WO2024067260A1

WO2024067260A1 - Method for preparing fibers of imide copolymer from amic acid copolymer, and fibers prepared therefrom

Info

Publication number: WO2024067260A1
Application number: PCT/CN2023/119808
Authority: WO
Inventors: 杨万泰; 黄延宾; 常添笑; 陈明森
Original assignee: 清华大学
Priority date: 2022-09-28
Filing date: 2023-09-19
Publication date: 2024-04-04
Also published as: CN115652474A

Abstract

A method for preparing fibers of an imide copolymer (A) from an amic acid copolymer (B), the method comprising: (I) spinning an aqueous solution of an amic acid copolymer (B) to obtain fibers of the amic acid copolymer (B), and (II) imidizing the fibers of the amic acid copolymer (B) obtained in step (I) to obtain fibers of an imide copolymer (A), wherein the imide copolymer (A) is an imide copolymer having an imide pendant group. The present disclosure further relates to fibers obtained by means of the method and an article obtained from the fibers. The method is simple, efficient, economical and environmentally friendly, and can be used for continuously preparing imide copolymer fibers.

Description

Method for preparing fibers of imide copolymers from amic acid copolymers and fibers prepared therefrom

Technical Field

The present disclosure relates to a method for preparing fibers of imide copolymers from amic acid copolymers and fibers prepared therefrom.

Background technique

Fiber materials play a very important role in the development of the national economy and national defense construction. At present, fiber materials are developing towards high performance, multifunctionality, high added value and low environmental pollution in the production process. Among fiber materials, a large part of fiber materials are artificially made of polymer materials, called "synthetic fibers", mainly polyester, nylon, acrylic fiber, polypropylene fiber, spandex, vinylon, chloroprene, etc. However, these synthetic fibers have problems such as insufficient raw material sources, high preparation costs, and difficulty in dyeing. Therefore, it is very important to develop new low-cost polar copolymer fibers.

Maleic anhydride copolymer is a polar copolymer with low cost and wide source of raw materials. After being processed into fiber materials, it is usually used in the fields of adsorption and papermaking. US 3983095 A and US 3954721 A disclose a method of preparing absorbent fibers by dissolving maleic anhydride copolymer in an organic solution and spinning it, lightly crosslinking it with diamine or diol, and then ammoniation or saponification. US 4731067 A and US 4880868 A disclose a method of saponifying maleic anhydride copolymer to form a carboxylic acid metal salt, crosslinking it with diol, spinning it with water as solvent, and finally forming absorbent fibers after heat treatment. However, maleic anhydride copolymers are usually used as hydrophilic fibers, and their application range is limited.

Therefore, there is a need in the prior art to prepare water-resistant, high-performance imide copolymer fibers through a simple, efficient, economical and environmentally friendly continuous method.

Summary of the invention

In view of the above-mentioned state of the prior art, the inventors of the present invention have conducted extensive and in-depth research in the field of fibers in order to find a simple, efficient, economical and environmentally friendly method for continuously preparing imide copolymer fibers. The inventors of the present invention have found a method for preparing fibers of an imide copolymer (A) from an aqueous solution of an amic acid copolymer (B), which is simple, efficient, economical, environmentally friendly and can continuously prepare water-resistant, high-performance imide copolymer fibers. The present invention is completed based on the above findings.

One aspect of the present invention provides a method for preparing fibers of an imide copolymer (A) from an amic acid copolymer (B), comprising:

(I) spinning an aqueous solution of the amic acid copolymer (B) to obtain fibers of the amic acid copolymer (B), and

(II) imidizing the fibers of the amic acid copolymer (B) obtained in step (I) to obtain fibers of the imide copolymer (A),

The imide copolymer (A) is an imide copolymer having imide side groups.

Another aspect of the present invention provides fibers obtainable by the process of the present invention.

In yet another aspect the present invention provides articles obtainable from the fibers of the present invention.

The technical solution for achieving the purpose of the present invention can be summarized as follows:

1. A method for preparing fibers of an imide copolymer (A) from an amic acid copolymer (B), comprising:

The imide copolymer (A) is an imide copolymer having imide side groups.

2. The method according to item 1, wherein the viscosity of the aqueous solution of the amic acid copolymer (B) is 500-15000 cp, preferably 500-12000 cp; and/or

The solid content of the aqueous solution of the amic acid copolymer (B) is 1 to 60% by weight, preferably 1.5 to 50% by weight, and more preferably 2 to 45% by weight.

3. The method according to item 1 or 2, wherein the spinning in step (I) is selected from wet spinning (a), dry spinning (b), solution blowing spinning (c) and electrospinning (d).

4. The method according to item 3, wherein the wet spinning (a) comprises (a-1) extruding an aqueous solution of the amic acid copolymer (B), (a-2) coagulating in a coagulation bath, and (a-3) optionally drying to spin.

5. The method according to item 3, wherein the dry spinning (b) comprises (b-1) extruding an aqueous solution of the amic acid copolymer (B), (b-2) coagulating with hot air and (b-3) drying to spin.

6. The method according to item 4 or 5, wherein the extrusion step comprises extruding an aqueous solution of the amic acid copolymer (B) through a spinneret, preferably the spinneret has a porous spinneret plate and a pore size of 0.01-0.8 mm, preferably 0.012-0.5 mm, more preferably 0.014-0.2 mm.

7. The method according to item 3, wherein the solution blow spinning (c) comprises blowing a jet of an aqueous solution of the amic acid copolymer (B) with hot air.

8. A method according to item 7, wherein an aqueous solution of the amide acid copolymer (B) in a nozzle is propelled by a syringe pump to produce a jet, preferably the propulsion speed of the syringe pump for a single nozzle is 50-2000 μl/min, more preferably 80-1200 μl/min, and the diameter of the nozzle mouth is 0.06 mm-0.6 mm.

9. The method according to item 7 or 8, wherein the temperature of the hot air is 70-250° C., preferably 90-180° C., and the flow rate is 1-100 m/s, preferably 10-50 m/s.

10. The method according to any one of items 1 to 9, wherein the imidization in step (II) is carried out at 110-220°C, or 140-160°C.

11. The method according to any one of items 1 to 10, wherein the imidization reaction time in step (II) is 0.7-6 h, or 0.8-5 h.

12. A method according to any one of items 1 to 11, wherein the imide copolymer (A) has at least one repeating unit (i) with an imide side group, preferably the molar amount of the repeating unit (i) is 15-75 mol%, or 35-65 mol%, based on the total amount of repeating units of the imide copolymer (A).

13. The process according to item 12, wherein the imide copolymer (A) has at least one repeating unit (i) bearing an imide side group and at least one further repeating unit (ii) different from the repeating unit (i), preferably the further repeating unit (ii) is selected from repeating units derived from the following monomers _{: C1} _- _C10 _alkyl esters of monoethylenically unsaturated C3-C8 monocarboxylic acids, amides of monoethylenically unsaturated _C3 - _C8 monocarboxylic acids, vinyl alkyl ethers having _C1 - _C8 alkyl groups, _C2 - _C22 monoolefins, _C4 - _C22 conjugated dienes, styrene, styrene substituted by one or more substituents selected from _C1 - _C12 alkyl, _C1 - _C12 alkoxy and halogen, vinyl esters of _C1 - _C20 carboxylic acids, vinylpyrrolidone, (meth)acrylonitrile, ethylenically unsaturated monomers containing hydroxyl groups, N-vinylformamide, vinylimidazole, allylbenzene, indene, methylindene and compounds containing furan rings,

or

The other repeating units (ii) are derived from at least one monomer containing a carbon-carbon unsaturated double bond of a reaction material derived from gasoline, _C4 fraction, _C5 fraction, _C8 fraction, _C9 fraction, coumarone resin raw material, or coal tar light fraction.

14. The process according to any one of items 1 to 13, wherein the nitrogen atom of the imide of the imide copolymer (A) carries a group R ¹ , wherein R ¹ is selected from H, C ₁ -C ₁₂ alkyl, C ₃ -C ₈ cycloalkyl, C ₁ - _C12 alkyl- _C3 - _C8 cycloalkyl, _C6-C10 _aryl , C1- _C12 alkyl- _C6 _- _C10 aryl, _C3 - _C9 heteroaryl or _C1 - _C12 alkyl- _C3 - _C9 heteroaryl, wherein the heteroaryl has 1 to 3 heteroatoms selected from N, O and S, preferably ^R1 is selected from H and _C1 - _C12 alkyl.

15. A method according to any one of items 1 to 14, wherein the amide acid copolymer (B) has at least one repeating unit (i') having an amide group and a carboxyl group and/or an ammonium salt thereof and at least one other repeating unit (ii), preferably at least one other repeating unit (ii) is as defined in item 13.

16. The method according to any one of items 1 to 15, wherein the number average molecular weight of the amic acid copolymer (B) is at least 20,000, preferably at least 25,000, or at least 30,000.

17. The method according to item 15 or 16, wherein the molar amount of the repeating unit (i') is 15-75 mol%, or 35-65 mol%, based on the total amount of the repeating units of the amic acid copolymer (B).

18. The process according to any one of items 1 to 17, wherein the amic acid copolymer (B) is derived from an anhydride copolymer (C), wherein the anhydride copolymer (C) has at least one repeating unit (i") bearing anhydride groups and at least one other repeating unit (ii), preferably at least one other repeating unit (ii) is as defined in item 13.

19. A process according to any one of items 1 to 18, wherein the amic acid copolymer (B) is obtained by reacting an anhydride copolymer (C) with ammonia or an amine, wherein the anhydride copolymer (C) has at least one repeating unit (i") bearing anhydride groups and at least one other repeating unit (ii), preferably at least one other repeating unit (ii) is as defined in item 13.

20. The method according to any one of items 1 to 19, wherein the aqueous solution of the amic acid copolymer (B) is prepared as follows:

dissolving the amic acid copolymer (B) in water; or

A method of reacting a solid of the anhydride copolymer (C) as defined in item 18 with ammonia or an amine and then dissolving the resulting amic acid copolymer (B) in water; or

An aqueous solution of the anhydride copolymer (C) as defined in item 18 is reacted with ammonia or an amine to obtain an aqueous solution of the amic acid copolymer (B).

21. The method according to any one of items 1 to 20, wherein the aqueous solution of the amic acid copolymer (B) in step (I) does not contain an organic crosslinking agent capable of undergoing a covalent crosslinking reaction with an amide and/or carboxyl group or an ammonium salt thereof.

22. Fiber obtainable by a process as claimed in any one of items 1 to 21.

23. The fiber according to item 22, wherein the fiber is insoluble in water.

24. Articles obtainable from the fibers of item 22 or 23.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an infrared spectrum of different polymers in Example 1; Curve 1: maleic anhydride copolymer; Curve 2: maleamic acid copolymer; Curve 3: maleimide copolymer;

FIG2(a) is a scanning electron micrograph of a coal tar light fraction-maleamic acid/styrene-maleamic acid copolymer fiber prepared by a solution blow spinning method in Example 2; FIG2(b) is a water contact angle of the fiber;

Figure 3(a) is a scanning electron microscope image of the fiber in Figure 2(a) after heat treatment; Figure 3(b) is the water contact angle of the fiber; Figure 3(c) is the TGA curve of the fiber; Figure 3(d) is the adsorption effect of the fiber on the dye (left) before adsorption (right) after adsorption;

FIG4 is a scanning electron micrograph of ultrahigh molecular weight styrene-maleimide copolymer fibers prepared by a solution blow spinning method in Example 5;

FIG5 is a scanning electron micrograph of styrene-maleimide copolymer fibers prepared by dry spinning in Example 7;

FIG6 is a scanning electron micrograph of styrene-maleimide copolymer fibers prepared by wet spinning in Example 10.

Detailed ways

Specific values disclosed herein for relevant features (including the endpoints of the disclosed ranges) can be combined with each other to form new ranges.

One aspect of the present invention relates to a method for preparing fibers of an imide copolymer (A) from an amic acid copolymer (B), comprising:

The imide copolymer (A) is an imide copolymer having imide side groups.

Step (I)

In one embodiment, the viscosity of the aqueous solution of the amic acid copolymer (B) in step (I) may be 500-15000 cp (e.g., 600 cp, 1000 cp, 2000 cp, 4000 cp, 6000 cp, 8000 cp, 10000 cp or 12000 cp), preferably 500-12000 cp, more preferably 1000-10000 cp or 1000-9000 cp.

The solid content of the aqueous solution of the amic acid copolymer (B) can be 1-60 wt % (e.g., 1, 2, 5, 8, 10, 15, 20, 30, 40 or 50 wt %), or 1-40 wt %, or 1.5-40 wt %, or 5-60 wt %, or 10-50 wt %, or 15-45 wt %, preferably 1.5-50 wt %, more preferably 2-45 wt %.

The temperature of the aqueous solution of the amic acid copolymer (B) may be 15-92°C (eg, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 90°C), preferably 20-90°C, preferably 30-70°C.

According to the present invention, the spinning in step (I) can be selected from wet spinning (a), dry spinning (b), solution blowing spinning (c) and electrospinning (d).

Wet spinning (a) and dry spinning (b)

In one embodiment, the spinning in step (I) is wet spinning (a). According to the present invention, wet spinning (a) may include (a-1) extruding an aqueous solution of the amic acid copolymer (B), (a-2) coagulating in a coagulation bath, and optionally (a-3) drying to spin.

In one embodiment, the spinning in step (I) is dry spinning (b). According to the present invention, dry spinning (b) may include (b-1) extruding an aqueous solution of the amic acid copolymer (B), (b-2) coagulating with hot air, and (b-3) drying to spin.

In wet spinning (a), the solid content of the aqueous solution of the amic acid copolymer (B) may preferably be 8-40 wt %, preferably 10-35 wt %. In wet spinning (a), the viscosity of the aqueous solution of the amic acid copolymer (B) may preferably be 1000-15000 cp, such as 1200-12000 cp, preferably 1500-10000 cp or 2000-9000 cp.

In dry spinning (b), the solid content of the aqueous solution of the amic acid copolymer (B) may preferably be 20-60 wt %, preferably 25-45 wt %. In dry spinning (b), the viscosity of the aqueous solution of the amic acid copolymer (B) may preferably be 1000-15000 cp, such as 1200-12000 cp, preferably 1500-10000 cp or 2000-9000 cp.

In one embodiment, the wet spinning (a) and the dry spinning (b) may include copolymerizing the amic acid The aqueous solution of material (B) is extruded through a spinneret, and preferably the spinneret has a porous spinneret. The pore size of the porous spinneret is 0.01-0.8mm (such as 0.01, 0.012, 0.014, 0.016, 0.018, 0.02, 0.025, 0.03, 0.04, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 or 0.5mm), preferably 0.012-0.5mm, more preferably 0.014-0.2mm. The porous spinneret can have 5-500 holes, or 10-400 holes.

In one embodiment, the pore size of the porous spinneret in step (a-1) is 0.03-0.8 mm, preferably 0.04-0.5 mm, more preferably 0.06-0.2 mm. In one embodiment, the pore size of the porous spinneret in step (b-1) is 0.01-0.1 mm, preferably 0.01-0.08 mm, more preferably 0.012-0.06 mm.

During the extrusion of the spinning solution (aqueous solution of the amic acid copolymer (B)), spinning can be carried out directly under normal pressure, or gas (preferably nitrogen) can be used to assist in injecting the spinning solution into the spinning manifold. The gas pressure can be 0.1-0.5 MPa, preferably 0.1-0.3 MPa.

In one embodiment, wet spinning (a) comprises extruding an aqueous solution of an amide acid copolymer (B) and passing it through an air layer, and then coagulating it in a coagulation bath. Preferably, the length of the air layer is 3-80 mm (such as 3, 5, 10, 20, 30, 40, 50, 60, 70 or 80 mm), or 5-60 mm, more preferably 10-40 mm.

In one embodiment, the coagulation bath in step (a-2) of wet spinning (a) is a poor solvent in which the amic acid copolymer (B) can be precipitated, and the poor solvent is preferably selected from aqueous sodium sulfate solution, C ₁ -C ₆ alkanol, C ₃ -C ₆ cycloalkanol, aromatic hydrocarbon, or a combination thereof. The concentration of the aqueous sodium sulfate solution is at least 300 g/L, or at least 350 g/L or at least 400 g/L. The C ₁ -C ₆ alkanol is preferably methanol, ethanol, propanol. The aromatic hydrocarbon is preferably selected from benzene substituted with 1, 2 or more C ₁ -C ₆ alkyl groups, preferably toluene and xylene.

According to the present invention, the temperature of the coagulation bath may be 15-60°C, preferably 20-40°C, more preferably 22-35°C.

According to the present invention, the coagulation bath is located in a coagulation bath tank having a length of 1-5 m (such as 1, 2, 3, 4 or 5 m).

According to the invention, the extrudate coagulated in step (a-2) is then optionally dried in step (a-3). If necessary, the product of step (a-2) (coagulated extrudate) is washed. The washing can be carried out with water.

In one embodiment, the drying in step (a-3) can be carried out at 50-98°C (e.g., 60, 70, 80, 90, 92, 95 or 98°C), preferably 60-95°C or 70-95°C.

According to the present invention, the dry spinning (b) comprises (b-1) extruding an aqueous solution of the amic acid copolymer (B), (b-2) coagulating with hot air and (b-3) drying to spin.

The step (b-2) of solidification by hot air and the step (b-3) of drying can be performed in one step.

In one embodiment, the temperature in step (b-2) and step (b-3) is 120-200°C, preferably 130-190°C.

In a preferred embodiment, step (b-2) and step (b-3) are carried out in a flowing air stream. The flowing air stream can be achieved by a fan, and the fan preferably has a rotation speed of 200-1500 r/min, preferably 600-1200 r/min.

In a preferred embodiment, step (b-2) and step (b-3) are carried out in a tunnel. Preferably, the length of the tunnel is 3-8 m, or 3-6 m. The above-mentioned flowing air may exist in this channel.

According to the present invention, wet spinning (a) and dry spinning (b) further comprise the step of winding the obtained fiber. The winding speed may be 5-200 m/min, preferably 10-100 m/min. Preferably, the winding speed in wet spinning (a) is 5-60 m/min (e.g., 10, 20, 30, 40, 50 m/min), preferably 10-50 m/min. Preferably, the winding speed in dry spinning (b) is 10-200 m/min (20, 40, 60, 80, 100, 120, 140, 160 or 180 m/min), preferably 30-100 m/min.

Solution blow spinning (c)

According to the present invention, the solution blow spinning (c) comprises blowing a jet of an aqueous solution of the amic acid copolymer (B) with hot air.

In solution blow spinning (c), the solid content of the aqueous solution of the amic acid copolymer (B) may be 1-50 wt % (e.g., 2, 4, 6, 8, 10, 15, 20, 30 or 40 wt %), preferably 2-40 wt %. In solution blow spinning (c), the viscosity of the aqueous solution of the amic acid copolymer (B) may preferably be 500-15000 cp, such as 500-10000 cp, preferably 500-8000 cp or 500-5000 cp.

In one embodiment, the aqueous solution of the amic acid copolymer (B) is propelled in the nozzle by a nozzle, for example, a syringe pump to produce a jet. The propulsion speed of the syringe pump for a single nozzle can be 50-2000 μl/min (e.g., 60, 80, 100, 150, 200, 300, 400, 500, 800, 1000, 1200, 1500 or 1800 μl/min), more preferably 80-1200 μl/min, such as 80-800 μl/min or 80-500 μl/min.

The nozzle diameter of the nozzle can be 0.06mm-0.60mm, such as 0.1mm-0.5mm or 0.15 mm-0.4mm.

The temperature of the hot air used for blowing may be 70-250°C (e.g., 80°C, 90°C, 100°C, 120°C, 150°C, 160°C, 180°C, 200°C or 220°C), preferably 110-180°C or 120-180°C.

The flow rate of the hot air used for blowing may be 1-100 m/s (e.g. 2, 5, 10, 15, 20, 30, 50 or 80 m/s), such as 5-80 m/s, preferably 10-50 m/s.

According to the present invention, a plurality of nozzles may be used in parallel, for example, a plurality of nozzles may be used in parallel.

According to the present invention, the fibers of the blown amic acid copolymer (B) are collected by a collecting device, which can be a mesh, a hollow cage or a drum, and the collected products are micro-nano fibers in the form of a mass or a film.

In one embodiment, the fiber can also be blown into a coagulation bath. The coagulation bath is a poor solvent in which the amic acid copolymer (B) can be precipitated, preferably the poor solvent is selected from sodium sulfate aqueous solution, alcohol, aromatic hydrocarbon or a combination thereof. The concentration of the sodium sulfate aqueous solution is at least 300 g/L, or at least 350 g/L or at least 400 g/L. The alcohol can be selected from C ₁ -C ₆ alkanol and C ₃ -C ₆ cycloalkanol, preferably methanol, ethanol, propanol. The aromatic hydrocarbon is preferably selected from benzene substituted with 1, 2 or more C ₁ -C ₆ alkyl groups, preferably toluene and xylene.

Electrospinning (d): According to the present invention, electrospinning can be performed by methods known in the art.

Step (II)

According to the present invention, in step (II), the fibers of the amic acid copolymer (B) obtained in step (I) are imidized to obtain fibers of the imide copolymer (A).

The imidization in step (II) may be carried out at 110-220°C, 115-200°C, preferably 120-180°C, 140-180°C or 140-160°C.

The imidization time in step (II) may be 0.7-6 h (eg, 0.8 h, 0.9 h, 1 h, 2 h, 3 h, 4 h or 5 h), or 0.8-5 h.

The fiber of the amide acid copolymer (B) can be heated to the above heating temperature at one time; or programmed heating can be adopted, for example, maintaining at a temperature of 90-120°C for 1-2 hours, then heating to the above heating temperature (such as 120-180°C, 140-180°C or 140-160°C) at a rate of 1-2°C/min, and keeping warm for 0.5-3 hours to carry out imidization.

In the present invention, the imide conversion rate is preferably 70% or more (e.g., 75%, 80%, 85%, 90%, 95% or 98%), more preferably 90% or more, and even more preferably 95% or more. In the present invention, the imide conversion rate refers to the percentage of the amic acid units that form the imide units in the amic acid copolymer (B) to the total amic acid units. The imide conversion rate is usually determined by an infrared spectrometer (e.g., Nexus 670, Nicolet Corporation, USA).

By the method of the present invention, the fiber of the imide copolymer (A) can be directly obtained. The fiber of the imide copolymer (A) has a diameter in the micrometer range, the submicrometer range or the nanometer range. The diameter of the fiber is, for example, 50nm to 100μm (such as 80nm, 100nm, 200nm, 500nm, 800nm, 1μm, 10μm, 20μm, 50μm or 80μm), such as 50nm to 200nm, 200nm to 500nm, 500nm to 10μm, 10μm to 100μm, or 80nm to 80μm.

Imidene copolymer (A)

According to the present invention, the imide copolymer (A) is an imide copolymer having imide side groups, and preferably the imide copolymer (A) has at least one repeating unit (i) having imide side groups. The imide side groups on the imide copolymer (A) may, for example, include the following structure:

wherein R ¹ is as defined below.

In one embodiment, the imide copolymer (A) has at least one repeating unit (i) carrying an imide side group and at least one further repeating unit (ii) different from the repeating unit (i), preferably the further repeating unit (ii) is selected from the repeating units derived from the following monomers: _C1 - _C10 _alkyl esters of monoethylenically unsaturated _C3 -C8 monocarboxylic acids, amides of monoethylenically unsaturated _C3 - _C8 monocarboxylic acids, vinyl alkyl ethers having _C1 - _C8 alkyl groups, _C2 - _C22 monoolefins, _C4 - _C22 conjugated dienes, styrene, styrene substituted by one or more substituents selected from _C1 - _C12 alkyl, _C1 - _C12 alkoxy and halogen, vinyl esters of _C1 - _C20 carboxylic acids, vinylpyrrolidone, (meth)acrylonitrile, ethylenically unsaturated monomers containing hydroxyl groups, N-vinylformamide, vinylimidazole, allylbenzene, indene, methylindene and compounds containing furan rings,

or

The other repeating units (ii) are derived from at least one monomer containing a carbon-carbon unsaturated double bond of a reaction material derived from gasoline, _C4 fraction, _C5 fraction, _C8 fraction, _C9 fraction, coumarone resin raw material or coal tar light fraction.

Details regarding the monomers and reaction materials for these other repeating units (ii) are described in detail below as for the anhydride copolymer (C).

Those skilled in the art will appreciate that the expression "derived from" includes both the case where the repeating unit is directly formed from the monomer corresponding to the repeating unit and the case where the repeating unit is not directly formed from the monomer corresponding to the repeating unit. It can be obtained from the polymerization of acrylic acid or by polymerization of acrylic acid esters followed by hydrolysis.

In a preferred embodiment of the present invention, the other repeating units (ii) of the imide copolymer (A) are derived from at least one monomer containing carbon-carbon unsaturated double bonds of a reaction material such as gasoline, _C4 fraction, _C5 fraction, _C8 fraction, _C9 fraction, coumarone resin raw material or coal tar light fraction. As described in detail below with respect to the anhydride copolymer (C), the monomers containing carbon-carbon unsaturated double bonds in gasoline, _C4 fraction, _C5 fraction, _C8 fraction, _C9 fraction, coumarone resin raw material or coal tar light fraction can form the other repeating units (ii) of the imide copolymer (A) after polymerization.

Molecular weights used herein are number average molecular weights unless otherwise indicated.

In one embodiment, the number average molecular weight of the imide copolymer (A) is at least 20,000, at least 30,000, at least 50,000, at least 80,000, at least 90,000 or at least 100,000. The upper limit of the number average molecular weight of the imide copolymer (A) may be, for example, 2,000,000, or 1,800,000 or 1,600,000. In one embodiment, the number average molecular weight of the imide copolymer (A) is 20,000-2,000,000, preferably 25,000-1,800,000, or 30,000-1,600,000.

In one embodiment, the fiber has two or more imide copolymers (A) of different molecular weights and/or different structures. In the two or more imide copolymers (A) of different molecular weights, the sum of the weight fraction of each imide copolymer × the molecular weight of the imide copolymer should meet the above molecular weight requirements. For example, if two imide copolymers (A) with molecular weights of 10,000 and 90,000 are used in a weight ratio of 1:1, the sum of the weight fraction of each imide copolymer × the molecular weight of the imide copolymer is 50,000 (=0.5×1+0.5×9), thereby meeting the above molecular weight requirements.

In one embodiment, the nitrogen atom of the imide of the imide copolymer (A) carries a group R ¹ , wherein R ¹ is selected from H, C ₁ -C ₁₂ alkyl, C ₃ -C ₈ cycloalkyl, C ₁ -C ₁₂ alkyl-C ₃ -C ₈ cycloalkyl, C ₆ -C ₁₀ aryl, C ₁ -C ₁₂ alkyl-C ₆ -C ₁₀ aryl, C ₃ -C ₉ heteroaryl or C ₁ -C ₁₂ alkyl-C ₃ -C ₉ heteroaryl, preferably H and C ₁ -C ₁₂ alkyl, more preferably H and C ₁ -C ₆ alkyl, more preferably H and C ₁ -C ₄ alkyl (such as methyl, ethyl, propyl and butyl). In this context, the heteroaryl group may have 1-3 (such as 1, 2 or 3) heteroatoms selected from N, O and S. Examples of aryl groups include phenyl and naphthyl.

In one embodiment, the amount of repeating unit (i) may be 10-80 wt%, such as 20-75 wt%, or 30-70 wt%, or 35-65 wt%, based on the weight of the imide copolymer (A).

In one embodiment, the molar amount of repeating units (i) can be 15-75 mol% (e.g., 20 mol%, 30 mol%, 40 mol%, 50 mol%, 60 mol% or 70 mol%), such as 20-75 mol% or 30-70 mol% or 35-65 mol%, based on the total amount of repeating units of the imide copolymer (A).

Amic acid copolymer (B)

According to the present invention, the amic acid copolymer (B) has at least one repeating unit (i') with an amide group and a carboxyl group and/or an ammonium salt thereof and at least one other repeating unit (ii). According to the present invention, the at least one other repeating unit (ii) is as defined above. Details about the monomers and reaction materials of these other repeating units (ii) are described in detail below as for the anhydride copolymer (C).

According to the present invention, the amide group on the repeating unit (i') and the carboxyl group and/or its ammonium salt can form an imide group, that is, form an imide side group on the repeating unit (i) of the imide copolymer (A).

In one embodiment, the number average molecular weight of the amic acid copolymer (B) corresponds to the number average molecular weight of the imide copolymer (A). For example, the number average molecular weight of the amic acid copolymer (B) is at least 20,000, at least 30,000, at least 50,000, at least 80,000, at least 90,000 or at least 100,000. The upper limit of the number average molecular weight of the amic acid copolymer (B) can be, for example, 2,000,000, or 1,800,000 or 1,600,000. In one embodiment, the number average molecular weight of the amic acid copolymer (B) is 20,000-2,000,000, preferably 25,000-1,800,000, or 30,000-1,600,000.

In the method of the present invention, two or more amic acid copolymers (B) may be used. The two or more amic acid copolymers (B) may have different structures (such as repeating units) and/or different number average molecular weights.

In the method of the present invention, two or more amic acid copolymers (B) with different molecular weights may be used. In the two or more amic acid copolymers (B) with different molecular weights, the sum of the weight fraction of each amic acid copolymer x the molecular weight of the amic acid copolymer should meet the above molecular weight requirements. For example, if two amic acid copolymers (B) with molecular weights of 10,000 and 90,000 are used in a weight ratio of 1:1, the sum of the weight fraction of each amic acid copolymer × the molecular weight of the amic acid copolymer is 50,000 (=0.5×1+0.5×9), thus satisfying the above molecular weight requirement.

In one embodiment, the nitrogen atom of the amide of the amic acid copolymer (B) carries, in addition to one H atom, a group R ¹ , wherein R ¹ is as defined above.

In one embodiment, the amount of repeating unit (i') may be 10-82 wt%, e.g., 20-78 wt%, or 30-72 wt%, or 35-68 wt%, based on the weight of the amic acid copolymer (B).

In one embodiment, the molar amount of the repeating unit (i') may be 15-75 mol%, e.g., 20-75 mol%, or 30-70 mol% or 35-65 mol%, based on the total amount of the repeating units of the amic acid copolymer (B).

Acid anhydride copolymer (C)

In one embodiment, the amic acid copolymer (B) is derived from an anhydride copolymer (C), wherein the anhydride copolymer (C) has at least one repeating unit (i") bearing an anhydride group and at least one other repeating unit (ii).

According to a preferred embodiment of the present invention, the anhydride groups on the anhydride copolymer (C) are introduced into the anhydride copolymer (C) by polymerization of at least one monomer having a carbon-carbon unsaturated double bond and anhydride groups. The monomer having a carbon-carbon unsaturated double bond and anhydride groups can be selected from monoethylenically unsaturated dicarboxylic anhydrides having 4 to 8 carbon atoms, preferably maleic anhydride, itaconic anhydride, citraconic anhydride, methylenemalonic anhydride and mixtures thereof, more preferably maleic anhydride.

The other repeating units (ii) of the acid anhydride copolymer (C) are as described above for the other repeating units (ii) of the copolymer (A), preferably the other repeating units (ii) are selected from repeating units derived from the following monomers: _C1 _- _C10 _alkyl esters of monoethylenically unsaturated C3-C8 monocarboxylic acids, amides of monoethylenically unsaturated _C3 - _C8 monocarboxylic acids, vinyl alkyl ethers having _C1 - _C8 alkyl groups, _C2 - _C22 monoolefins, _C4 - _C22 conjugated dienes, styrene, styrene substituted with one or more substituents selected from _C1 - _C12 alkyl groups, _C1 - _C12 alkoxy groups and halogens, vinyl esters of _C1 - _C20 carboxylic acids, vinyl pyrrolidone, (meth)acrylonitrile, ethylenically unsaturated monomers containing hydroxyl groups, N-vinylformamide, vinylimidazole, allylbenzene, indene, methylindene and compounds containing furan rings.

or

The other repeating units (ii) are derived from gasoline, _C4 fraction, _C5 fraction, _C8 fraction, _C9 fraction, At least one monomer containing a carbon-carbon unsaturated double bond in the reaction materials of the raw materials of the coal tar light fraction, the coumarone resin raw material or the coal tar light fraction.

As examples of _C1 - _C10- alkyl esters of monoethylenically unsaturated _C3 - _C8 -monocarboxylic acids, mention may be made of _C1 _- C10-alkyl (meth)acrylates, in particular methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate or mixtures thereof.

Mention may be made, as examples of monoethylenically unsaturated C ₃ -C ₈ monocarboxylic acids, of acrylic acid, methacrylic acid, crotonic acid and vinylacetic acid, preference being given to acrylic acid and methacrylic acid.

Mention may especially be made, as examples of amides of monoethylenically unsaturated C ₃ -C ₈ -monocarboxylic acids, of (meth)acrylamide.

As the vinyl alkyl ether having a C ₁ -C ₈ alkyl group, preferably there may be mentioned vinyl alkyl ether having a C ₁ -C ₄ alkyl group, such as methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, n-butyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl ether, isopentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether and 2-ethylhexyl vinyl ether.

The _C2 - _C22 monoolefins can be alkenes and cycloolefins, for example, alkenes having 2-20 carbon atoms, such as 2-12 carbon atoms, or 2-8 carbon atoms, such as ethylene, propylene, butene, 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene; cycloolefins having 5-20 carbon atoms, preferably 5-12 or 5-8 carbon atoms, such as cyclopentene, cyclohexene, cycloheptene and the like; dihydrobicycloolefins having 8-20 carbon atoms, preferably 8-16 or 8-12 carbon atoms, in particular dihydrodicyclopentadiene (such as 2,3-dihydrodicyclopentadiene), dihydromethyldicyclopentadiene and dihydrodimethyldicyclopentadiene, etc.

The _C4 - _C22 conjugated diene may be, for example, a _C4 - _C16 conjugated diene or a _C5 - _C16 conjugated diene, a _C4 - _C8 conjugated diene or a _C5 - _C8 conjugated diene. Examples of these conjugated dienes include 1,3-butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, cyclopentadiene, methylcyclopentadiene and 1,3-cyclohexadiene.

As for styrene substituted with one or more substituents selected from C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy and halogen, the alkyl or alkoxy group preferably has 1 to 10 carbon atoms, such as 1 to 4 carbon atoms; the halogen group preferably has chlorine and bromine. As specific examples, vinyltoluene (such as α-methylstyrene and p-methylstyrene), α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene, p-methoxystyrene, chlorostyrene and bromostyrene can be mentioned.

As examples of vinyl esters of C ₁ -C ₂₀ carboxylic acids, mention may be made of vinyl laurate, vinyl stearate, Vinyl propionate, vinyl neodecanoate, and vinyl acetate.

The ethylenically unsaturated monomers containing a hydroxyl group include, for example, C ₁ -C ₁₀ hydroxyalkyl (meth)acrylates such as hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and 3-hydroxypropyl methacrylate.

Examples of the furan ring-containing compound include furan, dihydrofuran and monomers in which the furan ring and the dihydrofuran ring are substituted with one or more (e.g., 2 to 4) substituents selected from C ₁ -C ₁₂ alkyl and C ₁ -C ₁₂ hydroxyalkyl groups, such as furfuryl alcohol. The furan ring may be further condensed with a benzene ring, such as methylbenzofuran.

In a preferred embodiment of the present invention, the reaction mass comprising the monomer containing the at least one carbon-carbon unsaturated double bond and saturated hydrocarbons, other impurities not participating in polymerization, such as gasoline, C ₄ fractions, C ₅ fractions, C ₈ fractions, C ₉ fractions, coumarone resin raw materials or coal tar light fractions can be used directly without separation. According to this preferred embodiment, the anhydride copolymer (C) can be a copolymer formed by at least one monomer having carbon-carbon unsaturated double bonds and anhydride groups and at least one monomer containing carbon-carbon unsaturated double bonds of the reaction mass derived from such as gasoline, C ₄ fractions, C ₅ fractions, C ₈ fractions, C ₉ fractions, coumarone resin raw materials or coal tar light fractions. When using these reaction masses to form the anhydride copolymer (C) (such as via free radical polymerization), the components outside the monomer containing carbon-carbon unsaturated double bonds in these reaction masses can be used as solvents in the preparation process. When using these fractions as reaction masses, the cost of fiber of the present invention can be further reduced.

As the _C4 fraction, there may be mentioned the by-product produced as a by-product of producing ethylene by petroleum cracking or catalytic cracking, which generally contains components such as isobutylene, 1-butene-1, 2-butene and butane.

The _C4 fraction may have the following specific composition:

Table 1

The _C5 fraction is usually a _C5 fraction from petroleum cracking. The _C5 fraction usually contains about 45-55% of diolefins and 8-15% of monoolefins. Other components in the _C5 fraction include 18-25% of alkanes, about 1% of alkynes, 10-20% of _C4 , benzene and other components.

The _C5 fraction may have the following specific composition:

Table 2

The _C8 and _C9 fractions are mainly derived from the steam cracking process for producing ethylene and the naphtha platinum reforming process, and some of them are derived from toluene disproportionation or alkyl transfer products and coal tar.

The _C8 fraction generally contains 22-35% of monoolefins, such as styrene, allylbenzene, vinyltoluene, indene, and methylindene. Other components in the _C8 fraction include 45-55% of aromatics and about 20% of other unknown components.

The _C8 fraction may have the following specific composition:

Table 1

The _C9 fraction usually contains 20-30% of monoolefins (such as styrene, allyl benzene, vinyl methyl ether, etc.) Benzene, indene), 8-15% dienes. Other components in the _C9 fraction usually include about 5% alkanes, 40-50% aromatics, and about 10% other unknown components. The _C9 fraction can have the following specific composition:

Table 2

The light oil components in coal tar mainly contain styrene, α-methylstyrene, alkylbenzene, vinyltoluene, dicyclopentadiene, benzofuran, indene, methylindene and methylbenzofuran, etc. The light fraction of coal tar can have the following specific composition:

table 3

The polymerization of the monomer having carbon-carbon unsaturated double bonds and anhydride groups with other monomers containing carbon-carbon unsaturated double bonds for preparing the anhydride copolymer (C) can be carried out using an oil-soluble free radical initiator. The oil-soluble free radical initiator includes, for example, an azo initiator or a peroxide initiator. The azo initiator includes: azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate etc.; the peroxide initiator includes: dibenzoyl peroxide, diisopropyl peroxide, di(2,4-dichlorobenzoyl) peroxide, di-tert-butyl peroxide, dodecyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate and dicyclohexyl peroxydicarbonate, etc. The amount of the initiator used is 0.05-10% by weight, preferably 0.5-6% by weight, based on the weight of the monomer.

The polymerization reaction can be carried out in the presence of a solvent. The solvent can include aromatic hydrocarbons, mixtures of alkanes and ketones, carboxylates, mixtures of alkanes and aromatic hydrocarbons, mixtures of aromatic hydrocarbons and carboxylates, or mixtures of alkanes and carboxylates, or mixtures of alkanes, aromatic hydrocarbons and carboxylates.

As examples of the aromatic hydrocarbons, toluene, xylene, ethylbenzene and the like may be mentioned.

The carboxylic acid ester may include _C1 - _C8 alkyl esters, phenyl esters or benzyl esters of _C1 - _C6 carboxylic acids and _C1 - _C8 alkyl esters of aromatic carboxylic acids having 6-10 carbon atoms. Specific examples include ethyl formate, propyl formate, isobutyl formate, amyl formate, ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, isoamyl acetate, benzyl acetate, phenyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, isobutyl butyrate, isoamyl butyrate, ethyl isobutyrate, ethyl isovalerate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate, ethyl phenylacetate, propyl phenylacetate, butyl phenylacetate, isoamyl phenylacetate and the like ester solvents.

The ketone in the mixture of alkane and ketone can be selected from acetone, butanone, cyclohexanone, methyl isobutyl ketone, methyl isopropyl ketone, and the alkane can be selected from n-pentane, n-hexane, cyclohexane, n-heptane, n-octane and isooctane, etc. In the mixture of alkane and ketone, ketone usually accounts for 5-65% by volume.

The polymerization reaction can be carried out in the presence of an inert gas such as nitrogen. The polymerization temperature is usually 55-120°C, preferably 60-100°C; the polymerization time is usually 1-12 hours, preferably 2-8 hours. After the polymerization reaction, the obtained anhydride copolymer (C) can be separated and dried.

In a preferred embodiment, the polymerization reaction is carried out by precipitation polymerization. The precipitation polymerization can be carried out by selecting a solvent that can dissolve the monomers but cannot dissolve the obtained anhydride copolymer (C). Through precipitation polymerization, the anhydride copolymer (C) can be directly obtained in powder form.

According to the present invention, if gasoline, _C4 fraction, _C5 fraction, _C8 fraction, _C9 fraction, coumarone or coal tar light fraction is used as the reaction material, the unreacted alkane or aromatic mixture after the reaction is completed can be separated by simple distillation to obtain various high value-added solvents and industrial raw materials.

According to the present invention, the anhydride copolymer (C) can be reacted with ammonia or amine to obtain an amic acid Copolymer (B).

The number average molecular weight of the acid anhydride copolymer (C) usually corresponds to the number average molecular weight of the imide copolymer (A).

The amount of repeating unit (i") corresponds to the amount of repeating unit (i). In one embodiment, the amount of repeating unit (i") may be 10-75 wt%, such as 20-70 wt%, or 30-65 wt% or 35-60 wt%, based on the weight of the anhydride copolymer (C).

In one embodiment, the molar amount of the repeating unit (i") may be 15-75 mol%, such as 20-75 mol%, or 30-70 mol% or 35-65 mol%, based on the total amount of repeating units of the anhydride copolymer (C).

According to the present invention, no organic crosslinking agents such as polyols, polyamines, polyalkanolamines or mixtures thereof which are capable of covalently crosslinking with the anhydride groups in the anhydride copolymer (C) are used in the process of the present invention.

Preparation of amide acid copolymer (B) from anhydride copolymer (C)

In one embodiment, the amic acid copolymer (B) is obtained by reacting an anhydride copolymer (C) with ammonia or an amine, wherein the anhydride copolymer (C) has at least one repeating unit (i") carrying an anhydride group and at least one other repeating unit (ii).

Ammonia can be used in the form of aqueous ammonia or ammonia gas.

The structure of the amine corresponds to the group ^R1 carried by the nitrogen atom of the imide of the imide copolymer (A). As described above, ^R1 is selected from H, _C1 - _C12 alkyl, _C3 - _C8 cycloalkyl, _C1 - _C12 alkyl- _C3 - _C8 cycloalkyl, _C6 - _C10 aryl, _C1 - _C12 alkyl- _C6 - _C10 aryl, _C3 - _C9 heteroaryl or _C1 - _C12 alkyl- _C3 - _C9 heteroaryl, preferably H and _C1 - _C12 alkyl, more preferably H and _C1 - _C6 alkyl, more preferably H and _C1 - _C4 alkyl (such as methyl, ethyl, propyl and butyl). In this context, the heteroaryl group may have 1-3 (such as 1, 2 or 3) heteroatoms selected from N, O and S.

For example, when ^R1 is methyl, the amine is methylamine.

According to the present invention, the amine may have the structure of formula (I):

R ¹ -NH ₂ (I)

wherein R ¹ is as defined above.

The temperature of the reaction of the anhydride copolymer (C) with ammonia or amine is usually below 100°C, preferably 15-70°C. The reaction time is usually 0.5-10 hours, preferably 1-6 hours. The amination rate is usually not less than 90%, preferably not less than 95%, more preferably not less than 98%, such as 100%. The amination rate of the anhydride groups of the anhydride copolymer (C) can be determined by titration.

The anhydride copolymer (C) may be in the form of a powder before reacting with ammonia or an amine. Preferably, the anhydride copolymer (C) in powder form can be prepared by precipitation polymerization. The anhydride copolymer (C) in powder form can also be obtained by grinding the anhydride copolymer (C) (e.g., block) into a powder form. The average particle size of the anhydride copolymer (C) in powder form can be 0.01-10 μm, preferably 0.05-8 μm, more preferably 0.1-5 μm. The average particle size of the anhydride copolymer (C) in powder form can be 0.01-10 μm, preferably 0.05-8 μm, more preferably 0.1-5 μm.

The reaction time of the solid (powder) anhydride copolymer (C) with ammonia is usually 2 to 300 minutes (eg, 5, 10, 30, 60, 120, 180 or 240 minutes), such as 5 to 120 minutes.

According to the present invention, the aqueous solution of the amic acid copolymer (B) can be prepared as follows:

dissolving the amic acid copolymer (B) in water; or

The solid anhydride copolymer (C) is reacted with ammonia or an amine, and then the obtained amic acid copolymer (B) is dissolved in water; or

The aqueous solution of the acid anhydride copolymer (C) is reacted with ammonia or amine to obtain an aqueous solution of the amic acid copolymer (B).

The solvent that can dissolve the amic acid copolymer (B) is as described above.

If necessary, the aqueous solution of the amic acid copolymer (B) can be degassed before spinning. The degassed method can be selected from normal pressure static degassed and vacuum degassed. The degassed time is usually 1-15 hours, preferably 2-10 hours. The degassed temperature is generally 30-99° C., preferably 50-80° C. For example, a spinning solution with a solid content of 15% by weight can be degassed by standing at 80° C. for 3 hours.

According to the present invention, the aqueous solution of the amic acid copolymer (B) in step (I) does not contain an organic crosslinking agent capable of undergoing a covalent crosslinking reaction with amide and/or carboxyl groups or their ammonium salts, such as polyols, polyamines, polyalkanolamines or mixtures thereof.

One aspect of the present invention relates to fibers of the imide copolymer (A) obtainable by the process of the present invention. The fibers of the imide copolymer (A) have a diameter in the micrometer range, the submicrometer range, or the nanometer range. The diameter of the fiber is, for example, 50 nm to 100 μm (e.g., 80 nm, 100 nm, 200 nm, 500 nm, 800 nm, 1 μm, 10 μm, 20 μm, 50 μm or 80 μm), such as 50 nm to 200 nm, 200nm to 500nm, 500nm to 10μm, 10μm to 100μm, or 80nm to 80μm.

The fibers may be in the form of fiber films, nonwoven fabrics or monofilaments.

According to the invention, the fibers are insoluble in water.

The present invention also relates to products that can be obtained from the fiber of the present invention. The products can be, for example, fiber membranes, nonwoven fabrics, filter materials, water-absorbing materials or adsorbent materials, yarns, textiles, clothing products, products in the fields of environmental protection and biomedicine, for example, the fiber can be made into various hemostatic cotton, bandages, gauze and surgical sutures, and can also be made into substitute materials for human tissues, such as "artificial muscles" and "artificial organs", as well as products in the field of construction.

The maleimide copolymer fiber of the present invention can be used in various applications (for example, fiber membranes, nonwoven fabrics, filter materials, water-absorbing materials, adsorbent materials, etc.) while maintaining the fiber state.

The method of the invention is simple, efficient, economical, environmentally friendly and can continuously prepare water-resistant high-performance imide copolymer fibers. The method of the invention can also prepare fibers in the form of monofilaments, films or non-woven fabrics, and the obtained fibers have excellent adsorption properties, especially for dyes; and the obtained fibers have excellent mechanical properties.

Example

The technical scheme in the present invention is further described below in conjunction with the specific embodiments of the present invention, but it should not be understood as limiting the scope of protection of the present invention. The embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiments listed in the present invention, other embodiments proposed by other technicians in the field without creative work all belong to the scope of protection of the present invention. Unless otherwise specified, the percentages in the embodiments are percentages by weight, and the parts in the embodiments are parts by weight.

In Examples 7-10, the single fiber tensile test was performed using an XQ-1AN fiber strength and elongation tester (see Figure 2), and the test standard used was GB/T 14337-2008.

The spinning machine device in Example 1-6 (solution jet spinning) includes: an air pump, an injection pump, a nozzle, an oil bath pot and a fiber collecting device. During the spinning process, the polymer solution is stretched by a high-speed hot air flow and solidified into fibers as the solution evaporates.

The spinning machine in Examples 7-9 (dry spinning) is Lingxian LH-GF-2000 spinning machine (produced by Changzhou Lingxian Textile Machinery Co., Ltd.).

The spinning machine of Example 10 (wet spinning) is a BJ-SFFS-00-01 spinning machine (produced by Chengdu Shengda Xingye Chemical Engineering Co., Ltd.).

Example 1

10g of coal tar light fraction-maleic anhydride copolymer (number average molecular weight 10000, molar content of maleic anhydride unit is 53% as determined by titration) is added to a reaction flask, and 2g of ammonia is introduced, and after reacting at room temperature for 20min, a coal tar light fraction-maleamic acid copolymer (the molar percentage of maleic anhydride monomer units that have been aminolyzed in the copolymer is 99% as measured by acid-base titration, and the molar content of maleamic acid units is 52%) is obtained. 10g of styrene-maleic anhydride copolymer (number average molecular weight 110000, molar content of maleic anhydride unit is 52%) is added to a reaction flask, and 2g of ammonia is introduced, and reacting at room temperature for 25min, a styrene-maleamic acid copolymer (the molar percentage of maleic anhydride monomer units that have been aminolyzed in the copolymer is 98% as measured by acid-base titration, and the molar content of maleamic acid units is 51%) is obtained.

10 g of the obtained coal tar light fraction-maleamic acid copolymer, 10 g of the obtained styrene-maleamic acid copolymer and 47 g of water were stirred at 70°C for 0.5 hour to obtain a coal tar light fraction-maleamic acid copolymer/styrene-maleamic acid copolymer spinning solution with a solid content of 30% and a spinning solution viscosity of 2600cp.

After the spinning solution was statically degassed at 80°C for 4 hours, it was poured into a 10mL nozzle with a nozzle diameter of 0.21mm, and the spinning solution was propelled by an injection pump at a propulsion speed of 200μL/min. A mesh was used as a receiving substrate, and the distance from the receiving substrate to the spinneret was 30cm; at the same time, hot air at 150°C and a flow rate of 20m/s was used to blow the polymer solution jet. The average diameter of the obtained coal tar light fraction-maleamic acid/styrene-maleamic acid copolymer fiber was 2040nm.

The obtained hydrophilic coal tar light fraction-maleamic acid/styrene-maleamic acid copolymer fiber was heat-treated at 140°C for 1 hour, and the obtained fiber was transformed into a hydrophobic imide copolymer fiber (the molar content of maleimide unit was 51%), and the diameter remained unchanged at 2040nm.

The infrared spectra of the maleic anhydride copolymer, the maleamic acid copolymer and the maleimide copolymer are shown in FIG1 .

Curve 1 in Figure 1 is the infrared spectrum of maleic anhydride copolymer, at 1860cm ^-1 and 1780cm ^-1 The peaks are the two carbonyl C=O stretching vibration peaks on the anhydride, and the strong absorption at 940 cm ^-1 is unique to the five-membered ring anhydride;

Curve 2 in Figure 1 is the infrared spectrum of the maleamic acid copolymer, with the asymmetric and symmetric stretching vibration peaks of -NH ₂ at 3200 cm ^-1 and the stretching vibration peak of amide C=O at 1650 cm ^-1 . The characteristic peaks of the anhydride group corresponding to the original maleic anhydride copolymer basically disappeared;

Curve 3 in FIG. 1 is an infrared spectrum of the maleimide copolymer, in which characteristic absorptions of cyclic imide appear at 1770 cm ^-1 and 1710 cm ^-1 , and characteristic absorption of CNC structure appears at 1350 cm ^-1 .

Example 2

10g of coal tar light fraction-maleic anhydride copolymer (number average molecular weight 10000, maleic anhydride unit molar content of 53%) was added to a reaction flask, and 2g of ammonia was introduced, and after reacting at room temperature for 20min, a coal tar light fraction-maleamic acid copolymer (the molar percentage of maleic anhydride monomer units that have been aminolyzed in the copolymer measured by acid-base titration is 99%, and the molar content of maleamic acid units is 52%). 10g of ultra-high molecular weight styrene-maleic anhydride copolymer (number average molecular weight 1500000, maleic anhydride unit molar content of 51%) was added to a reaction flask, and 2g of ammonia was introduced, and reacted at room temperature for 30min to obtain an ultra-high molecular weight styrene-maleamic acid copolymer (the molar percentage of maleic anhydride monomer units that have been aminolyzed in the copolymer is 97%, and the molar content of maleamic acid units is 49%).

15.3 parts of the obtained coal tar light fraction-maleamic acid copolymer, 1.7 parts of the obtained ultra-high molecular weight styrene-maleamic acid copolymer, and 83 parts of water were stirred at 70°C for 1 hour to obtain a coal tar light fraction-maleamic acid copolymer/ultra-high molecular weight styrene-maleamic acid copolymer spinning solution with a solid content of 17% and a spinning solution viscosity of 1400cp.

After the spinning solution was statically degassed at 80°C for 4 hours, it was poured into a 10mL nozzle with a nozzle diameter of 0.21mm, and the spinning solution was propelled by an injection pump at a propulsion speed of 200μL/min. A mesh was used as a receiving substrate, and the distance from the receiving substrate to the spinneret was 30cm; at the same time, the polymer solution jet was blown with hot air at 150°C and a flow rate of 20m/s. The obtained coal tar light fraction-maleamic acid/ultra-high molecular weight styrene-maleamic acid copolymer fiber had an average diameter of 1500nm (as shown in Figure 2a), and showed hydrophilicity with a water contact angle of 57° (as shown in Figure 2b), where the water contact angle was measured by Dataphysics OCA200.

The obtained hydrophilic coal tar light fraction-maleamic acid/ultra-high molecular weight styrene-maleamic acid copolymer fiber was heat-treated at 140°C for 3h, and the obtained fiber was transformed into an imide copolymer fiber (the molar content of maleimide unit was 51%). The fiber morphology remained unchanged, and the average diameter was still 1500nm (as shown in Figure 3a). The fiber was transformed into a hydrophobic fiber with a water contact angle of 136° (as shown in Figure 3b). The TGA test results of this fiber are shown in Figure 3c. Its initial decomposition temperature is 320°C and the fastest decomposition temperature is 396°C. The TGA data was measured by the NETZSCH TG209 instrument, with a test range of 50°C to 800°C and a heating rate of 20°C/min.

0.1g of the obtained imide copolymer fiber was immersed in 10mL, 0.1g/L rhodamine B aqueous solution and adsorbed for 180min without stirring. The color of the solution changed from pink to colorless (as shown in Figure 3d). The absorbance at 554nm before and after adsorption was measured by an ultraviolet spectrophotometer (Agilent Cary 60UV-Vis). It can be seen that the dye content before adsorption was 100% and the dye content after adsorption was 1.5%. It can be seen that the fiber has a good adsorption effect on the dye, and the adsorption rate can reach 98.5%.

Example 3

13.5 parts of coal tar light fraction-maleamic acid copolymer prepared according to Example 2, 1.5 parts of ultra-high molecular weight styrene-maleamic acid copolymer prepared according to Example 2, and 85 parts of water were stirred at 70°C for 3 hours to obtain a coal tar light fraction-maleamic acid copolymer/ultra-high molecular weight styrene-maleamic acid copolymer spinning solution with a solid content of 15% and a spinning solution viscosity of 1100cp.

After the spinning solution was statically degassed at 90°C for 3h, it was poured into a 10mL nozzle with a nozzle diameter of 0.21mm, and the spinning solution was propelled by an injection pump with a propulsion speed of 200μL/min. A mesh cloth was used as a receiving substrate, and the distance from the receiving substrate to the spinneret was 30cm; at the same time, hot air at 150°C and a flow rate of 25m/s was used to blow the polymer solution jet to obtain coal tar light fraction-maleamic acid/ultra-high molecular weight styrene-maleamic acid copolymer fiber. The obtained hydrophilic coal tar light fraction-maleamic acid/ultra-high molecular weight styrene-maleamic acid copolymer fiber was heat-treated at 140°C for 3h, and the obtained fiber was converted into a hydrophobic imide copolymer fiber (maleimide unit molar content of 51%) with an average diameter of 1320nm.

Example 4

10.8 parts of the coal tar light fraction-maleamic acid copolymer prepared according to Example 2, 1.2 parts of the ultrahigh molecular weight styrene-maleamic acid copolymer prepared according to Example 2, and 88 parts of water were stirred at 70° C. for 3 hours to obtain a coal tar light fraction-maleamic acid copolymer with a solid content of 12%. /Ultra-high molecular weight styrene-maleamic acid copolymer spinning solution, the spinning solution viscosity is 600cp.

After the spinning solution was statically degassed at 90°C for 3h, it was poured into a 10mL nozzle with a nozzle diameter of 0.21mm, and the spinning solution was propelled by an injection pump with a propulsion speed of 200μL/min. A high-speed roller was used as a receiving substrate, and the distance from the receiving substrate to the spinneret was 30cm; at the same time, hot air at 150°C and a flow rate of 30m/s was used to blow the polymer solution jet to obtain coal tar light fraction-maleamic acid/ultra-high molecular weight styrene-maleamic acid copolymer fiber. The obtained hydrophilic coal tar light fraction-maleamic acid/ultra-high molecular weight styrene-maleamic acid copolymer fiber was heat-treated at 140°C for 3h, and the obtained fiber was converted into a hydrophobic imide copolymer fiber (maleimide unit molar content of 51%) with an average diameter of 350nm.

Example 5

2.5 parts of the ultrahigh molecular weight styrene-maleamic acid copolymer prepared according to Example 2 and 97.5 parts of water were stirred at 70° C. for 2 hours to obtain an ultrahigh molecular weight styrene-maleamic acid copolymer spinning solution with a solid content of 2.5% and a spinning solution viscosity of 1500 cp.

After the spinning solution was statically degassed at 80°C for 4 hours, it was poured into a 10mL nozzle with a nozzle diameter of 0.21mm, and the spinning solution was propelled by an injection pump with a propulsion speed of 100μL/min. A mesh cloth was used as a receiving substrate, and the distance from the receiving substrate to the spinneret was 30cm; at the same time, hot air at 150°C and a flow rate of 30m/s was used to blow the polymer solution jet to obtain ultrahigh molecular weight styrene-maleamic acid copolymer fibers. The obtained hydrophilic ultrahigh molecular weight styrene-maleamic acid copolymer fibers were heat treated at 150°C for 2 hours, and the obtained fibers were transformed into hydrophobic imide copolymer fibers (maleimide unit molar content of 48%) with an average diameter of 98nm. The scanning electron microscope photo is shown in Figure 4

Example 6

Four parts of the ultrahigh molecular weight styrene-maleamic acid copolymer prepared according to Example 2 were stirred with 96 parts of water at 70° C. for 2 hours to obtain an ultrahigh molecular weight styrene-maleamic acid copolymer spinning solution with a solid content of 4% and a spinning solution viscosity of 2400 cp.

After the spinning solution was statically degassed at 80°C for 4 hours, it was poured into a 10mL nozzle with a nozzle diameter of 0.21mm, and the spinning solution was propelled by an injection pump at a propulsion speed of 100μL/min. A mesh was used as a receiving substrate, and the distance from the receiving substrate to the spinneret was 30cm. At the same time, hot air at 150°C and a flow rate of 25m/s was blown on the polymer solution jet to obtain an ultra-high The obtained hydrophilic ultrahigh molecular weight styrene-maleamic acid copolymer fiber was heat treated at 150°C for 2h, and the obtained fiber was transformed into a hydrophobic imide copolymer fiber (maleimide unit molar content of 47%) with an average diameter of 192nm.

Example 7

30 parts of styrene-maleamic acid copolymer (derived from styrene-maleic anhydride copolymer with a number average molecular weight of 110,000 and a molar content of maleamic acid units of 51%) and 70 parts of water were poured into a dissolving kettle of a dry spinning machine and stirred at 70°C for 4 hours to obtain a styrene-maleamic acid spinning solution with a solid content of 30%. After the spinning solution was statically degassed in a dissolving kettle at 80°C for 8 hours, the spinning solution temperature was lowered to 60°C and then spun. The viscosity of the spinning solution was 6000cp.

Under a nitrogen pressure of 0.1 MPa (gauge pressure), the spinning solution was dry-spun on a spinning machine, wherein the metering pump speed was 15 r/min, the metering pump seat temperature was 60°C, the spinneret used was 12 holes, the spinneret aperture was 0.015 mm, the temperature was 60°C, the spinning solution was extruded from the spinneret into a high-temperature tunnel, the hot air temperature in the tunnel was 160°C, the fan speed was 1000 r/min, and the winding speed was 60 m/min. The spun fiber was heat-treated at 160°C for 2 hours, and finally a styrene-maleimide copolymer fiber (maleimide unit molar content was 49%) was obtained, the average diameter was 38 μm, and the fiber strength was 2.6 cN/dtex, and its scanning electron microscope photo is shown in Figure 5.

Example 8

35 parts of styrene-maleic anhydride (number average molecular weight of 28000, maleic anhydride molar content of 51%), 11.8 parts of 28% ammonia water, and 53.2 parts of water were stirred at 60°C for 4 hours to obtain a styrene-maleamic acid spinning solution with a solid content of 35% (maleamic acid unit molar content of 50%) and a spinning solution viscosity of 4000cp. The spinning solution was poured into the dissolving kettle of the dry spinning machine, and the temperature of the dissolving kettle was set to 80°C. The spinning solution was statically degassed in the dissolving kettle for 8 hours, and then the spinning solution temperature was reduced to 60°C before spinning.

Under a nitrogen pressure of 0.2MPa (gauge pressure), the spinning solution was dry-spun on a spinning machine, wherein the metering pump speed was 10r/min, the metering pump seat temperature was 60°C, the spinneret used was 12 holes, the spinneret aperture was 0.015mm, the temperature was 60°C, the spinning solution was extruded from the spinneret into a high-temperature tunnel, the hot air temperature in the tunnel was 180°C, the fan speed was 1000r/min, and the fiber winding speed was 40m/min. The spun fiber was heat-treated at 160°C for 2h, and finally an imide copolymer fiber (maleimide unit molar content was 49%) was obtained, with an average diameter of 52μm and a fiber strength of 2.7 cN/dtex.

Example 9

40 parts of styrene-maleic anhydride (number average molecular weight of 28000, maleic anhydride molar content of 51%), 13.5 parts of 28% ammonia water, and 46.5 parts of water were stirred at 60°C for 4 hours to obtain a styrene-maleamic acid spinning solution with a solid content of 40% (maleamic acid unit molar content of 50%), and the spinning solution viscosity was 4800cp. The spinning solution was poured into the dissolving kettle of the dry spinning machine, and the temperature of the dissolving kettle was set to 80°C. The spinning solution was statically degassed in the dissolving kettle for 8 hours, and then the spinning solution temperature was reduced to 60°C before spinning.

The spinning solution was dry-spun on a spinning machine under a nitrogen pressure of 0.2 MPa (gauge pressure). The spinneret used was 6 holes, the spinneret aperture was 0.015 mm, the metering pump speed was 10 r/min, the metering pump seat temperature was 60°C, and the temperature was 60°C. The spinning solution was extruded from the spinneret into a high-temperature tunnel. The hot air temperature in the tunnel was 180°C, the fan speed was 1000 r/min, and the fiber winding speed was 40 m/min. The spun fiber was heat-treated at 160°C for 2 hours to finally obtain an imide copolymer fiber (maleimide unit molar content was 49%) with an average diameter of 72 μm and a fiber strength of 2.5 cN/dtex.

Example 10

25 parts of styrene-maleamic acid copolymer (derived from styrene-maleic anhydride copolymer with a number average molecular weight of 28,000, maleic anhydride molar content of 51%, maleic anhydride amination rate of 99%, maleic acid molar content of 50%) and 75 parts of water were poured into the dissolving kettle of the wet spinning machine and stirred at 70°C for 4 hours to obtain styrene-maleamic acid spinning solution with a solid content of 25% and a spinning solution viscosity of 3000cp. After the spinning solution was statically degassed in a dissolving kettle at 80°C for 8 hours, the spinning solution temperature was lowered to room temperature before spinning.

Under a nitrogen pressure of 0.1 MPa (gauge pressure), the spinning solution is pushed by a metering pump through a spinneret and directly extruded into a coagulation bath. The spinneret used is 50 holes, the spinneret aperture is 0.08 mm, the metering pump speed is 10 r/min, the coagulation bath is a sodium sulfate solution (concentration is 420 g/L), the coagulation bath length is 2 m, the temperature is room temperature, and after drawing (drawing speed is 20 m/min), an amic acid copolymer fiber is obtained. After the amic acid copolymer fiber is washed with water, it is heat treated at 180°C for 3 hours to finally obtain a styrene-maleimide copolymer fiber (maleimide unit molar content is 49%), wherein the average fiber diameter is 18 μm (see Figure 6) and the fiber strength is 2.4 cN/dtex.

The above description is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications made within the scope of the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

A method for preparing fibers of an imide copolymer (A) from an amic acid copolymer (B), comprising:

(I) spinning an aqueous solution of an amic acid copolymer (B) to obtain fibers of the amic acid copolymer (B), and (II) imidizing the fibers of the amic acid copolymer (B) obtained in step (I) to obtain fibers of the imide copolymer (A),

The imide copolymer (A) is an imide copolymer having imide side groups.
The method according to claim 1, wherein the viscosity of the aqueous solution of the amic acid copolymer (B) is 500-15000cp, preferably 500-12000cp; and/or

The solid content of the aqueous solution of the amic acid copolymer (B) is 1 to 60% by weight, preferably 1.5 to 50% by weight, and more preferably 2 to 45% by weight.
The method according to claim 1 or 2, wherein the spinning in step (I) is selected from wet spinning (a), dry spinning (b), solution blowing spinning (c) and electrospinning (d).
The method according to claim 3, wherein the wet spinning (a) comprises (a-1) extruding an aqueous solution of the amic acid copolymer (B), (a-2) coagulating in a coagulation bath and (a-3) optionally drying to spin.
The method according to claim 3, wherein the dry spinning (b) comprises (b-1) extruding an aqueous solution of the amic acid copolymer (B), (b-2) coagulating with hot air and (b-3) drying to spin.
The method according to claim 4 or 5, wherein the extrusion step comprises extruding an aqueous solution of the amic acid copolymer (B) through a spinneret, preferably the spinneret has a porous spinneret and a pore size of 0.01-0.8 mm, preferably 0.012-0.5 mm, more preferably 0.014-0.2 mm.
The method according to claim 3, wherein the solution blow spinning (c) comprises blowing a jet of an aqueous solution of the amic acid copolymer (B) with hot air.
The method according to claim 7, wherein the aqueous solution of the amide acid copolymer (B) in the nozzle is propelled by a syringe pump to produce a jet, preferably the propulsion speed of the syringe pump for a single nozzle is 50-2000 μl/min, more preferably 80-1200 μl/min, and the diameter of the nozzle nozzle is 0.06mm-0.6mm.
The method according to claim 7 or 8, wherein the temperature of the hot air is 70-250°C, preferably 90-180°C, and the flow rate is 1-100 m/s, preferably 10-50 m/s.
The method according to any one of claims 1 to 9, wherein the imidization in step (II) is carried out 110-220°C, or 140-160°C.
The method according to any one of claims 1 to 10, wherein the imidization reaction time in step (II) is 0.7-6h, or 0.8-5h.
The method according to any one of claims 1 to 11, wherein the imide copolymer (A) has at least one repeating unit (i) with an imide side group, preferably the molar amount of the repeating unit (i) is 15-75 mol%, or 35-65 mol%, based on the total amount of repeating units of the imide copolymer (A).
The process according to claim 12, wherein the imide copolymer (A) has at least one repeating unit (i) carrying an imide side group and at least one further repeating unit (ii) different from the repeating unit (i), preferably the further repeating unit (ii) is selected from the repeating units derived from the following monomers: C1 - C10 alkyl esters of monoethylenically unsaturated C3 -C8 monocarboxylic acids, amides of monoethylenically unsaturated C3 - C8 monocarboxylic acids, vinyl alkyl ethers having C1 - C8 alkyl groups, C2 - C22 monoolefins, C4 - C22 conjugated dienes, styrene, styrene substituted by one or more substituents selected from C1 - C12 alkyl, C1 - C12 alkoxy and halogen, vinyl esters of C1 - C20 carboxylic acids, vinylpyrrolidone, (meth)acrylonitrile, ethylenically unsaturated monomers containing hydroxyl groups, N-vinylformamide, vinylimidazole, allylbenzene, indene, methylindene and compounds containing furan rings,

or

The other repeating units (ii) are derived from at least one monomer containing a carbon-carbon unsaturated double bond of a reaction material derived from gasoline, C4 fraction, C5 fraction, C8 fraction, C9 fraction, coumarone resin raw material, or coal tar light fraction.
The process according to any one of claims 1 to 13, wherein the nitrogen atom of the imide of the imide copolymer (A) carries a group R1 , wherein R1 is selected from H, C1 - C12 alkyl, C3 - C8 cycloalkyl, C1 - C12 alkyl- C3 - C8 cycloalkyl, C6-C10 aryl , C1 - C12 alkyl- C6 - C10 aryl, C3 - C9 heteroaryl or C1 - C12 alkyl- C3 - C9 heteroaryl, wherein the heteroaryl has 1 to 3 heteroatoms selected from N, O and S, preferably R1 is selected from H and C1 - C12 alkyl.
The method according to any one of claims 1 to 14, wherein the amic acid copolymer (B) has at least one repeating unit (i') having an amide group and a carboxyl group and/or an ammonium salt thereof and at least one other repeating unit (ii), preferably at least one other repeating unit (ii) is as defined in claim 13.
The method according to any one of claims 1 to 15, wherein the number average molecular weight of the amic acid copolymer (B) is at least 20,000, preferably at least 25,000, or at least 30,000.
The method according to claim 15 or 16, wherein the molar amount of the repeating unit (i') is 15-75 mol%, or 35-65 mol%, based on the total amount of the repeating units of the amic acid copolymer (B).
The process according to any one of claims 1 to 17, wherein the amic acid copolymer (B) is derived from an anhydride copolymer (C), wherein the anhydride copolymer (C) has at least one repeating unit (i") carrying anhydride groups and at least one other repeating unit (ii), preferably at least one other repeating unit (ii) as defined in claim 13.
The process according to any one of claims 1 to 18, wherein the amic acid copolymer (B) is obtained by reacting an anhydride copolymer (C) with ammonia or an amine, wherein the anhydride copolymer (C) has at least one repeating unit (i") carrying anhydride groups and at least one other repeating unit (ii), preferably at least one other repeating unit (ii) as defined in claim 13.
The method according to any one of claims 1 to 19, wherein the aqueous solution of the amic acid copolymer (B) is prepared as follows:

dissolving the amic acid copolymer (B) in water; or

Reacting the solid anhydride copolymer (C) as defined in claim 18 with ammonia or an amine and then dissolving the resulting amic acid copolymer (B) in water; or

An aqueous solution of an acid anhydride copolymer (C) as defined in claim 18 is reacted with ammonia or an amine to obtain an aqueous solution of an amic acid copolymer (B).
The method according to any one of claims 1 to 20, wherein the aqueous solution of the amic acid copolymer (B) in step (I) does not contain an organic crosslinking agent capable of undergoing a covalent crosslinking reaction with an amide and/or a carboxyl group or an ammonium salt thereof.
Fibers obtainable by a process as claimed in any one of claims 1 to 21.
The fiber according to claim 22, wherein said fiber is insoluble in water.
Article obtainable from the fibres of claim 22 or 23.