CN110776636B - Thermosetting resin based on imidazole dinitrile reactive groups and preparation method thereof - Google Patents
Thermosetting resin based on imidazole dinitrile reactive groups and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a thermosetting resin based on imidazole dinitrile reactive groups and a preparation method thereof, wherein the thermosetting resin is formed by heating and curing a compound containing imidazole dinitrile or a blend of the compound containing imidazole dinitrile and a curing agent, and the mass ratio of the compound containing imidazole dinitrile to the curing agent is 10: (0.7-1.0). The thermosetting resin is prepared by curing a compound containing imidazole dinitrile, or a blend of a compound containing imidazole dinitrile and a curing agent, in a nitrogen atmosphere. The thermosetting resin prepared by the invention has excellent thermal stability, thermo-oxidative stability and structure modifiability, and is a novel material with wide application value.
Description
Technical Field
The invention belongs to the technical field of high-temperature-resistant resin materials, and particularly relates to thermosetting resin taking imidazole dinitrile as a reactive group and a preparation method thereof.
Background
Along with the rapid development of the high-tech fields of aerospace, marine ships, microelectronics and the like, higher requirements are also put forward on the polymer with high-temperature resistance. Thermosetting high-performance resin has the advantages of high temperature resistance, light weight, corrosion resistance and the like, so the thermosetting high-performance resin always belongs to the leading field of high-performance polymer development by virtue of excellent comprehensive performance.
High performance thermosetting resins having different thermosetting grades have been developed in succession, including benzoxazine resins, bismaleimide resins, arylacetylene resins, phthalonitrile resins, and the like. The phthalonitrile resin taking the nitrile group as the reaction group has wide application prospect in the fields of aerospace, marine ships and the like by virtue of excellent heat resistance, thermal mechanical property, flame retardant property and the like. However, since phthalonitrile resins are based mainly on nucleophilic substitution reactions of 4-nitrophthalonitrile with hydroxyl groups and the like, they have the following disadvantages: (1) because the nucleophilic substitution rapid reaction temperature is about 250 ℃ generally, and the subsequent curing temperature is above 300 ℃, the composite modification of phthalonitrile and other resins is hindered; (2) because the nucleophilic substitution reaction is mainly based on 4-nitrophthalonitrile and hydroxyl, etc., the molecular design and the structural modification are not flexible enough.
Therefore, the development of a high-performance thermosetting resin which is comparable to the thermosetting property of the phthalonitrile resin and can improve the defects of the phthalonitrile resin such as high curing temperature, poor decoration and the like has very important significance and great commercial prospect for the development of high-performance polymers.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a thermosetting resin based on an imidazole dinitrile reactive group and a preparation method thereof, and the prepared thermosetting resin has lower curing temperature, excellent thermal stability and thermal-oxygen stability and good structure modification property.
The thermosetting resin based on the imidazole dinitrile reactive group is formed by heating and curing a compound containing the imidazole dinitrile or a blend of the compound containing the imidazole dinitrile and a curing agent, wherein the mass ratio of the compound containing the imidazole dinitrile to the curing agent is 10: (0.7-1.0).
The thermosetting resin based on the imidazole dinitrile reactive group, wherein the compound containing the imidazole dinitrile is one of the following structural formulas:
wherein the content of the first and second substances,
the above-mentioned imidazole dinitrile-containing compound has 4, 5-dicyanoimidazole as a reactive group, and can be cured (or accelerated) by a Lewis acid/Lewis base such as an aromatic amino group, a phenolic hydroxyl group or a metal salt, and a curing group such as a methylene group/methine group, thereby producing a thermosetting resin. The imidazole dinitrile-containing compound has two structural modification sites on an imidazole ring, so that the prepared thermosetting resin has excellent structural modifiability. In addition, due to the unique aromatic heterocyclic structure, the thermosetting resin has potential functionality in the aspects of carbon materials, ionic liquids and the like, so that the prepared thermosetting resin has wide potential application value.
The above thermosetting resin based on an imidazole dinitrile-reactive group, the curing agent is a lewis acid/lewis base, or a compound containing a methylene/methine curing group.
The Lewis acid/Lewis base may be an aromatic amino compound, a phenolic hydroxy compound or a metal salt having a curing function, for example, 3' - (1, 3-phenylenedi (oxy)) diphenylamine, ZnCl2Bisphenol A, and the like. The methylene/methine curable group-containing compound may be 2,2' - (oxybis (4, 1-phenylene)) bis (3 α,4, 7,7a tetrahydro-1H-isoindole-1, 3(2H) -dione), and the like. In a preferred implementation, the curing agent is an amino curing agent, as the amino curing agent can form hydrogen bonds with the imidazole rings, increasing the dispersion uniformity of the curing agent.
The preparation process for thermosetting resins differs for different types of compounds containing imidazole dinitriles, mainly divided into the following two types:
(A) when the imidazole dinitrile-containing compound has the structural formula I, III, IV or VII, since the compound in this case contains an autocatalytic group-NH-, it is possible to obtain a thermosetting resin by curing only the imidazole dinitrile-containing compound as a raw material. The specific operation is as follows: curing the compound containing the imidazole dinitrile at a gradient temperature in a nitrogen atmosphere,
keeping the temperature for 0-10 hours at the temperature T of more than or equal to 150 and less than or equal to 190 ℃,
keeping the temperature for 0-10 hours at the temperature of T more than or equal to 200 and less than or equal to 210 ℃,
keeping the temperature for 0-10 hours at the temperature of more than or equal to 230 and less than or equal to 250 ℃,
t is more than or equal to 290 and less than or equal to 300 ℃, the temperature is kept for 0.5 to 10 hours,
the temperature T is not less than 150 and not more than 190 ℃, the temperature T is not less than 200 and not more than 210 ℃, and the heat preservation time is not more than 230 and not more than 250 ℃ is not 0 at the same time;
or curing the compound containing the imidazole dinitrile at the following temperature and time in sequence:
keeping the temperature for 0-10 hours at the temperature T of more than or equal to 150 and less than or equal to 190 ℃,
keeping the temperature for 0-10 hours at the temperature of T more than or equal to 200 and less than or equal to 210 ℃,
keeping the temperature for 0-10 hours at the temperature of more than or equal to 230 and less than or equal to 250 ℃,
t is more than or equal to 290 and less than or equal to 300 ℃, the temperature is kept for 0-10 h,
keeping the temperature of T more than or equal to 350 and less than or equal to 380 ℃ for 0.5-10 h;
the temperature T is not less than 150 and not more than 190 ℃, the temperature T is not less than 200 and not more than 210 ℃, and the heat preservation time is not more than 230 and not more than 250 ℃ is not 0 at the same time;
after the curing was completed, the resultant product was furnace-cooled to room temperature.
(B) When the structural formula of the compound containing the imidazole dinitrile is I to VII, the compound containing the imidazole dinitrile is used for obtaining the thermosetting resin under the action of the curing agent, and the curing efficiency of the resin can be improved and the curing temperature can be reduced by adding the curing agent. The specific operation comprises the following steps:
(1) mixing a compound containing imidazole dinitrile and a curing agent according to the mass ratio of 10: (0.7-1.0) blending, and uniformly blending a compound containing imidazole dinitrile and a curing agent to obtain a blend;
(2) the resulting blend was cured under nitrogen atmosphere at the following temperatures and times in order:
keeping the temperature for 0-10 hours at the temperature T of more than or equal to 150 and less than or equal to 190 ℃,
keeping the temperature for 0-10 hours at the temperature of T more than or equal to 200 and less than or equal to 210 ℃,
keeping the temperature for 0-10 hours at the temperature of more than or equal to 230 and less than or equal to 250 ℃,
t is more than or equal to 290 and less than or equal to 300 ℃, the temperature is kept for 0.5 to 10 hours,
the temperature T is not less than 150 and not more than 190 ℃, the temperature T is not less than 200 and not more than 210 ℃, and the heat preservation time is not more than 230 and not more than 250 ℃ is not 0 at the same time;
or the obtained blend is cured according to the following temperature and time in sequence:
keeping the temperature for 0-10 hours at the temperature T of more than or equal to 150 and less than or equal to 190 ℃,
keeping the temperature for 0-10 hours at the temperature of T more than or equal to 200 and less than or equal to 210 ℃,
keeping the temperature for 0-10 hours at the temperature of more than or equal to 230 and less than or equal to 250 ℃,
t is more than or equal to 290 and less than or equal to 300 ℃, the temperature is kept for 0-10 h,
keeping the temperature of T more than or equal to 350 and less than or equal to 380 ℃ for 0.5-10 h;
the temperature T is not less than 150 and not more than 190 ℃, the temperature T is not less than 200 and not more than 210 ℃, and the heat preservation time is not more than 230 and not more than 250 ℃ is not 0 at the same time;
after the curing was completed, the resultant product was furnace-cooled to room temperature.
In the preparation method of the thermosetting resin based on the imidazole dinitrile reactive group, in the step (1), the compound containing the imidazole dinitrile and the curing agent are blended in the following two ways:
(i) dissolving a compound containing imidazole dinitrile and a curing agent in a solvent for mixing, and then spin-drying the obtained mixed solution; the solvent is tetrahydrofuran or acetone.
(ii) The imidazole dinitrile-containing compound and the curing agent are mixed by grinding.
According to the thermosetting resin prepared by the method, under the nitrogen atmosphere, the temperature of 5% of the weight loss of the resin can reach 570 ℃, and the carbon residue rate at 800 ℃ can reach 80%, which indicates that the prepared thermosetting resin has good thermal stability; the temperature at which 5% weight loss of the resin is observed, even in an air atmosphere, is not much different from that in a nitrogen atmosphere, indicating that the thermosetting phase resin prepared has good thermo-oxidative stability. And the imidazole group provided by the compound containing the imidazole dinitrile and the unique aromatic heterocyclic structure thereof enable the prepared resin to have excellent structure modifiability.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention takes imidazole dinitrile group as reactive group, and accelerates the curing under the action of curing group to prepare the thermosetting resin with excellent thermal stability and thermo-oxidative stability.
2. The imidazole group and the unique aromatic heterocyclic structure thereof provided by the compound containing the imidazole dinitrile lead the prepared thermosetting resin to have rich modifiable sites, thereby leading the prepared thermosetting resin to show excellent structure modifiable property.
3. The aromatic heterocyclic structure provided by the compound containing the imidazole dinitrile can enable the prepared thermosetting resin to have potential functionality in the aspects of preparing N-doped carbon materials, dielectric materials and the like, so that the prepared thermosetting resin has wide potential application value.
4. The invention is suitable for popularization and development in the field due to wide raw material sources, simple synthesis process and low cost.
Drawings
FIG. 1 is a rheological profile of a blend of DCI and m-APB of example 1 of the present invention.
FIG. 2 is an IR spectrum of a blend of DCI and m-APB of example 1 of the present invention before and after curing.
FIG. 3 shows the results of thermo-gravimetric analysis (TGA) test in example 1 of the present invention; wherein a is a thermogravimetric analysis curve of the DCI under the nitrogen atmosphere, b is a thermogravimetric analysis curve of the m-APB under the nitrogen atmosphere, c is a thermogravimetric analysis curve of a product obtained after the DCI and the m-APB are cured under the nitrogen atmosphere, and d is a thermogravimetric analysis curve of a product obtained after the DCI and the m-APB are cured under the air atmosphere.
Detailed Description
The technical solutions of the present invention are described in detail below with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the following examples:
(1) TGA, T5%: the method is characterized in that a sample is subjected to temperature loss of 5% in a thermogravimetric analyzer TG at a heating rate of 10 ℃/min under a nitrogen atmosphere.
(2) The char yield refers to the residual weight of the sample at 800 ℃ in the thermogravimetric analyzer TG.
Example 1
The preparation method is characterized in that imidazole dinitrile monomolecular resin (4, 5-dicyanoimidazole, DCI, commercially available) and curing agent (3,3' - (1, 3-phenylene di (oxy)) diphenylamine, m-APB) are used as raw materials, and the preparation method comprises the following steps:
(1) dissolving 10g of DCI and 0.8g m-APB in 200mL of tetrahydrofuran, uniformly mixing, and carrying out spin drying and grinding on the obtained mixed solution to obtain blended powder.
(2) And (3) curing the obtained blended powder in a nitrogen atmosphere according to the following temperature gradients in sequence: keeping the temperature at 150 ℃ for 1h, keeping the temperature at 210 ℃ for 10h, keeping the temperature at 290 ℃ for 1h, and cooling to room temperature along with a furnace after curing is finished to obtain the thermosetting resin.
And (2) performing rheological test on the blended powder obtained in the step (1) by using a rheometer to obtain a rheological curve of viscosity changing along with temperature, wherein the rheological curve is shown in figure 1. As can be seen from the figure, the DCI and m-APB blended powder can keep lower viscosity after melting at about 170 ℃, but after 225 ℃, the viscosity begins to rise obviously, which indicates that the DCI and m-APB blended system has undergone a curing reaction.
The infrared analysis was performed on the DCI and m-APB blended powder and the thermosetting resin obtained after curing the two, and the analysis results are shown in FIG. 2. Compared with the characteristic peak before and after m-APB curing, the DCI mainly shows that the nitrile group is 2245cm-1The left and right characteristic peaks are obviously weakened, which indicates that nitrile groups already participate in the reaction, and the blending powder of DCI and m-APB has already undergone a curing reaction.
Thermogravimetric analysis is carried out on the DCI, the m-APB, the DCI and m-APB blended powder and the thermosetting resin obtained after the DCI, the m-APB, the DCI and m-APB blended powder are solidified in a nitrogen atmosphere, and the analysis result is shown in figure 3. As can be seen from the figure, the temperature of 5% weight loss (T5%) of the thermosetting resin obtained after the DCI and m-APB blending system is cured under the nitrogen atmosphere is about 563 ℃, the carbon residue rate at 800 ℃ is 65%, and compared with DCI and m-APB, the thermosetting resin obtained after the DCI and m-APB blending system is cured shows excellent thermal stability. The temperature of 5% weight loss (T5%) of the thermosetting resin obtained after the DCI and m-APB blending system is cured under the air atmosphere is about 561 ℃, and is similar to the temperature of 5% weight loss (T5%) under the nitrogen atmosphere, which shows that the thermosetting resin prepared by the embodiment has excellent thermo-oxidative stability.
Example 2
This example uses an imidazole dinitrile monomolecular resin (2,2', 2"- ((benzene-1, 3, 5-triyltris (oxy)) tris (benzene-4, 1-diyl)) tris (1H-imidazole-4, 5-dinitrile)) and a curing agent ZnCl2The preparation method comprises the following steps:
(1) adding phloroglucinol (10mmol), potassium carbonate (45mmol) and dried DMF (dimethylformamide, 30mL) into a container, heating to 80 ℃ under the condition of stirring, reacting at the temperature for 1h, then cooling to room temperature, adding 4-fluorobenzaldehyde (40mmol) into the container, heating to a reflux state, cooling to room temperature after refluxing for 20h, pouring the obtained reaction liquid into 500mL of ice-water bath for precipitation, adjusting the pH of the mixed liquid containing the precipitate to be neutral by hydrochloric acid, filtering and collecting a filter cake, washing by deionized water, filtering for three times (100 mL each time), collecting the obtained filter cake, and drying at 80 ℃ for 12h under the vacuum condition to obtain an aldehyde group intermediate 1; adding aldehyde group intermediate 1(5mmol), diaminomaleonitrile (20mmol) and dried dioxane (30mL) into a container, heating to a reflux state, refluxing for 10H, cooling to 80 ℃, rapidly adding manganese dioxide (50mmol) into a reaction system, continuously heating to a reflux state, reacting for 50H, cooling to room temperature, filtering and collecting a filter cake, leaching the filter cake with diethyl ether, extracting insoluble substances in the filter cake with THF (tetrahydrofuran), and finally spin-drying the filter cake at 100 ℃ for 5H to obtain a monomer 2,2' - ((benzene-1, 3, 5-triyltris (oxy)) tris (benzene-4, 1-diyl)) tris (1H-imidazole-4, 5-dinitrile) with the structural formula shown below.
(2) Will be provided with10g of the monomer prepared in step (1) and 1.0g of ZnCl2Grinding and blending uniformly to obtain blended powder.
(3) And (3) curing the obtained blended powder in a nitrogen atmosphere according to the following temperature gradients in sequence: keeping the temperature at 250 ℃ for 10h, keeping the temperature at 380 ℃ for 10h, and cooling to room temperature along with the furnace after curing is finished to obtain the thermosetting resin.
Thermogravimetric analysis of the thermosetting resin obtained after curing was carried out under a nitrogen atmosphere, and the temperature at 5% weight loss (T5%) was about 551 ℃ and the residual carbon rate at 800 ℃ was 75%.
Example 3
This example was prepared from imidazole dinitrile monomolecular resin (1,1', 1 "- ((benzene-1, 3, 5-triyltris (oxy)) tris (3- (trifluoromethyl) benzene-4, 1-diyl)) tris (1H-imidazole-4, 5-dinitrile)) and curing agent (2,2' - (oxybis (4, 1-phenylene)) bis (3 α,4, 7,7a tetrahydro-1H-isoindole-1, 3(2H) -dione)) (see Yuan P, Ji S, Hu J, et al. systematic on high density polymerization reaction elastomer and silane: scope, Properties and mechanism [ J ]. 266, 2016,102: 280) as starting materials in the following steps:
(1) adding DCI (15mmol), potassium carbonate (45mmol) and dried DMSO (dimethyl sulfoxide, 60mL) into a container, then reacting for 1h at room temperature under the condition of stirring, adding 2-trifluoromethyl-5-fluoronitrobenzene (15mmol) into the container, heating to 80 ℃, reacting for 24h, then cooling to room temperature, pouring the obtained reaction liquid into 500mL ice water bath for precipitation, then adjusting the pH of the mixed liquid containing the precipitate to be neutral by hydrochloric acid, filtering and collecting a filter cake, washing with deionized water and filtering for three times (100 mL each time), collecting the obtained filter cake, drying for 12h at 80 ℃ under the vacuum condition, then washing for three times (50mL each time) by petroleum ether, collecting the obtained filter cake, and drying for 12h at 110 ℃ under the vacuum condition to obtain an intermediate 2; phloroglucinol (3mmol), potassium carbonate (30mmol) and dry DMSO (60mL) were added to a vessel, reacting for 1h at room temperature under the condition of stirring, adding the intermediate 2(10mmol) into the container, then heating to 110 ℃ for reaction for 24h, then cooling to room temperature, pouring the obtained reaction solution into 500mL of ice-water bath for precipitation, then, the pH of the mixed solution containing the precipitate is adjusted to be neutral by hydrochloric acid, the mixed solution is filtered, a filter cake is collected, the mixed solution is washed by deionized water and filtered for three times (each time, 100mL), the obtained filter cake is collected and dried for 12 hours at 80 ℃ under the vacuum condition, and the monomer (1,1' - ((benzene-1, 3, 5-triyltris (oxygen)) tris (3- (trifluoromethyl) benzene-4, 1-diyl)) tris (1H-imidazole-4, 5-dinitrile)) is obtained, wherein the structural formula is shown as follows.
(2) Dissolving 10g of the monomer prepared in the step (1) and 1.0g of the curing agent in 200mL of acetone, uniformly mixing, and spin-drying and grinding the obtained mixed solution to obtain blended powder.
(3) And (3) curing the obtained blended powder in a nitrogen atmosphere according to the following temperature gradients in sequence: keeping the temperature at 190 ℃ for 10h, keeping the temperature at 230 ℃ for 1h, keeping the temperature at 300 ℃ for 10h, keeping the temperature at 350 ℃ for 1h, and cooling to room temperature along with the furnace after curing is finished to obtain the thermosetting resin.
Thermogravimetric analysis of the thermosetting resin obtained after curing was carried out under nitrogen atmosphere, and the temperature at 5% weight loss (T5%) was about 565 ℃ and the residual carbon rate at 800 ℃ was 78%.
Example 4
This example was prepared from imidazole dinitrile monomolecular resin (2,2' - ((1, 3-phenylenedi (oxy)) bis (4, 1-phenylene)) bis (4, 5-dihydro-1H-imidazole-4, 5-dinitrile)) tris (1H-imidazole-4, 5-dinitrile)) and curing agent bisphenol a by the following steps:
(1) adding resorcinol (10mmol), potassium carbonate (30mmol) and dried DMF (dimethylformamide, 25mL) into a container, heating to 80 ℃ under the condition of stirring, reacting at the temperature for 1h, cooling to room temperature, adding 4-fluorobenzaldehyde (25mmol) into the container, heating to a reflux state, refluxing for 15h, cooling to room temperature, pouring the obtained reaction liquid into 500mL of ice-water bath for precipitation, adjusting the pH of the mixed liquid containing the precipitate to be neutral by hydrochloric acid, filtering, collecting a filter cake, washing with deionized water, filtering for three times (100 mL each time), collecting the obtained filter cake, and drying at 80 ℃ for 12h under the vacuum condition to obtain an aldehyde group intermediate 3; aldehyde intermediate 3(5mmol), diaminomaleonitrile (13mmol) and dried dioxane (35mL) were added to a vessel, then heating to a reflux state under the condition of stirring, cooling to 80 ℃ after refluxing for 10h, quickly adding 100mmol of manganese dioxide into the reaction system, continuously heating to the reflux state, cooling to room temperature after reacting for 40h, filtering and collecting a filter cake, leaching the filter cake with diethyl ether, extracting insoluble substances in the filter cake with DMF (N, N-dimethylformamide), precipitating with water, filtering, collecting the filter cake, spin-drying at 100 deg.C for 5 hr, the monomer 2,2' - ((1, 3-phenylene di (oxy)) di (4, 1-phenylene)) di (4, 5-dihydro-1H-imidazole-4, 5-dinitrile) is obtained, and the structural formula is shown as follows.
(2) Dissolving 10g of the monomer prepared in the step (1) and 0.9g of a curing agent in 150mL of acetone, uniformly mixing, and spin-drying and grinding the obtained mixed solution to obtain blended powder.
(3) And (3) curing the obtained blended powder in a nitrogen atmosphere according to the following temperature gradients in sequence: keeping the temperature at 180 ℃ for 2h, keeping the temperature at 250 ℃ for 1h, keeping the temperature at 300 ℃ for 1h, keeping the temperature at 350 ℃ for 1h, and cooling to room temperature along with the furnace after curing is finished to obtain the thermosetting resin.
Thermogravimetric analysis of the thermosetting resin obtained after curing was carried out under a nitrogen atmosphere, and the temperature at 5% weight loss (T5%) was about 561 ℃ and the residual carbon content at 800 ℃ was 79%.
Example 5
This example was prepared from imidazole dinitrile monomolecular resin (1,1' - ((1, 3-phenylenedi (oxy)) bis (3- (trifluoromethyl) -4, 1-phenylene)) bis (1H-imidazole-4, 5-dinitrile)) and curing agent m-APB by the following steps:
(1) resorcinol (5mmol), potassium carbonate (20mmol) and dry DMSO (50mL) were added to a vessel, then reacting for 1h at room temperature under the condition of stirring, adding the intermediate 2(11mmol) into the container, then heating to 110 ℃ for reaction for 24h, then cooling to room temperature, pouring the obtained reaction solution into 500mL of ice-water bath for precipitation, then adjusting the pH of the mixed solution containing the precipitate to be neutral by using hydrochloric acid, filtering and collecting a filter cake, washing and filtering the filter cake by using deionized water for three times (each time, 100mL), collecting the obtained filter cake, drying the filter cake for 12 hours at 90 ℃ under the vacuum condition, to obtain the monomer 1,1' - ((1, 3-phenylene di (oxy)) di (3- (trifluoromethyl) -4, 1-phenylene)) di (1H-imidazole-4, 5-dinitrile), wherein the structural formula is shown as follows.
(2) Dissolving 10g of the monomer prepared in the step (1) and 0.7g of a curing agent in 100mL of acetone, uniformly mixing, and spin-drying and grinding the obtained mixed solution to obtain blended powder.
(3) And (3) curing the obtained blended powder in a nitrogen atmosphere according to the following temperature gradients in sequence: keeping the temperature at 200 ℃ for 1h, keeping the temperature at 240 ℃ for 1h, keeping the temperature at 300 ℃ for 1h, keeping the temperature at 350 ℃ for 1h, and cooling to room temperature along with the furnace after curing is finished to obtain the thermosetting resin.
Thermogravimetric analysis of the thermosetting resin obtained after curing was carried out under a nitrogen atmosphere, and the temperature at 5% weight loss (T5%) was about 570 ℃ and the residual carbon rate at 800 ℃ was 81%.
Example 6
This example was prepared by curing a monomer containing hydroxyl and imidazole dinitrile (2- (4-hydroxyphenyl) -1H-imidazole-4, 5-dinitrile) as a starting material.
(2- (4-hydroxyphenyl) -1H-imidazole-4, 5-dinitrile) the preparation is described in Bettencourt A, Castro M, Silva J, et al, New Nitrogen Compounds Coupled to Phenolic Units with additives and additives: Synthesis and Structure-Activity Relationship [ J ]. Molles, 2018,23(10):2530, having the formula:
placing (2- (4-hydroxyphenyl) -1H-imidazole-4, 5-dinitrile) in a nitrogen atmosphere, and sequentially carrying out a curing operation according to the following temperature gradients: keeping the temperature at 200 ℃ for 1h, keeping the temperature at 240 ℃ for 1h, keeping the temperature at 300 ℃ for 1h, keeping the temperature at 350 ℃ for 1h, and cooling to room temperature along with the furnace after curing is finished to obtain the thermosetting resin.
Thermogravimetric analysis of the thermosetting resin obtained after curing was carried out under a nitrogen atmosphere, and the temperature at 5% weight loss (T5%) was about 541 ℃ and the residual carbon rate at 800 ℃ was 70%.
Example 7
The preparation method is characterized in that an amino-and imidazole-containing dinitrile monomer (1- (4-aminophenyl) -1H-imidazole-4, 5-dinitrile) is used as a raw material and is prepared according to the following steps:
(1) 3.8937g (33mmol) DCI and 1.48g NaH at 60% were added to the vessel, then dropping dry DMF39ml into the container under the conditions of ice water bath and stirring, slowly releasing hydrogen from the obtained reaction system, after the dropping of DMF, the reaction system was allowed to continue reacting at room temperature for 2 hours, after which 4.23g (29mmol) of parafluoronitrobenzene dissolved in 42ml of DMF was added to the resulting reaction system, then heating the obtained reaction system to 90 ℃ for reaction for 6h, cooling to room temperature after the reaction is finished, then evaporating most of solvent (about 70mL) in a rotary manner, slowly pouring the reaction liquid into 200mL of deionized water, stirring for ten minutes, filtering, repeating the water washing for three times until the pH value of the water washing liquid is neutral, drying the obtained filter cake at 80 ℃ for 10h under vacuum condition, washing the powder with n-hexane, filtering and collecting the filter cake, and drying at 120 ℃ for 10h under vacuum condition to obtain an intermediate 4; subsequently, 0.45g of intermediate 4 was dissolved in 27ml of DMF, and then 1.43g of Na was added to the reaction system under stirring2S*9H2O, and then 7.6mL of glacial acetic acid is dripped into the reaction system (the dripping time is 5 min); after the glacial acetic acid is added dropwise, the reaction is continued for 12H at room temperature, then the reaction solution is added into 200mL of deionized water for precipitation, the obtained precipitate is filtered and a filter cake is collected, the filter cake is washed by the deionized water to be neutral, the filter cake is collected, and the monomer (1- (4-aminophenyl) -1H-imidazole-4, 5-dinitrile) is obtained after vacuum drying at 80 ℃ for 12H, and the structural formula is as follows:
(2) placing (1- (4-aminophenyl) -1H-imidazole-4, 5-dinitrile) in a nitrogen atmosphere, and carrying out curing operation according to the following temperature gradients: keeping the temperature at 180 ℃ for 1h, keeping the temperature at 230 ℃ for 1h, keeping the temperature at 300 ℃ for 1h, keeping the temperature at 350 ℃ for 0.5h, and cooling to room temperature along with the furnace after curing is finished to obtain the thermosetting resin.
Thermogravimetric analysis of the thermosetting resin obtained after curing was carried out under nitrogen atmosphere, and the temperature at 5% weight loss (T5%) was about 555 ℃ and the residual carbon rate at 800 ℃ was 73%.
Example 8
The preparation method is implemented by taking imidazole dinitrile monomolecular resin (1,1' - (propane-1, 3-diyl) bis (1H-imidazole-4, 5-dinitrile)) and curing agent m-APB as raw materials according to the following steps:
(1) 10g of 1,1' - (propane-1, 3-diyl) bis (1H-imidazole-4, 5-dinitrile) and 1.0g m-APB were dissolved in 300mL of acetone and mixed uniformly, and the resulting mixture was spin-dried and ground to obtain a blended powder.
(2) And (3) curing the obtained blended powder in a nitrogen atmosphere according to the following temperature gradients in sequence: keeping the temperature at 150 ℃ for 1h, keeping the temperature at 200 ℃ for 1h, keeping the temperature at 240 ℃ for 1h, keeping the temperature at 290 ℃ for 0.5h, and cooling to room temperature along with the furnace after curing is finished to obtain the thermosetting resin.
1,1' - (propane-1, 3-diyl) bis (1H-imidazole-4, 5-dinitrile) preparation is described in Pinter P, Biffins A, Tubaro C, et al Palladium (II) complexes with electron-pore, 4, 5-disubstitated diimidazol-2-ylidine ligands: synthesis, characterization and catalytic activity [ J ] Dalton Transactions,2015,44(20): 9391-:
thermogravimetric analysis of the thermosetting resin obtained after curing was carried out under a nitrogen atmosphere, and the temperature at 5% weight loss (T5%) was about 450 ℃ and the residual carbon rate at 800 ℃ was 61%.
Claims (6)
1. A thermosetting resin based on an imidazole dinitrile reactive group, characterized in that the resin is formed by heat-curing an imidazole dinitrile-containing compound of the following structural formula (VII) with an imidazole dinitrile group as the reactive group;
or the imidazole dinitrile-containing compound is formed by heating and curing a blend of any one of the following structural formulas (I) to (VII) and a curing agent by taking an imidazole dinitrile group as a reactive group, wherein the mass ratio of the imidazole dinitrile-containing compound to the curing agent is 10: (0.7-1.0), wherein the curing agent is Lewis acid/Lewis base or a compound containing methylene/methine curing groups;
wherein the content of the first and second substances,
2. the thermosetting resin based on imidazole dinitrile-reactive groups according to claim 1, characterized in that the lewis acid/lewis base is an aromatic amino compound, phenolic hydroxyl compound or metal salt having a curing function and the compound containing methylene/methine curing groups is 2,2' - (oxybis (4, 1-phenylene)) bis (3a, 4,7,7 a-tetrahydro-1H-isoindole-1, 3(2H) -dione).
3. A method for preparing thermosetting resin based on imidazole dinitrile reactive group is characterized in that under nitrogen atmosphere, imidazole dinitrile group is taken as reactive group, and a compound containing imidazole dinitrile is cured according to the following temperature and time in sequence:
keeping the temperature for 0-10 hours at the temperature T of more than or equal to 150 and less than or equal to 190 ℃,
keeping the temperature for 0-10 hours at the temperature of T more than or equal to 200 and less than or equal to 210 ℃,
keeping the temperature for 0-10 hours at the temperature of more than or equal to 230 and less than or equal to 250 ℃,
t is more than or equal to 290 and less than or equal to 300 ℃, the temperature is kept for 0.5 to 10 hours,
the temperature T is not less than 150 and not more than 190 ℃, the temperature T is not less than 200 and not more than 210 ℃, and the heat preservation time is not more than 230 and not more than 250 ℃ is not 0 at the same time;
or curing the compound containing the imidazole dinitrile at the following temperature and time in sequence:
keeping the temperature for 0-10 hours at the temperature T of more than or equal to 150 and less than or equal to 190 ℃,
keeping the temperature for 0-10 hours at the temperature of T more than or equal to 200 and less than or equal to 210 ℃,
keeping the temperature for 0-10 hours at the temperature of more than or equal to 230 and less than or equal to 250 ℃,
t is more than or equal to 290 and less than or equal to 300 ℃, the temperature is kept for 0-10 h,
keeping the temperature of T more than or equal to 350 and less than or equal to 380 ℃ for 0.5-10 h;
the temperature T is not less than 150 and not more than 190 ℃, the temperature T is not less than 200 and not more than 210 ℃, and the heat preservation time is not more than 230 and not more than 250 ℃ is not 0 at the same time;
after the solidification is finished, cooling the obtained product to room temperature along with the furnace;
the compound containing an imidazole dinitrile is represented by the structural formula (VII) in claim 1.
4. A process for the preparation of thermosetting resins based on imidazole dinitrile reactive groups, characterized in that it comprises the following steps:
(1) taking an imidazole dinitrile group as a reactive group, and mixing a compound containing imidazole dinitrile and a curing agent according to the mass ratio of 10: (0.7-1.0) blending, and uniformly blending a compound containing imidazole dinitrile and a curing agent to obtain a blend;
(2) the resulting blend was cured under nitrogen atmosphere at the following temperatures and times in order:
keeping the temperature for 0-10 hours at the temperature T of more than or equal to 150 and less than or equal to 190 ℃,
keeping the temperature for 0-10 hours at the temperature of T more than or equal to 200 and less than or equal to 210 ℃,
keeping the temperature for 0-10 hours at the temperature of more than or equal to 230 and less than or equal to 250 ℃,
t is more than or equal to 290 and less than or equal to 300 ℃, the temperature is kept for 0.5 to 10 hours,
the temperature T is not less than 150 and not more than 190 ℃, the temperature T is not less than 200 and not more than 210 ℃, and the heat preservation time is not more than 230 and not more than 250 ℃ is not 0 at the same time;
or the obtained blend is cured according to the following temperature and time in sequence:
keeping the temperature for 0-10 hours at the temperature T of more than or equal to 150 and less than or equal to 190 ℃,
keeping the temperature for 0-10 hours at the temperature of T more than or equal to 200 and less than or equal to 210 ℃,
keeping the temperature for 0-10 hours at the temperature of more than or equal to 230 and less than or equal to 250 ℃,
t is more than or equal to 290 and less than or equal to 300 ℃, the temperature is kept for 0-10 h,
keeping the temperature of T more than or equal to 350 and less than or equal to 380 ℃ for 0.5-10 h;
the temperature T is not less than 150 and not more than 190 ℃, the temperature T is not less than 200 and not more than 210 ℃, and the heat preservation time is not more than 230 and not more than 250 ℃ is not 0 at the same time;
after the solidification is finished, cooling the obtained product to room temperature along with the furnace;
the imidazole dinitrile-containing compound is any one of structural formulae (I) to (VII) according to claim 1; the curing agent is a lewis acid/lewis base or a compound containing methylene/methine curing groups.
5. The method for preparing thermosetting resin based on imidazole dinitrile-reactive group according to claim 4, wherein in step (1), the imidazole dinitrile-containing compound and the curing agent are blended in such a manner that: dissolving a compound containing imidazole dinitrile and a curing agent in a solvent for mixing, and then spin-drying the obtained mixed solution; the solvent is tetrahydrofuran or acetone.
6. The method for preparing thermosetting resin based on imidazole dinitrile-reactive group according to claim 4, wherein in step (1), the imidazole dinitrile-containing compound and the curing agent are blended in such a manner that: the imidazole dinitrile-containing compound and the curing agent are mixed by grinding.
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