MLCC release film, method of making and use thereof

Abstract

The application relates to the field of high polymer chemical industry and discloses an MLCC release film and a preparation method and application thereof. The surface roughness Ra of the release film is less than or equal to 25 nm, the surface roughness Rq is less than or equal to 50 nm, and the surface roughness Rz is less than or equal to 293 nm. The preparation method of the MLCC release film comprises the following steps: S1, under esterification reaction conditions, carrying out first-stage reaction on a binary acid monomer, a binary alcohol monomer and a catalyst to obtain a reactant I; S2, under polycondensation reaction conditions, mixing the reactant I and a dispersion liquid containing spherical nanosilica to carry out second-stage reaction to obtain an MLCC release film base film polyester; the median particle size of the spherical nanosilica is 150-800 nm, and the span is 1.2-2.5; and S3, after the MLCC release film base film polyester and a conventional polyester are mixed, the mixture is stretched into a film. The release film has low surface roughness and can meet the peeling requirement, and is convenient for subsequent application in the preparation of a multilayer ceramic capacitor.

Description

Technical Field

[0001] This invention relates to the field of polymer chemistry, specifically to a release film for MLCCs, its preparation method, and its application. Background Technology

[0002] The release film for MLCCs (Multi-Layer Ceramic Capacitors) is mainly used in their production. MLCCs are widely used and are often referred to as "industrial rice," with primary end-use applications including smartphones, laptops, automotive electronics, and smart wearable devices. The MLCC manufacturing process involves using a polyester film as a base film. First, an organosilicon coating is coated onto the base film to create a release film. Then, liquid clay is uniformly coated onto the organosilicon coating surface. Electrodes are then printed on the clay layer. The printed electrode clay layers are then stacked, pressed, and sintered for shaping. After further processing, such as cutting, the MLCC is manufactured into a multi-layer ceramic chip capacitor.

[0003] The release film for MLCCs is a key material, serving to support the ceramic layer. Its uniform thickness, good peelability, and smoothness must ensure easy peeling after drying without damaging the dielectric layer, allowing for subsequent MLCC lamination. The key material of the release film is the base film. Polyester film, compared to other plastic films, possesses excellent dimensional stability, chemical resistance, and good processability, thus being used as the base film for MLCC release films. An opening agent needs to be added to the polyester base film to prevent adhesion and provide a smooth surface. However, existing polyester base films often result in uneven coatings after subsequent coating processes, affecting the peelability and smoothness of the release film, and negatively impacting the processing of the ceramic layer, particularly affecting the uniformity of the ceramic layer's thickness.

[0004] Chinese patent application 201911336964.2 describes a release film base film comprising a first layer, a second layer, and a third layer. The third layer contains 50 grams of a third-layer modified polyester base material and 50 grams of a third-layer surface modifier. The third-layer modified polyester base material contains 1 gram of a first copolyester and 49 grams of a third-layer polyester base material. This invention introduces a copolyester to improve stiffness, but its preparation process is complex, increasing the complexity of using recycled film materials. Furthermore, the introduced inorganic filler is added through blending, making it difficult to ensure uniformity. Chinese patent application 201911337225.5 discloses a release film base film for high-adhesion MLCC manufacturing and its preparation method. The product of this invention includes a first layer, a second layer, and a third layer. The components of the coating liquid for the third layer include resin, N,N-dimethylethanolamine, surfactant, defoamer, curing agent, etc. After cross-linking, the resin forms a dense resin layer, which can effectively block oligomers, prevent them from entering the release layer, and reduce residual adhesion. This invention introduces a lot of organic additives. Chinese patent applications 202011063754.3, 202011014739.X, and 202111585609.6 also use a similar coating liquid curing method to prepare MLCC films. It is difficult to ensure the uniformity of the curing reaction through the film forming process. Chinese patent application 202111623727.1 discloses an ABA-type release film base film. The polyester layer A is produced by in-situ polymerization, with nano-silica particles added during the esterification feeding stage to improve dispersion. The online coated surface is smoothed by the coating liquid's coverage of the nanoparticles in layer A and the leveling properties of the coating liquid. The uncoated surface is smoothed by the good dispersion of the in-situ copolymerized nano-silica, thus solving the problem of coexistence of openness and smoothness. The nanoparticles used in this invention are gas-phase inorganic nanomaterials with a particle size between 100-150 nm. When gas-phase inorganic nanomaterials are fed during the esterification stage, their particle size is too small to achieve uniform dispersion.

[0005] Although the preparation of MLCC release film base film has been improved in recent years through online coating, introduction of copolyester, and blending with nanomaterials, it still cannot meet the requirements for stable MLCC production in terms of reducing roughness, reusing film materials, and uniform dispersion of inorganic fillers. Summary of the Invention

[0006] The purpose of this invention is to overcome the technical problem of high roughness of the base film of MLCC release film in the prior art, and to provide an MLCC release film, its preparation method and application.

[0007] The inventors of this invention unexpectedly discovered during their research that by adding spherical nano-silica to the polyester base film of MLCC release film during the reaction process and limiting the median particle size d (0.50) and spacing of the spherical nano-silica, uniform dispersion of the spherical nano-silica in the polyester matrix can be achieved. This effectively reduces the surface roughness of the MLCC release film and lowers its viscosity, making its friction coefficient meet requirements and achieving an anti-adhesion effect, facilitating subsequent peeling and application in the fabrication of multilayer ceramic chip capacitors. Furthermore, the basic component of the MLCC release film remains conventional polyester, which is beneficial for subsequent recycling. Based on these findings, this invention is proposed.

[0008] To achieve the above objectives, the first aspect of the present invention provides a release film for MLCCs, wherein the release film has a surface roughness Ra less than or equal to 25 nm, a surface roughness Rq less than or equal to 50 nm, a surface roughness Rz less than or equal to 293 nm, and a coefficient of friction less than or equal to 0.4.

[0009] The film roughness index is tested using a roughness tester. Ra: Arithmetic mean height, representing the arithmetic mean of the absolute values ​​of the heights to the plane; Rz: Maximum height of the film, representing the distance from the highest point to the lowest point on the surface; Rq: Root mean square height of the film, which is equivalent to the standard deviation of the distance to the average plane, i.e., the standard deviation of the height.

[0010] According to the present invention, the dynamic friction coefficient and static friction coefficient of the release film are both less than or equal to 0.4.

[0011] Preferably, the surface roughness Rp of the release film is less than or equal to 190 nm. Wherein, Rp: maximum peak height of the film, representing the maximum value of the average surface height to the surface.

[0012] A second aspect of the present invention provides a method for preparing a release film for MLCCs, the method comprising the following steps:

[0013] S1. Under esterification reaction conditions, a dicarboxylic acid monomer, a diol monomer, and a catalyst are subjected to a first-stage reaction to obtain reactant I.

[0014] S2. Under polycondensation reaction conditions, reactant I and a dispersion containing spherical nano-silica are mixed to carry out a second-stage reaction to obtain polyester for MLCC release film base film; the spherical nano-silica has a median particle size of 150-800 nm and a particle size spacing of 1.2-2.5.

[0015] S3. The MLCC release film base film is mixed with polyester and conventional polyester and then stretched into a film to obtain the MLCC release film.

[0016] The third aspect of the present invention provides the application of the above-described MLCC release film or the MLCC release film prepared by the above-described method in the preparation of chip multilayer ceramic capacitors.

[0017] The fourth aspect of the present invention provides the application of the MLCC release film described above or the MLCC release film prepared by the above method in the manufacture of smartphones, laptops or automobiles.

[0018] The MLCC release film provided by this invention has a surface roughness index Ra less than or equal to 25 nm, a surface roughness Rq less than or equal to 50 nm, a surface roughness Rz less than or equal to 293 nm, and a friction coefficient less than or equal to 0.4. This low surface roughness and viscosity achieve an anti-adhesion effect, facilitating subsequent peeling and application in the fabrication of multilayer ceramic chip capacitors. Furthermore, the basic component of the MLCC release film remains conventional polyester, which is beneficial for subsequent recycling. Attached Figure Description

[0019] Figure 1 This is a SEM image of the silica used in Example 1;

[0020] Figure 2 This is a SEM image of the silica used in Comparative Example 3;

[0021] Figure 3 This is a SEM image of the silica used in Comparative Example 4. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] As mentioned above, the first aspect of the present invention provides a release film for MLCCs, wherein the surface roughness Ra of the release film is less than or equal to 25 nm, the surface roughness Rq is less than or equal to 50 nm, the surface roughness Rz is less than or equal to 293 nm, and the coefficient of friction is less than or equal to 0.4.

[0024] The film roughness index is tested using a roughness tester. Ra: Arithmetic mean height, representing the arithmetic mean of the absolute values ​​of the heights to the plane; Rz: Maximum height of the film, representing the distance from the highest point to the lowest point on the surface; Rq: Root mean square height of the film, which is equivalent to the standard deviation of the distance to the average plane, i.e., the standard deviation of the height.

[0025] According to the present invention, the surface roughness parameters are tested under white light interference conditions, and the testing instrument is a laser confocal microscope. The friction coefficient includes the dynamic friction coefficient and the static friction coefficient, and both the dynamic friction coefficient and the static friction coefficient of the release film are less than or equal to 0.4.

[0026] The MLCC release film provided by this invention has a smooth surface and low viscosity, achieving an anti-adhesion effect and facilitating subsequent peeling, thus enabling its application in the fabrication of multilayer ceramic chip capacitors. Furthermore, the basic components of the MLCC release film remain conventional, which is beneficial for subsequent reuse.

[0027] According to the present invention, preferably, the surface roughness Rp of the release film is less than or equal to 190 nm. Wherein, Rp: maximum peak height of the film, representing the maximum value of the average surface height to the surface.

[0028] According to the present invention, preferably, the surface roughness Ra of the release film is less than or equal to 15 nm, the surface roughness Rq is less than or equal to 10 nm, and the surface roughness Rz is less than or equal to 50 nm. The release film surface limited by the above conditions is smoother. From the viewpoint of further improving the smoothness of the release film, preferably, the surface roughness Ra of the release film is less than or equal to 7 nm, the surface roughness Rq is less than or equal to 7 nm, and the surface roughness Rz is less than or equal to 46 nm.

[0029] According to the present invention, preferably, the surface roughness Rp of the release film is less than or equal to 40 nm. The release film surface limited by the above conditions is smoother. From the viewpoint of being able to further improve the smoothness of the release film, preferably, the surface roughness Rp of the release film is less than or equal to 35 nm.

[0030] A second aspect of the present invention provides a method for preparing a release film for MLCCs, the method comprising the following steps:

[0031] S1. Under esterification reaction conditions, a dicarboxylic acid monomer, a diol monomer, and a catalyst are subjected to a first-stage reaction to obtain reactant I.

[0032] S2. Under polycondensation reaction conditions, reactant I and a dispersion containing spherical nano-silica are mixed to carry out a second-stage reaction to obtain polyester for MLCC release film base film; the spherical nano-silica has a median particle size of 150-800 nm and a particle size spacing of 1.2-2.5.

[0033] S3. The MLCC release film base film is mixed with polyester and conventional polyester and then stretched into a film to obtain the MLCC release film.

[0034] According to the present invention, the dispersion containing spherical nano-silica may further utilize a dicarboxylic acid monomer and / or a diol monomer as a dispersion solvent. Preferably, the dispersion solvent of the dispersion containing spherical nano-silica is a diol monomer.

[0035] The preparation method described above involves adding spherical nano-silica at the end of the first-stage reaction, limiting the median particle size d (0.50) and spacing of the spherical nano-silica to achieve uniform dispersion of the spherical nano-silica in the polyester matrix. This effectively reduces the surface roughness of the MLCC release film and lowers its viscosity, ensuring its friction coefficient meets requirements and achieving anti-adhesion, facilitating subsequent peeling and application in the fabrication of multilayer ceramic chip capacitors. The release film obtained by the above method has a surface roughness Ra less than or equal to 25 nm, a surface roughness Rq less than or equal to 50 nm, a surface roughness Rz less than or equal to 293 nm, and a friction coefficient less than or equal to 0.4. Moreover, the basic component of the MLCC release film remains conventional polyester, which is beneficial for subsequent recycling.

[0036] The release film can be a film with the aforementioned surface roughness, prepared by any method using spherical nano-silica and polyester. Preferably, the release film contains polyester for MLCC release film base film and conventional polyester, with a mass ratio of 1:0.7-3. Preferably, the raw material components of the polyester for MLCC release film base film contain diacid monomers, diol monomers, spherical nano-silica, and a catalyst. By adding spherical nano-silica to the raw material components of the polyester for MLCC release film base film and mixing the polyester for MLCC release film base film and conventional polyester according to the above mass ratio, the resulting release film has high smoothness and a low coefficient of friction, meeting the peeling requirements and facilitating its subsequent application in the preparation of multilayer ceramic chip capacitors.

[0037] In this invention, the conventional polyester can be a commercially available polyester commonly used for preparing MLCC release films, or a polyester prepared by conventional methods in the art. Exemplarily, the preparation method of the conventional fiber includes the following steps: mixing antimony glycolate catalyst, terephthalic acid (PTA), and ethylene glycol (EG) at a weight ratio of 1:2800-3200:1600-2000, and carrying out a conventional esterification reaction under conditions of a gauge pressure of 0.2-0.3 MPa and a temperature of 200-300°C; after the esterification reaction, carrying out a pre-condensation reaction at 260-275°C for 40-50 min, and finally controlling the condensation reaction temperature at 270-285°C for a final condensation reaction, with an absolute pressure below 100 Pa, and accumulating a condensation time of 100-110 min after the stirring current in the reactor reaches the set value; the melt is then extruded by a melt pump, pelletized, and dried to obtain the conventional polyester.

[0038] Preferably, the content of the spherical nano-silica in the release film is 0.1-0.6 wt%, specifically 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, or any value between these values. Limiting the content of the spherical nano-silica to the above range can further improve the surface smoothness of the prepared release film and reduce the coefficient of friction. Further preferably, considering the ability to further reduce the surface roughness of the release film, the content of the spherical nano-silica in the release film is 0.1-0.25 wt%.

[0039] Preferably, the median particle size d(0.50) of the spherical nano-silica is 150-800 nm, specifically 150 nm, 300 nm, 450 nm, 600 nm, 750 nm, 800 nm, or any value between these values; the particle size distribution is 1.2-2.5, specifically 1.2, 1.5, 2, 2.5, or any value between these values. Using the above conditions for the spherical nano-silica can further improve the surface smoothness of the prepared release film and reduce the coefficient of friction. Considering the ability to further reduce the surface roughness of the release film, it is further preferred that the median particle size d(0.50) of the spherical nano-silica is 150-400 nm, and the particle size distribution is 1.5-2.5.

[0040] According to the present invention, preferably, the dicarboxylic acid monomer is selected from at least one of terephthalic acid, isophthalic acid and adipic acid; more preferably, it is terephthalic acid.

[0041] According to the present invention, preferably, the diol monomer is ethylene glycol and / or pentanediol; more preferably, it is ethylene glycol.

[0042] According to the present invention, preferably, the catalyst is an organoantimony catalyst; more preferably, it is antimony glycol.

[0043] In this invention, the aforementioned dicarboxylic acid monomer, diol monomer, spherical nano-silica, polyethylene glycol, and catalyst are all commercially available or can be prepared by methods disclosed in the prior art.

[0044] According to the present invention, the amounts of the diacid monomer and the diol monomer can be determined according to the specific requirements of the release film. Preferably, the weight ratio of the diacid monomer to the diol monomer is 1-2.5:1, specifically 1:1, 1.5:1, 2:1, 2.5:1, or any value between these values; more preferably, it is 1.5-1.8:1. The inventors have found that, under this preferred embodiment, it is beneficial to improve the surface smoothness of the prepared release film.

[0045] According to the present invention, the amounts of bis(hydroxyethyl) isophthalate and the catalyst can be specifically determined according to actual conditions. Preferably, the amount of catalyst added to the polyester base film of the MLCC release film is 0.01-0.04 wt%. The inventors have found that the surface of the release film prepared under the above conditions is smoother.

[0046] Preferably, in step S1, the esterification reaction conditions include at least: a temperature of 250-260°C and an absolute pressure of 0.2-0.4 MPa. The inventors have found that under this preferred embodiment, the spherical silica and polyester can be mixed more uniformly during the preparation process, thereby improving the surface smoothness of the subsequently prepared release film. The termination condition of the first-stage reaction can be determined by the experimenter based on the actual situation, for example, determining whether to terminate the first-stage reaction based on the amount of water in reactant I.

[0047] Preferably, in step S2, the polycondensation reaction conditions include: an initial temperature equal to the esterification reaction temperature, a heating rate of 0.4-0.7℃, and a maximum temperature of 275-285℃. The inventors have found that this preferred embodiment is beneficial for improving the surface smoothness of the obtained release film. The conditions for the end of the second-stage reaction include: the stirring current reaching a preset value.

[0048] According to the present invention, the preset value of the stirring current can be determined by the test personnel based on the actual situation.

[0049] In this invention, the method for preparing the release film further includes: extruding, pelletizing, and drying the mixed mixture before stretching it into a film. The extrusion, pelletizing, and drying methods can employ conventional techniques and equipment.

[0050] The third aspect of this invention provides the application of the MLCC release film described in any technical solution of the first aspect and the MLCC release film prepared by the preparation method described in any technical solution of the second aspect in the preparation of chip multilayer ceramic capacitors.

[0051] The fourth aspect of this invention provides the application of the MLCC release film described in any technical solution of the first aspect and the MLCC release film prepared by the preparation method described in any technical solution of the second aspect in the manufacture of smartphones, laptops or automobiles.

[0052] According to a particularly preferred embodiment of the present invention, the method for preparing an MLCC release film includes the following steps:

[0053] S1. Terephthalic acid, ethylene glycol, and antimony glycol are reacted at a temperature of 250-260℃ and an absolute pressure of 0.2-0.4 MPa; after the reaction is completed, reactant I is obtained.

[0054] The weight ratio of terephthalic acid to ethylene glycol is 1-2.5:1;

[0055] A dispersion of spherical nano-silica was obtained by mixing spherical nano-silica with a median particle size d(0.50) of 150-400 nm and a particle size spacing of 1.5-2.5 nm with ethylene glycol dispersion solvent.

[0056] S2. The reactant I and the dispersion are mixed and reacted at a heating rate of 0.4-0.7°C; after the temperature reaches 275-285°C, the reaction continues at this temperature, and after the stirring current reaches a preset value, polyester for MLCC release film base film is obtained.

[0057] S3. The MLCC release film base film is mixed with polyester and conventional polyester at a mass ratio of 1:0.7-3, then extruded, granulated and dried, and then stretched into a film to obtain the MLCC release film. In the release film, the content of the spherical nano silica is 0.1-0.25 wt%.

[0058] The above method, under the binary reaction system of terephthalic acid and ethylene glycol, introduces spherical nano-silica at the end of the esterification reaction, and limits the particle size and spacing of the spherical nano-silica to achieve uniform dispersion of the spherical nano-silica in the polyester matrix. The MLCC release film base film prepared by melt extrusion and biaxial stretching of the polyester of this invention has the advantages of uniform inorganic powder dispersion and low roughness, and a friction coefficient of less than 0.4, meeting the peeling requirements. Furthermore, the matrix composition of the release film base film is still conventional polyester, which is beneficial for subsequent recycling.

[0059] The present invention will be described in detail below through embodiments.

[0060] In the following examples, unless otherwise specified, all other raw materials and reagents used are conventional commercial products, and their purity is chemically pure.

[0061] The aforementioned film roughness parameters were tested using a roughness tester. Ra: Arithmetic mean height, representing the arithmetic mean of the absolute values ​​of the heights to the average surface of the plane; Rz: Maximum film height, representing the distance from the highest point to the lowest point on the surface; Rq: Root mean square height of the film, equivalent to the standard deviation of the distance to the average surface, i.e., the standard deviation of the height. The coefficient of friction was measured according to GB / T 10006-2021.

[0062] The following examples and comparative examples illustrate the preparation methods of conventional polyesters:

[0063] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycol catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under the conditions of gauge pressure of 0.25MPa and temperature of 255℃. After the esterification reaction was completed, the temperature was gradually increased to carry out a pre-condensation reaction for 45min, and a final condensation reaction was carried out at 280℃. After the stirring current of the reactor reached the set value, the melt was extruded by a melt pump, pelletized, and dried to obtain polyester for conventional base film.

[0064] Example 1

[0065] Spherical silica nanoparticles were dispersed in ethylene glycol to prepare a 10% (w / w) suspension slurry. The median particle size d(0.5) of the silica nanoparticles was 400 nm, and the particle size spacing was 1.5. See the scanning electron microscope image for details. Figure 1 .

[0066] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycol catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 289.15g of suspension slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for MLCC release film base film, with a nano-silica content of 0.50%.

[0067] The MLCC release film base film was obtained by blending 2000g of polyester with 2000g of conventional polyester, drying, melt extruding, and biaxially stretching. The mass content of spherical nano-spherical silica in the film was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0068] Example 2

[0069] Spherical nano-silica was dispersed in ethylene glycol to prepare a suspension slurry with a mass concentration of 10%. The median particle size d(0.5) of the nano-silica was 400 nm and the particle size spacing was 1.5.

[0070] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycol catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 115.66g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for MLCC release film base film, with a nano-silica content of 0.20%.

[0071] The MLCC release film base film was blended with 2000g of conventional polyester, dried, melt-extruded, and biaxially stretched to form a film. The mass content of spherical nano-silica in the film was 0.10%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0072] Example 3

[0073] Spherical nano-silica was dispersed in ethylene glycol to prepare a suspension slurry with a mass concentration of 10%. The median particle size d(0.5) of the nano-silica was 400 nm and the particle size spacing was 1.5.

[0074] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycol catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 578.30g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for MLCC release film base film, with a nano-silica content of 1.00%.

[0075] The MLCC release film base film was obtained by blending 2000g of polyester with 1400g of conventional polyester, drying, melt extruding, and biaxially stretching. The mass content of spherical nano-silica in the film was 0.588%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0076] Example 4

[0077] Spherical nano-silica was dispersed in ethylene glycol to prepare a 10% by mass suspension slurry. The median particle size d(0.5) of the nano-silica was 400 nm and the particle size spacing was 2.5.

[0078] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycol catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 289.15g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for MLCC release film base film, with a nano-silica content of 0.50%.

[0079] The MLCC release film base film was obtained by blending 2000g of polyester with 4000g of conventional polyester, drying, melt extruding, and biaxially stretching. The mass content of spherical nano-silica in the film was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0080] Example 5

[0081] Spherical nano-silica was dispersed in ethylene glycol to prepare a suspension slurry with a mass concentration of 10%. The median particle size d(0.5) of the nano-silica was 150 nm and the particle size spacing was 2.0.

[0082] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycol catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 289.15g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for MLCC release film base film, with a nano-silica content of 0.50%.

[0083] The MLCC release film base film was obtained by blending 2000g of polyester with 6000g of conventional polyester, drying, melt extruding, and biaxially stretching. The mass content of spherical nano-silica in the film was 0.125%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0084] Example 6

[0085] Spherical nano-silica was dispersed in ethylene glycol to prepare a suspension slurry with a mass concentration of 10%. The median particle size d(0.5) of the nano-silica was 800 nm and the particle size spacing was 1.5.

[0086] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycol catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 578.3g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for MLCC release film base film, with a nano-silica content of 0.50%.

[0087] The MLCC release film base film was blended with 2000g of conventional polyester, dried, melt-extruded, and biaxially stretched to form a film. The mass content of spherical nano-silica in the film was 0.50%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0088] Example 7

[0089] Spherical nano-silica was dispersed in ethylene glycol to prepare a suspension slurry with a mass concentration of 10%. The median particle size d(0.5) of the nano-silica was 400 nm and the particle size spacing was 1.5.

[0090] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycol catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 289.15g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for MLCC release film base film, with a nano-silica content of 0.50%.

[0091] The MLCC release film base film was blended with 2000g of polyester and 4000g of conventional polyester, dried, and used as the A layer surface in the ABA three-layer film form. It was then melt-extruded and biaxially stretched to form the MLCC release film. The mass content of spherical nano-silica in the film surface layer was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0092] Example 8

[0093] Spherical nano-silica was dispersed in ethylene glycol to prepare a 10% by mass suspension slurry. The median particle size d(0.5) of the nano-silica was 400 nm and the particle size spacing was 1.5.

[0094] 3000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 0.67g of antimony acetate catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.4MPa gauge pressure and 250℃. After the esterification reaction was completed, 289.15g of suspension slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 275℃. After the reactor stirring current reached the set value, the melt was extruded by a melt pump, pelletized, and dried to obtain 5783g of polyester for MLCC release film base film, of which the mass content of nano-silica was 0.50%.

[0095] The MLCC release film base film was blended with 2000g of conventional polyester, dried, melt-extruded, and biaxially stretched to form a film. The mass content of nano-spherical silica in the film was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0096] Example 9

[0097] Spherical nano-silica was dispersed in ethylene glycol to prepare a 10% by mass suspension slurry. The median particle size d(0.5) of the nano-silica was 400 nm and the particle size spacing was 1.5.

[0098] 5000g of terephthalic acid (PTA), 2000g of ethylene glycol (EG), and 2.8g of antimony glycolate catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.2MPa gauge pressure and 260℃. After the esterification reaction was completed, 289.15g of suspension slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 285℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for MLCC release film base film, with a nano-silica content of 0.50%.

[0099] The MLCC release film base film was blended with 2000g of conventional polyester, dried, melt-extruded, and biaxially stretched to form a film. The mass content of nano-spherical silica in the film was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0100] Example 10

[0101] MLCC release films were prepared according to the method described in Example 1, except that terephthalic acid was replaced with isophthalic acid.

[0102] Example 11

[0103] The MLCC release film was prepared according to the method described in Example 1, except that ethylene glycol was replaced with pentanediol.

[0104] Comparative Example 1

[0105] Conventional micron-sized silica was dispersed in ethylene glycol to prepare a 10% by mass suspension slurry with a median silica particle size d(0.5) of 3000 nm and a particle size spacing of 1.5.

[0106] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycolate catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 289.15g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded by a melt pump, pelletized, and dried to obtain 5783g of polyester for the base film, with a silica content of 0.50%.

[0107] MLCC release film was obtained by blending 2000g of conventional base film with 2000g of conventional polyester, drying, melt extrusion, and biaxial stretching. The silica content in the film was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this comparative example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0108] Comparative Example 2

[0109] Spherical nano-silica was dispersed in ethylene glycol to prepare a suspension slurry with a mass concentration of 10%. The median particle size d(0.5) of the nano-silica was 100 nm and the particle size spacing was 1.5.

[0110] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycolate catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 289.15g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for the base film, with a nano-silica content of 0.50%.

[0111] The base film was blended with 2000g of conventional polyester, dried, melt-extruded, and biaxially stretched to form a MLCC release film. The mass content of spherical nano-silica in the film was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this comparative example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0112] Comparative Example 3

[0113] Spherical silica nanoparticles were dispersed in ethylene glycol to prepare a 10% (w / w) suspension slurry. The median particle size d(0.5) of the silica nanoparticles was 400 nm, and the particle size spacing was 3.0. See the scanning electron microscope image for details. Figure 2 .

[0114] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycolate catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 289.15g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded, pelletized, and dried using a melt pump to obtain 5783g of polyester for the base film, with a nano-silica content of 0.50%.

[0115] The base film was blended with 2000g of conventional polyester, dried, melt-extruded, and biaxially stretched to form a MLCC release film. The mass content of spherical nano-silica in the film was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this comparative example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0116] Comparative Example 4

[0117] Bulk-sized nano-silica was dispersed in ethylene glycol to prepare a 10% (w / w) suspension slurry. The median particle size d(0.5) of the nano-silica was 400 nm, and the particle size spacing was 3.0. See the scanning electron microscope image for details. Figure 3 .

[0118] 5000g of terephthalic acid (PTA), 3000g of ethylene glycol (EG), and 1.67g of antimony glycolate catalyst were added to a 20L general-purpose polymerization reactor. A conventional esterification reaction was carried out under conditions of 0.25MPa gauge pressure and 255℃. After the esterification reaction was completed, 289.15g of slurry was added. A pre-condensation reaction was carried out by gradually increasing the temperature for 45min, followed by a final condensation reaction at 280℃. After the reactor stirring current reached the set value, the melt was extruded by a melt pump, pelletized, and dried to obtain 5783g of polyester for the base film, with a silica content of 0.50%.

[0119] The base film was blended with 2000g of conventional polyester, dried, melt-extruded, and biaxially stretched to form a MLCC release film. The silica content in the film was 0.25%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this comparative example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0120] Comparative Example 5

[0121] The polyester for MLCC release film base film was prepared in the same manner as in Example 6.

[0122] The MLCC release film base film was directly blended with polyester, dried, melt-extruded, and biaxially stretched to form a film. The content of spherical nano-silica in the film was 1.00%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this comparative example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0123] Comparative Example 6

[0124] Polyester for MLCC release film base film was prepared in the same manner as in Example 1.

[0125] The MLCC release film base film was obtained by blending 300g of polyester with 2700g of conventional polyester, drying, melt extruding, and biaxially stretching. The content of spherical nano-silica in the film was 0.05%. The roughness index and friction coefficient of the film were tested. The relevant test parameters in this comparative example are shown in Table 1, and the measured product parameters are shown in Table 2.

[0126] Table 1

[0127]

[0128]

[0129] Table 2

[0130]

[0131]

[0132] As can be seen from the data in Table 2, the test results of the films in the examples are all within the protection scope of this invention. Compared with the base film of Comparative Example 1, the roughness index of the examples in this invention is significantly reduced, achieving the purpose of preparing MLCC release base films. The data in Table 2 show that the spherical silica used in this invention has the following characteristics: spherical shape, median particle size d(0.50) of 150nm-800nm, and a diameter spacing of 1.2-2.5. The films prepared using spherical silica have a roughness less than or equal to 25nm, with a minimum of 6.5nm; a surface roughness Rq less than or equal to 50nm, with a minimum of 6.9nm; and a surface roughness Rz less than or equal to 293nm, with a minimum of 45.3nm. This indicates that the prepared films have good flatness, and the coefficient of friction is less than 0.4, ensuring that the films can play an anti-adhesion role in subsequent processing and are practical. While bulk nano-silica can reduce roughness to some extent, it doesn't achieve monodispersity in actual production, resulting in inconsistent particle sizes. Small particles increase crystallization and secondary agglomeration, while large particles increase film roughness, hindering smoothness improvement. Comparative Example 4 demonstrates this high roughness. Regarding the particle size range of spherical nano-silica, while smaller particles are beneficial for reducing film roughness, Comparative Example 2 shows that excessively small particles have strong internal forces, making dispersion difficult and leading to severe agglomeration, resulting in increased film roughness. Conversely, excessively large particles result in greater surface roughness. Comparative Example 3 shows that when the particle size distribution of spherical nano-silica is too wide, the varying particle sizes increase crystallinity and film roughness, hindering the preparation of high-quality MLCC release films. Comparative Example 5 shows that an excessive amount of nano-spherical silica in the film increases roughness and also increases the risk of powder agglomeration within the film. Comparative Example 6 shows that when there is too little spherical silica, the coefficient of friction is too high to be measured, thus failing to facilitate subsequent peeling, and its high coefficient of friction also fails to prevent adhesion.

[0133] Considering the performance requirements of MLCC release films, the preparation methods of MLCC release films provided in Examples 1-11 are adopted. By adding spherical silica with appropriate particle size and spacing during the preparation of the ester for the MLCC release film base film, the surface roughness of the MLCC release film can be effectively reduced, and its viscosity can be reduced, so that its friction system meets the requirements, achieving the effect of anti-adhesion and facilitating subsequent peeling.

[0134] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A release film for MLCCs, characterized in that, The release film has a surface roughness Ra less than or equal to 20.2 nm, a surface roughness Rq less than or equal to 26.9 nm, a surface roughness Rz less than or equal to 168.7 nm, a surface roughness Rp less than or equal to 110.9 nm, and a friction coefficient less than or equal to 0.

4. The release film contains spherical nano-silica with a median particle size of 150-400 nm and a particle size spacing of 1.5-2.5 mm. The amount of spherical nano-silica added to the release film is 0.1-0.25 wt%.

2. The MLCC release film according to claim 1, characterized in that, The release film has a surface roughness Ra of less than or equal to 15 nm, a surface roughness Rq of less than or equal to 10 nm, and a surface roughness Rz of less than or equal to 50 nm.

3. The MLCC release film according to claim 2, characterized in that, The release film has a surface roughness Ra less than or equal to 7 nm, a surface roughness Rq less than or equal to 7 nm, and a surface roughness Rz less than or equal to 46 nm.

4. The MLCC release film according to claim 3, characterized in that, The surface roughness Rp of the release film is less than or equal to 40 nm.

5. The MLCC release film according to claim 4, characterized in that, The surface roughness Rp of the release film is less than or equal to 35 nm.

6. A method for preparing a release film for MLCCs, characterized in that, The method includes the following steps: S1. Under esterification reaction conditions, a dicarboxylic acid monomer, a diol monomer, and a catalyst are subjected to a first-stage reaction to obtain reactant I. S2. Under polycondensation reaction conditions, reactant I and a dispersion containing spherical nano-silica are mixed to carry out a second-stage reaction to obtain polyester for MLCC release film base film; the spherical nano-silica has a median particle size of 150-400 nm and a particle size spacing of 1.5-2.

5. S3. The MLCC release film base film is mixed with polyester and conventional polyester and stretched into a film to obtain the MLCC release film; in the release film, the amount of spherical nano silica added is 0.1-0.25wt%.

7. The preparation method according to claim 6, characterized in that, The mass ratio of the polyester used in the MLCC release film base film to the conventional polyester is 1:0.7-3.

8. The application of the MLCC release film according to any one of claims 1 to 5 or the MLCC release film prepared according to the method of claim 6 or 7 in the preparation of chip multilayer ceramic capacitors.

9. The use of the MLCC release film according to any one of claims 1 to 5 or the MLCC release film prepared according to the method of claim 6 or 7 in the manufacture of smartphones, laptops or automobiles.

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