FCCL adhesive and preparation method thereof

Abstract

The invention discloses an FCCL adhesive and a preparation method thereof. The FCCL adhesive comprises the following components in parts by weight: 30-50 parts of an epoxy resin base material selected from at least two mixtures of bisphenol A and F epoxy resins and novolac epoxy resins; 10-25 parts of an elastomer modifier, which is a blend of maleic anhydride grafted hydroxyl-terminated nitrile rubber and carboxy nitrile rubber; 5-20 parts of a latent curing component, wherein the latent curing component contains dicyandiamide, diaminodiphenyl sulfone and a microencapsulated imidazole accelerant; 8-18 parts of a nanometer composite reinforcing agent which is boehmite powder subjected to silane surface modification; 35-55 parts of a solvent component and 1.5-6 parts of a functional auxiliary agent. And the functional auxiliary agent contains a core-shell toughening agent and the like. The preparation method comprises the steps of elastomer modification, nano reinforcing agent treatment, core-shell toughening agent synthesis and the like. The peeling strength, the heat resistance, the elongation at break and the electrical insulating property of the adhesive are obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to an FCCL adhesive and a preparation method thereof. Background Art

[0002] In flexible copper-clad laminates (FCCLs), adhesives are the key connecting medium between the insulation layer and the copper foil, and require a variety of excellent properties. However, traditional epoxy resin-based adhesives face numerous technical bottlenecks.

[0003] In terms of toughness and interfacial compatibility, conventional epoxy resins are brittle after curing, and elastomer toughening can easily lead to phase separation. Furthermore, improper control of the elastomer's acid value and grafting ratio can affect the curing reaction and cause cross-linking network defects. Regarding the curing process, traditional latent curing systems require high temperatures and long curing times, while highly reactive curing agents can easily induce pre-curing or shorten the shelf life.

[0004] Regarding nanoreinforcements, unmodified nanoparticles like boehmite are prone to agglomeration, resulting in weak interfacial bonding, leading to stress concentration and performance degradation. Conventional solvent formulations have poor evaporation rates, impacting adhesive layer uniformity and adhesion. Coordinating toughening and heat resistance is also difficult, as traditional toughening agents significantly lower the glass transition temperature.

[0005] Existing technologies mostly focus on optimizing single components or simple compounding, making it difficult to systematically address the issue of improving overall performance. Therefore, there is an urgent need to develop new FCCL adhesives that achieve the desired combination of high bond strength, flexibility, high-temperature resistance, and process stability through molecular structure design, multi-scale interface regulation, and coordinated component optimization. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides an FCCL adhesive and a preparation method. The specific technical solution is: an FCCL adhesive comprises, by weight: 30-50 parts of an epoxy resin base material, 10-25 parts of an elastomer modifier, 5-20 parts of a latent curing component, 8-18 parts of a nanocomposite reinforcing agent, 35-55 parts of a solvent component, and 1.5-6 parts of a functional additive.

[0007] Preferably, the epoxy resin base material is selected from a mixture of at least two of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin, and its epoxy equivalent is 180-250 g / eq;

[0008] The elastomer modifier is a blend of maleic anhydride grafted modified hydroxyl-terminated nitrile rubber and carboxyl nitrile rubber, with a grafting rate of 1.5-3.8 wt % and an acid value controlled in the range of 35-45 mgKOH / g;

[0009] The latent curing component comprises a complex of dicyandiamide and diaminodiphenyl sulfone, the mass ratio of the two being 1:0.2-5, and the ratio of active hydrogen equivalent to epoxy equivalent being 0.9-1.1:1;

[0010] The nanocomposite reinforcing agent is boehmite powder surface-modified with γ-glycidyloxypropyltrimethoxysilane, with an average particle size of 30-80 nm and a specific surface area of ​​50-150 m 2 / g, surface silane loading is 1.2-3.5wt%;

[0011] The solvent component is composed of methyl ethyl ketone, cyclohexanone and gamma-butyrolactone in a volume ratio of 1:0.8-1.5:0.3-0.8;

[0012] The functional additives include an accelerator, an antioxidant and a core-shell toughening agent, wherein the core-shell toughening agent is polymethyl methacrylate / butyl acrylate rubber particles with a particle size distribution of 80-200 nm.

[0013] Preferably, the mass ratio of the hydroxy-terminated nitrile rubber to the carboxyl nitrile rubber in the elastomer modifier is 1:0.3-2.5, and the reaction temperature of the maleic anhydride graft modification is 85-120° C., and the reaction time is 2-5 hours.

[0014] Preferably, the surface modification of the nanocomposite reinforcing agent adopts an in-situ hydrolysis-condensation process, specifically comprising: dispersing boehmite powder in an ethanol-water mixture, adding a silane coupling agent, and performing a hydrolysis reaction at pH 4-6 for 1-3 hours, followed by aging at 60-80°C for 2-4 hours.

[0015] Preferably, the latent curing component further comprises 0.5-3 parts of an imidazole latent accelerator, wherein the imidazole latent accelerator is 2-phenylimidazoline or 2-ethyl-4-methylimidazole, and the accelerator is microencapsulated, and the capsule wall material is a polyurethane-acrylate copolymer.

[0016] Preferably, the preparation method of the core-shell toughening agent comprises: first synthesizing a polybutyl acrylate rubber core with a particle size of 50-100 nm by emulsion polymerization, then grafting a methyl methacrylate hard shell layer step by step by a gradient temperature increase method, and finally forming core-shell particles with a gradient modulus structure.

[0017] Preferably, the solvent component further contains 0.1-0.5 parts of a leveling control agent, which is a fluorine-containing acrylate copolymer with a molecular weight of 5000-20000 and a fluorine content of 8-15 wt%.

[0018] Preferably, the antioxidant in the functional additive is a complex of hindered phenols and phosphites, with a mass ratio of 1:0.5-2, and the composite antioxidant is adsorbed on a silica carrier, with a drug loading of 40-60%.

[0019] A method for preparing an FCCL adhesive comprises the following steps:

[0020] S1. Preparation of elastomer modifier: Mix hydroxyl-terminated nitrile rubber and carboxyl nitrile rubber in a mass ratio of 1:0.3-2.5, add maleic anhydride and carry out grafting reaction at 85-120° C. for 2-5 hours, control the grafting rate to 1.5-3.8 wt % and the acid value to 35-45 mgKOH / g;

[0021] S2. Nanocomposite reinforcing agent treatment: dispersing boehmite powder in an ethanol-water mixture, adding γ-glycidyloxypropyltrimethoxysilane, adjusting the pH to 4-6, performing a hydrolysis reaction for 1-3 hours, and aging at 60-80° C. for 2-4 hours to obtain a modified powder with a surface silane loading of 1.2-3.5 wt%;

[0022] S3. Synthesis of core-shell toughening agent: prepare polybutyl acrylate rubber core by emulsion polymerization, gradually increase the temperature to 80-95°C and graft methyl methacrylate shell layer in steps to form gradient modulus core-shell particles with a particle size of 80-200 nm;

[0023] S4. Latent curing component treatment: dicyandiamide and diaminodiphenyl sulfone are mixed in a mass ratio of 1:0.2-5, and a microencapsulated imidazole accelerator is added to control the ratio of active hydrogen equivalent to epoxy equivalent to 0.9-1.1:1;

[0024] S5. Preparation of glue: premix the epoxy resin base material and the product of step S1 in a solvent component at 40-60° C., add the products of steps S2-S4 and functional additives in sequence, disperse at high speed, and then filter. The solvent is used in a volume ratio of methyl ethyl ketone: cyclohexanone: γ-butyrolactone of 1:0.8-1.5:0.3-0.8.

[0025] Furthermore, in step S2, the mass ratio of boehmite powder to silane coupling agent is 100:1.5-4.5, and the ultrasonic power during the hydrolysis reaction is controlled at 200-400W;

[0026] The temperature gradient in step S3 includes: a first stage at 60-70°C to initiate core layer polymerization, a second stage at 75-85°C to form a transition layer, and a third stage at 90-95°C to complete shell grafting, with a temperature difference of ≥10°C / h in each stage;

[0027] The microencapsulation treatment in step S4 includes: reacting an imidazole accelerator with a polyurethane-acrylate copolymer monomer in an emulsification system to form microcapsules with a wall thickness of 0.1-0.5 μm by interfacial polymerization, a coverage rate of ≥85%, and a thermal decomposition starting temperature of ≥130° C.;

[0028] In step S5: in the premixing stage, the stirring rate is controlled to 800-1500 rpm, and the dispersion time is 30-60 min; the high-speed dispersion adopts the nano-sand milling process, and the particle size is controlled to D90≤500 nm; the leveling control agent is added in an atomized manner in the later stage of dispersion, and the temperature is maintained at 40±2°C.

[0029] The method for preparing nickel fiber provided by the present invention has the following beneficial effects:

[0030] 1. Solve the problems of brittleness and thermal stability: Adopt bisphenol A / F and phenolic epoxy resin compound system to make the adhesive have both high bonding strength and heat resistance, overcoming the defects of traditional epoxy adhesive such as high brittleness and insufficient thermal stability.

[0031] 2. Avoid interlayer delamination: The dicyandiamide / diaminodiphenyl sulfone composite curing system is combined with microencapsulated imidazole accelerator to form a three-level latent curing mechanism. The precise control of the curing active hydrogen equivalent ratio will reduce the curing shrinkage rate and solve the interlayer delamination problem.

[0032] 3. Improve toughness and dimensional stability: Maleic anhydride grafted onto nitrile rubber forms an "island structure" to enhance impact strength; core-shell toughening agents achieve stress gradient dispersion and improve fracture toughness; silane-modified boehmite nanoparticles enhance interfacial bonding, reduce the thermal expansion coefficient, improve brittleness, and enhance dimensional stability.

[0033] 4. Improve process adaptability: The solvent system regulates the volatilization gradient through hydrogen bonding, and is combined with a fluorine-containing leveling agent to reduce coating thickness deviation, shorten surface drying time, and improve process adaptability.

[0034] 5. Ensure long-term stability: Antioxidants are adsorbed on silica carriers to achieve sustained release protection, ensuring long-term stability.

[0035] 6. Green and environmentally friendly with extended storage period: The surface modification of boehmite adopts in-situ hydrolysis in an ethanol-water system to reduce VOC emissions; the microencapsulation technology enables zero migration of the accelerator at room temperature, and the storage period of the glue is extended, achieving green preparation and good storage performance. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0037] This embodiment provides an FCCL adhesive, which includes, by weight: 30-50 parts of an epoxy resin base material, 10-25 parts of an elastomer modifier, 5-20 parts of a latent curing component, 8-18 parts of a nanocomposite reinforcing agent, 35-55 parts of a solvent component, and 1.5-6 parts of a functional additive.

[0038] Furthermore, the epoxy resin base is selected from a mixture of at least two of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin, with an epoxy equivalent weight of 180-250 g / eq. The principle is as follows: bisphenol A epoxy resin provides basic bonding strength and chemical resistance; bisphenol F epoxy resin reduces system viscosity and improves flexibility; and novolac epoxy resin introduces multifunctional epoxy groups, increasing crosslinking density and heat resistance. The combination of these three achieves a balance of strength, flexibility, and temperature resistance. An epoxy equivalent weight of 180-250 g / eq ensures moderate reactivity and network integrity after curing.

[0039] The elastomer modifier is a blend of maleic anhydride-grafted hydroxyl-terminated nitrile rubber and carboxyl-terminated nitrile rubber, with a grafting ratio of 1.5-3.8% by weight and an acid value controlled within the range of 35-45 mgKOH / g. The principle is that the hydroxyl groups of the hydroxyl-terminated nitrile rubber (HTBN) and the carboxyl groups of the carboxyl-terminated nitrile rubber (X-NBR) synergistically participate in the epoxy curing reaction to form a chemically bonded toughening phase. Maleic anhydride grafting introduces anhydride groups, which react with epoxy groups to form ester bonds, strengthening the elastomer-resin interface. A grafting ratio of 1.5-3.8% balances toughening and phase separation, while an acid value of 35-45 mgKOH / g ensures sufficient reaction sites without causing excessive crosslinking.

[0040] The latent curing component comprises a complex of dicyandiamide and diaminodiphenyl sulfone in a mass ratio of 1:0.2-5, with an active hydrogen equivalent to epoxy equivalent ratio of 0.9-1.1:1. The principle is that dicyandiamide (DICY) acts as a high-temperature curing agent, combined with diaminodiphenyl sulfone (DDS) to create a step-curing profile: DDS initiates initial crosslinking at a lower temperature, while DICY completes the deep cure at a higher temperature. The active hydrogen to epoxy equivalent ratio of 0.9-1.1:1 ensures complete cure and avoids residual epoxy groups. Imidazole microencapsulation enables "timed release," and the polyurethane-acrylate wall material ruptures above 130°C to release the accelerator, precisely controlling the cure kinetics.

[0041] The nanocomposite reinforcing agent is boehmite powder surface-modified with γ-glycidyloxypropyltrimethoxysilane, with an average particle size of 30-80 nm and a specific surface area of ​​50-150 m 2 / g, with a surface silane loading of 1.2-3.5wt%; the principle is: boehmite (γ-AlOOH) nanosheets are surface-modified with γ-glycidyloxypropylsilane, and the epoxy groups react with the resin to form chemical bonds, thereby improving the efficiency of interfacial stress transfer. 2 High surface area optimizes filling effect and crack deflection ability. Silane loading of 1.2-3.5% balances dispersion stability and reinforcement efficiency.

[0042] The solvent composition consists of methyl ethyl ketone (MEK), cyclohexanone (Cyclohexanone), and gamma-butyrolactone (GBL) in a volume ratio of 1:0.8-1.5:0.3-0.8. The principle is that methyl ethyl ketone (MEK) provides rapid volatilization, cyclohexanone regulates the volatilization gradient to prevent rapid surface drying, and GBL, as a high-boiling-point solvent, maintains leveling during processing. The volume ratio of 1:0.8-1.5:0.3-0.8 creates an azeotropic effect, ensuring that the coating process is free of orange peel defects.

[0043] The functional additives include an accelerator, an antioxidant, and a core-shell toughening agent. The core-shell toughening agent is polymethyl methacrylate / butyl acrylate rubber particles with a particle size distribution of 80-200 nm. The principle behind this is that the core-shell toughening agent (PMMA / PBA) is designed with a shell modulus gradient (80-200 nm particle size): the soft core triggers silver crazing to absorb energy, while the hard shell restricts crack propagation. The hindered phenol / phosphite composite antioxidant is adsorbed on a SiO2 carrier, achieving sustained release, extending the thermal oxidation protection period.

[0044] Furthermore, the mass ratio of the hydroxy-terminated nitrile rubber to the carboxyl nitrile rubber in the elastomer modifier is 1:0.3-2.5, and the reaction temperature of the maleic anhydride graft modification is 85-120° C., and the reaction time is 2-5 hours.

[0045] Furthermore, the surface modification of the nanocomposite reinforcing agent adopts an in-situ hydrolysis-condensation process, specifically comprising: dispersing boehmite powder in an ethanol-water mixture, adding a silane coupling agent, and performing a hydrolysis reaction at pH 4-6 for 1-3 hours, followed by aging at 60-80°C for 2-4 hours.

[0046] Furthermore, the latent curing component further comprises 0.5-3 parts of an imidazole latent accelerator, wherein the imidazole latent accelerator is 2-phenylimidazoline or 2-ethyl-4-methylimidazole, and the accelerator is microencapsulated, and the capsule wall material is a polyurethane-acrylate copolymer.

[0047] Furthermore, the preparation method of the core-shell toughening agent includes: first synthesizing a polybutyl acrylate rubber core with a particle size of 50-100 nm by emulsion polymerization, and then step-by-step grafting a methyl methacrylate hard shell layer by a gradient temperature rising method, and finally forming core-shell particles with a gradient modulus structure.

[0048] The solvent component further contains 0.1-0.5 parts of a leveling agent, a fluorinated acrylate copolymer with a molecular weight of 5,000-20,000 and a fluorine content of 8-15% by weight. The fluorinated acrylate leveling agent spreads via a surface tension gradient, and a molecular weight of 5,000-20,000 ensures that its migration rate matches the solvent's evaporation rate.

[0049] Furthermore, the antioxidant in the functional additive is a complex of hindered phenols and phosphites, with a mass ratio of 1:0.5-2, and the composite antioxidant is adsorbed on a silica carrier, with a drug loading of 40-60%.

[0050] A method for preparing the FCCL adhesive as described above comprises the following steps:

[0051] S1. Preparation of the elastomer modifier: Mix hydroxyl-terminated nitrile rubber and carboxyl-terminated nitrile rubber in a mass ratio of 1:0.3-2.5. Add maleic anhydride and conduct a grafting reaction at 85-120°C for 2-5 hours, controlling the grafting rate to 1.5-3.8wt% and the acid value to 35-45mgKOH / g. The maleic anhydride is melt-grafted at 85-120°C, synergistically activating the reaction sites with the hydroxyl and carboxyl groups. A two-step control process is employed: an initial low temperature (85°C) ensures uniform grafting, followed by a subsequent high temperature (120°C) to achieve deep modification. Acid value control is achieved by adjusting the maleic anhydride feed ratio and reaction time.

[0052] S2. Nanocomposite reinforcement treatment: Boehmite powder is dispersed in an ethanol-water mixture, γ-glycidyloxypropyltrimethoxysilane is added, the pH is adjusted to 4-6, a hydrolysis reaction is carried out for 1-3 hours, and the powder is aged at 60-80°C for 2-4 hours to obtain a modified powder with a surface silane loading of 1.2-3.5wt%. In the in-situ hydrolysis-condensation process, a pH of 4-6 promotes the hydrolysis of silane to silanols while inhibiting the dissolution of boehmite. The ethanol-water mixed solvent regulates the hydrolysis rate, and the aging stage (60-80°C) promotes the condensation of silanols with the hydroxyl groups on the boehmite surface to form a covalent bond graft layer. Ultrasonic treatment (200-400W) breaks up powder agglomerates and achieves monodisperse modification.

[0053] S3. Synthesis of core-shell toughening agent: prepare polybutyl acrylate rubber core by emulsion polymerization, increase the temperature gradually to 80-95℃ and graft methyl methacrylate shell layer step by step to form gradient modulus core-shell particles with a particle size of 80-200nm; wherein, the gradient temperature emulsion polymerization is as follows: butyl acrylate polymerization is initiated at 60-70℃ to form a soft core (Tg≈-50℃); methyl methacrylate-butyl acrylate copolymer is introduced into the transition layer at 75-85℃ to form a modulus gradient; methyl methacrylate homopolymerization hard shell is completed at 90-95℃ (Tg≈105℃); the temperature difference is ≥10℃ / h to control the monomer diffusion rate and realize shell densification.

[0054] S4. Latent curing component treatment: dicyandiamide and diaminodiphenyl sulfone are mixed in a mass ratio of 1:0.2-5, and a microencapsulated imidazole accelerator is added to control the ratio of active hydrogen equivalent to epoxy equivalent to 0.9-1.1:1;

[0055] S5. Preparation of adhesive: Premix the epoxy resin base material and the product of step S1 in a solvent component at 40-60°C, then add the products of steps S2-S4 and functional additives in sequence, disperse at high speed, and filter. The solvent is used in a volume ratio of methyl ethyl ketone: cyclohexanone: γ-butyrolactone of 1:0.8-1.5:0.3-0.8. Premixing is performed at a temperature of 40-60°C and a stirring speed of 800-1500 rpm to reduce the viscosity of the resin and promote the dispersion of the elastomer phase. A nano-sand milling process (D90 ≤ 500nm) is used to break up the soft agglomeration of nanoparticles, and a leveling agent is added by atomization to prevent surface defects caused by excessive local concentration. The solvent evaporation gradient design ensures synchronous curing of the coating surface and interior.

[0056] Furthermore, in step S2, the mass ratio of boehmite powder to silane coupling agent is 100:1.5-4.5, and the ultrasonic power during the hydrolysis reaction is controlled at 200-400W;

[0057] The temperature gradient in step S3 includes: a first stage at 60-70°C to initiate core layer polymerization, a second stage at 75-85°C to form a transition layer, and a third stage at 90-95°C to complete shell grafting, with a temperature difference of ≥10°C / h in each stage;

[0058] The microencapsulation treatment in step S4 includes: reacting an imidazole accelerator with a polyurethane-acrylate copolymer monomer in an emulsification system to form microcapsules with a wall thickness of 0.1-0.5 μm by interfacial polymerization, a coverage rate of ≥85%, and a thermal decomposition starting temperature of ≥130° C.;

[0059] In step S5: in the premixing stage, the stirring rate is controlled to 800-1500 rpm, and the dispersion time is 30-60 min; the high-speed dispersion adopts the nano-sand milling process, and the particle size is controlled to D90≤500 nm; the leveling control agent is added in an atomized manner in the later stage of dispersion, and the temperature is maintained at 40±2°C.

[0060] Specific examples are provided below. The provided examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0061] Example 1

[0062] 1. Raw material ratio (by weight)

[0063] Bisphenol A epoxy resin (epoxy equivalent 200g / eq): 25 parts;

[0064] Novolac epoxy resin (epoxy equivalent 220g / eq): 15 parts;

[0065] Maleic anhydride grafted hydroxy-terminated nitrile rubber (grafting rate 2.5wt%): 12 parts;

[0066] Carboxyl nitrile rubber: 8 parts;

[0067] Dicyandiamide: 6 parts;

[0068] Diaminodiphenyl sulfone: 3 parts;

[0069] Surface-modified boehmite powder (silane loading 2.2 wt%): 12 parts;

[0070] Methyl ethyl ketone: 20 parts;

[0071] Cyclohexanone: 18 parts;

[0072] γ-Butyrolactone: 7 parts;

[0073] Microencapsulated 2-ethyl-4-methylimidazole (encapsulation efficiency 90%): 1.5 parts;

[0074] Hindered phenol antioxidant (drug loading 50%): 0.8 parts;

[0075] Phosphite antioxidant (drug loading 50%): 0.4 parts;

[0076] Core-shell toughening agent (particle size 150nm): 1.2 parts;

[0077] Fluorine-containing acrylate leveling agent (fluorine content 10wt%): 0.3 parts;

[0078] 2. Preparation Method

[0079] S1. Preparation of elastomer modifier: hydroxy-terminated nitrile rubber and carboxyl nitrile rubber were mixed in a mass ratio of 1:0.67, heated to 95° C., and maleic anhydride was added to react for 3 hours, with the grafting rate controlled at 2.5 wt % and the acid value at 40 mg KOH / g.

[0080] S2. Nanocomposite reinforcement treatment: boehmite powder (average particle size 50 nm) was dispersed in an ethanol-water mixture (volume ratio 3:1), γ-glycidyloxypropyltrimethoxysilane (powder to silane mass ratio 100:3) was added, the pH was adjusted to 5, ultrasonic power 300 W was used for hydrolysis reaction for 2 hours, and then aged at 70°C for 3 hours.

[0081] S3. Synthesis of core-shell toughening agent: ① Core layer polymerization: emulsion polymerization of butyl acrylate at 60℃ to form an 80nm rubber core; ② Gradient heating: grafting methyl methacrylate transition layer at 75℃, and completing hard shell layer polymerization at 90℃, with a final particle size of 150nm.

[0082] S4. Preparation of latent curing component: dicyandiamide and diaminodiphenyl sulfone were mixed in a mass ratio of 1:0.5, and a microencapsulated imidazole accelerator (wall thickness 0.3 μm) was added, with the ratio of active hydrogen equivalent to epoxy equivalent being 1:1.

[0083] S5. Preparation of adhesive: premix the epoxy resin base material and the elastomer modifier in a solvent at 50°C (stirring rate 1200 rpm, 45 min), add the nano-reinforcement agent, latent curing component, antioxidant and core-shell toughening agent in sequence, nano-grind to D90 ≤ 400 nm, add the leveling agent through atomization, and filter at 40°C with insulation.

[0084] Example 2

[0085] 1. Raw material ratio (by weight)

[0086] Bisphenol F epoxy resin (epoxy equivalent 190g / eq): 40 parts;

[0087] Novolac epoxy resin (epoxy equivalent 220g / eq): 10 parts;

[0088] Maleic anhydride grafted hydroxy-terminated nitrile rubber (grafting rate 2.5wt%): 10 parts;

[0089] Carboxyl nitrile rubber: 15 parts;

[0090] Dicyandiamide: 6 parts;

[0091] Diaminodiphenyl sulfone: 3 parts;

[0092] Surface-modified boehmite powder (silane loading 3.0 wt%): 18 parts;

[0093] Methyl ethyl ketone: 20 parts;

[0094] Cyclohexanone: 18 parts;

[0095] γ-Butyrolactone: 7 parts;

[0096] Microencapsulated 2-ethyl-4-methylimidazole (encapsulation efficiency 90%): 1.5 parts;

[0097] Hindered phenol antioxidant (drug loading 50%): 0.8 parts;

[0098] Phosphite antioxidant (drug loading 50%): 0.4 parts;

[0099] Core-shell toughening agent (particle size 150nm): 1.2 parts;

[0100] Fluorine-containing acrylate leveling agent (fluorine content 10wt%): 0.3 parts;

[0101] 2. Preparation method process adjustment

[0102] The rubber mass ratio of the elastomer modifier to the elastomer modifier was 1:1.5, the grafting reaction temperature was 110°C, and the reaction time was 4 hours. The nanoreinforcement agent was aged at 80°C, and the silane loading was increased to 3.0 wt%.

[0103] The heating rate during the shell polymerization stage of the core-shell particles was increased to 15°C / h, and the final particle size was 80 nm;

[0104] The rest is the same as in Example 1.

[0105] Example 3

[0106] 1. Raw material ratio (by weight)

[0107] Bisphenol A epoxy resin (epoxy equivalent 210g / eq): 20 parts;

[0108] Bisphenol F epoxy resin (epoxy equivalent 195g / eq): 20 parts;

[0109] Maleic anhydride grafted hydroxy-terminated nitrile rubber (grafting rate 3.2 wt%): 15 parts;

[0110] Carboxylated nitrile rubber: 10 parts;

[0111] Dicyandiamide: 8 parts;

[0112] Diaminodiphenyl sulfone (DDS): 6 parts;

[0113] Surface-modified boehmite powder (silane loading 1.8 wt%): 10 parts;

[0114] Methyl ethyl ketone: 25 parts;

[0115] Cyclohexanone: 20 parts;

[0116] γ-Butyrolactone: 10 parts;

[0117] Microencapsulated 2-phenylimidazoline (encapsulation efficiency 88%): 2.0 parts;

[0118] Hindered phenol antioxidant (drug loading 55%): 1.0 part;

[0119] Phosphite antioxidant (drug loading 55%): 0.6 parts;

[0120] Core-shell toughening agent (particle size 120nm): 1.5 parts;

[0121] Fluorine-containing acrylate leveling agent (fluorine content 12wt%): 0.4 parts;

[0122] 2. Preparation Method

[0123] S1. Preparation of elastomer modifier: hydroxyl-terminated nitrile rubber and carboxyl-terminated nitrile rubber were mixed in a mass ratio of 1:1.2, and maleic anhydride was grafted onto the mixture at 105°C for 4 hours to control the grafting rate to 3.2 wt% and the acid value to 38 mgKOH / g;

[0124] S2, nanocomposite reinforcement treatment: boehmite powder (average particle size 60 nm) and silane coupling agent mass ratio 100:2.5, hydrolysis at 350 W ultrasonic power under pH 4.8 for 2.5 hours, and aging at 75 ° C for 3.5 hours;

[0125] S3. Synthesis of core-shell toughening agent: ① Core layer polymerization: Synthesize 90nm butyl acrylate rubber core at 65℃; ② Gradient temperature increase: Graft the transition layer at 80℃, and complete the shell layer polymerization at 95℃, with a final particle size of 120nm;

[0126] S4. Preparation of latent curing component: the mass ratio of dicyandiamide to DDS is 1:0.75, microencapsulated 2-phenylimidazoline (wall thickness 0.2 μm) is added, and the active hydrogen equivalent ratio is 1.05:1.

[0127] S5. Preparation of adhesive solution: stirring speed in premixing stage is 1000 rpm, time is 50 min; D90 is ≤ 450 nm after nano sand grinding, and leveling agent is added by atomization and kept warm at 45°C.

[0128] Example 4

[0129] 1. Raw material ratio (by weight)

[0130] Novolac epoxy resin (epoxy equivalent 240g / eq): 35 parts;

[0131] Bisphenol A epoxy resin (epoxy equivalent 205g / eq): 15 parts;

[0132] Maleic anhydride grafted hydroxy-terminated nitrile rubber (grafting rate 1.8wt%): 8 parts;

[0133] Carboxylated nitrile rubber: 12 parts;

[0134] Dicyandiamide: 4 parts;

[0135] Diaminodiphenyl sulfone (DDS): 10 parts;

[0136] Surface-modified boehmite powder (silane loading 3.2 wt%): 16 parts;

[0137] Methyl ethyl ketone: 15 parts;

[0138] Cyclohexanone: 25 parts;

[0139] γ-Butyrolactone: 5 parts;

[0140] Microencapsulated 2-ethyl-4-methylimidazole (encapsulation efficiency 92%): 1.8 parts;

[0141] Hindered phenol antioxidant (drug loading 45%): 0.7 parts;

[0142] Phosphite antioxidant (drug loading 45%): 0.5 parts;

[0143] Core-shell toughening agent (particle size 180nm): 2.0 parts;

[0144] Fluorinated acrylate leveling agent (fluorine content 14wt%): 0.2 parts;

[0145] 2. Preparation method process adjustment

[0146] Elastomer modifier: Grafting reaction temperature 88°C, time 2.5 hours, acid value 42 mgKOH / g;

[0147] Nano-reinforcement agent: boehmite powder to silane mass ratio of 100:4.0, hydrolysis at pH 5.5 for 1.5 hours, and aging at 65°C for 4 hours;

[0148] Core-shell toughening agent: core layer particle size is 50nm, shell layer gradient heating rate is 20℃ / h, and finally a 180nm gradient structure is formed;

[0149] Latent curing components: mass ratio of dicyandiamide to DDS is 1:2.5, and active hydrogen equivalent ratio is 0.95:1;

[0150] Preparation of adhesive solution: premixing temperature 55℃, stirring speed 1500rpm, D90≤350nm after nano-sand grinding;

[0151] The rest is the same as Example 3.

[0152] Comparative Example 1

[0153] No core-shell toughening agent was used, and the rest was the same as in Example 1.

[0154] Comparative Example 2

[0155] The nano-reinforcement agent was not surface-modified, and boehmite was directly added. The rest was the same as in Example 1.

[0156] Performance test: The performance of the adhesives of the examples and comparative examples was characterized, and the results are shown in the following table:

[0157]

[0158] Combining Examples 1 to 4 and Comparative Examples 1 to 2, it can be seen that through the synergistic modification of core-shell toughening agents, surface-modified nanofillers, and multi-component resins / curing agents, the adhesive is optimized in terms of peel strength, heat resistance, toughness, and electrical properties. Among them, Example 2 (bisphenol F resin as the main component, high silane loading nanofiller, core-shell particle size of 80nm) has better overall performance and is suitable for scenarios with high requirements for heat resistance and interfacial strength; Example 1 (balanced ratio) performs outstandingly in toughness and fatigue performance. The comparative examples verify the irreplaceable nature of the key modified components and provide a clear direction for optimizing adhesive formulations.

[0159] The principles and implementation methods of the present invention are described herein using specific examples. The description of the above embodiments is only intended to help understand the method and core ideas of the present invention. The above are only preferred implementation methods of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, and all of these should fall within the scope of protection of the present invention.

Claims

1. A FCCL adhesive, characterized in that: The invention comprises, by weight, 30-50 parts of epoxy resin base material, 10-25 parts of elastomer modifier, 5-20 parts of latent curing component, 8-18 parts of nanocomposite reinforcing agent, 35-55 parts of solvent component and 1.5-6 parts of functional additive.

2. The FCCL adhesive according to claim 1, characterized in that The epoxy resin base material is selected from a mixture of at least two of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin, and its epoxy equivalent is 180-250g / eq; The elastomer modifier is a blend of maleic anhydride grafted modified hydroxyl-terminated nitrile rubber and carboxyl nitrile rubber, with a grafting rate of 1.5-3.8 wt % and an acid value controlled in the range of 35-45 mgKOH / g; The latent curing component comprises a complex of dicyandiamide and diaminodiphenyl sulfone, the mass ratio of the two being 1:0.2-5, and the ratio of active hydrogen equivalent to epoxy equivalent being 0.9-1.1:1; The nanocomposite reinforcing agent is boehmite powder surface-modified with γ-glycidyloxypropyltrimethoxysilane, with an average particle size of 30-80 nm and a specific surface area of ​​50-150 m 2 / g, surface silane loading is 1.2-3.5wt%; The solvent component is composed of methyl ethyl ketone, cyclohexanone and gamma-butyrolactone in a volume ratio of 1:0.8-1.5:0.3-0.8; The functional additives include an accelerator, an antioxidant and a core-shell toughening agent, wherein the core-shell toughening agent is polymethyl methacrylate / butyl acrylate rubber particles with a particle size distribution of 80-200 nm.

3. The FCCL adhesive according to claim 2, characterized in that The mass ratio of the terminal hydroxyl nitrile rubber to the carboxyl nitrile rubber in the elastomer modifier is 1:0.3-2.5, and the reaction temperature of the maleic anhydride graft modification is 85-120° C., and the reaction time is 2-5 hours.

4. The FCCL adhesive according to claim 2, characterized in that The surface modification of the nanocomposite reinforcing agent adopts an in-situ hydrolysis-condensation process, which specifically includes: dispersing boehmite powder in an ethanol-water mixture, adding a silane coupling agent, and performing a hydrolysis reaction at pH 4-6 for 1-3 hours, followed by aging at 60-80°C for 2-4 hours.

5. The FCCL adhesive according to claim 2, characterized in that The latent curing component further comprises 0.5-3 parts of an imidazole latent accelerator, wherein the imidazole latent accelerator is 2-phenylimidazoline or 2-ethyl-4-methylimidazole, and the accelerator is microencapsulated, and the capsule wall material is a polyurethane-acrylate copolymer.

6. The FCCL adhesive according to claim 2, characterized in that The preparation method of the core-shell toughening agent comprises: first synthesizing a polybutyl acrylate rubber core with a particle size of 50-100 nm by emulsion polymerization, then grafting a methyl methacrylate hard shell layer step by step by a gradient temperature increase method, and finally forming core-shell particles with a gradient modulus structure.

7. The FCCL adhesive according to claim 2, characterized in that The solvent component also contains 0.1-0.5 parts of a leveling control agent, which is a fluorine-containing acrylate copolymer with a molecular weight of 5000-20000 and a fluorine content of 8-15 wt%.

8. The FCCL adhesive according to claim 2, characterized in that The antioxidant in the functional additive is a complex of hindered phenols and phosphites, with a mass ratio of 1:0.5-2. The composite antioxidant is adsorbed on a silicon dioxide carrier, and the drug loading is 40-60%.

9. A method for preparing the FCCL adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Preparation of elastomer modifier: Mix hydroxyl-terminated nitrile rubber and carboxyl nitrile rubber in a mass ratio of 1:0.3-2.5, add maleic anhydride and carry out grafting reaction at 85-120° C. for 2-5 hours, control the grafting rate to 1.5-3.8 wt % and the acid value to 35-45 mgKOH / g; S2. Nanocomposite reinforcing agent treatment: dispersing boehmite powder in an ethanol-water mixture, adding γ-glycidyloxypropyltrimethoxysilane, adjusting the pH to 4-6, performing a hydrolysis reaction for 1-3 hours, and aging at 60-80° C. for 2-4 hours to obtain a modified powder with a surface silane loading of 1.2-3.5 wt%; S3. Synthesis of core-shell toughening agent: prepare polybutyl acrylate rubber core by emulsion polymerization, gradually increase the temperature to 80-95°C and graft methyl methacrylate shell layer in steps to form gradient modulus core-shell particles with a particle size of 80-200 nm; S4. Latent curing component treatment: dicyandiamide and diaminodiphenyl sulfone are mixed in a mass ratio of 1:0.2-5, and a microencapsulated imidazole accelerator is added to control the ratio of active hydrogen equivalent to epoxy equivalent to 0.9-1.1:1; S5. Preparation of glue: premix the epoxy resin base material and the product of step S1 in a solvent component at 40-60° C., add the products of steps S2-S4 and functional additives in sequence, disperse at high speed, and then filter. The solvent is used in a volume ratio of methyl ethyl ketone: cyclohexanone: γ-butyrolactone of 1:0.8-1.5:0.3-0.

8.

10. The preparation method according to claim 9, characterized in that In step S2, the mass ratio of boehmite powder to silane coupling agent is 100:1.5-4.5, and the ultrasonic power is controlled at 200-400W during the hydrolysis reaction; The temperature gradient in step S3 includes: a first stage at 60-70°C to initiate core layer polymerization, a second stage at 75-85°C to form a transition layer, and a third stage at 90-95°C to complete shell grafting, with a temperature difference of ≥10°C / h in each stage; The microencapsulation treatment in step S4 includes: reacting an imidazole accelerator with a polyurethane-acrylate copolymer monomer in an emulsification system to form microcapsules with a wall thickness of 0.1-0.5 μm by interfacial polymerization, a coverage rate of ≥85%, and a thermal decomposition starting temperature of ≥130° C.; In step S5: in the premixing stage, the stirring rate is controlled to 800-1500 rpm, and the dispersion time is 30-60 min; the high-speed dispersion adopts the nano-sand milling process, and the particle size is controlled to D90≤500 nm; the leveling control agent is added in an atomized manner in the later stage of dispersion, and the temperature is maintained at 40±2°C.

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