Mobile phone back cover, composite plate with crater and forming process thereof

Abstract

The disclosure provides a mobile phone back cover, a composite plate with a crater and a forming process thereof. The forming process of the composite plate with the crater comprises the following steps: obtaining a first substrate and a second substrate. The first substrate is subjected to a first cutting treatment, so that a flow material extension groove is formed on the first substrate. The first substrate and the second substrate are subjected to a mold entering treatment, so that the first substrate and the second substrate are placed in an injection mold, and the slope insert of the injection mold, the first substrate and the second substrate jointly form a cavity runner with a slope when the injection mold is closed, which is communicated with the flow material extension groove. The cavity runner is subjected to an injection molding treatment, so that a filling resin layer respectively adhered to the first substrate and the second substrate is formed in the cavity runner and the flow material extension groove, and a composite plate is obtained. The second substrate and the filling resin layer jointly constitute the crater structure of the composite plate. The flow material extension groove is located directly below the slope part of the cavity runner.

Description

Technical Field

[0001] This disclosure relates to the field of mobile phone back cover technology, and in particular to a mobile phone back cover, a composite board with a crater-like shape, and its molding process. Background Technology

[0002] The volcano-shaped design on the sheet material is usually used for limiting or positioning components, or for lightweight and three-dimensional design, making the overall appearance more aesthetically pleasing, such as the back cover of a mobile phone.

[0003] Currently, the crater design within the board material is generally achieved using cold carving or one-piece injection molding. The cold carving process first involves cold carving (cutting) a thickened first substrate (e.g., 1.5mm~2mm) at room temperature to a lower preset thickness (e.g., preset thickness of 0.3mm~0.5mm), while preserving the crater structure during the cold carving process. Then, the cold-carved surface (cut surface) is polished. However, during the cold carving process, since the cutting blade and mold are in hard contact with the board material, there will be cutting and polishing errors on the board surface and the slope of the crater. With the addition of these double errors, the yield rate of boards processed by the cold carving process is relatively low, and the steps of the cold carving process are also quite complicated.

[0004] One-piece injection molding is a process where the mold is injected as a single piece. Although the process is relatively simple, the crater itself has a slope design, so the mold is matched with an insert with a corresponding slope design. When the mold is closed, the gap between the runners in the cavity will decrease as the slope height decreases. Due to the decrease in the gap between the runners, the flow of the liquid material is restricted, which means that the liquid material cannot completely fill the end area of ​​the narrowed gap. This results in insufficient liquid material being injected at the end of the gap, and defects are likely to appear on the surface of the plate and the crater slope after molding, affecting the consistency of the plate molding. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a mobile phone back cover, a composite board with a crater-shaped crater, and its molding process that can simplify the process steps, avoid cutting and grinding errors, and improve the molding yield and consistency of the composite board.

[0006] The purpose of this disclosure is achieved through the following technical solution: A molding process for a composite panel with a volcanic crater shape includes the following steps: Obtain the first substrate and the second substrate; The first substrate is subjected to a first cutting process to form a material flow extension groove on the first substrate; The first substrate and the second substrate are subjected to mold insertion processing so that the first substrate and the second substrate are placed in the injection mold. When the injection mold is closed, the slope insert of the injection mold, the first substrate and the second substrate together form a cavity flow channel with a slope that communicates with the flow extension channel. The cavity flow channel is subjected to injection molding to form a composite plate with a volcano-like shape, in which a filling resin layer that is respectively bonded to the first substrate and the second substrate is formed in the cavity flow channel and the flow extension groove. The second substrate and the filling resin layer together form the crater structure of the composite plate; The material extension channel is located directly below the sloping portion of the cavity flow channel.

[0007] In one embodiment, during the first cutting process of the first substrate, a first positioning hole is also formed on the first substrate.

[0008] In one embodiment, after the step of performing the first cutting process on the first substrate and before the step of performing the molding process on the first substrate and the second substrate, the following step is further included: The second substrate is subjected to a second cutting process to form a second positioning groove on the second substrate.

[0009] In one embodiment, the specific steps for molding the first substrate and the second substrate are as follows: The first positioning block of the lower mold of the injection mold is engaged in the first positioning hole of the first substrate, so that the first substrate is placed in the lower mold of the injection mold; The second positioning block of the upper mold of the injection mold is engaged in the first positioning groove of the second substrate, so that the second substrate is placed in the upper mold of the injection mold; The upper mold and the lower mold are combined.

[0010] In one embodiment, during the second cutting process of the second substrate, the second substrate is further provided with a feed through-hole.

[0011] In one embodiment, the specific steps for injection molding the cavity flow channel are as follows: The injection mold upper mold injection component injects liquid material into the cavity flow channel through the feed through hole, and the liquid material fills the cavity flow channel and the flow extension groove; The injection mold is cooled and molded to solidify the liquid material in the cavity flow channel and the flow extension groove to form the filling resin layer that is respectively attached to the first substrate and the second substrate, and the composite plate with crater is formed.

[0012] In one embodiment, after the first cutting process of the first substrate and before the molding process of the first substrate and the second substrate, the following step is further included: The first substrate and the second substrate are cleaned and coated.

[0013] In one embodiment, the filling resin layer is a polycarbonate resin layer.

[0014] In one embodiment, the height of the crater structure of the composite board is the distance from the side of the second substrate away from the filling resin layer to the side of the first substrate near the filling resin layer, and the height of the crater structure of the composite board is 1.5mm to 1.8mm.

[0015] In one embodiment, both the first substrate and the second substrate are PC boards.

[0016] In one embodiment, the thickness of the first substrate is 0.3 mm to 0.5 mm.

[0017] In one embodiment, the thickness of the second substrate is 0.1 mm to 1.0 mm.

[0018] In one embodiment, the depth of the material extension channel is 0.05mm to 0.08mm, and the width of the material extension channel is 2.0mm to 3.0mm.

[0019] A composite panel with a crater is prepared using the composite panel molding process with a crater as described in any of the above embodiments; The composite board with a crater-like structure includes a first substrate, a second substrate, and a filling resin layer. A flow extension groove is formed on the side of the first substrate that is close to the first substrate. The first substrate and the second substrate are used to place the first substrate and the second substrate in an injection mold so that when the injection mold is closed, the slope insert of the injection mold, the first substrate, and the second substrate together form a cavity flow channel with a slope that communicates with the flow extension groove. The flow extension groove is located directly below the slope portion of the cavity flow channel. The filling resin layer is respectively attached to the first substrate and the second substrate, and a portion of the filling resin layer fills the flow extension groove.

[0020] A mobile phone back cover, characterized in that it includes a composite board with a crater-like shape as described in the above embodiments.

[0021] Compared with the prior art, this disclosure has at least the following advantages: 1. By inserting the first substrate and the second substrate into the mold, the first substrate and the second substrate are placed inside the injection mold. When the injection mold is closed, the slope insert of the injection mold, the first substrate, and the second substrate together form a cavity flow channel with a slope shape. Before the first substrate is inserted into the mold, the first substrate is cut to form a flow extension groove, and the flow extension groove is located directly below the slope portion of the cavity flow channel. This allows the flow extension groove to serve as an extension of the cavity flow channel when the injection mold is closed, thus compensating for the gap of the slope portion of the cavity flow channel. This increases the gap of the slope portion at the end of the cavity flow channel, allowing the liquid material to fill the slope portion of the cavity flow channel smoothly. This avoids the situation where the liquid material is injected too little at the end of the slope portion of the cavity flow channel, thereby avoiding defects in the volcano slope forming of the composite board and ensuring the consistency of the composite board forming.

[0022] 2. By directly obtaining the first substrate and cutting only one flow extension groove on the first substrate, on the one hand, there is no need for additional cold cutting and polishing of the main body of the first substrate, and the flow extension groove formed by cutting the first substrate is also filled with a resin layer, avoiding cutting and polishing errors on the first substrate. On the other hand, it also avoids the situation where the flow channel gap becomes smaller, resulting in a smaller amount of liquid injected, causing defects on the surface of the first substrate. Furthermore, the resin layer is integrally injection molded between the second substrate and the first substrate, and the second substrate and the resin layer together form the crater of the composite board. There is no need to polish the slope of the crater structure of the composite board, avoiding cutting and polishing errors on the crater slope of the composite board, thereby improving the molding yield of the composite board with crater, simplifying the operation steps of the molding process of the composite board with crater, and ensuring the consistency of the molding of the composite board with crater. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a flowchart of the molding process for the composite panel with a volcano-like crater according to the present invention; Figure 2 This is a schematic diagram of the composite plate with a crater-like structure of the present invention. Figure 3 This is a schematic diagram of the injection mold of the present invention; Figure 4 for Figure 3 The diagram shown is a cross-sectional view of the injection mold during injection molding. Figure 5 for Figure 4 A magnified view of point A shown below; Figure 6 for Figure 3 A schematic diagram of a partial structure of the injection mold shown; Figure 7 for Figure 3 A schematic diagram of a partial structure of the injection mold shown; Figure 8 This is a cross-sectional view of the composite plate of Embodiment 1 of the present invention; Figure 9 This is a cross-sectional view of the composite plate of Comparative Example 1 of the present invention; Figure 10 This is a cross-sectional view of the composite plate of Comparative Example 1 of the present invention. Detailed Implementation

[0025] To facilitate understanding of this disclosure, a more complete description will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the present disclosure. However, this disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure.

[0026] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] To better understand the technical solutions and beneficial effects of this disclosure, the following detailed description is provided in conjunction with specific embodiments. Please refer to [link / reference]. Figure 1 One embodiment of the composite panel molding process with a crater includes some or all of the following steps: S100, Obtain the first substrate and the second substrate.

[0029] In this embodiment, by directly obtaining the first substrate of the finished product, there is no need to use a thickened substrate for cold carving, thinning, and polishing, thus avoiding cutting errors on the surface of the first substrate. At the same time, it can also save costs and reduce waste.

[0030] Furthermore, in one embodiment, the thickness of the first substrate is 0.3mm to 0.5mm. It can be understood that the thickness of the first substrate is 0.3mm to 0.5mm, that is, the base plate of the composite board is 0.3mm to 0.5mm. When the composite board is applied to the back cover of a mobile phone, it can meet the requirements of the thin and light design of the back cover of the mobile phone while ensuring the structural stability of the base structure of the back cover of the mobile phone.

[0031] Furthermore, in one embodiment, the thickness of the second substrate is 0.1 mm to 1.0 mm. It is understood that by directly obtaining the finished second substrate with a thickness between 0.1 mm and 1.0 mm, the base structure of the crater structure can be ensured when it is formed together with the filling resin layer to create the crater structure of the composite board. Moreover, since the filling resin layer is integrally injection molded, the crater structure formed by the second substrate and the filling resin layer does not require additional polishing, and no cutting is needed on the second substrate. This avoids cutting and polishing errors in the crater structure, thereby improving the molding yield of the composite board.

[0032] Furthermore, in one embodiment, both the first substrate and the second substrate are PC sheets. It is understood that PC (polycarbonate) is a polymer formed by the polymerization of bisphenol A and carbonate bonds. The main chain contains a large number of rigid benzene rings, providing strength and heat resistance, while the flexible ether bonds (-O-) grant the molecular chain a certain degree of rotational freedom, allowing the chain segments to undergo localized movement and rearrangement upon impact. Furthermore, under external impact, numerous fine "silver streaks" form inside the PC, dissipating energy through shear yielding, thereby preventing crack propagation. This mechanistic "self-dissipating" characteristic makes its notched impact strength far higher than that of ordinary plastics (such as PMMA and ABS). The inherent mechanism of PC sheets endows them with good structural toughness, heat resistance, and impact resistance. The good heat resistance prevents thermal deformation or melting of the first and second substrates during injection molding, thus ensuring the structural stability of the composite sheet. The rigid benzene rings and flexible ether bonds of PC itself enhance the toughness and impact resistance of the composite sheet, improving the toughness and impact resistance of the phone back cover when applied to it. Furthermore, the thickness of the first substrate is preferably 0.5 mm. A thicker first substrate, serving as the base of the composite board, i.e., a thicker forming layer on the rigid-flexible PC board, enhances the structural toughness of the composite board, maximizing its impact resistance while meeting the requirements of a thin and light design for the phone's back cover. Furthermore, the thickness of the second substrate is preferably 1.0 mm. As the base of the crater structure and also a structural component of the composite board, a thicker second substrate, i.e., a thicker forming layer on the rigid-flexible PC board, enhances the structural toughness of the composite board, maximizing its impact resistance while meeting the requirements of a thin and light design for the phone's back cover.

[0033] Furthermore, the specific operational steps for obtaining the first substrate and the second substrate are as follows: First, the first large panel and the second large panel are coated with a first film, so that the surfaces of the first large panel and the second large panel are covered with CNC-cut film. Next, the first and second large panels after lamination are CNC slitting to cut multiple first substrates and multiple second substrates.

[0034] Understandably, by applying a CNC cutting film to the first and second large panels, two advantages are achieved: firstly, it prevents cutting debris from damaging the exposed PC surface during CNC cutting, thus improving the surface quality of the first substrate; secondly, while PC itself has high toughness, CNC cutting is essentially "forced fracture separation." By covering the surfaces of the first and second large panels with the film, the entire surface of the board is "wrapped," increasing the lateral constraint of the surface material, making the cut edges neater, reducing minor chipping and corner breakage, and thus suppressing edge collapse. Furthermore, due to the stress concentration within the PC board, cutting heat and mechanical stress can easily induce micro-cracks at the edge cuts. The film can bind the surface of the PC board, delaying the outward propagation of cracks and reducing the risk of stress cracking during subsequent use. Furthermore, the CNC cutting film is a PE (polyethylene) protective film. Understandably, PE is soft, can tightly adhere to the PC board surface, and has good air permeability (e.g., textured PE film), preventing debris from scratching the board or causing positioning misalignment during CNC cutting due to film lifting. Furthermore, by performing CNC slitting on the first and second large panels after lamination, the first large panel is slitted into multiple first substrates, and the second large panel is slitted into multiple second substrates. Based on the size design, the first and second substrates can be obtained in batches, thereby improving efficiency.

[0035] Furthermore, since the crater structure protrudes from the first substrate, the impact force of the crater structure hitting the floor when the phone is accidentally dropped from a height is common. Moreover, the PC board itself has low hardness, meaning the surface hardness of the crater structure is insufficient, making it prone to scratches when the phone's back cover is dropped. Therefore, in one embodiment, before performing the first coating process on the first and second large panels, the following steps are included: The second large panel is hardened so that the side of the second large panel opposite to the filling resin layer is covered with a hardened coating.

[0036] Understandably, the side of the second large panel that faces away from the filling resin layer, which is the side of the second substrate that faces away from the filling resin layer and the exposed side of the phone back cover, is hardened by applying a hardened coating to this side, increasing the surface hardness of the composite board's crater structure and thus reducing the occurrence of scratches.

[0037] Furthermore, the hardening treatment can be one of the following methods: coating curing, UV curing, or vapor deposition. It is understood that when the hardening treatment is a coating curing process, the hardened coating is an organosilicon hardened coating. The coating is applied via a spray coating method, forming a liquid curtain through an overflow tank, and continuously coated onto a uniformly moving PC board. This method is particularly suitable for hardening large-area boards, and the resulting coating has high uniformity. When the hardening treatment is a UV curing process, the hardened coating is an acrylic UV hardened coating. After the slurry is applied to the PC board surface, it is cross-linked and cured under nitrogen protection or normal pressure deoxygenation environment by irradiation with a UV lamp (wavelength 250nm~410nm). This process is highly efficient and has low energy consumption. When the hardening process is vapor deposition, the hardened coating is an inorganic hard coating layer. Vapor deposition is divided into PVD. PVD (physical vapor deposition) atomizes solid target materials (SiO2, Si3N4, DLC, etc.) in a vacuum chamber by magnetron sputtering or evaporation and deposits them onto the surface of PC board. The temperature in the vacuum chamber needs to be controlled between 25℃ and 80℃ to prevent the PC board from thermally deforming.

[0038] S200, the first substrate is subjected to a first cutting process to form a material extension groove on the first substrate.

[0039] In this embodiment, a flow extension groove is CNC-cut on the side of the first substrate near the filling resin layer, and the flow extension groove is located directly below the slope portion of the cavity flow channel. This allows the flow extension groove to serve as an extension of the flow channel within the cavity when the injection mold is closed, thus compensating for the gap in the slope portion of the cavity flow channel. This increases the gap in the end slope portion of the cavity flow channel, allowing the liquid to smoothly fill the slope portion of the cavity flow channel. This avoids insufficient liquid injection at the end slope portion of the cavity flow channel, thereby preventing defects in the volcano-shaped slope of the composite board and ensuring the consistency of the composite board molding.

[0040] Furthermore, in one embodiment, the depth of the flow extension groove is 0.05mm~0.08mm, and the width of the flow extension groove is 2.0mm~3.0mm. It is understood that when the depth of the flow extension groove is less than 0.05mm, the compensation effect as an extension of the flow channel within the cavity is poor, meaning the improvement in the flowability of the liquid at the end of the flow channel within the cavity is inadequate, and uneven flow still exists. While when the depth of the flow extension groove is greater than 0.08mm, although it can effectively supplement the extended portion of the cavity flow channel and improve the flowability of the liquid at the end of the cavity flow channel, the liquid deposited in the flow extension groove is prone to generating air bubbles, causing gaps between the filling resin layer in the flow extension groove and the first substrate. This affects the bonding strength between layers, thereby reducing the consistency of the composite board, i.e., the tensile strength is inconsistent after the filling resin layer is bonded to the first substrate and the second substrate. Therefore, in this embodiment, the depth of the flow extension groove is controlled between 0.05mm and 0.08mm. This not only effectively compensates for the flow channels within the cavity, improving the fluidity of the liquid material at the end of the flow channels, but also avoids gaps at the connection between the filling resin layer and the first substrate due to excessive depth. This ensures both the bonding strength between the three layers of the composite board and the consistency of the connection between the three layers, thereby improving the production yield of the composite board. Furthermore, the flow extension groove is located directly below the slope portion of the flow channels in the cavity. That is, by setting the width of the flow extension groove to 2.0mm to 3.0mm to match the slope insert of the injection molding die, the flow extension groove can cover the entire slope portion of the flow channels within the cavity, thereby improving the fluidity of the liquid material at the end of the flow channels within the cavity, and thus improving the consistency of the composite board.

[0041] Furthermore, since the crater structure of the composite board is annular, in this embodiment, the material extension groove is also annular groove, which is set as annular groove to match the molding requirements of the annular crater structure.

[0042] S300, the first substrate and the second substrate are subjected to mold insertion processing so that the first substrate and the second substrate are placed in the injection mold, and the slope insert of the injection mold, the first substrate and the second substrate together form a cavity flow channel with a slope that communicates with the flow extension groove when the injection mold is closed.

[0043] In this embodiment, the first substrate and the second substrate are placed inside the injection mold, and the slope insert of the injection mold, the first substrate and the second substrate form a cavity flow channel communicating with the flow extension groove when the injection mold is closed. By setting the flow extension groove, the problem of poor material flow at the end of the cavity flow channel after the injection mold is closed can be solved, thereby improving the yield and consistency of composite board molding.

[0044] Furthermore, since the second substrate is CNC-cut into individual pieces from the second large panel, and the circumferential side of the second substrate forms a bevel after CNC cutting (i.e., CNC cutting is a straight-blade bevel cut), the circumferential side of the second substrate is a flat bevel. However, the crater slope needs to have a curvature to ensure its three-dimensionality. The circumferential side of the second substrate is a component of the crater structure's slope. Because of this flat bevel, the slope connection at the junction of the filling resin layer and the second substrate is poor, resulting in poor flatness and a poor three-dimensionality of the entire crater structure's slope. Therefore, in one embodiment, when the slope insert, the first substrate, and the second substrate are closed in the injection mold, the second substrate and the slope insert also form a slope compensation groove, which communicates with the cavity flow channel. Understandably, the second substrate and the slope insert form a slope compensation groove, with one end of the slope insert abutting against the circumferential side of the second substrate. This creates a reference slope line for the crater-like slope formation, ensuring the three-dimensionality of the crater structure in the composite board. During subsequent injection molding, the filling resin layer also fills the slope compensation groove, allowing the filling resin layer to adhere to the circumferential side of the second substrate. This ensures the three-dimensionality of the crater structure in the composite board and improves its slope flatness. Furthermore, the adhesion between the filling resin layer and the circumferential side of the second substrate further increases the connection stability between the filling resin layer and the second substrate, thereby improving the yield and consistency of the composite board.

[0045] It should also be noted that the slope insert is also annular, which can cover and surround the second substrate when the mold is closed, thereby forming a surrounding cavity flow channel. At the same time, the slope compensation groove is also surrounding, that is, it can cover the part of the second substrate, eliminating the problem of poor slope connection effect at the connection between the filling resin layer and the second substrate, and improving the slope flatness and slope three-dimensionality of the volcano structure of the composite board.

[0046] S400, the cavity flow channel is injection molded to form a filling resin layer that is respectively bonded to the first substrate and the second substrate in the cavity flow channel and the flow extension groove, thereby obtaining a composite board.

[0047] In this embodiment, liquid material is injected into the cavity flow channel through an injection mold and hot-pressed to form a filling resin layer that fills the cavity flow channel and the flow extension groove. The filling resin layer is then bonded to the first substrate and the second substrate, and the filling resin layer and the second substrate together form the crater structure of the composite plate, thereby forming a composite plate with a crater.

[0048] It should be noted that the liquid material will also fill the slope compensation trough.

[0049] In one embodiment, during the first cutting process of the first substrate, a first positioning hole is also formed on the first substrate. It is understood that by CNC cutting the first positioning hole into the first substrate, rapid positioning of the first substrate during mold entry is facilitated, thereby improving the molding efficiency of the composite board.

[0050] In one embodiment, after the step of performing the first cutting process on the first substrate and before the step of performing the molding process on the first substrate and the second substrate, the following step is further included: The second substrate is subjected to a second cutting process to form a second positioning groove on the second substrate. It can be understood that by CNC cutting the second positioning groove into the second substrate, it is easier to quickly position the second substrate when it enters the mold, thereby improving the molding efficiency of the composite board.

[0051] Furthermore, the ambient temperature for both the first and second cutting processes is 20℃~30℃. It is understood that to avoid "active heating" of the environment during the cutting process, which would increase the surface temperature of the first and second substrates during the cutting process, air cooling is used simultaneously during the first and second cutting processes to cool the first and second substrates and prevent thermal deformation.

[0052] In one embodiment, the specific steps for molding the first substrate and the second substrate are as follows: The first positioning block of the lower mold of the injection mold is engaged in the first positioning hole of the first substrate, so that the first substrate is placed in the lower mold of the injection mold; The second positioning block of the upper mold of the injection mold is engaged in the first positioning groove of the second substrate, so that the second substrate is placed in the upper mold of the injection mold; The upper mold and the lower mold are combined.

[0053] It is understandable that the first positioning block and the second positioning block can quickly position the first substrate and the second substrate in the upper and lower molds of the injection mold and merge them, thereby improving the mold entry efficiency and thus improving the molding efficiency of the composite board.

[0054] In one embodiment, during the second cutting process of the second substrate, the second substrate also has a feed through-hole. It is understood that since the injection mold's injection element is located in the upper mold, by providing a feed through-hole on the second substrate, the molten material is injected through the injection element into the cavity flow channel and dispersed in all directions, thereby filling the cavity flow channel, the flow extension groove, and the slope compensation groove, ensuring smooth injection of the molten material.

[0055] In one embodiment, the specific steps for injection molding the cavity flow channel are as follows: The injection mold upper mold injection component injects liquid material into the cavity flow channel through the feed through hole, and the liquid material fills the cavity flow channel and the flow extension groove; The injection mold is cooled and molded to solidify the liquid material in the cavity flow channel and the flow extension groove to form the filling resin layer that is respectively attached to the first substrate and the second substrate, and the composite plate with crater is formed.

[0056] Understandably, the molten material is input through the barrel and then injected into the injection mold through the injection unit. Since the temperature of the molten material in the barrel is 280℃~340℃, it is ensured to remain in a flowing, molten state. The injection pressure of the injection unit is 50MPa~250MPa, which allows the molten material to fill the cavity flow channels, flow extension grooves, and slope compensation grooves. Further, a cooling medium is injected through the upper and lower molds to lower the temperature of the molten material inside the mold, bringing it to the solidification and molding temperature of 80℃~120℃.

[0057] In one embodiment, after the first cutting process of the first substrate and before the molding process of the first substrate and the second substrate, the following step is further included: The first substrate and the second substrate are cleaned and coated.

[0058] Understandably, ultrasonic cleaning of the surfaces of the first and second substrates after cutting removes cutting debris, ensuring high cleanliness requirements for both substrates. Furthermore, to prevent thermal deformation of the first and second substrates due to high temperatures during injection molding, a high-temperature resistant PET protective film is applied to the side of the first substrate contacting the lower mold, and the side of the second substrate contacting the upper mold is also covered with a high-temperature resistant PET protective film. This prevents thermal deformation of the first and second substrates during in-mold injection molding. Furthermore, applying a PE protective film to the side of the first substrate facing away from the lower mold, and the side of the second substrate facing away from the upper mold, prevents dust from adhering to the first and second substrates during transfer to the injection mold, ensuring high cleanliness of both substrates.

[0059] It should be noted that the PE protective film needs to be removed before the first and second substrates are placed into the mold.

[0060] In one embodiment, the filling resin layer is a polycarbonate resin layer. It is understood that the filling resin layer being a polycarbonate resin layer means the molten resin is polycarbonate resin, the same material as the PC material of the first and second substrates. During injection molding, the molten molten resin flows into the cavity runner and contacts the side of the first substrate facing away from the lower mold and the side of the second substrate facing away from the upper mold, i.e., the sides of the first and second substrates not covered with the PET protective film. The high temperature (280℃~340℃) of the molten resin causes the surfaces of the first and second substrates to slightly melt. The polycarbonate molecular chains at the interface between the molten resin and the substrate diffuse and entangle, forming a chemical bond similar to "welding" after cooling and molding. This effectively improves the connection stability between the three layers of the composite board, thus ensuring good consistency of the composite board. Furthermore, during injection molding, the molten molten resin flows into the flow extension groove, which increases the fluidity of the molten resin at the end of the cavity runner, allowing the molten resin to fill the cavity runner and flow extension groove, avoiding uneven molding of the filling resin layer and ensuring the integrity of the layered structure. On the other hand, the molten material can slightly melt with the surface of the flow extension tank, meaning that the polycarbonate molecular chains at the interface between the molten material and the tank diffuse and entangle, forming a chemical bond with a "welding" effect after cooling and molding, further improving the connection stability between the filler resin layer and the first substrate. Similarly, during injection molding, the molten material flows into the slope compensation tank, meaning that the molten material can slightly melt with a portion of the annular side surface of the second substrate, meaning that the polycarbonate molecular chains at the interface between the molten material and the annular side surface of the second substrate diffuse and entangle, forming a chemical bond with a "welding" effect after cooling and molding, further improving the connection stability between the filler resin layer and the second substrate. This effectively improves the molding yield and consistency of the composite board.

[0061] In one embodiment, the height of the crater structure of the composite board is the distance from the side of the second substrate facing away from the filling resin layer to the side of the first substrate close to the filling resin layer, and the height of the crater structure of the composite board is 1.5mm to 1.8mm. It is understood that different degrees of crater structure molding requirements can be selected according to the size design. In this embodiment, by setting the height of the crater structure of the composite board between 1.5mm and 1.8mm, it is possible to ensure that the crater structure has a sloping, three-dimensional feel while meeting the requirements of a thin and light design for the phone back cover when the composite board is applied to it.

[0062] Please see Figures 1 to 7 This application also provides a composite plate 10 with a crater, which is prepared by the molding process of the composite plate 10 with a crater as described in any of the above embodiments; The composite board 10 with a crater-like structure includes a first substrate 100, a second substrate 200, and a filling resin layer 300. A flow extension groove 102 is formed on the side of the first substrate 100 that is close to the first substrate. The first substrate 100 and the second substrate 200 are placed in an injection mold 20 so that when the injection mold 20 is closed, the slope insert 410, the first substrate 100, and the second substrate 200 together form a cavity flow channel 402 with a slope that communicates with the flow extension groove 102. The filling resin layer 300 is respectively attached to the first substrate 100 and the second substrate 200, and part of the filling resin layer 300 fills the flow extension groove 102.

[0063] In this embodiment, by setting the flow extension groove 102, and with the flow extension groove 102 located directly below the slope portion of the cavity flow channel 402, the flow extension groove 102 can serve as an extension portion of the cavity flow channel 402 when the injection mold 20 is closed. That is, it compensates for the gap of the slope portion of the cavity flow channel 402, increasing the gap of the end slope portion of the cavity flow channel 402. This allows the liquid material to be smoothly filled into the slope portion of the cavity flow channel 402. In other words, after the liquid material is formed, the filling resin layer 300 can completely fill the cavity flow channel 402 and the flow extension groove 102, avoiding the situation where the liquid material injection at the end slope portion of the cavity flow channel 402 is too small. This avoids the situation where the filling resin layer 300 has structural defects when the volcano slope of the composite board 10 is formed, thereby ensuring the consistency of the composite board 10 forming.

[0064] In one embodiment, the first substrate 100 has a first positioning hole 104, and the second substrate 200 has a second positioning groove 202. It is understood that the first positioning hole 104 and the second positioning groove 202 enable rapid positioning and mold insertion of the first substrate 100 and the second substrate 200, thereby improving mold insertion efficiency.

[0065] In one embodiment, the composite plate 10 with a crater structure is prepared using the injection mold 20 of this embodiment. The injection mold 20 includes an injection part 600, an upper mold 400, and a lower mold 500. The injection part 600 is disposed inside the upper mold 400. The upper mold 400 and the lower mold 500 are movably connected. The upper mold 400 is provided with an annular slope insert 410, and a substrate embedding groove 406 is formed at the center of the annular slope insert 410. The substrate embedding groove 406 has an inlet 408 that communicates with the outlet end of the injection part 600. The inlet 408 is also connected to the inlet of the second substrate 200. The through hole 204 is connected, and the substrate embedding groove 406 is also provided with a second positioning block 510 that is movably engaged with the second positioning groove 202 on the second substrate 200, so that the upper mold 400 is movably engaged with the second substrate 200. The lower mold 500 is provided with a first positioning block 420 that is movably engaged with the first positioning hole 104 on the first substrate 100, so that the lower mold 500 is movably engaged with the first substrate 100. When the upper mold 400 and the lower mold 500 are closed, the first substrate 100, the slope insert 410 and the second substrate 200 together form a cavity flow channel 402 with a slope that is connected to the flow extension groove 102. It is understandable that the injection molding part 600 is used to feed the molten material into the cavity flow channel 402 and the flow extension groove 102 through the injection molding part 600, the molten material is then fed into the cavity flow channel 402 and the flow extension groove 102 through the inlet 408 and the inlet through hole 204. This allows the filling resin layer 300 to be formed between the first substrate 100 and the second substrate 200 and to undergo a chemical bond similar to "welding" during the molding process, thereby improving the molding yield and consistency of the composite board 10.

[0066] Furthermore, there are multiple first positioning holes 104, second positioning grooves 202, first positioning blocks 420, and second positioning blocks 510. The number of first positioning holes 104 corresponds one-to-one with the number of first positioning blocks 420, and the number of second positioning grooves 202 corresponds one-to-one with the number of second positioning blocks 510. It can be understood that by setting multiple quantities, the molding efficiency of the first substrate 100 and the second substrate 200 is further improved.

[0067] Furthermore, in one embodiment, when the upper mold 400 and the lower mold 500 are closed, a portion of the annular side surface of the second substrate 200 and the slope insert 410 form a slope compensation groove 404. A portion of the resin-filled layer 300 fills the slope compensation groove 404, so that the portion of the resin-filled layer 300 is tightly bonded to the portion of the annular side surface of the second substrate 200. That is, a chemical bond with a "welding" effect occurs during the molding process, which not only ensures a stronger three-dimensional effect of the volcano-shaped slope surface of the composite board 10, but also improves the stability of the connection between the layers of the composite board 10, thereby improving the consistency of the composite board 10.

[0068] Furthermore, in one embodiment, the second substrate 200 has a feed through hole 204, which is movably connected to the feed inlet 408 and the cavity flow channel 402. It is understood that when the upper mold 400 and lower mold 500 are closed, the feed through hole 204 is connected to the feed inlet 408 and the cavity flow channel 402, allowing the molten material to be injected into the cavity flow channel 402 through the feed through hole 204 via the injection unit 600 and dispersed to the surrounding area. This ensures that the molten material fills the cavity flow channel 402, the flow extension groove 102, and the slope compensation groove 404, guaranteeing smooth injection of the molten material.

[0069] This application also provides a mobile phone back cover, characterized in that it includes the composite plate with a crater-like shape as described in the above embodiments.

[0070] In this embodiment, the composite plate with a crater-shaped surface prepared by the crater-shaped composite plate molding process of this application not only has a strong three-dimensional effect of the crater slope and good molding consistency, but also has a simple process and a high yield rate. When applied to the back cover of a mobile phone, it can meet the requirements of thin and light design while meeting the requirements of the high slope three-dimensional effect of the crater structure.

[0071] Compared with the prior art, this disclosure has at least the following advantages: 1. By inserting the first substrate and the second substrate into the mold, the first substrate and the second substrate are placed inside the injection mold. When the injection mold is closed, the slope insert of the injection mold, the first substrate, and the second substrate together form a cavity flow channel with a slope shape. Before the first substrate is inserted into the mold, the first substrate is cut to form a flow extension groove, and the flow extension groove is located directly below the slope portion of the cavity flow channel. This allows the flow extension groove to serve as an extension of the cavity flow channel when the injection mold is closed, thus compensating for the gap of the slope portion of the cavity flow channel. This increases the gap of the slope portion at the end of the cavity flow channel, allowing the liquid material to fill the slope portion of the cavity flow channel smoothly. This avoids the situation where the liquid material is injected too little at the end of the slope portion of the cavity flow channel, thereby avoiding defects in the volcano slope forming of the composite board and ensuring the consistency of the composite board forming.

[0072] 2. By directly obtaining the first substrate and cutting only one flow extension groove on the first substrate, on the one hand, there is no need for additional cold cutting and polishing of the main body of the first substrate, and the flow extension groove formed by cutting the first substrate is also filled by the filling resin layer, avoiding cutting and polishing errors on the first substrate. On the other hand, it also avoids the situation where the flow channel gap becomes smaller, resulting in a smaller amount of liquid injected, causing defects on the surface of the first substrate. Furthermore, the filling resin layer is integrally injection molded between the second substrate and the first substrate, and the second substrate and the filling resin layer together form the crater of the composite board. There is no need to polish the slope of the crater structure of the composite board, avoiding cutting and polishing errors on the crater slope of the composite board, thereby improving the molding yield of the composite board with crater, simplifying the operation steps of the molding process of the composite board with crater, and ensuring the consistency of the molding of the composite board with crater. Some specific embodiments are given below. When %, it means by weight percentage.

[0073] It should be noted that the following embodiments do not exhaust all possible situations, and the materials used in the following embodiments are commercially available unless otherwise specified.

[0074] Example 1

[0075] Both the first and second substrates are PC boards, and the molding liquid used for filling the resin layer is polycarbonate resin. In this process, the ambient temperature for both the first and second cutting processes is 25°C, the temperature of the molten material inside the barrel is 290°C, the injection pressure of the injection component is 100MPa, the thickness of the first substrate is 0.5mm, the thickness of the second substrate is 1.0mm, the crater structure is 1.5mm, the width of the flow extension groove is 2.5mm, and the depth of the flow extension groove is 0.06mm. The composite plate is prepared using the crater-shaped composite plate forming process of this application. A cross-sectional view of the composite plate is shown below. Figure 8 As shown.

[0076] Comparative Example 1 Both the first and second substrates are PC boards, and the liquid used to fill the resin layer is polycarbonate resin. In this process, the ambient temperature for both the first and second cutting processes is 25°C, the temperature of the molten material inside the barrel is 290°C, the injection pressure of the injection component is 100MPa, the thickness of the first substrate is 0.5mm, the thickness of the second substrate is 1.0mm, the crater structure is 1.5mm, the width of the flow extension groove is 2.5mm, and the depth of the flow extension groove is 0.03mm. The composite plate is prepared using the crater-shaped composite plate forming process of this application. The cross-sectional view of the composite plate is shown below. Figure 9 As shown.

[0077] Comparative Example 2 Both the first and second substrates are PC boards, and the liquid used to fill the resin layer is polycarbonate resin. In this process, the ambient temperature for both the first and second cutting processes is 25°C, the temperature of the molten material inside the barrel is 290°C, the injection pressure of the injection component is 100MPa, the thickness of the first substrate is 0.5mm, the thickness of the second substrate is 1.0mm, the crater structure is 1.5mm, the width of the flow extension groove is 2.5mm, and the depth of the flow extension groove is 0.1mm. The composite plate is prepared using the crater-shaped composite plate forming process of this application. A cross-sectional view of the composite plate is shown below. Figure 10 As shown.

[0078] Depend on Figures 8 to 10 In the cross-sectional view of the composite board in Example 1, the connection between the three layers (first substrate, filling resin layer and second substrate) is good, no black spots are generated, and the overall consistency is good. Black spots (gap or air bubbles at the connection) are present between the filling resin layer and the first and second substrates in the cavity flow channel end and the flow extension groove of the composite plate cross section in Comparative Example 1, indicating poor connection between layers and poor consistency. In the cross-sectional view of the composite plate in Comparative Example 2, black spots (gap or air bubbles at the connection) are also present between the filling resin layer in the cavity flow channel and the flow extension groove and the first and second substrates, indicating that the connection between the layers is not good and the consistency is poor. It can be seen that the difference between Example 1, Comparative Example 1 and Comparative Example 2 is the difference in the depth of the material extension channel.

[0079] When the depth of the material extension groove is less than 0.05 mm, i.e., Comparative Example 1, the compensation effect as an extension of the flow channel in the cavity is not good, that is, the effect of improving the fluidity of the liquid at the end of the flow channel in the cavity is not good, and there is still a problem of uneven material flow.

[0080] When the depth of the flow extension groove is greater than 0.08 mm, i.e., Comparative Example 2, although it can effectively supplement the extended part of the cavity flow channel and improve the flowability of the liquid at the end of the cavity flow channel, the liquid deposited in the flow extension groove is prone to generating air bubbles, which causes a gap between the filling resin layer and the first substrate, affecting the bonding strength between the layers, thereby reducing the consistency of the composite board, i.e. the tensile strength is inconsistent after the filling resin layer is bonded to the first substrate and the second substrate.

[0081] Therefore, the depth range of the material extension groove is preferably 0.05mm to 0.08mm. In this depth range of Example 1, it can not only effectively compensate for the flow channel in the cavity to improve the flowability of the liquid at the end of the flow channel in the cavity, but also avoid the situation where there is a gap at the connection between the filling resin layer and the first substrate due to excessive depth. It can determine the bonding strength between the three layers of the composite board and ensure the connection consistency between the three layers of the composite board, thereby improving the production yield of the composite board.

[0082] The embodiments described above are merely illustrative of several implementations of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the disclosed patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A molding process for a composite panel with a volcano-like crater, characterized in that, The steps include the following: Obtain the first substrate and the second substrate; The first substrate is subjected to a first cutting process to form a material flow extension groove on the first substrate; The first substrate and the second substrate are subjected to mold insertion processing so that the first substrate and the second substrate are placed in the injection mold. When the injection mold is closed, the slope insert of the injection mold, the first substrate and the second substrate together form a cavity flow channel with a slope that communicates with the flow extension channel. The cavity flow channel is subjected to injection molding to form a filling resin layer that is respectively bonded to the first substrate and the second substrate in the cavity flow channel and the flow extension groove, thereby obtaining a composite board; The second substrate and the filling resin layer together form the crater structure of the composite plate; The material extension channel is located directly below the sloping portion of the cavity flow channel.

2. The molding process for the composite panel with a volcano-like crater as described in claim 1, characterized in that, In the operation step of performing the first cutting process on the first substrate, a first positioning hole is also formed on the first substrate.

3. The molding process for the composite panel with a volcano-like crater as described in claim 2, characterized in that, After the step of performing the first cutting process on the first substrate, and before the step of performing the molding process on the first substrate and the second substrate, the following steps are also included: The second substrate is subjected to a second cutting process to form a second positioning groove on the second substrate.

4. The molding process for the composite panel with a volcano-like crater according to claim 3, characterized in that, The specific steps for molding the first substrate and the second substrate are as follows: The first positioning block of the lower mold of the injection mold is engaged in the first positioning hole of the first substrate, so that the first substrate is placed in the lower mold of the injection mold; The second positioning block of the upper mold of the injection mold is engaged in the first positioning groove of the second substrate, so that the second substrate is placed in the upper mold of the injection mold; The upper mold and the lower mold are combined.

5. The molding process for the composite panel with a crater-like structure according to claim 4, characterized in that, In the second cutting process of the second substrate, the second substrate is also formed with a feed through hole.

6. The molding process for the composite panel with a crater-like structure according to claim 5, characterized in that, The specific steps for injection molding the cavity flow channel are as follows: The injection mold upper mold injection component injects liquid material into the cavity flow channel through the feed through hole, and the liquid material fills the cavity flow channel and the flow extension groove; The injection mold is cooled and molded to solidify the liquid material in the cavity flow channel and the flow extension groove to form the filling resin layer that is respectively attached to the first substrate and the second substrate, and the composite plate with crater is formed.

7. The molding process for the composite panel with a crater-like structure according to claim 1, characterized in that, After the first cutting process of the first substrate and before the molding process of the first substrate and the second substrate, the following steps are also included: The first substrate and the second substrate are cleaned and coated.

8. The molding process for the composite panel with a volcano-like crater according to claim 1, characterized in that, The filling resin layer is a polycarbonate resin layer; and / or, The height of the crater structure of the composite board is the distance from the side of the second substrate facing away from the filling resin layer to the side of the first substrate close to the filling resin layer, and the height of the crater structure of the composite board is 1.5mm~1.8mm; and / or, Both the first substrate and the second substrate are PC boards; and / or, The thickness of the first substrate is 0.3 mm to 0.5 mm; and / or, The thickness of the second substrate is 0.1 mm to 1.0 mm; and / or, The depth of the material extension channel is 0.05mm to 0.08mm, and the width of the material extension channel is 2.0mm to 3.0mm.

9. A composite panel with a crater-like structure, characterized in that, The composite plate with a crater shape is prepared using any one of the molding processes described in claims 1-8; The composite board with a crater-like structure includes a first substrate, a second substrate, and a filling resin layer. A flow extension groove is formed on the side of the first substrate that is close to the first substrate. The first substrate and the second substrate are used to place the first substrate and the second substrate in an injection mold so that when the injection mold is closed, the slope insert of the injection mold, the first substrate, and the second substrate together form a cavity flow channel with a slope that communicates with the flow extension groove. The flow extension groove is located directly below the slope portion of the cavity flow channel. The filling resin layer is respectively attached to the first substrate and the second substrate, and a portion of the filling resin layer fills the flow extension groove.

10. A mobile phone back cover, characterized in that, Including the composite panel with a crater as described in claim 9.

Images