A flame-retardant and high-toughness PVC electrical casing and its preparation method

Abstract

The present invention relates to the technical field of polyvinyl chloride, and discloses a flame-retardant and high-toughness PVC electrical conduit and a preparation method thereof. The PVC electrical conduit of the present invention comprises 100 parts of polyvinyl chloride resin, 3-10 parts of copper-carrying core-shell particle toughening agent, 0.3-1.2 parts of maleic anhydride grafted polyethylene wax, 6-10 parts of plasticizer, and 2.5-3.5 parts of heat stabilizer, and a double-roll open mill is used for plasticizing, discharging, and molding to obtain a flame-retardant and high-toughness PVC electrical conduit. The core-shell particle toughening agent is uniformly dispersed in the polyvinyl chloride, plays a good toughening effect, improves the tensile properties and impact strength of the material, contains a large amount of copper ions in the shell-core particle toughening agent, and the copper ions can promote the cross-linking of polyolefin chains on the polyvinyl chloride main chain to form carbon during combustion, thereby improving the limiting oxygen index and flame retardant properties of the polyvinyl chloride, and the prepared PVC material has good practical applications in aspects such as electrical conduits.

Description

Technical Field

[0001] The invention relates to the technical field of polyvinyl chloride, in particular to a flame-retardant and high-toughness PVC electrical casing and a preparation method thereof. Background Art

[0002] Polyvinyl chloride is the third largest synthetic polymer plastic in the world. It has good mechanical strength, wear resistance, dielectric properties and other properties. It is widely used in pipes, wires and cables, packaging, construction materials and other fields. Traditional polyvinyl chloride materials have poor toughness and poor impact resistance, which limits the practical application of polyvinyl chloride. Therefore, it needs to be toughened and modified. Common toughening agents include natural rubber, polyacrylate elastomers, core-shell latex particles, etc.

[0003] Although polyvinyl chloride has certain flame retardancy, it releases toxic gases during combustion, posing a great safety hazard. At present, the flame retardants used for polyvinyl chloride mainly include hydroxides, antimony trioxide, zinc borate, transition metal oxides, etc. Copper-based complex flame retardants have the characteristics of diverse preparation methods, rich carrier types, good carbonization effect, and excellent flame retardant properties. They are important applications in materials such as polyvinyl chloride and epoxy resins. Chinese patent CN112920526B discloses a method for preparing a flame-retardant and smoke-suppressing PVC sheet containing a copper ion and molybdate ion complex. The flame retardant and smoke-suppressing agent prepared using sodium p-styrene sulfonate, acryloyloxyethyl trimethylammonium chloride, copper chloride, and sodium molybdate as raw materials improves the flame retardant and smoke-suppressing effect of PVC sheets, but the patent does not solve the problems of low impact resistance and poor toughness of PVC materials. Summary of the invention

[0004] (I) Technical problem to be solved: The present invention provides a PVC electrical conduit with good flame retardancy, high impact strength and high toughness and a preparation method thereof.

[0005] (II) Technical solution: A flame-retardant and high-toughness PVC electrical conduit, which comprises, by weight, 100 parts of polyvinyl chloride resin, 3-10 parts of copper-loaded core-shell particle toughening agent, 0.3-1.2 parts of maleic anhydride grafted polyethylene wax, 6-10 parts of plasticizer dioctyl phthalate, and 2.5-3.5 parts of calcium zinc stabilizer.

[0006] The preparation method of the copper-loaded core-shell particle toughening agent is as follows: S1. Add water, polybutadiene latex, chelating agent sodium pyrophosphate, reducing agent glucose, reducing agent ferrous sulfate, and potassium hydroxide into a flask, introduce nitrogen, heat to 65-70°C, add styrene, 2,4-dihydroxybenzaldehyde condensed to p-aminostyrene, methyl methacrylate, and oxidant isopropylbenzene hydroperoxide after stirring, react for 4-6 hours, pour the solution into an aqueous solution of magnesium sulfate for demulsification, filter, wash with water, and dry to obtain a core-shell particle toughening agent.

[0007] S2. Add ethanol and core-shell particle toughening agent to the flask, disperse by ultrasonic, add copper nitrate, heat to 70-90°C, stir and react for 6-10 hours, filter after cooling, wash with water, and dry to obtain the copper-loaded core-shell particle toughening agent.

[0008] Preferably, by weight, the amount of polybutadiene latex in S1. is 100 parts, sodium pyrophosphate is 0.4-0.48 parts, glucose is 0.56-0.63 parts, ferrous sulfate is 0.009-0.01 parts, potassium hydroxide is 0.09-0.1 parts, styrene is 15-22 parts, 2,4-dihydroxybenzaldehyde condensed para-aminostyrene is 25-40 parts, methyl methacrylate is 16-22 parts, and isopropylbenzene hydroperoxide is 0.11-0.14 parts.

[0009] Preferably, by weight, the amount of the core-shell particle toughening agent in S2. is 100 parts, and the amount of copper nitrate is 25-40 parts.

[0010] Preferably, the preparation method of 2,4-dihydroxybenzaldehyde condensed p-aminostyrene is: add ethanol, 2,4-dihydroxybenzaldehyde and p-aminostyrene into a flask equipped with a condenser reflux tube, heat to 60-70°C, react for 3-4 hours, distill under reduced pressure, and recrystallize the product in dichloromethane to obtain 2,4-dihydroxybenzaldehyde condensed p-aminostyrene.

[0011] Preferably, by weight, the amount of 2,4-dihydroxybenzaldehyde is 100 parts, and the amount of p-aminostyrene is 86-91 parts.

[0012] Preferably, the preparation method of the flame-retardant and high-toughness PVC electrical conduit is: adding polyvinyl chloride resin, copper-loaded core-shell particle toughening agent, maleic anhydride grafted polyethylene wax, plasticizer, and heat stabilizer to a double-roll mill, plasticizing at 160-175°C for 4-6 minutes, discharging, and molding to obtain the flame-retardant and high-toughness PVC electrical conduit.

[0013] (III) Technical effect of the present invention: The present invention uses polybutadiene latex particles as the core and styrene, 2,4-dihydroxybenzaldehyde condensed para-aminostyrene and methyl methacrylate as the shell, and obtains a core-shell particle toughening agent through emulsion polymerization. The core-shell particle toughening agent contains salicylaldehyde Schiff base groups, which coordinate with copper ions, thereby complexing and adsorbing the copper ions into the toughening agent matrix to obtain copper-loaded core-shell toughened particles.

[0014] The invention blends polyvinyl chloride resin, copper-loaded core-shell toughening particles, maleic anhydride grafted polyethylene wax compatibilizer and the like to obtain a flame-retardant and high-toughness PVC electrical conduit material. When the polyvinyl chloride is subjected to external force, the core-shell particles can absorb and consume stress, and maleic anhydride grafted polyethylene wax is added as a compatibilizer, and the anhydride group of the maleic anhydride grafted polyethylene wax can react with the hydroxyl group in 2,4-dihydroxybenzaldehyde p-aminostyrene, thereby improving the compatibility between the core-shell particles and the polyvinyl chloride matrix and enhancing the interface bonding strength between the two. The core-shell particles are uniformly dispersed in the polyvinyl chloride to form uniform stress concentration points, which is beneficial to the transmission of stress between the polyvinyl chloride and the core-shell particle dispersed phase, thereby playing a good toughening role and improving the tensile properties and impact strength of the material.

[0015] The core-shell particle toughening agent of the present invention contains a large amount of copper ions. When burning, the copper ions can promote the cross-linking of the polyolefin chains on the main chain of polyvinyl chloride to form carbon, thereby improving the carbonization property of polyvinyl chloride, thereby improving the limiting oxygen index and flame retardant performance of polyvinyl chloride. The prepared PVC material has good practical application in electrical conduits and the like. DETAILED DESCRIPTION

[0016] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as limiting the present invention.

[0017] The following polyvinyl chloride resin, brand S-65, was purchased from Dongguan Hongrui Plastic Raw Materials Co., Ltd. Maleic anhydride grafted polyethylene wax, model PE-MA 4351, was purchased from Guangzhou Yinuo Chemical Technology Co., Ltd. Polybutadiene latex, model NipolLX111A2, solid content 54%, was purchased from Zeon Co., Ltd. Calcium zinc stabilizer, active ingredient content 99%, was purchased from Shandong Yueyang New Materials Co., Ltd.

[0018] Example 1

[0019] S1. Add 350 mL of ethanol, 20 g of 2,4-dihydroxybenzaldehyde, and 17.2 g of p-aminostyrene to a flask equipped with a condenser reflux tube, heat to 70°C, react for 4 hours, and distill under reduced pressure. The product is recrystallized in dichloromethane to obtain 2,4-dihydroxybenzaldehyde condensed p-aminostyrene. The reaction formula is as follows:

[0020] .

[0021] S2. Add water, 100g polybutadiene latex, 0.48g sodium pyrophosphate, 0.6g glucose, 0.01g ferrous sulfate, and 0.1g potassium hydroxide into a flask, introduce nitrogen, heat to 70°C, stir, add 22g styrene, 25g 2,4-dihydroxybenzaldehyde condensed para-aminostyrene, 20g methyl methacrylate, and 0.12g isopropylbenzene hydroperoxide, react for 6h, pour the solution into an aqueous solution of magnesium sulfate for demulsification, filter, wash with water, and dry to obtain a core-shell particle toughening agent.

[0022] S3. Add 650 mL of ethanol and 60 g of core-shell particle toughening agent into a flask, disperse by ultrasonic, add 15 g of copper nitrate, heat to 90°C, stir and react for 6 hours, filter after cooling, wash with water, and dry to obtain a copper-loaded core-shell particle toughening agent.

[0023] S4. Add 1 kg of polyvinyl chloride resin, 30 g of copper-loaded core-shell particle toughening agent, 3 g of maleic anhydride grafted polyethylene wax, 60 g of plasticizer dioctyl phthalate, and 28 g of calcium zinc stabilizer into a double-roll mill, and plasticize at 165°C for 6 min. Discharge and shape to obtain a flame-retardant and high-toughness PVC electrical conduit.

[0024] Example 2

[0025] S1. Add 400 mL of ethanol, 20 g of 2,4-dihydroxybenzaldehyde, and 18.2 g of p-aminostyrene to a flask equipped with a condenser reflux tube, heat to 60°C, react for 3 hours, and distill under reduced pressure. The product is recrystallized in dichloromethane to obtain 2,4-dihydroxybenzaldehyde condensed with p-aminostyrene.

[0026] S2. Add water, 100g polybutadiene latex, 0.4g sodium pyrophosphate, 0.63g glucose, 0.01g ferrous sulfate, and 0.1g potassium hydroxide into a flask, introduce nitrogen, heat to 70°C, stir, add 18g styrene, 33g 2,4-dihydroxybenzaldehyde condensed to p-aminostyrene, 16g methyl methacrylate, and 0.11g cumene hydroperoxide, react for 6h, pour the solution into an aqueous solution of magnesium sulfate for demulsification, filter, wash with water, and dry to obtain a core-shell particle toughening agent.

[0027] S3. Add 700 mL of ethanol and 60 g of core-shell particle toughening agent into a flask, disperse by ultrasonic, add 20 g of copper nitrate, heat to 70°C, stir and react for 10 hours, filter after cooling, wash with water, and dry to obtain a copper-loaded core-shell particle toughening agent.

[0028] S4. Add 1 kg of polyvinyl chloride resin, 60 g of copper-loaded core-shell particle toughening agent, 8 g of maleic anhydride grafted polyethylene wax, 100 g of plasticizer dioctyl phthalate, and 35 g of calcium zinc stabilizer into a double-roll mill, and plasticize at 170°C for 4 min. Discharge and shape to obtain a flame-retardant and high-toughness PVC electrical conduit.

[0029] Example 3

[0030] S1. Prepare 2,4-dihydroxybenzaldehyde condensate and p-aminostyrene according to the method of Example 1.

[0031] S2. Add water, 100g polybutadiene latex, 0.45g sodium pyrophosphate, 0.56g glucose, 0.009g ferrous sulfate, and 0.09g potassium hydroxide into a flask, introduce nitrogen, heat to 65°C, stir, add 15g styrene, 40g 2,4-dihydroxybenzaldehyde condensed to p-aminostyrene, 22g methyl methacrylate, and 0.14g isopropylbenzene hydroperoxide, react for 4h, pour the solution into an aqueous solution of magnesium sulfate for demulsification, filter, wash with water, and dry to obtain a core-shell particle toughening agent.

[0032] S3. Add 800 mL of ethanol and 60 g of core-shell particle toughening agent into a flask, disperse by ultrasonic, add 24 g of copper nitrate, heat to 75°C, stir and react for 10 hours, filter after cooling, wash with water, and dry to obtain a copper-loaded core-shell particle toughening agent.

[0033] S4. Add 1 kg of polyvinyl chloride resin, 100 g of copper-loaded core-shell particle toughening agent, 12 g of maleic anhydride grafted polyethylene wax, 100 g of plasticizer dioctyl phthalate, and 25 g of calcium zinc stabilizer into a double-roll mill, and plasticize at 160°C for 6 min. Discharge and shape to obtain a flame-retardant and high-toughness PVC electrical conduit.

[0034] Comparative Example 1

[0035] The difference between this comparative example and Example 1 is that no copper-loaded core-shell particle toughening agent is added.

[0036] S1. Add 1 kg of polyvinyl chloride resin, 3 g of maleic anhydride grafted polyethylene wax, 60 g of plasticizer dioctyl phthalate, and 28 g of calcium zinc stabilizer into a double-roll mill, and mix at 165°C for 6 min. Discharge and shape to obtain a flame-retardant and high-toughness PVC electrical conduit.

[0037] Comparative Example 2

[0038] The difference between this comparative example and Example 1 is that the core-shell particle toughening agent is used instead of the copper-loaded core-shell particle toughening agent.

[0039] S1. Add 1 kg of polyvinyl chloride resin, 30 g of core-shell particle toughening agent, 3 g of maleic anhydride grafted polyethylene wax, 60 g of plasticizer dioctyl phthalate, and 28 g of calcium zinc stabilizer into a double-roll mill, and mix at 165°C for 6 min. Discharge and shape to obtain flame-retardant and high-toughness PVC electrical conduit.

[0040] Comparative Example 3

[0041] The difference between this comparative example and Example 1 is that styrene is used instead of 2,4-dihydroxybenzaldehyde condensate p-aminostyrene.

[0042] S1. Add water, 100g polybutadiene latex, 0.48g sodium pyrophosphate, 0.6g glucose, 0.01g ferrous sulfate, and 0.1g potassium hydroxide into a flask, introduce nitrogen, heat to 70°C, add 47g styrene, 20g methyl methacrylate, and 0.12g cumene hydroperoxide after stirring, react for 6h, pour the solution into an aqueous solution of magnesium sulfate for demulsification, filter, wash with water, and dry to obtain a core-shell particle toughening agent.

[0043] S2. Add 650 mL of ethanol and 60 g of core-shell particle toughening agent into a flask, disperse by ultrasonic, add 15 g of copper nitrate, heat to 90°C, stir and react for 6 hours, filter after cooling, wash with water, and dry to obtain the core-shell particle toughening agent.

[0044] S3. Add 1 kg of polyvinyl chloride resin, 30 g of core-shell particle toughening agent, 3 g of maleic anhydride grafted polyethylene wax, 60 g of plasticizer dioctyl phthalate, and 28 g of calcium zinc stabilizer into a double-roll mill, and plasticize at 165°C for 6 min. Discharge and shape to obtain flame-retardant and high-toughness PVC electrical conduit.

[0045] Comparative Example 4

[0046] The difference between this comparative example and Example 1 is that no maleic anhydride grafted polyethylene wax is added.

[0047] S1. Add 1 kg of polyvinyl chloride resin, 30 g of copper-loaded core-shell particle toughening agent, 60 g of plasticizer dioctyl phthalate, and 28 g of calcium zinc stabilizer into a double-roll mill, and mix at 165°C for 6 min. Discharge and shape to obtain a flame-retardant and high-toughness PVC electrical conduit.

[0048] The flame retardant properties of the PVC electrical conduits prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were tested according to GB / T 2406.1-2008 standard.

[0049] The mechanical properties of Examples 1 to 3 and Comparative Examples 1 to 4 were tested. Taking Example 1 as an example, 1 kg of polyvinyl chloride resin, 30 g of copper-loaded core-shell particle toughening agent, 3 g of maleic anhydride grafted polyethylene wax, 100 g of plasticizer dioctyl phthalate, and 28 g of calcium zinc stabilizer were added to a double-roll mill, plasticized at 165 ° C for 6 min, discharged, and then hot-pressed at 180 ° C for 5 min at a pressure of 10 MPa in a flat vulcanizer to make a specimen. The tensile properties were tested according to standard GB / T 1040.1-2018. The simply supported beam impact strength was tested according to standard GB / T1043.1-2008. The test results are shown in Table 1.

[0050] Table 1 Performance test

[0051]

[0052] As can be seen from Table 1, compared with Comparative Example 1, Examples 1-3 add a copper-loaded core-shell particle toughening agent, the toughening agent has polybutadiene latex particles as the core, and a copolymer of methyl methacrylate, styrene, and 2,4-dihydroxybenzaldehyde condensed para-aminostyrene as the shell, forming a unique core-shell structure. When polyvinyl chloride is subjected to external force, the core-shell particles can absorb and consume stress, and maleic anhydride grafted polyethylene wax is added as a compatibilizer, the anhydride group of which can react with the hydroxyl group (the 4-position hydroxyl group not coordinated with the copper ion) in 2,4-dihydroxybenzaldehyde condensed para-aminostyrene, thereby improving the compatibility between the core-shell particle toughening agent and the polyvinyl chloride matrix, and enhancing the interfacial bonding strength between the two. The core-shell particle toughening agent is uniformly dispersed in the polyvinyl chloride to form a uniform stress concentration point, which is beneficial to the stress transfer between the polyvinyl chloride and the core-shell particle dispersed phase, thereby playing a good toughening role, and significantly improving the elongation at break and impact strength of the material.

[0053] And the core-shell particle toughening agent contains an o-hydroxy Schiff base structure ( ), and the copper ions are coordinated to adsorb the copper ions into the toughening agent matrix. During combustion, the copper ions can promote the cross-linking of the polyolefin chains on the main chain of polyvinyl chloride to form carbon, thereby improving the carbonization of polyvinyl chloride, thereby improving the limiting oxygen index and flame retardant properties of polyvinyl chloride.

[0054] The core-shell particle toughening agent added in Comparative Example 2 does not contain copper ions, and the limiting oxygen index and flame retardancy of polyvinyl chloride are low, but the tensile properties and impact strength are high.

[0055] In Comparative Example 3, styrene is used instead of 2,4-dihydroxybenzaldehyde condensed para-aminostyrene. The obtained core-shell particle toughening agent does not contain an o-hydroxy Schiff base structure and cannot undergo coordination and complex adsorption with copper ions. After washing with water, the copper ions are washed away from the core-shell particle toughening agent matrix, resulting in the core-shell particle toughening agent containing no copper ions, and the limiting oxygen index and flame retardant properties of polyvinyl chloride are low.

[0056] Comparative Example 4 did not add maleic anhydride grafted polyethylene wax, resulting in lower compatibility between the copper-loaded core-shell particle toughening agent and polyvinyl chloride than in Example 1, poor toughening effect, and lower tensile properties and impact strength.

Claims

1. A flame retardant and high-toughness PVC electrical conduit, characterized in that: The PVC electrical conduit comprises, by weight, 100 parts of polyvinyl chloride resin, 3-10 parts of copper-loaded core-shell particle toughening agent, 0.3-1.2 parts of maleic anhydride grafted polyethylene wax, 6-10 parts of plasticizer, and 2.5-3.5 parts of heat stabilizer; The preparation method of the copper-loaded core-shell particle toughening agent is as follows: S1. Add water, polybutadiene latex, sodium pyrophosphate, glucose, ferrous sulfate, potassium hydroxide to a flask, introduce nitrogen, heat to the reaction temperature, stir, add styrene, 2,4-dihydroxybenzaldehyde condensed p-aminostyrene, methyl methacrylate, cumene hydroperoxide, and pour the solution into an aqueous solution of magnesium sulfate for demulsification after the reaction, filter, wash with water, and dry to obtain a core-shell particle toughening agent; S2. Add ethanol and core-shell particle toughening agent into the flask, disperse by ultrasonic, add copper nitrate, stir for reaction, filter, wash with water, and dry to obtain the copper-loaded core-shell particle toughening agent.

2. The flame-retardant and high-toughness PVC electrical conduit according to claim 1, characterized in that: The plasticizer is dioctyl phthalate, and the heat stabilizer is calcium zinc stabilizer.

3. The flame-retardant and high-toughness PVC electrical conduit according to claim 1, characterized in that: In parts by weight, the amount of polybutadiene latex in S1 is 100 parts, sodium pyrophosphate is 0.4-0.48 parts, glucose is 0.56-0.63 parts, ferrous sulfate is 0.009-0.01 parts, potassium hydroxide is 0.09-0.1 parts, styrene is 15-22 parts, 2,4-dihydroxybenzaldehyde condensed para-aminostyrene is 25-40 parts, methyl methacrylate is 16-22 parts, and isopropylbenzene hydroperoxide is 0.11-0.14 parts.

4. The flame-retardant and high-toughness PVC electrical conduit according to claim 1, characterized in that: The reaction temperature in S1 is 65-70°C and the reaction time is 4-6h.

5. The flame-retardant and high-toughness PVC electrical conduit according to claim 1, characterized in that: In terms of weight, the amount of the core-shell particle toughening agent in S2 is 100 parts, and the amount of copper nitrate is 25-40 parts.

6. The flame-retardant and high-toughness PVC electrical conduit according to claim 1, characterized in that: The reaction temperature in S2 is 70-90°C and the reaction time is 6-10h.

7. The flame-retardant and high-toughness PVC electrical conduit according to claim 1, characterized in that: The preparation method of 2,4-dihydroxybenzaldehyde condensed p-aminostyrene comprises: adding ethanol, 2,4-dihydroxybenzaldehyde and p-aminostyrene into a flask provided with a condenser reflux tube, heating to 60-70° C., reacting for 3-4 hours, performing reduced pressure distillation, and recrystallizing the product in dichloromethane to obtain 2,4-dihydroxybenzaldehyde condensed p-aminostyrene.

8. The flame-retardant and high-toughness PVC electrical conduit according to claim 7, characterized in that: In terms of weight, the amount of 2,4-dihydroxybenzaldehyde is 100 parts, and the amount of p-aminostyrene is 86-91 parts.

9. A method for preparing the flame-retardant and high-toughness PVC electrical conduit according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: adding polyvinyl chloride resin, copper-loaded core-shell particle toughening agent, maleic anhydride grafted polyethylene wax, plasticizer and heat stabilizer into a double-roll mill, plasticizing at 160-175° C. for 4-6 minutes, discharging and molding to obtain a flame-retardant and high-toughness PVC electrical conduit.

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