阅读说明：本技术 一种高白度聚酰亚胺超细纤维及其制备方法和应用 (High-whiteness polyimide superfine fiber and preparation method and application thereof ) 是由 刘金刚 郭晨雨 吴�琳 张燕 职欣心 武晓 于 2020-04-29 设计创作，主要内容包括：本发明提供了一种高白度聚酰亚胺超细纤维及其制备方法和应用。该聚酰亚胺纤维,包括由全脂环二酐HTDA与含甲基或氟甲基的芳香族二胺单体反应通过化学亚胺法得到的聚酰亚胺。本发明得到的聚酰亚胺超细纤维兼具优良的耐热稳定性和纺丝成膜性且织物具有超高的白度。该聚酰亚胺超细纤维织物可作为耐高温、高白度组件应用于个人防护用品,如口罩、防护服等,也可作为电子组件应用于航空航天、光电子、微电子以及汽车等高技术领域。(The invention provides a high-whiteness polyimide superfine fiber and a preparation method and application thereof. The polyimide fiber comprises polyimide obtained by reacting full-alicyclic dianhydride HTDA with an aromatic diamine monomer containing methyl or fluoromethyl through a chemical imine method. The polyimide superfine fiber obtained by the invention has excellent heat-resistant stability and spinning film-forming property, and the fabric has ultrahigh whiteness. The polyimide superfine fiber fabric can be used as a high-temperature-resistant and high-whiteness component to be applied to personal protective articles, such as masks, protective clothing and the like, and can also be used as an electronic component to be applied to the high-technology fields of aerospace, photoelectrons, microelectronics, automobiles and the like.)

1. A polyimide fiber characterized by comprising a polyimide obtained by a chemical imine process by reacting a full-aliphatic cyclic dianhydride HTDA with a methyl-or fluoromethyl-containing aromatic diamine monomer.

2. The polyimide fiber according to claim 1, wherein the methyl-or fluoromethyl-containing aromatic diamine monomer is 2,2 '-dimethyl-4, 4' -Diaminobiphenyl (DMBZ) or 4,4 '-diamino-2, 2' -bistrifluoromethylbenzene (TFMB).

3. The polyimide fiber according to claim 1 or 2, wherein the polyimide is a compound represented by the following general structural formula I:

in the general structural formula of the formula I, the-Ar-isAnd n is an integer of 1-200.

4. Polyimide fiber according to claim 1 or 2, wherein-Ar-isAnd n is an integer of 10-100.

5. The method for producing the polyimide fiber according to any one of claims 1 to 4, comprising the steps of:

1) dissolving an aromatic diamine monomer containing methyl or fluoromethyl in an aprotic strong polar solvent, stirring to form a homogeneous solution, adding full-alicyclic dianhydride (HTDA), and reacting to obtain a polyamic acid (PAA) solution;

2) adding acetic anhydride and pyridine into the PAA solution, and reacting to obtain a soluble polyimide solution;

3) precipitating the soluble polyimide solution into absolute ethyl alcohol to obtain polyimide resin;

4) and dissolving the polyimide resin in an organic solvent to obtain a polyimide solution, and preparing the high-whiteness polyimide superfine fiber under the voltage of 12-20kV by using an electrostatic spinning technology.

6. The method according to claim 5, wherein in the step 1), the molar ratio of the methyl-or fluoromethyl-containing aromatic diamine monomer to the full-aliphatic dianhydride HTDA is (0.95-1.02): 1.02-0.95, preferably (0.98-1.01): 1;

and/or the aprotic strongly polar solvent is selected from at least one of N-methylpyrrolidone (NMP), m-cresol, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), gamma-butyrolactone, preferably N, N-dimethylacetamide;

the dosage of the aprotic strong polar solvent is that the mass percentage of the solid in the reaction system is 10-30 wt%, preferably 15-25 wt%;

the reaction temperature is 0-30 ℃ and the reaction time is 10-48 hours; preferably, the reaction temperature is 10-25 ℃ and the reaction time is 18-24 hours.

7. The production method according to claim 5, wherein in the step 2),

the molar ratio of the aromatic dianhydride HTDA to the acetic anhydride to the pyridine is 1 (3-20) to (2-16), preferably 1 (5-10): (4-8);

and/or the reaction temperature is 0-25 ℃ and the reaction time is 10-48 hours; preferably, the reaction temperature is 15-25 ℃ and the reaction time is 12-24 hours.

8. The preparation method according to any one of claims 5 to 7, wherein in the step 4), the solid content of the polyimide solution is 15 wt% to 40 wt%; the organic solvent is selected from one or more of N-methyl pyrrolidone (NMP), N-Dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO) and N, N-Dimethylformamide (DMF).

9. The preparation method according to any one of claims 5 to 7, wherein in the step 4), the parameters of the electrostatic spinning technology are 0.21-0.50mm of inner diameter of a spinneret, 12-20kV of applied voltage, 0.1m L/h of injection speed, 10-20cm of distance between the spinneret and a receiving device and 30 +/-10% of relative humidity.

10. Use of a polyimide fiber according to any one of claims 1 to 4 or a method of preparation according to any one of claims 5 to 9 in personal protective articles, microelectronics, optoelectronics or wearable electronics.

Technical Field

The invention relates to the field of functional fiber materials, in particular to a high-whiteness polyimide superfine fiber and a preparation method and application thereof.

Background

White is the most popular color in industrial products today in terms of color, and high whiteness polymer fiber fabrics are becoming increasingly popular in modern industries. In addition, high-brightness components can generally improve the efficiency of the functional device. For example, the addition of high-whiteness coatings can generally provide high reflectivity and scattering properties, which are advantageous for improving the light efficiency and quality of the illumination system. It is common in the art to increase the whiteness and opacity of materials by the addition of mineral fillers such as titanium dioxide, kaolin, calcium carbonate, and the like, or organic optical brighteners. In this case, to obtain sufficient whiteness, the content of the added pigment tends to be large, affecting the mechanical properties of the material; meanwhile, the compatibility of the mineral filler and the polymer is generally poor, necessary treatment is required before use, and the added production process increases the cost of the material; and has potential environmental pollution and harm to human health. On the other hand, the existing intrinsic high-whiteness fiber materials, such as cotton fibers, polyvinyl alcohol fibers, polyethylene fibers and the like, have poor temperature resistance, and cannot meet the application requirements of the high-technology field. Therefore, research and development of intrinsic high temperature resistant high whiteness materials are necessary.

In recent years, Polyimide (PI) ultrafine fiber fabrics have been widely used in many fields such as high-temperature dust filter materials, electrical insulation materials, various high-temperature resistant flame-retardant protective clothing, parachutes, heat sealing materials, composite reinforcing agents, and radiation-resistant materials due to their excellent comprehensive properties. However, the color of the traditional wholly aromatic PI fiber fabric product is usually darker due to stronger conjugation between molecules.

Disclosure of Invention

The first purpose of the invention is to provide a high-whiteness PI superfine fiber. The superfine fiber overcomes the defect that fabrics present dark brown to yellow color due to strong intramolecular and intermolecular conjugate interaction in the chain in the existing PI spinning technology, and provides the soluble PI superfine fiber which has good comprehensive performance and high whiteness.

The invention provides soluble PI superfine fiber, namely polyimide fiber of the invention, which comprises polyimide obtained by a chemical imine method through the reaction of full-alicyclic dianhydride HTDA and an aromatic diamine monomer containing methyl or fluoromethyl.

In a preferred embodiment of the present invention, the methyl group-containing aromatic diamine monomer is 2,2 '-dimethyl-4, 4' -Diaminobiphenyl (DMBZ) or 4,4 '-diamino-2, 2' -bistrifluoromethylbenzene (TFMB).

In a preferred embodiment of the present invention, the polyimide is a compound represented by the following structural formula I:

in the general structural formula of the formula I, the-Ar-isAnd n is an integer of 1-200. More preferably, said-Ar-isThat is, a polyimide fiber obtained by a chemical imine method by reacting a fully alicyclic dianhydride HTDA with a methyl group-containing aromatic diamine monomer is a more preferable embodiment of the present invention. Wherein n is more preferably an integer of 10-100, and the polyimide fiber prepared by using the structure has high molecular weight, good performance and high whiteness.

The polyimide fiber provided by the invention is high-whiteness polyimide superfine fiber, not only can be dissolved in a polar aprotic solvent, but also has good solubility in conventional solvents including but not limited to chloroform, tetrahydrofuran, cyclopentanone, cyclohexanone, methyl isobutyl ketone and the like.

The second object of the present invention is to provide a method for producing the polyimide fiber, which comprises using a full-aliphatic dianhydride monomer HTDA and a methyl-or fluoromethyl-containing aromatic diamine monomer as raw materials and using a chemical imidization method. The preparation method is simple and efficient, and has high yield.

The preparation method of the polyimide fiber comprises the following steps:

1) dissolving an aromatic diamine monomer containing methyl or fluoromethyl in an aprotic strong polar solvent, stirring to form a homogeneous solution, adding full-alicyclic dianhydride (HTDA), and reacting to obtain a polyamic acid (PAA) solution;

2) adding acetic anhydride and pyridine into the PAA solution, and reacting to obtain a soluble polyimide solution;

3) precipitating the soluble polyimide solution into absolute ethyl alcohol to obtain polyimide resin;

4) and dissolving the polyimide resin in an organic solvent to obtain a polyimide solution, and preparing the polyimide fiber by an electrostatic spinning technology under the voltage of 12-20 kV. The polyimide fiber obtained by the invention is also a high-whiteness polyimide superfine fiber (high-whiteness PI superfine fiber).

In a preferred embodiment of the present invention, the molar ratio of the methyl-or fluoromethyl-containing aromatic diamine monomer to the full-aliphatic cyclic dianhydride HTDA is (0.95-1.02): 1.02-0.95, preferably (0.98-1.01): 1.

In a preferred embodiment of the present invention, the methyl-or fluoromethyl-containing aromatic diamine monomer is preferably a methyl-containing aromatic diamine monomer, and more preferably 2,2 '-dimethyl-4, 4' -Diaminobiphenyl (DMBZ).

In a preferred embodiment of the present invention, the aprotic strongly polar solvent in step 1) is selected from at least one of N-methylpyrrolidone (NMP), m-cresol, N-Dimethylformamide (DMF), N-Dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), γ -butyrolactone, preferably N, N-dimethylacetamide.

Wherein, the amount of the aprotic highly polar solvent used in step 1) is such that the mass percentage of the solid in the reaction system is preferably 10 wt% to 30 wt%, and more preferably 15 wt% to 25 wt%.

In a preferred embodiment of the present invention, in the step 1), the reaction temperature is 0 to 30 ℃ and the reaction time is 10 to 48 hours; preferably, the reaction temperature is 10-25 ℃ and the reaction time is 18-24 hours.

In a preferred embodiment of the invention, in the step 2), the molar ratio of the aromatic dianhydride HTDA, acetic anhydride and pyridine is 1 (3-20) to (2-16), preferably 1 (5-10): (4-8).

In a preferred embodiment of the present invention, in the step 2), the reaction temperature is 0 to 25 ℃ and the reaction time is 10 to 48 hours; preferably, the reaction temperature is 15-25 ℃ and the reaction time is 12-24 hours.

In the present invention, both step 1) and step 2) are performed under a nitrogen atmosphere.

In a preferred embodiment of the present invention, in the step 4), the solid content of the polyimide solution is 15 wt% to 40 wt%. The organic solvent may be one or more organic solvents commonly used in the art, preferably selected from N-methylpyrrolidone (NMP), N-Dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), and N, N-Dimethylformamide (DMF), and preferably is N, N-Dimethylacetamide (DMAC).

In a preferred embodiment of the invention, in order to ensure the mechanical properties of the fiber and simultaneously improve the whiteness of the fiber, in the step 4), the parameters of the electrostatic spinning technology are that the inner diameter of a spinneret is 0.21-0.50mm, the applied voltage is 12-20kV, the injection speed is 0.1m L/h, the distance between the spinneret and a receiving device is 10-20cm, and the relative humidity is 30 +/-10%, wherein the applied voltage is preferably 15-18 kV.

In the preparation method of the present invention, the method preferably further comprises heat-treating the polyimide microfiber obtained by electrospinning at 180 to 200 ℃ for 0.5 to 5 hours, more preferably 1 to 3 hours, to obtain a polyimide microfiber fabric.

The invention also aims to provide application of the polyimide fiber or the preparation method of the polyimide fiber in personal protection products, microelectronics, optoelectronics or wearable electronic products.

The polyimide provided by the invention has good solubility, and the prepared polyimide superfine fiber has excellent heat resistance stability and spinning film forming property and ultrahigh whiteness. The polyimide superfine fiber fabric can be used as an electronic component to be applied to the high-tech fields of aerospace, photoelectron, microelectronics, automobiles and the like.

Drawings

FIG. 1 is a Gel Permeation Chromatography (GPC) chart of PI resins prepared in examples 1-2.

FIG. 2 shows an infrared (FT-IR) spectrum of PI ultrafine fiber fabrics prepared in examples 1-2.

FIG. 3 is a Scanning Electron Microscope (SEM) image of the PI ultrafine fiber fabric prepared in example 1.

FIG. 4 is a TGA spectrum of PI superfine fiber fabric prepared in examples 1-2.

Fig. 5 is an ultraviolet-visible (UV-Vis) spectrum of PI ultra fine fiber fabrics prepared in example 1 and comparative example 1.

FIG. 6 is a chromaticity coordinate diagram of PI ultrafine fiber fabrics prepared in example 1 and comparative example 1.

FIG. 7 is an SEM image of PI prepared in example 1 and a Polystyrene (PS) microfiber fabric prepared in comparative example 2 after high temperature treatment.

Detailed Description

The following examples are given to further illustrate the embodiments of the present invention. The following examples are provided to illustrate the present invention, but are not intended to limit the scope of the present invention.

The method is a conventional method unless otherwise specified. The materials are commercially available from the open literature unless otherwise specified.

The performance evaluation method of the PI resin and PI superfine fiber fabric obtained in the following examples is as follows:

molecular weight of PI resin:

gel Permeation Chromatography (GPC) the prepared PI resin was subjected to High Performance Liquid Chromatography (HPLC) at L C-20AD from Shimadzu corporation, Japan, with N-methylpyrrolidone (NMP) as the mobile phase.

The microscopic morphology evaluation method of the PI superfine fiber fabric comprises the following steps:

scanning Electron Microscope (SEM), the prepared PI superfine fiber fabric is tested on JSM-IT300 series scanning electron microscope of Japan JEO L company, and the accelerating voltage is 5-20 KV.

The thermal decomposition temperature evaluation method of the PI superfine fiber fabric comprises the following steps:

thermogravimetric analysis (TGA): the prepared PI superfine fiber fabric is tested on a thermal gravimetric analyzer STA8000 of PerkinElmer company in the United states, and the temperature rise speed is as follows: 10 ℃/min, nitrogen atmosphere.

The whiteness evaluation method of the PI superfine fiber fabric comprises the following steps:

ultraviolet-visible reflectance spectrum (UV-Vis): the prepared PI ultrafine fiber fabric was tested on a UV spectrophotometer model U-3900 of HITACHI, Japan. The wavelength range is 200 and 800 nm. R457 is defined as the reflectance of the sample at 457 nm.

Whiteness Index (WI) the prepared PI ultra-fine fiber fabrics were tested on an X-rite color i7 spectrophotometer and color parameters were calculated according to the CIE L ab equation, where L is the brightness, 100 represents white, 0 represents black, positive a represents red, negative a represents green, positive b represents yellow, negative b represents blue, whiteness index WI was calculated according to the chinese standard GB/T17644-.