1. An aramid wire enamel is characterized by comprising a modified polyisophthaloyl metaphenylene diamine polymer and an organic solvent;

the modified polyisophthaloyl metaphenylene diamine polymer is obtained by polymerizing metaphenylene diamine, isophthaloyl dichloride and 4, 4' -diaminodiphenyl ether, and the specific preparation process comprises the following steps:

1) carrying out solution polycondensation on 4, 4' -diaminodiphenyl ether, m-phenylenediamine, a solvent, an acid-binding agent and isophthaloyl dichloride accounting for 70-85% of the total mass of the isophthaloyl dichloride by using a supercritical carbon dioxide fluid as a reaction solvent, and adding hydrophobic nano-silica and the acid-binding agent into a reaction system, wherein the addition amount of the hydrophobic nano-silica is 0.1-0.5% of the mass of the isophthaloyl dichloride added in the step;

2) after the reaction is carried out for 2-30 minutes in the step 1), adding the rest 4, 4' -diaminodiphenyl ether, m-phenylenediamine, isophthaloyl chloride, an acid-binding agent and a solvent to continue the solution polycondensation reaction, adding hydrophobic nano-silica into a reaction system, wherein the addition amount of the hydrophobic nano-silica is 1-2% of the mass of the m-phthaloyl chloride added in the step, and washing a polymerization product to be neutral to obtain the modified polyisophthaloyl isophthaloyl diamide polymer.

2. The aramid wire enamel of claim 1, wherein the molar ratio of 4, 4' -diaminodiphenyl ether to m-phenylenediamine in step 1) is 1: 8-10.

3. The aramid wire enamel of claim 1, wherein the molar ratio of 4, 4' -diaminodiphenyl ether to m-phenylenediamine in the step 2) is 1: 3-5.

4. The aramid wire enamel according to claim 1, wherein the molar amount of the isophthaloyl dichloride in the step 1) and the step 2) is: the sum of the molar weight of the 4, 4' -diaminodiphenyl ether and the molar weight of the m-phenylenediamine is 1: 1.01-1.02.

5. The aramid wire enamel according to claim 1, wherein the hydrophobic nano-silica is nano-silica modified with 3- (2, 3-glycidoxy) propyltrimethoxysilane.

6. The aramid wire enamel according to claim 5, wherein the grafting ratio of the hydrophobic nano silica is 2-5%.

7. The aramid wire enamel according to claim 1, wherein the preparation method of the hydrophobic nano silica comprises the following steps: adding the dried nano silicon dioxide powder into N-methyl pyrrolidone, carrying out ultrasonic dispersion for 20-30 min, adding KH560, carrying out ultrasonic treatment for about 5 min, transferring the mixture into a four-mouth bottle under the atmosphere of N2, stirring and reacting at 50-60 ℃ for 2-3 h, carrying out centrifugal separation on the reaction liquid, precipitating the modified silicon dioxide, and drying to obtain the hydrophobic nano silicon dioxide.

8. The aramid wire enamel of claim 1, wherein the acid scavenger is an organic base.

9. The aramid wire enamel of claim 1, wherein the organic solvent is any one or a mixture of N-methyl pyrrolidone, dimethyl acetamide and N, N-dimethyl formamide.

10. The aramid wire enamel of claim 1, wherein the aramid wire enamel comprises, in parts by weight: 20-60 parts of dried modified polyisophthaloyl metaphenylene diamine polymer and 30-120 parts of organic solvent.

Background

The wire enamel is a coating capable of generating a good insulating layer between a conducting wire and a conducting wire in a winding, and is mainly used for bare copper wires, alloy wires and outer layers of glass fiber covered wires with various wire diameters so as to improve and stabilize the performance of the enameled wire. As a coating with excellent electrical insulation performance, wire enamel is an indispensable material for electrical equipment, and the quality of the wire enamel is directly related to the economic and technical indexes and the service life of the electrical equipment. With the increasing economic and civilian standards of living, the demand of wire enamels in both military and civilian fields is rapidly increasing.

The miniaturization of the motor and the electric appliance is an important trend of the development of electrical products, and when the motor and the electric appliance run under a short-time overload condition, the enameled wire bears thermal shock which is rapidly reduced from high temperature exceeding the highest working temperature to room temperature. Under the high-speed condition when the high-speed electric drill motor is used, a paint film is simultaneously subjected to the combined action of three factors of heat, machinery and electricity, and if the paint film is subjected to thermoplastic deformation, softening breakdown is easily generated.

The main component and key factor of wire enamel is the base resin, and the properties of the resin directly determine the properties and application range of the wire enamel. Wire enamel may be classified into oil enamel, epoxy enamel, silicone resin enamel, acetal enamel, polyester enamel, polyurethane enamel, polyester imide enamel, polyimide enamel, polyamide imide enamel, etc., depending on the resin used.

The meta-aramid (poly m-phenylene isophthalamide) has long thermal stability, can be used at a high temperature of 200 ℃ for a long time without aging, and has excellent dimensional stability; the meta-aramid fiber has excellent electrical insulation, and the breakdown voltage resistance of the insulation paper made of the meta-aramid fiber can reach 20kv/mm, so that the meta-aramid fiber is a globally recognized optimal insulation material; in addition, the meta-aramid fiber has excellent radiation resistance, and can still maintain 49% of the original strength after being continuously irradiated by 50kV X-rays for 250 hours. The inventor prepares the meta-aramid insulating paint with excellent performance by modifying and researching the meta-aramid in the earlier stage. The inventors have further developed high performance aramid wire enamel.

Disclosure of Invention

The invention aims to provide aramid insulation wire enamel.

The technical scheme adopted by the invention is as follows:

an aramid wire enamel comprises a modified polyisophthaloyl metaphenylene diamine polymer and an organic solvent;

the modified polyisophthaloyl metaphenylene diamine polymer is obtained by polymerizing metaphenylene diamine, isophthaloyl dichloride and 4, 4' -diaminodiphenyl ether, and the specific preparation process comprises the following steps:

1) carrying out solution polycondensation on 4, 4' -diaminodiphenyl ether, m-phenylenediamine, a solvent, an acid-binding agent and isophthaloyl dichloride accounting for 70-85% of the total mass of the isophthaloyl dichloride by using a supercritical carbon dioxide fluid as a reaction solvent, and adding hydrophobic nano-silica and the acid-binding agent into a reaction system, wherein the addition amount of the hydrophobic nano-silica is 0.1-0.5% of the mass of the isophthaloyl dichloride added in the step;

2) after the reaction is carried out for 2-30 minutes in the step 1), adding the rest 4, 4' -diaminodiphenyl ether, m-phenylenediamine, isophthaloyl chloride, an acid-binding agent and a solvent to continue the solution polycondensation reaction, adding hydrophobic nano-silica into a reaction system, wherein the addition amount of the hydrophobic nano-silica is 1-2% of the mass of the m-phthaloyl chloride added in the step, and washing a polymerization product to be neutral to obtain the modified polyisophthaloyl isophthaloyl diamide polymer.

The molar ratio of the 4, 4' -diaminodiphenyl ether to the m-phenylenediamine in the step 1) is 1: 8-10.

The molar ratio of the 4, 4' -diaminodiphenyl ether to the m-phenylenediamine in the step 2) is 1: 3-5.

Preferably, the molar amount of isophthaloyl dichloride in step 1) and step 2) is: the sum of the molar weight of the 4, 4' -diaminodiphenyl ether and the molar weight of the m-phenylenediamine is 1: 1.01-1.02.

Preferably, the hydrophobic nano-silica is modified by KH560(3- (2, 3-glycidoxy) propyltrimethoxysilane).

The amount of the hydrophobic nano-silica added in the step 1) can be any value or a combination of any values in the range of 0.1-0.5% of the mass of the isophthaloyl dichloride added in the step, such as 0.2%, 0.3%, and 0.4%.

The adding amount of the hydrophobic nano-silica in the step 2) is within a range formed by any value or combination of any values within the range of 1-2% of the mass of the isophthaloyl dichloride added in the step, such as 1.2%, 1.4%, 1.6%, 1.8% and 1.9%.

More preferably, the grafting ratio of the hydrophobic nano-silica is 2% to 5%.

The inventor finds that under the condition of using supercritical carbon dioxide as a solvent, a certain amount of modified nano-silica is added in the step 1) and the step 2), and the obtained wire enamel further has better heat resistance and water resistance, which is probably because on one hand, the modified nano-silica has good dispersibility in a reaction system, and on the other hand, the surface group of the modified nano-silica can partially react with amino, so that the compatibility between the nano-silica and a polymer is further improved, and meanwhile, the water resistance of the polymer is enhanced.

The preparation method of the hydrophobic nano silicon dioxide comprises the following steps: adding the dried nano silicon dioxide powder into N-methyl pyrrolidone, carrying out ultrasonic dispersion for 20-30 min, adding KH560, carrying out ultrasonic treatment for about 5 min, transferring the mixture into a four-mouth bottle under the atmosphere of N2, stirring and reacting at 50-60 ℃ for 2-3 h, carrying out centrifugal separation on the reaction liquid, precipitating the modified silicon dioxide, and drying to obtain the hydrophobic nano silicon dioxide.

Preferably, the acid scavenger is added to the reaction in an amount of 0.95 to 1.2 times the theoretical stoichiometric amount required to neutralize the hydrogen chloride produced, based on the amounts of phenylenediamine and phthaloyl chloride.

The acid-binding agent is organic base. Preferably, the organic base is an amine such as triethylamine, trimethylamine, tripropylamine, tributylamine, dimethylisopropylamine, dimethylcyclohexylamine, pyridine, 4-methylmorpholine, 4-ethylmorpholine, 4-butylmorpholine, N-methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, N-methylindole, N-ethylindole, N-methylpyrrole, and the like.

Preferably, the organic solvent is any one or a mixture of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc) and N, N-Dimethylformamide (DMF). Further preferably, the organic solvent is dimethylacetamide or N-methylpyrrolidone.

Preferably, the aramid wire enamel comprises the following components in parts by weight: 20-60 parts of dried modified polyisophthaloyl metaphenylene diamine polymer and 30-120 parts of organic solvent.

As can be understood by those skilled in the art, the aramid wire enamel disclosed in the present application can also be added with certain amounts of pigments and fillers and other functional additives such as leveling agents and the like according to needs.

When the supercritical carbon dioxide fluid is used as a reaction solvent, the reaction environment is kept above the critical temperature and the critical pressure of CO2, the reaction temperature is higher than 31.1 ℃, and the reaction pressure is higher than 7.29 MPa; preferably, the reaction temperature is 31.1-120 ℃, and the pressure is 7.29-50 MPa.

Preferably, in the polymerization process of the modified polyisophthaloyl metaphenylene diamine polymer, in the step 1), 4 '-diaminodiphenyl ether, metaphenylene diamine, an acid-binding agent and a solvent are prepared into a mixed solution of 4, 4' -diaminodiphenyl ether-metaphenylene diamine-acid-binding agent-supercritical carbon dioxide; the isophthaloyl dichloride and the hydrophobic nano-silica are prepared into isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution, and the prepared two solutions are mixed and reacted under stirring.

Further, in the step 2), the residual isophthaloyl chloride, hydrophobic nano-silica and solvent are prepared into an isophthaloyl chloride-hydrophobic nano-silica-supercritical carbon dioxide solution; preparing the rest 4,4 '-diaminodiphenyl ether, m-phenylenediamine and an acid-binding agent to obtain a novel 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution.

The nano silicon dioxide can be obtained commercially or prepared by self according to the prior art, and the invention has no special limitation on the purchase manufacturers of the nano silicon dioxide.

Compared with the prior art, the method has the following beneficial effects:

(1) the modified polyisophthaloyl metaphenylene diamine polymer is used for wire enamel, has good solubility and can be dissolved in dimethylacetamide or N-methylpyrrolidine under the condition of not adding a cosolvent;

(2) in the process of preparing the modified polyisophthaloyl metaphenylene diamine polymer, supercritical carbon dioxide is used as a solvent, compared with the traditional polymerization solvent, the supercritical carbon dioxide has stronger dissolubility to nano silicon dioxide and the product, the prepared product has better performance, does not pollute the product and is easy to separate, and the separation of the product and the solvent can be realized only by changing the temperature and/or the pressure;

(3) the wire enamel prepared by the method has excellent dielectric property, high temperature resistance, hydrophobicity and moisture resistance, and has good bonding property with a base material;

(4) the modified polyisophthaloyl metaphenylene diamine polymer is prepared in two steps, and hydrophobic nano silicon dioxide is respectively added in the first step and the second step, so that the dielectric property of the modified polymer is enhanced, and the heat resistance and the humidity resistance of the modified polymer can be enhanced;

(5) in the two steps of preparing the modified polyisophthaloyl metaphenylene diamine, the adding amount of different modified 4, 4' -diaminodiphenyl ether is respectively controlled, so that the dissolving performance of a modified polymer in a solvent is improved, the bonding strength of interfaces is improved, the porosity between the interfaces is reduced, and the water resistance is enhanced.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

In the following examples, the nanosilica was purchased from mcolin reagents ltd.

Example 1

An aramid wire enamel comprises a modified polyisophthaloyl metaphenylene diamine polymer and a solvent;

the modified polyisophthaloyl metaphenylene diamine polymer is obtained by polymerizing metaphenylene diamine, isophthaloyl dichloride and 4, 4' -diaminodiphenyl ether, and the specific preparation process comprises the following steps:

1) adding 2g of 4,4 '-diaminodiphenyl ether and 8.65g of m-phenylenediamine into a pressure reactor which is provided with a stirrer and is connected with a dry nitrogen pipe, adding 19.08g of triethylamine as an acid-binding agent, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, keeping for a period of time, converting the carbon dioxide into a supercritical state, and dissolving substances in the pressure reactor to prepare a mixed solution of the 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide; adding 0.09g of hydrophobic nano-silica and 18.09g of isophthaloyl dichloride into another pressure reactor which is provided with a stirrer and is connected with a dry nitrogen pipe, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, and dissolving substances in the pressure reactor to prepare isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; adding isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution into a mixed solution of 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid binding agent-supercritical carbon dioxide under rapid stirring, always keeping the supercritical state of carbon dioxide, and continuously stirring for reaction;

2) preparing 0.08g of hydrophobic nano-silica and 7.75g of isophthaloyl dichloride to obtain a new isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; 1.95g of 4,4 '-diaminodiphenyl ether, 3.16g of m-phenylenediamine and 8.18g of acid-binding agent triethylamine are prepared to obtain a novel 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution. After the reaction is carried out for 2-30 minutes in the step 1), adding the newly configured isophthaloyl dichloride-hydrophobic nano-silica-superfineAnd (3) continuously stirring the critical carbon dioxide solution and the 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution for reaction until the reaction is finished. Adjusting the temperature and pressure of the reactor to a non-critical state, adding 200 g of water into the pressure reactor, stirring for 30 minutes in the non-critical state, standing for layering, discharging wastewater, washing for four times according to the step, adding 500 g of deionized water, and gradually discharging CO₂The gas is compressed again, condensed and recycled; and performing post-treatment such as centrifugal filtration and washing to remove residual acid-binding agent, and drying for later use.

In this embodiment, the preparation method of the hydrophobic nano-silica comprises: adding 1g of dried nano silicon dioxide powder into 20ml of N-methyl pyrrolidone, carrying out ultrasonic dispersion for 20-30 min, then adding 0.5g of KH560, carrying out continuous ultrasonic treatment for about 5 min, transferring the mixture into a four-mouth bottle under the atmosphere of N2, stirring and reacting at 50-60 ℃ for 3-4 h, carrying out centrifugal separation on the reaction liquid, precipitating the modified silicon dioxide, and drying to obtain the hydrophobic nano silicon dioxide with the grafting rate of 2-5%.

20g of the prepared modified polyisophthaloyl metaphenylene diamine polymer is dissolved in 35g of NMP solvent, and the aramid wire enamel can be obtained after appropriate heating, dissolution and uniform stirring.

Example 2

An aramid wire enamel comprises a modified polyisophthaloyl metaphenylene diamine polymer and a solvent;

the modified polyisophthaloyl metaphenylene diamine polymer is obtained by polymerizing metaphenylene diamine, isophthaloyl dichloride and 4, 4' -diaminodiphenyl ether, and the specific preparation process comprises the following steps:

1) adding 2g of 4,4 '-diaminodiphenyl ether and 9.41g of m-phenylenediamine into a pressure reactor which is provided with a stirrer and connected with a dry nitrogen pipe, adding 15.99g of acid-binding agent pyridine, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, keeping for a period of time, converting the carbon dioxide into a supercritical state, and preparing a mixed solution of 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide after substances in the pressure reactor are dissolved; adding 0.06g of hydrophobic nano-silica and 19.36g of isophthaloyl dichloride into another pressure reactor which is provided with a stirrer and is connected with a dry nitrogen pipe, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, and dissolving substances in the pressure reactor to prepare isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; adding isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution into a mixed solution of 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid binding agent-supercritical carbon dioxide under rapid stirring, always keeping the supercritical state of carbon dioxide, and continuously stirring for reaction;

2) preparing 0.1g of hydrophobic nano-silica and 6.45g of isophthaloyl dichloride to obtain a new isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; 4,4 '-diaminodiphenyl ether, 2.7g m-phenylenediamine and 5.33g acid-binding agent pyridine are prepared into a novel 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution. After reacting for 2-30 minutes in the step 1), adding a newly-configured isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution and a 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution, and continuously stirring for reaction until the reaction is finished. Adjusting the temperature and pressure of the reactor to a non-critical state, adding 200 g of water into the pressure reactor, stirring for 30 minutes in the non-critical state, standing for layering, discharging wastewater, washing for four times according to the step, adding 500 g of deionized water, and gradually discharging CO₂The gas is compressed again, condensed and recycled; and performing post-treatment such as centrifugal filtration and washing to remove residual acid-binding agent, and drying for later use.

In this example, the preparation method of the hydrophobic nano-silica is the same as that of example 1.

35g of the prepared modified polyisophthaloyl metaphenylene diamine polymer is dissolved in 100g of NMP solvent, and the aramid wire enamel can be obtained after appropriate heating, dissolution and uniform stirring.

Example 3

An aramid wire enamel comprises a modified polyisophthaloyl metaphenylene diamine polymer and a solvent;

the modified polyisophthaloyl metaphenylene diamine polymer is obtained by polymerizing metaphenylene diamine, isophthaloyl dichloride and 4, 4' -diaminodiphenyl ether, and the specific preparation process comprises the following steps:

1) adding 2g of 4,4 '-diaminodiphenyl ether and 9.73g of m-phenylenediamine into a pressure reactor which is provided with a stirrer and is connected with a dry nitrogen pipe, adding 21.1g of triethylamine as an acid-binding agent, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, keeping for a period of time, converting the carbon dioxide into a supercritical state, and dissolving substances in the pressure reactor to prepare a mixed solution of the 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide; adding 0.08g of hydrophobic nano-silica and 20.0g of isophthaloyl dichloride into another pressure reactor which is provided with a stirrer and is connected with a dry nitrogen tube, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, and dissolving substances in the pressure reactor to prepare isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; adding isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution into a mixed solution of 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid binding agent-supercritical carbon dioxide under rapid stirring, always keeping the supercritical state of carbon dioxide, and continuously stirring for reaction;

2) preparing 0.07g of hydrophobic nano-silica and 3.53g of isophthaloyl dichloride to obtain a new isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; 0.7g of 4,4 '-diaminodiphenyl ether, 1.52g of m-phenylenediamine and 3.72g of acid-binding agent triethylamine are prepared to obtain a novel 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution. After reacting for 2-30 minutes in the step 1), adding a newly-prepared isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution and a 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution, continuously stirring and reacting until the reaction is finished, and adjusting the temperature and the pressure of the reactor to be non-criticalAdding 200 g of water into a pressure reactor, stirring for 30 minutes in a non-critical state, standing for layering, discharging wastewater, washing for four times according to the step, adding 500 g of deionized water, and gradually discharging CO₂The gas is compressed again, condensed and recycled; and performing post-treatment such as centrifugal filtration and washing to remove residual acid-binding agent, and drying for later use.

In this example, the preparation method of the hydrophobic nano-silica is the same as that of example 1.

45g of the prepared modified polyisophthaloyl metaphenylene diamine polymer is dissolved in 110g of NMP solvent, and the aramid wire enamel can be obtained after proper heating, dissolution and uniform stirring.

Example 4

An aramid wire enamel comprises a modified polyisophthaloyl metaphenylene diamine polymer and a solvent;

the modified polyisophthaloyl metaphenylene diamine polymer is obtained by polymerizing metaphenylene diamine, isophthaloyl dichloride and 4, 4' -diaminodiphenyl ether, and the specific preparation process comprises the following steps:

1) adding 2g of 4,4 '-diaminodiphenyl ether and 10.27g of m-phenylenediamine into a pressure reactor which is provided with a stirrer and is connected with a dry nitrogen pipe, adding 22.11g of triethylamine as an acid-binding agent, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, keeping for a period of time, converting the carbon dioxide into a supercritical state, and dissolving substances in the pressure reactor to prepare a mixed solution of the 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide; adding 0.02g of hydrophobic nano-silica and 20.96g of isophthaloyl dichloride into another pressure reactor which is provided with a stirrer and is connected with a dry nitrogen pipe, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, and dissolving substances in the pressure reactor to prepare isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; adding isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution into a mixed solution of 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid binding agent-supercritical carbon dioxide under rapid stirring, always keeping the supercritical state of carbon dioxide, and continuously stirring for reaction;

2) preparing 0.09g of hydrophobic nano-silica and 5.24g of isophthaloyl dichloride to obtain a new isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; 0.96g of 4,4 '-diaminodiphenyl ether, 2.32g of m-phenylenediamine and 5.53g of acid-binding agent triethylamine are prepared to obtain a novel 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution. After reacting for 2-30 minutes in the step 1), adding a newly-configured isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution and a 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution, and continuously stirring for reaction until the reaction is finished. Adjusting the temperature and pressure of the reactor to a non-critical state, adding 200 g of water into the pressure reactor, stirring for 30 minutes in the non-critical state, standing for layering, discharging wastewater, washing for four times according to the step, adding 500 g of deionized water, and gradually discharging CO₂The gas is compressed again, condensed and recycled; and performing post-treatment such as centrifugal filtration and washing to remove residual acid-binding agent, and drying for later use.

In this example, the preparation method of the hydrophobic nano-silica is the same as that of example 1.

60g of the prepared modified polyisophthaloyl metaphenylene diamine polymer is dissolved in 120g of NMP solvent, and the aramid wire enamel can be obtained after proper heating, dissolution and uniform stirring.

Example 5

An aramid wire enamel comprises a modified polyisophthaloyl metaphenylene diamine polymer and a solvent;

the modified polyisophthaloyl metaphenylene diamine polymer is obtained by polymerizing metaphenylene diamine, isophthaloyl dichloride and 4, 4' -diaminodiphenyl ether, and the specific preparation process comprises the following steps:

1) adding 2g of 4,4 '-diaminodiphenyl ether and 10.81g of m-phenylenediamine into a pressure reactor which is provided with a stirrer and is connected with a dry nitrogen pipe, adding 23.09g of triethylamine as an acid-binding agent, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, keeping for a period of time, converting the carbon dioxide into a supercritical state, and dissolving substances in the pressure reactor to prepare a mixed solution of the 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide; adding 0.04g of hydrophobic nano-silica and 21.89g of isophthaloyl dichloride into another pressure reactor which is provided with a stirrer and is connected with a dry nitrogen tube, replacing original gas with nitrogen, adding liquid carbon dioxide, keeping the temperature at 35 ℃ and the pressure at 8MPa, and dissolving substances in the pressure reactor to prepare isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; adding isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution into a mixed solution of 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid binding agent-supercritical carbon dioxide under rapid stirring, always keeping the supercritical state of carbon dioxide, and continuously stirring for reaction;

2) preparing 0.06g of hydrophobic nano-silica and 4.81g of isophthaloyl dichloride to obtain a new isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution; 0.8g of 4,4 '-diaminodiphenyl ether, 2.17g of m-phenylenediamine and 5.07g of acid-binding agent triethylamine are prepared to obtain a novel 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution. After reacting for 2-30 minutes in the step 1), adding a newly-configured isophthaloyl dichloride-hydrophobic nano-silica-supercritical carbon dioxide solution and a 4, 4' -diaminodiphenyl ether-m-phenylenediamine-acid-binding agent-supercritical carbon dioxide solution, and continuously stirring for reaction until the reaction is finished. Adjusting the temperature and pressure of the reactor to a non-critical state, adding 200 g of water into the pressure reactor, stirring for 30 minutes in the non-critical state, standing for layering, discharging wastewater, washing for four times according to the step, adding 500 g of deionized water, and gradually discharging CO₂The gas is compressed again, condensed and recycled; and performing post-treatment such as centrifugal filtration and washing to remove residual acid-binding agent, and drying for later use.

In this example, the preparation method of the hydrophobic nano-silica is the same as that of example 1.

30g of the prepared modified polyisophthaloyl metaphenylene diamine polymer is dissolved in 60g of NMP solvent, and the aramid wire enamel can be obtained after appropriate heating, dissolution and uniform stirring.

Comparative example 1

This example is the same as example 1 except that no hydrophobic nano silica was added in step 1).

Comparative example 2

This example is the same as example 1 except that no hydrophobic nano silica was added in step 2).

Comparative example 3

This example is the same as example 2 except that 0.02g of hydrophobic nano-silica was added in step 1) and 0.03g of hydrophobic nano-silica was added in step 2).

Comparative example 4

This example is the same as example 2 except that 0.12g of hydrophobic nano-silica was added in step 1) and 0.11g of hydrophobic nano-silica was added in step 2).

Comparative example 5

This example is the same as example 3, except that the molar ratio of 4, 4' -diaminodiphenyl ether to m-phenylenediamine in step 1) is adjusted to 1: 6.5, and the specific changes are as follows: in the step 1), the addition amount of the m-phenylenediamine is 6.5g, the addition amount of the m-phenylenediamine formyl chloride is 15g, the addition amount of the corresponding hydrophobic nano-silica is 0.06g, the addition amount of the acid-binding agent is 15.82g, and in the step 2), the addition amounts of the 4, 4' -diaminodiphenyl ether, the m-phenylenediamine, the isophthaloyl dichloride and the hydrophobic nano-silica are 0.53g, 1.14g, 2.65g and 0.05g respectively.

Comparative example 6

This example is the same as example 3, except that the molar ratio of 4, 4' -diaminodiphenyl ether to m-phenylenediamine in step 1) is adjusted to 1: 11, and the specific changes are as follows: in the step 1), the addition amount of the m-phenylenediamine is 11.9g, the addition amount of the m-phenylenediamine formyl chloride is 24g, the addition amount of the corresponding hydrophobic nano-silica is 0.1g, the addition amount of the acid binding agent is 25.31g, and in the step 2), the addition amounts of the 4, 4' -diaminodiphenyl ether, the m-phenylenediamine, the isophthaloyl dichloride and the hydrophobic nano-silica are 0.85g, 1.83g, 4.24g and 0.08g respectively.

Comparative example 7

This example is the same as example 4, except that the molar ratio of 4, 4' -diaminodiphenyl ether to m-phenylenediamine in step 2) is adjusted to 1: 2, and the specific changes are as follows: in the step 2), the adding amount of the 4, 4' -diaminodiphenyl ether and the m-phenylenediamine is 1.75g and 1.89g respectively.

Comparative example 8

This example is the same as example 4, except that the molar ratio of 4, 4' -diaminodiphenyl ether to m-phenylenediamine in step 2) is adjusted to 1: 6, and the specific changes are as follows: in the step 2), the adding amount of the 4, 4' -diaminodiphenyl ether and the m-phenylenediamine is 0.75g and 2.43g respectively.

Comparative example 9

This example is similar to example 5, except that the hydrophobic nanosilica grafting ratio is less than 2%.

In this embodiment, the preparation method of the hydrophobic nano-silica comprises: adding dried 1g of nano silicon dioxide powder into 20ml of N-methyl pyrrolidone, carrying out ultrasonic dispersion for 20-30 min, then adding 0.5g of KH560, continuing ultrasonic treatment for about 5 min, transferring the mixture into a four-mouth bottle under the atmosphere of N2, stirring and reacting for 2.5 h at 45 ℃, carrying out centrifugal separation on the reaction liquid, precipitating the modified silicon dioxide, and drying to obtain the hydrophobic nano silicon dioxide.

Comparative example 10

This example is similar to example 5, except that the grafting ratio of the hydrophobic nano-silica is greater than 5%.

In this embodiment, the preparation method of the hydrophobic nano-silica comprises: adding dried 1g of nano silicon dioxide powder into 20ml of N-methyl pyrrolidone, carrying out ultrasonic dispersion for 20-30 min, then adding 0.5g of KH560, continuing ultrasonic treatment for about 5 min, transferring the mixture into a four-mouth bottle, stirring and reacting for 4h at 70 ℃ under the atmosphere of N2, carrying out centrifugal separation on the reaction liquid, precipitating the modified silicon dioxide, and drying to obtain the hydrophobic nano silicon dioxide.

The aramid wire enamels provided in examples 1 to 5 and comparative examples 1 to 10 were subjected to performance tests, and the test results are shown in table 1 below:

TABLE 1 aramid fiber enamelled wire paint performance test table

Wherein: the adhesive force is tested by GB/T9286-1998, the breakdown strength is tested by GB/T1408.1-2016, and the heat resistance is tested by GB/T27749-2011; the volume resistance testing method refers to GB/T1410-2006, and tests are carried out after film coating and test results are carried out after the film coating and the hot water soaking at 50 ℃ for 24 hours.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.