Curing agent and preparation method thereof, concrete surface protective agent and preparation method thereof, concrete

Abstract

The present invention discloses a curing agent and a preparation method thereof, a concrete surface protective agent and a preparation method thereof, and concrete, and relates to the technical field of concrete admixtures. The preparation method of the curing agent comprises the following steps: mixing a polyamine compound, a halogenated methylbenzyl alcohol, an alkaline agent, and an organic solvent, performing a first substitution reaction, and obtaining a first intermediate; mixing the first intermediate, cyanuric chloride, an alkaline agent, and an organic solvent, performing a second substitution reaction, and obtaining a second intermediate; mixing the second intermediate, thionyl chloride, an alkaline agent, and an organic solvent, performing a chlorination reaction, and obtaining a third intermediate; mixing the third intermediate, urea, an alkaline agent, and an organic solvent, and performing a third substitution reaction, and obtaining a curing agent. The curing agent prepared by the technical solution of the present invention is beneficial for improving the toughness, impact resistance, and mechanical properties of the concrete surface protective agent, and solves the problem that the existing concrete surface protective agent is easily ineffective.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete admixtures, in particular to a curing agent and a preparation method thereof, a concrete surface protective agent and a preparation method thereof, and concrete. Background Art

[0002] Concrete is one of the most widely used and versatile materials in civil engineering, widely used in the construction of roads, bridges, tunnels, and other projects. Because concrete is porous and brittle, the intrusion of atmospheric particles such as carbon dioxide, chloride ions, and sulfates, as well as carbonization of the concrete, can lead to a decline in system performance and ultimately concrete failure during its service life.

[0003] Using concrete surface protectants to create a protective coating on concrete surfaces is one of the most effective methods for extending the service life of concrete. Epoxy resins, due to their excellent mechanical properties and chemical resistance, have become a key component of concrete surface protectants. Bisphenol A epoxy resin combined with an amino curing agent is a commonly used classic combination. After curing, the epoxy resin exhibits a highly cross-linked structure. However, cured epoxy resins are brittle and prone to cracking when subjected to external forces. They also have a poor ability to inhibit crack expansion, ultimately making the protective coating susceptible to failure.

[0004] Therefore, existing concrete surface protective agents still have the problem of being easily ineffective. Summary of the Invention

[0005] The main purpose of the present invention is to provide a curing agent and a preparation method thereof, a concrete surface protective agent and a preparation method thereof, and concrete, aiming to solve the problem that existing concrete surface protective agents are prone to failure.

[0006] To achieve the above object, the present invention provides a method for preparing a curing agent, comprising the following steps:

[0007] Mixing a polyamine compound, a halogenated methylbenzyl alcohol, an alkaline reagent and an organic solvent to perform a first substitution reaction to obtain a first intermediate, wherein the first intermediate includes an alcohol containing an amino group;

[0008] mixing the first intermediate, cyanuric chloride, an alkaline reagent and an organic solvent, and performing a second substitution reaction to obtain a second intermediate;

[0009] The second intermediate, thionyl chloride, an alkaline reagent and an organic solvent are mixed to carry out a chlorination reaction to obtain a third intermediate;

[0010] The third intermediate, urea, an alkaline reagent and an organic solvent are mixed and a third substitution reaction is carried out to obtain a curing agent.

[0011] In one embodiment, the polyamine compound includes any one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine and ethylenediamine; and / or,

[0012] The halogenated methylbenzyl alcohol includes any one of 4-(chloromethyl)benzyl alcohol, 4-(bromomethyl)benzyl alcohol and 4-(iodomethyl)benzyl alcohol; and / or,

[0013] The alkaline reagent includes at least one of diethylamine, triethylamine and pyridine; and / or,

[0014] The organic solvent comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide and toluene; and / or,

[0015] The temperature of the first substitution reaction is 0-5°C; the time is 10-15h; and / or,

[0016] The temperature of the second substitution reaction is 20 to 30° C. and the time is 22 to 26 hours; and / or,

[0017] The chlorination reaction temperature is 40-45°C; the time is 4-6 hours; and / or,

[0018] The temperature of the third substitution reaction is 45-50° C. and the time is 10-15 hours; and / or,

[0019] The molar ratio of the polyamine compound, the halogenated methylbenzyl alcohol and the alkaline agent is (0.9-1.1):1:(0.4-0.6); and / or,

[0020] The molar ratio of the first intermediate, cyanuric chloride and alkaline reagent is 3: (0.7-1.2): (1.2-1.7); and / or,

[0021] The molar ratio of the second intermediate, thionyl chloride and alkaline reagent is 1: (1.6-1.8): (1.2-1.6); and / or,

[0022] The molar ratio of the third intermediate, urea and alkaline reagent is 1: (1.2-1.4): (2.8-3.2).

[0023] The present invention provides a curing agent, which is prepared by the curing agent preparation method.

[0024] The present invention provides a method for preparing a concrete surface protective agent, which is prepared using the curing agent. The method for preparing the concrete surface protective agent comprises the following steps:

[0025] mixing epoxy resin, diluent and white carbon black to obtain a mixture;

[0026] Add curing agent to the mixture to obtain concrete surface protective agent

[0027] In one embodiment, the diluent comprises any one of neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether and C12-14 alkyl glycidyl ether; and / or,

[0028] The epoxy resin includes E51 epoxy resin; and / or,

[0029] The mass ratio of the epoxy resin, white carbon black and curing agent is 40:(1-10):(12-15).

[0030] In one embodiment, the white carbon black is prepared by the following preparation method:

[0031] A silane coupling agent, an amino compound and a metal catalyst are mixed to carry out a cross-linking reaction to obtain an amino-modified silane coupling agent;

[0032] Mix the amino-modified silane coupling agent and silica.

[0033] In one embodiment, the silane coupling agent includes decamethyldihydrogenpentasiloxane; and / or,

[0034] The amino compound includes 1,4-diamino-2,5-divinylbenzene; and / or,

[0035] The metal catalyst includes a platinum catalyst; and / or,

[0036] The molar ratio of the silane coupling agent to the amino compound is 1:(1.0-1.2); and / or,

[0037] The mass ratio of the silane coupling agent to the metal catalyst is 1000:(0.003-0.005).

[0038] In one embodiment, the step of mixing the amino-modified silane coupling agent and white carbon black comprises:

[0039] Mixing white carbon black and isopropyl alcohol to obtain a white carbon black suspension; mixing an amino-modified silane coupling agent and ethanol to obtain an amino-modified silane coupling agent solution;

[0040] The silica suspension and the amino-modified silane coupling agent solution are mixed.

[0041] The present invention provides a concrete surface protective agent, which is prepared by the concrete surface protective agent preparation method.

[0042] The present invention provides concrete, which includes the concrete surface protective agent.

[0043] The technical solution of the present invention uses polyamine compounds and halogenated methylbenzyl alcohol as starting materials, and obtains a curing agent rich in amino functional groups and imino functional groups through substitution reaction and chlorination reaction, and introduces a flexible segment into the curing agent. The rich amino and imino groups on the curing agent can increase the reaction sites with the epoxy resin, which is beneficial to increase the crosslinking density of the resin system after curing in the subsequent curing process, thereby improving the overall physical properties of the concrete surface protective agent; the introduction of a flexible segment into the curing agent can improve the toughness of the epoxy resin system after curing, thereby reducing the possibility of cracks in the concrete surface protective agent after being subjected to external force, and improving the impact resistance of the concrete surface protective agent. In addition, the curing agent prepared by the preparation method of the present invention also has tertiary amino groups and benzene rings, which can promote the curing of the epoxy resin system, thereby improving the mechanical properties of the concrete surface protective agent. Therefore, the curing agent prepared using the technical solution of the present invention can improve the toughness, impact resistance and mechanical properties of the concrete surface protective agent, and is used to solve the problem that the existing concrete surface protective agent is easy to fail. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0045] Figure 1 This is a synthetic route for the curing agent provided in Example 1 of the present invention;

[0046] Figure 2 This is a synthetic route diagram of the silane coupling agent provided in Example 1 of the present invention.

[0047] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0050] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] Concrete is one of the most widely used and versatile materials in civil engineering, widely used in the construction of roads, bridges, tunnels, and other projects. Because concrete is porous and brittle, the intrusion of atmospheric particles such as carbon dioxide, chloride ions, and sulfates, as well as carbonization of the concrete, can lead to a decline in system performance and ultimately concrete failure during its service life.

[0052] Using concrete surface protective agents to prepare protective coatings on the concrete surface is one of the effective methods to increase the service life of concrete. Epoxy resin has become an important component of concrete surface protective agents due to its excellent mechanical properties and chemical corrosion resistance. Among them, bisphenol A epoxy resin combined with amino curing agent is a commonly used classic combination. After curing, the epoxy resin presents a highly cross-linked structure. However, the cured epoxy resin is relatively brittle and easily cracks when subjected to external forces. It also has a poor ability to prevent crack expansion, which ultimately makes the protective coating prone to failure. Therefore, existing concrete surface protective agents still have the problem of easy failure, which leads to concrete failure and shortened service life.

[0053] In view of this, the present invention proposes a method for preparing a curing agent, comprising the following steps:

[0054] Mixing a polyamine compound, a halogenated methylbenzyl alcohol, an alkaline reagent and an organic solvent to perform a first substitution reaction to obtain a first intermediate, wherein the first intermediate includes an alcohol containing an amino group;

[0055] mixing the first intermediate, cyanuric chloride, an alkaline reagent and an organic solvent, and performing a second substitution reaction to obtain a second intermediate;

[0056] The second intermediate, thionyl chloride, an alkaline reagent and an organic solvent are mixed to carry out a chlorination reaction to obtain a third intermediate;

[0057] The third intermediate, urea, an alkaline reagent and an organic solvent are mixed and a third substitution reaction is carried out to obtain a curing agent.

[0058] In order to improve the flexibility and reactivity of the curing agent, the technical solution of the present invention produces a curing agent rich in amino and imino functional groups through substitution reaction and chlorination reaction, and introduces a flexible chain segment into the curing agent. The rich amino and imino groups on the curing agent can increase the reaction sites with the epoxy resin, which is beneficial to increase the crosslinking density of the resin system after curing in the subsequent curing process, thereby improving the overall physical properties of the concrete surface protective agent; the introduction of a flexible chain segment into the curing agent can improve the toughness of the epoxy resin system after curing, thereby reducing the possibility of cracks in the concrete surface protective agent after being subjected to external force, and improving the impact resistance of the concrete surface protective agent. In addition, the curing agent prepared by the preparation method of the present invention also has tertiary amino groups and benzene rings, which can promote the curing of the epoxy resin system, thereby improving the mechanical properties of the concrete surface protective agent. Therefore, the curing agent prepared using the technical solution of the present invention can improve the toughness, impact resistance and mechanical properties of the concrete surface protective agent, and is used to solve the problem that the existing concrete surface protective agent is easy to fail.

[0059] In the technical solution of the present invention, a polyamine compound and a halogenated methylbenzyl alcohol are used as starting materials. First, the polyamine compound acts as a nucleophile to attack the carbon cation or polarized carbon-halogen bond in the halogenated methylbenzyl alcohol, initiating a substitution reaction to obtain a first intermediate containing a benzene ring and an amino group. Subsequently, the first intermediate acts as a nucleophile to attack the carbon cation or polarized carbon-halogen bond in cyanuric chloride, initiating a substitution reaction to obtain a second intermediate. The second intermediate increases the number of benzene rings, amino groups, and imino groups compared to the first intermediate, while introducing a flexible carbon chain. Subsequently, the second intermediate undergoes a chlorination reaction with thionyl chloride to obtain a third intermediate containing a carbon-halogen bond, so as to proceed to the next substitution reaction. Subsequently, the third intermediate undergoes a substitution reaction with urea to further increase the imino structure and adjust the carbon chain length to obtain a curing agent. During the substitution reaction or chlorination reaction, an alkaline agent is added to neutralize the acid generated by the reaction to promote the forward reaction.

[0060] In an embodiment of the present invention, the polyamine compound comprises any one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenediamine and ethylenediamine. Using polyamine compounds can increase the amino structure in the prepared curing agent. Although the increase of amine groups is conducive to introducing more amino groups in the curing agent, the cost also increases therewith. Taking into account the use cost and the fact that longer side chains may cause the mechanical properties of the epoxy resin as a whole to decline, in one embodiment of the present invention, the polyamine compound preferably uses diethylenetriamine.

[0061] In an embodiment of the present invention, the halomethyl benzyl alcohol includes any one of 4-(chloromethyl) benzyl alcohol, 4-(bromomethyl) benzyl alcohol and 4-(iodomethyl) benzyl alcohol. Using halomethyl benzyl alcohol as raw material, phenyl ring can be introduced in curing agent, which is conducive to promoting the heat resistance and mechanical property of resin, and the alcohol in halomethyl benzyl alcohol is utilized to carry out follow-up chlorination, the halogen atom in halomethyl benzyl alcohol is utilized to carry out substitution reaction, thereby introducing flexible long chain and polyamino structure. Taking into account cost of use and reactivity, in one embodiment of the present invention, 4-(chloromethyl) benzyl alcohol is preferably used.

[0062] In an embodiment of the present invention, the alkaline reagent comprises at least one of diethylamine, triethylamine and pyridine. The alkaline reagent is added to neutralize the acid generated during the reaction to promote the reaction and avoid the adverse effects of acid accumulation on the reaction.

[0063] In an embodiment of the present invention, the organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide and toluene.

[0064] In an embodiment of the present invention, the temperature of the first substitution reaction is 0-5° C. and the time is 10-15 hours.

[0065] Setting the temperature of the first substitution reaction to 0-5°C is beneficial for controlling the reaction rate. A temperature too high will result in an overly vigorous reaction, while a temperature below this temperature may result in an overly slow reaction rate and a prolonged reaction time. In one embodiment of the present invention, the temperature of the first substitution reaction is set to 0°C and the reaction time is set to 13 hours.

[0066] In an embodiment of the present invention, the temperature of the second substitution reaction is 20-30° C. and the time is 22-26 hours.

[0067] Setting the second substitution reaction temperature to 20-30°C and the reaction time to 22-26 hours facilitates a full reaction and reduces the possibility of byproducts. Exceeding this temperature and time range may lead to the formation of byproducts. In one embodiment of the present invention, the second substitution reaction is set to proceed at 25°C for 24 hours.

[0068] In an embodiment of the present invention, the temperature of the chlorination reaction is 40-45° C. and the time is 4-6 hours.

[0069] When the temperature of the chlorination reaction is set to 40-45°C and the time of the chlorination reaction is set to 4-6 hours, the chemical reaction rate is relatively moderate. Exceeding this temperature and time range is not conducive to controlling the occurrence of side reactions. In one embodiment of the present invention, the temperature of the chlorination reaction is set to 43°C and the time of the chlorination reaction is set to 5 hours.

[0070] In an embodiment of the present invention, the temperature of the third substitution reaction is 45-50° C. and the time is 10-15 hours.

[0071] Setting the third substitution reaction to be carried out at this reaction temperature and reaction time is conducive to ensuring that the reaction is fully complete and reducing the production of by-products. Exceeding the temperature range may cause side reactions, and falling below the temperature range may cause the reaction rate to be too slow. In one embodiment of the present invention, the temperature of the third substitution reaction is set to 47°C and the time of the third substitution reaction is 13 hours.

[0072] In an embodiment of the present invention, the molar ratio of the polyamine compound, the halogenated methylbenzyl alcohol, and the alkaline agent is (0.9-1.1):1:(0.4-0.6). Setting the molar ratio of the polyamine compound, the halogenated methylbenzyl alcohol, and the alkaline agent within the above range is beneficial to reducing the occurrence of side reactions. Exceeding or falling below this range may be detrimental to controlling the occurrence of side reactions.

[0073] In an embodiment of the present invention, the molar ratio of the first intermediate, cyanuric chloride, and alkaline agent is 3:(0.7-1.2):(1.2-1.7). Setting the molar ratio of the first intermediate, cyanuric chloride, and alkaline agent within the above range is beneficial to reducing the occurrence of side reactions. Exceeding or falling below this range may be detrimental to controlling the occurrence of side reactions.

[0074] In an embodiment of the present invention, the molar ratio of the second intermediate, thionyl chloride, and alkaline agent is 1:(1.6-1.8):(1.2-1.6). Setting the molar ratio of the second intermediate, thionyl chloride, and alkaline agent within the above range is beneficial to reducing the occurrence of side reactions. Exceeding or falling below this range may be detrimental to controlling the occurrence of side reactions.

[0075] In an embodiment of the present invention, the molar ratio of the third intermediate, urea, and alkaline agent is 1:(1.2-1.4):(2.8-3.2). Setting the molar ratio of the three intermediates, urea, and alkaline agent within the above range is beneficial to reducing the occurrence of side reactions. Exceeding or falling below this range may be detrimental to controlling the occurrence of side reactions.

[0076] The present invention provides a curing agent, which is prepared by the curing agent preparation method.

[0077] The present invention provides a method for preparing a concrete surface protective agent, using the curing agent described in the above technical solution. The method for preparing the concrete surface protective agent comprises the following steps:

[0078] mixing epoxy resin, diluent and white carbon black to obtain a mixture;

[0079] A curing agent is added to the mixture to obtain a concrete surface protective agent.

[0080] The preparation method of the concrete surface protective agent provided by the present invention adopts a modified curing agent to prepare the concrete surface protective agent. Since the modified curing agent contains abundant amino functional groups and imino functional groups, it can increase the reaction sites with the epoxy resin, which is beneficial to increase the cross-linking density of the resin system after curing, thereby improving the overall physical properties of the concrete surface protective agent. In addition, the used curing agent also introduces a flexible chain segment, which can enhance the toughness of the epoxy resin system after curing, thereby reducing the possibility of cracking of the concrete surface protective agent after being subjected to external force and improving the impact resistance of the concrete surface protective agent. Therefore, the concrete surface protective agent prepared by the technical solution of the present invention has good toughness, impact resistance and mechanical properties, and can be used to solve the problem that existing concrete surface protective agents are prone to failure.

[0081] In an embodiment of the present invention, epoxy resin, diluent and white carbon black are first mixed and stirred for 1 to 2 hours to obtain an emulsion, and then a curing agent is added and stirred for 3 to 5 minutes to obtain the concrete surface protective agent.

[0082] In an embodiment of the present invention, the diluent includes any one of neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether and C12-14 alkyl glycidyl ether. The main function of the diluent is to reduce the viscosity, adjust the physical properties of the cured product, and participate in the cross-linking network, thereby improving the mechanical properties and chemical resistance of the final product. Among them, when using polypropylene glycol diglycidyl ether as a diluent, polypropylene glycol diglycidyl ether with an epoxy value of 0.28 to 0.34, a viscosity of 50 to 100 mPa·s, and a density of 1.13 to 1.15 g / mL can be selected.

[0083] In the embodiment of the present invention, the epoxy resin includes E51 epoxy resin, which belongs to the bisphenol A glycidyl ether epoxy resin and is a widely used bisphenol A type epoxy resin with good comprehensive properties and good processing performance.

[0084] In the embodiment of the present invention, the mass ratio of the epoxy resin, white carbon black and curing agent is 40: (1-10): (12-15). If the proportion of white carbon black is lower than this range, the strength of the concrete surface protective agent system may decrease, and if it is higher than this range, the toughness and impact resistance of the concrete surface protective agent system may decrease; if the amount of curing agent is too large, it will make it difficult to disperse the curing agent evenly when added, resulting in some epoxy resins being unable to cure; if the amount of curing agent is too low, the epoxy resin will not be completely cured due to insufficient curing agent, affecting the overall performance of the final product. Setting the mass ratio of the epoxy resin, white carbon black and curing agent to 40: (1-10): (12-15) results in better overall performance of the final product.

[0085] Adding nanoparticles (such as white carbon black) to epoxy resin can significantly improve the mechanical properties of the resin protective layer. It should be noted that the technical solution of the present invention can use white carbon black, that is, the purchased white carbon black can be directly used to prepare the concrete surface protective agent, or the white carbon black can be modified with a silane coupling agent and then added to the epoxy resin system to prepare the concrete surface protective agent. Preferably, the white carbon black is modified with a silane coupling agent before use. This is because there is a large physical and chemical incompatibility between the nanoparticles and the epoxy resin coating interface. After being subjected to external forces, they are prone to failure at the epoxy resin-nanoparticle interface. In order to overcome the above-mentioned defects, the use of a coupling agent can increase the compatibility between nanoparticles and epoxy resin.

[0086] In an embodiment of the present invention, the white carbon black is prepared by the following preparation method:

[0087] A silane coupling agent, an amino compound and a metal catalyst are mixed to carry out a cross-linking reaction to obtain an amino-modified silane coupling agent;

[0088] Mix the amino-modified silane coupling agent and silica.

[0089] In the technical solution of the present invention, silica is modified with a silane coupling agent and then added to an epoxy system to prepare a concrete surface protective agent. The silane coupling agent is first modified to obtain an amino-modified silane coupling agent. Since the amino-modified silane coupling agent has a polyamino structure, using the amino-modified silane coupling agent instead of a conventional silane coupling agent can further increase the compatibility between silica nanoparticles and epoxy resin.

[0090] In an embodiment of the present invention, the silane coupling agent includes decamethyldihydrogenpentasiloxane. The use of decamethyldihydrogenpentasiloxane facilitates the production of a silane coupling agent containing long-chain alkane groups. By introducing a flexible segment into the silane coupling agent, the toughness of the epoxy resin system can be enhanced during the curing process, suppressing cracks in the protective layer caused by external forces and improving the protective layer's impact resistance in environments such as wind and sand.

[0091] In an embodiment of the present invention, the amino compound includes 1,4-diamino-2,5-divinylbenzene. Polymerization of 1,4-diamino-2,5-divinylbenzene can produce an amino-modified silane coupling agent. Because the amino-modified silane coupling agent has a polyamino structure, it exhibits superior coupling effects on nanoparticles compared to conventional silane coupling agents, enhancing the bonding strength between silica and the resin interface, thereby improving the overall performance of the resulting concrete surface protective agent.

[0092] In an embodiment of the present invention, the metal catalyst includes a platinum catalyst. Platinum catalysts can efficiently catalyze the addition reaction of Si-Vi (silicon-vinyl, i.e., the connection between silicon and a carbon-carbon double bond) and Si-H (silicon-hydrogen), thereby promoting the crosslinking and curing of siloxane materials. They are highly active and efficient and generally do not produce side reactions.

[0093] In an embodiment of the present invention, the molar ratio of the silane coupling agent to the amino compound is 1:(1.0-1.2). When the mass ratio of the silane coupling agent to the amino compound is within the above range, the generation of side reactions can be reduced. Exceeding or falling below this range may be detrimental to controlling the occurrence of side reactions.

[0094] In an embodiment of the present invention, the mass ratio of the silane coupling agent to the metal catalyst is 1000:(0.003-0.005). When the mass ratio of the silane coupling agent to the metal catalyst is within the above range, the catalytic effect of the metal catalyst is better while controlling the production cost.

[0095] In an embodiment of the present invention, the step of mixing a silane coupling agent, an amino compound, and a metal catalyst to perform a cross-linking reaction to obtain an amino-modified silane coupling agent comprises:

[0096] The silane coupling agent, amino compound and dichloromethane are mixed, and then a metal catalyst is added at 0-5°C, and the temperature is raised to 35-40°C for cross-linking reaction, and the amino-modified silane coupling agent is obtained after the reaction for 3-6 hours.

[0097] The metal catalyst is added at 0-5°C to ensure the stability of the metal catalyst.

[0098] In an embodiment of the present invention, the step of mixing the amino-modified silane coupling agent and white carbon black comprises:

[0099] Mixing silica and isopropyl alcohol, and high-speed shearing at 8000-15000 rpm for 10-20 minutes to obtain a silica suspension; mixing an amino-modified silane coupling agent and ethanol to obtain an amino-modified silane coupling agent solution;

[0100] Mix the silica suspension and the silane coupling agent solution and react at 75-85°C for 2-3 hours;

[0101] Wherein, the mass ratio of the white carbon black to isopropyl alcohol is 1:(19-99);

[0102] The ethanol is an ethanol aqueous solution with a volume concentration of 85-95%, and the mass ratio of the amino-modified silane coupling agent to the ethanol is 1:(25-30);

[0103] The mass ratio of the white carbon black suspension to the silane coupling agent solution is 6:(1.1-1.3).

[0104] Setting the mass ratio of the amino-modified silane coupling agent solution to the silica suspension at (1.1-1.3):6 helps improve the compatibility of silica with the epoxy resin system. Using too little modified silane coupling agent solution can lead to poor compatibility between silica and the epoxy resin, reducing the mechanical properties of the finished product. Using too much modified silane coupling agent solution can increase costs and affect the dispersibility of silica during curing.

[0105] The present invention provides a concrete surface protective agent, which is prepared by the concrete surface protective agent preparation method.

[0106] The present invention provides a concrete comprising the concrete surface protective agent. The concrete comprises all technical solutions of the concrete surface protective agent and thus possesses all the beneficial effects of the concrete surface protective agent, which will not be described in detail herein.

[0107] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0108] Example 1

[0109] A method for preparing a concrete surface protective agent comprises the following steps:

[0110] 1) Preparation of curing agent:

[0111] A1. Under nitrogen protection, 4-(chloromethyl)benzyl alcohol was dissolved in N,N-dimethylformamide, the temperature was controlled at 0°C, diethylenetriamine and triethylamine were added and stirred to obtain a mixed solution, the mixed solution was stirred for 13 hours at room temperature, and the product was subjected to reduced pressure distillation to obtain a first intermediate. The reaction process is as follows: Figure 1 As shown; wherein the molar ratio of 4-(chloromethyl)benzyl alcohol, diethylenetriamine and triethylamine is 1:1:0.5;

[0112] A2. The first intermediate, cyanuric chloride and diethylamine were added to toluene and stirred evenly. The reaction was continued at 25° C. for 24 h under nitrogen protection. The product was rotary evaporated to obtain the second intermediate. The reaction process is as follows: Figure 1 As shown; wherein the molar ratio of the first intermediate, cyanuric chloride and diethylamine is 3:1:1.5;

[0113] A3. The second intermediate, thionyl chloride and pyridine were added to toluene in sequence and stirred evenly. The system was heated to 43°C under nitrogen protection and reacted at this temperature for 5 hours. The product was rotary evaporated to obtain the third intermediate. The reaction process is as follows: Figure 1 As shown; wherein the molar ratio of the second intermediate, thionyl chloride and pyridine is 1:1.7:1.4;

[0114] A4. Under nitrogen protection, the third intermediate was added to N,N-dimethylformamide and mixed evenly. Then, triethylamine and urea were added to the system and mixed evenly. The system was heated to 47°C and reacted for 13 hours. The product was distilled under reduced pressure and then vacuum dried to constant weight to obtain a curing agent. The reaction process is as follows: Figure 1 As shown; wherein, the molar ratio of the third intermediate, triethylamine, and urea is 1:1.3:3.0.

[0115] 2) Preparation of amino-modified silane coupling agent:

[0116] B1. Under nitrogen protection, decamethyldihydrogen pentasiloxane and 1,4-diamino-2,5-divinylbenzene were added to dichloromethane and mixed evenly; the system temperature was controlled to 2°C, and Karstedt platinum catalyst was added. The reaction was stirred at 35°C for 4 hours. The obtained product was rotary evaporated and vacuum dried to obtain an amino-modified silane coupling agent. The reaction process is as follows: Figure 2 As shown; wherein, the molar ratio of decamethyldihydrogen pentasiloxane to 1,4-diamino-2,5-divinylbenzene is 1:1; the amount of Custer platinum catalyst is calculated according to the actual mass of decamethyldihydrogen pentasiloxane participating in the reaction, and 5 μg of Custer platinum catalyst is added per gram.

[0117] 3) Preparation of white carbon black:

[0118] C1. Unmodified silica (Wanhua Tianhe TH-620, particle size 300-400 mesh) and isopropyl alcohol were added to a container and high-speed sheared at 15,000 rpm for 20 minutes to obtain a silica suspension; 1 part of an amino-modified silane coupling agent was mixed with 27 parts of a 90% ethanol aqueous solution, and the mixture was stirred and mixed to obtain an amino-modified silane coupling agent solution;

[0119] C2. Add the amino-modified silane coupling agent solution to the silica suspension, stir and react at a constant temperature of 80° C. for 2.5 hours, filter the reaction product and dry it to constant weight to obtain silica; wherein the mass ratio of silica suspension to amino-modified silane coupling agent solution is 6:1.2.

[0120] 4) Preparation of concrete surface protective agent:

[0121] D1, E51 epoxy resin, neopentyl glycol diglycidyl ether, and the white carbon black prepared in step 3) were stirred for 1.5 hours to obtain a uniform emulsion;

[0122] D2. Add a curing agent to the emulsion of step D1 and stir for 3 minutes to obtain a concrete surface protective agent; wherein the amount of E51 epoxy resin, white carbon black, curing agent and diluent is 40:5:14:41.

[0123] Example 2

[0124] Compared with Example 1, the difference is that the molar ratio of the first intermediate, cyanuric chloride and diethylamine in Step A2 is 3:0.7:1.2.

[0125] Example 3

[0126] Compared with Example 1, the difference is that the molar ratio of the third intermediate, triethylamine and urea in Step A4 is 1:1.4:3.

[0127] Example 4

[0128] Compared with Example 1, the difference is that in step B1, the molar ratio of decamethyldihydrogenpentasiloxane to 1,4-diamino-2,5-divinylbenzene is 1:1.2.

[0129] Example 5

[0130] Compared with Example 1, the difference is that in step C2, the mass ratio of the white carbon black suspension to the amino-modified silane coupling agent solution is 6:1.3.

[0131] Comparative Example 1

[0132] Compared with Example 1, the difference is that 13 parts of diethylenetriamine and 1 part of 2,4,6-tris(dimethylaminomethyl)phenol are used instead of the curing agent.

[0133] Comparative Example 2

[0134] Compared with Example 1, the difference is that KH-450 is used instead of the amino-modified silane coupling agent.

[0135] Performance Testing

[0136] The concrete surface protective agents prepared in Examples 1-5 and Comparative Examples 1-2 were tested for compressive strength, tensile strength, elongation at break, impact strength and bond tensile strength according to GB / T2567-2021 "Test Method for Performance of Resin Castings" and DL / T 5193-2004 "Technical Specification for Epoxy Resin Mortar". The test results are shown in Table 1.

[0137] Table 1 Test results of Examples 1-5 and Comparative Examples 1-2

[0138]

[0139]

[0140] As can be seen from Table 1, the concrete surface protective agents of Examples 1-5 have excellent comprehensive performance, and the physical properties of the concrete surface protective agents prepared in Examples 1-5 are better than those of Comparative Example 1 and Comparative Example 2, indicating that the scheme of the present invention can improve the comprehensive performance of the concrete surface protective agent.

[0141] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for preparing a curing agent, characterized in that: The following steps are involved: A polyamine compound, a halogenated methylbenzyl alcohol, an alkaline reagent and an organic solvent are mixed to perform a first substitution reaction to obtain a first intermediate; wherein the polyamine compound is diethylenetriamine, the alkaline reagent is triethylamine, and the structural formula of the first intermediate is shown in Formula (I); The first intermediate, cyanuric chloride, an alkaline reagent and an organic solvent are mixed to perform a second substitution reaction to obtain a second intermediate; wherein the alkaline reagent is diethylamine, and the structural formula of the second intermediate is shown in formula (II); The second intermediate, thionyl chloride, an alkaline reagent and an organic solvent are mixed and subjected to a chlorination reaction to obtain a third intermediate; wherein the alkaline reagent is pyridine, and the structural formula of the third intermediate is shown in formula (III); The third intermediate, urea, an alkaline reagent and an organic solvent are mixed to carry out a third substitution reaction to obtain a curing agent; wherein the alkaline reagent is triethylamine, and the structural formula of the curing agent is shown in Formula (IV); 2. The method for preparing a curing agent according to claim 1, wherein The halomethylbenzyl alcohol is selected from any one of 4-(chloromethyl)benzyl alcohol, 4-(bromomethyl)benzyl alcohol and 4-(iodomethyl)benzyl alcohol; and / or, The organic solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide and toluene; and / or, The temperature of the first substitution reaction is 0-5°C; the time is 10-15h; and / or, The temperature of the second substitution reaction is 20 to 30° C. and the time is 22 to 26 hours; and / or, The chlorination reaction temperature is 40-45°C; the time is 4-6 hours; and / or, The temperature of the third substitution reaction is 45-50° C. and the time is 10-15 hours; and / or, The molar ratio of the polyamine compound, the halogenated methylbenzyl alcohol and the alkaline agent is (0.9-1.1):1:(0.4-0.6); and / or, The molar ratio of the first intermediate, cyanuric chloride and alkaline reagent is 3: (0.7-1.2): (1.2-1.7); and / or, The molar ratio of the second intermediate, thionyl chloride and alkaline reagent is 1: (1.6-1.8): (1.2-1.6); and / or, The molar ratio of the third intermediate, urea and alkaline reagent is 1: (1.2-1.4): (2.8-3.2).

3. A curing agent, characterized in that The curing agent is prepared by the preparation method of the curing agent according to claim 1 or 2, and the structural formula of the curing agent is shown in formula (IV); 4. A method for preparing a concrete surface protective agent, characterized in that: The method for preparing the concrete surface protective agent using the curing agent according to claim 3 comprises the following steps: mixing an epoxy resin, a diluent, and modified silica to obtain a mixture; adding a curing agent to the mixture to obtain a concrete surface protective agent; Wherein, the modified silica is prepared by the following preparation method: A silane coupling agent, an amino compound and a metal catalyst are mixed to carry out a cross-linking reaction to obtain an amino-modified silane coupling agent; The amino-modified silane coupling agent and unmodified silica are mixed.

5. The method for preparing the concrete surface protective agent according to claim 4, wherein: The diluent is selected from any one of neopentyl glycol diglycidyl ether, polypropylene glycol diglycidyl ether and C12-14 alkyl glycidyl ether; and / or, The epoxy resin is E51 epoxy resin; and / or, The mass ratio of the epoxy resin, white carbon black and curing agent is 40:(1-10):(12-15).

6. The method for preparing the concrete surface protective agent according to claim 4, wherein: The silane coupling agent is decamethyldihydrogenpentasiloxane; and / or, The amino compound is 1,4-diamino-2,5-divinylbenzene; and / or, The metal catalyst is a platinum catalyst; and / or, The molar ratio of the silane coupling agent to the amino compound is 1:(1.0-1.2); and / or, The mass ratio of the silane coupling agent to the metal catalyst is 1000:(0.003-0.005).

7. The method for preparing the concrete surface protective agent according to claim 4, wherein: The step of mixing the amino-modified silane coupling agent and unmodified white carbon black comprises: Mixing unmodified silica and isopropyl alcohol to obtain a silica suspension; mixing an amino-modified silane coupling agent and ethanol to obtain an amino-modified silane coupling agent solution; The silica suspension and the amino-modified silane coupling agent solution are mixed.

8. A concrete surface protective agent, characterized in that: The concrete surface protective agent is prepared by the preparation method of the concrete surface protective agent according to any one of claims 4 to 7.

9. A concrete, characterized in that: The concrete includes the concrete surface protective agent according to claim 8.

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