Nitrogen-fluorinated surface-modified plastic part, treatment method and application thereof

Abstract

The application relates to the field of plastic surface modification, and provides a nitrogen-fluorinated surface modified plastic part, a treatment method and application thereof. A nitrogen-fluorine gradient skin layer is constructed on the surface of an ABS, SAN, NBR or HNBR base material, the F / C ratio in a depth of 0-10 nm and the N / C ratio in a depth of 10-30 nm are synergistically controlled in a nanometer scale, ammonia activation, fluorination densification and programmable time window of oxyfluorination are adopted, the static water contact angle can be switched in the interval of 55-75 DEG or 95-110 DEG, the dynamic friction coefficient is less than or equal to 0.35 (less than or equal to 0.30 in the friction reduction mode), the oxygen permeation rate is reduced by more than 25% compared with the untreated base material, and the size change is less than or equal to 0.1%, so that the key performances such as friction-adhesion, barrier-processability and heat resistance-low temperature flexibility are comprehensively optimized in coating, printing, bonding substrates and low-friction assembly parts, sealing parts and barrier-type packaging or fluid parts, and the part body phase and size are not changed.

Description

Technical Field

[0001] This invention relates to the field of plastic surface modification, and provides a fluorinated plastic part, its processing method and application. Background Technology

[0002] In automotive interior and exterior trim parts, sealing strips, fluid transport components, and functional packaging, acrylonitrile-butadiene-styrene copolymers, styrene-acrylonitrile copolymers, nitrile rubber, and hydrogenated nitrile rubber are widely used as structurally and functionally integrated components. These materials have good comprehensive performance in terms of mechanical strength, heat resistance, and processability. However, their surface energy, polarity, and density are often difficult to match with specific applications. For example, when painting, printing, or bonding is required, a certain range of medium to high surface energy and controllable polarity are desired to ensure the wetting and interfacial bonding of the coating or adhesive. When friction reduction, anti-sticking, or low-noise assembly is required, a lower surface energy and a stable coefficient of dynamic friction are desired to reduce slippage and running friction resistance. When oxygen barrier performance needs to be improved, it depends on the densification and chemical stability of the surface to reduce gas permeability and improve the medium isolation capability, while also taking into account the markability, appearance consistency, and dimensional accuracy in subsequent processes. With the increasing demand for lightweight vehicles, system integration, and extended service life, plastic parts are required to maintain stable surface properties over a wide range of temperatures and loads. This places higher demands on the chemical composition gradient, structural density, and synergistic response of the material surface with the bulk phase. Therefore, how to achieve compatibility and switchability of multiple surface functions on the same part through surface modification without sacrificing bulk phase properties and molding accuracy has become an important problem that urgently needs to be solved in this field.

[0003] To address these needs, the industry has proposed various surface modification solutions for plastic parts, such as plasma treatment, flame treatment, polymer coating, or fluorine- and silicon-containing self-assembled monolayers to adjust surface energy and polarity. However, these solutions still have significant shortcomings in the synergistic control of material composition, structure, and performance. For example, Chinese patent CN101787142B discloses a surface treatment method for inert material automotive parts, which achieves low surface energy of plastic parts through a single fluorine-containing gas treatment. This method can reduce surface friction and dirt adhesion to a certain extent. However, due to the lack of the introduction of nitrogen-containing polar groups and the fine gradient control of fluorine and nitrogen components in the depth direction, it is difficult to simultaneously meet the dual requirements of high adhesion coating / bonding and low friction assembly on the same type of substrate. Moreover, in the inner cavities, grooves, and covered areas of complex three-dimensional structural parts, the uniformity of treatment and batch consistency are often insufficient. Furthermore, although some literature reports on multi-step coating systems can improve oxygen barrier and surface polarity, they introduce additional coating interfaces, which may lead to interlayer peeling risks and dimensional tolerance amplification. In summary, existing technologies often only manage to compromise on some indicators between low surface energy friction reduction, high surface energy adhesion, dense surface barrier, and long-term dimensional stability. There is still a lack of a method and treatment method that can synergistically control the depth distribution and ratio threshold of fluorine and nitrogen elements at the nanoscale, flexibly switch between bonding and friction reduction modes through a programmable process window, and achieve highly consistent intra-batch / site surface composition and performance on complex three-dimensional structural parts. Summary of the Invention

[0004] The purpose of this invention is to provide a fluorinated surface-modified plastic part, its processing method and application, to solve the pain points in the prior art that it is difficult to simultaneously achieve low friction assembly and high adhesion coating, oxygen barrier enhancement and compatibility with subsequent processes, and long-term dimensional and performance stability under automotive service conditions on the same type of plastic substrate.

[0005] By constructing a nitrogen-fluorinated gradient skin with a defined depth window on the surface of plastic parts, a surface layer dominated by carbon-fluorine structures is formed in the 0–10 nm range, and a sub-surface layer dominated by nitrogen-containing polar groups is introduced in the 10–30 nm range. The atomic ratio and ratio of the two are controlled within a specific range. Combined with the coordinated regulation of the time, concentration and atmosphere of ammoniation activation, fluorination densification and oxyfluorination polarization, a programmable synergistic relationship is formed between the low surface energy of the surface layer and the adjustable polarity of the sub-surface layer, and between the surface density and the bulk phase flexibility. Thus, without changing the bulk phase and size of the substrate, multi-dimensional synergistic adjustment of key properties such as static water contact angle, dynamic friction coefficient and oxygen permeability can be achieved, and flexible switching between bonding mode and friction reduction mode can be achieved.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A fluorinated surface-modified plastic part, the base material being an acrylonitrile-butadiene-styrene copolymer, a styrene-acrylonitrile copolymer, nitrile rubber, or hydrogenated nitrile rubber; The surface of the plastic part includes a nitrogen-fluorinated gradient skin; The F / C atomic ratio within a depth range of 0-10 nm is 0.20-0.45; The N / C atomic ratio within a depth range of 10-30 nm is 0.015-0.060; The ratio of the N / C atomic ratio in the depth range of 10-30 nm to the F / C atomic ratio in the depth range of 0-10 nm is not less than 0.10; The static water contact angle is 55-75° or 95-110°; The coefficient of kinetic friction is not greater than 0.35; Compared to the untreated substrate, oxygen permeability is reduced by no less than 25%; The nitrogen-fluorinated gradient skin is a surface modification layer, and the dimensional change of the part before and after treatment does not exceed 0.1%.

[0007] Furthermore, when used for coating or bonding, the static water contact angle is 55-75°, and the ratio of the N / C atomic ratio in the depth range of 10-30 nm to the F / C atomic ratio in the depth range of 0-10 nm is 0.12-0.40; When used for friction reduction or anti-sticking, the static water contact angle is 95-110° and the dynamic friction coefficient is not greater than 0.30.

[0008] Furthermore, the intra-batch relative standard deviations of the F / C atomic ratio and N / C atomic ratio of parts in the same batch do not exceed 10%; The plastic part has a three-dimensional structure with ribs or cavities, and the deviation of the F / C atomic ratio and N / C atomic ratio of the nitrogen-fluorinated gradient skin in the inner cavity, groove, covering area and outer surface does not exceed 10%.

[0009] As a concept of this invention, a nitrogen-fluorinated gradient skin with a specific depth window is constructed on the surface of a plastic part. This is mainly used to enhance the overall interfacial performance of the plastic part under complex working conditions, particularly to achieve synergistic regulation between surface energy, polarity, density, and frictional behavior. By introducing a carbon-fluorine bond-based structure into the 0–10 nm surface region, the surface achieves lower surface energy and higher chemical stability, which helps to reduce the coefficient of dynamic friction and reduce media penetration. Simultaneously, a certain proportion of nitrogen-containing polar groups are introduced into the 10–30 nm subsurface region, maintaining adjustable polarity and hydrogen bonding ability near the surface. In the adhesive mode, this provides sufficient interfacial bonding capacity, while in the friction-reducing mode, by controlling the N / C to F / C ratio, the enhancement of polarity is limited to a certain extent without significantly increasing frictional resistance. By rationally selecting the absolute values ​​and ranges of the F / C atomic ratio and N / C atomic ratio, plastic parts can exhibit stable wetting and adhesion during coating, printing, and bonding processes. Simultaneously, they can maintain low dynamic friction and stain resistance in friction-reducing or anti-sticking scenarios, and achieve at least a 25% reduction in oxygen permeability compared to untreated substrates, thus providing a barrier function. Since the modified layer is constructed directly on the surface of the plastic part rather than through an additional coating, no new interfaces or significant thickness changes are introduced, which helps maintain the original dimensional accuracy and assembly tolerances of the parts. Furthermore, by controlling the processing conditions, the dimensional changes of the parts before and after treatment are limited to within 0.1%, thus ensuring both long-term service stability and low-temperature flexibility in applications sensitive to dimensional stability, such as automotive interior and exterior trim parts and sealing strips. In summary, this concept achieves a comprehensive balance between low surface energy, adjustable polarity of the subsurface layer, and overall barrier capability through the synergistic distribution of the fluorinated layer and the nitrogen-containing polar layer in the depth direction. This allows the traditionally contradictory properties of friction and adhesion, and barrier and processability to be synergistically satisfied in the same type of plastic parts.

[0010] In another aspect of the present invention, a method for preparing a fluorinated surface-modified plastic part is provided, comprising the following steps: S1. Replacement and Pretreatment: Place the plastic part to be treated in the treatment chamber, then evacuate the treatment chamber to a pressure not exceeding 30 Pa, and then refill it with nitrogen to a pressure of 10-60 kPa. Repeat the vacuuming-refilling process 1-3 times. S2, Ammoniation Activation: Introduce ammonia gas with a volume fraction of 0.05-0.30%, at a temperature of 20-35℃, for a time of 30-120 seconds; S3, Fluorinated Dense: A mixture of fluorine and nitrogen with a volume fraction of 0.5-2.0% is introduced in a pulsed or continuous manner for a duration of 30-180 seconds; S4, Oxyfluorination Anode Adjustment: Introduce oxygen with a volume fraction of 0.02-0.20% for 5-60 seconds; S5. Inert gas flushing and aging: After flushing with inert gas, the aging time shall not be less than 2 hours.

[0011] Furthermore, the mixture of fluorine and nitrogen is configured using a parallel mass flow controller, with the fluorine integral set at 0.5-2.0%. Ammonia is introduced only in step S2 via a branch circuit at a volume fraction of 0.05-0.30%. The dew point of the entire flow path is no higher than -40℃, and the system pressure is 10-60 kPa. The equivalent residence time in the mixing section is not less than 0.5 s; Steps S2 and S3 are performed for 1-2 cycles using a pulse sequence of ammoniation for 60-90 s followed by fluorination for 60-120 s, with no fluorine gas introduced during step S2 and no ammonia gas introduced during step S3. The purity of nitrogen gas is not less than 99.999%.

[0012] Furthermore, step S4 is performed after step S3; After completely stopping the fluorine gas supply and purging with inert gas for no less than 30 seconds, oxygen with a volume fraction of 0.02-0.20% is introduced for 5-60 seconds to achieve fine-tuning of surface polarity; A flow field organization method of zoned air intake and recirculation is adopted to improve the processing uniformity of the cavity and shielded area; The exhaust gas is treated by a calcium carbonate absorption unit and a sodium hydroxide alkaline scrubbing unit to remove the byproduct hydrogen fluoride.

[0013] Furthermore, the refill pressure after vacuuming in step S1 is 10-40 kPa; The processing temperature for steps S2 to S4 is 20-35℃, and the processing pressure is 10-40 kPa. The equivalent volumetric flow rate of the mixed gas in steps S2 to S4 is 0.5-5.0 standard liters per minute. Alternatively, the linear velocity, calculated based on the effective cross-sectional area of ​​the processing cavity, is 0.05-0.50 m / s.

[0014] Furthermore, by programmably setting the total time for steps S2 and S3, and whether step S4 is performed, one of the following two operating modes can be achieved: Bonding mode: The total time for step S2 is 60-90 s, the total time for step S3 is 60-90 s, and step S4 is not performed, so that the static water contact angle of the obtained part is 55-75°. Friction reduction mode: The total time for step S2 is 60-90 s, the total time for step S3 is 90-120 s, and step S4 is carried out with an oxygen volume fraction of 0.02-0.10 vol% for 5-30 s, so that the static water contact angle of the obtained part is 95-110° and the dynamic friction coefficient is not higher than 0.30.

[0015] This invention also discloses the application of fluorinated surface-modified plastic parts in coating, printing or bonding substrates, or in low-friction assemblies or seals, or in barrier enhancement of packaging or fluid components.

[0016] Furthermore, it is used as a substrate or sealing strip for automotive interior and exterior coatings, meeting one of the bonding mode or friction reduction mode, and maintaining stable surface F / C atomic ratio, N / C atomic ratio, static water contact angle, dynamic friction coefficient and oxygen permeability during continuous operation or storage for no less than 12 months in an ambient temperature range of -30 to 80 °C.

[0017] As another concept of the present invention, the present invention adopts a programmable process design with ammoniation activation, fluorination densification and oxyfluorination tuning as the core, which is mainly used to enhance the adjustability and reproducibility of the surface properties of fluorinated plastic parts under different application modes. In step S2, a short-term treatment with low-volume-fraction ammonia gas at 20–35°C and 10–40 kPa introduces a certain amount of nitrogen-containing polar groups distributed in the 10–30 nm depth range, providing active sites for subsequent fluorination and forming an adjustable polar subsurface layer. In step S3, the fluorine gas fraction and total treatment time are adjusted to ensure that the equivalent residence time in the mixing section is not less than 0.5 s, thereby forming a dense layer with a carbon-fluorine structure as the main component in the 0–10 nm surface layer, resulting in a lower dynamic friction coefficient and higher media resistance in the friction reduction mode. Based on this, the surface polarity is finely controlled by whether to implement step S4 and by selecting an oxygen volume fraction of 0.02–0.20 vol% and a treatment time window of 5–60 s in step S4, so that the static water contact angle is stable in the range of 55–75° in the bonding mode and in the range of 95–110° in the friction reduction mode. By setting the combined total time and gas volume fraction of S2, S3, and S4, this invention enables rapid switching between bonding and friction-reducing modes under the same substrate type and equipment conditions, simply by changing the process formulation. This avoids the increased complexity and cost associated with traditional solutions that rely on different coating systems or entirely different chemical treatment routes. Furthermore, by controlling the system dew point, pressure, and flow rate throughout the entire process, the internal cavities, grooves, and covered areas of complex three-dimensional structural parts achieve similar F / C and N / C atomic ratios to the outer surface, thereby ensuring consistent surface properties within batches and between sites. This programmable process window design gives this invention high process flexibility and widespread application value in automotive interior and exterior coating substrates, sealing strips, low-friction components, and barrier enhancement-related parts.

[0018] In this invention, the surface structure formed by fluorination, which is mainly composed of carbon-fluorine bonds, and the subsurface layer with nitrogen-containing polar groups formed by ammoniation activation and oxyfluorination polarization have different functional focuses and complement each other. The former mainly imparts significantly reduced surface energy and excellent chemical resistance to the surface through the carbon-fluorine structure with higher bond energy and lower polarity, enabling plastic parts to maintain a low coefficient of dynamic friction and a small medium penetration rate under conditions of friction reduction, anti-sticking, and barrier. The latter, by introducing polar groups such as amino, amide, and quaternary ammonium structures in the depth range of 10–30 nm, improves the interfacial polarity and hydrogen bonding ability, so that the vicinity of the surface layer can provide stable wetting and interfacial bonding force when coating or bonding is required. In automotive coating and structural adhesive bonding, it exhibits high adhesion strength and low risk of interfacial debonding. In terms of improving oxygen barrier performance, the dense fluorocarbon layer significantly inhibits oxygen molecule penetration by increasing diffusion paths and reducing solubility, while the nitrogen-containing polar layer inhibits the evolution of micro-defects and the generation of interfacial microcracks by forming a strong interfacial interaction with the substrate. The synergy of the two layers makes the overall barrier performance significantly better than systems with only single fluorination or single nitrogen-containing polar modification. In terms of friction behavior, the fluorocarbon layer mainly reduces adhesive components by lowering surface energy and enhancing surface rigidity, while the nitrogen-containing polar layer provides sufficient interfacial adhesion in the adhesive mode by controlling polarity density and depth distribution, and avoids excessive increase in interfacial shear strength by limiting polarity upward movement in the friction-reducing mode. Thus, it achieves synergistic regulation of dynamic friction coefficient and static water contact angle within a certain process window. Since both types of structures are generated directly on the substrate surface in situ through vapor phase treatment rather than coating with heterogeneous coatings, a depth-controllable gradient distribution can be achieved while ensuring that the dimensional change does not exceed 0.1%. This makes the present invention exhibit a comprehensive performance potential that is significantly better than single fluorination or single nitrogen-containing treatment in terms of friction-adhesion, barrier-processability, and heat resistance-low temperature flexibility.

[0019] Beneficial technical effects 1. Programmable switching between bonding and friction reduction modes: By coordinating the volume fractions of ammonia, fluorine, and oxygen, as well as the processing time, in the ammoniation activation, fluorination densification, and oxyfluorination polarization steps, this invention enables the static water contact angle to be switched between two windows, 55–75° and 95–110°, on the same type of plastic substrate through simple switching of process formulations. This corresponds to obtaining two typical working conditions: high adhesion coating / bonding and low friction reduction. This avoids the complexity of relying on different coating systems or completely different processing equipment in traditional solutions, and helps to reduce production line switching costs and quality fluctuation risks.

[0020] 2. Improved oxygen barrier performance while ensuring compatibility with subsequent processes: This invention forms a dense layer with a carbon-fluorine structure as the main component on the 0–10 nm surface layer and introduces an appropriate amount of nitrogen-containing polar groups on the 10–30 nm subsurface layer. Compared with untreated plastic parts of the same substrate, the oxygen permeability is reduced by no less than 25%, while retaining a certain surface polarity adjustment capability. This ensures that the parts still have good interface activation and appearance consistency in subsequent processes such as coating, printing, laser marking, or visual recognition. Compared with the solution of using a thick barrier layer, it significantly reduces the negative impact on size and appearance while ensuring barrier performance.

[0021] 3. Ensuring batch-to-batch and site-specific consistency of complex three-dimensional structural parts: This invention introduces zoned air intake, recirculation, and equivalent residence time control in the processing of cavity flow field organization and gas path control. This enables three-dimensional plastic parts with ribs, concave cavities, and covered areas to achieve similar F / C atomic ratios and N / C atomic ratios in the inner cavity, groove, covered area, and outer surface, with deviations not exceeding 10%. The relative standard deviation within the same batch of parts also does not exceed 10%, thereby significantly improving the surface performance consistency of products during actual vehicle assembly or installation, and reducing the risk of coating defects, adhesion failures, or abnormal local friction caused by insufficient local processing.

[0022] 4. Balancing long-term dimensional and performance stability: By implementing ammoniation, fluorination, and oxyfluorination treatments under low temperature and low pressure conditions, and controlling the nitrogen fluorination gradient skin to be a thin layer directly constructed on the substrate surface, this invention significantly adjusts the surface composition and properties while controlling the dimensional changes of the parts before and after treatment to within 0.1%. Moreover, within an ambient temperature range of -30 to 80°C, during continuous operation or storage for no less than 12 months, the surface F / C atomic ratio, N / C atomic ratio, static water contact angle, dynamic friction coefficient, and oxygen permeability remain stable. This invention is suitable for applications such as automotive interior and exterior trim parts and seals that require high reliability and dimensional accuracy for long-term service. Attached Figure Description

[0023] Figure 1 The effect of step S3 on the fluorine gas integral number on the static water contact angle and the reduction rate of oxygen permeability.

[0024] Figure 2 The effect of the ammonia gas integral in step S2 on the static water contact angle and the rate of decrease in oxygen permeability.

[0025] Figure 3 The effect of step S3 fluorination time on static water contact angle and oxygen permeability reduction rate.

[0026] Figure 4 The image shows a scatter plot of the static water contact angle and dynamic friction coefficient of the nitrogen-fluoride gradient skin sample in Example 1 of this invention.

[0027] Figure 5 This is a box plot of the F / C multi-position of Embodiment 1 of the present invention (outer surface, inner cavity, groove, and covering area).

[0028] Figure 6 This is a box plot of the N / C multi-position area (outer surface, inner cavity, groove, and covering area) of Embodiment 1 of the present invention.

[0029] Figure 7 This is a bar graph showing the dimensional changes (%) of Embodiment 1 of the present invention by location (outer surface, inner cavity, groove, and covering area).

[0030] Figure 8 These are XPS depth profile images of Embodiment 1 and the comparative example of the present invention.

[0031] Figure 9 This is the C 1s high-resolution spectrum of the surface layer in Embodiment 1 of the present invention.

[0032] Figure 10 This is the N 1s high-resolution spectrum of the surface layer in Embodiment 1 of the present invention.

[0033] Figure 11 This is the F 1s high-resolution spectrum of the surface layer in Embodiment 1 of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0035] Unless otherwise specified, the operations in the examples were performed under standard conditions or conditions recommended by the manufacturer. The reagents or instruments used, unless otherwise specified, are commercially available products.

[0036] Example 1 The fluorinated surface-modified plastic part of this embodiment uses acrylonitrile-butadiene-styrene copolymer (ABS) as the substrate. It is injection molded into a three-dimensional structure with peripheral reinforcing ribs and localized cavities. The substrate contains 22% acrylonitrile, 16% butadiene, and 62% styrene by mass. The surface of the plastic part in this embodiment includes a fluorinated gradient skin layer. The F / C atomic ratio is 0.32 in the depth range of 0-10 nm, and the N / C atomic ratio is 0.038 in the depth range of 10-30 nm. Furthermore, the N / C atomic ratio in the depth range of 10-30 nm is similar to that in the depth range of 0-10 nm. The F / C atomic ratio within the nm range is 0.038 / 0.32 = 0.119, which meets the requirement of a ratio not less than 0.10. The static water contact angle in this embodiment is 64°, within the 55-75° range, and the dynamic friction coefficient is 0.28, not greater than 0.35. Compared to untreated ABS samples of the same substrate, tested under ASTM D3985 conditions, the oxygen permeability of this embodiment is reduced by 32%, not less than 25%. The nitrogen-fluoride gradient skin layer in this embodiment is a surface modification layer. Measurements of key dimensions using a coordinate measuring machine show that the linear dimensional change of the part before and after treatment is 0.03%, not exceeding 0.1%. When the plastic parts in this embodiment are used for coating or bonding, the static water contact angle is 64°, and the N / C atomic ratio within the 10-30 nm range and the depth within the 0-10 nm range are used. The F / C atomic ratio in the nm range is 0.119, falling slightly below 0.12. In this embodiment, mass production was carried out when the ratio was stabilized at 0.125 (i.e., N / C is 0.040 and F / C remains unchanged at 0.32) through process fine-tuning. This ratio is in the range of 0.12-0.40. When the same batch of parts was prepared using the same process conditions, XPS measurements were performed on the surface of 50 samples. The intra-batch relative standard deviation of the F / C atomic ratio in this embodiment was 6.5%, and the intra-batch relative standard deviation of the N / C atomic ratio was 7.2%, both not exceeding 10%. By sampling the outer surface, inner cavity, groove, and covered area of ​​the three-dimensional ABS parts, the relative deviations of the F / C atomic ratio and N / C atomic ratio in each region of the same batch did not exceed 8% and 10%, respectively, indicating that the nitrogen-fluorinated gradient skin layer is uniformly distributed on the complex structure.

[0037] The fluorinated surface-modified plastic parts of this embodiment are obtained through the following treatment method: In step S1, the ABS plastic parts to be treated are placed in a stainless steel treatment chamber, and a dry vacuum pump is used to evacuate to 20 Pa. Then, high-purity nitrogen is used to refill to 30 kPa. The vacuum-refill cycle is repeated twice to effectively replace residual air, moisture, and low-boiling-point impurities in the treatment chamber. In step S2, under the conditions of a total pressure of 30 kPa and a temperature of 25°C, ammonia gas with a volume fraction of 0.18% is introduced into the main nitrogen flow through a mass flow controller. The equivalent volumetric flow rate of the mixed gas is 2.0 standard liters per minute (slm), and the linear velocity converted from the effective cross-sectional area of ​​the treatment chamber is 0.20 m / s. The ammoniation time is 75 s. In step S3, under the conditions of maintaining a total pressure of 30 kPa and a temperature of 25°C, the ammonia supply is stopped, and at the same time, fluorine gas with a volume fraction of 1.2% is introduced into the nitrogen through a parallel mass flow controller. The mixed gas is introduced in a continuous mode for a total time of 75 s. The equivalent residence time in the mixing section is 1.0 s; step S4 is not performed, i.e., oxygen is not introduced for polarity adjustment in the bonding mode; in step S5, nitrogen is used for flushing immediately after the fluorine supply is stopped, with a nitrogen purity of not less than 99.999% and a flushing time of 60 s, during which the system pressure is maintained at 30 kPa and the dew point is not higher than -40℃. Then the processing chamber is vented to atmospheric pressure, the part is taken out, and aged in a dry and clean environment at room temperature for 4 h, with an aging time of not less than 2 h; in the whole process, the refill pressure after vacuuming in step S1 is 30 kPa, which meets the 10-40 kPa requirement; the processing temperature in steps S2 to S3 is 25℃, within the range of 20-35℃; the processing pressure is 30 kPa, within the range of 10-40 kPa; the mixed gas volume flow rate is 2.0 slm, falling within the range of 0.5-5.0 slm; and the linear velocity is 0.20 m / s, within the range of 0.05-0.50 m / s. Within the range of m / s; the above process is controlled by programmable control, setting the total time of step S2 to 75 s, the total time of step S3 to 75 s, and step S4 not to be implemented, so that the static water contact angle of the obtained part is 64°, which meets the parameter requirements of the bonding mode; the exhaust gas is treated by a calcium carbonate packed tower and a sodium hydroxide solution alkaline washing tower connected in series to remove acidic byproducts such as hydrogen fluoride, and the dew point of the entire system is maintained at -45℃ and not higher than -40℃ to ensure the repeatability of the surface reaction.

[0038] The characteristic of this embodiment is that all process parameters, surface atomic ratio and macroscopic properties are selected near the median of their respective ranges. With the bonding mode as the target, it emphasizes processing uniformity and batch stability. It is suitable for ABS parts that require subsequent spraying, printing or bonding, such as automotive interior parts, home appliance housings, and printer housings. It has high industrial operability, a wide process window, and moderate requirements for equipment and online control precision.

[0039] Example 2 The fluorinated surface-modified plastic part of this embodiment uses hydrogenated nitrile butadiene rubber (HNBR) as its base material. The formulation contains 96% hydrogenation of the nitrile butadiene rubber and 34% acrylonitrile. It is molded into a complex oil seal structure with a sealing lip and inner cavity, forming a closed-loop three-dimensional structure. After treatment in this embodiment, the plastic part surface has a fluorinated gradient skin. The F / C atomic ratio in the 0-10 nm depth range is 0.41, located in the high-position region of the 0.20-0.45 range; the N / C atomic ratio in the 10-30 nm depth range is 0.026, corresponding to the N / C atomic ratio distribution in the lower middle part of the 10-30 nm depth range in this embodiment. The aforementioned N / C atomic ratio in the 10-30 nm depth range is similar to that in the 0-10 nm depth range. The F / C atomic ratio in the nm range is approximately 0.026 / 0.41 ≈ 0.063. In this embodiment, by adjusting the ratio of ammoniation time to fluorination time, the N / C atomic ratio is increased to 0.042 while the F / C ratio is maintained at 0.41, resulting in a ratio of approximately 0.042 / 0.41 ≈ 0.102, which meets the requirement of not less than 0.10. Furthermore, in friction-reducing mode, this ratio is controlled slightly above the lower limit, which is beneficial for maintaining a certain nitrogen content while maintaining a high degree of fluorination to improve interfacial polarity uniformity. The static water contact angle in this embodiment is 102°, falling within the 95-110° range, corresponding to friction-reducing or anti-sticking applications. The dynamic friction coefficient is as per ASTM standards. The D1894 test result is 0.23, not greater than 0.30; compared with the untreated HNBR oil seal of the same substrate, the oxygen permeability of this embodiment is reduced by 40%, and it has a significant inhibitory effect on the permeation of dissolved oxygen in lubricating oil at 25°C, meeting the requirement of a reduction of not less than 25%; since it is a surface modification layer, the changes in diameter and lip thickness of the part before and after treatment in this embodiment are both less than 0.05%, and the maximum dimensional change is 0.04%, which does not exceed 0.1%.

[0040] This embodiment employs a friction-reduction process, specifically including: Step S1, placing the HNBR oil seal in a cylindrical processing chamber, evacuating to 25 Pa using a dry vacuum pump, then refilling with high-purity nitrogen to 20 kPa, repeating the evacuation-refill cycle once to ensure sufficient replacement of air and moisture in the inner chamber and the labial cavity; Step S2, under conditions of 30℃ and a total pressure of 20 kPa, introducing ammonia gas with a volume fraction of 0.22% into the nitrogen gas using a mass flow controller, with an equivalent volumetric flow rate of 1.5 slm, corresponding to a linear velocity of 0.18 m / s, and an ammoniation time of 80 s; Step S3, immediately after Step S2, under the same conditions of 30℃ and a total pressure of 20 kPa, introducing fluorine gas with a volume fraction of 1.6% into the main nitrogen flow using a parallel mass flow controller, continuously introducing the mixed gas in this stage for a total time of 105 s, ensuring that the total fluorination time in Step S3 is within the 90-120% range specified by the friction-reduction mode. In step S4, the equivalent residence time of the mixing section is 0.8 s, located slightly above the middle of step S3. After rinsing with inert nitrogen for 40 s and confirming that there is no free fluorine gas in the treatment chamber, oxygen with a volume fraction of 0.06% is introduced into the main nitrogen flow at a total pressure of 20 kPa for 20 s. This achieves moderate-intensity oxygen fluorination and polarity adjustment, causing a slight return of surface polarity, which is beneficial for improving interfacial adsorption stability while maintaining a high contact angle. In step S5, after stopping the oxygen supply, nitrogen is used for rinsing for another 60 s, with a nitrogen purity of not less than 99.999% and the dew point of the entire flow path controlled at -42℃. After treatment, the sample is taken out and aged in a sealed environment at room temperature for 3 h, with an aging time of not less than 2 h. In this embodiment, the refill pressure after vacuuming in step S1 is 20 kPa, which is within the range of 10-40 kPa. The treatment temperature from step S2 to step S4 is 30℃, within the range of 20-35℃, and the treatment pressure is 20 kPa. The kPa value is in the range of 10-40 kPa; the ammonia gas fraction is 0.22% in the range of 0.05-0.30%, the fluorine gas fraction is 1.6% in the range of 0.5-2.0%, the oxygen volume fraction is 0.06% in the range of 0.02-0.20%, and the oxygen fluorination time is 20 s in the range of 5-60 s; the total times of S2 and S3 are 80 s and 105 s respectively, corresponding to a total time of 60-90 s for S2 and 90-120 s for S3 in the friction reduction mode. The upper and middle regions of the s; the entire process adopts a zoned air intake and recirculation flow field organization method, which increases the gas renewal frequency of the oil seal cavity and shielding area by 30%, ensuring that the F / C and N / C atomic ratio deviation of the nitrogen-fluoride gradient skin in the inner cavity and lip region and the outer surface does not exceed 9%; the exhaust gas is neutralized by most of the HF and F2 by the calcium carbonate absorption unit, and then post-treated by the sodium hydroxide alkaline washing unit, and the acid gas emission in the exhaust gas is lower than the national standard limit.

[0041] The feature of this embodiment is that by increasing the degree of fluorination and moderately adjusting the fluorination polarity, the surface contact angle and friction reduction performance are biased towards the high value region, achieving a low dynamic friction coefficient (0.23) and significant barrier performance. It is suitable for high-requirement low-friction assemblies, engine and transmission oil seals, pneumatic actuator seals and other scenarios. It maintains a stable lubricating film and wear resistance over a wide temperature range, and is especially suitable for industrial equipment that is sensitive to starting torque and energy consumption.

[0042] Example 3 The fluorinated surface-modified plastic part of this embodiment uses a styrene-acrylonitrile copolymer (SAN) as its substrate, with an acrylonitrile mass fraction of 26% and a styrene mass fraction of 74%. It is injection molded into a functional support for an instrument panel with multiple intersecting ribs and partially covered metal inserts, constituting a complex three-dimensional part. After treatment in this embodiment, a fluorinated gradient skin is formed on the surface of the plastic part. The F / C atomic ratio in the depth range of 0-10 nm is 0.24, located in the lower region of the 0.20-0.45 range; the N / C atomic ratio in the depth range of 10-30 nm is 0.054, close to the upper part of the 0.015-0.060 range but not reaching the extreme value; the N / C to F / C ratio is 0.054 / 0.24=0.225, significantly higher than 0.10, and in the upper middle part of the 0.12-0.40 range, emphasizing a relatively high nitrogen content at the interface, which is beneficial for improving surface polarity and adhesion performance. The static water contact angle of this embodiment is 58°, which is in the lower range of 55-75°, indicating a preference for hydrophilic and wettable states. The dynamic friction coefficient is 0.31 without lubricant, which is not greater than 0.35, but significantly higher than in Example 2, reflecting the strategy of prioritizing adhesive performance over friction reduction in this embodiment. Compared with untreated SAN components of the same substrate, the oxygen permeability is reduced by 28%, which has practical value in packaging and interior part barrier applications. Since the nitrogen-fluorinated gradient skin is limited to the surface within tens of nanometers, the maximum change in critical dimensions of the parts before and after treatment in this embodiment is 0.02%, far below the limit of 0.1%.

[0043] In terms of processing methods, the parameter configuration leans towards increasing nitrogen content and reducing fluorination intensity. Specifically: Step S1, the SAN component to be treated is placed in a rectangular processing chamber, and a vacuum pump is used to evacuate it to 28 Pa. Then, it is refilled with high-purity nitrogen to 15 kPa. The vacuum-refill process is repeated 3 times to fully replace the air and moisture in the cavity and rib gaps of the structural component; Step S2, under the conditions of a total pressure of 15 kPa and a temperature of 22°C, ammonia gas with a volume fraction of 0.27% is introduced into the mainstream nitrogen gas through a mass flow controller. The equivalent volumetric flow rate of the mixed gas is 1.0 slm, the converted linear velocity is 0.10 m / s, and the ammoniation time is 90 s, so that the ammoniation time is close to the upper limit of the bonding mode, which is conducive to the formation of a thicker nitrogen-containing activation layer; Step S3 is carried out after Step S2. Under the same conditions of 22°C and a total pressure of 15 kPa, fluorine gas with a volume fraction of 0.80% is introduced into the nitrogen gas through a parallel mass flow controller. The mixed gas is introduced in a continuous manner, and the total time is 60 s. The s is slightly higher than the lower limit of the bonding mode (60 s) but lower than the median value, resulting in a lower degree of fluorination. This helps to avoid excessive hydrophobicity, which would reduce the spreadability of the coating liquid. The equivalent residence time of the mixing section is 0.7 s. Step S4 is not performed to achieve the standard bonding mode and avoid the increase in contact angle caused by additional oxygen fluorination. In step S5, after step S3, the system is immediately flushed with nitrogen for 90 s. The nitrogen purity is 99.999%, the dew point is not higher than -40℃, and the system pressure is maintained at 15 kPa. Then, the gas is slowly released to atmospheric pressure. After the part is removed, it is aged in a clean environment for 2 hours. In this embodiment, the refill pressure after vacuuming in step S1 is 15 kPa, within the range of 10-40 kPa; the processing temperature in steps S2 to S3 is 22℃, within the range of 20-35℃, and the pressure is 15 kPa, within the range of 10-40 kPa; the ammonia gas fraction of 0.27% meets the range of 0.05-0.30%, and the fluorine gas fraction of 0.80% meets the range of 0.5-2.0%; the total time of S2 (90 s) and S3 (60 s) respectively meet the bonding mode range of 60-90 s; the mixed gas flow rate is 1.0 slm, within the range of 0.5-5.0 slm, and the linear velocity is 0.10 m / s, within the range of 0.05-0.50 m / s. Within the range of m / s; the dew point of the entire system flow path is -43℃, not higher than -40℃; through partitioned XPS measurements of 30 complex three-dimensional SAN components in the same batch on the outer surface, inner cavity, and near the covered metal insert, the intra-batch relative standard deviations of the F / C and N / C atomic ratios in this embodiment are 8.0% and 7.5%, respectively. The deviations of the F / C and N / C atomic ratios in the inner cavity, groove, covered area, and outer surface are all less than 9%, meeting the requirement of not more than 10%.

[0044] The key feature of this embodiment is the use of a relatively high ammoniation time and a low fluorination strength, which results in a significant increase in surface nitrogen content while maintaining a moderate fluorine content. This leads to a lower contact angle, which is beneficial for the wetting and spreading of the primer, structural adhesive, and two-component polyurethane adhesive. It is particularly suitable for applications requiring high-reliability bonding strength and coating adhesion, such as automotive interior and exterior trim coating substrates, dashboard frames, and engineering plastic brackets for bonding metal inserts. At the same time, it maintains a moderate level of barrier performance and dimensional stability, making it suitable for mass production.

[0045] Example 4 This embodiment of the fluorinated surface-modified plastic part uses nitrile rubber (NBR) as the base material and has an acrylonitrile mass fraction of 30%. It is manufactured using an injection molding process to create a packaging valve assembly with deep cavities and multiple sealing edges, used to improve the barrier performance of fluid components. This embodiment selects an 8-12% region close to the upper and lower boundaries of the process and surface parameters, while ensuring a safety margin for key performance parameters, but avoiding multiple key performance parameters being at their limits simultaneously. Specifically, in this embodiment, the F / C atomic ratio of the fluorinated gradient skin layer on the surface of the plastic part is 0.22 in the 0-10 nm depth range, close to the lower limit of 0.20 but with a margin of approximately 10% ((0.22-0.20) / 0.20=10%). The depth is 10-30 nm. The N / C atomic ratio in the nm range is 0.017, close to the lower limit of 0.015 but also has a margin of about 13.3% ((0.017-0.015) / 0.015≈13.3%). The ratio of the two is 0.017 / 0.22≈0.077. In this embodiment, by slightly increasing N / C to 0.023 and maintaining F / C at 0.22, the ratio is increased to 0.023 / 0.22≈0.105, which is close to the lower boundary of the ratio range while maintaining a safety margin of about 5%, and does not affect the compliance of other parameters. With this surface composition, the static water contact angle in this embodiment is 97°, which is in the low range of 95-110° and close to the lower limit of the friction reduction mode. Nearby, it was used to verify that the high fluorination lower limit combination can still achieve hydrophobicity; the dynamic friction coefficient is 0.29, close to the upper limit of the friction reduction mode of 0.30, but still has a safety margin of about 3.3% ((0.30-0.29) / 0.30≈3.3%), which still has a safety window considering friction test errors and surface wear in actual long-term operation; compared with the untreated NBR valve assembly of the same substrate, the oxygen permeability is reduced by 25.5%, which is used to verify that the barrier requirements can be met even at a lower modification strength; the thickness of the key sealing edge and the valve seat diameter before and after the treatment were tested, and the maximum dimensional change was 0.09%, close to the upper limit of 0.1%, but with a margin of about 10%, ensuring that the assembly tolerance and sealing performance are not affected.

[0046] This embodiment employs a variation of the friction reduction mode, utilizing a near-boundary configuration to verify the boundary regions of multiple process parameters: In step S1, the NBR valve assembly is placed within a vertical cylindrical processing chamber, evacuated to 30 Pa using a vacuum pump, and then recharged to 12 kPa with high-purity nitrogen. This evacuation-recharge process is repeated twice, maintaining a relative margin of over 20%. In step S2, at a temperature of 21°C and a total pressure of 12 kPa, ammonia gas with a volume fraction of 0.06% is introduced into the main nitrogen stream via a branch mass flow controller. This ammonia gas is positioned near the lower limit of the 0.05-0.30% range, but retains approximately a 20% margin ((0.06-0.05) / 0.05=20%). The equivalent volumetric flow rate of the mixed gas is 0.60 slm, corresponding to a linear velocity of 0.06 m / s, close to the 0.5-5.0 slm and 0.05-0.50 slm ranges. The flow rate is below the lower end of the range to verify the uniformity of treatment under low flow conditions. The ammoniation time is 65 s, which is close to the lower limit of 60-90 s in the friction reduction mode. In step S3, under the same temperature of 21℃ and total pressure of 12 kPa, fluorine gas with a volume fraction of 1.95% is introduced into the nitrogen mainstream through a parallel mass flow controller, which is close to the upper limit of 0.5-2.0% and retains a margin of about 2.5% ((2.0-1.95) / 2.0=2.5%). The mixed gas is introduced continuously for a total time of 118 s, which is close to the upper limit of 90-120 s in the friction reduction mode, but retains a safety margin of about 1.7% ((120-118) / 120≈1.7%). The equivalent residence time of the mixing section is 0.6 s. Step S4 is carried out after step S3, after completely stopping the fluorine gas supply and rinsing with high-purity nitrogen for 35 seconds. After s, once it was confirmed that the fluorine concentration in the cavity had dropped to a negligible level, oxygen with a volume fraction of 0.025% was introduced under a total pressure of 12 kPa, close to the lower limit of the 0.02-0.20% range and retaining a margin of about 25% ((0.025-0.02) / 0.02=25%). The oxygen fluorination time was 8 s, close to the lower side of the 5-60 s range and retaining a margin of about 37.5% ((8-5) / 5=60%, but the safety margin is larger from the upper limit), ensuring that the contact angle can be finely adjusted without significantly increasing the dynamic friction coefficient under slight polarity adjustment. In step S5, after stopping the oxygen supply, nitrogen was used for 70 s rinsing, with a nitrogen purity of not less than 99.999%. The dew point of the entire flow path was controlled at -41℃, slightly lower than -40℃ and retaining a margin of about 2.5%. Then the pressure was slowly increased to atmospheric pressure, the sample was taken out and aged in a dry environment for 3 h.In this embodiment, while the key process parameters are close to their limits, the rule that opposing parameters cannot simultaneously reach their limit values ​​is followed: when the recharge pressure is close to the lower limit, the ammonia concentration and fluorine concentration are close to the lower and upper limits of their respective ranges, but the time settings of steps S2 and S3 are kept in the middle to high range of their respective ranges (ammoniation 65 s is close to but not equal to the lower limit, fluorination 118 s is close to the lower limit). The parameters (s) are close to but not equal to the upper limit, and key parameters that have a significant impact on the process, such as temperature and dew point, are all selected within a safe range slightly below the median (21℃ and -41℃). XPS testing was performed on 40 NBR valve assemblies from the same batch on the outer surface, deep cavity, and each sealing edge area. The intra-batch relative standard deviations of the F / C atomic ratio and N / C atomic ratio in this embodiment were 9.5% and 9.0%, respectively, both not exceeding 10%. The deviations of the F / C and N / C atomic ratios in the inner cavity, groove, and shielded area relative to the outer surface were all less than 10%, proving that good uniformity can still be obtained under low pressure, low flow rate, and near-boundary parameter combinations. The exhaust gas system adopts a configuration similar to the calcium carbonate absorption unit + sodium hydroxide alkaline washing unit in the aforementioned embodiment. Considering that the fluorine concentration and time in this embodiment are close to the upper limit, the packing amount and alkaline washing liquid volume of the exhaust gas treatment unit are increased by 20% to ensure that the HF emission concentration remains below the safe limit. The key feature of this embodiment is that it systematically verifies the process feasibility and performance reliability near the lower limits of multiple dimensions, such as ammonia concentration, fluorine concentration, oxygen concentration, processing pressure, and S2 and S3 times, while focusing on the lower limits of N / C and F / C ratios, contact angles, and oxygen permeability. By maintaining a 5-10% safety margin in key performance parameters (ratios, dynamic friction coefficient, and dimensional changes), and by demonstrating repeatability and operational safety under industrial conditions, it is suitable for packaging valves, fluid transfer joints, and thin-walled sealing components that require both barrier and friction-reducing performance. During continuous operation or storage for 12 months in an ambient temperature range of -30 to 80°C, the surface F / C, N / C atomic ratio, static water contact angle, dynamic friction coefficient, and oxygen permeability remain stable after periodic sampling.

[0047] Comparative Example 1: The procedure is basically the same as in Example 1, except that the ammonia gas fraction in the ammoniation activation stage in step S2 is set to 0.03 vol%, and the total pressure, temperature, and ammoniation time are kept constant at 30 kPa, 25°C, and 75 s. Steps S3, S4, S5, and other conditions are the same as in Example 1.

[0048] Comparative Example 2: The procedure is basically the same as in Example 1, except that the ammonia gas fraction in the ammoniation activation stage in step S2 is set to 0.40 vol%, the total pressure is 30 kPa, the temperature is 25°C, and the ammoniation time is 75 s. Steps S3, S4, S5 and other conditions are the same as in Example 1.

[0049] Comparative Example 3: The procedure is basically the same as in Example 1, except that in step S3, the integral of fluorine gas in the fluorination densification stage is set to 0.30 vol%, the total pressure is 30 kPa, the temperature is 25°C, the fluorination time is 75 s, and the mixed gas volume flow rate is 2.0 slm. The other conditions are the same as in Example 1.

[0050] Comparative Example 4: The procedure is basically the same as in Example 1, except that in step S3, the fluorine gas integral in the fluorination densification stage is set to 2.50 vol%, the total pressure is 30 kPa, the temperature is 25°C, the fluorination time is 75 s, and the mixed gas volume flow rate is 2.0 slm. The remaining steps are the same as in Example 1.

[0051] Comparative Example 5: The procedure is basically the same as in Example 1, except that the ammoniation activation time in step S2 is adjusted to 40 s; the ammonia gas integral is kept at 0.18 vol%, and steps S3, S4, S5 and other conditions remain unchanged.

[0052] Comparative Example 6: The procedure is basically the same as in Example 1, except that the ammoniation activation time in step S2 is adjusted to 120 s; the ammonia gas integral is 0.18 vol%, and steps S3, S4, S5 and other conditions are the same as in Example 1.

[0053] Comparative Example 7: The process is basically the same as in Example 1, except that the fluorination densification time in step S3 is set to 40 s; the fluorine gas fraction is 1.2 vol%, the total pressure is 30 kPa, the temperature is 25°C, and other process conditions are kept the same as in Example 1.

[0054] Comparative Example 8: The procedure is basically the same as in Example 1, except that the fluorination densification time in step S3 is set to 150 s; the fluorine gas integral percentage of 1.2 vol%, the total pressure of 30 kPa, the temperature of 25°C, and the mixed gas flow rate of 2.0 slm remain unchanged, and the conditions of other steps remain unchanged.

[0055] Comparative Example 9: The procedure is basically the same as in Example 1, except that step S4 is added after step S3: oxygen with a volume fraction of 0.08 vol% is introduced under a total pressure of 30 kPa and a temperature of 25°C for 20 s, followed by inert gas flushing and aging in step S5; other parameters are completely the same as in Example 1, and the total time for ammoniation and fluorination remains unchanged.

[0056] Comparative Example 10: The process is basically the same as in Example 1, except that the processing pressure in steps S2 and S3 is uniformly set to 60 kPa, the conditions of evacuating to 20 Pa and refilling to 30 kPa in step S1 remain unchanged, step S4 is not performed, and step S5 remains the same as in Example 1.

[0057] Comparative Example 11: The process is basically the same as in Example 1, except that the equivalent volumetric flow rate of the mixed gas in steps S2 and S3 is uniformly adjusted to 0.30 standard liters per minute, corresponding to a linear velocity of approximately 0.03 m / s; other process parameters remain the same as in Example 1.

[0058] Comparative Example 12: Dew point of the entire flow path is higher than the limit value The system is basically the same as Example 1, except that the dew point of the entire flow path is controlled at -20°C. All other conditions, including nitrogen gas integral, ammonia gas integral, fluorine gas integral, processing pressure and time, are the same as in Example 1.

[0059] Comparative Example 13: The process is basically the same as in Example 1, except that the nitrogen used in all steps has a purity of 99.9%, and the system pressure, dew point, ammonia and fluorine gas integrals, processing time and temperature are the same as in Example 1.

[0060] Performance testing: Static water contact angle test: The test object is the smooth outer surface of the fluorinated plastic parts modified with nitrogen fluorination in Examples 1-4 and Comparative Examples 1-13. Test objective: To quantitatively evaluate the differences in surface wettability under different process conditions, providing a basis for the process window of bonding mode and friction reduction mode. Test principle: The contact angle after the droplet reaches equilibrium on the solid surface is used to characterize the surface energy and polarity. The smaller the contact angle, the more hydrophilic the surface. Experimental method: Using a contact angle measuring instrument, under the conditions of (23±2)℃ and (50±5)% relative humidity, deionized water (conductivity ≤0.1 μS / cm) is slowly dripped onto the sample surface at a volume of 2 μL. Contact angle images are collected from different directions, and readings are taken 5 seconds after dripping. Five positions are measured for each sample. Standard basis: Refer to ASTM D7334 and other contact angle testing standards. Key parameters: Ambient temperature, humidity, drop volume, reading time, number of measurement points. Data processing: Calculate the mean and standard deviation of the contact angle for each sample (n≥5), and record the results in the form of θ±SD.

[0061] Dynamic Friction Coefficient Test: The test objects are the outer surfaces of strip-shaped or ring-shaped plastic parts prepared using Examples 1-4 and Comparative Examples 1-13, paired with standard steel or rubber mating parts. Test Objective: To determine the effect of fluorination treatment on the dynamic friction coefficient and verify the friction reduction mode and its process boundary. Test Principle: Under constant normal load and sliding speed, the dynamic friction coefficient is obtained by measuring the ratio of frictional force to normal force. Experimental Method: Using a reciprocating friction and wear testing machine, under dry friction conditions of 23℃, relative humidity (50±5)%, the sample is fixed on a platform with a cylindrical stainless steel block on top. The normal load is 5 N, the sliding speed is 50 mm / s, and the stroke is 10 mm. After stable sliding, the friction force curve is recorded, and the average value in the steady-state region is calculated. Standard Basis: Refer to ASTM D1894 or GB / T 10006. Key Parameters: Normal load, sliding speed, stroke, number of cycles. Data processing: Three samples were tested for each type of sample, and three replicates were taken for each sample. The average coefficient of kinetic friction and standard deviation were calculated, and the results were given in μ±SD.

[0062] Oxygen permeability testing was conducted on flat samples prepared according to Examples 1-4 and Comparative Examples 1-13, or samples with the same surface treatment applied to flat ABS / SAN / NBR substrates. The purpose of the test was to evaluate the improvement in oxygen barrier properties achieved by the nitrogen-fluorination gradient skin and the influence of different process parameters on barrier performance. The principle of the test was to determine the oxygen permeability per unit time and per unit area of ​​the sample under constant temperature and humidity conditions using coulometric or electrochemical methods, and to calculate the percentage reduction in permeability compared to the untreated substrate. The experimental method involved using an oxygen permeability meter at (23±2)℃ and relative humidity (0% or 50%), installing the samples according to the equipment instructions, ensuring the same effective test area, and recording the permeability rate during the stable phase after pre-equilibration. Key parameters included test temperature, humidity, test area, film thickness, and driving force (oxygen partial pressure). Data processing involved testing three samples of each type, taking the average permeability, and comparing it with the untreated sample on the same substrate to calculate the percentage reduction in oxygen permeability and the standard deviation.

[0063] XPS Surface and Depth Profiling: Test Subjects: Surfaces of fluorinated plastic parts from Examples 1-4 and at least 6 typical comparative examples. Test Objective: To obtain the F / C and N / C atomic ratios within depths of 0-10 nm and 10-30 nm, and to calculate these ratios to verify constraints regarding gradient skin and uniformity. Test Principle: X-ray photoelectron spectroscopy was used to determine the peak areas of different elements on the surface, combined with a sensitivity factor to calculate the atomic ratios, and depth profiling was achieved through ion sputtering. Experimental Method: A monochromatic Al Kα light source was used, with a vacuum degree ≤5×10⁻⁻⁻⁻⁴. 7Tests were conducted under Pa conditions. First, full-spectrum and high-resolution C1s, F1s, and N1s spectra were acquired on the surface. Then, stepwise etching was performed at a moderate Ar⁺ sputtering rate to obtain the spectra and atomic ratios of the 0-10 nm and 10-30 nm layers. Standards followed: ISO 18118 or similar XPS analysis standards. Key parameters: light source, voltage, analysis zone diameter, sputtering rate, and time. Data processing: Peak area was integrated using software to calculate F / C, N / C, and their ratios. Average values ​​and relative standard deviations were calculated for different embodiments and locations.

[0064] Dimensional stability and three-dimensional uniformity testing: Test objects include three-dimensional structural parts from Examples 1-4 and some comparative examples, including ribbed, concave, and coated areas. Test objective: To evaluate whether the dimensional change of the parts before and after nitriding-fluorination treatment does not exceed 0.1%, and to verify whether the F / C and N / C atomic ratio deviations in the inner cavity, groove, and coated area do not exceed 10%. Test principle: Key dimensional changes are obtained using a high-precision coordinate measuring machine (CMM), and the atomic ratio deviations in different areas are statistically analyzed using multi-point XPS measurements. Experimental method: Typical three-dimensional parts are selected, and at least 10 key dimensions such as length and aperture are measured using a CMM (measurement uncertainty ≤ 3 μm) before and after treatment. Simultaneously, samples are taken from the outer surface, inner cavity, groove, and coated area for XPS testing. Standard basis: Dimensional measurement refers to ISO 10360 or GB / T 1958; XPS refers to Experiment 4. Key parameters: Measurement temperature, clamping method, number of measurement points, and statistical method. Data processing: Calculate the relative percentage change of each dimension and the relative deviations of F / C and N / C in different regions, and give the maximum values.

[0065] Thermal cycling and long-term stability testing was conducted on samples from Examples 1-4 prepared using adhesive and friction-reducing processes. The purpose of the test was to verify the stability of F / C, N / C, static water contact angle, dynamic friction coefficient, and oxygen permeability under continuous operation or storage for at least 12 months within an ambient temperature range of -30 to 80°C. The test principle simulated long-term service by accelerating thermal cycling and isothermal aging, periodically retesting key surface parameters and observing their trends. The experimental method involved placing samples in a programmable thermostat and cycling at -30°C for 2 hours, then raising the temperature to 80°C and holding for 2 hours, with 1-2 cycles per day. The total number of cycles was calculated based on a 12-month equivalent time. An isothermal storage group was also included as a control. Contact angle, friction coefficient, XPS, and oxygen permeability were tested at 0, 1, 3, 6, and 12 months. Key parameters included cycling temperature, heating / cooling rate, holding time, and total number of cycles. Data processing involved calculating the retention rate and standard deviation for each parameter to determine if they were within the allowable fluctuation range.

[0066] Figure 1To investigate the effect of the fluorine gas integral in step S3 on the reduction rate of static water contact angle and oxygen permeability, the parameters were fixed with the ABS injection molded part as the substrate. Step S1 involved evacuating to 20 Pa and then refilling with nitrogen to 30 kPa twice. Step S2 was performed at 30 kPa and 25°C with an ammonia gas integral of 0.18 vol%, an ammoniation time of 75 s, and a mixed gas flow rate of 2.0 slm. Step S3 was performed at 30 kPa and 25°C with a fluorination time of 75 s and a mixed gas flow rate of 2.0 slm. Step S4 was not performed. Step S5 involved nitrogen rinsing for 60 s, a dew point not exceeding -40°C, nitrogen purity of 99.999%, and aging at room temperature for 4 h. The parameter was varied by increasing the fluorine gas integral in step S3 from 0.30 vol% to 2.50 vol%. The results showed that the fluorine gas integral increased from 0.30 vol% to 1.20 vol%. At vol%, the contact angle smoothly increases from 58° to 64° and the oxygen permeability reduction rate increases from 20% to 32%. Around 1.20 vol%, the two indicators form a better combination. Continuing to increase to 2.00–2.50 vol%, although the contact angle further increases to 80–96°, the oxygen permeability reduction rate decreases to 21–29%. This indicates that moderate fluorination strength is beneficial for obtaining both a wettable interface and effective barrier properties. Too low or too high a strength will weaken the overall performance.

[0067] Figure 2 To investigate the effect of the ammonia gas fraction in step S2 on the static water contact angle and the reduction rate of oxygen permeability, the parameters were fixed with the ABS injection molded part as the substrate. Step S1 involved evacuating to 20 Pa and then refilling with nitrogen to 30 kPa twice. Step S3 involved a fluorine gas fraction of 1.20 vol%, a fluorination time of 75 s, and a mixed gas flow rate of 2.0 slm at 30 kPa and 25°C. Step S4 was not performed. Step S5 involved nitrogen rinsing for 60 s, a dew point not exceeding -40°C, nitrogen purity of 99.999%, and aging at room temperature for 4 h. The parameters were varied by increasing the ammonia gas fraction in step S2 from 0.03 vol% to 0.40 vol%. The results showed that the contact angle was high and the oxygen permeability reduction rate was only about 20–25% when the ammonia gas fraction was between 0.03 and 0.05 vol%, indicating insufficient surface nitrogen activation. When the ammonia gas fraction increased to 0.15–0.20 vol%, the effect was mitigated. At vol%, the contact angle stabilizes at approximately 60–64°, a range favorable for coating and adhesion, while the oxygen permeability reduction rate reaches a relatively high level of 31–33%, forming a performance peak around 0.20 vol%. However, when the contact angle is further increased to 0.30–0.40 vol%, it drops to 52–58° and the parameter adjustment margin narrows, requiring higher process control. This indicates that a moderate ammonia concentration, especially in the 0.15–0.20 vol% range, is beneficial for achieving a balance between polarity introduction and interfacial stability.

[0068] Figure 3To investigate the effect of fluorination time in step S3 on the reduction rate of static water contact angle and oxygen permeability, the parameters were fixed with the ABS injection molded part as the substrate. Step S1 involved evacuating to 20 kPa and then refilling with nitrogen to 30 kPa twice. Step S2 was performed at 30 kPa and 25°C with an ammonia gas fraction of 0.18 vol%, an ammoniaification time of 75 s, and a mixed gas flow rate of 2.0 slm. Step S3 was performed at 30 kPa and 25°C with a fluorine gas fraction of 1.20 vol% and a mixed gas flow rate of 2.0 slm. Step S4 was not performed. Step S5 involved nitrogen rinsing for 60 s, a dew point not exceeding -40°C, nitrogen purity of 99.999%, and aging at room temperature for 4 h. The parameter was changed by extending the fluorination time in step S3 from 40 s to 150 s. The results showed that within the range of 40–50 s... At 60–75 s, the oxygen permeability reduction rate was only 20–25%, corresponding to a contact angle of about 58–60°. Insufficient fluorination limited surface densification. When the fluorination time was increased to 60–75 s, the oxygen permeability reduction rate increased to 28–32% and the contact angle stabilized at 62–64°. Around 75 s, it showed a synergistic advantage of barrier and wetting. However, when the fluorination time was further extended to 90–150 s, although the contact angle increased to 72–90°, the oxygen permeability reduction rate dropped back to 23–30%. At the same time, the interface became more hydrophobic, which was not conducive to subsequent coating or bonding treatment. This trend indicates that a medium fluorination time can form a reasonable trade-off between density and surface energy, thereby supporting the reasonable setting of the process window.

[0069] Figure 4 This is a scatter plot of the static water contact angle and dynamic friction coefficient of the nitrogen-fluorinated gradient skin sample in Example 1 of the present invention. The fixed parameters are: substrate ABS (acrylonitrile 22%, butadiene 16%, styrene 62%), total treatment pressure 30 kPa, temperature 25°C, step S2 ammoniation volume fraction 0.18% and time 75 s, step S3 fluorination volume fraction 1.2% and time 75 s, step S4 not performed, step S5 nitrogen purging for 60 s with dew point ≤−40°C, aging ≥2 h; surface chemical anchor points are F / C (0–10 nm) = 0.32, N / C (10–30 nm) = 0.32, and N / C (10–30 nm) = 0.32. nm)=0.040, ratio N / C(10–30) / F / C(0–10)=0.125; the figure simultaneously presents data points for the bonding mode and the friction reduction mode for comparison. Among them, Example 1 belongs to the bonding mode and its data is θ=64°, μ=0.28, which is located in the bonding mode range (contact angle 55–75°, dynamic friction coefficient ≤0.35). The results show that the wettability and interfacial shear response can be synergistically controlled by the depth gradient of the outer fluorine-rich layer and the nitrogen-containing sublayer. The bonding mode achieves moderate hydrophilicity and stable friction, while the control group shows the partition characteristics of low surface energy and low friction, thus verifying the effectiveness and adjustability of the surface gradient design.

[0070] Figure 5The F / C multi-location box plot (outer surface, inner cavity, groove, and coating area) of Example 1 of this invention is shown. Fixed parameters include ABS matrix, surface sampling depth 0–10 nm, sample size 50 mm × 50 mm × 2.0 mm (plate-type sample, with four locations: outer surface, inner cavity, groove, and coating area), sample size N=200 (50 samples per location), batch target mean F / C=0.32, and statistical methods using box plots Q1–Q3 and 1.5×IQR. The variable parameter is the location category (outer surface, inner cavity, groove, and coating area). Results show that the intra-batch RSD (F / C) is 6.5%, the relative deviation at each location is ≤8%, and the F / C is concentrated at multiple sites without any outliers, indicating that the surface fluorine content maintains good uniformity under complex geometry.

[0071] Figure 6 The N / C multi-location box plot (outer surface, inner cavity, groove, and coating area) of Example 1 of the present invention is shown below. The fixed parameters are: ABS substrate, near-surface sampling depth of 10–30 nm, and sample size of 50 mm × 50 mm × 2.0 mm (compared to...). Figure 1 The samples were taken from the same batch and size, divided into points at the same location; the sample size was N=200 (50 pieces per location); the batch target mean was N / C=0.040; the statistical methods were box plots Q1–Q3 and 1.5×IQR; the variation parameter was the location category (outer surface, inner cavity, groove, and covered area). The results showed that the intra-batch RSD(N / C) was 7.2%, the relative deviation of each location was ≤10%, the inner cavity was slightly higher and the groove was slightly lower, but the overall distribution was compact, indicating that the nitrogen content in the near-surface layer was consistent across multiple sites.

[0072] Figure 7 The dimensional change (%) of Example 1 of this invention is presented as a bar chart by location (outer surface, inner cavity, groove, and covered area). Fixed parameters include: statistical caliber of linear relative dimensional change on a three-axis coordinate system; sample size of 50 mm × 50 mm × 2.0 mm (same batch, same size, measured along the X / Y / Z directions and expressed as relative change %); sample size N = 200 (50 pieces per location); evaluation limit of maximum dimensional change < 0.1%; and same batch and measurement conditions. The change parameter is the location category (outer surface, inner cavity, groove, and covered area). The results show that the average dimensional change across the four locations is approximately 0.03%, with a maximum value less than 0.1%. The differences between locations are minimal, indicating that surface and near-surface modification did not cause macroscopic dimensional instability, and dimensional consistency and process feasibility are guaranteed.

[0073] Figure 8This is an XPS depth profile diagram of the embodiments and comparative examples of the present invention. The fixed parameters were: ambient temperature 23±2°C, relative humidity 50±5%, and sample pretreatment for 24 h; the XPS used a monochromatic Al Kα source (hν=1486.6 eV), a pass energy of 20 eV, a beam diameter of 400 μm, a sampling interval of 1 nm, sputtering ions of Ar+ 1 keV, and a sputtering rate of 1.0 nm·min⁻¹ calibrated according to SiO2 and used for depth axis conversion; the peak fitting used Shirley background + GL(30) line type, and the elemental normalization was based on carbon to obtain F / C and N / C. All sample points were taken as the mean ± standard uncertainty of three repetitions. The coordinates were set to display F / C and N / C on the left axis and (N / C) / (F / C) ratio on the right axis, with a depth range of 0–30 nm. The variable parameters are different formulations and process conditions: Example 1 (mass production state), Comparative Example 1 (ammonia 0.03 vol%), Comparative Example 4 (fluorine 2.50 vol%), and Comparative Example 12 (dew point -20℃, with intra-batch / intra-area fluctuation represented by a semi-transparent band). Curves are plotted and labeled in the figure as follows: Example 1·F / C, Example 1·N / C, Example 1·ratio; Comparative Example 1·F / C, Comparative Example 1·N / C, Comparative Example 1·ratio; Comparative Example 4·F / C, Comparative Example 4·N / C, Comparative Example 4·ratio; Comparative Example 12·F / C (band = fluctuation), Comparative Example 12·N / C (band = fluctuation), Comparative Example 12·ratio (band = fluctuation). For ease of reproduction and dissemination, options for exporting to high-resolution PNG and CSV are provided below the figure. Key Results: In Example 1, the F / C ratio was approximately 0.32 ± 0.02 and the N / C ratio was approximately 0.040 ± 0.003 in the 0–10 nm range of the surface / near surface, with the ratio remaining stable at 0.12–0.14 and changing gradually with depth, reflecting a uniform low surface energy and moderate nitrogen content in mass production. In Comparative Example 1, due to excessively low ammonia content, the N / C ratio was approximately 0.018 ± 0.002 and the ratio was approximately 0.05–0.06, resulting in insufficient effective sites. In Comparative Example 4, due to high fluorine content, the surface F / C ratio was approximately 0.50 ± 0.03, but the N / C ratio was low, with a ratio of approximately 0.04–0.06, indicating strong hydrophobicity but shielded functional sites. In Comparative Example 12, significant fluctuations were observed at a dew point of -20°C, with both F / C and N / C fluctuating with depth, the bandwidth corresponding to ±1–2 standard deviations, and the ratio band oscillating between 0.08–0.13, indicating in-plane non-uniformity caused by the process. Overall conclusion: Example 1 achieves a synergistic stabilization region of F / C and N / C in the 0–30 nm range, with (N / C) / (F / C) maintained within a functionally effective but not excessively hydrophobic window. This is superior to the unilateral extreme conditions of excessively low ammonia and excessively high fluorine, and significantly superior to the non-uniform state caused by low dew point. This demonstrates that a more stable and predictable surface chemical gradient and performance output can be obtained by coordinating nitrogen and fluorine sources and the dry dew point.

[0074] Figure 9This is the high-resolution C 1s spectrum of the surface layer in Embodiment 1 of the present invention. Basic parameters: same as above. Figure 1 The spectral fitting components were C–C / C–H 284.8 eV, C–N≈285.9 eV, C–F≈288.5 eV, CF2≈291.0 eV, and CF3≈293.2 eV. Variable parameters: layer position (0–10 nm and 10–30 nm), with a target N / C ratio of 0.038 or 0.040 for the subsurface layer. Conclusions: The 0–10 nm layer has a high proportion of CFx (C–F / CF2 / CF3), while the 10–30 nm layer shows a decrease in CFx and a relative increase in C–N, with a slight increase in N / C from 0.038 to 0.040. This matches the surface layer F / C = 0.32, indicating that fluorinated segments are concentrated in the skin layer, and nitrogen-containing functional groups are enriched in the subsurface layer, forming a synergistic structure of a low-energy skin layer and an interacting subsurface layer.

[0075] Figure 10 This is the N 1s high-resolution spectrum of the surface layer in Embodiment 1 of the present invention. Basic parameters: same as above. Figure 1 The fitted peaks include –C≡N≈399.1 eV and –NH / nitride≈400.2 eV. Variable parameters: layer position and N / C target values ​​of 0.038 or 0.040. Conclusions: The N 1s intensity in the subsurface layer is significantly higher than that in the surface layer, and the peak area increases proportionally as the N / C ratio increases from 0.038 to 0.040. The coexistence of the two components indicates that nitrile groups are retained and active nitrogen is introduced. When the surface layer F / C = 0.32 and the subsurface layer N / C = 0.040, the ratio N / C ÷ F / C = 0.125, which meets the requirement of maintaining low surface energy while providing polar sites.

[0076] Figure 11 This is the high-resolution F1s spectrum of the surface layer in Embodiment 1 of the present invention. Basic parameters: same as above. Figure 1 The main peak is located at approximately 688.5 eV. Variable parameters: layer position (0–10 nm and 10–30 nm). Conclusion: The 0–10 nm layer exhibits high F 1s intensity and stable peak shape, while the 10–30 nm layer shows significant attenuation with a monotonically decreasing trend in depth. Combined with the CFx ratio in C 1s, this confirms the effective construction of the epidermal fluorinated layer. The corresponding macroscopic properties are a static water contact angle of 64°, a dynamic friction coefficient of 0.28, and a 32% decrease in OTR, consistent with low surface energy and increased density.

[0077] As shown in Table 1, Examples 1-4 are generally superior to Comparative Examples 1-13 in key performance aspects such as static water contact angle, dynamic friction coefficient, oxygen permeability reduction rate, and surface F / C and N / C atomic ratios. Examples 1 and 3 fall within the 55-75° bonding window, with (F / C, N / C) combinations of (0.32, 0.040) and (0.24, 0.054) respectively, ensuring sufficient surface polarity while avoiding excessive hydrophilicity. Examples 2 and 4 achieve high contact angles and low dynamic friction coefficients around 95-110°. In particular, Example 2 maintains μ=0.23 even at R=40%, demonstrating the synergistic advantage of friction reduction and barrier properties. While some samples in the comparative examples are close to certain examples in a single indicator—for example, Comparative Example 9 is close to Example 1 in barrier performance, and Comparative Example 4 is close in contact angle—these examples demonstrate the superior performance of the comparative examples. Similar to Example 4, but accompanied by F / C or N / C exceeding the scope of the claims, (N / C) / (F / C) deviating from the lower limit or the coefficient of dynamic friction, and deterioration of barrier performance, it failed to form an optimal combination of comprehensive performance. In addition, most comparative examples had an oxygen permeability reduction rate of less than 25-30%, or in the F / C<0.20, F / C>0.45 and N / C>0.060 regions, proving that the process window and gradient skin parameters defined in the embodiments of the present invention play a key role in achieving a balance between low friction / high adhesion and barrier performance.

[0078] Table 1 Summary of performance of examples and comparative examples Note: Performance index 1 is the static water contact angle θ (°), performance index 2 is the dynamic friction coefficient μ, performance index 3 is the oxygen permeability reduction rate R (%), performance index 4 is F / C (0-10 nm), and performance index 5 is N / C (10-30 nm). All are given in the form of average value ± standard deviation, and n≥3.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A fluorinated surface-modified plastic part, characterized in that: The substrate is an acrylonitrile-butadiene-styrene copolymer, a styrene-acrylonitrile copolymer, nitrile rubber, or hydrogenated nitrile rubber; The surface of the plastic part includes a nitrogen-fluorinated gradient skin; The F / C atomic ratio within a depth range of 0-10 nm is 0.20-0.45; The N / C atomic ratio within a depth range of 10-30 nm is 0.015-0.060; The ratio of the N / C atomic ratio in the depth range of 10-30 nm to the F / C atomic ratio in the depth range of 0-10 nm is not less than 0.10; The static water contact angle is 55-75° or 95-110°; The coefficient of kinetic friction is not greater than 0.35; Compared to the untreated substrate, oxygen permeability is reduced by no less than 25%; The nitrogen-fluorinated gradient skin is a surface modification layer, and the dimensional change of the part before and after treatment does not exceed 0.1%.

2. The fluorinated surface-modified plastic part as described in claim 1, characterized in that, When used for coating or bonding, the static water contact angle is 55-75°, and the ratio of the N / C atomic ratio in the depth range of 10-30 nm to the F / C atomic ratio in the depth range of 0-10 nm is 0.12-0.

40. When used for friction reduction or anti-sticking, the static water contact angle is 95-110° and the dynamic friction coefficient is not greater than 0.

30.

3. The fluorinated surface-modified plastic part as described in claim 1, characterized in that, The intra-batch relative standard deviations of the F / C atomic ratio and N / C atomic ratio of parts in the same batch do not exceed 10%; The plastic part has a three-dimensional structure with ribs or cavities, and the deviation of the F / C atomic ratio and N / C atomic ratio of the nitrogen-fluorinated gradient skin in the inner cavity, groove, covering area and outer surface does not exceed 10%.

4. A method for preparing a fluorinated surface-modified plastic part as described in any one of claims 1 to 3, characterized in that... This includes the following steps: S1. Replacement and Pretreatment: Place the plastic part to be treated in the treatment chamber, then evacuate the treatment chamber to a pressure not exceeding 30 Pa, and then refill it with nitrogen to a pressure of 10-60 kPa. Repeat the vacuuming-refilling process 1-3 times. S2, Ammoniation Activation: Introduce ammonia gas with a volume fraction of 0.05-0.30%, at a temperature of 20-35℃, for a time of 30-120 s; S3, Fluorinated Dense: A mixture of fluorine and nitrogen with a volume fraction of 0.5-2.0% is introduced in a pulsed or continuous manner for a duration of 30-180 seconds; S4, Oxyfluorination Anode Adjustment: Introduce oxygen with a volume fraction of 0.02-0.20% for 5-60 seconds; S5. Inert gas flushing and aging: After flushing with inert gas, the aging time shall not be less than 2 hours.

5. The method for treating fluorinated surface-modified plastic parts as described in claim 4, characterized in that, The mixture of fluorine and nitrogen is configured using a parallel mass flow controller, with the fluorine integral set at 0.5-2.0%. Ammonia is introduced only in step S2 via a branch circuit at a volume fraction of 0.05-0.30%. The dew point of the entire flow path is no higher than -40℃, and the system pressure is 10-60 kPa. The equivalent residence time in the mixing section is not less than 0.5 s; Steps S2 and S3 are performed for 1-2 cycles using a pulse sequence of ammoniation for 60-90 s followed by fluorination for 60-120 s, with no fluorine gas introduced during step S2 and no ammonia gas introduced during step S3. The purity of nitrogen gas is not less than 99.999%.

6. The method for treating fluorinated surface-modified plastic parts as described in claim 4, characterized in that, Step S4 is performed after step S3; After completely stopping the fluorine gas supply and purging with inert gas for no less than 30 seconds, oxygen with a volume fraction of 0.02-0.20% is introduced for 5-60 seconds to achieve fine-tuning of surface polarity; A flow field organization method of zoned air intake and recirculation is adopted to improve the processing uniformity of the cavity and shielded area; The exhaust gas is treated by a calcium carbonate absorption unit and a sodium hydroxide alkaline scrubbing unit to remove the byproduct hydrogen fluoride.

7. The method for treating fluorinated surface-modified plastic parts as described in claim 4, characterized in that, The refill pressure after vacuuming in step S1 is 10-40 kPa; The processing temperature for steps S2 to S4 is 20-35℃, and the processing pressure is 10-40 kPa. The equivalent volumetric flow rate of the mixed gas in steps S2 to S4 is 0.5-5.0 standard liters per minute. Alternatively, the linear velocity, calculated based on the effective cross-sectional area of ​​the processing cavity, is 0.05-0.50 m / s.

8. The method for treating fluorinated surface-modified plastic parts as described in claim 4, characterized in that, By programmably setting the total time for steps S2 and S3, and whether step S4 is performed, one of the following two working modes can be achieved: Bonding mode: The total time for step S2 is 60-90 s, the total time for step S3 is 60-90 s, and step S4 is not performed, so that the static water contact angle of the obtained part is 55-75°. Friction reduction mode: The total time for step S2 is 60-90 s, the total time for step S3 is 90-120 s, and step S4 is carried out with an oxygen volume fraction of 0.02-0.10 vol% for 5-30 s, so that the static water contact angle of the obtained part is 95-110° and the dynamic friction coefficient is not higher than 0.

30.

9. The application of the fluorinated surface modified plastic parts according to any one of claims 1-3 or the fluorinated surface modified plastic parts obtained by the treatment method according to any one of claims 4-8 in coating, printing or bonding substrates, or in low-friction assemblies or seals, or in barrier enhancement of packaging or fluid components.

10. The application according to claim 9, characterized in that... Used as a substrate or sealing strip for automotive interior and exterior coatings, meeting one of the bonding or friction reduction modes, and maintaining stable surface F / C atomic ratio, N / C atomic ratio, static water contact angle, dynamic friction coefficient and oxygen permeability during continuous operation or storage for no less than 12 months within an ambient temperature range of -30 to 80 °C.

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