Composite protective film resistant to high-temperature molten metal splashing and preparation method of composite protective film

Abstract

The invention discloses a composite protective film resistant to high-temperature molten metal splashing, which comprises a polymer substrate layer, one side of the polymer substrate layer is an adhesive layer, and the other side of the polymer substrate layer is a multi-layer gradient metal coating; the adhesive layer contains polyimide resin and ceramic fibers; the multi-layer gradient metal coating comprises a nickel metal adhesion layer, a chromium metal oxidation-resistant layer and a titanium metal hardening layer which are sequentially arranged from inside to outside. The thin film can effectively resist heat-force coupling impact of high-temperature molten metal liquid drops, and meanwhile, excellent adhesive force and structural integrity are kept.

Description

Technical Field

[0001] This invention relates to the field of polymer film technology, and in particular to a composite protective film resistant to high-temperature molten metal splashing and its preparation method. Background Technology

[0002] In modern industrial production, especially in fields such as automobile manufacturing, aerospace, precision instrument processing, and steel metallurgy, processes such as welding, laser cutting, and metal casting are widely used. These processes commonly involve the splashing of high-temperature molten metal droplets (such as welding slag, molten aluminum, and steel slag). Once these high-temperature splashes come into contact with equipment surfaces, precision workpieces, sensors, or heat-sensitive materials such as glass, they can easily cause permanent damage, such as ablation, pitting, adhesion, or performance failure, leading to decreased product yield and increased production costs.

[0003] Currently, the main solutions available on the market for this type of protection include: Traditional physical covering methods include using asbestos cloth, fire blankets, or metal plates. These methods are cumbersome, inconvenient to operate, difficult to adapt to the protection of complex curved surfaces or precision areas, and may cause secondary pollution due to fiber shedding.

[0004] Ordinary polymer protective films: such as protective films based on polyethylene (PE) or polypropylene (PP). These materials have extremely poor temperature resistance, and usually soften and deform below 100°C. They are completely unable to withstand the impact of metal droplets at hundreds or even thousands of degrees Celsius, and will be melted through instantly, losing their protective effect.

[0005] Existing pressure-sensitive tapes, such as acrylic or rubber tapes, are convenient to use, but the upper limit of the temperature resistance of their adhesives is usually no more than 150°C. Under the impact of high-temperature splashes, the adhesive layer will rapidly degrade and carbonize, lose its adhesion, cause the protective film to fall off, and even leave adhesive residues that are difficult to remove on the protected surface.

[0006] Single-metal coated thin films: Some technical solutions attempt to deposit a single layer of metal (such as aluminum or nickel) on plastic films to improve heat resistance. However, these films generally suffer from the following defects: poor interfacial adhesion between the metal coating and the polymer base film, making them prone to delamination and peeling under thermal shock; the single metal coating itself is relatively brittle, with insufficient impact and puncture resistance; and the metal layer is easily oxidized and fails in high-temperature oxidizing atmospheres.

[0007] Therefore, there is an urgent need in this field for a flexible protective film technology that possesses excellent high-temperature resistance and resistance to molten metal impact, as well as good flexibility and adhesion, can be easily applied to various complex surfaces, and can be cleanly removed after use. Summary of the Invention

[0008] Purpose of the invention: In order to overcome the shortcomings of the prior art, the first objective of this invention is to provide a composite protective film that is resistant to high-temperature molten metal splashes. The film of this invention can effectively resist the thermal-mechanical coupling impact of high-temperature molten metal droplets, while maintaining excellent adhesion and structural integrity. The second objective is to provide a method for preparing the aforementioned composite protective film.

[0009] Technical solution: The composite protective film for high-temperature molten metal splash resistance of the present invention comprises: A polymer substrate layer, wherein one side of the polymer substrate layer is an adhesive layer and the other side is a multilayer gradient metal plating layer; The adhesive layer contains polyimide resin and ceramic fibers; The multi-layer gradient metal coating comprises, from the inside out, a nickel metal adhesion layer, a chromium metal oxidation-resistant layer, and a titanium metal hardening layer. The nickel metal adhesion layer serves as the bottom layer, enhancing the adhesion between the entire metal coating and the polymer substrate. The chromium metal oxidation-resistant layer serves as the intermediate layer, forming a dense oxide passivation layer at high temperatures to resist oxidation and ablation. The titanium metal hardening layer serves as the top layer, formed through ion implantation, to improve surface hardness and resist physical penetration by molten metal droplets.

[0010] Furthermore, the polymer substrate layer is a PET film.

[0011] Furthermore, the adhesive layer contains the following raw materials in parts by weight: Polyimide resin: 50-70 parts; Organosilicon micro powder: 15-25 parts; Ceramic fiber: 10-20 parts; Coupling agent: 2-8 parts.

[0012] Furthermore, the ceramic fiber is alumina fiber or aramid fiber.

[0013] Furthermore, the adhesive layer also contains 5 parts by weight of self-healing microcapsules; the capsule wall of the self-healing microcapsule is made of silica material, and the capsule core contains epoxy resin repair agent.

[0014] Furthermore, the outer surface of the titanium metal hardened layer in the multilayer gradient metal coating is coated with an intumescent fire-retardant coating.

[0015] Furthermore, the thickness of the nickel metal adhesion layer is 5-10 μm.

[0016] Furthermore, the thickness of the chromium metal oxidation-resistant layer is 3-5 μm.

[0017] Furthermore, the thickness of the titanium metal hardened layer is 0.5-1 μm.

[0018] The preparation method of the above-mentioned high-temperature resistant composite protective film against molten metal splashes includes the following steps: S1. Corona treatment is applied to the surface of the polymer substrate to be coated to increase surface tension; S2. A nickel metal adhesion layer is formed by chemical deposition on the surface of a corona-treated polymer substrate; a chromium metal oxidation-resistant layer is formed on the surface of the nickel metal adhesion layer by magnetron sputtering; and titanium ions are implanted into the surface of the chromium metal oxidation-resistant layer to form a titanium metal hardened layer. S3. Coat the other surface of the polymer substrate with a coupling agent solution; apply the polyimide-based high-temperature resistant adhesive by blade coating, and perform heat treatment in two stages: pre-curing and post-curing, to finally form the adhesive layer.

[0019] Beneficial effects: Compared with the prior art, the significant advantages of this invention are: 1. High-temperature impact resistance: Through the Ni / Cr / Ti gradient metal coating design, the surface layer has high hardness and is puncture resistant, the middle layer is resistant to high-temperature oxidation, and the bottom layer ensures adhesion, forming a synergistic protective effect. It can withstand the impact of molten metal droplets at temperatures up to 1500℃ without penetration.

[0020] 2. Interfacial bonding stability: Using electroless nickel plating as the bottom layer and combining it with corona pretreatment of the base film significantly improves the adhesion between the metal layer and the flexible base film, effectively avoiding delamination failure under thermal shock and mechanical stress.

[0021] 3. High-temperature bonding capability: The innovative polyimide-based composite adhesive breaks through the temperature resistance limit of traditional pressure-sensitive adhesives. It can maintain stable shear strength (≥12MPa) at instantaneous high temperatures of up to 350℃, ensuring that the protective film does not shift or fall off under harsh working conditions.

[0022] 4. Process combination and cost-effectiveness: The composite coating process of "wet (chemical plating) + dry (sputtering / implantation)" effectively reduces production costs while ensuring coating density, compared with the pure physical vapor deposition (PVD) process, and has greater industrialization potential.

[0023] 5. Functional Integration Potential: The structure of this invention provides a platform for further integration of advanced functions such as flame retardancy and self-healing. For example, self-healing microcapsules can be introduced into the adhesive, or an intumescent fire-retardant coating can be laminated onto the metal layer, thereby greatly expanding the application scenarios and service life of the product. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Example 1: Preparation of a composite protective film resistant to high-temperature molten metal splashes Substrate pretreatment: A 50 μm thick polyethylene terephthalate (PET) film was selected as the polymer substrate layer 1. Its first surface (i.e. the surface to be coated) was placed under a corona treatment machine with a power of 5 kW and a processing speed of 5 m / min for treatment. After treatment, its surface tension increased from 40 mN / m to 55 mN / m.

[0027] Preparation of multilayer gradient metal coating 3: carried out on the pretreated first surface.

[0028] Electroless nickel plating: The pretreated PET film is immersed in an electroless nickel plating solution with a pH of 4.5 and a temperature of 85 degrees Celsius, and reacted for 30 minutes to form a nickel metal adhesion layer 301 with a thickness of 8 μm. Testing showed that the adhesion between this nickel layer and the PET substrate reached 5.2 N / cm (ASTM D3359 standard).

[0029] Magnetron sputtering chromium plating: The nickel-plated film is fed into a magnetron sputtering device, and chromium target sputtering is performed under the conditions of argon (Ar) flow rate of 50 sccm and sputtering power of 3kW to deposit a chromium metal oxide-resistant layer 302 with a thickness of 4μm.

[0030] Titanium ion implantation: The above-mentioned thin film was placed in an ion implanter, using an energy of 100 keV and an implantation dose of 1*10. 17 ions / cm 2 Titanium ion implantation was performed using the parameters to form a titanium metal hardened layer 303 with a depth of about 0.8 μm on the chromium layer surface, and its surface hardness reached HV2000.

[0031] Preparation and coating of adhesive layer 2: Adhesive preparation: Mix 60 parts by weight of polyimide resin, 20 parts by weight of organosilicon micro powder (average particle size 5μm), 15 parts by weight of alumina ceramic fiber (average diameter 3μm, aspect ratio 20:1) and 5 parts by weight of KH-560 silane coupling agent in a high-speed disperser to obtain a high-temperature resistant adhesive.

[0032] Coating and Curing: A 2% KH-560 silane coupling agent solution is first uniformly coated as a primer onto the second surface of the polymer substrate 1 (i.e., the surface opposite to where the metal coating forms). Then, the prepared adhesive is uniformly coated using a doctor blade coating method, controlling the wet film thickness to 50 μm. The coated film is then placed in an oven for pre-curing at 150°C for 10 minutes, followed by post-curing at 300°C for 2 hours. After cooling, the finished product is obtained.

[0033] Performance Testing: The protective film prepared in this embodiment was adhered to a glass plate. Molten aluminum droplets (approximately 3 mm in diameter) at 1500°C were dropped onto the film surface. It was observed that the aluminum rapidly solidified into a spherical shape on the film surface, without penetrating the film, and the glass plate underneath remained intact. After removing the film, no adhesive residue remained on the glass plate surface.

[0034] Example 2: Range Lower Limit Verification The preparation process in this embodiment is basically the same as that in Example 1, except that: The control parameters for the thickness of each layer of the multilayer gradient metal coating were adjusted: Electroless nickel plating: Adjust the reaction time to form a nickel metal coating with a thickness of 5μm.

[0035] Magnetron sputtering chromium plating: By adjusting the sputtering time, a 3μm thick chromium metal oxide-resistant layer is deposited.

[0036] Ion implantation of titanium: By adjusting the implantation dose, a titanium metal hardened layer with a depth of about 0.5 μm is formed on the surface of the chromium layer.

[0037] Adhesive preparation: Mix 50 parts by weight of polyimide resin, 15 parts by weight of organosilicon micro powder (average particle size 5μm), 10 parts by weight of alumina ceramic fiber (average diameter 3μm, aspect ratio 20:1) and 2 parts by weight of KH-560 silane coupling agent in a high-speed disperser to obtain a high-temperature resistant adhesive.

[0038] Performance testing: The protective film prepared in this embodiment was subjected to the same performance tests as in Example 1. The results showed that the film could also withstand the impact of molten aluminum droplets at 1500°C without being penetrated, proving that the present invention can still achieve the expected technical effect at the lower limit of the required protection thickness range.

[0039] Example 3: Range Upper Limit Verification The preparation process in this embodiment is basically the same as that in Example 1, except that: The control parameters for the thickness of each layer in the multilayer gradient metal coating were adjusted: Electroless nickel plating: Adjust the reaction time to form a nickel metal coating with a thickness of 10μm.

[0040] Magnetron sputtering chromium plating: By adjusting the sputtering time, a chromium metal oxide-resistant layer with a thickness of 5μm is deposited.

[0041] Ion implantation of titanium: By adjusting the implantation dose, a titanium metal hardened layer with a depth of about 1.0 μm is formed on the surface of the chromium layer.

[0042] Adhesive formulation: Mix 70 parts by weight of polyimide resin, 25 parts by weight of organosilicon micro powder (average particle size 5μm), 20 parts by weight of alumina ceramic fiber (average diameter 3μm, aspect ratio 20:1) and 8 parts by weight of KH-560 silane coupling agent in a high-speed disperser to obtain a high-temperature resistant adhesive.

[0043] Performance testing: The protective film prepared in this embodiment was subjected to the same performance tests as in Example 1. The results showed that the film could also withstand the impact of molten aluminum droplets at 1500°C without being penetrated, proving that the present invention can still achieve the expected technical effect at the upper limit of the required protection thickness range.

[0044] Example 4: This example improves upon Example 1 by adding a self-healing function to the adhesive layer. Five parts (by weight) of self-healing microcapsules are added to the adhesive formulation of Example 1. The microcapsule walls are made of high-temperature resistant silica, and the core contains an epoxy resin repair agent. A curing agent is pre-dispersed in the adhesive components. The remaining preparation steps are identical to those in Example 1.

[0045] Meanwhile, in this embodiment, the ceramic fiber is aramid fiber.

[0046] Example 5: This example adds a flame-retardant composite coating layer to Example 1. A 200 μm thick intumescent fire-retardant coating is applied to the outer surface of the multilayer gradient metal coating prepared in Example 1 (i.e., the surface of the titanium metal hardened layer). The remaining preparation steps are exactly the same as in Example 1.

Claims

1. A composite protective film resistant to high-temperature molten metal splashes, characterized in that, include: A polymer substrate (1) has an adhesive layer (2) on one side and a multilayer gradient metal plating layer (3) on the other side. The adhesive layer (2) contains polyimide resin and ceramic fibers; The multilayer gradient metal coating (3) includes a nickel metal adhesion layer (301), a chromium metal oxidation-resistant layer (302), and a titanium metal hardening layer (303) arranged sequentially from the inside to the outside.

2. The composite protective film resistant to high-temperature molten metal splashes according to claim 1, characterized in that: The polymer substrate layer (1) is a PET film.

3. The composite protective film resistant to high-temperature molten metal splashes according to claim 1, characterized in that, The adhesive layer (2) contains the following raw materials in parts by weight: Polyimide resin: 50-70 parts; Organosilicon micro powder: 15-25 parts; Ceramic fiber: 10-20 parts; Coupling agent: 2-8 parts.

4. The composite protective film resistant to high-temperature molten metal splashes according to claim 3, characterized in that: The ceramic fiber is either alumina fiber or aramid fiber.

5. The composite protective film resistant to high-temperature molten metal splashes according to claim 3, characterized in that, The adhesive layer (2) also contains 5 parts by weight of self-healing microcapsules; the capsule wall of the self-healing microcapsule is made of silica material, and the capsule core contains epoxy resin repair agent.

6. The composite protective film resistant to high-temperature molten metal splashes according to claim 1, characterized in that: The outer surface of the titanium metal hardened layer (303) in the multilayer gradient metal coating (3) is coated with an intumescent fireproof coating.

7. The composite protective film resistant to high-temperature molten metal splashes according to claim 1, characterized in that: The thickness of the nickel metal adhesion layer is 5-10 μm.

8. The composite protective film resistant to high-temperature molten metal splashes according to claim 1, characterized in that: The thickness of the chromium metal oxidation-resistant layer is 3-5 μm.

9. The composite protective film resistant to high-temperature molten metal splashes according to claim 1, characterized in that: The thickness of the titanium metal hardened layer is 0.5-1 μm.

10. The method for preparing the high-temperature resistant composite protective film against molten metal splashes as described in claim 1, characterized in that, Includes the following steps: S1. Corona treatment is applied to the surface of the polymer substrate to be coated to increase surface tension; S2. A nickel metal adhesion layer is formed by chemical deposition on the surface of a corona-treated polymer substrate; a chromium metal oxidation-resistant layer is formed on the surface of the nickel metal adhesion layer by magnetron sputtering; and titanium ions are implanted into the surface of the chromium metal oxidation-resistant layer to form a titanium metal hardened layer. S3. Coat the other surface of the polymer substrate with a coupling agent solution; apply the polyimide-based high-temperature resistant adhesive by blade coating, and perform heat treatment in two stages: pre-curing and post-curing, to finally form the adhesive layer.

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