MLCC release protective film and preparation method thereof

Abstract

The invention belongs to the technical field of polyester film production and processing, and particularly relates to an MLCC release protective film and a preparation method thereof. The preparation method of the MLCC release protective film comprises the following steps: taking a polyester chip and a master batch as raw materials of an auxiliary extruder I and an auxiliary extruder II, and respectively preparing the polyester chip and the master batch into auxiliary extrusion melts serving as an upper surface layer and a lower surface layer in the auxiliary extruder I and the auxiliary extruder II; the PET melt is conveyed to a metering pump through a pipeline and then filtered, and a main extrusion melt serving as a core layer is obtained; converging and extruding the filtered main extrusion melt and the filtered auxiliary extrusion melt in an ABC type three-layer die head, and forming a cast sheet by electrostatic adsorption through a cold roller after extrusion; longitudinally stretching the casting piece into a thick film; carrying out corona treatment on the thick film; uniformly smearing the coating liquid on the membrane surface; preheating, transversely stretching, transversely shaping and transversely cooling the film in sequence; and finally, rolling and slitting to obtain the release protective film. The method disclosed by the invention solves the problems of low efficiency and high cost in the traditional production.

Description

Technical Field

[0001] The invention belongs to the technical field of polyester film production and processing, and in particular relates to an MLCC release protective film and a preparation method thereof. Background Art

[0002] In the production process of electronic components, especially multilayer ceramic capacitors (MLCC), release films play a vital role. As electronic devices develop towards miniaturization and high functionality, MLCCs also require higher and higher capacity and smaller size, which requires the ceramic dielectric layer of MLCC to be extremely thin, usually with a thickness of only 1 micron per dielectric layer. The preparation of this high-density stacked ultra-thin dielectric layer requires the release film to have extremely high precision and performance.

[0003] In traditional production methods, release protective films are usually produced using non-online silicon coating technology, which results in long production cycles and high costs. In addition, the physical properties of the film, such as elastic modulus, temperature resistance and surface roughness, are insufficient to meet the high-standard MLCC production requirements. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The present invention mainly aims at the above problems and proposes an MLCC release protective film and a preparation method, the purpose of which is to solve the problems of the existing MLCC release protective film in production efficiency, cost control and physical properties.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the present invention provides an MLCC release protective film and a preparation method thereof, the method comprising the following steps:

[0008] Using 80%-90% by weight of polyester chips and 10%-20% by weight of masterbatch as raw materials for auxiliary extruder 1 and auxiliary extruder 2, respectively, in the auxiliary extruder 1 and the auxiliary extruder 2, the polyester chips and the masterbatch are transferred to a metering pump and filtered to prepare auxiliary extrusion melts as the upper surface layer and the lower surface layer;

[0009] The PET melt is transferred to a metering pump through a pipeline and then filtered to obtain a main extrusion melt as a core layer;

[0010] The filtered main extrusion melt and auxiliary extrusion melt are combined and extruded in an ABC three-layer die head, and the extruded melt passes through a cold roller to form a casting sheet by electrostatic adsorption;

[0011] The melt-extruded cast sheet is longitudinally stretched into a thick film;

[0012] performing corona treatment on the thick film to activate its surface and increase its surface energy;

[0013] The coating liquid is evenly spread on the coating roller by a scraper, and the coating roller transfers the coating liquid to the film surface;

[0014] The coated film is sequentially preheated, transversely stretched, transversely shaped and transversely cooled, so that the polymer solution leaves a polymer layer on the film surface;

[0015] Finally, the release protective film is obtained by rolling and slitting.

[0016] Furthermore, the grade of the polyester chips is KH2650A.

[0017] Furthermore, the masterbatch is prepared by mixing 95wt% of slurry, 1.8wt% of catalyst and 3.2wt% of dispersed silica particles, esterification reaction, prepolymerization treatment and polycondensation, wherein the slurry includes 66-73wt% of terephthalic acid and 27%-34% of ethylene glycol, and the catalyst is antimony ethylene glycol.

[0018] Furthermore, the step of evenly spreading the coating liquid on the coating roller by a scraper, and transferring the coating liquid to the film surface by the coating roller includes: guiding the film by an expansion roller so that its edge is pulled outward in a bow shape, and evenly spreading the coating liquid on the coating roller by a scraper, and transferring the coating liquid to one side of the film surface by the coating roller.

[0019] Furthermore, the coating liquid brand is Dow Corning 7920.

[0020] Furthermore, the temperature of the combined extrusion is 275-285°C.

[0021] Furthermore, the corona treatment applies a high-frequency, high-voltage power supply between the metal electrode and the corona treatment roller to ionize the air and form a large amount of ozone, thereby activating the film surface.

[0022] Furthermore, the auxiliary extruder 1 and the auxiliary extruder 2 are both twin-screw extruders.

[0023] To achieve the above-mentioned purpose, the present invention also provides an MLCC release protective film, which is made by the preparation method.

[0024] Furthermore, the release protective film has an ABC three-layer structure, wherein layer A is an upper surface layer composed of polyester chips and masterbatch; layer B is a core layer composed of PET melt; layer C is a lower surface layer composed of polyester chips, masterbatch and coating liquid; wherein the thickness ratio of the three layers ABC is layer A: layer B: layer C = (5-10): (80-90): (5-8), preferably, the thickness ratio of the three layers ABC is layer A: layer B: layer C = (6-8): (83-88): (6-8).

[0025] (III) Beneficial effects

[0026] Compared with the prior art, the MLCC release protective film and preparation method provided by the present invention effectively solves the problems of low efficiency and high cost in traditional production by introducing online silicon coating and biaxial stretching technology. The present invention adopts an integrated production process to integrate the silicon coating and stretching process into online production, avoiding the multiple independent steps required after silicon coating in the traditional method, thereby significantly improving the production speed and reducing energy consumption. In addition, the ABC three-layer structure adopted by the present invention, in which the A layer and the C layer effectively reduce the surface roughness of the film by adding masterbatch. These improvements not only improve the quality of the release film, but also achieve substantial cost savings, meeting the needs of efficient and economical industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of a preparation process of an MLCC release protective film of the present invention. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] The MLCC release protective film has an ABC three-layer structural structure, wherein layer A is an upper surface layer composed of polyester chips and masterbatch; layer B is a core layer composed of PET melt; layer C is a lower surface layer composed of polyester chips, masterbatch and coating liquid, wherein the thickness ratio of the three layers ABC is layer A: layer B: layer C = (5-10): (80-90): (5-8), preferably, the thickness ratio of the three layers ABC is layer A: layer B: layer C = (6-8): (83-88): (6-8); particularly preferably, the thickness ratio of the three layers ABC is layer A: layer B: layer C = 7:86:7.

[0030] The specific process flow of this embodiment is as follows Figure 1 As shown: auxiliary extruder 1 (polyester chips and masterbatch), auxiliary extruder 2 (polyester chips and masterbatch) and (PET melt) - metering pump - filter - melt delivery pipeline - die head - casting - longitudinal drawing - coating - transverse drawing - traction - winding - material inspection - slitting - quality inspection - packaging - warehousing.

[0031] In this embodiment, each link of the production process will be described in detail below, including batching, extrusion, stretching, corona treatment, coating, horizontal stretching and final winding and slitting. Through this process, a high-performance release protective film can be produced.

[0032] 1. Raw materials and ingredients

[0033] 1. Auxiliary extruder 1 and auxiliary extruder 2 batching

[0034] Auxiliary extruder 1: polyester chips (brand KH2650A) and masterbatch.

[0035] Auxiliary extruder 2: polyester chips (brand KH2650A) and masterbatch.

[0036] 2. Masterbatch preparation method

[0037] The slurry (terephthalic acid and ethylene glycol) is mixed with a catalyst (ethylene glycol antimony), and after undergoing an esterification reaction, a prepolymerization treatment (addition of dispersed silica particles) is performed, followed by polycondensation.

[0038] 2. Extrusion process

[0039] 1. Main extruder

[0040] The PET melt is transferred to the metering pump through a pipeline and filtered through a filter to obtain the main extrusion melt as the core layer.

[0041] 2. Auxiliary extruder 1 and auxiliary extruder 2

[0042] The polyester chips and masterbatch are transferred to the metering pump and filtered through the filter to obtain the auxiliary extrusion melt as the upper surface layer and the lower surface layer.

[0043] 3. Melt temperature control

[0044] Since the melting temperature of PET raw material is 265°C, the extruder temperature is set between 275°C and 285°C.

[0045] 4. Extruder equipment

[0046] The twin-screw extruder is used, which is characterized by large output, uniform plasticization and energy saving. The heating method is electric module heating and water cooling. Before the melt enters the ABC three-layer die head, it must first be vacuumed to remove moisture and oligomers in the melt.

[0047] 3. Stretch and Cool Down

[0048] The melt-extruded PET cast sheet is longitudinally stretched into a thick film.

[0049] 4. Corona treatment

[0050] By applying high-frequency, high-voltage power between the metal electrode and the corona treatment roller, the air is ionized and a large amount of ozone is generated. The high-energy electric spark impacts the film surface, activating the film surface, increasing the surface energy, and increasing the wet surface tension of the film.

[0051] 5. Coating process

[0052] 1. Coating equipment

[0053] The film is guided by the expansion roller, and the edge of the film is pulled outward in an arch shape by the expansion roller, thereby tensioning the film. The coating liquid is evenly applied to the film surface by a scraper. The coating liquid brand is Dow Corning 7920. It should be noted that the surface of the expansion roller is designed to be arched (also called arc or arch), so that when the film passes through the expansion roller, its edge will be pulled outward. This outward pulling force can keep the film in a tensioned state in the horizontal direction, preventing the film from wrinkling or loosening in the next process; after passing the expansion roller, the film enters the coating area.

[0054] In the online coating device, scrapers are installed on the upper and lower sides of the coating chamber. Before the coating roller is started, the coating chamber is close to and fits the coating roller to form a closed system. The coating liquid is transported to the coating chamber by the liquid supply system. After the coating roller is started, the liquid is evenly coated on the coating roller under the action of the scraper. The coating roller transfers the coating liquid to the film surface, and the excess coating liquid flows out from the left and right sides of the coating chamber and returns to the liquid supply system. Through the above steps, the film can be smoothly and evenly coated under the guidance and tension of the expansion roller, ensuring the production of high-quality release protective film.

[0055] 2. Coating process

[0056] The film is preheated, transversely stretched, transversely shaped, and transversely cooled in sequence. After the polymer solution is dried in the transverse stretching machine, a layer of coated polymer is left on the surface of the film.

[0057] 6. Winding and Slitting

[0058] Finally, the film is rolled up and slit to obtain the release protective film.

[0059] The polyester film produced by the patent of the present invention adopts the melt direct drawing method, and its structure is an ABC three-layer structure. The addition of polyester chips can provide the basic polymer material, and the addition of corresponding small-size masterbatch in the A and C layers can reduce the surface roughness. In addition, the online coating process is adopted to produce products that can be directly used by customers at one time without secondary processing, which significantly improves production efficiency and saves customers' delivery time.

[0060] The technical contents of the present invention will be explained in detail below through Examples 1-3 and Comparative Example 1.

[0061] Example 1

[0062] The present invention provides a method for preparing a release protective film for a chip-type multilayer ceramic capacitor (MLCC). The method comprises the following steps:

[0063] 1. Raw material preparation: polyester chips grade KH2650A (80% by mass), masterbatch (20% by mass), wherein the masterbatch is prepared from 95wt% of slurry, 1.8wt% of catalyst and 3.2wt% of dispersed silica particles. The slurry composition includes 66% by mass of terephthalic acid and 34% by mass of ethylene glycol, and the catalyst is ethylene glycol antimony.

[0064] 2. Operation of auxiliary extruder: Auxiliary extruder 1 and auxiliary extruder 2 use polyester chips grade KH2650A and the above masterbatch respectively, and the raw materials are transferred to the metering pump and filtered to prepare the auxiliary extrusion melt of the upper surface layer and the lower surface layer;

[0065] 3. Operation of main extruder: The PET melt is transferred to the metering pump through a pipeline and then filtered to obtain the main extrusion melt as the core layer;

[0066] 4. Three-layer die extrusion: The filtered main extrusion melt and auxiliary extrusion melt are combined and extruded in an ABC three-layer die. The temperature of the combined extrusion is 275°C. The extruded melt passes through a cold roller and is formed into a casting sheet by electrostatic adsorption;

[0067] 5. Longitudinal stretching: The molten extruded cast sheet is stretched longitudinally into a thick film.

[0068] 6. Corona treatment: Corona treatment is performed on thick films. By applying a high-frequency, high-voltage power supply between the metal electrode and the corona treatment roller, the air is ionized and a large amount of ozone is formed, thereby activating the surface of the film and increasing the surface energy.

[0069] 7. Coating liquid application: Use a scraper to evenly apply the coating liquid (brand name: Dow Corning 7920) on the coating roller, and the coating roller transfers the coating liquid to the film surface. The specific operation is to guide the film through the expansion roller, so that its edge is pulled outward in an arched shape, and use a scraper to evenly apply the coating liquid on the coating roller, and the coating roller transfers the coating liquid to one side of the film surface.

[0070] 8. Transverse treatment: The coated film is preheated, transversely stretched, transversely shaped and transversely cooled in sequence, so that the polymer solution leaves a polymer layer on the surface of the film.

[0071] 9. Winding and slitting: Finally, the treated film is rolled and slit to obtain a standard MLCC release protective film.

[0072] The total thickness of the MLCC release protective film is 30μm, and the thickness ratio of the three layers ABC is layer A: layer B: layer C = 7:86:7.

[0073] Example 2

[0074] The present invention provides a method for preparing a release protective film for a chip-type multilayer ceramic capacitor (MLCC). The method comprises the following steps:

[0075] 1. Raw material preparation: polyester chips grade KH2650A (mass percentage 87%), masterbatch (mass percentage 13%), wherein the masterbatch is prepared from 95wt% slurry, 1.8wt% catalyst and 3.2wt% dispersed silica particles. The slurry composition includes 69wt% terephthalic acid and 31wt% ethylene glycol, and the catalyst is ethylene glycol antimony.

[0076] 2. Operation of auxiliary extruder: Auxiliary extruder 1 and auxiliary extruder 2 use polyester chips grade KH2650A and the above masterbatch respectively, and the raw materials are transferred to the metering pump and filtered to prepare the auxiliary extrusion melt of the upper surface layer and the lower surface layer;

[0077] 3. Operation of main extruder: The PET melt is transferred to the metering pump through a pipeline and then filtered to obtain the main extrusion melt as the core layer;

[0078] 4. Three-layer die extrusion: The filtered main extrusion melt and auxiliary extrusion melt are combined and extruded in the ABC three-layer die. The temperature of the combined extrusion is 280°C. The extruded melt passes through a cold roller and is formed into a casting sheet by electrostatic adsorption;

[0079] 5. Longitudinal stretching: The molten extruded cast sheet is stretched longitudinally into a thick film.

[0080] 6. Corona treatment: Corona treatment is performed on thick films. By applying a high-frequency, high-voltage power supply between the metal electrode and the corona treatment roller, the air is ionized and a large amount of ozone is formed, thereby activating the surface of the film and increasing the surface energy.

[0081] 7. Coating liquid application: Use a scraper to evenly apply the coating liquid (brand name: Dow Corning 7920) on the coating roller, and the coating roller transfers the coating liquid to the film surface. The specific operation is to guide the film through the expansion roller, so that its edge is pulled outward in an arched shape, and use a scraper to evenly apply the coating liquid on the coating roller, and the coating roller transfers the coating liquid to one side of the film surface.

[0082] 8. Transverse treatment: The coated film is preheated, transversely stretched, transversely shaped and transversely cooled in sequence, so that the polymer solution leaves a polymer layer on the surface of the film.

[0083] 9. Winding and slitting: Finally, the treated film is rolled and slit to obtain a standard MLCC release protective film.

[0084] The total thickness of the MLCC release protective film is 30μm, and the thickness ratio of the three layers ABC is layer A: layer B: layer C = 8:84:8.

[0085] Example 3

[0086] The present invention provides a method for preparing a release protective film for a chip-type multilayer ceramic capacitor (MLCC). The method comprises the following steps:

[0087] 1. Raw material preparation: polyester chips grade KH2650A (90% by mass), masterbatch (10% by mass), wherein the masterbatch is prepared from 95wt% of slurry, 1.8wt% of catalyst and 3.2wt% of dispersed silica particles. The slurry composition includes 72% by mass of terephthalic acid and 28% by mass of ethylene glycol, and the catalyst is ethylene glycol antimony.

[0088] 2. Operation of auxiliary extruder: Auxiliary extruder 1 and auxiliary extruder 2 use polyester chips grade KH2650A and the above masterbatch respectively, and the raw materials are transferred to the metering pump and filtered to prepare the auxiliary extrusion melt of the upper surface layer and the lower surface layer;

[0089] 3. Operation of main extruder: The PET melt is transferred to the metering pump through a pipeline and filtered to obtain the main extrusion melt as the core layer;

[0090] 4. Three-layer die extrusion: The filtered main extrusion melt and auxiliary extrusion melt are combined and extruded in an ABC three-layer die. The temperature of the combined extrusion is 285°C. The extruded melt passes through a cold roller and is formed into a casting sheet by electrostatic adsorption;

[0091] 5. Longitudinal stretching: The molten extruded cast sheet is stretched longitudinally into a thick film.

[0092] 6. Corona treatment: Corona treatment is performed on thick films. By applying a high-frequency, high-voltage power supply between the metal electrode and the corona treatment roller, the air is ionized and a large amount of ozone is formed, thereby activating the surface of the film and increasing the surface energy.

[0093] 7. Coating liquid application: Use a scraper to evenly apply the coating liquid (brand name: Dow Corning 7920) on the coating roller, and the coating roller transfers the coating liquid to the film surface. The specific operation is to guide the film through the expansion roller, so that its edge is pulled outward in an arched shape, and use a scraper to evenly apply the coating liquid on the coating roller, and the coating roller transfers the coating liquid to one side of the film surface.

[0094] 8. Transverse treatment: The coated film is preheated, transversely stretched, transversely shaped and transversely cooled in sequence, so that the polymer solution leaves a polymer layer on the surface of the film.

[0095] 9. Winding and slitting: Finally, the treated film is rolled and slit to obtain a standard MLCC release protective film.

[0096] The total thickness of the MLCC release protective film is 30μm, and the thickness ratio of the three layers ABC is layer A: layer B: layer C = 6:88:6.

[0097] Comparative Example 1

[0098] A method for preparing a release protective film for a chip-type multilayer ceramic capacitor (MLCC) is provided. The method comprises the following steps:

[0099] 1. Raw material preparation: polyester chips grade KH2650A (mass percentage 70%), masterbatch (mass percentage 30%), wherein the masterbatch is prepared from 95wt% slurry, 1.8wt% catalyst and 3.2wt% dispersed silica particles. The slurry composition includes 70wt% terephthalic acid and 30wt% ethylene glycol, and the catalyst is ethylene glycol antimony.

[0100] 2. Auxiliary extruder operation: Auxiliary extruder 1 and auxiliary extruder 2 use polyester chips of grade KH2650A respectively. The raw materials are transferred to the metering pump and filtered to prepare the auxiliary extrusion melt of the upper surface layer and the lower surface layer;

[0101] 3. Operation of main extruder: The PET melt is transferred to the metering pump through a pipeline and filtered to obtain the main extrusion melt as the core layer;

[0102] 4. Three-layer die extrusion: The filtered main extrusion melt and auxiliary extrusion melt are combined and extruded in an ABC three-layer die. The temperature of the combined extrusion is 285°C. The extruded melt passes through a cold roller and is formed into a casting sheet by electrostatic adsorption;

[0103] 5. Longitudinal stretching: The molten extruded cast sheet is stretched longitudinally into a thick film.

[0104] 6. Corona treatment: Corona treatment is performed on thick films. By applying a high-frequency, high-voltage power supply between the metal electrode and the corona treatment roller, the air is ionized and a large amount of ozone is formed, thereby activating the surface of the film and increasing the surface energy.

[0105] 7. Coating liquid application: Use a scraper to evenly apply the coating liquid (brand name: Dow Corning 7920) on the coating roller, and the coating roller transfers the coating liquid to the film surface. The specific operation is to guide the film through the expansion roller, so that its edge is pulled outward in an arched shape, and use a scraper to evenly apply the coating liquid on the coating roller, and the coating roller transfers the coating liquid to one side of the film surface.

[0106] 8. Transverse treatment: The coated film is preheated, transversely stretched, transversely shaped and transversely cooled in sequence, so that the polymer solution leaves a polymer layer on the surface of the film.

[0107] 9. Winding and slitting: Finally, the treated film is rolled and slid to obtain the MLCC release protective film.

[0108] The total thickness of the MLCC release protective film is 30μm, and the thickness ratio of the three layers ABC is layer A: layer B: layer C = 7:86:7.

[0109] Comparative Example 2

[0110] A method for preparing a release protective film for a chip-type multilayer ceramic capacitor (MLCC) is provided. The method comprises the following steps:

[0111] 1. Raw material preparation: polyester chips grade KH2650A (mass percentage 87%), masterbatch (mass percentage 13%), wherein the masterbatch is prepared from 95wt% slurry, 1.8wt% catalyst and 3.2wt% dispersed silica particles. The slurry composition includes 71wt% terephthalic acid and 29wt% ethylene glycol, and the catalyst is ethylene glycol antimony.

[0112] 2. Operation of auxiliary extruder: Auxiliary extruder 1 and auxiliary extruder 2 use polyester chips grade KH2650A and the above masterbatch respectively, and the raw materials are transferred to the metering pump and filtered to prepare the auxiliary extrusion melt of the upper surface layer and the lower surface layer;

[0113] 3. Operation of main extruder: The PET melt is transferred to the metering pump through a pipeline and then filtered to obtain the main extrusion melt as the core layer;

[0114] 4. Three-layer die extrusion: The filtered main extrusion melt and auxiliary extrusion melt are combined and extruded in the ABC three-layer die. The temperature of the combined extrusion is 280°C. The extruded melt passes through a cold roller and is formed into a casting sheet by electrostatic adsorption;

[0115] 5. Longitudinal stretching: The molten extruded cast sheet is stretched longitudinally into a thick film.

[0116] 6. Corona treatment: Corona treatment is performed on thick films. By applying a high-frequency, high-voltage power supply between the metal electrode and the corona treatment roller, the air is ionized and a large amount of ozone is formed, thereby activating the surface of the film and increasing the surface energy.

[0117] 7. Transverse treatment: The film after power treatment is preheated, transversely stretched, transversely shaped and transversely cooled in sequence, so that the polymer solution leaves a polymer layer on the surface of the film.

[0118] 8. Winding and slitting: Finally, the treated film is rolled and slid to obtain the MLCC release protective film.

[0119] The total thickness of the MLCC release protective film is 30μm, and the thickness ratio of the three layers ABC is layer A: layer B: layer C = 8:84:8.

[0120] Comparative Example 3

[0121] A method for preparing a release protective film for a chip-type multilayer ceramic capacitor (MLCC) is provided. The method comprises the following steps:

[0122] 1. Raw material preparation: polyester chips grade KH2650A (95% by mass), masterbatch (5% by mass), wherein the masterbatch is prepared from 95% by weight of slurry, 1.8% by weight of catalyst and 3.2% by weight of dispersed silica particles. The slurry composition includes 67% by weight of terephthalic acid and 33% by weight of ethylene glycol, and the catalyst is ethylene glycol antimony.

[0123] 2. Auxiliary extruder operation: Auxiliary extruder 1 and auxiliary extruder 2 use polyester chips grade KH2650A raw materials respectively. After the raw materials are transferred to the metering pump, they are filtered to prepare the auxiliary extrusion melts of the upper surface layer and the lower surface layer;

[0124] 3. Operation of main extruder: The PET melt is transferred to the metering pump through a pipeline and then filtered to obtain the main extrusion melt as the core layer;

[0125] 4. Three-layer die extrusion: The filtered main extrusion melt and auxiliary extrusion melt are combined and extruded in the ABC three-layer die. The temperature of the combined extrusion is 280°C. The extruded melt passes through a cold roller and is formed into a casting sheet by electrostatic adsorption;

[0126] 5. Longitudinal stretching: The molten extruded cast sheet is stretched longitudinally into a thick film.

[0127] 6. Corona treatment: Corona treatment is performed on thick films. By applying a high-frequency, high-voltage power supply between the metal electrode and the corona treatment roller, the air is ionized and a large amount of ozone is formed, thereby activating the surface of the film and increasing the surface energy.

[0128] 7. Transverse treatment: The film after power treatment is preheated, transversely stretched, transversely shaped and transversely cooled in sequence, so that the polymer solution leaves a polymer layer on the surface of the film.

[0129] 8. Winding and slitting: Finally, the treated film is rolled and slid to obtain the MLCC release protective film.

[0130] The total thickness of the MLCC release protective film is 30μm, and the thickness ratio of the three layers ABC is layer A: layer B: layer C = 6:88:6.

[0131] The above Examples 1-3 and Comparative Examples 1-3 were subjected to tensile strength tests according to ASTM D882, surface roughness measurements according to ISO 4287, and conventional release force tests according to FI NAT 10. The data after the above tests are shown in Table 1:

[0132] Table 1:

[0133]

[0134]

[0135] By comparing the data of different embodiments and comparative experiments, it can be seen that the MLCC release protective film provided by the present invention has excellent performance in tensile strength, surface roughness and release force. The performance of Examples 1 to 3 is significantly better than that of Comparative Examples 1, 2 and 3, indicating that the method of the present invention effectively improves product quality and optimizes the production process.

[0136] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an MLCC release protective film, characterized in that: The preparation method comprises the following steps: Using 80%-90% by weight of polyester chips and 10%-20% by weight of masterbatch as raw materials for auxiliary extruder 1 and auxiliary extruder 2, respectively, in the auxiliary extruder 1 and the auxiliary extruder 2, the polyester chips and the masterbatch are transferred to a metering pump and filtered to prepare auxiliary extrusion melts as the upper surface layer and the lower surface layer; The PET melt is transferred to a metering pump through a pipeline and then filtered to obtain a main extrusion melt as a core layer; The filtered main extrusion melt and auxiliary extrusion melt are combined and extruded in an ABC three-layer die head, and the extruded melt passes through a cold roller to form a casting sheet by electrostatic adsorption; The melt-extruded cast sheet is longitudinally stretched into a thick film; performing corona treatment on the thick film to activate its surface and increase its surface energy; The coating liquid is evenly spread on the coating roller by a scraper, and the coating roller transfers the coating liquid to the film surface; The coated film is sequentially preheated, transversely stretched, transversely shaped and transversely cooled, so that the polymer solution leaves a polymer layer on the film surface; Finally, the release protective film is obtained by rolling and slitting.

2. The method for preparing a MLCC release protective film according to claim 1, characterized in that: The polyester chips are graded KH2650A.

3. The method for preparing a MLCC release protective film according to claim 1, characterized in that: The masterbatch is prepared by mixing 95wt% of slurry, 1.8wt% of catalyst and 3.2wt% of dispersed silica particles, esterification reaction, prepolymerization treatment and polycondensation, wherein the slurry includes 66-73wt% of terephthalic acid and 27%-34% of ethylene glycol, and the catalyst is ethylene glycol antimony.

4. The method for preparing a MLCC release protective film according to claim 1, characterized in that: The steps of evenly applying the coating liquid on the coating roller by a scraper and transferring the coating liquid to the film surface by the coating roller include: guiding the film by an expansion roller so that its edge is pulled outward in an arch shape, and evenly applying the coating liquid on the coating roller by a scraper, and transferring the coating liquid to one side of the film surface by the coating roller.

5. The method for preparing a MLCC release protective film according to claim 4, characterized in that: The coating liquid brand is Dow Corning 7920.

6. The method for preparing a MLCC release protective film according to claim 1, characterized in that: The temperature of the combined extrusions was 275-285°C.

7. The method for preparing a MLCC release protective film according to claim 1, characterized in that: The corona treatment is performed by applying a high-frequency, high-voltage power supply between a metal electrode and a corona treatment roller to ionize the air and form a large amount of ozone, thereby activating the film surface.

8. The method for preparing a MLCC release protective film according to claim 1, characterized in that: Auxiliary extruder 1 and auxiliary extruder 2 are both twin-screw extruders.

9. An MLCC release protective film, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. The MLCC release protective film according to claim 9, characterized in that: The release protective film has an ABC three-layer structure, wherein layer A is an upper surface layer composed of polyester chips and masterbatch; layer B is a core layer composed of PET melt; layer C is a lower surface layer composed of polyester chips, masterbatch and coating liquid; wherein the thickness ratio of the three layers ABC is layer A: layer B: layer C = (5-10): (80-90): (5-8), preferably, the thickness ratio of the three layers ABC is layer A: layer B: layer C = (6-8): (83-88): (6-8).

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