Flame-retardant environment-friendly PVC cable and preparation method thereof

Abstract

The invention relates to a flame-retardant environment-friendly PVC cable and a preparation method thereof, and belongs to the technical field of PVC cables. The flame-retardant environment-friendly PVC cable comprises a PVC cable body and a flame-retardant layer arranged on the surface of the PVC cable body, the flame-retardant layer is prepared from the following components in parts by weight: 80 to 90 parts of PVC (Polyvinyl Chloride), 5 to 7 parts of compatilizer and 15 to 20 parts of hybrid flame retardant; a Schiff base structure rich in nitrogen element is synthesized on expandable graphite, a porous structure is formed, a zinc metal element is introduced, then a phosphorus element is introduced through chemical grafting, and through the synergistic effect of different flame-retardant mechanisms, the expandable graphite has high flame-retardant performance.

Description

Technical Field

[0001] The invention belongs to the technical field of PVC cables and relates to a flame-retardant and environment-friendly PVC cable and a preparation method thereof. Background Art

[0002] Among the types of cables, PVC (polyvinyl chloride) cables have played an important role in many fields such as electricity, communications, and construction due to their excellent insulation performance and low cost. However, the flammability of PVC cables has always been the focus of attention. In order to meet this challenge, flame retardant layers came into being and became an indispensable part of PVC cables.

[0003] When PVC cables encounter fire, the polyvinyl chloride material inside will decompose rapidly, accompanied by the release of a large amount of smoke and toxic gases. These toxic gases not only pose a threat to human health, but may also accelerate the spread of fire, bringing great difficulties to rescue work. Therefore, the flammability of PVC cables has become a major obstacle to their widespread application.

[0004] As a unique inorganic flame retardant material, expandable graphite plays an important role in fire prevention, heat insulation and other fields with its unique properties. When expandable graphite is heated, the water molecules inside it will vaporize rapidly, causing the distance between graphite layers to increase sharply, forming a porous expansion structure. This unique expansion mechanism causes the volume of graphite to expand rapidly by hundreds of times, forming a dense carbon foam layer, which effectively isolates oxygen, thereby blocking the combustion chain reaction and showing excellent flame retardant properties. According to experimental data, the limiting oxygen index (LOI) of composite materials with an appropriate amount of expandable graphite can be significantly improved, greatly improving the flame retardant grade of the material. The expanded graphite foam layer is not only dense but also has good thermal stability, which can effectively slow down heat transfer and have a good thermal insulation effect. This feature makes expandable graphite have broad application prospects in aerospace, building insulation and other fields.

[0005] However, when expandable graphite is added to most polymer matrices, the compatibility between the two is poor, which may cause problems such as increased wear and poor fluidity of the composite materials during processing such as mixing and extrusion. Summary of the invention

[0006] The purpose of the present invention is to provide a flame-retardant and environmentally friendly PVC cable and a preparation method thereof. A Schiff base structure rich in nitrogen is synthesized on expandable graphite to form a porous structure, zinc metal elements are introduced, and then phosphorus elements are introduced through chemical grafting. Through the synergistic effect of different flame-retardant mechanisms, the flame retardant ability of the material is significantly improved, while the mechanical properties of the PVC composite material are ensured.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A flame-retardant and environment-friendly PVC cable, comprising a PVC cable body and a flame-retardant layer arranged on the surface of the PVC cable body; the flame-retardant layer comprises the following components by weight: 80-90 parts of PVC, 5-7 parts of a compatibilizer and 15-20 parts of a hybrid flame retardant;

[0009] The preparation method of the hybrid flame retardant comprises the following steps:

[0010] Step S1: placing expandable graphite, anhydrous ethanol and aminothiophenol in a reaction kettle for ultrasonic dispersion, adding an auxiliary agent and cinnamaldehyde, heating and stirring, centrifuging to remove the supernatant, washing with alcohol, and vacuum drying to constant weight to obtain a preform;

[0011] Step S2: soaking the preform in an acidic solution, letting it stand, filtering out the solid, soaking it in a zinc chloride solution with stirring, filtering it, washing it with alcohol, and vacuum drying it to a constant weight to obtain an intermediate;

[0012] Step S3: After the intermediate and anhydrous ethanol are placed in a reaction kettle and stirred to mix, an initiator and DOPO are added and treated at a constant temperature, the supernatant is removed by centrifugation, the mixture is washed with alcohol, and vacuum dried to a constant weight to obtain a hybrid flame retardant.

[0013] As a preferred technical solution of the present invention, the compatibilizer is glyceryl methacrylate grafted polyvinyl chloride.

[0014] As a preferred technical solution of the present invention, in step S1, the ultrasonic dispersion is performed at a frequency of 300-360W for 10-12 minutes; the heating stirring is performed at a temperature of 60-70°C for 4-5 hours; and the alcohol washing is performed three times with anhydrous ethanol.

[0015] As a preferred technical solution of the present invention, in step S1, the mass ratio of expandable graphite, anhydrous ethanol, aminothiophenol, auxiliary agent and cinnamaldehyde is 18-20:50-60:3.6-4.2:0.2-0.3:4.8-5.0; the auxiliary agent is sodium bicarbonate; and the aminothiophenol is 3-aminothiophenol.

[0016] As a preferred technical solution of the present invention, in step S2, the standing time is 10-12 hours; the stirring treatment is stirring at a speed of 200-300 r / min for 4-6 hours and then standing for 2-3 hours; the alcohol washing is washing three times with anhydrous ethanol.

[0017] As a preferred technical solution of the present invention, in step S2, the volume ratio of the preform, the acid solution and the zinc chloride solution is 1.0-1.2:1.2-1.4:5.0-6.2; the acid solution is 1 mol / L hydrochloric acid solution; and the mass fraction of the zinc chloride solution is 2-3%.

[0018] As a preferred technical solution of the present invention, in step S3, the stirring and mixing is stirring at a speed of 700-800 r / min for 30-40 min; the constant temperature treatment is stirring at a temperature of 60-72°C for 10-12 h; and the alcohol washing is washing three times with anhydrous ethanol.

[0019] As a preferred technical solution of the present invention, in step S3, the mass ratio of the intermediate, anhydrous ethanol, initiator and DOPO is 20-22:70-80:0.2-0.3:5.8-7.0; the initiator is initiator AIBN; and the DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0020] A method for preparing a flame-retardant and environment-friendly PVC cable comprises the following steps: weighing PVC, a compatibilizer and a hybrid flame retardant by weight, mixing them, kneading them at 150-160°C for 20-30 minutes, placing them in a twin-screw extruder, melting and extruding them at 190-200°C, and coating them on the cable body to obtain the cable.

[0021] Beneficial effects of the present invention:

[0022] The present invention synthesizes a Schiff base structure rich in nitrogen on expandable graphite to form a porous structure, introduces zinc metal elements, and then introduces phosphorus elements through chemical grafting. Through the synergistic effect of different flame retardant mechanisms, the flame retardant ability of the material is significantly improved, while ensuring the mechanical properties of the PVC composite material. DETAILED DESCRIPTION

[0023] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0024] Example 1

[0025] A flame-retardant and environmentally friendly PVC cable comprises a PVC cable body and a flame-retardant layer arranged on the surface of the PVC cable body; the flame-retardant layer comprises the following components by weight: 80 parts of PVC, 5 parts of a compatibilizer and 15 parts of a hybrid flame retardant; the compatibilizer is methacrylate-grafted polyvinyl chloride;

[0026] The preparation method of the hybrid flame retardant comprises the following steps:

[0027] Step S1: placing expandable graphite, anhydrous ethanol and aminothiophenol in a reaction kettle for ultrasonic dispersion, adding an auxiliary agent and cinnamaldehyde, heating and stirring, centrifuging to remove the supernatant, washing with alcohol, and vacuum drying to constant weight to obtain a preform;

[0028] Step S2: soaking the preform in an acidic solution, letting it stand, filtering out the solid, soaking it in a zinc chloride solution with stirring, filtering it, washing it with alcohol, and vacuum drying it to a constant weight to obtain an intermediate;

[0029] Step S3: After the intermediate and anhydrous ethanol are placed in a reaction kettle and stirred to mix, an initiator and DOPO are added and treated at a constant temperature, the supernatant is removed by centrifugation, the mixture is washed with alcohol, and vacuum dried to a constant weight to obtain a hybrid flame retardant.

[0030] In step S1, the ultrasonic dispersion is performed at a frequency of 300 W for 10 minutes; the heating stirring is performed at a temperature of 60° C. for 4 hours; the alcohol washing is performed three times with anhydrous ethanol; the mass ratio of the expandable graphite, anhydrous ethanol, aminothiophenol, auxiliary agent and cinnamaldehyde is 18:50:3.6:0.2:4.8; and the auxiliary agent is sodium bicarbonate.

[0031] In step S2, the standing time is 10 hours; the stirring treatment is stirring at a speed of 200 r / min for 4 hours and then standing for 2 hours; the alcohol washing is washing three times with anhydrous ethanol; the volume ratio of the preform, the acid solution and the zinc chloride solution is 1.0:1.2:5.0; the acid solution is 1 mol / L hydrochloric acid solution; the mass fraction of the zinc chloride solution is 2%.

[0032] In step S3, the stirring and mixing is stirring at a speed of 700 r / min for 30 minutes; the constant temperature treatment is stirring at a temperature of 60° C. for 10 hours; the alcohol washing is washing three times with anhydrous ethanol; the mass ratio of the intermediate, anhydrous ethanol, initiator and DOPO is 20:70:0.2:5.8; and the initiator is initiator AIBN.

[0033] A method for preparing a flame-retardant and environment-friendly PVC cable comprises the following steps: PVC, a compatibilizer and a hybrid flame retardant are weighed in parts by weight, mixed, kneaded at 150° C. for 20 minutes, placed in a twin-screw extruder for melt extrusion at 190° C. to obtain a flame-retardant layer, and the melted flame-retardant layer is coated on the cable body to obtain the cable.

[0034] Example 2

[0035] A flame-retardant and environmentally friendly PVC cable comprises a PVC cable body and a flame-retardant layer arranged on the surface of the PVC cable body; the flame-retardant layer comprises the following components by weight: 85 parts of PVC, 6 parts of a compatibilizer and 18 parts of a hybrid flame retardant; the compatibilizer is methacrylate-grafted polyvinyl chloride;

[0036] The preparation method of the hybrid flame retardant comprises the following steps:

[0037] Step S1: placing expandable graphite, anhydrous ethanol and aminothiophenol in a reaction kettle for ultrasonic dispersion, adding an auxiliary agent and cinnamaldehyde, heating and stirring, centrifuging to remove the supernatant, washing with alcohol, and vacuum drying to constant weight to obtain a preform;

[0038] Step S2: soaking the preform in an acidic solution, letting it stand, filtering out the solid, soaking it in a zinc chloride solution with stirring, filtering it, washing it with alcohol, and vacuum drying it to a constant weight to obtain an intermediate;

[0039] Step S3: After the intermediate and anhydrous ethanol are placed in a reaction kettle and stirred to mix, an initiator and DOPO are added and treated at a constant temperature, the supernatant is removed by centrifugation, the mixture is washed with alcohol, and vacuum dried to a constant weight to obtain a hybrid flame retardant.

[0040] In step S1, the ultrasonic dispersion is performed at a frequency of 330 W for 11 minutes; the heating stirring is performed at a temperature of 65° C. for 4.5 hours; the alcohol washing is performed three times with anhydrous ethanol; the mass ratio of the expandable graphite, anhydrous ethanol, aminothiophenol, auxiliary agent and cinnamaldehyde is 19:55:3.9:0.25:4.9; and the auxiliary agent is sodium bicarbonate.

[0041] In step S2, the standing time is 11 hours; the stirring treatment is stirring at a speed of 250 r / min for 5 hours and then standing for 2.5 hours; the alcohol washing is washing three times with anhydrous ethanol; the volume ratio of the preform, the acid solution and the zinc chloride solution is 1.1:1.3:5.6; the acid solution is a 1 mol / L hydrochloric acid solution; the mass fraction of the zinc chloride solution is 2.5%.

[0042] In step S3, the stirring and mixing is stirring at a speed of 750 r / min for 35 minutes; the constant temperature treatment is stirring at a temperature of 66° C. for 11 hours; the alcohol washing is washing three times with anhydrous ethanol; the mass ratio of the intermediate, anhydrous ethanol, initiator and DOPO is 21:75:0.25:6.4; and the initiator is initiator AIBN.

[0043] A method for preparing a flame-retardant and environment-friendly PVC cable comprises the following steps: PVC, a compatibilizer and a hybrid flame retardant are weighed in parts by weight, mixed, kneaded at 155° C. for 25 minutes, placed in a twin-screw extruder for melt extrusion at 195° C. to obtain a flame-retardant layer, and the melted flame-retardant layer is coated on the cable body to obtain the cable.

[0044] Example 3

[0045] A flame-retardant and environmentally friendly PVC cable comprises a PVC cable body and a flame-retardant layer arranged on the surface of the PVC cable body; the flame-retardant layer comprises the following components by weight: 90 parts of PVC, 7 parts of a compatibilizer and 20 parts of a hybrid flame retardant; the compatibilizer is methacrylate-grafted polyvinyl chloride;

[0046] The preparation method of the hybrid flame retardant comprises the following steps:

[0047] Step S1: placing expandable graphite, anhydrous ethanol and aminothiophenol in a reaction kettle for ultrasonic dispersion, adding an auxiliary agent and cinnamaldehyde, heating and stirring, centrifuging to remove the supernatant, washing with alcohol, and vacuum drying to constant weight to obtain a preform;

[0048] Step S2: soaking the preform in an acidic solution, letting it stand, filtering out the solid, soaking it in a zinc chloride solution with stirring, filtering it, washing it with alcohol, and vacuum drying it to a constant weight to obtain an intermediate;

[0049] Step S3: After the intermediate and anhydrous ethanol are placed in a reaction kettle and stirred to mix, an initiator and DOPO are added and treated at a constant temperature, the supernatant is removed by centrifugation, the mixture is washed with alcohol, and vacuum dried to a constant weight to obtain a hybrid flame retardant.

[0050] In step S1, the ultrasonic dispersion is performed at a frequency of 360 W for 12 minutes; the heating stirring is performed at a temperature of 70° C. for 5 hours; the alcohol washing is performed three times with anhydrous ethanol; the mass ratio of the expandable graphite, anhydrous ethanol, aminothiophenol, auxiliary agent and cinnamaldehyde is 20:60:4.2:0.3:5.0; and the auxiliary agent is sodium bicarbonate.

[0051] In step S2, the standing time is 12 hours; the stirring treatment is stirring at a speed of 300 r / min for 6 hours and then standing for 3 hours; the alcohol washing is washing three times with anhydrous ethanol; the volume ratio of the preform, the acid solution and the zinc chloride solution is 1.2:1.4:6.2; the acid solution is 1 mol / L hydrochloric acid solution; the mass fraction of the zinc chloride solution is 3%.

[0052] In step S3, the stirring and mixing is stirring at a speed of 800 r / min for 40 minutes; the constant temperature treatment is stirring at a temperature of 72° C. for 12 hours; the alcohol washing is washing three times with anhydrous ethanol; the mass ratio of the intermediate, anhydrous ethanol, initiator and DOPO is 22:80:0.3:7.0; and the initiator is initiator AIBN.

[0053] A method for preparing a flame-retardant and environment-friendly PVC cable comprises the following steps: PVC, a compatibilizer and a hybrid flame retardant are weighed in parts by weight, mixed, kneaded at 160° C. for 30 minutes, placed in a twin-screw extruder for melt extrusion at 200° C. to obtain a flame-retardant layer, and the melted flame-retardant layer is coated on the cable body to obtain the cable.

[0054] Comparative Example 1

[0055] Compared with Example 2, Comparative Example 1 is different in that aminothiophenol is not used, and the remaining components, preparation steps and parameters are the same.

[0056] Comparative Example 2

[0057] Compared with Example 2, Comparative Example 2 is different in that aniline is used instead of aminothiophenol, and the other components, preparation steps and parameters are the same.

[0058] Comparative Example 3

[0059] Compared with Example 2, Comparative Example 3 is different in that no auxiliary agent is used, and the remaining components, preparation steps and parameters are the same.

[0060] Comparative Example 4

[0061] Compared with Example 2, Comparative Example 4 is different in that cinnamaldehyde is not used, and the remaining components, preparation steps and parameters are the same.

[0062] Comparative Example 5

[0063] Compared with Example 2, Comparative Example 5 is different in that DOPO is not used, and the other components, preparation steps and parameters are the same.

[0064] The flame retardant layers prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to the following limiting oxygen index test, and the test results are shown in Table 1.

[0065] Table 1

[0066] Limiting oxygen index (%) Example 1 31.3 Example 2 32.0 Example 3 31.5 Comparative Example 1 23.4 Comparative Example 2 24.3 Comparative Example 3 26.6 Comparative Example 4 25.2 Comparative Example 5 20.5

[0067] Compared with Comparative Examples 1-5, the flame retardant layer prepared in Example 1-3 of the present invention has thermal stability and a higher limiting oxygen index. Analysis and comparison show that the present invention uses aminothiophenol to load the expandable graphite structure through hydrogen bonds, and forms a Schiff base connection with cinnamaldehyde. The auxiliary agent and acid soaking expand the intermediate channel structure to obtain a higher specific surface area, and then introduce zinc metal elements through soaking, and then promote grafting more DOPO through unsaturated double bonds, introduce P elements, so that an inorganic inside and organic outside wrapping structure is formed, which is used in PVC composite materials, that is, by synthesizing a Schiff base structure rich in nitrogen on expandable graphite, forming a porous structure, introducing zinc metal elements, and then introducing phosphorus elements through chemical grafting, and through the synergistic effect of different flame retardant mechanisms, it has higher flame retardant properties.

[0068] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A flame-retardant and environmentally friendly PVC cable, characterized in that: The flame-retardant and environmentally friendly PVC cable comprises a PVC cable body and a flame-retardant layer arranged on the surface of the PVC cable body; the flame-retardant layer comprises the following components by weight: 80-90 parts of PVC, 5-7 parts of a compatibilizer and 15-20 parts of a hybrid flame retardant; The preparation method of the hybrid flame retardant comprises the following steps: Step S1: placing expandable graphite, anhydrous ethanol and aminothiophenol in a reaction kettle for ultrasonic dispersion, adding an auxiliary agent and cinnamaldehyde, heating and stirring, centrifuging to remove the supernatant, washing with alcohol, and vacuum drying to constant weight to obtain a preform; Step S2: soaking the preform in an acidic solution, letting it stand, filtering out the solid, soaking it in a zinc chloride solution with stirring, filtering it, washing it with alcohol, and vacuum drying it to a constant weight to obtain an intermediate; Step S3: After the intermediate and anhydrous ethanol are placed in a reaction kettle and stirred to mix, an initiator and DOPO are added and treated at a constant temperature, the supernatant is removed by centrifugation, the mixture is washed with alcohol, and vacuum dried to a constant weight to obtain a hybrid flame retardant.

2. A flame-retardant and environmentally friendly PVC cable according to claim 1, characterized in that: The compatibilizer is glyceryl methacrylate grafted polyvinyl chloride.

3. The flame-retardant and environmentally friendly PVC cable according to claim 1, characterized in that: In step S1, the ultrasonic dispersion is performed at a frequency of 300-360W for 10-12 minutes; the heating and stirring is performed at a temperature of 60-70°C for 4-5 hours; and the alcohol washing is performed three times with anhydrous ethanol.

4. The flame-retardant and environmentally friendly PVC cable according to claim 1, characterized in that: In step S1, the mass ratio of the expandable graphite, anhydrous ethanol, aminothiophenol, auxiliary agent and cinnamaldehyde is 18-20: 50-60: 3.6-4.2: 0.2-0.3: 4.8-5.0; the auxiliary agent is sodium bicarbonate.

5. The flame-retardant and environmentally friendly PVC cable according to claim 1, characterized in that: In step S2, the standing time is 10-12 hours; the stirring treatment is stirring at a speed of 200-300 r / min for 4-6 hours and then standing for 2-3 hours; the alcohol washing is washing three times with anhydrous ethanol.

6. The flame-retardant and environmentally friendly PVC cable according to claim 1, characterized in that: In step S2, the volume ratio of the preform, the acid solution and the zinc chloride solution is 1.0-1.2:1.2-1.4:5.0-6.2; the acid solution is a 1 mol / L hydrochloric acid solution; and the mass fraction of the zinc chloride solution is 2-3%.

7. The flame-retardant and environmentally friendly PVC cable according to claim 1, characterized in that: In step S3, the stirring and mixing is stirring at a speed of 700-800 r / min for 30-40 minutes; the constant temperature treatment is stirring at a temperature of 60-72° C. for 10-12 hours; and the alcohol washing is washing three times with anhydrous ethanol.

8. The flame-retardant and environmentally friendly PVC cable according to claim 1, characterized in that: In step S3, the mass ratio of the intermediate, anhydrous ethanol, initiator and DOPO is 20-22:70-80:0.2-0.3:5.8-7.0; the initiator is initiator AIBN. The DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

9. A method for preparing a flame-retardant and environmentally friendly PVC cable according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: weighing PVC, a compatibilizer and a hybrid flame retardant by weight, mixing them, kneading them at 150-160° C. for 20-30 minutes, placing them in a twin-screw extruder for melt extrusion at 190-200° C., and coating them on the cable body to obtain the product.