阅读说明：本技术 功能化氧化钛改性聚酰亚胺纤维过滤材料的制备方法 (Preparation method of functionalized titanium oxide modified polyimide fiber filter material ) 是由 王文爽 沈文齐 于 2020-05-06 设计创作，主要内容包括：本发明公开一种功能化氧化钛改性聚酰亚胺纤维过滤材料的制备方法：利用羧基和羟基修饰的功能化纳米氧化钛与4,4’-六氟异丙基邻苯二甲酸酐单体、4,4’-(六氟异亚丙基)二苯胺单体共聚而成,再静电纺丝成聚酰亚胺纤维无纺布；具体包括以下步骤：S1：制备功能化纳米氧化钛：将钛酸四丁酯、2,3-二羟基丁二酸溶解于65％乙醇溶液中,并滴加乙酰丙酮,100～130℃水热反应2～4h,静置陈化3～6h,过滤、洗涤、干燥后,得到功能化纳米氧化钛；S2：制备改性聚酰亚胺；S3：静电纺丝。本发明首次实现纳米氧化钛从分子层面上对聚酰亚胺的改性作用,制备出的过滤材料稳定性高,机械性能、耐久性、耐候性良好,不会发生纳米氧化钛脱落、剥离现象。(The invention discloses a preparation method of a functionalized titanium oxide modified polyimide fiber filtering material, which comprises the following steps: the functional nano titanium oxide modified by carboxyl and hydroxyl is copolymerized with 4,4 '-hexafluoroisopropyl phthalic anhydride monomer and 4,4' - (hexafluoroisopropyl) diphenylamine monomer, and then the mixture is subjected to electrostatic spinning to form polyimide fiber non-woven fabric; the method specifically comprises the following steps: s1: preparing functionalized nano titanium oxide: dissolving tetrabutyl titanate and 2, 3-dihydroxysuccinic acid in 65% ethanol solution, dropwise adding acetylacetone, carrying out hydrothermal reaction at 100-130 ℃ for 2-4 h, standing and aging for 3-6 h, filtering, washing and drying to obtain functionalized nano titanium oxide; s2: preparing modified polyimide; s3: and (4) electrostatic spinning. The invention realizes the modification effect of the nano titanium oxide on polyimide from a molecular layer for the first time, and the prepared filter material has high stability, good mechanical property, durability and weather resistance, and can not generate the phenomena of falling off and peeling off of the nano titanium oxide.)

1. A preparation method of a functionalized titanium oxide modified polyimide fiber filter material is characterized by comprising the following steps: the functional nano titanium oxide modified by carboxyl and hydroxyl is copolymerized with 4,4 '-hexafluoroisopropyl phthalic anhydride monomer and 4,4' - (hexafluoroisopropyl) diphenylamine monomer, and then the mixture is subjected to electrostatic spinning to form polyimide fiber non-woven fabric; the method specifically comprises the following steps:

s1: preparing functionalized nano titanium oxide: dissolving tetrabutyl titanate and 2, 3-dihydroxysuccinic acid in 65% ethanol solution, dropwise adding acetylacetone, carrying out hydrothermal reaction at 100-130 ℃ for 2-4 h, standing and aging for 3-6 h, filtering, washing and drying to obtain functionalized nano titanium oxide; the dosage proportion of tetrabutyl titanate, 2, 3-dihydroxy succinic acid, acetylacetone and 65% ethanol solution is (10-20) mmol: (2-5) mmol: (0.5-1) mmol: 100 mL;

s2: preparing modified polyimide: dissolving 4,4 '-hexafluoroisopropylphthalic anhydride and 4,4' - (hexafluoroisopropylidene) diphenylamine in an N-methylpyrrolidone solvent, adding functionalized nano titanium oxide, isoquinoline and p-toluenesulfonic acid, heating to 60-100 ℃, stirring and polymerizing for 4-8 hours, continuously heating to 180-200 ℃, imidizing for 10-18 hours, and synthesizing a modified polyimide solution; in the reaction system: the mass ratio of 4,4 '-hexafluoroisopropylphthalic anhydride +4, 4' - (hexafluoroisopropylidene) diphenylamine, functionalized nano titanium oxide, isoquinoline, p-toluenesulfonic acid and N-methylpyrrolidone is 1: (0.2-0.3): (0.1-0.15): (0.05-0.1): (6.5-7.5);

s3: electrostatic spinning: diluting the modified polyimide solution to a solid content of 5-8%, and performing electrostatic spinning under a voltage of 15-20 kV to prepare the titanium oxide cross-linked modified fluorine-containing polyimide fiber membrane.

2. The method for preparing the functionalized titanium oxide modified polyimide fiber filter material as claimed in claim 1, wherein the molar ratio of 4,4 '-hexafluoroisopropylphthalic anhydride to 4,4' - (hexafluoroisopropylidene) diphenylamine is 1: (0.9-1.1).

Technical Field

The invention belongs to the field of preparation of a functionalized titanium oxide modified polyimide fiber filter material.

Background

Polyimide is a polymer containing imide rings (-CO-N-CO-) on the main chain, has high temperature resistance of more than 400 ℃, long-term use temperature range of-200-300 ℃, excellent thermal stability and mechanical strength, corrosion resistance and high insulativity, a dielectric constant of 4.0 at 103 Hz and dielectric loss of only 0.004-0.007, belongs to F to H, is one of organic polymer materials with the best comprehensive performance, and is widely applied to the fields of aviation, aerospace, microelectronics, nano-scale, liquid crystal, separation membranes, lasers and the like.

With the increasing severity of the environmental pollution caused by high-temperature flue gas such as industrial flue gas, combustion coal, automobile exhaust, biomass combustion, metallurgy, etc., the high-temperature filtration and dust removal technology has become a research hotspot in the industrial and academic industries. At present, high-temperature flue gas filter materials mainly take high-temperature resistant polymer fibers such as polyimide, polyphenylene sulfide, aromatic polyamide, polysulfonamide, polytetrafluoroethylene and the like as raw materials, and mainly filter and separate fine particles in high-temperature flue gas, but industrial high-temperature flue gas often contains SO_x、NO_x、H₂S, HCN, etc., and various photocatalyst/polyimide composite materials have been developed to further degrade the toxic and harmful gases.

The existing polyimide/titanium dioxide composite material is mainly prepared by mixing and reacting nano titanium oxide, diamine and dianhydride, but the nano titanium oxide does not participate in polymerization reaction, but is compounded with polyimide fibers in a physical blending mode, the bonding firmness is not high, and the nano titanium oxide is easy to fall off from the surfaces of the polyimide fibers, for example, a patent of application No. CN201710857569.3 discloses polyimide/titanium dioxide hybrid fibers, and nano TiO is utilized to prepare the polyimide/titanium dioxide hybrid fibers₂4,4' -diaminodiphenyl ether and pyromellitic dianhydride are mixed and reacted to prepare polyimideTitanium dioxide hybrid fiber, but nano TiO₂Is a physical doping mode. In addition, the method is only suitable for the synthesized polyimide fiber, is not suitable for diamine monomers and dianhydride monomers which do not undergo condensation polymerization, has limitations on synthesis process and application, is also physical deposition essentially, has no chemical crosslinking effect between polyimide and titanium oxide, has poor durability and wear resistance, can cause the titanium oxide deposited on the surface to fall off after long-term use, and can cause the nano particles to easily carry out in-situ blocking on the pore diameter of the fiber membrane in the direct deposition process so as to greatly reduce the filtration efficiency of the fiber membrane, for example, the patent with the application number of CN201610050579.1 discloses a preparation method of the polyimide fiber membrane with a titanium dioxide nano layer coated on the surface, the polyamide acid fiber membrane is treated by a titanium compound, for example, patent with application number of CN201710132514.6, discloses a polyimide/titanium dioxide composite fiber and a preparation method and application thereof, wherein a titanyl sulfate solution is used for impregnating the polyimide fiber, ammonia water is added for in-situ precipitation, and the polyimide/titanium dioxide composite fiber is obtained after heat treatment.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a preparation method of a functionalized titanium oxide modified polyimide fiber filter material.

The technical scheme of the invention is summarized as follows:

a preparation method of a functionalized titanium oxide modified polyimide fiber filter material comprises the following steps: the functional nano titanium oxide modified by carboxyl and hydroxyl is copolymerized with 4,4 '-hexafluoroisopropyl phthalic anhydride monomer and 4,4' - (hexafluoroisopropyl) diphenylamine monomer, and then the mixture is subjected to electrostatic spinning to form polyimide fiber non-woven fabric; the method specifically comprises the following steps:

s1: preparing functionalized nano titanium oxide: dissolving tetrabutyl titanate and 2, 3-dihydroxysuccinic acid in 65% ethanol solution, dropwise adding acetylacetone, carrying out hydrothermal reaction at 100-130 ℃ for 2-4 h, standing and aging for 3-6 h, filtering, washing and drying to obtain functionalized nano titanium oxide; the dosage proportion of tetrabutyl titanate, 2, 3-dihydroxy succinic acid, acetylacetone and 65% ethanol solution is (10-20) mmol: (2-5) mmol: (0.5-1) mmol: 100 mL;

s2: preparing modified polyimide: dissolving 4,4 '-hexafluoroisopropylphthalic anhydride and 4,4' - (hexafluoroisopropylidene) diphenylamine in an N-methylpyrrolidone solvent, adding functionalized nano titanium oxide, isoquinoline and p-toluenesulfonic acid, heating to 60-100 ℃, stirring and polymerizing for 4-8 hours, continuously heating to 180-200 ℃, imidizing for 10-18 hours, and synthesizing a modified polyimide solution; in the reaction system: the mass ratio of 4,4 '-hexafluoroisopropylphthalic anhydride +4, 4' - (hexafluoroisopropylidene) diphenylamine, functionalized nano titanium oxide, isoquinoline, p-toluenesulfonic acid and N-methylpyrrolidone is 1: (0.2-0.3): (0.1-0.15): (0.05-0.1): (6.5-7.5);

s3: electrostatic spinning: diluting the modified polyimide solution to a solid content of 5-8%, and performing electrostatic spinning under a voltage of 15-20 kV to prepare the titanium oxide cross-linked modified fluorine-containing polyimide fiber membrane.

Preferably, the molar ratio of the 4,4 '-hexafluoroisopropylidene phthalic anhydride to the 4,4' - (hexafluoroisopropylidene) diphenylamine is 1: (0.9-1.1).

The invention has the beneficial effects that:

1. according to the invention, a hydrothermal method of 2, 3-dihydroxybutanedioic acid and tetrabutyl titanate is utilized for the first time to prepare the carboxyl-and-hydroxyl-rich high-reactivity nano titanium oxide, amidation between carboxyl and amino and esterification between hydroxyl and carboxyl are utilized, the nano titanium oxide is subjected to condensation copolymerization with fluorine-containing dianhydride monomer and fluorine-containing diamine monomer, and then the nano titanium oxide is grafted or crosslinked onto a polyimide molecular chain.

2. The fluorine-containing polyimide fiber membrane prepared by the method has high specific surface area which can reach 852.7m²More than g, wherein the specific surface area of micropores with the pore diameter of less than 1nm can reach 196.4m²More than g, effectively improves the filtration efficiency of the high-temperature flue gas, has low surface energy and good anti-fouling performance, has a water drop contact angle of more than 138.4 degrees, and can efficiently degrade toxic and harmful substances in the high-temperature flue gas.

Drawings

FIG. 1 is a flow chart of a preparation method of a functionalized titanium oxide modified polyimide fiber filter material of the invention.

Detailed Description

The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.