High-temperature-resistant low-outgassing TPX release film and preparation method thereof

Abstract

This invention discloses a high-temperature resistant, low-precipitation TPX release film and its preparation method, relating to the field of electronic process protective film materials technology. The TPX release film adopts a three-layer co-extrusion structure, with the upper and lower layers being TPX release layers and the middle layer being a soft buffer layer. The raw materials consist of TPX, PP, EMMA, compatibilizers, antioxidants, etc. Its preparation method involves steps such as mixing, multi-layer co-extrusion casting, shaping, rapid cooling, and curing. The core improvement lies in significantly reducing the cooling temperature from the conventional 50-100℃ to 0-20℃, utilizing supercooling to drive crystallization / secondary crystallization, causing small molecules within the film to form large grains that are difficult to precipitate. This invention solves the industry pain point of small molecule precipitation in existing TPX films under high-temperature pressing at 180℃ / 500S, increasing the dyne value to 48 or higher, while maintaining stable performance in terms of transmittance and haze, meeting the production requirements of high-end FPC (TP board), and has broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of electronic process protective film materials technology, specifically a high-temperature resistant and low-deposition TPX release film and its preparation method. Background Technology

[0002] Flexible printed circuit boards (FPCs), also known as flexible boards, are printed circuits made of flexible insulating substrates. They offer excellent electrical performance, meet the design requirements for smaller and higher-density installations, help reduce assembly steps and enhance reliability, and can significantly reduce the size and weight of electronic products. They are of great significance in the process of developing electronic products towards high density, miniaturization, and high reliability.

[0003] In the fabrication of FPCs, to prevent metal circuits from being oxidized and corroded by air, moisture, and other substances, thus affecting their electrical performance, a protective film is usually applied to one side of the printed circuit. TPX protective film is made from poly4-methylpentene (TPX) and is completed in five steps: "raw material pretreatment → film forming → surface modification → functional coating → curing and slitting". The core is surface treatment (to improve adhesion) and functional layer coating (which determines the protection / adhesion performance). It has extremely wide applications in process protection in the electronics industry.

[0004] In existing technologies, plasticizers and other small molecule additives are added to TPX during manufacturing. After film formation, these small molecule additives remain in the film and tend to migrate to the surface. In vacuum coating processes, when the temperature exceeds a certain time (180℃ / 500S high-temperature pressing), the small molecule additives inside the TPX will migrate and precipitate to the film surface. Small molecules will precipitate to varying degrees on the film surface, appearing as a white haze to the naked eye. These small molecules will remain on the surface of the object being coated or dispersed in the process space, greatly affecting the quality of the product. Summary of the Invention

[0005] This invention provides a high-temperature resistant, low-precipitation TPX release film and its preparation method. By optimizing the cooling process and the synergistic effect of raw material formulation and structural design, the film achieves the crystallization and aggregation / secondary crystallization of small molecules, avoiding the risk of precipitation, and at the same time improving the product's dyne value and other key properties, thereby solving the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A high-temperature resistant and low-exudation TPX release film has a three-layer composite structure, including an upper surface layer, an intermediate layer, and a lower surface layer. The upper and lower surface layers are TPX release layers, both made primarily of TPX resin with added compatibilizers, antioxidants, initiators, and composite emulsifiers. The outer surface is coated with a release agent (such as silicone oil), each with a thickness of 20±8 μm. Preferably, the mass ratio of TPX resin, compatibilizer (such as maleic anhydride-grafted polypropylene or maleic anhydride-grafted ethylene-octene copolymer), antioxidant (such as hindered phenolic antioxidant 1010 or phosphite antioxidant 168), initiator (such as dicumyl peroxide or benzoyl peroxide), and composite emulsifier (such as sodium dodecylbenzenesulfonate and polyoxyethylene octylphenol ether OP-10 compounded at a mass ratio of 1-2:1) is 94:3:0.5:2:0.5.

[0007] The intermediate layer is a buffer layer composed of a blend of TPX, polypropylene, and ethylene-methyl methacrylate copolymer with a polymeric adhesive (such as polyurethane adhesive or acrylate adhesive), with a thickness of 90±10μm. Preferably, TPX accounts for 80%, polypropylene accounts for 8%, ethylene-methyl methacrylate copolymer accounts for 7%, and polymeric adhesive accounts for 5%. The surface roughness of the release film satisfies Ra≥5µm and Rz≥10µm.

[0008] Preferably, the intermediate layer material further contains 0.5-1.5 wt% of a transition metal ion compound, wherein the transition metal ion compound is one or both of zinc stearate and aluminum acetylacetonate.

[0009] Through the synergistic interaction of transition metal ion compounds with ethylene-methyl methacrylate copolymer (EMMA) and deep coupling with a low-temperature quenching process at 0-20℃, an in-situ self-assembly synergistic nucleation effect is generated. The mechanism includes: (1) Formation of dynamic coordination precursor: During the melt blending stage, transition metal ions form dynamic and reversible weak coordination bonds with the ester groups on the ethylene-methyl methacrylate copolymer chain; (2) Rapid cooling triggers dual locking: When rapidly cooled at 0-20℃, the molecular motion is rapidly frozen, and the above coordination sites become stable heterogeneous nucleation centers. At the same time, polar groups such as ester groups in ethylene-methyl methacrylate copolymer can be physically adsorbed and locked by van der Waals forces and dipole interactions to lock small molecule additives. (3) Construction of a rigid-flexible structure: The final microstructure is formed by the uniform interweaving of crystalline and flexible phases, achieving high resistance to precipitation, high surface energy and good low-temperature toughness.

[0010] The present invention also provides a method for preparing the above-mentioned high-temperature resistant and low-deposition TPX release film, comprising the following steps: S1. Layered mixing: Prepare multiple layers of materials separately, and mix each layer for 20-30 minutes to form a mixture. S2. Melt co-extrusion: The mixture of each layer is fed into the corresponding extruder and melted and plasticized at a temperature of 260℃-300℃. It is then extruded through a multi-layer co-extrusion die to form a melt sheet; preferably, the die temperature is 70℃ and the screw length-to-diameter ratio L / P is 20-30. S3. Casting: The molten sheet is cast (casting speed 4-6 m / min) onto a cooling roller; S4. Low-temperature rapid cooling: The surface temperature of the cooling roller is controlled at 0-20℃, so that the molten sheet is rapidly cooled, shaped and crystallized on the cooling roller to form a multilayer composite film; S5. Curing and Slitting: The cooled and shaped film is cured (at room temperature for 1-3 days), then slit and wound up to obtain the TPX release film.

[0011] Preferably, in step S4, the linear speed of the cooling roller is controlled at 5-15 m / min, and the cooling water circulation flow rate is not less than 5 L / min·m (per meter of roller length).

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By adopting a low-temperature rapid cooling process from 0℃ to 20℃, the TPX melt generates a huge supercooling degree when it comes into contact with the cooling roller. The mobility of molecular chains and additive molecules decreases sharply, which promotes the in-situ crystallization and aggregation of small molecule additives or induces secondary crystallization of the matrix resin, thereby "locking" them in the film body and effectively solving the problem of precipitation and contamination in subsequent high-temperature processes above 180℃. 2. After being treated with this process, the release film can have its surface tension (surface dyn value) increased from about 40 dyn / cm in traditional products to 48 dyn / cm or higher under simulated high-temperature pressing conditions, which improves its adhesion performance with cover film or other materials. 3. While achieving low precipitation and high surface energy, the key optical indicators of the release film, such as light transmittance (≥90%) and haze (≤5%), are not adversely affected, meeting the visual inspection and alignment requirements of precision electronic manufacturing processes.

[0013] 4. Raw materials are readily available, the preparation process can be improved based on existing casting equipment, production costs are controllable, and the application prospects are broad. Attached Figure Description

[0014] Fig. 1 This is a schematic diagram of the structure of a high-temperature resistant, low-deposition TPX release film provided by the present invention.

[0015] Fig. 2 The present invention provides a flowchart of a method for preparing a high-temperature resistant, low-deposition TPX release film.

[0016] Figure labeling notes: 1. Top layer; 2. Middle layer; 3. Bottom layer. Detailed Implementation

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0018] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0019] Example 1 Please see Figs. 1-2 In this embodiment of the invention, a high-temperature resistant and low-deposition TPX release film is prepared by the following steps: S1. Layered mixing: Upper layer 1 / lower layer 3 materials: Weigh 94 parts of TPX resin, 3 parts of compatibilizer, 0.5 parts of antioxidant, 2 parts of initiator, and 0.5 parts of composite emulsifier according to the mass ratio, mix for 25 minutes to form a mixture; Intermediate layer 2 material: Weigh 80 parts of TPX resin, 8 parts of polypropylene, 7 parts of ethylene-methyl methacrylate copolymer, and 5 parts of polymer adhesive according to the mass ratio, mix for 25 minutes to form a mixture.

[0020] S2. Melt co-extrusion: The mixture of each layer is fed into the corresponding extruder, melted and plasticized at a temperature of 280°C, and then extruded through a multi-layer co-extrusion die to form a melt sheet; the die temperature is 70°C and the screw length-to-diameter ratio L / P is 25.

[0021] S3. Guide the extruded molten sheet to the cooling roller at a casting speed of 5 meters per minute.

[0022] S4. Set the surface temperature of the cooling roller to 0℃, the linear speed of the cooling roller to 10m / min, and the cooling water circulation speed to 6L / min·m. The molten sheet is rapidly solidified and formed on the cooling roller.

[0023] S5. After the formed film has been cured at room temperature for 24 hours, it is cut and wound up to obtain TPX release film sample A.

[0024] Example 2 The difference from Example 1 is that in step S4, the surface temperature of the cooling roller is set to 5°C to obtain TPX release film sample B.

[0025] Example 3 The difference from Example 1 is that in step S4, the surface temperature of the cooling roller is set to 10°C to obtain TPX release film sample C.

[0026] Example 4 The difference from Example 1 is that in step S4, the surface temperature of the cooling roller is set to 15°C to obtain TPX release film sample D.

[0027] Example 5 The difference from Example 1 is that in step S4, the surface temperature of the cooling roller is set to 20°C to obtain TPX release film sample E.

[0028] Comparative Example 1 The preparation process is exactly the same as in Example 1, except that the surface temperature of the cooling roller in step S4 is changed to 30°C to obtain TPX release film sample F.

[0029] Comparative Example 2 The preparation process is exactly the same as in Example 1, except that the surface temperature of the cooling roller in step S4 is changed to 50°C to obtain TPX release film sample G.

[0030] Comparative Example 3 The preparation process is exactly the same as in Example 1, except that the surface temperature of the cooling roller in step S4 is changed to 80°C to obtain TPX release film sample H.

[0031] Performance testing High-temperature precipitation test: Place the sample on a 180°C hot plate for 500 seconds, observe the surface condition after cooling, and weigh the collected volatiles using a precision electronic balance.

[0032] Surface tension test: The surface tension of the sample after the above hot pressing treatment is measured using a dyne pen or a surface tension tester.

[0033] Optical performance testing: The haze and transmittance of the untreated samples were tested using a haze meter and a transmittance meter.

[0034] The test results are shown in Table 1 below: As shown in the table above, this invention significantly reduces the temperature of the key cooling step in the casting process from the traditional 50-100℃ to 0-20℃. It has been found that this not only effectively suppresses the precipitation of small molecules in the TPX release film at high temperatures, but also simultaneously improves its surface energy. This breaks the technical bias in the field of using higher cooling temperatures in pursuit of production efficiency, and provides a simple, efficient, and industrially suitable high-performance TPX release film solution.

[0035] Example 6 Layered mixing: Upper / lower surface materials: Same as in Example 3 (94 parts TPX resin, 3 parts MAH-g-PP compatibilizer, 0.5 parts antioxidant 1010 / 168 compound, 2 parts DCP initiator, 0.5 parts SDS / OP-10 composite emulsifier), mixed for 25 minutes; Intermediate layer material: Weigh 80 parts TPX resin, 8 parts polypropylene, 7 parts ethylene-methyl methacrylate copolymer, and 5 parts polyurethane adhesive by mass ratio, and add 1 wt% zinc stearate (based on the total mass of the intermediate layer), and mix for 25 minutes. Melt co-extrusion: Same as Example 3 (melting at 280°C, die temperature at 70°C, screw length-to-diameter ratio at 25); Casting: Same as in Example 3 (casting speed 5 m / min); Low-temperature rapid cooling: control the surface temperature of the cooling roller at 10℃, the linear speed of the cooling roller at 10m / min, and the cooling water circulation flow rate at 6L / min·m; Curing and slitting: Curing at room temperature for 24 hours, slitting and rolling to obtain sample I.

[0036] Example 7 The difference from Example 6 is that 1 wt% aluminum acetylacetonate was added to the intermediate layer material to replace zinc stearate, while the other steps were the same, resulting in sample J.

[0037] As shown in the table above, the content of precipitates decreased after the addition of transition metal ion compounds, indicating a stronger locking effect of in-situ self-assembly synergistic nucleation on small molecules; the low-temperature impact strength was improved, indicating the synergistic toughening effect of ethylene-methyl methacrylate copolymer-metal ions, solving the potential problem of low-temperature embrittlement; at the same time, the surface tension (dyne value) after pressing was further improved.

[0038] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0039] It should be understood that the disclosed apparatus can be implemented in other ways, as illustrated in the embodiments provided in this application. For example, the apparatus embodiments described above are merely illustrative; the division of units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or communication connections shown or discussed may be through some interfaces; the indirect coupling or communication connections between devices or units may be telecommunications or other forms.

[0040] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions also fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature resistant, low-deposition TPX release film, characterized in that, Includes the following steps: S1. Layered mixing: Preparing multiple layers of materials separately; S2. Melt co-extrusion: The multi-layered materials are fed into corresponding extruders for melting and plasticizing, and then the multi-layered molten materials are extruded together through a multi-layer co-extrusion die to form a melt sheet; S3. Casting: The molten sheet is cast onto a cooling roller; S4. Low-temperature rapid cooling: The surface temperature of the cooling roller is controlled to be between 0°C and 20°C, so that the molten sheet is cooled and shaped on the cooling roller to form a thin film; S5. Curing and Slitting: After cooling and setting, the film is cured and then slitted and wound up to obtain the TPX release film.

2. The method for preparing the high-temperature resistant, low-deposition TPX release film according to claim 1, characterized in that, In step S1, the multilayer material includes at least an upper surface material, an intermediate layer material, and a lower surface material to form a melt sheet with at least three layers.

3. The method for preparing the high-temperature resistant, low-deposition TPX release film according to claim 1, characterized in that, In step S2, the melting and plasticizing temperature is 260℃-300℃, the screw length-to-diameter ratio L / P of each extruder is 20-30, and the die lip temperature is 60-80℃.

4. The method for preparing the high-temperature resistant, low-deposition TPX release film according to claim 1, characterized in that, In step S3, the casting speed is 4-6 meters per minute.

5. The method for preparing the high-temperature resistant, low-deposition TPX release film according to claim 1, characterized in that, In step S4, the linear velocity of the cooling roller is controlled at 5-15 m / min, and / or the flow rate of the cooling medium used to cool the cooling roller is not less than 5 L / min·m (per meter of roller length).

6. The method for preparing the high-temperature resistant, low-deposition TPX release film according to claim 1, characterized in that, In step S5, the aging process is to age at room temperature for 1-3 days.

7. The method for preparing the high-temperature resistant, low-deposition TPX release film according to claim 2, characterized in that, Both the upper and lower surface materials include TPX resin; the intermediate layer material includes TPX resin, polypropylene, and ethylene-methyl methacrylate copolymer.

8. The method for preparing the high-temperature resistant, low-deposition TPX release film according to claim 7, characterized in that, The intermediate layer material in step S1 also contains 0.5-1.5 wt% of a transition metal ion compound, wherein the transition metal ion compound is one or two of zinc stearate and aluminum acetylacetonate.

9. A high-temperature resistant, low-exudation TPX release film, characterized in that, The material is prepared by any one of claims 1-8 and has a three-layer composite structure, including an upper surface layer, a middle layer and a lower surface layer. The upper and lower surface layers are TPX release layers, each with a thickness of 12-28 μm. The intermediate layer is a buffer layer with a thickness of 80-100μm.

10. The high-temperature resistant, low-exudation TPX release film as described in claim 9, characterized in that, The surface roughness of the release film satisfies Ra≥5µm, Rz≥10µm; The surface dyn value of the release membrane after treatment at 180°C for 500s is not less than 48 dyn / cm, and there are no visible precipitates on the surface.

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