Flame-retardant insulating PVC electrical conduit and preparation method thereof

Abstract

The invention discloses a flame-retardant insulating PVC electrical conduit and a preparation method thereof. The PVC electrical conduit is prepared from PVC resin, a phenolic resin coated red phosphorus flame retardant, brominated polystyrene, a compatilizer, a stabilizer, an antioxidant, a lubricant and a pigment according to a certain ratio. The preparation method of the PVC electrical conduit comprises the following steps: S1, uniformly mixing the PVC resin, the phenolic resin coated red phosphorus flame retardant, the brominated polystyrene, the compatilizer, the stabilizer, the antioxidant, the lubricant and the pigment to obtain a mixed material; and S2, adding the mixed material into a double-screw extruder, carrying out extrusion molding, and carrying out cooling shaping, so as to obtain the flame-retardant and insulating PVC electrical conduit. The PVC electrical conduit is reasonable in formula design, so that the prepared PVC electrical conduit has good insulating property and flame retardant property, and other properties (such as mechanical properties) meet the national standard requirements.

Description

Technical Field

[0001] The invention relates to the technical field of power cable bushings, and in particular to a flame-retardant insulating PVC electrical bushing and a preparation method thereof. Background Art

[0002] Electrical conduit is a hard pipe used for laying power lines. The power lines are inserted into the electrical conduit, and then the electrical conduit is laid at a specific location in the building. The electrical conduit plays a role in fixing and insulating. The electrical conduit is generally made of polyvinyl chloride (PVC), which can achieve the effect of being light, hard, and having good insulation properties.

[0003] In daily life, wires and cables often generate high temperatures due to short circuits or overloads. If there are no fire prevention measures around them, fires may occur. Flame-retardant electrical conduits can slow down the burning speed of wires at high temperatures to a certain extent, thus effectively avoiding fire accidents.

[0004] During the production process of PVC electrical conduits, appropriate flame retardants are added. These flame retardants can effectively prevent the spread of fire, reduce the burning speed, and even extinguish the flame when a fire occurs. There are many types of flame retardants. Flame retardants can be divided into halogen flame retardants, phosphorus flame retardants, and metal oxide flame retardants such as aluminum, antimony, boron, and molybdenum according to the main elements that play a flame retardant role; they can also be divided into bromine, phosphorus, chlorine, and aluminum-based, boron-based, antimony-based flame retardants, etc.

[0005] At present, brominated flame retardants are the most important and effective type of halogen flame retardants. Brominated flame retardants have good flame retardant effects, but they also have serious disadvantages, namely, they reduce the anti-ultraviolet light stability of the flame-retarded materials and generate more smoke, corrosive gases and toxic gases during combustion. Therefore, it is necessary to reduce the use of brominated flame retardants and develop a new PVC electrical conduit with good flame retardant and insulation effects. Summary of the invention

[0006] Based on the above-mentioned prior art, the present invention provides a flame-retardant and insulating PVC electrical conduit and a preparation method thereof. The formula design of the PVC electrical conduit is reasonable, so that the prepared PVC electrical conduit has good insulation and flame retardant properties, while other properties (such as mechanical properties) meet the national standard requirements.

[0007] The technical solution adopted to achieve the above-mentioned purpose of the present invention is:

[0008] A flame-retardant insulating PVC electrical conduit is prepared from the following raw materials in parts by weight:

[0009] PVC resin 100 parts

[0010]

[0011] Further, the preparation method of the phenolic resin coated red phosphorus flame retardant is as follows:

[0012] S1. Mix red phosphorus powder, phenol and formaldehyde solution evenly, and then heat in a 70-90°C water bath for 5-15 minutes to obtain a prepolymer;

[0013] S2. The prepolymer is shaken, concentrated ammonia water is added, and heating is continued in a 70-90° C. water bath for 2-4 hours. After the reaction is completed, the obtained mixed product is filtered, and the filter cake is dried to obtain the phenolic resin-coated red phosphorus flame retardant.

[0014] Furthermore, the mass percentage concentration of the formaldehyde solution is 35-40%, and the mass percentage concentration of the concentrated ammonia water is 25%-30%.

[0015] Furthermore, the mass ratio of the phenol, red phosphorus powder and formaldehyde is 1:1:1.2-1.5.

[0016] Furthermore, the compatibilizer is a maleic anhydride grafted product, and the compatibilizer is one of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene.

[0017] Furthermore, the stabilizer is one of a calcium-zinc composite stabilizer and an organic tin stabilizer.

[0018] Furthermore, the antioxidant is at least one of antioxidant 1010, antioxidant 168 and antioxidant 1076.

[0019] Furthermore, the lubricant is at least one of oxidized polyethylene wax, lead stearate, glyceryl monostearate and stearyl alcohol.

[0020] Furthermore, the pigment is at least one of titanium dioxide, permanent green, fast red BBN and carbon black.

[0021] A method for preparing a flame-retardant insulating PVC electrical conduit comprises the following steps:

[0022] S1, mixing PVC resin, phenolic resin coated red phosphorus flame retardant, brominated polystyrene, compatibilizer, stabilizer, antioxidant, lubricant and pigment to obtain a mixed material;

[0023] S2, adding the mixed material into a twin-screw extruder, extruding and shaping, cooling and shaping, and obtaining the flame-retardant insulating PVC electrical conduit.

[0024] Furthermore, the processing temperature of the twin-screw extruder barrel is 160-210°C, wherein the temperature of zone 1 is 185-195°C, the temperature of zone 2 is 185-195°C, the temperature of zone 3 is 175-185°C, the temperature of zone 4 is 170-180°C, and the temperature of zone 5 is 170-180°C.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0026] 1. The present invention adopts phenolic resin coated red phosphorus flame retardant and brominated polystyrene to synergistically flame retard PVC resin, which significantly improves the flame retardant performance of the electrical conduit on the one hand, and reduces the usage of brominated polystyrene on the other hand, and reduces the smoke and toxic gas generated when brominated polystyrene is burned as much as possible.

[0027] 2. The present invention adopts phenolic resin coated red phosphorus as a flame retardant. The phenolic resin coated red phosphorus has good insulation properties and can further improve the insulation properties of the electrical bushing. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to specific embodiments, but these embodiments are not to be interpreted as limiting the protection scope of the present invention in any sense.

[0029] The preparation method of the phenolic resin coated red phosphorus flame retardant used in the following examples and comparative examples is as follows:

[0030] S1. In a reaction bottle, add 20 g of red phosphorus powder, phenol and 30 mL of 40 wt% formaldehyde solution and mix well, then place in a water bath at 80°C and heat for 10 min to obtain a prepolymer;

[0031] S2. The prepolymer is shaken, 5 mL of 25 wt% concentrated aqueous ammonia is added, and the mixture is heated in a water bath at 80° C. for 3 h. After the reaction is completed, the obtained mixed product is filtered, and the filter cake is washed with water, and then the filter cake is dried at 100° C. for 6 h to obtain the phenolic resin-coated red phosphorus flame retardant.

[0032] Example 1

[0033] A flame-retardant insulating PVC electrical conduit is prepared from the following raw materials in parts by weight:

[0034]

[0035]

[0036] The preparation method of the flame retardant insulating PVC electrical conduit is as follows:

[0037] 1. Add PVC resin, phenolic resin coated red phosphorus flame retardant, brominated polystyrene, maleic anhydride-bonded polyethylene, calcium zinc composite stabilizer, oxidized polyethylene wax, lead stearate, antioxidant 1010, antioxidant 168 and titanium dioxide into a high mixing pot, mix well, cool and obtain a mixed material.

[0038] 2. The mixed material is conveyed to a twin-screw extruder, and the temperature of the barrel zone 1 is set to 190°C, the temperature of the zone 2 is set to 190°C, the temperature of the zone 3 is set to 180°C, the temperature of the zone 4 is set to 175°C, and the temperature of the zone 5 is set to 175°C. Extrusion molding is performed, and cooling is performed to obtain the flame-retardant insulating PVC electrical conduit.

[0039] Example 2

[0040] A flame-retardant insulating PVC electrical conduit is prepared from the following raw materials in parts by weight:

[0041]

[0042] The preparation method of the flame-retardant insulating PVC electrical conduit of this embodiment is the same as that of Embodiment 1.

[0043] Example 3

[0044] A flame-retardant insulating PVC electrical conduit is prepared from the following raw materials in parts by weight:

[0045]

[0046]

[0047] The preparation method of the flame-retardant insulating PVC electrical conduit of this embodiment is the same as that of Embodiment 1.

[0048] Comparative Example 1

[0049] A PVC electrical conduit is prepared from the following raw materials in parts by weight:

[0050]

[0051] The preparation method of the PVC electrical conduit in this comparative example is the same as that in Example 1.

[0052] Comparative Example 2

[0053] A PVC electrical conduit is prepared from the following raw materials in parts by weight:

[0054]

[0055]

[0056] The preparation method of the PVC electrical conduit in this comparative example is the same as that in Example 1.

[0057] Comparative Example 3

[0058] A PVC electrical conduit, characterized in that it is prepared from the following raw materials in parts by weight:

[0059]

[0060] The preparation method of the PVC electrical conduit in this comparative example is the same as that in Example 1.

[0061] The flame retardant properties and insulation properties of the PVC electrical conduits prepared in Examples 1-3 and Comparative Examples 1-3 were tested. The flame retardant properties test was based on GB / T 8624-2012 "Classification of Combustion Performance of Building Materials and Products": 1. Self-extinguishing time, in accordance with "GB / T 43815-2024 Building Rigid Polyvinyl Chloride (PVC-U) Insulated Electrical Conduits and Accessories"; 2. Oxygen index, in accordance with GB / T2406.2-2009; 3. Smoke density, in accordance with GB / T 8627-2007. The test results are shown in the following table:

[0062]

[0063]

[0064] It can be seen from the above table that when phenolic resin-coated red phosphorus flame retardant and brominated polystyrene are used to modify the flame retardancy of PVC electrical conduits, the two produce a synergistic effect, the flame retardancy of the PVC electrical conduits is greatly improved, and the insulation performance is also improved to a certain extent.

Claims

1. A flame retardant insulating PVC electrical conduit, characterized in that It is prepared from the following raw materials in parts by weight:

2. The flame-retardant insulating PVC electrical conduit according to claim 1, characterized in that: The preparation method of the phenolic resin coated red phosphorus flame retardant is as follows: S1. Mix red phosphorus powder, phenol and formaldehyde solution evenly, and then heat in a 70-90°C water bath for 5-15 minutes to obtain a prepolymer; S2. The prepolymer is shaken, concentrated ammonia water is added, and heating is continued in a 70-90° C. water bath for 2-4 hours. After the reaction is completed, the obtained mixed product is filtered, and the filter cake is dried to obtain the phenolic resin-coated red phosphorus flame retardant.

3. The flame-retardant insulating PVC electrical conduit according to claim 2, characterized in that: The mass percentage concentration of the formaldehyde solution is 35-40%, and the mass percentage concentration of the concentrated ammonia water is 25%-30%.

4. The flame-retardant insulating PVC electrical conduit according to claim 2, characterized in that: The mass ratio of the phenol, red phosphorus powder and formaldehyde is 1:1:1.2-1.

5.

5. The flame-retardant insulating PVC electrical conduit according to claim 1, characterized in that: The compatibilizer is a maleic anhydride grafted product, and the compatibilizer is one of maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene.

6. The flame-retardant insulating PVC electrical conduit according to claim 1, characterized in that: The stabilizer is one of a calcium-zinc composite stabilizer and an organic tin stabilizer.

7. The flame-retardant insulating PVC electrical conduit according to claim 1, characterized in that: The antioxidant is at least one of antioxidant 1010, antioxidant 168 and antioxidant 1076.

8. The flame-retardant insulating PVC electrical conduit according to claim 1, characterized in that: The lubricant is at least one of oxidized polyethylene wax, lead stearate, glyceryl monostearate and stearyl alcohol.

9. The flame-retardant insulating PVC electrical conduit according to claim 1, characterized in that: The pigment is at least one of titanium dioxide, permanent green, fast red BBN and carbon black.

10. A method for preparing the flame-retardant insulating PVC electrical conduit according to any one of claims 1 to 9, characterized in that The steps include: S1, mixing PVC resin, phenolic resin coated red phosphorus flame retardant, brominated polystyrene, compatibilizer, stabilizer, antioxidant, lubricant and pigment to obtain a mixed material; S2, adding the mixed material into a twin-screw extruder, extruding and shaping, cooling and shaping, and obtaining the flame-retardant insulating PVC electrical conduit.

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