Method for depositing decorative film on surface of polymer through magnetron sputtering technology

Abstract

The invention relates to the technical field of automotive upholstery decoration, in particular to a method for depositing a decorative film on the surface of a polymer through a magnetron sputtering technology, which comprises the following steps: S1, pretreating and cleaning a polymer material; s2, performing magnetron sputtering of a Cr film on the surface of the polymer material; s3, after the Cr film in the step S2 is sputtered, a CrOx film is sputtered; the film prepared by the method disclosed by the invention not only meets the requirements of automotive upholstery on color decoration, but also meets the industrial standards in hardness and binding force. And the traditional electroplating technology which is high in cost, heavy in pollution and harmful to a human body can be replaced. Meanwhile, an important reference value is provided for the field of polymer metallization decoration.

Description

Technical Field

[0001] This invention relates to the field of automotive interior decoration technology, specifically to a method for depositing decorative thin films on polymer surfaces using magnetron sputtering technology. Background Technology

[0002] Polymers are widely used in construction, automotive, packaging, electronics, medical, and new energy fields due to their lightweight, corrosion resistance, and ease of molding. However, inherent defects such as low abrasion resistance, poor gloss, and unattractive appearance limit their applications. To overcome these defects, metal thin films can be deposited on polymer surfaces using specific processes, giving them the advantages of both polymers (lightweight and easy processing) and metals (hardness, gloss, and aesthetic appeal).

[0003] Currently, common methods for polymer metallization include physical vapor deposition (PVD), electroless plating, thermal spraying, and direct polymer-metal bonding. Among these, electroless plating is widely used in polymer metallization, but the wastewater, waste gas, and solid waste it generates pose threats to the environment and human health. Therefore, the European Union has enacted legislation to restrict the use of hexavalent chromium solutions. PVD, with its advantages of low deposition temperature, low cost, wide substrate adaptability, stable surface properties after modification, and zero emissions of waste gas and liquid, is the most promising method for polymer metallization.

[0004] Cr and its oxide coating systems have always attracted much attention in the field of decorative coatings, and their excellent color tunability and environmental stability have made them a research hotspot.

[0005] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0006] The purpose of this invention is to solve the problem that the inherent defects of polymers, such as low wear resistance, poor gloss, and unattractive appearance, limit their application, and to provide a method for depositing decorative thin films on polymer surfaces using magnetron sputtering technology.

[0007] To achieve the above objectives, this invention discloses a method for depositing a decorative thin film on a polymer surface using magnetron sputtering technology, comprising the following steps:

[0008] S1, Pretreatment and cleaning of polymer materials;

[0009] S2, magnetron sputtering of a Cr film onto the surface of a polymer material;

[0010] S3, After the Cr film sputtering in step S2 is completed, sputter CrO x film.

[0011] In step S1, the polymer material is polypropylene-butadiene-propylene.

[0012] In step S1, the pretreatment specifically includes the following processes: cleaning, painting, leveling, and UV curing.

[0013] In step S1, the cleaning is ultrasonic cleaning, which takes 15 minutes, and the cleaning solution is alcohol.

[0014] In step S2, the specific process of magnetron sputtering Cr film is as follows: First, the polymer material is dried and then placed into the chamber. After glow cleaning for 15 minutes at an Ar flow rate of 200 sccm and a bias voltage of 700 V, a Cr coating with a thickness of 320 nm is prepared as the bottom film at a sputtering power of 280 W, a bias voltage of 40 V, a working gas pressure of 0.5 Pa, and a target spacing of 120 mm.

[0015] In step S3, CrO is sputtered. x The thin film processing conditions are as follows: sputtering power 280W, bias voltage 40V, target spacing 120mm, and total pressure of Ar and O2 maintained at 0.5Pa.

[0016] In step S3, CrO x The sputtering time for the thin film is 35–125 min.

[0017] Compared with existing technologies, the advantages of this invention are as follows: This invention employs a green and environmentally friendly PVD process, fundamentally avoiding the drawbacks of electroplating processes such as high energy consumption, severe pollution, and threats to human health. Secondly, the decorative film prepared by this invention not only has a simplified process and a rich selection of colors, but also achieves a hardness of H or higher and an adhesion of 0, fully meeting market requirements for product performance and making it suitable for industrial promotion. Attached Figure Description

[0018] Figure 1 A schematic diagram of the sputtering system structure of a magnetic coating equipment;

[0019] Figure 2 A Cr / CrO double-layer structure magnetron sputtered on the surface of a polymer material x Thin film process flow diagram;

[0020] Figure 3 A Cr / CrO double-layer structure magnetron sputtered on the surface of a polymer material x Schematic diagram of thin film structure;

[0021] Figure 4 The images show the cracking of Cr films on polymer material surfaces after different sputtering times. A and B represent the cracking morphologies of Cr after sputtering for 30 and 60 minutes, respectively.

[0022] Figure 5 The reflectance values ​​of the Cr film on the surface of the polymer material under different sputtering times are shown.

[0023] Figure 6 The cracking of Cr film on the surface of polymer materials under different sputtering powers are shown in Figure 280W and Figure 360W.

[0024] Figure 7 The reflectance values ​​of the Cr film on the surface of the polymer material under different sputtering powers;

[0025] Figure 8 For magnetron sputtering of Cr / CrO on polymer material surfaces x The colors after the film are A, B, C, D, E, and F, which represent chromium oxide sputtering times of 35, 45, 55, 85, 95, and 125 min, respectively.

[0026] Figure 9 CrO at different sputtering times x Colorimetric values ​​of the thin film;

[0027] Figure 10 For magnetron sputtering of Cr / CrO on polymer material surfaces x The hardness of the thin film, A, B, C, D, E, and F are respectively the chromium oxide sputtering times of 35, 45, 55, 85, 95, and 125 min;

[0028] Figure 11 For magnetron sputtering of Cr / CrO on polymer material surfaces x The adhesion of the thin film, A, B, C, D, E, and F are the chromium oxide sputtering times of 35, 45, 55, 85, 95, and 125 min, respectively. Detailed Implementation

[0029] Double-layer Cr / CrO x The principle of color development in decorative thin films is the interference effect of the thin film, that is, changing the optical path difference of light. Changing the film thickness is the only way, and the simplest and most effective way to change the film thickness is to change the sputtering time.

[0030] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0031] Appendix Figure 1 This is a schematic diagram of the sputtering system of the coating equipment. This experiment uses medium-frequency magnetron sputtering, with two rectangular targets on each side, each connected to a medium-frequency (MF) sputtering power supply (used in the experiment). Figure 1 (Right target), the sample is placed on the right side of the sample holder, close to the holder. During the mid-frequency reactive sputtering process, when the voltage on the target is in the negative half-cycle, the target surface is bombarded by positive ions and sputtering occurs; when the voltage is in the positive half-cycle, electrons in the plasma are accelerated to bombard the target surface, neutralizing the positive charge accumulated on the target surface, thereby avoiding abnormal discharge and target poisoning caused by charge accumulation, and ensuring the stable operation of the sputtering process.

[0032] Example 1

[0033] like Figure 2 As shown, the specific implementation steps for depositing decorative thin films on polymer surfaces using magnetron sputtering technology are as follows:

[0034] Step 1: Prepare polymer materials;

[0035] Step 2: Pre-treatment of polymer materials: cleaning, spraying, leveling, and UV curing; polyurethane is selected as the primer, with a spraying thickness of 15um and a UV curing temperature of 80℃.

[0036] Step 3: After cutting the sample to a size of 50mm x 50mm x 1mm, clean it with ultrasonic alcohol for 15 minutes.

[0037] Step 4: The target material is a planar rectangular Cr target with a purity of 99.99%. The working gas is high-purity (99.99%) Ar. After drying the sample, it is placed in the chamber. The sample is glow-cleaned for 15 minutes at an Ar flow rate of 200 sccm and a bias voltage of 700 V. Cr coatings with thicknesses of 320 nm and 1 μm are prepared as the bottom film at a sputtering power of 480 W, sputtering times of 30 and 60 min, a bias voltage of 40 V, a working gas pressure of 0.5 Pa, and a target spacing of 120 mm.

[0038] like Figure 4 As shown, with increasing sputtering time of the Cr film, the degree of film cracking significantly worsens, which is related to the stress experienced by the film. From Figure 5 It can be observed that the maximum reflectance of the Cr film is 62.0% when the sputtering time is 30 minutes, and 59.3% when the sputtering time is 60 minutes.

[0039] Example 2

[0040] like Figure 2 As shown, the specific implementation steps for depositing decorative thin films on polymer surfaces using magnetron sputtering technology are as follows:

[0041] Step 1: Prepare polymer materials;

[0042] Step 2: Pre-treatment of polymer materials: cleaning, spraying, leveling, and UV curing; polyurethane is selected as the primer, with a spraying thickness of 15um and a UV curing temperature of 80℃.

[0043] Step 3: After cutting the sample to a size of 50mm x 50mm x 1mm, clean it with ultrasonic alcohol for 15 minutes.

[0044] Step 4: The target material is a planar rectangular Cr target with a purity of 99.99%. The working gas is high-purity (99.99%) Ar. After drying the sample, it is placed in the chamber. The sample is glow-cleaned for 15 minutes at an Ar flow rate of 200 sccm and a bias voltage of 700 V. A Cr coating with a thickness of 320 nm is prepared as the bottom film under sputtering power of 280 W and 360 W, a bias voltage of 40 V, a working gas pressure of 0.5 Pa, and a target spacing of 120 mm.

[0045] like Figure 6 As shown, with increasing sputtering power of the Cr film, the degree of film cracking significantly worsens, which is related to the stress experienced by the film. At rapid deposition rates, the film structure exhibits a strong shadowing effect, subsequently forming inter-pillar voids, which facilitate tensile stress propagation and exacerbate cracking. Figure 7 It can be observed that the maximum reflectance of the Cr film is 55.5% at 360W and 66.5% at 280W, because the Cr film prepared at this power is the brightest and crack-free.

[0046] Example 3

[0047] like Figure 2 As shown, the specific implementation steps for depositing decorative thin films on polymer surfaces using magnetron sputtering technology are as follows:

[0048] Step 1: Prepare polymer materials;

[0049] Step 2: Pre-treatment of polymer materials: cleaning, spraying, leveling, and UV curing; polyurethane is selected as the primer, with a spraying thickness of 15um and a UV curing temperature of 80℃.

[0050] Step 3: After cutting the sample to a size of 50mm x 50mm x 1mm, clean it with ultrasonic alcohol for 15 minutes.

[0051] Step 4: The target material is a planar rectangular Cr target with a purity of 99.99%. The working gas is high-purity (99.99%) Ar. After drying the sample, it is placed in the chamber. The sample is glow-cleaned for 15 minutes at an Ar flow rate of 200 sccm and a bias voltage of 700 V. A Cr coating with a thickness of 320 nm is prepared as the bottom film under sputtering conditions of 280 W sputtering power, 40 V bias voltage, 0.5 Pa working gas pressure, and 120 mm target spacing.

[0052] Step 5: The reaction gas is high-purity (99.99%) O2, the sputtering power is still 280W, the total pressure of O2 and Ar is maintained at 0.5Pa, the target spacing is still 120mm, the chromium oxide sputtering time is 35 and 45min, and the measured actual film thickness is 35 and 54nm.

[0053] like Figure 8As shown, the film colors observed with the naked eye after chromium oxide sputtering for 35 and 45 minutes were orange and blue, respectively. The film colors were accurately measured using a colorimeter, and the results are as follows: Figure 9 As shown, after chromium oxide sputtering for 35 min, a* = 2.21 and b* = 15.41, indicating that the film is mainly yellow with a slight reddish tinge, which is consistent with the orange film observed in practice. Figure 8 A) After 45 minutes of sputtering, a* = -0.77, b* = -21.13, and the thin film was predominantly blue. Figure 8 B). The hardness of the film was tested using the pencil hardness test according to ISO 19252:2018 standard, and the results are as follows: Figure 10 As shown. When the sputtering time of chromium oxide is 35 and 45 minutes, the pencil hardness is less than 5H. At this time, only the graphite traces left by the pencil can be seen on the film (e.g., Figure 10 (As shown in the yellow box area A). When the pencil hardness exceeds 5H, obvious scratches appear on the film surface (such as...). Figure 10 The area shown in the red box (B) exposes the white substrate, indicating that the film is damaged. Therefore, the film's hardness reaches 5H, meeting industry requirements. The film's hardness is closely related to its phase structure; in the chromium oxide film prepared at this sputtering time, Cr2O3 is the main component, and its corundum-type structure imparts high hardness. On the other hand, the film's adhesion was tested using the cross-cut adhesion test according to ISO 2409:2013. The test results are as follows... Figure 11 The cut squares are neat and regular, with no coating peeling at any edge. According to the standard assessment, its adhesion is grade 0, which meets the requirements. The good adhesion may stem from the formation of Cr-O and Cr-C chemical bonds between the underlying Cr film and the sprayed primer, which effectively enhances the adhesion between the film and the polymer substrate.

[0054] Example 4

[0055] like Figure 2 As shown, the specific implementation steps for depositing decorative thin films on polymer surfaces using magnetron sputtering technology are as follows:

[0056] Step 1: Prepare polymer materials;

[0057] Step 2: Pre-treatment of polymer materials: cleaning, spraying, leveling, and UV curing; polyurethane is selected as the primer, with a spraying thickness of 15um and a UV curing temperature of 80℃.

[0058] Step 3: After cutting the sample to a size of 50mm x 50mm x 1mm, clean it with ultrasonic alcohol for 15 minutes.

[0059] Step 4: The target material is a planar rectangular Cr target with a purity of 99.99%. The working gas is high-purity (99.99%) Ar. After drying the sample, it is placed in the chamber. The sample is glow-cleaned for 15 minutes at an Ar flow rate of 200 sccm and a bias voltage of 700 V. A Cr coating with a thickness of 320 nm is prepared as the bottom film under sputtering conditions of 280 W sputtering power, 40 V bias voltage, 0.5 Pa working gas pressure, and 120 mm target spacing.

[0060] Step 5: The reaction gas is high-purity (99.99%) O2, the sputtering power is still 280W, the total pressure of O2 and Ar is maintained at 0.5Pa, the target spacing is still 120mm, the chromium oxide sputtering time is 55 and 85min, and the measured actual film thickness is 73 and 110nm.

[0061] like Figure 8 As shown, the film colors observed to the naked eye after chromium oxide sputtering for 55 and 85 minutes were cyan and green, respectively. Accurate color measurements of the film were performed using a colorimeter, and the results are as follows: Figure 9 As shown, after chromium oxide sputtering for 55 min, a* = 7.37 and b* = -17.85. The film is also predominantly blue, but doped with a certain amount of red, consistent with the observed cyan color of the film. Figure 8 C). At a sputtering time of 85 min, a* = -4.13, b* = 10.95, and the film exhibits a green color ( Figure 8 D). The hardness of the film was tested using the pencil hardness test, and the results are as follows. Figure 10 As shown in C and 10D. The film hardness is the same as that at sputtering times of 35 and 45 min, reaching 5H. The adhesion of the film was tested using the cross-cut adhesion test. The test results are as follows. Figure 11 The cut squares are neat and regular, with no coating peeling at any edge. According to the standard assessment, its adhesion is grade 0, which meets the requirements.

[0062] Example 5

[0063] like Figure 2 As shown, the specific implementation steps for depositing decorative thin films on polymer surfaces using magnetron sputtering technology are as follows:

[0064] Step 1: Prepare polymer materials;

[0065] Step 2: Pre-treatment of polymer materials: cleaning, spraying, leveling, and UV curing; polyurethane is selected as the primer, with a spraying thickness of 15um and a UV curing temperature of 80℃.

[0066] Step 3: After cutting the sample to a size of 50mm x 50mm x 1mm, clean it with ultrasonic alcohol for 15 minutes.

[0067] Step 4: The target material is a planar rectangular Cr target with a purity of 99.99%. The working gas is high-purity (99.99%) Ar. After drying the sample, it is placed in the chamber. The sample is glow-cleaned for 15 minutes at an Ar flow rate of 200 sccm and a bias voltage of 700 V. A Cr coating with a thickness of 320 nm is prepared as the bottom film under sputtering conditions of 280 W sputtering power, 40 V bias voltage, 0.5 Pa working gas pressure, and 120 mm target spacing.

[0068] Step 5: The reaction gas is high-purity (99.99%) O2, the sputtering power is still 280W, the total pressure of O2 and Ar is maintained at 0.5Pa, the target spacing is still 120mm, the chromium oxide sputtering time is 95 and 125min, and the measured actual film thickness is 130 and 168nm.

[0069] like Figure 8 As shown, the film colors observed by the naked eye after chromium oxide sputtering for 95 and 125 min were yellow and purple, respectively. The film colors were accurately measured using a colorimeter, and the results are as follows: Figure 9 As shown, after chromium oxide sputtering for 95 min, a* = 2.95 and b* = 31.22. The film is mainly yellow with a slight red tinge, exhibiting a yellow ( Figure 8 E). Sputtering time 125 min, a* = 25.29, b* = -18.37, the film is predominantly red with some blue mixed in, therefore the film actually observed appears purplish-red. Figure 8 F). The hardness of the film was measured using the same method. When the sputtering time of chromium oxide was 95 and 125 minutes, and the pencil hardness exceeded H, obvious scratches appeared on the film surface (e.g., Figure 10 E, 10F (shown in the red box areas), resulting in the exposure of the white substrate, indicating that the film has been damaged. Therefore, the hardness of this film can reach H. In the chromium oxide film prepared at this sputtering time, Cr2O3 and CrO3 are the main components, and CrO3 molecules contain Cr 6+ It forms a chain-like structure with O, with molecules tightly bound together by van der Waals forces, resulting in extremely low hardness. Although the film hardness is H, it still meets the requirements. The bonding strength remains at 0.

[0070] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for depositing a decorative thin film on a polymer surface using magnetron sputtering technology, characterized in that, Includes the following steps: S1, Pretreatment and cleaning of polymer materials; S2, magnetron sputtering of a Cr film onto the surface of a polymer material; S3, After the Cr film sputtering in step S2 is completed, sputter CrO x film.

2. The method for depositing a decorative thin film on a polymer surface using magnetron sputtering technology as described in claim 1, characterized in that, In step S1, the polymer material is polypropylene-butadiene-propylene.

3. The method for depositing a decorative thin film on a polymer surface using magnetron sputtering technology as described in claim 1, characterized in that, In step S1, the pretreatment specifically includes the following processes: cleaning, painting, leveling, and UV curing.

4. The method for depositing a decorative thin film on a polymer surface using magnetron sputtering technology as described in claim 1, characterized in that, In step S1, the cleaning is ultrasonic cleaning, which takes 15 minutes, and the cleaning solution is alcohol.

5. The method for depositing a decorative thin film on a polymer surface using magnetron sputtering technology as described in claim 1, characterized in that, In step S2, the specific process of magnetron sputtering Cr film is as follows: First, the polymer material is dried and then placed into the chamber. After glow cleaning for 15 minutes at an Ar flow rate of 200 sccm and a bias voltage of 700 V, a Cr coating with a thickness of 320 nm is prepared as the bottom film at a sputtering power of 280 W, a bias voltage of 40 V, a working gas pressure of 0.5 Pa, and a target spacing of 120 mm.

6. The method for depositing a decorative thin film on a polymer surface by magnetron sputtering as described in claim 1, characterized in that, In step S3, CrO is sputtered. x The thin film processing conditions are as follows: sputtering power 280W, bias voltage 40V, target spacing 120mm, and total pressure of Ar and O2 maintained at 0.5Pa.

7. The method for depositing a decorative thin film on a polymer surface by magnetron sputtering as described in claim 1, characterized in that, In step S3, CrO x The sputtering time for the thin film is 35–125 min.

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