Flame-retardant polyolefin composition, and preparation method therefor and use thereof

Abstract

Provided in the present application are a flame-retardant polyolefin composition, and a preparation method therefor and the use thereof. The flame-retardant polyolefin composition comprises, in parts by weight, 13-22 parts of an ethylene-vinyl acetate copolymer, 1.5-8.5 parts of a linear low-density polyethylene, 8-17 parts of a polyolefin elastomer, 35-55 parts of a flame retardant and 0.5-2.5 parts of an antioxidant. The antioxidant comprises a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant comprises a hindered phenolic antioxidant and an amine antioxidant; and the secondary antioxidant comprises a thioester antioxidant and / or a phosphite antioxidant. In the present application, by means of the compounding of the ethylene-vinyl acetate copolymer, linear low density polyethylene and polyolefin elastomer on the basis of specific contents in combination with the antioxidant having a specific composition, the flame-retardant polyolefin composition has good heat resistance and aging resistance, has a good precipitation resistance effect, and also has good mechanical properties.

Description

A flame-retardant polyolefin composition, its preparation method and application Technical Field

[0001] This application relates to the field of polymer materials technology, such as a flame-retardant polyolefin composition, its preparation method, and its application. Background Technology

[0002] With social development, the use of cables is gradually increasing; as the usage time extends, cables will age, and aged cables are extremely prone to fire; therefore, with the increase in the use of cables, the probability of fires caused by cables is also gradually increasing.

[0003] Related technologies often improve the flame-retardant properties of cables by adding various flame retardants, thereby reducing the probability of fire. However, adding too little flame retardant will not significantly improve the flame-retardant effect, while adding too much will affect the mechanical properties of the cable. In addition, antioxidants are generally added to cable formulations to improve the aging performance of the cable; especially for cable materials with high flame retardant content, more antioxidants are needed. However, with the addition of too many antioxidants, the additives are easily leached out over time, leading to a decrease in the cable's aging resistance and thus affecting its service life.

[0004] Therefore, developing a cable material that is resistant to precipitation, has good heat resistance, is resistant to aging, and also has good mechanical properties is an urgent problem to be solved in this field. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0006] This application provides a flame-retardant polyolefin composition, its preparation method, and its application. The flame-retardant polyolefin composition exhibits excellent heat resistance, aging resistance, and exudation resistance, as well as good mechanical properties.

[0007] In a first aspect, this application provides a flame-retardant polyolefin composition, which, by weight, comprises 13-22 parts of ethylene-vinyl acetate copolymer, 1.5-8.5 parts of linear low-density polyethylene, 8-17 parts of polyolefin elastomer, 35-55 parts of flame retardant, and 0.5-2.5 parts of antioxidant; the antioxidant comprises a primary antioxidant and a secondary antioxidant; the primary antioxidant comprises hindered phenolic antioxidants and amine antioxidants; and the secondary antioxidant comprises thioester antioxidants and / or phosphite antioxidants.

[0008] In this application, a compound of ethylene-vinyl acetate copolymer (EVA), linear low-density polyethylene (LLDPE), and polyolefin elastomer (POE) is used, and the content range of the three is controlled. This can improve the crystallinity of the material, reduce the free volume of the material, and reduce the mobility of molecular chain segments, thereby inhibiting the diffusion and migration of small molecules of additives. The use of antioxidants with specific compositions is beneficial to improving the heat resistance and aging resistance of the material. Furthermore, the use of hindered phenolic and amine antioxidants can also improve the compatibility between antioxidants and polyolefin matrix, further improving the heat and oxygen aging resistance. This makes the material have the performance requirements of resistance to precipitation, high temperature resistance, and aging resistance.

[0009] In this application, 13 to 22 parts of ethylene-vinyl acetate copolymer can be, for example, 13 parts, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, 20.5 parts, 21 parts, 21.5 parts, 22 parts or any range of the above values, and can be selected as 15 to 20 parts.

[0010] In this application, 1.5 to 8.5 parts of linear low-density polyethylene can be, for example, 1.5 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.5 parts, 4.8 parts, 5 parts, 5.2 parts, 5.5 parts, 5.8 parts, 6 parts, 6.2 parts, 6.5 parts, 6.8 parts, 7 parts, 7.2 parts, 7.5 parts, 7.8 parts, 8 parts, 8.2 parts, 8.5 parts, or any range of the above values; it can be selected as 2 to 5 parts.

[0011] In this application, 8 to 17 parts of polyolefin elastomer can be, for example, 8 parts, 8.2 parts, 8.4 parts, 8.6 parts, 8.8 parts, 9 parts, 9.2 parts, 9.4 parts, 9.6 parts, 9.8 parts, 10 parts, 10.2 parts, 10.5 parts, 10.8 parts, 11 parts, 11.2 parts, 11.5 parts, 11.8 parts, 12 parts, 12.2 parts, 12.5 parts, 12.8 parts, 13 parts, 13.2 parts, 13.5 parts, 13.8 parts, 14 parts, 14.2 parts, 14.5 parts, 14.8 parts, 15 parts, 15.2 parts, 15.5 parts, 15.8 parts, 16 parts, 16.2 parts, 16.5 parts, 16.8 parts, 17 parts, or any range of the above values; it can be selected as 10 to 15 parts.

[0012] In this application, 35 to 55 parts of flame retardant can be, for example, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55 parts or any range of the above values; optionally, 40 to 50 parts.

[0013] In this application, the antioxidant is 0.5 to 2.5 parts, for example, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, or any range of the above values; it can be selected as 0.9 to 2 parts.

[0014] In one embodiment, at 190°C and 2.16 kg, the melt index of the ethylene-vinyl acetate copolymer is 0.2~5 g / 10min, for example, it can be 0.3 g / 10min, 0.5 g / 10min, 1 g / 10min, 2 g / 10min, 3 g / 10min, 4 g / 10min, 5 g / 10min or any range between the above values.

[0015] In one embodiment, the mass percentage of vinyl acetate structural units in the ethylene-vinyl acetate copolymer is 10-45%, for example, it can be 10%, 12%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 45%, or any range of the above values; optionally, the mass percentage of vinyl acetate structural units is 18-28%.

[0016] In one embodiment, at 190°C and 2.16 kg, the melt index of the linear low-density polyethylene is 1 to 5 g / 10 min, for example, it can be 1 g / 10 min, 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min or any range between the above values.

[0017] In one embodiment, the linear low-density polyethylene has an elongation at break of ≥600%.

[0018] In one embodiment, the polyolefin elastomer comprises ethylene-butene copolymer and / or ethylene-octene copolymer.

[0019] In this application, the polyolefin elastomer includes a polyolefin elastomer prepared using a metallocene catalyst.

[0020] In one embodiment, at 190°C and 2.16 kg, the melt index of the polyolefin elastomer is 0.3~5 g / 10min, for example, it can be 0.3 g / 10min, 0.5 g / 10min, 1 g / 10min, 2 g / 10min, 3 g / 10min, 4 g / 10min, 5 g / 10min or any range between the above values.

[0021] In one embodiment, the density of the polyolefin elastomer is 0.860~0.915 g / cm³. 3 For example, it can be 0.860 g / cm³ 3 0.861 g / cm 3 0.862 g / cm 3 0.863 g / cm 3 0.864 g / cm 3 0.865 g / cm 3 0.866 g / cm 3 0.867 g / cm 3 0.868 g / cm 3 0.869 g / cm 3 0.870 g / cm 3 0.875 g / cm 3 0.88 g / cm 3 0.885 g / cm 3 0.89 g / cm 3 0.895 g / cm 3 0.9 g / cm 3 0.905 g / cm 3 0.91 g / cm 3 0.915 g / cm 3 Or any value within the range mentioned above; the density of the optional polyolefin elastomer is 0.865~0.905 g / cm³. 3 .

[0022] In this application, the melt flow index is tested according to ASTM D 1238; the VA content can be tested using infrared spectroscopy; and the POE density can be tested according to ASTM D792.

[0023] In one embodiment, the mass ratio of the ethylene-vinyl acetate copolymer, linear low-density polyethylene, and polyolefin elastomer is (2~10):1:(1~8), wherein the specific values ​​of (2~10) can be, for example, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6, 6.2, 6.4, 6.6, 6.8, 7, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.4, 9.6, 9. 8, 10, or any of the above values; specific values ​​in (1~8) can be, for example, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6, 6.2, 6.4, 6.6, 6.8, 7, 7.2, 7.4, 7.6, 7.8, 8, or any of the above values; the mass ratio of ethylene-vinyl acetate copolymer, linear low-density polyethylene, and polyolefin elastomer can be (3~8):1:(2~6).

[0024] In one embodiment, the mass ratio of the flame retardant to the polyolefin elastomer is (2~6):1, for example, it can be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8, 6 or any range of the above values; optionally, the mass ratio of the flame retardant to the polyolefin elastomer is (3~5):1.

[0025] In one embodiment, the flame retardant comprises a halogen-free flame retardant.

[0026] In one embodiment, the flame retardant comprises magnesium hydroxide and / or aluminum hydroxide.

[0027] In one embodiment, the flame retardant is surface-grafted with at least one of an amine compound, a silane, or stearic acid.

[0028] In this application, the amine compounds include, but are not limited to, quaternary ammonium salts and / or amide compounds; the silanes include, but are not limited to, at least one of vinylsilane, aminosilane, epoxysilane or polysilicate.

[0029] In one embodiment, the mass ratio of the primary antioxidant to the secondary antioxidant is (1~3):1, wherein the specific values ​​of (1~3) can be, for example, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3 or any range of the above values; optionally, the mass ratio of the primary antioxidant to the secondary antioxidant is (1.5~2.5):1.

[0030] In one embodiment, the mass ratio of the hindered phenolic antioxidant to the amine antioxidant is (0.5~1.5):1, wherein the specific value of (0.5~1.5) can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or any range between the above values; optionally, the mass ratio of the hindered phenolic antioxidant to the amine antioxidant is (0.9~1.4):1.

[0031] In one embodiment, the hindered phenolic antioxidant includes a first hindered phenolic antioxidant and a second hindered phenolic antioxidant; the absolute value of the difference between the solubility parameter of the first hindered phenolic antioxidant and the solubility parameter of the second hindered phenolic antioxidant is >3.

[0032] In this application, the solubility parameter is the square root of the cohesive energy density of the material, which can be calculated using methods known in the art, such as the summation method of E and V contribution values ​​of Van Krevelen's groups.

[0033] In one embodiment, the mass ratio of the first hindered phenolic antioxidant to the second hindered phenolic antioxidant is (0.5~1.7):1, wherein the specific value of (0.5~1.7) can be, for example, 0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or any range of the above values; optionally, the mass ratio of the first hindered phenolic antioxidant to the second hindered phenolic antioxidant is (0.8~1.3):1.

[0034] In one embodiment, the solubility parameter of the first hindered phenolic antioxidant is 12 to 21, for example, it can be 12, 12.2, 12.4, 12.6, 12.8, 13, 13.2, 13.5, 13.8, 14, 14.2, 14.5, 14.8, 15, 15.2, 15.5, 15.8, 16, 16.2, 16.5, 16.8, 17, 17.2, 17.5, 17.8, 18, 18.2, 18.5, 18.8, 19, 19.2, 19.5, 19.8, 20, 20.2, 20.5, 20.8, 21 or any of the above values; the optional solubility parameter is 16 to 19.

[0035] In one embodiment, the first hindered phenolic antioxidant includes at least one of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), 2,2'-thionylethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (antioxidant 1330), butylated hydroxytoluene (BHT), or N,N′-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (antioxidant 1098).

[0036] In one embodiment, the solubility parameter of the second hindered phenolic antioxidant is 18 to 26, for example, it can be 18, 18.2, 18.5, 18.8, 19, 19.2, 19.5, 19.8, 20, 20.2, 20.5, 20.8, 21, 21.2, 21.5, 21.8, 22, 22.2, 22.5, 22.8, 23, 23.2, 23.5, 23.8, 24, 24.2, 24.5, 24.8, 25, 25.2, 25.5, 25.8, 26 or any of the above values; the optional solubility parameter is 19 to 23.

[0037] In one embodiment, the second hindered phenolic antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), N,N′-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (antioxidant 1098), or 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (antioxidant 1790).

[0038] In one embodiment, the amine antioxidants include 4,4'-bis(phenylisopropyl)diphenylamine (antioxidant 445) and / or N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)propanediamine (antioxidant 1019).

[0039] In one embodiment, the auxiliary antioxidant includes thioester antioxidants and phosphite antioxidants, wherein the mass ratio of the thioester antioxidants to the phosphite antioxidants is (0.5~1.5):1, wherein the specific value of (0.5~1.5) can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or any range between the above values.

[0040] In one embodiment, the thioester antioxidant includes at least one of dioctadecyl thiodipropionate (antioxidant DSTDP), pentaerythritol tetra(3-lauryl thiopropionate) (antioxidant 412S), or didodecyl thiodipropionate; the phosphite antioxidant includes at least one of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, or bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate (antioxidant PEP-36).

[0041] In one embodiment, the flame-retardant polyolefin composition further comprises 4.4 to 15 parts by weight of other additives, for example, 4.4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts or any range of the above values.

[0042] In one embodiment, the other additives include at least one of a compatibilizer, a dispersant, or a colorant.

[0043] In one embodiment, the compatibilizer comprises maleic anhydride-grafted polyethylene.

[0044] In one embodiment, the dispersant comprises an organosiloxane polymer.

[0045] In one embodiment, the colorant comprises carbon black.

[0046] In this application, the carbon black exists in the form of carbon black masterbatch, wherein the carbon black content in the carbon black masterbatch is ≥48% by mass, for example, it can be 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80% or any range between the above values; the resin matrix of the carbon black masterbatch includes polyolefin.

[0047] In one embodiment, the flame-retardant polyolefin composition comprises, by weight, 2 to 5.2 parts of compatibilizer (e.g., 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, 3.2 parts, 3.5 parts, 3.8 parts, 4 parts, 4.2 parts, 4.5 parts, 4.8 parts, 5 parts, or any range of the above values), 2 to 5 parts of dispersant (e.g., 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, 3 parts, 3.2 parts, 3.5 parts, 3.8 parts, 4 parts, 4.2 parts, 4.5 parts, 4.8 parts, 5 parts, or any range of the above values), and 0.5 to 2.7 parts of colorant (e.g., 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.7 parts, or any range of the above values).

[0048] In this application, lubricants may also be added as needed; the lubricants include erucamide, ethylene bis-stearamide, ethylene wax or white oil, etc.

[0049] Secondly, this application provides a method for preparing the flame-retardant polyolefin composition described in the first aspect, the method comprising the following steps:

[0050] The flame-retardant polyolefin composition is obtained by mixing ethylene-vinyl acetate copolymer, linear low-density polyethylene, polyolefin elastomer, flame retardant and antioxidant, and then extruding the mixture.

[0051] In one embodiment, the mixed material also includes other additives.

[0052] In this application, the mixing includes: adding ethylene-vinyl acetate copolymer, linear low-density polyethylene, polyolefin elastomer, flame retardant and optional compatibilizer and dispersant into a high-speed mixer and mixing them evenly at a speed of 2000~3000 rpm; adding optional lubricant and mixing at a speed of 1000~3000 rpm for 1~3 min; and then adding antioxidant and carbon black and mixing them evenly in a high-speed mixer at a speed of 500~1500 rpm.

[0053] In one embodiment, the extrusion temperature is 180~210°C, for example, it can be 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C or any range of the above values.

[0054] In this application, the extrusion is carried out in a twin-screw extruder; the length-to-diameter ratio of the twin-screw extruder is 44~50:1; and the temperature of each zone of the twin-screw extruder is 180~220℃.

[0055] Thirdly, this application provides a cable comprising the flame-retardant polyolefin composition described in the first aspect.

[0056] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific point values ​​included in the range.

[0057] Compared with related technologies, the beneficial effects of this application are as follows:

[0058] The flame-retardant polyolefin composition provided in this application is made by compounding ethylene-vinyl acetate copolymer, linear low-density polyethylene and polyolefin elastomer in specific amounts, and is combined with an antioxidant of a specific composition, so that the flame-retardant polyolefin composition has good heat resistance, aging resistance and exudation resistance, and also has good mechanical properties.

[0059] After reading and understanding the detailed description, other aspects can be understood. Detailed Implementation

[0060] The technical solution of this application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely to help understand this application and should not be regarded as specific limitations on this application.

[0061] All materials used in this application can be obtained by commercially available or conventional preparation methods. Unless otherwise specified, the materials used in this application are as follows:

[0062] EVA-1: VA content 18% by mass, EVA 7350M, Formosa Plastics, Taiwan, China.

[0063] EVA-2: VA content 26% by mass, EVA 7470M, Formosa Plastics, Taiwan, China.

[0064] EVA-3: VA content 40% by mass, EVA 40L-03, DOW.

[0065] EVA-4: VA content 14% by mass, EVA UL00014, ExxonMobil.

[0066] LLDPE-1: LLDPE DFDA-7042, Wanhua Chemical.

[0067] LLDPE-2: LLDPE ML2202, Shanghai Petrochemical.

[0068] POE-1: Density is 0.866 g / cm³ 3 INFUSE 9107, DOW.

[0069] POE-2: Density is 0.902 g / cm³ 3 , POE 8450, DOW.

[0070] POE-3: Density is 0.908 g / cm³ 3 , POE8540, DOW.

[0071] POE-4: Density is 0.862 g / cm³ 3 , POE 7467, DOW.

[0072] main antioxidant

[0073] Hindered phenol 1: Solubility parameter is 16, BHT, Double Bond Chemical Co., Ltd.;

[0074] Hindered phenol 2: solubility parameter is 18, antioxidant 1076, Tianjin Lianlong New Material Co., Ltd.;

[0075] Hindered phenol 3: solubility parameter is 20, antioxidant 1098, Tianjin Lianlong New Material Co., Ltd.;

[0076] Hindered phenol 4: solubility parameter is 23, antioxidant 1010, Tianjin Lianlong New Material Co., Ltd.;

[0077] Hindered phenol 5: solubility parameter is 15, antioxidant 1330, Double Bond Chemical Co., Ltd.;

[0078] Hindered phenol 6: solubility parameter is 25, antioxidant 1790, Tianjin Lianlong New Material Co., Ltd.;

[0079] Amine antioxidant 1: Antioxidant 445, Tianjin Lianlong New Material Co., Ltd.

[0080] Amine antioxidant 2: Antioxidant 1019, Tianjin Lianlong New Material Co., Ltd.

[0081] Co-oxidants

[0082] Thioester 1: Antioxidant DSTDP, Tianjin Lianlong New Material Co., Ltd.

[0083] Thioester 2: Antioxidant 412S, Tianjin Lianlong New Material Co., Ltd.

[0084] Phosphite 1: Antioxidant 168, Tianjin Lianlong New Material Co., Ltd.

[0085] Phosphite 2: Antioxidant PEP-36, Tianjin Lianlong New Material Co., Ltd.

[0086] Flame retardant

[0087] Aluminum hydroxide: AH-01DH, Jiangsu Aiteke Flame Retardant Materials Co., Ltd.

[0088] Magnesium hydroxide: Aitemag 10FD, Jiangsu Aitemag Flame Retardant Materials Co., Ltd.

[0089] Compatibilizer: Maleic anhydride-grafted modified metallocene polyethylene, MC218, Ningbo Nengzhiguang New Material Technology Co., Ltd.

[0090] Dispersant: Ultra-high molecular weight organosiloxane polymer, GT-300, Zhejiang Jiahua Essence.

[0091] Carbon black masterbatch: The matrix resin is PE; the carbon black mass percentage is 50% and the carbon black dispersion grade is ≤3.

[0092] Examples 1-20 and Comparative Examples 1-4 each provide a flame-retardant polyolefin composition. The formulations of the flame-retardant polyolefin compositions are shown in Tables 1-4 by weight. Wherein, " / " indicates that the component is not in the formulation; the ratio of values ​​to values ​​indicates the mass ratio, such as EVA:LLDPE:POE 4:1:3 indicating that the mass ratio of the three is 4:1:3; the carbon black content refers to the pure carbon black content, excluding the matrix resin in the masterbatch.

[0093] The preparation method of the flame-retardant polyolefin composition includes: adding LLDPE, POE, EVA, flame retardant, compatibilizer and dispersant into a high-speed mixer in proportion and mixing them evenly at a speed of 2500 rpm; adding 10# white oil and mixing at a speed of 2000 rpm for 2 minutes; then adding antioxidant and carbon black masterbatch and mixing them evenly in a high-speed mixer at a speed of 1000 rpm; extruding the resulting mixture through a twin-screw extruder and granulating it; the length-to-diameter ratio (L / D) of the twin screw is 48:1; the temperature of each zone is 180-200℃, wherein T1 is 180℃, T2-T7 are all 200℃, and T8 is 180℃.

[0094]

[0095]

[0096]

[0097]

[0098] Performance testing

[0099] The flame-retardant polyolefin composition particles provided in Examples 1-20 and Comparative Examples 1-4 were hot-pressed into sheets with a thickness of 1 mm and tested as follows; wherein, when testing tensile strength and elongation at break, the sheets were cut into dumbbell shapes for testing.

[0100] (1) Initial tensile strength and initial elongation at break: determined according to the method of standard GB / T 1040.3-2018.

[0101] (2) Heat resistance and aging resistance: The flame-retardant polyolefin composition was aged in air at 180°C for 168 h. The tensile strength and elongation at break of the flame-retardant polyolefin composition after aging were tested according to standard GB / T 1040.3-2018. The tensile strength retention rate and elongation at break retention rate were calculated. Retention rate = tensile strength after aging (elongation at break after aging) / initial tensile strength (initial elongation at break). The higher the retention rate, the better the heat resistance and aging resistance.

[0102] (3) Resistance to precipitation: The flame-retardant polyolefin composition was placed at a temperature of 85°C and a humidity of 85% for 1000 hours, and the presence of additives on the material surface was observed. If no additives were precipitated, it was recorded as 0; if the amount of precipitated additives was less than 0.5% of the total material area, it was recorded as 1; if the amount of precipitated additives was 0.5% or more of the total material area, it was recorded as 2.

[0103] The specific test results are shown in Table 5.

[0104]

[0105] As shown in Table 5, the flame-retardant polyolefin composition provided in this application uses EVA, LLDPE, and POE in specific proportions, along with an antioxidant of a specific composition. This results in good heat oxidation resistance and good exudation resistance, while also exhibiting excellent mechanical properties. The initial tensile strength of the flame-retardant polyolefin composition is ≥13.0 MPa, and the initial elongation at break is ≥400%; after heat oxidation, the tensile strength retention rate is ≥74%, and the elongation at break retention rate is ≥72%.

[0106] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A flame-retardant polyolefin composition, wherein, By weight, the flame-retardant polyolefin composition comprises 13-22 parts of ethylene-vinyl acetate copolymer, 1.5-8.5 parts of linear low-density polyethylene, 8-17 parts of polyolefin elastomer, 35-55 parts of flame retardant and 0.5-2.5 parts of antioxidant. The antioxidants include primary antioxidants and secondary antioxidants; The primary antioxidants include hindered phenolic antioxidants and amine antioxidants; the secondary antioxidants include thioester antioxidants and / or phosphite antioxidants.

2. The flame-retardant polyolefin composition according to claim 1, wherein, At 190°C and 2.16 kg, the melt index of the ethylene-vinyl acetate copolymer is 0.2~5 g / 10min.

3. The flame-retardant polyolefin composition according to claim 1 or 2, wherein, The ethylene-vinyl acetate copolymer contains 10-45% vinyl acetate structural units by mass, and optionally 18-28% vinyl acetate structural units by mass.

4. The flame-retardant polyolefin composition according to any one of claims 1-3, wherein, At 190℃ and 2.16kg, the melt index of the linear low-density polyethylene is 1~5 g / 10min; Optionally, the linear low-density polyethylene has an elongation at break of ≥600%.

5. The flame-retardant polyolefin composition according to any one of claims 1-4, wherein, The polyolefin elastomer includes ethylene-butene copolymer and / or ethylene-octene copolymer; Optionally, at 190°C and 2.16 kg, the melt index of the polyolefin elastomer is 0.3~5 g / 10min; Optionally, the density of the polyolefin elastomer is 0.860~0.915 g / cm³. 3 The density of the selected polyolefin elastomer is 0.865~0.905 g / cm³. 3 .

6. The flame-retardant polyolefin composition according to any one of claims 1-5, wherein, The mass ratio of the ethylene-vinyl acetate copolymer, linear low-density polyethylene and polyolefin elastomer is (2~10):1:(1~8), and optionally the mass ratio of the ethylene-vinyl acetate copolymer, linear low-density polyethylene and polyolefin elastomer is (3~8):1:(2~6).

7. The flame-retardant polyolefin composition according to any one of claims 1-6, wherein, The mass ratio of the flame retardant to the polyolefin elastomer is (2~6):1, and optionally the mass ratio of the flame retardant to the polyolefin elastomer is (3~5):1; Optionally, the flame retardant includes a halogen-free flame retardant; Optionally, the flame retardant includes magnesium hydroxide and / or aluminum hydroxide.

8. The flame-retardant polyolefin composition according to any one of claims 1-7, wherein, The mass ratio of the primary antioxidant to the secondary antioxidant is (1~3):1, and optionally the mass ratio of the primary antioxidant to the secondary antioxidant is (1.5~2.5):

1.

9. The flame-retardant polyolefin composition according to any one of claims 1-8, wherein, The mass ratio of the hindered phenolic antioxidant to the amine antioxidant is (0.5~1.5):

1.

10. The flame-retardant polyolefin composition according to any one of claims 1-9, wherein, The hindered phenolic antioxidant includes a first hindered phenolic antioxidant and a second hindered phenolic antioxidant; the absolute value of the difference between the solubility parameter of the first hindered phenolic antioxidant and the solubility parameter of the second hindered phenolic antioxidant is >3. Optionally, the mass ratio of the first hindered phenolic antioxidant to the second hindered phenolic antioxidant is (0.5~1.7):1, or optionally the mass ratio of the first hindered phenolic antioxidant to the second hindered phenolic antioxidant is (0.8~1.3):

1. Optionally, the solubility parameter of the first hindered phenolic antioxidant is 12~21, and optionally the solubility parameter is 16~19; Optionally, the first hindered phenolic antioxidant includes at least one of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,2'-thionylethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, dibutylhydroxytoluene, or N,N′-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide); Optionally, the solubility parameter of the second hindered phenolic antioxidant is 18~26, and optionally the solubility parameter is 19~23; Optionally, the second hindered phenolic antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N′-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide), or 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

11. The flame-retardant polyolefin composition according to any one of claims 1-10, wherein, The amine antioxidants include 4,4'-bis(phenylisopropyl)diphenylamine and / or N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)propanediamine.

12. The flame-retardant polyolefin composition according to any one of claims 1-11, wherein, The auxiliary antioxidants include thioester antioxidants and phosphite antioxidants, and the mass ratio of the thioester antioxidants to the phosphite antioxidants is (0.5~1.5):1; Optionally, the thioester antioxidant includes at least one of dioctadecyl thiodipropionate, pentaerythritol tetra(3-lauryl thiopropionate), or didodecyl thiodipropionate; the phosphite antioxidant includes at least one of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, or bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate. Optionally, the flame-retardant polyolefin composition further includes 4.4 to 15 parts by weight of other additives; Optionally, the other additives include at least one of compatibilizers, dispersants, or colorants; Optionally, the flame-retardant polyolefin composition comprises, by weight, 2 to 5.2 parts compatibilizer, 2 to 5 parts dispersant and 0.5 to 2.7 parts colorant.

13. A method for preparing a flame-retardant polyolefin composition according to any one of claims 1-12, comprising the following steps: The flame-retardant polyolefin composition is obtained by mixing ethylene-vinyl acetate copolymer, linear low-density polyethylene, polyolefin elastomer, flame retardant and antioxidant, and then extruding the mixture.

14. The preparation method according to claim 13, wherein, The mixed materials also include other additives; Optionally, the extrusion temperature is 180~210℃.

15. A cable, wherein, The cable comprises the flame-retardant polyolefin composition according to any one of claims 1-12.

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