Curved-surface printed thin-wall food container, preparation method and preparation equipment

Abstract

The invention discloses a curved-surface printing thin-wall food container, a preparation method and preparation equipment, and belongs to the technical field of injection molding.The food container comprises an injection molding body layer and a printing material, and the printing material comprises a plastic printing thin film layer and a disc edge printing layer; the disc edge printing layer is made of a layered material which is rich in texture and is arranged on the plastic printing film layer back to the injection molding body layer; the printing material is extruded and deformed by the pressure melt in the injection molding process through an in-mold decal process, and is tightly attached and fixed on the injection molding body layer; the disc edge printing layer, the plastic printing film layer and the injection molding body layer are sequentially stacked, the three layers of materials jointly form a stacked deformation structure with a three-dimensional printing face, and the disc edge printing layer is of an outward exposed structure. The invention further discloses a preparation method and manufacturing equipment of the food container. By combining and improving the structure, material, process and equipment of the product, the product has high-end material texture and three-dimensional printing visual effect, and is suitable for automatic batch manufacturing.

Description

Technical Field

[0001] The invention relates to the technical field of injection molding, in particular to a curved surface printed thin-wall food container, a preparation method and a preparation device. Background Art

[0002] With the accelerating pace of life and increasing demands for hygiene and health, especially with the rise in casual activities like travel, outdoor activities, and gatherings, traditional ceramic food containers (tableware) are heavy, cannot be stacked in multiple layers, and are easily damaged, making them inconvenient to carry and use in large quantities. This has led to the emergence of a variety of disposable, injection-molded, stackable food containers (tableware), including plastic plates, boxes, and bowls. These containers primarily consist of a flat surface with a curved edge. In addition to being affordable, easy to use, safe, and environmentally friendly, these products also demand aesthetics, high quality, sufficient strength, and ease of manufacture. Food and tableware both carry significant cultural attributes, and the aesthetics, quality, and quality of tableware often directly impact the user's dining experience. While existing disposable injection-molded tableware can overcome the drawbacks of traditional tableware's heavy weight and fragility, due to limitations in the plastic material, existing in-mold injection-molded products suffer from significant shortcomings compared to traditional ceramic tableware, including inferior texture, low quality, unattractive appearance, and the inability to customize them.

[0003] Specifically, the disposable injection-molded tableware products in the prior art have poor texture, rough visual appearance, stiff touch, and low aesthetics due to the physical properties of the plastic material itself (dark gloss, low density) and processing cost limitations (low-precision molds), which easily trigger users' psychological associations of "cheap" and "unsafe". Consumers generally believe that such products are low-quality, unsightly, and low-end products. Even if some products are processed through in-mold decals or subsequent decals, heat transfer or laser printing, screen printing, etc. after injection molding, the basic material of these injection-molded products is still plastic, including various plastic printed films. Due to the cold and hard texture and low air permeability, and the fact that they are mostly used in affordable packaging and disposable products, the overall grade of the products is low, and it is still difficult to completely get rid of the inherent limitations of plastic materials. In some social application scenarios that pursue texture (such as high-end restaurants, hotel plating, social gatherings, etc.), plastic tableware has always been difficult to replace traditional tableware made of ceramic, glass, metal, etc.

[0004] In the existing in-mold molding (IML) process, a plastic film is printed, formed in a forming machine, sheared, and then placed in an injection mold to produce the finished product. However, existing curved, thin-walled injection molding equipment and processes are complex, with low automation levels and strict process requirements. This can easily lead to defects such as localized bubbles, cracks, and wrinkles in the plastic film, resulting in low product yields. Therefore, existing thin-walled food containers are often manufactured using a vacuum forming process, such as the disposable plate forming process and equipment disclosed in CN119610616 A. Some products employing injection molding technology require highly complex product and mold design to meet the process and product design requirements. For example, the easily degradable disposable plate disclosed in CN221012761 U requires a circular break line at the junction of the plate body and rim, along with a tray support, to improve product yield.

[0005] More importantly, the difficulty in balancing the low-cost, high-speed, and mass-produced production of curved injection-molded products with high-end, sophisticated printing (printing) and product quality has long been a technical challenge constraining the industry. Common issues include complex printing processes, slow injection molding speeds, and high overall costs. For example, CN108277668A discloses a method for heat transfer printing on dinner plates. This involves placing the bottom surface of the dinner plate upward, applying a heat transfer sticker to the bottom surface, heating the sticker, and then applying the printed layer to the back of the plate. This method is complex, slow, and inefficient, and requires highly transparent injection molding materials to ensure the print appears from the front of the plate. This method is not applicable if less transparent injection molding materials (or if opaque fillers are added to the plastic) are used.

[0006] In addition, the traditional in-mold lamination process for manufacturing larger tableware also presents numerous technical difficulties. The melt can easily break through the printed film, damaging the ink print (causing the print to be blurred), or causing the printed film to shift. It can also easily cause the printed film to curl, wrinkle, and warp. Air entrapment can also easily lead to defects such as film breakage and bubbles. Existing technologies, such as the in-mold lamination process disclosed in CN 115383974 A, use a special thick decorative film that is preheated and combined with specific injection molding process parameters and injection molding equipment to quickly fill the mold cavity with the plastic melt, reduce the impact of temperature on the printing ink, and reduce the warping problem of the in-mold film. However, this process, equipment, and materials are significantly complex, require high process conditions, and are slow. In addition, there are still problems that cannot be solved, such as breakage, bubbles, and wrinkles caused by local air entrapment in the film.

[0007] In summary, the existing disposable injection-molded tableware and other food containers have the problems of single product texture, easy wrinkles and bubbles on the edges of the printed film, blurred or deformed patterns, and weak bonding between the printed material and the injection molding interface due to the limitations of injection-molded plastics and printed film materials and processes. Compared with traditional ceramic tableware, there are obvious shortcomings such as poor product texture, low grade, unsightly appearance and inability to be customized. They cannot accurately present colorful and complex printed patterns and patterns, nor can they present high-end product effects such as multicultural art styles such as Chinese painting shading and Islamic gilding and silk texture. They cannot effectively replace traditional high-end tableware, let alone surpass it. At the same time, there are also problems such as backward molds, processes and preparation equipment, and difficulty in low-cost, large-scale and automated manufacturing, which makes it difficult to meet the industry's demand for high-end, low-cost disposable injection-molded food containers (tableware). Summary of the Invention

[0008] (1) Technical problems solved In view of the shortcomings of the above-mentioned products, processes, equipment and other aspects of the existing technology, as well as the industry's demand for high-end tableware products, a curved printed thin-walled food container, preparation method and preparation equipment are provided. By combining and improving the product structure, materials, processes and equipment, starting from the three dimensions of material upgrading, process optimization and texture design, a plate edge printing layer made of high-end rich texture materials and a gradient exhaust groove design are introduced, so that the product structure is simple, beautiful, lightweight, safe, and can be stacked in multiple layers, carried in large quantities, convenient and easy to use. The preparation process is simplified and the exhaust effect is good, which can greatly improve the quality, texture, grade and artistic expression of the curved printed thin-walled injection-molded food container, and achieve partial replacement and surpassing of traditional high-end tableware; at the same time, the mold device, injection molding equipment and injection molding process are collaboratively improved to reduce the requirements for plastic printed film and plate edge printing layer, improve the degree of automation and production efficiency of production equipment and processes, improve the product yield, and meet the industry's diversified needs for highly disposable injection-molded tableware products.

[0009] (2) Technical solution

[0010] A curved surface printed thin-walled food container, comprising an injection molded body layer and a printing material, wherein the injection molded body layer comprises a flat bottom and a curved surface warped edge; The printing material includes a plastic printing film layer and a disk edge printing layer; wherein the plastic printing film layer is pre-set with colors, patterns or designs and is covered on one side of the injection molded body layer after molding; the disk edge printing layer is a layered material with rich texture and is arranged at a position on the plastic printing film layer corresponding to the curved edge facing away from the injection molded body layer; The printing material is squeezed and deformed by the pressure melt during the injection molding process through the in-mold decal process, and pressed into the gradient exhaust groove of the mold core molding surface. After integral molding, it is tightly adhered and fixed to the injection molding body layer; the disk edge printing layer, the plastic printing film layer and the injection molding body layer at the curved edge position are stacked in sequence to construct multiple centrally radiating, long strip-shaped continuous gradient strips. The three layers of material together form a curved printed thin-walled food container with a stacked deformation of a three-dimensional printing surface and an outwardly exposed disk edge printing layer.

[0011] The gradient exhaust groove is a gradient exhaust groove that is sunken relative to the core molding surface, and is a channel structure directly formed by multiple gradient grooves arranged at intervals on the core molding surface; or the gradient exhaust groove is based on the convex gradient exhaust groove relative to the core molding surface, and is a channel structure formed by multiple gradient exhaust ridges arranged at intervals on the core molding surface, and the interval grooves between them; Multiple gradient venting grooves are centrally symmetrical and annularly arranged on the core molding surface corresponding to the disk edge printing layer, with a length slightly greater than the covering length of the printing material; the cross-section of a single gradient venting groove is arc-shaped, with the molding surface as the reference, and the depth or height gradually increases from the center to the outer edge, with the starting section sunken or convex by 0.1~0.3mm, and the end section gradually changes to 0.5~0.8mm, with a width of 3~10mm and a length slightly smaller than the curved warped edge; the multiple continuous gradient strips on the curved warped edge are formed by the gradient venting grooves during injection molding.

[0012] The invention also discloses a method for preparing the curved surface printed thin-wall food container and equipment for preparing the curved surface printed thin-wall food container.

[0013] Beneficial effects

[0014] 1. The present invention improves the product structure, materials, processes and equipment, introduces a disk edge printing layer made of a textured material, and arranges gradient exhaust grooves on the molding surface. Combined with the in-mold decal process, multiple continuous gradient strips with central radiation and long strips are constructed at the curved edge position. Here, the disk edge printing layer, the plastic printing film layer and the injection molded body layer are stacked in sequence. The three layers of materials together form a curved surface printed thin-walled food container with a stacked deformation of a three-dimensional printed surface and an outwardly exposed disk edge printing layer. This can ensure that the final finished product has exquisite colors, patterns and designs, and can present a variety of artistic styles and high-end product textures such as hot stamping and silk, greatly improving the quality and grade of the product, making the product rich in texture, artistic and beautiful, and high-end, and can support various personalized customization needs; by simplifying the overall structure and manufacturing process of the product, and combining it with automated manufacturing equipment, the product can be produced in large quantities efficiently, quickly and at low cost, which can meet the industry's diversified needs for high-end food container products.

[0015] 2. The present invention introduces gradient venting grooves to construct a continuous gradient strip and multi-layer printing structure, synergistically improving the product structure, injection mold, injection molding materials, and process. The three-layer structure works together to achieve the use of conventional plastic printing film, high-end materials, and conventional injection molding equipment and processes to obtain high-end tableware products with front or back printing, beautiful surface, safe use (printing ink is double-layered), and high strength. At the same time, the overall product manufacturing process is simple, easy to automate, and can be quickly mass-produced, significantly reducing manufacturing costs.

[0016] 3. The present invention solves the technical contradiction between improving the material texture and grade of curved surface printed thin-walled injection-molded food containers and the complex manufacturing process and high manufacturing cost. Gradient exhaust grooves are designed on the core molding surface, and at the same time, the technical problems of local bubbles, deformation, blurring, wrinkles or damage that are prone to occur in plastic printed films during injection molding are solved; the introduction of a high-end disk edge printing layer with high-quality (non-plastic) texture completely solves the problem that the plastic printed surface cannot accurately present colorful and complex printed patterns and designs. The use of high-end fabrics such as silk and rice paper can perfectly present special cultural and artistic styles such as Chinese painting shading and Islamic gilding, and has a high-end texture. After the product is injection molded, no post-processing (printing, hot stamping, etc.) is required. The process is simple, the cost is low, and it can be quickly and mass-produced.

[0017] 4. The present invention can improve the overall texture of the product, overcome the single texture, and make the product high-end by adding a disk edge printing layer with rich texture; on the other hand, during the injection molding process, it is pressed into the gradient exhaust groove together with the plastic printing film layer, thereby increasing the thickness and strength of the printing material, avoiding displacement, air entrapment, bubbles and wrinkles in the plastic printing film, preventing the printing ink from escaping, increasing the bonding strength between the printing film layer and the surface of the injection molding body layer, and improving the strength of the curved edge part and the surface friction when the user holds it, further improving the beauty, safety and ease of use of the product.

[0018] 5. The present invention ensures the quality of the product, improves the high-end texture and artistic expression of the product, improves the production efficiency and yield rate of the product, and improves the overall competitiveness of the product through the combined design of injection molding material and covering surface, the symmetrical design of gradient exhaust grooves and continuous gradient strips, the composite design of printing materials, and the coordinated design of mold device, multiple manipulators and PLC automatic control. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a bottom view of the structure of a curved printed thin-walled food container according to Example 1 of the present invention; Figure 2 This is a bottom-up structural diagram of the injection-molded body layer of Example 1 of the present invention; Figure 3This is a schematic top view of the structure of the injection-molded body layer of Example 1 of the present invention; Figure 4 This is a schematic diagram of the three-dimensional appearance structure of the injection-molded body layer of Example 1 of the present invention; Figure 5 This is a schematic diagram of the main structure of a food container product according to embodiment 1 of the present invention; Figure 6 for Figure 5 Schematic diagram of the cross-sectional structure of AA; Figure 7 for Figure 6 Schematic diagram of the local enlarged structure at C in the middle; Figure 8 for Figure 5 BB cross-sectional structure diagram in; Figure 9 for Figure 8 Schematic diagram of the local enlarged structure at D in the middle; Figure 10 This is a schematic top view of the structure of a curved printed thin-walled food container according to Example 2 of the present invention.

[0020] Figure 11 This is a schematic diagram of the bottom-up structure of the injection-molded body layer of Example 2 of the present invention.

[0021] Figure 12 This is a schematic diagram of the top view of the injection-molded body layer of Example 2 of the present invention.

[0022] Figure 13 This is a schematic diagram of the three-dimensional structure of the injection-molded body layer of Example 2 of the present invention.

[0023] Figure 14 This is a schematic diagram of the main structure of a curved printed thin-walled food container according to Example 2 of the present invention; Figure 15 for Figure 14 Schematic diagram of the cross-sectional structure of AA; Figure 16 for Figure 15 Schematic diagram of the structure at C in the middle; Figure 17 for Figure 14 BB cross-sectional structure diagram in; Figure 18 for Figure 17 Schematic diagram of the structure at point D in the middle.

[0024] Figure 19 This is a schematic diagram of the main structure of a curved printed thin-walled food container according to Example 3 of the present invention; Figure 20 for Figure 19 A schematic diagram of the partially enlarged structure of the cross section at point A; Figure 21This is a schematic diagram of the main structure of a curved printed thin-walled food container according to Example 4 of the present invention; Figure 22 for Figure 21 A schematic diagram of the partially enlarged structure of the cross section at point A; Figure 23 This is a schematic diagram of the main structure of the injection-molded body layer of Example 5 of the present invention; Figure 24 This is a schematic top view of the structure of the injection-molded body layer of Example 5 of the present invention; Figure 25 This is a schematic diagram of the main structure of the injection-molded body layer of Example 6 of the present invention; Figure 26 This is a schematic top view of the structure of the injection-molded body layer of Example 6 of the present invention; Figure 27 This is a schematic diagram of the overall structure of the injection molding manufacturing equipment according to an embodiment of the present invention; Figure 28 This is a schematic diagram of the three-dimensional assembly structure of the mold device according to embodiment 1 of the present invention from a first viewing angle; Figure 29 This is a schematic diagram of the three-dimensional assembly structure of the mold device according to embodiment 1 of the present invention from a second viewing angle; Figure 30 This is a schematic diagram of the three-dimensional assembly structure of the mold assembly from a first perspective according to Example 2 of the present invention; Figure 31 This is a schematic diagram of the three-dimensional assembly structure of the mold device of Example 2 of the present invention from a second viewing angle.

[0025] In the picture: 1. Thin-walled food container with curved printing; 11. Injection molding body layer; 12. Continuous gradient strips; 13. Continuous gradient grooves; 14. Flat round bottom; 15. First curved surface warping edge; 16. Second curved surface warping edge; 17. Flat elliptical bottom; 18. Flat square bottom; 2. Printing material; 21. Plastic printing film layer; 22. Plate edge printing layer; 3. Moving die set; 31. Fixed die set; 32. Guide rail; 4. Feeding robot; 41. Loading robot; 42. Unloading robot; 43. Slide rail; 5. Injection molding machine; 51. Ceiling; 52. Floor; 6. Fixed mold panel; 61. Fixed mold A plate; 62. Fixed mold core; 64. Fixed mold stripper plate; 65. Sprue bushing; 66. Moving mold bottom plate; 67. Gradient exhaust groove; 63. Moving mold B plate; 68. Nozzle; 69. Moving mold core; 7. Auxiliary demoulding mechanism. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] The following is a detailed description with reference to the accompanying drawings and multiple embodiments.

[0028] Basic Example See Figure 1 、 Figure 2 The curved surface printed thin-walled food container 1 provided in this embodiment includes an injection molded body layer 11 and a printed material 2. The injection molded body layer 11 includes a flat bottom (including a flat round bottom, a flat elliptical bottom, or a flat square bottom, etc.), a curved surface warping edge (including a first curved surface warping edge, a second curved surface warping edge, a third curved surface warping edge, etc.); The printed material 2 includes a plastic printed film layer 21 and a disk edge printed layer 22. The plastic printed film layer 21 is pre-set with a color, pattern, or design and is covered on one side of the injection molded body layer 11 after molding. The disk edge printed layer 22 is a textured, annular layered material and is disposed on the plastic printed film layer 21 at a position corresponding to the curved edge, facing away from the injection molded body layer 11. The printing material 2 is squeezed and deformed by the pressure melt during the injection molding process through the in-mold decal process, and pressed into the gradient exhaust groove 67 on the core molding surface of the mold. After integral molding, it is tightly adhered and fixed to the injection molding body layer 11; the disk edge printing layer 22, the plastic printing film layer 21 and the injection molding body layer 11 at the curved edge position are stacked in sequence to construct multiple centrally radiating, long strip-shaped continuous gradient strips 12 (similar to the ridge or groove structure of the sun pattern). The three layers of material together form a curved printed thin-walled food container 1 with a stacked deformation of a three-dimensional printing surface and an outwardly exposed disk edge printing layer.

[0029] The plastic printed film layer 21 is a transparent, translucent or opaque film made of a plastic substrate such as PP (HMSPP), PS, PET or PA with single-sided printing. The opaque film may be a metallic coated plastic printed film. The thickness is 0.03-0.06 mm. If it is too thick, it is easy to wrinkle; if it is too thin, it is easy to be broken by the molten adhesive. The thermal shrinkage rate is ≤1%. The plastic printed film layer 21 is entirely covered on the front or back of the injection molding body layer 11. The covered surface includes two parts: the curved warped edge and the flat bottom. During injection molding, it is located between the injection molding body layer 11 and the disk edge printed layer 22, and its printed surface is connected to the injection pressure melt.

[0030] The edge-printed layer 22 is a textured, thin sheet material with pre-set colors, patterns, or designs. The material may be made from a variety of textured textiles, non-woven fabrics, metal foils, hot stamping films, specialty papers, leather, or metal-coated composite materials. A textured material presents a multi-layered and varied sensory experience under varying angles, lighting, forces, or touch. It's not a single sensation, but a combination of sensations rich in contrast and transitions, offering a rich and varied experience across multiple dimensions, including tactile (thickness, hardness, coldness, warmth), and visual (gloss, color, and transparency).

[0031] The plate edge printing layer 22 is located at the position corresponding to the warped edge of the curved surface, and is pre-compounded (heat-sealed, bonded, etc.) on the plastic printing film layer to form a printing material 2; during the injection molding process, it is pressed into the gradient exhaust groove 67 together with the plastic printing film layer 21 to form a continuous gradient strip 12, and a three-layer structure is formed on the warped edge of the curved surface, with the plate edge printing layer 22 exposed outward, the plastic printing film layer 21 in the center, and the injection molding body layer 11 inside, having rich texture and three-dimensional visual effect.

[0032] The injection-molded body layer 11 is an open structure having at least one flat bottom surface and a curved warped edge, wherein the curved warped edge is a curved surface composed of at least one arc surface of curvature, or a curved surface composed of multiple arc surfaces of curvature connected to each other, and the variation range of the curvature radius between two adjacent arc surfaces is ≤10%; The injection-molded main body layer 11 is a structural layer formed by injection molding of the injection molding material, and the thickness of the flat bottom portion thereof is 0.9-1.1 mm, the center thickness / average thickness ratio of the flat bottom is between (1.3-1.65):1, and the thickness / diameter ratio is greater than 1 / 200; The injection molding materials include: PCTG (poly(1,4-cyclohexanedimethanol terephthalate), general-purpose polystyrene GPPS (transparent), high-impact polystyrene HIPS (opaque), modified PP-type polypropylene plastic, degradable polylactic acid (PLA), poly(butylene terephthalate-adipate) (PBAT), poly(butylene terephthalate) (PBT), polyhydroxybutyrate (PHB) or poly(butylene succinate) (PBS), or other suitable thermoplastic injection molding materials.

[0033] The curved printed thin-walled food container can specifically be an open, one-time injection-molded curved printed thin-walled dinner plate, dinner bowl, dinner dish, lunch box or other food container; wherein, the shape, specification and size of the injection-molded main body layer 11, the plastic printed film layer 21 of the printing material 2 and the plate edge printed layer 22 can all be customized as needed, and can support various personalized customization needs.

[0034] See Figure 27The present embodiment provides a device for preparing a curved surface printed thin-walled food container, which is used to prepare the curved surface printed thin-walled food container, or to implement the following preparation method, which includes: A PLC controller (not shown), an injection molding machine 5, a mold assembly, a loading robot 41, an unloading robot 42, and a feeding robot 4; the injection molding machine 5 is disposed on one side of the mold assembly and is connected to the mold assembly via an injection pressure pipeline, and injects molten plastic into the mold cavity of the mold assembly during injection molding; See also Figure 28 and Figure 29 The mold device includes: a movable mold group 3, a fixed mold group 31, a clamping cylinder, and a guide rail 32; the clamping cylinder is arranged on the movable mold group, and the movable mold group is arranged on the guide rail 32. The movable mold group 3 and the fixed mold group 31 are correspondingly provided with guide pins and guide sleeves, and relatively provided with a fixed mold core 62, a movable mold core 69, a molding surface and a release surface; a gradient exhaust groove 67 is provided on one side of the fixed mold core 62 or the movable mold core 69 facing the mold cavity, and an auxiliary demolding mechanism 7 (air top or other telescopic pushing mechanism) is also provided; a nozzle 68 is provided at the center position of the molding surface of the molding core on the side that is not in contact with the printing material.

[0035] When the back side of the main body layer 11 is injection molded with appliques, the gradient exhaust groove 67 is arranged on the molding surface of the movable mold core 69, the nozzle 68 and the auxiliary demoulding mechanism 7 are both arranged on the fixed mold core 62, and the pressure melt is injected into the mold cavity from the nozzle 68 arranged at the center position of the molding surface of the fixed mold core 62; when the front side of the main body layer 11 is injection molded with appliques, the gradient exhaust groove 67 is arranged on the molding surface of the fixed mold core 62, the nozzle 68 and the auxiliary demoulding mechanism 7 are both arranged on the movable mold core 69, and the pressure melt is injected into the mold cavity from the nozzle 68 arranged at the center position of the molding surface of the movable mold core 69.

[0036] The feeding robot 4, loading robot 41, and unloading robot 42 are respectively arranged on one side of the mold device, and each includes a robot arm and a material removal fixture. The upper ends of the robot arms of the loading robot 41 and the unloading robot 42 are fixed to two slide rails 43 on the ceiling 51, and the material removal fixture (including the vacuum suction cup) at the lower end of the robot arm is suspended and arranged around the forming mold core. The robot arm completes the loading and unloading actions respectively through its own up and down movement and forward and backward movement (along the slide rail 43), rotation, etc.; the material removal fixture at the lower end is suspended and arranged around the forming mold core. The feeding robot 4 is arranged on the outside of the loading robot, and uses a suction cup to suck one or more pages from the compounded printing material pile, so that the printing material is charged with static electricity and then transferred to the loading robot 41; in some embodiments, the feeding robot 4 may not be provided, and the loading robot 41 directly picks up one or more pages of printing material from the pile, charges them with static electricity and then feeds them into the mold device, but this will reduce the overall manufacturing speed.

[0037] The feeding robot 4 is arranged outside the loading robot 41, and sucks one (or more) pages of printing material from the compounded printing material pile with a vacuum suction cup, charges the printing material with static electricity, and then transfers it to the loading robot with the vacuum suction cup; The PLC controller is respectively connected to the injection molding machine 5, the mold device, the loading robot 41, the unloading robot 42, the feeding robot 4, the mold clamping cylinder, and the auxiliary demoulding mechanism 7 to control their coordinated operation.

[0038] The equipment for preparing curved printed thin-walled food containers provided in this embodiment also includes conventional electricity, power parts and auxiliary mechanisms, components, etc. that constitute the injection molding equipment to enable it to perform injection molding production at high speed and automatically. These are conventional technologies and will not be listed one by one.

[0039] A method for preparing the curved surface printed thin-walled food container comprises the following steps: S1. Preparation of printing materials Prepare the plate edge printing layer 22, set the color or pattern on the thin sheet material layer with rich texture, and cut it into rings; Prepare a plastic printed film layer 21, cut the printed plastic film with a pattern into a shape slightly smaller than the surface to be covered by the injection-molded main layer, and leave a venting gap at the outer edge of the covered surface; The annular disk edge printing layer 22 is laminated on the position of the plastic printing film layer 21 corresponding to the curved edge to form the printing material 2; S2. Mold preparation A mold device and a jig are prepared separately. The mold device includes a fixed mold group and a movable mold group. The fixed mold group includes a fixed mold core, and the movable mold group includes a movable mold core. At least on the molding surface of the fixed mold core or one of the movable mold cores, there are multiple gradient exhaust grooves that are centrally symmetrical and spaced apart; and on the release surface surrounding the periphery of the molding surface, an annular exhaust channel is provided close to the far end of the gradient exhaust groove or directly connected to the gradient exhaust groove; on the molding surface of the fixed mold core 62 or the movable mold core 69, near the edge, there are centrally symmetrical, strip-shaped gradient exhaust grooves, the center lines of which all point to the center of the circle, are spaced apart from each other, surround the mold core surface near the edge, and cover the last filling area of ​​the thin-walled curved surface, including the apex, Edge dead corners and other locations prone to air trapping; the depth of each gradient exhaust groove can be selected from 0.1-0.3mm to prevent flash, and the width can be selected from 5-10mm, extending along the edge of the cavity and the periphery of the printing material coverage area to ensure that the gas in the cavity is quickly discharged; the depth of each gradient exhaust groove gradually increases from the center to the outer edge, with a gradient groove of 0.1-0.3mm at the starting section and 0.5-0.8mm at the end section, which can be obtained by CNC milling, electric spark machining and other methods; if the short-term flow rate of the exhaust channel is insufficient, it is easy to cause quality defects such as molten glue burning, bulging and wrinkling of the printing material; the edge printing layer is set at the position of the curved edge corresponding to the plastic printing film, which can also enhance the strength of the plastic printing film at this position and improve the yield rate; S3, In-mold Lamination A jig equipped with an electrostatic generator is used by a feeding robot or a loading robot to suck one or more pages of printing material at a time (corresponding to the number of cavities in the mold device) and feed the statically charged printing material into the mold. One side of the plastic printing film with a disc-shaped printing layer faces away from the cavity, while the other side faces the cavity and is tightly attached to the molding surface of the mold core. After the plastic printing film is attached to the molding surface, a blank molding surface is left near the edge of the molding surface for outer edge exhaust to prevent the printing material from blocking the exhaust channel and causing air trapping defects. S4, mold closing and injection molding The movable die set and the fixed die set are combined to form a thin-walled cavity between the core of the movable die set and the core of the fixed die set; After mold closing, the injection molding machine injects plastic pressure melt into the mold cavity. The pressure melt contacts and melts the printed surface of the plastic printing film. At the same time, the pressure melt presses the printing material tightly onto the molding surface of the mold cavity. The plastic printing film and the disk edge printing layer corresponding to the curved warping part are simultaneously pressed into the gradient exhaust groove to avoid displacement, air entrapment, bubbles and wrinkles of the printing material during the injection molding process, thereby increasing the bonding strength between the printing film layer and the surface of the injection molding body layer. After pressure holding and cooling and shaping, the printing material and the injection molding body layer form multiple long continuous gradient strips with the disk edge printing layer exposed outward at the curved warping position, thereby increasing the texture and strength of the curved warping part and the surface friction when the user holds it. S5. Demolding and blanking: After the mold is opened, the formed food container is taken out from the mold to obtain a curved surface printed thin-walled food container.

[0040] The main process parameters in each preparation step include: 1. The mold injection port (nozzle) and valve needle are recommended to have a diameter of 6-8mm; 2. Generally, the center thickness increases to 0.9-1.1mm; 3. Generally, the container injection molding thickness / diameter>1 / 200; 4. The curvature change between two adjacent surfaces in the warping should be within 10 degrees; 5. When laminating the front side, it is recommended to use PP, PS or PA plastic printed film. The back side can be further laminating with other plastic printed films. The plastic printed film and the plate edge printed layer can be transparent, opaque or translucent material layers.

[0041] 6. The thickness of the plastic printing film is between 0.02 and 0.06 mm; the thickness of the plate edge printing layer is between 0.5 and 0.8 mm; the total thickness of the printing material matches the depth of the gradient exhaust groove and is less than the depth of the gradient exhaust groove; 7. The center thickness of the container / the average thickness of the tray container is between 1.3 / 1 and 1.65 / 1.

[0042] Other specific processes and parameters of injection molding and in-mold applique can be selected using conventional technology based on the product structure design and the characteristics of the injection molding material.

[0043] Example 1 See also Figures 1 to 9 The embodiment of the present invention is a specific selection based on the aforementioned basic embodiment, specifically providing a high-end printed glossy 10.25-inch round dinner plate molded in one step. A decal is applied to the back of the injection-molded body with an overall round outline. The injection molding material used is a transparent PCTG (polyethylene terephthalate-1,4-cyclohexanedimethanol) plastic printed film layer, which is a PP plastic printed film. The plate edge printed layer is made of high-end PU artificial leather. The plate edge printed layer 22 is exposed on the outer side of a curved edge 15 (the back of the container). When a user takes the dinner plate, the plate edge printed layer 22 is easily observed and touched, thereby allowing the user to perceive the high-end texture of the product.

[0044] A curved printed thin-walled food container 1 (glossy injection-molded dinner plate) comprises an injection-molded main layer 11 and a printed material. The injection-molded main layer 11 (made of transparent PCTG plastic) is an open, true circular structure having a flat circular bottom 14 and a first curved warped edge 15. The first curved warped edge 15 is formed by an arc surface with a curvature, forming the dinner plate. The injection-molded main layer 11 is formed of injection-molded material. The thickness of the flat bottom is 0.9-1.1 mm. The center thickness / average thickness ratio of the flat circular bottom 14 of the dinner plate is 1.5:1, and the thickness / diameter ratio of the dinner plate is approximately 1 / 250.

[0045] The PP plastic printed film layer 21 is pre-set with colors, patterns or designs. After molding, it is covered on the outer surface (back) of the transparent injection-molded main layer 11 as a whole, with only gaps left at the edges to facilitate smooth air exhaust during molding and avoid wrinkles in the plastic printed film layer; the disk edge printed layer 22 is made of artificial leather fabric with rich texture and is annular. It is arranged on the plastic printed film layer 21 with its back facing the injection-molded main layer 11. After molding, its upper end face is exposed on the inner surface (back) of the injection-molded main layer 11, which is easy to observe and touch; at the same time, the disk edge printed layer 22 of artificial leather fabric with a certain thickness and strength is pre-combined with the plastic printed film layer 21, which can also enhance the strength of the printed material corresponding to the first curved edge 15 position, further preventing defects such as bubbles and wrinkles.

[0046] The plastic printed film layer 21 used in this embodiment is specifically a transparent PP printed film with a HMSPP substrate printed on one side, which includes a printed surface and a non-printed surface, with a thickness of 0.03~0.06mm. If it is too thick, it is easy to wrinkle, and if it is too thin, it is easy to be broken by the molten glue; the thermal shrinkage rate is ≤1%, and it is compatible with the injection pressure melt material PCTG (or PS, etc.); it is entirely covered on the back of the injection body layer 11, and the covered surface includes a flat round bottom 14 and a first curved warped edge 15, and is pressed between the disk edge printed layer 22 and the first curved warped edge 15, with a radius slightly smaller than the front of the injection body layer 11, and an exhaust gap is left at the edge of the molding surface of the movable mold core 69 corresponding to the back of the injection body layer 11.

[0047] The disk edge printing layer 22 used in this embodiment is a layer of artificial leather sheet material with rich texture (microfiber polyurethane (PU) synthetic leather (thickness 0.3~0.5mm), and a pattern is pressed or printed on the sheet material layer. It is pre-bonded to the position of the plastic printing film layer 21 corresponding to the first curved surface warping edge 15. During the injection molding process, it is pressed into the gradient exhaust groove together to form a continuous gradient strip 12 (ridge), which has a multi-layer structure, a three-dimensional visual effect and a decorative curved surface warping edge with a strong texture, and finally forms an integrated injection-molded curved surface printed thin-walled food container 1 with rich texture and decoration. In other embodiments, polyvinyl chloride (PVC) artificial leather or polyethylene (PE) artificial leather can also be selected to prepare the disk edge printing layer 22.

[0048] The printed material is squeezed and deformed by the pressure melt during the injection molding process through the in-mold decal process, and pressed into the gradient exhaust groove 67 on the core molding surface of the mold. After integral molding, it is tightly adhered and fixed to the injection molding body layer 11, forming a plurality of centrally radiating, long continuous gradient strips 12 (specifically, continuous gradient ridges) at the position of the first curved surface warping edge 15. The disk edge printing layer 22, the plastic printing film layer 21 and the injection molding body layer 11 are stacked in sequence. The three layers of materials of different materials together form a curved printed thin-walled food container 1 with a stacked deformation of a three-dimensional printed surface and an outwardly exposed structure of the disk edge printing layer 22, that is, a one-time injection molded soft leather feel dinner plate.

[0049] In this embodiment, the formed curved surface printed thin-walled food container 1 has a PP plastic printed film layer 21 covering the back of the injection molded body layer 11 and pre-printed with patterns and designs simulating natural marble. The PP plastic printed film layer can be seen from the front of the product through perspective. The edge printed layer 22 is PU artificial leather, pre-pressed or printed with a granite cross-section pattern, annular in shape, and disposed on the plastic printed film layer 21. The position, shape, and area all correspond to the continuous gradient strip 12 on the first curved surface warped edge 15. The PU artificial leather material layer of the edge printed layer 22 is connected to the injection molded body layer 11 through the plastic printed film layer 21. It is always located on the outer surface of the plastic printed film layer 21 at a position corresponding to the curved surface warped edge, covering the PP plastic printed film layer and the injection molded body layer when the user holds it, making it easier for the user to observe and touch. This gives the product the soft leather texture and three-dimensional printed visual effect of a high-end product, significantly improving the overall quality and grade of the product. The texture of the printed material with leather in this embodiment is significantly enhanced compared to the printed material with only a PP plastic printed film layer (comparison material). After comparative testing, the printed material has been significantly improved in terms of vision, touch, and sensory experience. The quantification of this enhancement effect requires a combination of objective physical parameter testing and subjective sensory evaluation results, as shown in Table 1 below.

[0050] Table 1

[0051] In this embodiment, the gradient exhaust groove 67 is set to a structure with a gradually increasing depth from the center to the edge. It is set on the movable mold core 69 and is a gradient exhaust groove that is sunken relative to the molding surface of the movable mold core 69. The channel structure is directly formed by multiple gradient grooves that are spaced apart on the molding surface of the movable mold core 69. The multiple gradient exhaust grooves 67 are centrally symmetrical and annularly arranged on the molding surface position of the movable mold core 69 corresponding to the disk edge printing layer 22. The center lines of the multiple gradient exhaust grooves 67 all point to the center of the circle. The length is slightly larger than the covering length of the printing material and slightly smaller than the curved edge, so as to smoothly Exhaust; The cross section of a single gradient exhaust groove is arc-shaped. Taking the molding surface as the reference, the initial section has a sink depth of 0.3mm, the final section gradually deepens to 0.8mm, the width is 5~8mm, and it is narrow in the front and gradually wide in the back; each gradient exhaust groove 67 faces one end (far end) of the parting surface of the fixed mold core 62, and is close to the exhaust channel of the parting surface of the movable mold core 69, or is connected to the exhaust channel, so as to smoothly discharge the gas in the cavity during the injection molding process, avoid the occurrence of local trapped air, bubbles, wrinkles and other quality defects, and form a beautiful and complete continuous gradient strip 12 (ridge).

[0052] The multiple continuous gradient strips 12 on the curved warped edge of the curved printed thin-walled food container 1 are formed by the corresponding long gradient exhaust grooves 67 on the molding surface of the movable mold core 69 on one side of the printed surface during injection molding. During the injection molding process, under the extrusion of the injection pressure melt, each gradient exhaust groove 67 positions, guides deformation, accommodates and exhausts the disk edge printing layer 22 and the plastic printed film layer 21, and guides the disk edge printing layer 22 and the plastic printed film layer 21 to be pressed into the gradient exhaust grooves 67 at the same time; after shaping, the continuous gradient strips 12 limit and support the deformed disk edge printing layer 22 and the plastic printed film layer 21, thereby improving the texture, mechanical strength, surface friction and visual effect of the curved warped edge.

[0053] See also Figures 27 to 29 The equipment for preparing curved printed thin-walled food containers provided in this embodiment comprises a PLC controller, an injection molding machine 5, a mold assembly, a feeding robot 4, a loading robot 41, an unloading robot 42, and other conventional auxiliary components, all of which are the same as those in the basic embodiment; the difference lies in the following specific selections based on the product structure and process requirements of the double-layer front decal: The movable mold group 3 includes: a movable mold bottom plate 66, a movable mold B plate 63, and a movable mold core 69. The side of the movable mold core 69 on the movable mold B plate 63 facing the cavity (fixed mold group) is the front molding surface, and a plurality of gradient exhaust grooves 67 arranged symmetrically with the center are provided on the front molding surface; the fixed mold group includes: a fixed mold panel 6, a fixed mold A plate 61, a fixed mold core 62, a fixed mold stripper plate 64, a sprue sleeve 65, and a nozzle 68; the nozzle 68 passes through the sprue sleeve 65 and is arranged at the center position of the circle of the rear molding surface of the fixed mold A plate 61. At the same time, an auxiliary demoulding mechanism 7 (an air cap mechanism in this embodiment) is also provided on the molding surface of the fixed mold core 62; during injection molding, the printing material is first attached to the front molding surface of the movable mold core 69, and the artificial leather material layer contacts the gradient exhaust groove 67 on the movable mold core 69, and the printing surface of the plastic printing film layer contacts the pressure melt. The injection molding body layer formed after injection molding tightly combines the printing material on its front surface.

[0054] The aforementioned method for producing a thin-walled food container with curved printing employs the aforementioned preparation equipment and specifically includes the following steps based on the basic embodiment: S1. Preparation of printing materials S1-1 Preparation of plastic printed film Marble colors, patterns, or designs are printed on one side of a 0.03-0.06mm thick HMSPP film substrate, followed by corona treatment. The corona value on the printed side is 38-42 dyn / cm, and on the non-printed side is 32-34 dyn / cm, improving adhesion to the modified PP material while preventing melt slip during injection molding. S1-2 Preparation of disk edge printing layer On a thin sheet material of rich texture, artificial leather fabric (microfiber polyurethane PU synthetic leather, thickness 0.3-0.5mm), the color, pattern and design imitating the cross section of red granite are pre-pressed or printed, and then cut into rings to obtain a disk edge printing layer; in other embodiments, polyvinyl chloride (PVC) artificial leather or polyethylene (PE) artificial leather can also be selected; S1-3 two-layer composite Laminating the disk edge printing layer on the position of the plastic printing film corresponding to the warped edge of the curved surface to obtain a printing material; In this embodiment, a solvent-based polyurethane (PU) coating is used to pre-bond the back of the artificial leather material to the non-printed surface of the plastic printing film layer 21 to obtain a composite printing material. The bonding material is a water-based PU adhesive. The operation steps are as follows: first, use a fine brush or scraper to apply a thin layer of PU adhesive to the PP plastic printing film; when it is half dry, adhere it to the back of the artificial leather material, and dry it at a low temperature of 80°C or naturally cure it for 24 hours.

[0055] S1-4 coating modified resin A layer of viscous resin coating or powder compatible with the injection molding material is applied on the printed surface of the marble pattern of the plastic printing film facing the cavity to form a transition layer to strengthen the interface bonding ability and buffer the impact of the injection pressure melt on the printing ink.

[0056] S2. Mold preparation The S2-1 mold device includes a fixed mold group 31 and a movable mold group 3 and their mold frames. The fixed mold group includes a fixed mold panel 6, a fixed mold A plate 61, a fixed mold stripper plate 64, a sprue sleeve 65, a fixed mold core 62, and a nozzle 68. The movable mold group includes a movable mold core 69, a movable mold B plate, and a movable mold bottom plate 66. The front molding surface of the movable mold core 69 is provided with a plurality of gradient exhaust grooves 67 that are centrally symmetrical and spaced apart. An annular exhaust channel is provided near the far end of the gradient exhaust groove 67 on the release surface surrounding the molding surface. A cavity for a curved printed thin-walled food container 1 is formed between the fixed mold core 62 and the movable mold core 69. The nozzle 68 is arranged at the center of the rear molding surface of the fixed mold A plate 61 through the sprue sleeve 65. The auxiliary demoulding mechanism 7 (air cap) is also provided on the fixed mold core 62, located on the outside of the nozzle 68 and arranged symmetrically. S2-2 Preparation of fixture The fixture includes a feeding robot 4, a loading robot 41, a unloading robot 42, a PLC controller, a mold clamping cylinder and a slide rail 43; Among them, the feeding robot 4 and / or the loading robot 41 are provided with an electrostatic generator and a vacuum suction cup; the feeding robot 4 is provided with an electrostatic generator and a vacuum suction cup, and first picks up a page of the stacked printing material, and then discharges the electrostatic generator, so that the printing material is charged with static electricity and then conveyed to the feeding robot 4; after the vacuum suction cup of the loading robot 41 absorbs the printing material, it can discharge the electrostatic generator again, strengthen the static electricity of the printing material, and then feed it to the front molding surface (the side holding the food) of the movable mold core 69, and the printing material automatically adheres to the molding surface due to the electrostatic effect; The unloading robot 42 is used to remove the food container formed by injection molding from the mold device in cooperation with the auxiliary demoulding mechanism 7 after the mold is opened; The PLC controller is used to control the coordinated actions of the fixed die set 31, the movable die set 3, the feeding robot 4, the loading robot 41, the unloading robot 42, the mold clamping cylinder and the injection molding machine 5; The movable die set is set on the guide rail 32 as a whole. Under the drive of the mold closing cylinder, the movable die set 3 performs horizontal back and forth reciprocating motion on the guide rail 32 to close or open the mold. S2-3 are connected to each other Connect the fixed die set 31, the movable die set 3, the feeding robot 4, the loading robot 41, the unloading robot 42, the mold clamping cylinder and the injection molding machine 5 to the PLC controller respectively; The melt outlet of the injection molding machine 5 is connected to the cavity inside the mold device through a pressure pipe, a sprue sleeve 65 and a nozzle 68; S2-4 Setting Parameters The operating parameters of the injection molding machine 5, the mold clamping cylinder, the fixed mold assembly 31, the movable mold assembly 3, the feeding robot 4, the loading robot 41, the unloading robot 42, the auxiliary demoulding mechanism 7 and other parts are set in the PLC controller respectively, so as to automatically control the coordinated and automated operation of each part during production to improve production efficiency and product quality; S3, In-mold Lamination S3-1 Printing material stacking The pre-prepared printing materials are stacked in a container to form a pile; S3-2 Printing material pickup The feeding robot 4 picks up the printing materials one by one using a suction cup equipped with an electrostatic generator, corresponding to the number of cavities in a single injection molding, picking up one piece each time (in other embodiments, multiple pieces can also be picked up); S3-3 Printing material feeding The feeding robot 4 moves, picks up the printing material on its suction cup, applies static electricity, and then transports it to the loading position of the loading robot 41; S3-4 printing material in-mold labeling After the feeding robot 41 reaches the feeding position, it uses its suction cup to pick up the electrostatically printed material on the feeding robot 4 and then transfers it to the mold device, so that the printed surface of the plastic printed film layer faces the mold cavity and is tightly attached to the molding surface of the movable mold core 69, while the disk edge printed layer faces away from the mold cavity and does not come into contact with the pressurized melt during the injection molding process; After the plastic printing film is attached to the molding surface, a blank molding surface is left near the edge of the molding surface to prevent the printing material from blocking the exhaust channel and causing air trapping defects; S4 mold closing injection molding S4-1 Preheating and loading Preheating: Under the control of the PLC controller, the loading robot does not move, and the injection molding is performed 3 to 5 times to preheat the cavity to 70-80 degrees; The loading robot 41 loads the material: the vacuum suction cup on the loading robot 41 first picks up the statically charged printing material, and then makes the printing layer on the edge of the plate face away from the molding surface, and feeds it to the molding surface of the movable mold core 69, and the printing material automatically adheres to the molding surface; S4-2 mold closing and locking Mold closing: Under the control of the PLC controller, the mold closing cylinder drives the movable mold group to move toward the fixed mold group on the guide rail, so that the movable mold group and the fixed mold group are precisely fitted together, forming a thin-walled cavity between the mold core of the movable mold group and the mold core of the fixed mold group; Clamping: When the mold is completely closed, the clamping cylinder applies a clamping force that must be greater than the pressure of the melt on the cavity during injection, and 1.2 to 1.5 times the injection pressure, to ensure the cavity is sealed. S4-3 Injection Molding After the mold is closed, under the control of the PLC controller, the injection molding machine injects the PCTG plastic pressure melt into the mold cavity from the nozzle 68 at the center position of the molding surface of the fixed mold core 62; the pressure melt contacts the printing surface of the plastic printing film in the printing material and melts and combines with it. At the same time, the printing material is tightly pressed against the cavity wall by the melt pressure, and the printing material corresponding to the curved and warped part is pressed into the gradient exhaust groove, so that the printing material is prevented from displacement, air entrapment, bubbles and wrinkles during the injection molding process, thereby increasing the bonding strength between the printing material and the injection molding body layer; S4-4Pressure holding and shaping After the injection molding is completed, the pressure is maintained for 3 to 5 seconds, and then cooled and fixed for 5 to 10 seconds. The printing material forms multiple long continuous gradient strips on the printed surface of the injection molding body, and the printed layer on the edge of the plate is exposed to improve the texture of the curved edge, mechanical strength and surface friction when the user holds it; S5, demoulding and unloading S5-1, mold opening Under the control of the PLC controller, the mold closing cylinder drives the movable mold group to move away from the fixed mold group on the guide rail, so that the movable mold group and the fixed mold group are separated, exposing the injection molded product formed between the mold core of the movable mold group and the mold core of the fixed mold group; S5-2, demoulding An auxiliary demoulding mechanism 7 (air lift) is pre-installed on the molding surface of the fixed mold core 62. After the mold is opened, air is ventilated to activate the auxiliary demoulding mechanism 7, pushing the injection molded body layer outward and away from the molding surface, so that the molded food container is separated from the molding surface. S5-3, cutting The blanking robot 42 moves to take the formed food container out of the mold device to obtain a curved surface printed thin-walled food container 1.

[0057] The curved printed thin-walled food container provided in this embodiment uses embossed artificial leather + back decals, and a disc-shaped injection-molded body made of transparent PCTG plastic. A sunken continuous gradient strip is provided on the mold forming surface, and a corresponding convex ridge-shaped continuous gradient strip is formed on the warped edge of the curved surface of the product, which greatly improves the texture, grade, production automation level and product quality of the product, so that its texture and artistic expression can reach or exceed that of existing conventional porcelain material food containers, thereby improving the overall competitiveness of the product.

[0058] Example 2

[0059] See also Figures 10 to 18 , Figure 28 and Figure 29The curved printed thin-walled food container provided in the embodiment of the present invention is prepared using a method and apparatus based on the basic embodiment. Specifically, a circular disposable injection-molded curved high-end silk texture printed dinner plate is provided, comprising a transparent GPPS injection molded plate, a decal on the back of the injection-molded body, a PS plastic printed film, a silk fabric printed on the edge of the plate, and an upward convex continuous gradient strip on the second curved edge. The plate is the same as that in embodiment 1, with the following differences: The injection-molded body layer 11 is an open structure with a flat circular bottom 14, a first curved edge 15, and a second curved edge 16. The curved edge is composed of two interconnected arcs (the first curved edge 15 and the second curved edge 16), with the radius of curvature between adjacent arcs varying by 10% or less. Multiple, elongated, continuous gradient strips 12 radiating from the center are spaced apart on the second curved edge 16. These strips 12 are specifically recessed grooves, known as continuous gradient grooves 13, with a depth gradually increasing from the center to the outer edges. These grooves correspond to the gradient venting grooves 67 provided on the molding surface of the fixed mold core 62 and are formed during injection molding within the mold cavity.

[0060] The gradient exhaust groove 67 is based on a convex gradient exhaust groove on the relative core molding surface, and is a groove channel structure formed by a plurality of gradient exhaust ridges arranged at intervals on the core molding surface, and the intervals between each other; a plurality of gradient exhaust grooves 67 are formed correspondingly between two adjacent gradient exhaust ridges, which are centrally symmetrical and annularly arranged on the molding surface position of the movable mold core 69 corresponding to the disk edge printing layer 22; each gradient exhaust ridge faces one end of the movable mold core 69 parting surface, and is close to the exhaust channel of the movable mold core 69 parting surface; wherein, the cross section of a single gradient exhaust ridge is an arc shape, and with the molding surface as the reference, the height gradually increases from the center to the outer edge, the convex height of the starting section is 0.1~0.3mm, and the last section gradually increases to 0.5~0.8mm, the width is 3~10mm, the front is narrow and the back is gradually wide, and the length is 2~3mm. The degree is slightly smaller than the warped edge of the curved surface and slightly larger than the disk edge printing layer 22, so as to facilitate exhaust; the continuous gradient strip 12 is specifically presented as a continuous gradient groove 13, which is formed by the adjacent long strip sunken gradient exhaust grooves on the parting surface of the mold core during injection molding; during the injection molding process, under the extrusion of the injection pressure melt, each gradient exhaust ridge (gradient exhaust groove 67) positions the disk edge printing layer 22 and the plastic print film layer 21, guides deformation and exhausts, and guides the disk edge printing layer 22 and the plastic print film layer 21 to be squeezed into the gradient exhaust groove 67 at the same time, avoiding local damage, bubbles and other defects caused by trapped air; after shaping, the continuous gradient strip 12 limits and supports the deformed disk edge printing layer 22 and the plastic print film layer 21, and improves the texture, mechanical strength and visual effect of the curved warped edge part.

[0061] The disk edge printing layer 22 is made of high-end silk fabric among textile fabrics (pressed or printed with a scroll-type cloud pattern), is annular, and is arranged on the plastic printing film layer 21, and its position, shape and area all correspond to the gradient exhaust groove on the second curved warping edge 16; corresponding to the position of the continuous gradient groove on the second curved warping edge 16, the outer disk edge printing layer 22 and the inner plastic printing film layer 21 are pressed into the gradient exhaust groove 67 on the molding surface of the movable mold core 69, and after shaping, they are simultaneously fixed on the surface of the second curved warping edge 16 with a continuous gradient depression, and become one with the injection molded body layer 11, forming a curved printed thin-walled food container 1 with multi-layer, rich-textured silk fabric decoration and a three-dimensional printing surface; the silk fabric of the outer disk edge printing layer 22 is on the outer surface of the plastic printing film layer 21, facing the side where the food is held, and is easier for the user to observe and touch during use; the inner side surface of the inner plastic printing film layer 21 is tightly fitted with the injection molded body layer 11 during molding.

[0062] The plastic printed film layer 21 is a PS plastic printed film, and the printed surface thereof is printed with the colors, patterns and designs of the Dunhuang Flying Apsaras. It is entirely covered on the front of the injection molding body layer 11, including a flat round bottom 14, a first curved warped edge 15, and a second curved warped edge 16, and is pressed between the disk edge printed layer 22 and the second curved warped edge 16. The radius is slightly smaller than the front of the injection molding body layer 11, and an exhaust gap is left at the edge of the molding surface of the movable mold core 69 corresponding to the front of the injection molding body layer 11.

[0063] See also Figures 30 to 31 The equipment for preparing curved printed thin-walled food containers provided in this embodiment is basically the same as that in Example 1, except that the gradient exhaust groove 67 is provided on the front molding surface of the movable mold core 69 facing the mold cavity (fixed mold group). The gradient exhaust groove is based on the convex gradient exhaust groove on the molding surface relative to the mold core, and is a groove channel structure formed by the intervals between multiple gradient exhaust ridges arranged at intervals on the molding surface of the mold core.

[0064] The method for printing a thin-walled food container on a curved surface is similar to that of Example 1, except that: S1. Preparation of printing materials S1-1 Preparation of plastic printed film layer The colors, patterns, and designs of Dunhuang Flying Apsaras are printed on one side of a 0.03-0.06mm thick PS film substrate, and then corona treated. The corona value of the printed surface is 38-42dyn / cm, and that of the non-printed surface is 32-34dyn / cm, which improves adhesion to GPPS and prevents melt slip during injection molding. S1-2 Preparation of disk edge printing layer Print colors, patterns or designs on a thin sheet of silk fabric with rich texture, cut into rings to obtain disk edge printing; S1-3 two-layer composite The disc edge printing layer 22 is laminated to the PS plastic printing film layer 21 at the position corresponding to the second curved surface warping 16. In this embodiment, an adhesive lamination method is used. A water-based polyurethane (PU) adhesive is applied to the PS plastic printing film layer, and then the pre-treated silk fabric is covered and aligned. A pressure roller is used to gently press (pressure 0.2-0.5 MPa) to ensure close contact. The fabric is then placed in a drying / curing device and dried at 60-80°C for 1-3 minutes to remove moisture, prevent high-temperature deformation of the PS, and protect the silk texture. After lamination, a peel strength test is performed, and a strength of ≥1.5 N / 25mm is considered acceptable.

[0065] S1-4 coating modified resin For the composite printing material, the surface of the plastic printing film facing the cavity is coated with a layer of sticky resin coating or nano-scale rubber powder compatible with the injection molding material GPPS, such as thermoplastic acrylate or polyurethane coating, or nano-scale rubber powder, to form a transition layer to strengthen the interface bonding ability and improve the interface adhesion with the substrate, so that the peel strength is ≥0.5N / cm; the front side of the disk edge printing layer (silk fabric) faces the cavity and is isolated from the pressure melt by the PS plastic printing film during injection molding.

[0066] The curved printed thin-walled food container made of silk fabric provided in the embodiment of the present invention has, except for the above-mentioned parts, other product structures, preparation equipment, processes, etc. that are the same as those described in the basic embodiment or Example 1. The product of this embodiment has a high-end silk texture and high artistic expression.

[0067] Example 3 See attached Figure 19 and Figure 20 The curved printed thin-walled food container, preparation method, and preparation equipment provided in the embodiments of the present invention are based on the basic embodiments and specifically provide an opaque modified PP type polypropylene plastic injection molding, a decal on the front of the injection-molded body, the plastic printing film layer is an opaque PET metallic glossy printed film, the plate edge printing layer is a special paper (a traditional Chinese painting style gradient printed rice paper), and the curved surface warped edge is provided with upward convex continuous gradient stripes. The embodiment is basically the same as the first and second embodiments, and the differences from the first and second embodiments include: The injection molding material used in this example is modified PP-type polypropylene plastic. Based on ordinary PP material, fillers such as talc and / or glass fiber are added to address the softness and easy deformation of ordinary PP. The addition of fillers increases the hardness of the injection-molded product by over 30%, increases its weight by over 20%, and creates a crisper surface that is less susceptible to sink marks. The specific addition ratio and process can be adjusted according to product requirements using conventional techniques. The addition ratio selected in this example is 10wt% talc + 20wt% glass fiber. This combination synergistically enhances the rigidity and dimensional stability of PP while further reducing shrinkage. It can be used in the manufacture of high-end food containers such as dinner plates, dishes, bowls, and lunch boxes.

[0068] The plastic printed film layer 21 is an opaque metallic luster plastic printed film (a metallic silver luster printed composite film obtained by aluminum plating a PET substrate) printed on one side, and the edge printed layer 22 is printed rice paper (special paper) printed with a gradient style Chinese painting; the two are composited using a hot melt adhesive process, with the hot melt adhesive film sandwiched between the metal film and the rice paper. After the positions are aligned, they are pressed together by a heating roller (temperature 80-120°C, adjusted according to the melting point of the adhesive film) and a pressure roller (0.2-0.4MPa). The heating time is controlled at 1-3 seconds. After natural cooling, the adhesive film solidifies to achieve bonding.

[0069] The equipment and method for preparing curved printed thin-walled food containers provided in this embodiment are basically the same as those in Example 1, except that the gradient exhaust groove 67 is arranged on the molding surface of the fixed mold core 62, the nozzles 68 are all arranged and the auxiliary demolding mechanism 7 is all arranged on the movable mold core 69, and the pressure melt is injected into the mold cavity from the nozzle 68 arranged at the center position of the molding surface of the movable mold core 69, and then cooled and molded; the injection-related structure of this mold device is symmetrically designed with the related structure of Example 1.

[0070] During the preparation process, the loading robot feeds the printing material onto the molding surface of the fixed mold core 62; the gradient exhaust groove 67 arranged on the molding surface is a gradient exhaust groove that is sunken relative to the molding surface of the mold core, and the continuous gradient strip 12 formed after injection molding is convex, obtaining a high-end curved printed thin-walled food container with opaque front decal + modified PP + disc injection molding body layer + convex continuous gradient strip + metallic silver gloss printing film + special paper (rice paper printed with gradient Chinese painting); the rest is the same as Example 1.

[0071] In other embodiments, the specialty paper may also be: virgin fiber-based specialty paper, such as food-grade kraft paper, parchment paper, oil-proof paper, plant fiber molded paper; or coated / composite modified specialty paper, such as laminated paper (PE laminated paper), aluminum foil composite paper, and starch-based coated paper.

[0072] Example 4 See attached Figure 21 and Figure 22 The curved printed thin-walled food container, preparation method, and preparation equipment provided in the embodiments of the present invention are based on the basic embodiments and specifically provide a circular disposable injection-molded curved surface high-end metallic texture printed dinner plate, which is HIPS injection-molded, has a decal on the front of the injection-molded body, a printed layer on the edge of the plate made of metal foil (printed metal copper foil), a PS plastic printed film, and sunken continuous gradient strips on the second curved and third warped edges. The embodiment is basically the same as embodiments 1 to 3, with the following differences: The injection molding material used in this embodiment is opaque high-impact polystyrene (HIPS) injection molding, the plastic printed film layer 21 uses a single-sided printed PS plastic printed film (printed with Islamic-style decorative patterns), and the plate edge printed layer 22 is a printed metal copper foil, giving the food container as a whole a distinctive Islamic copper metal utensil artistic style.

[0073] The opaque injection-molded body layer 11 includes a flat, rounded bottom 14, a first curved warped edge 15, and a second curved warped edge 16. A plastic printed film layer 21 entirely covers the front of the injection-molded body layer 11. A disc-shaped printed layer 22 covers the injection-molded body layer 11 at locations corresponding to the first and second curved warped edges 15, 16, forming a large-area metallic copper foil layer. The two-layer printed material complements the shape of the injection-molded body layer, including its continuous gradient strips, to create a product that simulates a metal container. The mold assembly is also adaptively designed to accommodate changes in the structure of the injection-molded body layer 11.

[0074] Example 5 See attached Figure 23 and Figure 24 The curved printed thin-walled food container, preparation method, and preparation equipment provided in the embodiments of the present invention are based on the basic embodiments and specifically provide an 18-inch fish dish made of biodegradable polylactic acid (PL) injection molding, a decal on the front of the injection-molded body layer, an oval-shaped overall contour of the injection-molded body layer, a PA plastic printed film, and a hollow embossed non-woven fabric edge printed layer. The container is essentially the same as embodiments 1 to 4, with the following differences: The injection-molded main body layer 11 is an open structure having a flat elliptical bottom 17 and a first curved warped edge 15. The overall outer contour is elliptical, and its elliptical bottom causes the curvature distribution of the first curved warped edge 15 to be asymmetric along the major axis and the minor axis; a thickened disk edge is provided on the outer edge of the first curved warped edge 15, and a circle of convex rings is provided on the bottom surface of the flat elliptical bottom 17.

[0075] PA plastic printed film is printed with ocean-related colors, patterns and designs. The edge printing layer made of hollow embossed non-woven fabric is hollowed out or embossed with three-dimensional concave and convex shapes, specifically wavy lines or fish schools, to increase the texture and friction of the part that users touch. The hollow embossed non-woven fabric is hot-pressed and laminated on the non-printed surface of the PA plastic printed film.

[0076] Example 6 See attached Figure 25 and Figure 26 The curved printed thin-walled food container, preparation method, and preparation equipment provided in the embodiments of the present invention are based on the basic embodiments and specifically provide a square disposable injection-molded curved surface high-end metallic texture square printed dinner plate made of polybutylene terephthalate (PBAT) injection molding, with the overall contour of the injection-molded body being square, a front decal, a plate edge printing layer being a metal foil (printed metal copper foil), a translucent PP plastic printed film, and a sunken continuous gradient stripe on the curved surface warping edge. The embodiment is basically the same as embodiments 1 to 5, with the following differences: The injection-molded main body layer 11 has an overall rectangular shape with rounded corners, including a square base 18 with rounded corners, a first curved edge 15 formed by an arc surface, a thickened edge around the outer edge of the first curved edge 15, and a raised ring on the bottom surface of the square base 18. Each component conforms to the shape of the mold cavity and is formed in one step during injection molding. The edge printing layer is made of metallic copper foil, and the plastic printing film layer is made of translucent PP plastic printing film.

[0077] In other embodiments, other suitable injection molding materials can also be selected, and the injection molding body layer can also be other basic contour shapes, including curved edges composed of multiple arc surfaces, and appropriately set thickened disk edges, bottom convex rings and other structures; the thickness, aspect ratio, etc. of the injection molding body layer can be selected according to specific needs; the plastic printed film can be made of a variety of plastic base materials such as PP, PS, PET or PA film, and its shape, scale and printing pattern can be selected according to design needs; the thin sheet material with rich texture can be made of various textured textile fabrics (such as chemical fiber textile fabrics, brocade, etc.), non-woven fabrics, metal foils, hot stamping films, special papers, leather or metal-coated composite materials, etc., which are thin layers that meet food safety regulations.

[0078] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Within the scope of the above embodiments of the present invention, the selection of specific materials, components, proportions, structures and process parameters can achieve the technical effects recorded in the present invention, so they will not be listed one by one. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned embodiments, or to make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A curved printed thin-walled food container, characterized in that: It includes an injection-molded body layer and a printing material, wherein the injection-molded body layer includes a curved surface and warped edges; The printing material comprises a plastic printing film layer and a disk edge printing layer; the disk edge printing layer is a layered material with rich texture and the back-injection molding main layer is arranged on the plastic printing film layer; The printing material is squeezed and deformed by the pressure melt during the injection molding process through the in-mold decal process, and is tightly adhered to and fixed on the injection molding body layer; the disk edge printing layer, the plastic printing film layer and the injection molding body layer are stacked in sequence, and the three layers of materials together form a curved printed thin-walled food container with a stacked deformation of a three-dimensional printing surface and an outwardly exposed structure of the disk edge printing layer.

2. The curved printed thin-walled food container according to claim 1, characterized in that: The injection molded body layer also includes a planar bottom edge; The plastic printed film layer is pre-set with colors, patterns or designs, and is covered on one side of the injection molded body layer after molding; the disk edge printed layer is annular and is arranged at a position on the plastic printed film layer corresponding to the curved edge facing away from the injection molded body layer; The printing material is squeezed and deformed by the pressure melt during the injection molding process through the in-mold decal process, and pressed into the gradient exhaust groove of the mold core molding surface. After integral molding, it is tightly adhered and fixed to the injection molding body layer; the disk edge printing layer, the plastic printing film layer and the injection molding body layer at the curved edge position are stacked in sequence to construct multiple centrally radiating, long strip-shaped continuous gradient strips. The three layers of material together form a curved printed thin-walled food container with a stacked deformation of a three-dimensional printing surface and an outwardly exposed disk edge printing layer.

3. The curved printed thin-walled food container according to claim 2, characterized in that: The gradient venting groove is a gradient venting groove that is sunken relative to the core molding surface. It is a channel structure directly formed by multiple gradient grooves arranged on the core molding surface. The multiple gradient venting grooves are centrally symmetrical and annularly arranged on the core molding surface corresponding to the disk edge printing layer, and the length is slightly greater than the covering length of the printing material. The cross-section of a single gradient venting groove is arc-shaped. With the molding surface as the reference, the depth gradually increases from the center to the outer edge. The initial section has a sunken depth of 0.1~0.3mm, and the final section gradually deepens to 0.5~0.8mm, with a width of 3~10mm and a length slightly smaller than the warped edge of the curved surface. The multiple continuous gradient strips on the warped edge of the curved surface are formed correspondingly by the gradient venting grooves during injection molding.

4. The curved printed thin-walled food container according to claim 2, characterized in that: The gradient venting groove is a convex gradient venting groove relative to the core molding surface, and is a channel structure formed by multiple gradient venting ridges spaced apart on the core molding surface and the grooves spaced apart from each other; wherein, the cross-section of a single gradient venting ridge is arc-shaped, and with the molding surface as the reference, the height gradually increases from the center to the outer edge, the convex height of the starting section is 0.1~0.3mm, and the final section gradually increases to 0.5~0.8mm, the width is 3~10mm, and the length is slightly smaller than the warped edge of the curved surface; the continuous gradient strip is formed by the corresponding adjacent long strip-shaped sunken gradient venting grooves on the core parting surface during injection molding.

5. The curved printed thin-walled food container according to claim 1, characterized in that: The plastic printed film layer is a transparent, translucent or opaque film with a single-sided printing on a PP, PS or PA substrate, with a thickness of 0.03-0.06 mm and a heat shrinkage rate of ≤1%. It is entirely covered on the front or back of the injection molding body layer, and the covered surface includes two parts: a curved edge and a flat bottom. During injection molding, it is located between the injection molding body layer and the disk edge printed layer, and its printed surface is connected to the injection pressure melt.

6. The curved printed thin-walled food container according to claim 1, characterized in that: The plate edge printing layer is a thin sheet material with rich texture, on which colors, patterns or designs are pre-set, including: thin sheet materials made of textile fabrics, non-woven fabrics, metal foils, hot stamping films, special papers, leather or metal-coated composite materials; The disc edge printing layer is located at the position corresponding to the warped edge of the curved surface and is pre-compounded on the plastic printing film layer to form a printing material. During the injection molding process, it is pressed into the gradient exhaust groove together with the plastic printing film layer to form a continuous gradient strip, and a three-layer structure is formed on the warped edge of the curved surface, with the disc edge printing layer exposed outward, the plastic printing film layer in the middle, and the injection molding body layer inside, which has rich texture and three-dimensional visual effect.

7. The curved printed thin-walled food container according to claim 2, characterized in that: The injection-molded body layer is an open structure having at least one flat bottom surface and a curved warped edge, wherein the curved warped edge is a curved surface composed of a single curvature arc surface, or a curved surface composed of multiple curvature arc surfaces interconnected and composed of a plurality of curvature arc surfaces, and the variation in the curvature radius between two adjacent arc surfaces is ≤10%; The injection-molded body layer is a structural layer formed by injection molding of the injection molding material, and the thickness of the flat bottom is 0.9-1.1 mm, the center thickness / average thickness ratio of the flat bottom is (1.3-1.65):1, and the thickness / diameter ratio is greater than 1 / 200; The injection molding materials include: poly (1,4-cyclohexanedimethanol terephthalate) PCTG, general-purpose polystyrene GPPS, high-impact polystyrene HIPS, modified PP-type polypropylene plastic, polylactic acid PLA, poly (butylene terephthalate-adipate) PBAT, poly (butylene terephthalate) PBT, poly (hydroxybutyrate) PHB or poly (butylene succinate) PBS.

8. A method for preparing the curved printed thin-walled food container according to any one of claims 1 to 7, characterized in that: It includes the following steps: S1. Preparation of printing materials preparing a disk edge printing layer and a plastic printing film layer respectively; The plate edge printing layer is laminated on the position of the plastic printing film corresponding to the warped edge of the curved surface to form a printing material; S2. Mold preparation A mold device and a jig are prepared separately, wherein the mold device includes a fixed mold group and a movable mold group, wherein the fixed mold group includes a fixed mold core, and the movable mold group includes a movable mold core, and a plurality of gradient exhaust grooves are provided on the molding surface of at least one of the fixed mold core or the movable mold core in a centrally symmetrical and spaced manner; S3, In-mold Lamination The jig absorbs the printing material, charges it with static electricity, and then feeds it into the mold; S4, mold closing and injection molding Combine the movable mold and the fixed mold, and after closing the mold, the injection molding machine injects the plastic pressure melt into the mold cavity for injection molding; After pressure holding and cooling, the printing material and the injection-molded body layer are formed at the warped edge of the curved surface, forming a plurality of long continuous gradient strips with the printed layer exposed outwards; S5. Demolding and blanking: After the mold is opened, the formed food container is taken out from the mold to obtain a curved surface printed thin-walled food container.

9. The method for preparing a curved surface printed thin-walled food container according to claim 8, characterized in that: The preparation of the S1 printing material specifically includes the following steps: S1-1 Preparation of plastic printed film Print a pattern or design on one side of a PP, PS or PA substrate film with a thickness of 0.03-0.06mm, and then perform a corona treatment. The corona value of the printed surface is 38-42dyn / cm, and the non-printed surface is 32-34dyn / cm, to improve the adhesion with the pressure melt material and prevent the pressure melt from slipping during injection molding. S1-2 Preparation of disk edge printing layer A pattern is printed on a thin sheet material with rich texture, which is then cut into rings to obtain a disk edge printing layer; S1-3 two-layer composite Laminating the disk edge printing layer on the position of the plastic printing film corresponding to the warped edge of the curved surface to obtain a printing material; S1-4 coating modified resin On the printing surface of the plastic printing film facing the cavity, a layer of viscous resin coating or powder compatible with the injection molding material is applied to form a transition layer to strengthen the interface bonding ability and buffer the impact of the injection pressure melt on the printing ink.

10. The method for preparing a curved surface printed thin-walled food container according to claim 8, characterized in that: The S2 mold preparation includes the following steps: S2-1 Mould preparation device The mold device includes a fixed mold group and a movable mold group and a mold frame. The fixed mold group includes a fixed mold core, and the movable mold group includes a movable mold core. At least one of the fixed mold core or the movable mold core is provided with a plurality of gradient exhaust grooves that are centrally symmetrical and spaced apart. In addition, an annular exhaust channel is provided on a release surface surrounding the periphery of the molding surface, close to the distal end of the gradient exhaust groove or directly connected to the gradient exhaust groove. A cavity for a curved printed thin-walled food container is formed between the fixed mold core and the movable mold core. S2-2 Preparation of fixture The fixture includes a loading robot, an unloading robot, a PLC controller, a mold clamping cylinder and guide rails; Among them, the loading robot picks up the statically charged printing material, and then makes the printed layer on the edge of the plate face away from the forming surface, and feeds it to the forming surface of one of the fixed mold core or the movable mold core, and the printing material automatically adheres to the forming surface; When decaling the front of a food container, the loading robot feeds the printing material onto the molding surface of the fixed mold core, and then injects the pressurized melt from the nozzle of the movable mold core. When decaling the back of a food container, the loading robot feeds the printing material onto the molding surface of the movable mold core, and then injects the pressurized melt from the nozzle of the fixed mold core. The unloading robot is used to remove the injection-molded food container from the mold device after the mold is opened; The PLC controller is used to control the coordinated actions of the fixed die set, movable die set, loading robot, unloading robot, mold clamping cylinder and injection molding machine; The movable die set is placed on the guide rail as a whole. Driven by the mold closing cylinder, the movable die set makes horizontal back and forth reciprocating motion on the guide rail as a whole to close or open the mold. S2-3 are connected to each other Connect the fixed die set, movable die set, loading robot, unloading robot, mold clamping cylinder and injection molding machine to the PLC controller respectively; The molten material of the injection molding machine is connected to the cavity between the fixed mold core and the movable mold core through the pipeline and the nozzle; S2-4 Setting Parameters The operating parameters of the injection molding machine, clamping cylinder, fixed die set, movable die set, loading robot and unloading robot are set in the PLC controller respectively.

11. The method for preparing a curved surface printed thin-walled food container according to claim 8, characterized in that: The S3 in-mold lamination process includes the following steps: S3-1 Printing material stacking The pre-prepared printing materials are stacked in a container to form a pile; S3-2 Printing material pickup The feeding robot uses a suction cup equipped with an electrostatic generator to pick up printing materials from the pile one by one. It picks up 1 to 4 pieces each time according to the number of cavities in a single injection molding. S3-3 Printing material feeding The electrostatic generator is started, which makes the printing material picked up on its suction cup charged with static electricity, and the feeding robot moves to transport the printing material to the loading position of the loading robot; S3-4 printing material in-mold labeling After the feeding robot arrives at the feeding position, it uses its suction cup to pick up the electrostatically printed material on the feeding robot and then transfers it to the mold device, so that the printed surface of the plastic printing film faces the cavity and fits tightly to the molding surface of the mold core, while the printed layer on the edge of the plate faces away from the cavity and does not come into contact with the pressurized melt during the injection molding process; After the plastic printing film is attached to the molding surface, a blank molding surface is left near the edge of the molding surface to prevent the printing material from blocking the exhaust channel and causing air trapping defects.

12. The method for preparing a curved printed thin-walled food container according to claim 8, wherein: The S4 mold closing and injection molding process includes the following steps: S4-1 Preheating and loading Preheating: Under the control of the PLC controller, the loading robot does not move, and the injection molding is performed 3 to 5 times to preheat the cavity to 70-80 degrees; Loading by the loading robot: The vacuum suction cup on the loading robot first picks up the statically charged printing material, then makes the printing layer on the edge of the plate face away from the forming surface, and feeds it to the forming surface of one of the fixed mold core or the movable mold core, and the printing material automatically adheres to the forming surface; When applying decals on the front of a food container, the printing material is fed into the molding surface of the fixed mold core; when applying decals on the back of a food container, the printing material is fed into the molding surface of the movable mold core; S4-2 mold closing and locking Mold closing: Under the control of the PLC controller, the mold closing cylinder drives the movable mold group to move toward the fixed mold group on the guide rail, so that the movable mold group and the fixed mold group are precisely fitted together, forming a thin-walled cavity between the mold core of the movable mold group and the mold core of the fixed mold group; Clamping: When the mold is completely closed, the clamping cylinder applies a clamping force that must be greater than the pressure of the melt on the cavity during injection, and 1.2 to 1.5 times the injection pressure, to ensure the cavity is sealed. S4-3 Injection Molding After the mold is closed, under the control of the PLC controller, the injection molding machine injects the plastic pressure melt into the mold cavity. The pressure melt contacts the printed surface of the plastic printing film in the printing material and melts and combines with it. At the same time, the printing material is tightly pressed against the cavity wall by the melt pressure. The printing material corresponding to the curved edge part is pressed into the gradient exhaust groove, so that the printing material avoids displacement, air entrapment, bubbles and wrinkles during the injection molding process, and increases the bonding strength between the printing material and the injection molding body layer. S4-4Pressure holding and shaping After the injection molding is completed, the pressure is maintained for a few seconds, and then cooled to set. The printing material finally forms multiple long continuous gradient strips on the printing surface of the injection molding body, and the printing layer on the edge of the disk is exposed to improve the texture of the curved edge part, the mechanical strength and the surface friction when the user holds it.

13. The method for preparing a curved surface printed thin-walled food container according to claim 8, characterized in that: The S5 demoulding and blanking process specifically includes the following steps: S5-1, mold opening Under the control of the PLC controller, the mold closing cylinder drives the movable mold group to move away from the fixed mold group on the guide rail, so that the movable mold group and the fixed mold group are separated, exposing the injection molded product formed between the mold core of the movable mold group and the mold core of the fixed mold group; S5-2, demoulding An auxiliary demoulding mechanism is pre-installed on the core of the movable die group or the fixed die group. After the mold is opened, the auxiliary demoulding mechanism is activated to separate the formed food container from the forming surface. S5-3, cutting The blanking robot moves to take the formed food container out of the mold to obtain a curved printed thin-walled food container.

14. A device for preparing curved printed thin-walled food containers, characterized in that: It is used to prepare the curved printed thin-walled food container according to any one of claims 1 to 7, or to implement the preparation method according to any one of claims 8 to 11, which comprises: PLC controller, injection molding machine, mold device, loading robot, unloading robot, feeding robot; The injection molding machine is arranged on one side of the mold device and is connected to the mold device through an injection pressure pipeline; The mold assembly includes: a movable mold assembly, a fixed mold assembly, a mold clamping cylinder, and a guide rail; the mold clamping cylinder is installed on the movable mold assembly, and the movable mold assembly is installed on the guide rail; the movable mold assembly and the fixed mold assembly are respectively provided with guide pins and guide sleeves, and are respectively provided with a forming mold core and a release surface; a gradient exhaust groove is provided on one side of the forming mold core facing the mold cavity, and an auxiliary demolding mechanism is also provided; The loading robot and unloading robot are respectively set on one side of the mold device, and both include a robot arm and a material picking fixture; the upper end of the robot arm is fixed to the ceiling, and the material picking fixture at the lower end is suspended and set around the forming mold core; The feeding robot is arranged outside the loading robot, and sucks one or more pages from the composite printing material pile with a suction cup at a time, applies static electricity and then transfers them to the loading robot; The PLC controller is respectively connected with the injection molding machine, mold device, loading robot, unloading robot, feeding robot, mold clamping cylinder, and auxiliary demoulding mechanism to control their coordinated operation.

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