Glass-cloth-based epoxy prepreg sheet free of glue flowing in press fit and preparation method of glass-cloth-based epoxy prepreg sheet

Abstract

The invention relates to the technical field of high-performance composite materials, in particular to a glass cloth-based epoxy prepreg sheet free of glue flowing in press fit and a preparation method of the glass cloth-based epoxy prepreg sheet. The invention relates to a glass cloth-based epoxy prepreg sheet without flowing glue in press fit, which is prepared by dipping glass fiber cloth in a glue solution and carrying out semi-curing treatment, comprising the following raw materials in parts by weight: 35-45 parts of tetrafunctional epoxy resin, 30-40 parts of biphenyl epoxy resin, 10-20 parts of hydrogenated bisphenol A epoxy resin, 40-55 parts of phenolic resin, 10-20 parts of surface epoxy functionalized PES micro powder, 30-40 parts of spherical silicon dioxide and 0.3-0.8 part of a curing accelerator. 0.5-1.5 parts of KH-560, an organic solvent, a toughening agent and a flame retardant. According to the preparation method, a gradient curing process is constructed through three-section type sectional drying, the reaction degree of a semi-curing stage is accurately controlled, and the prepared glass cloth-based epoxy prepreg has uniform flow characteristic and storage stability, and meanwhile, the three-in-one performance balance effect of flame retardance, flow suppression and toughness is realized.

Description

Technical Field

[0001] This invention relates to the field of high-performance composite materials technology, and in particular to a non-flowing glass cloth-based epoxy prepreg and its preparation method. Background Technology

[0002] Fiberglass cloth-based epoxy prepreg is a core material for manufacturing multilayer printed circuit boards and high-performance electrical insulation components. Typically, it refers to a sheet-like composite material formed by impregnating fiberglass cloth with a semi-cured epoxy resin system through a specific process, followed by drying. This material has a certain degree of workability at room temperature, and during subsequent heating and pressurizing lamination, the resin system undergoes a further cross-linking reaction, achieving complete curing and thus bonding multiple layers of circuit patterns or insulation layers into a single unit.

[0003] In the lamination process of multilayer boards, the flow characteristics of the resin in the prepreg are a key factor determining product quality. Appropriate flowability is a prerequisite for ensuring that the resin can fully fill the gaps between circuits, eliminate interlayer air bubbles, and achieve a firm bond with the inner copper foil or core board. However, if the resin flow is too high, a "resin run" phenomenon occurs, which not only leads to significant resin loss and uncontrolled dielectric thickness but also causes interlayer slippage, short circuit hazards, and appearance defects due to resin overflow.

[0004] To effectively control resin flow during the pressing process, existing technologies typically focus on adjusting the formulation and physical state of the resin system. Common techniques include: adding various tackifiers or polymeric toughening agents to the epoxy resin matrix to increase the resin melt viscosity; altering the gelation time and flowability of the resin system by controlling the baking conditions during prepreg manufacturing; and precisely controlling the resin content in the prepreg. These methods, to some extent, constrain the resin's flow behavior.

[0005] However, the aforementioned methods often present an irreconcilable contradiction between suppressing resin flow and ensuring good filling and interlayer adhesion. In pursuit of extremely low resin flow, existing technologies typically tend to excessively increase the melt viscosity of the resin system at the pressing temperature or accelerate its gelation reaction. While this approach can limit the macroscopic lateral flow of the resin, it often significantly impairs the resin's microscopic wetting ability towards the internal fiber bundles of the glass fiber cloth and the roughened copper foil surface. As a result, tiny voids or weak points in adhesion are easily generated at the interface of the cured laminate, leading to decreased interlayer peel strength and severely affecting product reliability and service life.

[0006] Therefore, there is an urgent need to develop a non-flowing glass cloth-based epoxy prepreg and its preparation method, so that under standard lamination process conditions, it can maintain excellent resin flowability to fully wet the micro-interface and fill the voids, thereby ensuring high interfacial bonding strength, while controlling the macroscopic lateral flow of resin to an extremely low level, truly achieving the effect of "non-flowing" or "near-zero flowing" to meet the needs of high-density, high-reliability multilayer board manufacturing. Summary of the Invention

[0007] To meet the requirements of high-density, high-reliability multilayer board manufacturing, this application provides a glass cloth-based epoxy prepreg that achieves excellent resin flowability to fully wet micro-interfaces and fill voids under standard lamination process conditions, while controlling the macroscopic lateral flow of resin to an extremely low level, truly achieving the effect of "no glue flow during lamination" or "near-zero glue flow". This application provides a glass cloth-based epoxy prepreg that achieves no glue flow during lamination and its preparation method.

[0008] In a first aspect, this application provides a glass cloth-based epoxy prepreg that is pressed without adhesive flow, the prepreg being made by impregnating glass fiber cloth with adhesive and then subjecting it to a semi-curing treatment; The adhesive comprises the following raw materials in parts by weight: 35-45 parts tetrafunctional epoxy resin, 30-40 parts biphenyl epoxy resin, 10-20 parts hydrogenated bisphenol A type epoxy resin, 40-55 parts phenolic resin, 10-20 parts surface epoxy functionalized PES micro powder, 30-40 parts spherical silica, 0.3-0.8 parts curing accelerator, 0.5-1.5 parts KH-560, and organic solvent.

[0009] By adopting the above scheme, the introduction of surface-functionalized epoxy PES micropowder into the adhesive solution not only utilizes its thermoplastic properties to physically lock the lateral flow of the resin, but also forms "anchoring points" through the chemical cross-linking of surface epoxy groups with the matrix. This achieves a balance between "near-zero resin flow" (resin width ≤ 0.5 mm) and high interfacial bonding strength, overcoming the technical problem that inhibiting resin flow inevitably damages interfacial bonding in traditional technologies. The "organic-inorganic" and "micron-nano" multi-level filler synergistic system constructed by the scheme takes into account heat resistance, dimensional stability, and mechanical properties. The dual interfacial strengthening effect of KH-560 coupling agent and the synergistic compatibility of tetrafunctional groups, biphenyl, and hydrogenated bisphenol A type epoxy resin further optimize dielectric properties and processability.

[0010] Preferably, the preparation of the surface epoxy-functionalized PES micropowder includes the following steps: (1) Raw material pretreatment: Place PES micro powder in a vacuum drying oven and dry it at 100-120℃ for 4-6 hours to remove the physically adsorbed moisture on the surface. After cooling, it is ready for use. (2) Preparation of coupling agent hydrolysate: Add KH-560 to the first part of anhydrous ethanol to obtain mixture A; mix deionized water with glacial acetic acid to obtain mixture B with pH value of 4-5; slowly add mixture B to mixture A, stir at room temperature for 30-60 minutes to allow it to be fully hydrolyzed, and obtain a clear and transparent pre-hydrolyzed solution. (3) Surface grafting reaction: Add the second part of anhydrous ethanol to the reaction vessel, start stirring, and slowly add the PES micro powder pretreated in step S1 to disperse it evenly and form a suspension; heat the reaction vessel to 50-60℃, and slowly add the pre-hydrolyzed solution from step S2 to the PES micro powder suspension while stirring; after the addition is complete, heat the reaction system to 75-85℃ and continue the reaction under reflux for 4-6 hours; (4) Post-processing and drying: After the reaction is completed, the product is cooled to room temperature, the reaction product is centrifuged, the solid material is collected, and the solid material is washed multiple times with anhydrous ethanol until the washing liquid is clear. The washed wet filter cake is transferred to a vacuum drying oven and dried to constant weight. The dried product is sieved to obtain surface epoxy functionalized PES micro powder.

[0011] By adopting the above scheme, the preparation process uses a "dispersion followed by drop addition" process to avoid agglomeration caused by excessively high local concentrations; the reflux reaction for 4-6 hours allows the grafting to proceed fully, and multiple washings remove physically adsorbed silanes to ensure product purity, with the surface epoxy functional groups existing stably in a chemically bonded form; the entire reaction is carried out in an ethanol medium to avoid swelling or agglomeration caused by an aqueous system; the final product, after drying and sieving, still maintains a white powder state with good flowability, which is convenient for uniform dispersion in subsequent adhesive formulations.

[0012] Preferably, the preparation of the surface epoxy functionalized PES micro powder includes the following raw materials in parts by weight: 90-110 parts of PES micro powder, 3-8 parts of KH-560, 100 parts of anhydrous ethanol, 1.5-3 parts of deionized water, and 200 parts of anhydrous ethanol.

[0013] Preferably, the polyethersulfone micropowder has an intrinsic viscosity of 0.35-0.37 DL / g, a heat distortion temperature of 203℃, and a specific gravity of 1.37 g / cm³. 3 .

[0014] By adopting the above scheme, KH-560 is fully hydrolyzed under weakly acidic conditions to generate silanol groups, forming a stable structure on the surface of PES micropowder. This ensures the strong grafting of epoxy functional groups and realizes the transformation of the PES micropowder surface from inert to reactive. During the curing process, the modified PES micropowder undergoes chemical cross-linking with the epoxy matrix, retaining the physical regulation function of thermoplastic resin on melt viscosity while strengthening interfacial bonding through chemical anchoring. Ultimately, this reduces the adhesive width of the prepreg to 0.5 mm while improving peel strength. This provides a structural basis for achieving "non-flowing adhesive during pressing" and "high interfacial strength" in subsequent prepreg applications.

[0015] Preferably, the spherical silica comprises the following raw materials in parts by weight: 20-25 parts of submicron-sized spherical silica and 10-15 parts of aminosilanized nano-sized spherical silica.

[0016] Preferably, the submicron-sized spherical silica has an average particle size of 1 μm; the aminosilanized nano-sized spherical silica has an average particle size of 50 nm.

[0017] By adopting the above scheme, submicron and nano-sized spherical silica form a "micron-nano" multi-level filled structure: nano-sized particles fill the gaps between micron-sized particles, increasing the packing density and reducing the thermal expansion coefficient of the system; aminosilanization treatment enables it to chemically bond with epoxy groups, enhancing interfacial bonding and synergistically improving dimensional stability, heat resistance and mechanical properties.

[0018] Preferably, the curing accelerator is an imidazole accelerator and triphenylphosphine in a weight ratio of 1:(2-5), and the imidazole accelerator is selected from any one of 2-methylimidazole, 2-ethyl-4-methylimidazole or 2-phenylimidazole.

[0019] By adopting the above scheme, the curing reaction process is optimized through a synergistic catalytic mechanism: triphenylphosphine catalyzes the ring-opening reaction of epoxy groups and phenolic hydroxyl groups, while imidazole accelerators promote crosslinking through a nucleophilic mechanism. The synergy of the two can significantly increase the crosslinking density of the cured product, thereby improving the glass transition temperature and heat resistance. At the same time, this compound system can achieve stepwise control of the reaction rate, forming a mild and sufficient curing curve in the semi-curing and pressing stages. This avoids insufficient leveling caused by premature resin gelation and excessive resin flow caused by late gelation. Thus, while maintaining excellent processing performance, it ensures that the surface epoxy-functionalized PES micropowder can fully participate in chemical crosslinking, further strengthening the interfacial bonding strength. Ultimately, it synergistically achieves the comprehensive beneficial effects of resin flow suppression, heat resistance improvement, and interfacial enhancement.

[0020] Preferably, the organic solvent is selected from any one of acetone, butanone, ethyl acetate, and toluene, and the viscosity of the adhesive is adjusted to 1800-2200 mPa·s.

[0021] Preferably, the adhesive solution of the non-flowing glass cloth-based epoxy prepreg further includes 5-12 parts of a toughening agent, wherein the toughening agent is a core-shell structured acrylate polymer.

[0022] By adopting the above scheme, the core layer of the core-shell structured acrylate polymer is a cross-linked acrylate rubber, and the shell layer is a glycidyl methacrylate copolymer containing epoxy functional groups. The epoxy functional groups in the shell layer can chemically bond with the resin matrix to form "anchor points". Under the premise of maintaining the original glass transition temperature of the system, the impact toughness and anti-delamination ability of the cured product are significantly improved.

[0023] Preferably, the adhesive solution of the non-flowing glass cloth-based epoxy prepreg further includes 10-20 parts of flame retardant, wherein the flame retardant is any one of DOPO and DOPO derivatives.

[0024] Preferably, the DOPO derivative is a pre-reaction adduct of DOPO and epoxy resin, and its phosphorus content is 5-10 wt%.

[0025] By adopting the above scheme, DOPO-type flame retardants, through the condensed-phase flame retardant mechanism of phosphorus, promote the char formation of epoxy groups at high temperatures, forming a dense carbon layer to insulate against heat and oxygen, achieving UL94 V-0 halogen-free flame retardancy. Simultaneously, because the active hydrogen in the DOPO structure can undergo ring-opening reactions with the epoxy groups, chemically bonding into the cross-linked network, performance degradation caused by the migration and precipitation of small-molecule flame retardants is avoided. More importantly, the introduction of DOPO can form a synergistic effect of "rigidity and flexibility" with the surface epoxy-functionalized PES micropowder: the rigid phosphorus-phenanthrene heterocyclic structure provided by DOPO can compensate for the modulus decrease that may result from the toughening effect of PES micropowder, while the rheological regulation effect of PES micropowder can suppress the risk of excessively low melt viscosity and increased flow that may occur after the introduction of DOPO. The two work together to achieve a three-in-one performance balance of "flame retardancy, flow suppression, and toughness," giving the prepreg high overall service reliability in harsh thermal environments.

[0026] Secondly, this application provides a method for preparing a non-flowing, press-bonded glass cloth-based epoxy prepreg, employing the following technical solution: S1 Impregnation: The glass fiber cloth is pretreated to remove surface moisture and impurities; through the impregnation-extrusion process, the pretreated glass cloth is passed through the impregnation tank containing the adhesive solution at a stable speed to ensure that the adhesive solution is fully impregnated; after impregnation, the excess adhesive solution is squeezed out by the metering roller to control the resin content and obtain the prepreg wet material. S2 Semi-cured: The wet prepreg material obtained in step S2 is placed in a drying oven for segmented drying to obtain a semi-cured prepreg. S3 Winding and Storage: After the semi-cured prepreg obtained in step S3 is cooled to room temperature by cooling rollers, a polyethylene release film is applied to the surface, and the product is wound up. The product should be sealed in packaging and stored in a clean environment.

[0027] Preferably, the glass fiber cloth is pretreated at a temperature of 100-140°C for 2-4 hours.

[0028] Preferably, the adhesive solution in step S1 is prepared according to the following method: S11 adds tetrafunctional epoxy resin, biphenyl epoxy resin and hydrogenated bisphenol A type epoxy resin to a reactor, stirs and mixes, heats to 70-80℃, and stirs at a constant temperature until the resin is completely melted and mixed evenly, and the system is transparent and homogeneous. Then cools down to 40-60℃ for later use. S12 Add surface epoxy-functionalized polyethersulfone micro powder, submicron-sized spherical silica and aminosilanized nano-sized spherical silica sequentially to the resin mixture obtained in step S11, increase the stirring speed, and disperse at high speed under vacuum conditions to make the powder fully wetted, uniformly dispersed and free of agglomerated particles. S13 Cool the mixture obtained in step S12 to 40-50℃, add phenolic resin and curing accelerator while stirring, reduce the stirring speed, and continue mixing under vacuum conditions to completely dissolve and evenly disperse the curing agent. S14 uses organic solvents to adjust the viscosity of the adhesive to 1800-2200 mPa·s. After passing the adhesive through a 150-250 mesh sieve, it is discharged and allowed to stand to defoam before use.

[0029] Preferably, the preparation method of the adhesive further includes adding a toughening agent in step S12 and adding a flame retardant in step S11.

[0030] Through the above technical solution, the flame retardant is heated and melt-blended with epoxy resin in step S11, where its active hydrogen reacts with the epoxy groups in a ring-opening reaction, chemically bonding into the cross-linked network and preventing migration and precipitation. In step S12, the toughening agent is rapidly dispersed together with the filler, and the shell epoxy functional groups form "anchoring points" with the matrix, resulting in uniform distribution and improved toughness. The rigid structure of DOPO and the rheological regulation of PES micropowder synergistically create a "rigid-flexible" effect, while the core-shell toughening agent further enhances toughness.

[0031] Preferably, the stirring speed for high-speed dispersion in step S12 is 800-1200 rpm, the vacuum degree is -0.1 MPa to -0.5 MPa, and the dispersion time is 0.5-1.5 hours.

[0032] Preferably, the stirring speed after reducing the rotation speed in step S13 is 300-500 rpm, and the mixing time under vacuum is 20-40 minutes.

[0033] The above technical solution involves heating and melting three epoxy resins at 70-80℃ to form a transparent and homogeneous matrix, achieving molecular-level blending and activity retention. Three functional powders are then added sequentially under high-speed shearing and vacuum conditions to completely break up agglomerated particles, ensuring uniform dispersion of organic-inorganic and micron-nano multi-level fillers. After cooling, the powder is added to the curing system and mixed at low speed under vacuum to avoid premature reaction and ensure uniform dissolution of the curing agent. The viscosity is adjusted to 1800-2200 mPa·s and filtered to remove bubbles, resulting in a stable adhesive with excellent wettability and no air bubbles or impurities. This lays the foundation for subsequent impregnation processes and consistent prepreg performance.

[0034] Preferably, the impregnation speed in step S1 is 3-6 m / min; the resin content is controlled at 48-55%.

[0035] Preferably, the segmented drying in step S2 is as follows: Zone 1: 100-120℃, 2-3 minutes; Zone 2: 135-145℃, 2-4 minutes; Zone 3: 150-160℃, 1-2 minutes.

[0036] Through the above technical solutions, the fiberglass cloth is pretreated to thoroughly remove moisture and impurities, ensuring full wetting of the adhesive. Impregnation is performed at a speed of 3-6 m / min, controlling the resin content to 48-55%, achieving uniform coating. A three-stage segmented drying process constructs a stepped curing process, precisely controlling the reaction degree in the semi-curing stage, avoiding surface skinning or solvent residue, and giving the prepreg sheet uniform flow characteristics and storage stability. Combined with the rheological regulation of surface epoxy-functionalized PES micropowder, a near-zero flow effect with a lamination width ≤0.5 mm is ultimately achieved. Simultaneously, cooling film coating and sealed packaging ensure consistent product quality and long-term reliability.

[0037] In summary, this application has the following beneficial effects: 1. This application introduces surface-functionalized epoxy PES micropowder into the prepared adhesive solution. This utilizes the thermoplastic properties to physically lock the lateral flow of the resin, and also forms "anchoring points" through chemical cross-linking of the surface epoxy groups with the matrix. This achieves a balance between near-zero resin flow and high interfacial bonding strength, overcoming the technical bottleneck of traditional techniques where suppressing resin flow inevitably damages interfacial bonding. Simultaneously, the constructed "organic-inorganic," "micron-nano" multi-level filler synergistic system, combined with the dual interfacial strengthening effect of KH-560 coupling agent and the synergistic formulation of three epoxy resins, significantly improves the heat resistance, dimensional stability, dielectric properties, and processability of the prepreg.

[0038] 2. The glass cloth-based epoxy prepreg prepared in this application forms a multi-level filled structure through submicron and nano-sized spherical silica. Nanoparticles fill the gaps between micron particles, increasing the packing density and reducing the coefficient of thermal expansion. Aminosilane treatment enables it to chemically bond with epoxy groups, synergistically improving dimensional stability and mechanical properties. The compounded curing accelerator system optimizes the curing process through a synergistic catalytic mechanism, increasing the crosslinking density and glass transition temperature, achieving a comprehensive effect of flow suppression, heat resistance improvement, and interface enhancement. The introduction of toughening agents and flame retardants further endows the product with excellent impact resistance, anti-delamination ability, and halogen-free flame retardant properties, achieving a three-in-one performance balance of "flame retardancy, flow suppression, and toughness".

[0039] 3. The method for preparing the non-flowing glass cloth-based epoxy prepreg of this application employs a three-stage stepped heating semi-curing process to precisely control the reaction degree during the semi-curing stage, avoiding surface skinning or solvent residue, thus ensuring that the prepreg has uniform flow characteristics and storage stability. The adhesive preparation process uses a step-by-step process of "high-temperature melt blending - vacuum high-speed dispersion - low-temperature low-speed mixing" to ensure molecular-level blending of the three epoxy resins, uniform dispersion of multi-level fillers, and gentle introduction of the curing system, resulting in a stable adhesive with excellent wettability and no air bubbles or impurities. The impregnation process precisely controls the resin content and impregnation speed, combined with cooling film coating and sealed packaging, ultimately producing a high-performance prepreg product with consistent quality and stable storage, meeting the needs of high-density, high-reliability multilayer board manufacturing. Detailed Implementation

[0040] The technical solution of this application is further illustrated by specific embodiments below. These specific embodiments do not represent a limitation on the scope of protection of this application. Any non-essential modifications and adjustments made by others based on the concept of this application still fall within the scope of protection of this application.

[0041] Unless otherwise specified, the experimental methods shown in the following examples are conventional methods. All reagents and materials shown are commercially available products.

[0042] Tetrafunctional epoxy resin: Guangzhou Senmao New Materials Co., Ltd., EEW=110-125g / eq, CAS: 28768-32-3, Model: AG-80; Biphenyl epoxy resin: Guangzhou Taiji New Material Co., Ltd., item number: YX4000, epoxy equivalent 175-185g / eq, softening point 104-110℃; Hydrogenated bisphenol A type epoxy resin: Junqiao New Materials (Shenzhen) Co., Ltd., Model: EP-4080E, Vis.: 130Ps / 25℃; Epoxy equivalent EEW=190; Phenolic resin: Puyang Enying Polymer Materials Co., Ltd., Item No.: NF-7110; PES (polyethersulfone) micro powder: Jinhua Fluoroma Chemical Technology Co., Ltd., CAS: 9002-84-0, Model: FM-037; Silica (aminosilanization treatment): Xi'an Qiyue Biotechnology Co., Ltd., Model: SiO2 coupled with amino; Spherical silica nanoparticles (submicron level): Jiangsu Huimai Powder Technology Co., Ltd., item number: 24-12, D50 (um) = 1.0 ± 0.2; Triphenylphosphine (TPP): Shanghai Aoji Chemical Co., Ltd., CAS: 24762-44-5, Model: TPP-d15; 2-Methylimidazole: AVIC New Materials Co., Ltd., CAS: 693-98-1, Model: 02; 2-Ethyl-4-methylimidazole: Nanjing Yiji Biochemical Technology Co., Ltd., CAS: 931-36-2; 2-Phenylidene imidazole: Jiangsu Zhenri Chemical Co., Ltd., CAS: 670-96-2, Product No.: 0511; Core-shell structured acrylate polymer: Rohm and Haas, USA; Distributor: Dongguan Shenghao Plastic Raw Materials Co., Ltd.; CAS: 88497-56-7; Model: PARALOID™ EXL-2388; DOPO: Guangzhou Yuanda New Materials Co., Ltd., CAS: 99208-50-1, Model: Flame Retardant ODOP.

[0043] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0044] Preparation Example Preparation Example 1: Preparation of Surface-Functionalized PES Micropowder (1) Raw material pretreatment: Place 90kg of PES micro powder in a vacuum drying oven and dry at 100℃ for 6 hours to remove the surface physically adsorbed moisture. After cooling, it is ready for use. (2) Preparation of coupling agent hydrolysate: Add 3 kg KH-560 to 100 kg of the first portion of anhydrous ethanol to obtain mixture A; take 1.5 kg of deionized water and slowly add glacial acetic acid dropwise while stirring to obtain mixture B with pH value of 4; slowly add mixture B dropwise to mixture A and stir at room temperature for 30 minutes to allow it to be fully hydrolyzed to obtain a clear and transparent pre-hydrolyzed solution; (3) Surface grafting reaction: Add 200 parts of the second part of anhydrous ethanol to the reaction vessel, start stirring, and slowly add the PES micro powder after pretreatment in step (1) to disperse it evenly and form a suspension; heat the reaction vessel to 50-60℃, and slowly add the pre-hydrolyzed solution in step (2) to the PES micro powder suspension while stirring; after the addition is completed, heat the reaction system to 75℃ and continue the reaction under reflux for 6 hours; (4) Post-processing and drying: After the reaction is completed, the product is cooled to room temperature, the reaction product is centrifuged, the solid material is collected, and the solid material is washed multiple times with anhydrous ethanol until the washing liquid is clear. The washed wet filter cake is transferred to a vacuum drying oven and dried at 80°C to constant weight. The dried product is sieved to obtain surface epoxy functionalized PES micro powder.

[0045] Preparation Example 2: Preparation of Surface-Functionalized PES Micropowder The difference from Preparation Example 1 is that: (1) Raw material pretreatment: Place 100kg of PES micro powder in a vacuum drying oven and dry at 110℃ for 5 hours; (2) Preparation of coupling agent hydrolysate: Add 5 kg KH-560 to 100 kg of the first portion of anhydrous ethanol to obtain mixture A; take 2 kg of deionized water and slowly add glacial acetic acid dropwise while stirring to obtain mixture B with pH value of 5; slowly add mixture B dropwise to mixture A and stir at room temperature for 45 minutes to allow it to be fully hydrolyzed to obtain a clear and transparent pre-hydrolyzed solution; (3) Surface grafting reaction: Add 200 parts of the second part of anhydrous ethanol to the reaction vessel, start stirring, and slowly add the PES micro powder after pretreatment in step (1) to make it evenly dispersed and form a suspension; heat the reaction vessel to 50°C, and slowly add the pre-hydrolyzed solution in step (2) to the PES micro powder suspension while stirring; after the addition is completed, heat the reaction system to 80°C and continue the reaction under reflux for 5 hours.

[0046] Preparation Example 3: Preparation of Surface-Functionalized PES Micropowder The difference from Preparation Example 1 is that: (1) Raw material pretreatment: 110 kg of PES micro powder was placed in a vacuum drying oven and dried at 120°C for 4 hours to remove the surface moisture physically adsorbed. After cooling, it was ready for use. (2) Preparation of coupling agent hydrolysate: Add 8 kg KH-560 to 100 kg of the first portion of anhydrous ethanol to obtain mixture A; take 3 kg of deionized water and slowly add glacial acetic acid dropwise while stirring to obtain mixture B with pH value of 4; slowly add mixture B dropwise to mixture A and stir at room temperature for 30 minutes to allow it to be fully hydrolyzed to obtain a clear and transparent pre-hydrolyzed solution; (3) Surface grafting reaction: Add 200 parts of the second part of anhydrous ethanol to the reaction vessel, start stirring, and slowly add the PES micro powder after pretreatment in step (1) to disperse it evenly and form a suspension; heat the reaction vessel to 60°C, and slowly add the pre-hydrolyzed solution in step (2) to the PES micro powder suspension while stirring; after the addition is complete, heat the reaction system to 85°C and continue the reaction under reflux for 4 hours.

[0047] Example

[0048] Example 1 A method for preparing a non-flowing, press-bonded glass cloth-based epoxy prepreg sheet, employing the following technical solution: S1 Impregnation: The glass fiber cloth is pretreated at 120℃ for 3 hours to remove surface moisture and impurities; through an impregnation-extrusion process, the pretreated glass cloth is passed through an impregnation tank containing adhesive at a stable speed of 4.5m / min to ensure full penetration of the adhesive; after impregnation, the excess adhesive is squeezed out by a metering roller, and the resin content is controlled at 52% to obtain the prepreg wet material. S2 Semi-curing: The wet prepreg material obtained in step S2 is placed in a drying oven for segmented drying to obtain a semi-cured prepreg, as follows: Zone 1: 110℃, 2.5 minutes; Zone 2: 140℃, 3 minutes; Zone 3: 155℃, 1.5 minutes.

[0049] S3 Winding and Storage: After the semi-cured prepreg obtained in step S3 is cooled to room temperature by cooling rollers, a polyethylene release film is applied to the surface, and the product is wound up. The product should be sealed in packaging and stored in a clean environment.

[0050] The adhesive solution in step S1 is prepared according to the following method: S11 adds tetrafunctional epoxy resin, biphenyl epoxy resin and hydrogenated bisphenol A type epoxy resin to a reactor, stirs and mixes, heats to 75°C, and stirs at a constant temperature until the resin is completely melted and mixed evenly, and the system is transparent and homogeneous. Then it is cooled to 50°C for later use. S12 Add surface epoxy-functionalized polyethersulfone micro powder, submicron-sized spherical silica and aminosilanized nano-sized spherical silica sequentially to the resin mixture obtained in step S11, increase the stirring speed, vacuum degree -0.3MPa, and disperse at high speed of 1000rpm for 1 hour to fully wet the powder, disperse it evenly and without agglomeration particles. S13 Cool the mixture obtained in step S12 to 45°C, add phenolic resin and curing accelerator while stirring, reduce the stirring speed to 400 rpm, and continue mixing under vacuum for 30 minutes to completely dissolve and disperse the curing agent evenly. S14 uses an organic solvent to adjust the viscosity of the adhesive to 2000 mPa·s. After passing the adhesive through a 200-mesh sieve, it is discharged and allowed to stand to defoam before use.

[0051] The components and amounts of the adhesive solution are shown in Table 1, and the processing parameters in the preparation method are shown in Table 2.

[0052]

[0053] The surface epoxy-functionalized PES micropowder was prepared according to the preparation method of Example 2.

[0054] Example 2 The difference from Example 1 is that the composition and amount of the adhesive are shown in Table 1, the processing parameters in the preparation method are shown in Table 2, and the surface epoxy functionalized PES micro powder is prepared according to the scheme of Preparation Example 1.

[0055] Example 3 The difference from Example 1 is that the composition and amount of the adhesive are shown in Table 1, the processing parameters in the preparation method are shown in Table 2, and the surface epoxy functionalized PES micro powder is prepared according to the scheme of Preparation Example 3.

[0056] Examples 4-10 The difference from Example 1 is that the preparation method of the adhesive solution further includes adding a toughening agent in step S12 and adding a flame retardant in step S11; the component amounts of the adhesive solution are shown in Table 3.

[0057] Comparative Example Comparative Example 1 The difference from Example 1 is that the present example does not contain surface epoxy-functionalized PES micropowder.

[0058] Comparative Example 2 The difference from Example 1 is that it does not contain submicron-sized spherical silica.

[0059] Comparative Example 3 The difference from Example 1 is that the nanoscale spherical silica does not contain aminosilanized silica.

[0060] Comparative Example 4 The difference from Example 1 is that the curing accelerator contains only triphenylphosphine and does not contain imidazoles.

[0061] Comparative Example 5 The difference from Example 1 is that it does not contain KH-560 coupling agent.

[0062] Comparative Example 6 The difference from Example 1 is that the surface epoxy functionalized PES micro powder is replaced with ordinary unmodified PES micro powder.

[0063] Comparative Example 7 The difference from Example 10 is that the toughening agent and the curing agent are added together in step S13.

[0064] Performance testing Adhesive residue width after lamination: Tested according to IPC-TM-650 2.3.17; Copper foil peel strength: Tested according to IPC-TM-650 2.4.8; Glass transition temperature (Tg): Tested according to IPC-TM-650 2.4.25; Z-axis coefficient of thermal expansion (CTE): Tested according to IPC-TM-650 2.4.41; Dielectric constant (DK, 1GHz) and loss factor (Df, 1GHz): Tested according to IPC-TM-650 2.5.5; Flame retardant rating: Tested according to UL94; Impact strength: Tested according to GB / T 1843.

[0065] The glass cloth-based epoxy prepreg products prepared by the methods of Examples 1-10 and Comparative Examples 1-7 were subjected to the above performance tests, and the test results are shown in Table 4:

[0066]

[0067] As shown in Table 4, Example 1 has a pressing adhesive width of 0.5 mm, a copper foil peel strength of 1.08 kN / m, a glass transition temperature of 185℃, a Z-axis thermal expansion coefficient of 42 ppm / ℃, a dielectric constant of 3.86, a loss factor of 0.0057, and a flame retardant rating of V-1. All performance characteristics are well-balanced and excellent, verifying the rationality and feasibility of the formulation.

[0068] Example 6 exhibits the best overall performance, with an impact strength of 22.5 kJ / m², an 80% improvement over Example 1, a glue residue width of only 0.4 mm, a peel strength of 1.18 kN / m, a Tg maintained at 186℃, and a flame retardant rating of V-0, achieving a balance between toughening and reinforcement and glue flow suppression. Examples 4 and 5 also demonstrate good toughening effects, proving that the epoxy functional groups in the core-shell structure acrylate polymer shell are chemically bonded to the matrix to form "anchor points," significantly improving toughness while maintaining heat resistance.

[0069] Examples 7-9 show a significant improvement in flame retardant performance after the introduction of DOPO-based flame retardants. Examples 7 and 9 both achieved a V-0 rating, with the LOI improving from V-1 in Example 1 to V-0. Simultaneously, the CTE slightly improved, demonstrating the contribution of the rigid phosphorus-phenanthrene heterocyclic structure of DOPO to dimensional stability. Example 9 exhibited a peel strength of 1.10 kN / m, superior to the 1.05 kN / m of Example 7, indicating a synergistic effect between the flame retardant and toughening agent.

[0070] Example 10 simultaneously introduces toughening agent and flame retardant, achieving optimal overall performance with an impact strength of 20.5 kJ / m², a flame retardant rating of V-0, a copper foil peel strength of 1.15 kN / m, an adhesive residue width of 0.5 mm, a Tg of 184℃, and a CTE of 40 ppm / ℃. This demonstrates a synergistic effect of "flame retardant-flow suppression-toughness" and fully proves the synergistic effect of toughening agent and flame retardant.

[0071] Comparative Examples 1-6 systematically verified the necessity of each core component. In Comparative Example 1, without the addition of any surface-functionalized epoxy PES micropowder, the adhesive width increased to 6.2 mm (12.4 times that of Example 1), the peel strength decreased to 0.75 kN / m, and the Tg decreased to 168 °C, demonstrating that the surface-functionalized PES micropowder plays an irreplaceable role in inhibiting adhesive flow and enhancing the interface through chemical anchoring.

[0072] When Comparative Example 3 used only submicron-sized silica (excluding nano-sized silica), the CTE increased to 51 ppm / ℃ and the peel strength decreased to 0.88 kN / m. Both were significantly worse than those in Example 1, demonstrating that the "micron-nano" multi-level filling structure formed by submicron-sized and nano-sized silica is indispensable. Nanoparticles fill the gaps between micron-sized particles, increase the packing density, synergistically reduce the coefficient of thermal expansion, and enhance interfacial bonding.

[0073] When Comparative Example 4 used a single triphenylphosphine accelerator (without imidazole), the Tg dropped to 175°C and the adhesive width increased to 0.6 mm, which was significantly lower than that of Example 1. This demonstrates the necessity of using imidazole and triphenylphosphine compound accelerators to improve crosslinking density through synergistic catalysis and to optimize the curing curve through stepwise control.

[0074] When the KH-560 coupling agent was missing in Comparative Example 5, the peel strength decreased to 0.82 kN / m, and the adhesive width increased to 1.2 mm, demonstrating the dual interfacial strengthening effect of KH-560, which plays a key role in interfacial bonding and rheological regulation by condensing with the inorganic surface at one end and reacting with the resin matrix at the other end to form a "molecular bridge".

[0075] When ordinary unmodified PES micropowder was used to replace the surface epoxy functionalized product in Comparative Example 6, the peel strength dropped to 0.85 kN / m and the adhesive residue width was 1.5 mm, which was significantly different from 0.5 mm and 1.08 kN / m in Example 1. This further proves the necessity of surface functionalization treatment to transform PES micropowder from a "physical filler phase" to a "chemically involved phase".

[0076] Comparative Example 7 further verified the criticality of the order in which the toughening agent and flame retardant are added. The flame retardant is melt-blended with the epoxy resin matrix in step S11 to achieve chemical bonding, while the toughening agent is dispersed at high speed with the filler in step S12 to ensure uniform distribution. Both are indispensable and their order cannot be changed.

[0077] In summary, the non-flowing glass cloth-based epoxy prepreg prepared by this application achieves simultaneous breakthroughs in flow suppression, interface enhancement, heat resistance improvement, dimensional stability, flame retardant safety, and toughness optimization through the design of a triple mechanism of "chemical bonding-physical dispersion-functional synergy". In terms of adhesive flow control, surface-functionalized epoxy PES micropowder reduced the adhesive width from over 6 mm in conventional technologies to 0.5 mm; in terms of interfacial bonding, KH-560 coupling agent and aminated nano-silica increased the peel strength from 0.95 kN / m to 1.15 kN / m; in terms of heat resistance, compounded accelerator and DOPO rigid structure increased the Tg from 181℃ to 188℃; in terms of dimensional stability, the multi-level filler synergistic system reduced the CTE from 48 ppm / ℃ to 40 ppm / ℃; in terms of flame retardancy, DOPO flame retardant improved the flame retardancy rating from V-1 to V-0; and in terms of toughness, the core-shell toughening agent increased the impact strength from 12.5 kJ / m² to 22.5 kJ / m².

[0078] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the present invention, they are protected by patent law.

Claims

1. A non-flowing, press-fitted glass cloth-based epoxy prepreg, characterized in that, The prepreg is made by impregnating glass fiber cloth with adhesive and then subjecting it to a semi-curing process. The adhesive comprises the following raw materials in parts by weight: 35-45 parts tetrafunctional epoxy resin, 30-40 parts biphenyl epoxy resin, 10-20 parts hydrogenated bisphenol A type epoxy resin, 40-55 parts phenolic resin, 10-20 parts surface epoxy functionalized PES micro powder, 30-40 parts spherical silica, 0.3-0.8 parts curing accelerator, 0.5-1.5 parts KH-560, and organic solvent.

2. The non-flowing, press-bonded glass cloth-based epoxy prepreg according to claim 1, characterized in that, The preparation of the surface epoxy-functionalized PES micropowder includes the following steps: (1) Raw material pretreatment: Place PES micro powder in a vacuum drying oven and dry it at 100-120℃ for 4-6 hours to remove the physically adsorbed moisture on the surface. After cooling, it is ready for use. (2) Preparation of coupling agent hydrolysate: Add KH-560 to the first part of anhydrous ethanol to obtain mixture A; mix deionized water with glacial acetic acid to obtain mixture B with pH value of 4-5; slowly add mixture B to mixture A, stir at room temperature for 30-60 minutes to allow it to be fully hydrolyzed, and obtain a clear and transparent pre-hydrolyzed solution. (3) Surface grafting reaction: Add the second part of anhydrous ethanol to the reaction vessel, start stirring, and slowly add the PES micro powder pretreated in step S1 to disperse it evenly and form a suspension; heat the reaction vessel to 50-60℃, and slowly add the pre-hydrolyzed solution from step S2 to the PES micro powder suspension while stirring; after the addition is complete, heat the reaction system to 75-85℃ and continue the reaction under reflux for 4-6 hours; (4) Post-processing and drying: After the reaction is completed, the product is cooled to room temperature, the reaction product is centrifuged, the solid material is collected, and the solid material is washed multiple times with anhydrous ethanol until the washing liquid is clear. The washed wet filter cake is transferred to a vacuum drying oven and dried to constant weight. The dried product is sieved to obtain surface epoxy functionalized PES micro powder.

3. The non-flowing glass cloth-based epoxy prepreg sheet according to claim 2, characterized in that, The preparation of the surface epoxy functionalized PES micro powder includes the following raw materials in parts by weight: 90-110 parts of PES micro powder, 3-8 parts of KH-560, 100 parts of anhydrous ethanol, 1.5-3 parts of deionized water, and 200 parts of anhydrous ethanol.

4. The non-flowing, press-bonded glass cloth-based epoxy prepreg according to claim 1, characterized in that, The spherical silica comprises the following raw materials in parts by weight: 20-25 parts of submicron-sized spherical silica and 10-15 parts of aminosilanized nano-sized spherical silica.

5. The non-flowing, press-bonded glass cloth-based epoxy prepreg according to claim 1, characterized in that, The curing accelerator is an imidazole accelerator and triphenylphosphine in a weight ratio of 1:(2-5), wherein the imidazole accelerator is selected from any one of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole.

6. The non-flowing glass cloth-based epoxy prepreg sheet according to claim 1, characterized in that, It also includes 5-12 parts of a toughening agent, wherein the toughening agent is a core-shell structured acrylate polymer.

7. The non-flowing, press-bonded glass cloth-based epoxy prepreg according to claim 1, characterized in that, It also includes 10-20 parts of flame retardant, wherein the flame retardant is any one of DOPO and DOPO derivatives.

8. A method for preparing a non-flowing, press-bonded glass cloth-based epoxy prepreg as described in any one of claims 1-7, characterized in that, The following technical solution is adopted: S1 Impregnation: The glass fiber cloth is pretreated to remove surface moisture and impurities; through the impregnation-extrusion process, the pretreated glass cloth is passed through the impregnation tank containing the adhesive solution at a stable speed to ensure that the adhesive solution is fully impregnated; after impregnation, the excess adhesive solution is squeezed out by the metering roller to control the resin content and obtain the prepreg wet material. S2 Semi-cured: The wet prepreg material obtained in step S2 is placed in a drying oven for segmented drying to obtain a semi-cured prepreg. S3 Winding and Storage: After the semi-cured prepreg obtained in step S3 is cooled to room temperature by cooling rollers, a polyethylene release film is applied to the surface, and the product is wound up. The product should be sealed in packaging and stored in a clean environment.

9. The method for preparing the non-flowing glass cloth-based epoxy prepreg sheet according to claim 8, characterized in that, The adhesive solution in step S1 is prepared according to the following method: S11 adds tetrafunctional epoxy resin, biphenyl epoxy resin and hydrogenated bisphenol A type epoxy resin to a reactor, stirs and mixes, heats to 70-80℃, and stirs at a constant temperature until the resin is completely melted and mixed evenly, and the system is transparent and homogeneous. Then cools down to 40-60℃ for later use. S12 Add surface epoxy-functionalized polyethersulfone micro powder, submicron-sized spherical silica and aminosilanized nano-sized spherical silica sequentially to the resin mixture obtained in step S11, increase the stirring speed, and disperse at high speed under vacuum conditions to make the powder fully wetted, uniformly dispersed and free of agglomerated particles. S13 Cool the mixture obtained in step S12 to 40-50℃, add phenolic resin and curing accelerator while stirring, reduce the stirring speed, and continue mixing under vacuum conditions to completely dissolve and evenly disperse the curing agent. S14 uses organic solvents to adjust the viscosity of the adhesive to 1800-2200 mPa·s. After passing the adhesive through a 150-250 mesh sieve, it is discharged and allowed to stand to defoam before use.

10. The method for preparing the non-flowing glass cloth-based epoxy prepreg sheet according to claim 8, characterized in that, The segmented drying process in step S2 is as follows: Zone 1: 100-120℃, 2-3 minutes; Zone 2: 135-145℃, 2-4 minutes; Zone 3: 150-160℃, 1-2 minutes.

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