PVC electrical bushing and preparation method and application thereof

Abstract

The application belongs to the technical field of electrician sleeves, and discloses a PVC electrician sleeve and a preparation method and application thereof, the PVC electrician sleeve comprises the following raw materials in parts by weight: 100 parts of PVC resin, 6-10 parts of toughening agent, 15-25 parts of flame retardant, 1-3 parts of heat stabilizer, 0.5-1.5 parts of lubricant and 0.1-0.8 parts of antioxidant; wherein the toughening agent comprises a core, a first shell layer formed on the surface of the core and a second shell layer formed on the surface of the first shell layer, and the core is a conjugated diene-(meth)acrylate copolymer; the flame retardant comprises an organic silicon flame retardant and bisphenol A bis(diphenyl phosphate). The PVC electrician sleeve of the application realizes the balance of high toughness, high transparency and flame retardant performance through the synergistic effect of PVC resin, a specific toughening agent system and a specific flame retardant system, and solves the contradiction between the toughness improvement and the transparency reduction of the traditional product.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrical sleeves, in particular to a PVC electrical sleeve and a preparation method and application thereof. BACKGROUND

[0002] The electrical sleeve is a key component for protecting electric wires and cables in the field of building electricity, and its core requirement is to have transparent visibility, insulation protection and reliable mechanical properties. The transparent property can facilitate the observation of internal wire arrangement during the threading process, avoiding misplacement or obstruction. The insulation and mechanical properties can ensure that the sleeve can resist external extrusion and impact during installation and long-term use, preventing damage and exposing the wires.

[0003] Currently, PVC resin material has become the mainstream substrate for preparing electrical sleeves due to its excellent insulation performance and low raw material cost. However, PVC resin as a substrate has high brittleness and insufficient impact resistance, which needs to be improved by adding a toughening agent. In existing toughening technology for PVC electrical sleeves, the compatibility of the toughening agent with the PVC resin matrix is poor, which easily forms micro-aggregated structures in the system, destroys the uniformity of the PVC resin matrix, and significantly reduces the light transmittance of the sleeve, failing to meet the requirements of transparent visibility. Although some toughening agents can improve the toughness of PVC in the short term, they are difficult to disperse stably in the PVC matrix for a long time due to weak interfacial bonding with PVC, resulting in gradual degradation of the impact resistance of the sleeve over time, which cannot continuously guarantee the mechanical reliability.

[0004] In addition, with the expansion of application scenarios of electrical equipment, the demand for flame retardant performance of electrical sleeves is increasingly prominent in order to cope with possible high temperature environments or accidental fires and reduce the risk of fire spreading. However, the application of existing flame retardants in PVC electrical sleeves faces significant adaptation problems: most flame retardants have low transparency, which directly leads to the loss of transparency of the sleeve after addition; a few flame retardants with certain transparency have poor compatibility with the PVC matrix, which easily causes precipitation during processing or damages the PVC molecular chain structure, resulting in significant decline in mechanical indicators such as bending strength and impact resistance of the sleeve, making it difficult to achieve a balance between flame retardant performance and transparency and mechanical performance. SUMMARY

[0005] The present application aims to improve at least one technical problem in the background art.

[0006] The first aspect of the present application provides a PVC electrical sleeve, comprising the following raw materials by weight:

[0007] PVC resin 100 parts, toughening agent 6-10 parts, flame retardant 15-25 parts, heat stabilizer 1-3 parts, lubricant 0.5-1.5 parts, antioxidant 0.1-0.8 parts;

[0008] The toughening agent comprises a core, a first shell layer formed on the surface of the core, and a second shell layer formed on the surface of the first shell layer, the core is a conjugated diene-(meth)acrylate copolymer, the first shell layer is an alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer, and the second shell layer is a (meth)acrylate-acrylamide copolymer.

[0009] The flame retardant comprises an organosilicon flame retardant and bisphenol A bis(diphenyl phosphate).

[0010] The PVC resin as the matrix has excellent insulation and processing adaptability, but the inherent brittleness and the problem of lacking flame retardancy need to be improved by functional additives, and the PVC electrical sleeve of the present application improves the mechanical properties and flame retardant properties of the PVC resin by the specific toughening agent system and the specific flame retardant system.

[0011] In the toughening system, the core is a conjugated diene-(meth)acrylate copolymer, which mainly functions to absorb impact energy through the elastic deformation of the conjugated diene segment, thereby supplementing the toughness of the PVC resin. Due to the low polarity of the conjugated diene segment in the core, there is a significant compatibility difference with the highly polar PVC resin, and without an intermediate transition layer, agglomeration easily occurs due to insufficient interfacial force, resulting in a loss of toughening function. The first shell layer selected for the alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer plays a key role in the interface transition: the polarity of the alkenyl copolymer segment is highly matched with the polarity of the (meth)acrylate unit in the core, and can form a stable interface combination with the core through intermolecular interaction, forming a stable coating structure and effectively inhibiting the agglomeration of the core itself; at the same time, the hydroxyl polar groups contained in the first shell layer can form secondary bonding with the ester groups and amide groups in the second shell layer ((meth)acrylate-acrylamide copolymer) through hydrogen bonding or polar interaction, building a continuous and stable interface bonding system between the "core-first shell layer-second shell layer", providing a structural basis for the effective transmission of toughness. The second shell layer, as the direct contact phase of the toughening agent and the PVC resin, has good compatibility with PVC due to the (meth)acrylate unit, and the amide group of the acrylamide unit can further form a strong hydrogen bond with the PVC molecular chain, significantly improving the interfacial bonding strength of the toughening agent and the PVC resin. Through the transition and synergistic effect of the first shell layer, the toughening agent can be uniformly dispersed in the PVC resin, not only avoiding the destruction of PVC transparency caused by light scattering due to uneven dispersion, but also allowing stress to be efficiently transmitted through the PVC resin-second shell layer-first shell layer path to the core when subjected to external force. The conjugated diene segment of the core absorbs impact energy through deformation, and then reversely transmits the dispersed stress to the second shell layer and the PVC resin, effectively relieving local stress concentration in the PVC resin, thereby solving the inherent brittleness problem. It can be seen that the three-layer structure of the toughening agent (core, first shell layer, and second shell layer) does not function independently, but forms a complete system through interfacial synergy, and the first shell layer in the middle layer is the key transitional link that adapts the function of the core to the PVC resin.

[0012] In the flame retardant system, the organic silicon flame retardant forms an efficient synergy with bisphenol A bis(diphenyl phosphate): the organic silicon flame retardant can be converted into a siloxane protective layer during combustion, covering the surface of the PVC resin to isolate oxygen and heat; bisphenol A bis(diphenyl phosphate) decomposes to produce phosphoric acid substances at high temperatures, promoting the PVC molecular chain to form a dense carbon layer, which cooperates with the siloxane protective layer to block heat and combustible material release, significantly improving the flame retardant effect. More importantly, both of these two flame retardants have good transparency and PVC compatibility, and will not destroy the uniformity of the PVC resin, effectively avoiding the problem of reduced light transmittance caused by traditional flame retardants.

[0013] In addition, the PVC electrical sleeve of the present application further comprises a heat stabilizer, a lubricant and an antioxidant, wherein the heat stabilizer can inhibit the C-Cl bond breaking and molecular chain degradation caused by heat during the processing and use of the PVC resin, so as to ensure the stability of the base structure; the lubricant can improve the processing fluidity of each component, so as to ensure the uniformity of the sleeve forming; and the antioxidant can slow down the aging rate of the PVC resin caused by oxygen molecules during long-term use, so as to avoid the yellowing or toughness attenuation of the PVC resin caused by thermal oxidation aging, and the three together can jointly maintain the long-term comprehensive performance of the PVC electrical sleeve.

[0014] Preferably, the average diameter of the inner core is 100-150 nm, the average thickness of the first shell layer is 20-50 nm, and the average thickness of the second shell layer is 5-20 nm.

[0015] Preferably, the conjugated diene-(meth)acrylate copolymer is obtained by copolymerization of butadiene and methyl methacrylate, and the mass ratio of butadiene to methyl methacrylate is 1: (1.2-1.8).

[0016] Preferably, the alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer is obtained by copolymerization of ethylene-vinyl acetate copolymer and N-hydroxyethyl acrylamide, and the mass ratio of ethylene-vinyl acetate copolymer to N-hydroxyethyl acrylamide is 1: (0.3-0.5), and the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 28%-32%.

[0017] Preferably, the (meth)acrylate-acrylamide copolymer is obtained by copolymerization of methyl methacrylate and N- (hydroxypropyl) acrylamide, and the mass ratio of methyl methacrylate to N- (hydroxypropyl) acrylamide is 1: (0.05-0.15).

[0018] Preferably, the mass ratio of the organosilicon flame retardant to the bisphenol A bis (diphenyl phosphate) is 1: (1.5-2.5).

[0019] Further, the flame retardant further comprises N-hydroxyethyl diethanolamine, and the mass ratio of N-hydroxyethyl diethanolamine in the flame retardant is 5%-8%.

[0020] Preferably, the heat stabilizer is an organotin stabilizer or a metal soap stabilizer.

[0021] Preferably, the lubricant comprises at least one of calcium stearate, glycerol stearate, paraffin and polyethylene wax.

[0022] Preferably, the antioxidant comprises at least one of antioxidant CA, antioxidant 1010, antioxidant 168, antioxidant 245 and antioxidant 1076.

[0023] The second aspect of the present application provides a preparation method of the above-mentioned PVC electrical sleeve, comprising the following steps:

[0024] The PVC resin, the toughening agent, the flame retardant, the heat stabilizer, the lubricant and the antioxidant are mixed to obtain a mixture;

[0025] The mixture is plasticized and molded to obtain the PVC electrical sleeve.

[0026] The third aspect of the present application provides the application of the above-mentioned PVC electrical sleeve in wire and cable threading.

[0027] The PVC electrical sleeve of the present application synchronously realizes the balance of high toughness, high transparency and flame retardant performance through the synergistic effect of the PVC resin, the specific toughening agent system and the specific flame retardant system, and solves the contradiction between the toughness improvement and the transparency reduction of the traditional product. DETAILED DESCRIPTION

[0028] The present application will be further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate but not to limit the scope of the present application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content disclosed in the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0029] Example 1

[0030] A PVC electrical sleeve comprises the following raw materials by weight:

[0031] PVC resin 100 parts, toughening agent 7 parts, flame retardant 18 parts, maleic acid di-n-octyl tin (heat stabilizer) 1.5 parts, calcium stearate (lubricant) 0.8 parts, antioxidant 1010 (antioxidant) 0.3 parts.

[0032] The toughening agent comprises conjugated diene-(meth)acrylate copolymer (inner core), alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer (first shell layer) formed on the surface of the inner core, and (meth)acrylate-acrylamide copolymer (second shell layer) formed on the surface of the first shell layer; the average diameter of the inner core is 110 nm, the average thickness of the first shell layer is 25 nm, and the average thickness of the second shell layer is 8 nm; the conjugated diene-(meth)acrylate copolymer is obtained by copolymerization of butadiene and methyl methacrylate at a mass ratio of 1:1.4; the alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer is obtained by copolymerization of ethylene-vinyl acetate copolymer (the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 29%) and N-hydroxyethyl acrylamide at a mass ratio of 1:0.35; and the (meth)acrylate-acrylamide copolymer is obtained by copolymerization of methyl methacrylate and N-(hydroxypropyl) acrylamide at a mass ratio of 1:0.08.

[0033] A method for preparing a toughening agent, comprising the following steps:

[0034] Into a reaction kettle, 150 parts of deionized water and 1.5 parts of sodium dodecyl sulfate were added, stirred until the sodium dodecyl sulfate was dissolved, and then oxygen was removed by nitrogen for 30 min. Then 50 parts of butadiene, 70 parts of methyl methacrylate, and 0.3 parts of potassium persulfate were added, and the emulsion A was obtained by stirring at 65℃ for 6h.

[0035] Into the emulsion A, a first mixed solution (obtained by mixing 60 parts of ethylene-vinyl acetate copolymer and 21 parts of N-hydroxyethyl acrylamide) was added, and then 0.1 parts of potassium persulfate was added. The emulsion B was obtained by stirring at 70℃ for 4h.

[0036] Into the emulsion B, a second mixed solution (obtained by mixing 80 parts of methyl methacrylate and 6.4 parts of N-(hydroxypropyl) acrylamide) was added, and the stirring was carried out at 75℃ for 3h. Then, 10% sulfuric acid solution was added to adjust the pH to 3.5, and the stirring was carried out for 30 min. The solid was collected by filtration, washed with deionized water until neutral, and dried at 80℃ under vacuum for 4h to obtain the toughening agent.

[0037] The flame retardant includes polydimethylsiloxane (silicone flame retardant) and bisphenol A bis(diphenyl phosphate) in a mass ratio of 1:1.8, and N-hydroxyethyl diethanolamine accounts for 6% in the flame retardant.

[0038] The preparation method of the PVC electrical sleeve, comprising the following steps:

[0039] The PVC resin, the toughening agent, the flame retardant, the maleic acid di-n-octyl tin, the calcium stearate, and the antioxidant 1010 were mixed (mixed at 60℃ for 30 min at 1200r / min in a high-speed mixer) to obtain a mixture.

[0040] The mixture was plasticized (extruded continuously at a screw speed of 50r / min, and the temperatures of the 1-4 zones of the main cylinder of the extruder were 175℃, 185℃, 180℃, and 158℃, respectively), extruded into a mold for molding, and cooled to obtain the PVC electrical sleeve.

[0041] Example 2

[0042] A PVC electrical sleeve, comprising the following raw materials in parts by weight:

[0043] PVC resin 100 parts, toughening agent 8 parts, flame retardant 20 parts, maleic acid di-n-octyl tin (thermal stabilizer) 2 parts, glycerol stearate (lubricant) 1.0 parts, antioxidant 168 (antioxidant) 0.5 parts.

[0044] The toughening agent comprises a conjugated diene-(meth)acrylate copolymer (core), an alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer (first shell layer) formed on the surface of the core, and a (meth)acrylate-acrylamide copolymer (second shell layer) formed on the surface of the first shell layer; the average diameter of the core is 130 nm, the average thickness of the first shell layer is 35 nm, and the average thickness of the second shell layer is 12 nm; the conjugated diene-(meth)acrylate copolymer is obtained by copolymerization of butadiene and methyl methacrylate at a mass ratio of 1:1.6; the alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer is obtained by copolymerization of ethylene-vinyl acetate copolymer (the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 30%) and N-hydroxyethyl acrylamide at a mass ratio of 1:0.4; and the (meth)acrylate-acrylamide copolymer is obtained by copolymerization of methyl methacrylate and N-(hydroxypropyl) acrylamide at a mass ratio of 1:0.1.

[0045] The preparation method of the toughening agent comprises the following steps:

[0046] The reaction kettle is added with 150 parts of deionized water and 1.5 parts of sodium dodecyl sulfate, and after stirring until the sodium dodecyl sulfate is dissolved, nitrogen is introduced to remove oxygen for 30 minutes, then 55 parts of butadiene, 88 parts of methyl methacrylate and 0.35 parts of potassium persulfate are added, and stirring is carried out at 65℃ for 6.5 hours to obtain emulsion A;

[0047] The first mixed solution (the first mixed solution is obtained by mixing 65 parts of ethylene-vinyl acetate copolymer (the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 30%) and 26 parts of N-hydroxyethyl acrylamide) is added to the emulsion A, and then 0.12 parts of potassium persulfate is added, and stirring is carried out at 70℃ for 4.5 hours to obtain emulsion B;

[0048] The second mixed solution (the second mixed solution is obtained by mixing 85 parts of methyl methacrylate and 8.5 parts of N-(hydroxypropyl) acrylamide) is added to the emulsion B, and stirring is carried out at 75℃ for 3.5 hours, then a 10% sulfuric acid solution is added to adjust the pH to 3.5, and stirring is carried out for 30 minutes for coagulation, and the solid is collected by filtration, washed with deionized water until neutral, and vacuum dried at 80℃ for 4 hours to obtain the toughening agent.

[0049] The flame retardant comprises an organic silicon flame retardant (polymethylphenylsiloxane) and bisphenol A bis(diphenyl phosphate) at a mass ratio of 1:2, and N-hydroxyethyl diethanolamine accounts for 7% in the flame retardant.

[0050] The preparation method of the PVC electrical sleeve comprises the following steps:

[0051] The PVC resin, toughening agent, flame retardant, maleic acid di-n-octyl tin, glyceryl stearate and antioxidant 168 are mixed (mixed at 60℃ for 30min at 1200r / min in a high-speed mixer), to obtain a mixture;

[0052] The mixture is plasticized (extruder main machine cylinder 1-4 zone temperature is 176℃, 188℃, 182℃, 160℃ respectively, screw rotation speed is 50r / min, continuous extrusion), extruded into a mold for molding, and the PVC electrical sleeve is obtained after cooling.

[0053] Example 3

[0054] A PVC electrical sleeve, comprising the following raw materials by weight:

[0055] PVC resin 100 parts, toughening agent 9 parts, flame retardant 22 parts, dibutyltin laurate (thermal stabilizer) 2.5 parts, polyethylene wax (lubricant) 1.2 parts, antioxidant 1076 (antioxidant) 0.7 parts.

[0056] The toughening agent comprises a conjugated diene-(meth)acrylate copolymer (inner core), an alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer (first shell layer) formed on the surface of the inner core, and a (meth)acrylate-acrylamide copolymer (second shell layer) formed on the surface of the first shell layer; the average diameter of the inner core is 140nm, the average thickness of the first shell layer is 45nm, and the average thickness of the second shell layer is 18nm; the conjugated diene-(meth)acrylate copolymer is obtained by copolymerization of butadiene and methyl methacrylate at a mass ratio of 1:1.5; the alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer is obtained by copolymerization of ethylene-vinyl acetate copolymer (the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 31%) and N-hydroxyethyl acrylamide at a mass ratio of 1:0.45; and the (meth)acrylate-acrylamide copolymer is obtained by copolymerization of methyl methacrylate and N-(hydroxypropyl) acrylamide at a mass ratio of 1:0.12.

[0057] A method for preparing the toughening agent, comprising the following steps:

[0058] 150 parts of deionized water and 1.5 parts of sodium dodecyl sulfate are added to a reaction kettle, stirred until the sodium dodecyl sulfate is dissolved, then nitrogen is introduced to remove oxygen for 30min, then 60 parts of butadiene, 90 parts of methyl methacrylate and 0.4 parts of potassium persulfate are added, and stirred at 65℃ for 7h to obtain emulsion A;

[0059] A first mixture (the first mixture is obtained by mixing 70 parts of ethylene-vinyl acetate copolymer (the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 31%) and 31.5 parts of N-hydroxyethyl acrylamide) is added to the emulsion A, and then 0.15 parts of potassium persulfate is added, and the reaction is stirred at 70℃ for 5h to obtain emulsion B;

[0060] A second mixture (the second mixture is obtained by mixing 90 parts of methyl methacrylate and 10.8 parts of N-(hydroxypropyl) acrylamide) is added to the emulsion B, and the reaction is stirred at 75℃ for 4h, then a 10% sulfuric acid solution is added to adjust the pH to 3.5, and the stirring coagulation is carried out for 30min, and the solid is collected by filtration, washed with deionized water until neutral, and vacuum dried at 80℃ for 4h to obtain the toughening agent.

[0061] Among them, the flame retardant includes silicone flame retardant (polydimethylsiloxane) and bisphenol A bis(diphenyl phosphate) with a mass ratio of 1:2.2, and N-hydroxyethyl diethanolamine accounts for 7.5% in the flame retardant.

[0062] The preparation method of the PVC electrical sleeve includes the following steps:

[0063] The PVC resin, the toughening agent, the flame retardant, the dibutyltin laurate, the polyethylene wax, and the antioxidant 1076 are mixed (mixed at 60℃ for 30min at 1200r / min in a high-speed mixer) to obtain a mixture;

[0064] The mixture is plasticized (extruded continuously at an extruder main machine cylinder temperature of 177℃, 186℃, 183℃, and 162℃ in zones 1-4, and a screw rotation speed of 50r / min), and then molded into a mold to perform molding, and the PVC electrical sleeve is obtained after cooling.

[0065] Comparative Example 1

[0066] A PVC electrical sleeve, which is different from Example 1 in that the weight parts of the toughening agent is 12 parts. The rest is the same as Example 1.

[0067] Comparative Example 2

[0068] A PVC electrical sleeve, which is different from Example 1 in that the weight parts of the toughening agent is 4 parts. The rest is the same as Example 1.

[0069] Comparative Example 3

[0070] A PVC electrical sleeve, which is different from Example 1 in that the toughening agent only includes the inner core (conjugated diene-(meth)acrylate copolymer) and the second shell layer ((meth)acrylate-acrylamide copolymer), without the first shell layer. The rest is the same as Example 1.

[0071] Comparative Example 4

[0072] A PVC electrical conduit, which differs from Example 1 in that the weight parts of the flame retardant is 35 parts. The rest is the same as Example 1.

[0073] Comparative Example 5

[0074] A PVC electrical conduit, which differs from Example 1 in that the weight parts of the flame retardant is 8 parts. The rest is the same as Example 1.

[0075] Comparative Example 6

[0076] A PVC electrical conduit, which differs from Example 1 in that the flame retardant is decabromodiphenyl ether and bisphenol A bis(diphenyl phosphate) with a mass ratio of 1:2. The rest is the same as Example 1.

[0077] Comparative Example 7

[0078] A PVC electrical conduit, which differs from Example 1 in that the second shell layer in the toughening agent is styrene-acrylonitrile copolymer. The rest is the same as Example 1.

[0079] Effect test experiment

[0080] The products prepared in Example 1 and Comparative Examples 1-7 were subjected to performance tests, and the relevant test methods are as follows:

[0081] Light transmittance test: according to GB / T 2410-2008;

[0082] Tensile strength test: according to ISO 527-1 and ISO 527-2;

[0083] Impact resistance: according to GB / T 1843-2008;

[0084] Flame retardant performance - limiting oxygen index (LOI) test: according to ISO 4589-2;

[0085] The test results are shown in Table 1.

[0086] Table 1 Test results

[0087]

[0088] Referring to the test results of Table 1, compared with Example 1, it can be seen that when the amount of toughening agent is excessive, the compatibility decreases due to exceeding the suitable ratio with the PVC resin, and the excess toughening agent is easy to form micro-agglomeration in the PVC resin, thereby affecting the transparency and toughness performance. Compared with Example 1, it can be seen that when the amount of toughening agent is too small, the inherent brittleness of the PVC resin cannot be fully compensated due to the lack of toughening effective components, and it is difficult to achieve the ideal impact resistance effect and tensile strength. Compared with Example 1, the interface bonding force is greatly weakened due to the lack of the first shell layer in the toughening agent system, and the core of the toughening agent is easy to agglomerate, which not only destroys the transparency, but also affects the toughness transmission path. Compared with Example 1, it can be seen that when the amount of flame retardant is excessive, too many flame-retardant components will occupy the regular arrangement space of the PVC molecular chain, affecting the transparency, and even destroying the intermolecular force, resulting in a decrease in tensile strength and impact strength. Compared with Example 1, it can be seen that when the amount of flame retardant is too small, the flame-retardant effect is greatly weakened due to the lack of flame-retardant effective components, which cannot form a complete protective layer and carbon layer during combustion. Compared with Example 1, the bromine-based flame retardant (decabromodiphenyl ether) in the flame retardant system of Comparative Example 6 has poor compatibility with the PVC resin, which is easy to form micro-particles in the PVC resin, resulting in a decrease in transparency, and the bromine component may also have an adverse effect on the PVC molecular chain, thereby affecting the mechanical properties. Compared with Example 1, the polarity of the second shell component styrene-acrylonitrile copolymer in Comparative Example 7 is low, and the toughening agent is not uniformly dispersed in the PVC resin, forming obvious interface defects, which directly leads to the overall deterioration of transparency, toughness and strength.

[0089] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and supplements without departing from the method of the present application, and these improvements and supplements should also be considered as the protection scope of the present application.

Claims

1. A PVC electrical conduit, characterized in that, The raw materials include the following weight parts: PVC resin 100 parts, toughening agent 6-10 parts, flame retardant 15-25 parts, heat stabilizer 1-3 parts, lubricant 0.5-1.5 parts, antioxidant 0.1-0.8 parts; The toughening agent includes a core, a first shell layer formed on the surface of the core, and a second shell layer formed on the surface of the first shell layer, the core is a conjugated diene-(meth)acrylate copolymer, the first shell layer is an alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer, and the second shell layer is a (meth)acrylate-acrylamide copolymer; The average diameter of the core is 100-150 nm, the average thickness of the first shell layer is 20-50 nm, and the average thickness of the second shell layer is 5-20 nm; The conjugated diene-(meth)acrylate copolymer is obtained by copolymerization of butadiene and methyl methacrylate, and the mass ratio of the butadiene to the methyl methacrylate is 1:(1.2-1.8); The alkenyl copolymer-hydroxyl-containing (meth)acrylate copolymer is obtained by copolymerization of ethylene-vinyl acetate copolymer and N-hydroxyethyl acrylamide, and the mass ratio of the ethylene-vinyl acetate copolymer to the N-hydroxyethyl acrylamide is 1:(0.3-0.5), and the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 28%-32%; The (meth)acrylate-acrylamide copolymer is obtained by copolymerization of methyl methacrylate and N-(hydroxypropyl) acrylamide, and the mass ratio of the methyl methacrylate to the N-(hydroxypropyl) acrylamide is 1:(0.05-0.15); The flame retardant includes an organic silicon flame retardant and bisphenol A bis(diphenyl phosphate); The mass ratio of the organic silicon flame retardant to the bisphenol A bis(diphenyl phosphate) is 1:(1.5-2.5).

2. The PVC electrical sleeve of claim 1, wherein, The flame retardant further includes N-hydroxyethyl diethanolamine, and the mass ratio of the N-hydroxyethyl diethanolamine in the flame retardant is 5%-8%.

3. The PVC electrical sleeve of claim 1, wherein, The heat stabilizer is an organic tin stabilizer or a metal soap stabilizer; And / or, the lubricant includes at least one of calcium stearate, glycerol stearate, paraffin wax, and polyethylene wax; And / or, the antioxidant includes at least one of antioxidant CA, antioxidant 1010, antioxidant 168, antioxidant 245, and antioxidant 1076.

4. A process for the production of PVC electrical conduit as claimed in any one of claims 1 to 3 characterised in that, The method includes the following steps: Mixing the PVC resin, the toughening agent, the flame retardant, the heat stabilizer, the lubricant, and the antioxidant to obtain a mixture; Plasticizing the mixture and molding to obtain the PVC electrical bushing.

5. The PVC electrical bushing according to any one of claims 1-3 is applied to wire and cable threading.

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