CN116731396B - Preparation method and application of high-performance asphalt odor-removal flame-retardant synergist - Google Patents

Abstract

The invention discloses a preparation method and application of an asphalt odor-removing flame-retardant synergist, and belongs to the technical field of materials. And (3) sequentially coating zinc stannate and high-carbon alcohol on the surface of the calcium carbonate to obtain the high-carbon alcohol coupled zinc stannate coated calcium carbonate, namely the asphalt odor-removing flame-retardant synergist. The asphalt odor-removing flame-retardant synergist can be effectively compatible with asphalt, so that the asphalt odor-removing flame-retardant performance is improved, and the rheological property of asphalt is improved to a certain extent. The odor-removing flame-retardant synergist can adsorb smoke of asphalt in the paving process, can play a certain flame-retardant effect, and greatly reduces harm of harmful components in the smoke of the asphalt to constructors and environment. The invention achieves the purpose of reducing the smell of the asphalt in a high-temperature state through a simpler preparation process and low cost, and provides a new method for developing and applying the odor-free environment-friendly asphalt.

Description

Preparation method and application of a high-performance asphalt odor-free flame retardant synergist

Technical field

The invention relates to the field of material technology, and in particular to a preparation method and application of a high-performance asphalt odor-free flame retardant synergist.

Background technique

Asphalt is mainly composed of hydrocarbons and their non-metallic derivatives. It is a thick, semi-solid and complex mixture. It is widely used in waterproofing, coatings, plastics, etc. due to its excellent properties such as viscosity, ductility, and temperature deformation. Rubber, roads, etc. Due to the high melting point of asphalt, it must be heated first during use, and the composition of asphalt is very complex. During the heating process, not only will asphalt smoke be produced, but a large amount of energy will also be consumed, and a large amount of carbon dioxide and nitrogen oxides will be produced. , sulfur oxides and other pollutants are important sources of air pollution.

Asphalt flue gas mainly comes from asphalt, petroleum, coal, etc. It is a smog-like substance that diffuses into the air during the high-temperature production process of these raw materials. When these raw materials are exposed to high temperatures, due to insufficient oxygen supply, they cannot be deeply oxidized and produce asphalt fumes. The composition of asphalt is complex, and the composition of asphalt produced under different regions, manufacturers, and production process conditions varies greatly. However, the composition of asphalt smoke is basically close to that of asphalt. It usually exists in the form of aerosol, and its particle size is mostly in the Between 0.1 and 1.0μm, it is more harmful to environmental pollution.

At present, road traffic construction is developing rapidly, and asphalt is often used to pave roads. Using asphalt mixture to pave the road can not only reduce road noise, but also improve the driving comfort of the road. However, when constructing in some closed and long tunnels or in hot weather, asphalt smoke seriously threatens the physical and mental health of construction workers. At the same time, asphalt is a universal building material, and the environmental pollution caused by its widespread use has become an unavoidable environmental problem. Therefore, studying the composition of asphalt smoke and suppressing the generation of asphalt smoke can reduce the harm to construction workers and reduce the environmental pollution caused by asphalt smoke.

Contents of the invention

The purpose of the present invention is to provide a preparation method and application of a high-performance asphalt odor-free flame retardant synergist to reduce smoke hazards during asphalt construction. The present invention develops a zinc stannate-coated calcium carbonate based on high-carbon alcohol coupling as a high-performance asphalt odor-cleaning flame retardant synergist. The calcium carbonate is coated with tin stannate to make it have flame retardant properties, and then One end of the silane coupling agent molecule reacts with the hydroxyl group on the surface of calcium carbonate to form a hydrogen bond, and is condensed, dehydrated and solidified under certain conditions to form a covalent bond; the other end is combined with a high-carbon alcohol, thereby making the polymer material (High carbon alcohol) - silane coupling agent - inorganic material (zinc stannate coated calcium carbonate) produces a good interface bond, forming a porous and high specific surface structure on the surface of calcium carbonate. This material uses zinc stannate partially coated on the surface of calcium carbonate to improve the flame retardant properties of asphalt. The porous and high specific surface structure of the surface absorbs the small molecule smoke substances released by asphalt at high temperatures. At the same time, the silane coupling agent The compatibility of this material with asphalt is enhanced. Therefore, this material is used in asphalt construction as an odor-free flame retardant synergist for asphalt. It can improve the high temperature performance and flame retardant performance of asphalt and reduce the emission of asphalt smoke and odorous gases. .

To achieve the above object, the present invention provides the following solutions:

One of the technical solutions of the present invention: a method for preparing an asphalt odor-free flame retardant synergist, which includes sequentially coating zinc stannate and higher alcohol on the surface of calcium carbonate to obtain a high alcohol-coupled zinc stannate coating. Coated with calcium carbonate, it is the asphalt odor-free flame retardant synergist.

Further, the method of coating zinc stannate on the surface of calcium carbonate also includes:

Add calcium carbonate powder and urea (CO(NH) ₂ ) to water, heat, stir, and disperse to obtain a pretreated calcium carbonate aqueous dispersion;

Mix zinc stannate, zinc oxide and an alkali metal compound with water, heat and stir, then add the pre-treated calcium carbonate aqueous dispersion, continue heating and stirring the reaction, after the reaction is completed, the obtained emulsion is filtered, dried and calcined to obtain stannic acid Zinc coated calcium carbonate powder.

Further, the method of coating higher carbon alcohol on the surface of calcium carbonate also includes:

Dissolve the zinc stannate-coated calcium carbonate powder in the ester compound solution, then add a silane coupling agent, heat and stir, then add high-carbon alcohol powder, continue to heat and stir the reaction, filter, dry and grind after the reaction is completed. The high-carbon alcohol-coupled zinc stannate-coated calcium carbonate is obtained, which is the asphalt odor-cleaning flame retardant synergist.

Further, the method of adding calcium carbonate powder and urea to water, heating, stirring, and dispersing to obtain a pretreated calcium carbonate aqueous dispersion also includes:

The particle size of the calcium carbonate powder is 200-400 mesh; the mass ratio of the calcium carbonate powder to urea is (3.5-5):1, and the dosage ratio of calcium carbonate powder to water is (1-1.5)g:10ml ; The heating and stirring temperature is 35-65°C, and the stirring time is 40-80min.

The dispersion is ultrasonic dispersion, and the time is 50-100 minutes.

Furthermore, the method of mixing zinc stannate, zinc oxide and an alkali metal compound with water, heating and stirring, then adding the pretreated calcium carbonate aqueous dispersion, continuing heating and stirring to react, filtering, drying and calcining the obtained emulsion after the reaction is completed, and obtaining the zinc stannate coated calcium carbonate powder also includes:

The zinc stannate is zinc hydroxystannate (Na ₂ Sn(OH) ₆ ), and the alkali metal oxide is preferably sodium hydroxide (NaOH).

The dosage ratio of the zinc stannate to water is (1-2)g:7-10ml.

The mass ratio of zinc stannate: zinc oxide: alkali metal compound: calcium carbonate powder is (1.0-2.0): (0.3-0.8): (1.0-2.2): 10; the calcination temperature is 500-700° C., and the calcination time is 0.8-2.2 h.

The heating and stirring temperature before and after the addition of the pretreated calcium carbonate aqueous dispersion is 50-90°C, the rotation speed is 300-550 rpm, and the total stirring time is 5-12 hours.

Further, the zinc stannate-coated calcium carbonate powder is dissolved in the ester compound solution, then a silane coupling agent is added, heated and stirred, then high-carbon alcohol powder is added, the heating and stirring reaction is continued, and after the reaction is completed, it is filtered and dried. , grinding to obtain high-carbon alcohol-coupled zinc stannate-coated calcium carbonate, which is the asphalt odor-cleaning flame retardant synergist. The method also includes:

The ester compound solution is ethyl acetate or isoamyl acetate.

The heating and stirring temperature before and after adding the high-carbon alcohol powder is 40-85°C, the rotation speed is 300-350 rpm, and the total stirring time is 6-10 hours.

The drying temperature is 45-75°C.

The grinding is to grind the solid product to a particle size of 200-400 mesh.

Further, the number of carbon atoms of the higher carbon alcohol is 16-18.

Further, the mass ratio of the calcium carbonate powder to the silane coupling agent is 20: (0.15-0.22); the mass ratio of the calcium carbonate powder to the higher alcohol is 25: (0.1-0.3).

The principle of generating zinc stannate-coated calcium carbonate powder is to react with zinc hydroxystannate under alkaline conditions (the alkaline conditions are provided by alkali metal oxides and urea) to generate zinc stannate particles with stable crystal form and uniformly precipitate in carbonic acid. The calcium surface is then calcined to remove impurities and make the coated calcium carbonate powder more stable.

Urea plays a very important role in controlling the reaction. It can slowly release hydroxyl hydrogen ions, thereby accurately controlling the reaction speed and making the resulting product particles uniform in size and regular in shape. This is because urea will hydrolyze during the heating process to generate ammonia and diamine carbonate, and then release hydroxyl ions. This process is relatively slow and can be used as a buffer for the reaction.

In addition, urea can provide an alkaline environment suitable for the formation of zinc stannate crystals. When urea reacts with ions in the solution, the corresponding stannate and zincate can be formed. The concentration of these two substances in the solution will gradually increase until it exceeds saturation, thus forming zinc stannate crystals. This method can produce zinc stannate with excellent crystal properties.

In addition, the present invention controls the coating area of zinc stannate on the surface of calcium carbonate by controlling the dosage ratio of calcium carbonate powder and zinc hydroxystannate, so as to achieve partial coating of zinc stannate on the surface of calcium carbonate. In addition, the coating area of high-carbon alcohol is controlled by controlling the dosage ratio of calcium carbonate powder, zinc hydroxystannate, and high-carbon alcohol powder, and because the silane coupling agent is a substance that can connect the surfaces of different materials, it It has a wide range of grafting properties, so the silane coupling agent can be coated on the surface of calcium carbonate coated with zinc stannate, or directly coated on the surface of calcium carbonate that has not been coated with zinc stannate.

The second technical solution of the present invention: an asphalt odor-free flame retardant synergist prepared according to the above preparation method.

Furthermore, the surface of the high carbon alcohol coupled zinc stannate coated calcium carbonate has a porous structure with a high specific surface area, and the porosity of the high carbon alcohol coupled zinc stannate coated calcium carbonate can reach 19.87%, and the specific surface area can reach 42.1332 m ² /g.

The third technical solution of the present invention: a method for preparing modified asphalt. The above-mentioned asphalt odor-free flame retardant synergist and modifier are added to the asphalt, and the mixture is sheared and dispersed evenly to obtain the modified asphalt.

Further, the blending amount of the asphalt clean smell flame retardant synergist is 3.0-15.0‰ of the total mass of asphalt.

Further, the modifier is SBS (styrene-butadiene-styrene block copolymer).

Furthermore, the amount of the modifier added is 5% of the total mass of the asphalt.

Furthermore, before adding the asphalt odor-free flame retardant synergist and modifier, the asphalt was dried at 135°C for 2 hours.

Further, the specific operation of the shearing and dispersing is: maintaining a constant temperature of 175°C, first shearing and dispersing at a rotation speed of 5000rpm for 1-2h, and then shearing and dispersing at a rotational speed of 350-750rpm for 1-2h.

The fourth technical solution of the present invention: a modified asphalt prepared according to the above preparation method.

Reaction principle of the present invention:

Based on high-carbon alcohol-coupled zinc stannate-coated calcium carbonate, ZnS is generated by reacting Zn ²⁺ in zinc stannate with H ₂ S gas released from asphalt. ZnS can capture the highly active OH ^- and H ⁺ radicals in the gas phase of asphalt flue gas, interfere with the chain reaction that interrupts combustion, and promote the formation of a dense and strong carbonized layer on the asphalt surface in the solid phase. At the same time, at high temperatures, ZnS forms a glass-like coating on the surface of combustible asphalt, which can not only play a role in heat insulation, but also isolate oxygen in the air. In addition, the SnO ₃ ^2- ions in zinc stannate can react with H ₂ S to form stannate H ₂ SnO ₃ and H ₂ O. H ₂ O can absorb heat at high temperatures and dilute the oxygen concentration. H ₂ SnO ₃ can form a coating on the surface of asphalt and can react with H ₂ S to generate SnS ₂ . ZnS and SnS ₂ are both Lewis acids. They can catalyze the dehydrogenation of long-chain alkane substances in asphalt to generate trans polyene structures. This reaction The formula structure cannot be cyclized to generate benzene, thus greatly reducing the generation of aromatic compounds and reducing the amount of smoke produced by asphalt at high temperatures; at the same time, ZnS and SnS ₂ can further promote cross-linking and carbonization reactions between molecules, It increases the amount of carbon formed in asphalt at high temperatures, thereby reducing the amount of smoke formed and preventing combustion from continuing. The H ₂ S in the flue gas is consumed, so the pungent odor in the asphalt flue gas is also greatly reduced.

The surface of calcium carbonate coated with zinc stannate has a needle-like or flaky structure, which greatly increases the surface area and porosity of calcium carbonate. These voids have a good interception effect on macromolecular particles in asphalt flue gas. At the same time, the high specific surface area also enhances the contact area between calcium carbonate and asphalt, enhancing the compatibility. However, as an inorganic powder, calcium carbonate still has poor compatibility with asphalt due to its strong polarity. Therefore, the present invention continues surface modification by coating calcium carbonate with zinc stannate. As a common surface modifier, silane coupling agent is mainly used to modify the surface of inorganic fillers in polymer composite materials. In the present invention, one end of the silane coupling agent molecule reacts with the hydroxyl group on the surface of calcium carbonate. Form hydrogen bonds, and condense, dehydrate and solidify under certain conditions to form covalent bonds; the other end is combined with higher-carbon alcohols, thereby making the polymer material (higher-carbon alcohol) - silane coupling agent - inorganic material (tin Zinc acid coated calcium carbonate) produces a good interfacial bonding. At the same time, the main odorous substance in asphalt flue gas is sulfide, and the outermost electron layer of the sulfur atom has an empty orbit and can receive external electrons. It is a Lewis acid, and high-carbon alcohol is a Lewis base. It can undergo Lewis acid-base reaction with S-containing substances, thereby reducing the odor of asphalt smoke.

This invention uses zinc stannate partially coated on the surface of calcium carbonate to improve the flame retardant properties of asphalt. The porous and high specific surface structure formed by coating zinc stannate and higher carbon alcohol absorbs the small molecule smoke released by asphalt at high temperatures. At the same time, the silane coupling agent enhances the compatibility of this material with asphalt. Therefore, this material is used in asphalt construction as an odor-free flame retardant synergist for asphalt, which can improve the high temperature performance and flame retardant performance of asphalt and reduce the asphalt The role of smoke and odorous gas emissions.

The invention discloses the following technical effects:

(1) The present invention uses inexpensive calcium carbonate as a matrix and partially coats zinc stannate particles to improve the flame retardant properties of modified asphalt, while greatly reducing the amount of zinc stannate used, and the cost of use is greatly reduced. At the same time, zinc stannate can react with asphalt smoke to block the combustion process and form a dense carbonized layer. The stannous sulfide and zinc sulfide generated after the zinc stannate reaction can reduce the generation of aromatic compounds in asphalt smoke, increase the carbon content, and reduce the smoke generation. After the zinc stannate is coated on the surface of calcium carbonate, the present invention continues to coat high carbon alcohols. As a Lewis base, high carbon alcohols can react with sulfur-containing substances to produce Lewis acid-base reactions, thereby reducing the odor of asphalt smoke.

(2) Since the surface of the asphalt odor-free flame retardant synergist of the present invention is covered with zinc stannate and high carbon alcohol substances with partial flaky or needle-like structures, its surface has a higher specific surface area and porosity than the unmodified calcium carbonate powder. These voids can better adsorb large particle molecules in asphalt smoke. At the same time, the addition of silane coupling agent helps the modified calcium carbonate powder to be better and more evenly dispersed in the asphalt, which greatly improves the low compatibility problem between the highly polar inorganic calcium carbonate powder and asphalt. At the same time, the good dispersibility enables the modified calcium carbonate powder to provide more three-dimensional mechanical support in the asphalt, thereby enhancing the rheological properties of the asphalt. The zinc stannate and high carbon alcohols with flame retardant and smoke suppression synergistic effects can improve the high temperature performance of the asphalt.

(3) The asphalt odor-cleaning flame retardant synergist of the present invention can be effectively compatible with asphalt, which not only improves the odor-cleaning flame retardant performance of asphalt, but also improves the rheological properties of asphalt to a certain extent. The asphalt odor-free flame retardant synergist of the present invention absorbs the smoke from asphalt during the paving process through its flame retardant and porous chemical and structural characteristics. At the same time, it can have a certain flame retardant effect and greatly reduce the asphalt smoke. Harmful components in the air harm construction workers and the environment. At the same time, the odor-free flame retardant synergist also improves the rheological properties and flame retardant properties of the asphalt itself to a certain extent. Through a relatively simple preparation process and low cost, it can achieve the purpose of reducing the odor of asphalt at high temperatures, providing a way to clean the odor. The development and application of environmentally friendly asphalt provides a new method.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the drawings of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without exerting creative efforts.

Figure 1 is an SEM image of the raw calcium carbonate powder and the high-carbon alcohol-coupled zinc stannate-coated calcium carbonate prepared in Example 2, where a is the raw calcium carbonate powder, and b is the high-carbon alcohol-coupled stannic acid. zinc coated calcium carbonate;

FIG2 is a comparison diagram of the complex shear modulus G*(10Hz) of the modified asphalt prepared in Application Examples 1-3 of the present invention and Comparative Application Examples 1-2 as a function of temperature;

Figure 3 is a comparison chart of the storage modulus G' (10Hz) of the modified asphalt prepared in Application Examples 1-3 of the present invention and Comparative Application Examples 1-2 as a function of temperature;

Figure 4 is a comparison chart of the change in loss modulus G” (10Hz) with temperature of the modified asphalt prepared in Application Examples 1-3 of the present invention and Comparative Application Examples 1-2;

Figure 5 is a GC-MS total gas chromatogram of the modified asphalt prepared in Application Example 2 and Comparative Application Example 2 of the present invention.

Detailed ways

Various exemplary embodiments of the invention will now be described in detail. This detailed description should not be construed as limitations of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention.

It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which the documents relate. In the event of conflict with any incorporated document, the contents of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and changes can be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to the skilled person from the description of the invention. The specification and examples are intended to be illustrative only.

The words "includes", "includes", "has", "contains", etc. used in this article are all open terms, which mean including but not limited to.

The particle size range of the calcium carbonate powder used in the following examples and comparative examples is 200-400 mesh, and the carbon atom number of the high carbon alcohol used is 18.

Example 1

(1) Weigh 50 g of calcium carbonate powder sieved to 200-400 mesh and add it to 500 ml of aqueous solution, add 10 g of urea, stir for 1 h at a constant temperature of 50° C. and a rotation speed of 350 rpm, and then ultrasonicate for 1 h to obtain a pretreated calcium carbonate aqueous dispersion for use;

(2) Weigh 5.578 g of zinc hydroxystannate (Na ₂ Sn(OH) ₆ ), 1.75 g of zinc oxide (ZnO), and 5.749 g of an alkali metal compound (NaOH), add them to 350 ml of an aqueous solution, heat and stir at 60° C. for 1 h at a speed of 350 rpm, then add the pretreated calcium carbonate aqueous dispersion in step (1), stir and react at 85° C. for 6 h at a speed of 450 rpm; after the reaction, cool the obtained emulsion to room temperature, filter, rinse with deionized water for 3 times, dry in an oven at 60° C. for 4 h, and then calcine in a muffle furnace at 500° C. for 1 h to obtain calcium carbonate powder coated with zinc stannate;

(3) The zinc stannate-coated calcium carbonate powder obtained in step (2) is dissolved in an ester compound solution (ethyl acetate), and 0.375 g of a silane coupling agent (KH-550) is added. The mixture is stirred at 350 rpm for 30 min at 50°C, and then 0.2 g of a high-carbon alcohol is added. The mixture is stirred at 350 rpm for 6 h. The mixture is filtered, rinsed three times with ethanol and water, and dried in an oven at 60°C for 4 h. The mixture is ground to a particle size of 200-400 mesh to obtain an asphalt odorless flame retardant synergist (high-carbon alcohol-coupled zinc stannate-coated calcium carbonate, NFRC).

Example 2

(1) Weigh 50 g of calcium carbonate powder sieved to 200-400 mesh and add it to 500 ml of aqueous solution, add 12.5 g of urea, stir for 1 h at a constant temperature of 50° C. and a rotation speed of 350 rpm, and then ultrasonicate for 1 h to obtain a pretreated calcium carbonate aqueous dispersion for use;

(2) Weigh 5.314g of zinc hydroxystannate (Na ₂ Sn(OH) ₆ ), 1.55g of zinc oxide (ZnO), and 5.536g of alkali metal compound (NaOH), add them to 350 ml of aqueous solution, and heat and stir at a constant temperature of 60°C 1h, the rotation speed is 350rpm, then add the pretreated calcium carbonate aqueous dispersion in step (1), stir at a constant temperature of 85°C for 6h, the rotation speed is 450rpm; after the reaction is completed, the obtained emulsion is cooled to room temperature, filtered, and deionized using After being repeatedly rinsed with water three times, dried in an oven at 60°C for 4 hours, and then calcined in a muffle furnace at 500°C for 1 hour, zinc stannate-coated calcium carbonate powder was obtained;

(3) The zinc stannate-coated calcium carbonate powder obtained in step (2) is dissolved in an ester compound solution (ethyl acetate), and 0.5 g of a silane coupling agent (KH-550) is added. After stirring at 350 rpm for 30 min at 50°C, 0.4 g of a high-carbon alcohol is added, and stirring is continued at 350 rpm for 7.5 h. The mixture is filtered, rinsed three times with ethanol and water, and dried in an oven at 65°C for 4 h. The mixture is ground to a particle size of 200-400 mesh to obtain an asphalt odorless flame retardant synergist (NFRC).

Example 3

(1) Weigh 75g of calcium carbonate powder sieved to 200-400 mesh into 500ml of aqueous solution, add 21.43g of urea, stir for 1 hour at a constant temperature of 50°C, with a rotation speed of 400 rpm, and then ultrasonic for 1 hour to obtain pretreated calcium carbonate water The dispersion is ready for use;

(2) Weigh 9 g of zinc hydroxystannate ( _Na2Sn (OH)6), 3.75 g of zinc oxide (ZnO), and 10.5 g of (NaOH), add them to 500 ml of aqueous solution, heat and stir at 60°C for 1 h, and rotate at 450 rpm, then add the pretreated calcium carbonate aqueous dispersion in step (1), and stir at 85°C for 6 h, and rotate at 450 rpm; after the reaction is completed, cool the obtained emulsion to room temperature, filter, rinse with deionized water for 3 times, dry in an oven at 60°C for 4 h, and then calcine in a muffle furnace at 500°C for 1 h to obtain calcium carbonate powder coated with zinc stannate;

(3) The zinc stannate-coated calcium carbonate powder obtained in step (2) is dissolved in an ester compound solution (ethyl acetate), and 0.55 g of a silane coupling agent (KH-550) is added. After stirring at 450 rpm for 30 min at 50 ° C, 0.6 g of a high-carbon alcohol is added, and stirring is continued at 450 rpm for 8 h. The mixture is filtered, rinsed repeatedly with ethanol and water for 3 times, and then placed in an oven at 75 ° C for 4 h. The mixture is ground to a particle size of 200-400 mesh to obtain an asphalt odorless flame retardant synergist (NFRC).

Application example 1

Weigh 200g of SK-70A asphalt and dry it in a 135°C oven for 2 hours to remove excess moisture. Add the NFRC and SBS obtained in Example 1 to the asphalt, maintain a constant temperature of 150°C, and shear it with a 5000rpm high-speed shearing machine. 1h, and dispersed under a 400rpm high-speed shear for 1h to obtain NFRC/SBS composite modified asphalt; the NFRC blending amount is 3‰ of the total mass of asphalt (the mass of asphalt before water removal), and the SBS blending amount is 3% of the asphalt. 5% of total mass.

Application example 2

Weigh 200g of SK-70A asphalt and dry it in a 135°C oven for 2 hours to remove excess moisture. Add the NFRC and SBS obtained in Example 2 to the asphalt, maintain a constant temperature of 165°C, and shear it with a 5000rpm high-speed shearer. 1.5h, and dispersed under a 450rpm high-speed shear for 1.5h to obtain NFRC/SBS composite modified asphalt; the NFRC blending amount is 5‰ of the total mass of asphalt (the mass of asphalt before water removal), and the SBS blending amount is It is 5% of the total mass of asphalt.

Application example 3

Weigh 200g of SK-70A asphalt and dry it in a 135°C oven for 2 hours to remove excess moisture. Add the NFRC and SBS obtained in Example 3 to the asphalt, maintain a constant temperature of 175°C, and shear it with a 5000rpm high-speed shearer. 2h, and dispersed for 2h under a 500rpm high-speed shear to obtain NFRC/SBS composite modified asphalt; the NFRC blending amount is 9‰ of the total mass of asphalt (the mass of asphalt before water removal), and the SBS blending amount is 5% of total mass.

Comparative application example 1

Same as Application Example 2, the only difference is that the use of NFRC is omitted and only SBS is added as a modifier to prepare SBS modified asphalt.

Comparative application example 2

Weigh 200g of SK-70A asphalt, dry it in a 135°C oven for 2 hours to remove excess moisture, and grind the intermediate product zinc stannate-coated calcium carbonate powder obtained in Example 2 (grinded to a particle size of 200-400 mesh) Add SBS to the asphalt, maintain a constant temperature of 165°C, shear it with a 5000rpm high-speed shear for 1.5h, and disperse it with a 450rpm high-speed shearer for 1.5h to obtain the NFRC/SBS composite modified asphalt; NFRC blending amount is 5‰ of the total asphalt mass, and the SBS blending amount is 5% of the total asphalt mass.

Effect verification

1. Morphology and structure

Take the raw material calcium carbonate powder in Example 2, the intermediate product zinc stannate-coated calcium carbonate powder, and the final product high-carbon alcohol-coupled zinc stannate-coated calcium carbonate to test the porosity and specific surface area (the raw material calcium carbonate powder Grind the intermediate product zinc stannate-coated calcium carbonate powder until the particle size is consistent with the final product high-carbon alcohol-coupled zinc stannate-coated calcium carbonate), and the results are shown in Table 1:

Table 1

As can be seen from Table 1, coating zinc stannate on the surface of calcium carbonate can significantly increase the specific surface area and porosity of calcium carbonate. After coating zinc stannate, continuing to coat high-carbon alcohol can further increase its specific surface area and porosity.

In addition, a scanning electron microscope was used to characterize the morphology of the raw calcium carbonate powder and the final product high-carbon alcohol-coupled zinc stannate-coated calcium carbonate. The SEM images of the two are shown in Figure 1, where a is the raw calcium carbonate powder. , b is high-carbon alcohol-coupled zinc stannate-coated calcium carbonate; as can be seen from Figure 1, the unmodified calcium carbonate powder exhibits a regular cubic morphology (calcite crystal form), while the high-carbon alcohol-coupled calcium carbonate powder has a regular cubic morphology (calcite crystal form). The surface of zinc stannate-coated calcium carbonate is wrapped by needle-shaped zinc stannate particles and small spherical high-carbon alcohols, and the wrapping is relatively uniform.

2. Dynamic shear rheology test (DSR)

The modified asphalt prepared in Application Examples 1-3 and Comparative Application Examples 1-2 was subjected to DSR testing. The specific method was: pour 1.0g of asphalt in the center of a test plate with a diameter of 25mm, move the test plate and squeeze the two test plates. Asphalt in between, heat the specimen dresser to correct the excess asphalt around it, and then adjust the gap to the test gap of 1mm. When the temperature is balanced, the equipment will automatically conduct tests at a frequency of 10rad/s and the selected stress target value, and the recording and calculation are completed by the data acquisition system.

Test results: Figure 2 is a comparison chart of the change of the complex shear modulus G* (10Hz) with temperature of the modified asphalt prepared in Application Examples 1-3 and Comparative Application Examples 1-2. It can be seen from Figure 2 that at the same temperature Under , the complex shear modulus G* of SBS modified asphalt with NFRC added (NFRC/SBS composite modified asphalt) is greater than the complex shear modulus G* of SBS modified asphalt without NFRC, which shows that the NFRC The addition can improve the deformation resistance of SBS modified asphalt, while the addition of the intermediate product zinc stannate-coated calcium carbonate powder will slightly reduce the deformation resistance of SBS modified asphalt; Figure 3 shows application examples 1-3 and comparative applications. The storage modulus G' (10Hz) of the modified asphalt prepared in Example 1-2 changes with temperature. From Figure 3, it can be seen that at the same temperature, the G' of the NFRC/SBS composite modified asphalt is greater than that of SBS. Modified asphalt, this shows that the addition of NFRC can improve the elastic properties of SBS modified asphalt, while the addition of the intermediate product zinc stannate-coated calcium carbonate powder will slightly reduce the elastic properties of SBS modified asphalt; Figure 4 is an application example 1-3 and Comparative Application Example 1-2. The loss modulus G” (10Hz) of the modified asphalt prepared in Comparative Application Example 1-2 is compared with the temperature change. It can be seen from Figure 4 that at the same temperature, NFRC/SBS modification The loss modulus G" of asphalt is higher than that of SBS modified asphalt, which shows that the addition of NFRC can effectively enhance the viscosity properties of SBS modified asphalt, while the addition of the intermediate product zinc stannate coated calcium carbonate powder will actually Slightly reduce the viscosity properties of SBS modified asphalt.

Compared with SBS modified asphalt without adding NFRC, the reason why the road properties such as deformation resistance, elasticity and viscosity of the composite modified asphalt with intermediate zinc stannate coated calcium carbonate powder and SBS are slightly reduced is that : The intermediate product zinc stannate-coated calcium carbonate powder is an inorganic substance, and inorganic substances can easily segregate in asphalt polymers (that is, the difference in force between the two interfaces causes the inorganic powder to be deposited at the bottom of the asphalt), thus affecting the overall asphalt The consistency of performance more directly affects its road performance. In the process of preparing high-carbon alcohol-coupled zinc stannate-coated calcium carbonate, the coupling agent further introduced on the surface of the zinc stannate-coated calcium carbonate powder is the key to solving the segregation problem, so adding a silane coupling agent in the middle The asphalt performance of the product zinc stannate coated calcium carbonate powder decreased.

3. Smoke collection and smoke component testing

The modified asphalt prepared in Application Examples 1-3 and Comparative Application Examples 1-2 was subjected to a flue gas collection test, and the components in the flue gas were tested and analyzed. The specific method is: take 80.0g of asphalt in a customized split three-necked flask. , heat the asphalt to the warm mixing temperature of 180-200°C, and stir at 250 rpm for 1 hour. Use nitrogen as the carrier gas. Pass the gas generated during the warm mixing of the asphalt into 25 ml of benzene solution through the designed pipeline, and finally collect it. The organic components of asphalt flue gas. After diluting the obtained asphalt flue gas liquid 100 times, the components of the asphalt flue gas were analyzed using a gas chromatography mass spectrometer (GC-MS). In addition, when the mixing time is 20min, 40min, and 60min, a tin foil gas sampling bag with a volume of 1L is used to collect the inorganic flue gas after benzene absorption of the asphalt, and then a flue gas analyzer is used to analyze the inorganic gas at the three time points. The concentration of the main odorous gas hydrogen sulfide was tested and the average value was taken as the final test result.

Test results: Figure 5 shows the GC-MS total gas chromatogram of the modified asphalt prepared in Application Example 2 and Comparative Application Example 2. Under the condition that the other test conditions are the same, the peaks at the positions with the same retention time are larger, indicating that the The higher the component content, as shown in Figure 5, the flue gas generated by SBS modified asphalt has the most organic components and the highest content, while the number and concentration of organic components in the flue gas of NFRC/SBS composite modified asphalt are greatly reduced. Different retention times in the chromatographic column represent different chemical compositions of substances. Qualitative verification of the detected compounds is performed based on the GC-MS total gas chromatogram combined with the National Institute of Standards and Technology (NIST) fragment library (NIST17), and the smoke The concentrations of each component in the gas are relatively compared, and combined with the instrument report, Table 2 is obtained. It can be seen from Table 2 that the flue gas generated by SBS modified asphalt (Comparative Application Example 1) contains a total of 40 organic components, while the organic components contained in the NFRC/SBS composite modified asphalt (Application Example 2) are only 6 Compared with SBS modified asphalt, it is reduced by 85%, indicating that the NFRC asphalt flame retardant and odor-reducing synergist has a good odor-reducing and smoke-suppressing effect.

Table 2

Table 3 shows the test results of the hydrogen sulfide concentration in the inorganic flue gas of Application Examples 1-3 and Comparative Application Examples 1-2. Table 3 shows that the addition of NFRC significantly reduces the hydrogen sulfide concentration in the SBS modified asphalt flue gas, from 178.0 mg/m ³ dropped to 45.0mg/m ³ , a decrease of 74.72%. It shows that NFRC can effectively reduce the odor gas in asphalt flue gas while reducing the organic components in SBS modified asphalt flue gas.

table 3

4. Flue gas collection and testing of solid particle production in flue gas

The modified asphalt obtained in Application Examples 1-3 and Comparative Application Examples 1-2 was subjected to flue gas collection test and the amount of solid particles generated in the flue gas was tested. The specific method is as follows: 80.0g of asphalt was taken into a customized split three-necked flask, heated to a warm mixing temperature of 180-200°C, and stirred at a speed of 250rpm for 1h. During the stirring period, a self-designed glass fiber sleeve adsorption device was used to adsorb macromolecular substances in the asphalt flue gas at the outlet of the three-necked flask. The adsorption time was 1h, and the weight change of the glass fiber sleeve after adsorption of the flue gas was compared, that is, the content of macromolecular substances in the flue gas of NFRC/SBS composite modified asphalt and SBS modified asphalt was compared. The above-mentioned glass fiber sleeve needs to be treated at high temperature to keep its quality stable before it can be used.

Test results: Table 4 shows the mass changes of the glass fiber sleeve before and after asphalt flue gas collection in Application Examples 1-3 and Comparative Application Examples 1-2. From Table 4, it can be seen that the asphalt flame retardant odor synergist (NFRC) can reduce The amount of solid particles produced in asphalt smoke. When NFRC is incorporated, the smoke particles of NFRC/SBS composite modified asphalt (Application Example 2) are reduced by about 77% compared to SBS modified asphalt, indicating that NFRC can improve the thermal stability of SBS modified asphalt and make it high temperature There are fewer macromolecular particles in the smoke produced under these conditions.

Table 4

5. High temperature performance, water stability and rutting performance tests

(1) Sample preparation

Take a certain quality of NFRC/SBS composite modified asphalt, use AC-13 dense proportion to prepare the asphalt mixture, and select diabase as the aggregate. According to the content of the "T0709-2011" standard, the asphalt mixture was prepared into 8 (Φ101.6±0.2)mm×(63.5±1.3)mm cylindrical specimens using the standard compaction method, of which 4 specimens were immersed in 60℃± Take it out after 30 minutes in a constant-temperature water tank at 1°C for use. The other four specimens are immersed in a constant-temperature water tank at 60°C ± 1°C for 48 hours and then take it out for use. In addition, the wheel rolling method was used to prepare 300mm×300mm×50mm plate specimens for later use. The NFRC/SBS composite modified asphalt prepared in Application Examples 1-3 and the SBS modified asphalt prepared in Comparative Application Examples 1-2 were used as raw materials in the sample preparation process to prepare 5 groups of samples.

(2) Test method

The five groups of specimens prepared were subjected to standard Marshall stability, immersed Marshall stability and rutting tests. The specific method is: use an automatic Marshall tester to test the prepared Marshall and immersed Marshall specimens, and record the data collected by the computer; place the rut plate specimen together with the test mold on the test bench of the wheel rutting testing machine, and the test wheel is tested. The walking direction of the central part of the piece must be consistent with the rolling direction of the test piece. Start the automatic rutting deformation recorder. The test time is 1 hour. Record the deformation curve and calculate the dynamic stability of the rutting test.

(3)Test results

Table 5 shows the data on the Marshall stability, water immersion Marshall stability and rutting test dynamic stability of the samples prepared using the modified asphalt prepared in Application Examples 1-3 and Comparative Application Examples 1-2 as raw materials, as shown in Table 5 As shown, the test results show that the Marshall stability test of NFRC/SBS composite modified asphalt exceeds the national standard (6kN), and the Marshall stability, water immersion Marshall stability and rutting test of NFRC/SBS composite modified asphalt (Application Example 2) The dynamic stability is higher than that of SBS modified asphalt, and the water immersion residual strength ratio is increased by 3.46%, which shows that the high temperature performance, water stability and rutting performance of NFRC/SBS composite modified asphalt are higher than that of SBS modified asphalt and can meet the road requirements. Use demand.

table 5

6. Flame retardant performance test

The extreme oxygen index (LOI) of the modified asphalt prepared in Application Examples 1-3 and Comparative Application Examples 1-2 was tested to characterize its flame retardant performance. The test results are shown in Table 6. The test results show that compared with SBS modified asphalt, The flame retardant properties of asphalt and NFRC/SBS composite modified asphalt have been improved, that is, the asphalt flame retardant and odor-free synergist (NFRC) can improve the flame retardant properties of asphalt.

Table 6

The above-described embodiments only describe the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can make various modifications to the technical solutions of the present invention. All deformations and improvements shall fall within the protection scope determined by the claims of the present invention.

Claims (6)

1. A method for preparing an asphalt odor-free flame retardant synergist, which is characterized in that it includes sequentially coating zinc stannate and higher carbon alcohol on the surface of calcium carbonate to obtain high carbon alcohol coupled zinc stannate-coated carbonic acid. Calcium is the asphalt odor-cleaning flame retardant synergist; The method for coating zinc stannate on the surface of calcium carbonate also includes: Add calcium carbonate powder and urea to water, heat, stir, and disperse to obtain a pretreated calcium carbonate aqueous dispersion; Mix zinc stannate, zinc oxide and an alkali metal compound with water, heat and stir, then add the pre-treated calcium carbonate aqueous dispersion, continue heating and stirring the reaction, after the reaction is completed, the obtained emulsion is filtered, dried and calcined to obtain stannic acid Zinc coated calcium carbonate powder; In terms of mass ratio, zinc stannate: zinc oxide: alkali metal compound: calcium carbonate powder = (1.0-2.0): (0.3-0.8): (1.0-2.2): 10; the calcination temperature is 500-700°C , time is 0.8-2.2h; The method for coating higher carbon alcohol on the surface of calcium carbonate also includes: Dissolve the zinc stannate-coated calcium carbonate powder in the ester compound solution, then add a silane coupling agent, heat and stir, then add high-carbon alcohol powder, continue to heat and stir the reaction, filter, dry and grind after the reaction is completed. High-carbon alcohol-coupled zinc stannate-coated calcium carbonate is obtained; The mass ratio of the calcium carbonate powder to the silane coupling agent is 20:(0.15-0.22); the mass ratio of the calcium carbonate powder to the high carbon alcohol is 25:(0.1-0.3). 2. The preparation method according to claim 1, characterized in that the method of adding calcium carbonate powder and urea into water, heating and stirring, and dispersing to obtain the pretreated calcium carbonate aqueous dispersion also includes: The particle size of the calcium carbonate powder is 200-400 mesh; the mass ratio of the calcium carbonate powder to urea is (3.5-5):1, and the dosage ratio of calcium carbonate powder to water is (1-1.5)g:10ml ; The heating and stirring temperature is 35-65°C, and the stirring time is 40-80min. 3. An asphalt odor-free flame retardant synergist prepared by the preparation method according to any one of claims 1-2. 4. A method for preparing modified asphalt, characterized in that the asphalt odor-free flame retardant synergist and modifier described in claim 3 are added to the asphalt, and the mixture is sheared and dispersed evenly to obtain the modified asphalt. 5. The preparation method according to claim 4, characterized in that the amount of the asphalt odor-free flame retardant synergist added is 3.0-15.0‰ of the total mass of asphalt. 6. A modified asphalt obtained by the preparation method according to any one of claims 4 to 5.