A cage type toughening agent, a preparation method thereof, and a high-temperature-resistant low-loss adhesive film and a preparation method thereof

Abstract

The application provides a cage type toughening agent and a preparation method thereof and a high-temperature-resistant low-loss adhesive film and a preparation method thereof, and belongs to the technical field of resin composite materials.The application uses active end group polyimide and POSS as monomers for preparing the cage type toughening agent, uses a catalyst to promote the reaction of the monomers, uses an organic solvent to dissolve the monomers and form liquid drops containing the monomers, uses a dispersing agent to disperse the liquid drops, and obtains the cage type toughening agent through suspension polymerization in the case that deionized water is used as a continuous phase.The cage type toughening agent provided by the application uses POSS as an inner core and uses a high-temperature-resistant thermoplastic polyimide resin with active end groups as an outer shell, the POSS provides high-temperature resistance, flame resistance and low moisture absorption, the polyimide layer provides primary toughening, the POSS provides secondary toughening, and the cage type toughening agent has the effect of double toughening; and the cage type toughening agent has good solubility and interfacial combination, can be matched with nitrile group resin, and can be used as a toughening agent for nitrile group resin.

Description

Technical Field

[0001] This invention relates to the field of resin composite materials technology, and in particular to a cage-type toughening agent and its preparation method, and a high-temperature resistant, low-loss adhesive film and its preparation method. Technical Background

[0002] Modern aerospace equipment places more stringent demands on the heat resistance and stability of thermosetting resin films. However, currently, thermosetting resin films...

[0003] Among films, polyimide films, which have the highest temperature resistance, do not exceed 450℃. However, during the curing process, small molecules are released, which can be highly corrosive to product components, failing to meet the requirements of practical applications. For example, Chinese patent CN201310096029.X discloses a high-temperature resistant carrier film and its preparation method. After curing, the thermal weight loss is as low as 2.7% at 433℃, and the shear strength reaches 6.5 MPa at 400℃. Although this method exhibits higher heat resistance stability compared to other types of films, its temperature resistance still cannot meet the requirements of practical applications.

[0004] In recent years, nitrile resins have been found to possess high thermal stability and flame retardancy due to the formation of phthalocyanine rings in their cured products. Furthermore, nitrile resins offer strong designability and processability comparable to cyanate ester resins. The curing process releases no small molecules, resulting in products with good dimensional stability, making them potential applications in high-end manufacturing fields requiring high heat resistance. However, traditional toughening materials such as rubber particles, high-performance engineering plastics, and thermosetting resins are incompatible with nitrile resins in terms of temperature resistance and processability, thus failing to effectively toughen and modify nitrile resins. Consequently, modified nitrile resins obtained using existing methods and technologies cannot be practically used to prepare high-temperature resistant adhesive film materials.

[0005] Therefore, there is an urgent need to provide a toughening agent suitable for improving the heat resistance and toughness of nitrile resins. Summary of the Invention

[0006] The purpose of this invention is to provide a toughening agent that is highly suitable for improving the heat resistance and toughness of nitrile resins.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a cage-type toughening agent, which is prepared by suspension polymerization from raw materials comprising the following components in parts by mass: 10-95 parts of active end-group polyimide, 1-5 parts of epoxy-based cage-type silsesquioxane, 0.1-0.5 parts of catalyst, 0.01-0.10 parts of dispersant, 500-1000 parts of organic solvent, and 1000-2000 parts of deionized water.

[0009] Preferably, the active end-group polyimide comprises one or more compounds as shown in Formulas I to V:

[0010]

[0011] In formulas I to V, R is independently CH3, CH2CH3, or benzyl;

[0012] n independently ranges from 10 to 30;

[0013] In the formula V, x is 5 to 20, y is 5 to 20, and x+y is 10 to 30.

[0014] Preferably, the epoxy-based cage-type silsesquioxane has the structural formula shown in Formula VI:

[0015] ;

[0016] In equation VI, R is

[0017]

[0018]

[0019] The present invention also provides a method for preparing the cage-type toughening agent described in the above technical solution, comprising: mixing an active end-group polyimide, an epoxy-based cage-type silsesquioxane, a dispersant, a portion of an organic solvent and deionized water and then stirring at high speed to obtain a suspension;

[0020] The remaining organic solvent and catalyst are mixed to obtain a catalyst solution;

[0021] The catalyst solution is added dropwise to the suspension to carry out a polymerization reaction, thereby obtaining a cage-type toughening agent.

[0022] This invention provides a high-temperature resistant, low-loss adhesive film, which is obtained by compounding a resin film and quartz cloth. By mass, the resin film is prepared by suspension polymerization of raw materials comprising the following components: 60-100 parts of nitrile resin, 1-5 parts of low-viscosity heterocyclic resin, 1-10 parts of the cage-type toughening agent described in the above technical solution or the cage-type toughening agent prepared by the preparation method described in the above technical solution, 0.1-0.5 parts of accelerator, and 0.5-5 parts of filler.

[0023] Preferably, the nitrile resin includes one or more of the following: resorcinol-type nitrile resin, bisphenol F-type nitrile resin, bisphenol S-type nitrile resin, bisphenol A-type nitrile resin, biphenyl-type nitrile resin, allyl bisphenol A-type nitrile resin, dimethylsilane nitrile resin, and triazine nitrile resin.

[0024] Preferably, the low-viscosity heterocyclic resin includes one or more of trimethoxysilyne resin, triarylsilyne resin, bisphenol E cyanate resin, and anthraquinone-containing allyl compounds.

[0025] Preferably, the promoter comprises one or more of organotransition metal compounds, imidazole compounds, and urea derivatives.

[0026] Preferably, the filler comprises one or more of silicon micro powder, silicon carbide, alumina, and calcium sulfate whiskers.

[0027] This invention also provides a method for preparing the high-temperature resistant, low-loss adhesive film described in the above technical solution, comprising the following steps:

[0028] (1) After mixing acrylonitrile resin, low viscosity heterocyclic resin, cage toughening agent, accelerator and filler, the mixture is pressed into a film to obtain a resin film.

[0029] (2) The resin film obtained in step (1) is molded and laminated with quartz cloth to obtain a high-temperature resistant and low-loss adhesive film.

[0030] This invention provides a cage-like toughening agent, prepared by suspension polymerization from raw materials comprising the following components in parts by mass: 10-95 parts of active-terminated polyimide, 1-5 parts of epoxy-based cage-like silsesquioxane, 0.1-0.5 parts of catalyst, 0.01-0.10 parts of dispersant, 500-1000 parts of organic solvent, and 1000-2000 parts of deionized water. This invention uses active-terminated polyimide and epoxy-based cage-like silsesquioxane (POSS) as monomers for preparing the cage-like toughening agent. A catalyst promotes the reaction of the monomers, an organic solvent dissolves the monomers to form droplets containing dissolved monomers, and a dispersant is used to disperse the droplets formed by the monomers and organic solvent. With deionized water as the continuous phase, the cage-like toughening agent can be obtained through suspension polymerization. The cage-type toughening agent provided by this invention uses POSS as the core and a shell of high-temperature resistant thermoplastic polyimide resin with active end groups. POSS provides high temperature resistance, flame retardancy, and low moisture absorption. The polyimide layer provides primary toughening, and POSS provides secondary toughening, thus having a dual toughening effect. Furthermore, this cage-type toughening agent has good solubility and interfacial bonding, and can be matched with nitrile resins, making it suitable as a toughening agent for nitrile resins. Because the toughening agent provided by this invention has good bonding between the core and shell particles, it enhances the synergistic toughening effect of both. The results of the examples show that, compared with the nitrile resin toughened by traditional thermoplastic polyimide resin alone, the impact toughness of the film obtained after using the toughening agent provided by this invention is increased by about 130%. Furthermore, when the toughening agent provided by this invention is used to prepare the film, the film can be cured at a temperature below 250°C with a degree of curing of more than 90%, a room temperature shear strength ≥10MPa, a 480°C shear strength ≥5MPa, a dielectric constant ≤3.1, and a dielectric loss ≤0.011, exhibiting excellent high temperature resistance, toughness, and low loss. Attached Figure Description

[0031] Figure 1 A photograph of the cage-type toughening agent prepared in Example 1 of this invention;

[0032] Figure 2 TEM image of the cage-type toughening agent prepared in Example 1 of this invention;

[0033] Figure 3 A photograph of the high-temperature resistant, low-loss adhesive film prepared in Example 2 of this invention;

[0034] Figure 4 The thermogravimetric curve of the high-temperature resistant, low-loss adhesive film prepared in Example 1 of the present invention. Detailed Implementation

[0035] This invention provides a cage-type toughening agent, which is prepared by suspension polymerization from raw materials comprising the following components in parts by mass: 10-95 parts of active end-group polyimide, 1-5 parts of epoxy-based cage-type silsesquioxane, 0.1-0.5 parts of catalyst, 0.01-0.10 parts of dispersant, 500-1000 parts of organic solvent, and 1000-2000 parts of deionized water.

[0036] Unless otherwise specified, all reagents used in this invention are commercially available products well known to those skilled in the art.

[0037] The raw materials for preparing the cage-type toughening agent of the present invention, by weight, include 10-95 parts, preferably 30-60 parts, of an active end-group polyimide. In the present invention, the active end-group polyimide preferably includes one or more compounds as shown in Formulas I to V:

[0038]

[0039] In this invention, in formulas I to V, R is independently preferably CH3, CH2CH3, or benzyl; n is independently preferably 10 to 30, more preferably 15 to 20; in formula V, x is preferably 5 to 20, more preferably 5 to 15, y is preferably 5 to 20, more preferably 5 to 15, and x+y is preferably 10 to 30, more preferably 15 to 20. In this invention, the active end-group polyimide can improve the toughness and high-temperature resistance of cyano resin. When the active end-group polyimide is of the above type, the prepared toughening agent can further improve the toughness and high-temperature resistance of cyano resin. This invention does not specifically limit the source of the active end-group polyimide; commercially available products or self-made products well known to those skilled in the art can be used. In this invention, the preferred commercial channels for the active end-group polyimide are the Changchun Institute of Applied Chemistry, General Electric (GE), and the Beijing Institute of Chemistry.

[0040] In this invention, the polyimide with active end groups of Formula I is preferably prepared by suspension polymerization from raw materials comprising the following components: 50-70 parts of 4,4'-diaminodiphenyl ether ODA, 50-100 parts of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride (OPDA), 10-20 parts of concentrated ammonia, 500-1000 parts of organic solvent, 200-400 parts of acetic anhydride, 60-120 parts of triethylamine, 2000-5000 parts of anhydrous ethanol, 1-3 parts of solid alkali, and 5-15 parts of end-capping agent.

[0041] In this invention, the organic solvent preferably includes one or more of dimethylformamide, dimethylacetamide, and dimethyl sulfoxide; the end-capping agent is preferably R3SiCH2Cl; and the solid base is preferably sodium hydroxide.

[0042] In this invention, the method for preparing the polyimide with active end groups of Formula I preferably includes the following steps:

[0043] (1) Dissolve ODA in an organic solvent to obtain an ODA solution, add OPDA to the ODA solution, and react at 0℃~5℃ for 8~12h. After the reaction is completed, remove water vapor under vacuum at room temperature to obtain polyimide, store it in a gas-tight container, and refrigerate it for later use.

[0044] (2) The mixture of acetic anhydride and triethylamine is dried to remove water, and the resulting mixture of acetic anhydride and triethylamine is sealed for later use; the drying and water removal method is preferably a molecular sieve or recrystallization method;

[0045] (3) Thaw the polyimide acid obtained in step (1) to room temperature to 40°C, add the mixture of acetic anhydride and triethylamine prepared in step (2) in three portions, stir thoroughly, add the resulting solution to anhydrous ethanol, react for 12 hours to obtain a solid precipitate, wash the solid precipitate once with alcohol and three times with distilled water, filter it, dry the obtained solid material in an air environment at 90°C for 4 hours, and then place it in a vacuum oven at 250°C for 4 hours to obtain thermoplastic polyimide containing anhydride end groups, and seal it in a vacuum container for later use.

[0046] (4) The thermoplastic polyimide containing anhydride end groups obtained in step (3) is dissolved again in an organic solvent. Weighed concentrated ammonia and solid alkali are added in three portions. The reaction is carried out for 4 to 6 hours. The temperature is raised to 60 to 80°C and then weighed end-capping agent is added. The reaction is carried out for 4 to 8 hours. After the reaction is completed, the reactants are post-treated to remove the solvent, dried and sieved to obtain a solid thermoplastic polyimide copolymer containing hydroxyl and silicon elements.

[0047] The raw materials for preparing the cage-like toughening agent of the present invention include 1 to 5 parts, preferably 2 to 4 parts, of an epoxy-based cage-like silsesquioxane, based on a mass of 10 to 95 parts of the active end-group polyimide. In the present invention, the preferred structural formula of the epoxy-based cage-like silsesquioxane is shown in Formula VI:

[0048] In this invention, R is...

[0049]

[0050]

[0051] In this invention, the epoxy-based cage-type silsesquioxane has a cage-like structure, which has good high-temperature resistance, flame retardancy and low moisture absorption. When the epoxy-based cage-type silsesquioxane has the above-mentioned structure, the toughening agent prepared can further improve the toughness and high-temperature resistance of cyano resin.

[0052] The raw materials for preparing the cage-like toughening agent of the present invention include 0.1 to 0.5 parts of catalyst, preferably 0.2 to 0.4 parts, based on 10 to 95 parts by mass of the active terminal polyimide. In the present invention, the catalyst is preferably an imidazole compound, which preferably includes one or more organophosphorus compounds, polyether amines, and tertiary amines, more preferably 2,4-imidazole and / or 3-phenylphosphine. In the present invention, the catalyst can initiate a reaction between the active terminal polyimide and the epoxy-based cage-like silsesquioxane, thereby forming a core-shell structure with POSS as the core and an epoxy-based cage-like silsesquioxane as the shell.

[0053] The raw materials for preparing the cage-type toughening agent of the present invention include 0.01 to 0.10 parts of dispersant, preferably 0.2 to 0.5 parts, based on 10 to 95 parts by mass of the active end-group polyimide. In the present invention, the dispersant preferably includes one or more of polyvinyl alcohol, calcium carbonate, magnesium carbonate, barium sulfate, sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and hexadecyl alcohol, more preferably one or more of polyvinyl alcohol, calcium carbonate, and sodium dodecyl sulfate. In the present invention, when preparing the cage-type toughening agent by suspension polymerization, the dispersant can disperse droplets. When the dispersant is of the type described above, it can fully disperse the droplets and prevent droplet aggregation.

[0054] The raw materials for preparing the cage-like toughening agent of the present invention, based on 10-95 parts by mass of the active-terminated polyimide, include 500-1000 parts, preferably 600-800 parts, of an organic solvent. In the present invention, the organic solvent preferably includes one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and chlorobenzene. In the present invention, the organic solvent can dissolve and provide the necessary reagent environment for the polymerization reaction of the active-terminated polyimide and the epoxy-based cage-like silsesquioxane to form the cage-like toughening agent; when the organic solvent is of the above type, it can promote the full progress of the polymerization reaction.

[0055] The raw materials for preparing the cage-like toughening agent of the present invention include 1000-2000 parts, preferably 1500-2000 parts, of deionized water, based on 10-95 parts by mass of the active end-group polyimide. In the present invention, the deionized water serves as a solvent and can act as a continuous phase in the preparation of the cage-like toughening agent by suspension polymerization.

[0056] The cage-type toughening agent provided by this invention uses POSS as the core and a shell of high-temperature resistant thermoplastic polyimide resin with active end groups. POSS provides high temperature resistance, flame retardancy, and low moisture absorption. The polyimide layer provides primary toughening, and POSS provides secondary toughening, thus having a dual toughening effect. Furthermore, this cage-type toughening agent has good solubility and interfacial bonding, and can be matched with nitrile resins, making it suitable as a toughening agent for nitrile resins.

[0057] The present invention also provides a method for preparing the cage-type toughening agent described in the above technical solution, comprising: mixing an active end-group polyimide, an epoxy-based cage-type silsesquioxane, a dispersant, a portion of an organic solvent and deionized water and then stirring at high speed to obtain a suspension;

[0058] The remaining organic solvent and catalyst are mixed to obtain a catalyst solution;

[0059] The catalyst solution is added dropwise to the suspension to carry out a polymerization reaction, thereby obtaining a cage-type toughening agent.

[0060] This invention involves mixing an active end-group polyimide, an epoxy-based cage-type silsesquioxane, a dispersant, a portion of an organic solvent, and deionized water, followed by high-speed stirring to obtain a suspension.

[0061] This invention does not specifically limit the method of mixing the active-terminated polyimide, epoxy-coated silsesquioxane, dispersant, a portion of the organic solvent, and deionized water, as long as the above components are fully dissolved to form a mixed solution. In this invention, the preferred method of mixing the active-terminated polyimide, epoxy-coated silsesquioxane, dispersant, a portion of the organic solvent, and deionized water includes: mixing the active-terminated polyimide, epoxy-coated silsesquioxane, and a portion of the organic solvent at 40–60°C to obtain a transparent solution; and mixing the transparent solution with the dispersant and deionized water. In this invention, when the active-terminated polyimide, epoxy-coated silsesquioxane, dispersant, a portion of the organic solvent, and deionized water are mixed using the above method, the components can be fully dissolved and uniformly mixed.

[0062] The present invention does not impose a particular limitation on the amount of the organic solvent used; it can be adjusted as needed. In the present invention, the organic solvent is preferably 4 / 5 of the total weight of the organic solvent.

[0063] In this invention, the speed of the high-speed stirring is preferably 2000–5000 r / min, more preferably 3000–4000 r / min. When the high-speed stirring speed is within the above range, droplet microspheres can be formed in the solution system obtained by mixing, thereby obtaining a suspension. This invention does not have a particular limitation on the high-speed stirring time, as long as it enables the solution system to form a suspension with uniform droplet distribution.

[0064] In this invention, the high-speed stirring is preferably carried out in a nitrogen atmosphere. The nitrogen atmosphere prevents the oxidation of the active-terminated polyimide and the epoxy-based cage-like silsesquioxane.

[0065] The present invention mixes the remaining organic solvent and the catalyst to obtain a catalyst solution.

[0066] The present invention does not have any particular limitation on the method of mixing the remaining organic solvent and the catalyst, as long as the catalyst can be dissolved in the organic solvent.

[0067] After obtaining the suspension and the catalyst solution, the present invention adds the catalyst solution dropwise to the suspension to carry out a polymerization reaction, thereby obtaining a cage-type toughening agent.

[0068] Preferably, the suspension is first heated to 90-95°C, and then the catalyst solution is added dropwise to the suspension. In this invention, heating the suspension to 90-95°C before adding the catalyst solution allows the catalyst to react with the polyimide end groups during the dropwise addition process, i.e., a polymerization reaction, thereby shortening the polymerization time and ensuring the polymerization reaction proceeds fully.

[0069] In this invention, the dropping rate is preferably 0.02 to 0.2 mL / s, more preferably 0.05 mL / s. When the dropping rate is within the above range, it prevents the reaction from becoming too violent due to an excessively rapid dropping rate.

[0070] After the addition of the catalyst solution is completed, the system obtained by adding the catalyst solution is kept at a certain temperature to continue the polymerization reaction. In this invention, the temperature for keeping the system at a certain temperature is preferably 90-95°C, more preferably 92-95°C, and the time for keeping the system at a certain temperature is preferably 4-8 hours, more preferably 6-8 hours. In this invention, when the temperature and time for keeping the system are within the above ranges, the polymerization reaction can proceed fully.

[0071] In this invention, the polymerization reaction is preferably carried out under a nitrogen atmosphere. The nitrogen atmosphere prevents the polymerization products from being oxidized, thereby improving the purity of the cage-type toughening agent.

[0072] Preferably, the system obtained after the polymerization reaction is subjected to sequential cooling to 60°C, washing, vacuum drying, cooling grinding, dispersion, and screening to obtain a cage-like toughening agent. The present invention does not impose any particular limitation on the methods for washing, vacuum drying, cooling grinding, dispersion, and screening; methods well known to those skilled in the art can be used.

[0073] This invention prepares cage-type toughening agents by suspension polymerization. This method has good heat dissipation and stable reaction, which can make the molecular weight distribution of the obtained polymer relatively uniform, thereby obtaining cage-type toughening agents with high purity, which have good solubility and interfacial bonding properties and can be matched with nitrile resins.

[0074] The present invention also provides a high-temperature resistant and low-loss adhesive film, which is obtained by compounding a resin film and a quartz cloth. By mass, the resin film is prepared from raw materials comprising the following components: 60-100 parts of nitrile resin, 1-5 parts of low-viscosity heterocyclic resin, 1-10 parts of the cage-type toughening agent described in the above technical solution or the cage-type toughening agent prepared according to the preparation method described in the above technical solution, 0.1-0.5 parts of accelerator, and 0.5-5 parts of filler.

[0075] In this invention, the high-temperature resistant, low-loss adhesive film is obtained by laminating a resin film and quartz cloth. This invention does not specify the type of quartz cloth; any commercially available product well-known to those skilled in the art can be used. In this invention, the thickness of the quartz cloth is preferably 0.10–0.20 mm. In this invention, the quartz cloth serves as the carrier of the high-temperature resistant, low-loss adhesive film, supporting the resin film.

[0076] In this invention, the mass of the resin film is preferably 50-70% of the mass of the high-temperature resistant, low-loss adhesive film, more preferably 60-70%. When the mass content of the resin film is within the above range, it is more advantageous for the high-temperature resistant, low-loss adhesive film to have higher heat resistance during application.

[0077] The raw materials for preparing the resin film of the present invention, by weight, include 60-100 parts of nitrile resin, preferably 80-90 parts. In the present invention, the nitrile resin preferably includes one or more of resorcinol-type nitrile resin, bisphenol F-type nitrile resin, bisphenol S-type nitrile resin, bisphenol A-type nitrile resin, biphenyl-type nitrile resin, allyl bisphenol A-type nitrile resin, dimethylsilane nitrile resin, and triazine nitrile resin; more preferably, it includes one or more of bisphenol A-type nitrile resin, resorcinol-type nitrile resin, and bisphenol F-type nitrile resin. In the present invention, the nitrile resin has high heat resistance stability. When the nitrile resin is of the above-mentioned type, it has good heat resistance stability, which is more conducive to obtaining a film with high heat resistance and low loss.

[0078] The raw materials for preparing the resin film of the present invention include 1 to 5 parts, preferably 2 to 4 parts, of a low-viscosity heterocyclic resin, based on a mass fraction of 60 to 100 parts of nitrile resin. In the present invention, the low-viscosity heterocyclic resin preferably includes one or more of trimethoxysilyne resin, triarylsilyne resin, bisphenol E cyanate resin, and anthraquinone-containing allyl compounds, more preferably trimethoxysilyne resin or triarylsilyne resin. In the present invention, the low-viscosity heterocyclic resin can reduce the eutectic viscosity of the nitrile resin system, which is beneficial to the improvement of mechanical properties, film-forming properties, etc. When the low-viscosity heterocyclic resin is of the above type, the viscosity is below 30,000 cp, exhibiting a low viscosity.

[0079] The raw materials for preparing the resin film of the present invention include 1 to 10 parts, preferably 5 to 10 parts, of a cage-type toughening agent, based on 60 to 100 parts by weight of the nitrile resin. In the present invention, the cage-type toughening agent is the cage-type toughening agent described in the above-mentioned technical solution. In the present invention, the cage-type toughening agent has a POSS core and a shell of a high-temperature resistant thermoplastic polyimide resin with active end groups. The POSS provides high-temperature resistance, flame retardancy, and low moisture absorption; the polyimide layer provides primary toughening, and the POSS provides secondary toughening, thus having a dual toughening effect; furthermore, this cage-type toughening agent has good solubility and interfacial bonding properties, and can be matched with the nitrile resin, making it suitable as a toughening agent for the nitrile resin.

[0080] The raw materials for preparing the resin film of the present invention include 0.1 to 0.5 parts, preferably 0.3 to 0.5 parts, of an accelerator, based on 60 to 100 parts by weight of the nitrile resin. In the present invention, the accelerator preferably includes one or more of organotransition metal compounds, imidazole compounds, and urea derivatives. More preferably, the organotransition metal compounds include dibutyltin dilaurate, n-butyllithium, acetylated ferrocene, iron acetylacetonate, or cobalt acetylacetonate; the imidazole compounds preferably include dimethylimidazolium, dimethyltetraethylimidazolium, 1-phenyl-2-methylimidazolium, 1-cyanoethyl-2-methylimidazolium, or 2-methylimidazolium azazine complex; the urea derivatives preferably include 1,3-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, or 3-(3,4-dichlorophenyl)-1,1-dimethylurea. In this invention, the accelerator can reduce the curing temperature of the nitrile resin; when the accelerator is of the type described above, the curing temperature of the nitrile resin can be reduced to below 250°C.

[0081] The raw materials for preparing the resin film of the present invention, based on 60-100 parts by weight of the nitrile resin, include 0.5-5 parts, preferably 2-5 parts, of filler. In the present invention, the filler preferably includes one or more of silicon micropowder, silicon carbide, alumina, and calcium sulfate whiskers. The present invention does not have a particular limitation on the particle size of the filler; commercially available products well known to those skilled in the art can be used. In the present invention, the filler can alleviate the concentrated exothermic effect, control the flow of the adhesive, improve processability, and increase thermal conductivity, thereby facilitating a reduction in the curing temperature of the nitrile resin.

[0082] The cage-type toughening agent in the high-temperature resistant and low-loss adhesive film provided by this invention can be matched with the nitrile resin, thereby improving the heat resistance and toughness of the nitrile resin-based adhesive film.

[0083] This invention also provides a method for preparing the high-temperature resistant, low-loss adhesive film described in the above technical solution, comprising the following steps:

[0084] (1) A resin film is obtained by mixing acrylonitrile resin, low viscosity heterocyclic resin, cage toughening agent, accelerator and filler and then pressing the mixture.

[0085] (2) The resin film obtained in step (1) is molded and laminated with quartz cloth to obtain a high-temperature resistant and low-loss adhesive film.

[0086] This invention involves mixing nitrile resin, low-viscosity heterocyclic resin, cage-type toughening agent, accelerator, and filler, followed by lamination to obtain a resin film.

[0087] This invention does not specifically limit the method of mixing the nitrile resin, low-viscosity heterocyclic resin, cage-type toughening agent, accelerator, and filler. Any mixing method well-known to those skilled in the art can be used to ensure uniform mixing of the components. In this invention, the preferred method of mixing the nitrile resin, low-viscosity heterocyclic resin, cage-type toughening agent, accelerator, and filler includes: melting the nitrile resin and low-viscosity heterocyclic resin to obtain a molten liquid; adding the cage-type toughening agent to the molten liquid in three portions to obtain a main resin; and mixing the main resin with the accelerator and filler. In this invention, when the above method is used to mix the nitrile resin, low-viscosity heterocyclic resin, cage-type toughening agent, accelerator, and filler, the components can be thoroughly and uniformly mixed.

[0088] In this invention, nitrile resin and low-viscosity heterocyclic resin are melted to obtain a melt, and the cage-type toughening agent is added to the melt in three portions to obtain the main resin.

[0089] In this invention, the melting is preferably carried out at 150-160°C. This invention does not have a special limitation on the melting time, as long as the nitrile resin and the low viscosity heterocyclic resin can be fully melted.

[0090] In this invention, when the cage-type toughening agent is added in three parts, the amount added each time is not particularly limited, and can be adjusted according to the dispersion of the cage-type toughening agent.

[0091] In this invention, the melting and addition of the cage-type toughening agent are preferably carried out under stirring, and the stirring speed is preferably 1000-3000 r / min, more preferably 1500-2000 r / min. In this invention, the stirring can promote better and more uniform mixing of the components.

[0092] In this invention, the cage-type toughening agent is added to the molten liquid in three portions, and then stirring is continued for 1 to 5 hours. In this invention, the stirring promotes the full dispersion of the cage-type toughening agent.

[0093] In this invention, the main resin is preferably mixed with an accelerator and a filler. In this invention, the method of mixing the main resin with the accelerator and filler preferably includes cooling the main resin to 20–40°C and mixing it under stirring. This invention does not have a particular limitation on the mixing method, as long as it can fully mix the accelerator and filler into the main resin.

[0094] In this invention, the film pressing temperature is preferably 70–90°C, more preferably 80–90°C. This invention does not specifically limit the film pressing time; it can be adjusted as needed to form a uniform resin film from the mixed system. This invention does not specifically limit the film pressing apparatus; any film pressing apparatus well known to those skilled in the art can be used. In this invention, the film pressing apparatus is preferably a film pressing machine.

[0095] The present invention does not impose any special limitation on the thickness of the resin film; it can be adjusted as needed.

[0096] After obtaining the resin film, the present invention performs molding composite of the resin film and quartz cloth to obtain a high-temperature resistant and low-loss adhesive film.

[0097] The present invention does not specifically limit the method for molding the resin film and quartz cloth together; any molding method well known to those skilled in the art can be used. In the present invention, the molding process can combine the resin film and quartz cloth to form an adhesive film.

[0098] This invention obtains a resin film by mixing acrylonitrile resin, low viscosity heterocyclic resin, cage toughening agent, accelerator and filler. The cage toughening agent can improve the toughness and heat resistance of the acrylonitrile resin, so that the obtained film has excellent toughness and high temperature resistance.

[0099] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0100] Example 1

[0101] A cage-like toughening agent, by weight, is prepared by suspension polymerization from the following raw materials: 95 parts of active-terminated polyimide, 5 parts of epoxy-based cage-like silsesquioxane, 0.2 parts of 2,4-imidazole catalyst, 0.3 parts of 3-phenylphosphine catalyst, 0.05 parts of polyvinyl alcohol dispersant, 0.05 parts of calcium carbonate dispersant, 500 parts of dimethylformamide organic solvent, and 1000 parts of deionized water.

[0102] The structural formula of the active end-group polyimide is as follows:

[0103]

[0104] Where n is 10; R is methyl;

[0105] The structural formula of epoxy-based cage-type silsesquioxanes is:

[0106] ;

[0107] Where R is .

[0108] The preparation method of the above-mentioned cage-type toughening agent includes the following steps:

[0109] Active terminal polyimide, epoxy cage-type silsesquioxane and 400 parts of organic solvent were mixed at 60°C to obtain a transparent solution; the transparent solution was mixed with a dispersant and deionized water, nitrogen gas was introduced, and high-speed stirring was started at 2000 r / min until the mixture formed droplet microbeads to obtain a suspension;

[0110] The remaining 100 parts of organic solvent and catalyst were mixed to obtain a catalyst solution;

[0111] The suspension was heated to 95°C, and the catalyst solution was added dropwise to the suspension at a rate of 0.05 mL / s. After the addition was complete, the temperature was maintained at 95–100°C for 8 hours. After the reaction was complete, the temperature was lowered to 60°C, and the nitrogen protection was turned off. After washing, solvent removal, vacuum drying, cooling, grinding, dispersion, and screening, a light yellow powder, namely the cage-type toughening agent, was obtained.

[0112] Actual photos of cage-type toughening agents are shown below. Figure 1As shown; the cage-like toughening agent prepared in this embodiment was observed using a transmission electron microscope (TEM), and the TEM image is shown below. Figure 2 As shown. From Figure 2 It can be seen that the cage-type toughening agent prepared in this embodiment has a core-shell structure.

[0113] Example 2

[0114] A high-temperature resistant, low-loss adhesive film is obtained by compounding a resin film and a quartz cloth, wherein the thickness of the quartz cloth is 0.1 mm and the mass of the resin film is 65% of the mass of the high-temperature resistant, low-loss adhesive film.

[0115] The resin film, by weight, is prepared from the following raw materials: 85 parts of bisphenol A type nitrile resin, 5 parts of trimethoxysilyl yne resin, 10 parts of the cage-type toughening agent prepared in Example 1, 0.5 parts of cobalt acetylacetonate accelerator, and 5 parts of silicon carbide filler.

[0116] The preparation method of the above-mentioned high-temperature resistant and low-loss adhesive film includes the following steps:

[0117] (1) The nitrile resin and the low viscosity heterocyclic resin are heated to 170°C, stirred and melted at a stirring rate of 1500 r / min to obtain a molten liquid. The cage toughening agent is added to the molten liquid in three portions and stirred for 5 hours to obtain the main resin. The main resin is cooled to 40°C, mixed with accelerator and filler under stirring, and then pressed at 90°C using a film press to obtain a resin film.

[0118] (2) The resin film obtained in step (1) is molded and laminated with quartz cloth to obtain a high-temperature resistant and low-loss adhesive film.

[0119] The actual image of the high-temperature resistant, low-loss adhesive film prepared in this embodiment is shown below. Figure 3 As shown.

[0120] Test Example 1

[0121] The high-temperature resistant and low-loss adhesive film prepared in Example 2 was cured. The curing process was as follows: (150±5℃) / 1h + (250±5℃) / 4h; pressure 0.2~0.4MPa, heating rate 1~3℃ / min; after curing, it was cooled to below 60℃.

[0122] The high-temperature resistant, low-loss adhesive film was prepared, and the tensile shear test specimens were carbon steel pieces that had undergone sandblasting and degreasing treatment. The tensile shear strength at -55℃ and the room tensile shear strength were tested according to the relevant provisions of HB5164-1981 "Test Method for Tensile Shear Strength of Adhesive Bonds in Metals". The shear strength at 250℃, 400℃, and 480℃ was tested according to the relevant provisions of GJB444-1988 "Test Method for High-Temperature Tensile Shear Strength of Adhesives (Metal to Metal)". The flame retardancy of the adhesive film material was tested according to the relevant content of ANSI / UL-94-1985 "American Flame Retardant Materials Standard". The dielectric properties were tested using the resonant cavity method at a frequency of 10 GHz, and the thermogravimetric analysis (TGA) method was used. The thermogravimetric curve of the resin film in the high-temperature resistant, low-loss adhesive film is shown below. Figure 4 As shown in Table 1, the high and low temperature mechanical and physical properties of the resin film in the obtained high-temperature resistant and low-loss adhesive film are shown in Table 1.

[0123] Table 1. Performance test results of the resin film in the high-temperature resistant, low-loss adhesive film prepared in Example 2.

[0124]

[0125] As can be seen from Table 1, the resin film in the high-temperature resistant and low-loss adhesive film prepared in Example 2 has excellent high-temperature resistance and low-loss properties.

[0126] Example 3

[0127] A cage-type toughening agent, differing from Example 1 in that the structure of the active end-group polyimide is:

[0128]

[0129] Where n is 10 and R is ethyl.

[0130] The remaining components are the same as in Example 1.

[0131] The preparation method of the above-mentioned cage-type toughening agent includes the following steps:

[0132] Active terminal polyimide, epoxy cage-type silsesquioxane and 400 parts of organic solvent were mixed at 60°C to obtain a transparent solution; the transparent solution was mixed with a dispersant and deionized water, nitrogen gas was introduced, and high-speed stirring was started at 2000 r / min until the mixture formed droplet microbeads to obtain a suspension;

[0133] The remaining 100 parts of organic solvent and catalyst were mixed to obtain a catalyst solution;

[0134] The suspension was heated to 95°C, and the catalyst solution was added dropwise to the suspension at a rate of 0.05 mL / s. After the addition was complete, the temperature was maintained at 95–100°C for 8 hours. After the reaction was complete, the temperature was lowered to 60°C, and the nitrogen protection was turned off. After washing, solvent removal, vacuum drying, cooling, grinding, dispersion, and screening, a light yellow powder, namely the cage-type toughening agent, was obtained.

[0135] Example 4

[0136] A high-temperature resistant, low-loss adhesive film and its preparation method are disclosed. The difference between this and Example 2 is that the cage-type toughening agent used is the cage-type toughening agent prepared in Example 3, while the remaining steps are the same as in Example 2.

[0137] Test Example 2

[0138] The high-temperature resistant, low-loss adhesive film prepared in Example 4 was tested using the method described in Test Example 1. The high and low temperature mechanical and physical properties of the resin film in the high-temperature resistant, low-loss adhesive film are shown in Table 2.

[0139] Table 2. Performance test results of the resin film in the high-temperature resistant, low-loss adhesive film prepared in Example 4.

[0140]

[0141] A comparison of Tables 1 and 2 shows that the main repeating unit of the self-made cage-type toughening particles adopts a phenyl ether structure, and the strength of the film at 480℃ decreases by about 15%. This indicates that the change in the molecular structure of the self-made cage-type toughening particles has a significant impact on the heat resistance of the film, but has little impact on other properties such as durability and dielectric properties.

[0142] Comparative Example 1

[0143] The preparation method of the high temperature resistant and low loss adhesive film differs from that of Example 2 in that commercially available thermoplastic polyimide resin is used to replace the cage toughening agent, while the remaining steps are the same as those in Example 2.

[0144] The structural formula of commercially available thermoplastic polyimide resin is as follows:

[0145]

[0146] Test Example 3

[0147] The high-temperature resistant, low-loss adhesive film prepared in Comparative Example 1 was tested using the method described in Test Example 1. The high- and low-temperature mechanical and physical properties of the resin film in the high-temperature resistant, low-loss adhesive film are shown in Table 3.

[0148] Table 3. Performance test results of the resin film in the high-temperature resistant, low-loss adhesive film prepared in Comparative Example 1.

[0149]

[0150] Table 4 shows a comparison of the properties of Example 1, Comparative Example 1, and commercially available high-temperature resistant adhesives:

[0151] Table 4. Comparison of the performance of Example 1, Comparative Example 1, and commercially available high-temperature resistant adhesives.

[0152]

[0153] As shown in Table 4, the film prepared by modifying nitrile resin with general-purpose thermoplastic polyimide resin exhibits a strength decrease of approximately 100% at 480℃, making it impossible to test the strength value. This indicates that the self-synthesized cage-like toughening particles are a key toughening material for the film when applied under 480℃ load.

[0154] The test results above show that the cage-type toughening agent provided by the present invention can significantly improve the high temperature resistance and toughness of the film when used as a toughening agent for nitrile resin. This indicates that the cage-type toughening agent provided by the present invention is applicable to nitrile resin-based composite materials and can significantly improve the heat resistance stability of the film, resulting in a film with high temperature resistance, low loss and high toughness.

[0155] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cage-type toughening agent, prepared by suspension polymerization from raw materials comprising the following components in parts by mass: 10-95 parts of active end-group polyimide, 1-5 parts of epoxy-based cage-type silsesquioxane, 0.1-0.5 parts of catalyst, 0.01-0.10 parts of dispersant, 500-1000 parts of organic solvent and 1000-2000 parts of deionized water; The active terminal polyimide comprises one or more compounds as shown in Formulas I to V: ； In formulas I to V, R is independently CH3, CH2CH3 or benzyl, and n is independently 10 to 30. In the formula V, x is 5~20, y is 5~20, and x+y is 10~30; The structural formula of the epoxy-based cage-type silsesquioxane is shown in Formula VI: ； In equation VI, R is or ; The preparation method of the cage-type toughening agent includes: A suspension was obtained by mixing active end-group polyimide, epoxy cage-type silsesquioxane, dispersant, some organic solvent and deionized water and then stirring at high speed. The remaining organic solvent and catalyst are mixed to obtain a catalyst solution; The catalyst solution is added dropwise to the suspension to carry out a polymerization reaction, thereby obtaining a cage-type toughening agent; The cage-type toughening agent has a core-shell structure, with an epoxy-based cage-type silsesquioxane as the core and an active-terminated polyimide as the shell. The core and shell are connected by chemical bonding between the active-terminated groups and the epoxy groups.

2. The method for preparing the cage-type toughening agent according to claim 1, comprising: Active end A suspension was obtained by mixing polyimide, epoxy-based cage-type silsesquioxane, dispersant, some organic solvent and deionized water and stirring at high speed. The remaining organic solvent and catalyst are mixed to obtain a catalyst solution; The catalyst solution is added dropwise to the suspension to carry out a polymerization reaction, thereby obtaining a cage-type toughening agent.

3. A high-temperature resistant, low-loss adhesive film, obtained by compounding a resin film and quartz cloth, wherein, by mass parts, the resin film is prepared from raw materials comprising the following components: 60-100 parts of nitrile resin, 1-5 parts of low-viscosity heterocyclic resin, 1-10 parts of the cage-type toughening agent as described in claim 1 or the cage-type toughening agent prepared by the preparation method described in claim 2, 0.1-0.5 parts of accelerator, and 0.5-5 parts of filler.

4. The high-temperature resistant, low-loss adhesive film according to claim 3, characterized in that, The nitrile resin includes one or more of the following: resorcinol-type nitrile resin, bisphenol F-type nitrile resin, bisphenol S-type nitrile resin, bisphenol A-type nitrile resin, biphenyl-type nitrile resin, allyl bisphenol A-type nitrile resin, dimethylsilane nitrile resin, and triazine nitrile resin.

5. The high-temperature resistant, low-loss adhesive film according to claim 3, characterized in that, The low-viscosity heterocyclic resin includes one or more of trimethoxysilyne resin, triarylsilyne resin, bisphenol E cyanate resin, and anthracycline-containing allyl compounds.

6. The high-temperature resistant, low-loss adhesive film according to claim 3, characterized in that, The promoters include one or more of organotransition metal compounds, imidazole compounds, and urea derivatives.

7. The high-temperature resistant, low-loss adhesive film according to claim 3, characterized in that, The filler includes one or more of silicon micropowder, silicon carbide, alumina, and calcium sulfate whiskers.

8. A method for preparing the high-temperature resistant, low-loss adhesive film according to any one of claims 3 to 7, comprising the following steps: (1) The nitrile resin, low viscosity heterocyclic resin, cage toughening agent, accelerator and filler are mixed and then pressed to obtain a resin film; (2) The resin film obtained in step (1) is molded and laminated with quartz cloth to obtain a high-temperature resistant and low-loss adhesive film.

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