Triptycene modified semi-crosslinking interpenetrating network toughened bismaleimide resin compound

Abstract

The invention relates to the technical field of polymer composite materials, and particularly discloses a triptycene modified semi-crosslinking interpenetrating network toughened bismaleimide resin compound. The triptycene modified semi-crosslinked interpenetrating network toughened bismaleimide resin compound provided by the invention is prepared from the following raw materials: a bismaleimide monomer and / or a homolog thereof, a modified triptycene'knot 'molecular polymer, an allyl-containing monomer and / or a homolog thereof and the like. And the toughness of the resin is improved while the heat resistance of the bismaleimide resin is not reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composite materials, in particular to a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite. Background Art

[0002] Bismaleimide resin, containing maleimide as an active end group, is a thermosetting resin that can be copolymerized and modified with a variety of compounds. Its backbone, containing aromatic and nitrogen heterocyclic rings, offers advantages such as high-temperature resistance, heat and humidity resistance, radiation resistance, and excellent processability, making it widely used in load-bearing structures in aerospace vehicles. However, the inherent toughness of bismaleimide resin is poor, making it difficult to meet the growing requirements for use in aircraft primary structures, necessitating toughening modification.

[0003] Traditional methods for toughening and modifying bismaleimide resins include copolymerization to extend the molecular chain, allyl modification, rubber toughening modification, and thermoplastic resin toughening. As the strength modulus of new carbon fibers continues to increase, it is difficult for bismaleimide resins using traditional formulation design ideas to match them. The thermoplastic resin toughening bismaleimide resin matrix technology commonly used in engineering currently encounters a major bottleneck. Improving toughness requires increasing the thermoplastic resin content, and increasing the thermoplastic resin content often leads to poor processability of the prepreg, making it difficult to meet engineering requirements. Therefore, it is necessary to study new methods for constructing bismaleimide resin systems based on the molecular structure design of the resin matrix and to develop the next generation of high-performance bismaleimide resin composite toughening technology.

[0004] Based on the above problems, the present invention aims to develop a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite to achieve toughening of the bismaleimide resin and improve the resin toughness without reducing the heat resistance. Summary of the Invention

[0005] The main technical problem solved by the present invention is to provide a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite, which can achieve toughening of the bismaleimide resin and improve the toughness of the resin without reducing the heat resistance of the bismaleimide resin.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite, the composite comprising the following raw materials in weight percentage:

[0007]

[0008] The triptycene molecule is a three-dimensional organic conjugated material formed by three benzene rings interconnected by bridgehead carbon atoms. It has D3h symmetry. In terms of spatial structure, the three benzene rings are 120° to each other. The triptycene molecule can be modified through amination reaction. Aromatic imines, alkyl chains and other groups are further grafted onto the benzene rings through the amino group and polymerized into a polymer with a "knot" structure (the alkyl chain in the molecule is the "rope" and the triptycene structure is the "knot").

[0009] The modified triptycene "knot" molecular polymer used in the present invention is selected from at least one of the polymers represented by the following formulas 1 to 5:

[0010]

[0011]

[0012] In the numerators of the above formulas 1 to 5, the value range of n is: 20≤n≤50.

[0013] As an embodiment of the present invention, the bismaleimide monomer includes at least one of diaminotoluene, aliphatic diamine compounds, aliphatic amine compounds, p-xylylenediamine, alicyclic diamine compounds, and alicyclic amine compounds;

[0014] The bismaleimide monomer homologue is selected from at least one of 4,4'-diaminodiphenylmethane bismaleimide, 1,2-phenylene bismaleimide, 1,4-phenylene bismaleimide, N,N'-m-phenylene bismaleimide, N,N'-(4-methyl-1,3-phenylene)-bismaleimide, 4,4'-diphenyl ether bismaleimide, 2,2-bisphenol A bismaleimide phenylene ether, and 1,5-bismaleimide pentane.

[0015] As an embodiment of the present invention, the allyl group-containing monomer and / or its homologue is selected from at least one of diallyl bisphenol A, bisphenol A diallyl ether, allyl cresol, 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone, diallyl isocyanurate, triallyl isocyanurate and oligomers thereof.

[0016] As an embodiment of the present invention, the toughening agent is thermoplastic material particles, selected from at least one of polysulfone, polyethersulfone, polyetherimide, polyimide and modified products, and the particle diameter D50 is 1-50 μm.

[0017] As an embodiment of the present invention, the modifier includes at least one of a flow regulator, a filler, and an anti-aging agent.

[0018] As a preferred embodiment of the present invention, the modifier is 4,4'-dimethylbenzophenone.

[0019] The present invention also provides a method for preparing the composite of the present invention, comprising the steps of:

[0020] (1) Mix component B and component C and stir to form a transparent dissolved substance;

[0021] (2) mixing the dissolved substance with a portion of component A to form a prepolymer that is mixed and entangled at the molecular level; the number average molecular weight of the obtained prepolymer is 500-2000;

[0022] (3) The prepolymer is mixed with the remaining component A, the toughening agent, and the modifier to form a suspension, thereby obtaining a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite.

[0023] Preferably, in step (1), the mixing and stirring is carried out at 60-180° C., the stirring time is 15-180 minutes, and the stirring speed is 50-600 rpm.

[0024] Preferably, in step (2), the mixing is carried out at 70-180° C., the mixing time is 5-120 minutes, and the stirring speed is 100-1000 rpm.

[0025] Preferably, in step (3), the mixing is carried out at 80-180° C., the mixing time is 2-240 minutes, and the stirring speed is 5-800 rpm.

[0026] The present invention also provides the use of the triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite provided by the present invention in the preparation of the main load-bearing structure of an aircraft fuselage.

[0027] The present invention further provides a composite material, which is prepared using the triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite provided by the present invention; the preparation process comprises:

[0028] coating the triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite to prepare an adhesive film;

[0029] The adhesive film is compounded with the fiber to form a prepreg. The compounding process can be carried out by hot melt method or solvent method. The compounding temperature is 50-115°C. The fiber weight per unit area of ​​the formed prepreg is 50-280g / m 2 ;

[0030] The prepreg is cured and formed to obtain the composite material;

[0031] Wherein, the fiber is selected from any one of carbon fiber, glass fiber, aramid fiber, quartz fiber and fabrics thereof.

[0032] Preferably, the surface density of the film is 20-100 g / m 2 .

[0033] The composite material provided by the present invention has an interlaminar shear strength of ≥90 MPa and a glass transition temperature of ≥240°C.

[0034] The present invention also provides application of the composite material of the present invention in the main load-bearing structure of an aircraft fuselage.

[0035] The present invention achieves molecular-level mixing and entanglement of modified triptychene "knot" molecular polymers with bismaleimide resins to form a semi-crosslinked interpenetrating network system, thereby toughening the bismaleimide resin and improving the toughness of the resin without reducing the heat resistance of the bismaleimide resin. Interpenetrating network polymers refer to two or more crosslinked network polymers that randomly interpenetrate and entangle with each other to form a unique class of polymer blends. For a two-component system, if one component is a network structure and the other component is a linear structure, this polymer is called a semi-interpenetrating network polymer. This network structure has the effect of forced inclusion, and the components connected by the network produce synergistic effects on some special functions, so that the overall performance of the material is transformed in a more optimal direction. The crosslinked interpenetrating network structure is not a simple physical blend, but a molecular-level mixing and entanglement. During the molecular curing process, the system causes unstable induced phase separation due to chain growth, but the mutual entanglement at the molecular level limits this separation. After curing is completed, the interpenetrating network structure is locked to achieve the effect of bulk toughening. The invention improves the toughness of the bismaleimide resin while maintaining its heat resistance by establishing a suitable interpenetrating network structure.

[0036] The triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite prepared by the present invention can be further compounded with carbon fiber, glass fiber, aramid fiber, quartz fiber and their fabrics. For example, the composite material prepared after compounding with carbon fiber has an interlaminar shear strength greater than 90 MPa and a glass transition temperature above 240°C, and has broad application prospects in the main load-bearing structure of aircraft fuselage. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a photo of a composite material test plate prepared in Example 3 of the present invention;

[0038] Figure 2 This is a physical picture of the composite material test plate prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0039] The following examples are intended to further illustrate the present invention, but are not intended to limit the scope of protection of the present invention.

[0040] In the following examples, unless otherwise specified, all raw materials used were purchased.

[0041] Example 1

[0042] This embodiment provides a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite, the raw materials and composition of which are shown in Table 1 below.

[0043] Table 1

[0044]

[0045] The structural formula of the polyimide-type triptycene "knot" molecule is shown below, and its number average molecular weight is 16,500:

[0046]

[0047] The structural formula of the naphthalimide-type triptycene "knot" molecule is shown below, with a number average molecular weight of 18,900:

[0048]

[0049] The triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite provided in this embodiment is prepared by the following steps:

[0050] (1) Add component B and component C into a mixing container and stir to dissolve to form a transparent solution; the mixing and stirring is carried out at 120±5°C, the stirring time is 45 minutes, and the stirring speed is 500 rpm;

[0051] (2) adding the dissolved substance and 4,4'-diaminodiphenylmethane bismaleimide into a mixing container and stirring to form a prepolymer with molecular level mixing and entanglement; the mixing and stirring is carried out at 130±5°C, the mixing and stirring time is 60 minutes, and the stirring speed is 300 rpm; the number average molecular weight of the obtained prepolymer is 1500;

[0052] (3) The prepolymer, 1,2-phenylene bismaleimide, toughening agent, and modifier are added to a mixing container, and stirred at 155±5°C for 75 minutes at a stirring speed of 35 rpm to obtain a suspension, which is a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite.

[0053] Example 2

[0054] This embodiment provides a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite, the raw materials and composition of which are shown in Table 2 below.

[0055] Table 2

[0056]

[0057] The structural formula of the bismaleimide-type triptycene "knot" molecule is shown below, and its number average molecular weight is 23,700:

[0058]

[0059] The triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite provided in this embodiment is prepared by the following steps:

[0060] (1) Add component B and component C into a mixing container and stir to dissolve to form a transparent solution; the mixing and stirring is carried out at 130±5°C, the stirring time is 30 minutes, and the stirring speed is 400 rpm;

[0061] (2) adding the dissolved substance and 4,4'-diaminodiphenylmethane bismaleimide into a mixing container and stirring to form a prepolymer with molecular level mixing and entanglement; the mixing and stirring is carried out at 130±5°C, the mixing and stirring time is 45 minutes, and the stirring speed is 500 rpm; the number average molecular weight of the obtained prepolymer is 750;

[0062] (3) The prepolymer, 1,4-phenylene bismaleimide, toughening agent and modifier are added to a mixing container, and stirred and mixed at 150±5°C for 60 minutes at a stirring speed of 50 rpm to obtain a suspension, which is a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite.

[0063] Example 3

[0064] This embodiment provides a composite material, which is prepared using the triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite provided in Example 1. The preparation process is as follows:

[0065] The triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite prepared in Example 1 was evenly coated on a film-forming device to obtain a film; the film had a surface density of 33 g / m 2 ;

[0066] The adhesive film is compounded with carbon fiber on a composite device to form a prepreg. The composite process adopts a hot melt method and the composite temperature is 90-100°C. The fiber weight per unit area of ​​the formed prepreg is 133g / m 2 ;

[0067] The prepreg was cured in an autoclave at 180°C for 2 hours and 205°C for 5 hours under a pressure of 0.6 MPa to obtain a composite material. Figure 1 .

[0068] The interlaminar shear strength of the composite material is 100 MPa (tested using ASTM D2344-22);

[0069] The glass transition temperature is 250°C (tested using ASTM D7028-07).

[0070] Example 4

[0071] This embodiment provides a composite material, which is prepared using the triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite provided in Example 2. The preparation process is as follows:

[0072] The triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite prepared in Example 2 was evenly coated on a film-forming device to obtain a film; the film had a surface density of 40 g / m 2 ;

[0073] The adhesive film is compounded with carbon fiber on a composite device to form a prepreg. The composite process adopts a hot melt method and the composite temperature is 100-105°C. The fiber weight per unit area of ​​the formed prepreg is 160g / m 2 ;

[0074] The prepreg was cured in an autoclave at 0.6 MPa pressure at 150°C for 1 hour, 180°C for 2 hours, and 205°C for 5 hours to obtain a composite material. Figure 2 .

[0075] The interlaminar shear strength of the composite material is 95 MPa (testing method is the same as that of Example 3), and the glass transition temperature is 245° C. (testing method is the same as that of Example 3).

[0076] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or any direct or indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite, characterized in that: The composite comprises the following raw materials in weight percentage: Wherein, the modified triptycene "knot" molecular polymer is selected from at least one of the polymers represented by the following formulas 1 to 5: Formula 1 Bismaleimide-type triptycene "knot" molecule Formula 2 Polyimide-type triptycene "knot" molecule Formula 3 Naphthalimide-type triptycene "knot" molecule Formula 4 Tripterygium-type Tripterygium "knot" molecule Formula 5: Flexible long-chain triptycene "knot" molecule; In Formula 1 to Formula 5, the value range of n is: 20≤n≤50.

2. The composite according to claim 1, characterized in that The bismaleimide monomer includes at least one of diaminotoluene, aliphatic diamine compounds, aliphatic amine compounds, p-xylylenediamine, alicyclic diamine compounds, and alicyclic amine compounds; The bismaleimide monomer homologue is selected from at least one of 4,4'-diaminodiphenylmethane bismaleimide, 1,2-phenylene bismaleimide, 1,4-phenylene bismaleimide, N,N'-m-phenylene bismaleimide, N,N'-(4-methyl-1,3-phenylene)-bismaleimide, 4,4'-diphenyl ether bismaleimide, 2,2-bisphenol A bismaleimide phenylene ether, and 1,5-bismaleimide pentane.

3. The composite according to claim 1, characterized in that The allyl group-containing monomer and / or its homologue is selected from at least one of diallyl bisphenol A, bisphenol A diallyl ether, allyl cresol, 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone, diallyl isocyanurate, triallyl isocyanurate and oligomers thereof.

4. The composite according to claim 1, characterized in that The toughening agent is thermoplastic material particles, selected from at least one of polysulfone, polyethersulfone, polyetherimide, polyimide and modified products, and the particle diameter D50 is 1-50 μm.

5. The composite according to claim 1, characterized in that The modifier includes at least one of a flow regulator, a filler, and an anti-aging agent.

6. The composite according to claim 5, characterized in that The modifier is 4,4'-dimethylbenzophenone.

7. A method for preparing the composite according to any one of claims 1 to 6, characterized in that: Including steps: (1) Mix component B and component C and stir to form a transparent dissolved substance; (2) mixing the dissolved substance with a portion of component A to form a prepolymer that is mixed and entangled at the molecular level; (3) The prepolymer is mixed with the remaining component A, the toughening agent, and the modifier to form a suspension, thereby obtaining a triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite.

8. Use of the composite material according to any one of claims 1 to 6 or the composite material obtained by the preparation method according to claim 7 in the preparation of the main load-bearing structure of an aircraft fuselage.

9. A composite material, prepared using the composite according to any one of claims 1 to 6 or the composite obtained by the preparation method according to claim 7; the preparation process comprising: coating the triptycene-modified semi-crosslinked interpenetrating network toughened bismaleimide resin composite to prepare an adhesive film; Compounding the adhesive film with fibers to form a prepreg; The prepreg is cured and formed to obtain the composite material; Wherein, the fiber is selected from any one of carbon fiber, glass fiber, aramid fiber, quartz fiber and fabrics thereof.

10. Use of the composite material according to claim 9 in the main load-bearing structure of an aircraft fuselage.

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