Release film for multilayer ceramic capacitor and preparation method thereof

Abstract

The invention discloses a release film for a multilayer ceramic capacitor and a preparation method of the release film in the field of polymer composites.The release film is characterized in that polyethylene glycol terephthalate is adopted as a matrix, and specific spherical silicon dioxide and aluminum oxide are matched to form a bimodal nanoparticle system; and a bifunctional modifier containing perfluoroalkyl and siloxane and a hyperbranched multi-arm block polyester siloxane synergistic interface regulating agent are innovatively introduced. The preparation method comprises the key steps of nano particle surface modification, functional master batch melt blending extrusion, two-way stretching forming and the like. Through the synergistic effect of the two special modifiers, the dispersity of nanoparticles in a matrix is remarkably improved, and the interface bonding strength is enhanced, so that the obtained release film has extremely low surface roughness, excellent anti-bonding performance and good heat resistance and dimensional stability at the same time, and completely meets the requirements of a high-end multilayer ceramic capacitor preparation process.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to a release film for multilayer ceramic capacitors and its preparation method. Background Technology

[0002] Multilayer ceramic capacitors, as an indispensable basic component in modern electronics, place extremely stringent requirements on related auxiliary materials during their manufacturing process. In the tape casting process of multilayer ceramic capacitors, the release film plays a crucial role as a carrier, and its performance directly determines the uniformity and density of the ceramic dielectric layer, as well as the reliability and miniaturization of the final component. An ideal release film must simultaneously meet several interdependent performance indicators: it must possess excellent and stable anti-adhesion properties to ensure complete peeling of the cured ceramic green body; it needs extremely low and uniform surface roughness to ensure uniform thickness of the tape-cast ceramic dielectric layer and avoid local defects; and it must also possess excellent heat resistance, dimensional stability, and mechanical strength to withstand subsequent high-temperature processing and machining. Currently, the industry commonly uses polyester film as the substrate, and introduces various inorganic nanoparticles and organic additives to regulate its surface properties and overall performance.

[0003] However, existing multilayer ceramic capacitor release film technology still faces several long-standing technical bottlenecks. The primary problem lies in the poor dispersibility and interfacial compatibility of inorganic nanoparticles in the organic resin matrix. Commonly used fillers such as nano-silica and alumina are prone to agglomeration due to their high surface energy. These agglomerates become stress concentration points during film formation, directly leading to an uneven film surface and significantly increasing surface roughness. Secondly, there is an irreconcilable contradiction between the anti-adhesion performance of the release film and surface roughness. To improve the release effect, it is often necessary to increase the amount or size of nanoparticles, but this exacerbates surface roughness; conversely, pursuing a smooth surface may sacrifice release reliability. Furthermore, traditionally used interfacial modifiers such as silane coupling agents have relatively simple molecular structures, limited modification effects, and are prone to failure under high-temperature processing conditions, making it difficult to establish a strong and durable interfacial bond between nanoparticles and resin.

[0004] To overcome these challenges, the industry has made various attempts. For example, constructing bimodal or multimodal distribution systems using nanoparticles of different sizes aims to achieve better packing density and surface properties at the same filling volume; developing polymer dispersants with specific functional groups aims to improve the dispersion stability of nanoparticles through steric hindrance; and utilizing the low surface energy of fluorinated compounds to enhance anti-adhesion effects. Although these methods have made some progress, they often only address one aspect of the problem and cannot achieve a breakthrough improvement in overall performance. In particular, existing technologies still fall short of the nanoscale surface smoothness and near-perfect release stability required for high-end multilayer ceramic capacitors. Therefore, it is urgent to start from the molecular structure design level to develop novel interface modification materials and composite preparation processes to fundamentally solve the problems of nanoparticle dispersion, interface strengthening, and performance balance, in order to meet the demand for high-performance release films in the manufacturing of next-generation electronic components. Summary of the Invention

[0005] The purpose of this invention is to provide a release film for multilayer ceramic capacitors and its preparation method, which solves the technical problems of high surface roughness caused by easy agglomeration of nanoparticles and weak interfacial bonding in existing release films for multilayer ceramic capacitors, as well as the difficulty in achieving both anti-adhesion performance and low surface roughness.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] This invention provides a method for preparing a release film for multilayer ceramic capacitors, comprising the following steps:

[0008] S1. Mix spherical silica and alumina, add anhydrous ethanol, and disperse by ultrasonication; then add a bifunctional modifier containing perfluoroalkyl and siloxane groups, and mechanically stir in a water bath at 68-72℃; then centrifuge, wash with ethanol, and dry in a vacuum drying oven at 74-76℃ to obtain a surface-modified bimodal nanoparticle composite.

[0009] S2. Polyethylene terephthalate, surface-modified bimodal nanoparticle composite, hyperbranched multi-arm block polyester-siloxane synergistic interface modifier, polyethylene wax, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite are premixed in a high-speed mixer to obtain a premix; the premix is ​​added to a twin-screw extruder through the main feeding system, while surface-modified bimodal nanoparticle composite is added through the side feeding system, and the mixture is melt-blended and extruded, water-cooled, drawn into strips and granulated to obtain a release film functional masterbatch;

[0010] S3. The release film functional masterbatch is mixed with polyethylene terephthalate and melt-extruded through an extruder. It is then cast through a flat die at 278-282℃ and quenched with a chilling roller at 28-32℃ to form an unshaped casting. The casting is first stretched longitudinally at a preheating temperature of 84-86℃, a stretching temperature of 94-96℃, and a stretching ratio of 3.4-3.6 times. Then it is stretched transversely at a preheating temperature of 88-92℃, a stretching temperature of 104-106℃, and a stretching ratio of 3.6-3.9 times. Finally, it is heat-set at 208-212℃, cooled, and then wound up.

[0011] In this invention, the preparation of the release film is a systematic engineering process involving interwoven physicochemical processes. Its core mechanism lies in the stable multiphase composite structure established by the interfacial interactions and physical entanglement of the components. First, in the nanoparticle surface modification stage, the siloxane end groups of the perfluoroalkyl and siloxane bifunctional modifier undergo hydrolysis-condensation reactions with the silanol or aluminum hydroxyl groups on the surface of spherical silica and alumina nanoparticles under mild heating and mechanical stirring conditions, forming strong silicon-oxygen-silicon covalent bonds or silicon-oxygen-aluminum covalent bonds. This surface chemical reaction fundamentally alters the surface properties of the nanoparticles, transforming them from hydrophilic to oleophobic and hydrophobic. Furthermore, the extended fluoroalkyl long chains effectively prevent the nanoparticles from approaching each other and agglomerating during subsequent processing through steric hindrance, laying the molecular foundation for achieving nanoscale uniform dispersion. Subsequently, in the melt blending and film forming stages, the hyperbranched multi-arm block polyester siloxane synergistic interface regulator plays a crucial role. Its hyperbranched core acts as a "molecular anchor," tightly binding to the polyethylene terephthalate (PET) molecular chains through physical entanglement and van der Waals forces. Simultaneously, its polysiloxane arms exhibit good compatibility with the fluorinated outer layer of the surface-modified nanoparticles, while its polycaprolactone arms demonstrate strong affinity for the polyester matrix. This unique molecular structure allows it to act like a "molecular glue," establishing a flexible and robust transitional interface layer between inorganic nanoparticles and the organic resin matrix. This interface layer not only effectively transfers stress, preventing interfacial cracking due to differences in the thermal expansion coefficients of the two phases, but also inhibits the migration and re-aggregation of nanoparticles through its massive three-dimensional structure. Finally, through a precisely controlled biaxial stretching process, the polymer molecular chains and nanoparticle composite are highly oriented along the planar direction under the influence of heat and mechanical forces, forming a dense and highly ordered microstructure. The heat-setting process, through precise control of chain segment relaxation and crystallinity, fixes the orientation structure, ultimately yielding a high-quality release film with an extremely smooth surface, stable internal structure, and excellent anti-adhesion and mechanical properties. The synergistic effect of the two innovative modifiers is the essence of this invention; they jointly construct a high-performance composite material system from the molecular to the macroscopic scale.

[0012] According to a preferred embodiment of the present invention, in step S2, the temperature of melt blending extrusion is 260-280°C and the screw speed is 400-600 r / min.

[0013] According to a preferred embodiment of the present invention, in step S3, the heat setting treatment at 208-212°C takes 10-12 seconds.

[0014] According to a preferred embodiment of the present invention, the preparation method of the bifunctional modifier containing perfluoroalkyl and siloxane groups includes: A1, under a dry nitrogen atmosphere, dissolving perfluorohexylethanol and triethylamine in anhydrous tetrahydrofuran, cooling to 0-5°C in an ice-water bath; then adding acryloyl chloride dropwise, controlling the reaction temperature at 8-10°C; after the addition is complete, raising the temperature to room temperature for reaction, filtering, and distilling under reduced pressure to obtain intermediate 1; A2, dissolving intermediate 1 and 3-mercaptopropyltriethoxysilane in toluene, adding azobisisobutyronitrile, and carrying out a thiol-ene click reaction at 78-82°C; after the reaction is completed, rotating the evaporator to achieve the desired effect.

[0015] In this invention, the preparation process of the bifunctional modifier containing perfluoroalkyl and siloxane groups involves two key chemical reaction steps with precise and efficient mechanisms. The first step is an acyl chloride esterification reaction. Under strictly controlled anhydrous and low-temperature conditions, the terminal hydroxyl group of perfluorohexyl ethanol undergoes a nucleophilic substitution reaction with the acyl chloride group of acryloyl chloride. Triethylamine, as a highly efficient acid absorber, promptly neutralizes the hydrogen chloride generated in the reaction, driving the reaction equilibrium towards ester formation, thus successfully obtaining the perfluoroalkyl acrylate intermediate. The key to this step lies in the effective suppression of the self-polymerization of acryloyl chloride and potential side reactions with the solvent through low-temperature dropwise addition and precise temperature control, ensuring the high purity and reactivity of the intermediate. The second step is a thiol-ene click reaction, which is the core of constructing the target molecular skeleton. Under the action of a free radical initiator, the carbon-carbon double bond of the acrylate at the end of the intermediate molecule undergoes a highly efficient free radical addition reaction with the thiol group at the end of the triethoxysilane derivative molecule. This click chemistry strategy exhibits near-quantitative reaction efficiency, excellent regioselectivity, and good functional group tolerance. The reaction mechanism is a typical chain process, including three stages: chain initiation, chain propagation, and chain termination. Ultimately, the reaction successfully connects low-surface-energy fluorinated segments with reactive siloxane groups through stable carbon-sulfur bonds and carbon-carbon single bonds, forming a bifunctional molecule that possesses both excellent hydrophobic and oleophobic properties and strong interfacial bonding ability. This molecular structure allows it to act as a microscopic bridge, with one end firmly bonded to the surface of inorganic nanoparticles through siloxane groups, while the other end achieves good compatibility with organic resins and significantly reduces interfacial energy through fluorinated segments.

[0016] According to a preferred embodiment of the present invention, in step A1, the reaction time to room temperature is 12-14 hours.

[0017] According to a preferred embodiment of the present invention, in step A2, the thiol-ene click reaction time is 6-8 hours.

[0018] According to a preferred embodiment of the present invention, the preparation method of the hyperbranched multi-arm block polyester-siloxane synergistic interface regulator includes: B1, firstly, adding pentaerythritol and 2,2-dimethylolpropionic acid, N,N-dimethylformamide and p-toluenesulfonic acid to a dry reactor, and reacting at 134-136°C to generate a second-generation hyperbranched polyester; then cooling the reaction system to 78-82°C, and adding isocyanate propyltriethoxysilane and dibutyltin dilaurate for reaction; B2, then adding a mixture of monohydroxy-terminated polydimethylsiloxane and monoamino-terminated polycaprolactone, and continuing the reaction at 84-86°C; finally adding 3-isocyanate propyltriethoxysilane for end-capping reaction, and purifying after the reaction is completed.

[0019] In this invention, the synthesis of the hyperbranched multi-arm block polyester-siloxane synergistic interface regulator embodies a precise multi-step polymer molecular design with a complex yet orderly mechanism. The entire process begins with the construction of a hyperbranched polyester core, using pentaerythritol as the core molecule, which undergoes a melt condensation reaction with dimethylolpropionic acid. Based on the difference in monomer functionality, a stepwise polymerization mechanism is followed to generate a second-generation hyperbranched polyester with a highly branched three-dimensional structure. This molecule contains numerous cavities and its surface is rich in terminal hydroxyl groups, providing abundant reaction sites for subsequent functionalization. The next crucial step is the end-group conversion step, where the isocyanate group of isocyanate propyltriethoxysilane reacts quantitatively with the terminal hydroxyl groups of the hyperbranched polyester to form urethane links. This reaction proceeds efficiently in the presence of an organotin catalyst, and its mechanism involves the nucleophilic addition of hydroxyl groups to the electron-deficient carbon-nitrogen double bonds in the isocyanate groups. This step not only converts all reactive hydroxyl groups into isocyanate end groups, but more importantly, it introduces the ultimately required silane coupling functional groups in advance, laying the foundation for interfacial bonding of the entire molecule. Finally, the crucial grafting step for constructing the multi-arm structure involves using the isocyanate-terminated hyperbranched prepolymer generated in the previous step as a multifunctional platform. The terminal isocyanate groups undergo rapid nucleophilic addition reactions with the hydroxyl groups of monohydroxy-terminated polydimethylsiloxane and the amino groups of monoamino-terminated polycaprolactone, respectively, forming stable urethane and urea bonds. This allows for the precise stoichiometric grafting of flexible polysiloxane segments and well-compatible polycaprolactone segments onto the hyperbranched framework. This design ultimately results in a star-shaped multi-arm block copolymer with a hyperbranched polyester core and polysiloxane and polycaprolactone arms. Its three-dimensional structure generates strong steric hindrance effects and excellent stress dissipation capabilities in the interfacial region.

[0020] According to a preferred embodiment of the present invention, in step B1, the reaction time is 8-10 h at 134-136 °C; the reaction time for adding isocyanate propyltriethoxysilane and dibutyltin dilaurate is 3-4 h.

[0021] According to a preferred embodiment of the present invention, in step B2, the reaction continues at 84-86°C for 6-8 hours.

[0022] The present invention also provides a method for preparing a release film for a multilayer ceramic capacitor, comprising the following raw materials in parts by weight: 80-95 parts by weight of polyethylene terephthalate; 3-10 parts by weight of spherical silica; 1-5 parts by weight of alumina; 0.5-3 parts by weight of a bifunctional modifier containing perfluoroalkyl and siloxane groups; 1-5 parts by weight of a hyperbranched multi-arm block polyester-siloxane synergistic interface regulator; 0.1-1 parts by weight of polyethylene wax; 0.1-0.5 parts by weight of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; and 0.1-0.5 parts by weight of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention achieves a breakthrough improvement in the overall performance of multilayer ceramic capacitor release films through a unique molecular structure design and innovative preparation process. Its core technological effect is primarily reflected in fundamentally solving the problems of dispersion and interfacial bonding of inorganic nanoparticles in organic resin matrices. By employing a bifunctional modifier containing perfluoroalkyl and siloxane groups to modify the surface of a bimodal nanoparticle system composed of spherical silica and alumina, the siloxane groups in the modifier molecule form strong chemical bonds with the nanoparticle surface, while the perfluoroalkyl segments extend outward to form a low surface energy protective layer, effectively preventing the agglomeration tendency of nanoparticles and achieving uniform nanoscale dispersion. Simultaneously, the hyperbranched multi-arm block polyester siloxane synergistic interfacial regulator, with its three-dimensional spherical structure as its core, interacts strongly with the resin matrix and modified nanoparticles through numerous terminal functional groups, forming a flexible transition layer at the interface. This significantly enhances the interfacial adhesion strength and avoids interfacial delamination during processing and use.

[0025] Secondly, this invention successfully achieves the optimal balance between the anti-adhesion performance and low surface roughness of the release film, a long-standing challenge in this technical field. Perfluoroalkyl segments form a dense, low surface energy layer on the film surface, endowing the release film with excellent anti-adhesion properties; while the hyperbranched interface regulator, through its molecular chain entanglement and steric hindrance effect, ensures the stable dispersion of nanoparticles in the matrix, preventing increased surface roughness due to particle aggregation or sedimentation. The synergistic effect of these two innovative compounds enables the release film to maintain extremely low surface roughness while still possessing excellent release capability. In particular, by precisely controlling the parameters of the biaxial stretching process, including stretching temperature, stretching ratio, and heat setting conditions, the surface morphology and microstructure of the film are further optimized, achieving an unprecedented level of surface smoothness.

[0026] Finally, the release film prepared by this invention exhibits comprehensive performance improvements, meeting the stringent requirements of high-end multilayer ceramic capacitor manufacturing. This release film not only has extremely low surface roughness, ensuring uniform thickness of the ceramic dielectric layer formed by casting, but also possesses stable and reliable anti-adhesion properties, enabling complete peeling of the ceramic green body without residue. Simultaneously, this release film also demonstrates excellent heat resistance, dimensional stability, and mechanical strength, able to withstand subsequent high-temperature processing without deformation or performance degradation. Furthermore, the antioxidants and heat stabilizers added to the formulation further ensure the long-term stability of the product during processing and use. In summary, this invention, through multi-level innovation, successfully prepares a release film for multilayer ceramic capacitors with balanced and excellent performance, providing key material support for the miniaturization and high reliability of electronic components. Detailed Implementation

[0027] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0028] The following is information on domestic suppliers of key related equipment and materials:

[0029] The spherical silica was purchased from Jiangsu Lianrui New Materials Co., Ltd.

[0030] The alumina was purchased from Zibo Shanlu Electronic Technology Co., Ltd.

[0031] The polyethylene terephthalate was purchased from Sinopec Yizheng Chemical Fiber Co., Ltd.

[0032] The polyethylene wax was purchased from Nanjing Tianshi New Material Technology Co., Ltd.

[0033] The pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] was purchased from Linyi Sanfeng Chemical Co., Ltd.

[0034] The bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite was purchased from Linyi Sanfeng Chemical Co., Ltd.

[0035] The perfluorohexylethanol was purchased from Zhonghao Fluorochemical Co., Ltd.

[0036] The triethylamine was purchased from Jinan Century Tongda Chemical Co., Ltd.

[0037] The acryloyl chloride was purchased from Shandong Huihai Pharmaceutical Chemical Co., Ltd.

[0038] The 3-mercaptopropyltriethoxysilane was purchased from Hubei Xinlantian New Materials Co., Ltd.

[0039] The azobisisobutyronitrile was purchased from Zibo Qilong Chemical Co., Ltd.

[0040] The pentaerythritol was purchased from Hubei Yihua Chemical Co., Ltd.

[0041] The 2,2-dihydroxymethylpropionic acid was purchased from Guangzhou Qiyun Biotechnology Co., Ltd.

[0042] The p-toluenesulfonic acid was purchased from Nanjing Chemical Reagent Co., Ltd.

[0043] The isocyanate propyltriethoxysilane was purchased from Jingzhou Jianghan Fine Chemical Co., Ltd.

[0044] The dibutyltin dilaurate was purchased from the Beijing Additives Research Institute.

[0045] The monohydroxy-terminated polydimethylsiloxane was purchased from Zhejiang Xin'an Chemical Group Co., Ltd.

[0046] The monoamino-terminated polycaprolactone was purchased from Shanghai Zhenzhun Biotechnology Co., Ltd.

[0047] The 3-isocyanate-propyltriethoxysilane was purchased from Jingzhou Jianghan Fine Chemical Co., Ltd.

[0048] Example 1

[0049] Preparation of a bifunctional modifier containing perfluoroalkyl and siloxane groups: Under a dry nitrogen atmosphere, 10 g of perfluorohexylethanol and 5 g of triethylamine were dissolved in 100 g of anhydrous tetrahydrofuran, and the mixture was cooled to 3 °C in an ice-water bath. Then, 6 g of acryloyl chloride was added dropwise, controlling the reaction temperature at 9 °C. After the addition was complete, the mixture was allowed to rise to room temperature and reacted for 13 h. The mixture was then filtered and distilled under reduced pressure to obtain intermediate 1. Intermediate 1 and 8 g of 3-mercaptopropyltriethoxysilane were dissolved in 50 g of toluene, and 0.5 g of azobisisobutyronitrile was added. The mixture was subjected to a thiol-ene click reaction at 80 °C for 7 h. After the reaction was completed, the bifunctional modifier containing perfluoroalkyl and siloxane groups was obtained by rotary evaporation.

[0050] Preparation of hyperbranched multi-arm block polyester-siloxane synergistic interface modifier: Pentaerythritol 5g and 2,2-dimethylolpropionic acid 10g, N,N-dimethylformamide 50g and p-toluenesulfonic acid 0.5g were added to a dry reactor, and the reaction was carried out at 135℃ for 9h to generate a second-generation hyperbranched polyester. The reaction system was then cooled to 80℃, and isocyanate propyltriethoxysilane 8g and dibutyltin dilaurate 0.2g were added, followed by a reaction for 3.5h. Next, a mixture of monohydroxy-terminated polydimethylsiloxane 6g and monoamino-terminated polycaprolactone 4g was added, and the reaction was continued at 85℃ for 7h. Finally, 3-isocyanate propyltriethoxysilane 5g was added for end-capping. After the reaction was completed, the hyperbranched multi-arm block polyester-siloxane synergistic interface modifier was obtained by purification.

[0051] Preparation of release film for multilayer ceramic capacitors: S1, 5g of spherical silica and 2g of alumina are mixed, 50g of anhydrous ethanol is added, and the mixture is ultrasonically dispersed; then 1.5g of a bifunctional modifier containing perfluoroalkyl and siloxane groups is added, and the mixture is mechanically stirred in a water bath at 70℃; then the mixture is centrifuged, washed with ethanol, and dried in a vacuum drying oven at 75℃ to obtain a surface-modified bimodal nanoparticle composite. S2. 50g of polyethylene terephthalate, 10g of surface-modified bimodal nanoparticle composite, 3g of hyperbranched multi-arm block polyester-siloxane synergistic interface modifier, 0.5g of polyethylene wax, 0.3g of tetrakis(β-3,5-di-tert-butyl-4-hydroxyphenylpropionate) pentaerythritol ester and 0.3g of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite are premixed in a high-speed mixer to obtain a premix. The premix is ​​added to a twin-screw extruder through the main feeding system, while 5g of surface-modified bimodal nanoparticle composite is added through the side feeding system. The mixture is melt-blended and extruded at an extrusion temperature of 270℃ and a screw speed of 500r / min. The mixture is then water-cooled, stretched, and pelletized to obtain a release film functional masterbatch. S3. Mix 60g of release film functional masterbatch with 40g of polyethylene terephthalate, melt-extrude through an extruder, cast through a flat die at 280℃, and then quench with a chilling roller at 30℃ to form an unshaped casting. First, stretch the casting longitudinally at a preheating temperature of 85℃, a stretching temperature of 95℃, and a stretching ratio of 3.5 times. Then, stretch it transversely at a preheating temperature of 90℃, a stretching temperature of 105℃, and a stretching ratio of 3.7 times. Finally, heat-set the casting at 210℃ for 11 seconds, cool, and then wind it up.

[0052] Example 2

[0053] The specific implementation method is the same as in Example 1, except that a bifunctional modifier containing perfluoroalkyl and siloxane groups is prepared: Under a dry nitrogen atmosphere, 8g of perfluorohexylethanol and 4g of triethylamine are dissolved in 80g of anhydrous tetrahydrofuran, and the mixture is cooled to 3°C in an ice-water bath; then 5g of acryloyl chloride is added dropwise, and the reaction temperature is controlled at 9°C; after the addition is complete, the mixture is raised to room temperature and reacted for 13h, filtered, and distilled under reduced pressure to obtain intermediate 1. Intermediate 1 and 6g of 3-mercaptopropyltriethoxysilane are dissolved in 40g of toluene, and 0.4g of azobisisobutyronitrile is added. A thiol-ene click reaction is carried out at 80°C for 7h; after the reaction is completed, the bifunctional modifier containing perfluoroalkyl and siloxane groups is obtained by rotary evaporation.

[0054] Preparation of hyperbranched multi-arm block polyester-siloxane synergistic interface modifier: 4g of pentaerythritol and 8g of 2,2-dimethylolpropionic acid, 40g of N,N-dimethylformamide and 0.4g of p-toluenesulfonic acid were added to a dry reactor, and the reaction was carried out at 135℃ for 9h to generate a second-generation hyperbranched polyester. Subsequently, the reaction system was cooled to 80℃, and 6g of isocyanate-propyltriethoxysilane and 0.16g of dibutyltin dilaurate were added, and the reaction was carried out for 3.5h. Next, a mixture of 5g of monohydroxy-terminated polydimethylsiloxane and 3g of monoamino-terminated polycaprolactone was added, and the reaction was continued at 85℃ for 7h. Finally, 4g of 3-isocyanate-propyltriethoxysilane was added for end-capping. After the reaction was completed, the hyperbranched multi-arm block polyester-siloxane synergistic interface modifier was obtained by purification.

[0055] Preparation of release film for multilayer ceramic capacitors: S1, 4g of spherical silica and 1.5g of alumina were mixed, 40g of anhydrous ethanol was added, and the mixture was ultrasonically dispersed; then 1.2g of a bifunctional modifier containing perfluoroalkyl and siloxane groups was added, and the mixture was mechanically stirred in a water bath at 70℃; then the mixture was centrifuged, washed with ethanol, and dried in a vacuum drying oven at 75℃ to obtain a surface-modified bimodal nanoparticle composite. S2. 45g of polyethylene terephthalate, 8g of surface-modified bimodal nanoparticle composite, 2.5g of hyperbranched multi-arm block polyester-siloxane synergistic interface modifier, 0.4g of polyethylene wax, 0.25g of tetrakis(β-3,5-di-tert-butyl-4-hydroxyphenylpropionate) pentaerythritol ester and 0.25g of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite are premixed in a high-speed mixer to obtain a premix. The premix is ​​added to a twin-screw extruder through the main feeding system, while 4g ​​of surface-modified bimodal nanoparticle composite is added through the side feeding system. The mixture is melt-blended and extruded at an extrusion temperature of 270℃ and a screw speed of 500r / min. The mixture is then water-cooled, stretched, and pelletized to obtain a release film functional masterbatch. S3. Mix 55g of release film functional masterbatch with 35g of polyethylene terephthalate, melt-extrude through an extruder, and cast through a flat die at 280℃. Then, quench the mixture with a 30℃ chiller roller to form an unshaped casting. First, stretch the casting longitudinally at a preheating temperature of 85℃ and a stretching temperature of 95℃, with a stretching ratio of 3.5 times. Then, stretch it transversely at a preheating temperature of 90℃ and a stretching temperature of 105℃, with a stretching ratio of 3.7 times. Finally, heat-set the mixture at 210℃ for 11 seconds, cool it, and then wind it up.

[0056] Example 3

[0057] The specific implementation method is the same as in Example 1, except that a bifunctional modifier containing perfluoroalkyl and siloxane groups is prepared: Under a dry nitrogen atmosphere, 12g of perfluorohexylethanol and 6g of triethylamine are dissolved in 120g of anhydrous tetrahydrofuran, and the mixture is cooled to 3°C in an ice-water bath; then 7g of acryloyl chloride is added dropwise, and the reaction temperature is controlled at 9°C; after the addition is complete, the mixture is raised to room temperature and reacted for 13h, filtered, and distilled under reduced pressure to obtain intermediate 1. Intermediate 1 and 10g of 3-mercaptopropyltriethoxysilane are dissolved in 60g of toluene, and 0.6g of azobisisobutyronitrile is added. A thiol-ene click reaction is carried out at 80°C for 7h; after the reaction is completed, the bifunctional modifier containing perfluoroalkyl and siloxane groups is obtained by rotary evaporation.

[0058] Preparation of hyperbranched multi-arm block polyester-siloxane synergistic interface regulator: Pentaerythritol 6g and 2,2-dimethylolpropionic acid 12g, N,N-dimethylformamide 60g and p-toluenesulfonic acid 0.6g were added to a dry reactor, and the reaction was carried out at 135℃ for 9h to generate a second-generation hyperbranched polyester. The reaction system was then cooled to 80℃, and isocyanate propyltriethoxysilane 10g and dibutyltin dilaurate 0.24g were added, followed by a reaction for 3.5h. Next, a mixture of monohydroxy-terminated polydimethylsiloxane 7g and monoamino-terminated polycaprolactone 5g was added, and the reaction was continued at 85℃ for 7h. Finally, 3-isocyanate propyltriethoxysilane 6g was added for end-capping. After the reaction was completed, the hyperbranched multi-arm block polyester-siloxane synergistic interface regulator was obtained by purification.

[0059] Preparation of release film for multilayer ceramic capacitors: S1, 6g of spherical silica and 2.5g of alumina were mixed, 60g of anhydrous ethanol was added, and the mixture was ultrasonically dispersed; then 1.8g of a bifunctional modifier containing perfluoroalkyl and siloxane groups was added, and the mixture was mechanically stirred in a water bath at 70℃; then the mixture was centrifuged, washed with ethanol, and dried in a vacuum drying oven at 75℃ to obtain a surface-modified bimodal nanoparticle composite. S2. 55g of polyethylene terephthalate, 12g of surface-modified bimodal nanoparticle composite, 3.5g of hyperbranched multi-arm block polyester-siloxane synergistic interface modifier, 0.6g of polyethylene wax, 0.35g of tetrakis(β-3,5-di-tert-butyl-4-hydroxyphenylpropionate) pentaerythritol ester and 0.35g of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite are premixed in a high-speed mixer to obtain a premix. The premix is ​​added to a twin-screw extruder through the main feeding system, while 6g of surface-modified bimodal nanoparticle composite is added through the side feeding system. The mixture is melt-blended and extruded at an extrusion temperature of 270℃ and a screw speed of 500r / min. The mixture is then water-cooled, stretched, and pelletized to obtain a release film functional masterbatch. S3. Mix 65g of release film functional masterbatch with 45g of polyethylene terephthalate, melt-extrude through an extruder, and cast through a flat die at 280℃. Then, quench the mixture with a 30℃ chiller to form an unshaped casting. First, stretch the casting longitudinally at a preheating temperature of 85℃ and a stretching temperature of 95℃, with a stretching ratio of 3.5 times. Then, stretch it transversely at a preheating temperature of 90℃ and a stretching temperature of 105℃, with a stretching ratio of 3.7 times. Finally, heat-set the mixture at 210℃ for 11 seconds, cool it, and then wind it up.

[0060] Comparative Example 1

[0061] The specific implementation method is the same as in Example 1, except that the release film for multilayer ceramic capacitors is prepared as follows: S1, 5g of spherical silica and 2g of alumina are mixed, 50g of anhydrous ethanol is added, and the mixture is ultrasonically dispersed; then, without adding a bifunctional modifier containing perfluoroalkyl and siloxane groups, the mixture is mechanically stirred in a 70°C water bath; then, it is centrifuged, washed with ethanol, and dried in a 75°C vacuum drying oven to obtain an unmodified bimodified nanoparticle composite. S2. 50g of polyethylene terephthalate, 10g of unmodified bimodal nanoparticle composite, 3g of hyperbranched multi-arm block polyester-siloxane synergistic interface modifier, 0.5g of polyethylene wax, 0.3g of tetrakis(β-3,5-di-tert-butyl-4-hydroxyphenylpropionate) pentaerythritol ester and 0.3g of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite are premixed in a high-speed mixer to obtain a premix. The premix is ​​added to a twin-screw extruder through the main feeding system, while 5g of unmodified bimodal nanoparticle composite is added through the side feeding system. The mixture is melt-blended and extruded at an extrusion temperature of 270℃ and a screw speed of 500r / min. The mixture is then water-cooled, stretched, and pelletized to obtain a release film functional masterbatch. S3. Mix 60g of release film functional masterbatch with 40g of polyethylene terephthalate, melt-extrude through an extruder, cast through a flat die at 280℃, and then quench with a chilling roller at 30℃ to form an unshaped casting. First, stretch the casting longitudinally at a preheating temperature of 85℃, a stretching temperature of 95℃, and a stretching ratio of 3.5 times. Then, stretch it transversely at a preheating temperature of 90℃, a stretching temperature of 105℃, and a stretching ratio of 3.7 times. Finally, heat-set the casting at 210℃ for 11 seconds, cool, and then wind it up.

[0062] Comparative Example 2

[0063] The specific implementation method is the same as in Example 1, except that the release film for multilayer ceramic capacitors is prepared as follows: S1, 5g of spherical silica and 2g of alumina are mixed, 50g of anhydrous ethanol is added, and the mixture is ultrasonically dispersed; then 1.5g of a bifunctional modifier containing perfluoroalkyl and siloxane groups is added, and the mixture is mechanically stirred in a water bath at 70°C; then the mixture is centrifuged, washed with ethanol, and dried in a vacuum drying oven at 75°C to obtain a surface-modified bimodal nanoparticle composite. S2. 50g of polyethylene terephthalate, 10g of surface-modified bimodal nanoparticle composite, unbranched multi-arm block polyester-siloxane synergistic interface modifier, 0.5g of polyethylene wax, 0.3g of tetrakis(β-3,5-di-tert-butyl-4-hydroxyphenylpropionate) pentaerythritol ester, and 0.3g of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite are premixed in a high-speed mixer to obtain a premix. The premix is ​​added to a twin-screw extruder through the main feeding system, while 5g of surface-modified bimodal nanoparticle composite is added through the side feeding system. The mixture is melt-blended and extruded at an extrusion temperature of 270℃ and a screw speed of 500r / min. The mixture is then water-cooled, stretched, and pelletized to obtain a release film functional masterbatch. S3. Mix 60g of release film functional masterbatch with 40g of polyethylene terephthalate, melt-extrude through an extruder, cast through a flat die at 280℃, and then quench with a chilling roller at 30℃ to form an unshaped casting. First, stretch the casting longitudinally at a preheating temperature of 85℃, a stretching temperature of 95℃, and a stretching ratio of 3.5 times. Then, stretch it transversely at a preheating temperature of 90℃, a stretching temperature of 105℃, and a stretching ratio of 3.7 times. Finally, heat-set the casting at 210℃ for 11 seconds, cool, and then wind it up.

[0064] Comparative Example 3

[0065] The specific implementation method is the same as in Example 1, except that the release film for multilayer ceramic capacitors is prepared as follows: S1, 5g of spherical silica and 2g of alumina are mixed, 50g of anhydrous ethanol is added, and the mixture is ultrasonically dispersed; then, without adding a bifunctional modifier containing perfluoroalkyl and siloxane groups, the mixture is mechanically stirred in a 70°C water bath; then, it is centrifuged, washed with ethanol, and dried in a 75°C vacuum drying oven to obtain an unmodified bimodified nanoparticle composite. S2. 50g of polyethylene terephthalate, 10g of unmodified bimodal nanoparticle composite, unbranched multi-arm block polyester-siloxane synergistic interface modifier, 0.5g of polyethylene wax, 0.3g of tetrakis(β-3,5-di-tert-butyl-4-hydroxyphenylpropionate) pentaerythritol ester, and 0.3g of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite are premixed in a high-speed mixer to obtain a premix. The premix is ​​added to a twin-screw extruder through the main feeding system, while 5g of unmodified bimodal nanoparticle composite is added through the side feeding system. The mixture is melt-blended and extruded at an extrusion temperature of 270℃ and a screw speed of 500r / min. The mixture is then water-cooled, stretched, and pelletized to obtain a release film functional masterbatch. S3. Mix 60g of release film functional masterbatch with 40g of polyethylene terephthalate, melt-extrude through an extruder, cast through a flat die at 280℃, and then quench with a chilling roller at 30℃ to form an unshaped casting. First, stretch the casting longitudinally at a preheating temperature of 85℃, a stretching temperature of 95℃, and a stretching ratio of 3.5 times. Then, stretch it transversely at a preheating temperature of 90℃, a stretching temperature of 105℃, and a stretching ratio of 3.7 times. Finally, heat-set the casting at 210℃ for 11 seconds, cool, and then wind it up.

[0066] Performance testing

[0067] According to national and industry standard testing specifications, the performance of the release films for multilayer ceramic capacitors prepared in Examples 1-3 and Comparative Examples 1-3 was tested: All performance tests were conducted in a standard laboratory environment with a temperature of 23±2℃ and a relative humidity of 50±5%. For peel force testing, a universal testing machine was used. A standard acrylic pressure-sensitive tape with a width of 25mm was pressed onto the surface of the release film using a 2kg pressure roller. After standing for 20 hours, peeling was performed at a peel angle of 180° and a constant speed of 300 mm / min. Stable force values ​​were recorded, and the average of five tests was taken. The results are expressed in grams per inch (g / inch). For heat shrinkage testing, a 100mm × 100mm sample was precisely cut from each sample and placed unconstrained in a 150℃ forced-air drying oven for 30 minutes. After cooling to room temperature, the longitudinal and transverse dimensional changes were measured, and the average value was calculated as the final heat shrinkage rate, expressed as a percentage. Tensile strength and elongation at break tests were performed using dumbbell-shaped specimens on a tensile testing machine with an initial clamping distance of 500 mm / min and a beam speed of 50 mm / min until the specimen broke. The maximum tensile force was recorded, and the tensile strength was calculated. The average of five tests was taken, and the result was expressed in megapascals (MPa). Water contact angle testing was performed using a contact angle measuring instrument. A 2 μL droplet of ultrapure water was precisely dropped onto the sample surface using the seated drop method. The droplet morphology was analyzed using the instrument software, and the static contact angle was calculated. Five measurements were taken at different locations for each sample, and the average was taken. The result was expressed in degrees. Dielectric constant testing was performed using an impedance analyzer at a frequency of 1 kHz. The capacitance of the sample was measured using a parallel plate electrode system, and the dielectric constant was calculated.

[0068] Performance test results:

[0069] Table 1: Performance test results of each embodiment and comparative example

[0070] Test Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Peel force (g / in) 15 18 12 35 28 50 Heat shrinkage rate (%) 1.5 1.7 1.3 3.0 2.5 4.0 Tensile strength (MPa) 55 52 58 40 35 30 Contact angle (°) 105 102 108 80 90 70 Dielectric constant 3.1 3.2 3.0 3.5 3.4 3.8

[0071] As shown in Table 1, the test results indicate that the release films prepared in Examples 1-3 are superior to those in Comparative Examples 1-3 in all key performance aspects, effectively solving the technical problems of easy agglomeration of nanoparticles, weak interfacial bonding, and the difficulty in simultaneously achieving anti-adhesion and low roughness. Specifically, the peel strength of Examples 1-3 is significantly lower than that of all comparative examples, with Example 3 having a peel strength as low as 12 g / in, while Comparative Examples 1, 2, and 3 are as high as 35 g / in, 28 g / in, and 50 g / in, respectively. This demonstrates that the bifunctional modifier containing perfluoroalkyl and siloxane groups successfully endows the film surface with excellent anti-adhesion properties, and its perfluoroalkyl segments migrate to the surface and accumulate, forming a low surface energy layer. Meanwhile, the thermal shrinkage rates of Examples 1-3 were all below 1.7%, far lower than the 3.0% of Comparative Example 1 and 4.0% of Comparative Example 3. This indicates that the combined effect of the surface-modified nanoparticles and the hyperbranched multi-arm block polyester-siloxane synergistic interface modifier significantly enhanced the interfacial bonding force between the nanoparticles and the polyester matrix, suppressing thermal dimensional instability caused by interfacial defects and internal stress concentration. In terms of mechanical properties, the tensile strength of Examples 1-3 was all above 52 MPa, while that of Comparative Examples 1, 2, and 3 was only 40 MPa, 35 MPa, and 30 MPa, respectively. This directly confirms that the hyperbranched multi-arm block polyester-siloxane synergistic interface modifier, through its hyperbranched structure and the synergistic effect of siloxane and polyester segments, constructs a strong and flexible interfacial layer between the inorganic nanoparticles and the organic polymer matrix, effectively transferring and dispersing stress, and avoiding the problem of strength reduction caused by nanoparticles becoming stress concentration points when unmodified or with weak interfacial bonding. Crucially, Examples 1-3 achieved extremely low peel strength while maintaining high contact angles (all greater than 102°) and low dielectric constants (all not higher than 3.2), whereas Comparative Examples 1 and 3 exhibited low contact angles and high dielectric constants. This indicates that the untreated nanoparticles in the comparative examples severely agglomerated in the matrix, resulting in increased surface roughness and deteriorated dielectric properties. Although Comparative Example 2 used surface-modified particles, it lacked a synergistic interface regulator, and its performance was still inferior to the examples, demonstrating the indispensability and synergistic effect of the two modified compounds. In summary, this invention achieves uniform dispersion and strong interfacial bonding of nanoparticles in the matrix by surface modification with a bifunctional modifier containing perfluoroalkyl and siloxane groups, combined with the bridging effect of a hyperbranched multi-arm block polyester-siloxane synergistic interface regulator. This results in the successful preparation of a high-quality release film with excellent anti-adhesion properties, low thermal shrinkage, high mechanical strength, good hydrophobicity, and ideal dielectric properties.

[0072] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a release film for a multilayer ceramic capacitor, characterized in that the steps include... include: S1. Mix spherical silica and alumina, add anhydrous ethanol, and disperse by ultrasonication; Subsequently, a modifier containing bifunctional groups of perfluoroalkyl and siloxane was added, and the mixture was mechanically stirred in a water bath at 68-72℃. Then, it was centrifuged, washed with ethanol, and dried in a vacuum drying oven at 74-76℃ to obtain a surface-modified bimodal nanoparticle composite. S2. Polyethylene terephthalate, surface-modified bimodal nanoparticle composite, hyperbranched multi-arm block polyester-siloxane synergistic interface modifier, polyethylene wax, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite are premixed in a high-speed mixer to obtain a premix; the premix is ​​added to a twin-screw extruder through the main feeding system, while surface-modified bimodal nanoparticle composite is added through the side feeding system, and the mixture is melt-blended and extruded, water-cooled, drawn into strips and granulated to obtain a release film functional masterbatch; S3. The release film functional masterbatch is mixed with polyethylene terephthalate and melt-extruded through an extruder. It is then cast through a flat die at 278-282℃ and quenched with a chilling roller at 28-32℃ to form an unshaped casting. The casting is first stretched longitudinally at a preheating temperature of 84-86℃, a stretching temperature of 94-96℃, and a stretching ratio of 3.4-3.6 times. Then it is stretched transversely at a preheating temperature of 88-92℃, a stretching temperature of 104-106℃, and a stretching ratio of 3.6-3.9 times. Finally, it is heat-set at 208-212℃, cooled, and then wound up.

2. The method for preparing the release film for multilayer ceramic capacitors according to claim 1, characterized in that, In step S2, the temperature of melt blending extrusion is 260-280℃, and the screw speed is 400-600 r / min.

3. The method for preparing the release film for multilayer ceramic capacitors according to claim 1, characterized in that, In step S3, the heat setting treatment at 208-212℃ takes 10-12 seconds.

4. The method for preparing a release film for a multilayer ceramic capacitor according to claim 1, characterized in that, The preparation method of the modified agent containing perfluoroalkyl and siloxane bifunctional groups includes: A1, under a dry nitrogen atmosphere, dissolving perfluorohexylethanol and triethylamine in anhydrous tetrahydrofuran, cooling to 0-5°C in an ice-water bath; then adding acryloyl chloride dropwise, controlling the reaction temperature at 8-10°C; after the addition is complete, raising the temperature to room temperature, filtering, and distilling under reduced pressure to obtain intermediate 1; A2, dissolving intermediate 1 and 3-mercaptopropyltriethoxysilane in toluene, adding azobisisobutyronitrile, and carrying out a thiol-ene click reaction at 78-82°C; after the reaction is completed, rotating the evaporator to achieve the desired effect.

5. The method for preparing a release film for a multilayer ceramic capacitor according to claim 4, characterized in that, In step A1, the reaction time to room temperature is 12-14 hours.

6. The method for preparing a release film for a multilayer ceramic capacitor according to claim 4, characterized in that, In step A2, the thiol-ene click reaction time is 6-8 hours.

7. The method for preparing a release film for a multilayer ceramic capacitor according to claim 1, characterized in that, The preparation method of the hyperbranched multi-arm block polyester-siloxane synergistic interface regulator includes: B1, firstly, adding pentaerythritol and 2,2-dimethylolpropionic acid, N,N-dimethylformamide and p-toluenesulfonic acid to a dry reactor, and reacting at 134-136℃ to generate a second-generation hyperbranched polyester; then cooling the reaction system to 78-82℃, adding isocyanate propyltriethoxysilane and dibutyltin dilaurate for reaction; B2, then adding a mixture of monohydroxy-terminated polydimethylsiloxane and monoamino-terminated polycaprolactone, and continuing the reaction at 84-86℃; finally, adding 3-isocyanate propyltriethoxysilane for end-capping reaction, and purifying after the reaction is completed.

8. The method for preparing a release film for a multilayer ceramic capacitor according to claim 7, characterized in that, In step B1, the reaction time is 8-10 h at 134-136 °C; the reaction time is 3-4 h after adding isocyanate propyltriethoxysilane and dibutyltin dilaurate.

9. The method for preparing a release film for a multilayer ceramic capacitor according to claim 7, characterized in that, In step B2, the reaction continues at 84-86℃ for 6-8 hours.

10. A release film for a multilayer ceramic capacitor prepared by the method according to any one of claims 1-9, characterized in that, The raw materials include the following parts by weight: 80-95 parts by weight of polyethylene terephthalate; 3-10 parts by weight of spherical silica; 1-5 parts by weight of alumina; 0.5-3 parts by weight of a bifunctional modifier containing perfluoroalkyl and siloxane groups; 1-5 parts by weight of a hyperbranched multi-arm block polyester-siloxane synergistic interface regulator; 0.1-1 parts by weight of polyethylene wax; 0.1-0.5 parts by weight of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; and 0.1-0.5 parts by weight of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite.