A method for post-processing of a pet backsheet

Abstract

This invention relates to a post-treatment method for PET backing sheets, belonging to the field of backing sheet treatment technology, and includes the following steps: S1, hanging: suspending the molded PET long-fiber backing sheet on a hanger; S2, impregnation treatment: applying a treatment solution to the surface of the backing sheet; S3, pre-drying treatment: transferring the impregnated backing sheet to a pre-drying tank to remove moisture and form a preliminary film; S4, baking treatment: transferring the pre-dried backing sheet to a baking tank to allow the water- and oil-repellent agent to cross-link and cure on the backing sheet surface; S5, air cooling treatment: cooling the backing sheet to below 40°C; S6, unloading and inspection: packaging qualified products according to customer requirements, and isolating unqualified products. This PET backing sheet post-treatment method, through post-treatment with fluorinated acrylate or fluorine-free silicone agents, reduces the surface tension of the backing sheet, allowing the droplet contact angle to reach over 120°, or even exceeding 150°, achieving a lotus leaf effect, causing water droplets to automatically roll off and preventing liquid penetration.

Description

Technical Field

[0001] This invention relates to the field of bottom protector processing technology, specifically a post-processing method for PET bottom protectors. Background Technology

[0002] PET long-fiber underbody panels, wheel covers, battery boxes, and other products are widely used in new energy vehicles due to their advantages such as low density, high strength, excellent sound insulation and vibration reduction performance, and 100% recyclability. These products are mainly made of PET bicomponent continuous fiber nonwoven fabric through compression molding, which can reduce weight by 20%-30% compared to plastic parts. They are mainly used for protection against flying foreign objects, sound insulation and noise reduction, and maintaining chassis flatness.

[0003] However, currently, PET long-fiber bottom protectors are usually not surface-treated after molding and are directly installed in vehicles, resulting in generally poor water and oil repellency. During long-term use, especially in water or oily environments, the internal structure of the material is prone to loosening, aging, delamination, and deformation, with a service life of only 6-8 years, requiring frequent replacement and increasing usage costs and maintenance burden.

[0004] Therefore, there is an urgent need for a post-treatment method that can improve the water and oil repellency of PET long fiber backing boards in order to extend their service life. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a post-processing method for PET bottom protectors, which has advantages such as excellent water and oil repellency and longer service life, solving the problems of poor water and oil repellency, easy aging and delamination, and short service life of existing bottom protectors.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A post-processing method for PET bottom protectors includes the following steps:

[0008] S1. Hanging: The molded PET long fiber bottom guard plate is suspended on the hanger and the hanger is fixed on the crossbeam of the automatic trolley. One or more sets of hangers are suspended on the crossbeam at the same time.

[0009] S2. Immersion treatment: The bottom protective plate on the crossbeam and the hanger is immersed in an immersion tank containing a water- and oil-repellent treatment solution by an automatic crane for immersion treatment, so that the treatment solution adheres to the surface of the bottom protective plate; the water- and oil-repellent treatment solution is an aqueous solution of fluorinated acrylate agent or an aqueous solution of fluorine-free organosilicon agent.

[0010] S3. Pre-drying treatment: Transfer the impregnated bottom cover to a pre-drying tank and pre-dry at a temperature of 60℃~110℃ for 1~10 minutes to remove moisture and form a preliminary film.

[0011] S4. Baking treatment: Transfer the pre-baked bottom cover to the baking tank and bake at 100℃~150℃ for 50 seconds to 8 minutes to allow the water and oil repellent agent to cross-link and cure on the surface of the bottom cover.

[0012] S5. Air cooling treatment: Transfer the baked bottom plate to the air cooling tank and use room temperature air or cooling air for forced air cooling to cool the bottom plate to below 40°C.

[0013] S6. Unloading and Inspection: Remove the cooled bottom guard plate from the hanger and conduct a visual inspection, including checking for scratches, deformation, and damage on the surface. Qualified products are packaged according to customer requirements, and unqualified products are isolated.

[0014] Furthermore, the concentration of the fluorinated acrylate agent is 20-60 g / L, and the concentration of the fluorine-free organosilicon agent is 60-80 g / L.

[0015] Furthermore, the pre-drying temperature is 60-110℃, and the pre-drying time is 1-10 minutes.

[0016] Furthermore, the baking temperature is 100-150℃, and the baking time is 50 seconds to 8 minutes.

[0017] Furthermore, the impregnation, pre-drying, baking, and air-cooling processes are completed by an automated crane, with multiple sets of hangers suspended on the crane's crossbeam.

[0018] Furthermore, the PET long fiber underbody protection plate includes automotive PET long fiber underbody protection plates, wheel covers, or battery boxes.

[0019] Furthermore, the contact angle of the treated bottom guard plate surface is greater than 120°, preferably greater than 130°, and more preferably greater than 150°.

[0020] Furthermore, after the treated bottom guard plate is continuously soaked for 240 hours or more than 10 dry and wet cycles, its tensile strength, impact strength, and flexural strength retention rate is greater than 90%.

[0021] Furthermore, the automated line is equipped with multiple traveling machines operating in separate zones, and adjacent traveling machines are connected by a common channel to avoid collisions.

[0022] Furthermore, the visual inspection includes checking for scratches, deformation, and skin damage on the surface, and defective products are isolated.

[0023] Compared with the prior art, the present invention provides a post-processing method for PET bottom protectors, which has the following beneficial effects:

[0024] 1. The post-treatment method of this PET bottom protector reduces the surface tension of the bottom protector by using fluorinated acrylate or fluorine-free silicone agents. The droplet contact angle can reach more than 120°, or even more than 150°, to achieve the lotus leaf effect, so that water droplets roll off automatically and avoid liquid penetration.

[0025] 2. The post-treatment method for this PET bottom protector allows the bottom protector to retain more than 90% (containing fluorine) or 95% (without fluorine) of its mechanical properties (tensile, impact, and bending strength) after continuous immersion in water for 240 hours or more than 10 dry and wet cycles, which is much higher than the 80% of the untreated bottom protector, and improves its durability by 10%-20%.

[0026] 3. This PET bottom plate post-processing method can achieve both automated continuous production and manual operation, supports multi-carriage zone operation, has high production efficiency, and is suitable for large-scale industrial applications.

[0027] 4. The post-treatment method for this PET bottom cover provides a fluorine-free silicone solution, which meets environmental protection requirements while maintaining good water repellency. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of a post-processing method for a PET bottom cover according to the present invention. Detailed Implementation

[0029] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Materials and equipment preparation:

[0031] PET long fiber underbody protection plate: Made of PET bicomponent continuous fiber nonwoven fabric through molding, with dimensions of 800mm×600mm×3mm, used for automotive chassis protection.

[0032] Medicine:

[0033] Fluorinated acrylate emulsion (solid content 30%).

[0034] Fluorine-free silicone emulsion (40% solid content).

[0035] Equipment: An automated impregnation production line, including an upper hanging area, an impregnation tank (with constant temperature stirring), a pre-drying oven, a baking oven, an air-cooling tank, and an lower hanging area, controlled by one or more automatic overhead cranes. The crane beam can simultaneously suspend 10 sets of hangers, and each set of hangers can hold 6 bottom guard plates.

[0036] Example 1:

[0037] Please see Figure 1 The post-processing method for a PET bottom protector in this embodiment includes the following steps:

[0038] S1. Hanging: Manually hang the molded PET long fiber bottom guard plate onto the hanger, with a spacing of ≥50mm between each set of hangers to avoid mutual contact. The hanger is fixed to the crane crossbeam.

[0039] S2. Impregnation: Prepare a fluorinated acrylate agent in the impregnation tank at a concentration of 45 g / L (diluted with deionized water and stirred at room temperature for 15 minutes until homogeneous). The crane immerses the bottom guard plate in the solution for 3 minutes at a temperature of 25 ± 2℃.

[0040] S3. Pre-drying: The crane transfers the impregnated bottom protection plate to the pre-drying tank, sets the temperature to 90℃, and pre-dries for 6 minutes to remove moisture and initially solidify into a film.

[0041] S4. Baking: Transfer to a baking tank, bake at 130℃ for 4 minutes to allow the water and oil repellent to fully cross-link and cure.

[0042] S5. Air cooling: Transfer to the air cooling tank and force airflow at room temperature for 2 minutes to cool the product to below 40°C.

[0043] S6. Hanging and Inspection: Hang manually and visually inspect the surface for scratches, deformation, and damage under fluorescent light. Qualified products are packaged according to customer requirements.

[0044] Test results:

[0045] Contact angle: An optical contact angle meter (KRÜSS DSA100, Germany) was used. The water droplet volume was 5μL, and the test was conducted at room temperature. The average value of the five different locations on the surface was taken, and the contact angle was 142°.

[0046] Water resistance test: Following the method in Appendix B of "PET Continuous Fiber Automotive Underbody Panels" (T / CAAMTB 298-2025), the sample was completely immersed in deionized water (23±2℃) for 240 consecutive hours. After removal and surface drying, tensile strength, impact strength, and flexural strength were tested. The performance retention rates were: tensile strength 93%, impact strength 91%, and flexural strength 94%. The appearance showed no cracking, swelling, delamination, or powdering.

[0047] Example 2: (Fluoroacrylate, lower concentration)

[0048] Same as Example 1, except that the concentration of fluorinated acrylate is 25 g / L, the pre-drying temperature is 80℃ / 5 min, and the baking temperature is 120℃ / 6 min.

[0049] Test results: Contact angle 128°; Performance retention after water resistance test: tensile strength 89%, impact strength 88%, flexural strength 90%. Good appearance.

[0050] Example 3: (Fluorine-free organosilicon)

[0051] Same as Example 1, except that a fluorine-free organosilicon agent was used at a concentration of 70 g / L, the pre-baking temperature was 100°C / 4 min, and the baking temperature was 140°C / 3 min.

[0052] Test results: Contact angle 132°; Performance retention rate after water resistance test: tensile strength 96%, impact strength 95%, flexural strength 97%. No abnormalities in appearance.

[0053] Example 4: (Fluorine-free organosilicon, high concentration)

[0054] Same as Example 1, except that a high-concentration fluorine-free organosilicon agent with a concentration of 80 g / L was used, and the pre-drying was carried out at 110°C for 2 min, followed by baking at 150°C for 1.5 min.

[0055] Test results: Contact angle 138°; Performance retention: Tensile strength 97%, Impact strength 96%, Flexural strength 98%.

[0056] Comparative Example 1: (Unprocessed)

[0057] The molded PET long fiber bottom cover is used directly without any impregnation or drying treatment.

[0058] Test results: Contact angle 82°; After water resistance test, performance retention: tensile strength 81%, impact strength 79%, flexural strength 80%. Slight delamination and swelling appeared on the surface.

[0059] Comparative Example 2: (Dip only, no baking)

[0060] Same as in Example 1, but without baking after soaking, only air-drying at room temperature for 24 hours.

[0061] Test results: Contact angle 105°; After the water resistance test, the performance retention rate was: tensile strength 82%, impact strength 80%, and flexural strength 81%. Some of the agent flaked off from the surface, and the water repellency was significantly reduced.

[0062] The optimal range of process parameters and their impact on performance are summarized in Table 1.

[0063] Table 1

[0064] Drug type Fluoroacrylates Fluorine-free organosilicon Unprocessed Concentration (g / L) 20-60 60-80 - Pre-drying (°C / min) 60-110 / 1-10 60-110 / 1-10 - Baking (°C / min) 100-150 / 0.8-8 100-150 / 0.8-8 - Contact angle (°) 120-150 120-142 <90 Strength retention rate after 240h water immersion (%) 90-95 95-98 ≈80

[0065] Industrial application description:

[0066] This method is not only applicable to automotive underbody protection panels, but also to components requiring water and oil repellency, such as PET long-fiber wheel covers and battery box covers. The treated products can be used long-term in environments ranging from -40℃ to +80℃, and are resistant to common automotive liquids such as mud, de-icing agents, engine oil, and brake fluid. Their service life is extended from 6-8 years to over 10 years, significantly reducing replacement frequency and maintenance costs for users.

[0067] The beneficial effects of this invention are:

[0068] The post-treatment method for PET bottom protectors provided by this invention significantly improves the water and oil repellency of the bottom protectors, achieving a surface contact angle of over 120° and realizing the lotus leaf effect. After immersion or dry-humidity cycle tests, the mechanical properties retain over 90%, far exceeding those of untreated products. This effectively prevents aging, delamination, and structural deformation, increasing durability by 10%–20% and extending service life to over 10 years. This method is highly adaptable, can be automated, and provides an environmentally friendly, fluorine-free solution that meets industry standards.

[0069] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A post-processing method for PET bottom protectors, characterized in that, Includes the following steps: S1. Hanging: The molded PET long fiber bottom guard plate is suspended on the hanger and the hanger is fixed on the crossbeam of the automatic trolley. One or more sets of hangers are suspended on the crossbeam at the same time. S2. Immersion treatment: The bottom protective plate on the crossbeam and the hanger is immersed in an immersion tank containing a water- and oil-repellent treatment solution by an automatic crane for immersion treatment, so that the treatment solution adheres to the surface of the bottom protective plate; the water- and oil-repellent treatment solution is an aqueous solution of fluorinated acrylate agent or an aqueous solution of fluorine-free organosilicon agent. S3. Pre-drying treatment: Transfer the impregnated bottom cover to a pre-drying tank and pre-dry at a temperature of 60℃~110℃ for 1~10 minutes to remove moisture and form a preliminary film. S4. Baking treatment: Transfer the pre-baked bottom cover to the baking tank and bake at 100℃~150℃ for 50 seconds to 8 minutes to allow the water and oil repellent agent to cross-link and cure on the surface of the bottom cover. S5. Air cooling treatment: Transfer the baked bottom plate to the air cooling tank and use room temperature air or cooling air for forced air cooling to cool the bottom plate to below 40°C. S6. Unloading and Inspection: Remove the cooled bottom guard plate from the hanger and conduct a visual inspection, including checking for scratches, deformation, and damage on the surface. Qualified products are packaged according to customer requirements, and unqualified products are isolated.

2. The post-processing method for a PET bottom protector according to claim 1, characterized in that, The concentration of the fluorinated acrylate agent is 20-60 g / L, and the concentration of the fluorine-free organosilicon agent is 60-80 g / L.

3. The post-processing method for a PET bottom protector according to claim 1, characterized in that, The pre-drying temperature is 60-110℃, and the pre-drying time is 1-10 minutes.

4. The post-processing method for a PET bottom protector according to claim 1, characterized in that, The baking temperature is 100-150℃, and the baking time is 50 seconds to 8 minutes.

5. A post-processing method for a PET bottom protector according to claim 1, characterized in that, The impregnation, pre-drying, baking, and air-cooling processes are completed by an automated crane, with multiple sets of hangers suspended on the crane's crossbeam.

6. The post-processing method for a PET bottom protector according to claim 1, characterized in that, The PET long fiber underbody protection includes automotive PET long fiber underbody protection, wheel covers, or battery boxes.

7. A post-processing method for a PET bottom protector according to claim 1, characterized in that, The contact angle of the treated bottom guard plate surface is greater than 120°, preferably greater than 130°, and more preferably greater than 150°.

8. A post-processing method for a PET bottom protector according to claim 1, characterized in that, After treatment, the bottom protective plate retains more than 90% of its tensile strength, impact strength, and flexural strength after continuous immersion for 240 hours or more than 10 dry-wet cycles.

9. A post-processing method for a PET bottom protector according to claim 5, characterized in that, The automated line is equipped with multiple traveling machines operating in different zones, and adjacent traveling machines are connected by a common channel to avoid collisions.

10. A post-processing method for a PET bottom protector according to claim 1, characterized in that, The visual inspection includes checking for scratches, deformation, and skin damage on the surface, and defective products are isolated.

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