Spirofluorene diphthalonitrile monomer, polymer and preparation method

Abstract

The invention belongs to the technical field of polymer materials, and particularly relates to a spirofluorene diphthalonitrile monomer, a polymer and a preparation method. The spirofluorene diphthalonitrile monomer is prepared by taking spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diphenol spirocyclic bisphenol ether and 4-nitrophthalonitrile as raw materials. The spirofluorene diphthalonitrile monomer has a melting point of 142-146 DEG C. The obtained prepolymer has good solubility and low melting temperature. When the polymer of the spirofluorene diphthalonitrile monomer is prepared, the initial curing temperature is 220 DEG C, and the processing temperature window reaches 74-78 DEG C. The heating melting temperature of the prepolymer can be kept away from the curing starting temperature while maintaining good fluidity, which is more conducive to processing and shaping and uniform addition of carbon fiber and glass fiber. The mechanical properties of the obtained polymer are equivalent to those of the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and specifically relates to a spirofluorene bisphthalonitrile monomer, a polymer and a preparation method thereof. Background Art

[0002] Phthalonitrile resin has a stable curing process without the release of small molecules, a zero shrinkage rate of the cured product, and extremely high flame retardancy, excellent thermal stability and thermo-oxidative stability. In addition, it has a very high char yield and a flexible molecular structure designability. Therefore, it is called a polymer fireproof material.

[0003] Generally, the molten viscosity of a general biphenyl type (BPH) phthalonitrile monomer is very low, generally between 0.1 - 0.2 Pa·s. Its curing process is an addition polymerization reaction. Therefore, no small molecule by-products are generated during its polymerization process. The finally formed product is dense and defect-free, and its polymerization rate can be controlled by adjusting the dosage of its curing additive and the processing temperature. These characteristics make the processing and forming methods of composites based on BPH flexible and diverse.

[0004] However, due to the influence of the BPH monomer structure and reactivity, there are many difficulties in its processing process. The melting temperature of the monomer is high, and the melting temperature of the prepolymer obtained by heating and mixing the monomer with the curing agent is as high as 230 - 235 °C. The initial curing temperature of the phthalonitrile resin is 250 °C. Currently, the prepolymer in the molten state is injected into a molding die and heated for curing, which results in a narrow processing temperature window, only 15 - 20 °C. If the temperature is too high, it is easy to reach the curing temperature, and after the curing reaction occurs, the fluidity of the prepolymer decreases. If the temperature is too low, the viscosity of the prepolymer will increase, which is not conducive to casting. When manufacturing composites, it is difficult to uniformly add carbon fiber and glass fiber. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a spirofluorene bisphthalonitrile monomer, a polymer and a preparation method thereof, adding a spiral large side group in the molecular chain to make the melting temperature of the prepolymer lower and increase the processing temperature window.

[0006] Based on the above purpose, a spirofluorene bisphthalonitrile monomer provided by the present invention has the following molecular structure:

[0007]

[0008] A preparation method of a spirofluorene bisphthalonitrile monomer includes the following steps:

[0009] Mix spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diphenol spirobisphenol ether, 4-nitrophthalonitrile, an acid-binding agent, and an organic solvent; after the reaction is completed, perform post-treatment to obtain a spirofluorene bisphthalonitrile monomer.

[0010] Optionally, the molar ratio of spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diphenol spirobisphenol ether to 4-nitrophthalonitrile is 1:2 - 2.1, and the molar ratio of the acid-binding agent to 4-nitrophthalonitrile is 1.2 - 1.5:1.

[0011] Optionally, the organic solvent is an aprotic solvent, including N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, and dimethyl sulfoxide; the acid-binding agent is calcium carbonate, sodium carbonate, or potassium carbonate.

[0012] Optionally, the post-treatment method is washing and vacuum drying, and the conditions for vacuum drying are: temperature 80 ± 10°C; absolute vacuum degree below 1000 Pa.

[0013] A method for preparing a spirofluorene bisphthalonitrile polymer, comprising the following steps:

[0014] Prepolymer synthesis: Mix a curing agent with a spirofluorene bisphthalonitrile monomer, heat and melt to obtain a prepolymer;

[0015] Curing reaction: Cure the prepolymer to obtain a spirofluorene-based bisphthalonitrile polymer.

[0016] Optionally, the conditions for the curing reaction are: in an inert gas atmosphere, first cure at 220°C - 240°C for a period of time, then cure at 270°C for a period of time, and finally cure at 320°C for a period of time.

[0017] Optionally, the curing agent is a benzene derivative of the diamino type, including the following structural formula:

[0018]

[0019] Optionally, the mass ratio of the curing agent to the spirofluorene bisphthalonitrile monomer is 1.5 - 4:100.

[0020] A spirofluorene bisphthalonitrile polymer obtained by using the method for preparing a spirofluorene bisphthalonitrile polymer described above.

[0021] The beneficial effects of the present invention are as follows: The melting point of the prepolymer obtained by the reaction of the spiral fluorene bisphthalonitrile monomer provided by the present invention with the curing agent is 142°C - 146°C. The obtained prepolymer has a relatively low melting temperature. When preparing the polymer of the spiral fluorene bisphthalonitrile monomer of the present invention, the initial curing temperature is 220°C, so that the processing temperature window reaches 74 - 78°C. It can keep the heating and melting temperature of the prepolymer away from the initial curing temperature while maintaining good fluidity, which is more conducive to processing and shaping and uniformly adding carbon fiber and glass fiber. And the mechanical properties of the obtained polymer are comparable to those of the prior art. At the same time, the melting temperature of the prepolymer is reduced, and the initial curing temperature and post-curing temperature are also reduced by 10 - 30°C compared with the prior art, which is also beneficial to energy conservation.

[0022] The prepolymer has good solubility, which can broaden the application range of the material. It can be used for surface spraying and coatings under special working conditions. In addition, it can be dissolved in solvents to impregnate reinforcing materials such as glass fiber and carbon fiber, and then the solvent can be dried to obtain prepreg and then molded by compression. If the solubility is not good, only melting can be used to manufacture composite materials. Specific Embodiments

[0023] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0024] Example 1

[0025] A preparation method of a spiral fluorene bisphthalonitrile monomer, adding spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diphenol spirobisphenol ether, 4-nitrophthalonitrile, potassium carbonate and N,N-dimethylformamide into a reaction vessel, reacting at room temperature for 20 h. After the reaction is completed, it is washed with distilled water, filtered and dried in vacuum to obtain the spiral fluorene bisphthalonitrile monomer;

[0026] Among them, the molar ratio of spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diphenol spirobisphenol ether to 4-nitrophthalonitrile is 1:2, and the molar ratio of potassium carbonate to 4-nitrophthalonitrile is 1.2:1.

[0027] A preparation method of a spiral fluorene bisphthalonitrile polymer. First, prepolymer synthesis is carried out: heating and melting DDS and the spiral fluorene bisphthalonitrile monomer at a heating and melting temperature of 200°C for 3 minutes to obtain a prepolymer, and the melting temperature of the prepolymer is 145°C; then curing reaction is carried out: the prepolymer is placed in a nitrogen atmosphere, first cured at 220°C for 2 h, then at 270°C for 2 h, and finally at 320°C for 2 h to obtain a spiral fluorene-based bisphthalonitrile polymer;

[0028] Among them, the mass ratio of DDS to the spirofluorene bisphthalonitrile monomer is 1:50.

[0029] Example 2

[0030] The preparation method of the spirofluorene bisphthalonitrile monomer is the same as that in Example 1;

[0031] A preparation method of a spirofluorene bisphthalonitrile polymer, different from Example 1 in that the curing agent is DDS, the mass ratio of DDS to the spirofluorene bisphthalonitrile monomer is 1:25, and the melting temperature of the prepolymer is 142 °C, and the rest of the methods are the same.

[0032] Example 3

[0033] The preparation method of the spirofluorene bisphthalonitrile monomer is the same as that in Example 1;

[0034] A preparation method of a spirofluorene bisphthalonitrile polymer, different from Example 1 in that the curing agent is P-APB, the mass ratio of P-APB to the spirofluorene bisphthalonitrile monomer is 1:50, and the melting temperature of the prepolymer is 143 °C, and the rest of the methods are the same.

[0035] Example 4

[0036] The preparation method of the spirofluorene bisphthalonitrile monomer is the same as that in Example 1;

[0037] A preparation method of a spirofluorene bisphthalonitrile polymer, different from Example 1 in that the curing agent is m-APB, the mass ratio of m-APB to the spirofluorene bisphthalonitrile monomer is 1:50, and the melting temperature of the prepolymer is 145 °C, and the rest of the methods are the same.

[0038] Example 5

[0039] The preparation method of the spirofluorene bisphthalonitrile monomer is the same as that in Example 1;

[0040] A preparation method of a spirofluorene bisphthalonitrile polymer, different from Example 1 in that the curing agent is P-APBS, the mass ratio of P-APBS to the spirofluorene bisphthalonitrile monomer is 1:50, and the melting temperature of the prepolymer is 146 °C, and the rest of the methods are the same.

[0041] Example 6

[0042] The preparation method of the spirofluorene bisphthalonitrile monomer is the same as that in Example 1;

[0043] A preparation method of a spirofluorene bisphthalonitrile polymer, different from Example 1 in that the curing agent is m-APBS, the mass ratio of m-APBS to the spirofluorene bisphthalonitrile monomer is 1:50, and the melting temperature of the prepolymer is 144 °C, and the rest of the methods are the same.

[0044] The specific feed amounts of Examples 1-6 are shown in Table 1, and the melting points of the prepolymers and the mechanical properties of the resulting polymers are shown in Table 2.

[0045] Comparative Example 1

[0046] Preparation of BPH bisphthalonitrile monomer: Biphenol, 4-nitrophthalonitrile, potassium carbonate and N,N-dimethylformamide were added to a reaction vessel. The molar ratio of biphenol to 4-nitrophthalonitrile was 1:2, and the molar ratio of potassium carbonate to 4-nitrophthalonitrile was 1.2:1. The reaction was carried out at room temperature for 24 h. After the reaction, it was washed with distilled water and dried under vacuum to obtain the BPH bisphthalonitrile monomer, and its structural formula is:

[0047] Using BPH bisphthalonitrile monomer as the raw material, curing agent DDS was added, and it was heated and melted to 220 °C, stirred for 3 minutes and then cooled; then the curing reaction was carried out: the obtained prepolymer was in a nitrogen atmosphere, first at 230 °C for 2 h, then at 280 °C for 2 h, and finally at 350 °C for 2 h to prepare the corresponding polymer.

[0048] Comparative Example 2

[0049] Using spirofluorene bisphthalonitrile monomer and BPH bisphthalonitrile monomer as raw materials, curing agent DDS was added, heated to 220 °C and melted, stirred for 3 minutes and then cooled; then the curing reaction was carried out: the obtained prepolymer was in a nitrogen atmosphere, first at 230 °C for 2 h, then at 280 °C for 2 h, and finally at 350 °C for 2 h to prepare the corresponding polymer.

[0050] The specific feed amounts of Comparative Example 1 and Comparative Example 2 are shown in Table 1, and the melting points of the prepolymers and the mechanical properties of the resulting polymers are shown in Table 2.

[0051] Table 1: Formulation table of comparative examples and examples

[0052]

[0053] Table 2: Performance table of comparative examples and examples

[0054]

[0055] Note: The qualitative solubility test method is as follows: 10 mg of the material in 1 mL of tetrahydrofuran for 24 h: + means dissolved at room temperature; - means incompletely dissolved.

[0056] The melting point of the spirofluorene bisphthalonitrile monomer obtained in Examples 1-6 was 195 °C.

[0057] From Table 1 and Table 2, it can be seen that the melting point of the prepolymer obtained by the reaction of the spirofluorene bisphthalonitrile monomer provided by the present invention with the curing agent is 142°C - 146°C. The obtained prepolymer has a relatively low melting temperature. When preparing the polymer of the spirofluorene bisphthalonitrile monomer of the present invention, the initial curing temperature is 220°C, so that the processing temperature window reaches 74 - 78°C. This can keep the heating and melting temperature of the prepolymer away from the initial curing temperature while maintaining good fluidity, which is more conducive to processing and shaping and uniformly adding carbon fiber and glass fiber. Moreover, the mechanical properties of the obtained polymer are comparable to those of the prior art. At the same time, the reduction of the melting temperature of the prepolymer, as well as the 10 - 30°C reduction of the initial curing temperature and the post-curing temperature compared with the prior art, is also beneficial to energy conservation.

[0058] The prepolymer has good solubility, which can broaden the application range of the material. It can be used for surface spraying and coatings under special working conditions. In addition, it can be dissolved in a solvent to impregnate reinforcing materials such as glass fiber and carbon fiber, and then the solvent can be dried to obtain prepreg and then molded by compression. If the solubility is not good, only melting can be used to manufacture composite materials.

[0059] Those of ordinary skill in the art should understand that: the discussion of any embodiment above is only exemplary and is not intended to imply that the protection scope of this application is limited to these examples; under the concept of this application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order. There are many other variations in different aspects of one or more embodiments of this application as described above, and they are not provided in detail for the sake of brevity.

[0060] One or more embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omission, modification, equivalent substitution, improvement, etc. made within the spirit and principle of one or more embodiments of this application shall be included in the protection scope of this application.

Claims

1. A spirofluorene diphthalonitrile monomer, characterized in that: The molecular structure of the spirofluorene diphthalonitrile monomer is as follows: 。 2. A method for preparing the spirofluorene diphthalonitrile monomer according to claim 1, characterized in that: The following steps are involved: Spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diphenol spirocyclic bisphenol ether, 4-nitrophthalonitrile, an acid-binding agent and an organic solvent are mixed; after the reaction is completed, the mixture is treated to obtain a spirofluorene diphthalonitrile monomer.

3. The method for preparing the spirofluorene diphthalonitrile monomer according to claim 2, characterized in that: The molar ratio of the spiro[9H-fluorene-9,9'-[9H]xanthene]-3',6'-diphenol spirocyclic bisphenol ether to 4-nitrophthalonitrile is 1:2-2.1, and the molar ratio of the acid binding agent to 4-nitrophthalonitrile is 1.2-1.5:

1.

4. The method for preparing the spirofluorene diphthalonitrile monomer according to claim 2, characterized in that: The organic solvent is an aprotic solvent, and the acid-binding agent is calcium carbonate, sodium carbonate or potassium carbonate.

5. The method for preparing the spirofluorene diphthalonitrile monomer according to claim 2, characterized in that: The treatment method is washing and vacuum drying. The vacuum drying conditions are: temperature 80±10℃; absolute vacuum degree is below 1000pa.

6. A method for preparing a spirofluorene diphthalonitrile polymer, characterized in that: The following steps are involved: Prepolymer synthesis: mixing the curing agent with the spirofluorene diphthalonitrile monomer as claimed in claim 1, heating and melting, to obtain a prepolymer; Curing reaction: curing the prepolymer to obtain a spirofluorene-based diphthalonitrile polymer.

7. The method for preparing the spirofluorene diphthalonitrile polymer according to claim 6, characterized in that: The curing reaction conditions are: in an inert gas atmosphere, first curing at 220° C.-240° C. for a period of time, then curing at 270° C. for a period of time, and finally curing at 320° C. for a period of time.

8. The method for preparing the spirofluorene diphthalonitrile polymer according to claim 6, characterized in that: The curing agent is a compound of the following structural formula: 。 9. The method for preparing the spirofluorene diphthalonitrile polymer according to claim 6, characterized in that: The mass ratio of the curing agent to the spirofluorene diphthalonitrile monomer is 1.5-4:

100.

10. A spirofluorene diphthalonitrile polymer, characterized in that: The method is adopted to obtain the product according to any one of claims 6 to 9.

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