Use of sydnones for catalytic preparation of phthalonitrile resin prepolymers

Abstract

The present application relates to a kind of preparation of phthalonitrile resin prepolymer catalyzed by sydnones. Specifically, the present application relates to a kind of preparation of modified phthalonitrile resin prepolymer using sydnones as catalyst. Compared with conventional phenolic, amine catalytic system, the curing temperature of prepolymer prepared using sydnones as catalyst is significantly lower, and the thermal performance of the final cured product is comparable to or even better than that of the conventional cured product.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic synthesis high polymer materials, and particularly relates to a use of sydnone in catalytic preparation of phthalonitrile resin prepolymer. BACKGROUND

[0002] High-temperature resistant thermosetting resin is a kind of resin with special functions. Due to the differences in main chain structure, curing mechanism, product structure, etc., the temperature resistance performance is quite different, and the final application temperature is also different. Because the processing technology is usually high, the curing temperature is relatively high, and the application environment is complex, the resin in the field of high-tech such as aerospace puts forward new requirements of "low-temperature curing and high-temperature use".

[0003] Phthalonitrile resin is a kind of thermosetting resin known for its excellent temperature resistance. Its products have excellent thermal performance, good flame retardant performance, high glass transition temperature, low water absorption and good corrosion resistance. However, in order to achieve the best performance of phthalonitrile resin, the use of conventional amine or phenolic catalyst usually requires a high-temperature post-processing process for its cured product, and the post-curing temperature is even higher than 400 DEG C. The process is complex and the energy consumption is high, which has many limitations for expanding production and application. Metal catalysts can reduce the curing temperature to a certain extent, but their dispersibility is poor, and the introduction of metal ions significantly reduces the thermal oxidation performance of the resin.

[0004] Therefore, the conventional curing method of phthalonitrile resin cannot meet the current application requirements. It is urgent to develop a phthalonitrile resin prepolymer with low curing temperature and good thermal performance in the field. SUMMARY

[0005] An object of the present application is to provide a phthalonitrile resin prepolymer with low curing temperature and excellent thermal performance.

[0006] In the first aspect of the present application, the use of sydnone as a catalyst for preparing modified phthalonitrile resin prepolymer is provided, which is used in the following reaction:

[0007] Under the protection of inert gas, the phthalonitrile resin monomer reacts in the presence of sydnone catalyst in an organic polar solvent to obtain the modified phthalonitrile resin prepolymer.

[0008] In another preferred embodiment, the mass ratio of the phthalonitrile resin monomer and the sydnone catalyst is 100:(1-10).

[0009] In another preferred embodiment, the mass ratio of the phthalonitrile resin monomer and the sydnone catalyst is 100:(1-5); preferably 100:(1-3).

[0010] In another preferred embodiment, the sydnones catalyst is selected from the group consisting of: or a combination thereof.

[0011] In another preferred embodiment, the sydnones is 3,3'-(1,4-phenyl) bis-sydnones.

[0012] In another preferred embodiment, the reaction temperature is 130-250°C; preferably 150-210°C; more preferably 190-210°C.

[0013] In another preferred embodiment, the reaction time is 1-6h; preferably 1-4h; more preferably 1.5-3h.

[0014] In another preferred embodiment, the phthalonitrile resin monomer is selected from the group consisting of:

[0015]

[0016] Preferably, the phthalonitrile resin monomer is selected from the group consisting of: biphenyl type phthalonitrile resin, benzophenone type phthalonitrile resin, bisphenol A type phthalonitrile resin, bisphenol AF type phthalonitrile resin, bisphenol F type phthalonitrile resin, bisphenol S type phthalonitrile resin, or a combination thereof.

[0017] In another preferred embodiment, the method comprises the following steps:

[0018] Under inert gas protection, the phthalonitrile resin monomer and sydnones are dissolved in the organic polar solvent with a mass ratio of 100:(1-10) and reacted at 130-250°C for 1-6h to obtain the modified phthalonitrile resin prepolymer.

[0019] In another preferred embodiment, the reaction is accompanied by stirring.

[0020] In another preferred embodiment, the method further comprises: after the reaction is completed, cooling to room temperature, adding a precipitant to the reaction solution, and precipitating the solid, which is the modified phthalonitrile resin prepolymer.

[0021] In another preferred embodiment, the precipitant is water, C1-C6 alcohol solvent, or a combination thereof; preferably one or more of water, methanol, and ethanol.

[0022] In another preferred embodiment, the method further comprises post-treatment: filtration, washing, and drying.

[0023] In another preferred embodiment, the washing refers to washing with water and / or ethanol.

[0024] In another preferred embodiment, the washing is performed multiple times (e.g., 2, 3, or 4 times).

[0025] In another preferred embodiment, the organic polar solvent is selected from the group consisting of N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, diphenyl ether, or a combination thereof; preferably N-methylpyrrolidone, diphenyl ether, or a combination thereof.

[0026] In another preferred embodiment, the mass ratio of the phthalonitrile resin monomer to the organic polar solvent is 5:8.

[0027] In a second aspect of the present application, a method for preparing a modified phthalonitrile resin prepolymer is provided, comprising the following steps:

[0028] In the presence of a catalyst, the phthalonitrile resin monomer is reacted in an organic polar solvent under inert gas protection to obtain the modified phthalonitrile resin prepolymer.

[0029] In another preferred embodiment, the reaction further comprises: after the reaction is completed, cooling to room temperature (15-35°C), adding a precipitant to the reaction solution to precipitate the solid, which is the modified phthalonitrile resin prepolymer.

[0030] In a third aspect of the present application, a modified phthalonitrile resin cured product is provided, which is cured from the modified phthalonitrile resin prepolymer.

[0031] In another preferred embodiment, the curing is temperature gradient curing.

[0032] In another preferred embodiment, the temperature gradient curing is 200°C / 2h + 230°C / 2h + 250°C / 4h.

[0033] In another preferred embodiment, the temperature gradient curing is 200°C / 2h + 230°C / 2h + 250°C / 4h + 280°C / 4h.

[0034] In another preferred embodiment, the T d5 (under nitrogen) is 460-500°C.

[0035] In another preferred embodiment, the mass retention rate of the cured product at 1000°C (under nitrogen) is ≥66%; preferably ≥70%.

[0036] In a fourth aspect of the present application, an article is provided, which comprises the modified phthalonitrile resin cured product of the third aspect of the present application.

[0037] In another preferred embodiment, the modified phthalonitrile resin cured product accounts for ≥1% of the total product; preferably ≥10%, ≥20%, ≥30%, ≥40%, ≥50%, ≥60%, ≥70%, ≥80%, ≥90%, ≥95%, ≥99%.

[0038] It should be understood that, within the scope of the present application, each of the technical features described above and in the following (e.g., in the examples) can be combined with each other to form new or preferred technical solutions. Due to the limited space, they will not be listed one by one here. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The infrared spectrum of the biphenyl phthalonitrile resin prepolymer prepared in Example 3.

[0040] Figure 2 The DSC spectra of the biphenyl phthalonitrile resin prepolymer before and after the reaction in Example 3.

[0041] Figure 3 The reaction process of the phthalonitrile resin catalyzed by Sydney ketone.

[0042] Figure 4 The TGA curve of the bisphenol F phthalonitrile resin cured product prepared in Example 1.

[0043] Figure 5 The TGA curve of the bisphenol A phthalonitrile resin cured product prepared in Example 2.

[0044] Figure 6 The TGA curve of the biphenyl phthalonitrile resin cured product prepared in Example 3. DETAILED DESCRIPTION

[0045] The inventors have made extensive and in-depth studies and for the first time unexpectedly discovered a phthalonitrile resin prepolymer catalyzed by Sydney ketone as a catalyst. Compared with conventional phenolic and amine catalytic systems, Sydney ketone as a catalyst can significantly reduce the curing temperature and obtain comparable or even better thermal properties. Based on this, the inventors completed the present application.

[0046] Sydney ketone

[0047] Sydney ketone is a mesoionic compound with 1,3-dipole properties, which can undergo dipole cycloaddition reactions with unsaturated compounds such as alkenes and alkynes. Sydney ketone compound is a five-membered heterocyclic compound composed of O(1)-N(2)-N(3)C(4)-C(5), which belongs to non-benzene aromatic compounds. The charge distribution of each atom on the ring is quite special, which cannot be represented by a single covalent structure, making its reaction unique.

[0048] Specifically, the present application provides a Sydney ketone catalyst having the structure shown below:

[0049]

[0050] As Figure 3 shown, through the electron-withdrawing ability of the N atom at the 3 position of Sydney ketone, the catalytic reaction forms a C cation, further triggering the nucleophilic substitution of the cyanide curing reaction, greatly reducing the curing temperature and process energy consumption of phthalonitrile resin.

[0051] Phthalonitrile resin

[0052] Phthalonitrile resin (PN resin) is a kind of thermosetting resin with high temperature resistance and other excellent comprehensive performance. The polymer of the resin has excellent structural stability, high temperature resistance, flame retardance, moisture resistance, and less smoke and toxic gas, and has excellent mechanical properties.

[0053] It has wide application demand in harsh environment such as national defense and military industry. In addition, it can also be used for high performance resin matrix, insulating material, electronic packaging material, high temperature resistant adhesive, high temperature resistant coating, laminated material, etc.

[0054] The Sydney ketone catalyst of the present application can catalyze the pre-polymerized phthalonitrile resin monomer having the following structure:

[0055]

[0056] Further, the phthalonitrile resin monomer used includes one or more of biphenyl type phthalonitrile resin, nitrile ether type phthalonitrile resin, bisphenol A type phthalonitrile resin, bisphenol AF type phthalonitrile resin, bisphenol F type phthalonitrile resin, and bisphenol S type phthalonitrile resin.

[0057] Method for preparing phthalonitrile resin prepolymer

[0058] The cured product prepared by the conventional catalytic method of phthalonitrile resin usually needs to be post-treated at high temperature to achieve the ideal performance, and the temperature needs to reach 400℃ or even higher.

[0059] The present application unexpectedly found that Sydney ketone can be used as a catalyst to participate in the preparation of modified phthalonitrile resin prepolymer by phthalonitrile resin pre-polymerization reaction. As Figure 3As shown, the electron-withdrawing ability of the nitrogen atom at the 3-position of sydney ketone catalyzes the reaction to form a C cation, which further triggers a nucleophilic substituted cyano curing reaction. This significantly reduces the curing temperature and process energy consumption of the phthalonitrile resin, eliminates the need for long-term high-temperature post-treatment, and makes the prepolymer suitable for a variety of molding processes. It can be seen that using sydney ketone as a catalyst for prepolymerization of phthalonitrile resin can significantly reduce the prepolymerization temperature, and the cured product obtained after the prepolymer is cured has excellent thermal properties.

[0060] Specifically, the present invention provides a method for preparing a phthalonitrile resin prepolymer by using a Sydney ketone catalyst in a prepolymerization reaction of a phthalonitrile resin monomer. The method comprises the following steps:

[0061] The phthalonitrile resin monomer and the Sydney ketone catalyst are dissolved in an organic polar solvent in a mass ratio of 100:(1-10), and reacted at 130°C to 250°C for 1-6 hours under the protection of an inert gas. After the reaction is completed, the reaction solution is cooled to room temperature, and the reaction solution is added to a precipitant to precipitate the product, thereby obtaining a Sydney ketone-catalyzed phthalonitrile resin prepolymer.

[0062] In the present invention, the reaction time is not particularly limited and can be any time from 1 to 6 hours for the reaction to occur; for example, 2, 3, 4, 5, 6, etc.

[0063] In the present invention, the post-treatment of the reaction is a conventional post-treatment step, including: collecting the solid by filtration, (multiple) washing, (vacuum) drying, etc.

[0064] In the present invention, the term "organic polar solvent" refers to a solvent having polar bonds within its molecules, resulting in polar molecules having electrical polarity. Suitable organic polar solvents for use in the present invention include amide solvents and pyrrolidone solvents, such as N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, diphenyl ether, or combinations thereof.

[0065] In the present invention, the precipitant refers to a liquid that precipitates the prepolymer from the solution, for example, water or an alcohol solvent.

[0066] In the present invention, the inert gas used is a common inert gas in the art, such as nitrogen, argon, etc.

[0067] Phthalonitrile resin cured product

[0068] The present invention also provides a modified phthalonitrile resin cured product, which is obtained by curing the phthalonitrile resin prepolymer.

[0069] Specifically, the curing is temperature gradient curing.

[0070] In a preferred embodiment, the temperature gradient curing is 200℃ / 2h+230℃ / 2h+250℃ / 4h.

[0071] In a preferred embodiment, the temperature gradient curing is 200℃ / 2h+230℃ / 2h+250℃ / 4h+280℃ / 4h.

[0072] The T d5 (under nitrogen) is 460-500℃.

[0073] The mass retention rate (under nitrogen) of the cured product at 1000℃ is ≥66%; preferably ≥70%.

[0074] The present application also provides an article comprising the above-mentioned phthalonitrile resin cured product, wherein the proportion of the modified phthalonitrile resin cured product is ≥1%; preferably ≥10%, ≥20%, ≥30%, ≥40%, ≥50%, ≥60%, ≥70%, ≥80%, ≥90%, ≥95%, ≥99%. The article is resistant to high temperature and is suitable for high-precision fields such as aerospace and electronics.

[0075] Compared with the prior art, the main advantages of the present application include:

[0076] (1) The present application first proposes to use Sydney ketone as a catalyst to prepare a phthalonitrile resin prepolymer.

[0077] (2) Using Sydney ketone as a catalyst can cure the phthalonitrile resin prepolymer at a low temperature, and the thermal performance of the cured product is comparable to, or even better than, that of the cured product obtained under a conventional phenolic or amine catalytic system.

[0078] (3) The present application provides a method for preparing a phthalonitrile resin prepolymer using Sydney ketone as a catalyst. Compared with the conventional phthalonitrile resin catalytic system, which requires a post-treatment temperature of above 400℃, the prepolymer of the present application can be cured and formed at a lower temperature by using the electron-withdrawing ability of the N atom at position 3 of Sydney ketone to catalyze the reaction to form a C cation, which further initiates a nucleophilic substitution cyanide curing reaction. This method eliminates the high-temperature long-time post-treatment process, greatly reduces the curing temperature and energy consumption, and is suitable for various molding processes, has good processing performance, and is conducive to the preparation of various high-performance composites.

[0079] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. The experimental methods in the following examples are not specified, and are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise specified, percentages and parts are calculated by weight.

[0080] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Methods and materials similar or equivalent to those described herein can be used in the practice of the present application. The preferred materials and methods are described herein.

[0081] Example 1

[0082] (1) 5 g of bisphenol F type phthalonitrile monomer, 0.15 g of 3,3'-(1,4-phenyl) bisindanone, and 8 g of N-methyl pyrrolidone were added to a dry four-necked flask, and the temperature was raised to 200°C under nitrogen atmosphere, and the reaction was carried out for 2.5 hours under high-speed stirring. After the completion of the reaction, the temperature was lowered to room temperature.

[0083] (2) The product solution obtained in step (1) was poured into 200 ml of H2O, and a large amount of dark brown precipitate was formed. The filtrate was washed with deionized water and an ethanol solution several times, and vacuum drying was carried out to obtain a black solid, which was a low-temperature curing modified phthalonitrile resin prepolymer.

[0084] (3) The prepolymer of step (2) was ground, and a small amount of powder was placed in a ceramic crucible.

[0085] (4) The sample prepared in step (3) was cured in a muffle furnace according to the conditions of 200°C / 2h + 230°C / 2h + 250°C / 4h + 280°C / 4h, and after the muffle furnace was cooled to room temperature, a cured product of the low-temperature curing modified phthalonitrile resin was obtained.

[0086] Example 2

[0087] (1) 5 g of bisphenol A type phthalonitrile monomer, 0.05 g of 3,3'-(4,4'-diphenyl ether) bisindanone, and 8 g of N-methyl pyrrolidone were added to a dry four-necked flask, and the temperature was raised to 200°C under nitrogen atmosphere, and the reaction was carried out for 3 hours under high-speed stirring. After the completion of the reaction, the temperature was lowered to room temperature.

[0088] (2) The product solution obtained in step (1) was poured into 200 ml of H2O, and a large amount of brown precipitate was formed. The filtrate was washed with deionized water and an ethanol solution several times, and vacuum drying was carried out to obtain a black solid, which was a low-temperature curing modified phthalonitrile resin prepolymer.

[0089] (3) The prepolymer of step (2) was ground, and a small amount of powder was placed in a ceramic crucible.

[0090] (4) The sample prepared in step (3) was cured in a muffle furnace according to the conditions of 200°C / 2h + 230°C / 2h + 250°C / 4h, and after the muffle furnace was cooled to room temperature, a cured product of the low-temperature curing modified phthalonitrile resin was obtained.

[0091] Example 3

[0092] (1) 5 g of a biphenyl type phthalonitrile monomer, 0.1 g of 3,3'-(1,4-phenyl) bisindanone, and 8 g of diphenyl ether were added to a dry four-necked flask, and the temperature was raised to 210°C under nitrogen protection, and the reaction was performed for 1.5 h under high-speed stirring. After the reaction was completed, the temperature was cooled to room temperature.

[0093] (2) The product solution obtained in step (1) was poured into 200 ml of methanol, and a large amount of black precipitate was generated. The filter residue was washed with deionized water and an ethanol solution several times, and vacuum drying was performed to obtain a black solid, which was a low-temperature curing modified phthalonitrile resin prepolymer.

[0094] (3) After the prepolymer of step (2) was ground, a small amount of powder was placed in a ceramic crucible.

[0095] (4) The sample prepared in step (3) was cured in a muffle furnace under the conditions of 200°C / 2h + 230°C / 2h + 250°C / 4h + 280°C / 4h, and the cured product of the low-temperature curing modified phthalonitrile resin was obtained after the muffle furnace was cooled to room temperature.

[0096] Comparative Example 1

[0097] (1) 100 g of a bisphenol A type phthalonitrile resin was added to a 200 mL beaker, and the beaker was placed in an oil bath to raise the temperature to 200°C until the monomers were completely melted. Then, it was placed in a 200°C vacuum oven and vacuumized for 30 min.

[0098] (2) 28 g of bisphenol A was added to the resin of step (1), and after rapid stirring for 5 min, it was slowly poured into a preheated mold, and curing treatment was performed in an oven under the curing conditions of 200°C / 10h + 240°C / 10h.

[0099] Comparative Example 2

[0100] (1) 100 g of a bisphenol A type phthalonitrile resin was added to a 200 mL beaker, and the beaker was placed in an oil bath to raise the temperature to 200°C until the monomers were completely melted. Then, it was placed in a 200°C vacuum oven and vacuumized for 30 min.

[0101] (2) 3 g of 4,4'-bis(3-aminophenoxy)diphenyl sulfone (m-BAPS) was added to the resin of step (1), and after rapid stirring for 5 min, it was slowly poured into a preheated mold, and curing treatment was performed in an oven under the curing conditions of 250°C / 4h + 275°C / 4h + 300°C / 4h + 325°C / 4h.

[0102] Comparative Example 3

[0103] (1) In a 200 mL beaker, 100 g of bisphenol F type phthalonitrile resin was added, and the beaker was placed in an oil bath to heat to 160°C until the monomer was completely melted, and then it was placed in a 160°C vacuum oven and vacuumed for 30 min.

[0104] (2) 3 g of 4,4'-bis(3-aminophenoxy)diphenyl sulfone (m-BAPS) was added to the resin of step (1), and after rapid stirring for 5 min, it was slowly poured into a preheated mold, and cured in an oven with a curing schedule of 250°C / 4h + 275°C / 4h + 300°C / 4h + 325°C / 4h.

[0105] The above cured product was tested in a nitrogen atmosphere at a heating rate of 10°C / min to obtain the thermal decomposition temperature (T d5 ) at which 5% mass loss and the 1000°C mass retention rate, respectively, as shown in the following table. Compared with conventional phenolic and amine catalytic systems, the curing temperature of the prepolymer obtained by using the new Sydney ketone agent as a catalyst has obvious advantages, and the catalytic system can complete curing at a lower curing temperature and obtain equivalent thermal performance.

[0106]

[0107] All documents mentioned in the present application are incorporated herein by reference as if each document were individually incorporated by reference. In addition, it should be understood that various modifications and / or changes can be made to the present application by those skilled in the art, and such equivalent forms are intended to fall within the scope of the appended claims.

Claims

1. A method for preparing a modified phthalonitrile resin prepolymer by using Sydney ketone as a catalyst, characterized in that: Used in the following reactions: Under the protection of inert gas and in the presence of Sydney ketone catalyst, the phthalonitrile resin monomer reacts in an organic polar solvent to obtain the modified phthalonitrile resin prepolymer; Wherein, the Sydney ketone catalyst is selected from the following group: R： or a combination thereof.

2. The use according to claim 1, characterized in that The mass ratio of the phthalonitrile resin monomer to the Sydney ketone catalyst is 100:(1-10).

3. The use according to claim 1, characterized in that The reaction temperature is 130°C to 250°C.

4. The use according to claim 1, wherein The reaction temperature is 150-210°C.

5. The use according to claim 1, characterized in that The reaction temperature is 190-210°C.

6. The use according to claim 1, wherein The phthalonitrile resin monomer is selected from the following group: R： 7. The use according to claim 1, characterized in that The method comprises the following steps: Under the protection of inert gas, phthalonitrile resin monomer and Sydney ketone are dissolved in an organic polar solvent in a mass ratio of 100:(1-10), and reacted at 130° C. to 250° C. for 1-6 hours to obtain the modified phthalonitrile resin prepolymer.

8. The use according to claim 1, characterized in that The organic polar solvent is selected from the group consisting of N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, diphenyl ether, or a combination thereof.

9. The use according to claim 1, characterized in that The organic polar solvent is N-methylpyrrolidone, diphenyl ether, or a combination thereof.

10. A method for preparing a modified phthalonitrile resin prepolymer, characterized in that: The steps include: Under the protection of inert gas and in the presence of Sydney ketone catalyst, the phthalonitrile resin monomer reacts in an organic polar solvent to obtain the modified phthalonitrile resin prepolymer; Wherein, the Sydney ketone catalyst is selected from the following group: R： or a combination thereof.

11. The preparation method according to claim 10, characterized in that The reaction further comprises: after the reaction is completed, cooling to room temperature, adding a precipitant to the reaction solution to precipitate a solid, which is a modified phthalonitrile resin prepolymer.

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