Preparation method of high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interface crosslinking

Abstract

The invention discloses a preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of a flame retardant and synergistic interface crosslinking, which comprises the following steps: mixing raw rubber, sulfur, a vulcanizing aid and an anti-aging agent to obtain a rubber compound with high vulcanizing agent addition amount; mixing, vulcanizing and crushing the rubber compound with a high vulcanizing agent addition amount and a flame retardant to obtain flame-retardant rubber particles rich in dynamic sulfur bonds; and mixing and vulcanizing the flame-retardant rubber particles rich in dynamic sulfur bonds, raw rubber, sulfur and a vulcanizing agent to obtain the high-performance flame-retardant rubber composite material with controlled distribution of the flame retardant and synergistic interface crosslinking. According to the invention, a two-phase composite material is composed of a hard flame-retardant phase and a soft non-flame-retardant phase, so that the influence of the flame retardant on a rubber matrix is reduced, and the obtained high-performance flame-retardant rubber composite material with controlled distribution of the flame retardant and synergistic interface crosslinking has comprehensive performance superior to that of a traditional carbon black flame-retardant formula; such as high mechanical property, high flame retardance, high rebound resilience, low creep deformation, excellent low-temperature rigidity performance and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of rubber materials. Specifically, the present invention relates to a preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and synergistic interfacial crosslinking. Background Art

[0002] Rubber materials are widely used in many fields such as rail transit, aerospace, construction, and electronic devices due to their good elasticity, wear resistance, and insulation. However, ordinary rubber materials are prone to combustion and release a large amount of heat and toxic gases during combustion. With the continuous improvement of safety requirements in industrial and living fields, rubber products need to have flame-retardant properties in many application scenarios. Traditional flame-retardant rubber materials mainly achieve this by adding flame retardants, but there are problems such as a large amount of flame retardant added and poor compatibility with the elastomer matrix, which affect the physical properties and long-term use stability of the elastomer. Therefore, it is necessary to develop a new flame-retardant technology to overcome these defects.

[0003] In response to the problem of the decline in the comprehensive performance of flame-retardant rubber composites, researchers have made many attempts, but they have all focused on the development and modification of flame retardants, and the effects achieved are also very limited. In the research of polymer composites where the filler and the matrix are incompatible, the selective distribution of the adjustable functional filler in a certain phase can be used to reduce the influence of the filler on the substrate, and the effect of the filler is usually limited to the expansion of its own characteristics. Different from ordinary fillers, the functionality of flame retardants is usually only manifested at high temperatures. At present, there is no research and practical application related to the effect of flame retardants selectively distributed at high temperatures, and further, the impact on the comprehensive performance of the overall flame-retardant material is completely unclear. Therefore, using rubber as the matrix to develop a preparation method and application expansion of a flame-retardant and high-performance rubber composite material based on the selective distribution of flame retardants is not only of great significance to the rubber industry, but also of great significance to the research and application expansion of flame retardancy and high performance of other thermosetting materials. Summary of the Invention

[0004] An object of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0005] To achieve these objects and other advantages of the present invention, a preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and synergistic interfacial crosslinking is provided, including the following steps:

[0006] Step 1: Mix raw rubber, sulfur, vulcanization aids, and anti-aging agents to obtain a mixed rubber with a high sulfur agent addition amount;

[0007] Step 2: Mix, vulcanize, and pulverize the mixed rubber with a high sulfur agent addition amount and a flame retardant to obtain flame-retardant rubber particles rich in dynamic sulfur bonds;

[0008] Step 3: Knead and vulcanize the flame-retardant rubber particles rich in dynamic sulfur bonds, raw rubber, sulfur, and vulcanization aids to obtain a high-performance flame-retardant rubber composite with a controlled distribution of flame retardants and synergistic interfacial crosslinking.

[0009] Preferably, the raw rubber is one or more of ethylene propylene diene monomer rubber, natural rubber, styrene butadiene rubber, polybutadiene rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, polynorbornene, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, epoxidized styrene / isoprene block copolymer.

[0010] Preferably, the vulcanization aids are activators and accelerators.

[0011] Preferably, the activator is zinc oxide and stearic acid, and the mass ratio of zinc oxide to stearic acid is 4 - 6:1; the accelerator is one or more of accelerator CZ, accelerator TMTD, accelerator DM, accelerator NOBS, accelerator D, accelerator M, accelerator ZDC, accelerator NS.

[0012] Preferably, the anti-aging agent is one or more of anti-aging agent 4010NA, anti-aging agent 4020, anti-aging agent RD, anti-aging agent 264, anti-aging agent 2246, anti-aging agent DLTDP, anti-aging agent Irgafos 168, anti-aging agent BLE-C, anti-aging agent 445, anti-aging agent MB.

[0013] Preferably, in Step 2, the flame retardant is one or more of ammonium polyphosphate, pentaerythritol, aluminum hypophosphite, expandable graphite, melamine, melamine cyanurate, phytic acid, aluminum hydroxide, magnesium hydroxide, decabromodiphenyl ether, carbon nanotubes, montmorillonite.

[0014] Preferably, in Step 1, the mass ratio of raw rubber, sulfur, activator, and anti-aging agent is 100:2 - 40:1 - 10:1 - 10; the mass ratio of sulfur to accelerator is 2 - 8:1.

[0015] Preferably, in Step 2, the mass ratio of the high-vulcanizing agent addition kneaded rubber to the flame retardant is 1 - 3:1 - 2.

[0016] Preferably, in Step 3, the mass ratio of raw rubber, flame-retardant rubber particles rich in dynamic sulfur bonds, sulfur, and activator is 100:100 - 800:0.5 - 20:0.5 - 5; the mass ratio of sulfur to accelerator is 1 - 8:1.

[0017] Preferably, in Step 1, the kneading is carried out on a two-roll mill at 30 °C for 5 - 30 min;

[0018] In the second step, the mixing is carried out on an open mill at 30 °C for 10 - 50 min; the vulcanization temperature is 130 - 180 °C, and the time is the optimum vulcanization time; it is crushed to a particle size of 10 - 1000 μm.

[0019] In the third step, the mixing is carried out on an open mill at 30 °C for 10 - 50 min; the vulcanization temperature is 130 - 180 °C, and the time is the optimum vulcanization time.

[0020] The present invention has at least the following beneficial effects:

[0021] (1) The preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking provided by the present invention adds a flame retardant to a rubber material crosslinked with a large amount of sulfur, and is crushed to form flame-retardant rubber particles containing a large number of dynamic sulfur bonds (disulfide bonds and polysulfide bonds). Then, the flame-retardant rubber particles are used as fillers and kneaded and vulcanized with raw rubber, a small amount of sulfur, accelerators, etc. Based on the interfacial crosslinking reaction between the flame-retardant rubber particles and the surface of the raw rubber, a two-phase composite material composed of a hard flame-retardant phase and a soft non-flame-retardant phase is constructed. Due to the existence of the crosslinking density difference between the two phases, the flame retardant will be restricted in the high-crosslinking phase and cannot migrate freely, thereby reducing the influence of the flame retardant on the rubber matrix. The obtained high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking has comprehensive properties superior to those of traditional carbon black flame-retardant formulations, such as high mechanical properties, high flame retardancy, high resilience, low creep, excellent low-temperature stiffness performance, etc.

[0022] (2) For the high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking provided by the present invention, due to the strong interfacial crosslinking between the flame-retardant high-crosslinking hard phase and the soft matrix, the hard flame-retardant phase can replace the reinforcing effect of carbon black on the rubber matrix in the traditional rubber formulation. Without adding carbon black or even reducing its addition, the rubber can be flame-retarded and strengthened simultaneously. The reduction of the carbon black filling amount can significantly reduce the defects caused by fillers in the composite material, including: reducing the friction between rubber molecular chains and rigid carbon black during the dynamic process, thereby reducing the dynamic heat generation. The fatigue resistance of the high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking is significantly better than that of traditional carbon black flame-retardant formulations and significantly better than that of traditional flame-retardant rubbers.

[0023] (3) The preparation method of the high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking provided by the present invention has raw materials directly from the traditional rubber industry, a simple preparation process, does not require any special processing equipment, is applicable to all flame-retardant fillers, has good versatility, and can be used in industrial production.

[0024] Other advantages, objectives, and features of the present invention will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present invention. Detailed implementation mode

[0025] The following further detailed description is made of the present invention so that those skilled in the art can implement it according to the text of the specification.

[0026] It should be understood that terms such as "having", "comprising", and "including" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0027] The raw materials used in Examples 1 to 3 are shown in Tables 1 and 2.

[0028] Table 1 Raw materials used for flame-retardant rubber particles B11 - B13 rich in dynamic sulfur bonds

[0029] Flame-retardant rubber particles rich in dynamic sulfur bonds B11 B12 B13 Masterbatch with high vulcanizing agent addition (g) 100 230 300 Flame retardant (g) 100 165 200

[0030] Table 2 Raw materials used for high-performance flame-retardant rubber composites C11 - C13 with controlled distribution of flame retardants and synergistic interfacial crosslinking

[0031]

[0032] Example 1

[0033] A preparation method for a high-performance flame-retardant rubber composite with controlled distribution of flame retardants and synergistic interfacial crosslinking includes the following steps:

[0034] Step 1: Prepare a masterbatch with a high vulcanizing agent addition amount

[0035] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ, and 50 g of sulfur, add them to an open mill and mix at 30°C for 10 min to obtain a masterbatch with a high vulcanizing agent addition amount;

[0036] Step 2: Prepare flame-retardant rubber particles B11 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds)

[0037] Take 100 g of the masterbatch with a high vulcanizing agent addition amount and 100 g of a flame retardant (ammonium polyphosphate and pentaerythritol mixed in a mass ratio of 3:1) according to the amounts in Table 1, add them to an open mill, mix at 30°C for 20 min, then perform mold pressing and vulcanization on a flat vulcanizer at 143°C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame-retardant rubber particles B11 rich in dynamic sulfur bonds;

[0038] Step 3: Add all the flame-retardant rubber particles B11 rich in dynamic sulfur bonds obtained in Step 2, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ to the open mill according to the dosages in Table 2, mix for 15 min at 30 °C, add the obtained mixed rubber to the flat vulcanizer, and perform mold pressing vulcanization at 143 °C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite material C11 with controlled distribution of flame retardant and synergistic interfacial crosslinking.

[0039] Example 2

[0040] A preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking includes the following steps:

[0041] Step 1: Prepare a mixed rubber with a high sulfur vulcanizing agent addition amount

[0042] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ, and 50 g of sulfur, add them to the open mill, and mix for 10 min at 30 °C to obtain a mixed rubber with a high sulfur vulcanizing agent addition amount;

[0043] Step 2: Prepare flame-retardant rubber particles B12 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds)

[0044] Take 230 g of the mixed rubber with a high sulfur vulcanizing agent addition amount and 165 g of a flame retardant (ammonium polyphosphate and pentaerythritol are mixed at a mass ratio of 3:1) according to the dosages in Table 1, add them to the open mill, mix for 20 min at 30 °C, then perform mold pressing vulcanization on the flat vulcanizer at 143 °C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame-retardant rubber particles B12 rich in dynamic sulfur bonds;

[0045] Step 3: Take all the flame-retardant rubber particles B12 rich in dynamic sulfur bonds obtained in Step 2, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ and add them to the open mill according to the dosages in Table 2, mix for 15 min at 30 °C, add the obtained mixed rubber to the flat vulcanizer, and perform mold pressing vulcanization at 143 °C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite material C12 with controlled distribution of flame retardant and synergistic interfacial crosslinking.

[0046] Example 3

[0047] A preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking includes the following steps:

[0048] Step 1: Prepare a mixed rubber with a high sulfur vulcanizing agent addition amount

[0049] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ, and 50 g of sulfur. Add them to an open mill and mix at 30°C for 10 min to obtain a rubber compound with a high vulcanizing agent addition amount.

[0050] Step 2: Prepare flame-retardant rubber particles B13 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds).

[0051] Take 300 g of the rubber compound with a high vulcanizing agent addition amount and 200 g of a flame retardant (ammonium polyphosphate and pentaerythritol mixed in a mass ratio of 3:1) according to the amounts in Table 1. Add them to an open mill and mix at 30°C for 20 min. Then, use a flat vulcanizer to perform mold pressing vulcanization at 143°C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame-retardant rubber particles B13 rich in dynamic sulfur bonds.

[0052] Step 3: Take all the flame-retardant rubber particles B13 rich in dynamic sulfur bonds obtained in Step 2, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ according to the amounts in Table 2 and add them to an open mill. Mix at 30°C for 15 min. Add the obtained rubber compound to a flat vulcanizer and perform mold pressing vulcanization at 143°C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite material C13 with controlled distribution and synergistic interfacial crosslinking of the flame retardant.

[0053] Comparative Example 1

[0054] A preparation method of crosslinked rubber includes:

[0055] Take 100 g of natural rubber, 50 g of carbon black, 5 g of zinc oxide, 1 g of stearic acid, 2 g of antioxidant 4010NA, 1.5 g of accelerator CZ, and 2 g of sulfur. Add them to an open mill and mix at 30°C for 20 min. Add the obtained rubber compound to a flat vulcanizer and perform mold pressing vulcanization at 143°C according to the optimum vulcanization time to obtain crosslinked rubber CM1.

[0056] Comparative Example 2

[0057] A preparation method of flame-retardant crosslinked rubber includes:

[0058] Take 100 g of natural rubber, 50 g of carbon black, 50 g of a flame retardant (ammonium polyphosphate and pentaerythritol mixed in a mass ratio of 3:1), 5 g of zinc oxide, 1 g of stearic acid, 2 g of antioxidant 4010NA, 1.5 g of accelerator CZ, and 2 g of sulfur. Add them to an open mill and mix at 30°C for 20 min. Add the obtained rubber compound to a flat vulcanizer and perform mold pressing vulcanization at 143°C according to the optimum vulcanization time to obtain flame-retardant crosslinked rubber CM2.

[0059] Comparative Example 3

[0060] A preparation method of a flame-retardant crosslinked rubber, comprising:

[0061] Take 100 g of natural rubber, 50 g of a flame retardant (ammonium polyphosphate and pentaerythritol mixed in a mass ratio of 3:1), 5 g of zinc oxide, 1 g of stearic acid, 2 g of antioxidant 4010NA, 1.5 g of accelerator CZ, and 2 g of sulfur, add them to an open mill and mix at 30°C for 20 min. The obtained mixed rubber is added to a flat vulcanizer and molded and vulcanized at 143°C according to the optimum vulcanization time to obtain the flame-retardant crosslinked rubber CM3.

[0062] Test the mechanical properties and flame retardancy of the high-performance flame-retardant rubber composites with controlled distribution and synergistic interfacial crosslinking of the flame retardants in Examples 1 to 3 and the traditional non-flame-retardant formula rubbers and traditional flame-retardant formula rubbers prepared in Comparative Examples 1 to 3. The specific test methods are as follows:

[0063] Determination of the optimum vulcanization time: Use a rotorless vulcanizer to determine the optimum vulcanization time of the sample to be tested at 143°C;

[0064] Tensile strength test: The test is carried out on an INSTRON 3366 tensile machine. The test standard is GB / T528-2009, the test temperature is room temperature, the tensile rate is 500 mm / min, at least 5 parallel tests are carried out, and the average value is taken;

[0065] Elongation at break test: The test is carried out on an INSTRON 3366 tensile machine. The test standard is GB / T 528-2009, the test temperature is room temperature, the tensile rate is 500 mm / min, at least 5 parallel tests are carried out, and the average value is taken;

[0066] Shore hardness test: The test is carried out using a Type A Shore hardness tester. The test temperature is room temperature, and the test standard is GB / T531.1-2008.

[0067] Limiting oxygen index test: The test is carried out on a JF-6 type full-automatic oxygen index tester. The test standard is GB / T10707-2008.

[0068] Vertical burning test: The test is carried out on a KB-RS horizontal and vertical burning test machine. The test standard is GB / T10707-2008.

[0069] Cone calorimetry test: The test is carried out on an icone full-automatic cone calorimeter. The test standard is ISO 5660-1.

[0070] Low-temperature stiffness performance test: The test is carried out on a GT-7008-GM Gimmen torsion test machine. The test temperature range is -70°C to 23°C, and the heating rate is 1°C / min.

[0071] Abrasion resistance test: The test was carried out on a GT-7012-D type DIN abrasion testing machine. The test standard was GB / T9867-2008, the rotation speed was 40 rpm, the stroke was 40 m, and the pressure was 10 N.

[0072] Heat build-up under compression test: The test was carried out on an RHU-2000N heat build-up under compression testing machine. The test standard was GB / T1687.3-2016, the initial temperature was room temperature, the stroke was 4.45 mm, the pre-stress was 1 MPa, and the compression frequency was 30 Hz.

[0073] Dynamic compression creep test: The test was carried out on an RHU-2000N heat build-up under compression testing machine. The test standard was GB / T1687.3-2016, the initial temperature was room temperature, the stroke was 4.45 mm, the pre-stress was 1 MPa, and the compression frequency was 30 Hz.

[0074] Tensile fatigue test: The test was carried out on an HDT2548 high-frequency fatigue testing machine. The test standard was GB / T 1688-2008, the tensile frequency was a 5 Hz sine wave, and the test strain was 120%.

[0075] Table 3 Performance test results of high-performance flame-retardant rubber composites C11 - C13 with controlled distribution of flame retardants and synergistic interfacial cross-linking and reference rubbers CM1 - CM3

[0076]

[0077] Table 4 Performance test results of high-performance flame-retardant rubber composite C12 with controlled distribution of flame retardants and synergistic interfacial cross-linking and reference rubbers CM1 - CM3

[0078]

[0079] Table 5 Flame-retardant test results of high-performance flame-retardant rubber composite C12 with controlled distribution of flame retardants and synergistic interfacial cross-linking and reference rubbers CM1 - CM3

[0080] C12 CM1 CM2 CM3 Limiting oxygen index 28％ 18％ 27％ 28％ UL94 rating V-0 NR V-0 V-0 Ignition time TTI (sec) 67 15 39 32 <![CDATA[Peak heat release rate PHRR (kW / m 2 )]]> 289.44 1122.5 604.96 288.34 <![CDATA[Total Heat Release THR (MJ / m 2 )]]> 80.17 87.5 65.91 69.31 <![CDATA[Total smoke generation amount TSP (m 2 )]]> 16.4 18.5 18.19 13.81

[0081] Combined with Table 2 and the reference sample formula, it can be seen that except for the cross-linking density and phase structure, the formula of CM3 is the same as that of C12. From Table 3 and Table 4, it can be seen that compared with CM3 with a similar formula and the traditional flame-retardant formula CM2, the rubber composite C12 with a controlled distribution of flame retardants has a higher tensile strength, a hardness closer to that of the traditional non-flame-retardant carbon black-filled rubber CM1, lower abrasion, more excellent low-temperature stiffness performance, lower heat build-up under dynamic compression, lower dynamic compression creep, and a fatigue life comparable to that of the traditional non-flame-retardant carbon black-filled rubber CM1.

[0082] Comparing the mechanical properties of C11 - C13, it can be found that as the content of flame - retardant rubber particles increases, the tensile strength of the flame - retardant interfacial cross - linked rubber first increases and then decreases, and the elongation at break decreases. This is because as the content of flame - retardant rubber particles increases, the cross - link density of the high - performance flame - retardant rubber composite with controlled distribution of flame - retardants and synergistic interfacial cross - linking is improved. When the cross - link density is low, the interfacial cross - link strength between the two phases is low, and the strength of the composite material is low; when the cross - link density is too high, the material becomes brittle and the material strength also decreases. Therefore, there is a trend of first increasing and then decreasing.

[0083] As can be seen from Table 5, the high - performance flame - retardant rubber composite C12 with controlled distribution of flame - retardants and synergistic interfacial cross - linking has similar flame - retardant properties to the similar - formulation CM3, and is significantly superior to the non - flame - retardant formulation CM1 and the traditional flame - retardant formulation CM2. It can be seen that while improving various mechanical properties, C12 maintains excellent flame - retardant properties.

[0084] The raw materials used in Examples 4 - 6 are shown in Tables 6 and 7.

[0085] Table 6 Raw materials for flame - retardant rubber particles B21 - B23 rich in dynamic sulfur bonds

[0086] Flame-retardant rubber particles rich in dynamic sulfur bonds B21 B22 B23 Masterbatch with high vulcanizing agent addition (g) 100 100 100 Aluminum hypophosphite (g) 100 150 200

[0087] Table 7 Raw materials for high - performance flame - retardant rubber composites C21 - C23 with controlled distribution of flame - retardants and synergistic interfacial cross - linking

[0088]

[0089] Example 4

[0090] A preparation method of a high - performance flame - retardant rubber composite with controlled distribution of flame - retardants and synergistic interfacial cross - linking includes the following steps:

[0091] Step 1: Prepare a masterbatch with a high vulcanizing agent addition amount

[0092] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ, and 50 g of sulfur, add them to an open mill and mix at 30 °C for 10 min to obtain a masterbatch with a high vulcanizing agent addition amount;

[0093] Step 2: Prepare flame - retardant rubber particles B21 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds)

[0094] Take 100 g of the masterbatch with a high vulcanizing agent addition amount and 100 g of aluminum hypophosphite according to the dosages in Table 6, add them to an open mill and mix at 30 °C for 20 min, then use a flat vulcanizer to carry out mold pressing vulcanization at 143 °C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame - retardant rubber particles B21 rich in dynamic sulfur bonds;

[0095] Step 3: Add all the flame-retardant rubber particles B21 rich in dynamic sulfur bonds, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ obtained in Step 2 to an open mill according to the dosages in Table 7, mix at 30 °C for 15 min, add the obtained mixed rubber to a flat vulcanizer, and perform compression molding vulcanization at 143 °C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite material C21 with controlled distribution of flame retardant and synergistic interfacial crosslinking.

[0096] Example 5

[0097] A preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking includes the following steps:

[0098] Step 1: Prepare a mixed rubber with a high sulfur agent addition amount

[0099] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ, and 50 g of sulfur, add them to an open mill, and mix at 30 °C for 10 min to obtain a mixed rubber with a high sulfur agent addition amount;

[0100] Step 2: Prepare flame-retardant rubber particles B22 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds)

[0101] Take 100 g of the mixed rubber with a high sulfur agent addition amount and 150 g of aluminum hypophosphite according to the dosages in Table 6, add them to an open mill, mix at 30 °C for 20 min, then perform compression molding vulcanization with a flat vulcanizer at 143 °C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame-retardant rubber particles B22 rich in dynamic sulfur bonds;

[0102] Step 3: Add all the flame-retardant rubber particles B22 rich in dynamic sulfur bonds, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ obtained in Step 2 to an open mill according to the dosages in Table 7, mix at 30 °C for 15 min, add the obtained mixed rubber to a flat vulcanizer, and perform compression molding vulcanization at 143 °C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite material C22 with controlled distribution of flame retardant and synergistic interfacial crosslinking.

[0103] Example 6

[0104] A preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking includes the following steps:

[0105] Step 1: Prepare a mixed rubber with a high sulfur agent addition amount

[0106] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ, and 50 g of sulfur. Add them to an open mill and mix at 30 °C for 10 min to obtain a rubber compound with a high vulcanizing agent addition amount.

[0107] Step 2: Prepare flame-retardant rubber particles B23 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds).

[0108] Take 100 g of the rubber compound with a high vulcanizing agent addition amount and 200 g of aluminum hypophosphite according to the dosages in Table 6. Add them to an open mill and mix at 30 °C for 20 min. Then, use a flat vulcanizer to perform mold pressing vulcanization at 143 °C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame-retardant rubber particles B23 rich in dynamic sulfur bonds.

[0109] Step 3: Add all the flame-retardant rubber particles B13 rich in dynamic sulfur bonds obtained in Step 2, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ to an open mill according to the dosages in Table 7, and mix at 30 °C for 15 min. Add the obtained rubber compound to a flat vulcanizer and perform mold pressing vulcanization at 143 °C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite material C23 with controlled distribution of flame retardant and synergistic interfacial crosslinking.

[0110] Comparative Example 4

[0111] A preparation method of a flame-retardant crosslinked rubber, comprising:

[0112] Take 100 g of natural rubber, 50 g of carbon black, 50 g of aluminum hypophosphite, 5 g of zinc oxide, 1 g of stearic acid, 2 g of antioxidant 4010NA, 1.5 g of accelerator CZ, and 2 g of sulfur. Add them to an open mill and mix at 30 °C for 20 min. Add the obtained rubber compound to a flat vulcanizer and perform mold pressing vulcanization at 143 °C according to the optimum vulcanization time to obtain a flame-retardant crosslinked rubber CM4.

[0113] Perform performance tests on the high-performance flame-retardant rubber composite materials C21 - C23 with controlled distribution of flame retardant and synergistic interfacial crosslinking and the flame-retardant crosslinked rubber CM4 respectively. The specific test results are shown in Table 8.

[0114] Table 8 Performance test results of the high-performance flame-retardant rubber composite materials C21 - C23 with controlled distribution of flame retardant and synergistic interfacial crosslinking and the comparative rubbers CM1 and CM4

[0115]

[0116] It can be seen from Table 6 and Table 7 that C21 to C23 represent high-performance flame-retardant rubber composites with controlled distribution of flame retardants and synergistic interfacial cross-linking obtained by adding different amounts of aluminum hypophosphite flame retardant to the rubber compounds with high vulcanizing agent content. According to Table 8, by comparing the vulcanization time, mechanical properties and flame retardant properties of C21 to C23, it can be found that as the filling amount of aluminum hypophosphite increases, the optimum vulcanization time is prolonged, the tensile strength and elongation at break both decrease, while the flame retardant property is improved. This is because the increase in the filling amount of the flame retardant reduces the rubber content and the content of dynamic bonds in the flame-retardant rubber particles rich in dynamic sulfur bonds, thus reducing the strength of the two-phase interfacial cross-linking and the performance of the composite material deteriorates.

[0117] CM4 is a traditional rubber with aluminum hypophosphite flame retardant formulation. By comparing the mechanical properties and flame retardant properties of C21 and CM4, it can be found that both the mechanical properties and flame retardant properties of C21 are better than those of CM4. This is also due to the selective distribution of the flame retardant in the high cross-linking phase, which reduces the influence of the flame retardant on the rubber matrix. At the same time, the filling amount of carbon black is reduced, and the carbon layer obtained after combustion is denser, resulting in an improvement in the flame retardant property.

[0118] The raw materials used in Examples 7 to 9 are shown in Table 9 and Table 10.

[0119] Table 9 Raw materials used for flame-retardant rubber particles B31 to B33 rich in dynamic sulfur bonds

[0120] Flame-retardant rubber particles rich in dynamic sulfur bonds B31 B32 B33 Masterbatch with high vulcanizing agent addition (g) 100 100 100 Melamine (g) 100 150 200

[0121] Table 10 Raw materials used for high-performance flame-retardant rubber composites C31 to C33 with controlled distribution of flame retardants and synergistic interfacial cross-linking

[0122]

[0123] Example 7

[0124] A preparation method of a high-performance flame-retardant rubber composite with controlled distribution of flame retardants and synergistic interfacial cross-linking includes the following steps:

[0125] Step 1, preparing a rubber compound with high vulcanizing agent content

[0126] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ and 50 g of sulfur, add them to an open mill and mix at 30 °C for 10 min to obtain a rubber compound with high vulcanizing agent content;

[0127] Step 2, preparing flame-retardant rubber particles B31 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds)

[0128] Take 100 g of the masterbatch with a high vulcanizing agent addition and 100 g of melamine according to the dosages in Table 9, add them to an open mill, mix at 30 °C for 20 min, then perform compression molding and vulcanization on a flat vulcanizer at 143 °C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame-retardant rubber particles B31 rich in dynamic sulfur bonds;

[0129] Step 3: Add all the flame-retardant rubber particles B31 rich in dynamic sulfur bonds obtained in Step 2, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ to an open mill according to the dosages in Table 10, mix at 30 °C for 15 min, add the obtained masterbatch to a flat vulcanizer, and perform compression molding and vulcanization at 143 °C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite material C31 with controlled distribution of flame retardant and synergistic interfacial crosslinking.

[0130] Example 8

[0131] A preparation method of a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking includes the following steps:

[0132] Step 1: Prepare a masterbatch with a high vulcanizing agent addition

[0133] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ, and 50 g of sulfur, add them to an open mill, and mix at 30 °C for 10 min to obtain a masterbatch with a high vulcanizing agent addition;

[0134] Step 2: Prepare flame-retardant rubber particles B32 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds)

[0135] Take 100 g of the masterbatch with a high vulcanizing agent addition and 150 g of melamine according to the dosages in Table 9, add them to an open mill, mix at 30 °C for 20 min, then perform compression molding and vulcanization on a flat vulcanizer at 143 °C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame-retardant rubber particles B32 rich in dynamic sulfur bonds;

[0136] Step 3: Add all the flame-retardant rubber particles B32 rich in dynamic sulfur bonds obtained in Step 2, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ to an open mill according to the dosages in Table 10, mix at 30 °C for 15 min, add the obtained masterbatch to a flat vulcanizer, and perform compression molding and vulcanization at 143 °C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite material C32 with controlled distribution of flame retardant and synergistic interfacial crosslinking.

[0137] Example 9

[0138] A preparation method of a high-performance flame-retardant rubber composite with controlled distribution of flame retardant and synergistic interfacial crosslinking, comprising the following steps:

[0139] Step 1: Prepare a masterbatch with a high sulfur agent addition

[0140] Take 1000 g of natural rubber, 50 g of zinc oxide, 10 g of stearic acid, 20 g of antioxidant 4010NA, 15 g of accelerator CZ, and 50 g of sulfur, add them to an open mill and mix at 30 °C for 10 min to obtain a masterbatch with a high sulfur agent addition;

[0141] Step 2: Prepare flame-retardant rubber particles B33 rich in dynamic sulfur bonds (disulfide bonds and polysulfide bonds)

[0142] Take 100 g of the masterbatch with a high sulfur agent addition and 200 g of melamine according to the dosages in Table 9, add them to an open mill, mix at 30 °C for 20 min, then use a flat vulcanizer to carry out compression molding and vulcanization at 143 °C according to the optimum vulcanization time, and crush to an average particle size of about 300 microns to obtain flame-retardant rubber particles B33 rich in dynamic sulfur bonds;

[0143] Step 3: Add all the flame-retardant rubber particles B33 rich in dynamic sulfur bonds obtained in Step 2, 100 g of natural rubber, 1 g of sulfur, 3.33 g of zinc oxide, 0.66 g of stearic acid, and 1 g of accelerator CZ to an open mill according to the dosages in Table 10, mix at 30 °C for 15 min, add the obtained masterbatch to a flat vulcanizer, and carry out compression molding and vulcanization at 143 °C according to the optimum vulcanization time to obtain a high-performance flame-retardant rubber composite C33 with controlled distribution of flame retardant and synergistic interfacial crosslinking.

[0144] Comparative Example 5

[0145] A preparation method of a flame-retardant crosslinked rubber, comprising:

[0146] Take 100 g of natural rubber, 50 g of carbon black, 50 g of melamine, 5 g of zinc oxide, 1 g of stearic acid, 2 g of antioxidant 4010NA, 1.5 g of accelerator CZ, and 2 g of sulfur, add them to an open mill and mix at 30 °C for 20 min, add the obtained masterbatch CN5 to a flat vulcanizer, and carry out compression molding and vulcanization at 143 °C according to the optimum vulcanization time to obtain a flame-retardant crosslinked rubber CM5.

[0147] Perform performance tests on the high-performance flame-retardant rubber composites C31 - C33 with controlled distribution of flame retardant and synergistic interfacial crosslinking and the flame-retardant crosslinked rubber CM5 respectively. The specific test results are shown in Table 11.

[0148] Table 11 Performance test results of the high-performance flame-retardant rubber composites C31 - C33 with controlled distribution of flame retardant and synergistic interfacial crosslinking and the comparative rubbers CM1, CM5

[0149]

[0150]

[0151] As can be seen from Tables 3 to 5, Table 8 and Table 11, the method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking provided by the present invention has good generality, and various flame-retardant fillers can be applied to the present invention. Compared with the traditional flame-retardant formulations (CM2, CM4, CM5) with the same flame-retardant addition amounts, C12, C21 and C31 all have improved mechanical properties while retaining the flame-retardant efficiency. In short, the present invention proposes a method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and synergistic interfacial crosslinking, and prepares a large class of high-performance flame-retardant rubber composite materials with excellent comprehensive properties far higher than those of traditional flame-retardant formulations.

[0152] Although the embodiments of the present invention have been disclosed as above, it is not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and coordinated interfacial cross-linking, characterized in that: The following steps are involved: Step 1, mixing raw rubber, sulfur, vulcanizing agent and antioxidant to obtain a mixed rubber with a high amount of vulcanizing agent added; Step 2: mixing, vulcanizing, and crushing the rubber compound with a high amount of vulcanizing agent added and the flame retardant to obtain flame retardant rubber particles rich in dynamic sulfur bonds; Step 3: Mix and vulcanize the flame-retardant rubber particles rich in dynamic sulfur bonds, raw rubber, sulfur and vulcanization accelerators to obtain a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and coordinated interface cross-linking.

2. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and coordinated interfacial crosslinking according to claim 1, characterized in that: The raw rubber is one or more of EPDM rubber, natural rubber, styrene-butadiene rubber, polybutadiene rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, polynorbornene, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, and epoxidized styrene / isoprene block copolymer.

3. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and coordinated interfacial crosslinking according to claim 1, characterized in that: The vulcanization aid is an activator and an accelerator.

4. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and coordinated interfacial crosslinking according to claim 3, characterized in that: The activator is zinc oxide and stearic acid, wherein the mass ratio of zinc oxide to stearic acid is 4 to 6:1; the accelerator is one or more of accelerator CZ, accelerator TMTD, accelerator DM, accelerator NOBS, accelerator D, accelerator M, accelerator ZDC, and accelerator NS.

5. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and coordinated interfacial crosslinking according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 4010NA, antioxidant 4020, antioxidant RD, antioxidant 264, antioxidant 2246, antioxidant DLTDP, antioxidant Irgafos168, antioxidant BLE-C, antioxidant 445, and antioxidant MB.

6. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and coordinated interfacial crosslinking according to claim 1, characterized in that: In the step 2, the flame retardant is one or more of ammonium polyphosphate, pentaerythritol, aluminum hypophosphite, expandable graphite, melamine, melamine cyanurate, phytic acid, aluminum hydroxide, magnesium hydroxide, decabromodiphenyl ether, carbon nanotubes, and montmorillonite.

7. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and coordinated interfacial crosslinking according to claim 3, characterized in that: In the step 1, the mass ratio of raw rubber, sulfur, activator and antioxidant is 100:2-40:1-10:1-10; the mass ratio of sulfur to accelerator is 2-8:

1.

8. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and coordinated interfacial crosslinking according to claim 1, characterized in that: In the step 2, the mass ratio of the high vulcanizing agent added rubber to the flame retardant is 1-3:1-2.

9. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardants and coordinated interfacial crosslinking according to claim 3, characterized in that: In the step three, the mass ratio of raw rubber, flame-retardant rubber particles rich in dynamic sulfur bonds, sulfur and activator is 100:100-800:0.5-20:0.5-5; the mass ratio of sulfur to accelerator is 1-8:

1.

10. The method for preparing a high-performance flame-retardant rubber composite material with controlled distribution of flame retardant and coordinated interfacial crosslinking according to claim 1, characterized in that: In the step 1, the mixing is performed in an open mixer at 30° C. for 5 to 30 minutes; In the step 2, the mixing is performed in an open mill at 30°C for 10 to 50 minutes; the vulcanization temperature is 130 to 180°C for a time equal to the vulcanization time; and the particles are crushed to a particle size of 10 to 1000 μm; In the step 3, the mixing is carried out in an open mill at 30° C. for 10 to 50 minutes; the vulcanization temperature is 130 to 180° C., and the time is the positive vulcanization time.

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