Double-color and IML integrated injection molding process

Abstract

According to the double-color and IML integrated injection molding technology, vacuum adsorption, multiple guide columns and cavity pre-pressing combined positioning are adopted for a film, the injection molding quality is improved, a suspension cavity, corresponding to a mold, of a local protrusion is formed in the film in a hot press mode, and segmented injection molding and mold partition temperature control are adopted during first injection molding; the edge of the film is combined with a first injection molding material, a local convex area does not make contact with the first injection molding material to form an initial suspension structure, and the double-color middle layer suspension effect is achieved through second injection molding; in addition, the film is subjected to surface treatment before injection molding, an edge covering groove is formed in a mold cavity, a bottom layer agent is sprayed on the surface of a first-time injection molding product to construct a bonding layer, a bonding accelerant is added into a second-time injection molding material, the bonding strength between the materials is enhanced, annealing treatment is conducted after injection molding is completed, and the warping risk is further reduced. Therefore, the process is not limited to the combination of several specific materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of injection molding, in particular to a two-color and IML integrated injection molding process. BACKGROUND

[0002] The two-color injection molding and IML (in-mold label injection molding) integrated injection molding process is a composite technology that combines the "high-precision surface decoration" of IML and the "multi-material / multi-color function integration" of two-color injection molding into a single molding process through mold structure innovation and process coordination.

[0003] In actual production, it is found that the traditional two-color injection molding and IML integrated injection molding process cannot solve the problems of poor suspension effect of the intermediate layer after the combination of two different injection molding materials, low bonding strength of the film and plastic, and easy warping. Only by selecting materials with strong compatibility can the above-mentioned conditions be improved, which greatly limits the use of injection molding materials and restricts the diversification of development. SUMMARY

[0004] The purpose of the present application is to provide a two-color and IML integrated injection molding process to solve the above technical problems.

[0005] Technical solution: The present application provides a two-color and IML integrated injection molding process, comprising: S1, film printing and processing: according to the product design requirements, the IML film is printed to form the required patterns and text, after printing, small holes with a diameter of 0.5-1mm are pre-punched on the edge of the IML film, and local protrusions are made on the IML film, and the IML film is surface treated; S2, film conveying and positioning: the printed IML film is accurately sent into the fixed mold cavity of the fixed mold A plate of the mold by the conveying device, and the IML film is positioned by vacuum adsorption + multi-guide column + cavity pre-pressing combination; S3, first injection: the first injection material is added to the hopper of the injection molding machine, after the mold is closed, the injection molding machine injects the first color material into the mold cavity, and the IML film edge is fully combined, the local protrusions on the IML film do not contact the first injection material, after the injection is completed, cooling is carried out to make the first injection material solidify, and a preliminary suspension structure is formed; S4, mold rotation or movement: after the first injection is completed, the mold is opened, the movable mold B plate is rotated by 180°, and the movable mold cavity with the first injection product is switched to the position aligned with the second fixed mold cavity; S5, second injection molding: the second injection material is added to another hopper of the injection molding machine, after the mold is closed, the injection molding machine injects the second color material into the mold cavity, covering the area where the first injection IML film is combined with the first injection material, forming a double-color intermediate layer suspension effect, after the injection molding is completed, cooling is performed again to solidify the second material; S6, cooling and demolding: the product is fully cooled through the cooling system of the mold, so that the two plastic materials are completely solidified, after the cooling is completed, the mold is opened, and the product is ejected from the mold through the ejection mechanism; S7, subsequent processing: appearance inspection, size measurement and other quality detection are performed on the removed product.

[0006] Further, the specific method of local protrusion on the IML film is to place the IML film on the roller, heat press at 8-12 MPa and 120-150℃ for 30-60 seconds through the high-pressure mold, forming the protrusion shape matched with the mold suspension cavity.

[0007] Further, the surface treatment in S1 is to first use sandpaper to lightly grind the edge of the IML film, so that the roughness reaches 0.8-1.2μm, and then apply coupling agent on the surface of the IML film.

[0008] Further, a primer is sprayed on the surface of the first injection molded product, and an adhesion promoter is added to the second injection material.

[0009] Further, after the injection molding is completed, the injection molded product is fixed in an oven at 80-100℃ for 30-60min to release internal stress.

[0010] Further, micro positioning columns are arranged in the mold suspension cavity area, the micro positioning columns are uniformly distributed with a spacing of 5-10mm, and a glue groove with a depth of 0.3-0.5mm and a width of 1-1.5mm is arranged at the edge of the mold cavity.

[0011] Further, an exhaust groove with a width of 0.01-0.02mm is opened around the micro positioning column and extends to the mold parting surface, ensuring air exhaust during injection molding.

[0012] Further, a cooling water channel is arranged at a distance of 5-8mm from the cavity wall of the fixed mold cavity, and a cooling water channel is arranged at a distance of 8-12mm from the cavity wall of the movable mold cavity.

[0013] The technical scheme can achieve the following beneficial effects: the double-color and IML integrated injection molding process can improve the injection molding quality by adopting vacuum adsorption + multi-guide column + cavity pre-pressing combined positioning, and can form a preliminary suspension structure by using segmented injection molding and mold partition temperature control in the first injection molding, so that the film edge is combined with the first injection molding material, and the local protruding area is not in contact with the first injection molding material to form a preliminary suspension structure, and the suspension effect of the double-color intermediate layer is achieved through the second injection molding. In addition, the film is surface treated before injection molding, a cover slot is arranged in the mold cavity, the surface of the first injection molded product is sprayed with a primer to form a bonding layer, an adhesion promoter is added to the second injection molding material to enhance the bonding strength between the materials, and annealing treatment is performed after the injection molding is completed, thereby further reducing the warping risk, and the process can not be limited to the combination of certain specific materials. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The process flow of the double-color and IML integrated injection molding process. DETAILED DESCRIPTION

[0015] Embodiment 1 In this embodiment, the first injection molding material is PP, and the second injection molding material is TPE. The double-color and IML integrated injection molding process comprises the following steps: S1, film printing and treatment: according to the product design requirements, the IML film is printed to form the required patterns and characters, and after the printing is completed, small holes with a diameter of 0.5-1 mm are pre-punched at the edge of the IML film, and local protrusions are formed on the IML film, and the IML film is surface treated; S2, film conveying and positioning: the printed IML film is accurately sent into the mold cavity of the mold A plate by the conveying device, and the IML film is positioned by vacuum adsorption + multi-guide column + cavity pre-pressing; specifically, after the IML film is placed in the mold cavity, the vacuum adsorption system in the mold generates negative pressure to make the IML film tightly adhere to the surface of the mold, thereby achieving accurate positioning. The guide column mainly plays a guiding role to ensure that the movable mold and the fixed mold can be accurately centered when the mold is closed, thereby ensuring the position accuracy of the IML film in the mold, preventing the IML film from shifting due to mold misalignment during injection molding, and pre-pressing the cavity during mold closing to make the IML film tightly adhere to the cavity wall before injection molding, thereby further eliminating the gap between the IML film and the cavity, improving the molding quality and dimensional accuracy of the product, and also helping to prevent plastic melt from seeping into the gap between the IML film and the cavity during injection molding, thereby causing product defects; S3, first injection molding: the first injection material is added to the hopper of the injection molding machine, after the mold is closed, the injection molding machine injects the first color material into the mold cavity, fully combines with the edge of the IML film, the local protrusion on the IML film does not contact the first injection material, after the injection is completed, cooling is carried out to solidify the first injection material, and a preliminary suspension structure is formed; during injection molding, the melt temperature of the injection material is 240-260℃, which is 10-20℃ lower than the conventional temperature, the heat shock of the melt on the film is reduced, the edge deformation of the suspension cavity is prevented, slow injection (20-30mm / s) is adopted, and the injection is divided into two stages, the first stage injection pressure is 60-70MPa to fill the encapsulation groove, and the second stage injection pressure is 80-90MPa to compact the edge bonding area; the mold temperature is controlled in different zones, the edge bonding area is controlled at 60-70℃ to promote melt infiltration, and the suspension cavity area is 40-50℃ to delay melt flow; S4, mold rotation or movement: after the first injection molding is completed, the mold is opened, the movable mold B plate is rotated by 180°, and the movable mold cavity with the first injection molded product is switched to a position aligned with the second fixed mold cavity; S5, second injection molding: the second injection material is added to the other hopper of the injection molding machine, after the mold is closed, the injection molding machine injects the second color material into the mold cavity to cover the area where the first injection IML film is combined with the first injection material, forming a double-color intermediate layer suspension effect, after the injection is completed, the second material is solidified again; during injection molding, the melt temperature of the injection material is 225-255℃, which is lower than the temperature of the first injection, to avoid secondary softening, slow injection (10-30mm / s) is adopted, and the injection pressure is 50-70MPa to avoid pressing the first injection product; S6, cooling and demolding: the product is fully cooled through the cooling system of the mold to completely solidify the two plastic materials, after the cooling is completed, the mold is opened, and the product is ejected from the mold through the ejection mechanism; S7, subsequent processing: the removed product is subjected to appearance inspection, size measurement and other quality detection.

[0016] The specific method of the local protrusion on the IML film is to place the IML film on the roller, heat press at 120-150℃ for 30-60 seconds through a high-pressure mold with a pressure of 8-12MPa to form a protrusion shape matched with the suspension cavity of the mold.

[0017] The surface treatment in S1 is to first grind the edge of the IML film with sandpaper to make the roughness reach 0.8-1.2μm, change the micro surface morphology of the film edge, and create an anchoring basis for subsequent bonding, and then apply a coupling agent on the surface of the IML film, which has a chemical reaction with the IML film substrate on one end of its molecular structure and can be combined with the subsequent bonded substrate on the other end.

[0018] Spray primer on the surface of the first injection product to build a bonding layer, add adhesion promoter in the second injection material. The molecules of adhesion promoter can react with the first injection material on one end, and combine with the second injection material on the other end, forming chemical bonds to enhance the adhesion of the two materials.

[0019] After injection molding, the injection product is fixed in an oven at 80-100℃ for 30-60min to release internal stress, which can effectively reduce the risk of warping.

[0020] The mold suspension cavity area is provided with micro positioning columns, which are uniformly distributed with a spacing of 5-10mm. The edge of the mold cavity is provided with a glue groove with a depth of 0.3-0.5mm and a width of 1-1.5mm. The micro positioning column supports the film and prevents it from collapsing during injection molding. The glue groove is set to allow the material melt to flow into the groove during injection molding to form a barb structure, mechanically locking the film edge and preventing peeling.

[0021] A 0.01-0.02mm wide exhaust groove is provided around the micro positioning column and extends to the mold parting surface to ensure air exhaust during injection molding.

[0022] A cooling water channel is provided 5-8mm away from the cavity wall of the fixed mold cavity to quickly reduce the temperature of the plastic part below the thermal deformation temperature. A cooling water channel is provided 8-12mm away from the cavity wall of the movable mold cavity to slowly cool down and reduce the interfacial stress.

[0023] It should be noted that the above is only the technical solution of the invention and not a limitation. Although the invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the invention can be modified or replaced by equivalents without departing from the scope of the invention, which should be covered by the claims of the invention.

Claims

1. A two-color and IML integrated injection molding process, characterized in that: include: S1, Film Printing and Processing: According to the product design requirements, print the IML film to form the required patterns and text. After printing, pre-drill small holes with a diameter of 0.5-1mm on the edge of the IML film, then make local protrusions on the IML film, and perform surface treatment on the IML film. S2, Film conveying and positioning: The printed IML film is accurately fed into the fixed mold cavity of the fixed mold plate A of the mold through the conveying device. The IML film is positioned by a combination of vacuum adsorption + multiple guide pillars + cavity pre-compression. S3, First Injection: The first injection material is added to the hopper of the injection molding machine. After the mold is closed, the injection molding machine injects the first color material into the mold cavity, which fully combines with the edge of the IML film. The local protrusions on the IML film do not contact the first injection material. After the injection is completed, cooling is performed to solidify the first injection material and initially form a suspension structure. S4, Mold rotation or movement: After the first injection is completed, the mold is opened, and the moving mold plate B rotates 180° to switch the moving mold cavity with the first injection product to the position aligned with the second fixed mold cavity; S5, Second Injection: The second injection material is added to another hopper of the injection molding machine. After the mold is closed, the injection molding machine injects the second color material into the mold cavity, covering the area where the first injection IML film and the first injection material are combined, forming a two-color intermediate layer suspension effect. After the injection is completed, it is cooled again to solidify the second material. S6, Cooling and Demolding: The product is fully cooled by the mold's cooling system, allowing the two plastic materials to solidify completely. After cooling, the mold is opened, and the product is ejected from the mold by the ejection mechanism. S7, Post-processing: Perform quality inspections such as appearance inspection and size measurement on the removed products.

2. The two-color and IML integrated injection molding process according to claim 1 is characterized in that: The specific method for creating localized protrusions on an IML film is to place the IML film on a roller and heat-press it for 30-60 seconds at 120-150℃ using a high-pressure mold at a pressure of 8-12MPa to form a protrusion shape that matches the mold's suspension cavity.

3. The two-color and IML integrated injection molding process according to claim 1, characterized in that: The surface treatment in S1 specifically involves first lightly grinding the edge of the IML film with sandpaper to achieve a roughness of 0.8-1.2 μm, and then applying a coupling agent to the surface of the IML film.

4. The two-color and IML integrated injection molding process according to claim 1 is characterized in that: An undercoat is sprayed onto the surface of the first injection-molded product, and an adhesion promoter is added to the second injection-molded material.

5. The two-color and IML integrated injection molding process according to claim 1 is characterized in that: After injection molding, the injection molded product is fixed in an 80-100℃ oven for 30-60 minutes to release internal stress.

6. The two-color and IML integrated injection molding process according to claim 2 is characterized in that: The mold suspension cavity area is provided with micro positioning posts, which are evenly distributed with a spacing of 5-10mm. The edge of the mold cavity is provided with a rubber-coating groove with a depth of 0.3-0.5mm and a width of 1-1.5mm.

7. The two-color and IML integrated injection molding process according to claim 6 is characterized in that: The micro positioning post has venting grooves 0.01-0.02mm wide around its perimeter, extending to the mold parting surface, to ensure that air is discharged during injection molding.

8. The two-color and IML integrated injection molding process according to claim 1 is characterized in that: Cooling water channels are provided in the fixed mold cavity at a distance of 5-8mm from the cavity wall, and cooling water channels are provided in the moving mold cavity at a distance of 8-12mm from the cavity wall.

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