A polyolefin composition and its preparation method and application

Abstract

The present invention relates to a polyolefin composition and a preparation method and application thereof, the components of which include polyethylene, a compatibilizer, antimony trioxide, a low-melting-point glass powder, a ceramic skeleton material, and an antioxidant. The polyolefin composition of the present invention can be completely ceramicized at low temperatures and has extremely high ceramic strength at high temperatures, and is an excellent ceramicized polyolefin cable material.

Description

Technical Field

[0001] The invention belongs to the field of general plastics, and particularly relates to a polyolefin composition and a preparation method and application thereof. Background Art

[0002] At present, due to the rapid economic development, national policies attach more and more importance to fire safety, requiring that power cables in high-rise buildings must have fireproof and fire-resistant functions, especially cables with fire safety functions, to ensure that when a fire accident occurs, the burning middle layer of the cable must have high fire-resistant combustion performance to ensure that the inner insulation layer and core layer of the cable are not severely damaged, and even need to ensure normal power and signal transmission at the fire scene. Most of the current fire-resistant wires and cables use magnesium oxide mineral insulation or mica tape wrapping to achieve fire resistance, but this method greatly increases the overall cable cabling process and difficulty, improves the overall quality of the cable, and is extremely costly; in addition, in recent years, the world has been carrying out large-scale carbon neutrality actions, and this mica tape is not conducive to recycling and reuse, so there is an urgent need for a thermoplastic fire-resistant barrier material.

[0003] Existing ceramic refractory materials all have the defects of poor low-temperature ceramic-forming ability and low high-temperature ceramic-forming strength. Summary of the invention

[0004] In view of the defects of the prior art, the technical problem to be solved by the present invention is to provide a ceramicized, fire-resistant polyolefin composition and a preparation method and application thereof.

[0005] A polyolefin composition of the present invention comprises, by weight:

[0006]

[0007] The porcelain skeleton material is a mixture of silicon dioxide and silicon nitride whiskers, wherein the mass ratio of silicon dioxide to silicon nitride whiskers is 1:(2-5).

[0008] Silicon dioxide and silicon nitride have similar electrical potentials. In the polymer, the two will form good dispersion and mutual attachment, and have a good synergistic effect.

[0009] Preferably, the polyethylene is metallocene linear low density polyethylene.

[0010] Preferably, the compatibilizer is PE grafted maleic anhydride or / and PE grafted glycidyl methacrylate.

[0011] Preferably, the mass ratio of antimony trioxide and low-melting point glass powder is (7-1):1, and further preferably, the mass ratio of antimony trioxide and low-melting point glass powder is (4-2):1; the compounding of antimony trioxide and low-melting point glass powder can better take into account the ceramic material's porcelain strength at high and low temperatures. If the ratio is too low, the low-temperature porcelain strength is insufficient, and if the ratio is too high, the high-temperature porcelain strength is insufficient.

[0012] The melting point of the low-melting-point glass powder is 400-500°C. The melting point test method is as follows: the glass powder is placed in a muffle furnace at different temperatures of 400-900°C (every 50°C is a temperature point, such as 400°C, 450°C, 500°C, 550°C, 600°C...900°C) and calcined for 2 minutes. During calcination, observe whether the glass powder melts. If the glass powder melts within 2 minutes, the temperature point is judged to be the melting point of the glass powder. The melting point of the low-melting-point glass powder can be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, etc.

[0013] Preferably, the mass ratio of silicon dioxide to silicon nitride whiskers is 1:(3-4). Silicon nitride whiskers serve as the main porcelain skeleton. Too small a proportion will result in too low porcelain strength. Silicon dioxide serves as a synergistic porcelain filler. It is dispersed and attached to the vicinity of the silicon nitride whiskers to form a weak inorganic network structure to support porcelain formation. Too little content will not be able to form a weak network structure with the silicon nitride whiskers, which is unfavorable to the porcelain strength.

[0014] Preferably, the aspect ratio of the silicon nitride whisker is ≥ 30. The aspect ratio is tested according to JG / T 472-2015. Further preferably, the aspect ratio of the silicon nitride whisker is 40-50. Too large an aspect ratio will cause the whisker to be too fragile and easy to break during processing, while too small an aspect ratio will not play a strong supporting role as a skeleton component, which will lead to a decrease in the strength of the ceramic.

[0015] The aspect ratio of the silicon nitride whiskers may be 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, etc.

[0016] Preferably, the antioxidant is one or more of a hindered phenol antioxidant (such as antioxidant 3114, antioxidant 1010), a phosphite antioxidant (such as PEP-36, antioxidant 168), a thioether antioxidant (such as IRGANOX PS 802FD, antioxidant DSTDP), and a hindered amine antioxidant (such as CHIMASSORB 944FDL, Naugard 445).

[0017] Preferably, by weight, the components include:

[0018]

[0019] A method for preparing the polyolefin composition of the present invention comprises:

[0020] The components are weighed according to the weight ratio, mixed, and then put into an internal mixer. After internal mixing, they are extruded and granulated by an extruder to obtain a polyolefin composition.

[0021] Preferably, the temperature of the internal mixer is controlled at 120-140°C, and the temperature of the single-screw extruder is controlled at 140-150°C.

[0022] The polyolefin composition of the present invention is used in cable materials, such as fire-resistant polyolefin cables.

[0023] In the present invention, when low-melting-point glass powder is selected, antimony trioxide (melting point 600-700°C) is used as another porcelain powder component to make up for the defect that the low-melting-point glass powder is too easy to flow at high temperature (above 800°C) and is not sufficiently combined with silicon oxide and silicon nitride of the porcelain skeleton; the porcelain skeleton is selected from silicon dioxide and silicon nitride whiskers, which have similar electric potentials and good dispersibility, and the selection of silicon nitride whiskers with a specific aspect ratio provides a lot of guarantee for the bending strength after porcelain formation, and has good toughness.

[0024] Beneficial Effects

[0025] The polyolefin composition of the present invention can be completely ceramicized at low temperature and has extremely high ceramic strength at high temperature, and is an excellent ceramicized polyolefin cable material. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0027] 1. Source of raw materials

[0028] Polyethylene: Metallocene linear low-density polyethylene, LLDPE ENGAGE 3518PA, produced by ExxonMobil;

[0029] Compatibilizer: PE grafted maleic anhydride: MC-218, produced by Nengzhiguang;

[0030] Antimony trioxide: S-05N, Changde Chenzhou Antimony Products Co., Ltd.;

[0031] Sodium antimonate: SA-F, Chengdu Kaifei High Energy Chemical Industry Co., Ltd.;

[0032] Low melting point glass powder: FR0135, Anmi Micron, melting point 450℃;

[0033] Silica: SYLOBLOC 45, GRACE, USA;

[0034] Silicon nitride whisker-1: aspect ratio 50; UBE SN-E10, Ube, Japan

[0035] Silicon nitride whisker-2: aspect ratio 40; P95N; VESTA, Sweden

[0036] Silicon nitride whisker-3: aspect ratio 60; Japan Ube; SN-E10

[0037] Silicon nitride whisker-4: aspect ratio is 20; German CeramTec SL 200BG antioxidant: antioxidant 1010.

[0038] The mass ratio of the ceramic skeleton material-1: silicon dioxide and silicon nitride whisker-1 is 1:3;

[0039] The mass ratio of the ceramic skeleton material-2: silicon dioxide and silicon nitride whisker-1 is 1:4;

[0040] The mass ratio of the ceramic skeleton material-3: silicon dioxide and silicon nitride whisker-1 is 1:2;

[0041] The mass ratio of the ceramic skeleton material-4: silicon dioxide and silicon nitride whisker-1 is 1:5;

[0042] The mass ratio of the ceramic skeleton material-5: silicon dioxide and silicon nitride whisker-2 is 1:3;

[0043] The mass ratio of the ceramic skeleton material-6: silicon dioxide and silicon nitride whisker-3 is 1:3;

[0044] The mass ratio of the ceramic skeleton material-7: silicon dioxide and silicon nitride whisker-1 is 1:1;

[0045] The mass ratio of the ceramic skeleton material-8: silicon dioxide and silicon nitride whisker-1 is 1:8;

[0046] The mass ratio of the ceramic skeleton material-9: silicon dioxide and silicon nitride whisker-4 is 1:3;

[0047] The antioxidants used in the parallel examples and comparative examples are all the same commercially available products.

[0048] 2. Preparation methods of embodiments and comparative examples

[0049] The components are weighed according to the weight ratio, mixed, and then put into an internal mixer. After internal mixing, the components are extruded and granulated through a double-stage single-screw extruder to obtain a polyolefin composition. The temperature of the internal mixer is controlled at 120-140° C., and the temperature of the single-screw extruder is controlled at 140-150° C.

[0050] 3. Test standards and methods

[0051] The obtained polyolefin composition was pressed into sheets on a flat vulcanizer at 180°C for 10 min, with a pressure of 15 MPa and a sheet thickness of 1 mm. After being placed at room temperature for 16 h, the sheets were cut into strips of 60*10*1 mm and placed in a muffle furnace at 600 and 900°C for 5-10 min. The ceramicized strips were taken out for testing:

[0052] (1) Tap the ceramicized specimen and listen to the tapping sound, which can be divided into crisp, dull, and dull. The crisper the sound, the better the ceramicization.

[0053] (2) Observe the surface of the porcelain and classify it into intact, distorted, foamed, and broken.

[0054] (3) After the width and thickness of the porcelain specimens were tested, they were placed on a bending tester with a span of 30 mm and subjected to a bending compression test at a rate of 2 mm / min. Finally, the bending strength of the porcelain specimens was obtained. The greater the strength, the higher the porcelain strength and the better the porcelain effect.

[0055] Table 1 Proportions of the embodiments (parts by weight)

[0056]

[0057]

[0058] Table 2 Comparative Example Proportions (parts by weight)

[0059] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Polyethylene 30 30 30 30 30 30 30 Compatibilizer 6 6 6 6 6 6 6 Antimony trioxide 20 20 20 20 20 5 Sodium antimonate 20 Low melting point glass powder 10 10 10 10 10 10 10 Porcelain skeleton material-1 85 Porcelain skeleton material-7 85 Porcelain skeleton material-8 85 Porcelain skeleton material-9 85 Silicon dioxide 85 Silicon Nitride Whiskers-1 85 Antioxidants 3 3 3 3 3 3 3

[0060] Table 3 Performance data of the embodiment

[0061]

[0062]

[0063] Table 4 Performance data of comparative examples

[0064] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 600℃ porcelain sound Matte Dull Matte Dull Dull Matte Matte 600℃ Porcelain Appearance fracture Twisting, foaming fracture Twisting, foaming Twisting, foaming fracture fracture 600℃ Porcelain Flexural Strength (MPa) 2 Unable to test 2.5 Unable to test 1.5 2 Unable to test 900℃ porcelain sound Crisp Crisp Crisp Dull Dull Dull Dull 900℃ Porcelain appearance fracture whole distortion fracture fracture fracture fracture 900℃ Porcelain Flexural Strength (MPa) 5 5.5 4.5 5 4.1 4 5

[0065] The embodiments of the present invention can ensure complete porcelain formation at 600°C, and the low-temperature porcelain strength at 600°C is all >4MPa, indicating that the material has good porcelain forming properties at around 600°C; and when porcelain is formed at 900°C, all embodiments are completely porcelain formed, with a crisp porcelain forming sound, and the porcelain strength is all >9MPa, showing excellent high-temperature porcelain forming performance.

[0066] In the comparative examples, the porcelain strength at 600°C was less than 2MPa, and distortion and fracture occurred frequently, indicating that the low-temperature porcelain effect was not achieved at all; and although the shape of the porcelain was improved at 900°C, its maximum porcelain strength was only 5MPa, far less than the 9-11MPa of the embodiments.

Claims

1. A polyolefin composition, characterized in that By weight, the components include: 20-35 parts of polyethylene; 4-10 parts of compatibilizer; 15-25 parts of antimony trioxide; 4-15 parts of low melting point glass powder; 80-100 parts of porcelain skeleton material; 2-5 parts of antioxidant; The porcelain skeleton material is a mixture of silicon dioxide and silicon nitride whiskers, wherein the mass ratio of silicon dioxide to silicon nitride whiskers is 1:(2-5); the mass ratio of antimony trioxide to low-melting-point glass powder is (7-1):1; the melting point of the low-melting-point glass powder is 400-500°C; and the aspect ratio of the silicon nitride whiskers is 40-50.

2. The polyolefin composition according to claim 1, characterized in that: The polyethylene is metallocene linear low-density polyethylene; the compatibilizer is PE grafted maleic anhydride or / and PE grafted glycidyl methacrylate.

3. The polyolefin composition according to claim 1, characterized in that: The mass ratio of the silicon dioxide to the silicon nitride whisker is 1:(3-4).

4. The polyolefin composition according to claim 1, characterized in that: The mass ratio of the antimony trioxide to the low-melting-point glass powder is (4-2):

1.

5. The polyolefin composition according to claim 1, characterized in that: The antioxidant is one or more of a hindered phenol antioxidant, a phosphite antioxidant, a thioether antioxidant, and a hindered amine antioxidant.

6. The polyolefin composition according to claim 1, characterized in that: By weight, the components include: Polyethylene 25-30 parts; 5-8 parts of compatibilizer; 20-24 parts of antimony trioxide; 5-12 parts of low melting point glass powder; 85-95 parts of porcelain skeleton material; 2-5 parts of antioxidant.

7. A method for preparing the polyolefin composition according to claim 1, comprising: The components are weighed according to the weight ratio, mixed, and then put into an internal mixer. After internal mixing, they are extruded and granulated by an extruder to obtain a polyolefin composition.

8. Use of the polyolefin composition according to claim 1 in the preparation of ceramic fire-proof and fire-resistant cables and cable materials.

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