CN115260495A

CN115260495A - Phenolic hydroxyl ionic water-based polyamide imide containing reactive groups and preparation method thereof

Info

Publication number: CN115260495A
Application number: CN202211065494.2A
Authority: CN
Inventors: 刘丽; 马震宇; 普饮川; 黄玉东
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2022-08-31
Filing date: 2022-08-31
Publication date: 2022-11-01

Abstract

The invention discloses phenolic hydroxyl ionic water-based polyamide imide containing a reactive group and a preparation method thereof, wherein the method comprises the following steps: 1. reacting L-cysteine with 2, 3-epoxypropyltrimethylammonium chloride in water under the alkali catalysis condition to obtain L-Cys-A; 2. reacting cysteine derivative with 1,2, 4-cyclohexane tricarbamic acid anhydride in glacial acetic acid to obtain DA-A; 3. reacting levodopa and 1,2, 4-cyclohexane tricarboxylic acid anhydride in glacial acetic acid to obtain DA-dopa; 4. DA-A and DA-dopa react with 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane andbase:Sub>A monofunctional end-capping reagent in an ionic liquid containingbase:Sub>A water absorbent to obtain polyamideimide. The water-based polyamide-imide provided by the invention is not crystallized, has good flexibility, remarkably reduces the content of organic solvent in the sizing agent and the process difficulty of preparing a polymer into a material, realizes chemical bonding of the thermoplastic sizing agent and the surface of carbon fiber for the first time, and remarkably improves the interface bonding performance.

Description

Phenolic hydroxyl ionic water-based polyamide imide containing reactive groups and preparation method thereof

Technical Field

The invention belongs to the field of high molecules and composite materials, relates to a thermoplastic polymer, and particularly relates to a phenolic hydroxyl ionic water-based polyamide imide thermoplastic polymer containing a reactive group and a preparation method thereof.

Background

The carbon fiber reinforced resin matrix composite material has the advantages of light weight and high strength, and can be widely applied to the fields of automobiles, aviation and aerospace. Compared with thermosetting composite materials, the high-performance thermoplastic composite material has the advantages of high impact strength, simple, rapid and various forming methods, short forming period, recyclability and the like, and the application of the high-performance thermoplastic composite material in various fields is increased year by year. However, the conventional epoxy carbon fiber sizing agent cannot satisfy the high-performance thermoplastic resin matrix in terms of heat resistance and compatibility, and development of a carbon fiber sizing agent suitable for the high-performance thermoplastic resin matrix is urgently needed.

At present, in domestic and foreign research, a high-performance thermoplastic polymer with a structure similar to that of a thermoplastic matrix is mostly adopted as a main sizing agent of a sizing agent, and polyimide, polyetherimide, polyethersulfone, polyetheretherketone and the like are common. There are three types of sizing agents, solvent-based, emulsion-based and water-based. The solvent-based sizing agent is prepared by directly dissolving a polymer by an organic solvent, the method has limited improvement on the interfacial property and the mechanical property of the composite material, and the use of a large amount of organic solvent can cause harm to the environment and human bodies in the process of drying fibers. Emulsion sizing agent refers to a relatively stable mixed system obtained by adding water and a commercial emulsifier to an organic solvent solution of a polymer under high-speed shearing by using a phase inversion method. The sizing agent prepared by the method can improve the mechanical property of the composite material, the use of organic solvents is greatly reduced, but the preparation method is complex and difficult to industrialize, and the residual emulsifier can cause the thermal decomposition of the sizing agent in the forming process. At present, two types of common aqueous sizing agents are mainly used, one type is that water containing an emulsifier is uniformly mixed with a solution of a low-boiling-point organic solvent containing a polymer under the action of ultrasonic shearing by an emulsion/solvent evaporation method, most of the solvent is evaporated to form the sizing agent, but the problem of residual emulsifier still exists in the method, and the volatile toxicity of the low-boiling-point organic solvent is very high. The second method is to dissolve the polymer intermediate rich in hydrophilic groups, which is currently the intermediate polyamic acid of polyimide, directly in water to prepare sizing agent. However, the method needs high-temperature imidization at the temperature of more than 300 ℃ on a later-stage production line, is not suitable for the existing carbon fiber production line, and is difficult to industrialize. Aqueous sizing agents are the development of carbon fiber sizing agents suitable for thermoplastic matrices, but the existing methods all have disadvantages. In addition, the existing thermoplastic sizing agent has the advantages that as the main sizing agent thermoplastic resin, particularly the rigid high-performance thermoplastic resin, is relatively inert and does not contain a molecular structure of reactive active groups, and has only the physical action of intermolecular action such as hydrogen bonds with the surface of carbon fibers, and has no chemical bonding, the bonding between the sizing agent layer and the surface interface of the carbon fibers is weak, and the exertion and the promotion of the overall performance of the composite material are limited.

Among many high-performance thermoplastic polymers, polyamideimide has attracted much attention because of its combination of the advantages of polyamide processability, mechanical properties and excellent heat resistance of polyimide. However, the conventional aromatic polyamide imide has high crystallinity and poor flexibility because of the high rigidity of an imide structure and an aromatic ring structure, and is difficult to dissolve in an organic solvent. Through structural design, the performance of the device can be improved. At present, the methods for reducing the crystallinity and regularity of polyamide imide and improving the solubility include the following methods: 1. hetero atoms are introduced into a main chain structure, so that the flexibility is improved, the regularity is reduced, and the introduced hetero atoms can be oxygen, silicon, sulfur, nitrogen, phosphorus and the like; 2. aliphatic structures such as aliphatic chains and alicyclic chains are introduced into a main chain, but the regular arrangement is caused by the overlong aliphatic chains, the heat resistance is also influenced, and some ethylenic unsaturated structures are introduced by researchers, but the improvement on the solubility is not obvious; 3. some bulky side groups are introduced into a main chain, flexibility and solubility are improved by a method of weakening intermolecular force and improving free volume, and excellent optical properties and the like can be endowed to the polyamide-imide by introducing functional side groups; 4. a complex heterocyclic structure is introduced to reduce the regularity of a molecular chain, but the synthesis is complex and the industrialization is difficult. The method can achieve better effect by combining the methods, but the existing polyamide imide has low room temperature solubility in common organic solvents, and the room temperature solubility is not higher than 10% (w/v). And the complex monomer has higher synthesis cost and is not environment-friendly. Furthermore, no relevant studies have been found on aqueous polyamideimides.

Disclosure of Invention

The invention aims to provide phenolic hydroxyl ionic water-based polyamide imide containing a reactive group and a preparation method thereof. Particularly, the polyamide-imide of the sizing agent main sizing agent realizes covalent chemical bonding between the thermoplastic sizing agent and the surface of the carbon fiber for the first time through esterification reaction of phenolic hydroxyl activated by a side group catechol group and an oxygen-containing functional group on the surface of the carbon fiber, and interface combination is obviously improved. Compared with the existing polyamide imide, the water-based polyamide imide disclosed by the invention is not crystallized, has good flexibility, greatly improves the solubility in an organic solvent, obviously reduces the content of the organic solvent in a sizing agent and the process difficulty of preparing a polymer into a material, realizes the chemical bonding of the thermoplastic sizing agent and the surface of carbon fiber for the first time, and obviously improves the interface bonding performance.

The purpose of the invention is realized by the following technical scheme:

a phenolic hydroxyl ionic water-based polyamide imide containing a reactive group has the following structural formula:

the preparation method of the phenolic hydroxyl ionic water-based polyamide imide containing the reactive group comprises the following steps:

step one, mixing L-cysteine and 2, 3-epoxypropyl trimethyl ammonium chloride according to the proportion of 1-1.1: 1 in an inert atmosphere under the condition of alkali catalysis with pH of 7-9 in water at 25-30 ℃ for 12-48 h to obtain the cysteine derivative named L-Cys-A, wherein:

the alkali is one of sodium hydroxide, sodium carbonate and the like;

the inert atmosphere is inert gas such as argon and the like;

the structural formula of L-Cys-A is as follows:

step two, mixing cysteine derivative and 1,2, 4-cyclohexane tricarboxylic acid anhydride according to the weight ratio of 1-1.1: 1, firstly reacting for 10-15 h at 25-30 ℃ in glacial acetic acid, and then carrying out reflux reaction for 4-8 h at 110-130 ℃ to obtainbase:Sub>A water-soluble imide-containing diacid monomer, namely DA-A, wherein:

the structural formula of DA-A is as follows:

step three, mixing levodopa and 1,2, 4-cyclohexane tricarboxylic acid anhydride according to the weight ratio of 1-1.1: 1, firstly reacting for 10-15 h at 25-30 ℃ in glacial acetic acid, and then carrying out reflux reaction for 4-8 h at 110-130 ℃ to obtain a water-soluble diacid monomer containing imide and a reactive group, which is named as DA-dopa, wherein:

the structural formula of DA-dopa is as follows:

step four, mixing the total amount of DA-A and DA-dopa and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane according to the ratio of 1-1.1: 1 and 4 times of equivalent of ionic liquid are uniformly mixed, heated to liquid state, added with 4 times of equivalent of water absorbent and 0-0.5 time of equivalent of monofunctional end-capping reagent, mechanically stirred and reacted for 1-6 h at 120 ℃, so as to obtain semi-aromatic polyamide imide containing reactable catechol groups and quaternary ammonium salt groups, named PAI-D, wherein:

the molar ratio of DA-A to DA-dopa is 1-4: 1;

the ionic liquid is tetrabutylammonium bromide;

the water absorbent is triphenyl phosphite;

the monofunctional end-capping agent is aniline;

PAI-D has the following structural formula:

a preparation method of the carbon fiber sizing agent containing the phenolic hydroxyl ionic water-based polyamide imide containing the reactive group comprises the following steps:

step one, PAI-D is dissolved in an organic solvent to obtain a polymer solution with the concentration of 10-25% (w/v), wherein:

the organic solvent is one of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide and the like;

and step two, directly dripping the polymer solution into a large amount of water under stirring to prepare the carbon fiber sizing agent with the concentration of 0.1-1 wt%.

A method for preparing a polyetherimide composite material by using the carbon fiber sizing agent comprises the following steps:

step one, extracting commercial carbon fiber cloth through acetone to remove pulp, soaking the commercial carbon fiber cloth in a sizing agent for 15-30 min, and then drying moisture and a solvent to obtain PAI-D sized carbon fiber cloth, wherein:

the commercial carbon fiber cloth is T300 carbon cloth of Dongli company, domestic T300 level carbon cloth and the like;

the temperature of acetone extraction is 70-80 ℃, and the extraction time is 45-50 h;

the temperature for drying the water is 100 ℃, and the time is 20-40 min;

the temperature of the drying solvent is determined according to the boiling points of different solvents;

step two, laying the PAI-D sizing carbon fiber cloth and the powder of the high-performance thermoplastic resin matrix layer by layer, wherein each layer of polymer powder is uniformly laid on each layer of carbon cloth, placing the multilayer compound in a metal mould with flat plates at the upper part and the lower part, and obtaining the composite material laminated plate through hot press molding, wherein:

the powder of the high-performance thermoplastic resin matrix is one of commercially available polyetherimide, polyetheretherketone and the like;

the mass fraction of the high-performance thermoplastic resin matrix in the multilayer compound is 30-35%, and the number of layers is 12;

the forming system of the composite material laminated plate is different according to different high-performance thermoplastic resin matrixes, and by taking polyetherimide as an example, the method comprises the steps of firstly contacting, pressing and heating to 260 ℃, increasing the pressure to 5MPa and keeping for 30min, then increasing to 350 ℃, increasing the pressure to 10MPa and keeping for 1h, and then keeping the pressure and cooling to room temperature.

Compared with the prior art, the invention has the following advantages:

1. the polyamideimide provided by the invention has active reactive phenolic hydroxyl group through introducing levodopa containing catechol reactive group, so that the common rigid and inert high-performance thermoplastic polymer has active groups, and the structure and the method are not reported in the researches on the polyamideimide at home and abroad.

2. The polyamide-imide provided by the invention has excellent thermal stability and greatly improved solubility, and the solubility of the polyamide-imide is far higher than that of polyamide-imide which is currently researched at home and abroad.

3. The polyamideimide provided by the invention can prepare self-emulsifying aqueous dispersions with different particle sizes by adjusting the proportion of monomer diacid, and the dispersions have good storage stability, wherein the content of organic solvent is extremely low and is far lower than that of organic solvent in existing research and commercial thermoplastic sizing agents.

4. The polyamide-imide sizing agent provided by the invention forms covalent chemical bonding with the surface of the carbon fiber, obviously improves the interface bonding of the sizing agent and the surface of the carbon fiber, and realizes the chemical bonding of the thermoplastic sizing agent and the carbon fiber for the first time.

5. The polyamide-imide sizing carbon fiber reinforced polyetherimide and polyetheretherketone composite material provided by the invention has higher improvement degrees of interlaminar shear strength, bending strength and impact strength than other sizing agents and bare fibers.

Drawings

FIG. 1 shows DA-dopa and the synthesis raw material ¹³ C NMR spectrogram;

FIG. 2 shows PAI-D ¹ H NMR spectrum;

FIG. 3 is a graph of thermogravimetric analysis of a polymer;

FIG. 4 is a diagram showing the physical structure of the sizing agent before and after long-term storage;

FIG. 5 is a scanning electron micrograph of a fiber;

FIG. 6 is a bar graph of mechanical properties of different sized carbon fiber reinforced polyetherimide composites;

FIG. 7 is a bar graph of mechanical properties of different sized carbon fiber reinforced polyetheretherketone composites;

FIG. 8 is a schematic diagram of PAI-D sizing agent self-emulsification and composite material interface effect;

in the figure, dCF refers to carbon fiber after desizing, eCF refers to carbon fiber without desizing containing commercial epoxy sizing agent, sCF refers to carbon fiber sized with PAI-D of the present invention, PEI is polyetherimide and PEEK is polyetheretherketone.

Detailed Description

The technical solutions of the present invention are further described below with reference to the embodiments, but the present invention is not limited thereto, and any modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Example 1

The embodiment provides a phenolic hydroxyl ionic water-based polyamide imide carbon fiber sizing agent containing a reactive group and a reinforced polyetherimide composite material thereof, and the preparation steps are as follows:

1. synthesis of cysteine derivatives: l-cysteine was reacted with 2, 3-epoxypropyltrimethylammonium chloride (10 mmol) at a molar ratio of 1.1:1 in the argon atmosphere, adding a proper amount of 0.5mol/L NaOH solution, adjusting the pH to 9, magnetically stirring at room temperature in the argon atmosphere for reaction for 24 hours, and freeze-drying to obtain a colorless transparent product with the yield of 90%.

2. Synthesis of water-soluble imide-containing diacid monomer: cysteine derivative was reacted with 1,2, 4-cyclohexanetricarboxylic anhydride (10 mmol) in a 1:1 is dissolved in 50ml of glacial acetic acid, stirred and reacted at room temperature overnight, refluxed at 118 ℃ for 4 hours, and then most of acetic acid is removed by rotary evaporation, precipitated in ethyl acetate, washed for a plurality of times, dried in vacuum at 60 ℃, dissolved in water again, and freeze-dried to obtain a light yellow powdery product with the yield of 95%.

3. Synthesis of water-soluble imide-and reactive group-containing diacid monomer: levodopa was reacted with 1,2, 4-cyclohexanetricarboxylic anhydride (10 mmol) in a 1:1 is dissolved in 50ml of glacial acetic acid, stirred and reacted at room temperature overnight, then refluxed at 118 ℃ for 4 hours, most of acetic acid is removed by rotary evaporation, and the product is precipitated in ethyl acetate, washed for a plurality of times, dried in vacuum at 60 ℃, dissolved in water again and freeze-dried to obtain a light yellow powdery product with the yield of 98 percent, and the nuclear magnetic carbon spectrum of the product is shown in figure 1.

4. Synthesis of polyamideimide: mixing water-soluble diacid monomer containing imide, water-soluble diacid monomer containing imide and reactive group and 2, 2-bis [4- (4-aminophenoxy) phenyl]Propane (1.5 mmol) was added at a ratio of 1:0.5: mixing the mixture with 1.5 mol ratio and 6mmol tetrabutylammonium bromide, heating and stirring the mixture to be liquid, and adding 6mmol triphenyl phosphite and 0.5mmol aniline; mechanically stirring, and reacting for 1h at 120 ℃; precipitation in methanol, washing several times, filtration and vacuum drying gave the product as a pale yellow powder with a yield of 87%. The nuclear magnetic hydrogen spectrum of the polyimide is shown in figure 2, ¹ H NMR(600MHz,DMSO-d ₆ ,δ,ppm):9.96(m,1H),9.60(m,1H),9.34(m,1H),6.76-7.57(br,19H),4.94(br,1H),3.12-3.49(br,18H),2.39(m,1H),2.13(m,1H),2.02(s,2H),1.60-1.79(br,8H),1.30(m,1H),0.94(m,1H)。

5. the polymer PAI-D synthesized in the fourth step was dissolved in a small amount of N, N-dimethylformamide to obtain a 20% (w/v) polymer solution, and this solution was directly added dropwise to a large amount of water under stirring to prepare a 0.5wt% aqueous dispersion, which was a sizing agent.

6. And (2) extracting T300 carbon cloth from Dongli company in acetone at 75 ℃ for 48h to remove size, soaking in the sizing agent for 20min, drying the water at 100 ℃ for 30min, and drying the solvent at 150 ℃ for 15min to obtain the PAI-D sized carbon fiber cloth.

7. And (2) paving PAI-D sizing carbon fiber cloth and powder of polyetherimide layer by layer, wherein each layer of polymer powder is uniformly paved on each layer of carbon cloth to obtain 12 layers of layer-by-layer compound with the resin content of the resin of 30%, placing the layer-by-layer compound in a metal mould with flat plates on the upper and lower parts, placing the layer-by-layer compound on a flat vulcanizing instrument, firstly, contacting, pressing and heating to 260 ℃, increasing the pressure to 5MPa for 30min, then, heating to 350 ℃, increasing the pressure to 10MPa for 1h, then, keeping the pressure and cooling to room temperature for hot press molding, and obtaining the corresponding carbon fiber reinforced polyetherimide composite material laminated plate.

The initial thermal decomposition temperature of the product is 394 ℃ by thermogravimetric analysis, and the thermogravimetric curve is shown in figure 3; the solubility of the product in solvents such as DMF was tested at room temperature and was greater than 20% (w, v). The change of the state of the sizing agent before and after three months of storage is observed by naked eyes, no obvious change is found, and a real object diagram is shown in figure 4; the scanning electron micrograph of the sized fibers is shown in FIG. 5; the mechanical properties of different sized carbon fiber reinforced polyetherimide composite materials, such as interlaminar shear strength, bending strength, impact strength and the like, are shown in figure 6.

Example 2

This example differs from example 1 in that: 7. and (2) paving PAI-D sizing carbon fiber cloth and polyether-ether-ketone powder layer by layer, wherein each layer of polymer powder is uniformly paved on each layer of carbon cloth to obtain 12 layers of layer-by-layer compound with the resin content of 30%, placing the layer-by-layer compound in a metal mold with flat plates on the upper and lower sides, placing the metal mold on a flat vulcanizing instrument, firstly contacting and heating to 180 ℃, increasing the pressure to 5MPa for 60min, then heating to 370 ℃, increasing the pressure to 10MPa for 40min, then cooling and maintaining the pressure to room temperature for hot press molding to obtain the corresponding carbon fiber reinforced polyether-ether-ketone composite laminated plate.

The mechanical properties of the different sized carbon fiber reinforced polyetheretherketone composite materials, such as interlaminar shear strength, bending strength, impact strength, etc., are shown in fig. 7.

Claims

1. A phenolic hydroxyl ionic waterborne polyamideimide containing a reactive group, wherein the polyamideimide has the following structural formula:

2. a process for preparing the ionic aqueous polyamideimide containing a phenolic hydroxyl group capable of reacting according to claim 1, which comprises the steps of:

step one, mixing L-cysteine and 2, 3-epoxypropyltrimethylammonium chloride according to the weight ratio of 1-1.1: 1 in an inert atmosphere under the condition of alkali catalysis with pH of 7-9, reacting in water at 25-30 ℃ for 12-48 h to obtain the cysteine derivative named L-Cys-A, wherein:

the structural formula of L-Cys-A is as follows:

step two, mixing cysteine derivative and 1,2, 4-cyclohexane tricarboxylic acid anhydride according to the weight ratio of 1-1.1: 1, firstly reacting in glacial acetic acid at 25-30 ℃ for 10-15 h, and then performing reflux reaction at 110-130 ℃ for 4-8 h to obtainbase:Sub>A water-soluble imide-containing diacid monomer, namely DA-A, wherein:

the structural formula of DA-A is as follows:

step three, mixing levodopa and 1,2, 4-cyclohexane tricarboxylic acid anhydride according to the weight ratio of 1-1.1: 1, firstly reacting for 10-15 h at 25-30 ℃ in glacial acetic acid, and then carrying out reflux reaction for 4-8 h at 110-130 ℃ to obtain a water-soluble diacid monomer containing imide and a reactive group, wherein the diacid monomer is named as DA-dopa, and the molar ratio of the monomer is as follows:

the structural formula of DA-dopa is as follows:

step four, mixing the total amount of DA-A and DA-dopa with 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane according to the weight ratio of 1-1.1: 1 and 4 times of equivalent of ionic liquid are uniformly mixed, heated to liquid state, added with 4 times of equivalent of water absorbent and 0-0.5 time of equivalent of monofunctional end-capping reagent, mechanically stirred and reacted for 1-6 h at 120 ℃, so as to obtain semi-aromatic polyamide imide containing reactable catechol groups and quaternary ammonium salt groups, named PAI-D, wherein:

PAI-D has the following structural formula:

3. the method for preparing ionic water-based polyamideimide containing phenolic hydroxyl group capable of reacting according to claim 2, wherein the alkali is one of sodium hydroxide and sodium carbonate.

4. The method for preparing phenolic hydroxyl ionic waterborne polyamideimide containing reactable group as claimed in claim 2, characterized in that the ionic liquid is tetrabutylammonium bromide; the water absorbent is triphenyl phosphite; the monofunctional blocking agent is aniline.

5. The method for preparing ionic waterborne polyamideimide containing phenolic hydroxyl group capable of reacting according to claim 2, wherein the molar ratio of DA-A and DA-dopa is 1 to 4:1.

6. a method for preparing a carbon fiber sizing agent comprising the reactive group-containing phenolic hydroxyl ionic water-based polyamideimide according to claim 1, wherein said method comprises the steps of:

step one, dissolving phenolic hydroxyl ionic water-based polyamide imide containing a reactive group in an organic solvent to obtain a polymer solution with the concentration of 10-25% (w/v);

7. The method for preparing a carbon fiber sizing agent according to claim 6, wherein the organic solvent is one of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, and dimethylsulfoxide.

8. A method for preparing a polyetherimide composite material using the carbon fiber sizing agent of any one of claims 6 to 7, characterized in that the method comprises the steps of:

and step two, laying the PAI-D sizing carbon fiber cloth and the powder of the high-performance thermoplastic resin matrix layer by layer, wherein each layer of polymer powder is uniformly laid on each layer of carbon cloth, placing the multilayer composite in a metal mold with flat plates at the upper part and the lower part, and performing hot press molding to obtain the composite laminated plate.

9. The method for preparing the polyetherimide composite material by using the carbon fiber sizing agent as claimed in claim 8, wherein the acetone extraction temperature is 70-80 ℃, and the extraction time is 45-50 h.

10. The method for preparing the polyetherimide composite material using the carbon fiber sizing agent according to claim 8, characterized in that the powder of the high-performance thermoplastic resin matrix is one of polyetherimide and polyetheretherketone; the mass fraction of the high-performance thermoplastic resin matrix in the multilayer composite is 30-35%, and the number of layers is 12.