A method of plasma processing a steering wheel airbag cover

Abstract

The application discloses a kind of steering wheel air bag cover plasma processing method, it is related to the technical field of automotive interior product, including the following steps: step one, the skeleton of the steering wheel air bag cover is plasma primary processing, for surface cleaning;Wherein, the skeleton of the steering wheel air bag cover is plasma primary processing before needing to carry out pretreatment, the pretreatment is that the skeleton of the steering wheel air bag cover is baked;Step two, the skeleton of the steering wheel air bag cover is plasma secondary processing, for surface activation and roughness processing.The application improves the surface energy of TPO material steering wheel air bag cover by the plasma processing mode of secondary processing, guarantees skin covering peel force, guarantees the accuracy of air bag point explosion unfolding.

Description

Technical Field

[0001] This invention relates to the field of automotive interior product technology, and more specifically, to a plasma treatment method for a steering wheel airbag cover. Background Technology

[0002] Currently, to enhance the overall premium feel and comfort of automotive interiors, steering wheel airbag covers typically consist of a layer of soft outer material over a thermoplastic polyolefin elastomer (TPO). To ensure the airbag cover's burst requirements, precise tear lines are designed on the frame, and the outer material is weakened at corresponding locations. Furthermore, the tear seams between the outer material and the base material must be precisely aligned during the covering process. This ensures that when the airbag deploys, the entire cover opens neatly and smoothly along the pre-set tear seams, like "petals," guaranteeing driver safety. This requires not only extremely high positioning accuracy but also very strict bonding strength between the outer material and the frame.

[0003] This necessitates fluorination of the steering wheel airbag cover. The core purpose is to improve coating adhesion through chemical modification, preventing the coating from peeling off and forming dangerous fragments when the airbag deploys. It also optimizes the spraying process and ensures long-term durability. This process is an indispensable part of automotive passive safety systems and is directly related to the safety of drivers and passengers.

[0004] However, fluorination requires the use of highly toxic fluorine gas, complex exhaust gas treatment, and generates hazardous waste, resulting in poor environmental performance. It also requires corrosion-resistant vacuum reactors and complex safety and exhaust gas treatment systems, leading to high equipment investment and operating costs.

[0005] Based on the above problems, there is an urgent need to develop new processing methods for steering wheel airbag covers that can replace fluorination treatment. Summary of the Invention

[0006] The purpose of this invention is to design and develop a plasma treatment method for steering wheel airbag covers. By combining pretreatment with secondary plasma treatment, safety is improved while increasing the surface energy of the steering wheel airbag cover, ensuring the peeling force of the skin coating.

[0007] The technical solution provided by this invention is as follows: A plasma treatment method for a steering wheel airbag cover includes the following steps: Step 1: Perform a plasma treatment on the frame of the steering wheel airbag cover for surface cleaning. Step 2: Perform a secondary plasma treatment on the frame of the steering wheel airbag cover for surface activation and roughness treatment.

[0008] Preferably, the plasma primary treatment specifically includes: The steering wheel airbag cover is placed in the cavity of the plasma processing equipment, and compressed air is introduced into the cavity of the plasma processing equipment.

[0009] Preferably, the compressed air supply power is 15-20 kW, the compressed air intake flow rate is less than 300 sscm, and the compressed air supply time is 10-20 s.

[0010] Preferably, the plasma secondary treatment specifically includes: Oxygen is introduced into the cavity of the plasma treatment equipment.

[0011] Preferably, the oxygen supply power is 6-10 kW, the oxygen inlet flow rate is above 4000 sscm, and the oxygen supply time is 60-100 s.

[0012] Preferably, the plasma secondary treatment specifically includes: Argon gas is introduced into the cavity of the plasma processing equipment, followed by oxygen gas.

[0013] Preferably, the power of the argon and oxygen inlet is 5-8 kW, the inlet flow rate of the argon and oxygen is above 4000 sscm, the argon inlet time is 10 s, and the total inlet time of the argon and oxygen is 60-100 s.

[0014] Preferably, the step before step one includes: The frame of the steering wheel airbag cover is pre-processed; The preprocessing involves baking the frame of the steering wheel airbag cover.

[0015] Preferably, the baking temperature is 60℃~100℃ and the baking time is 4~48h.

[0016] Preferably, the frame material of the steering wheel airbag cover is TPO.

[0017] The beneficial effects of this invention are as follows: This invention presents a plasma treatment method for steering wheel airbag covers. The method employs a secondary plasma treatment to enhance the surface energy of the TPO material steering wheel airbag cover, ensuring the peel force of the skin coating, guaranteeing the accuracy of airbag deployment, and providing good adhesion to the skin. The treatment process is also more environmentally friendly, significantly reducing costs and improving production efficiency and applicability compared to fluorination treatment. Attached Figure Description

[0018] Figure 1 This is a top view schematic diagram of the assembly structure of the positive electrode plate and the negative electrode plate according to the present invention; Figure 2This is a bottom view of the assembly structure of the positive electrode plate and the negative electrode plate according to the present invention; Figure 3 This is a schematic diagram of the sample assembly structure described in this invention. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0020] This invention provides a plasma treatment method for a steering wheel airbag cover, which is performed using a plasma treatment device, such as... Figures 1-3 As shown, it includes: The cavity (not shown in the figure), the positive electrode plate 110, the negative electrode plate 120, and the sample support 130; The positive electrode plate 110 and the negative electrode plate 120 are arranged in parallel and at intervals in the cavity, that is, the positive electrode plate 110 is arranged parallel above and below the negative electrode plate 120. The sample support 130 is evenly distributed on all the electrode plates except the one at the top, and is used to support the sample 140. That is, the sample support 130 ensures that the sample 140 is between the positive electrode plate 110 and the negative electrode plate 120.

[0021] In this embodiment, the number of the positive electrode plate 110 and the negative electrode plate 120 is set according to the cavity and requirements.

[0022] The front panel of the cavity is evenly arranged with air inlets, and the rear panel is evenly arranged with exhaust outlets. A baffle is placed at the exhaust outlet position to ensure that the gas can evenly fill the entire cavity and then flow from the baffle to the exhaust outlet and be extracted, providing sufficient reactants for plasma cleaning.

[0023] In this embodiment, the spacing between each layer of electrode plates is consistent.

[0024] In this embodiment, when the sample 140 is placed on the sample holder 130, its top outer side is a skin-covered area, meaning that the area to be processed can come into contact with plasma.

[0025] In this embodiment, Langmuir probes are used to measure plasma density and electron temperature at the four corners and the center of the cavity to adjust the process and ensure uniformity and processing effect.

[0026] The plasma-treated steering wheel airbag cover product of this invention differs in its fundamental principle from existing fluorination treatment. Fluorination treatment uses fluorine gas (F2) to react with the CH bonds on the plastic surface to generate stable CF bonds, permanently altering the surface's chemical composition. However, plasma treatment cleans and alters the surface roughness through the physical impact of plasma. Simultaneously, oxygen free radicals and hydroxyl groups in the plasma combine with these broken bonds, introducing a large number of oxygen-containing polar functional groups onto the surface. Overall, this is still considered physical activation, and the activation effect decays over time. Therefore, the plasma treatment process needs improvement, specifically including the following steps: Step 1: After pre-treating the skeleton of the steering wheel airbag cover product, a plasma treatment is performed, which involves cleaning the surface of the steering wheel airbag cover product with high-power and high-flow-rate compressed air. Because the frame of the steering wheel airbag cover is made of TPO material, which contains many small molecules of additives, the current fluorination treatment can permanently change the surface chemical composition, which is equivalent to forming a dense and uniform barrier layer on the surface, preventing the internal small molecules from migrating to the surface. However, the plasma treatment process only physically cleans and activates the surface layer. Even if the interface is good in the initial stage of bonding, the small molecule additives (such as lubricants, plasticizers, and antioxidants) that continuously migrate from inside TPO will gradually penetrate and accumulate at the interface between the adhesive and TPO. These low surface energy oily substances will act like "separating agents" to physically block the intermolecular forces (van der Waals forces, hydrogen bonds, etc.) between the adhesive and the TPO substrate, causing the adhesion to slowly decrease. Therefore, in order to prevent failure due to the migration of small molecules, the frame of the steering wheel airbag cover needs to be pretreated. Specifically, the preprocessing includes: The frame of the steering wheel airbag cover product is baked at a temperature of 60℃~100℃ for 4~48 hours to accelerate the migration of small molecules from the interior to the surface and achieve a relatively balanced state. Then, plasma is used to remove low surface energy substances to ensure the subsequent bonding effect.

[0027] The plasma primary treatment specifically includes: Compressed air is introduced into the cavity of the plasma treatment equipment. The power of the compressed air is 15-20kw, the air intake flow rate is less than 300sscm, and the introduction time is 10-20s. High-power, high-volume, and short-time compressed air is used to clean the product surface and remove organic contaminants, oil stains, and weak boundary layers.

[0028] Step 2: Perform a secondary treatment on the surface of the steering wheel airbag cover product using oxygen or a mixture of oxygen and argon, ensuring sufficient processing time for surface activation and roughening. This specifically includes: Argon gas is introduced into the cavity of the plasma treatment equipment, followed by oxygen gas. The power of both argon and oxygen gas is 5-8 kW, the inlet flow rate of argon and oxygen gas is above 4000 sscm, the argon gas introduction time is 10 s, and the total introduction time of argon and oxygen gas is 60-100 s.

[0029] In this embodiment, oxygen can also be directly introduced, with the oxygen intake flow rate remaining unchanged, the introduction power being 6-10 kW, and the oxygen intake time being 60-100 s.

[0030] To verify the performance of the plasma treatment method for the steering wheel airbag cover described in this invention, the following tests were conducted: Using a conventional one-time plasma treatment method, the dyne value of the treated substrate is >60. The skin is coated within 4 hours. After cooling, the peel force between the skin and the skeleton is 15-20N. After 24 hours of storage, the peel force of the sample is 5-8N, which does not meet the product technical requirements. The substrate treated by the method described in this invention has a dyne value >60. The skin is coated within 4 hours. After cooling, the peel force between the skin and the skeleton is >50N, and the skin is completely broken. The test results are consistent after 24 hours of storage. The samples stored for 1 month and after high and low temperature tests are also completely broken.

[0031] This is because existing coating substrates are all made of PP material, which only undergoes a single plasma treatment. However, because the content of small molecules in TPO material is much higher than that in PP material, conventional single plasma treatment methods cannot meet the product's technical requirements. Therefore, the method described in this invention not only ensures the initial effect after treatment, but also guarantees subsequent adhesion and stability, and the adhesion strength of the substrate fully meets the product's technical requirements.

[0032] This invention presents a plasma treatment method for steering wheel airbag covers. The method employs a secondary plasma treatment to enhance the surface energy of the TPO material steering wheel airbag cover, ensuring the peel force of the skin coating, guaranteeing the accuracy of airbag deployment, and providing good adhesion to the skin. The treatment process is more environmentally friendly, significantly reducing costs compared to fluorination treatment, and improving production efficiency and applicability.

[0033] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A plasma treatment method for a steering wheel airbag cover, characterized in that, Includes the following steps: Step 1: Perform a plasma treatment on the frame of the steering wheel airbag cover for surface cleaning. Step 2: Perform a secondary plasma treatment on the frame of the steering wheel airbag cover for surface activation and roughness treatment.

2. The plasma treatment method for the steering wheel airbag cover as described in claim 1, characterized in that, The plasma primary treatment specifically includes: The steering wheel airbag cover is placed in the cavity of the plasma processing equipment, and compressed air is introduced into the cavity of the plasma processing equipment.

3. The plasma treatment method for the steering wheel airbag cover as described in claim 2, characterized in that, The compressed air supply power is 15-20 kW, the compressed air intake flow rate is less than 300 sscm, and the compressed air supply time is 10-20 s.

4. The plasma treatment method for the steering wheel airbag cover as described in claim 3, characterized in that, The plasma secondary treatment specifically includes: Oxygen is introduced into the cavity of the plasma treatment equipment.

5. The plasma treatment method for the steering wheel airbag cover as described in claim 4, characterized in that, The oxygen supply power is 6-10 kW, the oxygen inlet flow rate is above 4000 sscm, and the oxygen supply time is 60-100 s.

6. The plasma treatment method for the steering wheel airbag cover as described in claim 3, characterized in that, The plasma secondary treatment specifically includes: Argon gas is introduced into the cavity of the plasma processing equipment, followed by oxygen gas.

7. The plasma treatment method for the steering wheel airbag cover as described in claim 6, characterized in that, The power of each of the argon and oxygen gas is 5-8 kW, the inlet flow rate of the argon and oxygen gas is above 4000 sscm, the argon gas introduction time is 10 s, and the total introduction time of the argon and oxygen gas is 60-100 s.

8. The plasma treatment method for the steering wheel airbag cover as described in claim 5 or 7, characterized in that, Before step one, the following also applies: The frame of the steering wheel airbag cover is pre-processed; The preprocessing involves baking the frame of the steering wheel airbag cover.

9. The plasma treatment method for the steering wheel airbag cover as described in claim 8, characterized in that, The baking temperature is 60℃~100℃, and the baking time is 4~48h.

10. The plasma treatment method for the steering wheel airbag cover as described in claim 9, characterized in that, The frame material of the steering wheel airbag cover is TPO.

Images