A B1 - level low - smoke and halogen - free flame - retardant composition, its preparation method and application

Abstract

The present invention provides a B1 - level low - smoke and halogen - free flame - retardant composition, a preparation method thereof and an application. The B1 - level low - smoke and halogen - free flame - retardant composition comprises the following components calculated by weight: 60 - 120 parts of polyolefin resin; 3 - 8 parts of compatibilizer; 160 - 230 parts of inorganic flame retardant; 0.5 - 3 parts of calcium oxide; 0.5 - 1.5 parts of dehydrogenation catalyst; 0 - 4 parts of processing aid; wherein the dehydrogenation catalyst is a palladium - alumina catalyst; the D50 of the calcium oxide is 4 - 10 μm. The composition is added with a dehydrogenation catalyst. During the heating process, the dehydrogenation catalyst can dehydrogenate the polyolefin substrate into carbon, enabling the substrate to form a stable and efficient carbon layer. At the same time, the dehydrogenation catalyst is compounded with calcium oxide, which can effectively reduce the heat release of the sheath material itself and improve the flame - retardant performance of the material. The prepared material has a tensile strength of not less than 10 MPa and an elongation at break of not less than 160%, while meeting the B1 - level flame retardancy requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of cable sheath materials, and more specifically, to a B1-level low-smoke and halogen-free flame retardant composition, a preparation method thereof, and an application thereof. Background Art

[0002] Traditional low-smoke and halogen-free flame retardant sheath materials are prepared by using a composition of polyethylene, ethylene-vinyl acetate copolymer, and ethylene-octene copolymer as the resin base material, and using environmentally friendly metal hydroxides such as magnesium hydroxide and aluminum hydroxide as flame retardants to prepare modified polymer materials with low-smoke and halogen-free flame retardant properties, which are mainly applied to densely populated places such as airports, stations, rail transit, and large buildings.

[0003] As the country pays more and more attention to building fire safety, the fire prevention requirements for densely populated places are also getting higher and higher. The Code for Electrical Fire Protection Design of Civil Buildings stipulates that cables laid in high-rise buildings higher than 100 meters and less than 250 meters, wires laid openly in refuge floors and refuge rooms, and underground buildings where people stay for a long time should use cables with a combustion performance not lower than B1 level. Compared with GB / T 19666 and GB / T 17651, GB / T 31247 B1-level flame retardant has higher requirements for the heat release and smoke release performance of the sheath material, and it is difficult for traditional sheath materials to meet the requirements.

[0004] According to GB / T 32129-2015, the halogen-free flame retardant cable materials for wires and cables should meet the requirements of tensile strength ≥ 10.0 MPa and elongation at break ≥ 160%. However, in the prior art, there are few materials that simultaneously meet the B1-level flame retardant of GB / T 31247 and the low-smoke and halogen-free material standard of GB / T 32129-2015, which will limit their application, and usually require the compounding of flame retardants or the cooperation with flame retardant synergists to meet the requirements. Summary of the Invention

[0005] The present invention aims to overcome at least one of the above-mentioned defects in the prior art, and provides a B1-level low-smoke and halogen-free flame retardant composition, which meets the B1-level flame retardant, and at the same time has good tensile strength and elongation at break, and meets the low-smoke and halogen-free material standard of GB / T 32129-2015.

[0006] Another object of the present invention is to provide a preparation method of the B1-level low-smoke and halogen-free flame retardant composition.

[0007] Another object of the present invention is to provide an application of the B1-level low-smoke and halogen-free flame retardant composition in the preparation of cable sheath materials.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A B1 - level low - smoke, halogen - free flame - retardant composition, comprising the following components calculated by weight:

[0010]

[0011] Wherein the dehydrogenation catalyst is a palladium - alumina catalyst; the D50 of the calcium oxide is 4 - 10 μm.

[0012] The inventors found through a large number of experiments that adding a small amount of palladium - alumina as a dehydrogenation catalyst in the polyolefin resin system can dehydrogenate the polyolefin resin into carbon during heating, enabling the substrate to form a stable and efficient carbon layer; at the same time, the dehydrogenation catalyst is compounded with the inorganic flame - retardant, which can effectively reduce the heat release of the sheath material itself and improve the flame - retardant performance of the material; in addition, adding an appropriate amount of calcium oxide to the system, the inorganic flame - retardant releases water during heating, and the water can react with calcium oxide to generate calcium hydroxide. A small amount of milky calcium hydroxide can form a film - like structure on the material surface, and the dehydrogenation catalyst and calcium oxide synergistically enhance the flame - retardant performance.

[0013] Further, the compatibilizer is polyethylene - grafted maleic anhydride.

[0014] The inorganic flame - retardant involved in the present invention can be magnesium hydroxide or magnesium hydroxide surface - treated with a silane coupling agent. In the magnesium hydroxide surface - treated with a silane coupling agent, the mass ratio of magnesium hydroxide to the silane coupling agent is 95 - 100:1. The present invention is not limited thereto.

[0015] The surface - treated magnesium hydroxide can be commercially available or self - made.

[0016] Specifically, the self - made method is: in a high - speed mixer, heat the magnesium hydroxide and add 3 - aminopropyltriethoxysilane in proportion for high - speed mixing and coating.

[0017] Further, the D50 of the calcium oxide is 5 - 8 μm.

[0018] It should be noted that the polyolefin resin in the present invention can be selected according to the prior art. For example, but not limited to, the polyolefin resin is one or two of polyethylene resin, ethylene - octene copolymer or ethylene - vinyl acetate copolymer.

[0019] Further, the melt index of the polyolefin resin tested according to GB / T 3682 - 2000 under the conditions of 190 °C and 2.16 kg is 0.5 - 5 g / 10 min.

[0020] Further, the polyethylene resin is linear low - density polyethylene.

[0021] Further, the polyethylene resin is a polyethylene resin synthesized using a metallocene catalyst system.

[0022] Furthermore, the comonomer of the polyethylene resin is 1-hexene.

[0023] Furthermore, the density of the polyethylene resin is 0.925 - 0.936 g / cm 3 .

[0024] Furthermore, the melt index of the polyethylene resin under the conditions of 190 °C and 2.16 kg is 1 - 3.5 g / 10 min.

[0025] Furthermore, the mass ratio range of linear low density polyethylene resin, ethylene-octene copolymer and ethylene vinyl acetate copolymer in the polypropylene resin is (0.5 - 4.5):(2.5 - 4.5):1.

[0026] Specifically, 25 - 45 parts of linear low density polyethylene resin; 25 - 45 parts of ethylene-octene copolymer; 10 - 30 parts of ethylene vinyl acetate copolymer. Under such dosages, the mechanical properties of the prepared low-smoke and halogen-free flame retardant composition are better.

[0027] Furthermore, the melt index determination standard of the polyethylene resin is GB / T 3682 - 2000.

[0028] Furthermore, the comonomer of the polyethylene grafted with maleic anhydride is 1-hexene.

[0029] Furthermore, the density of the polyethylene of the grafting matrix of the polyethylene grafted with maleic anhydride is 0.92 - 0.940 g / cm 3 .

[0030] Furthermore, the maleic anhydride grafting rate of the polyethylene grafted with maleic anhydride is greater than or equal to 0.8%. If the maleic anhydride grafting rate is too low, the effect is not obvious, resulting in poor compatibility between the inorganic and organic substances of the material and affecting the mechanical properties of the material.

[0031] The determination method of the maleic anhydride grafting rate of the polyethylene grafted with maleic anhydride can adopt a conventional method, such as acid-base titration.

[0032] Furthermore, the residual maleic anhydride monomer in the polyethylene grafted with maleic anhydride is not more than 0.5‰.

[0033] Furthermore, the melt index of the ethylene-octene copolymer under the conditions of 190 °C and 2.16 kg is 0.5 - 5 g / 10 min.

[0034] Furthermore, the melt index determination standard of the polyethylene resin is GB / T 3682 - 2000.

[0035] Further, the melt index of the ethylene-vinyl acetate copolymer under the conditions of 190 °C and 2.16 kg is 0.5 to 3 g / 10 min.

[0036] Furthermore, the standard for measuring the melt index of the polyethylene resin is GB / T 3682-2000.

[0037] Further, in the ethylene-vinyl acetate copolymer, the vinyl acetate content is 18 to 30%.

[0038] Further, the processing aid is an antioxidant and / or a lubricant.

[0039] The present invention can select common antioxidants according to the prior art. Further, the antioxidant is one or more of hindered phenol antioxidants, phosphite antioxidants or thioester antioxidants.

[0040] Specifically, the hindered phenol antioxidant is one or more of N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamide) (Irganox 1098), pentaerythritol tetra[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (Irganox 1010), triethylene glycol bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (Iragnox259), n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Iragno 1076) or spiroglycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (ADK AO-80).

[0041] The phosphite antioxidant is one or more of 2,4-di-tert-butylphenol (Irganox 168), bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (PEP-36) or 627A.

[0042] The thioether antioxidant is one or more of distearyl thiodipropionate, dilauryl thiodipropionate or pentaerythritol tetrakis(3-laurylthiopropionate).

[0043] Common lubricants can be selected according to the prior art in the present invention. Further, the lubricant is one or more of calcium stearate, polyethylene wax, silicone oil or silicone masterbatch.

[0044] The present invention also provides a method for preparing the B1-level low-smoke and halogen-free flame retardant composition, comprising the following steps:

[0045] Put the polyolefin resin, compatibilizer, inorganic flame retardant, calcium oxide, dehydrogenation catalyst and processing aid into a mixer in proportion, mix, cool, discharge and granulate to obtain the B1-level low-smoke and halogen-free flame retardant composition.

[0046] Furthermore, the temperature of the internal mixer is 145 - 160 °C.

[0047] Furthermore, the mixing time is not less than 10 min.

[0048] The present invention also protects the application of the B1 - grade low - smoke and halogen - free flame - retardant composition in the preparation of cable sheath materials.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] The present invention provides a B1 - grade low - smoke and halogen - free flame - retardant composition. By adding a dehydrogenation catalyst to the polyolefin resin system, dehydrogenation of the polyolefin substrate into carbon is promoted to form a stable and efficient carbon layer. At the same time, the dehydrogenation catalyst is compounded with a magnesium hydroxide flame retardant, which can effectively reduce the heat release of the sheath material itself and improve the flame - retardant performance of the material. In addition, a small amount of milky calcium hydroxide is generated during the reaction of calcium oxide, forming a film - like structure on the surface of the material to increase the flame - retardant effect. The tensile strength of the B1 - grade low - smoke and halogen - free flame - retardant composition is not less than 10 MPa, and the elongation at break is not less than 160%, meeting the GB / T 32129 - 2015 standard. At the same time, the composition meets the B1 - grade flame retardancy. Detailed implementation manners

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below. However, the implementation manners of the present invention are not limited thereto.

[0052] The reagents, methods, and equipment used in the present invention are all conventional reagents, methods, and equipment in the technical field, unless otherwise specified.

[0053] The raw materials used in the following examples and comparative examples are as follows:

[0054] Polyolefin resin:

[0055] Polyethylene resin 1: Linear low - density polyethylene resin, LLDPE 3527, the comonomer is 1 - hexene, and the melt flow rate at 190 °C and 2.16 kg is 3.5 g / 10 min, and the density is 0.927 g / cm³ 3 ;

[0056] Polyethylene resin 2: Linear low - density polyethylene resin, LLDPE M2735, the comonomer is 1 - butene, and the melt flow rate at 190 °C and 2.16 kg is 2 g / 10 min, and the density is 0.930 g / cm³ 3 ;

[0057] Ethylene - octene copolymer: POE 58750, and the melt index under the conditions of 190 °C and 2.16 kg is 5 g / 10 min;

[0058] Ethylene-vinyl acetate copolymer: Escorene Ultra UL00328, with a melt index of 3 g / 10 min at 190 °C under 2.16 kg, and a vinyl acetate content of 28%;

[0059] Compatibilizer:

[0060] Polyethylene grafted maleic anhydride 1: The maleic anhydride grafting rate is 0.9%, and the residual maleic anhydride is 0.5‰;

[0061] Polyethylene grafted maleic anhydride 2: The maleic anhydride grafting rate is 0.7%, and the residual maleic anhydride is 0.5‰;

[0062] Inorganic flame retardant:

[0063] Magnesium hydroxide 1: Magnesium hydroxide surface-treated with silane coupling agent;

[0064] Self-made in the laboratory; using magnesium hydroxide with the brand of F5 from Shandong Aiful Company; the preparation method is to heat magnesium hydroxide to 60 °C in a high-speed mixer, add 3-aminopropyltriethoxysilane according to the mass ratio of magnesium hydroxide to 3-aminopropyltriethoxysilane of 99:1; mix at high speed for 30 minutes, and the coating rate is 99.5%;

[0065] Magnesium hydroxide 2: F5, magnesium hydroxide purchased from Shandong Aiful Company with the brand of F5.

[0066] Calcium oxide 1: D50 is 3 μm, commercially available;

[0067] Calcium oxide 2: D50 is 4 μm, commercially available;

[0068] Calcium oxide 3: D50 is 5 μm, commercially available;

[0069] Calcium oxide 4: D50 is 8 μm, commercially available;

[0070] Calcium oxide 5: D50 is 10 μm, commercially available;

[0071] Calcium oxide 6: D50 is 11 μm, commercially available;

[0072] Dehydrogenation catalyst: Palladium-aluminum oxide catalyst, RH-33T, purchased from Liaoning Haitai Technology Development Co., Ltd.;

[0073] Dehydrogenation catalyst: Platinum-aluminum oxide catalyst, purchased from Shaanxi Kaida;

[0074] Antioxidant: Using a combination of antioxidant 1010 and antioxidant 168, with a mass ratio of 3:1, from BASF Company, Germany;

[0075] Lubricant: Calcium stearate, commercially available. The same antioxidant and lubricant were used in the parallel experiments of each example and comparative example in the present invention.

[0076] The present invention will be described in detail below in conjunction with examples.

[0077] The following examples and comparative examples were all prepared for the B1 - grade low - smoke and halogen - free flame - retardant composition by the following method: Weigh each component according to the weight ratios shown in Tables 1 - 2; the specific steps are as follows:

[0078] Put the polyethylene resin, polyethylene - grafted maleic anhydride, ethylene - octene copolymer, ethylene - vinyl acetate copolymer, magnesium hydroxide, calcium oxide, dehydrogenation catalyst, antioxidant and lubricant into a mixer according to the proportion and mix until the temperature of the material reaches 145 - 160 °C. The mixer needs to be cooled with water, and the mixing time is not less than 10 minutes. After discharging, put it into a single - screw granulator for granulation, and the granulation method is air - cooled die - face granulation.

[0079] Examples 1 - 12 and Comparative Examples 1 - 9

[0080] Table 1 Dosages of each component in the B1 - grade low - smoke and halogen - free flame - retardant composition of Examples 1 - 12 (parts by weight)

[0081]

[0082]

[0083] Table 2 Dosages of each component in the B1 - grade low - smoke and halogen - free flame - retardant composition of Comparative Examples 1 - 9 (parts by weight)

[0084]

[0085]

[0086] Performance testing

[0087] Press the B1 - grade low - smoke and halogen - free flame - retardant compositions prepared in Examples 1 - 12 and Comparative Examples 1 - 9 on a flat vulcanizer at 180 °C * 10 min, with a pressure of 15 Mpa and a sample thickness of 1 mm. After standing at room temperature for 16 h, test the conventional properties; the cables and cable materials were determined according to the test methods of the low - smoke and halogen - free material standard of GB / T 32129 - 2015 and the B1 flame - retardant grade standard of GB 31247 - 2014. Among them, in the GB / T 32129 - 2015 standard, it is specified that the tensile strength ≥ 10 MPa meets the standard; the elongation at break ≥ 160% meets the standard, and the larger the value under the condition of meeting the standard, the better the effect. In the B1 flame - retardant of GB 31247 - 2014, it is specified that the peak heat release ≤ 30 KW, the total heat release ≤ 15 MJ, the peak smoke production ≤ 0.25 m 2 / s, and the total smoke production ≤ 50 m2 / s passed the test. The test results are shown in Table 3.

[0088] Table 3 Test Results of B1 - grade Low - Smoke and Halogen - Free Flame - Retardant Compositions in Each Example and Comparative Example

[0089]

[0090] It can be seen from Table 3 that the B1 - grade low - smoke and halogen - free flame - retardant composition prepared by the present invention has good comprehensive performance. It not only meets the B1 - grade flame retardancy of GB / T 31247 but also meets the low - smoke and halogen - free material standard of GB / T 32129 - 2015. The tensile strength of the prepared B1 - grade low - smoke and halogen - free flame - retardant composition is not less than 10 MPa, the elongation at break is not less than 160%, and it meets the B1 - grade flame retardancy.

[0091] It can be seen from Examples 1 - 4 that when the D50 of calcium oxide in the B1 - grade low - smoke and halogen - free flame - retardant composition is 5 - 8 μm, the prepared B1 - grade low - smoke and halogen - free flame - retardant composition has better comprehensive performance, its tensile strength is not less than 13 MPa, the elongation at break is not less than 205%, and it meets the B1 - grade flame retardancy.

[0092] By comparing Example 1 and Example 5, it can be seen that when the comonomer of linear polyethylene resin is 1 - hexene, the prepared low - smoke and halogen - free flame - retardant composition has better mechanical properties under the condition of meeting the B1 - grade flame retardancy, with a tensile strength of 11 MPa and an elongation at break of 185%.

[0093] By comparing Example 4 and Example 10, it can be seen that when the maleic anhydride grafting rate of the polyethylene grafted with maleic anhydride is greater than or equal to 0.8%, the prepared low - smoke and halogen - free flame - retardant composition has better mechanical properties under the condition of meeting the B1 - grade flame retardancy, with a tensile strength of 12 MPa and an elongation at break of 195%.

[0094] By comparing Example 4 and Example 11, it can be seen that when the halogen - free flame retardant is surface - treated, the prepared low - smoke and halogen - free flame - retardant composition has better mechanical properties.

[0095] It can be seen from Comparative Example 1 that when the dosage of calcium oxide is too small, although the prepared B1 - grade low - smoke and halogen - free flame - retardant composition has good mechanical properties, it cannot meet the B1 - grade flame retardancy. Because the dosage of calcium oxide is too small, the film - like structure formed by its reaction with moisture is less, resulting in poor flame - retardant performance of the composition and unable to meet the B1 - grade flame retardancy.

[0096] It can be seen from Comparative Example 2 that when the dosage of calcium oxide is excessive, the elongation at break of the obtained B1-level low-smoke halogen-free flame retardant composition decreases, only being 157%, which cannot meet the requirements. This is because when the dosage of added calcium oxide is excessive, calcium oxide will react with the maleic anhydride graft in the resin matrix, resulting in a significant decrease in the mechanical properties of the B1-level low-smoke halogen-free flame retardant composition. During the combustion process, calcium oxide will react with magnesium hydroxide and consume each other, resulting in the inability to meet the B1-level flame retardancy.

[0097] It can be seen from Comparative Example 3 that when the dosage of the dehydrogenation catalyst is small, although the mechanical properties of the obtained B1-level low-smoke halogen-free flame retardant composition are good, it cannot meet the B1-level flame retardancy. This is because when the dosage of the dehydrogenation catalyst is too small, the polyolefin substrate cannot be dehydrogenated to form carbon, and a stable and efficient carbon layer cannot be formed, resulting in poor flame retardant performance of the composition and not meeting the B1-level flame retardancy.

[0098] It can be seen from Comparative Example 4 that when the dosage of the dehydrogenation catalyst is excessive, the tensile strength of the obtained B1-level low-smoke halogen-free flame retardant composition decreases and cannot meet the requirements. This is because the dehydrogenation agent is difficult to disperse in the high-filled powder flame retardant system, resulting in the appearance of agglomeration points, which greatly damage the mechanical properties of the material. The tensile strength of the obtained B1-level low-smoke halogen-free flame retardant composition is only 9.5 MPa.

[0099] It can be seen from Comparative Example 5 that when the D50 of calcium oxide is too small, being 3 μm, both the tensile strength and elongation at break of the obtained B1-level low-smoke halogen-free flame retardant composition cannot meet the requirements. The tensile strength is only 9.4 MPa, and the elongation at break is only 155%.

[0100] It can be seen from Comparative Example 6 that when the D50 of calcium oxide is too large, being 11 μm, both the tensile strength and elongation at break of the obtained B1-level low-smoke halogen-free flame retardant composition decrease significantly. The tensile strength is only 8 MPa, and the elongation at break is only 150%.

[0101] It can be seen from Comparative Example 7 that when platinum alumina is used as the dehydrogenation catalyst, the flame retardant performance of the obtained B1-level low-smoke halogen-free flame retardant composition is poor and cannot meet the B1-level flame retardancy.

[0102] It can be seen from Comparative Example 8 that when calcium oxide is not added, the flame retardant performance of the obtained B1-level low-smoke halogen-free flame retardant composition is poor and cannot meet the B1-level flame retardancy.

[0103] It can be seen from Comparative Example 9 that when the dehydrogenation catalyst is not added, the flame retardant performance of the obtained B1-level low-smoke halogen-free flame retardant composition is poor and cannot meet the B1-level flame retardancy.

[0104] Obviously, the above 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, improvements, etc. 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 B1 - level low - smoke and halogen - free flame - retardant composition, characterized in that, It comprises the following components by weight parts: Wherein the dehydrogenation catalyst is a palladium-aluminum oxide catalyst; the D50 of the calcium oxide is 4-10 μm; the inorganic flame retardant is magnesium hydroxide.

2. The B1 - level low - smoke and halogen - free flame - retardant composition according to claim 1, wherein The D50 of the calcium oxide is 5-8 μm.

3. The B1 - level low - smoke and halogen - free flame - retardant composition according to claim 1, wherein, The polyolefin resin is one or two of polyethylene resin, ethylene-octene copolymer or ethylene-vinyl acetate copolymer.

4. The B1 - grade low - smoke and halogen - free flame - retardant composition according to claim 1, characterized in that, The compatibilizer is polyethylene grafted maleic anhydride.

5. The B1-level low-smoke and halogen-free flame-retardant composition according to claim 1, wherein The processing aid is an antioxidant and / or a lubricant.

6. The B1 - level low - smoke and halogen - free flame - retardant composition according to claim 5, characterized in that, The antioxidant is one or several of hindered phenol antioxidants, phosphite antioxidants or thioester antioxidants.

7. The B1 - level low - smoke and halogen - free flame - retardant composition according to claim 5, wherein The lubricant is one or several of calcium stearate, polyethylene wax, silicone oil or silicone masterbatch.

8. The preparation method of the B1-level low-smoke and halogen-free flame retardant composition according to any one of claims 1 to 7, characterized in that It comprises the following steps: Put the polyolefin resin, compatibilizer, inorganic flame retardant, calcium oxide, dehydrogenation catalyst and processing aid into a mixer in proportion, mix, cool, discharge and pelletize to obtain a B1-level low-smoke and halogen-free flame retardant composition.

9. Use of the B1-level low-smoke and halogen-free flame retardant composition according to any one of claims 1 to 7 in the preparation of cable sheath materials.

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