Method for immobilizing ionized amidoxime on polyamide-based fiber surface

Abstract

The invention provides a method for immobilizing ionized amidoxime on the surface of polyamide-based fiber, which is realized by the following steps of: (1) in a solvent, utilizing the acidity of an amide unit N-H in a polyamide chain structure and under the catalytic action of an alkali reagent, carrying out ring-opening reaction on the amide unit N-H and glycidyl-containing unsaturated quaternary ammonium salt to obtain a polyamide-based fiber; unsaturated quaternary ammonium cationization of polyamide is realized; and (2) copolymerizing and grafting the unsaturated quaternary ammonium cationized polyamide with a cyano-containing diallylammonium cationic monomer, a cyano-containing diallylammonium zwitterionic monomer and a multi-cyano-containing bis (diallylammonium) salt to realize grafting of a cyano-containing ionomer on the surface of the polyamide. Cross-linking of a polyamide chain structure and surface coating of the polyamide-based fiber are formed; and (3) grafting the cyano-containing ionomer on the surface of the polyamide-based fiber, and then carrying out amidoximation reaction to prepare the polyamide-based fiber with the surface grafted with amidoxime, quaternary ammonium cations, amido, carboxyl betaine or sulphobetaine, which is used for enrichment, extraction and separation of uranyl ions in a seawater system.

Description

Technical Field

[0001] The present invention relates to a method for preparing polyamide-based functional fibers, and particularly to a method for immobilizing amidoxime, quaternary ammonium cation, amino group, carboxybetaine, or sulfobetaine on the surface of polyamide-based fibers, belonging to the field of functional materials. Technical Background

[0002] For more than half a century, many developed marine countries have conducted comprehensive research and development on topics such as the uranium distribution state in seawater, the scientific principles of uranium extraction from seawater, uranium extraction technologies and methods from seawater, materials required for uranium extraction from seawater, uranium extraction engineering, uranium extraction safety, uranium extraction environment, and uranium extraction benefits, and significant progress has been made. Among them, the key to uranium extraction from seawater is the selection and combination of the substrate of the uranium extraction material from seawater and the uranium-adsorbing ligand. The requirements for the substrate are high toughness and durability; the ligand has high selectivity for uranium adsorption and a large uranium adsorption capacity; the preparation method of the uranium extraction material from seawater is simple, convenient for fixed-position use and recycling, energy-saving and environmentally friendly for elution and recycling, and has high economic benefits. Theoretical research and experiments over the years have shown that the combination of "polymer silk fabric + chelating uranium-adsorbing ligand" is the preferred design and preparation scheme for uranium extraction materials from seawater. The earliest selected combination of "polymer silk fabric + chelating uranium-adsorbing ligand" was directly the amidoximation of polyacrylonitrile fibers. However, there are several insurmountable defects in the amidoximation of polyacrylonitrile fibers. ① In order to improve the adsorption capacity of amidoximated polyacrylonitrile fibers, it is hoped that the cyano groups on the surface of polyacrylonitrile fibers can be amidoximated as much as possible. However, the mechanical properties of overly amidoximated polyacrylonitrile fibers are relatively poor; ② The amidoxime groups contained in amidoximated polyacrylonitrile fibers have little freedom in three-dimensional space, and it is very difficult to form a stable geometric complex with uranyl cations or uranyl carbonate anions in a ratio of 2:1 or 4:1, and it is easily competed by Fe 3+ , Ni 2+ , Zn 2+ , Cu 2+ or VO 2+ etc. in seawater; ③ The hydrophilicity of amidoximated polyacrylonitrile fibers is not high, and the complexation adsorption with uranyl ions in seawater is slow, and it takes about 30 to 50 days to reach saturated adsorption; ④ After the amidoximated polyacrylonitrile fibers are immersed in seawater, they are adhered or wrapped by marine microorganisms in a short time, and lose the function of adsorbing uranyl ions.

[0003] In order to find uranium extraction materials and production technology processes that meet the conditions of good adsorption selectivity for uranyl cations or uranyl carbonate anions, fast adsorption rate, large saturated adsorption capacity, high hydrophilicity, large specific surface area in contact with seawater, high mechanical strength, high chemical stability, resistance to adhesion of microorganisms in seawater, simple adsorption-desorption process, low recycling cost, durability, easy placement in open seawater, easy recovery and elution, and high operation efficiency, people have been making unremitting efforts. The comprehensive research results of scholars from many countries such as Japan, the United States, and China show that: grafting acrylonitrile and subsequent amidoximation on the surface of fibers or non-woven fabrics based on polymer materials such as polyethylene, polypropylene, or polystyrene is a satisfactory combination of "polymer fabric + chelating uranium adsorption ligand". First, synthetic polymer substrates such as polyethylene, polypropylene, or polystyrene have a large output, wide sources, low prices, high chemical stability, and surface grafting has little impact on their own mechanical properties; second, non-woven fabrics have a high porosity and large specific surface area, and it is simple to perform processes such as hot pressing, shearing, curling, folding, kneading, and weaving on them, and they are suitable for being placed in open oceans at various depths in the form of mesh, rope, branches, kelp, or seaweed to filter seawater. However, although the high-energy radiation grafting method without using chemical reagents is clean and environmentally friendly, through the improved process of pre-radiation and post-grafting, the homopolymerization problem of acrylonitrile and unsaturated functional monomers has not been completely solved; there are also limitations in the radiation grafting of m 2 -level large-area substrates and continuous production processes.

[0004] Professionals have noticed that the amount of amidoxime immobilized on existing uranium extraction materials from seawater is huge, but the actual uranium adsorption utilization rate in seawater is very low. Many studies have shown that to improve the uranium adsorption efficiency of uranium extraction materials with immobilized amidoxime, in addition to grafting acrylonitrile for amidoximation, functional monomers containing ligands are also selected, including: ① copolymerizing and grafting acrylic acid, itaconic acid, unsaturated phosphoric acid / unsaturated phosphonic acid, unsaturated sulfobetaine, unsaturated phosphorylcholine, or unsaturated carboxybetaine, etc. with acrylonitrile. These functional groups can enhance the selective complexation of amidoxime with uranyl cations or uranyl carbonate anions; ② unsaturated quaternary ammonium salts or unsaturated phosphorylcholine types, which can not only significantly improve the surface hydrophilicity of these polymer materials, achieve a wetting contact between seawater and uranium extraction materials, but also attract uranyl carbonate anions to aggregate towards the material through the electrostatic attraction of the positive charges they carry, realizing the ion exchange aggregation and rapidization between the material and seawater, and can also enhance the resistance of uranium extraction materials to the attachment and growth of marine microorganisms on their surfaces; ③ grafting organic polyamines on the surface of fibers or non-woven fabrics, which can improve the hydrophilicity and uranium adsorption capacity of the material. In view of this, how to create an all-round uranium extraction fiber from seawater and a simple and effective preparation method based on existing research results should be the key to improving the comprehensive benefits of uranium extraction from seawater today. Summary of the Invention

[0005] The research group of the present invention once used fibers as the substrate, impregnated and coated them with glycidyl acrylate, and then carried out ring-opening reactions of organic polyamines and glycidyl groups, quaternization reactions of 5-chloromethyl salicylaldehyde, and oximation reactions of hydroxylamine hydrochloride to prepare a series of chelating ion exchange fibers with quaternary ammonium cations, amidoxime, and salicylaldoxime functional groups supported on the side chains. These fibers can be used as uranium extraction materials from seawater with the characteristics of anti-marine biofouling. See CN102500432B, CN102505480B, CN102631954B, and CN102516425B. However, in the application tests, it was successively found that the chelating ion exchange fibers with quaternary ammonium cations, amidoxime, and salicylaldoxime functional groups supported on the side chains had poor persistence of ion exchange function in simulated seawater and low adsorption selectivity for heavy metal ions. After investigation, it was found that the ester bonds in the structure of the series of chelating ion exchange fibers were continuously hydrolyzed in weakly alkaline seawater, resulting in the loss of the bonded functional groups and low adsorption stability for heavy metal ions. At the same time, the chelating ion exchange fibers had too high a water swelling rate.

[0006] In recent years, the materials for uranium extraction from seawater that have been highly regarded are polyethylene or polypropylene fibers and their non-woven fabrics as the substrate, which are surface-grafted with acrylonitrile and unsaturated functional monomers through ultraviolet irradiation, γ-radiation, or plasma. However, it has also been found that although the high-energy radiation grafting method without using chemical reagents is clean and environmentally friendly, and the improved process of pre-radiation and post-grafting has been adopted, the problem of homopolymerization of acrylonitrile and unsaturated functional monomers has not been completely solved. Moreover, the continuous production process of radiation grafting for substrates with an area of m 2 level is limited.

[0007] All along, amidoxime has been considered the most effective chelating ligand for uranyl ions. Therefore, people have focused on grafting as much acrylonitrile or functional ligands as possible on the substrate surface (some reports show that the acrylonitrile grafting rate is as high as over 500%), while ignoring the fixing effect of the substrate and the pulling effect of the polyacrylonitrile polymer chain. As a result, the freedom of the two adjacent amidoximes converted from acrylonitrile grafted on the substrate surface in geometric space is small, which is not suitable for the coordination complexation of 2:1 or 4:1 with uranyl ions. Many research results have reported the fact that the utilization rate of acrylonitrile grafted and amidoximated chelating adsorption of uranyl ions on the substrate surface is very low. The present inventor believes that increasing the freedom of the two adjacent amidoximes on the substrate surface is beneficial to the "self-assembly" type of stable coordination complexation of amidoxime with uranyl ions in a ratio of 2:1 or 4:1. At the same time, relying on the electrostatic attraction of the charges carried on the substrate surface for uranyl ions, the substrate can actively collect extremely low-concentration uranyl ions from the vast seawater in a "wide net casting" manner on the substrate surface, thus generating the "self-assembly" type of stable coordination complexation of amidoxime with uranyl ions in a ratio of 2:1 or 4:1. Thus, the present inventor has created a preparation technology and scheme for a multifunctional material for uranium extraction from seawater with "wide net casting + self-assembly".

[0008] On the basis of summarizing the existing work, through experimental research, the present inventor found that the unsaturated quaternization of the amide unit N atom in the polyamide chain structure, the graft copolymerization with a cyanide-containing diallylammonium-type ionic monomer and a polycyano bis(diallylammonium) crosslinking agent in an aqueous medium, and the subsequent amidoximation of the cyano group are a method for preparing multifunctional fibers for uranium extraction from seawater with a simple technical solution, wide adaptability, continuous preparation process, excellent functions and properties. The polymer chemistry principle of the polyamide-based fiber surface immobilized with ionized amidoxime in the present invention is as follows: ① In a solvent, using the acidic N-H of the amide unit in the polyamide chain structure, under the catalytic action of an alkali reagent, an epoxy ring-opening reaction with an unsaturated quaternary ammonium salt containing a glycidyl group is carried out to achieve the unsaturated quaternary cationization of the polyamide fiber surface; ② The copolymerization grafting of the unsaturated quaternary cationized polyamide with a cyanide-containing diallylammonium-type cationic monomer, a cyanide-containing diallylammonium-type zwitterionic monomer, and a polycyano bis(diallylammonium) salt realizes the grafting and crosslinking of the cyanide-containing ionomer to the polyamide chain structure, as well as the surface bonding coating of the polyamide fiber; ③ After the polyamide fiber surface is grafted with an ionomer containing a cyano group, an amidoximation reaction is carried out to prepare the polyamide-based fiber with surface-immobilized amidoxime, amino group, carboxybetaine, or sulfobetaine, which is used for the enrichment, extraction and separation of uranyl ions in an aqueous system. From the above simple principle introduction, professionals can already understand that the present invention only through three-step preparation operations, realizes the introduction of amidoxime, quaternary cation, amino group, carboxybetaine, or sulfobetaine on the polyamide-based fiber surface, while endowing the polyamide surface with hydrophilic, antibacterial, and antifouling functions, and various modification effects of the crosslinking of ionized polyamidoxime to the polyamide chain structure and the surface bonding coating of the polyamide-based fiber. ④ Although the heat resistance of polyamide fiber is not as good as that of polyester, its moisture absorption is greater than that of polyester, and its initial modulus is 2-3 times lower than that of polyester, but it has a small specific gravity, high resilience, resistance to light radiation, and long-lasting resistance to aging. The impact wear resistance and abrasion resistance of polyamide fiber at high elongation are also the best among all fibers.

[0009] The method for immobilizing ionized amidoxime on the surface of a polyamide-based fiber described in the present invention is achieved through the following steps: Step 1, Preparation of unsaturated quaternary cationized polyamide-based fiber

[0010] Weigh the solvent in a reaction kettle at room temperature. While stirring, add the washed polyamide-based fiber into the reaction kettle. Slowly add the alkali reagent under N2 protection. After impregnating evenly, raise the temperature of the materials in the reaction kettle to 40-90 °C, and then gradually add the unsaturated quaternary ammonium salt containing a glycidyl group. Keep the temperature for 0.5-5 hours for the ring-opening reaction. Use an appropriate amount of acetic acid aqueous solution with a mass percentage concentration of 30-80% to neutralize the materials in the reaction kettle. End the reaction, filter out the polyamide-based fiber, wash it with water and dry it to obtain the unsaturated quaternary cationized polyamide-based fiber.

[0011] The dosage of the glycidyl-containing unsaturated quaternary ammonium salt is 0.5 to 50% of the number of moles of N-H of the amide structural units contained in the polyamide-based fiber, the dosage of the base reagent is 0.2 to 12% of the mass of the glycidyl-containing unsaturated quaternary ammonium salt, and the dosage of the solvent is 2 to 20 times the mass of the polyamide-based fiber.

[0012] Reaction formula -1 schematically shows the preparation method of the unsaturated quaternary ammonium cationized polyamide-based fiber:

[0013]

[0014] wherein R1 in Reaction formula -1 is selected from C1-C 18 hydrocarbon group.

[0015] The polyamide-based fiber refers to crosslinked or non-crosslinked polyamide fiber, or crosslinked or non-crosslinked polyamide composite fiber.

[0016] Among them, the crosslinked or non-crosslinked polyamide composite fiber refers to a composite fiber spun from crosslinked or non-crosslinked polyamide and a polymer as raw materials, or a composite fiber blended from crosslinked or non-crosslinked polyamide fiber, synthetic fiber, or plant fiber as raw materials.

[0017] Among them, the polymer refers to one or more of polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyethylene terephthalate, polyurethane, polyvinyl acetal, polyphenylene ether, polyether ketone, polyether sulfone, polyether ether sulfone, or polyether ether ketone; the synthetic fiber refers to one or more of polyethylene fiber, polypropylene fiber, polystyrene fiber, polyacrylonitrile fiber, polyester fiber, polyurethane fiber, or polyvinyl acetal fiber.

[0018] The plant fiber refers to one of cotton fiber, hemp fiber, or regenerated cellulose fiber.

[0019] The base reagent refers to one of sodium hydride, potassium hydride, sodium tert-butoxide, potassium tert-butoxide, lithium N,N-diisopropylamide, butyllithium, sodium phenyl, or sodium naphthyl.

[0020] The glycidyl-containing unsaturated quaternary ammonium salt has the structure shown in general formula (I):

[0021]

[0022] wherein R1 in general formula (I) is selected from C1-C 18 hydrocarbon group.

[0023] The solvent is selected from one or more of tetrahydrofuran, 1,4-dioxane, benzene, toluene, xylene, pentane, n-hexane, heptane, cyclohexane, decalin, petroleum ether with a boiling range of 60-90°C, or dimethyl sulfoxide.

[0024] As is well known to those skilled in the art, the unsaturated quaternary ammonium cationized polyamide-based fiber of the present invention has grafting-from characteristics. However, the degree of unsaturated quaternary ammonium cationization on the surface of the polyamide-based fiber should be controlled within an appropriate range: if the degree of unsaturated quaternary ammonium cationization is too low, the subsequent copolymer grafting rate is not high, and the crosslinking of the polyamide chain structure by the ionomer containing a cyano group and the surface coating efficiency of the polyamide-based fiber are also not high. Subsequently, the immobilization amidoximation efficiency is also not high, which will affect the function and benefit of the polyamide-based fiber immobilized with ionized amidoxime. However, the degree of unsaturated quaternary ammonium cationization should not be too high. First, because polyamide is a type of polar crystalline polymer material, there are H-bonds between its polymer chains. If the unsaturated quaternary ammonium cationization penetrates too deeply into the inner layer of the polyamide-based fiber, it will inevitably cause the destruction of H-bonds between the polyamide polymer chains, and the crystalline material will transform into an amorphous material, which will seriously affect the mechanical properties of the polyamide-based fiber. In order to perform unsaturated quaternary ammonium cationization only on the surface of the polyamide-based fiber as much as possible, the amount of the unsaturated quaternary ammonium salt containing a glycidyl group should be controlled, a non-polar solvent should be used, and the ring-opening reaction temperature should be appropriately reduced, etc. This is determined by the high ring-opening reaction efficiency between the amide N - negative ion and the glycidyl group and the fact that it belongs to a strongly exothermic reaction. In addition, the ring-opening reaction between the polyamide-based fiber and the unsaturated quaternary ammonium salt containing a glycidyl group also mainly occurs on the outer surface layer of the polyamide-based fiber, which is determined by the ring-opening reaction mechanism of the polyamide-based fiber and the unsaturated quaternary ammonium salt containing a glycidyl group catalyzed by an alkaline reagent.

[0025] Another important significance of performing unsaturated quaternary ammonium cationization on the polyamide-based fiber of the present invention is to endow the surface of the polyamide-based fiber with hydrophilicity, antibacterial and antifouling functions. As is well known to those skilled in the art, the quaternary ammonium cation not only has strong hydrophilicity, but also when R1 is selected from benzyl, heptyl, octyl, dodecyl or tetradecyl, the quaternary ammonium cation also has strong antibacterial activity, which is an important function to prevent microorganisms in water from adhering or growing on the surface of the polyamide-based fiber, and it is also an important function and characteristic for uranium extraction materials from seawater.

[0026] Step 2: Grafting an ionomer containing a cyano group on the surface of the polyamide-based fiber

[0027] Spray, roll coat, or brush coat the graft copolymerization solution on the surface of the unsaturated quaternary ammonium cationized polyamide-based fiber prepared in Step 1, or immerse the unsaturated quaternary ammonium cationized polyamide-based fiber prepared in Step 1 in the graft copolymerization solution. Take out the polyamide-based fiber that has been evenly dipped or evenly coated with the graft copolymerization solution and feed it into a polymerization reactor. After purging with nitrogen to remove oxygen for 30 minutes, control the temperature at 50-90°C and carry out the oscillating polymerization reaction for 4-12 hours. Take out the polyamide-based fiber from the polymerization reactor, and after shaping, cooling, washing with water, and drying, obtain the polyamide-based fiber with a surface grafted with a cyanide group-containing ionomer.

[0028] The dosage of the graft copolymerization solution is 0.2-20 times the mass of the unsaturated quaternary ammonium cationized polyamide-based fiber. Reaction formula -2 schematically shows the preparation method and process of the polyamide-based fiber with a surface grafted with a cyanide group-containing ionomer:

[0029]

[0030] Among them, R1 in Reaction formula -2 is selected from C1-C 18 hydrocarbon group. When Y is selected from C1-C 18 hydrocarbon group, X - is selected as Cl - , Br - or I - ; when Y is selected as -CH2CH2CO2 - , -CH2CH2CH2CO2 - , or -CH2CH2CH2SO3 - , X - does not select any one of the negative ions.

[0031] The graft copolymerization solution refers to a solution prepared by mixing a cyanide group-containing diallylammonium-type ionic monomer, a polycyanide group-containing bis(diallylammonium) salt crosslinking agent, and an aqueous initiator in deionized water according to a mass ratio of 1:0.1-5:0.03-0.13:1-10;

[0032] Among them, the cyanide group-containing diallylammonium-type ionic monomer has the structure shown in the general formula (II):

[0033]

[0034] Among them, when Y in the general formula (II) is selected from C1-C 18 hydrocarbon group, X - is selected as Cl - , Br - or I - ; when Y is selected as -CH2CH2CO2 - , -CH2CH2CH2CO2 - , or -CH2CH2CH2SO3- When X - does not select any kind of negative ions.

[0035] The polycyano bis(diallylammonium) salt crosslinking agent has the structure shown in general formula (Ⅲ):

[0036]

[0037] Among them, X in general formula (Ⅲ) - selects Cl - 、Br - or I - one of them, selects C1-C 18 alkylene or where n is selected from natural numbers between 0 and 200.

[0038] The aqueous initiator refers to one or more of hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, azodiisobutylamidine hydrochloride, azodiisobutimidazoline hydrochloride, sodium azodicyanovalerate, or azodiisopropylimidazoline hydrochloride.

[0039] It is well-known to professionals that dimethyldiallylammonium chloride is a commonly used cationic monomer, and its homopolymers, copolymers, and graft polymers are widely used in water treatment, daily chemical industry, oil extraction, and paper industry, etc. In order to create more diallylammonium chloride-based cationic monomers, people have replaced the dimethyl group with other hydrocarbon groups (such as butyl, hexyl, octyl, decyl, dodecyl, benzyl, etc.) or substituted hydrocarbon groups (such as carbonyloxyalkyl groups). The purpose is to meet different application scenarios, expand properties and functions; at the same time, the copolymerization of related diallylammonium chloride with monomers such as allylamine hydrochloride, diallylamine hydrochloride, acrylamide, acrylic acid, methacryloyloxyethylammonium chloride, vinylbenzenesulfonic acid, and vinylphosphoric acid has been clear. Therefore, on the basis of the previous work of CN201110322472.5, CN201110322503.7, CN201110304602.2, and CN201110304603.7, the inventor, according to the chemical principle of molecular design, based on the purpose and technical requirements of grafting acrylonitrile and functional monomers on the surface of uranium extraction materials from seawater, disclosed cyano-containing diallylammonium ionic monomers, cyano-containing diallylammonium zwitterionic monomers, and polycyano bis(diallylammonium) salt crosslinking agents in CN202311221445.8 for surface grafting modification of polymer materials to prepare seawater uranium extraction multifunctional materials with excellent performance and comprehensive functions.

[0040] Step 3: Preparation of polyamide-based fibers with surface-immobilized ionized amidoxime

[0041] Hydroxylamine salt is added to deionized water. After stirring and dissolving, the pH value is adjusted to 6.0 - 7.5 with an appropriate amount of base to obtain an aqueous hydroxylamine solution. Then, the polyamide-based fiber with a surface-grafted cyanide-containing ionomer prepared in Step 2 is immersed in the aqueous hydroxylamine solution, the temperature is controlled at 60 - 80 °C, and the reaction is carried out with oscillation for 10 - 12 hours. After cooling, the polyamide material is taken out, washed, and centrifuged to dryness to obtain the polyamide-based fiber with surface-immobilized ionized amidoxime.

[0042] Formula 3 schematically represents the chemical structure of the polyamide-based fiber with surface-immobilized ionized amidoxime:

[0043]

[0044] Among them, R1 in Formula -3 is selected from C1 - C 18 hydrocarbon groups. When Y is selected from C1 - C 18 hydrocarbon groups, X - is selected as Cl - , Br - or I - ; when Y is selected as -CH2CH2CO2 - , -CH2CH2CH2CO2 - , or -CH2CH2CH2SO3 - , X - does not select any one of the negative ions.

[0045] The mass ratio of the polyamide-based fiber with surface-grafted cyanide-containing ionomer / hydroxylamine salt / deionized water is 1:0.05 - 5:1 - 5.

[0046] The hydroxylamine salt refers to hydroxylamine hydrochloride or hydroxylamine sulfate.

[0047] The base refers to one or more of sodium hydroxide, sodium carbonate, calcium oxide, or magnesium oxide.

[0048] The beneficial effects of the polyamide-based fiber with surface-immobilized ionized amidoxime provided by the present invention are as follows:

[0049] ① The present invention realizes the all-round and uniform grafting of various functional ligands such as amidoxime, quaternary ammonium cation, tertiary amine group, carboxybetaine, or sulfobetaine on the surface of the polyamide-based fiber. The key is that the variety and grafting amount of the grafted functional ligands can be artificially regulated according to the morphology of the polyamide-based fiber.

[0050] ② The spacer arm connecting the ionized amidoxime on the surface of the polyamide-based fiber of the present invention is relatively long, and the spatial freedom degree of adjacent amidoximes is high, which can easily form 2:1 or 4:1 geometric complexes with uranyl ions or uranyl carbonate anions.

[0051] ③ The various functional ligands such as amidoxime, quaternary ammonium cation, tertiary amine group, carboxybetaine or sulfobetaine immobilized on the surface of the polyamide-based fiber of the present invention have high stability in seawater or acid-base aqueous solutions.

[0052] ④ The surface of the polyamide-based fiber of the present invention has high hydrophilicity, antibacterial property, anti-marine biofouling, zwitterionic double-exchange function, etc.

[0053] ⑤ Most of the base materials and reagent raw materials required for preparing the polyamide-based fiber immobilized with ionized amidoxime of the present invention are industrial products. The raw materials are easily available, the preparation method is simple, the cost is low, and the process is safe and efficient. Detailed implementation manners

[0054] The method for immobilizing ionized amidoxime on the surface of the polyamide-based fiber provided by the present invention is further illustrated by the following examples, aiming to better understand the content of the present invention. Therefore, the polyamide-based fiber immobilized with ionized amidoxime not listed in the examples should not be regarded as a limitation to the protection scope of the present invention.

[0055] Example 1 Preparation of polyamide 6 fiber immobilized with ionized amidoxime

[0056] Step 1: Preparation of surface unsaturated quaternary ammonium cationized polyamide 6 fiber

[0057] Weigh 280 grams of tetrahydrofuran in a reaction kettle at room temperature. While stirring, add 100 grams of polyamide 6 fiber bundle with a length of 280 dtex * 50 mm that has been cleaned to the reaction kettle. Slowly add 20 milliliters of a tetrahydrofuran solution containing 0.85 grams of potassium tert-butoxide under N2 protection. After stirring for half an hour, raise the temperature of the materials in the reaction kettle to 50 - 60 °C. Add 23.5 grams of N-glycidyl-N-benzyl-N,N-diallylammonium chloride in batches within 2 hours, and continue the heat preservation reaction for 2.5 hours. After cooling, neutralize the materials in the reaction kettle with an aqueous acetic acid solution with a mass percentage concentration of 30%. Take out the polyamide 6 fiber, wash it with water, and vacuum dry it to constant weight to obtain 120.3 grams of surface unsaturated quaternary ammonium cationized polyamide 6 fiber.

[0058] Step 2: Preparation of polyamide 6 fiber surface grafted with cyano-containing ionomer

[0059] Weigh 7.5 g of N-benzyl-N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)-N,N-diallylammonium chloride, 2.5 g of 4-(N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)-N,N-diallylammonium)butyrate, 5 g of 1,4-bis(N,N-diallyl-N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)ammonium)butane bromide and 1.05 g of azobisisobutylamidine hydrochloride, dissolve them in 15 g of deionized water to prepare a graft copolymerization solution;

[0060] 10.3 g of surface unsaturated quaternary ammonium cationized nylon 6 fiber obtained in step 1 was immersed in 30 g of graft copolymer solution, and after two immersions and two rollings, it was taken out and rinsed, and sent to a polymerization reactor. After nitrogen filling and deoxygenation for 30 minutes, the temperature was controlled at 50-60°C for oscillation polymerization reaction for 4 hours, and then the temperature was increased to 80-90°C for oscillation polymerization reaction for 2 hours. The nylon 6 was taken out from the polymerization reactor, cooled, washed with water, and centrifuged to obtain the nylon 6 fiber with surface grafted cyanide ionomer.

[0061] Step 3: Preparation of ionized amidoxime immobilized on the surface of nylon 6 fiber

[0062] 2.8 g of hydroxylamine hydrochloride was added to 30 g of deionized water, and after stirring and dissolving, the pH value was adjusted to 7.0 using caustic soda. Then, the nylon 6 fiber with surface grafted cyano ionomer obtained in step 2 was placed in the hydroxylamine aqueous solution, and the temperature was controlled at 60-80° C. and continuously immersed and reacted for 10 hours. After cooling, the nylon 6 was taken out, washed with water until neutral, and centrifuged at a constant speed of 2000±200 rpm for 5 minutes to obtain 20.6 g of nylon 6 fiber with surface immobilized ionized amidoxime.

[0063] According to the GB / T 5757-2008 method, the moisture content of 20.6g of nylon 6 fiber with ionized amidoxime immobilized on the surface was 29.03%. At room temperature, the nylon 6 fiber with ionized amidoxime immobilized on the surface was immersed in artificial seawater containing uranyl nitrate. The saturated adsorption capacity of uranium was 307.1mg / g and the saturated adsorption time was 13.5 minutes.

[0064] Example 2 Preparation of nylon 66 fiber immobilized ionized amidoxime

[0065] According to the preparation method and procedure of the polyamide 6 fiber with surface-immobilized ionized amidoxime described in Example 1, replace the 100 g polyamide 6 fiber bundle with a length of 280 dtex * 50 mm in Step 1 with a 100 g polyamide 66 fiber bundle with a length of 40 D * 50 mm, and respectively prepare surface-unsaturated quaternary ammonium cationized nylon 66 fiber, polyamide 66 fiber grafted with a cyano-containing ionomer on the surface, and polyamide 66 fiber immobilized with ionized amidoxime. At room temperature, immerse the polyamide 66 fiber immobilized with ionized amidoxime in artificial seawater containing uranyl nitrate, and the test measures a uranium saturation adsorption capacity of 236.8 mg / g and a saturation adsorption time of 12.6 minutes.

[0066] Preparation of Polyamide 66 Fiber Immobilized with Ionized Amidoxime in Example 3

[0067] According to the method and preparation procedure of the polyamide 6 fiber with surface-immobilized ionized amidoxime described in Example 1, replace the 100 g polyamide 6 fiber bundle with a length of 280 dtex * 50 mm in Step 1 with 100 g of raw polyamide 66 fiber with a yarn count of 40 D * 50 mm in length, and replace N-benzyl-N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)-N,N-diallylammonium in Step 2 with N-dodecyl-N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)-N,N-diallylammonium bromide, and 1,4-bis(brominated N,N-diallyl-N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)ammonium)butane with 4,4'-bis(chlorinated N,N-diallyl-N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)ammonium methyl)-1,1'-biphenyl, and respectively prepare surface-unsaturated quaternary ammonium cationized polyamide 66 fiber and polyamide 66 fiber immobilized with ionized amidoxime. At room temperature, immerse the polyamide 66 fiber immobilized with ionized amidoxime in artificial seawater containing uranyl nitrate, and the test measures a uranium saturation adsorption capacity of 223.4 mg / g and a saturation adsorption time of 22.3 minutes.

[0068] Preparation of Polyamide 66 Fiber Immobilized with Ionized Amidoxime in Example 4

[0069] According to the method and preparation procedure of the polyamide 6 fiber with surface-immobilized ionized amidoxime described in Example 1, replace the 100 g of polyamide 6 fiber bundle with a length of 280 dtex * 50 mm in Step 1 of Example 1 with 100 g of raw polyamide 66 fiber with a yarn count of 40D * 50 mm in length, and replace the 4-(N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)-N,N-diallylammonium) butyrate in Step 2 of Example 1 with 3-(N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)-N,N-diallylammonium)-1-propane sulfonate inner salt; replace 1,4-bis(brominated N,N-diallyl-N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)ammonium) butane with 1,4-bis((chlorinated N,N-diallyl-N-(2-hydroxy-3-(N,N-bis(2-cyanoethyl)amino)propyl)ammonium)methyl) benzene to respectively obtain unsaturated quaternary ammonium cationized polyamide 66 fiber and polyamide 66 fiber with immobilized ionized amidoxime. At room temperature, immerse the polyamide 66 fiber cloth with immobilized ionized amidoxime in artificial seawater containing uranyl nitrate, and the test measures that the uranium saturation adsorption capacity is 236.9 mg / g and the saturation adsorption time is 15 minutes.

[0070] Preparation of Polyamide-6 / Polyurethane Core-Sheath Composite Elastic Fiber with Immobilized Ionized Amidoxime in Example 5

[0071] According to the method and preparation procedure of the polyamide 6 fiber with surface-immobilized ionized amidoxime described in Example 1, replace the 100 g of polyamide 6 fiber bundle with a length of 280 dtex * 50 mm in Step 1 of Example 1 with 100 g of polyamide-6 / polyurethane core-sheath composite elastic fiber with a fineness of 22 dtex * 50 mm in length to respectively obtain unsaturated quaternary ammonium cationized polyamide-6 / polyurethane core-sheath composite elastic fiber and polyamide-6 / polyurethane core-sheath composite elastic fiber with immobilized ionized amidoxime. At room temperature, immerse the polyamide-6 / polyurethane core-sheath composite elastic fiber with immobilized ionized amidoxime in artificial seawater containing uranyl nitrate, and the test measures that the uranium saturation adsorption capacity is 376.3 mg / g and the saturation adsorption time is 12.5 minutes.

[0072] Preparation of Polyamide-Polyester Core-Sheath Composite Elastic Fiber with Immobilized Ionized Amidoxime in Example 6

[0073] According to the method and preparation procedure of the surface-fixed ionized amidoxime nylon 6 fiber described in Example 1, 100 grams of 55 dtex * 50 mm long core-shell nylon-polyester composite fiber with polyamide-6 / polyethylene terephthalate as raw materials is used instead of 100 grams of 280 dtex * 50 mm long nylon 6 fiber bundle in Step 1 of Example 1, and unsaturated quaternary ammonium cationized nylon-polyester core-shell composite fiber and nylon-polyester core-shell composite fiber fixed with ionized amidoxime are respectively prepared. At room temperature, the nylon-polyester core-shell composite fiber fixed with ionized amidoxime is immersed in artificial seawater containing uranyl nitrate, and the uranium saturation adsorption capacity is measured to be 312.7 mg / g and the saturation adsorption time is 13.8 minutes.

Claims

1. A method for immobilizing ionized amidoxime on the surface of polyamide-based fibers, characterized in that it is It is realized by the following steps: Step 1: Preparation of unsaturated quaternary ammonium cationized polyamide-based fiber Weigh a solvent into a reaction kettle. Under stirring at room temperature, add the polyamide-based fiber that has been cleaned and dried into the reaction kettle. Slowly add an alkali reagent under nitrogen protection. After impregnating evenly, raise the temperature of the materials in the reaction kettle to 40-90 °C, and then gradually add an unsaturated quaternary ammonium salt containing a glycidyl group. Keep the temperature for 0.5-5 hours to complete the ring-opening reaction. Neutralize the materials in the reaction kettle with an acetic acid aqueous solution with a mass percentage concentration of 30-80%. End the reaction, filter out the polyamide-based fiber, wash it with water and dry it to obtain the unsaturated quaternary ammonium cationized polyamide-based fiber; Among them, the dosage of the unsaturated quaternary ammonium salt containing a glycidyl group is 0.5-50% of the molar number of amide structural unit N-H contained in the polyamide-based fiber, the dosage of the alkali reagent is 0.2-12% of the mass of the unsaturated quaternary ammonium salt containing a glycidyl group, and the dosage of the solvent is 2-20 times the mass of the polyamide-based fiber; The polyamide-based fiber refers to one of cross-linked or non-cross-linked polyamide fibers, or cross-linked or non-cross-linked polyamide composite fibers; Among them, the cross-linked or non-cross-linked polyamide composite fiber refers to a composite fiber spun from cross-linked or non-cross-linked polyamide and a polymer as raw materials, or a composite fiber blended from cross-linked or non-cross-linked polyamide fibers, synthetic fibers, or plant fibers as raw materials; Among them, the polymer refers to one or more of polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyethylene terephthalate, polyurethane, polyvinyl acetal, polyphenylene ether, polyether ketone, polyether sulfone, polyether ether sulfone, or polyether ether ketone; the synthetic fiber refers to one or more of polyethylene fiber, polypropylene fiber, polystyrene fiber, polyacrylonitrile fiber, polyester fiber, polyurethane fiber, or polyvinyl acetal fiber; The plant fiber refers to one of cotton fiber, hemp fiber, or regenerated cellulose fiber; The unsaturated quaternary ammonium salt containing a glycidyl group has the structure shown in general formula (Ⅰ): Among them, R1 in general formula (I) is selected from C1-C 18 hydrocarbyl; Step 2: Grafting a cyanide-containing ionomer on the surface of the polyamide-based fiber Spray, roll coat, or brush coat the graft copolymerization solution on the surface of the unsaturated quaternary ammonium cationized polyamide-based fiber prepared in Step 1, or immerse the unsaturated quaternary ammonium cationized polyamide-based fiber prepared in Step 1 into the graft copolymerization solution. Take out the polyamide-based fiber that has been evenly dipped or evenly coated with the graft copolymerization solution and send it into a polymerization reactor. After purging with nitrogen and removing oxygen for 30 minutes, control the temperature at 50-60 °C and carry out an oscillating polymerization reaction for 4-8 hours, then raise the temperature to 80-90 °C and carry out an oscillating polymerization reaction for 2-4 hours. Take out the polyamide-based fiber from the polymerization reactor, cool it down, wash it with water and dry it to obtain the polyamide-based fiber with a cyanide-containing ionomer grafted on its surface; The graft copolymerization solution refers to a solution prepared by mixing a diallylammonium-type ionic monomer containing a cyano group, a bis(diallylammonium) salt crosslinking agent containing multiple cyano groups, and an aqueous initiator in deionized water according to a mass ratio of 1:0.1-5:0.03-0.3:1-10. The dosage of the graft copolymerization solution is 0.2-20 times the mass of the unsaturated quaternary ammonium cationized polyamide-based fiber; The diallylammonium-type ionic monomer containing a cyano group has the structure shown in general formula (Ⅱ): wherein when Y in the general formula (II) is selected from C1-C 18 hydrocarbyl, X - is selected from Cl - , Br - or I - ; when Y is selected from -CH2CH2CO2 - , -CH2CH2CH2CO2 - , or -CH2CH2CH2SO3 - , X - is not selected from any anions; The bis(diallylammonium) salt crosslinking agent containing multiple cyano groups has the structure shown in general formula (Ⅲ):

2. Among them, X in the general formula (Ⅲ) - Select Cl - , Br - or I - One of them, Select C1~C 18 Alkylene or , where n is selected from natural numbers between 0 and 200; Step 3. Preparation of a polyamide-based fiber with surface-immobilized ionized amidoxime Hydroxylamine salt is added to deionized water, stirred and dissolved, and then the pH value is adjusted to 6.0-7.5 with an appropriate amount of base to obtain an aqueous hydroxylamine solution. Then, the polyamide-based fiber with surface-grafted cyano-containing ionomer prepared in Step 2 is immersed in the aqueous hydroxylamine solution, the temperature is controlled at 60-80 °C, and the reaction is carried out with oscillation for 10-12 hours. After cooling, the polyamide-based fiber is taken out, washed and dried to obtain the polyamide-based fiber with surface-immobilized ionized amidoxime; The mass ratio of the polyamide-based fiber with surface-grafted cyano-containing ionomer / hydroxylamine salt / deionized water is 1:0.05-5:1-5.

3. The method for immobilizing ionized amidoxime on the surface of a polyamide-based fiber according to claim 1, wherein The base reagent refers to one of sodium hydride, potassium hydride, sodium tert-butoxide, potassium tert-butoxide, lithium N,N-diisopropylamide, butyllithium, sodium phenyl, or sodium naphthyl.

4. The method for immobilizing ionized amidoxime on the surface of a polyamide-based fiber according to claim 1, characterized in that The solvent is selected from one or more of tetrahydrofuran, 1,4-dioxane, benzene, toluene, xylene, pentane, n-hexane, heptane, cyclohexane, decalin, petroleum ether with a boiling range of 60-90 °C, or dimethyl sulfoxide.

5. A method for immobilizing ionized amidoxime on the surface of a polyamide-based fiber according to claim 1, characterized in that The aqueous initiator refers to one or more of hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) dihydrochloride, sodium 2,2'-azobis(2-cyanovalerate), or 2,2'-azobis(2-isopropylimidazoline) dihydrochloride.

6. The method for immobilizing ionized amidoxime on the surface of a polyamide-based fiber according to claim 1, characterized in that The hydroxylamine salt refers to hydroxylamine hydrochloride or hydroxylamine sulfate.

7. The method for immobilizing ionized amidoxime on the surface of a polyamide-based fiber according to claim 1, characterized in that The base refers to one or more of sodium hydroxide, sodium carbonate, calcium oxide, or magnesium oxide.

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