Flame-retardant diphenoxy phosphate silicone rubber material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of flame-retardant silicone rubber, and particularly relates to a flame-retardant diphenoxy phosphate silicone rubber material as well as a preparation method and application thereof. The flame-retardant diphenoxy phosphate silicone rubber material prepared by the invention is prepared from the following raw materials in parts by mass: 100 parts of polydimethylsiloxane, 10-50 parts of nano carbon black, 80-120 parts of calcium carbonate, 10-30 parts of magnesium hydroxide, 10-30 parts of a phosphate flame retardant, 2-6 parts of dimethyl silicone oil, 1-3 parts of a cross-linking agent, 1-3 parts of a coupling agent and 1-3 parts of a catalyst, and the mass ratio of magnesium hydroxide to the phosphate flame retardant is (1-3): 1. According to the invention, a flame-retardant system formed by compounding magnesium hydroxide, nano carbon black and a phosphate flame retardant is used, so that the flame-retardant effect of the material is improved through a synergistic effect, and meanwhile, adverse effects on mechanical properties are reduced; meanwhile, the nano carbon black is introduced, so that the mechanical property of the silicone rubber is enhanced while the high flame-retardant property is maintained, and the long-standing contradiction between the flame-retardant property and the mechanical property in the industry is solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flame-retardant silicone rubber, and particularly relates to a flame-retardant diphenyloxy phosphoric acid silicone rubber material and a preparation method and application thereof. BACKGROUND

[0002] Silicone rubber is widely used in cable insulation layers due to its excellent high and low temperature resistance, corrosion resistance and electrical insulation. However, silicone rubber is flammable and difficult to self-extinguish (low oxygen index), and it is difficult to meet the flame-retardant requirements of high-voltage transmission lines (such as FV-1 level of GB / T 10707-2008). The prior art improves the flame-retardant properties of the material by adding flame retardants, changing the material composition or blending with other polymer materials. For example, magnesium hydroxide is currently mainly used as a flame retardant. However, this method still has the following defects: (1) High addition amount requirement: more than 30 phr is required to reach FV-0 level, resulting in significant deterioration of mechanical properties (tensile strength, elongation at break); (2) Poor compatibility: Mg(OH)2 is not uniformly dispersed in the silicone rubber matrix, affecting the processing performance; (3) Low flame-retardant efficiency: single Mg(OH)2 has limited effect on extending the time to ignition (TTI).

[0003] Therefore, there is an urgent need in the art for a flame-retardant silicone rubber formulation with excellent comprehensive performance (high mechanical properties and flame-retardant properties) to meet the stringent safety and reliability requirements of cable insulation. SUMMARY

[0004] To meet the needs of the prior art, the application provides a flame-retardant diphenyloxy phosphoric acid silicone rubber material and a preparation method and application thereof. The optimal formulation is selected through multiple formulation experiments, and the rubber material prepared thereby achieves a balance between flame retardancy (FV-1 level) and mechanical properties (tensile strength > 3.2 MPa). The specific formulation includes: a flame-retardant system composed of magnesium hydroxide and diphenyloxy phosphoric acid silicone rubber, which improves the flame-retardant effect through synergistic effect and reduces the adverse effects on mechanical properties; nano-carbon black is introduced to enhance the mechanical properties of silicone rubber, such as tensile strength and elongation at break, and the processing parameters are optimized, such as surface drying time and curing depth.

[0005] Specifically, the application provides the following technical solutions: The first aspect of the present application provides a flame-retardant phosphorus-containing diphenyloxy silicone rubber material, which comprises the following raw materials in parts by mass: 100 parts of polydimethylsiloxane (PDMS), 10-50 parts of nano-carbon black, 80-120 parts of calcium carbonate, 10-30 parts of magnesium hydroxide, 10-30 parts of phosphate flame retardant, 2-6 parts of dimethyl silicone oil, 1-3 parts of cross-linking agent, 1-3 parts of coupling agent and 1-3 parts of catalyst, wherein the mass ratio of the magnesium hydroxide to the phosphate flame retardant is 1-3:1.

[0006] Optionally, the flame-retardant phosphorus-containing diphenyloxy silicone rubber material comprises the following raw materials in parts by mass: 100 parts of polydimethylsiloxane (PDMS), 30 parts of nano-carbon black, 100 parts of calcium carbonate, 20 parts of magnesium hydroxide, 10 parts of phosphate flame retardant, 3 parts of dimethyl silicone oil, 1 part of cross-linking agent, 1 part of coupling agent and 1 part of catalyst, wherein the mass ratio of the magnesium hydroxide to the phosphate flame retardant is 2:1.

[0007] Optionally, the particle size of the nano-carbon black is 7-40 nm.

[0008] Optionally, the phosphate flame retardant is selected from one or more of melamine diphosphonate (MDP) and 1,1'-(1,4-phenylene) bis(3,5-dimethyl-1H-pyrazole) (PBDP).

[0009] Optionally, the cross-linking agent is selected from one or more of methyltributylketoxime silane (KH-301, 95%) and vinyltributylketoxime silane (VOS).

[0010] Optionally, the coupling agent is selected from one or more of 3-aminopropyltrimethoxysilane (KH-540) and ethyl-aminopropyltrimethoxysilane (KH-792).

[0011] Optionally, the catalyst is selected from one or more of dibutyltin laurate and thiol dioctyltin.

[0012] The second aspect of the present application provides a preparation method of the flame-retardant phosphorus-containing diphenyloxy silicone rubber material, which comprises the following steps: mixing polydimethylsiloxane, nano-carbon black, calcium carbonate, magnesium hydroxide and phosphate flame retardant, performing a heating reaction, adding dimethyl silicone oil, cross-linking agent, coupling agent and catalyst after vacuum stirring treatment of the product, and continuously stirring to obtain the flame-retardant phosphorus-containing diphenyloxy silicone rubber material.

[0013] Optionally, the heating reaction is performed at a temperature of 110-120℃ for 0.5-1.5 h; the vacuum stirring treatment is performed at a pressure of <0.0095 Mpa for 2-4 h; and the continuous stirring is performed for 2-4 h.

[0014] Optionally, when the phosphate flame retardant is melamine diphosphonate (MDP), the MDP is prepared by reacting melamine with diphenyl phosphate, and the molar ratio of the melamine to the diphenyl phosphate is 1.1:1.

[0015] Optionally, when the phosphate flame retardant is 1,1'-(1,4-phenylene) bis(3,5-dimethyl-1H-pyrazole) (PBDP), the PBDP is prepared by reacting piperazine with diphenyl phosphate, and the molar ratio of the piperazine to the diphenyl phosphate is 1:2.

[0016] In a third aspect of the present application, the flame-retardant phosphoric acid diphenyloxy silicone rubber material of the first aspect is applied to a cable material.

[0017] In a fourth aspect of the present application, a cable insulation layer is prepared by using the flame-retardant phosphoric acid diphenyloxy silicone rubber material of the first aspect.

[0018] In a fifth aspect of the present application, a preparation method of the cable insulation layer of the fourth aspect is provided, which specifically comprises: performing extrusion molding or coating process on the flame-retardant phosphoric acid diphenyloxy silicone rubber material of the first aspect.

[0019] The beneficial effects of the above one or more technical solutions of the present application are as follows: (1) The synergistic flame-retardant performance of the flame-retardant phosphoric acid diphenyloxy silicone rubber material prepared by the present application is improved. Specifically, by compounding magnesium hydroxide and a phosphate flame retardant (such as MDP or PBDP), a gas phase (endothermic decomposition) and solid phase (char-forming protection) synergistic flame-retardant mechanism is formed, which significantly prolongs the ignition time, reduces the heat release rate and total heat release, and meets the FV-1 level flame-retardant standard. Among them, the decomposition of the phosphate generates polyphosphate, which promotes the formation of a dense carbon film on the surface of the material, and the decomposition of the magnesium hydroxide generates MgO combined with P2O5 to form high-temperature stable Mg2P2O7 (melting point > 1300℃), which further strengthens the thermal stability of the carbon layer.

[0020] (2) The mechanical properties of the flame-retardant phosphoric acid diphenyloxy silicone rubber material prepared by the present application are optimized. By introducing nano-carbon black, the active groups of the carbon black interact with the molecular chains of the silicone rubber, improving the tensile strength (2.88~3.02 MPa) and elongation at break (215~298%), while avoiding the performance degradation caused by traditional high addition amount of magnesium hydroxide (>30 parts). Among them, the carbon black acts as a carbon-forming skeleton, and cooperates with the phosphate flame retardant (such as MDP or PBDP) to form a "carbon black-pyrophosphoric acid salt" composite layer, which enhances the material density (by 50%) and thermal conduction network, disperses local heat, and balances the flame-retardant and mechanical properties.

[0021] (3) The three-component coordination mechanism involved in the technical solution of the present application: 1) Carbon layer reinforcement: Carbon black provides nucleation sites, and the phosphate ester decomposed from MDP crosslinks on its surface to form a graphitized carbon-ceramic composite layer.

[0022] 2) Heat shield synergism: MgO generated by the decomposition of Mg(OH)2 fills the voids of the carbon layer and combines with P2O5 derived from MDP to generate Mg2P2O7 (melting point > 1300°C), significantly improving the thermal stability of the carbon layer.

[0023] 3) Free radical synergistic quenching: Phosphorus-containing free radicals released by MDP capture ·OH in the gas phase, while metal oxides (MgO) adsorbed by carbon black catalyze CO → CO2 conversion, reducing toxic smoke.

[0024] (4) The technical solution of the present application solves the problem of uneven dispersion of traditional flame retardants (such as single Mg(OH)2) by optimizing the ratio of each component in the formula (such as the mass ratio of magnesium hydroxide to phosphate of 1~3:1), improving the uniformity and processing fluidity of the material. At the same time, through vacuum stirring (pressure <0.0095 MPa) and precise temperature control (110~120°C) process, reduce bubbles and defects, ensure the stability of the material structure.

[0025] (5) The phosphorus-based flame retardant used in the present application captures free radicals (such as ·OH) in the gas phase, and carbon black adsorbed MgO catalyzes CO → CO2 conversion, reducing the release of toxic smoke and improving fire safety. Compared with traditional high-filled flame retardant systems, the present application reduces the total amount of flame retardant (such as MDP only 10 parts), reducing the impact on the environment.

[0026] (6) The material prepared by the present application is suitable for high temperature and high safety requirement scenes such as cable insulation layer, and can meet the requirements of flame retardation and mechanical properties under complex working conditions through extrusion or coating process, and has significant industrial application value. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0028] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below with specific examples.

[0029] In the prior art, silicone rubber is itself flammable and not easy to self-extinguish (low oxygen index), and it is difficult to meet the flame-retardant requirements of high-voltage transmission lines, and when adding a flame retardant to improve the flame-retardant performance, the mechanical properties of the material will be deteriorated, therefore, the technical personnel in the field urgently need to prepare a flame-retardant silicone rubber formula with excellent comprehensive performance (with high mechanical properties and flame-retardant properties at the same time) to meet the stringent requirements of cable insulation for safety and reliability.

[0030] Specifically, the present application provides a flame-retardant phosphoric acid diphenyloxy silicone rubber material, which comprises the following raw materials in parts by mass: 100 parts of polydimethylsiloxane, 10-50 parts of nano carbon black, 80-120 parts of calcium carbonate, 10-30 parts of magnesium hydroxide, 10-30 parts of phosphate flame retardant, 5-10 parts of dimethyl silicone oil, 5-10 parts of crosslinking agent, 1-3 parts of coupling agent and 1-3 parts of catalyst, wherein the mass ratio of magnesium hydroxide to phosphate flame retardant is 1-3:1.

[0031] In some embodiments, the nano carbon black can be selected as 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, etc. In some embodiments, the calcium carbonate can be selected as 80 parts, 90 parts, 100 parts, 110 parts, 120 parts, etc. In some embodiments, the magnesium hydroxide can be selected as 10 parts, 20 parts, 30 parts, etc. In some embodiments, the phosphate flame retardant can be selected as 10 parts, 20 parts, 30 parts, etc. In some embodiments, the dimethyl silicone oil can be selected as 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, etc. In some embodiments, the crosslinking agent can be selected as 1 part, 2 parts, 3 parts, etc. In some embodiments, the coupling agent can be selected as 1 part, 2 parts, 3 parts, etc. In some embodiments, the catalyst can be selected as 1 part, 2 parts, 3 parts, etc.

[0032] Example 1 The present embodiment provides a flame-retardant phosphoric acid diphenyloxy silicone rubber material, and a preparation method thereof, which comprises the following steps: (1) Preparation of MDP: 1) Add 150 mL of ethanol-water mixed solvent to a 500 mL three-necked flask, then add 12.60 g of melamine, and perform 85℃ oil bath heating stirring for 30 min in a device equipped with mechanical stirring, condenser tube and thermometer until complete dissolution to obtain a transparent solution; 2) 50.04 g of diphenylphosphoric acid was dissolved in 50 mL of ethanol, preheated to 60°C, then slowly added through a constant pressure dropping funnel (control rate 2 mL / min), maintain temperature 85±2°C, the solution gradually became turbid, after the end of the drop, continue to stir for 1 h, test the end point pH is 5.8~6.2 (melamine pKb1=8.0), stop heating when a large amount of white precipitate appears, the product is cooled to 10°C by ice water bath, filtered, the filter cake is washed with 20 mL of cold ethanol, 20 mL of ether in turn, and dried under vacuum at 80°C for 24 h to obtain a white powder.

[0033] (2) Preparation of the flame-retardant phosphoric acid diphenyloxy silicone rubber material: The flame-retardant phosphoric acid diphenyloxy silicone rubber material prepared in this example includes the following raw materials by mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0034] The specific preparation method is as follows: α, ω-dihydroxy polydimethylsiloxane, nano carbon black, calcium carbonate, magnesium hydroxide, and MDP are added to a reactor, then stirred at 120°C for 1 h. Then continue to stir for 3 h under vacuum condition (<0.095 MPa). Finally, add dimethyl silicone oil, crosslinking agent, coupling agent, and catalyst, and continue to stir for 3 h to complete the packaging.

[0035] Example 2 The preparation method of the flame-retardant phosphoric acid diphenyloxy silicone rubber material provided in this example includes the following steps: (1) Preparation of PBDP: 1) 8.61 g of piperazine (1,4-diazine) solid (0.1 mol, MW=86.1 g / mol) and 100 mL of deionized water were added to a 250 mL three-necked flask, and the device was installed with a mechanical stirrer, a thermometer, and a reflux condenser, and heated with a 80°C water bath and stirred for 10 min until a transparent solution was formed.

[0036] 2) 50 g of diphenylphosphoric acid (0.2 mol, MW = 250.2 g / mol) was added to the transparent solution obtained in step 1) in 4-5 portions (5 min interval each), temperature control 80-85 °C, maintain vigorous stirring (500 rpm) for 1.5 hours, monitor the pH from the initial alkaline (pH ≈ 10) to neutral (pH = 7.0 ± 0.2), found that the solution first became turbid, then white solid precipitated, at this time the pH stabilized at 7.0, then stop heating, ice water bath cooling to 5 °C, reduced pressure suction filtration (0.45 μm filter membrane), then the filter cake was washed with 20 mL of cold ethanol and vacuum dried at 60 °C for 12 h to obtain white crystalline solid.

[0037] (2) Preparation of flame-retardant phosphoric acid diphenyloxy silicone rubber material: The difference between this example and example 1 is that the raw material of the flame-retardant phosphoric acid diphenyloxy silicone rubber material prepared in this example is PBDP instead of MDP, and the rest of the raw material content and the preparation method are exactly the same as those of example 1.

[0038] Example 3 This example provides a flame-retardant phosphoric acid diphenyloxy silicone rubber material The difference between this example and example 1 is that in step (2), the flame-retardant phosphoric acid diphenyloxy silicone rubber material prepared includes the following raw materials by mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 5 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part.

[0039] Example 4 This example provides a flame-retardant phosphoric acid diphenyloxy silicone rubber material The difference between this example and example 2 is that in step (2), the flame-retardant phosphoric acid diphenyloxy silicone rubber material prepared includes the following raw materials by mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, PBDP 5 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part.

[0040] Example 5 This example provides a flame-retardant phosphoric acid diphenyloxy silicone rubber material, and the preparation method thereof includes the following steps: (1) Preparation of MDP: 1) 150 mL of ethanol-water mixed solvent was added to a 500 mL three-necked flask, then 12.60 g of melamine was added, and the device was installed with mechanical stirring, condenser tube and thermometer. Heat stirring at 85 °C oil bath for 30 min until completely dissolved to obtain a transparent solution; 2) 50.04 g of diphenylphosphoric acid was dissolved in 50 mL of ethanol, preheated to 60°C, then slowly added through a constant pressure dropping funnel (control rate 2 mL / min), maintain temperature 85±2°C, the solution gradually became turbid, after the end of the drop, continue to stir for 1 h, test the end point pH is 5.8~6.2 (melamine pKb1=8.0), stop heating when a large amount of white precipitate appears, the product is cooled to 10°C by ice water bath, filtered, the filter cake is washed with 20 mL of cold ethanol, 20 mL of ether, and dried under vacuum at 80°C for 24 h to obtain white powder.

[0041] (2) Preparation of PBDP: 1) In a 250 mL three-necked flask, 8.61 g of piperazine (1,4-diazine) solid (0.1 mol, MW=86.1 g / mol) and 100 mL of deionized water were added, and the device was installed with a mechanical stirrer, a thermometer, and a reflux condenser, and heated with a water bath at 80°C and stirred for 10 min until a transparent solution was formed.

[0042] 2) 50 g of diphenylphosphoric acid (0.2 mol, MW=250.2 g / mol) was added to the transparent solution obtained in step 1) in 4~5 times (5 min interval each time), control temperature 80~85°C, maintain vigorous stirring (500 rpm) for 1.5 h, monitor pH from initial alkaline (pH≈10) to neutral (pH=7.0±0.2), find that the solution first becomes turbid, then white solid precipitates, at this time the pH is stable at 7.0, then stop heating, ice water bath cooling to 5°C, reduced pressure filtration (0.45 μm filter membrane), then the filter cake is washed with 20 mL of cold ethanol and dried under vacuum at 60°C for 12 h to obtain white crystalline solid.

[0043] (3) Preparation of flame-retardant phosphoric acid diphenyloxy silicone rubber material: The flame-retardant phosphoric acid diphenyloxy silicone rubber material prepared in this example includes the following raw materials by mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 10 parts, PBDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0044] The specific preparation method is as follows: α, ω-dihydroxy polydimethylsiloxane, nano carbon black, calcium carbonate, magnesium hydroxide, MDP, and PBDP are added to a reactor, then stirred at 120°C for 1 h. Then continue to stir for 3 h under vacuum condition (<0.0095 Mpa). Finally, add dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part, and continue to stir for 3 h to complete the packaging.

[0045] Comparative Example 1 The comparative example 1 provides a flame-retardant silicone rubber material The comparative example 1 is different from the example 1 in that: in step (2), magnesium hydroxide is not added (the total amount is unchanged), and the prepared flame-retardant phosphorus-containing silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, MDP 30 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0046] Comparative Example 2 The comparative example 2 provides a flame-retardant silicone rubber material The comparative example 2 is different from the example 2 in that: in step (2), magnesium hydroxide is not added (the total amount is unchanged), and the prepared flame-retardant phosphorus-containing silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, PBDP 30 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0047] Comparative Example 3 The comparative example 3 provides a flame-retardant silicone rubber material The comparative example 3 is different from the example 1 in that: in step (2), magnesium hydroxide is not added (the total amount is changed), and the prepared flame-retardant phosphorus-containing silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0048] Comparative Example 4 The comparative example 4 provides a flame-retardant silicone rubber material The comparative example 4 is different from the example 2 in that: in step (2), magnesium hydroxide is not added (the total amount is changed), and the prepared flame-retardant phosphorus-containing silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, PBDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0049] Comparative Example 5 The comparative example 5 provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 1 is that in step (2), MDP is not added (the total amount is unchanged), and the prepared flame-retardant phosphorus-containing diphenyloxy silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 30 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0050] Comparative Example 6 The present comparative example provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 1 is that in step (2), MDP is not added (the total amount is changed), and the prepared flame-retardant phosphorus-containing diphenyloxy silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0051] Comparative Example 7 The present comparative example provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 1 is that in step (2), nano carbon black is not added (the total amount is unchanged), and the prepared flame-retardant phosphorus-containing diphenyloxy silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 40 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0052] Comparative Example 8 The present comparative example provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 1 is that in step (2), nano carbon black is not added (the total amount is changed), and the prepared flame-retardant phosphorus-containing diphenyloxy silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0053] Comparative Example 9 The present comparative example provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 1 is that in step (2), nano carbon black is not added (the total amount is unchanged), and the prepared flame-retardant phosphorus-containing diphenyloxy silicone rubber material includes the following raw materials in mass fraction: α, ω-dihydroxy polydimethylsiloxane 100 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, PBDP 40 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0054] Comparative Example 10 The present comparative example provides a flame-retardant silicone rubber material The present comparative example differs from Example 2 in that, in step (2), no nano-carbon black (total amount changed) is added. The flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared specifically includes the following raw materials in parts by mass: a, w-dihydroxypolydimethylsiloxane 100 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, PBDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0055] Comparative Example 11 The present comparative example provides a flame-retardant silicone rubber material The present comparative example differs from Example 1 in that, in step (2), no magnesium hydroxide and MDP (total amount changed) is added. The flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared specifically includes the following raw materials in parts by mass: a, w-dihydroxypolydimethylsiloxane 100 parts, nano-carbon black 30 parts, calcium carbonate 100 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0056] Comparative Example 12 The present comparative example provides a flame-retardant silicone rubber material The present comparative example differs from Example 1 in that, in step (2), no magnesium hydroxide and MDP (total amount unchanged) is added. The flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared specifically includes the following raw materials in parts by mass: a, w-dihydroxypolydimethylsiloxane 100 parts, nano-carbon black 60 parts, calcium carbonate 100 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0057] Comparative Example 13 The present comparative example provides a flame-retardant silicone rubber material The present comparative example differs from Example 1 in that, in step (2), no nano-carbon black and MDP (only magnesium hydroxide is added, total amount changed) is added. The flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared specifically includes the following raw materials in parts by mass: a, w-dihydroxypolydimethylsiloxane 100 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0058] Comparative Example 14 The present comparative example provides a flame-retardant silicone rubber material The present comparative example differs from Example 1 in that, in step (2), no nano-carbon black and MDP (total amount unchanged) is added. The flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared specifically includes the following raw materials in parts by mass: a, w-dihydroxypolydimethylsiloxane 100 parts, calcium carbonate 100 parts, magnesium hydroxide 60 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0059] Comparative Example 15 The comparative example 1 provides a flame-retardant silicone rubber material The comparative example 1 is different from example 1 in that: in step (2), the nano carbon black and magnesium hydroxide are not added (the total amount is changed), and the prepared flame-retardant phosphoric acid diphenyloxy silicone rubber material includes the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, calcium carbonate 100 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part.

[0060] Comparative Example 16 The comparative example 1 provides a flame-retardant silicone rubber material The comparative example 1 is different from example 1 in that: in step (2), the nano carbon black and MDP are not added (the total amount is changed), and the prepared flame-retardant phosphoric acid diphenyloxy silicone rubber material includes the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, calcium carbonate 100 parts, MDP 60 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part.

[0061] Comparative Example 17 The comparative example 1 provides a flame-retardant silicone rubber material The comparative example 1 is different from example 1 in that: in step (2), the amount of magnesium hydroxide is changed, and the prepared flame-retardant phosphoric acid diphenyloxy silicone rubber material includes the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 35 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part.

[0062] Comparative Example 18 The comparative example 1 provides a flame-retardant silicone rubber material The comparative example 1 is different from example 1 in that: in step (2), the amount of magnesium hydroxide is changed, and the prepared flame-retardant phosphoric acid diphenyloxy silicone rubber material includes the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 10 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part.

[0063] Comparative Example 19 The comparative example 1 provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 2 is that in step (2), the addition amount of nano-carbon black is changed. Specifically, the flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared according to the present comparative example comprises the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, nano-carbon black 40 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0064] Comparative Example 20 The present comparative example provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 2 is that in step (2), the addition amount of nano-carbon black is changed. Specifically, the flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared according to the present comparative example comprises the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, nano-carbon black 40 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0065] Comparative Example 21 The present comparative example provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 2 is that in step (2), the addition amount of nano-carbon black is changed. Specifically, the flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared according to the present comparative example comprises the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, nano-carbon black 40 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0066] Comparative Example 22 The present comparative example provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 2 is that in step (2), the addition amount of nano-carbon black is changed. Specifically, the flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared according to the present comparative example comprises the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, nano-carbon black 40 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0067] Comparative Example 23 The present comparative example provides a flame-retardant silicone rubber material The difference between the present comparative example and Example 2 is that in step (2), the addition amount of nano-carbon black is changed. Specifically, the flame-retardant phosphorus-containing diphenyloxy silicone rubber material prepared according to the present comparative example comprises the following raw materials by mass fraction: a, w-dihydroxy polydimethylsiloxane 100 parts, nano-carbon black 40 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, MDP 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part, and catalyst 1 part.

[0068] Comparative Example 24 The comparative example 1 provides a flame-retardant silicone rubber material The comparative example 1 is different from the example 1 in that: in step (2), no MDP is added and the amount of nano-carbon black is changed. The flame-retardant phosphorus-containing silicone rubber material prepared in the comparative example 1 includes the following raw materials in parts by mass: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano-carbon black 50 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part.

[0069] Comparative Example 25 The comparative example 1 provides a flame-retardant silicone rubber material The comparative example 1 is different from the example 1 in that: in step (2), no MDP is added and the amount of nano-carbon black is changed. The flame-retardant phosphorus-containing silicone rubber material prepared in the comparative example 1 includes the following raw materials in parts by mass: α, ω-dihydroxy polydimethylsiloxane 100 parts, nano-carbon black 50 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part.

[0070] Experimental Example 1 The example 1 provides the specific amount of each raw material of the flame-retardant silicone rubber material prepared in the example 1~5 and the comparative example 1~25, as shown in Table 1 and Table 2: Table 1

[0071] Table 2

[0072] Experimental Example 1 The test example 1 provides the exploration of the mechanical properties and the flame-retardant properties of the flame-retardant silicone rubber material prepared in the example 1~5 and the comparative example 1~25 (1) The mechanical property test, the surface drying property and the curing depth property index are tested under the laboratory conditions of 25±2℃ and 50±5% humidity. The surface drying time is tested according to the standard GB / T13477.5-2002; the curing depth is tested according to the standard GB / T32369-2015; the shore hardness is tested according to GB / T2411-2008; the tensile strength and the elongation at break are tested according to GB / T528-2009; and the tensile shear strength is tested according to GB / T-13936-2014.

[0073] The specific test data is shown in Table 3: Table 3

[0074] (2) Flame retardant performance test, according to GB / T10707-2008 for testing, the specific test data as shown in Table 4: Table 4

[0075] From the data analysis of Table 3~4: Compared with Example 1, the performance balance of Example 2~5 still has deficiencies, the proportion between the components needs to be accurately controlled to meet the demand of the silicone rubber material with strong mechanical properties and flame retardant properties.

[0076] Compared with Examples 1~5, Comp. 1~4 do not add flame retardant magnesium hydroxide, Comp. 5~6 do not add diphenyl phosphate sample (MDP), Comp. 11~12 do not add magnesium hydroxide and MDP, and Comp. 17~18 change the amount of magnesium hydroxide added. From the performance test results, it can be seen that the addition of MDP significantly prolongs the ignition time (TTI), and the auxiliary role and limitation of magnesium hydroxide are limited when used alone: without MDP, magnesium hydroxide only slightly improves TTI but weakly suppresses heat release. The reason is that magnesium hydroxide mainly reduces temperature through endothermic decomposition, but has no carbonization ability.

[0077] Compared with Examples 1~5, Comp. 7~10 do not add nano carbon black, Comp. 13~14 do not add nano carbon black and MDP, Comp. 19~20 change the amount of nano carbon black added, and Comp. 21~24 change the amount of nano carbon black added and do not add MDP. From the performance test results, it can be seen that nano carbon black and MDP have a synergistic effect, and there is a dual nature in the flame retardant material: appropriate addition can significantly improve the flame retardant property, but excessive amount will seriously damage the mechanical property. This contradiction is due to the conflict of physical action and chemical structure interference in the material, which needs to be balanced by precise control of the amount. When the nano carbon black is added in an appropriate amount, the nano carbon black acts as a carbon skeleton, adsorbs the polyphosphate generated by the pyrolysis of MDP, and then forms a "carbon black-pyrophosphate" composite carbon layer, whose density is increased by 50%. Secondly, the nano carbon black forms a percolation heat conduction network, quickly disperses the local heat of combustion, and then delays the decomposition rate of MDP, prolonging the flame retardant effect time. But when the nano carbon black is excessive, the excessive carbon agglomeration will destroy the continuous expansion carbon layer generated by MDP, increase the oxygen permeation channel, and the carbon black will preferentially adsorb the PDMS molecular chain, blocking the contact between MDP and the polymer, eventually delaying and incomplete decomposition of MDP.

[0078] Compared with examples 1~5, no nano-carbon black and magnesium hydroxide were added in comparative examples 15~16, it can be seen that the flame retardant performance and mechanical properties are poor, magnesium hydroxide (MH) will absorb a large amount of heat when decomposed under heat (340~490℃), release water vapor to dilute oxygen and combustible gas, and at the same time generate MgO protective layer on the surface of the material to isolate heat and oxygen. Without adding MH, the material lacks this gas phase (endothermic, dilution) and solid phase (carbon barrier) synergistic flame retardant mechanism, resulting in a significant increase in heat release rate (HRR) and total heat release (THR), and nano-carbon black can promote the formation of dense carbon layer, improve the melt viscosity, and delay the combustion dripping. Its high specific surface area can also absorb free radicals to inhibit the combustion chain reaction. Without adding, the carbon layer is loose and easy to break during combustion, and the flame retardant efficiency is greatly reduced.

[0079] At the same time, according to the experimental results, the ignition time (TTI) of the heat vulcanized rubber without adding flame retardant (comparative example 11) is 19 seconds. The ignition time (TTI) of the room temperature vulcanized rubber added with flame retardant (comparative example 17 and comparative example 18) is longer than that of comparative example 11. From the experimental results, compared with the addition of magnesium hydroxide, the addition of phosphorus-based flame retardant further prolongs the ignition time of the vulcanized rubber (comparative example 17 and comparative example 5). The addition of phosphate can effectively prolong the ignition time of the room temperature vulcanized rubber. The reason may be that the silicone rubber releases substances such as phosphoric acid and polyphosphoric acid during heating, which causes the polymeric material to dehydrate and carbonize, forming a protective carbon film on the surface of the material, thereby delaying the combustion process. At the same time, adding magnesium hydroxide or MDP to the sample can effectively reduce the peak heat release rate of the rubber, and the total heat release (THR) refers to the total heat released during the ignition of the material to the extinction of the flame. Under the condition of heating, the polyphosphoric acid and phosphoric acid formed by the decomposition of phosphate capture the fragments generated by the decomposition of silicone rubber.

[0080] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A flame-retardant diphenyloxyphosphine silicone rubber material, characterized by, The raw materials include the following by mass fraction: polydimethylsiloxane 100 parts, nano carbon black 10-50 parts, calcium carbonate 80-120 parts, magnesium hydroxide 10-30 parts, phosphate flame retardant 10-30 parts, dimethyl silicone oil 2-6 parts, crosslinking agent 1-3 parts, coupling agent 1-3 parts and catalyst 1-3 parts, wherein the mass ratio of the magnesium hydroxide to the phosphate flame retardant is (1-3):

1.

2. The flame retardant phosphonic acid diphenyloxy silicone rubber material according to claim 1, wherein, The raw materials include the following by mass fraction: polydimethylsiloxane 100 parts, nano carbon black 30 parts, calcium carbonate 100 parts, magnesium hydroxide 20 parts, phosphate flame retardant 10 parts, dimethyl silicone oil 3 parts, crosslinking agent 1 part, coupling agent 1 part and catalyst 1 part, wherein the mass ratio of the magnesium hydroxide to the phosphate flame retardant is 2:

1.

3. The flame retardant phosphonic di-phenoxy silicone rubber material of claim 1, wherein, The particle size of the nano carbon black is 7-40 nm; The phosphate flame retardant is selected from one or more of melamine diphosphonate, 1,1'-(1,4-phenylene) bis(3,5-dimethyl-1H-pyrazole); The crosslinking agent is selected from one or more of methyltributanone oxime silane, vinyltributanone oxime silane; The coupling agent is selected from one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane; The catalyst is selected from one or more of dibutyltin laurate, thiol dioctyl tin.

4. A process for the preparation of the flame-retardant phosphonic di-phenyl-siloxane rubber material according to any one of claims 1 to 3, characterized in that, The method includes the following steps: The polydimethylsiloxane, nano carbon black, calcium carbonate, magnesium hydroxide and phosphate flame retardant are mixed and heated to react, and then the dimethyl silicone oil, crosslinking agent, coupling agent and catalyst are added after vacuum stirring treatment, and then continuous stirring is performed to obtain the product.

5. The production method according to claim 4, wherein The temperature of the heating reaction is 110-120℃, and the time is 0.5-1.5 h; the pressure of the vacuum stirring treatment is less than 0.0095 Mpa, and the time is 2-4 h; the time of the continuous stirring is 2-4 h.

6. The production method according to claim 4, wherein When the phosphate flame retardant is melamine diphosphonate, the MDP is prepared by reacting melamine with diphenyl phosphate, and the molar ratio of the melamine to the diphenyl phosphate is 1.1:

1.

7. The production method according to claim 4, wherein When the phosphate flame retardant is 1,1'-(1,4-phenylene) bis(3,5-dimethyl-1H-pyrazole), the PBDP is prepared by reacting piperazine with diphenyl phosphate, and the molar ratio of the piperazine to the diphenyl phosphate is 1:

2.

8. The application of the flame-retardant phosphoric acid diphenyloxy silicone rubber material in any one of claims 1-3 in cable materials.

9. A cable insulation layer, characterized by The flame-retardant phosphoric acid diphenyloxy silicone rubber material in any one of claims 1-3 is used.

10. A process for the preparation of a cable insulation layer as claimed in claim 9, characterized in that Specifically, the flame-retardant phosphoric acid diphenyloxy silicone rubber material in any one of claims 1-3 is subjected to extrusion molding or coating process to obtain the product.

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