High-pressure-resistant PVC electrician sleeve and preparation method thereof

Abstract

The application belongs to the technical field of PVC pipes and specifically relates to a high-pressure-resistant PVC electric sleeve and a preparation method thereof, which comprises the following components by weight: 100 parts of PVC resin, 5-10 parts of PVC latex particles, 3.5-5 parts of calcium-zinc stabilizer, 3-10 parts of calcium carbonate, 0.5-5 parts of mica powder, 5-7 parts of chlorinated polyethylene, 0-1 part of PVC processing aid, 0.6-1.2 parts of lubricant and 1-2 parts of titanium white powder. The high-pressure-resistant PVC electric sleeve prepared by the application can not only maintain good pressure resistance for a long time, but also can remain undeformed in a high-temperature construction environment.

Description

Technical Field

[0001] This invention belongs to the field of PVC pipe technology, specifically relating to a high-pressure PVC electrical conduit and its preparation method. Background Technology

[0002] PVC electrical conduits are typically concealed within concrete and subjected to pressure. This places certain requirements on the pressure resistance of the PVC electrical conduits. If the pressure resistance of the PVC electrical conduits is insufficient, the conduits may deform or crack during construction, leading to difficulties in wire pulling, wire wear, or the inability to replace the wires later. Therefore, PVC electrical conduits need to meet high pressure resistance requirements.

[0003] In addition, the mechanical properties of PVC materials are greatly affected by temperature. In the high temperatures of summer, the compressive strength of PVC electrical conduits will decrease, and the conduits will be more prone to deformation. Therefore, it is even more necessary to improve the compressive strength of PVC electrical conduits to avoid deformation under high temperature and pressure.

[0004] Therefore, this invention is proposed. Summary of the Invention

[0005] To address the aforementioned deficiencies in the existing technology, this invention provides a high-pressure PVC electrical conduit that is simple to prepare, easy to master, low in cost, and easy to mass-produce.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A high-pressure resistant PVC electrical conduit comprises the following components in parts by weight: 100 parts PVC resin, 5-10 parts PVC latex particles, 3.5-5 parts calcium-zinc stabilizer, 3-10 parts calcium carbonate, 0.5-5 parts mica powder, 5-7 parts chlorinated polyethylene, 0-1 parts PVC processing aid, 0.6-1.2 parts lubricant, and 1-2 parts titanium dioxide.

[0008] The PVC resin has a particle size of 75-250 μm.

[0009] The PVC latex particles have a particle size of 0.1-0.4 μm.

[0010] The calcium carbonate is precipitated calcium carbonate, with a settling volume of 2.4-2.8 ml / g and an average particle size of 0.1-1 μm.

[0011] The mica powder is muscovite powder, and the particle size of the muscovite powder is 40-60μm.

[0012] The mica powder is in the form of thin flakes.

[0013] The PVC processing aid is an acrylate copolymer.

[0014] The lubricant is two or three of the following: oxidized polyethylene wax, polyethylene wax, calcium stearate, or monoglyceride.

[0015] A method for preparing a high-pressure resistant PVC electrical conduit includes the following steps:

[0016] (1) Mixing of materials: Weigh out PVC resin, PVC latex particles, calcium zinc stabilizer, calcium carbonate, mica powder, chlorinated polyethylene, PVC processing aid, lubricant and titanium dioxide according to the proportion and add them to the high-speed mixer. Mix at high speed until the temperature reaches the first temperature range, then cold mix until the temperature reaches the second temperature range, and then discharge.

[0017] (2) Extruded by a twin-screw extruder. During extrusion, the temperature of zone 1 is 170-180℃, zone 2 is 190-200℃, zone 3 is 180-190℃, zone 4 is 180-190℃, zone 5 is 175-185℃, and the die head temperature is 200-210℃.

[0018] The first temperature range is 110-120℃, and the second temperature range is 45-55℃.

[0019] The beneficial effects of this invention are as follows:

[0020] (1) This application combines calcium carbonate and mica powder, and uses large layers of mica powder to form the main reinforcing skeleton of PVC material, while calcium carbonate fills the gaps in the skeleton as a secondary reinforcing filler. The two work together to improve the compressive strength of PVC electrical conduit.

[0021] (2) PVC latex particles are used to improve the problems of poor plasticization and poor toughness of PVC caused by large layers of mica powder. In order to avoid the barrier effect of large layers of mica powder on the mutual melting of PVC particles and reduce the toughness and bending performance of the sleeve, this application uses PVC latex particles. The particles are small in size and have no coating structure on the surface, so they can be quickly plasticized and melted and entangled during the processing.

[0022] (3) The high-pressure PVC electrical conduit prepared in this application can not only maintain good pressure resistance for a long time, but also remain unchanged in high-temperature construction environment. Detailed Implementation

[0023] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0024] Example 1

[0025] This embodiment of a high-pressure PVC electrical conduit comprises the following components in parts by weight: 100 parts PVC resin, 5 parts PVC latex particles, 3.5 parts calcium-zinc stabilizer, 3 parts calcium carbonate, 0.5 parts mica powder, 5.3 parts chlorinated polyethylene, 0.5 parts PVC processing aid, 0.9 parts lubricant, and 1 part titanium dioxide.

[0026] The lubricant used is a mixture of oxidized polyethylene wax, polyethylene wax and monoglyceride.

[0027] The preparation method includes the following steps:

[0028] (1) Mixing of materials: Weigh PVC resin, PVC latex particles, calcium zinc stabilizer, calcium carbonate, mica powder, chlorinated polyethylene, PVC processing aid, lubricant and titanium dioxide according to the proportion and add them to the high-speed mixer. Mix at high speed until the temperature reaches 110°C, then cold mix until the temperature reaches 50°C and discharge.

[0029] (2) Extruded by a twin-screw extruder. During extrusion, the temperature of zone 1 is 170℃, zone 2 is 195℃, zone 3 is 185℃, zone 4 is 180℃, zone 5 is 180℃, and the die head temperature is 200℃.

[0030] Example 2

[0031] This embodiment of a high-pressure PVC electrical conduit includes the following components in parts by weight: 100 parts PVC resin, 5 parts PVC latex particles, 3.8 parts calcium-zinc stabilizer, 5 parts calcium carbonate, 1 part mica powder, 5.8 parts chlorinated polyethylene, 0.5 parts PVC processing aid, 1 part lubricant, and 1 part titanium dioxide.

[0032] The lubricant used is a mixture of oxidized polyethylene wax, polyethylene wax and monoglyceride.

[0033] The preparation method includes the following steps:

[0034] (1) Mixing of materials: Weigh PVC resin, PVC latex particles, calcium zinc stabilizer, calcium carbonate, mica powder, chlorinated polyethylene, PVC processing aid, lubricant and titanium dioxide according to the proportion and add them to the high-speed mixer. Mix at high speed until the temperature reaches 115℃, then cold mix until the temperature reaches 50℃ and discharge.

[0035] (2) The extrusion molding is performed by a twin-screw extruder. During extrusion, the temperature of zone 1 is 170℃, the temperature of zone 2 is 195℃, the temperature of zone 3 is 185℃, the temperature of zone 4 is 180℃, the temperature of zone 5 is 180℃, and the temperature of the die head is 205℃.

[0036] Example 3

[0037] This embodiment of a high-pressure PVC electrical conduit includes the following components in parts by weight: 100 parts PVC resin, 5 parts PVC latex particles, 3.8 parts calcium-zinc stabilizer, 10 parts calcium carbonate, 1 part mica powder, 5.8 parts chlorinated polyethylene, 0.5 parts PVC processing aid, 1 part lubricant, and 1 part titanium dioxide.

[0038] The lubricant used is a mixture of oxidized polyethylene wax, polyethylene wax and monoglyceride.

[0039] The preparation method includes the following steps:

[0040] (1) Mixing of materials: Weigh PVC resin, PVC latex particles, calcium zinc stabilizer, calcium carbonate, mica powder, chlorinated polyethylene, PVC processing aid, lubricant and titanium dioxide according to the proportion and add them to the high-speed mixer. Mix at high speed until the temperature reaches 115℃, then cold mix until the temperature reaches 50℃ and discharge.

[0041] (2) Extruded by a twin-screw extruder. During extrusion, the temperature of zone 1 is 170℃, zone 2 is 195℃, zone 3 is 185℃, zone 4 is 180℃, zone 5 is 180℃, and the die head temperature is 210℃.

[0042] Comparative Example 1

[0043] This comparative example provides a common PVC electrical conduit, the formulation of which includes the following components in parts by weight: 100 parts PVC resin, 4 parts calcium-zinc stabilizer, 15 parts precipitated calcium carbonate, 5.8 parts chlorinated polyethylene wax, 0.2 parts PVC processing aid, 0.8 parts polyethylene wax, 0.1 parts oxidized polyethylene wax, and 1 part titanium dioxide.

[0044] Its preparation methods include material mixing and pipe extrusion molding.

[0045] Comparative Example 2

[0046] This comparative example provides a high-pressure PVC electrical conduit, whose formula is identical to that of Example 2 except that no PVC emulsion particles are added.

[0047] The PVC electrical conduit obtained in the examples and comparative examples was subjected to relevant tests, and the test results are shown in Table 1.

[0048] Table 1. Performance test results of PVC electrical conduits prepared in the examples and comparative examples.

[0049] Testing items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Tensile yield strength (MPa), tested at 23℃ 45.9 47.5 46.1 40.6 45.4 Tensile yield strength (MPa), tested at 30℃ 41.5 43.6 42.2 35.2 / Elongation at break (%), tested at 23℃ 182 201 195 190 96 Elongation at break (%), tested at 30℃ 180 196 194 183 / Df (750 N, %) under load for 1 minute, test temperature 23℃ 13.22 11.16 12.02 19.03 11.87 The Df(750N,%) test temperature was 23℃ after loading for 1 minute and unloading for 1 minute. 2.68 1.72 2.22 5.24 2.12 Df (750 N, %) under load for 2 minutes, test temperature 23℃ 13.74 11.67 12.50 20.69 / Df (750 N, %) under load for 3 minutes, test temperature 23℃ 14.10 12.02 12.95 21.75 / Df (750 N, %) under load for 4 minutes, test temperature 23℃ 14.29 12.22 13.18 22.66 / Df (750 N, %) under load for 5 minutes, test temperature 23℃ 14.51 12.46 13.39 23.41 / Df (750 N, %) under load for 6 minutes, test temperature 23℃ 14.76 12.68 13.62 24.02 / Df (750 N, %) under load for 7 minutes, test temperature 23℃ 14.98 12.93 13.84 24.52 / Df (750 N, %) under load for 8 minutes, test temperature 23℃ 15.21 13.08 13.99 24.97 / Df (750 N, %) under load for 9 minutes, at a test temperature of 23℃ 15.43 13.23 14.17 25.38 / Df (750 N, %) under load for 10 min, test temperature 23℃ 15.57 13.30 14.32 25.73 / After being loaded for 10 minutes, the Df(750N,%) test temperature was 23℃ after unloading for 1 minute. 5.64 3.94 5.08 11.08 / Df (750 N, %) under load for 30 min, test temperature 23℃ 18.42 15.25 16.48 / / After being loaded for 30 minutes, the Df(750N,%) test temperature was 23℃ after unloading for 1 minute. 5.91 5.35 5.81 / / Df (750 N, %) under load for 1 minute, test temperature 30℃ 15.85 13.59 14.83 22.62 / The Df(750N,%) test temperature was 30℃ after loading for 1 minute and unloading for 1 minute. 4.74 2.53 4.09 7.24 / Bending performance Unbreakable Unbreakable Unbreakable Unbreakable 2 broken

[0050] It should be noted that the following standards are adopted for the testing procedures related to PVC electrical conduit:

[0051] (a) Tensile strength test: GB / T 1040.2-2006 Determination of tensile properties of plastics - Part II;

[0052] (ii) Elongation at break test: GB / T 1040.2-2006 Determination of tensile properties of plastics, Part II;

[0053] (III) Df (750N) test under load for 1-10 min at an ambient temperature of 23℃: The test method refers to JG / T3050-1998 "Insulating Electrical Conduit and Fittings for Buildings";

[0054] (iv) Df (750N) at 23℃ ambient temperature for 1 min after unloading: The test method refers to JG / T 3050-1998 "Insulating Electrical Conduit and Fittings for Buildings";

[0055] (v) Df (750N) test at 30℃ ambient temperature with minimum load: The test method is as follows: JG / T3050-1998 "Insulating Electrical Conduit and Fittings for Buildings";

[0056] (vi) Df (750N) at 30℃ ambient temperature for 1 minute after unloading: The test method refers to JG / T 3050-1998 "Insulating Electrical Conduit and Fittings for Buildings";

[0057] (vii) Bending performance test: JG / T 3050-1998 "Insulating electrical conduits and fittings for building".

[0058] Calcium carbonate is an essential inorganic filler in the processing of PVC pipes. It can not only greatly reduce the production cost of PVC, but also improve the strength and toughness of PVC, as well as its processing fluidity and heat resistance to a certain extent. However, the use of calcium carbonate filler alone cannot meet the high compressive strength requirements of PVC electrical conduit.

[0059] Specifically, precipitated calcium carbonate has high hardness and low price. Using precipitated calcium carbonate as a filler reduces the cost of PVC electrical conduits while improving the hardness, rigidity, and dimensional stability of PVC products, and enhancing their processing performance. The small particle size and micropores of precipitated calcium carbonate can, to some extent, restrict the movement of PVC molecular chains and increase the Vicat softening temperature. However, calcium carbonate also presents dispersion difficulties, leading to a decrease in the mechanical properties of PVC. Furthermore, calcium carbonate increases the spacing between PVC molecular chains, weakening the intermolecular forces and reducing PVC strength. Therefore, the reinforcing effect of calcium carbonate on PVC materials is relatively limited.

[0060] Mica powder is a rigid two-dimensional filler that provides planar reinforcement in plastics, significantly improving their flexural modulus and tensile strength. Furthermore, it imparts excellent dimensional stability and heat resistance. Specifically, mica powder has a highly elastic, flexible, sheet-like structure. When this two-dimensional, large-sheet filler is added to PVC, it aligns and orients along the extrusion flow direction (the axial direction of electrical conduits) during PVC melt flow, forming a planar oriented structure that greatly improves the compressive strength of PVC electrical conduits. However, due to the large size of the mica powder sheet structure, PVC particles perpendicular to the flow direction are difficult to fuse together. Therefore, appropriate addition and use of mica powder are necessary.

[0061] This application utilizes a synergistic combination of calcium carbonate and mica powder as fillers to improve the compressive strength of PVC electrical conduits. However, the large size of mica powder flakes (40-60 μm) significantly affects the fusion between PVC particles when added to PVC, leading to high brittleness of the conduit. To avoid the barrier effect of large mica powder flakes on the mutual melting of PVC particles, which reduces the toughness and bending performance of the conduit, this invention also employs PVC latex particles. These are primary PVC particles (small particle size, no external coating structure), which can be plasticized and bonded together very quickly during processing, effectively improving the plasticity of PVC and maintaining the toughness of the PVC electrical conduit.

[0062] As can be seen from Examples 1-3 in Table 1, the addition of calcium carbonate and mica powder does indeed result in good tensile strength and compressive strength of the casing. Furthermore, Examples 2 and Comparative Example 2 show that the addition of PVC latex particles largely determines the toughness of the PVC. Without the addition of PVC latex particles, the elongation at break of the PVC decreases sharply, and the bending performance of the casing is also affected. It can be said that the addition of PVC latex particles solves the problem of large-scale mica powder blocking the fusion of PVC particles, thus ensuring the toughness and bending performance of the PVC casing.

[0063] Compared to ordinary PVC electrical conduit (Comparative Example 1), the high-compression-resistant PVC electrical conduit exhibits significant advantages. Taking Example 2 as an example, its Df (degrees of freedom) after 1 minute of load is 11.16%, and even after 30 minutes of continuous load, its Df (15.25%) is still much smaller than that of Comparative Example 1 after 1 minute of load (19.03%). This means that the high-compression-resistant PVC electrical conduit prepared in this application can maintain good compressive strength for a long time (the Df of the Comparative Example exceeds 25% after 10 minutes of load, exceeding the standard range, and the conduit fails). Moreover, at a test temperature of 30°C, the Df of Example 2 after 1 minute of load is only 13.59%, which is much lower than that of Comparative Example 1 (22.62%), further demonstrating that the electrical conduit of this invention has high compressive strength in high-temperature environments.

[0064] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A high-pressure resistant PVC electrical conduit, characterized in that: The product comprises the following components in parts by weight: 100 parts PVC resin, 5-10 parts PVC latex particles, 3.5-5 parts calcium-zinc stabilizer, 3-10 parts calcium carbonate, 0.5-5 parts mica powder, 5-7 parts chlorinated polyethylene, 0-1 parts PVC processing aid, 0.6-1.2 parts lubricant, and 1-2 parts titanium dioxide; wherein the PVC latex particles have a particle size of 0.1-0.4 μm. The mica powder is muscovite powder, and the particle size of the muscovite powder is 40-60μm; the shape of the mica powder is flake-like.

2. The high-pressure resistant PVC electrical conduit as described in claim 1, characterized in that: The PVC resin has a particle size of 75-250 μm.

3. The high-pressure resistant PVC electrical conduit as described in claim 1, characterized in that: The calcium carbonate is precipitated calcium carbonate, with a settling volume of 2.4-2.8 ml / g and an average particle size of 0.1-1 μm.

4. The high-pressure resistant PVC electrical conduit as described in claim 1, characterized in that: The PVC processing aid is an acrylate copolymer.

5. The high-pressure resistant PVC electrical conduit as described in claim 1, characterized in that: The lubricant is two or three of the following: oxidized polyethylene wax, polyethylene wax, calcium stearate, or monoglyceride.

6. A method for preparing a high-compression-resistant PVC electrical conduit as described in claim 1, characterized in that, Includes the following steps: (1) Mixing of materials: Weigh out PVC resin, PVC latex particles, calcium zinc stabilizer, calcium carbonate, mica powder, chlorinated polyethylene, PVC processing aid, lubricant and titanium dioxide according to the proportion and add them to the high-speed mixer. Mix at high speed until the temperature reaches the first temperature range, then cold mix until the temperature reaches the second temperature range, and then discharge. (2) Extruded by a twin-screw extruder. During extrusion, the temperature of zone 1 is 170-180℃, zone 2 is 190-200℃, zone 3 is 180-190℃, zone 4 is 180-190℃, zone 5 is 175-185℃, and the die head temperature is 200-210℃.

7. The method for preparing a high-pressure PVC electrical conduit as described in claim 6, characterized in that: The first temperature range is 110-120℃, and the second temperature range is 45-55℃.