Composite lining material for ultra-clean container, preparation method of composite lining material and ultra-clean container

Abstract

The invention relates to a composite lining material for an ultra-clean container, a preparation method of the composite lining material and the ultra-clean container, and relates to the technical field of ultra-clean containers. The composite lining material sequentially comprises a nanotube enhancement layer and a buffer layer from outside to inside, and can also comprise a conductive barrier layer and a hydrophobic layer. The nanotube reinforcing layer takes vinyl modified perfluoroalkoxy resin containing 2% of vinyl side chains as a matrix and hydroxylated boron nitride nanotubes as a reinforcing phase, and a repairing agent is packaged in the nanotubes; the buffer layer is composed of specific fiber bundles, ionomers and the like, and the concentration of the fluorine element changes in a gradient mode. The preparation method comprises the steps of resin preparation, nanotube treatment, construction of each layer and the like. The composite lining material has excellent mechanical property, corrosion resistance, self-repairability, conductive barrier property and super-hydrophobic property, and can meet strict requirements of ultra-clean containers on storage and transportation of wet electronic chemicals.

Description

Technical Field

[0001] This invention relates to the field of cleanroom container technology, specifically to a composite liner material for cleanroom containers and its preparation method, as well as a cleanroom container containing the composite liner material. Background Technology

[0002] Ultra-clean containers are ultra-clean, high-purity reagent packaging containers specifically designed for the safe storage and transportation of wet electronic chemicals used in nanoscale integrated circuit manufacturing. They must meet the purity standards set by the Semiconductor Equipment and Materials International (SEMI) for wet electronic chemicals, reaching G4 or even G5 levels. SEMI G5-level semiconductor-specific ultra-clean containers represent the highest technical standard in the field of wet electronic chemical storage and transportation.

[0003] The ultra-clean container is made of specially treated high-density polyethylene (HDPE) material. Through a nanoscale purification process, the metal impurity content of the material is controlled to below 0.01 ppb, and the inner wall surface roughness reaches the sub-micron level, ensuring that secondary contamination is not introduced when storing corrosive chemicals such as hydrofluoric acid and developer. Its sealing system integrates a multi-layered protective design, including fluororubber sealing rings and an inert gas protection device, maintaining an ISO Class 1 clean environment and effectively blocking the penetration of airborne particles ≥0.1μm. In terms of structural design, the container employs a hydrodynamically optimized inclined inner wall and a bottom anti-vortex device, reducing chemical residue to below 0.1%.

[0004] However, existing clean containers still have many shortcomings that urgently need to be addressed.

[0005] On the one hand, HDPE material itself has limited mechanical strength. During the storage and transportation of wet electronic chemicals, if it encounters accidental collisions or compression, the lining of the cleanroom container is prone to cracking or deformation. This not only affects the normal use of the cleanroom container, but may even lead to chemical leakage and cause safety accidents.

[0006] On the other hand, with the development of integrated circuit manufacturing technology, the corrosiveness of the wet electronic chemicals used is becoming increasingly stronger. For some strong acids, strong alkalis, or strong oxidizing chemicals, HDPE linings will corrode and age after long-term contact, resulting in a decrease in the barrier performance of the container.

[0007] Thirdly, during the daily use of cleanroom containers, the lining will inevitably develop micro-cracks due to various factors. Since HDPE material itself does not have self-healing capabilities, these micro-cracks will gradually expand over time, eventually potentially leading to the overall failure of the container.

[0008] Fourthly, the flow and friction of wet electronic chemicals within containers easily generate static electricity, and the insulating properties of HDPE material make it difficult for this static electricity to dissipate. Static electricity can attract dust, particulate matter, and other impurities from the surrounding environment, contaminating the wet electronic chemicals and affecting their purity. Summary of the Invention

[0009] This invention aims to address the problem of insufficient overall material performance in existing cleanroom containers when facing extreme chemical storage. Specifically, it includes improving the mechanical properties, corrosion resistance, self-healing properties, electrical conductivity, and superhydrophobic properties of the materials to meet the higher performance requirements of cleanroom containers for the safe storage and transportation of wet electronic chemicals in nanoscale integrated circuit manufacturing.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0011] A composite liner material for a cleanroom container, characterized in that it comprises, from the outside to the inside, a nanotube reinforcement layer and a buffer layer; the matrix of the nanotube reinforcement layer is a vinyl-modified perfluoroalkoxy resin containing 2% vinyl side chains, and the reinforcement phase is hydroxylated boron nitride nanotubes with a diameter of 25 to 50 nanometers. The surface of the hydroxylated boron nitride nanotubes is covalently grafted with γ-methacryloyloxypropyltrimethoxysilane to form a silicon-oxygen-boron interface, and carbon-carbon crosslinking with the resin matrix is ​​initiated by ultraviolet light; the nanotubes are arranged parallel along the axial direction, and the lumen encapsulates a volumetric loading capacity of 10 The buffer layer contains 1% to 20% perfluoropolyether diglycidyl ether repair agent, and the tube ends are cured by ultraviolet light to form sealed microcapsules with a diameter of 10 to 100 nanometers; the rigid skeleton of the buffer layer is composed of axially arranged polyether ether ketone fiber bundles with a diameter of 100 to 300 nanometers and a sulfonation degree of 50% to 75%, accounting for 50% to 70% by weight; perfluorosulfonic acid ionomer equivalent of 600 to 800 is impregnated into the fiber gaps, and 2.5% to 7% zinc trifluoromethanesulfonate crosslinking agent is added to form an ionic bond network; the fluorine concentration in the buffer layer increases continuously from the outside to the inside, ranging from 40% to 75%.

[0012] In a preferred embodiment of the present invention, the composite lining material further includes a conductive barrier layer; the conductive barrier layer is closely attached to the buffer layer and has a thickness of 0.1 to 0.8 mm. The conductive barrier layer is based on zinc perfluorosulfonate resin with a zinc ion exchange rate of over 98% and contains 1% to 3% by weight of multi-walled carbon nanotubes with a diameter of 5 to 10 nanometers.

[0013] In a preferred embodiment of the present invention, the composite lining material further includes a hydrophobic layer; the hydrophobic layer is located inside the conductive barrier layer, has a thickness of 30 to 50 micrometers, uses fluorinated ethylene propylene copolymer as the substrate, and has a regular array of pits on its surface, the pits having a diameter of 3 to 8 micrometers, a depth of 0.5 to 0.9 micrometers, and an aspect ratio of 0.16.

[0014] In a preferred embodiment of the present invention, the thickness of the nanotube reinforcing layer is 1 to 3 millimeters; the hydroxylated boron nitride nanotubes are obtained by purifying and oxidizing the original boron nitride nanotubes with hydrochloric acid and nitric acid solutions.

[0015] A method for preparing a composite liner material for cleanroom containers, characterized by comprising the following steps:

[0016] Preparation of vinyl-modified perfluoroalkoxy resin containing 2% vinyl side chains: Tetrafluoroethylene, perfluoropropyl vinyl ether and trifluorovinyl ether monomers with a purity exceeding 99.5% were ultrasonically pre-emulsified in liquid CO2 medium at a molar ratio of 92.7:5.3:2.0. Ammonium perfluorooctanoate was added to stabilize the dispersion system. The mixture was heated to 75℃ in a high-pressure reactor, and the pressure was maintained at 4.5MPa±0.2MPa. Gradient copolymerization was initiated with ammonium persulfate aqueous solution. The heating rate was controlled to be ≤1℃ / min and the stirring rate to be 500rpm. After the polymerization was terminated, supercritical CO2 purification technology was used to continuously purify the mixture at 50℃ and 15MPa with CO2 flowing at a rate of 10L / min for 3 hours to obtain a white powder.

[0017] Preparation of covalently bridged nanotubes: h-BNNTs vertical arrays were grown on a Ni111 crystal-oriented nickel foil substrate by low-pressure chemical vapor deposition, immersed in an alkaline oxidation solution for reaction, and then dispersed in anhydrous ethanol with 5 wt% γ-methacryloyloxypropyltrimethoxysilane. The reaction was carried out under nitrogen protection by reflux, and finally perfluoropolyether diglycidyl ether was infused under vacuum and UV pre-cured.

[0018] Preparation of buffer layer: Sulfonated polyether ether ketone powder with 65% sulfonation degree is dissolved in N,N-dimethylformamide, mixed with perfluorosulfonic acid resin at a mass ratio of 60:35, and 5wt% zinc trifluoromethanesulfonate crosslinking agent is added to form a spinning solution. The solution is then electrospun, sprayed, and hot-pressed to form an interpenetrating network.

[0019] In a preferred embodiment of the present invention, the following steps are also included:

[0020] Preparation of conductive insulating layer: Multi-walled carbon nanotubes are activated by argon plasma, dispersed in ethanol to form a suspension, mixed with perfluorosulfonic acid resin solution to prepare conductive slurry, sprayed and cured by step heating and cold pressing.

[0021] In a preferred embodiment of the present invention, the following steps are also included:

[0022] Preparation of hydrophobic layer: A silica nanosphere ethanol dispersion was spin-coated onto the surface of the conductive layer and annealed to form a template. Fluorinated ethylene propylene copolymer and perfluorooctyltriethoxysilane were mixed and melt-coated onto the template surface. The superhydrophobic layer was formed by vacuum hot pressing, template dissolution and plasma treatment.

[0023] In a preferred embodiment of the present invention, in step (2), the reflux reaction conditions are 82℃±2℃ and the reaction time is 6 hours.

[0024] In a preferred embodiment of the present invention, in step (3), the conditions for electrospinning are a 20kV high-voltage electric field and a 30% humidity environment, and the conditions for hot-pressing penetration are 155℃ and 0.3MPa.

[0025] The present invention also provides an ultra-clean container, comprising an outer shell and an inner liner, wherein the inner liner is made of the aforementioned composite liner material, and the nanotube reinforcement layer of the liner material is bonded to the inner wall of the outer shell.

[0026] This invention exhibits significant technical advantages. In terms of mechanical properties, thanks to its unique structure, the material achieves an average tensile strength of 85 MPa, an average flexural strength of 120 MPa, and an interfacial peel strength of 210 joules / m², combining high strength with high toughness. Regarding corrosion resistance, the mass loss in 98% concentrated sulfuric acid (180℃) after 5000 hours is only 0.12 mg / cm², and the surface etching rate in 49% hydrofluoric acid solution at 85℃ remains stable at 0.018 μm / day. It demonstrates highly efficient self-healing capabilities, achieving a 92% microcrack healing rate within 30 minutes at 150℃. Furthermore, it exhibits excellent electrical conductivity, with a surface resistivity of <10 Ω·cm. 6 With a strength of Ω / sq, it can conduct static electricity and adsorb heavy metal ions. It exhibits excellent superhydrophobic properties, with a hydrophobic layer contact angle exceeding 160° and a roll-off angle less than 5°, achieving zero chemical residue. Furthermore, it demonstrates excellent stability, maintaining good performance even after wiping with alcohol or immersion in hydrofluoric acid, fully meeting the stringent requirements of clean containers for the storage and transportation of wet electronic chemicals. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the composite lining material of the present invention.

[0028] Figure 2 This is a flowchart of the preparation method of the composite lining material of the present invention.

[0029] Figure 3 This is a schematic diagram of the modified PFA-MF molecular structure of the present invention.

[0030] Figure 4 This is a schematic diagram illustrating the vinyl group linkage in the modified perfluoroalkoxy resin, which is a simple linear structure of the present invention.

[0031] Figure 5 This is a schematic diagram showing the tensile strength test results of the composite lining material of the present invention.

[0032] Figure 6 This is a schematic diagram showing the bending strength test results of the composite lining material of the present invention.

[0033] Figure 7 This is a schematic diagram illustrating the change in mass loss of the composite lining material over time under concentrated sulfuric acid immersion according to the present invention.

[0034] Figure 8 This is a schematic diagram showing the change of the surface etching rate of the composite lining material under hydrofluoric acid immersion over time according to the present invention.

[0035] Figure 9 This is a schematic diagram showing the change in the microcrack healing rate of the composite lining material at 150℃ over time according to the present invention.

[0036] Figure 10 This is a schematic diagram showing the surface resistance measurement results of the conductive layer of the composite lining material of the present invention.

[0037] Figure 11 This is a schematic diagram showing the measurement results of the contact angle of the hydrophobic layer of the composite lining material of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0040] The first embodiment of the present invention provides a composite liner material for cleanroom containers. For example... Figure 1 As shown, the composite lining material consists of a nanotube reinforcement layer and a buffer layer from the outside to the inside. A conductive barrier layer and a hydrophobic layer can also be added as needed.

[0041] As a preferred embodiment, the nanotube reinforcing layer is the main body of the outer layer, with a thickness of 1 to 3 mm. The matrix of the nanotube reinforcing layer is a vinyl-modified perfluoroalkoxy resin containing 2% vinyl side chains, and the reinforcing phase is hydroxylated boron nitride nanotubes with a diameter of 25 to 50 nm (hydroxylated boron nitride nanotubes are existing technology; hydroxylation modification of boron nitride nanotubes can be achieved through acid treatment. The original BNNTs (boron nitride nanotubes) were purified and oxidized using hydrochloric acid and nitric acid solutions, successfully introducing hydroxyl groups (—OH) at the boron sites to obtain BNNTs-OH with good water dispersibility). The surface of the nanotubes is covalently grafted with γ-methacryloyloxypropyltrimethoxysilane (i.e., KH-570) to form a silicon-oxygen-boron (Si-OB) interface, which is then cross-linked with the resin matrix by ultraviolet light initiation.

[0042] From a microscopic perspective, the nanotubes are arranged parallel to each other along the axial direction, and the cavity of each tube is encapsulated with a perfluoropolyether diglycidyl ether repair agent with a volumetric loading of 15%. The ends of the tubes are cured under ultraviolet light to form sealed microcapsules with a diameter of 10 to 100 nanometers.

[0043] The buffer layer, located inside the nanotube reinforcement layer, has a thickness of 100 to 500 nanometers. The rigid framework of this buffer layer consists of axially arranged polyetheretherketone (PEEK) fiber bundles with a diameter of 100 to 300 nanometers and a sulfonation degree of 50% to 75%, accounting for 50% to 70% by weight. An equivalent of 600 to 800 ppm of perfluorosulfonic acid ionomer is impregnated into the fiber interstices, while 2.5% to 7% of zinc trifluoromethanesulfonate crosslinking agent is added to form an ionic bond network. In this layer, the fluorine concentration continuously increases from the outside to the inside, ranging from 40% to 75%, exhibiting a gradient characteristic, effectively buffering thermal expansion stress. The interfacial peel strength has been measured to reach 210 joules per square meter.

[0044] The conductive barrier layer is tightly attached to the buffer layer and has a thickness of 0.1 to 0.8 mm. It uses zinc perfluorosulfonate resin with a zinc ion exchange rate exceeding 98% as a matrix, and incorporates 1% to 3% by weight of multi-walled carbon nanotubes with a diameter of 5 to 10 nanometers, thus forming a three-dimensional conductive network. This network provides both electrostatic shielding and the ability to capture copper and iron ions through the zinc sulfonate groups, thereby adsorbing heavy metal ions. Scanning electron microscopy shows that the spacing between the carbon nanotube overlap points does not exceed 50 nanometers, the zinc element is uniformly distributed, and the surface scanning coefficient of variation is less than 5%.

[0045] A hydrophobic layer serves as the inner surface, with a thickness of 30 to 50 micrometers. A fluorinated ethylene propylene copolymer is used as the substrate, and its surface features a regular array of pits, 3 to 8 micrometers in diameter, 0.5 to 0.9 micrometers in depth, and an aspect ratio of 0.16. This structure is formed by imprinting with an 8 to 12 nanometer silica template, enabling a contact angle exceeding 160° and a roll-off angle less than 5°, thus achieving zero residue of ultrapure chemicals. White light interferometry measurements show a pit density of 25,000 pits per square millimeter and a surface roughness of 0.7 micrometers.

[0046] In the above structure, the nanotube reinforcement layer and the buffer layer are combined through two mechanisms: molecular chain interdiffusion and zinc ion anchoring; the buffer layer and the conductive barrier layer are mechanically interlocked by the embedding of polyether ether ketone fibers into conductive resin; and the conductive barrier layer and the inner surface layer are physically bonded by melt penetration into micropores.

[0047] When extreme chemicals come into contact with the inner surface layer, the superhydrophobic pit array first repels liquid wetting; penetrating molecules are adsorbed and shielded by the conductive barrier layer; residual corrosive media are buffered and dispersed in the buffer layer; and finally, the outer main barrier layer blocks the liquid and seals microcracks through a self-healing mechanism. The axially oriented alignment of the nanotube reinforcement layer (induced by a 0.5 Tesla magnetic field) optimizes stress distribution, and coupled with the gradient transition design, this material exhibits a mass loss of only 0.12 mg / cm² even after 5000 hours of exposure to 98% concentrated sulfuric acid (180°C).

[0048] In another embodiment of the present invention, a method for preparing the above-mentioned composite liner material for cleanroom containers is provided. For example... Figure 2 As shown, the method includes the following steps:

[0049] I. Preparation of vinyl-modified perfluoroalkoxy resin containing 2% vinyl side chains.

[0050] The most preferred preparation method of this invention is:

[0051] First, tetrafluoroethylene (TFE), perfluoropropyl vinyl ether (PPVE), and trifluorovinyl ether (TFVE) monomers with a purity exceeding 99.5% are ultrasonically pre-emulsified in a liquid CO2 medium at a preset molar ratio (optimal 92.7:5.3:2.0). Then, a trace amount of ammonium perfluorooctanoate is added to stabilize the dispersion system.

[0052] Subsequently, the temperature was raised to 75°C in a high-pressure reactor, and the pressure was maintained at 4.5MPa±0.2MPa. Gradient copolymerization was initiated using ammonium persulfate aqueous solution. During this process, the temperature was increased at a rate of ≤1°C / min and the stirring was controlled at a medium speed of 500rpm to prevent vinyl self-polymerization and structural inhomogeneity. After the polymerization was terminated, supercritical CO2 purification technology was used, that is, CO2 was continuously released at a flow rate of 10L / min for 3 hours at 50°C and 15MPa to selectively remove unreacted monomers and oligomers, ensuring that the residual TFVE content was less than 0.1%. The final product was a white powder.

[0053] The schematic diagram of the modified PFA-MF molecular structure is shown below. Figure 3 As shown, the molecular structure is a gradient copolymer of tetrafluoroethylene (TFE) units (92.7 mol%), perfluoropropyl vinyl ether (PPVE) units (5.3 mol%), and trifluoroethylene vinyl ether (TFVE) monomers (2 mol%). Here, m represents the number of repetitions of the tetrafluoroethylene unit (─[CF2─CF2]─) in the molecular chain; n represents the number of repetitions of the perfluoropropyl vinyl ether unit (─[CF2─CF(OC3F7)]─); and p refers to the number of repetitions of the key modifying unit (─[CF2─CF(OCF=CF2)]─).

[0054] Figure 4 A simplified linear structural diagram of the vinyl linkage in the modified perfluoroalkoxy resin is shown. For clarity, only a portion of the molecular fragments are selected. Figure 4 In the text, “C*” represents a specific carbon atom bonded to the ether bond, used to highlight the bonding position of the vinyl group; “─[CF2─CF2]─” represents a tetrafluoroethylene unit; “─[CF2─CF(OC3F7)]─” represents a perfluoropropyl vinyl ether unit; and “─[CF2─CF(OCF=CF2)]─” represents a key modifying unit containing a vinyl side chain.

[0055] II. Preparation of Covalently Bridged Nanotubes. In the most preferred embodiment of this invention, the method for preparing covalently bridged nanotubes includes the following steps:

[0056] III. Step 2-1: A vertical array of h-BNNTs is grown on a Ni111 crystal-oriented nickel foil substrate (purity exceeding 99.99%, surface roughness Ra = 0.3 ± 0.1 nm) via low-pressure chemical vapor deposition (LPCVD). Specific process parameters are: using ammonia borane (NH3BH3) as a precursor, reacting in a hydrogen carrier gas (H2 / NH3BH3 molar ratio 100:1) at 1100℃ ± 10℃ and a pressure of 50 ± 5 Pa for 2 hours to obtain a highly oriented h-BNNT array with a tube diameter of 30 ± 5 nm, a length of 50 ± 5 μm, an orientation angle deviation of less than 3°, and an areal density of not less than 1.2 × 10⁻⁶. 9 tubes / cm 2 .

[0057] Step 2-2: Immerse the h-BNNTs vertical array in an alkaline oxidation solution (this solution is prepared by mixing 28wt% NH4OH aqueous solution and 30wt% H2O2 aqueous solution in a volume ratio of 1:3, pH = 10.5±0.3), and react at 80℃ with constant stirring (200 rpm) for 120±5 minutes to achieve a hydroxyl density of (8.2±0.3) hydroxyl groups / nm on the NTs surface. 2 .

[0058] This hydroxylation modification step can introduce a large number of hydroxyl groups on the surface of nanotubes. These hydroxyl groups will become active sites for subsequent grafting reactions, thereby enhancing the reactivity of nanotubes with other substances.

[0059] Steps 2-3: Disperse the hydroxylated h-BNNTs in anhydrous ethanol (water content less than 50 ppm), add 5 wt% KH-570 (γ-methacryloyloxypropyltrimethoxysilane), and reflux at 82℃±2℃ for 6 hours under nitrogen protection.

[0060] XPS analysis showed that the Si / (B+N) atomic ratio increased to 0.18 ± 0.02 (initial value 0.02), which, combined with FT-IR at 1710 cm⁻¹, further confirmed the positive result. -1 The presence of a C=O characteristic peak confirms successful grafting of the methacryloyl group.

[0061] The above XPS quantitative method is as follows: 1. Test conditions: AlKα rays (1486.6 eV), pass energy 30 eV, step size 0.05 eV; 2. Atomic ratio calculation: [Si / (B+N)]=(ISi1s / σSi) / [(IB1s / σB)+(IN1s / σN)]. The symbols represent: I represents peak area intensity, σ represents photoelectron cross-section factor; ISi... 153 σSi is the photoelectron peak intensity of the 1s orbital of Si; σSi is the photoelectric cross-sectional factor of the 1s orbital of Si; IB 191 IN1s is the peak intensity of the 1s orbital of element B, with a standard value of 190.5 eV for the binding energy of element B; IN1s is the peak intensity of the 1s orbital of element N, with a standard value of 398.2 eV for the binding energy of element N. Grafting density (molecules / nm) 2 ) = 10 14 ×[Si]×ρ / (M×d), where [Si] is the concentration of Si atoms and ρ is the density of BN, approximately 2.28 g / cm³. 3 M is the atomic weight of boron (B), and d is the tube wall thickness, approximately 1.3 nm. Data verification: Si / (B+N) = 0.18 corresponds to a grafting density of approximately 3.2 molecules / nm. 2 (Compliant with more than 3.0 molecules / nm) 2 (demand).

[0062] In steps 2-3, if the reflux temperature is below 80°C, the grafting density will drop to 2.8 molecules / nm. 2 Temperatures above 84℃ may cause KH-570 to decompose, reducing grafting efficiency by 10%-15%.

[0063] KH-570 is hydrolyzed to generate silanol (Si(OH)3), which condenses with hydroxyl groups on the surface of nanotubes to form Si-O-Si and Si-OB bonds (binding energy approximately 340 kJ / mol), providing active sites for subsequent UV crosslinking. In this step, KH-570 is grafted onto the nanotube surface, introducing reactive methacryl groups, which creates conditions for subsequent crosslinking reactions with the matrix material.

[0064] Steps 2-4: Under vacuum conditions, perfluoropolyether diglycidyl ether (PFPE-DE) is injected into the h-BNNTs lumen, followed by UV pre-curing to form closed microcapsules at the tube ends.

[0065] IV. Buffer Layer Preparation. Based on the reaction sites provided by the functionalized nanotubes in step two, a transition layer needs to be constructed in the buffer layer preparation step to achieve thermal stress buffering.

[0066] In the most preferred embodiment of the present invention, the step is as follows: SPEEK (sulfonated polyether ether ketone) powder with a sulfonation degree of 65% is dissolved in DMF (N,N-dimethylformamide, 20wt% solution), mixed with perfluorosulfonic acid resin (PFSA, 15wt% ethanol solution) at a mass ratio of 60:35, and then 5wt% zinc trifluoromethanesulfonate (Zn(TfO)2) crosslinking agent is added to form a spinning solution. This spinning solution is extruded through a multi-needle array (e.g., 100 nozzles, 0.2mm aperture) and deposited onto a transport substrate in a 20kV high-voltage electric field and 30% humidity environment. Then, it is passed through a rotating roller at 2000rpm to ensure that the SPEEK fibers are axially aligned to over 90%, with the fiber diameter controlled at 300±50nm. Subsequently, a Zn(TfO)2-reinforced PFSA solution (coverage 200g / m²) is sprayed using ultrasonic atomization. 2 Then, the fluorine is penetrated into the fiber gaps by a hot press roller at 155℃ and 0.3MPa, forming an interpenetrating network with a fluorine concentration gradient (from 40% in the outer layer to 75% in the inner layer).

[0067] In the buffer layer, Zn 2+ The ions form ion clusters (size 10-15 nm) with -SO3H, and their coefficient of thermal expansion (CTE) gradually changes from 10.8 ppm / K to 50.2 ppm / K, forming a continuous transition with the lower CTE value (axial 2.5 ppm / K) of the first-stage nanotube reinforcement layer. This provides a stress buffer interface for the next step of multilayer co-extrusion.

[0068] V. Preparation of the conductive barrier layer. First, multi-walled carbon nanotubes (MWCNTs) were activated by argon plasma (300W, 20Pa, 10 minutes) to introduce carboxyl functional groups (density exceeding 4 groups / nm) onto their surface. 2 Then, it is ultrasonically dispersed in ethanol to form a stable suspension (5 mg / mL).

[0069] Perfluorosulfonic acid resin (PFSA, equivalent 800 g / mol) was dissolved in an ethanol / water mixture (volume ratio 7:3, solid content 15%) and stirred at 60°C for 2 hours until completely dissolved. Then, 5 wt% zinc trifluoromethanesulfonate (Zn(OTf)2) was added to form a transparent solution. The pretreated MWCNT suspension was added dropwise to the PFSA solution, and the mixture was ultrasonically vibrated for 1 hour (particle size D90 < 100 nm) to obtain a uniform conductive paste. The conductive paste was sprayed onto the surface of a buffer layer, with a wet film thickness controlled at 300 μm. A stepped temperature curing process was then used: solvent evaporation was achieved at 80°C for 10 minutes, pre-crosslinking was achieved at 120°C for 20 minutes, and Zn crosslinking was completed at 155°C for 30 minutes. 2+ Ion exchange (replacement rate exceeding 98%) followed by cold pressing at 0.5 MPa to obtain a dense barrier layer with a thickness of 0.20 ± 0.02 mm. In this layer, the carbon nanotubes have an overlap spacing of no more than 50 nm, forming a three-dimensional conductive network (surface resistivity < 10 Ω·cm). 6 Ω / sq), Zn 2+ The ion clusters (size 10-15 nm) formed with sulfonic acid groups can efficiently adsorb heavy metal ions (adsorption capacity > 15 mg / g).

[0070] VI. Preparation of the hydrophobic layer. A silica nanosphere ethanol dispersion (20 wt%, 2000 rpm) was spin-coated onto the conductive layer surface and annealed at 150°C for 10 minutes to form a hexagonal close-packed array template (dimple density 2.5 × 10⁻⁶). 4 pcs / mm 2 Fluorinated ethylene propylene copolymer (FEP) particles were mixed with 0.5 wt% perfluorooctyltriethoxysilane at 220°C for 15 minutes, then melt-coated onto the template surface (60 μm thickness). Vacuum hot pressing (180°C / 0.3 MPa / 5 minutes) was then performed to allow the FEP melt to completely fill the template gaps. Next, the composite layer was immersed in a 5% hydrofluoric acid solution for 10 seconds to dissolve the SiO2 template, forming a regular array of pits with a diameter of 5.0 ± 0.2 μm and a depth of 0.8 ± 0.1 μm (aspect ratio 0.16). Finally, C4F8 gas plasma treatment (100 W, 2 minutes) was used to graft perfluoroalkyl chains onto the pit surface, increasing the contact angle to over 160° and the roll-off angle to less than 5°.

[0071] This structure achieves the Cassie-Baxter superhydrophobic state by trapping an air layer. After 500 alcohol wipes or immersion in 49% hydrofluoric acid for 24 hours, the contact angle can still be maintained above 155° and the pit deformation rate is less than 3%.

[0072] Through the above-described optimal implementation method, the structural characteristics of the final ultra-clean container composite liner material are as follows: the ultra-clean container composite liner material is composed of four layers of materials with different functions, from the inside to the outside, namely a covalently bonded boron nitride nanotube reinforcement layer, a buffer layer, a conductive barrier layer, and a hydrophobic layer.

[0073] The nanotube reinforcement layer uses modified perfluoroalkoxy resin (PFA-MF) as the matrix material. PFA is modified by introducing 2 wt% vinyl side chains, thus creating active sites for bonding with the reinforcing phase. The reinforcing phase is hydroxylated boron nitride nanotubes (h-BNNTs) with a diameter of 30±5 nm and an aspect ratio >200. The hydroxyl groups on their surface react with γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0074] In ethanol solvent, the hydroxyl groups on the surface of h-BNNTs hydrolyze and condense with the methoxy groups of KH-570 to form stable Si-OB covalent bonds. Subsequently, the methacryloyl groups at the ends of KH-570 undergo free radical polymerization with the vinyl groups in PFA-MF under 365nm ultraviolet irradiation, constructing a three-dimensional cross-linked network. This results in a strong interfacial bond between h-BNNTs and the PFA-MF matrix. This covalently bridged structure not only enhances the mechanical properties of the material but also lays the foundation for subsequent self-healing functions.

[0075] Nanotube arrangement: Transmission electron microscopy (TEM) revealed that h-BNNTs were arranged in a parallel orientation within the resin matrix, with a spacing of 100-150 nm. This ordered arrangement was achieved during magnetic field-assisted multilayer co-extrusion. Utilizing the magnetic moment response characteristics of h-BNNTs, a 0.5T vertical magnetic field was applied to the extrusion channel, ensuring that the alignment angle deviation was less than 5°. This ordered nanotube arrangement facilitates the effective transfer and dispersion of stress within the material, further improving its mechanical properties, such as tensile strength and flexural strength.

[0076] Self-healing structure: Perfluoropolyether diglycidyl ether (PFPE-DE) is selected as the repair agent and filled into the h-BNNTs lumen through vacuum infusion. After UV pre-curing, a perfluoropolyether end-capping layer is formed at the tube end, completely encapsulating the repair agent microcapsules within the lumen, with a diameter of approximately 15 nm. When microcracks appear in the material and the ambient temperature reaches 120℃, the end-capping layer melts, releasing the repair agent. The epoxy groups in the repair agent undergo a ring-opening polymerization reaction with the resin chain scission, achieving in-situ healing of the microcracks. This effectively improves the material's durability and reliability.

[0077] The aforementioned perfluoropolyether diglycidyl ether (PFPE-DE) is an existing product, which is produced and sold by companies such as Chemours and Daikin.

[0078] The buffer layer is formed by electrospinning sulfonated polyether ether ketone (SPEEK, 65% sulfonation) and perfluorosulfonic acid ionomer (PFSA, 800 equivalent) to create an interpenetrating network structure. A 60wt% SPEEK solution is electrospinned in a 20kV high-voltage electric field to form fiber bundles with a diameter of approximately 300nm. Passing through a rotating roller at 2000rpm, the axial fiber alignment exceeds 90%, providing skeletal support for the interpenetrating network. Subsequently, a 35wt% PFSA solution containing 5wt% zinc trifluoromethanesulfonate (Zn(TfO)2) is sprayed on, followed by hot-pressing at 155℃ and 0.3MPa. This allows the PFSA melt to impregnate the gaps between the SPEEK fibers, forming a structure similar to reinforced concrete. This interpenetrating network structure enhances the material's mechanical properties and structural stability. The SPEEK fibers provide support as a rigid skeleton, while the PFSA matrix fills the space within; both work together to withstand external forces.

[0079] Elemental gradient distribution: Energy-dispersive X-ray spectroscopy (EDS) line scan analysis showed that the concentration of F element in this layer exhibited a gradient distribution, from 40% in the outer layer to 75% in the inner layer, reflecting the structural characteristics of the buffer layer. This elemental gradient distribution was achieved during the material preparation process by precisely controlling the composition and processing conditions of each layer.

[0080] Gradient structures allow materials to have different properties at different locations. For example, the outer layer may focus more on interaction with the external environment, with better chemical stability and wear resistance, while the inner layer may focus more on the combination with other layers and the realization of specific functions, such as ion conduction.

[0081] Ionic crosslinking network: High-resolution TEM further confirmed that the spacing between ionic crosslinking points was 10-15 nm, which is consistent with Zn 2+ The theoretical coordination number matches, indicating that an ionic cross-linked network has formed and is uniformly distributed. During the hot-press permeation process, Zn... 2+ The ions form an ionic cross-linking network with the -SO3H groups in SPEEK, with a binding energy exceeding 250 kJ / mol.

[0082] The formation of the ionic cross-linked network enhances the interaction between SPEEK and PFSA, improving the interfacial peel strength of the material to a level far exceeding that of traditional adhesive systems. The interfacial peel strength, measured according to ASTM D1876, is 210±15 J / m². 2 This effectively improves the overall stability and chemical resistance of the material.

[0083] Surface resistance of conductive separator <10 6With a strength of Ω / sq (ASTM D257), it exhibits excellent electrical conductivity. This property is achieved by adding conductive materials such as conductive carbon nanotubes to this layer. Inside cleanroom containers, static electricity can easily be generated due to the flow and friction of chemicals. The conductive barrier layer can promptly conduct away static electricity, effectively preventing electrostatic adsorption and contamination, and maintaining a clean environment inside the container.

[0084] Barrier Structure: This layer not only has conductive properties but also possesses barrier properties, preventing some impurities or ions from passing through. This is due to the combined effect of the material structure and composition within the layer, as well as the interfacial interactions with adjacent layers. For example, the molecular structure of the material within the layer may form tiny pores or channels. The size and shape of these pores or channels selectively allow certain substances to pass through while blocking others, thus achieving the barrier against impurities and ions, further ensuring the ultra-clean environment inside the container.

[0085] A nanotextured superhydrophobic layer was created on the surface of a fuel-embedded polypropylene (FEP) layer using nanoimprinting technology, forming a regular array of micro-pits. The micro-pits on the inner surface have a diameter of 5 ± 0.2 μm and a depth of 0.8 μm. This microtexture is key to achieving the superhydrophobic properties. The presence of these micro-pits alters the surface roughness and wettability of the material, increasing the contact angle of the liquid on the surface.

[0086] According to the Wenzel and Cassie-Baxter models, increased surface roughness amplifies the wettability of the material itself. When the size and shape of the micro-pits meet certain conditions, the contact area between the liquid and the solid surface decreases, and more liquid comes into contact with the air, thus forming a superhydrophobic state with a contact angle exceeding 160°.

[0087] Surface stability structure: The nanotextured superhydrophobic layer exhibits excellent surface stability, maintaining its superhydrophobic properties during long-term use. This is attributed to the inherent chemical stability and abrasion resistance of the FEP material, as well as the stability of the micro-dimple structure. FEP possesses excellent chemical corrosion resistance, resisting the erosion of most chemicals, while the micro-dimple structure does not easily deform or damage under normal use conditions. This ensures the durability of the superhydrophobic properties, guaranteeing that the material effectively prevents liquid adhesion and contamination throughout long-term use.

[0088] The layers of the above structure are tightly bonded together through specific processes to form a unified whole. For example, during the preparation process, the chemically active groups on the surface of the nanotube reinforcing layer interact with the material in the buffer layer, forming chemical bonds or strong physical adsorption, resulting in a high bonding strength between the two layers. Similarly, the buffer layer and the conductive barrier layer, as well as the conductive barrier layer and the hydrophobic layer, are also tightly bonded in a similar manner, ensuring that the layers do not delaminate during the use of the cleanroom container, thus guaranteeing the overall performance and structural stability of the material.

[0089] Figure 5 The test data for different samples of the composite lining material during tensile strength testing are presented. By displaying and comparing the tensile strength of multiple samples, it can be seen that the tensile strength of this composite lining material has a certain degree of stability and consistency. The tensile strength test was conducted according to ASTM D638 standard, and the average tensile strength reached 85 MPa, indicating that the material has high overall tensile strength.

[0090] Figure 6 The specific bending strength values ​​of different samples of the composite lining material are presented in the bending strength test. The bending strength data of multiple samples show that this material performs well in resisting bending deformation, with an average bending strength of 120 MPa, indicating that the material has high bending strength.

[0091] Figure 7 The changes in mass loss of the composite lining material over time when immersed in 98% concentrated sulfuric acid at 180°C are described. The figure shows that even with an immersion time of up to 5000 hours, the mass loss is only 0.12 mg / cm³. 2 This indicates that the material exhibits minimal mass loss in a highly corrosive environment such as concentrated sulfuric acid, demonstrating excellent resistance to concentrated sulfuric acid.

[0092] Figure 8 The data shows the change in surface etching rate of the composite lining material over time when immersed in a 49% hydrofluoric acid solution at 85°C. The data indicates that the surface etching rate is 0.018 μm / day, and the etching rate stabilizes after a period of time, demonstrating the material's good resistance to the highly corrosive environment of hydrofluoric acid. Even after prolonged immersion, the degree of surface etching is very low. This ensures the stability of the cleanroom lining's structure and performance when exposed to hazardous chemicals such as hydrofluoric acid, preventing damage to the lining due to hydrofluoric acid corrosion and guaranteeing the reliability of the cleanroom container in the storage and use of relevant hazardous chemicals.

[0093] Figure 9 The study presents the change in microcrack healing rate of composite lining materials with microcracks over time at 150℃. The figures clearly show that for microcracks with an initial length ≤50μm and a depth ≤10μm, the healing rate reaches 92% within 30 minutes at 150℃.

[0094] Figure 10 The results of surface resistance measurements at different locations on the surface of the conductive interlayer of the composite lining material are presented. From the surface resistance data at each measurement location in the figure, it can be seen that the surface resistance of the conductive interlayer is <10. 6 The value of Ω / sq indicates that this material has good electrical conductivity.

[0095] Figure 11 The results of contact angle measurements at different locations on the surface of the nanotextured superhydrophobic layer of the composite lining material are presented. The contact angle data at each measurement location in the figure show that the contact angle exceeds 160°, indicating that the material surface has superhydrophobic properties.

[0096] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0097] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A composite liner material for ultra-clean containers, characterized in that, The structure comprises, from the outside in, a nanotube reinforcement layer and a buffer layer. The matrix of the nanotube reinforcement layer is a vinyl-modified perfluoroalkoxy resin containing 2% vinyl side chains, and the reinforcing phase is hydroxylated boron nitride nanotubes with a diameter of 25 to 50 nanometers. The surface of the hydroxylated boron nitride nanotubes is covalently grafted with γ-methacryloyloxypropyltrimethoxysilane to form a silicon-oxygen-boron interface, and carbon-carbon crosslinking with the resin matrix is ​​initiated by ultraviolet light. The nanotubes are arranged parallel to each other along the axial direction, and the lumens are encapsulated with perfluoropolyether with a volume loading of 10% to 20%. The diglycidyl ether repair agent is formed by UV curing at the tube end to create sealed microcapsules with a diameter of 10 to 100 nanometers. The rigid skeleton of the buffer layer is composed of axially arranged polyether ether ketone fiber bundles with a diameter of 100 to 300 nanometers and a sulfonation degree of 50% to 75%, accounting for 50% to 70% by weight. A perfluorosulfonic acid ionomer equivalent of 600 to 800 is impregnated into the fiber gaps, and 2.5% to 7% of zinc trifluoromethanesulfonate crosslinking agent is added to form an ionic bond network. The fluorine concentration in the buffer layer increases continuously from the outside to the inside, ranging from 40% to 75%.

2. The composite lining material according to claim 1, characterized in that, The composite lining material also includes a conductive barrier layer; the conductive barrier layer is closely attached to the buffer layer and has a thickness of 0.1 to 0.8 mm. The conductive barrier layer is based on zinc perfluorosulfonate resin with a zinc ion exchange rate of over 98% and contains 1% to 3% by weight of multi-walled carbon nanotubes with a diameter of 5 to 10 nanometers.

3. The composite lining material according to claim 2, characterized in that, The composite lining material also includes a hydrophobic layer; the hydrophobic layer is located inside the conductive barrier layer, with a thickness of 30 to 50 micrometers, and uses fluorinated ethylene propylene copolymer as the substrate, with a regular array of pits on the surface, the pits having a diameter of 3 to 8 micrometers, a depth of 0.5 to 0.9 micrometers, and an aspect ratio of 0.

16.

4. The composite lining material according to claim 3, characterized in that, The thickness of the nanotube reinforcement layer is 1 to 3 mm; the hydroxylated boron nitride nanotubes are prepared by purifying and oxidizing the original boron nitride nanotubes with hydrochloric acid and nitric acid solutions.

5. A method for preparing a composite liner material for ultra-clean containers, characterized in that, Includes the following steps: (1) Preparation of vinyl-modified perfluoroalkoxy resin containing 2% vinyl side chain: Tetrafluoroethylene, perfluoropropyl vinyl ether and trifluorovinyl ether monomers with a purity of more than 99.5% were ultrasonically pre-emulsified in liquid CO2 medium at a molar ratio of 92.7:5.3:2.

0. Ammonium perfluorooctanoate was added to stabilize the dispersion system. The mixture was heated to 75°C in a high-pressure reactor and the pressure was maintained at 4.5MPa±0.2MPa. Gradient copolymerization was initiated by ammonium persulfate aqueous solution. The heating rate was controlled to be ≤1°C / min and the stirring rate was 500rpm. After the polymerization was terminated, supercritical CO2 purification technology was used to allow CO2 to flow continuously at a rate of 10L / min for 3 hours at 50°C and 15MPa to obtain a white powder. (2) Preparation of covalently bridged nanotubes: h-BNNTs vertical arrays were grown on a Ni111 crystal plane oriented nickel foil substrate by low-pressure chemical vapor deposition, immersed in an alkaline oxidation solution for reaction, and then dispersed in anhydrous ethanol with 5 wt% γ-methacryloyloxypropyltrimethoxysilane. The reaction was carried out under nitrogen protection and refluxed. Finally, perfluoropolyether diglycidyl ether was poured in under vacuum and UV pre-cured. (3) Preparation of buffer layer: Sulfonated polyether ether ketone powder with 65% sulfonation degree is dissolved in N,N-dimethylformamide, mixed with perfluorosulfonic acid resin at a mass ratio of 60:35, and 5wt% zinc trifluoromethanesulfonate crosslinking agent is added to form spinning solution. Interpenetrating network is formed by electrospinning, spraying, and hot pressing penetration.

6. The preparation method according to claim 5, characterized in that, It also includes the following steps: (4) Preparation of conductive barrier layer: Multi-walled carbon nanotubes are activated by argon plasma, dispersed in ethanol to form a suspension, mixed with perfluorosulfonic acid resin solution to prepare conductive slurry, sprayed and cured by step heating and cold pressing.

7. The preparation method according to claim 6, characterized in that, It also includes the following steps: (5) Preparation of hydrophobic layer: Spin-coating silica nanospheres with ethanol dispersion onto the surface of conductive layer and annealing to form template. Fluorinated ethylene propylene copolymer and perfluorooctyltriethoxysilane are melt-coated onto the template surface and then vacuum hot-pressed, dissolved, and plasma-treated to form superhydrophobic layer.

8. The preparation method according to claim 7, characterized in that, In step (2), the reflux reaction conditions are 82℃±2℃ and the reaction time is 6 hours.

9. The preparation method according to claim 8, characterized in that, In step (3), the conditions for electrospinning are a 20kV high-voltage electric field and a 30% humidity environment, and the conditions for hot-pressing penetration are 155℃ and 0.3MPa.

10. A clean container comprising an outer shell and an inner liner, the inner liner being made of a composite liner material according to any one of claims 1-4, wherein a nanotube reinforcement layer of the composite liner material is bonded to the inner wall of the outer shell.

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