove lumps, and then transported to a storage tank for standing and maturing for 2 to 4 hours to obtain a mixed material;

[0053] S3: The mixed materials are conveyed to a twin-screw extruder for plasticizing and extruding. During the plasticizing and extruding process, the barrel processing temperature of the twin-screw extruder is 170-190°C, the mold temperature is 190-210°C, the main engine screw speed is 60-75r / min, the main engine current is 80-85%, and the melt pressure is 19.5-21.5MPa. The extruded billet is first shaped by a sizing sleeve on the billet outlet die, and then enters a vacuum box, and then enters a water tank for cooling and shaping, and finally is printed, measured and cut to obtain a low-temperature resistant and high-strength PVC insulated electrical conduit.

[0054] The following are specific examples. In the following examples, unless otherwise specified, all raw materials can be obtained from commercial sources.

[0055] In the following examples and comparative examples, the calcium zinc stabilizer is a conventional environmentally friendly calcium zinc stabilizer; the internal lubricant is an aliphatic dicarboxylic acid ester; the external lubricant is polyethylene wax; and the release agent is a mixture of high-density oxidized polyethylene wax and ethylene bisstearamide in a mass ratio of 1:1.

[0056] Example 1

[0057] The present embodiment provides a low-temperature resistant and high-strength PVC insulated electrical conduit, comprising the following raw materials in parts by weight: 100 parts of PVC resin, 4.5 parts of calcium zinc stabilizer, 0.8 parts of internal lubricant, 1.5 parts of external lubricant, 0.5 parts of release agent, 2.0 parts of processing aid, 40 parts of inorganic modified filler, 10 parts of toughening agent, and 2.0 parts of titanium dioxide.

[0058] The toughening agent is a mixture of NBR, MBS resin and CPE, and the mass ratio of NBR, MBS resin and CPE in the toughening agent is 3:2:5;

[0059] The inorganic modified filler is prepared by surface treatment of 37.5 parts of talc, 37.5 parts of heavy calcium carbonate and 25 parts of light calcium carbonate with stearic acid and a silane coupling agent; specifically, the preparation method of the inorganic modified filler is as follows: 37.5 parts of talc, 37.5 parts of heavy calcium carbonate and 25 parts of light calcium carbonate are put into a high-speed mixer, and when the temperature rises to 85° C., 1.0 parts by weight of stearic acid and 2.0 parts by weight of a silane coupling agent are added, the temperature is continued to rise to 115° C., mixed for 20 minutes, and finally the high-speed mixing is stopped, and the material is cooled to obtain the inorganic modified filler;

[0060] This embodiment also provides a method for preparing a low-temperature resistant high-strength PVC insulated electrical conduit, the preparation method comprising the following steps:

[0061] S1: Weigh PVC resin, calcium zinc stabilizer, internal lubricant, external lubricant, release agent, processing aid, inorganic modified filler, toughening agent, and titanium dioxide according to the mass parts in the above formula;

[0062] S2: Add PVC resin, calcium zinc stabilizer, internal lubricant, processing aid, toughening agent, and titanium dioxide into a high-speed mixer and start mixing and stirring; after being fully mixed, a mixed material is prepared, the temperature is raised to 85° C., an external lubricant, a release agent, and an inorganic modified filler are added, and the mixing is continued to prepare a premix, the temperature is continued to be raised to 130° C., the premix is ​​sent to a cooling mixer for stirring, and the premix is ​​cooled to 55° C. and discharged to prepare a cold mix;

[0063] S3: The cold mixed material is screened through a vibrating screen to remove lumps, and then transported to a storage tank for standing and maturing for 4 hours to obtain a mixed material;

[0064] S4: Set the barrel temperature of the twin-screw extruder to 180°C, the mold temperature to 200°C, the screw speed to 70r / min, and the main engine current to 80%; convey the mixed materials to the above twin-screw extruder for plasticization and extrusion, and the extruded billet is first shaped by the sizing sleeve on the billet outlet die, enters the vacuum box, and then enters the water tank for cooling and shaping, and finally is printed, measured and cut to obtain a low-temperature resistant and high-strength PVC insulated electrical conduit.

[0065] In Examples 2 to 6 and Comparative Examples 1 to 3, the preparation methods of the low-temperature resistant high-strength PVC insulated electrical conduits provided are the same as those in Example 1, and the difference from Example 1 is that in Examples 2 to 6 and Comparative Examples 1 to 3, the raw material amounts and raw material compositions of the low-temperature resistant high-strength PVC insulated electrical conduits are different. In terms of weight fraction, the raw material compositions of the low-temperature resistant high-strength PVC insulated electrical conduits provided in Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Tables 1 and 2, respectively;

[0066] Table 1 Raw material composition of low temperature resistant high strength PVC insulated electrical conduits in Examples 1 to 6

[0067]

[0068] Table 2 Raw material composition of low temperature resistant high strength PVC insulated electrical conduits in comparative examples 1 to 3

[0069] Raw material components Comparative Example 1 Comparative Example 2 Comparative Example 3 PVC resin 100 100 100 Calcium zinc stabilizer 4.0 4.2 3.9 Internal lubricant 0.6 0.4 0.5 External lubricant 0.8 0.6 0.5 Release agent 1.0 0.8 0.6 Processing Aids 2.5 2.0 1.5 Heavy calcium carbonate 40.0 0.0 15.0 Light calcium carbonate 0.0 35.0 15.0 ACR Resin 5.0 0.0 2.0 Toughening agent 5.0 8.0 4.0 Titanium dioxide 2.0 2.0 2.0

[0070] Note: In Table 2, ACR resin is an acrylic copolymer with a core-shell structure, which has the functions and effects of increasing the toughness of PVC resin, improving processing performance, promoting plasticization, and improving the surface quality of products.

[0071] Experimental example

[0072] The PVC insulated electrical conduits (specification 305-20) prepared in the above Examples 1 to 6 and Comparative Examples 1 to 3 were tested for performance according to the standard JG / T 3050-1998 "Insulated electrical conduits and accessories for construction", and the test results are shown in Tables 3 and 4;

[0073] Table 3 Performance test results of low temperature resistant high strength PVC insulated electrical conduits in Examples 1 to 6

[0074]

[0075] Table 4 Performance test results of low temperature resistant high strength PVC insulated electrical conduits in comparative examples 1 to 3

[0076]

[0077] According to the performance test results in Table 3 and Table 4, it can be seen that the PVC insulated electrical conduit prepared by using the formula provided by the present invention has significantly higher test results of low-temperature impact performance, low-temperature bending performance, compression resistance and other indicators than Comparative Examples 1 to 3, indicating that the low-temperature resistant and high-strength PVC insulated electrical conduit provided by the present invention can take into account both compression resistance and low-temperature resistance.

[0078] The invention provides a low-temperature resistant high-strength PVC insulated electrical conduit. An inorganic modified filler, acrylonitrile rubber (NBR), methyl methacrylate-butadiene-styrene copolymer (MBS resin) and chlorinated polyethylene (CPE) are added to the raw material formula of the PVC insulated electrical conduit, and the additives are reasonably proportioned to achieve a synergistic effect. Specifically, on the one hand, NBR, MBS resin and CPE form a "sea-island" microstructure with a PVC resin continuous phase in the form of a dispersed phase, and the low-temperature toughening effect is remarkable. On the other hand, the talc powder or wollastonite powder in the inorganic modified filler has a needle-shaped and layered fiber structure, which greatly improves the rigidity and heat resistance of the composite material system. At the same time, the needle-shaped and layered fiber structure has a large aspect ratio and also plays a role in improving the toughness of the system. Therefore, the effective combination of the inorganic modified filler (inorganic powder modification) and the toughening of an organic elastomer (NBR, MBS resin, CPE) can make the prepared PVC insulated electrical conduit have low-temperature resistance, while the rigidity strength and heat resistance are improved.

[0079] The internal lubricant and external lubricant used in the present invention are polarly compatible with PVC. The internal lubricant with different melting ranges and structures can ensure that the PVC melt has sufficient melt strength, ductility and fluidity at different stages and forms of processing, and can be matched with a suitable external lubricant, especially can form a good surface film in different areas of the mold, reduce the shear flow difference between the inside and outside of the PVC melt and the difficulty of production and processing, and can improve the appearance of the pipe to a large extent while improving the production efficiency, and improve the smoothness of the inner and outer surfaces. Specifically, in actual production, taking the production of 305-20 pipes as an example, the main engine speed is 70r / min. By implementing the present invention, it is actually verified that the melt pressure can be reduced from 22.0MPa to 20.5MPa, the main engine current is reduced from 88% to 83%, and the one-out four-mold production line speed can be increased from 64m / min to 66m / min.

[0080] 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.

[0081] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A low temperature resistant high strength PVC insulated electrical casing, characterized in that: The invention comprises the following raw materials in parts by weight: 90 to 110 parts of PVC resin; 2.5 to 4.5 parts of calcium zinc stabilizer; 0.2 to 0.8 parts of internal lubricant; 0.4 to 1.5 parts of external lubricant; 0.2 to 0.5 parts of release agent; 0.5 to 2.0 parts of processing aid; 30 to 40 parts of inorganic modified filler; 4 to 10 parts of toughening agent; and 0.8 to 2.0 parts of titanium dioxide.

2. The low temperature resistant high strength PVC insulated electrical casing according to claim 1, characterized in that: The PVC resin is SG-5 type resin; The viscosity of the PVC resin is 107-118.

3. The low temperature resistant and high strength PVC insulated electrical conduit according to claim 1, characterized in that: The internal lubricant is any one or more of aliphatic dicarboxylic acid esters, long-chain fatty acid esters, fatty acid metal soaps and polyol fatty acid amides mixed in any proportion; The external lubricant is any one or more of polyethylene wax, Fischer-Tropsch wax and paraffin wax mixed in any proportion.

4. The low temperature resistant and high strength PVC insulated electrical conduit according to claim 1, characterized in that: The release agent is any one or more of high-density oxidized polyethylene wax and ethylene bisstearamide mixed in any proportion.

5. The low temperature resistant and high strength PVC insulated electrical conduit according to claim 1, characterized in that: The processing aid is acrylonitrile / styrene copolymer; The toughening agent is any one or more of nitrile rubber, MBS resin, and chlorinated polyethylene mixed in any proportion; The titanium dioxide is rutile titanium dioxide.

6. The low temperature resistant and high strength PVC insulated electrical conduit according to claim 1, characterized in that: The inorganic modified filler is prepared by treating the inorganic filler with a surface treatment agent; The inorganic filler is prepared by mixing a stone powder raw material and a calcium carbonate raw material; The stone powder raw material is talcum powder or wollastonite powder; The calcium carbonate raw material is any one or more of heavy calcium carbonate and light calcium carbonate mixed in any proportion; The surface treatment agent is a mixture of stearic acid and a silane coupling agent.

7. The low temperature resistant high strength PVC insulated electrical casing according to claim 6, characterized in that: The preparation method of the inorganic modified filler comprises the following steps: putting stone powder raw material and calcium carbonate raw material into a high-speed mixer to obtain inorganic filler, adding a surface treatment agent into the inorganic filler when the temperature rises to 80-85°C, continuing to heat to 110-115°C, mixing for 20 minutes, stopping high-speed mixing, cooling the discharged material, and obtaining the inorganic modified filler.

8. The low temperature resistant high strength PVC insulated electrical casing according to claim 7, characterized in that: The mass ratio of the inorganic filler to the surface treatment agent is 100:(2-3).

9. A method for preparing the low temperature resistant high strength PVC insulated electrical casing according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: S1: Add PVC resin, calcium zinc stabilizer, internal lubricant, processing aid, toughening agent and titanium dioxide into a high-speed mixer, mix and stir, fully mix and evenly prepare a mixed material, heat it to 80-85° C., add external lubricant, release agent and inorganic modified filler into the mixed material, continue to mix and prepare a premix, continue to heat it to 120-130° C., send the premix into a cooling mixer and stir at a low speed, cool it to 45-55° C. and discharge it to prepare a cold mix; S2: The cold mixed material is screened through a vibrating screen to remove lumps, and then transported to a storage tank for standing and maturing for 2 to 4 hours to obtain a mixed material; S3: The mixed materials are conveyed to a twin-screw extruder for plasticization and extrusion. The extruded billet is first shaped by a sizing sleeve on the billet outlet die, then enters a vacuum box, and then enters a water tank for cooling and shaping. Finally, it is printed, measured and cut to obtain a low-temperature resistant and high-strength PVC insulated electrical conduit.

10. The method for preparing a low temperature resistant high strength PVC insulated electrical casing according to claim 9, characterized in that: In step S3, during the process of conveying the mixed materials to the twin-screw extruder for plasticization and extrusion, the barrel processing temperature of the twin-screw extruder is 170-190° C., the mold temperature is 190-210° C., and the main screw speed is 60-75 r / min.

Images