A heat-resistant pet-based film for mlcc release film and a method for manufacturing the same

Abstract

The application relates to a heat-resistant PET base film for an MLCC release film and a preparation method thereof, wherein the PET base film is composed of a surface layer and a core layer through a co-extrusion process; the surface layer contains multifunctional composite fillers, the fillers take sodium-based montmorillonite as a matrix, are modified through intercalation of composite cation intercalation agents, are surface-functionalized through amino-terminated RAFT reagents, finally initiate controllable free radical polymerization of methyl methacrylate and aromatic monomers, and graft heat-resistant polymer brushes on the surfaces. Through molecular design, polymer brushes are grafted on the montmorillonite sheet, the composite functional fillers formed in this way integrate heat resistance and smoothness, improve the compatibility of montmorillonite and the PET matrix, avoid surface protrusions caused by agglomeration, make the finally-prepared PET base film have relatively low roughness and low heat shrinkage, has excellent adhesion with a silicon oil release agent, and has excellent aging resistance.

Description

Technical Field

[0001] This invention relates to the field of optical thin film technology, specifically to a heat-resistant PET base film for MLCC release film and its preparation method. Background Technology

[0002] Multilayer ceramic chip capacitors (MLCCs) are fundamental passive electronic components, belonging to the category of ceramic dielectric capacitors. They are widely used in mobile communication equipment, computer boards, home appliance remote controls, AI servers, and new energy vehicles. MLCCs have broad application prospects and huge demand. Their production process consumes a large amount of MLCC release film; the area of ​​release film used to produce a single-layer MLCC is roughly equal to the area of ​​the MLCC itself. China imports over 300,000 tons of high-end BOPET film annually. To save costs, domestic companies are continuously increasing their investment in independent research and development in related fields.

[0003] MLCC release films typically use polyethylene terephthalate (PET) film as the base material. The PET film needs to have low surface roughness, a certain degree of anti-sticking and surface smoothness, and an ultra-low heat shrinkage rate. Currently, modification of the PET base film mainly involves selecting inorganic fillers with smaller particle sizes as opening agents to reduce the surface roughness of the polyester film and improve its smoothness. However, the type of opening agent and the method of adding it have a significant impact on the surface roughness of the MLCC release film base. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention uses molecular design to prepare a composite filler that inherently possesses heat resistance enhancement and surface functionalization capabilities, and selectively introduces it into the surface layer of PET base film, effectively solving problems such as heat shrinkage, surface roughness, and release stability.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A heat-resistant PET base film for MLCC release film, wherein the PET base film is formed by co-extrusion of a surface layer and a core layer; the surface layer contains a multifunctional composite filler, and the preparation process is as follows:

[0007] S1. Disperse sodium-based montmorillonite in deionized water, add a cationic intercalating agent to carry out an intercalation reaction, and obtain organically intercalated modified montmorillonite;

[0008] S2. Disperse the organically intercalated modified montmorillonite in an organic solvent, add the amino-terminated RAFT reagent, and stir the reaction overnight at 25~40 ℃ to obtain RAFT-functionalized montmorillonite.

[0009] S3. Redisperse RAFT-functionalized montmorillonite in an organic solvent, then add methyl methacrylate, styrene, biphenyl-4-methyl methacrylate, and initiator AIBN. Heat to 70°C under nitrogen protection and react for 2-6 hours. After the reaction is complete, centrifuge, wash with anhydrous ethanol, and vacuum dry to obtain the product.

[0010] The cationic intercalating agent comprises a mixture of erucamide trimethylammonium chloride, glycidyltrimethylammonium chloride, and octadecyltrimethylammonium chloride in a mass ratio of 2-4:4-7:1;

[0011] The amino-terminated RAFT reagent has the following structural formula: .

[0012] Furthermore, the surface layer comprises optical-grade PET chips and a multifunctional composite filler comprising 2-8 wt% of the optical-grade PET chips; the core layer is a pure optical-grade PET chip layer.

[0013] Further, the specific process of step S1 is as follows: 10 parts by weight of sodium-based montmorillonite are ultrasonically dispersed in deionized water, and then stirred at high speed for 2 hours to form a stable suspension; 10 parts by weight of cationic intercalating agent are mixed and dissolved in 100 parts by weight of hot water, and slowly added dropwise to the montmorillonite suspension under stirring; the mixture is stirred at low speed overnight at 80°C, cooled to room temperature, centrifuged, washed multiple times with water and ethanol, vacuum dried, and ground to obtain organic intercalated modified montmorillonite.

[0014] Furthermore, in step S2, the mass ratio of organically intercalated modified montmorillonite to amino-terminated RAFT reagent is 5:1~2.

[0015] Further, in step S3, the molar ratio of methyl methacrylate, styrene, and biphenyl-4-methacrylate is 4~6:1~3:1~3; the mass ratio of the total monomer mass to the RAFT-functionalized montmorillonite is 5~10:1.

[0016] Furthermore, the amino-terminated RAFT reagent is obtained by amidation reaction of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid with excess ethylenediamine after acylation.

[0017] The present invention further provides a method for using a heat-resistant PET base film for MLCC release film as described above, comprising the following steps:

[0018] 1) After drying the metered PET chips and multifunctional composite filler separately, add them to the mixer and mix to obtain the surface material;

[0019] 2) Using pure PET as the core material, it is fed into the main extruder and the auxiliary extruder respectively along with the surface material. The temperature of the auxiliary extruder is adjusted to 270~290 ℃ and the temperature of the main extruder is 255~270 ℃. After melting, it is metered, extruded and filtered, and then produced as a three-layer composite casting sheet of surface layer-core layer-surface layer through a multi-layer co-extrusion process.

[0020] 3) Preheat the cast sheet at 65~85 ℃, and then stretch it longitudinally by 3.2~3.8 times at 90~120 ℃ to obtain a longitudinally stretched sheet; and then stretch it transversely by 3.5~4.2 times at 100~130 ℃; after stretching, heat set it, and then cool and traction roll it up to obtain the final product.

[0021] Furthermore, the mass ratio of the extrusion amount of the three layers (surface layer-core layer-surface layer) is 1~3:4~8:1~3.

[0022] Compared with the prior art, the present invention has the following beneficial effects: Through molecular design, the present invention first introduces epoxy groups into sodium-based montmorillonite with slip properties through an intercalation reaction, and then reacts with amino-terminated RAFT reagent to introduce active free radicals, initiating copolymerization of acrylate monomers, thereby "anchoring" the subsequently generated polymer onto the montmorillonite sheets. The resulting composite functional filler combines heat resistance and slip properties, while improving the compatibility between montmorillonite and the PET matrix, avoiding surface protrusions caused by agglomeration, so that the final PET base film has low roughness and low heat shrinkage rate, while having excellent adhesion to silicone oil release agents and excellent aging resistance. The filler is added in the form of masterbatch, which is easy to industrialize and can be widely used as a base film for MLCC release films. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] The raw materials used in this application are mostly bulk products that can be purchased on the market, such as Sinopharm Group, Aladdin, Sigma-Aldrich, etc. The PET chips selected are optical grade with an intrinsic viscosity of 0.65 dl / g and need to be dried and dehydrated before use.

[0026] Example:

[0027] A heat-resistant PET base film for MLCC release film, wherein the PET base film is formed by co-extrusion of a surface layer and a core layer; the surface layer contains a multifunctional composite filler, and the preparation process is as follows:

[0028] S1. Take 10 parts by weight of sodium-based montmorillonite (Zhejiang Fenghong, DK1) and ultrasonically disperse it in deionized water, then stir at high speed for 2 h to form a stable suspension; mix 10 parts by weight of cationic intercalating agent and dissolve it in 100 parts by weight of hot water, and slowly add it dropwise to the montmorillonite suspension under stirring, stir at low speed overnight at 80℃, cool to room temperature, centrifuge, wash with water and ethanol several times, vacuum dry, and grind to obtain organic intercalated modified montmorillonite (OMMT).

[0029] S2. Disperse 5g of OMMT in 150mL of anhydrous DMF and sonicate for 2 hours. Add 3g of amino-terminated RAFT reagent and 1mL of triethylamine. Under nitrogen protection, stir and react overnight at 40℃. After the reaction is complete, centrifuge and wash repeatedly with DMF and ethanol until the eluent is colorless. Dry under vacuum at 60℃ to obtain a light yellow powder of RAFT-functionalized montmorillonite (OMMT-RAFT).

[0030] S3. Redisperse OMMT-RAFT in anhydrous DMF, then add methyl methacrylate, styrene, biphenyl-4-methyl methacrylate, and initiator AIBN. Heat to 70°C under nitrogen protection and react for 2-6 hours. After the reaction is complete, centrifuge, wash with anhydrous ethanol, and vacuum dry to obtain the final product.

[0031] The amino-terminated RAFT reagent has the following structural formula: The preparation process is as follows: 5g of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid (CAS: 461642-78-4, purchased from Jiangsu Puleisheng Biotechnology Co., Ltd.), 10mL of thionyl chloride (SOCl2) and 2 drops of DMF were mixed and refluxed at 70℃ for 3 hours. Excess SOCl2 was evaporated to obtain trithioacryl chloride. The acryl chloride was dissolved in 50mL of anhydrous THF and slowly added dropwise to 100mL of THF solution containing excess ethylenediamine (20mL) under ice bath and stirring. After the addition was complete, the reaction was carried out at room temperature for 12 hours. The solvent was removed under reduced pressure, and the residue was dissolved in dichloromethane and washed successively with dilute hydrochloric acid, water and saturated brine. After drying with anhydrous sodium sulfate, the solvent was evaporated under reduced pressure to obtain a yellow oily substance, denoted as CTA-NH2 (yield approximately 75%).

[0032] In the above reaction, the cationic intercalating agent comprises a mixture of erucamide trimethylammonium chloride, glycidyltrimethylammonium chloride, and octadecyltrimethylammonium chloride in a mass ratio of 2-4:4-7:1; the molar ratio of methyl methacrylate, styrene, and biphenyl-4-methacrylate is 4-6:1-3:1-3; and the mass ratio of the total monomer mass to the RAFT-functionalized montmorillonite is 5-10:1. Different samples can be obtained by controlling different feed ratios. Table 1 lists the sample numbers and corresponding parameters for different feed ratios. In the table, the cationic intercalating agent is the mass ratio of erucamide trimethylammonium chloride, glycidyltrimethylammonium chloride, and octadecyltrimethylammonium chloride; n is the molar ratio of methyl methacrylate, styrene, and biphenyl-4-methacrylate; and m is the mass ratio of the total monomer mass to the RAFT-functionalized montmorillonite.

[0033] Table 1 Sample numbers and corresponding parameters under different feed ratios

[0034]

[0035] Example 1: 1) 100 parts by weight of PET chips and 5 parts by weight of multifunctional composite filler sample 1 were dried and then added to a mixer to mix and obtain the surface material;

[0036] 2) Using pure PET as the core material, it is fed into the main extruder and auxiliary extruder respectively along with the surface material. The temperature of the auxiliary extruder is adjusted to 280 ℃ and the temperature of the main extruder is 265 ℃. After melting, it is metered, extruded and filtered, and then processed through a multi-layer co-extrusion process to produce a three-layer composite casting sheet with a surface layer-core layer-surface layer. The mass ratio of the extruded amount of the three layers is 1.5:7:1.5.

[0037] 3) Preheat the cast sheet at 85 ℃, stretch it longitudinally by 3.4 times at 110 ℃ to obtain a longitudinally stretched sheet; and stretch it transversely by 3.8 times at 125 ℃; after stretching, heat set it, then cool and traction roll it up to obtain the final product.

[0038] Example 2: Basically the same as Example 1, except that the multifunctional composite filler is sample 2.

[0039] Example 3: Basically the same as Example 1, except that sample 3 is selected as the multifunctional composite filler.

[0040] Example 4: Basically the same as Example 1, except that sample 4 is selected as the multifunctional composite filler.

[0041] Example 5: Basically the same as Example 4, except that the proportion of multifunctional composite filler is 2 parts by weight.

[0042] Example 6: Basically the same as Example 4, except that the proportion of multifunctional composite filler is 8 parts by weight.

[0043] Comparative Example 1:

[0044] It is basically the same as Example 1, except that the multifunctional composite filler is selected as control sample 1.

[0045] Comparative Example 2:

[0046] It is basically the same as Example 1, except that the multifunctional composite filler is selected as control sample 2.

[0047] The performance of the PET base film prepared above was tested, and the results are recorded in Table 2.

[0048] Surface roughness Ra (nm): AFM (5μm×5μm);

[0049] Heat shrinkage rate (%): 250℃, 10 min;

[0050] Adhesion: After applying the same silicone oil release agent to the base film surface and curing, the coating adhesion was evaluated by a cross-cut adhesion test (0 is the best, 5 is the worst).

[0051] Release force: 180° peel after applying silicone oil;

[0052] Heat aging resistance: Artificial accelerated aging was carried out in hot air at 85°C for 96 hours, and the release force retention rate was tested after cooling to room temperature.

[0053] Table 2 Performance test results of PET base film

[0054]

[0055] Analysis of the data in Table 2 shows that surface roughness and thermal shrinkage vary with the selection of composite functional fillers in the system. Specifically, higher contents of erucamide trimethylammonium chloride, styrene, and biphenyl-4-methylacrylate in the samples result in lower roughness and thermal shrinkage. This application uses layered montmorillonite as the core, which is itself an excellent thermally stable reinforcing agent and slip agent. Organic modification can effectively enhance its compatibility with the PET matrix. The cationic intercalating agents selected were erucamide trimethylammonium chloride, glycidyltrimethylammonium chloride, and octadecyltrimethylammonium chloride. Erucamide trimethylammonium chloride further provided slip properties, improving the dispersion of montmorillonite in the organic phase during filler preparation. In the base film, its long alkyl segments enriched on the surface, collectively providing low surface energy and slip properties, resulting in ultra-low surface roughness. Glycidyltrimethylammonium chloride provided reaction sites, facilitating the covalent bonding of subsequent RAFT reagents, thus forming RAFT-functionalized montmorillonite. This RAFT-functionalized montmorillonite then underwent free radical polymerization with methyl methacrylate, styrene, and biphenyl-4-methacrylate to form a polymer brush. The rigid styrene structure and the biphenyl structural unit (biphenyl-4-methacrylate) significantly improved the glass transition temperature and thermal stability of the polymer brush. Synergistically with montmorillonite, a stable network structure was formed in the PET matrix, effectively improving the heat resistance of the film. This interface layer, formed by the chemically bonded polymer brushed onto the film surface, has strong adhesion to the PET matrix and provides an ideal substrate for the subsequent coating of silicone oil release agent. It exhibits good adhesion to the silicone oil release agent at level 0-1, good release force, and due to its good heat resistance and stability, the release force retention rate is still above 95% after heat aging.

[0056] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A heat-resistant PET-based film for an MLCC release film, characterized by, The PET base film is composed of a surface layer and a core layer by a co-extrusion process; the surface layer contains multifunctional composite fillers, and the preparation process is as follows: S1, take sodium-based montmorillonite and disperse it in deionized water, add cationic intercalation agent for intercalation reaction, and obtain organic intercalation modified montmorillonite; S2, disperse the organic intercalation modified montmorillonite in an organic solvent, add amino-terminated RAFT reagent, and stir at 25-40 ℃ overnight to obtain RAFT functionalized montmorillonite; S3, disperse the RAFT functionalized montmorillonite in an organic solvent, then add methyl methacrylate, styrene, 2-methyl methacrylate biphenyl-4-ester, and initiator AIBN, heat to 70 ℃ under nitrogen protection, and react for 2-6 h; after the reaction is completed, centrifugal separation, anhydrous ethanol washing, and vacuum drying are performed to obtain the product; The cationic intercalation agent includes a mixture of erucyl amide trimethyl ammonium chloride, glycidyl trimethyl ammonium chloride, and octadecyl trimethyl ammonium chloride in a mass ratio of 2-4:4-7:1; The amino-terminated RAFT reagent has the structural formula ； In step S3, the molar ratio of methyl methacrylate, styrene, and 2-methyl methacrylate biphenyl-4-ester is 4-6:1-3:1-3; and the mass ratio of the total mass of monomers to the mass of the RAFT functionalized montmorillonite is 5-10:

1.

2. The heat-resistant PET-based film for an MLCC release film according to claim 1, characterized by, The surface layer includes optical grade PET chips and multifunctional composite fillers accounting for 2-8 wt% of the optical grade PET chips; and the core layer is a pure optical grade PET chip layer.

3. The heat-resistant PET-based film for an MLCC release film according to claim 1, characterized by, The specific process of step S1 is as follows: 10 parts by weight of sodium-based montmorillonite is ultrasonically dispersed in deionized water, then high-speed stirring is performed for 2 h to form a stable suspension; 10 parts by weight of cationic intercalation agent is dissolved in 100 parts by weight of hot water, and slowly added dropwise to the montmorillonite suspension under stirring, low-speed stirring is performed at 80 ℃ overnight, the temperature is cooled to room temperature, centrifugal separation is performed, water and ethanol are washed multiple times, vacuum drying is performed, and grinding is performed to obtain the organic intercalation modified montmorillonite.

4. The heat-resistant PET-based film for an MLCC release film according to claim 1, characterized by, In step S2, the mass ratio of the organic intercalation modified montmorillonite to the amino-terminated RAFT reagent is 5:1-2.

5. The heat-resistant PET-based film for an MLCC release film according to claim 1, characterized by, The amino-terminated RAFT reagent is obtained by acyl chloride reaction of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid, and then amide reaction with excess ethylenediamine.

6. A method for producing the heat-resistant PET-based film for an MLCC release film according to any one of claims 1 to 5, characterized by, The method comprises the following steps: 1) After the metered PET chips and multifunctional composite fillers are dried, they are added to a mixer to obtain surface layer materials; 2) Pure PET is used as core layer materials, and the surface layer materials are respectively put into a main extruder and an auxiliary extruder; the temperature of the auxiliary extruder is adjusted to 270-290 ℃, and the temperature of the main extruder is adjusted to 255-270 ℃; after melting, metered extrusion and filtration are performed, and a surface layer-core layer-surface layer three-layer composite casting sheet is prepared by a multi-layer co-extrusion process; 3) The casting sheet is preheated at 65-85 ℃, longitudinally stretched 3.2-3.8 times at 90-120 ℃ to obtain a longitudinal stretched sheet; and transversely stretched 3.5-4.2 times at 100-130 ℃; after stretching, heat setting is performed, and then cooling and traction winding are performed to obtain the product.

7. The method for preparing heat-resistant PET-based film for MLCC release film according to claim 6, characterized in that, The mass ratio of the extrusion amount of the surface layer-core layer-surface layer three layers is 1-3:4-8:1-3.

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