Preparation method of modified lignin sulfonate asphalt emulsifier and product thereof

Abstract

The application discloses a preparation method of modified lignin sulfonate asphalt emulsifier, and application of products and the asphalt emulsifier. The emulsifier is prepared by the following steps: reacting an amine compound with acrylic acid to generate an amide compound, and then reacting the amide compound with sodium lignin sulfonate and formaldehyde in a solvent to generate the emulsifier. The molar ratio of the amine compound to the acrylic acid is 1:1, the amount of the sodium lignin sulfonate is 40% to 60% of the total mass of the amine compound and the acrylic acid, the amount of the formaldehyde is 14% to 26% of the mass of the sodium lignin sulfonate, and the mass ratio of the solvent to the reactants is (1 to 1.2):(1 to 1.2). The preparation method of the modified lignin sulfonate asphalt emulsifier is simple, the production cost is low, the water solubility is good, the surface activity is strong, the modified lignin sulfonate asphalt emulsifier belongs to a slow cracking type asphalt emulsifier, the emulsified asphalt produced by using the modified lignin sulfonate asphalt emulsifier is fine and uniform, the storage stability is excellent, and the modified lignin sulfonate asphalt emulsifier has a good application prospect in asphalt pavement construction.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of asphalt emulsifier and its product, in particular to a preparation method of modified lignin sulfonate asphalt emulsifier and its product and the application of asphalt emulsifier, belonging to the technical field of traffic material preparation. BACKGROUND

[0002] With the exhaustion of fossil resources and the increasing environmental pollution, more and more countries regard the development and utilization of renewable resources as an effective way to solve resource problems and reduce environmental pollution. Lignin is the only natural renewable resource containing aromatic ring in nature, and its reserves on earth are second only to cellulose. It can be converted into various industrial chemicals through modification, and has great application potential.

[0003] Lignin is a substance composed of aromatic alcohol polymer, which exists in woody tissue and mainly functions to harden cell walls by forming an interwoven network, being the main component of secondary wall. Lignin is mainly located between cellulose fibers, playing a supporting and compression-resistant role. In woody plants, lignin accounts for about 20% to 25%, being the second most abundant natural polymer in nature (cellulose is the first). Lignin is non-toxic and has excellent versatility in terms of performance, and has wide application in industry. In addition, lignin contains various groups in its structure, which can be easily modified by chemical reaction and used to produce various chemical materials, such as asphalt emulsifier, cement water reducer, etc. As a degradable and environmentally friendly material, lignin can well replace some non-degradable materials, and has great significance for environmental protection. Industrial lignin contains both hydrophilic and hydrophobic groups in its molecular structure, thus having good dispersion performance and certain emulsifying performance, and can be used as an emulsifier. However, due to its special molecular structure, industrial lignin has poor surface activity, and usually needs to be chemically modified to prepare emulsifiers with excellent performance.

[0004] Asphalt emulsifier is a kind of surfactant, which is a key material for producing emulsified asphalt. A small amount of asphalt emulsifier can greatly reduce the surface tension of the oil-water interface, and form a layer of emulsifier molecular film at the oil-water interface, thereby emulsifying asphalt, making the asphalt particles uniformly and stably dispersed in the soap solution, and making the asphalt have good fluidity at room temperature, facilitating the construction of asphalt at room temperature. Asphalt emulsifiers are divided into non-ionic asphalt emulsifiers, anionic asphalt emulsifiers, cationic asphalt emulsifiers and amphoteric asphalt emulsifiers according to whether the hydrophilic group is ionized and the charge carried by ionization.

[0005] Chinese patent CN104592530A reacts alkali lignin alkali aqueous solution with an appropriate amount of phenol to obtain phenolated lignin, and then reacts the phenolated lignin with polyamine and formaldehyde through Mannich reaction to finally obtain phenolated lignin amine cation emulsifier. Chinese patent CN105085933A activates lignin sodium sulfonate with saccharifying enzyme, and then uses pyridine as catalyst to react with 1-bromododecane to finally obtain alkylated lignin sodium sulfonate, and the surface tension of the product after reaction is greatly reduced. Chinese patent CN104974355A uses lignin sodium sulfonate, amine compounds and aldehydes to prepare amine group lignin sodium sulfonate through Mannich reaction in solution, which has significant pH response characteristics and can be applied to the field of pesticide microcapsule as wall material, and is also expected to be applied in the field of lignin-based nanomaterials. In the paper "Synthesis of sulfonated lignin-based chain transfer agent and its application in water phase RAFT polymerization", carbon disulfide and methyl bromoacetate are used to modify sulfonated lignin (SL) through xanthate ester functionalization, and sulfonated lignin-based chain transfer agent is synthesized, which is then used for water phase reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylamide to prepare sulfonated lignin-acrylamide copolymer. Chinese patent CN104311833A uses amine compounds, formaldehyde and lignin sodium sulfonate to react in solution to obtain lignin sulfonate type cold recycled asphalt emulsifier, and the prepared emulsifier has good emulsifying performance and the cold recycled asphalt emulsified mixture prepared therefrom has good road performance. Chinese patent CN101745340A relates to a preparation method of cationic asphalt emulsifier, wherein the main agent is obtained by reacting mixed organic acid and organic amine to obtain an intermediate, and then performing quaternary ammoniation reaction, and the auxiliary agent is nonionic surfactant and modified additive. The disadvantages of the method are that the preparation steps are complicated, the cost is high, and high-temperature reaction is required. Meanwhile, the preparation processes of the above-mentioned asphalt emulsifiers are complex and the cost is high, and there is no report on introducing amine group and amide bond at the same time to improve the emulsifying effect of modified lignin sodium sulfonate asphalt emulsifier. The applicant has confirmed through experiments that the introduction of amide group can produce intermolecular hydrogen bond between the modified lignin sodium sulfonate asphalt emulsifier, the mutual attraction of the intermolecular hydrogen bond greatly offsets the mutual repulsion of the head groups with the same charge, improves the adsorption density of the adsorption layer, improves the surface activity, reduces the critical surface tension, and thus better emulsifying effect can be obtained. It has very important practical application value to develop new modified lignin sulfonate asphalt emulsifier based on lignin as raw material, which has excellent performance and low cost. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application aims to provide a preparation method of modified lignin sulfonate asphalt emulsifier, products thereof and application of the asphalt emulsifier.

[0007] The preparation method of the modified lignin sulfonate asphalt emulsifier comprises the following steps:

[0008] (1) preparation of amide compound

[0009] Under the condition of N2, the acrylic acid is added into the four-necked flask, and then the amine compound solution is slowly added dropwise under stirring and heating to 110-130 DEG C, so that the amine compound and the acrylic acid are subjected to amidation reaction, and the amide compound is generated after 2-5 hours;

[0010] (2) preparation of modified lignin sulfonate asphalt emulsifier

[0011] The amide compound prepared in step (1) is added into the deionized water, and the lignin sulfonate is added at the same time, and the temperature is heated to 70-90 DEG C, wherein the added amount of the lignin sulfonate is 40%-60% of the total mass of the amine compound and the acrylic acid in step (1); then the formaldehyde is added, wherein the added amount of the formaldehyde is 14%-26% of the total mass of the lignin sulfonate, and the mass ratio of the solvent to the reactant is (1-1.2):(1-1.2); the formaldehyde, the lignin sulfonate and the amide compound are subjected to Mannich reaction, and finally the product is the modified lignin sulfonate asphalt emulsifier.

[0012] In the preparation method of the modified lignin sulfonate asphalt emulsifier, the amine compound is one or a combination of multiple kinds of amine compounds in any molar ratio, the lignin sulfonate is one of lignin sulfonate sodium and lignin sulfonate calcium, and the solvent is deionized water.

[0013] Further preferred embodiments are that the amine compound is triethylene tetramine, and the lignin sulfonate is lignin sulfonate sodium.

[0014] In the preparation method of the modified lignin sulfonate asphalt emulsifier, the added amount of the lignin sulfonate is preferably 50% of the total mass of the amine compound and the acrylic acid, the added amount of the formaldehyde is preferably 20% of the mass of the lignin sulfonate, and the mass ratio of the solvent to the reactant is preferably 1:1.

[0015] In the preparation method of the modified lignin sulfonate asphalt emulsifier, the temperature of the amidation reaction of the amine compound and the acrylic acid in step (1) is preferably 130 DEG C, and the temperature of the Mannich reaction in step (2) is preferably 80 DEG C.

[0016] Further, the preparation method of the modified lignin sulfonate asphalt emulsifier by using acrylic acid, triethylene tetramine, lignin sulfonate sodium and formaldehyde is as follows:

[0017] (1) preparation of triethylene tetramine-acrylic acid amide compound

[0018] Under the condition of N2, acrylic acid is added into a four-necked flask, and stirred and heated to 110-130℃, then triethylenetetramine solution is slowly added dropwise, and the molar ratio of triethylenetetramine to acrylic acid is 1:1 to carry out amidation reaction, and the amidation compound is generated after 2-5h; the reaction formula is as follows:

[0019]

[0020] (2) Preparation of modified sodium lignosulfonate asphalt emulsifier

[0021] The amidation compound prepared in step (1) is added into deionized water, and sodium lignosulfonate is added at the same time, and heated to 70-90℃, then formaldehyde is added, and the formaldehyde, sodium lignosulfonate and amide compound are reacted through Mannich reaction, and finally the modified sodium lignosulfonate asphalt emulsifier is obtained. The reaction formula is as follows:

[0022]

[0023] In the preparation method of the modified sodium lignosulfonate asphalt emulsifier, the temperature of the amidation reaction of triethylenetetramine and acrylic acid in step (1) is preferably 130℃; and the temperature of the Mannich reaction in step (2) is preferably 80℃.

[0024] The product prepared by the preparation method of the modified sodium lignosulfonate asphalt emulsifier.

[0025] The product is applied to prepare emulsified asphalt.

[0026] The application method is that the modified sodium lignosulfonate asphalt emulsifier is dissolved in water to prepare a soap solution, wherein the modified sodium lignosulfonate asphalt emulsifier accounts for 2.5-7.5wt.%, and water accounts for 92.5-97.5wt.% in the soap solution; then the soap solution is heated to 70-80℃, the pH value is adjusted to 10-12, and at the same time, the asphalt is heated to 130℃, then the soap solution and the asphalt are poured into a colloid mill for shearing for 2-5min to prepare the emulsified asphalt; wherein the asphalt accounts for 55-65wt.% in the emulsified asphalt component, the soap solution accounts for 35-45wt.%, and the modified sodium lignosulfonate asphalt emulsifier accounts for 1.0-3.0wt.% in the total amount of the emulsified asphalt component.

[0027] The preferred embodiment of the above application method is to dissolve the product modified lignin sulfonate asphalt emulsifier in water to prepare a soap solution, wherein the modified lignin sulfonate asphalt emulsifier accounts for 5 wt.% in the soap solution, and water accounts for 95 wt.%; then the soap solution is heated to 70 DEG C, the pH value is adjusted to 11, and at the same time, the asphalt is heated to 130 DEG C, then the soap solution and the asphalt are poured into a colloid mill for shearing for 3 minutes to prepare the emulsified asphalt; wherein the asphalt accounts for 60 wt.% in the emulsified asphalt component, the soap solution accounts for 40 wt.%; and the modified lignin sulfonate asphalt emulsifier accounts for 2.0 wt.% in the total amount of the emulsified asphalt component.

[0028] The outstanding advantages and beneficial effects of the present application are embodied in:

[0029] 1) The synthetic modified lignin sulfonate asphalt emulsifier has a two-step synthesis method, and can simply and efficiently synthesize the asphalt emulsifier with excellent performance.

[0030] 2) The present application does not directly use amine compounds, aldehydes and lignin sulfonate to directly undergo Mannich reaction, but first reacts the amine compounds with acrylic acid to generate acrylamide compounds, and then reacts with aldehyde substances and sodium lignin sulfonate to perform Mannich reaction. Experiments prove that introducing amine groups and amide bonds at the same time makes the modified sodium lignin sulfonate asphalt emulsifier have better emulsifying effect. The method of the present application creatively introduces amide groups, which can make the modified sodium lignin sulfonate asphalt emulsifier produce intermolecular hydrogen bonds. The mutual attraction of the intermolecular hydrogen bonds greatly offsets the mutual repulsion of the head groups with the same charge, improves the adsorption density of the adsorption layer, improves the surface activity, reduces the critical surface tension, and thus can obtain better emulsifying effect.

[0031] 3) The modified lignin sulfonate asphalt emulsifier synthesized by the method of the present application has good emulsifying capacity, and the emulsified asphalt has excellent high and low temperature performance and storage stability. The prepared emulsified asphalt meets the relevant requirements in the Technical Specification for Highway Asphalt Pavement Construction (JTG F40-2004), and has a good application prospect in the construction technology of slurry seal and micro-surfacing.

[0032] 4) The raw material lignin of the modified lignin sulfonate asphalt emulsifier is cheap and widely available, and the production cost of the asphalt emulsifier is low. The main raw material is lignin sulfonate modified from papermaking black liquor lignin, which can effectively reduce the environmental pollution of papermaking waste liquid and has significant social benefits. DETAILED DESCRIPTION

[0033] The application will be described in detail below with specific examples. The following examples are merely preferred embodiments of the application and are not intended to limit the application in any form. Any simple modification, equivalent change, and alteration, modification, replacement, combination, simplification made according to the technical essence of the application shall be equivalent replacement and shall be within the scope of the technical solution of the application.

[0034] The methods described in the embodiments of the application are all conventional methods unless otherwise specified. The materials and reagents used are all obtained from commercial channels unless otherwise specified.

[0035] Example 1

[0036] 1. Preparation of modified sodium lignosulfonate asphalt emulsifier

[0037] (1) Preparation of amide compound

[0038] Under the condition of nitrogen gas, 10.8 g of acrylic acid was added to a four-necked flask, and stirred to be heated to 130℃, then 21.9 g of triethylenetetramine solution was slowly added dropwise. The amide compound was generated after the amide reaction of triethylenetetramine and acrylic acid for 3 h.

[0039] (2) Preparation of modified sodium lignosulfonate asphalt emulsifier

[0040] The amide compound prepared in step (1) was added to 65.4 g of deionized water, and 32.7 g of sodium lignosulfonate was added at the same time, and then heated to 80℃. Then 17.6 g of formaldehyde solution with a concentration of 37% was added. The Mannich reaction of formaldehyde, sodium lignosulfonate and amide compound was carried out, and finally the product, modified sodium lignosulfonate asphalt emulsifier, was obtained.

[0041] 2. Preparation and performance test of emulsified asphalt

[0042] 20 g of the modified sodium lignosulfonate asphalt emulsifier prepared above was dissolved in water to prepare a soap solution. The soap solution was heated to 70℃, and 400 g of the soap solution was prepared (5 wt.% of the modified sodium lignosulfonate asphalt emulsifier and 95 wt.% of water), and the pH value was adjusted to 11. Then 600 g of 70# base asphalt was heated to 140℃, and finally the soap solution and the base asphalt were introduced into a colloid mill for shearing for 3 min to obtain the emulsified asphalt.

[0043] The asphalt in the emulsified asphalt accounts for 60 wt.%, and the soap solution accounts for 40 wt.%. The soap solution contains 2.0 wt.% of the modified sodium lignosulfonate asphalt emulsifier based on the total amount of the components of the emulsified asphalt.

[0044] The obtained emulsified asphalt was tested according to the test method of JTG E20-2011 Highway Engineering Asphalt and Asphalt Mixture Test Procedures, and the test results are shown in Table 1.

[0045] Example 2:

[0046] In this example, the modified lignin sulfonate asphalt emulsifier was prepared in the same manner as in Example 1, except that the amount of formaldehyde solution with a concentration of 37% used in step (1) was 12.37 g.

[0047] In this example, the emulsified asphalt was prepared and the performance of the emulsified asphalt was tested in the same manner as in Example 1, and the test results are shown in Table 1.

[0048] Example 3:

[0049] In this example, the modified lignin sulfonate asphalt emulsifier was prepared in the same manner as in Example 1, except that the amount of formaldehyde solution with a concentration of 37% used in step (1) was 22.97 g.

[0050] In this example, the emulsified asphalt was prepared and the performance of the emulsified asphalt was tested in the same manner as in Example 1, and the test results are shown in Table 1.

[0051] Example 4:

[0052] In this example, the modified lignin sulfonate asphalt emulsifier was prepared in the same manner as in Example 1, except that the amount of acrylic acid used in step (1) was 8.64 g, and the amount of triethylenetetramine used was 17.52 g.

[0053] In this example, the emulsified asphalt was prepared and the performance of the emulsified asphalt was tested in the same manner as in Example 1, and the test results are shown in Table 1.

[0054] Example 5:

[0055] In this example, the modified lignin sulfonate asphalt emulsifier was prepared in the same manner as in Example 1, except that the amount of acrylic acid used in step (1) was 12.96 g, and the amount of triethylenetetramine used was 26.28 g.

[0056] In this example, the emulsified asphalt was prepared and the performance of the emulsified asphalt was tested in the same manner as in Example 1, and the test results are shown in Table 1.

[0057] Example 6:

[0058] In this example, the modified lignin sulfonate asphalt emulsifier was prepared in the same manner as in Example 1, except that the reaction temperature of step (2) was changed to 70°C.

[0059] In this example, the emulsified asphalt was prepared and the performance of the emulsified asphalt was tested in the same manner as in Example 1, and the test results are shown in Table 1.

[0060] Example 7:

[0061] This example was prepared in the same manner as Example 1, except that the reaction temperature of step (2) was changed to 90°C.

[0062] This example was prepared in the same manner as Example 1, and the emulsified asphalt was tested for performance. The test results are shown in Table 1.

[0063] Comparative Example 1:

[0064] This comparative example used sodium lignosulfonate as the asphalt emulsifier, and the emulsified asphalt was prepared in the same manner as Example 1, and the emulsified asphalt was tested for performance. The test results are shown in Table 1.

[0065] Comparative Example 2:

[0066] In a three-necked flask, 14.6 g of triethylenetetramine, 30 g of sodium lignosulfonate, and 45 g of deionized water were added, stirred until completely dissolved, and heated to 80°C. Then, 16.21 g of a formaldehyde solution with a concentration of 37% was added dropwise to the above solution, and after the dropwise addition was completed, the solution was heated for 3 h to obtain a modified lignosulfonate asphalt emulsifier. The emulsified asphalt was prepared in the same manner as Example 1, and the emulsified asphalt was tested for performance. The test results are shown in Table 1.

[0067] Table 1: Test results of emulsified asphalt performance

[0068]

[0069] As can be seen from Table 1, the modified lignosulfonate asphalt emulsifier synthesized by the Mannich reaction has good low-temperature ductility and good solubility. The emulsifying effect of the modified lignosulfonate asphalt emulsifier in Examples 1-7 is better than that of the sodium lignosulfonate in Comparative Example 1.

[0070] The emulsifying effect of the modified lignosulfonate asphalt emulsifier in Examples 1-7 is also better than that of the modified sodium lignosulfonate asphalt emulsifier generated by the Mannich reaction of triethylenetetramine, sodium lignosulfonate, and formaldehyde in Comparative Example 2. This is because the amide bond can produce intermolecular hydrogen bonds. The interaction of hydrogen bonds increases the cohesive force of the molecules and the adsorption density of the adsorption layer, thereby reducing the critical micelle concentration cmc and the critical surface tension, and thus improving the emulsifying performance.

[0071] The emulsifier preparation method is simple, the production cost is low, the emulsifier product has good water solubility and strong surface activity, belongs to a slow cracking asphalt emulsifier, the emulsified asphalt produced by using the emulsifier is fine and uniform, has less influence on low-temperature performance of the emulsified asphalt, and each performance meets construction requirements, and has a good application prospect in thin slurry seal and micro-surfacing construction and the like.

Claims

1. A method for preparing a modified lignin sulfonate asphalt emulsifier, comprising the steps of: (1) preparing an amide compound by adding acrylic acid into a four-necked flask under N2, stirring and heating to 110-130℃, then slowly adding an amine compound solution at a molar ratio of 1:1 of the amine compound to the acrylic acid to allow the amine compound to react with the acrylic acid to form the amide compound after 2-5 hours; and (2) preparing the modified lignin sulfonate asphalt emulsifier by adding the amide compound prepared in step (1) into deionized water, adding lignin sulfonate and heating to 70-90℃, wherein the lignin sulfonate is added at a ratio of 40%-60% of the total mass of the amine compound and the acrylic acid in step (1), then adding formaldehyde at a ratio of 14%-26% of the total mass of the lignin sulfonate, and the mass ratio of the solvent to the reactants being (1-1.2):(1-1.2), so that the formaldehyde reacts with the lignin sulfonate and the amide compound through a Mannich reaction to obtain the modified lignin sulfonate asphalt emulsifier.

2. The method of claim 1, wherein the amine compound is triethylenetetramine, the lignin sulfonate is sodium lignin sulfonate, and the solvent is deionized water.

3. The method of claim 1, wherein the lignin sulfonate is added at a ratio of 50% of the total mass of the amine compound and the acrylic acid, the formaldehyde is added at a ratio of 20% of the mass of the lignin sulfonate, and the mass ratio of the solvent to the reactants is 1:

1.

4. The product prepared by the method of claim 1.

5. The use of the product of claim 4 in preparing an emulsified asphalt. wherein 6. The use of the product of claim 4 in preparing an emulsified asphalt, wherein the modified lignin sulfonate asphalt emulsifier is dissolved in water to prepare a soap solution, wherein the modified lignin sulfonate asphalt emulsifier accounts for 2.5-7.5 wt.% and water accounts for 92.5-97.5 wt.% in the soap solution, the soap solution is heated to 70-80℃ and adjusted to a pH of 10-12, and the asphalt is heated to 130℃, then the soap solution and the asphalt are poured into a colloid mill and sheared for 2-5 minutes to obtain the emulsified asphalt, wherein the asphalt accounts for 55-65 wt.% and the soap solution accounts for 35-45 wt.% in the emulsified asphalt, and the modified lignin sulfonate asphalt emulsifier accounts for 1.0-3.0 wt.% of the total amount of the emulsified asphalt.

2. The method for preparing modified lignin sulfonate bitumen emulsifier according to claim 1, characterized in that:

7. The use of the product of claim 4 in preparing an emulsified asphalt, wherein the modified lignin sulfonate asphalt emulsifier is dissolved in water to prepare a soap solution, wherein the modified lignin sulfonate asphalt emulsifier accounts for 5 wt.% and water accounts for 95 wt.% in the soap solution, the soap solution is heated to 70℃ and adjusted to a pH of 11, and the asphalt is heated to 130℃, then the soap solution and the asphalt are poured into a colloid mill and sheared for 3 minutes to obtain the emulsified asphalt, wherein the asphalt accounts for 60 wt.% and the soap solution accounts for 40 wt.% in the emulsified asphalt, and the modified lignin sulfonate asphalt emulsifier accounts for 2.0 wt.% of the total amount of the emulsified asphalt.

3. The method for preparing modified lignin sulfonate bitumen emulsifier according to claim 1, characterized in that: ​ ​ ​ 6. Use according to claim 5, characterized in that: ​ 7. Use according to claim 6, characterized in that: ​

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