CN103834008B

CN103834008B - A kind of o-phthalonitrile resin and preparation method thereof

Info

Publication number: CN103834008B
Application number: CN201410085565.4A
Authority: CN
Inventors: 周恒�; 赵彤; 韩悦
Original assignee: Institute of Chemistry CAS
Current assignee: Institute of Chemistry CAS
Priority date: 2014-03-10
Filing date: 2014-03-10
Publication date: 2016-09-28
Anticipated expiration: 2034-03-10
Also published as: CN103834008A

Abstract

The invention discloses a kind of o-phthalonitrile resin and preparation method thereof.Compared to tradition o-phthalonitrile resin (only 4 nitrophthalonitriles are end-capping reagent), this resin introduces the collaborative end-blocking of 3 nitrophthalonitriles, thus adds the unsymmetry of resin structure, add the randomness (see formula 1) of resin Composition.The o-phthalonitrile resin of the present invention, compared to tradition o-phthalonitrile resin, has melt temperature low, and dissolubility is good, process window width, the features such as solidification temperature is low, the resin mold casting die of preparation and polymer matrix composites, porosity is low, fine heat-resisting performance, mechanical property is high, can be as lightweight, high temperature resistant component, in Aero-Space, space technology, the application of the field such as machine-building.

Description

Phthalonitrile resin and preparation method thereof

Technical Field

The invention relates to a thermosetting phthalonitrile resin and a preparation method thereof

Background

Resin Matrix composites (Resin Matrix composites) are a class of composites that are currently mature and widely used in the art. The raw material of resin-based composite material includes matrix phase, reinforcing phase and additive. The matrix phase material refers to various polymers as a matrix, including thermosetting resins and thermoplastic resins, and the reinforcing phase refers to various fibers, such as glass fibers, carbon fibers, aramid fibers, high-density polyethylene fibers, and the like.

The thermosetting matrix resin of the resin-based composite material mainly comprises three types of epoxy resin, bismaleimide resin and polyimide resin, wherein only the temperature resistance grade of the polyimide can reach and exceed 300 ℃. Phthalonitrile resins are another class of resin systems that are considered to be temperature tolerant beyond 300 ℃.

From the 80 s of the last century, phthalonitrile monomers with various structures are synthesized, the synthesis is basically shown as a reaction formula 1, 4-nitrophthalonitrile and dihydric phenol generate bisphthalonitrile monomers with end caps at two ends under the catalysis of anhydrous potassium carbonate, the reaction is generally carried out in strong polar solvents such as N, N-Dimethylformamide (DMF) or N, N-dimethylacetamide (DMAc), and the reaction temperature is from 80 ℃ to 140 ℃.

Reaction formula 1 synthetic route of bisphthalonitrile monomer

The phthalonitrile resin system has excellent high temperature resistance, and the heat-resistant temperature can reach 350 ℃, even 450 ℃ without definite glass transition temperature. The phthalonitrile resin is addition cured, no micromolecule is released in the curing process, the porosity is low, and the mechanical property is excellent. Researches show that the phthalonitrile/carbon fiber composite material has equivalent or even slightly excellent performance with a polyimide resin PMR-15 composite material with better traditional application performance, so that the phthalonitrile/carbon fiber composite material is possibly used as a light and high-temperature resistant structural part and applied in the fields of aerospace, space technology, mechanical manufacturing and the like. In addition, the phthalonitrile condensate has the characteristics of low water absorption, excellent flame-retardant and fireproof performance and the like, and is possibly applied to the field of ships.

However, phthalonitrile resins generally have a problem that the melting point is high, the melting temperature of monomers is closely related to the processability, and the high melting temperature causes the processing window of the resin to be narrow and the processability to be poor. According to the literature reports, the relationship between the structure of various monomers and the melting point is shown in Table 1.

TABLE 1 melting points of phthalonitrile monomers of various structures

As can be seen from Table 1, the phthalonitrile monomers have high melting points, which are close to or exceed 200 ℃, and bring about certain inconvenience to the molding process. Foreign scholars study more biphenyl structure phthalonitrile monomer with melting point as high as 230 ℃, and the processing window of the resin system is narrower after the biphenyl structure phthalonitrile monomer is blended with a catalyst. Based on this, foreign scholars began to lower the melting point of phthalonitrile monomer and synthesized a series of monomers with longer bridge chain segment between the end capping groups, as shown in table 2.

TABLE 2 phthalonitrile monomer structure containing longer chain units and melting temperature interval

The main chains of the molecules listed in the table have a certain length, the crystallinity of the molecules is gradually reduced and is possibly in an amorphous state, the melting point or Tg is also reduced to about 100 ℃ or even lower, and certain convenience is brought to processing and forming, but a longer chain segment needs higher curing temperature to reach the thermal property of a short chain segment resin cured product, the maximum curing temperature of the short chain segment is 375 ℃, and the maximum curing temperature of the long chain segment is often as high as 425 ℃.

The invention introduces 3-nitro-1, 2-phthalonitrile (3-nitrophthalonitrile) into a resin system for the first time, and the 3-nitro-1, 2-phthalonitrile (4-nitrophthalonitrile) is cooperated with 4-nitro-1, 2-phthalonitrile to be used as an end capping group, and the end capping groups of para-phthalonitrile and meta-phthalonitrile can be adjusted randomly along with different charge ratios. The introduction of the meta-phthalonitrile end-capping group increases the asymmetry of the molecular structure, increases the chaos degree of resin composition, effectively reduces the melting point of phthalonitrile resin, improves the solubility of the resin, and greatly improves the processing technological performance of phthalonitrile resin. And experiments prove that the heat resistance and the mechanical property of the resin are not reduced by introducing the meta-phthalonitrile structure.

Disclosure of Invention

The invention aims to provide a novel thermosetting low-melting-point phthalonitrile resin.

Another object of the present invention is to provide a method for preparing the above matrix resin.

The invention is realized by the following technical scheme:

a phthalonitrile resin, characterized in that the resin is selected from a mixture of three polymers represented by the following formula (1), formula (2) or formula (3).

Wherein n is₁、n₂、n₃Each independently selected from an integer of 0 to 4;

r in the formulae₁Each independently selected from

R₂Each independently selected from

R₃Each independently selected from

According to the invention, the molar ratio of formula (1), formula (2) and formula (3) in the mixture is (20-45): (40-60): (10-25), preferably (25-40): 45-55): 12-20, more preferably 36:49: 15.

According to the invention, R in formula (1) is preferably₁And R in the formulae (2) and (3)₁The structures are the same; or R in the formula (1)₂And R in the formulae (2) and (3)₂The structures are the same; or, R in the formula (1)₃And R in the formulae (2) and (3)₃The structures are the same. Due to R in each component structure in the mixture₁And R₂Depending on the starting material, R in different molecular structures once the starting material is determined₁And R₂Namely a fixed structure.

According to a preferred embodiment of the invention, the mixture of resins is selected from:

or, selected from:

the invention also provides a preparation method of the phthalonitrile resin, which is characterized by comprising the following steps:

dissolving the phthalonitrile end capping agent in an organic solvent according to a certain proportion, slowly dripping the end capping agent into a solution of aromatic dihydric phenol and an optional aromatic binary halogenated compound dissolved in the organic solvent, and reacting under the conditions of a catalyst and an optional dehydrating agent to prepare phthalonitrile resin.

Wherein R1, R2, R3, n1, n2, n3 are as defined above.

Preferably, the first and second electrodes are formed of a metal,

when n1, n2 and n3=0, dissolving the phthalonitrile end-capping reagent in an organic solvent according to a certain proportion, slowly dropwise adding the mixture into an aromatic dihydric phenol solution dissolved in the organic solvent, and reacting under the conditions of a catalyst and an optional dehydrating agent to prepare the phthalonitrile resin mixture. Or,

when n1, n2 and n3=1-4 integers, dissolving the phthalonitrile end-capping reagent in an organic solvent according to a certain proportion, slowly dropwise adding the phthalonitrile end-capping reagent into a solution of aromatic dihydric phenol and an aromatic binary halogenated compound dissolved in the organic solvent, and reacting under the conditions of a catalyst and an optional dehydrating agent to prepare phthalonitrile resin.

According to the invention, the phthalonitrile blocking agent is selected from 3-nitro-1, 2-phthalonitrile or a mixture of 3-nitro-1, 2-phthalonitrile and 4-nitro-1, 2-phthalonitrile.

According to the invention, the aromatic dihydric phenol is one or a mixture of any two of catechol, resorcinol, hydroquinone, 4,4 '-biphenol, 4,4' -dihydroxy diphenylmethane, bisphenol A, 6F bisphenol A and dihydric phenol with polyimide structure.

According to the invention, the aromatic binary halogenated compound is one or a mixture of any two of 4,4 '-difluorobenzophenone, m-phenylbromide, bis (4-fluorophenyl) phenylphosphine oxide and 4,4' -dichlorodiphenyl sulfone.

According to the invention, the molar ratio of the aromatic dihydric phenol to the aromatic binary halogenated compound to the phthalonitrile-based capping agent is as follows: (n +1) n:2, wherein n =0-4, and n includes any one of n1, n2, and n 3.

According to the process of the present invention, the organic solvent is N, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide or N-methylpyrrolidone, or any mixture thereof.

Preferably, the molar part ratio of the aromatic dihydric phenol to the organic solvent is 1: 11.7-37.2, wherein the molar part ratio of the aromatic binary halogenated compound to the organic solvent is 1: 10.6-24.8.

The catalyst is anhydrous potassium carbonate, anhydrous sodium carbonate, potassium hydroxide, sodium hydroxide or any mixture thereof; the dehydrating agent is a mixture of cuprous iodide and phenanthroline.

Preferably, the aromatic dihydric phenol and the optional aromatic binary halogenated compound are dissolved in the organic solvent at room temperature under the protection of inert gas.

Preferably, the method comprises: dissolving the aromatic dihydric phenol and the optional aromatic binary halogenated compound in an organic solvent at room temperature (5-30 ℃) under the protection of inert gas, adding a catalyst, and heating to 50-130 ℃.

Preferably, the method further comprises maintaining the reaction system at an incubation temperature for 5 to 12 hours, preferably 6 to 10 hours, after the above reaction is completed.

Still more preferably, after the completion of the incubation reaction, the reaction system is cooled to room temperature, the solution system is precipitated in several times of distilled water or a slightly acidic aqueous solution, and the product is obtained by filtration. Still more preferably, the resin powder is obtained by washing the resin powder with distilled water, a mixture of distilled water and acetone, or methanol, and then drying the resin powder in the air or in a vacuum oven at room temperature.

Preferably, when n =0, the method specifically comprises the steps of:

1) dissolving the aromatic dihydric phenol in an organic solvent at room temperature (5-30 ℃) under the protection of inert gas;

2) adding a catalyst and an optional dehydrating agent into the reaction solution, and heating to 50-130 ℃;

3) dissolving the phthalonitrile end-capping reagent in an organic solvent according to a certain proportion, and slowly dripping the solution;

4) after the dropwise addition is finished, the reaction liquid system is subjected to heat preservation reaction for 5-12 hours;

5) after the reaction is finished, cooling the reaction system to room temperature, precipitating the solution system in several times of distilled water or a slightly acidic aqueous solution, filtering to obtain a product, fully washing the product with distilled water, a mixed solution of distilled water and acetone or methanol, and airing at room temperature or drying in a vacuum oven to obtain the final resin powder.

Reaction formula 2: synthetic route of n =0 phthalonitrile monomer

When n =1-4

1) Dissolving the aromatic dihydric phenol and the aromatic binary halogenated compound in an organic solvent at room temperature (5-30 ℃) under the protection of inert gas;

2) adding a catalyst and a dehydrating agent into the reaction solution, and heating to 100-180 ℃ for reflux dehydration reaction for 5-15 hours;

3) controlling the reaction liquid system at 50-130 ℃, dissolving the phthalonitrile end-capping reagent in an organic solvent according to a certain proportion, and slowly dripping the solution;

Reaction formula 3: synthetic route of n =1-4 phthalonitrile monomer

The phthalonitrile resin matrix is prepared by using aromatic dihydric phenol, an aromatic binary halogenated compound and a capping agent containing phthalonitrile as raw materials and adopting a two-step method, namely reacting the dihydric phenol and the binary halogenated compound under the protection of inert gas and the action of a catalyst and a dehydrating agent to generate a bisphenol compound, then adding a nitrophthalonitrile compound, reacting for 5-12 hours at 50-130 ℃ to obtain a product solution, finally precipitating the solution in distilled water or olefine acid aqueous solution which is multiplied by several times, and washing, drying and purifying to finally obtain phthalonitrile solid powder. The 3-nitrophthalonitrile used increases the asymmetry of molecules and the chaos degree of resin composition, thereby reducing the melting point of the resin, improving the solubility of the resin and achieving the purpose of improving the processing manufacturability of the resin.

The invention also provides the application of the phthalonitrile resin mixture in the preparation of composite materials.

According to the invention, the phthalonitrile resin can be freely cured or molded to obtain a resin molded part, or can be dissolved in an organic solvent to be compounded with a reinforcement to prepare a prepreg, and the prepreg is prepared by a mold pressing or autoclave process, or can be directly prepared by a Resin Transfer Molding (RTM) process or a resin film infiltration technology (RFI).

The novel phthalonitrile resin has lower melting point, different proportions of end-capping groups and different degrees of polymerization along with different main chain structures, and the melting point range of the resin system is 25-150 ℃, which is obviously lower than that of the traditional single 4-nitrophthalonitrile end-capped resin system. Compared with the traditional phthalonitrile resin (only 4-nitrophthalonitrile is used as a blocking agent), the 3-nitrophthalonitrile is introduced into the resin for blocking cooperatively, so that the asymmetry of the resin structure is increased, and the chaos degree of the resin components is increased (see formula 1). The resin system has better solubility in strong polar solvents such as N, N-dimethylformamide, N-dimethylacetamide and the like, and the solubility is obviously higher than that of the traditional single 4-nitrophthalonitrile terminated resin system. In addition, rheological tests show that compared with the 4-nitro-terminated phthalonitrile resin, the novel phthalonitrile resin disclosed by the invention has lower melt viscosity and wider processing window, and is suitable for composite material forming process methods such as a mould pressing process and Resin Transfer Molding (RTM). The resin system can be cured at the temperature of 150-170 ℃ and post-treated and cured at the temperature of 250-375 ℃.

The reaction is nucleophilic substitution reaction under base catalysis, phthalonitrile resin with different composition structures and different composition ratios can be obtained by controlling the proportion and the speed of feeding, and brown resin powder is obtained after precipitation, water washing and purification.

Compared with the traditional phthalonitrile resin, the novel phthalonitrile resin has the characteristics of low melting temperature, good solubility, wide processing window, low curing temperature and the like, and the composite material prepared from the prepared resin molded part and the resin matrix has low porosity, excellent heat resistance and higher mechanical property, and can be applied to the high and new technical fields of light and high-temperature resistant structural parts such as aerospace, space technology, mechanical manufacturing and the like. And the coating has low water absorption rate and excellent flame-retardant and fireproof performance, and can be applied to the field of marine ships.

Detailed Description

The present invention is illustrated in detail by the following examples. However, it is understood by those skilled in the art that the following examples are not intended to limit the scope of the present invention. Any modifications and variations made on the basis of the present invention are within the scope of the present invention.

Example 1

0.2mol of 4,4' -biphenol is dissolved in 2.34mol of N, N-Dimethylformamide (DMF) at room temperature under the protection of nitrogen, 0.3mol of anhydrous potassium carbonate is added thereto, and the temperature is raised to 80 ℃. 0.15mol of 4-nitrophthalonitrile and 0.25mol of 3-nitrophthalonitrile are dissolved in 4.68mol of DMF, slowly added dropwise into the solution, and after the dropwise addition is finished, the reaction is carried out for 8 hours at 80 ℃. After the reaction is finished, firstly cooling the solution system to room temperature, then slowly precipitating the solution in 5 times of distilled water to obtain a brown yellow precipitate, repeatedly washing the precipitate with distilled water until the filtrate is clear and the pH value is neutral, and drying in a vacuum oven at 60 ℃ for 8 hours to obtain a brown yellow powder product, wherein the structure of the product is shown as the following formula, and the yield is 85%.

The softening point of the resin is 85-90 ℃, and the melting temperature is reduced by over 100 ℃ compared with that of a product (melting point 232-.

Under the protection of nitrogen, the phthalonitrile resin obtained by the method is heated to a molten state, 5 to 10 percent of amino-containing catalyst in molar ratio is added into the phthalonitrile resin, and the mixture is uniformly blended and cooled to room temperature. And dissolving the resin in a DMF solution, compounding the solution with high-strength glass cloth to prepare a prepreg, and drying the prepreg for 2 hours in a 120-DEG C blast oven after most of the solvent is volatilized. Taking out the prepreg cloth, stacking and laying the prepreg cloth as required, placing the prepreg cloth in a mold, placing the mold in a press, keeping the temperature at 140 ℃ for 0.5 hour, directly heating to 170 ℃, pressurizing for 1-1.5 hours under 1.0MPa, keeping the temperature at 170 ℃ for 3 hours, keeping the temperature at 200 ℃ for 1 hour, and then heating to 250 ℃ for 5 hours. Naturally cooling to room temperature to obtain the phthalonitrile composite laminated board, and placing the phthalonitrile composite laminated board into an oven for free post-treatment at 315 ℃/3 h +375 ℃/5 h. The glass transition temperature of the laminate is greater than 450 ℃ (DMA) and the 5% weight loss temperature is greater than 520 ℃ (TGA).

Example 2

Under the protection of nitrogen at room temperature, 0.2mol of bisphenol A and 0.1mol of 4,4' -difluorobenzophenone are dissolved in 7.2mol of N-methylpyrrolidone (NMP), 0.4mol of anhydrous potassium carbonate is added into the solution, the temperature is raised to 100 ℃, the stirring reaction is carried out for 1 hour, then the water knockout vessel is filled with toluene, 20ml of toluene is added into the reaction system, the temperature is raised to 170-175 ℃, the reflux reaction is carried out for 14 hours, and the water generated by the reaction is removed. The reaction solution was cooled to 60 ℃ and 0.05mol of 4-nitrophthalonitrile and 0.05mol of 3-nitrophthalonitrile were dissolved in 2.34mol of NMP and slowly added dropwise thereto, and after the addition was completed, the reaction was maintained at 60 ℃ for 6 hours. After the reaction is finished, firstly cooling the solution system to room temperature, then slowly precipitating the solution in a 5-time diluted hydrochloric acid distilled water solution to obtain brown precipitate, repeatedly washing the precipitate with distilled water until the filtrate is clear and the pH value is neutral, further washing the crude product with a mixed solvent of acetone and water, and drying the crude product at room temperature to obtain a final product, wherein the structure is shown as the following formula, the softening point is 50-55 ℃, and the yield is reduced by over 50 ℃ compared with the product obtained by only using 4-nitrophthalonitrile for reaction, and the yield is 78%.

Example 3

Under the protection of argon at room temperature, 0.3mol of hydroquinone and 0.2mol of m-dibromo benzene are dissolved in 10.8mol of N, N-Dimethylformamide (DMF), 0.0064mol of 1, 10-phenanthroline, 0.0035mol of cuprous iodide and 0.7mol of anhydrous potassium carbonate are added into the DMF, then toluene is fully added into a water separator, 20ml of toluene is added into a reaction system, the temperature is raised to 140 ℃ and 145 ℃, reflux reaction is carried out for 16 hours, and no water is generated. The reaction solution was cooled to 80 ℃ and 0.025mol of 4-nitrophthalonitrile and 0.075mol of 3-nitrophthalonitrile were dissolved in 2.34mol of DMF and slowly added dropwise to the above solution, after the dropwise addition was completed, the reaction was maintained at 80 ℃ for 8 hours. After the reaction is finished, firstly cooling the solution system to room temperature, then slowly precipitating the solution in 6 times of dilute hydrochloric acid ice water solution to obtain brown precipitate, repeatedly washing the precipitate with ice water until the filtrate is clear and the pH value is neutral, further washing the crude product with methanol, after washing is finished, airing the crude product at room temperature for 48 hours to obtain a brown yellow product, wherein the room temperature is a semi-solid state, the softening point of the brown yellow product is reduced by about 10 ℃ compared with that of a 4-nitrophthalonitrile end-capped product, and the yield is 86%.

Under the protection of nitrogen, the phthalonitrile resin obtained by the method is heated to a molten state, 5 to 10 percent of amino-containing catalyst in molar ratio is added into the phthalonitrile resin, and the mixture is uniformly blended and cooled to room temperature. And dissolving the resin in an acetone solution, compounding the acetone solution with high-strength glass cloth to prepare a prepreg, and drying the prepreg for 2 hours in a 50 ℃ blast oven after most of the solvent is volatilized. Taking out the prepreg cloth, stacking and laying the prepreg cloth as required, placing the prepreg cloth in a mold, placing the mold in a press, keeping the temperature at 140 ℃ for 0.5 hour, directly heating to 170 ℃, pressurizing for 1-1.5 hours under 1.0MPa, keeping the temperature at 170 ℃ for 3 hours, keeping the temperature at 200 ℃ for 1 hour, and then heating to 250 ℃ for 5 hours. Naturally cooling to room temperature to obtain the phthalonitrile composite laminated board, and placing the phthalonitrile composite laminated board into an oven for free post-treatment at 315 ℃/3 h +375 ℃/5 h. The laminate has a glass transition temperature greater than 350 ℃ (DMA) and a 5% weight loss temperature greater than 500 ℃ (TGA).

Example 4

0.2mol of resorcinol was dissolved in 3.51mol of N, N-Dimethylformamide (DMF) at room temperature under nitrogen protection, and 0.3mol of anhydrous potassium carbonate was added thereto and the temperature was raised to 80 ℃. 0.2mol of 4-nitrophthalonitrile and 0.2mol of 3-nitrophthalonitrile are dissolved in 4.68mol of DMF, slowly added dropwise into the solution, and after the dropwise addition is finished, the reaction is carried out for 8 hours at 80 ℃. After the reaction is finished, firstly cooling the solution system to room temperature, then slowly precipitating the solution in 5 times of distilled water to obtain a brown yellow precipitate, repeatedly washing the precipitate with distilled water until the filtrate is clear and the pH value is neutral, and drying in a vacuum oven at 60 ℃ for 8 hours to obtain a brown yellow powder product, wherein the structure of the product is shown as the following formula, and the yield is 88%. The softening point of the resin is 70-75 ℃, and the melting temperature is reduced by over 100 ℃ compared with the product (melting point is 185 ℃) obtained by the reaction of 4-nitrophthalonitrile and resorcinol.

Under the protection of nitrogen, the phthalonitrile resin obtained by the method is heated to a molten state, 5 to 10 percent of amino-containing catalyst in molar ratio is added into the phthalonitrile resin, and the mixture is uniformly blended and cooled to room temperature. And dissolving the resin in an acetone solution, compounding the acetone solution with high-strength glass cloth to prepare a prepreg, and drying the prepreg for 2 hours in a 50 ℃ blast oven after most of the solvent is volatilized. Taking out the prepreg cloth, stacking and laying the prepreg cloth as required, placing the prepreg cloth in a mold, placing the mold in a press, keeping the temperature at 140 ℃ for 0.5 hour, directly heating to 170 ℃, pressurizing for 1-1.5 hours under 1.0MPa, keeping the temperature at 170 ℃ for 3 hours, keeping the temperature at 200 ℃ for 1 hour, and then heating to 250 ℃ for 5 hours. Naturally cooling to room temperature to obtain the phthalonitrile composite laminated board, and placing the phthalonitrile composite laminated board into an oven for free post-treatment at 315 ℃/3 h +375 ℃/5 h. The glass transition temperature of the laminate is greater than 450 ℃ (DMA) and the 5% weight loss temperature is greater than 515 ℃ (TGA).

Example 5

Under the protection of nitrogen at room temperature, 0.2mol of resorcinol and 0.1mol of bis (4-fluorophenyl) phenylphosphine oxide are dissolved in 8.4mol of N, N-dimethylacetamide, 0.4mol of anhydrous potassium carbonate is added into the dimethylacetamide, the temperature is raised to 110 ℃, the mixture is stirred and reacted for 1 hour, then toluene is fully added into a water separator, 20ml of toluene is added into a reaction system, the temperature is raised to 150 ℃ and 155 ℃, the reflux reaction is carried out for 12 hours, and water generated by the reaction is removed. The reaction solution was cooled to 60 ℃ and 0.05mol of 4-nitrophthalonitrile and 0.05mol of 3-nitrophthalonitrile were dissolved in 2.68mol of DMAc and slowly added dropwise to the above solution, after the dropwise addition was completed, the reaction was maintained at 60 ℃ for 8 hours. After the reaction is finished, firstly cooling the solution system to room temperature, then slowly precipitating the solution in a 5-time diluted hydrochloric acid distilled water solution to obtain brown precipitate, repeatedly washing the precipitate with distilled water until the filtrate is clear and the pH value is neutral, further washing the crude product with a mixed solvent of acetone and water, after the washing is finished, drying the crude product at room temperature,

the final product is obtained, the structure is shown as the following formula, the softening point is 40-45 ℃, compared with the product obtained by only using 4-nitrophthalonitrile, the yield is reduced by over 30 ℃, and the yield is 76%.

Examples of the experiments

The molar ratio of the mixtures of examples 1 to 5 can be controlled by controlling the dropping rate and the reaction time. Specifically, in the mixtures obtained by the production methods of examples 1 to 5 of the present invention, the molar ratios of formula (1), formula (2) and formula (3) were (20 to 45): (40-60): (10-25), preferably (25-40): 45-55): 12-20, more preferably 36:49: 15.

Tables 3 and 4 respectively show the thermal properties and mechanical properties of the pure resin cured products and the carbon fiber reinforced composite materials T300 prepared by different molding methods in examples 1 to 3 of the invention.

TABLE 3 typical phthalonitrile resin cured Material thermal Properties and mechanical Properties

Glass transition temperature/. degree.C	350-475	Measurement by DMA method
			Impact Strength/KJ/m²	5-20	GB/T2571-1995
Flexural Strength/MPa	82-118	GB/T2570-1995
			Flexural modulus/GPa	3.8-4.6	GB/T2570-1995

TABLE 4 mechanical properties of typical T300 carbon fiber reinforced phthalonitrile resin composite material

(compression Molding & RTM Molding)

Note: the bending property detection standard is as follows: GB/T3356-1999; the detection standard of the interlaminar shear performance is as follows: GB/T3357-82.

Claims

1. A phthalonitrile resin, characterized in that the resin is selected from a mixture of three polymers represented by the following formula (1), formula (2) or formula (3),

r in the formulae₁Each independently selected from

R₂Each independently selected from

R₃Each independently selected from-O-,or none;

wherein the molar ratio of formula (1), formula (2) and formula (3) in the mixture is (20-45): (40-60): (10-25).

2. The resin of claim 1, wherein the molar ratio of formula (1), formula (2) and formula (3) in the mixture is (25-40): (45-55): (12-20).

3. The resin of claim 2, wherein the molar ratio of formula (1), formula (2), and formula (3) in the mixture is 36:49: 15.

4. A resin according to any of claims 1 to 3, characterized in that R in said formula (1)₁And R in the formulae (2) and (3)₁The structures are the same; or R in the formula (1)₂And R in the formulae (2) and (3)₂The structures are the same; or, R in the formula (1)₃And R in the formulae (2) and (3)₃The structures are the same.

5. Resin according to claim 1, characterized in that it is selected from the following mixtures:

or, selected from:

6. a method for producing a phthalonitrile resin according to any one of claims 1 to 5, characterized in that the steps comprise:

dissolving phthalonitrile end capping reagent in an organic solvent according to a certain proportion, slowly dripping the end capping reagent into a solution of aromatic dihydric phenol and an optional aromatic binary halogenated compound dissolved in the organic solvent, reacting under the condition of a catalyst and an optional dehydrating agent to prepare phthalonitrile resin,

wherein R1, R2, R3, n1, n2, n3 are as defined in any one of claims 1 to 5,

the phthalonitrile end-capping reagent is selected from a mixture of 3-nitro-1, 2-phthalonitrile and 4-nitro-1, 2-phthalonitrile.

7. The production method according to claim 6,

when n1, n2 and n3 are 0, dissolving the phthalonitrile end-capping reagent in an organic solvent according to a certain proportion, slowly dropwise adding the mixture into an aromatic dihydric phenol solution dissolved in the organic solvent, and reacting under the conditions of a catalyst and an optional dehydrating agent to prepare the phthalonitrile resin mixture; or,

when n1, n2 and n3 are integers of 1-4, dissolving the phthalonitrile end-capping reagent in an organic solvent according to a certain proportion, slowly dropwise adding the mixture into a solution of aromatic dihydric phenol and an aromatic binary halogenated compound dissolved in the organic solvent, and reacting under the conditions of a catalyst and an optional dehydrating agent to prepare the phthalonitrile resin.

8. The method according to claim 7, wherein the aromatic dihydric phenol is one or a mixture of any two of catechol, resorcinol, hydroquinone, 4,4 '-biphenol, 4,4' -dihydroxydiphenylmethane, bisphenol A, 6F bisphenol A, a dihydric phenol having a polyimide structure;

the aromatic binary halogenated compound is one or a mixture of any two of 4,4 '-difluorobenzophenone, m-phenylbromide, bis (4-fluorophenyl) phenylphosphine oxide and 4,4' -dichlorodiphenyl sulfone.

9. The preparation method according to any one of claims 6 to 8, characterized in that the molar part ratio of the aromatic dihydric phenol to the aromatic dibasic halogenated compound to the phthalonitrile-based capping agent is as follows: and n is 0-4, wherein n comprises any one of n1, n2 and n 3.

10. The production method according to any one of claims 6 to 8, characterized in that the organic solvent is N, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, or N-methylpyrrolidone, or any mixture thereof;

the catalyst is anhydrous potassium carbonate, anhydrous sodium carbonate, potassium hydroxide, sodium hydroxide or any mixture thereof;

the dehydrating agent is a mixture of cuprous iodide and phenanthroline.

11. Preparation process according to any one of claims 6 to 8, characterized in that the aromatic dihydric phenol and the optional aromatic dibasic halogenated compound are dissolved in an organic solvent at room temperature under protection of an inert gas.

12. The method of manufacturing according to claim 11, characterized in that the method comprises: dissolving the aromatic dihydric phenol and the optional aromatic binary halogenated compound in an organic solvent at the room temperature of 5-30 ℃ under the protection of inert gas, adding a catalyst and an optional dehydrating agent, and heating to 50-130 ℃.

13. The process according to claim 12, further comprising incubating the reaction system for 5 to 12 hours after the completion of the above reaction.

14. The production method according to claim 13, characterized by further comprising allowing the reaction system to react while maintaining the temperature for 6 to 10 hours.

15. The process according to claim 13, wherein the reaction system is cooled to room temperature after the completion of the incubation reaction, the solution system is precipitated in several times of distilled water or a slightly acidic aqueous solution, and the product is obtained by filtration.

16. The method according to claim 15, wherein the resin powder is obtained by washing the resin powder with distilled water, a mixture of distilled water and acetone, or methanol, and then drying the resin powder in the air or in a vacuum oven at room temperature.

17. The production method according to any one of claims 6 to 8,

when n is 0, the method specifically comprises the following steps:

1) dissolving the aromatic dihydric phenol of the formula (5) in an organic solvent at room temperature of 5-30 ℃ under the protection of inert gas;

3) dissolving phthalonitrile end capping agents shown in the formulas (4) and (6) in an organic solvent according to a certain proportion, and slowly dripping the solution;

5) cooling the reaction system to room temperature after the reaction is finished, precipitating the solution system in several times of distilled water or a slightly acidic aqueous solution, filtering to obtain a product, fully washing the product with distilled water, a mixed solution of distilled water and acetone or methanol, airing at room temperature or drying in a vacuum oven to obtain final resin powder,

when n is 1-4, the method specifically comprises the following steps:

1) dissolving aromatic dihydric phenol and aromatic binary halogenated compound shown in formula (8) in an organic solvent at room temperature of 5-30 ℃ under the protection of inert gas,

3) controlling the reaction liquid system at 50-130 ℃, dissolving the phthalonitrile end-capping reagent shown in the formula (7) and the phthalonitrile end-capping reagent shown in the formula (9) in an organic solvent according to a certain proportion, and slowly dripping the solution into the solution;

18. use of the phthalonitrile resin according to any of claims 1 to 5 for the preparation of resin mouldings or resin-based composites.

19. Use of the phthalonitrile resins according to any of claims 1 to 5 in aerospace, space technology, mechanical manufacturing.