A low-smoke flame-retardant polyolefin composition, its preparation method and application

Abstract

The present invention discloses a low-smoke flame-retardant polyolefin composition, a preparation method thereof, and an application thereof. The low-smoke flame-retardant polyolefin composition comprises the following components calculated by weight: 40-50 parts of a polyolefin resin; 5-15 parts of a compatibilizer; 30-50 parts of a halogen-free flame retardant; 1-3 parts of silica aerogel; 1-6 parts of porous silica microspheres; wherein the specific surface area of the porous silica microspheres is not less than 200 m 2 / g. In the present invention, the low-smoke flame-retardant polyolefin composition can effectively reduce the smoke density of the composition and has good flame retardant properties while ensuring the mechanical properties and processing properties of the composition by using a polyolefin resin as a matrix resin, adding appropriate amounts of silica aerogel and porous silica microspheres with a specific surface area, and combining with a halogen-free flame retardant.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-smoke flame retardancy, and particularly relates to a low-smoke flame-retardant polyolefin composition, a preparation method thereof, and an application thereof. Background Art

[0002] According to statistics, 80% of the deaths in fires are caused by asphyxiation of smoke and toxic gases. Moreover, smoke will greatly reduce visibility, delaying the opportunity for fire extinguishing and rescue. In China's engineering construction fire prevention codes, the fire prevention requirements for densely populated places, high-rise buildings, and special places are becoming increasingly strict. The Code for Electrical Fire Prevention Design of Civil Buildings clearly stipulates that for high-rise buildings with a height of more than 100 meters and less than 250 meters, cables laid in vertical shafts, wires laid openly in refuge floors and refuge rooms, underground buildings where people stay for a long time, and cables laid in the ceiling and passing through fire prevention zones, high-flame-retardant and low-smoke cables should be selected.

[0003] In the prior art, medium and high voltage armored cables need to have excellent mechanical properties and anti-cracking properties. Generally, polyethylene is selected as the resin main body. To ensure its mechanical properties, the amount of flame retardant used will be reduced, but the smoke density of the material cannot meet the requirements. By adding common smoke suppressants to the resin system, the smoke density can be effectively reduced, but it will cause a decline in its mechanical properties, and the processing and extrusion appearance is rough, affecting its application. Therefore, there is a need in the art to develop a low-smoke flame-retardant polyolefin composition with good mechanical properties and processing properties at the same time. Summary of the Invention

[0004] The purpose of the present invention is to overcome the fact that low-smoke flame-retardant polyolefin polymers in the prior art cannot have both good mechanical properties and processing properties, and to provide a low-smoke flame-retardant polyolefin composition.

[0005] Another purpose of the present invention is to provide a preparation method of the low-smoke flame-retardant polyolefin composition.

[0006] Another purpose of the present invention is to provide an application of the low-smoke flame-retardant polyolefin composition.

[0007] In order to achieve the above purposes, the present invention is implemented by adopting the following technical solutions:

[0008] A low-smoke flame-retardant polyolefin composition, comprising the following components calculated by weight:

[0009]

[0010] Among them, the specific surface area of the porous silica microspheres is not less than 200 m 2 / g.

[0011] In the present invention, by using a polyolefin resin as the matrix resin and adding an appropriate amount of silica aerogel and porous silica microspheres with a specific specific surface area, while ensuring the mechanical properties and processing properties of the composition, the smoke density thereof is reduced.

[0012] Specifically, the purpose of using silica for both the aerogel and the microspheres is to utilize the char-forming property of silica. The silica aerogel has a high porosity and specific surface area, and can significantly suppress smoke and improve flame retardancy. However, due to its high porosity and low strength, if the addition amount is too high, it will be damaged during the processing, the extrusion appearance will be rough, and the compatibility and the structure of silica will be damaged, which will instead lead to a decrease in smoke suppression performance and flame retardancy; the porous silica microspheres have a high specific surface area and also have the effect of adsorbing and suppressing smoke. Although its smoke suppression effect is not as good as that of the silica aerogel, it is not easily broken compared with the silica aerogel, which helps to improve the strength of the composition; by compounding the porous silica microspheres and the silica aerogel, it has good char-forming properties, can reduce the smoke density of the composition on the premise of ensuring mechanical properties and processing properties, and has good flame retardancy at the same time.

[0013] It should be noted that the porous silica microspheres in the present invention do not include silica aerogel microspheres.

[0014] Specifically, the density of the silica aerogel < 0.5 g / cm 3 , and the density of the porous silica microspheres > 1.5 g / cm 3 .

[0015] It should be noted that in the low-smoke flame-retardant polyolefin composition of the present invention, the content of the polyolefin is preferably not less than 30 wt%.

[0016] It should be noted that in the present invention, the polyolefin resin is 40 - 50 parts, for example but not limited to 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 parts, 49 parts or 50 parts, etc., all of which can achieve the present invention.

[0017] In the present invention, the silica aerogel is 1 - 3 parts, for example but not limited to 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, etc., all of which can achieve the present invention.

[0018] In the present invention, the porous silica microspheres are 1 - 6 parts, for example but not limited to 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts or 6 parts, etc., all of which can achieve the present invention.

[0019] Furthermore, the low-smoke flame-retardant polyolefin composition includes the following components calculated by weight:

[0020]

[0021] Specifically, the melt flow rate of the polyolefin resin at 190 °C under a load of 2.16 kg is 0.5 to 10 g / 10 min.

[0022] Specifically, the test standard for the melt flow rate is ASTM D-1238-2010.

[0023] In the present invention, the specific surface area of the porous silica microspheres is not less than 200 m 2 / g, for example but not limited to not less than 210, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, etc. can all achieve the present invention. Further, the specific surface area of the porous silica microspheres is 220 to 550 m 2 / g.

[0024] Even further, the specific surface area of the porous silica microspheres is 300 to 500 m 2 / g.

[0025] Further, the specific surface area of the silica aerogel is ≥700 m 2 / g, for example but not limited to ≥710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1050, 1100, 1150, 1200 m 2 / g, etc. can all achieve the present invention. Further, the specific surface area of the silica aerogel is 700 to 1000 m 2 / g.

[0026] Specifically, the specific surface areas of the silica aerogel and the porous silica microspheres are tested by a specific surface area tester.

[0027] In the specific embodiment, the specific surface area is measured in three groups for each sample, and the average value is taken.

[0028] Further, the mass ratio of the porous silica microspheres to the silica aerogel is 1:3 to 3:1.

[0029] Even further, the mass ratio of the porous silica microspheres to the silica aerogel is 3:5 to 5:3.

[0030] Furthermore, the polyolefin resin includes at least one of polyethylene and polypropylene. Preferably, the polyolefin is polyethylene; further, the polyethylene is linear low density polyethylene.

[0031] Furthermore, the halogen-free flame retardant is a hydroxide flame retardant.

[0032] Even further, the hydroxide flame retardant is magnesium hydroxide and / or aluminum hydroxide.

[0033] Furthermore, the compatibilizer is a maleic anhydride graft.

[0034] Even further, the maleic anhydride graft is PE grafted maleic anhydride and / or POE grafted maleic anhydride.

[0035] Specifically, the maleic anhydride grafting rate of the compatibilizer is 0.5 - 2%.

[0036] Specifically, the test method for the maleic anhydride grafting rate is infrared spectroscopy.

[0037] Furthermore, the low-smoke flame-retardant polyolefin composition further includes 0.1 - 5 parts of additives.

[0038] Specifically, the additives include, for example but not limited to, one or several of antioxidants, lubricants, weathering agents or colorants.

[0039] In the present invention, common antioxidants can be selected, such as, for example but not limited to, one or several of hindered phenol antioxidants, phosphite antioxidants or thioester antioxidants.

[0040] Specifically, the hindered phenol antioxidants are one or several of N,N'-hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamide) (Irganox 1098), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 259), n-octadecyl β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate (Irganox 1076) or 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)acrylic acid]-1,1-dimethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane (ADK AO-80).

[0041] The phosphite antioxidants are one or several of tris(2,4-di-tert-butylphenyl) phosphite (Irganox 168), bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (PEP-36) or 627A.

[0042] The thioester antioxidant is one or more of distearyl thiodipropionate, dilauryl thiodipropionate or pentaerythritol lauryl thiotripropionate.

[0043] The present invention also protects a method for preparing the above low-smoke flame-retardant polyolefin composition, which comprises the following steps:

[0044] Mix the components evenly and obtain the low-smoke flame-retardant polyolefin composition by extrusion granulation.

[0045] Specifically, a two-stage single-screw extruder is used for the extrusion granulation.

[0046] Specifically, the extrusion temperature is 140-150 °C.

[0047] The present invention also protects the application of the above low-smoke flame-retardant polyamide composition in the preparation of flame-retardant sheath materials, especially suitable for medium and high-voltage flame-retardant sheath materials.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention provides a low-smoke flame-retardant polyamide composition. Using a polyolefin resin as the matrix resin and adding silica aerogel and porous silica microspheres with a specific specific surface area can effectively reduce the smoke density of the obtained composition, and at the same time enable the composition to have good mechanical properties and processing properties. Specific Embodiments

[0050] The following further elaborates the present invention in conjunction with specific embodiments. The embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention. The test methods used in the following embodiments are all conventional methods unless otherwise specified; the materials, reagents, etc. used are commercially available reagents and materials unless otherwise specified.

[0051] Raw materials used in each embodiment and comparative example:

[0052] Polyolefin resin:

[0053] Polyolefin resin 1: Metallocene linear low-density polyethylene, LLDPE ENGAGE 3518PA, produced by ExxonMobil;

[0054] Polyolefin resin 2: Linear low-density polyethylene, LLDPE FB2230, produced by Borealis;

[0055] Compatibilizer: PE-grafted maleic anhydride, MC-218, produced by Nengzhiguang;

[0056] Halogen-free flame retardant: Magnesium hydroxide, H-5, produced by Chemtura;

[0057] Silica aerogel:

[0058] Silica aerogel 1: SPS, specific surface area 850 m 2 / g, Jiayun New Materials;

[0059] Silica aerogel 2: SPQ, specific surface area 800 m 2 / g, Jiayun New Materials;

[0060] Porous silica microspheres:

[0061] Porous silica microspheres 1: XFF30, specific surface area 470 m 2 / g, average particle size 500 nm, Xianfeng Nano Materials Technology Co., Ltd.;

[0062] Porous silica microspheres 2: XFF48, specific surface area 540 m 2 / g, Xianfeng Nano Materials Technology Co., Ltd.;

[0063] Porous silica microspheres 3: SF80, specific surface area 210 m 2 / g, Qinghe County Chaotai Metal Materials Co., Ltd.;

[0064] Porous silica microspheres 4: Brofos-SiO2-JK500, specific surface area 154 m 2 / g, average particle size 500 nm, Bohuasi Nano Technology Co., Ltd.;

[0065] Auxiliary agent:

[0066] Antioxidant: 1010, commercially available; the same raw materials are used in the parallel experiments of the examples and comparative examples;

[0067] Examples 1 to 11 and Comparative Examples 1 to 4

[0068] According to the formulations in Tables 1 to 2, prepare a low-smoke flame-retardant polyolefin composition according to the following preparation method:

[0069] Add polyolefin, compatibilizer, halogen-free flame retardant, silica aerogel, porous silica microspheres and antioxidant into a high-speed mixer in proportion and mix evenly at a rotation speed of 1000 - 2000 rpm, then put it into a mixer. After mixing by the mixer, extrude and pelletize through a two-stage single-screw extruder to obtain a low-smoke flame-retardant polyolefin composition, and the extrusion temperature is 140 - 150 °C.

[0070] Table 1 Dosages of each component in the low-smoke flame-retardant polyolefin composition in Examples 1 to 11 (unit: parts by weight)

[0071]

[0072]

[0073] Table 2 Dosages of each component in the low-smoke flame-retardant polyolefin compositions of Comparative Examples 1 to 4 (unit: parts by weight)

[0074]

[0075] Performance testing

[0076] 1. Test method

[0077] Perform performance testing on the low-smoke flame-retardant crosslinked polyolefin compositions prepared in the above Examples and Comparative Examples:

[0078] (1) Mechanical property testing: Press the halogen-free flame-retardant polyolefin compositions prepared in the above Examples and Comparative Examples into sheets on a flat vulcanizing machine at 180 °C for 10 min, with a pressure of 15 MPa and a sample sheet thickness of 1 mm. After standing at room temperature for 16 h, refer to Standard GB / T 1040.2-2018 to measure the mechanical properties of the 1-mm-thick sample sheets; according to Standard IEC 60840-2020, the tensile strength is required to be > 13.5 MPa and the elongation at break is > 350%.

[0079] (2) Extrusion property testing: Extrude wires from the low-smoke flame-retardant polyolefin compositions prepared in the above Examples and Comparative Examples using an extruder, and observe the extrusion appearance. If the sample surface is bright and has no phenomena such as frosting, it is smooth in appearance, indicating excellent extrusion performance; if the sample surface is rough, uneven, has pores or particles on the surface, it is rough in appearance, indicating poor extrusion performance;

[0080] (3) Flame retardancy testing: Prepare the low-smoke flame-retardant polyolefin compositions prepared in the above Examples and Comparative Examples into specimens of 125 mm × 12.5 mm × 3 mm, and conduct UL94 vertical burning. Refer to Standard ASTM 3801, and the UL94 burning grades are divided into four grades: V-0, V-1, V-2, and NR, where the flame retardancy grades decrease in turn;

[0081] (4) Smoke density testing: Prepare the low-smoke flame-retardant polyolefin compositions prepared in the above Examples and Comparative Examples into specimens of 100 mm × 100 mm × 1 mm, and measure the smoke density according to Standard GB / T 8323.2-2008.

[0082] 2. Test results

[0083] Table 3 Performance test results of each Example and Comparative Example

[0084]

[0085]

[0086] As can be seen from Table 3, the low-smoke flame-retardant polyolefin composition prepared by the present invention has a low smoke density and good flame-retardant properties, and also has good mechanical properties and processing properties. Specifically: it can all reach V-0 level flame retardancy, and the extrusion appearance is smooth; the tensile strength > 13.5 MPa, the elongation at break > 350%, meeting the IEC 60840-2020 standard; the smokiness with flame is not higher than 80, and the smokiness without flame is not higher than 280, which can meet the requirements for obtaining qualified finished cables in subsequent processing.

[0087] As can be seen from Comparative Example 1, if silica aerogel and porous silica microspheres are not added, the prepared polyolefin composition has poor flame-retardant properties and a high smoke density that cannot meet the requirements.

[0088] As can be seen from Comparative Example 2, if the amount of silica aerogel is excessive, the silica aerogel is fragile, which will damage the compatibility, significantly reduce the mechanical properties and cannot meet the requirements, and the extrusion performance deteriorates. The prepared polyolefin composition also cannot meet V-0 flame retardancy.

[0089] As can be seen from Comparative Example 3, if only porous silica microspheres are used, the flame-retardant properties of the prepared polyolefin composition cannot be met, the smoke suppression efficiency is low, and the smoke density is high.

[0090] As can be seen from Comparative Example 4, when the specific surface area of the porous silica microspheres used is small, the flame-retardant properties of the prepared polyolefin composition cannot meet the requirements, and the smoke density is high.

[0091] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A low-smoke flame-retardant polyolefin composition, characterized in that, It comprises the following components calculated by weight parts: Among them, the specific surface area of the porous silica microspheres is 200-550 m 2 / g, and the specific surface area of the silica aerogel is 700-1000 m 2 / g; the halogen-free flame retardant is a hydroxide flame retardant.

2. The low-smoke flame-retardant polyolefin composition according to claim 1, wherein The surface area of the porous silica microspheres is 220 to 550 m 2 / g.

3. The low-smoke flame-retardant polyolefin composition according to claim 1, characterized in that, The mass ratio of the porous silica microspheres to the silica aerogel is 3:5 to 5:

3.

4. The low-smoke flame-retardant polyolefin composition according to claim 1, wherein The polyolefin resin is linear low density polyethylene.

5. The low-smoke flame-retardant polyolefin composition according to claim 1, wherein The compatibilizer is a maleic anhydride graft.

6. The low-smoke flame-retardant polyolefin composition according to claim 1, wherein The low-smoke flame-retardant polyolefin composition further comprises 0.1 to 5 parts of an auxiliary agent.

7. A method for preparing the low-smoke flame-retardant polyolefin composition according to any one of claims 1 to 6, characterized in that, It comprises the following steps: Mix the components evenly and obtain a halogen-free flame-retardant polyolefin composition by extrusion granulation.

8. Use of the low-smoke flame-retardant polyolefin composition according to any one of claims 1 to 6 in preparing a flame-retardant sheath material.

Images