A uv-cured material for ffc and a method of making the same
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DONGGUAN SHIYOU ADHESIVE MATERIALS CO LTD
- Filing Date
- 2026-06-10
- Publication Date
- 2026-08-07
AI Technical Summary
1.固化效率极低：传统热固化树脂如环氧树脂需60-120分钟才能完全固化，单件封装耗时久，生产线效率≤500件/小时，且加热能耗占工艺成本的30%以上；
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a UV-curable material for FFC and its preparation method. Background Technology
[0002] FFC connectors (flexible flat cable connectors) are widely used in compact space connections due to their flexibility and thinness, but current technology still faces two major bottlenecks: (I) Performance and process limitations of encapsulating resins 1. Extremely low curing efficiency: Traditional thermosetting resins such as epoxy resin require 60-120 minutes to fully cure, resulting in long single-piece encapsulation time, production line efficiency of ≤500 pieces / hour, and heating energy consumption accounting for more than 30% of the process cost. 2. Poor high voltage adaptability: The current tracking index (CTI) of existing resins is mostly ≤400V, which cannot meet the insulation requirements of high voltage systems above 1000V in new energy vehicle electronics, and is prone to high voltage breakdown risk; 3. Poor resistance to electrolytes: When electrolytes (such as coolant and battery electrolyte) leak in automotive electronics, the bonding strength of traditional resins decreases by ≥30% after 24 hours of immersion, or even cracks, leading to connector failure. 4. Insufficient mechanical properties: The bonding strength of flexible resins is mostly ≤80kg / cm². 2 Pressure strength ≤120kg / cm 2 It cannot withstand the external pressure during the assembly and use of FFC.
[0003] (ii) Process compatibility defects of packaging structure Traditional thermosetting processes require high-temperature ovens, which can easily cause thermal deformation of the FFC insulation film; moreover, the curing cycle is long, which cannot meet the high-volume production requirements of consumer electronics and restricts the reduction of production costs.
[0004] Therefore, there is an urgent need to develop modified acrylate UV-curable resins to achieve second-level curing, high mechanical strength, high voltage insulation, electrolyte resistance, and a rapid assembly process suitable for FFC packaging structures, thus solving its pain points. Summary of the Invention
[0005] The purpose of this invention is to provide a UV-curable material for FFC and a method for preparing the same, so as to solve the problems mentioned in the background art.
[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a UV curing material for FFC, comprising the following components by mass: 50-60 parts of base resin, 3-5 parts of photoinitiator, 15-20 parts of reactive diluent, 8-12 parts of reinforcing filler, 2-4 parts of additives, and 1-2 parts of electrolyte-resistant modifier.
[0007] Furthermore, the base resin is a blend of epoxy-modified acrylate and polyurethane-modified acrylate in a mass ratio of 8:3. The epoxy-modified acrylate improves the bond strength and CTI value, while the polyurethane-modified acrylate provides flexibility and electrolyte resistance.
[0008] Furthermore, the photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173) and benzophenone (photoinitiator BP) in a mass ratio of 4:3. Photoinitiator 1173 promotes rapid curing of the resin surface, while photoinitiator BP enhances deep curing and is compatible with 365-405nm UV light sources.
[0009] Furthermore, the reactive diluent is trimethylolpropane triacrylate (TMPTA) and isobornyl acrylate (IBOA) in a mass ratio of 5:4. TMPTA increases the crosslinking density of the resin, ensuring material strength; IBOA reduces the viscosity of the cured material, adapting to the dispensing process and reducing the viscosity of the cured resin.
[0010] Furthermore, the reinforcing filler is nano-alumina and fumed silica in a mass ratio of 3:2; nano-alumina improves the CTI value and electrolyte resistance, while fumed silica prevents sedimentation and improves thixotropy.
[0011] Furthermore, the additives include adhesion promoters, antioxidants, and defoamers in a mass ratio of 2:1:1; The adhesion promoter is γ-methacryloyloxypropyltrimethoxysilane (KH-570), which enhances the adhesion between the resin and the FFC insulating film and contacts. The antioxidant is the hindered amine light stabilizer HALS, which delays aging and ensures long-term temperature resistance; The defoamer is an organosilicone defoamer, which prevents bubbles from forming during dispensing and ensures insulation performance.
[0012] Furthermore, the electrolyte-resistant modifier is a perfluoroalkyl acrylate, which reduces electrolyte permeability and mitigates performance degradation.
[0013] In the above technical solution, by setting the components of the curing material, a combination of rapid curing, high mechanical properties, high insulation properties and electrolyte resistance is achieved, thereby improving the overall performance of the cured product.
[0014] A method for preparing a UV-curable material for FFC includes the following processes: Step 1: Preparation of UV-curable resin: Mix the base resin, reactive diluent, electrolyte-resistant modifier and additives, and stir once; add filler and stir twice; finally add photoinitiator, stir again, degas, and obtain UV-curable resin; Step 2, Curing: Apply UV-curing resin to the area to be encapsulated, and irradiate with UV light to obtain UV-cured material.
[0015] Furthermore, the process of one stirring step is to stir at 400-600 r / min for 8-15 min; The secondary stirring process involves stirring at 700–900 r / min for 15–25 min; The second stirring process involves stirring at 200–400 rpm for 3–8 minutes. The degassing process involves vacuum degassing at -0.085 to -0.095 MPa for 2 to 5 minutes. The viscosity of UV-curable resin can be controlled at 450–550 mPa·s at 25°C.
[0016] Furthermore, the UV irradiation employs a UV-LED light source with a UV wavelength of 365nm and an energy density of 750–850mW / cm². 2 ; The UV irradiation process involves irradiating for 1–3 seconds to achieve surface positioning and curing, at which point the resin bonding strength is ≥50 kg / cm². 2 It can be detached from the clamp; Then, irradiation continues for a total duration of 12–18 seconds to achieve deep curing with a full-layer curing degree of ≥95%.
[0017] Furthermore, the epoxy-modified acrylate is prepared by the following process: Mix epoxy resin, reactive diluent, and polymerization inhibitor, heat to 90-95℃, and stir until homogeneous; slowly add the premixed solution of acrylic acid and catalyst over 60-90 minutes, and then stir and react at 95-110℃ for 2-5 hours until the acid value drops below 5 mg KOH / g and the epoxy value is ≤0.02 mol / 100g, to obtain epoxy-modified acrylate.
[0018] Furthermore, the molar ratio of epoxy groups, acrylic acid, and catalyst in the epoxy resin is 1:(1.05–1.10):(0.5–1.0)%; The amount of reactive diluent used is 30-70% of the mass of epoxy resin; The polymerization inhibitor is p-hydroxyanisole, and the dosage is 200-500 ppm (based on total mass). The catalyst is one of triethylamine, N,N-dimethylbenzylamine, and triphenylphosphine.
[0019] Furthermore, the epoxy resin is one or a mixture of two of E44 and branched epoxy resin.
[0020] Furthermore, the branched epoxy resin is prepared by the following process: Bisphenol compound, decyl lactone and organic catalyst were mixed and reacted at 140-150℃ for 10-16 h with stirring. The mixture was dissolved in acetone, washed with KOH solution, and the oil phase was collected. Ethyl acetate was added, and the mixture was washed with water. The oil phase was then distilled under reduced pressure to obtain polydecyl lactone bisphenol. Under a nitrogen atmosphere, polydecyl lactone diol, trimethyloltriglycidyl ether, and catalyst were mixed and refluxed at 80–90 °C for 3.5–4.5 h. After cooling, tetrahydrofuran was added to dissolve the mixture, water was added, and the mixture was separated. This process was repeated 2–3 times. The organic phase was then dried under vacuum to obtain the branched epoxy resin.
[0021] Furthermore, the bisphenol compound is a mixture of bisphenol A and hexafluorobisphenol A in a molar ratio of (1-3):1; it is pre-melted and mixed uniformly at 80-90°C before use; The molar ratio of decanolide to bisphenol compounds is (6–10):1; The organic catalyst is diphenyl phosphate, and its dosage is 2-3% of the monomer molar fraction.
[0022] Furthermore, the mass ratio of polydecyl lactone diol, trimethylolpropane triglycidyl ether, and catalyst is 100:(25-40):(0.5-1.0). The catalyst is tetramethylammonium bromide.
[0023] In the above technical solution, decanolactone undergoes ring-opening reaction with bisphenol A and hexafluorobisphenol A to prepare polydecanolide diphenol. The phenolic hydroxyl group of polydecanolide diphenol undergoes a ring-opening addition reaction with the epoxy group of trimethylolpropane triglycidyl ether to form a branched structure, thus obtaining a branched epoxy resin. Subsequently, the carboxyl group of acrylic acid undergoes a ring-opening reaction with the epoxy group at the end of the branched epoxy resin to generate a hydroxy ester, and an acryloyloxy group is grafted to the end of the molecular chain to obtain an epoxy-modified acrylate.
[0024] Decanolide, as a soft segment and flexible spacer, provides excellent chain mobility through its ring-opening polymerization, enhancing the flexibility of epoxy-modified acrylates. The resulting UV-cured materials exhibit higher flexural strength and crack resistance. The benzene ring structure in bisphenol compounds provides rigidity and strength, strengthening and promoting adhesion; its moderate polarity facilitates adhesion between UV-cured materials and FFC materials. The fluoroisopropyl structure in hexafluorobisphenol A has strong electron-withdrawing properties, reducing surface energy, maintaining surface cleanliness, preventing surface leakage current, and improving insulation performance. Furthermore, the strong electronegativity of fluorine atoms binds electrons, reducing conductivity and increasing volume resistivity and CTI; while the high chemical inertness of the CF bond enhances resistance to electrolytes, acids, and alkalis, improving chemical resistance. The resulting branched structure increases crosslinking density, leading to a denser three-dimensional network after curing, further improving strength, adhesion, and chemical resistance.
[0025] During curing, the fluorinated segments of hexafluorobisphenol A tend to migrate to the material-environment interface, forming a fluorine-rich, hydrophobic, and electrolyte-resistant surface layer; while the main body of the material and the interface in contact with the substrate retain more of the bisphenol A structure to maintain its strong adhesion; and it has high CTI and high volume resistivity, meeting the high voltage insulation requirements of FFC.
[0026] Furthermore, the polyurethane-modified acrylate is prepared by the following process: 2,6-Dimethyl-4-aminopyridine, decanolide and organic catalyst were mixed and stirred for 8-20 h; acetone was added, and the mixture was washed with KOH solution. The oil phase was taken, ethyl acetate was added, and the mixture was washed with water. The oil phase was then distilled under reduced pressure to obtain polydecanolide diol. Isophorone diisocyanate, dibutyltin dilaurate, and ethyl acetate were mixed and heated to 38–42°C. Triethylene glycol was added over 30–40 minutes, followed by a reaction at 48–52°C for 1.5–2.0 hours. The temperature was then raised to 58–62°C, and polydecyl lactone diol was added over 30–40 minutes, followed by a reaction at 68–72°C for 1.5–2.0 hours. The temperature was then raised to 78–82°C, and p-hydroxyanisole and hydroxyethyl acrylate were added, followed by a reaction at 78–82°C for 2.5–3.0 hours. The ethyl acetate was removed by vacuum distillation to obtain polyurethane-modified acrylate.
[0027] Furthermore, the molar ratio of decanolide to 2,6-diethanol-4-aminopyridine is (4-10):1; The organic catalyst is diphenyl phosphate, used in amounts ranging from 1.8% to 4.0% of the monomer molar fraction. The OKH solution concentration is 1 wt%.
[0028] Furthermore, the polyurethane-modified acrylate comprises the following components by weight: 8.9–10.0 parts isophorone diisocyanate, 0.018–0.030 parts dibutyltin dilaurate, 1.8–2.2 parts triethylene glycol, 10.5–12.5 parts polydecyl lactone diol, 0.04–0.08 parts p-hydroxyanisole, 1.9–2.2 parts hydroxyethyl acrylate, and 15–25 parts ethyl acetate.
[0029] Furthermore, the 2,6-dimethyl-4-aminopyridine is amino-protected before use and deprotected before the preparation of polyurethane-modified acrylate. The specific process is as follows: Amino protection: Under a nitrogen atmosphere, 2,6-dimethyl-4-aminopyridine was dissolved in anhydrous tetrahydrofuran, and triethylamine and 4-dimethylaminopyridine were added at 0–5 °C, followed by a tetrahydrofuran solution of di-tert-butyl dicarbonate. The reaction was then stirred at 25 ± 5 °C for 12–16 h. After the reaction, the mixture was quenched with a saturated ammonium chloride aqueous solution, extracted with ethyl acetate, and the organic phases were combined, washed, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to obtain Boc-protected 2,6-dimethyl-4-aminopyridine. Deprotection: Boc-protected polydecyl lactone diol was dissolved in dichloromethane and trifluoroacetic acid was added at 0–5 °C. The mixture was then stirred at 25 ± 5 °C for 2–4 h. Saturated sodium bicarbonate solution was added in an ice bath, and the aqueous phase was extracted with ethyl acetate. The organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate. The mixture was filtered and distilled under reduced pressure to obtain polydecyl lactone diol.
[0030] Furthermore, the molar ratio of 2,6-dimethylethanol-4-aminopyridine, ditert-butyl dicarbonate, and triethylamine is 1:1.2:1.5; The amount of anhydrous tetrahydrofuran used is 8 to 12 times the mass of 2,6-dimethyl-4-aminopyridine. The concentration of the tetrahydrofuran solution of di-tert-butyl dicarbonate is 1.0–1.5 mol / L.
[0031] Furthermore, the amount of dichloromethane used is 5 to 10 times the mass of the Boc-protected polydecyl lactone diol; The volume ratio of trifluoroacetic acid to Boc-protected polydecyl lactone diol is (2-3):1.
[0032] In the above technical solution, the amino group in 2,6-dimethyl-4-aminopyridine can initiate chain growth. Therefore, it is protected beforehand to avoid amino group consumption, so that it can participate in the subsequent preparation of polyurethane acrylates. Decanolide ring-opening reacts with the hydroxyl group of 2,6-dimethyl-4-aminopyridine to obtain polydecanolide diol, which is then used to prepare a polyurethane-modified acrylate UV-curable resin with long carbon chains and urea groups. The long chains formed by decanolide provide flexibility and low-temperature resistance. The polarity of urea bonds and their ability to form hydrogen bonds are stronger than those of urethane bonds. As physical crosslinking points, they can reversibly open and recombine under external force, absorbing energy, thereby improving the toughness, heat resistance, and chemical resistance of polyurethane-modified acrylates and UV-curable materials. The polar urea / urethane hard segments and the non-polar polydecyl lactone soft segments are thermodynamically incompatible, forming a nanoscale microphase separation structure. The hard segment region provides strength and heat resistance as a physical cross-linking point, while the soft segment region provides flexibility and elasticity. It can also effectively extend the diffusion path of small molecule solvents such as electrolytes, improve the material's permeability resistance and swelling resistance, and work together with the fluorine element in the system to form a strong anti-permeability barrier.
[0033] In the above technical solution, in the formulation of the UV curing material, (1) the acrylate double bonds of epoxy modified acrylate and polyurethane modified acrylate undergo a copolymerization reaction with the reactive diluent under photoinitiation to form an interpenetrating, covalently linked hybrid network. The epoxy phase with high crosslinking density and the flexible polyurethane phase form a rigid and flexible network structure with micro-phase separation. When subjected to external extrusion and bending, the flexible phase can dissipate stress and prevent the rigid phase from cracking or peeling off from the interface, effectively resisting the mechanical deformation and stress concentration imposed by the external environment. (2) The rigid aromatic ring and high crosslinking density of epoxy resin improve strength; the urea bond hydrogen bond network and micro-phase separation structure of polyurethane improve toughness and achieve a balance of mechanical properties. (3) The bisphenol A structure provides good adhesion; KH-570 silane forms Si-O-Si covalent bonds with the substrate through its hydrolyzed silanol, so that the cured material forms a strong adhesion between the FFC insulating film and the metal contact parts. The migration / enrichment of fluorine atoms on the surface of the curing system and the microphase separation of polyurethane give UV-cured materials good electrolyte resistance and long-term reliability at the interface and in the material itself.
[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes a blend of epoxy-modified acrylate and polyurethane-modified acrylate as a photocurable polymer resin, achieving UV-curing in seconds, far shorter than the traditional thermocuring time of epoxy resin. This significantly improves mass production efficiency, greatly increasing daily production capacity, and eliminates the need for heating equipment, reducing energy consumption and costs. The increased resin CTI makes it compatible with high-voltage cockpit systems in new energy vehicles, avoiding the risk of high-voltage breakdown. It exhibits excellent adhesion, resistance to extrusion deformation, and electrolyte resistance, with no degradation after 24 hours. It balances flexibility and stability, demonstrating excellent mechanical and environmental resistance properties. It is compatible with the connector packaging structure of flexible flat cables (FFC) and suitable for flexible signal transmission scenarios requiring rapid mass production and high voltage reliability, such as consumer electronics (e.g., foldable phones, laptops) and new energy vehicle electronics (e.g., high-voltage cockpit systems). Detailed Implementation
[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0036] Unless otherwise specified, the experimental methods used in the following examples were performed under standard conditions or conditions recommended by the manufacturer. All reagents and instruments used, unless otherwise specified, are commercially available products. There are no special restrictions on the suppliers of any of the raw materials involved in this invention; exemplary examples include: Commercially available products: Epoxy-modified acrylate: Sartoma CN120NS; Polyurethane-modified acrylate: Zhanxin EBECRYL8413; The reactive diluents involved in the composition and preparation process are included in the component dosage of the UV-curable material; Base resin: a blend of epoxy-modified acrylate and polyurethane-modified acrylate in a mass ratio of 8:3; Photoinitiator: a blend of photoinitiator 1173 and photoinitiator BP in a mass ratio of 4:3; Reactive diluent: trimethylolpropane triacrylate and isobornyl acrylate in a mass ratio of 5:4; Reinforcing filler: nano-alumina (D50=50nm) and fumed silica (D50=15nm) in a mass ratio of 3:2; Additives: adhesion promoter KH-570, antioxidant HALS, and defoamer Leibang SR-540 in a mass ratio of 2:1:1; Electrolyte resistance modifier: perfluoroalkyl acrylate; Organic catalyst: diphenyl phosphate, and catalyst: triphenylphosphine. The UV irradiation uses a UV-LED light source with a UV wavelength of 365nm and an energy density of 800mW / cm². 2 The coating process utilizes an automated dispensing machine. Amine protection of 2,6-diethanol-4-aminopyridine: Under a nitrogen atmosphere, 2,6-diethanol-4-aminopyridine was dissolved in 10 times its weight of anhydrous tetrahydrofuran. The mixture was cooled to 2±2℃, and triethylamine and 4-dimethylaminopyridine were added. Then, a tetrahydrofuran solution of 1.2 mol / L ditert-butyl dicarbonate was slowly added. After the addition was complete, the mixture was brought back to room temperature and stirred at 25±5℃ for 14 h. The reaction was quenched with saturated ammonium chloride aqueous solution, extracted with ethyl acetate, and the organic phases were combined, washed, dried with anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to obtain Boc-protected 2,6-diethanol-4-aminopyridine. The molar ratio of 2,6-diethanol-4-aminopyridine, ditert-butyl dicarbonate, and triethylamine was 1:1.2:1.5. Deprotection: Boc-protected polydecyl lactone diol was dissolved in 8 times its mass of dichloromethane, cooled to 2±2℃, and 2.5 times its volume of trifluoroacetic acid was slowly added; after the addition was complete, the mixture was brought back to room temperature and stirred at 25±5℃ for 3 hours; after the reaction, saturated sodium bicarbonate solution was added under ice bath conditions, and the aqueous phase was extracted with ethyl acetate; the organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate; the mixture was filtered and distilled under reduced pressure to obtain polydecyl lactone diol; Example 1: A method for preparing a UV-curable material for FFC, comprising the following processes: Step 1: Preparation of the base resin: 1.1. Bisphenol A and hexafluorobisphenol A in a molar ratio of 3:1 were melt-mixed at 80°C to obtain a bisphenol compound; the bisphenol compound was mixed with 6 molar amounts of decanolide and 2 mol% organic catalyst, and stirred at 140°C for 10 h; acetone was added, and the mixture was washed with KOH solution, the oil phase was collected, ethyl acetate was added, and the mixture was washed with water. The oil phase was then distilled under reduced pressure to obtain polydecanolide diol; Under a nitrogen atmosphere, polydecyl lactone bisphenol, trimethylol triglycidyl ether, and tetramethylammonium bromide were mixed and refluxed at 80°C for 3.5 h; the mixture was cooled to 30°C, dissolved in tetrahydrofuran, and water was added. The mixture was separated and the reaction was repeated three times. The organic phase was dried under vacuum at 80°C and -0.10 MPa for 24 h to obtain branched epoxy resin. The mass ratio of polydecyl lactone bisphenol, trimethylol triglycidyl ether, and tetramethylammonium bromide was 100:25:0.5. Epoxy resin, 30wt% reactive diluent, and 400ppm polymerization inhibitor were mixed and heated to 90℃, then stirred until homogeneous. A premix of acrylic acid and catalyst was slowly added over 60 minutes. After addition, the mixture was stirred at 95℃ until the acid value dropped below 5mgKOH / g and the epoxy value ≤0.02mol / 100g, yielding epoxy-modified acrylate. The epoxy resin was a blend of E44 and branched epoxy resin in a mass ratio of 9:1. The molar ratio of epoxy groups, acrylic acid, and catalyst in the epoxy resin was 1:1.05:0.5%. 1.2. Boc-protected 2,6-diethanol-4-aminopyridine and decanolide were mixed with 1.8 mol% organic catalyst and stirred for 8 h. After the reaction, the mixture was dissolved in acetone, washed with 1 wt% KOH solution, and the oil phase was collected. Ethyl acetate was added, and the mixture was washed with water. The oil phase was then distilled under reduced pressure to obtain Boc-protected polydecanolide diol. Deprotection was performed to obtain polydecanolide diol. The molar ratio of decanolide to Boc-protected 2,6-diethanol-4-aminopyridine was 4:1. Isophorone diisocyanate, dibutyltin dilaurate, and ethyl acetate were mixed and heated to 40°C. Triethylene glycol was added over 30 minutes, and the mixture was reacted at 50°C for 1.5 hours. The temperature was then raised to 60°C, and polydecyl lactone diol was added over 30 minutes, followed by a reaction at 70°C for 1.5 hours. The temperature was then raised to 80°C, and p-hydroxyanisole and hydroxyethyl acrylate were added, followed by a reaction at 80°C for 2.5 hours. After the reaction was completed, the mixture was distilled under reduced pressure to obtain polyurethane-modified acrylate. The polyurethane-modified acrylate comprises the following components by mass: 10.0 parts isophorone diisocyanate, 0.018 parts dibutyltin dilaurate, 2.2 parts triethylene glycol, 10.5 parts polydecyl lactone diol, 0.08 parts p-hydroxyanisole, 2.2 parts hydroxyethyl acrylate, and 20 parts ethyl acetate. Step 2: Preparation of UV-curable resin: The base resin, reactive diluent, electrolyte-resistant modifier, and additives are mixed and stirred at 500 rpm for 10 min; filler is added and stirred at 800 rpm for 20 min; finally, photoinitiator is added and stirred at 300 rpm for 5 min, followed by vacuum degassing at -0.090 MPa for 3 min to obtain UV-curable resin; the UV-curable material comprises the following components by weight: 55 parts base resin, 3.5 parts photoinitiator, 18 parts reactive diluent, 10 parts reinforcing filler, 2 parts additives, and 1 part electrolyte-resistant modifier; Step 3: Curing: A UV-curable resin is applied to the area to be packaged, and then UV-irradiated (first irradiated for 2 seconds to remove from the fixture, then irradiated for 13 seconds for deep curing) to obtain a UV-curable material.
[0037] Example 2: A method for preparing a UV-curable material for FFC, comprising the following processes: Step 1: Preparation of the base resin: 1.1. Bisphenol A and hexafluorobisphenol A in a molar ratio of 2:1 were melt-mixed at 85°C to obtain a bisphenol compound; the bisphenol compound was mixed with 8 molar amounts of decanolide and 2.5 mol% organic catalyst, and stirred at 145°C for 13 h; acetone was added, and the mixture was washed with KOH solution, the oil phase was collected, ethyl acetate was added, and the mixture was washed with water. The oil phase was then distilled under reduced pressure to obtain polydecanolide diol; Under a nitrogen atmosphere, polydecyl lactone bisphenol A, trimethyloltriglycidyl ether, and tetramethylammonium bromide were mixed and refluxed at 85°C for 4 hours. The mixture was then cooled to 30°C, dissolved in tetrahydrofuran, and water was added. The mixture was separated and the reaction was repeated three times. The organic phase was dried under vacuum at 80°C and -0.10 MPa for 22 hours to obtain a branched epoxy resin. The mass ratio of polydecyl lactone bisphenol A, trimethyloltriglycidyl ether, and tetramethylammonium bromide was 100:32:0.8. Epoxy resin, 30wt% reactive diluent, and 400ppm polymerization inhibitor were mixed and heated to 92℃, then stirred until homogeneous. A premix of acrylic acid and catalyst was slowly added over 75 minutes. After addition, the mixture was stirred at 103℃ until the acid value dropped below 5mgKOH / g and the epoxy value ≤0.02mol / 100g, yielding epoxy-modified acrylate. The epoxy resin was a blend of E44 and branched epoxy resin in a mass ratio of 8:2. The molar ratio of epoxy groups, acrylic acid, and catalyst in the epoxy resin was 1:1.08:0.8%. 1.2. Boc-protected 2,6-diethanol-4-aminopyridine and decanolide were mixed with 3 mol% organic catalyst and stirred for 14 h. After the reaction, the mixture was dissolved in acetone, washed with 1 wt% KOH solution, and the oil phase was collected, ethyl acetate was added, washed with water, and the oil phase was distilled under reduced pressure to obtain Boc-protected polydecanolide diol. Deprotection was performed to obtain polydecanolide diol. The molar ratio of decanolide to 2,6-diethanol-4-aminopyridine was 8:1. Isophorone diisocyanate, dibutyltin dilaurate, and ethyl acetate were mixed and heated to 40°C. Triethylene glycol was added over 35 minutes, and the mixture was reacted at 50°C for 1.8 hours. The temperature was then raised to 60°C, and polydecyl lactone diol was added over 35 minutes, and the mixture was reacted at 70°C for 1.8 hours. The temperature was then raised to 80°C, and p-hydroxyanisole and hydroxyethyl acrylate were added, and the mixture was reacted at 80°C for 2.8 hours. The ethyl acetate was removed by vacuum distillation to obtain polyurethane-modified acrylate. The polyurethane-modified acrylate comprises the following components by mass: 9.5 parts isophorone diisocyanate, 0.024 parts dibutyltin dilaurate, 2.0 parts triethylene glycol, 11.5 parts polydecyl lactone diol, 0.06 parts p-hydroxyanisole, 2.0 parts hydroxyethyl acrylate, and 20 parts ethyl acetate. Steps two and three are the same as in Example 1.
[0038] Example 3: A method for preparing a UV-curable material for FFC, comprising the following processes: Step 1: Preparation of the base resin: 1.1. Bisphenol A and hexafluorobisphenol A in a molar ratio of 3:1 were melt-mixed at 80-90°C to obtain a bisphenol compound; the bisphenol compound was mixed with 10 molar amounts of decanolide and 3 mol% organic catalyst, and stirred at 150°C for 16 h; it was dissolved in acetone, washed with KOH solution, and the oil phase was collected. Ethyl acetate was added, and the mixture was washed with water. The oil phase was then distilled under reduced pressure to obtain polydecanolide diol. Under a nitrogen atmosphere, polydecyl lactone bisphenol, trimethylol triglycidyl ether, and tetramethylammonium bromide were mixed and refluxed at 90°C for 4.5 h. After cooling to 30°C, tetrahydrofuran was added to dissolve the mixture, water was added, and the mixture was separated. This process was repeated three times. The organic phase was then dried under vacuum at 80°C and -0.10 MPa for 24 h to obtain a branched epoxy resin. The mass ratio of polydecyl lactone bisphenol, trimethylol triglycidyl ether, and tetramethylammonium bromide was 100:40:1.0. Epoxy resin, 30wt% reactive diluent, and 400ppm polymerization inhibitor were mixed and heated to 95℃, then stirred until homogeneous. A premix of acrylic acid and catalyst was slowly added over 90 minutes. After addition, the mixture was stirred at 110℃ until the acid value dropped below 5mgKOH / g and the epoxy value ≤0.02mol / 100g, yielding epoxy-modified acrylate. The epoxy resin was a blend of E44 and branched epoxy resin in a mass ratio of 7:3. The molar ratio of epoxy groups, acrylic acid, and catalyst in the epoxy resin was 1:1.10:1.0%. 1.2. Boc-protected 2,6-diethanol-4-aminopyridine and decanolide were mixed with 4.0 mol% organic catalyst and stirred for 20 h. After the reaction, the mixture was dissolved in acetone, washed with 1 wt% KOH solution, and the oil phase was collected, ethyl acetate was added, washed with water, and the oil phase was distilled under reduced pressure to obtain Boc-protected polydecanolide diol. Deprotection was performed to obtain polydecanolide diol. The molar ratio of decanolide to 2,6-diethanol-4-aminopyridine was 10:1. Isophorone diisocyanate, dibutyltin dilaurate, and ethyl acetate were mixed and heated to 40°C. Triethylene glycol was added, and the mixture was allowed to complete the addition within 40 minutes. The reaction was then carried out at 50°C for 2.0 hours. The temperature was raised to 60°C, and polydecyl lactone diol was added, and the mixture was allowed to complete the addition within 40 minutes. The reaction was then carried out at 70°C for 2.0 hours. The temperature was raised to 80°C, and p-hydroxyanisole and hydroxyethyl acrylate were added. The reaction was carried out at 80°C for 3.0 hours. The ethyl acetate was removed by vacuum distillation to obtain polyurethane-modified acrylate. The polyurethane-modified acrylate contained the following components by mass: 8.9 parts isophorone diisocyanate, 0.030 parts dibutyltin dilaurate, 1.8 parts triethylene glycol, 12.5 parts polydecyl lactone diol, 0.04 parts p-hydroxyanisole, 1.9 parts hydroxyethyl acrylate, and 20 parts ethyl acetate. Steps two and three are the same as in Example 1.
[0039] Comparative Example 1: A method for preparing a UV-curable material for FFC, comprising the following processes: 1.1. Bisphenol A was mixed with 6 moles of decanolide and 2 mol% organic catalyst and stirred at 140 °C for 10 h. It was dissolved in acetone, washed with KOH solution, and the oil phase was collected. Ethyl acetate was added, and the oil phase was washed with water. The oil phase was then distilled under reduced pressure to obtain polydecanolide diol. The other process steps are the same as in Example 1.
[0040] Comparative Example 2: A method for preparing a UV-curable material for FFC, comprising the following processes: In step one, the epoxy-modified acrylate is replaced with an equal mass of commercially available products; The other process steps are the same as in Example 1.
[0041] Comparative Example 3: A method for preparing a UV-curable material for FFC, comprising the following processes: 1.2. 2,5-pyridinediethanol, decyl lactone and 1.8 mol% organic catalyst were mixed and stirred for 8 h. After the reaction, the mixture was dissolved in acetone, washed with 1 wt% KOH solution, and the oil phase was added to ethyl acetate, washed with water, and the oil phase was distilled under reduced pressure to obtain polydecyl lactone diol. The molar ratio of decyl lactone to 2,5-pyridinediethanol was 4:1. The other process steps are the same as in Comparative Example 2.
[0042] Comparative Example 4: A method for preparing a UV-curable material for FFC, comprising the following processes: Steps one and two are the same as steps two and three in Example 1. Both epoxy-modified acrylate and polyurethane-modified acrylate are commercially available products.
[0043] Comparative Example 5: A method for preparing a curing material for FFC, comprising the following processes: Mix 50 parts of epoxy resin E-51, 25 parts of silica powder filler, and 1 part of coupling agent KH-560. Stir at 300 rpm for 30 minutes at 80°C. Cool to 30°C, add 40 parts of curing agent methylhexahydrophthalic anhydride and 0.5 parts of accelerator 2,4,6-tris(dimethylaminomethyl)phenol, stir at 200 rpm for 10 minutes, degas under vacuum, and then apply. Cure at 100°C for 2 hours, and then at 150°C for 4 hours. All parts are by weight.
[0044] Experiment: The cured materials obtained in Examples 1-3 and Comparative Examples 1-5 were designated as encapsulation layers with a thickness of 100 μm. Their performance was tested and the results were recorded. Mechanical property testing: Prepare stainless steel-PI film overlap test specimens and test the bonding strength of the encapsulation layer; place the encapsulation layer in a mold and record the maximum pressure when it cracks at a rate of 1 mm / min to obtain the compressive strength; prepare dumbbell test specimens according to GB / T1040.1 and perform tensile testing at a tensile rate of 50 mm / min to test the elongation at break of the encapsulation layer. Electrical insulation performance test: The sample size is 15mm×15mm×3mm. The maximum voltage value (CTI) of the sample without leakage is measured when a voltage is applied between platinum electrodes and 50 drops of 0.1% ammonium chloride aqueous solution (volume 1.07±0.075g, time 24.5±2mm) of contaminating liquid are dropped from a height of 35mm. Referencing GB / T1410-2006, a three-electrode system is used, and the insulation resistance of the sample is measured using a high resistance meter. Electrolyte resistance test: The encapsulation layer sample was immersed in ethylene glycol electrolyte for 24 hours, and then the bonding strength was tested and the rate of change before and after the experiment was calculated. Stability test: The encapsulation layer was repeatedly bent at 180° 1000 times with a bending radius of 5mm and a frequency of 60 times / minute. Then the contact resistance was measured and the rate of change before and after the experiment was calculated. Based on the data in the table above, the following conclusions can be clearly drawn: The cured materials obtained in Examples 1-3 are compared with those obtained in Comparative Examples 1-5. The test results show that... The encapsulation layers obtained in Examples 1-3, compared to Comparative Example 5 which used an epoxy curing system, showed a significant reduction in curing time and higher curing efficiency, resulting in a substantial improvement in assembly efficiency for industrial applications. The adhesive strength, compressive strength, elongation at break, CTI, and insulation resistance data were all excellent, with no breakdown under 1000V high voltage. After immersion in ethylene glycol electrolyte for 24 hours, the adhesive strength remained good, and the encapsulation layer showed no cracking or discoloration. The contact resistance showed minimal change after repeated bending, and the encapsulation layer remained crack-free.
[0045] Compared to Example 1, Examples 2-3 show increased amounts of branched epoxy resin and decanolactone, as well as a higher proportion of hexafluorobisphenol A. The reduction in bisphenol A leads to a decrease in bond strength. Because the long chains of polydecanolate are flexible, the cured material is more easily deformed, exhibiting a decrease in compressive strength and an increase in elongation at break, resulting in better flexural resistance. The increased number of flexible long chains increases the free volume of the molecular chains, providing pathways for charge migration and electrolyte exchange; furthermore, the presence of different polarities affects the material's insulation and electrolyte resistance.
[0046] Compared to Example 1, Comparative Example 1 did not introduce hexafluorobisphenol A in the preparation of the branched epoxy resin, resulting in a decrease in the fluorine content of the ethylene, reduced resin surface energy and polarity, and consequently, deterioration of its adhesion, chemical resistance, insulation, and mechanical properties. The epoxy-modified acrylate in Comparative Example 2 was a commercially available product, lacking a rigid fluorinated structure and flexible polydecyl lactone, leading to a decrease in the resin's toughness, insulation, and chemical resistance. Compared to Comparative Example 2, the polydecyl lactone diol in Comparative Example 3 was prepared from decyl lactone and 2,5-pyridinediethanol, altering the structure of the polyurethane-modified acrylate and significantly reducing the resin's mechanical and chemical resistance properties. Both the epoxy-modified acrylate and polyurethane-modified acrylate in Comparative Example 4 were commercially available products, showing significant deterioration in all properties except for flexibility. The cured material in Comparative Example 5 was an epoxy resin system, exhibiting high brittleness, swelling and failing in the electrolyte, and becoming inflexible. Furthermore, the UV-cured resins in Comparative Examples 1-5 all had viscosities exceeding 500 mPa·s at 25°C.
[0047] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
Claims
1. A UV-curable material for FFC, characterized in that: It includes the following components: 50-60 parts base resin, 3-5 parts photoinitiator, 15-20 parts reactive diluent, 8-12 parts reinforcing filler, 2-4 parts additives, and 1-2 parts electrolyte-resistant modifier; The base resins include epoxy-modified acrylates and polyurethane-modified acrylates.
2. The UV-curable material for FFC according to claim 1, characterized in that: The mass ratio of the epoxy-modified acrylate to the polyurethane-modified acrylate is 8:
3.
3. The UV-curable material for FFC according to claim 1, characterized in that: The active diluent is trimethylolpropane triacrylate and isoborneol acrylate in a mass ratio of 5:
4.
4. A method for preparing a UV-curable material for FFC according to any one of claims 1-3, characterized in that: Including the following processes: Step 1: Mix the base resin, reactive diluent, electrolyte-resistant modifier and additives, add filler and photoinitiator in sequence and stir, degas to obtain UV-curable resin; Step 2: Apply UV-curable resin to the area to be encapsulated, and then irradiate with UV light to obtain the UV-curable material.
5. The method for preparing a UV-curable material for FFC according to claim 4, characterized in that: The epoxy-modified acrylate is prepared by the following process: Epoxy resin, reactive diluent, and polymerization inhibitor are mixed, heated to 90-95°C, acrylic acid and catalyst are added, and the mixture is stirred at 95-110°C for 2-5 hours to obtain epoxy-modified acrylate.
6. The method for preparing a UV-curable material for FFC according to claim 5, characterized in that: The epoxy resin is one or a mixture of two of E44 and branched epoxy resin.
7. The method for preparing a UV-curable material for FFC according to claim 6, characterized in that: The branched epoxy resin is prepared by the following process: Bisphenol compound, decanolactone, and organic catalyst are mixed and reacted at 140–150 °C for 10–16 h to obtain polydecyl lactone diphenol; under a nitrogen atmosphere, polydecyl lactone diphenol, trimethyloltriglycidyl ether, and catalyst are mixed and refluxed at 80–90 °C for 3.5–4.5 h to obtain branched epoxy resin.
8. The method for preparing a UV-curable material for FFC according to claim 4, characterized in that: The polyurethane-modified acrylate is prepared by the following process: Boc-protected 2,6-dimethyl-4-aminopyridine, decanolide, and an organic catalyst were mixed and stirred for 8–20 h to deprotect the product and obtain polydecanolide diol. Isophorone diisocyanate, dibutyltin dilaurate, and ethyl acetate were mixed and heated to 38–42°C. Triethylene glycol was added, and the mixture was reacted at 48–52°C for 1.5–2.0 h. The temperature was then raised to 58–62°C, and polydecyl lactone diol was added. The mixture was reacted at 68–72°C for 1.5–2.0 h. The temperature was then raised to 78–82°C, and p-hydroxyanisole and hydroxyethyl acrylate were added. The mixture was reacted at 78–82°C for 2.5–3.0 h to obtain polyurethane-modified acrylate.
9. A method for preparing a UV-curable material for FFC according to claim 6, characterized in that: The bisphenol compounds are bisphenol A and hexafluorobisphenol A, with a molar ratio of (1-3):1; the molar ratio of decanolide and bisphenol compounds is (6-10):
1. The mass ratio of polydecyl lactone diol to trimethyloltriglyceride triglycidyl ether is 100:(25-40).
10. A method for preparing a UV-curable material for FFC according to claim 7, characterized in that: The molar ratio of decanolide to Boc-protected 2,6-diethanol-4-aminopyridine is (4-10):1; The polyurethane-modified acrylate comprises the following components by weight: 8.9–10.0 parts isophorone diisocyanate, 0.018–0.030 parts dibutyltin dilaurate, 1.8–2.2 parts triethylene glycol, 10.5–12.5 parts polydecyl lactone diol, 0.04–0.08 parts p-hydroxyanisole, 1.9–2.2 parts hydroxyethyl acrylate, and 15–25 parts ethyl acetate.