Lignin flame retardant with toughening and antioxidant functions, preparation method and flame-retardant asphalt thereof

Abstract

The invention discloses a lignin flame retardant with toughening and antioxidant functions, flame-retardant elements such as F-GMA, N, P and Si are introduced into a lignin macromolecular structure, the flame-retardant elements are not easy to migrate and seep, the performance of the material is more stable, the dispersity is better, the flame-retardant property of asphalt can be improved by the introduced flame-retardant elements such as N, P and Si, and meanwhile, the flame-retardant property of the asphalt can be improved by the introduced flame-retardant elements such as N, P and Si. The grafted F-GMA enables the lignin to have a toughening function, and meanwhile, the lignin has rich phenolic hydroxyl groups, so that the lignin also has an antioxidant function. When the lignin-based flame retardant is applied to an asphalt material, the flame retardant property of a composite material can be remarkably improved, and an efficient synergistic flame retardant effect is achieved. And the method for preparing the lignin flame retardant is simple, and the process conditions are easy to control.

Description

Technical Field

[0001] The present invention relates to the modification treatment of lignin, and particularly relates to a lignin flame retardant with toughening and antioxidant functions, a preparation method thereof, and a flame retardant asphalt. Background Art

[0002] Industrial lignin mainly comes from the by-products of the pulp and paper industry. However, most lignin is used as low-value fuel for power generation, and only about 2% is used to develop high-value functional materials such as water reducers, adhesives, rubbers, and carbon fibers. The main reason for its limited application is that lignin has characteristics such as an amorphous chemical structure, low molecular weight, wide molecular weight distribution, and poor arrangement. Therefore, modification is carried out to overcome the complex inhomogeneous structure and inherent easy flocculation characteristics of lignin, so as to further realize the high-value and industrial application of lignin. Lignin is a molecular structure with various active groups, including phenolic hydroxyl groups, methoxy groups, alcoholic hydroxyl groups, carboxyl groups, and double bonds. By carrying out reactions such as halogenation, nitration, and silanization on it, hybrid elements such as chlorine, nitrogen, phosphorus, and silicon can be introduced into lignin. These elements can make up for the deficiencies of lignin alone as a charring agent in terms of flame retardant effect. When the hybrid elements form a coordination system with lignin, they will exert a synergistic flame retardant effect, thereby significantly improving the flame retardant efficiency of the composite material. However, in the prior art, although introducing flame retardant elements into lignin can improve the flame retardant effect, there is a risk of migration and exudation of flame retardant elements, and the thermal stability, chemical stability, and dispersibility of the material still need to be improved. Moreover, the modified lignin only has flame retardancy and has a single function.

[0003] Therefore, it is necessary to solve the problems of migration and exudation of flame retardant elements in modified lignin materials, improve the thermal stability, chemical stability, and dispersibility of the materials, and at the same time solve the problem of single functionality of the materials. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a lignin flame retardant with toughening and antioxidant functions, a preparation method thereof, and a flame retardant asphalt, to solve the problems of migration and exudation of flame retardant elements in modified lignin materials, improve the thermal stability, chemical stability, and dispersibility of the materials, and at the same time solve the problem of single functionality of the materials.

[0005] The lignin flame retardant with toughening and antioxidant functions of the present invention introduces a polymerized F-GMA structure and flame retardant elements into the macromolecular structure of lignin. The flame retardant elements are N, P, and Si, and the flame retardant elements are located on the same molecular chain;

[0006] Further, the chemical structural formula of the lignin flame retardant is:

[0007]

[0008] Further, the lignin is alkaline lignin;

[0009] Further, the raw materials of the lignin flame retardant include glycidyl methacrylate, furfurylamine, lignin, phenylphosphonic dichloride, and 1,3-bis(3-aminopropyl)tetramethyldisiloxane. By mass ratio, lignin:phenylphosphonic dichloride:1,3-bis(3-aminopropyl)tetramethyldisiloxane:glycidyl methacrylate:furfurylamine = 60:15:19:17.2:12.

[0010] Further, first, GMA and furfurylamine are reacted through a condensation reaction to generate F-GMA, and then the product generated by the condensation reaction is grafted onto lignin; then, P element is introduced onto lignin through a grafting reaction, and then N element and Si element are introduced through a polymerization reaction;

[0011] Further, phenylphosphonic dichloride reacts with the hydroxyl groups on the aromatic ring in lignin through a chemical reaction, thereby introducing phosphorus onto lignin, and the phenylphosphonic dichloride grafted onto lignin then undergoes a polymerization reaction with 1,3-bis(3-aminopropyl)tetramethyldisiloxane.

[0012] The present invention also discloses a preparation method of a lignin flame retardant with toughening and antioxidant functions, including the following steps:

[0013] S1, GMA and furfurylamine are uniformly mixed and then heated to react to obtain solid I. CaCl2 is uniformly dispersed in dimethyl sulfoxide to form mixture II, and then lignin is uniformly dispersed in mixture II, and solid I and H2O2 are added and reacted at room temperature;

[0014] S2, the product of S1 and triethylamine are uniformly dispersed in tetrahydrofuran to form mixture III, and then phenylphosphonic dichloride is dissolved in tetrahydrofuran and then added to mixture III, and then cooled to room temperature and reacted under ice bath conditions;

[0015] S3, 1,3-bis(3-aminopropyl)tetramethyldisiloxane is dispersed in tetrahydrofuran and then mixed with the product in step S2, and then triethylamine is added, heated and stirred, and then filtered, and the product is dried to obtain the lignin flame retardant.

[0016] Further, in step S2, the reaction temperature is 40°C; in step S3, the heating temperature is 70-90°C.

[0017] The present invention also discloses a flame retardant asphalt, including matrix asphalt and the lignin flame retardant with toughening and antioxidant functions as claimed in claim 1;

[0018] Further, the mass ratio of the matrix asphalt to the lignin flame retardant with toughening and antioxidant functions is 100:3-6.

[0019] Advantages of the present invention: The lignin flame retardant with toughening and antioxidant functions, its preparation method and the flame-retardant asphalt of the present invention introduce F-GMA, N, P and Si flame-retardant elements into the macromolecular structure of lignin. The flame-retardant elements are not easily migrated and exuded, the properties of the material are more stable and the dispersibility is better. The introduced flame-retardant elements such as N, P and Si can improve the flame-retardant performance of asphalt. At the same time, the grafted F-GMA endows lignin with a toughening function. Meanwhile, lignin itself has a rich content of phenolic hydroxyl groups, so lignin also has an antioxidant function. Applying the lignin-based flame retardant to asphalt materials can significantly improve the flame-retardant performance of the composite material and achieve an efficient synergistic flame-retardant effect. Moreover, the method for preparing the lignin flame retardant is simple and the process conditions are easy to control. Description of the Drawings

[0020] Figure 1 is a specific implementation diagram of step S1;

[0021] Figure 2 is a specific implementation diagram of step S2;

[0022] Figure 3 is a specific implementation diagram of step S3. Detailed Embodiments

[0023] For a better understanding of the present invention, the following embodiments further illustrate the present invention, but the content of the present invention is not limited to the following embodiments.

[0024] In the embodiments, the experimental methods used are all conventional methods unless otherwise specified, and the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0025] In this embodiment, the lignin flame retardant with toughening and antioxidant functions introduces a polymerized F-GMA structure and flame-retardant elements into the macromolecular structure of lignin. The flame-retardant elements are N, P and Si, and the flame-retardant elements are located on the same molecular chain; the chemical structural formula of the lignin flame retardant is:

[0026]

[0027] GMA is glycidyl methacrylate, and F-GMA is formed by the reaction of GMA. Grafting F-GMA onto lignin, the epoxy structure and the characteristics of its long chain of this group enable lignin to toughen asphalt. N, P, and Si are located on the macromolecular structure of lignin and on the same molecular chain, with stronger intermolecular forces and greater stability. The flame-retardant elements are not easily migrated and exuded in the macromolecular structure, and the thermal stability and chemical properties are more stable, and the dispersibility is better. This modifier has good flame-retardant and toughening properties. Its phenolic structure does not participate in the reaction and can further participate in the subsequent short-term aging reaction of asphalt, thereby improving the short-term aging resistance of asphalt; in addition, the addition of lignin will improve the mechanical properties of asphalt.

[0028] In this embodiment, the lignin is alkaline lignin; under the action of alkali, lignin undergoes a certain degree of alkaline hydrolysis, increasing its solubility and being extracted. After precipitation and separation, the obtained lignin is called alkali lignin. The combination of alkaline lignin and asphalt is better.

[0029] In this embodiment, the raw materials of the lignin flame retardant include glycidyl methacrylate, furfurylamine, lignin, phenylphosphonic dichloride, and 1,3-bis(3-aminopropyl)tetramethyldisiloxane according to a mass ratio, lignin:phenylphosphonic dichloride:1,3-bis(3-aminopropyl)tetramethyldisiloxane:glycidyl methacrylate:furfurylamine = 60:15:19:17.2:12. React GMA with furfurylamine through a condensation reaction to generate F-GMA, and then graft the product generated by the condensation reaction onto lignin; use phenylphosphonic dichloride to chemically react with the hydroxyl groups on the aromatic ring in lignin, thereby introducing phosphorus onto lignin. The phenylphosphonic dichloride grafted onto lignin undergoes a polymerization reaction with the subsequently added 1,3-bis(3-aminopropyl)tetramethyldisiloxane. In this way, N, P, and Si flame-retardant elements are introduced on the basis of lignin. These flame-retardant elements are not easily migrated and exuded in the macromolecular structure, with more stable performance and better dispersibility.

[0030] The preparation method of the lignin flame retardant with toughening and antioxidant functions in this embodiment includes the following steps:

[0031] S1, After uniformly mixing GMA and furfurylamine, heat up for reaction to obtain solid I. Disperse CaCl2 uniformly in dimethyl sulfoxide (DMSO) to form mixture II, then disperse lignin uniformly in mixture II, and add solid I and H2O2 to react at room temperature; the reaction formula is as follows:

[0032] S2, Uniformly disperse the product of S1 and triethylamine in tetrahydrofuran to form mixture III, then dissolve phenylphosphonic dichloride in tetrahydrofuran and add it to mixture III, and then cool to room temperature and react under ice bath conditions;

[0033] S3. Disperse 1,3-bis(3-aminopropyl)tetramethyldisiloxane in tetrahydrofuran, mix it with the product in step S2, then add triethylamine, stir with heating and filter, and dry the product to obtain the lignin flame retardant.

[0034] The specific reaction formula is as follows:

[0035]

[0036]

[0037] In step S2, the preferred heating temperature is 40°C; in step S3, the heating temperature is 70 - 90°C.

[0038] This example also discloses a flame-retardant asphalt, which includes matrix asphalt and a lignin flame retardant with toughening and antioxidant functions; the mass ratio of the matrix asphalt to the lignin flame retardant with toughening and antioxidant functions is 100:3 - 6, preferably 100:6. This lignin flame retardant has good flame retardancy and toughening properties. Its phenolic structure does not participate in the reaction and can further participate in the subsequent short-term aging reaction of asphalt, thereby improving the short-term aging resistance of asphalt. In addition, the addition of lignin will improve the mechanical properties of asphalt.

[0039] Example 1

[0040] Prepare the lignin flame retardant. Step (1): Synthesize F-GMA: 17.2 g of GMA (120 mmol) and 12 g (120 mmol) of furfurylamine are stirred at a stirring speed of 400 rpm, gradually heated to 150°C for reaction, and discharged after 12 h to obtain the product F-GMA.

[0041] Step (2): Graft F-GMA: Add CaCl2 (12.2 g of solid, purity 97%) to a 500 mL round flask containing 250 mL of DMSO (dimethyl sulfoxide) solution, and stir magnetically until completely dissolved. Then, add 60 g of lignin to the solution. After the lignin is completely dissolved, gradually add 24 mmol of F-GMA 17 g and 77.4 nmol of 30% H2O2, and stir magnetically at 40°C for 24 h.

[0042] Step (3): Graft phenylphosphonic dichloride: Add the lignin and TEA (triethylamine) (10 ml, relative molecular mass 101.19, boiling point 90°C, slightly soluble in water) produced in step (2) and disperse them evenly in 100 ml of THF (tetrahydrofuran) in a three-necked flask. Then dissolve phenylphosphonic dichloride (15.0 g, 77 mmol) in 50 ml of THF and drip it into the flask within 1 hour. Cool to room temperature, and then stir in an ice bath equipped with a mechanical stirrer for eight hours.

[0043] Step (4): Mix 100 ml of THF, 1,3-bis(3-aminopropyl)tetramethyldisiloxane (20 g, 77 mmol) and the just-obtained product. Stir the mixture with 100 mmol of triethylamine (10.1 g), then gradually heat the substance to 80 °C and stir for 12 h. Filter the obtained product, wash it with ethanol 3 - 5 times, and dry it at room temperature. The final product is formed.

[0044] Example 2

[0045] Through the infrared spectrum test of the modified lignin, the results show that a new characteristic absorption peak of P-N-C appears at 760 cm -1 , a stretching vibration peak of P-N appears at 880 cm -1 , an asymmetric stretching vibration peak of Si-O-C appears at 1040 cm -1 , a stretching vibration peak of Si-O-Si appears at 1100 cm -1 , an absorption peak of P=O appears at 1240 cm -1 ; in addition, sharp peaks appear near 1630 cm -1 and 3430 cm -1 , which may be caused by the overlapping of the deformation vibration absorption peak and stretching vibration absorption peak of N-H bonds with the original lignin peaks. Thus, it is proved that the lignin-based flame retardant is successfully prepared.

[0046] Example 3

[0047] Use the lignin flame retardant prepared in Example 1 to prepare flame-retardant asphalt, and prepare it in the following two ways:

[0048] 1. Place 300 g of matrix asphalt in an oven at 165 °C to soften for 2 h. After softening, put it into a high-speed shearer with 18 g of lignin flame retardant (fiber) and keep the temperature at 160 °C for shearing. Shear at a rate of 2000 r / min for 10 minutes, and then accelerate to 4000 r / min and shear for 20 min. The lignin-based modified asphalt with an addition amount of 6% is prepared.

[0049] 2. Soften and shear the matrix asphalt alone.

[0050] Compare the properties of the asphalt obtained by the above two methods, and the results are as follows:

[0051] Softening point Ductility Penetration Base asphalt 48 1500+ 62.1 Lignin-based modified asphalt 51.2 1000+ 58

[0052] The results show that the softening point of the modified asphalt increases by about 6%, the ductility decreases by about 30%, but still meets the requirements, and the penetration decreases by about 6% and still meets the requirements.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A lignin flame retardant with toughening and antioxidant functions, characterized in that: Introduce a polymerized F-GMA structure and flame retardant elements onto the macromolecular structure of lignin. The flame retardant elements are N, P, and Si, and the flame retardant elements are located on the same molecular chain.

2. The lignin flame retardant with toughening and antioxidant functions according to claim 1, characterized in that: The chemical structural formula of the lignin flame retardant is:

3. The lignin flame retardant with toughening and antioxidant functions according to claim 1, characterized in that: The lignin is alkaline lignin.

4. The lignin flame retardant with toughening and antioxidant functions according to claim 1, characterized in that: The raw materials of the lignin flame retardant include glycidyl methacrylate, furfurylamine, lignin, phenylphosphonic dichloride, 1,3-bis(3-aminopropyl)tetramethyldisiloxane; by mass ratio, lignin:phenylphosphonic dichloride:1,3-bis(3-aminopropyl)tetramethyldisiloxane:glycidyl methacrylate:furfurylamine = 60:15:19:17.2:

12.

5. The preparation method of the lignin flame retardant with toughening and antioxidant functions according to claim 1, characterized in that: First, introduce a polymerized F-GMA structure onto lignin through a grafting reaction, then introduce P element onto lignin through a grafting reaction, and finally introduce N element and Si element through a polymerization reaction.

6. The preparation method of the lignin flame retardant with toughening and antioxidant functions according to claim 4, characterized in that: Utilize the condensation reaction between GMA and furfurylamine, and then graft the product after the condensation reaction onto lignin. Utilize the chemical reaction between phenylphosphonic dichloride and the hydroxyl group on the aromatic ring in lignin to introduce phosphorus onto lignin. The phenylphosphonic dichloride grafted onto lignin then undergoes a polymerization reaction with 1,3-bis(3-aminopropyl)tetramethyldisiloxane.

7. The preparation method of the lignin flame retardant with toughening and antioxidant functions according to claim 6, characterized in that: It includes the following steps: S1, After GMA and furfurylamine are uniformly mixed, heat up for reaction to obtain solid I. Disperse Cacl2 uniformly in dimethyl sulfoxide to form mixture II, then disperse lignin uniformly in mixture II, and add solid I and H2O2 to react at room temperature; S2, Uniformly disperse the product of S1 and triethylamine in tetrahydrofuran to form mixture III. Then dissolve phenylphosphonic dichloride in tetrahydrofuran and add it to mixture III, and then cool to room temperature and react under ice bath conditions; S3, Disperse 1,3-bis(3-aminopropyl)tetramethyldisiloxane in tetrahydrofuran and mix it with the product in step S2, then add triethylamine, heat and stir, then filter, and dry the product to obtain the lignin flame retardant.

8. The preparation method of the lignin flame retardant with toughening and antioxidant functions according to claim 1, characterized in that: In step S2, the reaction temperature is 40°C. In step S3, the heating temperature is 70 - 90°C.

9. A flame-retardant asphalt, characterized in that: It includes matrix asphalt and the lignin flame retardant with toughening and antioxidant functions described in claim 1.

10. The flame-retardant asphalt according to claim 9, characterized in that: The mass ratio of the matrix asphalt to the lignin flame retardant with toughening and antioxidant functions is 100:3 - 6.

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