CN113088115B

CN113088115B - Modified asphalt for fire prevention of sleeper and preparation method thereof

Info

Publication number: CN113088115B
Application number: CN202110390018.7A
Authority: CN
Inventors: 张小良; 王昊博; 魏佳君; 欧阳春发
Original assignee: Shanghai Institute of Technology
Current assignee: Shanghai Institute of Technology
Priority date: 2021-04-12
Filing date: 2021-04-12
Publication date: 2021-12-21
Anticipated expiration: 2041-04-12
Also published as: CN113088115A

Abstract

The invention discloses modified asphalt for fire prevention of sleepers and a preparation method thereof, and the modified asphalt mainly comprises soap solution, maleic anhydride modified asphalt, a drier and a flame retardant; wherein the soap solution comprises: 4-25% of vinyl chloride aqueous dispersion, 5-30% of methyl acrylate, 6-8% of emulsifier, 5-25% of styrene, 2-10% of epoxy resin and 0.003-0.1% of catalyst. The modified asphalt for fire prevention of the sleeper constructs the flame-retardant cross-linked polymer through the mixing action of a synergistic flame-retardant system formed by vinyl chloride/methyl acrylate/styrene/epoxy resin modified water-based asphalt and a flame retardant, so that the water-based asphalt with an interpenetrating network structure is formed, and along with the increase of the cross-linking density, the modified asphalt for fire prevention of the sleeper forms a compact barrier layer on the surface of the sleeper to prevent the volatilization of bolt oil, and meanwhile, even if an exogenous fire source occurs, the flame-retardant material can form a compact protective layer.

Description

Modified asphalt for fire prevention of sleeper and preparation method thereof

Technical Field

The invention belongs to the field of road construction, and particularly relates to a method for preparing a novel sleeper fireproof asphalt material and sleeper fireproof modified asphalt.

Background

With the development of highway infrastructure, the asphalt industry, which is an irreplaceable material for highway infrastructure, has also made great technical progress. The increasing levels of bitumen use have led to the development of deficiencies in conventional hot bitumens, such as: asphalt is too fast to condense, and needs to be heated repeatedly during use, which causes great energy waste and environmental pollution, and the secondary construction and repair of road construction inevitably cause serious shortage of resources. Research and research find that the research and application of the asphalt emulsifier are one of effective ways for solving the problems. Compared with the traditional hot asphalt, the emulsified asphalt has the advantages of saving energy, improving work efficiency, prolonging construction season, improving construction conditions, reducing environmental pollution, prolonging the service life of asphalt pavement and the like.

The sleeper has the advantages that the sleeper is rich in elasticity and can ease the dynamic impact action of the train; easy to process and manufacture; the transportation, the laying, the maintenance and the repair are convenient; the insulating property is better; the fastener is simply connected with the wooden pillow; the wooden sleeper and the crushed stone ballast have larger friction coefficient, and the stability of the track can be ensured. The main defects of the sleeper are short service life and many failure reasons, mainly corrosion, mechanical abrasion and splitting, which are cause and effect with each other; secondly, the elasticity and the durability are not completely consistent, the track is easy to be unsmooth under the action of locomotives and vehicles, and particularly, the stability of a wood sleeper section paved by a seamless line is poor; and the wood resources are poor, the consumption is large in all aspects, and the use requirements can not be met no matter the quantity or the quality.

Through the bolt-up between sleeper and the track, in the railway routine maintenance in-process, in order to avoid the bolt to take place the corrosion, ensure that bolt nut can reliable compress tightly the track, need at bolt nut coating bolt oil. Because the bolt oil contains a large amount of volatile components and light components, the wood is a porous material, absorbs grease, and is easy to self-heat and self-ignite under the coupling complex environment of certain humidity, microorganisms and the like.

Disclosure of Invention

In order to solve the problem that accidents are caused by the existence of bolt oil in a sleeper, the invention provides modified asphalt for sleeper fire prevention and a preparation method thereof, wherein an interpenetrating network structure is formed to achieve the purpose of synergistic fire prevention. The technical scheme of the invention is as follows:

a modified asphalt for fire prevention of sleeper is prepared from soap solution, maleic anhydride modified asphalt, drier and fire retardant; wherein the soap solution comprises: 4-25% of vinyl chloride aqueous dispersion, 5-30% of methyl acrylate, 6-8% of emulsifier, 5-25% of styrene, 2-10% of epoxy resin and 0.003-0.1% of catalyst. The maleic anhydride modified asphalt has better performance, is more suitable for the preparation method, and can achieve good expected effect; the drier can accelerate the curing reaction of the soap solution, and compared with ethylene, the chloroethylene component introduces chlorine element and has good flame retardant property; the methyl acrylate enables the copolymer to have good film-forming property and high Vicat softening point and rigidity, the epoxy resin enables the copolymer to embody an interpenetrating network structure, and the subsequent addition of the flame retardant enables the modified asphalt to play a role in synergistic fire prevention.

The modified asphalt for fire prevention of the sleeper constructs the flame-retardant cross-linked polymer, forms the water-based asphalt with an interpenetrating network structure, and forms a compact barrier layer on the surface of the sleeper along with the increase of the cross-linking density, so as to prevent the volatilization of bolt oil, and meanwhile, the flame-retardant material can form a compact protective layer even if an exogenous fire source occurs.

In some embodiments, the weight ratio of maleic anhydride modified asphalt to soap solution is 1: 0.01-1.5.

In some embodiments, the flame retardant is at least one of antimony oxide, expanded graphite; the expanded graphite has good corrosion resistance and oil absorption performance, the expanded graphite has large adsorption capacity to oils, floats on the water surface after oil absorption, is easy to catch and recycle, and is simple and convenient to recycle. Antimony oxide (Sb)₂O₃) The flame-retardant fireproof additive belongs to antimony series, has better fireproof effect in the aspect of flame retardance, and if other flame retardants are used for replacing the flame retardant with the expanded graphite, a synergistic flame-retardant system with good performance cannot be formed, so that the flame-retardant effect is greatly reduced.

In some embodiments, the catalyst is: the catalyst may be at least one of ammonium sulfate, sodium bisulfite, potassium persulfate, sodium bisulfite, persulfate, or mercaptan.

In some embodiments, the drier is cobalt naphthenate, calcium naphthenate, zinc hexacyanocobaltate, or dibutyltin dilaurate, or a combination thereof.

In some embodiments, the soap solution is added with maleic anhydride modified asphalt to obtain a first modified asphalt emulsion, wherein the addition amount of the drier is 0.1-3 wt% of the weight of the first modified asphalt emulsion; based on the weight of the product after the drier is added, the flame retardant is antimony oxide and expanded graphite, wherein the addition amount of the antimony oxide is not less than 5% and the addition amount of the expanded graphite is not less than 3%.

In some embodiments, the emulsifier is at least one of a cationic emulsifier, an anionic emulsifier, or a nonionic emulsifier.

The emulsified asphalt is liquid asphalt which is produced by asphalt and emulsifier under a certain process condition and has oil-in-water or water-in-oil. The emulsified asphalt is classified into cationic emulsified asphalt, anionic emulsified asphalt and nonionic emulsified asphalt. The asphalt particles of the cation emulsified asphalt have positive charges, and the anion emulsified asphalt particles have negative charges. The anionic emulsifier system is stable in alkaline solution, but can be unstable when meeting acid, metal salt and hard water, and can be separated out as gel below the three-phase equilibrium point to lose emulsifying capacity. The non-ionic emulsifier is insensitive to pH change and is relatively stable; however, the emulsifying capacity is still inferior to that of the anionic emulsifying system, and the anionic emulsifying system is usually not used alone, and is often used together with an anionic emulsifying agent (to improve the sensitivity of a pure anionic emulsifying system to pH value, electrolyte and the like.

In some embodiments, the emulsifier is a complex emulsifying system formed by an anionic emulsifier and a nonionic emulsifier, and the anionic emulsifier is: at least one of fatty acid soap, alkyl sulfate, alkyl benzene sulfonate and phosphate, and the nonionic emulsifier is: at least one of polyoxyethylene ether, polyoxypropylene ether, ethylene oxide and propylene oxide block copolymer, polyalcohol fatty acid ester and polyvinyl alcohol. Physical and chemical stability can be ensured.

In some embodiments, the maleic anhydride modified asphalt is comprised of a base asphalt, maleic anhydride, and an initiator, wherein maleic anhydride is added in an amount of 2 to 10 wt% based on the weight of the base asphalt, and the initiator is added in an amount of 0.3 to 3 wt% based on the weight of maleic anhydride.

In some embodiments, the base asphalt is: at least one of natural asphalt, petroleum asphalt, coal tar asphalt and oil sand asphalt.

The invention also provides a preparation method of the modified asphalt for fire prevention of the sleeper, which comprises the following steps:

1) preparing 4-25 wt% of vinyl chloride aqueous dispersion, and adding the following components by weight of the vinyl chloride aqueous dispersion: 5-30 wt% of methyl acrylate, 5-25 wt% of styrene, 2-10 wt% of epoxy resin and 0.003-0.1 wt% of catalyst, then adding 6-8 wt% of emulsifier based on the weight of the vinyl chloride aqueous dispersion, stirring and mixing, and reacting for 2-6h at 40-50 ℃ to obtain soap solution;

2) heating the matrix asphalt to 140-160 ℃, adding maleic anhydride accounting for 2-10 wt% of the matrix asphalt, adding an initiator accounting for 0.3-3 wt% of the maleic anhydride, stirring and mixing, and reacting at 140-160 ℃ for 4-6 hours to obtain maleic anhydride modified asphalt;

3) modifying asphalt with maleic anhydride: the weight ratio of the soap liquid is 1: 0.01-1.5, adding the maleic anhydride modified asphalt obtained in the step 2) into the soap solution obtained in the step 1), and shearing and dispersing to obtain a first modified asphalt emulsion;

4) adding a drier accounting for 0.1-3 wt% of the weight of the first modified asphalt emulsion into the step 3), and uniformly mixing to obtain second modified water-based asphalt;

5) antimony oxide (Sb) of not less than 5 percent of the weight of the second modified water-based asphalt is added into the step 4)₂O₃) And not less than 3 percent of expanded graphite to obtain the modified asphalt for fire prevention of the sleeper.

Compared with the prior art, the invention has the following beneficial effects:

the flame-retardant cross-linked polymer is constructed through the mixing action of a synergistic flame-retardant system formed by vinyl chloride/methyl acrylate/styrene/epoxy resin modified water-based asphalt, antimony oxide and expanded graphite, so that the water-based asphalt with an interpenetrating network structure is formed, and along with the increase of the cross-linking density, the modified asphalt for fire prevention of the sleeper forms a compact barrier layer on the surface of the sleeper, so that the volatilization of bolt oil is prevented, and meanwhile, even if an exogenous fire source occurs, the flame-retardant material can form a compact protective layer.

In addition, the modified asphalt for fire prevention of the sleeper has good compatibility, and can achieve the effects of adapting to severe environment and climate and preventing corrosion after being mixed, thereby achieving the purpose of enhancing nail holding effect. Therefore, the method has wide application prospect.

Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.

Detailed Description

It is known that all-weather aging of road asphalt mainly includes oxidation aging, volatile matter decay, physical hardening, water aging, etc., and the aging degree and the aging type are closely related to the chemical composition and the structure type. The factors which can cause the asphalt aging mainly include environmental factors such as temperature, oxygen, illumination, water and the like or the combined action of the factors. The performance of asphalts of different qualities and compositions after aging is very different.

The invention provides a preparation method of polyvinyl chloride/methyl acrylate/styrene/epoxy resin modified water-based asphalt for fire prevention of sleepers, which comprises the following steps:

1) preparing 4-25 wt% of vinyl chloride aqueous dispersion, adding 5-30 wt% of methyl acrylate, 5-25 wt% of styrene, 2-10 wt% of epoxy resin and 0.003-0.1 wt% of catalyst based on the weight of the vinyl chloride aqueous dispersion, adding 6-8 wt% of emulsifier based on the weight of the vinyl chloride aqueous dispersion, stirring and mixing, and reacting at 40-50 ℃ for 2-6h to obtain soap solution (also called as vinyl chloride/methyl acrylate/styrene/epoxy resin copolymer aqueous emulsion);

3) 1: 0.01-1.5, adding the maleic anhydride modified asphalt obtained in the step 2) into the soap solution obtained in the step 1), and performing shearing dispersion for 10-20min at the rotation speed of 8000-;

4) adding a drier which accounts for 0.1-3 wt% of the weight of the first modified asphalt emulsion into the step 3), and uniformly mixing to obtain second modified water-based asphalt (also called as chloroethylene/methyl acrylate/styrene/epoxy resin modified water-based asphalt);

5) adding 5-15 wt% of antimony oxide (Sb2O3) and 3-15 wt% of expanded graphite into the step 4) by weight of the second modified water-based asphalt to obtain the modified asphalt for fire prevention of the sleeper.

The method of the present invention can provide a vinyl chloride/methyl acrylate/styrene/epoxy resin copolymer modified aqueous asphalt which can be an emulsion product as an industrial product, i.e., the modified aqueous asphalt for fire prevention of crossties obtained in the above step (5). And does not refer to asphalt formed after the paving construction, as will be readily understood by those skilled in the art.

The flame-retardant cross-linked polymer is constructed under the mixing action of a synergistic flame-retardant system consisting of the second modified water-based asphalt, antimony oxide (Sb2O3) and expanded graphite, so that the water-based asphalt with an interpenetrating network structure is formed, is a brand new modified emulsified asphalt and can achieve the synergistic fireproof effect. The modified asphalt for fire prevention of the sleeper is coated on the surface of the sleeper, the compatibility between the sleeper and the asphalt is good, and the purpose of corrosion prevention can be achieved after mixing.

The modified asphalt for fire prevention of the sleeper, prepared by the invention, overcomes the defects of common emulsified asphalt, forms an interpenetrating network structure, introduces chlorine element and has good flame retardant property. The asphalt is emulsified by chloroethylene/methyl acrylate/styrene/epoxy resin copolymer emulsion and then is crosslinked into a polymer network whole. Compared with a pure asphalt colloid structure, the integral network structure has much stronger capability of resisting external force damage; the firm epoxy cross-linked network improves the durability and the bonding strength of the modified emulsified asphalt. Meanwhile, a synergistic flame-retardant system consisting of antimony oxide (Sb2O3) and expanded graphite is added to construct a flame-retardant cross-linked polymer, so that the modified asphalt for fire prevention of the sleeper with the interpenetrating network structure is formed.

And in order to make the mixing of the prepared modified asphalt more uniform and thorough, the steps of the preparation method are unique, and the sequence cannot be changed, so that the impracticability of the product caused by blind addition is avoided.

In the production and processing of the modified emulsified asphalt of the present invention, the first step is to prepare a cross-linked vinyl chloride aqueous solution, i.e., a macromolecular emulsifier aqueous solution. The cross-linked aqueous vinyl chloride solution may be referred to herein simply as "soap solution" according to customary nomenclature of the industry.

In preparing the soap solution, the concentration of vinyl chloride in the aqueous solution may be 4 to 25 wt%, for example, 5 to 18 wt%, 6 to 15 wt%, 7 to 13 wt%, or 8 to 12 wt%, preferably about 10 wt%, depending on the molecular weight of vinyl chloride, the kind of base asphalt, etc. If the concentration of the aqueous solution of vinyl chloride is less than 5 wt%, the stability of the first modified asphalt emulsion obtained in step 3) tends to be lowered; if the concentration of the aqueous solution of vinyl chloride is more than 20% by weight, the viscosity of the final product is increased, the water resistance is lowered, and the waste of the polymer material and the production cost of the modified asphalt emulsion are increased.

The amount of methyl acrylate added is 5 to 30% by weight, for example 5.5 to 25% by weight, 6 to 20% by weight, 7.5 to 15% by weight, preferably about 20% by weight, based on the weight of the aqueous solution of vinyl chloride, depending on the type of vinyl chloride, the concentration of the aqueous solution of vinyl chloride, the degree of polymerization or molecular weight of vinyl chloride, and the desired degree of crosslinking of vinyl chloride. Since the reactivity ratio of methyl acrylate is much greater than that of vinyl chloride, a special process is required to obtain the desired copolymer. In the copolymerization process, the concentration of the monomer which is easy to polymerize and difficult to copolymerize in the system can be kept small, the concentration of the monomer which is easy to copolymerize and difficult to polymerize is increased, and the composition of the copolymer is controlled by controlling the relative concentration of the comonomer. Generally, the technique of continuously dripping a monomer which has high activity and is easy to self-polymerize into a monomer which is easy to copolymerize and not easy to self-polymerize is adopted in industry to achieve the purpose of controlling the composition of the copolymer.

It should be understood that when numerical features are expressed herein, the terms "about" or "approximately" mean that the number indicated may have a margin of error or variance of 10%, ± 9%, ± 8%, ± 7%, ± 6% or ± 5%.

In the modification with vinyl chloride/methyl acrylate/styrene/epoxy resin, the maleic anhydride may be added in an amount of 2 to 10 wt%, for example 2 to 7.5 wt%, 3 to 7 wt%, preferably 5 to 7 wt%, more preferably about 6 wt% of the base asphalt, depending on the type of base asphalt, the desired degree of asphalt grafting reaction, i.e., the grafting ratio, and the higher the grafting ratio, the more stable the product after emulsification, the lower the grafting ratio, which may result in the product settling out of water, and the vinyl chloride/methyl acrylate/styrene/epoxy resin copolymer and the base asphalt may be separated.

If the addition of the maleic anhydride is less than 1 wt%, the crosslinking between the asphalt and the chloroethylene/methyl acrylate/styrene/epoxy resin copolymer emulsion is insufficient, a crosslinked network integral body cannot be formed, the chloroethylene/methyl acrylate/styrene/epoxy resin grafted asphalt can be separated, the emulsion is unstable, and the mechanical property of the polymer integral body is reduced due to the lack of a bridging chemical bond between the polymers after the solidification, so that the aim of modification cannot be achieved; if the maleic anhydride is added in an amount of more than 8 wt%, the asphalt may be gelled due to too high graft density and may not be emulsified into an emulsion.

On the other hand, the flame-retardant cross-linked polymer is constructed by the mixing action of the synergistic flame-retardant system consisting of the second modified water-based asphalt, antimony oxide (Sb2O3) and expanded graphite, so that the water-based asphalt with an interpenetrating network structure is formed, and with the increase of the cross-linking density, the modified asphalt for fire prevention of the sleeper forms a compact barrier layer on the surface of the sleeper to prevent the volatilization of bolt oil, and meanwhile, even if an external fire source occurs, the flame-retardant material can form a compact protective layer. In addition, the sleeper and the modified asphalt for the sleeper fire prevention have good compatibility, and the purpose of corrosion prevention can be achieved after mixing.

In this context, a range of values from one value to another is a general expression avoiding any recitation of all values in the range in the specification. Thus, recitation of a range of values herein is intended to encompass any value within the range and any smaller range defined by any value within the range, as if the range and smaller range were explicitly recited in the specification.

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. In practice, the invention will be understood to cover all modifications and variations of this invention provided they come within the scope of the appended claims.

The addition amount, the content and the concentration of various substances are referred to in the examples, wherein the parts are all referred to as weight parts unless otherwise specified; the percentage contents are all mass percentages unless otherwise specified.

The softening point of the asphalt material is tested according to the method GB/T4507 asphalt softening point determination method-ring and ball method.

The tensile test of the asphalt product is carried out according to the method T0629 in JTGE20-2011 test Specification for road engineering asphalt and asphalt mixtures. The cement (vinyl chloride/acrylate copolymer modified water-based asphalt before aging) was poured into a 300 x 100 x2 steel mold, dried and formed into an asphalt strip, and the tensile strength and elongation at break were measured.

The ignition temperature is measured by a CONE Calorimeter (CONE), and the combustion performance of a new generation of polymer material tester based on an oxygen consumption principle has various combustion parameters of combustible materials obtained by the CONE in a fire, including a Heat Release Rate (HRR), Total Heat Release (THR), Effective Heat of Combustion (EHC), ignition time (TTI), smoke and toxicity parameters, mass change parameters (MLR) and the like. The cone calorimeter method has the advantages that the parameter measurement value is slightly influenced by external factors, the correlation with large-scale experimental results is good, and the like, and is applied to research in many fields.

EXAMPLE 1 preparation of soap solution

Heating 250 g of water to 50 ℃, adding 25.5g of vinyl chloride (supplier, Shanghai Moshu Biotech Co., Ltd.; purity 0.2mg/mL in MeOH), stirring and dissolving, then adding 5.1 g of methyl acrylate (supplier, Shanghai deepening practice Co., Ltd.; brand: VC-M) and 1.3g of styrene (supplier, Shanghai Tatan; purity 99%), 2.5g of epoxy resin (supplier, Shanghai Gaoxin; purity E-44), then adding 0.025g of ammonium persulfate (supplier, Shanghai Tatan; specification 19333477% purity is not less than 98%) initiator, finally adding 1.53g of sodium dodecyl sulfate (supplier, Shanghai Tatan; specification 19333042% purity is not less than 88.0%) and polyvinyl alcohol (supplier, Shanghai Tatan; specification 193337741788) composite emulsifier, stirring and mixing at the rotating speed of 300r/min for 10min, reacting at 50 ℃ for 4h to obtain vinyl chloride/methyl acrylate/styrene/epoxy resin copolymer with viscosity of 3000.s. Aqueous emulsion, namely soap solution.

Using a similar procedure as described above, different soap solutions were prepared according to the following formulation.

Preparation of different soap liquids

Note: the mass percentages in table one are the mass percentages of the components in the vinyl chloride aqueous dispersion.

Example 2 preparation of maleic anhydride modified asphalt

Heating 400g of matrix asphalt (70# matrix asphalt) to 140-160 ℃, adding 2-10 wt% of maleic anhydride based on the weight of the matrix asphalt, adding the maleic anhydride and the initiator in the manner of the following table two, adding 1 wt% of the initiator (ammonium persulfate) based on the weight of the maleic anhydride, shearing, stirring and mixing at 8000r/min, and reacting at 140-160 ℃ for 4-6h to obtain the maleic anhydride modified asphalt.

Preparation of maleic anhydride modified asphalt

As can be seen from Table II, the softening point of the maleic anhydride modified asphalt increases with the increase of the maleic anhydride content when the maleic anhydride modified asphalt is prepared.

Example 3 preparation of second modified aqueous Pitch

Respectively adding the maleic anhydride modified asphalt obtained in experiment number 3 in example 2 into four soap solutions with the soap solution numbers of 1, 2, 3 and 4 obtained in example 1, and shearing and dispersing to obtain a first modified asphalt emulsion; and respectively adding a drier (dibutyltin dilaurate) accounting for 0.1-3 wt% of the weight of the first modified asphalt emulsion, and respectively shearing at the rotating speed of 8000r/min for 15min to obtain second modified water-based asphalt in an emulsion state.

TABLE III comparison of the Properties of the products prepared from the various second modified Water-based asphalts

From the results in the table three, it is understood that the second modified aqueous asphalt product of the present example has a tensile strength of 1MPa or more, an elongation at break of 150% or more, and high mechanical properties. In this example, the softening point decreased and the tensile strength decreased with the increase in the methyl acrylate content, and the elongation increased, whereas the lower the relative amount of the acrylic ester added, the higher the strength, and the lower the elongation.

The first modified aqueous asphalt of serial No. 12 is most moderate in tensile strength and elongation at break and better in combination property, and thus is used for subsequent tests.

Example 4 preparation method of modified asphalt for fire prevention of crossties

The second modified aqueous asphalt obtained in experiment No. 12 of example 3 was added with antimony oxide (purity: 99.8%) in an amount of 5 to 15 wt% and expanded graphite (EG-X200) in an amount of 3 to 15 wt% based on the weight of the second modified aqueous asphalt in accordance with the formulation shown in Table four to obtain a modified asphalt for fire prevention of crossties.

TABLE IV comparison of the ignition temperatures of the crossties

As can be seen from Table IV, the synergistic flame-retardant systems comprising different amounts of antimony oxide (Sb2O3) and expanded graphite in the second modified aqueous asphalt had different temperatures at which the crossties were ignited, and the ignition temperature of No. 17 was 560 ℃. The combination of antimony oxide and expanded graphite composite flame retardant usually shows a synergistic effect, which can promote intermolecular crosslinking reaction to form carbide, and the carbide covers the surface of asphalt, thereby playing a role in flame retardance. Meanwhile, the coating has high mechanical property, good tensile strength and good fracture elongation, can be quickly molded when being coated on the surface of a sleeper to form a compact protective layer, adapts to the climate change of severe environment, has strong weather resistance effect, and can achieve corrosion prevention without influencing the nail holding effect.

Although the technical solution of the present invention is described above by taking the # 70 base asphalt as an example, it is obvious to those skilled in the art that the technical solution of the present invention is also applicable to similar treatment of other base asphalt according to the present disclosure.

While the foregoing is directed to the preferred embodiment of the present invention, it is not intended to detail all of the same, and it is to be understood that such embodiment is merely illustrative of the present invention and is not to be considered as limiting the scope of the invention, which is limited only by the claims and their full scope and equivalents.

The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. In light of the above teachings, those skilled in the art will readily appreciate that the materials and their equivalents, the processes and their equivalents, as listed or exemplified herein, are capable of performing the invention in any of its several forms, and that the upper and lower limits of the parameters of the materials and processes, and the ranges of values between these limits are not specifically enumerated herein.

Claims

1. A modified asphalt for fire prevention of crosstie is characterized in that the modified asphalt is mainly prepared from soap solution, maleic anhydride modified asphalt, drier and flame retardant;

wherein the soap solution comprises: an aqueous dispersion of vinyl chloride having a mass concentration of 4 to 25%, based on the weight of the aqueous dispersion of vinyl chloride: 5-30 wt% of methyl acrylate, 6-8 wt% of emulsifier, 5-25 wt% of styrene, 2-10 wt% of epoxy resin and 0.003-0.1 wt% of catalyst;

wherein the weight ratio of the maleic anhydride modified asphalt to the soap solution is 1: 0.01-1.5;

wherein the flame retardant is antimony oxide and expanded graphite, and the catalyst is persulfate;

the modified asphalt for fire prevention of the sleeper is prepared by the following method:

1) preparing 4-25 wt% of vinyl chloride aqueous dispersion, and adding the following components by weight of the vinyl chloride aqueous dispersion: 5-30 wt% of methyl acrylate, 5-25 wt% of styrene, 2-10 wt% of epoxy resin and 0.003-0.1 wt% of catalyst, then adding 6-8 wt% of emulsifier based on the weight of the vinyl chloride aqueous dispersion, and reacting for 2-6h at 40-50 ℃ to obtain soap solution;

2) heating the base asphalt to 140-160 ℃, adding maleic anhydride accounting for 2-10 wt% of the weight of the base asphalt, adding an initiator accounting for 0.3-3 wt% of the weight of the maleic anhydride, and reacting at 140-160 ℃ for 4-6h to obtain maleic anhydride modified asphalt;

5) and 4) adding antimony oxide with the weight not less than 5 wt% and expanded graphite with the weight not less than 3% of the second modified water-based asphalt into the step 4), so as to obtain the modified asphalt for fire prevention of the sleeper.

2. The modified asphalt for fire prevention of crossties according to claim 1, wherein the drier is cobalt naphthenate, calcium naphthenate, zinc hexacyanocobaltate or dibutyltin dilaurate, or a combination thereof.

3. The modified asphalt for fire prevention of crossties according to claim 1, wherein the emulsifier is at least one of a cationic emulsifier, an anionic emulsifier, and a nonionic emulsifier.

4. The modified asphalt for fire prevention of crosstie according to claim 3, wherein the emulsifier is a composite emulsifying system formed by anionic emulsifier and nonionic emulsifier, wherein the anionic emulsifier is: at least one of fatty acid soap, alkyl sulfate, alkyl benzene sulfonate and phosphate, and the nonionic emulsifier is: at least one of polyoxyethylene ether, polyoxypropylene ether, ethylene oxide and propylene oxide block copolymer, polyalcohol fatty acid ester and polyvinyl alcohol.

5. The modified asphalt for fire prevention of crossties according to claim 1, wherein the base asphalt is: at least one of natural asphalt, petroleum asphalt, coal tar asphalt and oil sand asphalt.