Application of sydnone in catalytic preparation of phthalonitrile resin prepolymer

Abstract

The invention relates to an application of sydnone in catalytic preparation of a phthalonitrile resin prepolymer. Specifically, the invention relates to application of sydnone as a catalyst to preparation of a modified phthalonitrile resin prepolymer. Compared with the conventional phenol and amine catalytic systems, the curing temperature of the prepolymer prepared by using sydnone as the catalyst is obviously lower, and the thermal performance of the finally obtained cured product is equivalent to or even better than that of the conventionally obtained cured product.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthetic polymer materials, and in particular, relates to a use of Sydney ketone to catalyze the preparation of phthalonitrile resin prepolymers. Background Art

[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 heat resistance is quite different, and the final applicable working temperature is also different. Because the processing technology is usually high, the curing temperature is relatively high, and the application environment is relatively complex, the high-tech fields such as aerospace put forward new requirements for resins to "cure at low temperature and use at high temperature".

[0003] Phthalonitrile resin is a thermosetting resin known for its excellent temperature resistance. Its products have excellent thermal properties, good flame retardancy, 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 phenol catalysts usually requires a high-temperature post-treatment process for its cured product. The post-curing temperature even exceeds 400°C. The process is complex and the energy consumption is high, which has many limitations on the expansion of production and application. Metal catalysts can reduce the curing temperature to a certain extent, but their dispersibility is very poor. The introduction of metal ions leads to a significant decrease in the thermal oxidation performance of the resin.

[0004] It can be seen that conventional phthalonitrile resin curing methods are difficult to meet current application requirements. There is an urgent need to develop a phthalonitrile resin prepolymer with low curing temperature and good thermal properties. Summary of the invention

[0005] An object of the present invention is to provide a phthalonitrile resin prepolymer having a low curing temperature and excellent thermal properties.

[0006] In the first aspect of the present invention, there is provided a use of Sydney ketone as a catalyst for preparing a modified phthalonitrile resin prepolymer for the following reaction:

[0007] Under the protection of inert gas and in the presence of Sydney ketone catalyst, phthalonitrile resin monomers react 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 to the Sydney ketone catalyst is 100:(1-10).

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

[0010] In another preferred embodiment, the Sydney ketone catalyst is selected from the following group: or a combination thereof.

[0011] In another preferred embodiment, the Sydney ketone is 3,3'-(1,4-phenyl) di-Sydney ketone.

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

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

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

[0015]

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

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

[0018] Under the protection of inert gas, the 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.-250° C. for 1-6 hours to obtain the modified phthalonitrile resin prepolymer.

[0019] In another preferred embodiment, the reaction is carried out with 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 to precipitate a solid, which is a modified phthalonitrile resin prepolymer.

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

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

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

[0024] In another preferred embodiment, the number of washing is multiple times (eg, 2, 3, or 4 times).

[0025] In another preferred embodiment, the organic polar solvent is selected from the following group: 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 invention, there is provided a method for preparing a modified phthalonitrile resin prepolymer, comprising the following steps:

[0028] Under the protection of inert gas and in the presence of Sydney ketone catalyst, phthalonitrile resin monomers react in an organic polar solvent 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 a solid, which is a modified phthalonitrile resin prepolymer.

[0030] In a third aspect of the present invention, a modified phthalonitrile resin cured product is provided, wherein the cured product is obtained by curing a 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 (Nitrogen)℃ is 460-500℃.

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

[0036] In a fourth aspect of the present invention, a product is provided, wherein the product comprises the modified phthalonitrile resin cured product according to the third aspect of the present invention.

[0037] In another preferred embodiment, in the product, the proportion of the modified phthalonitrile resin cured product described in the third aspect of the present invention is ≥1%; preferably ≥10%, ≥20%, ≥30%, ≥40%, ≥50%, ≥60%, ≥70%, ≥80%, ≥90%, ≥95%, ≥99%.

[0038] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0040] Figure 2 This is the DSC spectrum of the biphenyl type phthalonitrile resin before and after prepolymerization in Example 3.

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

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

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

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

[0045] After extensive and in-depth research, the inventor unexpectedly discovered for the first time that Sydney ketone can be used as a catalyst to prepare phthalonitrile resin prepolymer. Compared with conventional phenolic and amine catalytic systems, Sydney ketone can significantly reduce the curing temperature as a catalyst and obtain comparable or even better thermal properties. Based on this, the inventor completed the present invention.

[0046] Sydney Ketone

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

[0048] Specifically, the Sydney ketone catalyst provided by the present invention has the structure shown below:

[0049]

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

[0051] Phthalonitrile resin

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

[0053] It has a wide range of application needs in the fields of national defense, military industry and other harsh use environments. In addition, it can also be used in high-performance resin matrix, insulation materials, electronic packaging materials, high-temperature resistant adhesives, high-temperature resistant coatings, laminated materials, etc.

[0054] The Sydney ketone catalyst of the present invention can catalyze the prepolymerization of phthalonitrile resin monomers having the following structure:

[0055]

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

[0057] Preparation method of phthalonitrile resin prepolymer

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

[0059] The present invention unexpectedly found that Sydney ketone can be used as a catalyst to participate in the prepolymerization reaction of phthalonitrile resin to prepare modified phthalonitrile resin prepolymer. Figure 3As shown, the electron-withdrawing ability of the N atom at the 3-position of Sydney ketone catalyzes the reaction to form C positive ions, which further triggers the nucleophilic substitution cyano curing reaction, greatly reducing the curing temperature and process energy consumption of the phthalonitrile resin, eliminating the long-term high-temperature post-treatment step, and the prepolymer is suitable for a variety of molding processes. It can be seen that using Sydney ketone as a catalyst to prepolymerize 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 to participate in a prepolymerization reaction of a phthalonitrile resin monomer. Specifically, the method comprises the following steps:

[0061] The phthalonitrile resin monomer and Sydney ketone catalyst are dissolved in an organic polar solvent in a mass ratio of 100: (1-10), and reacted at 130°C-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 a product, thereby obtaining a prepolymer of the phthalonitrile resin catalyzed by Sydney ketone.

[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 solids by filtration, (multiple) washing, (vacuum) drying, etc.

[0064] In the present invention, the organic polar solvent refers to a solvent molecule having polar bonds, which is a polar molecule, so that these molecules have electrical polarity. Organic polar solvents suitable for the present invention include amide solvents, pyrrolidone solvents, etc.; for example: N, N-dimethylformamide, N-methylpyrrolidone, N, N-dimethylacetamide, diphenyl ether, or a combination 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 invention also provides a modified phthalonitrile resin cured product, wherein the cured product 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°C / 2h+230°C / 2h+250°C / 4h.

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

[0072] The T of the cured product d5 (Nitrogen)℃ is 460-500℃.

[0073] The mass retention rate (nitrogen) of the solidified material at 1000° C. is ≥66%; preferably ≥70%.

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

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

[0076] (1) For the first time, the use of Sydney ketone as a catalyst for the preparation of phthalonitrile resin prepolymer was proposed.

[0077] (2) Using Sydney ketone as a catalyst, phthalonitrile resin prepolymer can be cured at low temperature, and the thermal properties of its cured product are comparable to or even better than those obtained under conventional phenolic and amine catalytic systems.

[0078] (3) The present invention provides a method for preparing a phthalonitrile resin prepolymer by using syringone as a catalyst. Compared with the traditional phthalonitrile resin catalyst system which requires a post-processing temperature of more than 400°C, the prepolymer of the present invention uses the electron-withdrawing ability of the N atom at the 3-position of syringone to catalyze the reaction to form C positive ions, which further induces a nucleophilic substituted cyanide curing reaction. The prepolymer can be cured and formed under lower temperature conditions, eliminating the high-temperature and long-time post-processing process, greatly reducing 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 composite materials.

[0079] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

[0080] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only.

[0081] Example 1

[0082] (1) Add 5 g of bisphenol F-type phthalonitrile monomer, 0.15 g of 3,3'-(1,4-phenyl)dichlorophenone, and 8 g of N-methylpyrrolidone into a dry four-necked flask, heat to 200° C. under nitrogen protection, and react for 2.5 h under high-speed stirring. After the reaction is completed, cool 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 appeared. The precipitate was filtered off by suction, and the filter residue was washed with deionized water and ethanol solution for multiple times, and vacuum dried to obtain a black solid, i.e., a low-temperature curing modified phthalonitrile resin prepolymer.

[0084] (3) After grinding the prepolymer in step (2), a small amount of powder is placed in a ceramic crucible.

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

[0086] Example 2

[0087] (1) Add 5 g of bisphenol A type phthalonitrile monomer, 0.05 g of 3,3'-(4,4'-diphenyl ether) dioxygenone, and 8 g of N-methylpyrrolidone into a dry four-necked flask, heat to 200°C under nitrogen protection, and react for 3 h under high-speed stirring. After the reaction is completed, cool 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 appeared. The precipitate was filtered off by suction, and the filter residue was washed with deionized water and ethanol solution for multiple times, and vacuum dried to obtain a black solid, i.e., a low-temperature curing modified phthalonitrile resin prepolymer.

[0089] (3) After grinding the prepolymer in step (2), a small amount of powder is placed in a ceramic crucible.

[0090] (4) Curing the sample obtained in step (3) in a muffle furnace by stepwise heating at 200°C / 2h+230°C / 2h+250°C / 4h, and cooling the muffle furnace to room temperature to obtain a cured product of the low-temperature curing modified phthalonitrile resin.

[0091] Example 3

[0092] (1) Add 5 g of biphenyl-type phthalonitrile monomer, 0.1 g of 3,3'-(1,4-phenyl)dichlorophenone, and 8 g of diphenyl ether into a dry four-necked flask, heat to 210° C. under nitrogen protection, and react for 1.5 h under high-speed stirring. After the reaction is completed, cool 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 appeared. The product was filtered, and the filter residue was washed with deionized water and ethanol solution for multiple times. The product was vacuum dried to obtain a black solid, i.e., a low-temperature curing modified phthalonitrile resin prepolymer.

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

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

[0096] Comparative Example 1

[0097] (1) Add 100 g of bisphenol A phthalonitrile resin into a 200 mL beaker, place the beaker in an oil bath and heat to 200° C. until the monomer is completely melted, and then place the beaker in a vacuum oven at 200° C. for 30 min.

[0098] (2) Add 28 g of bisphenol A to the resin in step (1), stir rapidly for 5 min, then slowly pour into a preheated mold and cure in an oven at a curing rate of 200°C / 10 h+240°C / 10 h.

[0099] Comparative Example 2

[0100] (1) Add 100 g of bisphenol A phthalonitrile resin into a 200 mL beaker, place the beaker in an oil bath and heat to 200° C. until the monomer is completely melted, and then place the beaker in a vacuum oven at 200° C. for 30 min.

[0101] (2) Add 3 g of 4,4'-bis(3-aminophenoxy)diphenyl sulfone (m-BAPS) to the resin of step (1), stir rapidly for 5 min, then slowly pour into a preheated mold and cure in an oven at a curing rate of 250°C / 4h+275°C / 4h+300°C / 4h+325°C / 4h.

[0102] Comparative Example 3

[0103] (1) Add 100 g of bisphenol F phthalonitrile resin into a 200 mL beaker, place the beaker in an oil bath and heat to 160° C. until the monomer is completely melted, and place the beaker in a 160° C. vacuum oven for 30 min.

[0104] (2) Add 3 g of 4,4'-bis(3-aminophenoxy)diphenyl sulfone (m-BAPS) to the resin of step (1), stir rapidly for 5 min, then slowly pour into a preheated mold and cure in an oven at a curing rate of 250°C / 4h+275°C / 4h+300°C / 4h+325°C / 4h.

[0105] The above solidified material was tested in a nitrogen atmosphere at a heating rate of 10°C / min, and the thermal decomposition temperature (T d5 ) and 1000℃ mass retention rate are 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 is significantly superior. The catalytic system can complete the curing at a lower curing temperature and obtain comparable thermal properties.

[0106]

[0107] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a modified phthalonitrile resin prepolymer using Sydney ketone as a catalyst, characterized in that: Used for the following reactions: Under the protection of inert gas and in the presence of Sydney ketone catalyst, phthalonitrile resin monomers react in an organic polar solvent to obtain the modified phthalonitrile resin prepolymer.

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 Sydney ketone catalyst is selected from the following group: or a combination thereof.

4. The use according to claim 1, characterized in that The reaction temperature is 130°C to 250°C; preferably 150-210°C; more preferably 190-210°C.

5. The use according to claim 1, characterized in that The phthalonitrile resin monomer is selected from the following group: Preferably, the phthalonitrile resin monomer is selected from the following group: biphenyl phthalonitrile resin, benzophenone phthalonitrile resin, bisphenol A phthalonitrile resin, bisphenol AF phthalonitrile resin, bisphenol F phthalonitrile resin, bisphenol S phthalonitrile resin, or a combination thereof.

6. The use according to claim 1, characterized in that The method comprises the following steps: Under the protection of inert gas, the 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.-250° C. for 1-6 hours to obtain the modified phthalonitrile resin prepolymer.

7. The use according to claim 1, characterized in that The organic polar solvent is selected from the following group: N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, diphenyl ether, or a combination thereof; preferably N-methylpyrrolidone, diphenyl ether, or a combination thereof.

8. 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, phthalonitrile resin monomers react in an organic polar solvent to obtain the modified phthalonitrile resin prepolymer.

9. The preparation method according to claim 8, characterized in that: The reaction further comprises: after the reaction is completed, cooling to room temperature (15-35° C.), adding a precipitant to the reaction solution, and precipitating a solid, which is a modified phthalonitrile resin prepolymer.

10. A modified phthalonitrile resin cured product, characterized in that: The solidified material is obtained by solidifying a modified phthalonitrile resin prepolymer.

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