An ammonium polyphosphate-based halogen-free flame retardant and halogen-free flame-retardant radiation-crosslinked polyolefin cable material

Abstract

This invention belongs to the field of composite material technology, specifically relating to an ammonium polyphosphate-based halogen-free flame retardant and a halogen-free flame-retardant irradiated cross-linked polyolefin cable material. The ammonium polyphosphate-based halogen-free flame retardant is obtained by reacting ammonium polyphosphate with an amino compound. The halogen-free flame-retardant irradiated cross-linked polyolefin cable material comprises the following components in parts by weight: 90-100 parts polyolefin resin, 5-10 parts modified melamine flame retardant, 10-15 parts modified piperazine pyrophosphate flame retardant, 10-30 parts ammonium polyphosphate-based flame retardant, 4-8 parts compatibilizer, 0.5-2.0 parts antioxidant, and 0.5-2.0 parts dispersant. Grafting the ammonium polyphosphate-based flame retardant onto the polyolefin resin and compounding it with the modified melamine flame retardant and modified piperazine pyrophosphate flame retardant improves the compatibility between the flame retardant and the matrix resin, enhances the flame-retardant performance, and ultimately yields a halogen-free flame-retardant irradiated cross-linked polyolefin cable material with good flame-retardant and mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to an ammonium polyphosphate-based halogen-free flame retardant and a halogen-free flame retardant irradiated cross-linked polyolefin cable material. Background Technology

[0002] With the rapid pace of urbanization, the size of cities and the number of urban populations are increasing rapidly. Once a fire breaks out in a building, evacuation and rescue operations become extremely difficult. Therefore, flame-retardant materials are preferred in the design and construction process to reduce safety hazards during fires. Flame-retardant cables have also become the primary choice for cabling in public places. Adding halogenated flame retardants or using polyvinyl chloride and antimony-based flame retardants can achieve flame retardancy. However, halogenated flame retardants produce large amounts of harmful gases during combustion, posing a hazard to surrounding electrical equipment and rescue personnel, hindering firefighting and rescue efforts, and leading to serious "secondary hazards."

[0003] With increased environmental awareness and the promulgation of relevant laws, the use of halogen-containing flame-retardant cables has significantly decreased, and their use is now prohibited in the construction of critical infrastructure. Low-smoke flame-retardant wires and cables can be made by adding inorganic hydroxide flame retardants such as aluminum hydroxide and magnesium hydroxide to the insulation and sheathing materials. Chinese patent (patent publication number: CN106280034A) discloses a method for preparing halogen-free flame-retardant cable materials. The flame retardant is composed of one or more of hydroxides, organic hypophosphite flame retardants, and melamine compounds. Achieving high flame retardancy requires the addition of a large amount of flame retardant. Commonly used flame retardants contain many polar groups on their surface, while the resin matrix is ​​mostly composed of non-polar molecules, leading to poor compatibility and significantly reducing the mechanical and flame-retardant properties of the composite material. The compatibility and dispersion of flame retardants in the resin matrix has also been a significant challenge. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned technical problems by providing a halogen-free flame retardant based on ammonium polyphosphate, which has good compatibility with resin matrices and can yield composite materials with good flame retardant properties.

[0005] The ammonium polyphosphate-based halogen-free flame retardant in the technical solution of this invention is obtained by reacting ammonium polyphosphate with an amino compound.

[0006] Furthermore, the amino compound is a long carbon chain compound containing terminal alkenyl and amino groups in its molecular chain, and a benzene ring in its main chain. Examples include one or more of p-butenylaniline and 2,6-di-n-butenyl-1-aniline.

[0007] The alkenyl and benzene ring structures in amino compounds can introduce double bonds and benzene rings into ammonium polyphosphate-based halogen-free flame retardants. Double bonds can provide active sites and improve the compatibility of ammonium polyphosphate-based flame retardants with resin matrices. Benzene ring structures can improve the rigidity of resin matrices and enhance their mechanical properties. At the same time, they have a good char-forming effect, which can promote the dehydration and carbonization of organic surfaces, producing a condensed phase barrier layer. After combustion, a ceramic layer is easily formed on the surface, improving the strength and flame retardant properties of the melt.

[0008] Furthermore, the number of carbon atoms in amino compounds is 10 to 15.

[0009] The preparation method of the above-mentioned ammonium polyphosphate-based halogen-free flame retardant includes adding ammonium polyphosphate and an amino compound to a mixture of water and ethanol under a nitrogen atmosphere, heating and reacting, cooling, concentrating the resulting mixture under reduced pressure, washing, filtering, vacuum drying, and then grinding.

[0010] Furthermore, the mass ratio of ammonium polyphosphate to amino compound is 1.0:1.5 to 2.5.

[0011] Furthermore, the volume ratio of water to ethanol is 3.0–5.0:1.0.

[0012] Furthermore, the heating reaction is carried out at a temperature of 50–70°C for a time of 0.5–1.5 h.

[0013] Furthermore, the vacuum drying temperature is 70–90°C, and the time is 10–14 hours.

[0014] The present invention also provides a halogen-free flame-retardant irradiated cross-linked polyolefin cable material, comprising the following components in parts by weight: 90-100 parts of polyolefin resin, 5-10 parts of modified melamine flame retardant, 10-15 parts of modified piperazine pyrophosphate flame retardant, 10-30 parts of the above-mentioned ammonium polyphosphate flame retardant, 4-8 parts of compatibilizer, 0.5-2.0 parts of antioxidant, and 0.5-2.0 parts of dispersant.

[0015] Ammonium polyphosphate flame retardants contain long carbon chain structures, which have a compatibilizing effect on modified melamine flame retardants and modified piperazine pyrophosphate flame retardants, thus facilitating the uniform dispersion of these flame retardants and other additives in polyolefin resins. The benzene ring structure in ammonium polyphosphate flame retardants exhibits strong rigidity and char-forming properties. The gases produced by the high-temperature decomposition of modified melamine flame retardants can dilute flammable gases. When used in conjunction with the synergistically char-forming modified piperazine pyrophosphate flame retardants, both exhibit excellent flame-retardant effects.

[0016] Further, the polyolefin resin is one or more selected from polyethylene resin, polypropylene resin, ethylene copolymer, and propylene copolymer. Preferably, the polyolefin resin is a mixture of polyethylene resin and ethylene-vinyl acetate copolymer in a mass ratio of 1.0:0.2 to 0.4.

[0017] Furthermore, during the preparation of the above-mentioned halogen-free flame-retardant irradiated cross-linked polyolefin cable material, 0.5 to 2.0% by weight of polyolefin resin initiator is added.

[0018] Furthermore, the initiator is a peroxide initiator, such as one or more of benzoyl peroxide, benzoyl tert-butyl peroxide, methyl ethyl ketone peroxide, and dicumyl peroxide (DCP).

[0019] Furthermore, the modified melamine flame retardant and the modified piperazine pyrophosphate flame retardant are obtained by stirring the melamine flame retardant or piperazine pyrophosphate flame retardant at high speed of 500-600 rpm, while simultaneously spraying in 1.5-2.0% by weight of silane coupling agent of the melamine flame retardant or piperazine pyrophosphate flame retardant, and then heating to 95-100℃ and stirring for 3-5 minutes.

[0020] Modifying melamine-based flame retardants and piperazine pyrophosphate flame retardants using silane coupling agents and introducing non-polar groups on their surfaces can improve the compatibility between the flame retardants and the resin matrix, enhance interfacial bonding, and promote uniform dispersion of the flame retardants in the system.

[0021] Furthermore, the silane coupling agent is one or more of KH550, KH560, and KH570.

[0022] Furthermore, the compatibilizer is one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, polyethylene-grafted acrylonitrile, and polypropylene-grafted acrylonitrile.

[0023] Further, the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 164, antioxidant DNP, and antioxidant TNP. Preferably, antioxidant 1010 and antioxidant 168 are mixed in a mass ratio of 1.0:0.3 to 0.5.

[0024] Furthermore, the dispersant is a low-molecular-weight wax dispersant, such as one or more of polyethylene wax, oxidized polyethylene wax, and polyethylene glycol.

[0025] The preparation method of the above-mentioned halogen-free flame-retardant irradiated cross-linked polyolefin cable material includes the following steps:

[0026] (1) The ammonium polyphosphate flame retardant, initiator and polyolefin resin are mixed in an intensive manner and extruded and granulated to obtain intrinsic flame retardant polyolefin resin.

[0027] (2) The modified melamine flame retardant, the modified piperazine pyrophosphate flame retardant, the compatibilizer, the antioxidant, the dispersant and the intrinsic flame retardant polyolefin resin are mixed and extruded to obtain the cable, and then irradiated for crosslinking.

[0028] First, during the intensive mixing process, a grafting reaction is carried out on the polyolefin resin to graft an ammonium polyphosphate flame retardant. The double bonds in the ammonium polyphosphate flame retardant provide grafting sites for the flame retardant onto the polyolefin resin, improving the compatibility between the flame retardant and the resin matrix. Furthermore, the ammonium polyphosphate flame retardant molecule contains a large number of double bonds, exhibiting high reactivity. When combined with an initiator, it can act as a pre-crosslinker during extrusion, effectively reducing the irradiation intensity during the crosslinking process and increasing the crosslinking density.

[0029] Furthermore, in step (1), the mixing temperature is 100-120℃ and the time is 3-8 minutes.

[0030] Furthermore, in step (2), the irradiation crosslinking is performed using Co 60 Gamma rays are emitted in a nitrogen atmosphere, with an irradiation dose of 6–18 Mrad.

[0031] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0032] (1) In this invention, ammonium polyphosphate flame retardant is grafted onto polyolefin resin and compounded with modified melamine flame retardant and modified piperazine pyrophosphate flame retardant to improve the compatibility between flame retardant and matrix resin and improve flame retardant performance. Combined with radiation crosslinking, halogen-free flame retardant radiation crosslinked polyolefin cable material with high flame retardant performance and mechanical properties is obtained.

[0033] (2) The double bonds in the ammonium polyphosphate flame retardant provide active sites for the grafting of the ammonium polyphosphate flame retardant onto polyolefin resins, thereby improving the compatibility of the ammonium polyphosphate flame retardant with the resin matrix.

[0034] (3) The ammonium polyphosphate flame retardant contains a long carbon chain structure. One end of APP is polar and has a compatibilizing effect on other flame retardants, which is conducive to the uniform dispersion of each component, so as to obtain a halogen-free flame retardant irradiated cross-linked polyolefin cable material with a uniform system and stable performance.

[0035] (4) The large number of double bonds in the molecular structure of ammonium polyphosphate flame retardant have high reactivity. When combined with the initiator, they can play a pre-crosslinking role in the extrusion process, effectively reducing the irradiation intensity during the irradiation crosslinking process and increasing the crosslinking density.

[0036] (5) Ammonium polyphosphate flame retardants contain benzene ring structures and have a strong carbonization ability. At the same time, under high temperature conditions, they can generate polyphosphoric acid or metaphosphoric acid through dehydration, which promotes the dehydration and carbonization of organic matter surfaces, producing a condensed phase barrier layer. After combustion, a ceramic layer easily appears on the surface, which increases the melt strength. Modified melamine flame retardants can dilute combustible gases. When used together with modified piperazine flame retardants, they have a good synergistic flame retardant effect. Detailed Implementation

[0037] The technical solution of the present invention will be further described and illustrated below through specific embodiments. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the present invention. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0038] Example 1

[0039] The preparation method of halogen-free flame-retardant irradiated cross-linked polyolefin cable material in this embodiment includes the following steps:

[0040] (1) Under a nitrogen atmosphere, 100g of ammonium polyphosphate and 200g of 2,6-di-n-butylenyl-1-aniline (CAS No. 868615-56-9) were added to a flask containing a mixture of 800ml water and 200ml ethanol. The mixture was heated at 60°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain an ammonium polyphosphate flame retardant.

[0041] (2) Melamine flame retardant is stirred at high speed of 500 rpm, and KH560 of 2.0% by mass of melamine flame retardant is sprayed in at the same time. The mixture is heated to 100℃ and stirred for 5 min to obtain modified melamine flame retardant. Piperazine pyrophosphate flame retardant is stirred at high speed of 500 rpm, and KH560 of 2.0% by mass of piperazine pyrophosphate flame retardant is sprayed in at the same time. The mixture is heated to 100℃ and stirred for 5 min to obtain modified piperazine pyrophosphate flame retardant.

[0042] (3) Mix 30 parts of ammonium polyphosphate flame retardant, 1.0 part of DCP and 80 parts of linear low-density polyethylene at 110°C for 5 min, and then extrude and granulate to obtain intrinsic flame retardant polyolefin resin.

[0043] (4) Mix 8 parts of modified melamine flame retardant, 12 parts of modified piperazine pyrophosphate flame retardant, 5 parts of maleic anhydride grafted polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.5 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) and add them to the cable extruder. Extrude to obtain the cable. Then place the sample in a glass bottle and seal it with nitrogen gas. Irradiate and crosslink it with Co60 gamma rays with an irradiation dose of 14Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0044] Example 2

[0045] The preparation method of halogen-free flame-retardant irradiated cross-linked polyolefin cable material in this embodiment includes the following steps:

[0046] (1) Under a nitrogen atmosphere, 100g of ammonium polyphosphate and 200g of p-butenylaniline (CAS No. 1314936-78-1) were added to a flask containing a mixture of 700ml water and 200ml ethanol. The mixture was heated at 65°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 14h and then ground to obtain an ammonium polyphosphate flame retardant.

[0047] (2) Melamine flame retardant is stirred at high speed of 500 rpm, and KH560 of 2.0% by mass of melamine flame retardant is sprayed in at the same time. The mixture is heated to 100℃ and stirred for 5 min to obtain modified melamine flame retardant. Piperazine pyrophosphate flame retardant is stirred at high speed of 500 rpm, and KH560 of 2.0% by mass of piperazine pyrophosphate flame retardant is sprayed in at the same time. The mixture is heated to 100℃ and stirred for 5 min to obtain modified piperazine pyrophosphate flame retardant.

[0048] (3) Mix 30 parts of ammonium polyphosphate flame retardant, 1.0 part of DCP and 80 parts of linear low-density polyethylene at 115°C for 5 min, and then extrude and granulate to obtain intrinsic flame retardant polyolefin resin.

[0049] (4) Mix 8 parts of modified melamine flame retardant, 12 parts of modified piperazine pyrophosphate flame retardant, 5 parts of maleic anhydride grafted polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.5 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) and add them to a cable extruder. Extrude the cable and place the sample in a glass bottle and seal it with nitrogen gas. Then, irradiate and crosslink it with Co60 gamma rays at an irradiation dose of 14Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0050] Example 3

[0051] The preparation method of halogen-free flame-retardant irradiated cross-linked polyolefin cable material in this embodiment includes the following steps:

[0052] (1) Under a nitrogen atmosphere, 100g of ammonium polyphosphate and 220g of 2,6-di-n-butenyl-1-aniline were added to a flask containing a mixture of 700ml of water and 200ml of ethanol. The mixture was heated at 65°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 14h and then ground to obtain an ammonium polyphosphate flame retardant.

[0053] (2) Melamine flame retardant was stirred at high speed at 550 rpm, and KH550 with a mass of 2.0% of melamine flame retardant was sprayed in at the same time. The mixture was heated to 95℃ and stirred for 8 min to obtain modified melamine flame retardant. Piperazine pyrophosphate flame retardant was stirred at high speed at 550 rpm, and KH560 with a mass of 1.8% of piperazine pyrophosphate flame retardant was sprayed in at the same time. The mixture was heated to 100℃ and stirred for 5 min to obtain modified piperazine pyrophosphate flame retardant.

[0054] (3) Mix 30 parts of ammonium polyphosphate flame retardant, 1.0 part of benzoyl tert-butyl peroxide and 75 parts of linear low-density polyethylene at 110°C for 5 min, and then extrude and granulate to obtain intrinsic flame retardant polyolefin resin.

[0055] (4) Mix 9 parts of modified melamine flame retardant, 12 parts of modified piperazine pyrophosphate flame retardant, 5 parts of maleic anhydride grafted polyethylene, 25 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.2 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) and add them to the cable extruder. Extrude to obtain the cable. Then place the sample in a glass bottle and seal it with nitrogen gas. Irradiate and crosslink it with Co60 gamma rays with an irradiation dose of 12Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0056] Example 4

[0057] The preparation method of halogen-free flame-retardant irradiated cross-linked polyolefin cable material in this embodiment includes the following steps:

[0058] (1) Under a nitrogen atmosphere, 120g of ammonium polyphosphate and 200g of 2,6-di-n-butylenyl-1-aniline were added to a flask containing a mixture of 800ml of water and 180ml of ethanol. The mixture was heated at 70°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 85°C for 12h and then ground to obtain an ammonium polyphosphate flame retardant.

[0059] (2) Melamine flame retardant was stirred at high speed at 600 rpm, and KH560 with a mass of 1.8% of melamine flame retardant was sprayed in at the same time. The mixture was heated to 100℃ and stirred for 5 min to obtain modified melamine flame retardant. Piperazine pyrophosphate flame retardant was stirred at high speed at 600 rpm, and KH550 with a mass of 2.0% of piperazine pyrophosphate flame retardant was sprayed in at the same time. The mixture was heated to 95℃ and stirred for 8 min to obtain modified piperazine pyrophosphate flame retardant.

[0060] (3) 25 parts of ammonium polyphosphate flame retardant, 1.2 parts of DCP and 65 parts of linear low-density polyethylene were mixed at 110°C for 5 min and then extruded and granulated to obtain intrinsic flame retardant polyolefin resin.

[0061] (4) Mix 8 parts of modified melamine flame retardant, 14 parts of modified piperazine pyrophosphate flame retardant, 6 parts of maleic anhydride grafted polyethylene, 35 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.15 parts of antioxidant 168, 1.0 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) and add them to a cable extruder. Extrude the cable and place the sample in a glass bottle and seal it with nitrogen gas. Then, irradiate and crosslink it with Co60 gamma rays at an irradiation dose of 14Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0062] Example 5

[0063] The difference between this embodiment and embodiment 1 is only that in step (3), 30 parts of ammonium polyphosphate flame retardant, 1.0 parts of DCP and 100 parts of linear low-density polyethylene are mixed at 110°C for 5 minutes and extruded and granulated to obtain intrinsic flame-retardant polyolefin resin; in step (4), 8 parts of modified melamine flame retardant, 12 parts of modified piperazine pyrophosphate flame retardant, 5 parts of maleic anhydride grafted polyethylene, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.5 parts of polyethylene wax and the intrinsic flame-retardant polyolefin resin obtained in step (1) are mixed and added to a cable extruder, and the cable is extruded. The sample is then placed in a glass bottle and sealed with nitrogen gas. It is then crosslinked by Co60 gamma rays with an irradiation dose of 14 Mrad to obtain halogen-free flame-retardant irradiated crosslinked polyolefin cable material.

[0064] Example 6

[0065] The preparation method of halogen-free flame-retardant irradiated cross-linked polyolefin cable material in this embodiment includes the following steps:

[0066] (1) Under a nitrogen atmosphere, 100g of ammonium polyphosphate and 200g of 2,6-di-n-butylenyl-1-aniline were added to a flask containing a mixture of 800ml of water and 200ml of ethanol. The mixture was heated at 60°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain an ammonium polyphosphate flame retardant.

[0067] (2) 30 parts of ammonium polyphosphate flame retardant, 1.0 part of DCP and 80 parts of linear low-density polyethylene were mixed at 110°C for 5 min and then extruded and granulated to obtain intrinsic flame retardant polyolefin resin.

[0068] (3) Mix 8 parts of melamine flame retardant, 12 parts of piperazine pyrophosphate flame retardant, 5 parts of maleic anhydride grafted polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.5 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) and add them to a cable extruder. Extrude the cable and place the sample in a glass bottle and seal it with nitrogen gas. Then, irradiate and crosslink it with Co60 gamma rays at an irradiation dose of 14Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0069] Example 7

[0070] The preparation method of halogen-free flame-retardant irradiated cross-linked polyolefin cable material in this embodiment includes the following steps:

[0071] (1) Under a nitrogen atmosphere, 100g of ammonium polyphosphate and 200g of 2,6-di-n-butylenyl-1-aniline were added to a flask containing a mixture of 800ml of water and 200ml of ethanol. The mixture was heated at 60°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain an ammonium polyphosphate flame retardant.

[0072] (2) The piperazine pyrophosphate flame retardant was stirred at high speed at 500 rpm, and 2.0% of the mass of the piperazine pyrophosphate flame retardant KH560 was sprayed in at the same time. The temperature was raised to 100℃ and stirred for 5 min to obtain the modified piperazine pyrophosphate flame retardant.

[0073] (3) Mix 30 parts of ammonium polyphosphate flame retardant, 1.0 part of DCP and 80 parts of linear low-density polyethylene at 110°C for 5 min, and then extrude and granulate to obtain intrinsic flame retardant polyolefin resin.

[0074] (4) 20 parts of modified piperazine pyrophosphate flame retardant, 5 parts of maleic anhydride grafted polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.5 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) are mixed and added to a cable extruder. The cable is extruded and then the sample is placed in a glass bottle and sealed with nitrogen gas. It is then crosslinked by Co60 gamma rays with an irradiation dose of 14Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0075] Example 8

[0076] The preparation method of halogen-free flame-retardant irradiated cross-linked polyolefin cable material in this embodiment includes the following steps:

[0077] (1) Under a nitrogen atmosphere, 100g of ammonium polyphosphate and 200g of 2,6-di-n-butylenyl-1-aniline were added to a flask containing a mixture of 800ml of water and 200ml of ethanol. The mixture was heated at 60°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain an ammonium polyphosphate flame retardant.

[0078] (2) Melamine flame retardant is stirred at high speed at 500 rpm, and KH560 of 2.0% by mass of melamine flame retardant is sprayed in at the same time. The temperature is raised to 100℃ and stirred for 5 min to obtain modified melamine flame retardant.

[0079] (3) Mix 30 parts of ammonium polyphosphate flame retardant, 1.0 part of DCP and 80 parts of linear low-density polyethylene at 110°C for 5 min, and then extrude and granulate to obtain intrinsic flame retardant polyolefin resin.

[0080] (4) Mix 20 parts of modified melamine flame retardant, 5 parts of maleic anhydride grafted polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.5 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) and add them to a cable extruder. Extrude the cable and place the sample in a glass bottle and seal it with nitrogen. Then, irradiate and crosslink it with Co60 gamma rays at a dose of 14 Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0081] Comparative Example 1

[0082] The only difference between this comparative example and Example 1 is that in step (1), 60g of ammonium polyphosphate and 240g of 2,6-di-n-butylenyl-1-aniline were added to a flask containing a mixture of 800ml of water and 200ml of ethanol under a nitrogen atmosphere. The mixture was heated at 60°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain an ammonium polyphosphate-based flame retardant.

[0083] Comparative Example 2

[0084] The only difference between this comparative example and Example 1 is that in step (1), 150g of ammonium polyphosphate and 150g of 2,6-di-n-butenyl-1-aniline were added to a flask containing a mixture of 800ml of water and 200ml of ethanol under a nitrogen atmosphere. The mixture was heated at 60°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain an ammonium polyphosphate-based flame retardant.

[0085] Comparative Example 3

[0086] The only difference between this comparative example and Example 1 is that in step (3), 5 parts of ammonium polyphosphate flame retardant, 1.0 part of DCP and 80 parts of linear low-density polyethylene are mixed at 110°C for 5 minutes and then extruded and granulated to obtain intrinsic flame-retardant polyolefin resin.

[0087] Comparative Example 4

[0088] The only difference between this comparative example and Example 1 is that in step (3), 50 parts of ammonium polyphosphate flame retardant, 1.0 part of DCP and 80 parts of linear low-density polyethylene are mixed at 110°C for 5 minutes and then extruded and granulated to obtain intrinsic flame-retardant polyolefin resin.

[0089] Comparative Example 5

[0090] The preparation method of this comparative example of halogen-free flame-retardant irradiated cross-linked polyolefin cable material includes the following steps:

[0091] (1) Melamine flame retardant is stirred at high speed at 500 rpm, and KH560 with a mass of 2.0% of melamine flame retardant is sprayed in at the same time. The mixture is heated to 100℃ and stirred for 5 min to obtain modified melamine flame retardant. Piperazine pyrophosphate flame retardant is stirred at high speed at 500 rpm, and KH560 with a mass of 2.0% of piperazine pyrophosphate flame retardant is sprayed in at the same time. The mixture is heated to 100℃ and stirred for 5 min to obtain modified piperazine pyrophosphate flame retardant.

[0092] (2) Mix 30 parts of ammonium polyphosphate, 1.0 part of DCP and 80 parts of linear low-density polyethylene at 110°C for 5 min, and then extrude and granulate to obtain intrinsic flame-retardant polyolefin resin.

[0093] (3) Mix 8 parts of modified melamine flame retardant, 12 parts of modified piperazine pyrophosphate flame retardant, 5 parts of maleic anhydride grafted polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.5 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) and add them to the cable extruder. Extrude to obtain the cable. Then place the sample in a glass bottle and seal it with nitrogen gas. Irradiate and crosslink it with Co60 gamma rays with an irradiation dose of 14Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0094] Comparative Example 6

[0095] The preparation method of this comparative example of halogen-free flame-retardant irradiated cross-linked polyolefin cable material includes the following steps:

[0096] (1) Under a nitrogen atmosphere, 100g of ammonium polyphosphate and 150g of 2,6-di-n-butenyl-1-aniline were added to a flask containing a mixture of 800ml of water and 200ml of ethanol. The mixture was heated at 60°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain an ammonium polyphosphate flame retardant.

[0097] (2) Melamine flame retardant is stirred at high speed of 500 rpm, and KH560 of 2.0% by mass of melamine flame retardant is sprayed in at the same time. The mixture is heated to 100℃ and stirred for 5 min to obtain modified melamine flame retardant. Piperazine pyrophosphate flame retardant is stirred at high speed of 500 rpm, and KH560 of 2.0% by mass of piperazine pyrophosphate flame retardant is sprayed in at the same time. The mixture is heated to 100℃ and stirred for 5 min to obtain modified piperazine pyrophosphate flame retardant.

[0098] (3) Mix 30 parts of ammonium polyphosphate flame retardant, 1.0 part of DCP, 80 parts of linear low-density polyethylene, 8 parts of modified melamine flame retardant, 12 parts of modified piperazine pyrophosphate flame retardant, 5 parts of maleic anhydride grafted polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 0.4 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 1.5 parts of polyethylene wax and the intrinsic flame retardant polyolefin resin obtained in step (1) and add them to a cable extruder. Extrude the cable and place the sample in a glass bottle and seal it with nitrogen gas. Then, irradiate and crosslink it with Co60 gamma rays at an irradiation dose of 14Mrad to obtain halogen-free flame retardant irradiated crosslinked polyolefin cable material.

[0099] Comparative Example 7

[0100] The only difference between this comparative example and Example 1 is that in step (1), 100g of ammonium polyphosphate and 200g of 4-vinylaniline (CAS No. 1520-21-4) were added to a flask containing a mixture of 800ml of water and 200ml of ethanol under a nitrogen atmosphere, heated at 60°C for 1.0h, and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain an ammonium polyphosphate-based flame retardant.

[0101] Comparative Example 8

[0102] The only difference between this comparative example and Example 1 is that in step (1), 100g of ammonium polyphosphate and 200g of 1,6-heptadien-4-amine (CAS No. 83234-92-8) were added to a flask containing a mixture of 800ml of water and 200ml of ethanol under a nitrogen atmosphere. The mixture was heated at 60°C for 1.0h and then cooled to room temperature. The resulting mixture was concentrated under reduced pressure and washed with ethanol. After filtration, the resulting solid was dried under vacuum at 80°C for 12h and then ground to obtain the ammonium polyphosphate-based flame retardant.

[0103] The mechanical properties, flame retardant properties, and crosslinking degree of the halogen-free flame-retardant irradiated crosslinked polyolefin cable materials obtained in the above examples and comparative examples were tested. The crosslinking degree was characterized by gel content. The samples were soaked in toluene at 100°C for 24 hours, dried, and weighed at constant weight. The mass of the undissolved sample was measured. The gel content, i.e., the crosslinking degree, was expressed as the percentage of the mass of the undissolved sample to the total mass of the sample. The test results are shown in Table 1.

[0104] Table 1 Performance Test Data of Halogen-Free Flame-Retardant Irradiated Crosslinked Polyolefin Cable Material

[0105] Tensile strength MPa Elongation at break % crosslinking degree Limiting oxygen index UL-94 Example 1 16.4 299％ 84.4％ 31.6％ V-0 Example 2 16.2 321％ 82.9％ 31.0％ V-0 Example 3 16.8 292％ 85.3％ 31.2％ V-0 Example 4 16.1 283％ 83.2％ 30.9％ V-0 Example 5 15.3 198％ 74.2％ 28.7％ V-0 Example 6 14.1 252％ 83.0％ 27.8％ V-1 Example 7 14.6 266％ 83.9％ 27.3％ V-1 Example 8 14.4 263％ 83.2％ 26.7％ V-1 Comparative Example 1 13.2 183％ 74.8％ 25.8％ V-2 Comparative Example 2 12.7 210％ 72.5％ 28.4％ V-1 Comparative Example 3 12.3 265％ 79.6％ 24.7％ V-2 Comparative Example 4 13.2 166％ 84.1％ 30.9％ V-0 Comparative Example 5 10.7 160％ 68.3％ 26.2％ V-2 Comparative Example 6 13.5 231％ 79.6％ 28.3％ V-1 Comparative Example 7 13.6 216％ 77.9％ 28.1％ V-1 Comparative Example 8 12.7 252％ 82.3％ 26.4％ V-2

[0106] The halogen-free flame-retardant irradiated cross-linked polyolefin cable materials obtained in Examples 1-4 exhibit good mechanical and flame-retardant properties. In Example 5, the matrix resin of the halogen-free flame-retardant irradiated cross-linked polyolefin cable material does not contain ethylene-vinyl acetate copolymer, thus the toughening effect of the ethylene-vinyl acetate copolymer disappears. Simultaneously, the compatibility between the flame-retardant filler and the matrix deteriorates, resulting in reduced cross-linking density and degree after irradiation. Consequently, the toughness and strength of the resulting halogen-free flame-retardant irradiated cross-linked polyolefin cable material deteriorate. In Example 6, the melamine-based flame retardant and piperazine pyrophosphate flame retardant used are not modified, leading to poor compatibility between the flame retardant and the resin matrix, and decreased system homogeneity. Consequently, the mechanical and flame-retardant properties of the resulting halogen-free flame-retardant irradiated cross-linked polyolefin cable material deteriorate. In Example 7, no modified melamine was added. Amine flame retardants reduce the amount of gas produced during combustion, resulting in insufficient carbon layer expansion, increased combustible gas concentration, and decreased flame retardant performance. In Example 8, without the addition of modified piperazine pyrophosphate flame retardant, the density of the carbon layer was severely weakened, leading to a sharp decline in flame retardant performance. In Comparative Example 1, when preparing the ammonium polyphosphate-based flame retardant, an excess of 2,6-di-n-butyl-1-aniline and a small amount of ammonium polyphosphate were used. Due to steric hindrance and other effects, the ammonium polyphosphate could not continuously react with the excess 2,6-di-n-butyl-1-aniline. The system simultaneously contained a small amount of double-bonded ammonium polyphosphate groups and residual 2,6-di-n-butyl-1-aniline, which deteriorated the flame retardant and mechanical properties of the halogen-free flame-retardant irradiated cross-linked polyolefin cable material. Comparative Example 2 prepared ammonium polyphosphate... The first example uses a small amount of 2,6-di-n-butenyl-1-aniline and an excess of ammonium polyphosphate as the flame retardant. The reduced double bond content in the ammonium polyphosphate flame retardant leads to decreased crosslinking density and degree of crosslinking, resulting in poorer mechanical and flame-retardant properties of the resulting halogen-free flame-retardant irradiated crosslinked polyolefin cable material. The second example, Comparative Example 3, uses a small amount of ammonium polyphosphate flame retardant, reducing double bonds and crosslinking degree, further deteriorating the mechanical and flame-retardant properties of the resulting halogen-free flame-retardant irradiated crosslinked polyolefin cable material. The third example, Comparative Example 4, uses an excess of ammonium polyphosphate flame retardant, which can cause uneven dispersion of the flame retardant in the system, leading to decreased mechanical properties and weakened flame-retardant performance. The fifth example, Comparative Example 5, prepares a halogen-free flame retardant... Irradiated cross-linked polyolefin cable materials do not use ammonium polyphosphate-based flame retardants, but instead use ammonium polyphosphate. This reduces flame retardant performance. Furthermore, the polar groups on the surface of ammonium polyphosphate lead to agglomeration and uneven dispersion, resulting in a sharp decline in mechanical properties. Comparative Example 6 uses a one-step method to mix the components of halogen-free flame-retardant irradiated cross-linked polyolefin cable material before extrusion. This results in a decrease in the grafting rate of the ammonium polyphosphate-based flame retardant in the matrix resin, a reduction in cross-linking density, and a weakened compatibilizing effect, leading to a simultaneous decrease in both mechanical and flame retardant properties. Comparative Example 7 uses 4-ethyleneaniline to generate ammonium polyphosphate-based flame retardants, resulting in shorter carbon chain lengths, more pronounced steric hindrance, and more difficult grafting. This weakens the compatibilizing effect on the system, leading to a simultaneous decrease in both mechanical and flame retardant properties. Comparative Example 8 uses 1,6-Heptadien-4-amine reacts to form ammonium polyphosphate-based flame retardants. Lacking the benzene ring structure, its rigidity decreases, and its char-forming ability is weakened, resulting in a decline in flame retardant performance.

[0107] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A halogen-free flame-retardant irradiated cross-linked polyolefin cable material, characterized in that, It comprises the following components in parts by weight: 90-100 parts polyolefin resin, 5-10 parts modified melamine flame retardant, 10-15 parts modified piperazine pyrophosphate flame retardant, 10-30 parts ammonium polyphosphate flame retardant, 4-8 parts compatibilizer, 0.5-2.0 parts antioxidant, and 0.5-2.0 parts dispersant; The ammonium polyphosphate-based halogen-free flame retardant is obtained by reacting ammonium polyphosphate with an amino compound; the amino compound is one or both of p-butenylaniline and 2,6-di-n-butenyl-1-aniline.

2. The halogen-free flame-retardant irradiated cross-linked polyolefin cable material according to claim 1, characterized in that, The preparation method of the ammonium polyphosphate-based halogen-free flame retardant includes adding ammonium polyphosphate and an amino compound to a mixture of water and ethanol under a nitrogen atmosphere, heating and reacting, cooling, concentrating the resulting mixture under reduced pressure, washing, filtering, vacuum drying, and then grinding.

3. The halogen-free flame-retardant irradiated cross-linked polyolefin cable material according to claim 1, characterized in that, The mass ratio of ammonium polyphosphate to amino compound in the ammonium polyphosphate-based halogen-free flame retardant is 1.0:1.5~2.

5.

4. The halogen-free flame-retardant irradiated cross-linked polyolefin cable material according to claim 2, characterized in that, The heating reaction is carried out at a temperature of 50~70℃ for 0.5~1.5h.

5. The halogen-free flame-retardant irradiated cross-linked polyolefin cable material according to claim 1, characterized in that, The halogen-free flame-retardant irradiated cross-linked polyolefin cable material is prepared by adding 0.5-2.0% (by weight) of an initiator to the polyolefin resin.

6. The halogen-free flame-retardant irradiated cross-linked polyolefin cable material according to claim 1, characterized in that, Modified melamine flame retardants and modified piperazine pyrophosphate flame retardants are obtained by stirring melamine flame retardants or piperazine pyrophosphate flame retardants at high speed of 500~600 rpm, while simultaneously spraying in 1.5~2.0% by weight of silane coupling agent of melamine flame retardants or piperazine pyrophosphate flame retardants, and then heating to 95~105℃ and stirring for 3~8 minutes.

7. A method for preparing halogen-free flame-retardant irradiated cross-linked polyolefin cable material as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) The ammonium polyphosphate flame retardant, initiator and polyolefin resin are mixed and extruded to obtain intrinsic flame retardant polyolefin resin; (2) Melamine flame retardant, piperazine pyrophosphate flame retardant, compatibilizer, antioxidant, dispersant and intrinsic flame retardant polyolefin resin are mixed and extruded to obtain cable, and then irradiated for crosslinking.