Method for conducting UV 3D printing and painting on surface of plastic part

Abstract

The invention discloses a method for conducting UV 3D printing and painting on the surface of a plastic part, and relates to the technical field of plastic part surface machining. The method comprises the following steps: fixing a to-be-treated plastic part on a jig according to a positioning mark; the surface of the to-be-treated plastic part is pretreated; and non-contact UV 3D ink-jet printing is conducted on the surface of the pretreated plastic part, a printed part is taken out of the jig, adhesive force, alcohol resistance and abrasion resistance tests are conducted, and after the tests are qualified, gloss oil coating, hot-pressing film covering or local film covering treatment is selectively conducted according to requirements. By adopting the method provided by the invention, the adhesive force of the printing layer can be improved by 3-5 times, the alcohol wiping resistance is more than or equal to 100 times without falling, the production efficiency is improved by 50% or more, the energy consumption is reduced by 30-50%, and the method is suitable for various plastic materials such as ABS, PC, PP and PMMA, can be widely applied to the fields of shells of household electrical appliances, automobile decorating parts and the like, and has the remarkable advantages of high efficiency, environmental protection and accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plastic part surface processing, in particular to a method for UV 3D printing and drawing on the surface of a plastic part. BACKGROUND

[0002] With the wide application of plastic products in the fields of home appliances, automotive interiors, small household appliances, etc., consumers' requirements for the decorative effect and performance of the surface of plastic parts are increasing. UV 3D printing and drawing technology is widely used in the decoration of the surface of plastic parts due to its high printing precision and rich color. However, the traditional UV printing technology has many defects in practical application: 1. Insufficient adhesion: the traditional UV printing has a simple pretreatment on the surface of the plastic, especially for low surface energy plastic materials such as PP and PE, the printed layer is prone to peeling and peeling; 2. Poor weather resistance: the printed layer has insufficient alcohol wiping resistance and wear resistance, which cannot meet the needs of daily use or industrial environment; 3. Limited compatibility: single printing ink and process parameters are difficult to adapt to different types of plastic materials, resulting in limited application range; 4. Imbalance between efficiency and environmental protection: some improved processes increase the adhesion by adding a high-temperature baking step, which not only reduces the production efficiency, but also increases the energy consumption and VOC emissions.

[0003] In the prior art, such as Chinese patent CN102616067A, a surface treatment three-dimensional laser engraving process is disclosed, which realizes a three-dimensional pattern effect through steps such as ink spraying, laser engraving and electroplating. However, this process is complex and requires multiple coating treatments, and cannot solve the adhesion and weather resistance problems of UV printing on the surface of plastic. Therefore, it has become a technical problem to be solved in the field to develop a UV 3D printing and drawing surface decoration treatment method that is efficient, environmentally friendly, suitable for a variety of plastic materials, and can significantly improve the adhesion and weather resistance of the printed layer. SUMMARY

[0004] In order to solve the problems existing in the prior art, the present application provides the following technical solutions.

[0005] The present application provides a method for UV 3D printing and drawing on the surface of a plastic part, comprising: fixing the plastic part to be treated on a jig through a positioning member; pretreating the surface of the plastic part to be treated, including cleaning, air drying and drying treatment, and surface activation treatment for non-polar plastic materials; the surface activation treatment includes one of plasma treatment, corona treatment or flame treatment; Non-contact UV 3D inkjet printing is performed on the surface of pre-treated plastic parts, including: selecting a 3D UV inkjet printer that supports one-time multi-color pattern printing; matching inks according to the material type of the plastic parts; controlling printhead height, printing speed, ink layer thickness, texture thickness, printing accuracy, and printhead parameters; and using a UVLED curing lamp with a wavelength of 365-395nm and a power of ≥80W / cm to move synchronously with the printhead for curing, with a curing time of less than 1 second. Remove the printed part from the fixture and conduct adhesion, alcohol resistance and abrasion resistance tests. If the test is passed, selectively apply varnish, hot press film or partial film coating treatment as needed.

[0006] Preferably, in the plasma treatment, the surface energy of the plastic part is greater than or equal to 40 dyn / cm.

[0007] Preferably, the surface activation treatment further includes the step of: Spray a UV primer and control the film thickness to 5-10μm; The film is UV cured, and the curing energy is controlled at 80-120 mJ / cm².

[0008] Preferably, the step of matching and selecting ink according to the material type of the plastic part includes: If the plastic part is made of general-purpose plastic material, select PUV series ink or plastic UV ink according to the material properties. If the plastic part is made of plastic material with a surface energy of less than 35 mN / m, then choose a plastic UV ink containing an adhesion promoter.

[0009] Preferably, the curing process employs a two-stage curing method, which involves pre-curing followed by complete curing; wherein the power of the UV LED curing lamp is lower in the pre-curing stage than in the complete curing stage.

[0010] Preferably, the adhesion test is conducted by using 3M tape to adhere and peel off; the alcohol resistance test is conducted by repeatedly wiping the product surface with an alcohol swab a preset number of times; and the abrasion resistance test is conducted by repeatedly wiping the product surface with a friction tester or an eraser a preset number of times.

[0011] Preferably, the thickness of the varnish coating is controlled between 5-15 μm.

[0012] Preferably, during the implementation of the method, the ambient temperature is controlled at 20-25℃ and the humidity at 40-60%.

[0013] Preferably, the printhead height is controlled at 1-20mm; the printing speed is controlled at 50-100mm / s; the ink layer thickness is controlled at 15-25μm; the number of texture stacking layers is set to 10-100 layers according to requirements, with a single layer thickness of 5-10μm and a total thickness of 50-500μm; the resolution is controlled at 360×720dpi~1440×2880dpi; and the printhead ejection frequency is controlled at 10-30kHz.

[0014] Preferably, the cleaning and drying include: Wipe the surface of the plastic part to be treated with a cleaning agent, and then dry the surface with an air gun after wiping. Physically clean the surface by blowing it with an air gun.

[0015] The beneficial effects of this invention are as follows: The method for UV 3D printing on the surface of plastic parts provided by this invention, through optimized pretreatment process, matching special UV inks and precise curing parameters, improves the adhesion of the printed layer by 3-5 times, withstands alcohol wiping ≥100 times without peeling, and increases production efficiency by more than 50% while reducing energy consumption by 30-50%. It is applicable to various plastic materials such as ABS, PC, PP, and PMMA, and can be widely used in fields such as household appliance shells and automotive decorative parts, with significant advantages of high efficiency, environmental protection and precision. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of the method for UV 3D printing on the surface of a plastic part according to the present invention. Detailed Implementation

[0017] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0018] To address the problems of poor adhesion, insufficient alcohol resistance and abrasion resistance, poor material compatibility, and low production efficiency in existing UV-printed plastic parts surface decoration technologies, this invention provides a UV 3D printing inkjet technology that can be used for surface decoration of home appliance products (television casings, air conditioner casings, drum washing machine casings and door frames, refrigerator panels, water heater casings, etc.). Furthermore, the plastic parts surface can be flat, curved, or irregularly shaped. By optimizing the pretreatment process, matching specialized materials, and precisely controlling printing and curing parameters, efficient, environmentally friendly, and high-quality plastic parts surface decoration can be achieved.

[0019] like Figure 1 As shown, this embodiment of the invention provides a method for UV 3D printing on the surface of a plastic part, which may include the following steps: S101, the plastic part to be processed is fixed onto the fixture using positioning components. The fixture can be custom-made according to the shape and dimensions of the plastic part and the required printing position. Specifically, it can be made of materials such as acrylic sheet, aluminum, or bakelite board. Generally, the flatness error of the substrate should be ≤0.1mm / m, and the curvature deviation of curved substrates should be ≤0.5mm to avoid texture misalignment caused by substrate displacement during printing. Bakelite board has the advantages of high strength and good stability, making it suitable for mass production. In practical applications, the fixture can include a vacuum adsorption platform (adsorption force can be controlled between 0.06 and -0.08MPa) and positioning clamps (clamps can be fixed with screws to prevent position movement; flexible suction cups can be used when adapting to curved substrates). Positioning pins or magnetic components can be used to fix the plastic part to be processed. Using positioning and fixing methods can prevent displacement of the plastic part during printing and ensure the consistency of printing position for each product in mass production.

[0020] S102, pre-treating the surface of the plastic part to be treated, including cleaning, air drying and drying treatment, and surface activation treatment of non-polar plastic materials; the surface activation treatment includes one of plasma treatment, corona treatment or flame treatment.

[0021] This step is crucial for improving the adhesion of the printed layer, and it can be divided into two stages. The first stage includes the following steps: 1) Cleaning with alcohol, white spirit, or compound cleaner. Use anhydrous ethanol or isopropanol, white spirit, or compound cleaner as the cleaning medium to remove oil, mold release agent residue, and dust from the surface of the plastic parts by wiping. After wiping, use an air gun to thoroughly dry the surface of the plastic parts to ensure that there is no residual liquid or impurities, and to avoid residual substances affecting the adhesion between the printed layer and the plastic surface.

[0022] 2) Physical cleaning: Ultrasonic cleaning (power 40-60kHz, time 3-5min) → high-pressure air gun drying (air pressure 0.3-0.5MPa); 3) Drying treatment: Oven drying (temperature 40-60℃, time 10-20min) to ensure that the surface moisture content of the substrate is ≤0.1%.

[0023] Second stage: Surface activation. Surface activation treatment is selectively performed based on the material type of the plastic part. (1) Plasma treatment: Applicable to most plastic materials. High-energy plasma bombards the plastic surface, breaks the surface molecular bonds, increases the surface energy, and forms a micro-rough structure on the surface, which enhances the physical bonding force between the printing ink and the plastic surface; plasma power 100-300W, processing speed 5-10m / min, gas type (air / argon), processing distance 5-10mm; (2) Corona treatment: mainly applicable to film plastic materials. High voltage discharge oxidizes the plastic surface to form polar groups, improves surface wettability, and facilitates ink spreading; voltage 15-30kV, discharge gap 1-3mm, processing speed 8-15m / min (applicable to plastic film and leather substrate). (3) Flame treatment: For non-polar plastic materials such as PP and PE that are difficult to adhere to, the surface molecular structure is changed by short-term flame burning and other methods to increase polar sites and improve ink adhesion.

[0024] For polar plastic materials such as ABS and PS, they can proceed directly to the subsequent printing steps after cleaning with alcohol, white spirit, or composite cleaner; for non-polar plastic materials such as PP and PE, they need to undergo surface activation treatment and be coated with a special primer to further improve adhesion.

[0025] S103 involves non-contact UV 3D inkjet printing on the pre-treated plastic part surface, including: selecting a 3D UV inkjet printer that supports one-time multi-color pattern printing; selecting ink according to the material type of the plastic part; controlling the printhead height, printing speed, ink layer thickness, texture thickness, printing accuracy, and printhead parameters; and using a UV LED curing lamp with a wavelength of 365-395nm and a power ≥80W / cm to cure the pattern synchronously with the printhead, with a curing time of less than 1 second. This step is the core process, achieving accurate pattern printing and instant drying. Specifically, this invention uses a 3D UV inkjet printer that supports one-time multi-color pattern printing, eliminating the need for multiple overprints and improving production efficiency. The ink can be selected according to the type of plastic material. In one embodiment of this invention, a 3D UV inkjet printer of model KGT-2513 can be used. In this embodiment of the invention, a UV LED curing lamp with a wavelength of 365-395nm and a power ≥80W / cm can be used. During the printing process, the curing lamp moves synchronously with the printhead to achieve "instant drying" with a curing time of less than 1 second.

[0026] S104: Remove the printed part from the fixture and perform adhesion, alcohol resistance, and abrasion resistance tests. If the tests are passed, selectively apply varnish, hot-press lamination, or partial lamination as needed. After printing, remove the plastic part from the fixture, avoiding scratching the newly cured printed layer to prevent damage.

[0027] The extracted plastic parts undergo three core performance tests: ① adhesion test; ② alcohol resistance test; ③ abrasion resistance test. After passing the tests, post-processing can be selectively performed according to product requirements: ① applying protective varnish; ② hot-pressing lamination; ③ localized high-gloss treatment.

[0028] In one embodiment of the present invention, the surface energy of the plastic part is greater than or equal to 40 dyn / cm during the plasma treatment. By bombarding the plastic surface with high-energy plasma, the surface molecular bonds are broken, thereby increasing the surface energy of the plastic part. When the surface energy of the plastic part is greater than or equal to 40 dyn / cm, surface activation of the plastic part can be achieved, thereby enhancing the adhesion between the printing ink and the surface of the plastic part.

[0029] In one embodiment of the present invention, the surface activation treatment, in addition to plasma treatment, corona treatment, or flame treatment, may also include the following steps: Spray a UV primer and control the film thickness to 5-10μm; The film is UV cured, and the curing energy is controlled at 80-120 mJ / cm².

[0030] This step is suitable for inert substrates such as glass or metal.

[0031] In one embodiment of the present invention, the step of matching and selecting ink according to the material type of the plastic part includes: If the plastic part is made of general-purpose plastic material, PUV series inks or plastic UV inks can be selected according to the material properties. General-purpose plastic materials can include six major categories: polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene copolymer (ABS), and polymethyl methacrylate (PMMA).

[0032] If the plastic part has a surface energy below 35 mN / m, then a UV ink containing adhesion promoters should be selected. Adhesion promoters can include: methacryloxysilane (KH-570), chlorinated polypropylene resin (CPP-300), and fluorinated modified acrylic resin (FAR-100), with methacryloxysilane (KH-570) showing the best effect in improving adhesion. Plastic materials with a surface energy below 35 mN / m can include PP, PE, etc. Different inks should be selected for different plastic parts to promote chemical bonding between the ink and the plastic surface, further enhancing the adhesion strength of the printed layer.

[0033] In an embodiment of the present invention, the curing can adopt a two-stage curing method of pre-curing first and then full-curing; wherein, the power of the UV LED curing lamp is less in the pre-curing stage than in the full-curing stage. In each curing stage, the UV LED curing lamp is moved synchronously with the nozzle for curing. By adopting the two-stage curing method of pre-curing first and then full-curing, a lower-power curing lamp can be used for preliminary curing in the pre-curing stage to avoid excessive shrinkage of the ink; a rated-power curing lamp is used in the full-curing stage to ensure sufficient cross-linking and curing of the ink. In the embodiment of the present invention, the overall curing time is less than 1 second. Adopting the two-stage curing method can reduce the internal stress in the printed layer and improve the adhesion and weather resistance.

[0034] In an embodiment of the present invention, the 3M tape adhesion test method can be adopted for the adhesion test. After the tape is pasted, it is torn evenly with force, and the printed layer does not fall off is qualified; the alcohol resistance test is carried out by repeatedly wiping the product surface with an alcohol cotton ball for a preset number of times, and the abrasion resistance test is carried out by repeatedly wiping the product surface with a friction tester or a rubber (hardness 60-80 Shore A) for a preset number of times. The preset number of times can be ≥100 times. If there is no fading or peeling on the printed surface during the test, it is qualified; it can ensure that the printed layer is not easily worn in daily use scenarios.

[0035] In an embodiment of the present invention, the thickness of the varnish coating is controlled within 5-15μm. After passing the quality inspection, post-treatment can be carried out according to product requirements: ① Coating a protective varnish: The varnish thickness is controlled within 5-15μm, which can further improve the abrasion resistance and gloss of the printed layer; ② Thermal lamination: A protective film is covered on the surface of the printed layer by thermal pressing to improve the scratch resistance and waterproof performance; ③ Local high-gloss treatment: High-gloss treatment is carried out on specific areas of the pattern to enhance the visual hierarchy and texture of the product.

[0036] In an embodiment of the present invention, during the implementation of the method, the temperature of the environment is controlled at 20-25°C and the humidity is controlled at 40-60%.

[0037] In an embodiment of the present invention, the height of the nozzle can be controlled within 1-20mm. This height range can ensure the accuracy of non-contact printing, avoid scratching caused by the nozzle contacting the surface of the plastic part, and at the same time ensure good ink atomization effect; the printing speed is adjusted according to the pattern complexity, generally controlled within 50-100mm / s. A lower speed is adopted for complex patterns to ensure printing accuracy, and a higher speed is adopted for simple patterns to improve production efficiency; the ink layer thickness is controlled within 15-25μm. This thickness range can ensure that the pattern color is full, and at the same time avoid problems such as incomplete drying or peeling caused by too thick ink layer.

[0038] The texture thickness can be set according to the number of stacked layers (10-100 layers), with a single layer thickness of 5-10μm and a total thickness of 50-500μm (Braille requires ≥200μm, and tactile texture requires 80-200μm). The printing resolution can be controlled between 360×720dpi (rapid prototyping) and 1440×2880dpi (fine texture); the ejection frequency of the print head can be controlled between 10-30kHz (to match the curing speed and avoid ink droplet diffusion); the scanning method adopts unidirectional scanning (reducing bidirectional misalignment) or bidirectional scanning (efficiency is improved by 30%, but print head offset needs to be calibrated).

[0039] Compared with the prior art, the present invention has the following beneficial effects: 1. Significantly Improved Adhesion: Through targeted surface pretreatment processes and matching with special inks, the adhesion of the printed layer is improved by 3-5 times, which can meet the adhesion requirements of different plastic materials, especially solving the printing adhesion problem of low surface energy materials such as PP and PE; existing technologies do not clearly define the surface energy threshold, and this invention has determined 40dyn / cm as the optimal threshold through a large number of experiments, achieving a balance between adhesion and processing efficiency. 2. Excellent weather resistance: Tested, the printed layer can withstand ≥100 wipings with an alcohol swab without peeling off, and its wear resistance meets the requirements of daily use and industrial environment, significantly extending its service life; 3. High production efficiency: It adopts non-contact multi-color one-time molding printing and synchronous UV curing technology to achieve instant drying without waiting for drying time, which increases production efficiency by more than 50%; at the same time, it reduces the multi-plate overprinting process of traditional screen printing, further saving production time. 4. Energy saving and environmental protection: No high-temperature baking step is required, reducing energy consumption by 30-50%, and the VOC emission of UV ink is almost zero, which meets the requirements of green production; 5. Wide material compatibility: Applicable to a variety of plastic materials such as ABS, PC, PVC, PMMA, PET, PP, and PE, which can meet the decorative needs of plastic parts in different fields; 6. Significant cost advantages: It reduces processes such as plate making and overprinting, saving plate making costs and labor costs, while reducing the scrap rate caused by process defects, and further controlling production costs. Specific Implementation Example 1 This specific embodiment provides a method for UV 3D printing on the surface of an ABS mobile phone casing, which can be implemented according to the following steps: Step 1. Design File Preparation: Provide AI format mobile phone case decoration pattern design files, 300dpi resolution, and patterns containing gradient colors and fine textures.

[0041] Step 2. Fixture fabrication and positioning: A special fixture is made using bakelite / aluminum material. The ABS mobile phone shell is precisely fixed by positioning pins to ensure that the printed pattern is accurately aligned with the shell buttons and camera holes.

[0042] Step 3. Surface pretreatment: Wipe the surface of the ABS mobile phone shell with anhydrous ethanol, and blow it dry with an air gun after wiping; since ABS is a polar material, no additional surface activation treatment is required.

[0043] Step 4. Non-contact UV inkjet printing: Select a 3D UV inkjet printer and match it with PUV series general plastic UV ink; set the printhead height to 2mm, the printing speed to 80mm / s, and the ink layer thickness to 20μm; use a UVLED curing lamp with a wavelength of 385nm and a power of 80W / cm to simultaneously perform print-and-dry curing, with a curing time of 0.8 seconds.

[0044] Step 5. Post-processing and quality control: Carefully remove the printed phone case and perform quality inspection: 3M tape adhesion test shows no peeling, alcohol swab wiping 150 times shows no fading or peeling, eraser abrasion test shows no obvious scratches; apply 10μm thick protective varnish as needed to improve gloss and abrasion resistance.

[0045] The ABS mobile phone casing processed in this specific embodiment has clear patterns, rich colors, excellent adhesion and weather resistance, and meets the usage requirements of casings for home appliances. Specific Implementation Example 2 This specific embodiment provides a method for UV 3D printing on the surface of a PP toy shell, which can be implemented according to the following steps: Step 1. Design File Preparation: Provide a cartoon pattern design file for the toy shell in PS format, with a resolution of 350dpi, to ensure that the details of the cartoon pattern are clear.

[0047] Step 2. Fixture making and positioning: A special fixture is made of bakelite board / aluminum material, which is used to fix the PP toy shell with magnetic attraction to prevent displacement during printing.

[0048] Step 3. Surface pretreatment: Wipe the surface of the PP toy shell with isopropyl alcohol, blow it dry with an air gun, and then perform plasma treatment to increase the surface energy to 45 dyn / cm; then apply a layer of PP special primer and let it air dry for 5 minutes.

[0049] Step 4. Non-contact UV inkjet printing: Select a 3D UV inkjet printer and match it with PP-specific UV ink containing adhesion promoter; set the printhead height to 1.5mm, printing speed to 60mm / s, and ink layer thickness to 18μm; use a UV LED curing lamp with a wavelength of 395nm and a power of 100W / cm, and adopt a two-stage curing process: pre-curing power 40W / cm, full curing power 100W / cm, and a total curing time of 0.9 seconds.

[0050] Step 5. Post-processing and quality control: Remove the toy shell for testing: 3M tape adhesion test shows no peeling, alcohol swab wiping 120 times shows no fading, and a dedicated abrasion tester shows compliance with toy safety standards; no additional post-processing is required, proceed directly to the subsequent assembly process.

[0051] The PP toy shell processed in this specific embodiment has a strong bond between the printed layer and the shell, is wear-resistant and wipe-resistant, and meets the safety and usage requirements of toy products.

[0052] The UV 3D printing inkjet method provided by this invention can be widely applied in the following fields: 1. Appliance casings: Plastic casing decorations for home appliances and electronic products such as television casings, air conditioner casings, drum washing machine casings and door frames, refrigerator panels, water heater casings, mobile phones, tablets, and laptops, which can achieve personalized patterns, gradient colors and other decorative effects; 2. Automotive trim parts: Surface decoration of plastic interior parts such as car dashboards, center consoles, and air conditioning vents to enhance the interior's texture and aesthetics; 3. Small appliances: Plastic shell decoration for small appliances such as kitchen appliances (e.g., rice cookers, microwave ovens) and bathroom fixtures, to meet the aesthetic and durability requirements of the home environment; 4. Toys and cultural and creative products: Personalized customization and decoration of various plastic toys and cultural and creative products, enabling rapid production of small batches and multiple varieties; 5. Medical Devices: The surface decoration of plastic shells, control panels, etc. of medical devices must use UV inks that meet biocompatibility requirements and comply with the safety standards of the medical industry.

[0053] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A method for UV 3D printing inkjet printing on the surface of a plastic part, characterized in that, include: The plastic parts to be processed are fixed onto the fixture using positioning components; Pretreatment of the plastic parts to be treated includes cleaning, air drying and drying, as well as surface activation treatment for non-polar plastic materials; The surface activation treatment includes one of plasma treatment, corona treatment, or flame treatment; Non-contact UV 3D inkjet printing is performed on the surface of pretreated plastic parts, including: selecting a 3D UV inkjet printer that supports one-time multi-color pattern printing; matching inks according to the material type of the plastic parts; controlling printhead height, printing speed, ink layer thickness, texture thickness, printing accuracy, and printhead parameters; using a UV LED curing lamp with a wavelength of 365-395nm and a power of ≥80W / cm to move synchronously with the printhead for curing, and the curing time is less than 1 second; Remove the printed part from the fixture and conduct adhesion, alcohol resistance and abrasion resistance tests. If the test is passed, selectively apply varnish, hot press film or partial film coating treatment as needed.

2. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, During the plasma treatment, the surface energy of the plastic part is greater than or equal to 40 dyn / cm.

3. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, The surface activation treatment further includes the following steps: Spray a UV primer and control the film thickness to 5-10μm; The film is UV cured, and the curing energy is controlled at 80-120 mJ / cm².

4. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, The process of selecting inks based on the material type of the plastic part includes: If the plastic part is made of general-purpose plastic material, select PUV series ink or plastic UV ink according to the material properties. If the plastic part is made of plastic material with a surface energy of less than 35 mN / m, then choose a plastic UV ink containing an adhesion promoter.

5. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, The curing process employs a two-stage curing method, which involves pre-curing followed by full curing. The power of the UV LED curing lamp is lower during the pre-curing stage than during the full curing stage.

6. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, Adhesion was tested using 3M tape, alcohol resistance was tested by repeatedly wiping the product surface with an alcohol swab a preset number of times, and abrasion resistance was tested by repeatedly wiping the product surface with a friction tester or an eraser a preset number of times.

7. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, The thickness of the varnish coating is controlled between 5-15 μm.

8. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, During the implementation of the method, the ambient temperature is controlled at 20-25℃ and the humidity at 40-60%.

9. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, The printhead height is controlled between 1-20mm; the printing speed is controlled between 50-100mm / s; the ink layer thickness is controlled between 15-25μm; the number of texture stacking layers is set to 10-100 layers according to requirements, with a single layer thickness of 5-10μm and a total thickness of 50-500μm; the resolution is controlled between 360×720dpi~1440×2880dpi; and the printhead ejection frequency is controlled between 10-30kHz.

10. The method for UV 3D printing on the surface of a plastic part as described in claim 1, characterized in that, The cleaning and drying process includes: Wipe the surface of the plastic part to be treated with a cleaning agent, and then dry the surface with an air gun after wiping. Physically clean the surface by blowing it with an air gun.

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