Disclosure of Invention
The technical problem to be solved by the invention is as follows: the existing emulsified asphalt has the defects of generally low tensile strength and elongation at break, and solves the problems that counter ions such as sodium ions, ammonium ions, chloride ions, sulfate ions, sulfite ions and the like pollute water and frequently low-temperature stability is reduced.
In order to solve the technical problems, the invention provides a preparation method of single-component waterborne epoxy/SBS composite modified emulsified asphalt, which is characterized by comprising the following steps:
step 1): preparing 2-20% of polyethylene glycol aqueous dispersion, adding 1-30% of isocyanate, 1-20% of 2, 2-dimethylolpropionic acid and 0.003-0.1% of catalyst by weight of polyethylene glycol, stirring and mixing, and reacting at 60-80 ℃ for 2-6h to obtain an aqueous polyurethane solution;
step 2): heating the matrix asphalt to 140-;
step 3): stirring and mixing the maleic anhydride modified asphalt obtained in the step 2) with SBS and a compatilizer, wherein the amount of SBS and the compatilizer is 0.1-10% of the weight of the maleic anhydride modified asphalt, so as to obtain maleic anhydride/SBS modified asphalt;
step 4): mixing the maleic anhydride/SBS modified asphalt obtained in the step 3) with a mixing ratio of 1: adding 0.01-1.5 weight percent of the modified asphalt into the aqueous polyurethane solution obtained in the step 1), and performing shearing dispersion for 10-20min at the rotating speed of 8000-10000r/min to obtain maleic anhydride/SBS modified asphalt emulsion;
step 5): uniformly mixing the epoxy resin and the drier with the maleic anhydride/SBS modified asphalt emulsion obtained in the step 4), wherein the using amounts of the epoxy resin and the drier are respectively 1-50% and 0.1-3% of the weight of the maleic anhydride/SBS modified asphalt emulsion, and obtaining the single-component waterborne epoxy resin/SBS composite modified emulsified asphalt in an emulsion state.
Preferably, the stirring and mixing in step 1) is stirring and mixing at a rotation speed of 60-600r/min, such as 200-500 r/min.
Preferably, the polyethylene glycol in the step 1) is any one or a mixture of several of PEG-400, PEG-600, PEG-1000 and PEG-2000.
Preferably, the isocyanate in step 1) is one or a mixture of Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), 1, 6-hexamethylene diisocyanate (HDI, or "hexamethylene diisocyanate") and dicyclohexylmethane diisocyanate (HMDI), and prepolymers thereof.
Preferably, the catalyst in step 1) is diisooctyl tin mercaptide, dibutyl tin mercaptide or a mixture of the two.
Preferably, the base asphalt in step 2) is any one or a mixture of several of natural asphalt, petroleum asphalt, coal tar asphalt and oil sand asphalt, and can be 70# base asphalt or 90# asphalt.
Preferably, the initiator in the step 2) is any one or a mixture of more of dicumyl peroxide, benzoyl peroxide and tert-butyl hydroperoxide. The initiator is a strong oxidant and is used for catalyzing the graft copolymerization reaction of maleic anhydride and asphalt.
Preferably, the stirring and mixing in step 2) is preferably stirring and mixing at a rotation speed of 60-1000r/min, such as 300-800 r/min.
Preferably, the stirring and mixing in the step 3) is preferably stirring and mixing at a rotation speed of 60-1000r/min, such as 300-800 r/min.
Preferably, the epoxy resin in the step 4) is any one or a mixture of several of diphenol propane type epoxy resin, novolac polyepoxy resin and glycidyl ester epoxy resin.
Preferably, the epoxy resin in the step 5) is bisphenol A type epoxy resin, and the epoxy value is 0.40-0.55.
Preferably, the drier in step 5) is any one or a mixture of cobalt naphthenate, calcium naphthenate and zinc hexacyanocobaltate. The drier is used for catalyzing the cross-linking reaction between carboxyl and epoxy resin in the emulsifier, and the epoxy resin and the asphalt are mutually cross-linked into a macromolecular network whole after cross-linking.
Preferably, the stirring and mixing in the step 5) is preferably stirring and mixing at a rotation speed of 300-.
The invention also provides the single-component waterborne epoxy/SBS composite modified emulsified asphalt prepared by the preparation method of the single-component waterborne epoxy/SBS composite modified emulsified asphalt, and a usable epoxy/SBS composite modified asphalt condensate is formed after construction.
The invention provides a novel process for producing single-component aqueous epoxy/SBS composite modified emulsified asphalt, which improves the tensile strength and elongation at break of the product, improves the low temperature resistance of the asphalt, and solves the problems that the ionic emulsifier pollutes water quality and the mixture is mixed and transported.
The asphalt prepared by the invention has simple and rapid preparation process, the tensile strength of the product is more than 3MPa, the elongation at break is more than 100%, the Frass brittle point is lower than minus 20 ℃, and the asphalt has good stability, even if the asphalt is mixed with aggregate and water is not solidified, the mechanical property and the anti-rutting capability of the asphalt are improved, meanwhile, the weather resistance is good, the low temperature resistance is greatly improved, and the problem of mixing and transporting the emulsified asphalt and the aggregate is solved. The asphalt product solves the compatibility of emulsified asphalt and epoxy resin, and prevents the phenomenon of layering. In addition, the single-component waterborne epoxy/SBS composite modified emulsified asphalt does not contain an additional low-molecular ionic emulsifier, so that the water pollution is reduced, and the single-component waterborne epoxy/SBS composite modified emulsified asphalt belongs to an environment-friendly construction material and has a wide application prospect.
Detailed Description
In order to make the invention more comprehensible, preferred embodiments are described in detail below.
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 temperature, oxygen, illumination, water and the like or the combination of the factors. The performance of asphalts of different qualities and compositions after aging is very different.
The method of the present invention can provide a single-component aqueous epoxy/SBS composite modified emulsified asphalt, which can be an emulsion product, i.e., the single-component aqueous epoxy/SBS composite modified emulsified asphalt in an emulsion state obtained in the above step 5), as an industrial product, rather than the asphalt formed after the paving construction, as will be readily understood by those skilled in the art.
The single-component waterborne epoxy/SBS composite modified emulsified asphalt is brand-new modified emulsified asphalt, has good stability, oxidation resistance and low-temperature resistance after being laid, constructed and aged, greatly improves the mechanical property and the anti-rutting capability of the asphalt, has good weather resistance and can adapt to severe environment.
The single-component waterborne epoxy/SBS composite modified emulsified asphalt prepared by the invention improves the low-temperature toughness of common emulsified asphalt and has higher tensile strength and low-temperature stability. After the maleic anhydride is added into the matrix asphalt, on one hand, the maleic anhydride can perform esterification reaction with active groups such as hydroxyl and the like in the asphalt to play a role of a coupling agent, so that the average molecular weight of the asphalt is increased; on the other hand, after the maleic anhydride is dispersed in the base asphalt, the maleic anhydride and SBS added into the asphalt are subjected to graft reaction, and the generated SBS-maleic anhydride-asphalt ternary graft polymer is equivalent to a compatilizer of the asphalt and SBS, so that the compatibility of the asphalt and SBS is remarkably improved, and the SBS is more uniformly dispersed in an asphalt system to form a stable network structure.
And then, by controlling the addition proportion of DMPA in the synthesis of the waterborne polyurethane, the waterborne polyurethane with the carboxyl content of more than 50 percent is obtained and used as a macromolecular emulsifier. The macromolecular emulsifier prepared in this way has high storage stability and is dispersed in an asphalt system. When the moisture in the asphalt is not volatilized, the asphalt is used as a separant to separate functional groups, such as maleic anhydride and other groups, in the asphalt, which react with epoxy groups; after the moisture in the asphalt is volatilized, a large amount of carboxyl in the waterborne polyurethane can be combined with epoxy groups to form a stable crosslinking structure. In addition, PEG and DMPA which are greatly existed in the waterborne polyurethane are used as 'soft segments' and the butadiene block in SBS is synergistic, so that the good toughness is still maintained at low temperature, and the low temperature resistance of the emulsified asphalt is obviously improved. The single-component waterborne epoxy/SBS composite modified emulsified asphalt obtained by designing and synthesizing the waterborne polyurethane emulsifier with the ultrahigh carboxyl content and carrying out layer-by-layer polymerization crosslinking is ensured to have good high-temperature stability and low-temperature crack resistance.
For convenience of description, the "one-component aqueous epoxy/SBS composite modified emulsified asphalt" of the present invention is sometimes referred to herein simply as "modified emulsified asphalt".
In the production and processing of the modified emulsified asphalt, the first step is to prepare aqueous polyurethane solution, namely macromolecular emulsifier aqueous solution. The aqueous polyurethane solution herein may be referred to as "soap solution" for short, according to customary nomenclature in the industry.
In preparing the soap solution, the concentration of polyethylene glycol in the aqueous solution may be from 5 to 20% by weight, for example, from 6 to 12% by weight, from 7 to 14% by weight, or from 9 to 16% by weight, preferably about 10% by weight, depending on the degree of polymerization or molecular weight of polyethylene glycol, the type of base asphalt, and the like. If the concentration of the polyethylene glycol is lower than 5 wt%, the stability of the maleic anhydride/SBS modified asphalt emulsion obtained in the step 4) tends to be reduced; if the concentration of the aqueous solution of polyethylene glycol is more than 20 wt%, the viscosity of the final product is increased, which is not favorable for practical use, and the water resistance is reduced, which also causes waste of polymer materials and increases the production cost of the modified asphalt emulsion.
The isocyanate is added in an amount of 10 to 30% by weight, for example 10 to 16%, 12 to 20%, 15 to 25% by weight, based on the weight of the aqueous polyethylene glycol solution. If the amount of the isocyanate added is less than 10% by weight, it is difficult to sufficiently react with the polyethylene glycol to form a stable aqueous solution of the macromolecular emulsifier. If the isocyanate is added in an amount of more than 30% by weight, the intermolecular crosslinking density of polyethylene glycol is increased to cause polyethylene glycol gelation. DMPA may be added in an amount of 2-20 wt%, for example 2-6%, 4-10%, 10-20% based on the weight of the aqueous polyethylene glycol solution. The DMPA with too low addition amount ensures that the content of carboxyl in a polyurethane system is not enough, and cannot form a stable cross-linking structure with an epoxy group added finally, and the DMPA with too high addition amount can cause excessive esterification reaction in the system, so that the gelation phenomenon of polyurethane occurs. In summary, the addition amounts of isocyanate and DMPA in various proportions are calculated according to the proportion of-NCO/-OH in the system of nearly 1:1, based on the types of isocyanate, the concentration of the aqueous solution of polyethylene glycol, the degree of polymerization or molecular weight of polyethylene glycol, and the expected crosslinking degree of polyethylene glycol. Preferably about 15% by weight of isocyanate, 10% DMPA, to produce an aqueous polyurethane as the macromolecular emulsifier.
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 of the base asphalt with maleic anhydride/SBS, the maleic anhydride may be added in an amount of 1-8 wt%, for example 2-7.5 wt%, 3-7 wt%, preferably 5-7 wt%, more preferably about 4 wt% of the base asphalt, depending on the type of base asphalt, the degree of grafting reaction of the asphalt to be expected, i.e. the grafting ratio, the higher the grafting ratio, the more stable the product after emulsification. If the addition amount of the maleic anhydride is less than 1 wt%, the whole mechanical property of the polymer is reduced due to the lack of 'bridging' chemical bonds among the cured polymers, and 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. In another aspect, SBS is added in an amount of 3-15 wt% SBS, for example 3-6 wt%, 5-6 wt%, preferably about 9-11 wt% SBS, of the base asphalt. SBS is a non-polar substance, and asphalt is a weak polar substance, and the addition of SBS is too small, which can cause more sufficient esterification reaction between maleic anhydride and asphalt of the system, greatly reduce the polarity balance between the asphalt and the grafted SBS, improve the interaction force between SBS particles, reduce the deformation capability of SBS particles, and further reduce the low temperature resistance of the system to a certain extent. However, the excessive amount of SBS may not be sufficiently graft-polymerized with the maleic anhydride asphalt to be aggregated, so that phase separation may easily occur when the two are mixed, thereby causing SBS segregation.
The modified emulsified asphalt provided by the invention adopts raw material composition, proportion and processing technology different from those of the prior art, the obtained asphalt product solves the problem of compatibility of the emulsified asphalt and epoxy resin, has good stability, oxidation resistance and other properties, and simultaneously, the prepared macromolecular nonionic emulsifier overcomes the defect that an ionic emulsifier pollutes water quality, improves the bonding capability of the modified emulsified asphalt, remarkably improves the low temperature resistance of the modified emulsified asphalt, and obtains the effect of protecting ecological environment. In addition, the modified emulsified asphalt provided by the invention has the characteristics that the asphalt material is stirred and stirred at normal temperature to be quickly cured, and the cured asphalt material has high strength, high hardness and high ductility. The hardness of the modified emulsified asphalt is improved after curing, and excellent puncture resistance and shear failure resistance are endowed. Another advantage of the modified emulsified asphalt of the present invention is that the emulsified asphalt has high storage stability and storage stability of its mixture with aggregate, thereby improving adaptability to various construction methods.
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 viscosity was measured with a DV-79 digital viscometer manufactured by Shanghai precision instruments & instruments Ltd at a measurement temperature of 25 ℃.
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. Pouring the cementing material (the single-component waterborne epoxy/SBS composite modified emulsified asphalt before aging) into a steel mould of 300cm multiplied by 100cm multiplied by 2cm, forming an asphalt strip after the cementing material is dried, and measuring the tensile strength and the elongation at break of the asphalt strip.
Example 1
Preparing a soap solution:
heating 250 g of water to 60 ℃, adding 27.5g of polyethylene glycol (supplier, Shanghai Tatan science and technology, model 01050891), stirring to dissolve, sequentially adding 7.5g of IPDI (supplier, Shanghai Tatan science and technology, model 01072400),5.3g of 2, 2-dimethylolpropionic acid (supplier, Shanghai Moshu Biotech Co., Ltd., SY004305) and 0.1 g of di (dodecyl sulfur) diisooctyl tin, stirring and mixing at the rotating speed of 300r/min for 10min, and reacting at 60-80 ℃ for 4h to obtain an aqueous polyurethane solution with the viscosity of 3200mPa.s, namely a soap solution.
Example 2
Preparation of maleic anhydride/SBS modified asphalt:
250 g of No. 70 base asphalt is heated to 150 ℃, according to the formula shown in Table 1, maleic anhydride and 1 percent of cross-linking agent dibenzoyl peroxide (BPO) based on the weight of the maleic anhydride are mixed, then the mixture is added into the base asphalt, stirred and mixed, and the mixture reacts for 5 hours at 150 ℃ to obtain the cross-linking type maleic anhydride modified asphalt. And then adding SBS (the product of the Baling petrochemical company, model 791h) and a compatilizer (the product of the Datong plastic science and technology Limited, model DY-307) accounting for 1 percent of the weight of SBS into the maleic anhydride modified asphalt, and stirring and mixing for 5h at 150 ℃ to obtain the maleic anhydride/SBS modified asphalt.
TABLE 1 various maleic anhydride/SBS modified asphalts
Example 3
Preparing single-component waterborne epoxy/SBS composite modified emulsified asphalt:
100g of maleic anhydride/SBS modified asphalt obtained in experiment No. 5 in example 2 was added to 100g of the soap solution obtained in example 1, and shearing was performed at a rotation speed of 8500r/min for 15min to obtain an emulsion of maleic anhydride/SBS modified emulsified asphalt (emulsified asphalt for short).
Weighing E-618 epoxy resin (Shanghai resin factory Co., Ltd.) according to the formula weight in the table 2, shearing and uniformly mixing zinc hexacyanocobaltate and maleic anhydride/SBS modified emulsified asphalt at the rotating speed of 1500r/min for 15min, wherein the zinc hexacyanocobaltate and the maleic anhydride/SBS modified emulsified asphalt are 0.3 wt% of the weight of the epoxy resin, and obtaining the single-component waterborne epoxy/SBS composite modified emulsified asphalt.
TABLE 2 comparison of the Properties of various monocomponent waterborne epoxy/SBS composite modified emulsified asphalt products
Note: (1) the emulsified asphalt was the product of experiment number 3 in example 2.