An epoxy asphalt reactive phosphorus-silicon flame retardant, an epoxy asphalt concrete and a preparation method thereof

Abstract

The application discloses an epoxy asphalt reactive phosphorus-silicon flame retardant, an epoxy asphalt concrete and a preparation method thereof. The epoxy asphalt reactive phosphorus-silicon flame retardant contains a double epoxy group and a phosphorus-silicon synergistic skeleton, can greatly improve the limiting oxygen index of the epoxy asphalt, maintains good mechanical properties, and reduces the migration rate of the flame retardant. Compared with existing reactive phosphorus-silicon flame retardants, the epoxy asphalt reactive phosphorus-silicon flame retardant has better flame retardant performance, is used for preparing the epoxy asphalt concrete, improves the flame retardant performance of the epoxy asphalt concrete, and further improves the mechanical properties and road performance of the asphalt concrete, and is suitable for key scenes such as traffic infrastructure, building municipal engineering and special industrial facilities. The epoxy asphalt reactive phosphorus-silicon flame retardant is prepared through a phosphorylation reaction of a silane coupling agent hydrolysis product and an alkyl phosphate, and then end-capped by epoxy chloropropane, the preparation process is simple, no halogen and heavy metal are involved, and the epoxy asphalt reactive phosphorus-silicon flame retardant meets the EU REACH regulation and the domestic 'low toxicity and low harm' building material standard.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building materials, more specifically, relates to an epoxy asphalt reactive phosphorus-silicon flame retardant, an epoxy asphalt concrete and a preparation method thereof. BACKGROUND

[0002] As a building material, asphalt is widely used in infrastructure construction such as bridges, roads, tunnels and airports. In order to meet the demand for improving the toughness of materials in application scenarios, epoxy resin is cured with asphalt to form an epoxy asphalt material with excellent physical, high and low temperature and fatigue resistance. However, like traditional matrix asphalt and SBS modified asphalt, the limiting oxygen index of epoxy asphalt is low, and it is easy to burn during construction and use if exposed to open flame or high temperature, releasing a large amount of heat and toxic smoke, which has a negative impact on personal health, the environment and infrastructure safety.

[0003] At present, the flame retardants for epoxy asphalt mainly include two types. One is an additive type flame retardant, which is a traditional flame retardant commonly used for asphalt, such as aluminum hydroxide, magnesium hydroxide, antimony trioxide and bromine-based flame retardant, and physical compounding of such flame retardants. This type of flame retardant does not react with epoxy asphalt, and the flame retardant performance improvement effect is limited, and the compatibility with asphalt base is poor and easy to agglomerate. Some bromine-based flame retardants also produce toxic gases when burning. The other type is a reactive flame retardant, which is embedded in the polymer matrix through chemical bonding to avoid the migration and precipitation of effective flame retardant components to ensure sustained flame retardant performance. However, the research on reactive flame retardants for epoxy asphalt is very limited, and there are generally problems of insufficient reaction activity and low flame retardant efficiency. There are still the following problems:

[0004] (1) Halogen-containing system flame retardants have a greater impact on the environment;

[0005] (2) High addition amount leads to low economic efficiency;

[0006] (3) Affecting the mechanical properties of epoxy asphalt and the road performance of epoxy asphalt concrete.

[0007] These limitations limit the popularization and application of epoxy asphalt concrete in special scenarios such as tunnels and airports.

[0008] The present application develops a phosphorus-silicon synergistic halogen-free reactive flame retardant for epoxy asphalt through original molecular design. The flame retardant integrates efficient flame-retardant elements and epoxy end groups that can participate in curing in the molecular structure, achieving a significant improvement in the limiting oxygen index of epoxy asphalt at a low amount of flame retardant, while improving the high tensile strength and toughness of epoxy asphalt, and realizing the compatibility of the flame retardant performance, mechanical properties and road performance of epoxy asphalt concrete. SUMMARY

[0009] In order to solve the above defects or improvement needs of the prior art, the present application provides an epoxy asphalt reactive phosphorus-silicon flame retardant, an epoxy asphalt concrete and a preparation method thereof, which aims to synthesize a new epoxy-terminated phosphorus-silicon flame retardant, use the same as a reactive phosphorus-silicon flame retardant for epoxy asphalt, significantly improve the limiting oxygen index of the epoxy asphalt at a low addition amount, and improve the mechanical properties of the epoxy asphalt concrete, thereby solving the technical problem that the existing flame retardants are difficult to compatibly improve the flame retardant properties, mechanical properties and concrete road performance of the epoxy asphalt.

[0010] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0011] In a first aspect, the present application provides an epoxy asphalt reactive phosphorus-silicon flame retardant

[0012] which is an epoxy-terminated phosphorus-silicon flame retardant and has the following general formula (I):

[0013] ;

[0014] In the formula, R1 is selected from amino, mercapto, 2-(methoxymethyl)oxiranyl, acryloxy, diaminoethyl and methacryloxy, and R2 is selected from methyl, ethyl, propyl and hydroxyl.

[0015] Preferably, the epoxy asphalt reactive phosphorus-silicon flame retardant has a phosphorus content of 7.2% to 9.7%, a silicon content of 6.5% to 8.8% and an epoxy value of (0.23-0.50) eq / 100g.

[0016] Preferably, the epoxy asphalt reactive phosphorus-silicon flame retardant has R1 selected from mercapto, 2-(methoxymethyl)oxiranyl, acryloxy and methacryloxy, and R2 selected from methyl, ethyl, propyl and hydroxyl.

[0017] According to a second aspect of the present application, a preparation method of the epoxy asphalt reactive phosphorus-silicon flame retardant is also provided, which comprises the following steps:

[0018] (1) Hydrolysis reaction: mix a silane coupling agent and deionized water according to a molar ratio of 1:(3-5), adjust the pH of the system to 3-5, and react under an inert atmosphere at a temperature of 25-70°C for 1-3 hours to hydrolyze a liquid trihydroxysilane intermediate and methanol, and then distill the generated methanol and deionized water in the beaker to obtain the trihydroxysilane intermediate; the general formula of the silane coupling agent is [R1(CH2)3]Si(OCH3)3, and R1 is selected from amino, mercapto, 2-(methoxymethyl)oxiranyl, acryloxy, diaminoethyl and methacryloxy;

[0019] (2) Phosphorylation reaction: to the liquid trihydroxyl silane intermediate obtained in step (1), add alkyl phosphate ester in a molar amount of 1.0-1.5 times of the silane coupling agent, add catalyst in an amount of 0.3%-0.8% of the total mass of the reactants, and react at a temperature of 60-100°C for 3-5 hours to obtain a reaction product; the general formula of the alkyl phosphate ester is R2P(=O)(OCH3)2, wherein R2 is methyl, ethyl, propyl, or hydroxyl;

[0020] (3) Epoxy capping reaction: slowly add epichlorohydrin to the reaction product obtained in step (2), adjust the pH of the system to 7-8, react at 70-90°C for 4-8 hours, and remove the generated hydrogen chloride at the same time to obtain a light yellow transparent reaction end product, which is the epoxy asphalt reaction-type phosphorus-silicon flame retardant.

[0021] Preferably, in the method, the silane coupling agent in step (1) is selected from one or more of KH-540, KH-560, KH-570, KH-590, KH-792, and TMSPMA.

[0022] Preferably, in the method, the alkyl phosphate ester in step (2) is selected from one or more of dimethyl methylphosphonate (DMMP), dimethyl ethylphosphonate (DMEP), and dimethyl propylphosphonate (DPrMP) in any combination; and the catalyst is selected from dibutyltin dilaurate, which is added in an amount of 0.3%-0.8% of the total mass of the silane coupling agent and the alkyl phosphate ester.

[0023] Preferably, in the method, the amount of epichlorohydrin added in step (3) is 1.2-1.8 times of the molar amount of the silane coupling agent.

[0024] According to a third aspect of the present application, there is also provided a flame-retardant modified epoxy asphalt, which comprises epoxy asphalt and an epoxy asphalt reaction-type phosphorus-silicon flame retardant as described in the present application.

[0025] According to a fourth aspect of the present application, there is also provided a flame-retardant epoxy asphalt concrete, which comprises an epoxy asphalt reaction-type phosphorus-silicon flame retardant as described in the present application.

[0026] Preferably, the flame-retardant epoxy asphalt concrete has an limiting oxygen index (LOI, %) > 30, a vertical burning rating (UL94) of V-0, and a flame retardant migration amount < 0.8 μg / m 2 .

[0027] Preferably, the flame-retardant epoxy asphalt concrete is prepared by the following method:

[0028] Heat 40-100 parts of asphalt matrix to melt, add 30-50 parts of bisphenol A epoxy resin and 0.3-1 parts of silane coupling agent, and stir evenly to form a mixed matrix;

[0029] Add 5-15 parts of the epoxy asphalt reactive phosphorus-silicon flame retardant as described in this invention, heat to 130℃-160℃, and stir until homogeneous.

[0030] Cool to 110℃-130℃, add curing agent and accelerator, stir evenly, add 1000-1500 parts of mineral basalt heated to 170℃-180℃, stir at 110℃-130℃ for 5min±5s, and after curing, obtain flame-retardant epoxy asphalt concrete.

[0031] Overall, compared with the prior art, the above-described technical solution conceived by this invention, due to the discovery of a new method for synthesizing reactive phosphorus-silicon flame retardants, can achieve the following beneficial effects:

[0032] The epoxy asphalt reactive phosphorus-silicon flame retardant provided by this invention is an epoxy-terminated phosphorus-silicon flame retardant comprising a phosphoryl group, a siloxane group, and an epoxy end-capping component. It can achieve a limiting oxygen index of over 30% for epoxy asphalt while maintaining good mechanical properties, with a flame retardant migration of <0.8 μg / m³. 2 Compared to existing reactive phosphorus-silicon flame retardants, this product exhibits superior flame retardant properties. When used in the preparation of epoxy asphalt concrete, it not only enhances its flame retardant performance but also further improves the mechanical and road performance of the asphalt concrete. This epoxy asphalt reactive phosphorus-silicon flame retardant is compatible with the flame retardant properties, mechanical properties, and road performance of epoxy asphalt.

[0033] The preparation method of the epoxy asphalt reactive phosphorus-silicon flame retardant provided by this invention involves a phosphorylation reaction of silane coupling agent with alkyl phosphate ester, followed by epichlorohydrin end-capping. The molecular structure contains bi-epoxy groups and a phosphorus-silicon synergistic framework. The preparation process is simple and free of halogens and heavy metals, complying with EU REACH regulations and domestic "low-toxicity and low-harm" building material standards. The prepared epoxy asphalt reactive phosphorus-silicon flame retardant can be used in the preparation of asphalt concrete, suitable for transportation infrastructure, building and municipal engineering, and special industrial facilities. Specifically, it covers key scenarios such as steel bridge decks, highway tunnels, special sections of expressways, industrial roof waterproofing, underground parking lots, pedestrian overpasses, port piers, airport emergency repairs, and chemical pipeline corridors. Attached Figure Description

[0034] Figure 1 It is the general structural formula of epoxy asphalt reactive phosphorus-silicon flame retardant.

[0035] Figure 2 This is the infrared spectrum of the epoxy asphalt reactive phosphorus-silicon flame retardant synthesized in Example 1. Detailed Implementation

[0036] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0037] The present application provides an epoxy asphalt reactive phosphorus-silicon flame retardant, which is an epoxy-terminated phosphorus-silicon flame retardant, having a structure as shown in the following general formula (I):

[0038] ;

[0039] wherein R1 is selected from amino, mercapto, 2-(methoxymethyl)oxiranyl, acryloyloxy, diaminoethyl, methacryloyloxy, and R2 is methyl, ethyl, propyl, hydroxyl.

[0040] The present application integrates phosphoryl (-P(=O)(OCH3)2) and siloxane skeleton (-Si-O-) in the same molecule through molecular design, forming a unique gas phase, condensed phase and interface synergistic flame retardant mechanism. At the same time, the molecular structure also contains epoxy groups, which can chemically react with epoxy resin, thereby firmly combining with the epoxy asphalt matrix, avoiding the migration and precipitation of the flame retardant, and the flame retardant effect is more durable. The flame retardant is chemically bonded with the epoxy asphalt matrix, so that the limiting oxygen index of the epoxy asphalt concrete is more than 30%, while maintaining good mechanical properties, and the migration amount of the flame retardant is <0.8 μg / m 2 .

[0041] The epoxy-terminated phosphorus-silicon flame retardant has a phosphorus content of 7.2% to 9.7%, a silicon content of 6.5% to 8.8%, and an epoxy value of (0.23-0.50) eq / 100g. In some embodiments, the R1 in the structure of the epoxy-terminated phosphorus-silicon flame retardant is selected from mercapto, 2-(methoxymethyl)oxiranyl, acryloyloxy, and methacryloyloxy, and the R2 is selected from methyl, ethyl, propyl, and hydroxyl.

[0042] In addition, the present application also provides a preparation method of the epoxy asphalt reactive phosphorus-silicon flame retardant, which comprises the following steps:

[0043] (1) Hydrolysis reaction: mixing silane coupling agent and deionized water according to the molar ratio of 1: (3-5), adjusting pH to 3-5, reacting at temperature 25-70 °C under inert atmosphere for 1-3 hours, hydrolysis to generate liquid trihydroxysilane intermediate; the general formula of the silane coupling agent is [R1(CH2)3]Si(OCH3)3, R1 is selected from amino, mercapto, 2- (methoxymethyl) oxirane, acryloxy, diaminoethyl, methacryloxy.

[0044] (2) Phosphorylation reaction: adding alkyl phosphate and catalyst to the liquid trihydroxysilane intermediate obtained in step (1), adjusting pH to 7-8, reacting at temperature 60-100 °C for 3-5 hours to obtain reaction product; the general formula of the alkyl phosphate is R2P(=O)(OCH3)2, R2 is selected from methyl, ethyl, propyl, hydroxyl.

[0045] (3) Epoxy capping reaction: slowly adding epichlorohydrin to the reaction product obtained in step (2), reacting at 70-90 °C for 4-8 hours while removing the generated hydrogen chloride to obtain the final reaction product, a light yellow liquid, which is the epoxy asphalt reaction type phosphorus-silicon flame retardant.

[0046] In some embodiments, the silane coupling agent in step (1) is selected from one or more than two of 3-aminopropyltrimethoxysilane (KH-540), 3- aminopropyltriethoxysilane (KH-550), 3-glycidyloxypropyltrimethoxysilane (KH-560), 3-trimethoxysilyl methyl acrylate propyl (KH-570), 3- mercaptopropyltrimethoxysilane (KH-590), N-3-trimethoxysilylpropyl ethylenediamine (KH-792), 3-trimethoxysilyl acrylate propyl (TMSPMA) or any combination thereof. The structural formula of KH-540 is “ ”, the structural formula of KH-550 is “ ”, the structural formula of KH-560 is “ ”, the structural formula of KH-570 is “ ”, the structural formula of KH-590 is “ ”, the structural formula of KH-792 is “ ”, and the structural formula of TMSPMA is “ ”.

[0047] In some embodiments, the hydrolysis reaction in step (1) is carried out under nitrogen protection, the stirring rate is 300 rpm, the pH of the reaction system is 3-5, and the liquid trihydroxysilane intermediate and methanol are generated. Distillation removes the generated methanol and deionized water in the beaker to obtain the trihydroxysilane intermediate.

[0048] In some embodiments, the liquid trihydroxysilane intermediate obtained in step (1) is added with 1.0-1.5 times the molar amount of silane coupling agent, dried alkyl phosphate ester and 0.3%-0.8% of catalyst (i.e. the catalyst accounts for 0.3%-0.8% of the total mass of the silane coupling agent and alkyl phosphate ester), and the pH of the reaction system is adjusted to 7-8.

[0049] The catalyst is selected from dibutyltin dilaurate. The alkyl phosphate ester is selected from dimethyl methylphosphonate (DMMP), dimethyl ethylphosphonate (DMEP), dimethyl propylphosphonate (DPrMP), or any combination of one or more of DMP. The structural formula of DMMP is , the structural formula of DMEP is , the structural formula of DPrMP is , and the structural formula of DMP is .

[0050] Preferably, the residual trace amount of water in the liquid alkyl phosphate ester is removed by drying at room temperature before being added to the reaction system. The residual trace amount of water is removed to prevent hydrolysis of the raw materials, to initiate side reactions, and the like, thereby ensuring high conversion and high purity of the product.

[0051] In some embodiments, the reaction product obtained in step (2) is slowly added with 1.2-1.8 times the molar amount of silane coupling agent, and the reaction is carried out at 70-90°C for 4-8 hours to obtain a light yellow liquid reaction end product, i.e. the epoxy asphalt reaction-type phosphorus-silicon flame retardant.

[0052] In addition, the present application also provides a flame-retardant modified epoxy asphalt, which comprises epoxy asphalt and the epoxy asphalt reaction-type phosphorus-silicon flame retardant as described in the present application.

[0053] In addition, the present application also provides a flame-retardant epoxy asphalt concrete, which comprises the epoxy asphalt reaction-type phosphorus-silicon flame retardant as described in the present application.

[0054] In some embodiments, the flame-retardant epoxy asphalt concrete comprises 5-15 parts by mass of the epoxy asphalt reaction-type phosphorus-silicon flame retardant as described in the present application.

[0055] In some embodiments, the flame-retardant epoxy asphalt concrete has an limiting oxygen index (LOI, %) > 30, a vertical burning rating (UL94) of V-0, and a flame retardant migration amount < 0.8 μg / m 2 .

[0056] In some embodiments, the flame-retardant epoxy asphalt concrete is prepared as follows:

[0057] (1) Heat 40-100 parts of road petroleum asphalt to melt, add 30-50 parts of bisphenol A epoxy resin and 0.3-1 part of silane coupling agent, and stir to form a mixed matrix. For example, stir at 800 rpm for 30 minutes to form a mixed matrix.

[0058] (2) Add 5-15 parts of the epoxy asphalt reactive phosphorus-silicon flame retardant as described in the present application, and stir uniformly at a temperature of 130-160°C. For example, disperse at 1200 rpm for 30 minutes at a temperature of 150°C to stir uniformly.

[0059] (3) Reduce the temperature to 110-130°C, add a curing agent and an accelerator, stir uniformly, and then cure to obtain a flame-retardant epoxy asphalt mixture. For example, reduce the temperature to 120°C, add 5-8 parts of a curing agent and 1-2 parts of an accelerator, stir uniformly, and then add 1000-1500 parts of mineral aggregate basalt heated to 170-180°C, stir at 110-130°C for 5 min ± 5 s, and obtain a flame-retardant epoxy asphalt concrete after curing. In some embodiments, the curing in step (3) is 60°C curing for 24 hours.

[0060] The curing agent is selected from a polyamide curing agent and a fatty amine curing agent; and the accelerator is an imidazole accelerator selected from 2-methylimidazole and 2-ethyl-4-methylimidazole.

[0061] The following are examples

[0062] The following examples use the following compounds as silane coupling agents, alkyl phosphate esters, and epoxy chloropropane.

[0063] Table 1 Structure of compounds of silane coupling agents, alkyl phosphate esters, and epoxy chloropropane

[0064]

[0065] Example 1

[0066] 1. Preparation of a reactive flame retardant for epoxy asphalt

[0067] (1) Hydrolysis reaction: add 1 mol of silane coupling agent (KH-560, 3-glycidyloxypropyltrimethoxysilane) and 3 mol of deionized water to a 500 mL four-necked flask, adjust the pH to 3.2 with dilute hydrochloric acid under nitrogen protection, stir at 300 rpm, and react at 40°C for 2 hours to hydrolyze to form a liquid trihydroxysilane intermediate and methanol. Distill off the generated methanol and the deionized water in the beaker to obtain the trihydroxysilane intermediate.

[0068] (2) Phosphorylation reaction: 1.2 mol of dimethyl methylphosphonate (DMMP) and 0.5% of dibutyltin dilaurate (DBTDL) based on the total mass of the raw material were added to the liquid trihydroxysilane intermediate obtained in step (1), and the temperature was raised to 60°C for 4 hours of reaction.

[0069] (3) Epoxy capping reaction: 1.5 mol of epichlorohydrin was slowly added dropwise to the product obtained in step (2), and the reaction was carried out at 80°C for 6 hours. During the reaction, triethylamine was used to adjust the pH to 7.2, and the byproduct hydrogen chloride gas was eliminated. Attention should be paid to the collection of the tail gas. After the reaction was completed, the product (epoxy-capped phosphosilicon flame retardant) was obtained by distillation under reduced pressure, which was a light yellow transparent product. The epoxy asphalt reactive phosphosilicon flame retardant had a phosphorus content of 7.6%, a silicon content of 6.8%, and an epoxy value of 0.50 eq / 100 g. The infrared spectrum of the flame retardant synthesized in this example is shown in FIG. 1. Figure 2

[0070] The epoxy value refers to the number of equivalents of epoxy groups (-CH2-CH(O)-CH2-) contained in 100 g of epoxy resin. The larger the epoxy value, the more epoxy groups there are in 100 g of resin, and the smaller the molecular weight, and the lower the viscosity of the resin. The smaller the epoxy value, the larger the molecular weight, and the relatively higher the viscosity.

[0071] 2. Preparation of epoxy asphalt concrete:

[0072] 40 parts of bisphenol A type epoxy resin (epoxy value 0.4 eq / 100 g), 60 parts of road petroleum asphalt (penetration (25°C, 100 g, 5 s) 70 (0.1 mm)), 8 parts of polyamide curing agent (amine value 250 mgKOH / g), 1 part of 2-methylimidazole, and 0.8 part of silane coupling agent KH-560.

[0073] ① According to the mass fraction, 60 parts of road petroleum asphalt was heated to 140°C for melting, 40 parts of bisphenol A epoxy resin and 0.8 parts of KH-560 were added, and stirring was carried out at 800 rpm for 30 minutes.

[0074] ② 6 parts of the above epoxy-capped phosphosilicon flame retardant was added, and dispersion was carried out at 150°C and 1200 rpm for 1 hour.

[0075] ③ The temperature was lowered to 120°C, 8 parts of polyamide curing agent and 1 part of 2-methylimidazole accelerator were added, stirring was carried out at 3000 rpm for 1 min, and then 1300 parts of AC-13 mineral aggregate basalt at 180°C was added. The stirring was carried out at 120°C for 5 min to obtain the epoxy asphalt concrete.

[0076] The Marshall compaction instrument was used to form the test piece (Φ101.6 mm x 63.5 mm), which was cured at 120°C for 4 h and cooled to room temperature for standby. ​

[0077] Table 2 Asphalt concrete AC-13 aggregate gradation passing range

[0078]

[0079] Example 2

[0080] 1. Preparation of reactive flame retardant for epoxy asphalt

[0081] (1) Hydrolysis reaction: 1 mol of silane coupling agent (KH-560, 3-glycidyloxypropyltrimethoxysilane) and 3 mol of deionized water were added to a 500 mL four-necked flask, the pH was adjusted to 3.2 with dilute hydrochloric acid under nitrogen protection, stirred at 300 rpm, and reacted at 40°C for 2 hours. The hydrolysis generated liquid trihydroxysilane intermediates and methanol, and the generated methanol and deionized water in the beaker were removed by distillation to obtain the trihydroxysilane intermediates.

[0082] (2) Phosphorylation reaction: 1.2 mol of dimethyl ethyl phosphate (DMEP) and 0.5% of DBTDL based on the total mass of the raw materials were added to the liquid trihydroxysilane intermediates obtained in step (1), and the temperature was raised to 60°C for reaction for 4 hours.

[0083] (3) Epoxy capping reaction: 1.5 mol of epoxy chloropropane was slowly added to the product obtained in step (2), and the reaction was carried out at 80°C for 6 hours. During the reaction, the pH was adjusted to 7.2 with triethylamine, and the generated HCl gas was eliminated. Attention should be paid to collect the tail gas. After the reaction was completed, the epoxy-capped phosphorus-silicon flame retardant was obtained by distillation under reduced pressure, which was a light yellow transparent liquid. The phosphorus content was 7.6%, the silicon content was 6.7%, and the epoxy value was 0.48 eq / 100 g.

[0084] 2. Preparation of epoxy asphalt concrete:

[0085] 40 parts of bisphenol A type epoxy resin (epoxy value 0.4 eq / 100 g), 60 parts of road petroleum asphalt (penetration (25°C, 100 g, 5 s) 70 (0.1 mm)), 8 parts of polyamide curing agent (amine value 250 mg KOH / g), 1 part of 2-methylimidazole, and 0.8 part of silane coupling agent KH-560.

[0086] ① According to the mass fraction, 60 parts of road petroleum asphalt were heated to 140°C for melting, 40 parts of bisphenol A epoxy resin and 0.8 parts of KH-560 were added, and stirred at 800 rpm for 30 minutes;

[0087] ② 6 parts of the above epoxy-capped phosphorus-silicon flame retardant was added, and dispersed at 150°C and 1200 rpm for 1 hour;

[0088] ③Cool down to 120℃, add 8 parts of polyamide curing agent and 1 part of 2-methyl imidazole accelerator, stir at 3000 rpm for 1 min, then add 1300 parts of AC-13 mineral aggregate basalt at 180℃, stir at 120℃ for 5 min, to obtain epoxy asphalt concrete.

[0089] The test piece (Φ101.6mm×63.5mm) was formed by using Marshall compaction instrument, cured at 120℃ for 4h, and cooled to room temperature for standby.

[0090] Example 3

[0091] 1. Preparation of reactive flame retardant for epoxy asphalt

[0092] (1) Hydrolysis reaction: 1 mol of silane coupling agent (KH-590, 3-mercaptopropyl trimethoxysilane) and 3 mol of deionized water were added to a 500 mL four-necked flask, and the pH was adjusted to 3.2 with dilute hydrochloric acid under nitrogen protection, stirred at 300 rpm, and reacted at 60℃ for 2 hours to generate liquid trihydroxysilane intermediates and methanol. Distillation was performed to remove the generated methanol and deionized water in the beaker to obtain the trihydroxysilane intermediates.

[0093] (2) Phosphorylation reaction: 1.2 mol of dimethyl methylphosphonate (DMMP) and 0.5% of DBTDL based on the total mass of the raw materials were added to the liquid trihydroxysilane intermediates obtained in step (1), and the temperature was raised to 70℃ for reaction for 4 hours.

[0094] (3) Epoxy capping reaction: 1.5 mol of epoxy chloropropane was slowly added to the product obtained in step (2), and reacted at 80℃ for 6 hours. During the reaction, triethylamine was used to adjust the pH to 7.2, and the byproduct hydrogen chloride gas was eliminated. The tail gas was collected. After the reaction was completed, the product (epoxy-capped phosphorus-silicon flame retardant) was obtained by distillation under reduced pressure. The product was a light yellow transparent product, which was an epoxy asphalt reactive phosphorus-silicon flame retardant. The phosphorus content was 8.9%, the silicon content was 8.0%, and the epoxy value was 0.28 eq / 100g.

[0095] 2. Preparation of epoxy asphalt concrete:

[0096] 40 parts of bisphenol A type epoxy resin (epoxy value 0.4 eq / 100g), 60 parts of road petroleum asphalt (penetration (25℃, 100g, 5s) 70 (0.1mm)), 8 parts of polyamide curing agent (amine value 250mgKOH / g), 1 part of 2-methyl imidazole accelerator, and 0.8 parts of silane coupling agent KH-560.

[0097] ①According to the mass fraction, 60 parts of road petroleum asphalt was heated to 140℃ to melt, 40 parts of bisphenol A epoxy resin and 0.8 parts of KH-560 were added, and stirred at 800 rpm for 30 minutes.

[0098] ②Add 6 parts of the above epoxy-terminated phosphorus-silicon flame retardant, 150°C, 1200 rpm for 1 hour;

[0099] ③Cool to 120°C, add 8 parts of polyamide curing agent and 1 part of 2-methyl imidazole accelerator, stir at 3000 rpm for 1 min, then add 1300 parts of AC-13 mineral aggregate basalt at 180°C, stir at 120°C for 5 min, to obtain epoxy asphalt concrete.

[0100] Use Marshall compaction instrument to shape the test piece (Φ101.6mm×63.5mm), 120°C curing for 4h, and cool to room temperature for standby.

[0101] Example 4

[0102] 1. Preparation of reactive flame retardant for epoxy asphalt

[0103] (1) Hydrolysis reaction: 1 mol of silane coupling agent (KH-570, 3-trimethoxysilyl methyl methacrylate) and 3 mol of deionized water were added to a 500 mL four-necked flask, and the pH was adjusted to 3.2 with dilute hydrochloric acid under nitrogen protection, stirred at 300 rpm, and reacted at 50°C for 2 hours. Hydrolysis generates liquid trihydroxysilane intermediates and methanol, which are removed by distillation to obtain trihydroxysilane intermediates.

[0104] (2) Phosphorylation reaction: To the liquid trihydroxysilane intermediates obtained in step (1), 1.2 mol of dimethyl ethyl phosphate (DMEP) and 0.5% of DBTDL based on the total mass of the raw materials were added, and the temperature was raised to 60°C for 4 hours.

[0105] (3) Epoxy termination reaction: Slowly add 1.5 mol of epoxy chloropropane to the product obtained in step (2), and react at 80°C for 6 hours. During the reaction, adjust the pH to 7.2 with triethylamine and eliminate the byproduct hydrogen chloride gas. Note that the tail gas should be collected. After the reaction is completed, distill under reduced pressure to obtain a light yellow transparent product (epoxy-terminated phosphorus-silicon flame retardant), which is the epoxy asphalt reactive phosphorus-silicon flame retardant. The phosphorus content is 7.5%, the silicon content is 6.8%, and the epoxy value is 0.25 eq / 100g.

[0106] 2. Preparation of epoxy asphalt concrete:

[0107] Bisphenol A type epoxy resin (epoxy value 0.4 eq / 100g) 40 parts, road petroleum asphalt (penetration (25°C, 100g, 5s) 70 (0.1mm)) 60 parts, polyamide curing agent (amine value 250mgKOH / g) 8 parts, 2-methyl imidazole 1 part, 0.8 parts of silane coupling agent KH-560.

[0108] ① 60 parts of road petroleum asphalt was heated to 140℃ to melt, 40 parts of bisphenol A epoxy resin and 0.8 parts of KH-560 were added, and stirred at 3000 rpm for 30 minutes;

[0109] ② 10 parts of the above-mentioned epoxy-terminated phosphorus-silicon flame retardant was added, and dispersed at 150℃ and 1200 rpm for 1 hour;

[0110] ③ The temperature was lowered to 120℃, 8 parts of polyamide curing agent and 1 part of 2-methylimidazole accelerator were added, stirred at 3000 rpm for 1 min, then 1300 parts of AC-13 mineral aggregate basalt at 180℃ was added, stirred at 120℃ for 5 min, to obtain epoxy asphalt concrete.

[0111] The test piece (Φ101.6mm×63.5mm) was formed by using Marshall compaction instrument, and was cured at 120℃ for 4h, and cooled to room temperature for standby.

[0112] Comparative Example 1

[0113] An epoxy asphalt concrete, which was composed of the following raw materials by weight: bisphenol A type epoxy resin (epoxy value was 0.4 eq / 100g) 40 parts, road petroleum asphalt (penetration (25℃, 100g, 5s) was 70 (0.1mm)) 60 parts, decabromodiphenyl ethane 6 parts, polyamide curing agent (amine value was 250mgKOH / g) 8 parts, 2-methylimidazole 1 part, 0.8 parts of silane coupling agent KH-560 and AC-13 mineral aggregate basalt 1300 parts. The preparation method was the same as Example 1, except that the epoxy-terminated phosphorus-silicon flame retardant was replaced by decabromodiphenyl ethane (conventional flame retardant).

[0114] Comparative Example 2

[0115] (1) Hydrolysis reaction: 1 mol of silane coupling agent (KH-560, 3-glycidyloxypropyltrimethoxysilane) and 3 mol of deionized water were added to a 500 mL four-necked flask, and the pH was adjusted to 3.2 with dilute hydrochloric acid under nitrogen protection, stirred at 300 rpm, and reacted at 40℃ for 2 hours. Liquid trihydroxysilane intermediates and methanol were generated by hydrolysis, and the generated methanol and deionized water in the beaker were distilled to obtain the trihydroxysilane intermediates.

[0116] (2) Phosphorylation reaction: 1.2 mol of dimethyl methylphosphonate (DMMP) and 0.5% of DBTDL based on the total mass of the raw materials were added to the liquid trihydroxysilane intermediates obtained in step (1), and the temperature was raised to 60℃ for 4 hours. The reaction product containing only the original epoxy group of KH-560 was obtained, with a phosphorus content of 10.7%, a silicon content of 9.7%, and an epoxy value of 0.28 eq / 100g.

[0117] Preparation of epoxy asphalt concrete:

[0118] The preparation method is the same as that of Example 1, except that the epoxy-terminated phosphorus-silicon flame retardant is replaced by the flame retardant (a reaction product containing only KH-560 original epoxy group) described above.

[0119] In order to describe the present application in more detail, 100 parts of epoxy asphalt were added with 6 parts of the epoxy-terminated phosphorus-silicon flame retardant prepared in Examples 1-4 to prepare modified epoxy asphalt, and the modified epoxy asphalt was tested for performance. At the same time, the conventional flame retardant decabromodiphenyl ethane was used as Comparative Example 1, and the flame retardant without epoxy encapsulation reaction was used as Comparative Example 2, and the modified epoxy asphalt was tested for performance, such as limiting oxygen index test (NB / SH / T 0815-2010), vertical combustion test (GB / T 2408), Cleveland open cup method (GB / T 3536), smoke density box method (GB / T 8627-2007), direct tensile method (ASTM D638-22), and the test results are shown in Table 3 below.

[0120] Table 3 Performance test results of flame-retardant modified epoxy asphalt

[0121]

[0122] Compared with the conventional flame retardant of Comparative Example 1, the epoxy-terminated phosphorus-silicon flame retardants synthesized in Examples 1-4 using silane coupling agents KH-560, KH-570, KH-590 and alkyl phosphate DMMP, DMEP as raw materials all showed higher limiting oxygen index, and had higher vertical combustion grade, especially the epoxy-terminated phosphorus-silicon flame retardant synthesized by using alkyl phosphate DMMP for phosphorylation reaction had higher limiting oxygen index.

[0123] Compared with the phosphorus-silicon flame retardant without using epoxy chloropropane encapsulation of Comparative Example 2, the epoxy-terminated phosphorus-silicon flame retardants using epoxy chloropropane encapsulation in Examples 1-4 all showed higher limiting oxygen index. It is shown that compared with the existing flame retardant, the flame retardant effect of the epoxy-terminated phosphorus-silicon flame retardant prepared in the present application is better, and when it is used to prepare epoxy asphalt mixture such as epoxy asphalt concrete, the building material is more difficult to burn and has stronger combustion safety, and can be used as flame-retardant epoxy asphalt concrete, which is applied to tunnel, airport and other construction scenes.

[0124] The epoxy asphalt concretes prepared in Examples 1-4 and Comparative Examples 1 and 2 were respectively tested for performance, such as spalling test, Marshall stability test, rutting test, freeze-thaw splitting test, migration amount, according to JTG3410-2025, and the test results are shown in Table 4 below.

[0125] Migration test: prepare a size of 5 cm x 5 cm x 2 cm flame-retardant epoxy asphalt concrete test piece, 163℃ aging for 48 h, then completely immerse the test piece in a certain volume of deionized water, 25℃ soaking for 7 days, after soaking, use high performance liquid chromatography (HPLC) to detect the concentration of flame retardant in the soaking solution, calculate the migration amount of flame retardant per unit area (unit: μg / m²).

[0126] Table 4 Performance test results of epoxy asphalt concrete

[0127]

[0128] Compared with the epoxy asphalt concrete prepared by adding the conventional flame retardant in Comparative Example 1, the epoxy asphalt concrete prepared by adding the epoxy-capped phosphosilicon flame retardant in Examples 1 to 4 has higher freeze-thaw splitting strength ratio and lower migration amount. It is illustrated that the epoxy-capped phosphosilicon flame retardant prepared according to the method can not only improve the flame-retardant performance of the epoxy asphalt concrete, but also enhance the mechanical properties of the epoxy asphalt concrete, improve the road performance, and can be applied to application scenarios with high requirements for the flame-retardant effect, mechanical strength and use stability of building materials.

[0129] Those skilled in the art will readily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an epoxy asphalt reactive phosphorus-silicon flame retardant, characterized by, The method comprises the following steps: (1) Hydrolysis reaction: mixing silane coupling agent and deionized water according to the molar ratio of 1: (3-5), adjusting the pH of the system to 3-5, and reacting at 25-70℃ under inert atmosphere for 1-3 hours to hydrolyze to generate liquid trihydroxysilane intermediate; the general formula of the silane coupling agent is [R1(CH2)3]Si(OCH3)3, and R1 is selected from amino, mercapto, 2- (methoxymethyl) oxirane, acryloxy, diaminoethyl, or methacryloxy; (2) Phosphorylation reaction: adding alkyl phosphate in an amount of 1.0-1.5 times the molar amount of the silane coupling agent to the liquid trihydroxysilane intermediate obtained in step (1), adding a catalyst in an amount of 0.3%-0.8% of the total mass of the reactants, and reacting at 60-100℃ for 3-5 hours to obtain a reaction product; the general formula of the alkyl phosphate is R2P(=O)(OCH3)2, and R2 is methyl, ethyl, propyl, or hydroxyl; (3) Epoxy capping reaction: slowly adding epichlorohydrin to the reaction product obtained in step (2), adjusting the pH of the system to 7-8, and reacting at 70-90℃ for 4-8 hours while removing the generated hydrogen chloride to obtain a light yellow transparent final reaction product, which is the epoxy asphalt reaction-type phosphorus-silicon flame retardant.

2. The method of claim 1, wherein, The silane coupling agent in step (1) is selected from one or more of KH-540, KH-560, KH-570, KH-590, KH-792, and TMSPMA.

3. The method of claim 2, wherein, The alkyl phosphate in step (2) is selected from one or more of dimethyl methylphosphonate DMMP, dimethyl ethylphosphonate DMEP, and dimethyl propylphosphonate DPrMP; and the catalyst is selected from dibutyltin dilaurate, which is added in an amount of 0.3%-0.8% of the total mass of the silane coupling agent and the alkyl phosphate.

4. The method of claim 3, wherein, In step (3), the amount of added epichlorohydrin is 1.2-1.8 times the molar amount of the silane coupling agent.

5. An epoxy asphalt reactive phosphorus-silicon flame retardant, characterized by, Prepared according to the method of any one of claims 1 to 4.

6. A flame-retardant modified epoxy bitumen, characterized in that, Comprises epoxy asphalt and the epoxy asphalt reaction-type phosphorus-silicon flame retardant of claim 5.

7. A flame-retardant epoxy asphalt concrete, characterized by, Comprises the epoxy asphalt reaction-type phosphorus-silicon flame retardant of claim 5; the limiting oxygen index of the flame-retardant epoxy asphalt concrete is >30%, and the vertical burning rating is V-0.

8. The fire-retardant epoxy asphalt concrete of claim 7, wherein, Prepared according to the following method: Heat 40-100 parts of asphalt base to melting, add 30-50 parts of bisphenol A epoxy resin and 0.3-1 part of silane coupling agent, and stir uniformly to form a mixed base; Add 5-15 parts of the epoxy asphalt reaction-type phosphorus-silicon flame retardant of claim 5, and heat to 130-160℃ and stir uniformly; Cool to 110-130℃, add a curing agent and an accelerator, stir uniformly, then add 1000-1500 parts of mineral aggregate heated to 170-180℃, and stir at 110-130℃ for 5min±5s, and the flame-retardant epoxy asphalt concrete is obtained after curing.

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