Environmentally-friendly flame-retardant rubber and preparation method therefor

Abstract

An environmentally-friendly flame-retardant rubber and a preparation method therefor. The environmentally-friendly flame-retardant rubber comprises the following components: styrene-butadiene rubber, silicone rubber, white carbon black, an environmentally-friendly flame retardant, a vulcanizing agent, an anti-aging agent and an accelerator. The environmentally-friendly flame retardant consists of magnesium and aluminum hydroxides and an intumescent flame retardant. The intumescent flame retardant is a mixture of sodium alginate, melamine and ammonium polyphosphate. By means of modification, the magnesium and aluminum hydroxides can be better dispersed in the system, so as to enhance the charring of the flame retardant system, thereby forming highly intumesced, continuous and dense charcoal layers; and the formation of the highly intumesced, continuous and dense charcoal layers suppresses the transfer of heat and gases and prevents further combustion of internal matrixes. In addition, after being grafted with an alkyl long chain, the modified magnesium and aluminum hydroxides can be better dispersed in the system, and thus can more easily form a complex and dense cross-linked structure with other raw materials during rubber vulcanization, and the dense cross-linked structure can improve the mechanical properties of the environmentally-friendly flame retardant rubber.

Description

Environment-friendly flame-retardant rubber and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber, in particular to an environment-friendly flame-retardant rubber and a preparation method thereof. BACKGROUND

[0002] Rubber is a high-elastic polymer material with reversible deformation, which is elastic at room temperature, can produce large deformation under the action of small external force, and can restore to the original state after the external force is removed. At present, rubber products are widely used in various aspects of industry or life, such as transportation, national defense and military, agriculture, water conservancy, electrical communication, medical health, culture and education, and building fields. Most rubbers are flammable or combustible, so the risk of fire and the harm to the environment of rubber products are greatly increased. For example, various rubber products for household and vehicles require flame retardancy and high flame retardant performance. In order to improve the flame retardant performance of rubber, a certain amount of flame retardant is generally added to the rubber, including inorganic flame retardant, organic halogen-based flame retardant, organic phosphorus-based flame retardant, and intumescent flame retardant. However, the flame-retardant efficiency of inorganic flame retardant and organic phosphorus-based flame retardant is generally low. Although the organic halogen-based flame retardant with high flame-retardant efficiency can greatly reduce the combustion of the material, a large amount of smoke and hydrogen halide gas will be generated once a fire occurs, causing secondary disasters, which are often more serious than the direct consequences of burning, and have more lasting secondary damage effects. In addition, the steel in machine switch equipment and reinforced concrete will also be corroded and damaged, and the thick smoke will seriously hinder the evacuation of the building and endanger the safety of people's life and property, which is extremely harmful.

[0003] Intumescent flame retardant is an environmentally friendly green flame retardant with phosphorus and nitrogen as the main flame-retardant elements, which does not contain halogen. Its system has a synergistic effect. This kind of flame retardant is composed of acid source, carbon source and gas source. Its mechanism is that the flame retardant forms a dense porous foam layer on the surface of the material when heated. This foam carbon layer can prevent the further degradation of the inner layer polymer and the release of combustible materials to the surface, and can also prevent the transmission of heat source to the polymer and the isolation of oxygen source, thereby effectively preventing the spread and propagation of fire and achieving the effect of flame retardation. This technology basically overcomes the shortcomings of many traditional flame retardants, and is low in smoke and toxicity, and does not produce corrosive gas, which meets the future research and development direction of flame retardants, and has become one of the most active flame retardant research fields at home and abroad.

[0004] CN101812193A discloses an environmentally friendly flame-retardant rubber and a preparation method thereof, and the mass fractions of the formula components are as follows: chlorobutadiene rubber 100, hexamethyl quinoxaline-2,3-dithioformate 1-4, accelerator DM 1-2, zinc oxide 3-10, magnesium oxide 3-10, antioxidant 4010NA 1-2, paraffin 0.5-2, fast extrusion carbon black (N550) 20-40, kaolin 30-40, aluminum hydroxide 30-50, zinc borate 5-15, FR-808A 10-20, and cresylic acid phosphate 5-15. Through comparative analysis of the performance of the chlorobutadiene rubber formula containing halogen flame retardant and the chlorobutadiene rubber formula containing non-halogen flame retardant, the performance of the non-halogen flame-retardant formula fully meets the standard requirements and can replace the chlorobutadiene rubber formula containing halogen flame retardant. The use of the chlorobutadiene rubber formula can meet the flame-retardant use requirements, and the use of the material is environmentally friendly and safe to human body. However, the flame retardant used in the invention is an inorganic flame retardant, and the use of a large amount of the flame retardant leads to a decrease in the mechanical properties of the material.

[0005] SUMMARY

[0006] In view of the above defects of the prior art, the technical problem to be solved by the present application is to provide an environmentally friendly flame-retardant rubber, which contains an environmentally friendly flame retardant, and the use of the environmentally friendly flame retardant does not cause a decrease in the mechanical properties of the rubber.

[0007] To achieve the above-mentioned purpose, the present application provides an environmentally friendly flame-retardant rubber containing an environmentally friendly flame retardant, which is a mixture of an intumescent flame retardant and magnesium-aluminum hydroxide. The intumescent flame retardant is a mixture of sodium alginate, melamine and ammonium polyphosphate. The magnesium ions in the magnesium-aluminum hydroxide can promote the crosslinking of ammonium polyphosphate and form a bridge between the two phosphoric acid groups, increasing the content of effective ammonium polyphosphate in the system, thereby generating a more stable and effective carbon layer. Moreover, the magnesium-aluminum hydroxide can produce nanoscale substances, which can form a mutually penetrating polymer network with the carbon layer and enhance its density. Through modification of the magnesium-aluminum hydroxide, the magnesium-aluminum hydroxide can be uniformly dispersed in the system, promoting the carbon formation and enhancement of the flame-retardant system, forming a highly expanded and continuous dense carbon layer, inhibiting the transfer of heat and gas, and preventing further combustion of the internal matrix.

[0008] In order to achieve the above-mentioned purpose, the present application adopts the following technical solution:

[0009] An environmentally friendly flame-retardant rubber comprises the following components: styrene-butadiene rubber, silicone rubber, white carbon black, environmentally friendly flame retardant, vulcanizing agent, anti-aging agent and accelerator.

[0010] Preferably, an environment-friendly flame-retardant rubber comprises the following components in parts by weight: 20-35 parts of styrene-butadiene rubber, 95-100 parts of silicone rubber, 2-3 parts of white carbon black, 5-10 parts of environment-friendly flame retardant, 2-5 parts of vulcanizing agent, 0.5-1 part of anti-aging agent, and 0.6-1.0 part of accelerator.

[0011] Styrene-butadiene rubber, abbreviated as SBR, is the largest general-purpose synthetic rubber variety, and its physical structure performance, processing performance and product use performance are close to those of natural rubber. Some performances, such as wear resistance, heat resistance, aging resistance and vulcanization speed, are more excellent than those of natural rubber. SBR can be used with natural rubber and various synthetic rubbers, and is widely used in the production of tires, rubber belts, rubber pipes, electric wires and cables, medical devices and various rubber products.

[0012] Silicone rubber refers to rubber whose main chain is alternately composed of silicon and oxygen atoms, and the silicon atoms are usually connected with two organic groups. The heat resistance of silicone rubber is very outstanding, and it can work continuously at 200℃ for more than 7500 hours. Silicone rubber with a heat stabilizer can be used at a higher temperature for a long time.

[0013] Preferably, the environment-friendly flame retardant is a mixture of magnesium-aluminum hydroxide and intumescent flame retardant at a mass ratio of 1:2-3; further preferably, the environment-friendly flame retardant is a mixture of modified magnesium-aluminum hydroxide and intumescent flame retardant at a mass ratio of 1:2-3.

[0014] Preferably, the preparation method of the magnesium-aluminum hydroxide and the modified magnesium-aluminum hydroxide is as follows:

[0015] (1) Preparation of magnesium-aluminum hydroxide: Mg(NO3)2·6H2O and Al(NO3)3·9H2O are dissolved in water; under nitrogen protection, the pH value is adjusted with sodium bicarbonate aqueous solution; heating reaction, cooling, filtering, collecting the filter residue, washing the filter residue with water and drying to obtain magnesium-aluminum hydroxide;

[0016] (2) Preparation of modified magnesium-aluminum hydroxide: the magnesium-aluminum hydroxide prepared in step (1) is calcined at 400-600℃ to obtain magnesium-aluminum composite oxide, the magnesium-aluminum composite oxide is uniformly mixed with a potassium cetyl phosphate aqueous solution, and the mixture is reacted under argon atmosphere, centrifuged, and the precipitate is separated, washed with water and dried to obtain modified magnesium-aluminum hydroxide.

[0017] Further preferably, the preparation method of the magnesium-aluminum hydroxide and the modified magnesium-aluminum hydroxide is as follows:

[0018] (1) Preparation of magnesium aluminum hydroxide: 5-7 g of Mg(NO3)2.6H2O, 2-5 g of Al(NO3)3.9H2O, 100-200 mL of water are mixed and dissolved by stirring, then under nitrogen protection, 1-3 mol / L sodium bicarbonate aqueous solution is used to control the pH value of the solution to be 9-10, then the solution is heated to 60-70℃, and after reaction for 20-24 h, it is cooled to 20-40℃, filtered, the filter residue is washed with water for 2-3 times, and then dried in a 80-100℃ drying oven for 6-8 h to obtain magnesium aluminum hydroxide;

[0019] (2) Preparation of modified magnesium aluminum hydroxide: 1-2 g of the magnesium aluminum hydroxide prepared in step (1) is weighed, and then calcined at 400-600℃ for 4-6 h to obtain magnesium aluminum composite oxide, and then the magnesium aluminum composite oxide is mixed with 100-200 mL of 50-70 wt% potassium cetyl phosphate aqueous solution, and uniformly mixed, and then reacted under argon atmosphere for 20-24 h, after the reaction is completed, centrifugation is performed, the precipitate is separated, and then washed with water for 2-3 times, and then dried in a 100-120℃ drying oven for 6-8 h to obtain modified magnesium aluminum hydroxide.

[0020] Preferably, the intumescent flame retardant is a mixture of sodium alginate, melamine, and ammonium polyphosphate in a mass ratio of 2-5:1:1-2.

[0021] The intumescent flame retardant uses sodium alginate as a carbon source, melamine as a gas source, and ammonium polyphosphate as an acid source, the acid source generates a dehydrating agent by thermal decomposition, and an ester compound is generated by esterification reaction with the carbon source, under the action of the gas source, the intumescent flame retardant expands to form a foam layer, releases a large amount of non-flammable gas, and dilutes the oxygen in the environment, and then the ester compound is dehydrated and crosslinked to form a porous foam carbon layer, in addition, sodium alginate can form a water solution with viscosity with the water generated by combustion, which can isolate the combustion and inhibit further combustion. The environmentally friendly flame retardant prepared by mixing the magnesium aluminum hydroxide and the intumescent flame retardant can significantly improve the flame retardant performance of the flame retardant; the metal oxide generated by the decomposition of the magnesium aluminum hydroxide can enter the intumescent flame retardant system to promote the esterification reaction between the acid source and the carbon source, the divalent magnesium ion promotes the crosslinking of the ammonium polyphosphate and forms a bridge between the two phosphate groups, increases the content of the effective ammonium polyphosphate in the system, and thus a more stable and effective carbon layer is generated; and the magnesium aluminum hydroxide can generate nanoscale substances, which can form a mutual penetration polymer network with the carbon layer and enhance the density thereof; by grafting modification of the magnesium aluminum hydroxide with potassium cetyl phosphate, the magnesium aluminum hydroxide with long alkyl chains is uniformly dispersed in the system, which can promote the carbon formation and enhancement of the flame retardant system, form a highly expanded and continuous dense carbon layer, inhibit the transmission of heat and gas, and prevent further combustion of the internal matrix.

[0022] Preferably, the vulcanizing agent is one or two or more of the group consisting of dicumyl peroxide, sulfur, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, benzyltriphenylphosphonium chloride.

[0023] Preferably, the anti-aging agent is one or two or more of the group consisting of N,N'-diphenyl-p-phenylenediamine, antioxidant 3100, antioxidant ZMTI.

[0024] Preferably, the accelerator is one or two or more of the group consisting of stearic acid, zinc oxide, magnesium oxide.

[0025] Preferably, the application further provides a preparation method of the above-mentioned environmentally friendly flame-retardant rubber, comprising the following steps:

[0026] S1: mixing styrene-butadiene rubber, silicone rubber and environmentally friendly flame retardant at a temperature to obtain an environmentally friendly flame-retardant rubber masterbatch;

[0027] S2: mixing white carbon black, vulcanizing agent, anti-aging agent, accelerator with the environmentally friendly flame-retardant masterbatch and vulcanizing to obtain a finished product, i.e. the environmentally friendly flame-retardant rubber.

[0028] Further preferably, the preparation method of the environmentally friendly flame-retardant rubber comprises the following steps:

[0029] S1: weighing styrene-butadiene rubber, silicone rubber and environmentally friendly flame retardant according to the formula and adding them into a banbury mixer, mixing at a pressure of 45-55 N / cm 2 and a temperature of 145-155 ℃ for 150-200 s to obtain an environmentally friendly flame-retardant rubber masterbatch;

[0030] S2: weighing white carbon black, vulcanizing agent, anti-aging agent, accelerator according to the formula and mixing them with the environmentally friendly flame-retardant masterbatch, and vulcanizing at 150-220 ℃ for 10-30 min to obtain a finished product, i.e. the environmentally friendly flame-retardant rubber.

[0031] On the basis of common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined, i.e. each preferred embodiment of the application.

[0032] 1. The environmentally friendly flame retardant prepared by the application is a halogen-free green flame retardant, and the combustion process and combustion products have less harm to the environment.

[0033] 2. The intumescent flame retardant prepared by mixing sodium alginate, melamine and ammonium polyphosphate, wherein the sodium alginate can produce sticky substances with water produced during the combustion process, which can isolate the combustion products and inhibit further combustion.

[0034] 3. The application further improves the flame-retardant effect of rubber by mixing the intumescent flame retardant and magnesium-aluminum hydroxide

[0035] 4. By modifying magnesium aluminum hydroxide, it can be better dispersed in the system, which can promote the char formation of the flame retardant system, forming a highly expanded and continuous dense char layer, inhibiting the transfer of heat and gas, and preventing further combustion of the internal matrix. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments. Except for the content specifically mentioned below, the processes, conditions, and experimental methods for implementing the invention are all common knowledge and general knowledge in the field, and the present invention does not have any particular limitations.

[0037] To avoid unnecessary details, unless otherwise specified, all items used in the following examples are commercially available products, and all methods used are conventional methods unless otherwise specified.

[0038] The sources of some of the raw materials used in this invention are as follows:

[0039] Styrene-butadiene rubber, purchased from Jinhua Bojia Plastics Technology Co., Ltd., model SBR1502.

[0040] Silicone rubber, purchased from Guangdong Leputai New Material Technology Co., Ltd., product number LPT-P1350.

[0041] Mg(NO3)2·6H2O was purchased from the Shenzhen branch of Maoming Xiongda Chemical Co., Ltd.

[0042] Al(NO3)3·9H2O, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a purity of 98%.

[0043] Potassium hexadecyl phosphate, purchased from Hubei Jiufenglong Chemical Co., Ltd., CAS No. 19035-79-1, purity 98%.

[0044] Sodium alginate, purchased from Jiangsu Huagang Biotechnology Co., Ltd., has an active ingredient content of 99%, CAS number 9005-38-3, and is classified as food grade.

[0045] Melamine, purchased from Shandong Dongyue Chemical Co., Ltd., has a melting point of 354℃, a boiling point of 557.54℃, a molecular weight of 126.12, and a density of 1.661 g / cm³. 3 The CAS number is 108-78-1.

[0046] Ammonium polyphosphate, purchased from Henan Wanshan New Material Technology Co., Ltd., with a purity of 99% and CAS number 68333-79-9.

[0047] Comparative Example 1

[0048] A rubber preparation method comprising the following steps:

[0049] S1: 300g of styrene-butadiene rubber, 1000g of silicone rubber, 80g of an environmentally friendly flame retardant are weighed into an internal mixer, and mixed at a pressure of 50N / cm 2 and a temperature of 150℃ for 180s to obtain an environmentally friendly flame-retardant rubber masterbatch;

[0050] S2: 30g of white carbon black, 20g of dicumyl peroxide, 5g of N,N'-dimethylphenyl-p-phenylenediamine, 8g of zinc oxide are mixed with the environmentally friendly flame-retardant masterbatch, and vulcanized at 200℃ for 20min to obtain a finished product, i.e., the rubber.

[0051] Example 1

[0052] An environmentally friendly flame-retardant rubber preparation method comprising the following steps:

[0053] S1: 300g of styrene-butadiene rubber, 1000g of silicone rubber, 80g of an environmentally friendly flame retardant are weighed into an internal mixer, and mixed at a pressure of 50N / cm 2 and a temperature of 150℃ for 180s to obtain an environmentally friendly flame-retardant rubber masterbatch;

[0054] S2: 30g of white carbon black, 20g of dicumyl peroxide, 5g of N,N'-dimethylphenyl-p-phenylenediamine, 8g of zinc oxide are mixed with the environmentally friendly flame-retardant masterbatch, and vulcanized at 200℃ for 20min to obtain a finished product, i.e., the environmentally friendly flame-retardant rubber.

[0055] The environmentally friendly flame retardant is magnesium aluminum hydroxide, and its preparation method is as follows: 6g of Mg(NO3)2·6H2O, 4g of Al(NO3)3·9H2O, and 150mL of water are mixed and stirred to dissolve; under nitrogen protection, a 2mol / L sodium bicarbonate aqueous solution is used to control the pH value of the solution to be 9; then the solution is heated to 70℃, and after reaction for 24h, it is cooled to 30℃, filtered, and the filter residue is collected; the filter residue is washed with water for 3 times and then placed in a 100℃ drying oven for drying for 8h, and then ground to obtain magnesium aluminum hydroxide.

[0056] Example 2

[0057] An environmentally friendly flame-retardant rubber preparation method comprising the following steps:

[0058] S1: 300g of styrene-butadiene rubber, 1000g of silicone rubber, 80g of an environmentally friendly flame retardant are weighed into an internal mixer, and mixed at a pressure of 50N / cm 2 and a temperature of 150℃ for 180s to obtain an environmentally friendly flame-retardant rubber masterbatch;

[0059] S2: 30g of white carbon black, 20g of dicumyl peroxide, 5g of N,N'-dimethylphenyl-p-phenylenediamine, 8g of zinc oxide are weighed and mixed with the environmentally friendly flame retardant masterbatch, and then vulcanized at 200 DEG C for 20 minutes to obtain the finished product, i.e. the environmentally friendly flame-retardant rubber.

[0060] The environmentally friendly flame retardant is modified magnesium-aluminum hydroxide, and its preparation method is as follows:

[0061] (1) Preparation of magnesium-aluminum hydroxide: 6g of Mg(NO3)2·6H2O, 4g of Al(NO3)3·9H2O, and 150mL of water are mixed and dissolved by stirring; under nitrogen protection, the pH value of the solution is controlled to be 9 by using 2mol / L sodium bicarbonate aqueous solution; then the solution is heated to 70 DEG C, and after reaction for 24h, it is cooled to 30 DEG C, filtered, and the filter residue is collected; the filter residue is washed with water for 3 times and then placed in a 100 DEG C drying oven for drying for 8h to obtain magnesium-aluminum hydroxide.

[0062] (2) Preparation of modified magnesium-aluminum hydroxide: 2g of magnesium-aluminum hydroxide prepared in step (1) is placed in a 500 DEG C muffle furnace and calcined for 6h to obtain magnesium-aluminum composite oxide; the magnesium-aluminum composite oxide is mixed with 200mL of 70wt% potassium cetyl phosphate aqueous solution, and uniformly mixed; under argon atmosphere, the mixture is reacted for 24h; after the reaction is completed, centrifugation is performed, the precipitate is separated, and the precipitate is washed with water for 3 times and then placed in a 120 DEG C drying oven for drying for 8h to obtain modified magnesium-aluminum hydroxide.

[0063] Example 3

[0064] A preparation method of an environmentally friendly flame-retardant rubber comprises the following steps:

[0065] S1: 300g of styrene-butadiene rubber, 1000g of silicone rubber, and 80g of environmentally friendly flame retardant are weighed and added into a mixer, and mixed at a pressure of 50N / cm 2 , and a temperature of 150 DEG C for 180s to obtain an environmentally friendly flame-retardant rubber masterbatch;

[0066] S2: 30g of white carbon black, 20g of dicumyl peroxide, 5g of N,N'-dimethylphenyl-p-phenylenediamine, and 8g of zinc oxide are mixed with the environmentally friendly flame retardant masterbatch, and then vulcanized at 200 DEG C for 20 minutes to obtain the finished product, i.e. the environmentally friendly flame-retardant rubber.

[0067] The environmentally friendly flame retardant is a mixture of sodium alginate, melamine, and ammonium polyphosphate in a mass ratio of 5:1:2.

[0068] Example 4

[0069] A preparation method of an environmentally friendly flame-retardant rubber comprises the following steps:

[0070] S1: 300 g of styrene-butadiene rubber, 1000 g of silicone rubber, 80 g of environmentally friendly flame retardant were weighed into a mixer, and mixed at a pressure of 50 N / cm 2 at a temperature of 150 DEG C for 180 s to obtain an environmentally friendly flame-retardant rubber masterbatch;

[0071] S2: 30 g of white carbon black, 20 g of dicumyl peroxide, 5 g of N,N'-dimethylphenyl-p-phenylenediamine, 8 g of zinc oxide, and the environmentally friendly flame-retardant masterbatch were mixed, and vulcanized at 200 DEG C for 20 min to obtain a finished product, i.e., the environmentally friendly flame-retardant rubber.

[0072] The environmentally friendly flame retardant is a mixture of modified magnesium-aluminum hydroxide and intumescent flame retardant in a mass ratio of 1:3, and the modified magnesium-aluminum hydroxide is prepared as follows:

[0073] (1) Preparation of magnesium-aluminum hydroxide: 6 g of Mg(NO3)2.6H2O, 4 g of Al(NO3)3.9H2O, and 150 mL of water were mixed and stirred to dissolve; under nitrogen protection, a 2 mol / L aqueous sodium bicarbonate solution was used to control the pH of the solution to 9; then the solution was heated to 70 DEG C and reacted for 24 h, then cooled to 30 DEG C, filtered, and the filter residue was washed with water 3 times and then placed in a 100 DEG C drying oven for 8 h to obtain magnesium-aluminum hydroxide.

[0074] (2) Preparation of modified magnesium-aluminum hydroxide: 2 g of the magnesium-aluminum hydroxide prepared in step (1) was placed in a 500 DEG C muffle furnace and calcined for 6 h to obtain a magnesium-aluminum composite oxide, which was mixed uniformly with 200 mL of a 70 wt% aqueous potassium cetyl phosphate solution, and reacted under an argon atmosphere for 24 h; after the reaction was complete, the precipitate was separated by centrifugation, washed with water 3 times, and then placed in a 120 DEG C drying oven for 8 h to obtain modified magnesium-aluminum hydroxide.

[0075] The intumescent flame retardant is a mixture of sodium alginate, melamine, and ammonium polyphosphate in a mass ratio of 3:1:1.

[0076] Test Example 1

[0077] Flame Retardant Test: The environmentally friendly flame-retardant rubber prepared in Comparative Example 1 and Examples 1-4 was tested for vertical burning rating of flame-retardant samples according to ASTM UL94-2009 standard. The sample size standard was 120 mm x 12.7 mm x 3.2 mm. The vertical burning test mainly observed whether the sample self-extinguished within 10 s or 30 s, and whether there was dripping during the burning process. The vertical sample stopped burning within 10 s, and no dripping occurred, i.e., it reached UL94-V0 level. The sample was ignited and extinguished within 30 s of burning, and no polymer melt dripping occurred during the burning process, which was UL94-V1 level. The sample was ignited and extinguished within 30 s of burning, and there was melt dripping during the burning process, which was UL94-V2 level. The test results are shown in Table 1:

[0078] Table 1: Test Results of Flame Retardant Properties of Environmentally Friendly Flame-Retardant Rubber

[0079] As can be seen from the experimental results in Table 1, the environmentally friendly flame-retardant rubber prepared in Example 4 has the best flame-retardant properties. The difference between Example 4 and the other examples is that the environmentally friendly flame retardant prepared by mixing modified magnesium aluminum hydroxide and intumescent flame retardant is added. The metal oxide generated by the decomposition of magnesium aluminum hydroxide can enter the intumescent flame retardant system to promote the esterification reaction between the acid source and the carbon source. The divalent magnesium ion promotes the crosslinking of ammonium polyphosphate and forms a bridge between the two phosphate groups, increasing the content of effective ammonium polyphosphate in the system, thereby generating a more stable and effective carbon layer. Moreover, magnesium aluminum hydroxide can produce nanoscale substances, which can form an interpenetrating polymer network with the carbon layer and enhance its density. By modifying the magnesium aluminum hydroxide, the magnesium aluminum hydroxide can be uniformly dispersed in the system, which can promote the carbonization and enhancement of the flame-retardant system, forming a highly expanded and continuous dense carbon layer, which inhibits the transfer of heat and gas and prevents the further burning of the internal matrix, thereby further improving its flame-retardant properties.

[0080] Test Example 2

[0081] Mechanical Property Test: The test objects were the environmentally friendly flame-retardant rubbers prepared in Comparative Example 1 and Examples 1-4.

[0082] The mechanical properties of the vulcanized rubber were tested mainly as follows:

[0083] (1) Hardness: The hardness test was carried out according to the requirements of GB / T531.1-2008 "Vulcanized Rubber or Thermoplastic Rubber Compression Hardness Test Method Part 1: Shore Hardness Tester", and the Shore A hardness was tested. The sample bar should meet the specification of 35mm x 15mm x 6mm at least, and the sample bar of the tensile sample can be used for measurement after being stacked to make the thickness greater than 6mm. The upper and lower surfaces of the sample film should be parallel to reduce the gap. In order to ensure the accuracy of the measurement structure, multiple points were tested, the maximum and minimum values were removed, and the average value of the remaining data was taken.

[0084] (2) Tensile properties: The tensile test was carried out according to the requirements of GB / T528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber", the dumbbell-shaped cutting tool was used to cut the environmentally friendly flame-retardant rubber prepared in Examples 1-4 into a standard thickness of 1mm, a width of 6mm, and an effective tensile length of 25mm between the clamps, the tensile rate was 500mm / min, each sample was measured multiple times, and then the results of the samples with large deviations were removed, and then the average value was taken.

[0085] (3) Tear resistance: The sample bar was prepared according to the standard of GB / T529-2008 "Determination of Tear Strength of Vulcanized Rubber or Thermoplastic Rubber (Pant, Right Angle and Crescent Shape Samples)", the universal tensile testing machine was used to measure the tear resistance of the test, each sample was measured multiple times, the results of the samples with large deviations were removed, and then the average value was taken. The test results are shown in Table 2:

[0086] Table 2: Test results of mechanical properties of environmentally friendly flame-retardant rubber

[0087] As can be seen from the experimental data in Table 2, the addition of the environmentally friendly flame retardant does not reduce the mechanical properties of the rubber, and in addition, Example 4 also has the best mechanical properties, and the possible reason is that the modified magnesium-aluminum hydroxide is grafted with long-chain alkyl, which is better dispersed in the system, and it is easier to form a complex and dense crosslinked structure with other raw materials during the vulcanization of the rubber, and the dense crosslinked structure improves the mechanical properties of the environmentally friendly flame-retardant rubber.

[0088] The above describes the preferred embodiments of the present application in detail. It should be understood that those skilled in the art can make many modifications and changes without creative labor based on the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment based on the prior art according to the concept of the present application should be within the protection scope determined by the claims.

Claims

1. An environmentally friendly flame-retardant rubber, characterized by comprising: The components include: styrene butadiene rubber, silicone rubber, white carbon black, environmentally friendly flame retardant, vulcanizing agent, anti-aging agent, accelerator.

2. The environmentally friendly flame-retardant rubber according to claim 1, characterized in that, The components include: styrene butadiene rubber 20-35 parts, silicone rubber 95-100 parts, white carbon black 2-3 parts, environmentally friendly flame retardant 5-10 parts, vulcanizing agent 2-5 parts, anti-aging agent 0.5-1 part, accelerator 0.6-1.0 part.

3. The environmentally friendly flame-retardant rubber according to claim 1, characterized in that: The environmentally friendly flame retardant is a mixture of magnesium aluminum hydroxide and intumescent flame retardant.

4. The environmentally friendly flame-retardant rubber according to claim 3, wherein the amount of the phosphorus compound is 0.1 to 5 parts by weight. The preparation method of the magnesium aluminum hydroxide is as follows: Mg(NO3)2·6H2O, Al(NO3)3·9H2O are dissolved in water; under nitrogen protection, the pH value is adjusted with sodium bicarbonate aqueous solution; heat reaction, cool, filter, collect the filter residue, wash the filter residue with water and dry, grind to obtain magnesium aluminum hydroxide.

5. The environmentally friendly flame-retardant rubber according to claim 3 or 4, characterized in that, The magnesium aluminum hydroxide is modified magnesium aluminum hydroxide, and the preparation method is as follows: the magnesium aluminum hydroxide is calcined at 400-600°C to obtain magnesium aluminum composite oxide, the magnesium aluminum composite oxide is uniformly mixed with potassium cetyl phosphate aqueous solution, and the mixture is reacted under argon atmosphere, centrifuged, and the precipitate is separated, washed with water and dried to obtain modified magnesium aluminum hydroxide.

6. The environmentally friendly flame-retardant rubber according to claim 3, characterized in that: The intumescent flame retardant is a mixture of sodium alginate, melamine and ammonium polyphosphate with a mass ratio of 2-5:1:1-2.

7. The environmentally friendly flame-retardant rubber according to claim 1, wherein: the amount of the phosphorus compound is 0.1 to 10 parts by weight. The vulcanizing agent is one or two or more of dicumyl peroxide, sulfur, 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane, benzyl triphenyl phosphonium chloride.

8. The environmentally friendly flame-retardant rubber according to claim 1, characterized in that: The anti-aging agent is one or two or more of N,N'-dimethylphenyl-p-phenylenediamine, antioxidant 3100, antioxidant ZMTI.

9. The preparation method of the environmentally friendly flame-retardant rubber according to any one of claims 1 to 8, characterized in that, The steps include: S1: mixing styrene butadiene rubber, silicone rubber and environmentally friendly flame retardant at a temperature to form environmentally friendly flame retardant rubber masterbatch; S2: mixing white carbon black, vulcanizing agent, anti-aging agent, accelerator with environmentally friendly flame retardant masterbatch, and vulcanizing to obtain finished product, i.e. the environmentally friendly flame retardant rubber.

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