CN112795077B - Low-smoke halogen-free cable material containing rare earth synergistic flame retardant and preparation thereof - Google Patents

Abstract

The invention relates to a low-smoke halogen-free cable material containing a rare earth synergistic flame retardant and a preparation method thereof, wherein the cable material is prepared from the following raw materials in parts by weight: 40-60 parts of ethylene-vinyl acetate copolymer, 20-40 parts of fluorosilicone rubber, 10-20 parts of terpene resin, 10-20 parts of polyamide resin, 20-30 parts of rare earth synergistic flame retardant, 15-25 parts of compatilizer, 5-10 parts of reinforcing agent, 3-9 parts of stabilizer, 0.5-1 part of lubricant and 0.2-1 part of antioxidant. Compared with the prior art, the cable material disclosed by the invention is simple in preparation process, good in molding processability, oil stain resistance, weather resistance, outstanding in flame-retardant and smoke-suppression effects, good in mechanical strength and toughness, capable of ensuring the working performance and service life of the cable and greatly improving the safety and reliability of the cable in use.

Description

Low-smoke halogen-free cable material containing rare earth synergistic flame retardant and preparation thereof

Technical Field

The invention belongs to the technical field of wires and cables, and relates to a low-smoke halogen-free cable material containing a rare earth synergistic flame retardant and a preparation method thereof.

Background

As is well known, the wire and cable have the functions of energy transmission and information transmission, and nowadays, with the rapid development of urban economy, the wire and cable are not only used for supplying electric power to factories, houses, amusement places, large markets and the like, but also widely used for rail transportation facilities such as subways, light rails, trams, maglev trains and the like, and have tightly penetrated various aspects of life and production of people. However, during the use of the electric wire cable, the electric wire cable is often burnt due to its own heat generation in the transmission of electric power or an external fire, thereby initiating and spreading the fire. Because the cable fire disaster has the characteristics of fast spread, difficult fire fighting, secondary hazard generation, long recovery time and the like, and great loss is brought to national economy and the lives and properties of people, people provide more rigorous operating conditions for the flame retardant property, the fireproof property and the safety and reliability of the electric wire and the cable. In the first place, in order to improve the flame retardancy of electric wires and cables, a flame retardant containing halogen is generally added, however, during the combustion process of such electric wires and cables, a large amount of smoke and hydrogen halide gas are released, so that people are suffocated in fire, and meanwhile, the electric wires and cables have high corrosivity to equipment, so-called "secondary disaster", therefore, the development and use of low-smoke, low-halogen and halogen-free flame retardant materials are one of the development directions in cables and other fields.

At present, most of the traditional halogen-free low-smoke flame-retardant materials are prepared by adding aluminum hydroxide into a polyolefin substrate as a flame-retardant system, so that a certain flame-retardant effect can be achieved, but the requirements on electrical properties cannot be met at the same time. While the halogen-free low-smoke flame-retardant polyolefin material meeting the high electrical property requirement generally adopts magnesium as a flame retardant, but because domestic magnesium has large heat productivity and poor fluidity when being extruded in a screw extruder, if the extrusion speed is too high, the temperature is increased, so that the material is decomposed, and the large-scale production is not suitable in the practical application; the imported magnesium has the problem of high price, greatly increases the manufacturing cost, has no competitive advantage in domestic markets, and is not suitable for being used as a flame retardant. In addition, the addition of a large amount of inorganic materials also affects the physical and mechanical properties and the processing properties of the polyolefin material.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a low-smoke halogen-free cable material which is convenient to form and process, good in oil stain resistance, outstanding in flame retardance, high in strength and toughness and contains a rare earth synergistic flame retardant and a preparation method thereof.

The purpose of the invention can be realized by the following technical scheme:

according to one aspect of the invention, the low-smoke halogen-free cable material containing the rare earth synergistic flame retardant is prepared from the following raw materials in parts by weight: 40-60 parts of ethylene-vinyl acetate copolymer, 20-40 parts of fluorosilicone rubber, 10-20 parts of terpene resin, 10-20 parts of polyamide resin, 20-30 parts of rare earth synergistic flame retardant, 15-25 parts of compatilizer, 5-10 parts of reinforcing agent, 3-9 parts of stabilizer, 0.5-1 part of lubricant and 0.2-1 part of antioxidant.

In one embodiment, the ethylene-vinyl acetate copolymer has a vinyl acetate content of 12 to 25wt% and a melt index of 8 to 20 g/10min (190 ℃,2.16 kg).

In one embodiment, the fluorosilicone rubber has a reduction in tensile strength at 225 ℃ of 72 h of no greater than 35% from its initial tensile strength and an elongation at break of no greater than 30% from its initial elongation at break.

Preferably, the fluorosilicone rubber can be selected from one or more of commercially available FSR8430-U, FSR8440-U, FSR8460-U or FSR 8470-U.

In one embodiment, the terpene resin has a softening point of 100-130 deg.C and an acid value less than 1.0 mg KOH/g.

Preferably, the terpene resin may be selected from one or more of commercially available TP1105, TP1115 or TP 1125.

As an embodiment, the polyamide resin is selected from one or both of nylon 6 or nylon 66.

Preferably, the nylon 6 may be selected from commercially available VOLGAMID25 or VOLGAMID27, and the nylon 66 may be selected from commercially available EPR27 or 50BWFS.

As an embodiment, the rare earth synergistic flame retardant is prepared by compounding modified attapulgite loaded with a nano rare earth compound and an intumescent flame retardant according to a mass ratio of 1-5.

Preferably, the nano rare earth compound is selected from one or more of nano cerium oxide, nano lanthanum oxide, nano yttrium oxide, nano praseodymium oxide or nano rubidium oxide, and the particle size of the nano rare earth compound is less than or equal to 400 nm.

Preferably, the intumescent flame retardant is formed by mixing ammonium polyphosphate and trihydroxyethyl isocyanurate according to the mass ratio of 4-9:1.

As an embodiment, the preparation method of the modified attapulgite loaded with the nano rare earth compound comprises the following steps: washing the attapulgite soaked by the hydrogen peroxide solution to be neutral by using deionized water, and drying; adding the nano rare earth compound, the silane coupling agent and the attapulgite into deionized water, stirring and reacting for 1-2 hours at 80-90 ℃, centrifugally separating, retaining solids, washing with absolute ethyl alcohol for a plurality of times respectively, drying in vacuum, grinding, and sieving with a 500-mesh sieve.

Preferably, the addition amount of the nano rare earth compound is 20-60 wt%, the addition amount of the silane coupling agent is 2-10 wt%, and the mass concentration of the attapulgite in deionized water is 1.0-1.8 g/mL based on the mass of the dried attapulgite.

In one embodiment, the compatibilizer is selected from maleic anhydride grafted EVA having a grafting ratio of 1.2 to 1.8% and a melt index of 2 to 5 g/10min (190 ℃,2.16 kg).

As an embodiment, the strengthening agent is selected from fumed silica.

In one embodiment, the stabilizer is an organotin-based heat stabilizer and may be selected from at least one of dibutyltin maleate, dibutyltin dilaurate, dibutyltin laurate maleate, di-n-octyltin dilaurate, or di-n-octyltin bis (isooctyl thioglycolate).

In one embodiment, the lubricant is at least one of natural paraffin, liquid paraffin, microcrystalline paraffin, polyethylene wax, butyl stearate, oleamide, ethylene bis stearamide, and silicone powder.

As an embodiment, the antioxidant is at least one of 2,6-di-tert-butyl-p-cresol, octadecyl beta (3,5 di-tert-butyl-4-hydroxyphenyl) propionate, 1,1,3 tris (2-methyl-4 hydroxy-5-tert-butylphenyl) butane, 2,2' -methylenebis (4-ethyl-6-tert-butylphenol), 1,3,5-tris (3,5 tert-butyl-4-hydroxybenzyl) trimethylbenzene, 2,2' -methylenebis (4-methyl-6-tert-butylphenol), 4,4' -di-tert-octyldiphenylamine.

According to another aspect of the present invention, there is provided a preparation method of the low smoke zero halogen cable material containing the rare earth synergistic flame retardant, the method includes the following steps:

step 1): uniformly stirring and mixing ethylene-vinyl acetate copolymer, polyamide resin, compatilizer, rare earth synergistic flame retardant, stabilizer, lubricant and antioxidant in parts by weight at a high speed to prepare premix A;

step 2): uniformly stirring and mixing the fluorosilicone rubber, the terpene resin and the reinforcing agent at a high speed according to the parts by weight to prepare a premix B;

step 3): adding the premix A into a double-screw extruder from a main feed inlet, adding the premix B into the double-screw extruder through a side feed inlet, and cooling, drying and granulating after extrusion to obtain the low-smoke halogen-free cable material.

As a preferable technical scheme, the temperature of a first zone of the double-screw extruder is 210-230 ℃, the temperature of a second zone is 220-240 ℃, the temperature of a third zone is 220-240 ℃, the temperature of a fourth zone is 220-240 ℃, the temperature of a fifth zone is 230-250 ℃, the temperature of a sixth zone is 240-260 ℃, the temperature of a seventh zone is 230-250 ℃, the temperature of an eighth zone is 220-240 ℃ and the temperature of a ninth zone is 200-220 ℃.

Compared with the prior art, the invention has the following characteristics:

1) The cable material provided by the invention takes the ethylene-vinyl acetate copolymer as a main base material, introduces the fluorosilicone rubber to enhance the toughness and weather aging resistance of the base material, and has a fluorine-containing group, so that the medium resistance of the base material can be improved, the tolerance of a material system to organic solvents, oil substances and acid and alkali substances can be improved, and in addition, aiming at the fluorosilicone rubber, the molecular main chain structural unit of the fluorosilicone rubber is-Si-O-, the fumed silica is taken as a reinforcing agent, the fumed silica has the same silica framework, and the fumed silica particles can be stably filled in gaps of a cross-linking network in the fluorosilicone rubber, so that a stronger interaction is formed, the strength of the fluorosilicone rubber can be enhanced, the fluorosilicone rubber can be taken as a carrier and is dispersed in the ethylene-vinyl acetate copolymer base material, the heat resistance and the electric resistance of the base material can be effectively improved, the final material has excellent electric insulation and flame retardance, and the terpene resin is compounded with the fluorosilicone rubber, so that the adhesion between the fluorosilicone rubber particles and the base material can be stably fused in the base material, and the aging resistance of the base material can be further improved;

2) In order to improve the flame retardant property of the cable material, the invention adopts rare earth synergistic flame retardant which is compounded by modified attapulgite loaded with a nano rare earth compound and an intumescent flame retardant, silane coupling agent is adopted to modify the attapulgite, active groups can be introduced to the surface of attapulgite particles, the compatibility of the modified attapulgite and a base material is obviously improved, the mechanical strength of a material system is favorably enhanced, the acid and alkali resistance, corrosion resistance, mildew resistance and insulativity of the material system can be further improved, the modified attapulgite can also form stronger interaction with the nano rare earth compound, the nano rare earth compound and the attapulgite have excellent flame retardance, the nano rare earth compound and the attapulgite can jointly play a flame retardant synergistic effect when being compounded with the intumescent flame retardant, a stable and compact inorganic layer can be formed during combustion, heat propagation and smoke release can be effectively prevented, and thus the material system is endowed with excellent flame retardant and smoke suppression effects;

3) The cable material disclosed by the invention is simple in preparation process, good in molding processability, oil stain resistance, good in weather resistance, excellent in flame retardant and smoke suppression effects, good in mechanical strength and toughness, capable of ensuring the working performance and the service life of the cable, greatly improving the safety and the reliability of the cable in use and good in application prospect.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed embodiment and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments. All other embodiments obtained by a person skilled in the art without making any inventive step are within the scope of protection of the present invention.

As used herein, the term "about" when used to modify a numerical value means within + -5% of the error margin measured for that value.

The theory or mechanism described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, i.e., the present disclosure may be practiced without limitation to any particular theory or mechanism.

The present invention will be described in detail with reference to specific examples.

Example 1:

the cable material is prepared from the following raw materials in parts by weight: 40 parts of ethylene-vinyl acetate copolymer, 20 parts of fluorosilicone rubber, 10 parts of terpene resin, 10 parts of polyamide resin, 20 parts of rare earth synergistic flame retardant, 15 parts of compatilizer, 5 parts of reinforcing agent, 3 parts of stabilizer, 0.5 part of lubricant and 0.2 part of antioxidant.

Wherein the ethylene-vinyl acetate copolymer used has a vinyl acetate content of 12 wt% and a melt index of about 8 g/10min (190 ℃,2.16 kg); the fluorosilicone rubber used is FSR8430-U sold in the market; the terpene resin used was commercially available TP1105; the polyamide resin used was commercially available VOLGAMID25; the compatibilizer used was maleic anhydride grafted EVA with a grafting yield of 1.2% and a melt index of about 2 g/10min (190 ℃,2.16 kg); the reinforcing agent is fumed silica; the stabilizer is dibutyltin maleate; the lubricant used is polyethylene wax; the antioxidant used was 2,6-di-tert-butyl-p-cresol.

In the embodiment, the rare earth synergistic flame retardant is prepared by compounding modified attapulgite loaded with a nano rare earth compound and an intumescent flame retardant according to a mass ratio of 1.

In this example, the preparation method of the modified attapulgite loaded with the nano rare earth compound is as follows: washing the attapulgite soaked by 15 wt% hydrogen peroxide solution to be neutral by deionized water, and drying; adding the nano rare earth compound, gamma-aminopropyl trimethoxy silane and attapulgite into deionized water, stirring and reacting for 2 hours at 80 ℃, centrifugally separating, retaining solids, washing with absolute ethyl alcohol for a plurality of times, drying in vacuum, grinding, and sieving with a 500-mesh sieve.

In the preparation process, the addition amount of the nano rare earth compound is 20 wt%, the addition amount of the gamma-aminopropyl trimethoxy silane is 2 wt% and the mass concentration of the attapulgite in deionized water is 1.0 g/mL based on the mass of the dried attapulgite.

Example 2:

the cable material of the embodiment is prepared from the following raw materials in parts by weight: 60 parts of ethylene-vinyl acetate copolymer, 40 parts of fluorosilicone rubber, 20 parts of terpene resin, 20 parts of polyamide resin, 30 parts of rare earth synergistic flame retardant, 25 parts of compatilizer, 10 parts of reinforcing agent, 9 parts of stabilizer, 1 part of lubricant and 1 part of antioxidant.

Wherein the ethylene-vinyl acetate copolymer used has a vinyl acetate content of 25wt% and a melt index of about 20 g/10min (190 ℃,2.16 kg); the fluorosilicone rubber used is FSR8440-U sold in the market; the terpene resin used was commercially available TP1115; the polyamide resin used was commercially available VOLGAMID27; the compatibilizer used was maleic anhydride grafted EVA with a grafting yield of 1.8% and a melt index of about 5 g/10min (190 ℃,2.16 kg); the reinforcing agent is fumed silica; the stabilizer used is dibutyltin dilaurate; the lubricant used was butyl stearate; the antioxidant used was octadecyl beta (3,5 di-tert-butyl-4-hydroxyphenyl) propionate.

In the embodiment, the rare earth synergistic flame retardant is prepared by compounding modified attapulgite loaded with a nano rare earth compound and an intumescent flame retardant according to a mass ratio of 5 to 10, wherein the nano rare earth compound is nano rubidium oxide with a particle size of less than or equal to 400 nm, and the intumescent flame retardant is prepared by mixing ammonium polyphosphate and trihydroxyethyl isocyanurate according to a mass ratio of 9:1.

In this example, the preparation method of the modified attapulgite loaded with the nano rare earth compound was as follows: washing the attapulgite soaked by 15 wt% hydrogen peroxide solution to be neutral by deionized water, and drying; adding the nano rare earth compound, N-2-aminoethyl-3-aminopropylmethyldimethoxysilane and attapulgite into deionized water, stirring and reacting for 1 hour at 90 ℃, centrifugally separating, retaining solids, washing with absolute ethyl alcohol for a plurality of times respectively, drying in vacuum, grinding, and sieving with a 500-mesh sieve.

In the preparation process, the addition amount of the nano rare earth compound is 60 wt%, the addition amount of the N-2-aminoethyl-3-aminopropylmethyldimethoxysilane is 10 wt% and the mass concentration of the attapulgite in deionized water is 1.8 g/mL based on the mass of the dried attapulgite.

Example 3:

the cable material of the embodiment is prepared from the following raw materials in parts by weight: 52 parts of ethylene-vinyl acetate copolymer, 28 parts of fluorosilicone rubber, 15 parts of terpene resin, 15 parts of polyamide resin, 25 parts of rare earth synergistic flame retardant, 20 parts of compatilizer, 6 parts of reinforcing agent, 4 parts of stabilizer, 0.6 part of lubricant and 0.4 part of antioxidant.

Wherein the ethylene-vinyl acetate copolymer used has a vinyl acetate content of 18 wt% and a melt index of about 11 g/10min (190 ℃,2.16 kg); the fluorosilicone rubber used is FSR8460-U which is sold on the market; the terpene resin used was commercially available TP1125; the polyamide resin used is a commercially available 50BWFS; the compatibilizer used was maleic anhydride grafted EVA with a grafting yield of 1.4% and a melt index of about 3 g/10min (190 ℃,2.16 kg); the reinforcing agent is fumed silica; the stabilizer is prepared by mixing dibutyltin laurate maleate and di-n-octyltin maleate according to the mass ratio of 1:1; the lubricant is prepared by mixing natural paraffin, polyethylene wax and ethylene bis stearamide according to a mass ratio of 1; the antioxidant is prepared by mixing 1,1,3 tris (2-methyl-4 hydroxy-5 tert-butylphenyl) butane, 2,2' -methylene bis (4-ethyl-6 tert-butylphenol), 1,3,5-tris (3,5 tert-butyl-4-hydroxybenzyl) trimethylbenzene in a mass ratio of 5.

In the embodiment, the rare earth synergistic flame retardant is prepared by compounding modified attapulgite loaded with a nano rare earth compound and an intumescent flame retardant according to a mass ratio of 4 to 10, wherein the nano rare earth compound is nano lanthanum oxide with the particle size of not more than 400 nm, and the intumescent flame retardant is prepared by mixing ammonium polyphosphate and trihydroxyethyl isocyanurate according to a mass ratio of 6:1.

In this example, the preparation method of the modified attapulgite loaded with the nano rare earth compound is as follows: washing the attapulgite soaked by 15 wt% hydrogen peroxide solution to be neutral by deionized water, and drying; adding the nano rare earth compound, 3- (2,3-glycidoxy) propyl methyl dimethoxy silane and attapulgite into deionized water, stirring and reacting for 1 hour at 90 ℃, centrifugally separating, retaining solids, washing with absolute ethyl alcohol for a plurality of times respectively, drying in vacuum, grinding, and sieving with a 500-mesh sieve.

In the preparation process, the addition amount of the nano rare earth compound is 48 wt%, the addition amount of 3- (2,3-glycidoxy) propyl methyl dimethoxy silane is 6 wt% and the mass concentration of the attapulgite in deionized water is 1.6 g/mL based on the mass of the dried attapulgite.

Example 4:

the cable material of the embodiment is prepared from the following raw materials in parts by weight: 45 parts of ethylene-vinyl acetate copolymer, 30 parts of fluorosilicone rubber, 12 parts of terpene resin, 18 parts of polyamide resin, 22 parts of rare earth synergistic flame retardant, 18 parts of compatilizer, 8 parts of reinforcing agent, 5 parts of stabilizer, 0.8 part of lubricant and 0.7 part of antioxidant.

Wherein the ethylene-vinyl acetate copolymer used has a vinyl acetate content of 22 wt% and a melt index of about 18 g/10min (190 ℃,2.16 kg); the fluorosilicone rubber used is FSR8470-U sold in the market; the terpene resin used was commercially available TP1125; the polyamide resin used was commercially available EPR27; the compatibilizer used was maleic anhydride grafted EVA with a grafting yield of 1.4% and a melt index of about 3 g/10min (190 ℃,2.16 kg); the reinforcing agent is fumed silica; the stabilizer used is di (isooctyl thioglycolate) di-n-octyl tin; the lubricant is prepared by mixing microcrystalline paraffin, oleamide and silicone powder according to the mass ratio of 1; the antioxidant used was 2,2' -methylenebis (4-methyl-6-tert-butylphenol).

In the embodiment, the rare earth synergistic flame retardant is prepared by compounding modified attapulgite loaded with a nano rare earth compound and an intumescent flame retardant according to the mass ratio of 3 to 10, wherein the nano rare earth compound is nano yttrium oxide with the particle size of less than or equal to 400 nm, and the intumescent flame retardant is prepared by mixing ammonium polyphosphate and trihydroxyethyl isocyanurate according to the mass ratio of 5:1.

In this example, the preparation method of the modified attapulgite loaded with the nano rare earth compound was as follows: washing the attapulgite soaked by the hydrogen peroxide solution with the concentration of 15 wt% to be neutral by deionized water, and drying; adding the nano rare earth compound, vinyl tri (beta-methoxyethoxy) silane and attapulgite into deionized water, stirring and reacting for 2 hours at 86 ℃, centrifugally separating, retaining solids, washing with absolute ethyl alcohol for a plurality of times, drying in vacuum, grinding, and sieving with a 500-mesh sieve.

In the preparation process, the addition amount of the nano rare earth compound is 35 wt%, the addition amount of the vinyl tris (beta-methoxyethoxy) silane is 8 wt% and the mass concentration of the attapulgite in deionized water is 1.3 g/mL based on the mass of the dried attapulgite.

The cable materials of the above examples 1-4 were prepared by the following method:

step 1): uniformly stirring and mixing ethylene-vinyl acetate copolymer, polyamide resin, compatilizer, rare earth synergistic flame retardant, stabilizer, lubricant and antioxidant in parts by weight at a high speed to prepare premix A;

step 2): uniformly stirring and mixing the fluorosilicone rubber, the terpene resin and the reinforcing agent at a high speed according to the parts by weight to prepare a premix B;

and step 3): adding the premix A into a double-screw extruder from a main feed inlet, adding the premix B into the double-screw extruder through a side feed inlet, and cooling, drying and granulating after extrusion.

In the preparation method, the temperature of the first zone of the double-screw extruder is 220 ℃, the temperature of the second zone is 230 ℃, the temperature of the third zone is 235 ℃, the temperature of the fourth zone is 240 ℃, the temperature of the fifth zone is 245 ℃, the temperature of the sixth zone is 250 ℃, the temperature of the seventh zone is 250 ℃, the temperature of the eighth zone is 240 ℃ and the temperature of the ninth zone is 210 ℃.

Comparative example 1:

the comparative example cable material used attapulgite as a flame retardant, and the remainder was the same as in example 3.

Comparative example 2:

the comparative example cable material uses a mixture of ammonium polyphosphate and trihydroxyethyl isocyanurate in a mass ratio of 6:1 as a flame retardant, and the rest is the same as example 3.

Comparative example 3:

this comparative example does not contain fluorosilicone rubber, terpene resin, and reinforcing agent, and the remainder is the same as example 3.

The results of the performance tests of the cable materials prepared in examples 1 to 4 and comparative examples 1 to 3 are shown in table 1 below.

Table 1 results of performance testing

Note: the tensile strength and elongation at break tests in Table 1 were carried out in accordance with GB/T1040.3.

As can be seen from the test results in Table 1, the cable materials prepared in the embodiments 1 to 4 of the present invention have excellent mechanical strength and oil corrosion resistance, and are excellent in flame retardancy and insulating property, and have good application prospects.

Although the present invention has been described in detail, modifications within the spirit and scope of the invention will be apparent to those skilled in the art. Furthermore, it should be understood that the various aspects recited, portions of different embodiments, and various features recited may be combined or interchanged either in whole or in part. In the various embodiments described above, those embodiments that refer to another embodiment may be combined with other embodiments as appropriate, as will be appreciated by those skilled in the art. Furthermore, those skilled in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.

Claims (8)

1. The low-smoke halogen-free cable material containing the rare earth synergistic flame retardant is characterized by being prepared from the following raw materials in parts by weight: 40-60 parts of ethylene-vinyl acetate copolymer, 20-40 parts of fluorosilicone rubber, 10-20 parts of terpene resin, 10-20 parts of polyamide resin, 20-30 parts of rare earth synergistic flame retardant, 15-25 parts of compatilizer, 5-10 parts of reinforcing agent, 3-9 parts of stabilizer, 0.5-1 part of lubricant and 0.2-1 part of antioxidant; the rare earth synergistic flame retardant is prepared by compounding modified attapulgite loaded with a nano rare earth compound and an intumescent flame retardant according to the mass ratio of 1-5;

the nano rare earth compound is selected from one or more of nano cerium oxide, nano lanthanum oxide, nano yttrium oxide, nano praseodymium oxide or nano rubidium oxide, and the particle size of the nano rare earth compound is less than or equal to 400 nm;

the intumescent flame retardant is formed by mixing ammonium polyphosphate and trihydroxyethyl isocyanurate according to the mass ratio of 4-9:1; the preparation method of the modified attapulgite loaded with the nano rare earth compound comprises the following steps: washing the attapulgite soaked by the hydrogen peroxide solution to be neutral by using deionized water, and drying; adding the nano rare earth compound, the silane coupling agent and the attapulgite into deionized water, stirring and reacting for 1-2 hours at the temperature of 80-90 ℃, centrifugally separating, retaining solids, washing with absolute ethyl alcohol for a plurality of times respectively, drying in vacuum, grinding, and sieving with a 500-mesh sieve.

2. The low-smoke halogen-free cable material containing the rare-earth synergistic flame retardant as claimed in claim 1, wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content of 12-25wt%, a melt index of 8-20 g/10min, a test melt temperature of 190 ℃ and a weight of 2.16 kg.

3. The low-smoke halogen-free cable material containing the rare-earth synergistic flame retardant as claimed in claim 1, wherein the fluorosilicone rubber has a tensile strength of 72 h which is not more than 35% less than its initial tensile strength at 225 ℃, and an elongation at break which is not more than 30% less than its initial elongation at break.

4. The low-smoke halogen-free cable material containing the rare earth synergistic flame retardant is characterized in that the softening point of the terpene resin is 100-130 ℃, and the acid value of the terpene resin is less than 1.0 mg KOH/g.

5. The low-smoke halogen-free cable material containing the rare-earth synergistic flame retardant as claimed in claim 1, wherein the polyamide resin is selected from one or two of nylon 6 or nylon 66.

6. The low-smoke halogen-free cable material containing the rare earth synergistic flame retardant as claimed in claim 1, wherein the addition amount of the nano rare earth compound is 20-60 wt%, the addition amount of the silane coupling agent is 2-10 wt%, and the mass concentration of the attapulgite in deionized water is 1.0-1.8 g/mL, based on the mass of the dried attapulgite.

7. The low smoke zero halogen cable material containing rare earth synergistic flame retardant as claimed in claim 1, wherein the compatibilizer is maleic anhydride grafted EVA, the reinforcing agent is fumed silica, the stabilizer is an organotin heat stabilizer, the lubricant is at least one selected from natural paraffin, liquid paraffin, microcrystalline paraffin, polyethylene wax, butyl stearate, oleamide, ethylene bis stearamide and silicone powder, and the antioxidant is at least one selected from 2,6-di-tert-butyl-p-cresol, beta (3,5 di-tert-butyl-4-hydroxyphenyl) octadecyl propionate, 1,1,3 tris (2-methyl-4 hydroxy-5 tert-butylphenyl) butane, 3534 ' -methylene bis (4-ethyl-6 tert-butylphenol), 1,3,5-tris (3,5-butyl-4-hydroxybenzyl) trimethylbenzene, 2,2' -methylene bis (4-methyl-6-tert-butylphenol) and 4,4' -octyldiphenylamine.

8. The preparation method of the low-smoke halogen-free cable material containing the rare earth synergistic flame retardant as claimed in any one of claims 1 to 7, characterized in that the method comprises the following steps:

step 1): uniformly stirring and mixing ethylene-vinyl acetate copolymer, polyamide resin, compatilizer, rare earth synergistic flame retardant, stabilizer, lubricant and antioxidant in parts by weight at a high speed to prepare premix A;

step 2): uniformly stirring and mixing the fluorosilicone rubber, the terpene resin and the reinforcing agent at a high speed according to the parts by weight to prepare a premix B;

and step 3): adding the premix A into a double-screw extruder from a main feed inlet, adding the premix B into the double-screw extruder through a side feed inlet, and cooling, drying and granulating after extrusion to obtain the low-smoke halogen-free cable material.