High-brightness black and high-brightness milky white double-color high-brightness injection molding C-shaped decoration strip and production process thereof

Abstract

The invention relates to the field of decoration strips, in particular to a high-brightness black and high-brightness milky white double-color high-brightness injection molding C-shaped decoration strip which comprises a high-brightness black base body, a high-brightness black layer, a high-brightness milky white layer and a high-brightness injection molding C-shaped layer. The high-brightness black base body is integrally in a C shape, the section of the high-brightness black base body is in a dovetail shape, connecting plates are integrally arranged on the two side edges of the high-brightness black base body, and mounting grooves are formed in the connecting plates. And the three highlight milky white decoration sections are distributed in the length direction of the highlight black base body and used for embellishing, and the modeling style is highlighted. According to the highlight black highlight milky white double-color highlight injection molding C-shaped decoration strip and the production process thereof, the C-shaped decoration strip is attached to the curved surface of a bumper, the connecting plate and the mounting groove are directly matched with an assembly interface, additional connecting pieces are omitted, and looseness and displacement are avoided in an extreme environment after mounting. The dovetail groove type concave-convex stepped structure enhances the structural strength of the base body, can bear vibration impact in the running process of vehicles, solves the problem of spraying anti-UV varnish in the past, and improves the light aging resistance.

Description

Technical Field

[0001] This invention relates to the field of decorative strips, and more particularly to a two-tone high-gloss injection-molded C-shaped decorative strip in high-gloss black and high-gloss milky white and its manufacturing process. Background Technology

[0002] As the market share of new energy vehicles increases year by year, new energy vehicles are constantly incorporating bold and fashionable design elements. Currently, the requirements for the styling and texture of automotive exterior products are also becoming increasingly stringent, leading to the continuous application of innovative exterior products. In the past, decorative parts on automotive bumper assemblies were mostly textured or painted, with a single, fixed color, serving only a decorative purpose. To highlight the personalized styling of automobiles, beautify the front of the vehicle, and attract more consumers, major automakers are constantly innovating in front-end decorative parts. An innovative high-gloss black and milky white two-tone high-gloss injection-molded decorative strip part is more aesthetically pleasing than traditional high-gloss black high-gloss decorative strips, with a unique design element. However, it also presents significant challenges to traditional processes. High-gloss milky white high-gloss injection-molded parts generally have poor light aging resistance, requiring a layer of clear varnish to be sprayed after injection molding to improve the product's light aging resistance. Furthermore, two high-gloss injection molding processes are needed to achieve the fusion of the two colors, resulting in complex production processes and high part costs. At the same time, the two high-gloss colors place higher demands on the product's appearance quality, inevitably posing significant challenges to product design, mold design, and injection molding processes.

[0003] Therefore, it is necessary to provide a two-tone high-gloss injection-molded C-shaped decorative strip in high-gloss black and high-gloss milky white, and its manufacturing process to solve the above-mentioned technical problems. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a two-color high-gloss injection molded C-shaped decorative strip in high-gloss black and high-gloss milky white and its production process.

[0005] This invention provides a two-tone high-gloss injection-molded C-shaped decorative strip in high-gloss black and high-gloss milky white, characterized in that it comprises: The high-gloss black substrate is made of polycarbonate modified material; the high-gloss black substrate is C-shaped in general, and the cross-section of the high-gloss black substrate is dovetail-shaped. Both sides of the high-gloss black substrate are integrally provided with connecting plates, and the connecting plates are provided with mounting grooves. Three high-gloss milky white decorative segments are distributed along the length of the high-gloss black substrate for embellishment and enhanced aesthetics. A dovetail-groove stepped structure is provided at the junction of the high-gloss milky white decorative segments and the high-gloss black substrate. This stepped structure strengthens the C-shaped decorative strip substrate structure.

[0006] Preferably, the high-gloss black substrate is made of high-gloss black PC material, which comprises the following components by weight: 90-95 parts PC resin, 1.5-2.0 parts carbon black, 0.3-0.5 parts silicone lubricant, 0.5-1.0 parts phosphate ester flame retardant, and 3-5 parts glass fiber; the melt flow index of the material is 10-15 g / 10 min, gloss ≥ 95 GU, yellowing index ΔYI ≤ 1.0 after 2000 h of UVB irradiation, and heat distortion temperature ≥ 130℃. This solves the problem of improving light aging resistance in the past with sprayed anti-UV clear varnishes.

[0007] Preferably, the high-gloss milky white decorative section uses a high-gloss milky white PC material, which comprises the following components by weight: 88-92 parts PC resin, 5-8 parts titanium dioxide, 0.3-0.5 parts benzotriazole UV stabilizer, 0.1-0.2 parts hindered phenolic antioxidant, and 2-3 parts special white masterbatch; the material has an initial whiteness ≥92, a melt index of 8-12 g / 10 min, a hiding power ≥98%, and a yellowing index ΔYI ≤1.0 after 2000 h of UVB irradiation, with no degradation or discoloration during secondary injection molding. This solves the problem of improving light aging resistance caused by previous spray-applied UV-resistant varnishes.

[0008] A production process for manufacturing two-color high-gloss injection-molded C-shaped decorative strips in high-gloss black and high-gloss milky white is characterized by employing a horizontal rotary two-color injection molding machine with an independent temperature control system and a customized rotary mold. The process includes the following steps: (a) Material pretreatment: a. Drying of high-gloss black PC material: Put the high-gloss black PC material into a dehumidifying dryer, set the drying temperature to 120℃±5℃, the dew point temperature to ≤-40℃, and the drying time to 4-6h. After drying, the moisture content of the material should be ≤0.02%. After drying, transfer the material to an insulated hopper for later use. b. Drying of high-gloss milky white PC material: Put the high-gloss milky white PC material into another dehumidifying dryer with the same parameters as step a, ensuring that the moisture content is ≤0.02%. After drying, transfer it to an independent insulated hopper for later use. (II) Mold preheating and parameter setting: a. Turntable mold installation: Fix the customized turntable mold to the injection molding machine. The mold includes a first cavity corresponding to the high-gloss black base and a second cavity corresponding to the high-gloss milky white decorative section. The center distance between the two cavities matches the radius of the turntable. b. Cavity polishing inspection: Confirm that the polishing accuracy of the first cavity mirror surface Ra≤0.01μm, the polishing direction is along the demolding direction, and there are no scratches, pinholes, or orange peel texture; c. Temperature control system startup: The first cavity mold temperature is set to 100-120℃±2℃, and the temperature is controlled by a spiral cooling water channel with a channel diameter of 8-10mm and a spacing of 20-25mm. The second cavity mold temperature is set to 70-90℃±2℃, and the temperature is controlled by a ring cooling water channel with a channel diameter of 6-8mm and a spacing of 15-20mm. Combined with the regional local temperature control module, the temperature is set to 180-200℃±5℃, and controlled by embedded heating rods and thermocouples. (III) First injection molding: a. Barrel temperature settings: First stage 240-250℃±5℃, Second stage 250-260℃±5℃, Third stage 260-270℃±5℃, Nozzle temperature 270-280℃±5℃; b. Injection parameter settings: Injection speed is 50-80mm / s, controlled in 3 stages: 30-40mm / s in the initial stage, 50-80mm / s in the middle stage, and 20-30mm / s in the final stage; injection pressure is 90-110MPa, linearly adjusted with the filling stage; holding pressure is 85MPa±5MPa, divided into 2 stages: 85MPa in the initial stage and 75MPa in the final stage; holding time is 5-8s±1s; back pressure is 5-8MPa. c. Cooling and shaping: The cooling time is 15-25s±2s. The temperature of the high-gloss black substrate is reduced to 80-100℃ through the cooling water channel of the first cavity to ensure shaping but not complete cooling. The cavity pressure is maintained at 5-10MPa during the cooling process. (iv) Mold rotation and station switching: a. Turntable drive: The injection molding machine turntable rotates 180° at a speed of 5-10r / min, with a rotation time of 2-3s, transferring the molded high-gloss black substrate from the first cavity to the alignment position of the second cavity, with an alignment accuracy of ±0.02mm; b. Cavity cleaning: The second cavity and the bonding area of ​​the high-gloss black substrate are cleaned with compressed air at a pressure of 0.5-0.8MPa and a filtration accuracy of 0.1μm to remove surface dust and debris. (v) Second injection molding: a. Barrel temperature settings: First stage 230-240℃±5℃, Second stage 240-250℃±5℃, Third stage 250-260℃±5℃, Nozzle temperature 260-270℃±5℃; b. Injection parameter settings: Injection speed is 30-50mm / s, controlled in 2 stages: 30-40mm / s in the initial stage and 20-30mm / s in the final stage; injection pressure is 70-90MPa; holding pressure is 65MPa±5MPa, controlled in 2 stages: 65MPa in the initial stage and 55MPa in the final stage; holding time is 3-5s±1s; back pressure is 3-5MPa. c. Combined with regional temperature control: The temperature of the bonding area of ​​the high-gloss black substrate is maintained at 180-200℃ through the local temperature control module to ensure that the second injection melt forms molecular diffusion with the substrate surface. The cooling time is 10-15s±2s, which reduces the overall temperature of the decorative strip to 60-80℃. (vi) Ejection, demolding, and post-processing: a. Ejection control: Activate the concealed ejection mechanism. The ejector pins are 3-5mm in diameter, numbered 6-8, and distributed on the reinforcing ribs on the back of the high-gloss black substrate. The ejection speed is 10-15mm / s, and the ejection force is 20-30kN. Eject the product smoothly and avoid ejector pin marks on the high-gloss surface. The depth is ≤0.001mm. b. Post-processing: Remove gates from the product, with a gate residual length ≤0.5mm, remove burrs with a burr height ≤0.01mm, then perform appearance inspection, with a high gloss surface defect detection accuracy of 0.01mm, dimensional inspection using a coordinate measuring machine with an accuracy of ±0.005mm, and performance sampling inspection.

[0009] Preferably, step (iii) uses a point gate with a gate diameter of 1.5-2.0 mm, and the flow channel with a diameter of 8-10 mm is set at the end reinforcing rib of the high-gloss black substrate that is not on the surface of the substrate. The flow channel has a circular cross-section and the surface of the flow channel is polished to Ra≤0.02μm. Step (5) adopts a submarine gate with a gate diameter of 1.0-1.5mm, which is set at the end of the high-gloss milky white decorative section. The runner diameter is 6-8mm, and a 0.5-1.0mm step transition is provided at the connection between the runner and the cavity to avoid melt impact.

[0010] Preferably, the performance sampling inspection in step (vi) includes: Light aging resistance: UVB-313 lamp irradiation was performed according to GB / T 16422.3-2014 for 2000 hours, and the yellowing index ΔYI was ≤1.0.

[0011] Preferably, in step (2), the mold is also provided with an exhaust system. The exhaust groove has a width of 0.8-1.2mm, a depth of 0.01-0.02mm, and a length of 10-15mm. It is distributed at the end of the cavity and the edge of the joint area to ensure that the exhaust volume is ≥95% during the injection molding process and to avoid the generation of bubbles.

[0012] Preferably, the injection system used in steps (iii) and (v) employs a closed-loop control system that monitors the melt filling process in real time using pressure and displacement sensors. When the filling pressure fluctuation exceeds ±5MPa or the displacement deviation exceeds ±0.05mm, the system automatically adjusts the parameters to ensure injection molding stability.

[0013] Compared with related technologies, the present invention provides the following beneficial effects: (a) Structural performance: adaptable installation and long-term stability Improved assembly convenience: The C-shaped trim strip base fits the curved surface of the bumper, and the connecting plate and mounting slot directly match the assembly interface, eliminating the need for additional connecting parts, significantly improving assembly efficiency, and ensuring no loosening or displacement even in extreme environments after installation. Excellent structural strength: The dovetail-shaped profile enhances the strength of the matrix structure, enabling it to withstand vibrations and impacts during vehicle operation, and significantly reducing the after-sales claim rate. (ii) Material properties: Weather resistant and paint-free, solving the pain points of traditional materials. Light aging resistance meets standards: The high-gloss milky white material is enriched with anti-UV / antioxidant agents, resulting in excellent light aging resistance. It eliminates the need for anti-UV varnish, avoiding the low pass rate problem of traditional painting processes, while significantly reducing VOC emissions and meeting environmental protection requirements. Balanced performance in both colors: The high-gloss black material combines high gloss with scratch resistance, resolving the "contradiction between high gloss and scratch resistance"; the high-gloss milky white material has high initial whiteness and strong coverage, with no problem of the base color showing through, and the color difference between the two colors is small, meeting the visual needs of high-end models. (III) Process efficiency: Reduce costs and improve efficiency to ensure batch quality Improved production efficiency: The horizontal rotary two-color injection molding machine completes two injections on the same equipment, significantly shortening the production cycle, increasing daily capacity, and making it suitable for large-scale mass production. Significantly reduced defect rate: Through measures such as material drying, closed-loop parameter control, and high-gloss cavity polishing, the appearance defect rate is greatly reduced, and the product surface is free of flow marks, pinholes, and pin marks, with excellent surface quality. (iv) Bonding stability: high strength and long service life The dovetail groove-style concave-convex stepped structure expands the bonding area of ​​the two-color materials. Combined with the molecular diffusion layer, the bonding strength is high. It shows no warping or peeling after cold and hot cycle testing, meeting the long-term service life requirements of automotive exteriors. (v) Cost and environmental protection: Simplify processes, reduce costs and consumption. Cost reduction: Eliminating the painting process increases material utilization and reduces rework waste, resulting in a significant decrease in overall costs. Improved environmental performance: With no painting process, VOC emissions are significantly reduced, complying with national environmental protection policies, reducing paint waste disposal costs, and helping automakers achieve "green production". Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the decorative strip of the present invention; Figure 2 For the present invention Figure 1 Schematic diagram of the AA section; Figure 3 For the present invention Figure 1 Schematic diagram of the BB cross section; Figure 4 This is a process flow diagram of the present invention.

[0015] Numbering in the diagram: 1- High-gloss black substrate; 2- High-gloss milky white decorative section; 3- Connecting plate; 4- Mounting groove. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Please refer to the following: Figures 1-4 A high-gloss black and high-gloss milky white two-tone injection-molded C-shaped decorative strip, characterized in that it comprises: The high-gloss black substrate 1 is made of polycarbonate modified material; the high-gloss black substrate 1 is C-shaped in general, the cross section of the high-gloss black substrate 1 is dovetail-shaped, and both sides of the high-gloss black substrate 1 are integrally provided with connecting plates 3, and the connecting plates 3 are provided with mounting grooves 4. The high-gloss milky white decorative segment 2 is distributed along the length of the high-gloss black substrate 1, and there are three segments. The junction of the high-gloss milky white decorative segment 2 and the high-gloss black substrate 1 is provided with a dovetail groove-type concave-convex stepped structure.

[0018] The high-gloss black substrate 1 is made of high-gloss black PC material, which comprises the following components by weight: 90-95 parts PC resin, 1.5-2.0 parts carbon black, 0.3-0.5 parts silicone lubricant, 0.5-1.0 parts phosphate ester flame retardant, and 3-5 parts glass fiber; the melt flow index of the material is 10-15 g / 10 min, gloss ≥ 95 GU, yellowing index ΔYI ≤ 1.0 after 2000 h of UVB irradiation, and heat distortion temperature ≥ 130℃.

[0019] The high-gloss milky white decorative section 2 is made of high-gloss milky white PC material, which includes the following components by weight: 88-92 parts PC resin, 5-8 parts titanium dioxide, 0.3-0.5 parts benzotriazole UV stabilizer, 0.1-0.2 parts hindered phenolic antioxidant, and 2-3 parts special white masterbatch; the initial whiteness of the material is ≥92, the melt index is 8-12 g / 10 min, the hiding power is ≥98%, the yellowing index ΔYI after 2000 h of UVB irradiation is ≤1.0, and there is no degradation or discoloration during secondary injection molding.

[0020] A production process for manufacturing two-color high-gloss injection-molded C-shaped decorative strips in high-gloss black and high-gloss milky white uses a horizontal rotary two-color injection molding machine with an independent temperature control system and a customized rotary mold. The process includes the following steps: (a) Material pretreatment: a. Drying of high-gloss black PC material: Put the high-gloss black PC material into a dehumidifying dryer, set the drying temperature to 120℃±5℃, the dew point temperature to ≤-40℃, and the drying time to 4-6h. After drying, the moisture content of the material should be ≤0.02%. After drying, transfer the material to an insulated hopper for later use. b. Drying of high-gloss milky white PC material: Put the high-gloss milky white PC material into another dehumidifying dryer with the same parameters as step a, ensuring that the moisture content is ≤0.02%. After drying, transfer it to an independent insulated hopper for later use. (II) Mold preheating and parameter setting: a. Turntable mold installation: Fix the customized turntable mold to the injection molding machine. The mold includes a first cavity corresponding to the high-gloss black base 1 and a second cavity corresponding to the high-gloss milky white decorative section 2. The center distance between the two cavities matches the radius of the turntable. b. Cavity polishing inspection: Confirm that the polishing accuracy of the first cavity mirror surface Ra≤0.01μm, the polishing direction is along the demolding direction, and there are no scratches, pinholes, or orange peel texture; c. Temperature control system startup: The first cavity mold temperature is set to 100-120℃±2℃, and the temperature is controlled by a spiral cooling water channel with a channel diameter of 8-10mm and a spacing of 20-25mm. The second cavity mold temperature is set to 70-90℃±2℃, and the temperature is controlled by a ring cooling water channel with a channel diameter of 6-8mm and a spacing of 15-20mm. Combined with the regional local temperature control module, the temperature is set to 180-200℃±5℃, and controlled by embedded heating rods and thermocouples. (III) First injection molding: a. Barrel temperature settings: First stage 240-250℃±5℃, Second stage 250-260℃±5℃, Third stage 260-270℃±5℃, Nozzle temperature 270-280℃±5℃; b. Injection parameter settings: Injection speed is 50-80mm / s, controlled in 3 stages: 30-40mm / s in the initial stage, 50-80mm / s in the middle stage, and 20-30mm / s in the final stage; injection pressure is 90-110MPa, linearly adjusted with the filling stage; holding pressure is 85MPa±5MPa, divided into 2 stages: 85MPa in the initial stage and 75MPa in the final stage; holding time is 5-8s±1s; back pressure is 5-8MPa. c. Cooling and shaping: The cooling time is 15-25s±2s. The temperature of the high-gloss black substrate 1 is reduced to 80-100℃ through the cooling water channel of the first cavity to ensure shaping but not complete cooling. The cavity pressure is maintained at 5-10MPa during the cooling process. (iv) Mold rotation and station switching: a. Turntable drive: The injection molding machine turntable rotates 180° at a speed of 5-10r / min for 2-3s, transferring the molded high-gloss black substrate 1 from the first cavity to the alignment position of the second cavity, with an alignment accuracy of ±0.02mm; b. Cavity cleaning: The second cavity and the bonding area of ​​the high-gloss black substrate 1 are cleaned with compressed air at a pressure of 0.5-0.8MPa and a filtration accuracy of 0.1μm to remove surface dust and debris. (v) Second injection molding: a. Barrel temperature settings: First stage 230-240℃±5℃, Second stage 240-250℃±5℃, Third stage 250-260℃±5℃, Nozzle temperature 260-270℃±5℃; b. Injection parameter settings: Injection speed is 30-50mm / s, controlled in 2 stages: 30-40mm / s in the initial stage and 20-30mm / s in the final stage; injection pressure is 70-90MPa; holding pressure is 65MPa±5MPa, controlled in 2 stages: 65MPa in the initial stage and 55MPa in the final stage; holding time is 3-5s±1s; back pressure is 3-5MPa. c. Combined with regional temperature control: The temperature of the bonding area of ​​the high-gloss black substrate 1 is maintained at 180-200℃ through the local temperature control module to ensure that the second injection melt forms molecular diffusion with the substrate surface. The cooling time is 10-15s±2s, which reduces the overall temperature of the decorative strip to 60-80℃. (vi) Ejection, demolding, and post-processing: a. Ejection control: Activate the concealed ejection mechanism. The ejector pins are 3-5mm in diameter and number 6-8. They are distributed on the back of the high-gloss black substrate 1 at the reinforcing ribs. The ejection speed is 10-15mm / s and the ejection force is 20-30kN. The product is ejected smoothly, avoiding ejector pin marks on the high-gloss surface. The depth is ≤0.001mm. b. Post-processing: Remove gates from the product, with a gate residual length ≤0.5mm, remove burrs with a burr height ≤0.01mm, then perform appearance inspection, with a high gloss surface defect detection accuracy of 0.01mm, dimensional inspection using a coordinate measuring machine with an accuracy of ±0.005mm, and performance sampling inspection.

[0021] Step (iii) adopts a point gate with a gate diameter of 1.5-2.0mm. The flow channel with a diameter of 8-10mm is set at the end reinforcing rib of the high-gloss black substrate 1 on the non-appearance surface. It adopts a circular cross section and the surface of the flow channel is polished to Ra≤0.02μm. Step (5) adopts a submarine gate with a gate diameter of 1.0-1.5mm, which is set at the end of the high-gloss milky white decorative section 2. The runner diameter is 6-8mm, and a 0.5-1.0mm step transition is provided at the connection between the runner and the cavity to avoid melt impact.

[0022] The performance sampling inspection in step (vi) includes: Light aging resistance: UVB-313 lamp irradiation was performed according to GB / T 16422.3-2014 for 2000 hours, and the yellowing index ΔYI was ≤1.0. In step 2, the mold is also equipped with an exhaust system. The exhaust grooves are 0.8-1.2mm wide, 0.01-0.02mm deep, and 10-15mm long. They are distributed at the end of the cavity and the edge of the joint area to ensure that the exhaust volume is ≥95% during the injection molding process and to avoid the generation of air bubbles.

[0023] The injection system using closed-loop control in steps (iii) and (v) monitors the melt filling process in real time through pressure and displacement sensors. When the filling pressure fluctuation exceeds ±5MPa or the displacement deviation exceeds ±0.05mm, the system automatically adjusts the parameters to ensure injection molding stability.

[0024] Working principle: (I) Structural Design Logic: Adapting to Installation Requirements and Enhancing Stability Matrix structure functional adaptation The high-gloss black substrate is designed in a C-shape to fit the curved contours of new energy vehicle bumpers, improving the fit. Its dovetail-shaped section increases the moment of inertia of the cross section, enhancing the substrate's resistance to bending and impact, and preventing deformation over long-term use. The integrated connecting plates and mounting slots on both sides directly match the bumper assembly interface, eliminating the need for additional connectors and simplifying the vehicle assembly process. At the same time, the mounting slots can be secured by elastic snaps or bolts to ensure that the decorative strip does not loosen under vehicle vibration. Two-color combined structure reinforcement The dovetail-groove stepped structure of the high-gloss black substrate and the high-gloss milky white decorative section expands the interface contact area through "two-stage interlocking": the first 1.5-2.0mm wide contact surface achieves initial mechanical interlocking, and the second 1.0mm wide contact surface forms secondary interlocking. With a precise fit gap of 0.05-0.1mm, it ensures that the high-gloss milky white PC melt can fully fill the groove during the second injection molding. After cooling, it forms a dual bond of "physical interlocking + molecular diffusion" with the high-gloss black substrate, solving the problem of weak bonding strength in traditional planar bonding. (ii) Material adaptation mechanism: balancing performance requirements and weather resistance Mechanism of action of high-gloss black PC materials Synergistic effects of core components: PC resin (90-95 parts) provides basic mechanical support; carbon black (1.5-2.0 parts, particle size 20-50nm) ensures high gloss (≥95GU) and color stability; glass fiber (3-5 parts, length 3-5mm) enhances flexural strength (≥90MPa) and heat distortion resistance (≥130℃); silicone lubricant (0.3-0.5 parts) reduces melt shear resistance during injection molding and avoids flow marks; phosphate ester flame retardant (0.5-1.0 parts) improves safety in use. Performance-oriented optimization: By controlling the melt index (10-15g / 10min) through component ratio, it is ensured that the melt can fully fill the cavity during injection molding, while taking into account both high-gloss surface formability and structural strength. Mechanism of action of high-gloss milky white PC material Core guarantee of weather resistance: Benzotriazole UV stabilizer (0.3-0.5 parts) and hindered phenolic antioxidant (0.1-0.2 parts) are compounded to absorb ultraviolet rays and inhibit oxidative degradation, achieving a yellowing index ΔYI≤1.0 after 2000h of UVB irradiation, without the need for additional UV stabilizer varnish; Visual and molding compatibility: Titanium dioxide (5-8 parts, particle size 100-300nm) ensures hiding power ≥98% and avoids showing through the base color; special white masterbatch (2-3 parts) maintains initial whiteness ≥92; melt index (8-12g / 10min) is compatible with secondary injection temperature (220-240℃) to ensure that the melt does not degrade or change color during filling, and at the same time forms a molecular diffusion layer with the surface of the high-gloss black substrate. (III) Production process synergy: Precise control ensures high gloss quality and production stability Pre-treatment: Avoiding the root causes of injection molding defects The two PC materials were dehumidified and dried at 120℃±5℃ for 4-6 hours (dew point ≤-40℃) to control the moisture content to ≤0.02%, thus avoiding defects such as silver streaks and bubbles caused by moisture absorption during injection molding, laying the foundation for high-gloss surface molding. Two-stage injection molding: segmented temperature control and parameter coordination First injection molding (high-gloss black substrate): A high mold temperature of 100-120℃±2℃ (with spiral cooling water temperature control) is used, along with segmented injection speeds of "30-40mm / s (initial stage) - 50-80mm / s (mid stage) - 20-30mm / s (final stage)" to ensure that the melt flows fully and fits the cavity (Ra≤0.01μm mirror polishing) to form a high-gloss surface; segmented pressure holding at 85MPa±5℃ (initial shrinkage compensation, final stress relief) to avoid shrinkage marks; cooling to 80-100℃ ensures that the substrate is shaped but the surface layer still has "activation" to reserve conditions for secondary bonding. Second injection molding (high-gloss milky white decorative section): Switch to mold temperature of 70-90℃±2℃ (temperature controlled by annular cooling water circuit), maintain the bonding area at 180-200℃ through heating rods to soften the surface of the high-gloss black substrate, and inject at a medium speed of 30-50mm / s (to avoid displaced substrate) to allow the milky white melt to fill the dovetail groove and form molecular diffusion with the substrate surface; hold pressure at 65MPa±5℃ to ensure sufficient gap filling, and cool to 60-80℃ to complete the double bonding. Closed-loop control: ensuring production stability The melt filling process is monitored in real time by pressure sensors (accuracy ±0.1MPa) and displacement sensors (accuracy ±0.001mm). When the pressure fluctuation exceeds ±5MPa or the displacement deviation exceeds ±0.05mm, the injection speed / pressure is automatically adjusted. At the same time, the venting system (groove width 0.8-1.2mm, depth 0.01-0.02mm) ensures that the venting volume is ≥95%, avoiding bubble defects and achieving consistency in mass production.

[0025] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A two-tone high-gloss injection-molded C-shaped decorative strip in high-gloss black and high-gloss milky white, characterized in that, include: The high-gloss black substrate (1) is made of polycarbonate modified material; the high-gloss black substrate (1) is C-shaped in general, the cross section of the high-gloss black substrate (1) is dovetail-shaped, and both sides of the high-gloss black substrate (1) are integrally provided with connecting plates (3), and the connecting plates (3) are provided with mounting grooves (4). The high-gloss milky white decorative section (2) is distributed along the length of the high-gloss black substrate (1) in three sections. The high-gloss milky white decorative section (2) and the high-gloss black substrate (1) are provided with a dovetail groove-type concave-convex stepped structure.

2. The high-gloss black and high-gloss milky white two-tone high-gloss injection molded C-shaped decorative strip according to claim 1, characterized in that, The high-gloss black substrate (1) is made of high-gloss black PC material, which includes the following components by weight: 90-95 parts PC resin, 1.5-2.0 parts carbon black, 0.3-0.5 parts silicone lubricant, 0.5-1.0 parts phosphate ester flame retardant, and 3-5 parts glass fiber; the melt index of the material is 10-15 g / 10 min, gloss ≥ 95 GU, yellowing index ΔYI ≤ 1.0 after 2000 h of UVB irradiation, and heat distortion temperature ≥ 130℃.

3. The high-gloss black and high-gloss milky white two-tone high-gloss injection molded C-shaped decorative strip according to claim 1, characterized in that, The high-gloss milky white decorative section (2) is made of high-gloss milky white PC material, which includes the following components by weight: 88-92 parts PC resin, 5-8 parts titanium dioxide, 0.3-0.5 parts benzotriazole UV stabilizer, 0.1-0.2 parts hindered phenolic antioxidant, and 2-3 parts special white masterbatch; the initial whiteness of the material is ≥92, the melt index is 8-12 g / 10 min, the hiding power is ≥98%, the yellowing index ΔYI is ≤1.0 after 2000 h of UVB irradiation, and there is no degradation or discoloration during secondary injection molding.

4. A production process for preparing the high-gloss black and high-gloss milky white two-color high-gloss injection molded C-shaped decorative strip as described in any one of claims 1-3, characterized in that, The process, employing a horizontal rotary two-color injection molding machine with an independent temperature control system and customized rotary molds, includes the following steps: (a) Material pretreatment: a. Drying of high-gloss black PC material: Put the high-gloss black PC material into a dehumidifying dryer, set the drying temperature to 120℃±5℃, the dew point temperature to ≤-40℃, and the drying time to 4-6h. After drying, the moisture content of the material should be ≤0.02%. After drying, transfer the material to an insulated hopper for later use. b. Drying of high-gloss milky white PC material: Put the high-gloss milky white PC material into another dehumidifying dryer with the same parameters as step a, ensuring that the moisture content is ≤0.02%. After drying, transfer it to an independent insulated hopper for later use. (II) Mold preheating and parameter setting: a. Rotary mold installation: Fix the customized rotary mold to the injection molding machine. The mold includes a first cavity corresponding to the high-gloss black base (1) and a second cavity corresponding to the high-gloss milky white decorative section (2). The center distance between the two cavities matches the radius of the rotary mold. b. Cavity polishing inspection: Confirm that the polishing accuracy of the first cavity mirror surface Ra≤0.01μm, the polishing direction is along the demolding direction, and there are no scratches, pinholes, or orange peel texture; c. Temperature control system startup: The first cavity mold temperature is set to 100-120℃±2℃, and the temperature is controlled by a spiral cooling water channel with a channel diameter of 8-10mm and a spacing of 20-25mm. The second cavity mold temperature is set to 70-90℃±2℃, and the temperature is controlled by a ring cooling water channel with a channel diameter of 6-8mm and a spacing of 15-20mm. Combined with the regional local temperature control module, the temperature is set to 180-200℃±5℃, and controlled by embedded heating rods and thermocouples. (III) First injection molding: a. Barrel temperature settings: First stage 240-250℃±5℃, Second stage 250-260℃±5℃, Third stage 260-270℃±5℃, Nozzle temperature 270-280℃±5℃; b. Injection parameter settings: Injection speed is 50-80mm / s, controlled in 3 stages: 30-40mm / s in the initial stage, 50-80mm / s in the middle stage, and 20-30mm / s in the final stage; injection pressure is 90-110MPa, linearly adjusted with the filling stage; holding pressure is 85MPa±5MPa, divided into 2 stages: 85MPa in the initial stage and 75MPa in the final stage; holding time is 5-8s±1s; back pressure is 5-8MPa. c. Cooling and shaping: The cooling time is 15-25s±2s. The temperature of the high-gloss black substrate (1) is reduced to 80-100℃ through the cooling water channel of the first cavity to ensure shaping but not complete cooling. The cavity pressure is maintained at 5-10MPa during the cooling process. (iv) Mold rotation and station switching: a. Turntable drive: The injection molding machine turntable rotates 180° at a speed of 5-10r / min for 2-3s, transferring the molded high-gloss black substrate (1) from the first cavity to the alignment position of the second cavity, with an alignment accuracy of ±0.02mm; b. Cavity cleaning: The second cavity and the bonding area of ​​the high-gloss black substrate (1) are cleaned by compressed air at a pressure of 0.5-0.8MPa and a filtration accuracy of 0.1μm to remove surface dust and debris; (v) Second injection molding: a. Barrel temperature settings: First stage 230-240℃±5℃, Second stage 240-250℃±5℃, Third stage 250-260℃±5℃, Nozzle temperature 260-270℃±5℃; b. Injection parameter settings: Injection speed is 30-50mm / s, controlled in 2 stages: 30-40mm / s in the initial stage and 20-30mm / s in the final stage; injection pressure is 70-90MPa; holding pressure is 65MPa±5MPa, controlled in 2 stages: 65MPa in the initial stage and 55MPa in the final stage; holding time is 3-5s±1s; back pressure is 3-5MPa. c. Combined area temperature control: The temperature of the high-gloss black substrate (1) combined area is maintained at 180-200℃ by the local temperature control module to ensure that the second injection melt forms molecular diffusion with the substrate surface. The cooling time is 10-15s±2s, and the overall temperature of the decorative strip is reduced to 60-80℃. (vi) Ejection, demolding, and post-processing: a. Ejection control: Activate the hidden ejection mechanism, with ejector pins of 3-5mm in diameter and 6-8 in number, distributed at the reinforcing ribs on the back of the high-gloss black substrate (1), ejection speed of 10-15mm / s, ejection force of 20-30kN, ejecting the product smoothly, avoiding ejector pin marks on the high-gloss surface, depth ≤0.001mm; b. Post-processing: Remove gates from the product, with a gate residual length ≤0.5mm, remove burrs with a burr height ≤0.01mm, then perform appearance inspection, with a high gloss surface defect detection accuracy of 0.01mm, dimensional inspection using a coordinate measuring machine with an accuracy of ±0.005mm, and performance sampling inspection.

5. The production process according to claim 4, characterized in that, The step (iii) adopts a point gate with a gate diameter of 1.5-2.0mm, and is set at the end reinforcing rib of the high-gloss black substrate (1) where the flow channel diameter is 8-10mm and a circular cross section is adopted. The flow channel surface is polished to Ra≤0.02μm. Step (5) adopts a submarine gate with a gate diameter of 1.0-1.5mm, which is set at the end of the high-gloss milky white decorative section (2). The runner diameter is 6-8mm, and a 0.5-1.0mm step transition is provided at the connection between the runner and the cavity to avoid melt impact.

6. The production process according to claim 4, characterized in that, The performance sampling inspection in step (vi) includes: Light aging resistance: UVB-313 lamp irradiation was performed according to GB / T 16422.3-2014 for 2000 hours, and the yellowing index ΔYI was ≤1.

0.

7. The production process according to claim 4, characterized in that, In step (2), the mold is also equipped with an exhaust system. The exhaust groove has a width of 0.8-1.2mm, a depth of 0.01-0.02mm, and a length of 10-15mm. It is distributed at the end of the cavity and the edge of the joint area to ensure that the exhaust volume is ≥95% during the injection molding process and to avoid the generation of bubbles.

8. The production process according to claim 4, characterized in that, The injection system using closed-loop control in steps (iii) and (v) monitors the melt filling process in real time through pressure and displacement sensors. When the filling pressure fluctuation exceeds ±5MPa or the displacement deviation exceeds ±0.05mm, the system automatically adjusts the parameters to ensure injection molding stability.

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