Modified nylon flexibilizer, high-toughness prepreg resin, high-toughness prepreg, laminated board and preparation method and application thereof

Abstract

The invention provides a modified nylon flexibilizer, a high-toughness prepreg resin, a high-toughness prepreg, a laminated board and a preparation method and application thereof. The modified nylon toughening agent is prepared by reacting a mixture of nano silicon dioxide, graphene oxide and nylon with isocyanate-terminated polysiloxane; the isocyanate-terminated polysiloxane is obtained by carrying out a reaction on dihydroxy polydimethylsiloxane and diisocyanate; the high-toughness prepreg resin is prepared from raw materials including a modified nylon toughening agent, ultrahigh molecular weight epoxy resin, polyfunctional epoxy resin and a curing agent; the high-toughness prepreg is prepared from reinforced fibers, a resin matrix adhesive film A and a resin matrix adhesive film B. The resin matrix adhesive film A is obtained by coating high-toughness prepreg resin. According to the high-toughness prepreg prepared by the invention, the compression strength of a laminated plate after impact is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resins. Further, it relates to a modified nylon toughening agent, a high-toughness prepreg resin, a high-toughness prepreg, a laminate, and their preparation methods and applications. Background Art

[0002] Carbon fiber composites have high specific strength, specific stiffness, and specific modulus. At the same time, they have excellent fatigue resistance and corrosion resistance, and are highly designable. They are widely used in many fields such as aerospace, energy, military, automotive lightweight, and sports and leisure, and the application proportion is increasing day by day. The epoxy curing system is one of the most commonly used resin systems for resin matrix composites. In order to improve the heat resistance of the system, the epoxy resin and curing agent selected both have many rigid structures and usually have a high crosslinking density. In order to improve the toughness of epoxy resin-based composites, the epoxy resin matrix is usually toughened. For aerospace-grade composites, the post-impact compressive strength, abbreviated as compressive strength after impact (CAI), is generally used to measure the toughness of the composite material system. In order to solve the problems such as the large viscosity of the resin system caused by toughening the resin matrix and the poor impregnation effect of the matrix resin on the fibers, the toughening component is localized in the prepreg interlayer. Chinese invention patent CN104842619A provides a manufacturing process for a high-toughness multi-layer structure prepreg. On the basis of the three-layer structure of resin layer - fiber layer - resin layer, one or more toughening layers are added. The toughening layer exists in the form of a film, powder, or fabric, etc. The CAI of the toughened composite material reaches 260 MPa. Although the above toughening technology has achieved good toughening effects, it also brings other problems at the same time. The addition of the toughening layer makes the preparation process of the prepreg cumbersome. Interlayer toughening in the form of a film on the prepreg surface will cause one side of the prepreg to lose its adhesiveness, deteriorating the processing performance. Interlayer toughening in the form of powder will cause uneven dispersion of the powder on the prepreg surface, loss of adhesiveness on the prepreg surface, and deterioration of the production environment, etc.

[0003] Therefore, it is necessary to study a prepreg manufacturing process without a toughening layer, which can still achieve the toughening effect of the prepreg with a toughening layer after omitting the toughening layer. Summary of the Invention

[0004] In order to solve the technical problems existing in the prior art, the present invention provides a modified nylon toughening agent, a high-toughness prepreg resin, a high-toughness prepreg, a laminate, and their preparation methods and applications.

[0005] The present invention prepares a modified nylon toughening agent, which has a good toughening effect through the synergistic action of nano-silica (SiO 2 ), graphene oxide (GO), isocyanate-terminated polysiloxane, and nylon.

[0006] By adding a prepared modified nylon toughening agent and ultra-high molecular weight epoxy resin to a multi-functional epoxy resin, a resin adhesive film A is obtained after coating. At the same time, a resin with a lower viscosity is prepared and used to coat a resin adhesive film B. There is a difference in viscosity between resin adhesive film A and resin adhesive film B. Resin adhesive film A has a higher viscosity, while resin adhesive film B has a lower viscosity and can be quickly impregnated into the reinforcing fibers. The impregnation speed of resin adhesive film A is slower than that of resin adhesive film B during the prepreg process. By controlling the particle size of the modified nylon toughening agent, the diffusion of the modified nylon toughening agent into the reinforcing fiber layer can be blocked.

[0007] For the high-toughness prepreg prepared in the present invention, the modified nylon toughening agent is localized between the prepreg layers, significantly improving the compressive strength after impact of the laminate, and solving the disadvantages such as the cumbersome preparation process of conventional interlayer toughening, resulting in the loss of surface tack of the prepreg, poor processability, and limited performance improvement due to uneven distribution of the toughening agent.

[0008] One object of the present invention is to provide a modified nylon toughening agent, which is prepared by reacting a mixture of nano-silica, graphene oxide and nylon with an isocyanate-terminated polysiloxane; the isocyanate-terminated polysiloxane is obtained by reacting a raw material including dihydroxy polydimethylsiloxane and diisocyanate.

[0009] In a preferred embodiment of the present invention,

[0010] The average particle size of the nano-silica is 20 - 200 nm, preferably 30 - 80 nm;

[0011] The graphene oxide is monolayer or multilayer graphene oxide powder;

[0012] The nylon is at least one of nylon 6 and nylon 12, preferably at least one of nylon 6 resin powder and nylon 12 resin powder;

[0013] The weight average molecular weight of the dihydroxy polydimethylsiloxane is 400 - 1000;

[0014] The diisocyanate is at least one of toluene diisocyanate, isophorone diisocyanate and diphenylmethane diisocyanate.

[0015] Another object of the present invention is to provide a preparation method of a modified nylon toughening agent, including the following steps:

[0016] (1) Mix nano-silica, graphene oxide and nylon evenly and then extrude and granulate to obtain modified nylon particles;

[0017] (2) Grind and screen the modified nylon particles obtained in step (1) to obtain modified nylon powder;

[0018] (3) Under the protection of a protective gas, react a dihydroxypolydimethylsiloxane solution with a diisocyanate solution to obtain an isocyanate-terminated polysiloxane;

[0019] (4) React the modified nylon powder obtained in step (2) with the isocyanate-terminated polysiloxane obtained in step (3) to obtain a suspension, and remove the solvent to obtain the modified nylon toughening agent.

[0020] In a preferred embodiment of the present invention,

[0021] Step (1),

[0022] The mass of the nano-silica is 2-8% of the mass of the nylon, preferably 3-5%; and / or,

[0023] The mass of the graphene oxide is 0.5-3% of the mass of the nylon, preferably 1-2%; and / or,

[0024] The extrusion and granulation are carried out on a screw extruder; and / or,

[0025] Step (2),

[0026] The D50 particle size of the modified nylon powder is 20-40 μm, and the diameter of the fiber is generally about 5 μm. If the particle size of the toughening agent is too small, it will diffuse into the inside of the fiber and cannot remain between the layers, resulting in poor effects; if the particle size is too large, it will cause too thick layers between the layers, and the effects are also not good. When the D50 particle size of the toughening agent is 20-40 μm, the filtering effect of the fiber makes it difficult for the toughening agent to enter the inside of the fiber, and the toughening agent will remain on the surface of the prepreg and then remain between the layers of the composite material.

[0027] In a preferred embodiment of the present invention,

[0028] Step (3),

[0029] The protective gas is at least one of nitrogen and inert gas; and / or,

[0030] The molar ratio of the isocyanate group in the diisocyanate to the hydroxyl group in the dihydroxypolydimethylsiloxane is (1.9-2.1):1; and / or,

[0031] The dihydroxypolydimethylsiloxane is formulated with solvent A into a dihydroxypolydimethylsiloxane solution and then reacted. The mass concentration of the dihydroxypolydimethylsiloxane solution is 30-60%; the solvent A is preferably at least one of toluene and xylene; and / or,

[0032] The diisocyanate is formulated with solvent B into a diisocyanate solution and then undergoes a reaction. The mass concentration of the diisocyanate solution is 30-60%; the solvent B is preferably at least one of toluene and xylene; and / or,

[0033] A catalyst is added before the reaction. The catalyst is at least one of stannous octoate, dibutyltin dilaurate, triethylenediamine, lead octoate, zinc naphthenate, and tetra-isobutyl titanate; preferably, the dosage of the catalyst is 1.0-3.0 wt% of the mass of the diisocyanate, preferably 1.5-2.0 wt%; and / or,

[0034] The reaction temperature is 60-120°C, preferably 80-90°C; and / or,

[0035] The reaction time is 1-5 h, preferably 2-3 h.

[0036] In a preferred embodiment of the present invention,

[0037] Step (4),

[0038] The mass ratio of the isocyanate-terminated polysiloxane to the modified nylon powder is (1-1.5):20;

[0039] The isocyanate-terminated polysiloxane is formulated with solvent C into an isocyanate-terminated polysiloxane mixture and then undergoes a reaction. The mass concentration of the isocyanate-terminated polysiloxane mixture is 30-60%; the solvent C is preferably at least one of toluene and xylene;

[0040] The modified nylon powder is formulated with solvent D into a modified nylon powder mixture and then undergoes a reaction. The mass concentration of the modified nylon powder mixture is 30-60%; the solvent D is preferably at least one of toluene and xylene;

[0041] The reaction temperature is 60-120°C, preferably 90-100°C;

[0042] The reaction time is 1-5 h, preferably 2-3 h.

[0043] The third object of the present invention is to provide a high-toughness prepreg resin, which is prepared from raw materials including a modified nylon toughening agent, an ultra-high molecular weight epoxy resin, a polyfunctional epoxy resin, and a curing agent; the modified nylon toughening agent is the above-mentioned modified nylon toughening agent or the modified nylon toughening agent obtained by the above-mentioned preparation method.

[0044] In a preferred embodiment of the present invention,

[0045] Based on 100 parts by weight of the polyfunctional epoxy resin, the high-toughness prepreg resin includes:

[0046]

[0047] In a preferred embodiment of the present invention,

[0048] The multifunctional epoxy resin is at least one of trifunctional epoxy resin and tetrafunctional epoxy resin, preferably at least one of N,N,N',N'-tetraglycidyl-4,4-diaminodiphenylmethane epoxy resin (AG80), diglycidyl 4,5-epoxyhexane-1,2-dicarboxylate (TDE85), and triglycidyl p-aminophenol (MY0510);

[0049] The weight-average molecular weight of the ultra-high molecular weight epoxy resin is 20,000 to 40,000, preferably 25,000 to 35,000;

[0050] The curing agent A is at least one of 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and diaminodiphenyl methane.

[0051] The viscosity of the high-toughness prepreg resin is 80 to 130 Pas @ 70 °C.

[0052] The fourth object of the present invention is to provide a method for preparing a high-toughness prepreg resin, comprising the following steps:

[0053] (1) Mix the multifunctional epoxy resin and the ultra-high molecular weight epoxy resin evenly; preferably, the mixing temperature is 170 to 200 °C, and the mixing time is 0.5 to 1 h; preferably, the mixing temperature is 180 to 190 °C;

[0054] (2) Cool down the mixture obtained in step (1), add the modified nylon toughening agent, mix until uniform, adjust the temperature, and then add the curing agent A and mix until uniform to obtain the high-toughness prepreg resin; preferably, the temperature is cooled down to 50 to 70 °C; the temperature is adjusted to 65 to 75 °C. After adding the toughening agent, the viscosity increases, so the temperature is adjusted to be slightly higher.

[0055] The conditions for the first mixing and the second mixing are to mix and disperse evenly by planetary stirring.

[0056] The fifth object of the present invention is to provide a high-toughness prepreg, comprising the following components;

[0057] Based on 100 parts by weight of the reinforcing fiber,

[0058] Reinforcing fiber 100 parts by weight;

[0059] Resin matrix film A 15 to 30 parts by weight; preferably 20 to 25 parts by weight;

[0060] Resin matrix film B: 20 to 45 parts by weight; preferably 30 to 35 parts by weight;

[0061] The resin matrix film A is obtained by coating the above-mentioned high-toughness prepreg resin or the high-toughness prepreg resin obtained by the above preparation method;

[0062] Preferably,

[0063] The reinforcing fiber is at least one of carbon fiber, aramid fiber, and glass fiber; preferably carbon fiber;

[0064] The resin of the resin matrix film B is obtained by uniformly mixing epoxy resin, curing agent B, and optionally additives; based on 100 parts by weight of epoxy resin, the resin of the resin matrix film B includes the following components:

[0065] Epoxy resin: 100 parts by weight;

[0066] Curing agent B: 32 to 60 parts by weight;

[0067] Further preferably,

[0068] The epoxy resin is at least one of multi-functional epoxy and high-temperature resistant epoxy resin, and more preferably at least one of Huntsman 9663 epoxy resin, AG80 epoxy resin, and biphenyl phenol type epoxy resin;

[0069] The curing agent B is at least one of 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and diaminodiphenyl methane;

[0070] The viscosity of the resin of the resin matrix film B is 8 to 20 Pa s@70 °C.

[0071] The sixth object of the present invention is to provide a method for preparing a high-toughness prepreg, including;

[0072] Coating the high-toughness prepreg resin uniformly at 70 to 90 °C to obtain the resin matrix film A;

[0073] Coating the resin of the resin matrix film B uniformly at 60 to 75 °C to obtain the resin matrix film B;

[0074] Attach a layer of the resin matrix film A and the resin matrix film B on both sides of the reinforcing fiber respectively for impregnation to obtain the high-toughness prepreg; preferably, the reinforcing fiber is arranged unidirectionally; the impregnation temperature is 75 to 85 °C.

[0075] The seventh object of the present invention is to provide a laminate, which is obtained by cutting, laminating, and curing the prepreg.

[0076] The curing can be carried out in various ways, such as but not limited to thermal curing, light curing, etc.; the curing conditions for thermal curing have a relatively wide selection range, aiming to achieve curing, such as but not limited to 120 °C / 1 h - 180 °C / 2 h, etc.

[0077] The eighth object of the present invention is to provide an application of a modified nylon toughening agent, a high-toughness prepreg resin, a high-toughness prepreg, and a laminate in aerospace, military, or automotive fields.

[0078] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0079] The present invention prepares a modified nylon toughening agent, which has a good toughening effect through the synergistic action of nano-silica (SiO 2 ), graphene oxide (GO), isocyanate-terminated polysiloxane, and nylon.

[0080] By adding the prepared modified nylon toughening agent and ultra-high molecular weight epoxy resin to a multifunctional epoxy resin, resin film A is obtained after coating. At the same time, a resin with a lower viscosity is prepared, and resin film B is obtained by coating it. There is a difference in viscosity between resin film A and resin film B. Resin film A has a higher viscosity, and resin film B has a lower viscosity and can be quickly impregnated into the reinforcing fibers. The impregnation speed of resin film A is slower than that of resin film B during the prepreg process. By adjusting the particle size of the modified nylon toughening agent, the diffusion of the modified nylon toughening agent into the reinforcing fiber layer can be blocked.

[0081] For the high-toughness prepreg prepared by the present invention, the modified nylon toughening agent is localized between the prepreg layers, significantly improving the compressive strength after impact of the laminate, and solving the disadvantages of the conventional interlayer toughening preparation process being cumbersome, resulting in the loss of surface tack of the prepreg, poor processability, and limited performance improvement due to uneven distribution of the toughening agent. Specific Embodiments

[0082] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0083] The raw materials used in the examples and comparative examples of the present invention are all conventional commercially available raw materials.

[0084] The graphene oxide is an industrial monolayer graphene oxide powder from Suzhou Carbon Feng Technology, with 1 - 2 layers, a sheet diameter of 0.5 - 5 μm, a thickness of about 1 nm, and an oxygen content > 42%.

[0085]

Example 1

[0086] (1) Preparation of modified PA12 toughener

[0087] Mix SiO 2 (average particle size 30 nm), graphene oxide (hereinafter referred to as GO) and nylon 12 resin powder (hereinafter referred to as PA12) in proportion. The mass of SiO 2 is 5% of the mass of PA12, and the mass of GO is 1% of the mass of PA12. Use a screw extruder to mix and granulate the two, and use grinding and screening instruments to obtain modified nylon 12 powder, with an average particle size of the powder of 25 μm.

[0088] Mix toluene diisocyanate with toluene, with the mass percentage concentration of toluene diisocyanate being 40%. Protect the system with nitrogen and stir. Heat the system to 40 °C and add dibutyltin dilaurate, with the dosage of dibutyltin dilaurate being 2 wt% of toluene diisocyanate. Mix polydimethylsiloxane diol (weight-average molecular weight 400) with toluene, with the mass percentage concentration of the hydroxy polysiloxane being 40%. Drop the mixture of hydroxy polysiloxane and toluene into the mixture of toluene diisocyanate and toluene. The molar ratio of the isocyanate groups in toluene diisocyanate to the hydroxyl groups in polydimethylsiloxane diol is 2:1. After dropping, heat to 80 °C and react for 3 h to obtain isocyanate group-terminated polysiloxane.

[0089] Mix the modified nylon 12 powder with toluene, with the mass percentage concentration of the modified nylon 12 powder being 30%. Protect the system with nitrogen and stir. Heat the system to 40 °C. Mix the isocyanate group-terminated polysiloxane with toluene, with the mass percentage concentration of the mixture of isocyanate group-terminated polysiloxane being 30%. Drop the mixture of isocyanate group-terminated polysiloxane into the mixture of modified nylon 12 powder and toluene. The mass ratio of the isocyanate group-terminated polysiloxane to the modified nylon 12 powder is 1:20. After dropping, heat to 90 °C and react for 3 h to obtain a mixture of modified PA12 toughener and toluene. Remove the solvent to obtain the modified PA12 toughener.

[0090] (2) Preparation of high-toughness prepreg resin

[0091] The formulation composition is as follows:

[0092]

[0093] Mix ultra-high molecular weight epoxy resin with AG80 resin (N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane epoxy resin), heat up to 190 °C, mix for 0.5 h, then lower the temperature to 70 °C, add a mixture of modified PA12 toughening agent and toluene, stir and mix evenly, then remove the solvent, keep the system temperature at 75 °C, add diaminodiphenyl sulfone, and mix evenly to obtain a high-toughness prepreg resin.

[0094] (3) Preparation of high-toughness prepreg:

[0095] Composition of high-toughness prepreg:

[0096] Toray T800H×12k carbon fiber 100 parts by weight;

[0097] Resin matrix film A 25 parts by weight;

[0098] Resin matrix film B 30 parts by weight;

[0099] Preparation of resin matrix film A: Add the high-toughness prepreg resin to the resin tank of the coating machine, and evenly coat the resin matrix on the release paper at a coating temperature of 80 °C.

[0100] Preparation of resin matrix film B:

[0101] Composition of resin film B resin:

[0102]

[0103] Add the resin film B resin to the resin tank of the coating machine, and evenly coat the resin matrix on the release paper at a coating temperature of 65 °C.

[0104] Add the high-toughness prepreg resin to the resin tank of the coating machine, and evenly coat the resin matrix on the release paper at a coating temperature of 80 °C.

[0105] Pre-impregnation: Use Toray T800H×12k carbon fiber to prepare a prepreg with a fiber surface density of 130 g / m 2 of prepreg. Place two rolls of resin films on the upper and lower unwind stations at the front end of the prepreg machine. At the first, second, and third heating rollers and the heating plate, the upper and lower layers of the matrix resin films complete the impregnation of the unidirectionally arranged carbon fibers at an impregnation temperature of 85 °C. After cooling by the cooling plate, wind up the upper release paper, cover it with a PE film, and finally complete the winding of the prepreg.

[0106] (4) Preparation and performance evaluation of laminates:

[0107] Cut the prepreg into appropriate sizes according to the requirements of GB / T 21239-2007 standard, perform layup, and the layup sequence is [45 / 0 / -45 / 90]S. Then put it into the autoclave for curing. The curing process is 120℃ / 1h + 180℃ / 2h, and the heating rate is 2℃ / min. After curing, the laminate is cut to obtain a test sample with dimensions of 150mm×100mm×5mm. Conduct the compressive strength after impact test on the sample according to GB / T 21239-2007 standard.

[0108]

Example 2

[0109] The difference from Example 1 is: step (1) is different; specifically:

[0110] (1) Preparation of modified PA12 toughening agent

[0111] Mix SiO 2 (average particle size 30nm), GO and nylon 12 resin powder in proportion. The mass of SiO 2 is 3% of the mass of PA12, and the mass of GO is 2% of the mass of PA12. Use a screw extruder to mix and granulate the two, and use grinding and screening instruments to obtain modified nylon 12 powder with an average particle size of 25μm.

[0112] Mix isophorone diisocyanate and xylene. The mass percentage concentration of isophorone diisocyanate is 40%. Protect the system with nitrogen and stir. Heat the system to 40℃, and add dibutyltin dilaurate. The dosage of dibutyltin dilaurate is 1.5wt% of toluene diisocyanate. Mix dihydroxypolydimethylsiloxane (weight average molecular weight 400) and xylene. The mass percentage concentration of dihydroxypolydimethylsiloxane is 40%. Drop the mixture of dihydroxypolydimethylsiloxane and xylene into the mixture of isophorone diisocyanate and xylene. The molar ratio of isocyanate groups in isophorone diisocyanate to hydroxyl groups in dihydroxypolydimethylsiloxane is 1.9:1. After dropping, heat to 90℃ and react for 2h to obtain isocyanate group-terminated polysiloxane.

[0113] Mix the modified nylon 12 powder with xylene. The mass percentage concentration of SiO2 / GO / PA12 powder is 30%. Under nitrogen protection, stir and heat the system to 40°C. Mix the isocyanate group-terminated polysiloxane with toluene. The mass percentage concentration of the isocyanate group-terminated polysiloxane mixture is 30%. Drop the isocyanate group-terminated polysiloxane mixture into the mixture of modified nylon 12 powder and xylene. The mass ratio of the isocyanate group-terminated polysiloxane to the modified nylon 12 powder is 1.5:20. After dropping, heat the mixture to 100°C and react for 2 h to obtain a mixture of the modified PA12 toughening agent and xylene. After removing the solvent, the modified PA12 toughening agent is obtained.

[0114] Except for the above differences, other conditions in Example 2 are the same as those in Example 1. High-toughness prepreg resin, high-toughness prepreg, and laminates are obtained in sequence. The impact compressive strength test is carried out on the samples according to the standard of GB / T 21239-2007.

[0115]

Example 3

[0116] The difference from Example 1 is as follows: Step (1) is different; specifically:

[0117] (1) Preparation of the modified PA12 toughening agent

[0118] Mix SiO 2 (average particle size 80 nm), GO, and nylon 12 resin powder in proportion. The mass of SiO 2 is 3% of the mass of PA12, and the mass of GO is 2% of the mass of PA12. Use a screw extruder to mix and granulate the two, and use grinding and screening instruments to obtain modified nylon 12 powder with an average particle size of 25 μm.

[0119] Mix isophorone diisocyanate with xylene. The mass percentage concentration of isophorone diisocyanate is 50%. Under nitrogen protection, stir the system and heat it to 40°C. Add stannous octoate, and the dosage of stannous octoate is 1.5 wt% of toluene diisocyanate. Mix dihydroxypolydimethylsiloxane (weight average molecular weight 1000) with xylene. The mass percentage concentration of dihydroxypolydimethylsiloxane is 50%. Drop the mixture of dihydroxypolydimethylsiloxane and xylene into the mixture of isophorone diisocyanate and xylene. The molar ratio of the isocyanate group in isophorone diisocyanate to the hydroxyl group in dihydroxypolydimethylsiloxane is 2.1:1. After dropping, heat the mixture to 90°C and react for 2 h to obtain isocyanate group-terminated polysiloxane.

[0120] Mix the modified nylon 12 powder with xylene. The mass percentage concentration of the modified nylon 12 powder is 50%. Under the protection of nitrogen, stir and heat the system to 40°C. Mix the isocyanate group-terminated polysiloxane with xylene. The mass percentage concentration of the isocyanate group-terminated polysiloxane mixture is 50%. Drop the isocyanate group-terminated polysiloxane mixture into the mixture of the modified nylon 12 powder and xylene. The mass ratio of the isocyanate group-terminated polysiloxane to the modified nylon 12 powder is 1.5:20. After dropping, heat the mixture to 100°C and react for 2 hours to obtain a mixture of the modified PA12 toughening agent and xylene. Remove the solvent to obtain the modified PA12 toughening agent.

[0121] Except for the above differences, other conditions of Example 3 are the same as those of Example 1. High-toughness prepreg resin, high-toughness prepreg, and laminates are obtained in sequence. The impact compressive strength test is carried out on the samples according to the standard of GB / T 21239-2007.

[0122]

Example 4

[0123] The difference from Example 1 is that the average particle size of the modified nylon 12 powder obtained in step (1) is 20 μm;

[0124] Except for the above differences, other conditions of Example 4 are the same as those of Example 1. The modified PA12 toughening agent, high-toughness prepreg resin, high-toughness prepreg, and laminates are obtained in sequence. The impact compressive strength test is carried out on the samples according to the standard of GB / T 21239-2007.

[0125]

Example 5

[0126] The difference from Example 1 is that the average particle size of the modified nylon 12 powder obtained in step (1) is 40 μm;

[0127] Except for the above differences, other conditions of Example 5 are the same as those of Example 1. The modified PA12 toughening agent, high-toughness prepreg resin, high-toughness prepreg, and laminates are obtained in sequence. The impact compressive strength test is carried out on the samples according to the standard of GB / T 21239-2007.

[0128]

Example 6

[0129] The difference from Example 1 is that the preparation of the high-toughness prepreg resin in step (2) is different; specifically:

[0130] (2) Preparation of high-toughness prepreg resin

[0131] The formulation composition is:

[0132]

[0133] Mix ultra-high molecular weight epoxy resin with MY0510 epoxy resin, heat up to 180°C, mix for 1 hour, then lower the temperature to 50°C, add a mixed solution of a modified PA12 toughening agent and toluene, stir and mix evenly, and then remove the solvent. Keep the system temperature at 65°C, add diaminodiphenyl sulfone, and mix evenly to obtain a high-toughness prepreg resin;

[0134] Except for the above differences, other conditions in Example 6 are the same as those in Example 1. Sequentially obtain a modified PA12 toughening agent, a high-toughness prepreg, and a laminate, and conduct a post-impact compressive strength test on the sampled laminate according to the GB / T 21239-2007 standard.

[0135]

Example 7

[0136] The difference from Example 1 is that the formulation composition of the high-toughness prepreg resin in step (2) is different; specifically:

[0137] (2) The formulation composition of the high-toughness prepreg resin is as follows:

[0138]

[0139]

[0140] Except for the above differences, other conditions in Example 7 are the same as those in Example 1. Sequentially obtain a modified PA12 toughening agent, a high-toughness prepreg resin, a high-toughness prepreg, and a laminate, and conduct a post-impact compressive strength test on the sampled laminate according to the GB / T 21239-2007 standard.

[0141]

Example 8

[0142] The difference from Example 1 is that the composition of the high-toughness prepreg in step (3) is different, specifically:

[0143] (3) The composition of the high-toughness prepreg is as follows:

[0144] Toray T800H×12k carbon fiber 100 parts by weight;

[0145] Resin matrix film A 20 parts by weight;

[0146] Resin matrix film B 35 parts by weight;

[0147] Except for the above differences, other conditions in Example 8 are the same as those in Example 1. Sequentially obtain a modified PA12 toughening agent, a high-toughness prepreg resin, a high-toughness prepreg, and a laminate, and conduct a post-impact compressive strength test on the sampled laminate according to the GB / T 21239-2007 standard.

[0148]

Example 9

[0149] The differences from Example 1 are as follows: In the high-toughness prepreg in step (3), the resin composition of the resin film B used is different, and the impregnation temperature of the prepreg is different. Specifically:

[0150] (3) In the preparation of the high-toughness prepreg, the resin composition of the resin film B is:

[0151]

[0152] The impregnation temperature of the prepreg is 75 °C.

[0153] Except for the above differences, other conditions in Example 9 are the same as those in Example 1. The modified PA12 toughening agent, high-toughness prepreg resin, high-toughness prepreg, and laminate are obtained in sequence. The laminate is sampled for the impact-after compression strength test according to the standard of GB / T 21239-2007.

[0154]

Comparative Example 1

[0155] The difference from Example 1 is that in step (1), when preparing the modified nylon 12 powder, SiO 2 ;

[0156] Except for the above differences, other conditions in Comparative Example 1 are the same as those in Example 1. The modified PA12 toughening agent, prepreg resin, prepreg, and laminate are obtained in sequence. The sample is sampled for the impact-after compression strength test according to the standard of GB / T 21239-2007.

[0157]

Comparative Example 2

[0158] The difference from Example 1 is that in step (1), when preparing the modified nylon 12 powder, graphene oxide (GO) is not added;

[0159] Except for the above differences, other conditions in Comparative Example 2 are the same as those in Example 1. The modified PA12 toughening agent, prepreg resin, prepreg, and laminate are obtained in sequence. The sample is sampled for the impact-after compression strength test according to the standard of GB / T 21239-2007.

[0160]

Comparative Example 3

[0161] The difference from Example 1 is that in step (1), when preparing the modified PA12 toughening agent, toluene diisocyanate of equal mass is used to replace the isocyanate group-terminated polysiloxane;

[0162] Except for the above differences, other conditions in Comparative Example 3 are the same as those in Example 1. The modified PA12 toughening agent, prepreg resin, prepreg, and laminate are obtained in sequence. The sample is sampled for the impact-after compression strength test according to the standard of GB / T 21239-2007.

[0163]

Comparative Example 4

[0164] The differences from Example 1 are as follows: Steps (1) and (2) are not included. The prepreg resin used in the resin matrix film A in Step (3) does not contain the modified PA12 toughening agent. The specific formulation is as follows;

[0165] AG80 epoxy resin: 100 parts by weight;

[0166] Ultra-high molecular weight epoxy resin (weight average molecular weight 25,000): 10 parts by weight;

[0167] Diaminodiphenyl sulfone: 55 parts by weight;

[0168] The preparation method of the resin matrix film A is the same as that in Example 1;

[0169] Except for the above differences, other conditions of Comparative Example 4 are the same as those of Example 1. The prepreg and laminate are obtained in sequence, and the post-impact compressive strength test is carried out on the samples according to the standard of GB / T 21239-2007.

[0170]

Comparative Example 5

[0171] Steps (1) and (4) of Comparative Example 5 are the same as those of Example 1. The differences from Example 1 are as follows:

[0172] The modified PA12 toughening agent is not added to the high-toughness prepreg resin in Step (2);

[0173] When preparing the high-toughness prepreg in Step (3), at the first, second, and third heating rollers and the heating plate, the upper and lower layers of the matrix resin films complete the impregnation of the unidirectionally arranged carbon fibers. The impregnation temperature is 85°C. After impregnation, the same amount of the modified PA12 toughening agent as that in Example 1 is directly sprinkled on the surface of the prepreg. After cooling by the cooling plate, the upper release paper is wound up, covered with a PE film, and finally the prepreg is wound up;

[0174] Except for the above differences, other conditions of Comparative Example 5 are the same as those of Example 1. The modified PA12 toughening agent, prepreg resin, prepreg, and laminate are obtained in sequence, and the post-impact compressive strength test is carried out on the samples according to the standard of GB / T 21239-2007.

[0175]

Comparative Example 6

[0176] The differences from Example 1 are as follows: In Step (1), a grinding and screening instrument is used to obtain the modified nylon 12 powder, and the average particle size of the modified nylon 12 powder is 10 μm;

[0177] Except for the above differences, other conditions of Comparative Example 6 were the same as those of Example 1. The modified PA12 toughener, high-toughness prepreg resin, high-toughness prepreg, and laminate were obtained in sequence. The impact-after compression strength test was carried out on the samples according to the standard of GB / T 21239-2007.

[0178]

Comparative Example 7

[0179] The difference from Example 1 was that in step (1), a grinding and screening instrument was used to obtain the modified nylon 12 powder, and the average particle size of the modified nylon 12 powder was 60 μm;

[0180] Except for the above differences, other conditions of Comparative Example 7 were the same as those of Example 1. The modified PA12 toughener, high-toughness prepreg resin, high-toughness prepreg, and laminate were obtained in sequence. The impact-after compression strength test was carried out on the samples according to the standard of GB / T 21239-2007.

[0181] The performance evaluation of the laminate was carried out according to the method described in Example 1, and the results are shown in Table 1.

[0182] Table 1 Test results of impact-after compression strength of prepreg laminates

[0183]

[0184] Compared with Example 1, the impact-after compression strengths of the laminates obtained in Comparative Examples 1-3 decreased by 15.2%, 14.0%, and 12.4% respectively, proving that in Example 1, there was a synergistic effect among nylon 12, nano-silica (SiO 2 ), graphene oxide (GO), and isocyanate-terminated polysiloxane. SiO 2 and graphene oxide increased the interfacial area of the material, which could improve the rigidity and toughness of nylon. Isocyanate-terminated polysiloxane had good toughness and could improve the toughness of nylon. The impact-after compression strength (CAI) of the composite material required both high rigidity and high toughness. Without any one of them, the obtained modified nylon toughener would affect the CAI of the final composite material.

[0185] Compared with Example 1, the impact-after compression strength of the laminate obtained in Comparative Example 4 decreased by 37.3%, proving that the modified nylon toughener was crucial for the toughening performance of the composite material. When the modified nylon toughener was not added to the resin film A, the impact resistance of the finally obtained composite material decreased greatly.

[0186] Compared with Example 1, the impact-after compression strength of the laminate obtained in Comparative Example 5 decreased by 23.6%, proving that how the modified nylon toughener was added to the composite material matrix had a great impact on the toughening effect of the final composite material.

[0187] Compared with Example 1, the post-impact compression strengths of the laminates obtained in Comparative Examples 6-7 decreased by 12.7% and 16.5% respectively, proving that the particle size of the modified nylon 12 powder has a great influence on the toughening effect of the composite material. When the D50 particle size of the modified nylon 12 powder is 20-40 μm, the toughening effect is better.

[0188] In Examples 1-9 and Comparative Examples 1-3, the resin viscosity of the high-toughness prepreg resin for preparing Resin Film A was about 10 times that of the resin viscosity of Resin Film B. The resin of Resin Film B had a lower viscosity and could be quickly impregnated into the reinforcing fibers. The high-toughness prepreg resin had a high viscosity and slow impregnation of fibers, and could more easily remain between layers.

[0189] The post-impact compression strengths of the composites prepared in Examples 1-9 were 303-326 MPa, proving that the modified nylon toughening agent prepared by the present invention significantly improved the post-impact compression strength of the laminate between the prepreg layers, solving the problems of cumbersome preparation process for conventional interlayer toughening, resulting in loss of surface tack of the prepreg, poor processability, and limited performance improvement due to uneven distribution of the toughening agent.

Claims

1. A modified nylon toughening agent is prepared by reacting a mixture of nano-silica, graphene oxide and nylon with isocyanate-terminated polysiloxane; the isocyanate-terminated polysiloxane is obtained by reacting raw materials including dihydroxy polydimethylsiloxane and diisocyanate.

2. The modified nylon toughening agent according to claim 1, characterized in that: the average particle size of the nano-silica is 20 - 200 nm, preferably 30 - 80 nm; and / or, the nylon is at least one of nylon 6 and nylon 12, preferably at least one of nylon 6 resin powder and nylon 12 resin powder; and / or, the weight-average molecular weight of the dihydroxy polydimethylsiloxane is 400 - 1000; and / or, the diisocyanate is at least one of toluene diisocyanate, isophorone diisocyanate and diphenylmethane diisocyanate.

3. A preparation method of the modified nylon toughening agent according to claim 1 or 2, comprising the following steps: (1) Mix nano-silica, graphene oxide and nylon evenly and then extrude and granulate to obtain modified nylon particles; (2) Grind and screen the modified nylon particles obtained in step (1) to obtain modified nylon powder; (3) Under the protection of a protective gas, react the dihydroxy polydimethylsiloxane solution with the diisocyanate solution to obtain isocyanate-terminated polysiloxane; (4) React the modified nylon powder obtained in step (2) with the isocyanate-terminated polysiloxane obtained in step (3) to obtain a suspension, and remove the solvent to obtain the modified nylon toughening agent.

4. The preparation method of the modified nylon toughening agent according to claim 3, characterized in that: In step (1), the mass of the nano-silica is 2 - 8% of the mass of the nylon, preferably 3 - 5%; and / or, the mass of the graphene oxide is 0.5 - 3% of the mass of the nylon, preferably 1 - 2%; and / or, the extrusion and granulation are carried out on a screw extruder; and / or, In step (2), the D50 particle size of the modified nylon powder is 20 - 40 μm.

5. The preparation method of the modified nylon toughening agent according to claim 3, characterized in that: In step (3), the protective gas is at least one of nitrogen and inert gas; and / or, the molar ratio of the isocyanate group in the diisocyanate to the hydroxyl group in the dihydroxy polydimethylsiloxane is (1.9 - 2.1):1; and / or, the dihydroxy polydimethylsiloxane is formulated into a dihydroxy polydimethylsiloxane solution with solvent A and then reacted, and the mass concentration of the dihydroxy polydimethylsiloxane solution is 30 - 60%; the solvent A is preferably at least one of toluene and xylene; and / or, the diisocyanate is formulated into a diisocyanate solution with solvent B and then reacted, and the mass concentration of the diisocyanate solution is 30 - 60%; the solvent B is preferably at least one of toluene and xylene; and / or, A catalyst is added before the reaction. The catalyst is at least one of stannous octoate, dibutyltin dilaurate, triethylenediamine, lead octoate, zinc naphthenate, and tetra-isobutyl titanate. Preferably, the dosage of the catalyst is 1.0 to 3.0 wt% of the mass of the diisocyanate, preferably 1.5 to 2.0 wt%; and / or, The reaction temperature is 60 to 120 °C, preferably 80 to 90 °C; and / or, The reaction time is 1 to 5 h, preferably 2 to 3 h.

6. The method for preparing the modified nylon toughening agent according to claim 3, characterized in that: Step (4), The mass ratio of the isocyanate-terminated polysiloxane to the modified nylon powder is (1 to 1.5):20; and / or, The isocyanate-terminated polysiloxane is formulated with solvent C into an isocyanate-terminated polysiloxane mixed solution and then reacted. The mass concentration of the isocyanate group-terminated polysiloxane mixed solution is 30 to 60%; The solvent C is preferably at least one of toluene and xylene; and / or, The modified nylon powder is formulated with solvent D into a modified nylon powder mixed solution and then reacted. The mass concentration of the modified nylon powder mixed solution is 30 to 60%; The solvent D is preferably at least one of toluene and xylene; and / or, The reaction temperature is 60 to 120 °C, preferably 90 to 100 °C; and / or, The reaction time is 1 to 5 h, preferably 2 to 3 h.

7. A high-toughness prepreg resin is prepared from raw materials including a modified nylon toughening agent, an ultra-high molecular weight epoxy resin, a polyfunctional epoxy resin, and a curing agent A. The modified nylon toughening agent is the modified nylon toughening agent described in claim 1 or 2 or the modified nylon toughening agent obtained by the preparation method described in any one of claims 3 to 6.

8. The high-toughness prepreg resin according to claim 7, characterized in that: Based on 100 parts by weight of the polyfunctional epoxy resin, the high-toughness prepreg resin includes:

9. The high-toughness prepreg resin according to claim 7, characterized in that: The polyfunctional epoxy resin is at least one of a trifunctional epoxy resin and a tetrafunctional epoxy resin, preferably at least one of N,N,N',N'-tetraglycidyl-4,4-diaminodiphenylmethane epoxy resin, 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester, and triglycidyl p-aminophenol; and / or, The weight-average molecular weight of the ultra-high molecular weight epoxy resin is 20,000 to 40,000, preferably 25,000 to 35,000; and / or, The curing agent A is at least one of 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and diaminodiphenyl methane.

10. A method for preparing a high-toughness prepreg resin according to any one of claims 7 to 9, comprising the following steps: (1) Mix the polyfunctional epoxy resin and the ultra-high molecular weight epoxy resin evenly; preferably, the mixing temperature is 170 to 200 °C, and the mixing time is 0.5 to 1 h; the mixing temperature is more preferably 180 to 190 °C; (2) Cool down the mixture obtained in step (1), add the modified nylon toughening agent, mix until uniform, adjust the temperature, and then add curing agent A and mix until uniform to obtain the high-toughness prepreg resin; preferably, cool down to 50-70 °C; adjust the temperature to 65-75 °C.

11. A high-toughness prepreg, comprising the following components: Based on 100 parts by weight of reinforcing fibers, 100 parts by weight of reinforcing fibers; 15-30 parts by weight of resin matrix film A; preferably 20-25 parts by weight; 20-45 parts by weight of resin matrix film B; preferably 30-35 parts by weight; The resin matrix film A is obtained by coating the high-toughness prepreg resin described in any one of claims 7-9 or the high-toughness prepreg resin obtained by the preparation method of claim 10; Preferably, The reinforcing fiber is at least one of carbon fiber, aramid fiber, and glass fiber; preferably carbon fiber; and / or, The resin of the resin matrix film B is obtained by uniformly mixing epoxy resin, curing agent B, and optionally additives; based on 100 parts by weight of epoxy resin, the resin of the resin matrix film B comprises the following components: 100 parts by weight of epoxy resin; 32-60 parts by weight of curing agent B; Further preferably, The epoxy resin is at least one of multi-functional epoxy resin and high-temperature resistant epoxy resin, more preferably at least one of Huntsman 9663 epoxy resin, AG80 epoxy resin, and biphenyl phenol type epoxy resin; and / or, The curing agent B is at least one of 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, and diaminodiphenyl methane.

12. A preparation method of a high-toughness prepreg as claimed in claim 11, comprising: Coat the high-toughness prepreg resin uniformly at 70-90 °C to obtain the resin matrix film A; Coat the resin of the resin matrix film B uniformly at 60-75 °C to obtain the resin matrix film B; Attach a layer of the resin matrix film A and the resin matrix film B on both sides of the reinforcing fiber respectively for impregnation to obtain the high-toughness prepreg; preferably, the reinforcing fiber is arranged unidirectionally; the impregnation temperature is 75-85 °C.

13. A laminate obtained from a high-toughness prepreg as claimed in claim 11 or a high-toughness prepreg obtained by the preparation method as claimed in claim 12; the laminate is obtained by cutting, laminating, and curing the prepreg.

14. Application of the modified nylon toughening agent as claimed in claim 1 or 2, or the modified nylon toughening agent obtained by the preparation method as claimed in any one of claims 3-6, the high-toughness prepreg resin as claimed in any one of claims 7-9, or the high-toughness prepreg resin obtained by the preparation method as claimed in claim 10, the high-toughness prepreg as claimed in claim 11, or the high-toughness prepreg obtained by the preparation method as claimed in claim 12, and the laminate as claimed in claim 13 in aerospace, military, or automotive applications.

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