Plastic coating and core removing process of plastic coating and core removing structural part

Abstract

The invention discloses a plastic-coated core-removing process of a plastic-coated core-removing structural member, which comprises the following steps: injection molding of a mold core insert: selecting water-soluble thermoplastic polyvinyl alcohol, and forming the mold core insert in an injection mold, wherein the melt temperature of the injection mold is 5-15 DEG C higher than the melting temperature, and the mold temperature is 40-65 DEG C lower than the melting temperature; injection molding of a plastic-coated structural member: selecting a recycled polycarbonate composite material, and performing injection molding on the mold core insert through a plastic-coated mold to form the plastic-coated structural member, the melt temperature of the plastic-coated mold being 260-310 DEG C, and the mold temperature being 80-110 DEG C; and core removal: removing the mold core insert through water dissolution. The water-soluble mold core insert is subjected to plastic coating and then dissolved in water to obtain the plastic-coated structural part, the production efficiency is greatly improved through combination of injection molding and plastic coating, melting and deformation are reduced through cooperation of materials and the technology, and the percent of pass is guaranteed. Thermal isolation and protection are achieved in the mode that the emulsion wax type water wax coating layer is coated, deformation and melting are remarkably improved, and the percent of pass is remarkably increased.

Description

TECHNICAL FIELD

[0001] The application relates to a plastic-coated core-removing process for a plastic-coated core-removed structural member, and belongs to the technical field of injection molding. BACKGROUND

[0002] Injection molding, also known as injection molding, is a molding method that combines injection and molding. The advantages of injection molding method are high production speed and efficiency, automatic operation, various colors and shapes, and accurate product size. The product is easy to update, can form complex parts, and is suitable for mass production and complex product molding processing fields. At a certain temperature, the completely melted plastic material is stirred by a screw, injected into a mold cavity under high pressure, and then solidified after cooling to obtain a molded product. This method is suitable for batch production of complex parts and is one of the important processing methods.

[0003] At present, there is a kind of electronic structural member forming, which includes a shell with a cavity, and a plurality of extension pipelines are arranged on the side wall of the shell. The structural member is difficult to realize one-time injection molding, so the core-removing process needs to be used. For example, a water-soluble core material and its preparation method for replacing complex core-pulling structure disclosed in application publication No. CN116442442A. When the mold is filled with water-soluble mixture, the core material is formed after shaping, thereby meeting the plastic molding demand. Such core material is convenient for water-soluble core removal, but its molding cycle is long, and the bonding and deformation between the plastic material and the core material are prone to occur during the later plastic molding process. Especially when the plastic injection temperature is high, the injection material temperature exceeds the melting point of the plastic material, the deformation amount is large, and the product molding qualification rate is affected.

[0004] In addition, in order to meet the environmental protection and product performance requirements, the material of the injection molded part is limited at present. PCR PC is the abbreviation of Post-Consumer Recycled Polycarbonate, which is a kind of renewable polycarbonate material obtained by recycling and processing of post-consumer waste polycarbonate (PC) products. It has the basic performance and environmental properties of PC material, and is widely used in the trend of sustainable development. The injection molding temperature of such injection material is generally above 260℃, so the material properties of the core insert are required to be high, and the existing core insert is generally divided into mold pressing core material and injection molding core material. The characteristics of the mold pressing core material are long production cycle and large defects in the inner wall of the injection molded part during the plastic molding process. The injection molding core material meets the batch production and processing demand, but its melting temperature is low, which causes the deformation of the plastic structure, and it is also prone to bonding. SUMMARY

[0005] The application aims to solve the problems of the prior art, and provides a plastic-coated core-removed structural part and a plastic-coated core-removed process thereof.

[0006] To achieve the above-mentioned purpose, the application adopts the technical scheme of: The application provides a plastic-coated core-removed process of a plastic-coated core-removed structural part, which comprises a plastic-coated structural part and a core insert located in the plastic-coated structural part, and comprises the following steps: S1, core insert injection molding, selecting water-soluble thermoplastic polyvinyl alcohol to form a core insert in an injection mold, wherein the water-soluble thermoplastic polyvinyl alcohol has a melting temperature of 190-225 DEG C, a 0.45 MPa heat distortion temperature HDT greater than 100 DEG C, a shrinkage rate MD less than 1.5%, a shrinkage rate TD less than 0.1%, the injection mold has a melt temperature 5-15 DEG C higher than the melting temperature, and the mold temperature is 40-65 DEG C lower than the melting temperature; S2, plastic-coated structural part injection molding, selecting a recycled polycarbonate composite material to form a plastic-coated structural part on the core insert through a plastic-coated mold, wherein the recycled polycarbonate composite material has a 0.45 MPa heat distortion temperature HDT greater than 100 DEG C, the plastic-coated mold has a melt temperature of 260-310 DEG C and a mold temperature of 80-110 DEG C; S3, core removal, water-soluble removal of the core insert, wherein the water temperature is higher than the dissolution temperature of the water-soluble thermoplastic polyvinyl alcohol.

[0007] Preferably, in the step S1, the back pressure of the injection mold is 10±5 MPa, the injection pressure is 140-210 MPa, and the holding pressure is 30-55 MPa.

[0008] Preferably, in the step S1, the water-soluble thermoplastic polyvinyl alcohol comprises, in terms of mass fraction, polyvinyl alcohol base material 60-70 parts, composite plasticizer 10-20 parts, reinforcing filler 10-15 parts, crosslinking agent 1-1.5 parts, and antioxidant 0.5-1 part.

[0009] Preferably, in the step S2, the back pressure of the plastic-coated mold is 0.1-0.3 MPa.

[0010] Preferably, in the step S2, the recycled polycarbonate composite material comprises, in terms of mass fraction, polycarbonate 40-60 parts, glass fiber 15-25 parts, halogen-free phosphate ester flame retardant 8-12 parts, synergist 1-3 parts, antioxidant 0.1-0.5 parts, lubricant 0.3-1 part, heat stabilizer 0.1-0.3 part, and color master batch 1-3 parts, wherein the mass fraction of post-consumer recycled polycarbonate in the polycarbonate is not less than 80%.

[0011] Preferably, in the step S2, the plastic packaging mold comprises a first injection mold base and a second injection mold base with relative mold displacement, the first injection mold base is internally provided with a first mold cavity for limiting and adsorbing the core insert, and the second injection mold base is internally provided with a jacking limiting table with jacking displacement towards the core insert.

[0012] Preferably, the first injection mold base is provided with a jacking driving mechanism for driving the jacking displacement of the jacking limiting table, and the jacking limiting table and the first injection mold base are provided with an elastic floating part therebetween, and the jacking driving mechanism comprises a driving sliding table with linear displacement, and the driving sliding table and the jacking limiting table are provided with a mortise and tenon structure with relative misalignment cooperation therebetween, and the linear displacement direction of the driving sliding table is perpendicular to the jacking displacement direction of the jacking limiting table.

[0013] Preferably, in the step S3, the core insert is removed through water circulation and / or ultrasonic dissolution, and the water temperature is 80-95 DEG C.

[0014] Preferably, in the step S1, after the core insert is formed, a milk wax type water wax coating layer is coated on the outer surface of the core insert, and the melting point of the milk wax type water wax coating layer is greater than 200 DEG C.

[0015] The beneficial effects of the present application mainly include: 1. The water-soluble core insert is used to obtain a plastic packaging structure after water dissolution, and the combination of injection molding and plastic packaging greatly improves the production efficiency, and the melting and deformation are reduced through the cooperation of materials and processes, thereby ensuring the qualified rate.

[0016] 2. The hot isolation and protection are realized by coating the milk wax type water wax coating layer, the deformation and melting are significantly improved, and the qualified rate is significantly improved.

[0017] 3. The jacking limiting design of the core insert is provided, which ensures smooth and stable operation of the plastic packaging operation, and the structure of the plastic packaging formed product is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0018] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings: Figure 1 is a process flow diagram of the plastic packaging core removal process of the present application.

[0019] Figure 2 is a structure diagram of a plastic packaging mold in the plastic packaging core removal process of the present application.

[0020] Figure 3 is a side view structure diagram of a plastic packaging mold in the plastic packaging core removal process of the present application.

[0021] Figure 4Figure 1 is a schematic diagram of a partial default structure of a plastic-coated mold in a plastic-coated core-removing process of the present application.

[0022] Figure 5 Figure 2 is a schematic diagram of a structure of a second injection mold base in the plastic-coated core-removing process of the present application.

[0023] Figure 6 Figure 3 is a schematic diagram of a structure of a first injection mold base in the plastic-coated core-removing process of the present application. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in a clear and complete manner with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of the present application.

[0025] The present application will be further described below in detail with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, but not to limit the application. In addition, it should be noted that, for the convenience of description, only the parts related to the application are shown in the drawings. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0026] The present application provides a plastic-coated core-removing process of a plastic-coated core-removing structural member, including a plastic-coated structural member and a core insert located in the plastic-coated structural member, comprising the following steps: The core insert is injection molded, and water-soluble thermoplastic polyvinyl alcohol is selected to form the core insert in an injection mold, the melting temperature of the water-soluble thermoplastic polyvinyl alcohol is 190-225℃, the heat distortion temperature HDT at 0.45MPa is greater than 100℃, the shrinkage rate in the longitudinal direction MD is less than 1.5%, the shrinkage rate in the transverse direction TD is less than 0.1%, the melt temperature of the injection mold is higher than the melting temperature by 5-15℃, and the mold temperature is lower than the melting temperature by 40-65℃.

[0027] The plastic-encased structure is injection molded, a recycled polycarbonate composite material is selected, and the plastic-encased structure is formed on the core insert through a plastic-encased mold injection, the recycled polycarbonate composite material comprises, in terms of mass fraction, polycarbonate 40-60 parts, glass fiber 15-25 parts, halogen-free phosphate ester flame retardant 8-12 parts, synergist 1-3 parts, antioxidant 0.1-0.5 parts, lubricant 0.3-1 parts, thermal stabilizer 0.1-0.3 parts, and color master batch 1-3 parts, wherein the mass fraction of post-consumer recycled polycarbonate in the polycarbonate is not less than 80%, the 0.45MPa heat distortion temperature HDT of the recycled polycarbonate composite material is greater than 100℃, and the melt temperature of the plastic-encased mold is 260℃-310℃ and the mold temperature is 80℃-110℃.

[0028] Debinding, water-soluble core insert is removed, and the water temperature is higher than the dissolution temperature of the water-soluble thermoplastic polyvinyl alcohol.

[0029] The specific implementation process and principle are described as follows: The water-soluble thermoplastic polyvinyl alcohol belongs to the prior art, which meets the requirements of injection molding material and water-soluble requirements, and is used as a core insert material. In the present case, the water-soluble thermoplastic polyvinyl alcohol can use the finished base material of Jishui Chemical AP-001, AP-002 and AP-003.

[0030] The technical data of Jishui Chemical AP-001, AP-002 and AP-003 are as follows: AP-001: density 1.5g / cm 3 , 0.45MPa heat distortion temperature HDT 100℃, shrinkage MD:1.3 TD:0.05, melting temperature 204℃; AP-002: density 1.5g / cm 3 , 0.45MPa heat distortion temperature HDT 125℃, shrinkage MD:1.3 TD:0.05, melting temperature 202℃; AP-003: density 1.5g / cm 3 , 0.45MPa heat distortion temperature HDT 160℃, shrinkage MD:1.3 TD:0.05, melting temperature 204℃. It meets the requirements of thermoplasticity and water-soluble removal at the back end as a core insert material.

[0031] According to the melting temperature of the water-soluble thermoplastic polyvinyl alcohol, the corresponding melt temperature and mold temperature of the injection mold are set, which meets the requirements of complete molding and smooth surface of the core insert.

[0032] The recycled polycarbonate composite material can generally select a finished material, and the composite material with the trademark LNP™ ELCRIN™ DX2341RC1 of Saudi Basic Industries Corporation can be selected.

[0033] The following table is the mechanical property of LNP™ ELCRIN™ DX2341RC1: Performance Typical Value Unit Test Standard Tensile stress at yield (5 mm / min) 99 MPa ISO 527 Tensile stress at break (5 mm / min) 99 MPa ISO 527 Tensile strain at yield (5 mm / min) 2.4 % ISO 527 Tensile strain at break (5 mm / min) 2.4 % ISO 527 Tensile modulus (1 mm / min) 6000 MPa ISO 527 Flexural stress at break (2 mm / min) 162 MPa ISO 178 Flexural modulus (2 mm / min) 6100 MPa ISO 178 Type I tensile stress at yield (5 mm / min) 101 MPa ASTM D638 Type I tensile stress at break (5 mm / min) 103 MPa ASTM D638 Type I tensile strain at yield (5 mm / min) 2.5 % ASTM D638 Type I tensile strain at break (5 mm / min) 3.3 % ASTM D638 Tensile modulus (5 mm / min) 6100 MPa ASTM D638 Flexural stress at break (1.3 mm / min, 50 mm span) 159 MPa ASTM D790 Flexural modulus (1.3 mm / min, 50 mm span) 6000 MPa ASTM D790

[0034] The following table is the thermal property of LNP™ ELCRIN™ DX2341RC1: Performance Typical Value Unit Test Standard Heat deflection temperature (HDT, 0.45 MPa) 123 ℃ ISO 75 / Bf Heat deflection temperature (HDT, 1.8 MPa) 118 ℃ ISO 75 / Af Vicat softening temperature (rate B / 50) 125 ℃ ASTM D1525 Vicat softening temperature (rate B / 120) 127 ℃ ASTM D1525 HDT (0.45 MPa, 3.2 mm, unannealed) 121 ℃ ASTM D648 HDT (1.82 MPa, 3.2 mm, unannealed) 116 ℃ ASTM D648 Coefficient of linear thermal expansion (CTE, flow direction) 27 1 / ℃ ASTM E831 Coefficient of linear thermal expansion (CTE, transverse flow direction) 79 1 / ℃ ASTM E831

[0035] The following table is the physical property of LNP™ ELCRIN™ DX2341RC1: Performance Typical Value Unit Test Standard Density 1.34 g / cm 3 ]] ISO 1183 Water absorption (23°C / 50% RH) 0.02 % ISO 62 Melt volume flow rate (300°C / 1.2 kg) 11 cm 3 / 10 min ISO 1133 Melt volume flow rate (300°C / 2.16 kg) 22 cm 3 / 10 min ISO 1133 Specific gravity 1.35 - ASTM D792 Molding shrinkage (flow direction) 0.3–0.5 % SABIC Method Molding shrinkage (transverse flow direction) 0.3–0.5 % SABIC Method Melt flow rate (300°C / 1.2 kgf) 12 g / 10 min ASTM D1238 Melt flow rate (300°C / 2.16 kgf) 24 g / 10 min ASTM D1238

[0036] When performing over-molding, the core insert is placed in the over-molding mold, and the mold is preheated to 80-110°C before over-molding is performed, and the over-molded structure is formed on the core insert.

[0037] When over-molding is completed, the core insert is removed by water dissolution, and the water temperature is generally 65-95°C. The core insert is removed by water circulation and / or ultrasonic dissolution during water dissolution, that is, water circulation system is used for flushing, ultrasonic container is used for ultrasonic dissolution, or both methods are combined, and the preferred water temperature is 80-95°C. The dissolution rate is improved.

[0038] The recycled polycarbonate composite material is described in detail. The recycled polycarbonate composite material includes, by mass fraction: polycarbonate 40-60 parts, glass fiber 15-25 parts, halogen-free phosphate ester flame retardant 8-12 parts, synergist 1-3 parts, antioxidant 0.1-0.5 parts, lubricant 0.3-1 part, thermal stabilizer 0.1-0.3 part, and color master batch 1-3 parts. The mass fraction of post-consumer recycled polycarbonate in polycarbonate is not less than 80%, and the 0.45 MPa heat distortion temperature HDT of the recycled polycarbonate composite material is greater than 100°C.

[0039] The polycarbonate contains 10-15% high-heat-resistant polycarbonate, which can use Covestro 2605; the glass fiber is generally recycled glass fiber material; the halogen-free phosphate ester flame retardant generally uses phosphate oligomer and diphenyl phosphate; the synergist selects melamine cyanurate (MCA) or polysiloxane; the antioxidant generally selects hindered phenolic antioxidant; the lubricant is generally silicone oil; the thermal stabilizer is generally organic tin stabilizer; and the color master batch is carbon powder.

[0040] In this way, the structural strength of injection molding is met, and the basic mechanical properties of the material are improved, which meets the basic performance of over-molded structural parts and the over-molding requirements.

[0041] In one embodiment, the water-soluble thermoplastic polyvinyl alcohol comprises, by mass fraction: polyvinyl alcohol base material 60-70 parts, composite plasticizer 10-20 parts, reinforcing filler 10-15 parts, crosslinking agent 1-1.5 parts, and antioxidant 0.5-1 part.

[0042] The polyvinyl alcohol base material is selected from Kuraray PVA2488, the composite plasticizer is selected from PEG, glycerol, and metal salt, the reinforcing filler is selected from montmorillonite or fumed silica, the crosslinking agent is selected from an epoxy crosslinking agent, and the antioxidant is selected from a hindered phenol and a phosphite ester, thereby meeting the basic performance requirements of the water-soluble thermoplastic polyvinyl alcohol.

[0043] It should be noted that, in the present case, the water-soluble thermoplastic polyvinyl alcohol can be selected from Kuraray MOWIFLEX™ LP M 05, Kuraray MOWIFLEX™ H15, and Kuraray MOWIFLEX™ C 17, in addition to the AP-001, AP-002, and AP-003 brand materials of Jukwang Chemical.

[0044] In one embodiment, the back pressure of the injection mold is 10±5 MPa, the injection pressure is 140-210 MPa, and the holding pressure is 30-55 MPa. The back pressure of the overmolding mold is 0.1-0.3 MPa.

[0045] The high pressure of the core insert satisfies the integrity requirement of the workpiece and ensures the smoothness and integrity of the surface. The low back pressure design of the overmolding structure part can avoid overheating degradation, so that the deformation of the abutting surface between the overmolding structure part and the core insert is small, the sintering and melting conditions are improved, and the water-soluble residue is reduced.

[0046] In the experimental stage, BS-01 and BS-02 water-soluble thermoplastic polyvinyl alcohol are selected. BS-01 comprises, by mass fraction: Kuraray PVA2488 65 parts, PEG4000 10 parts, glycerol 5 parts, fumed silica 12 parts, epoxy crosslinking agent 1 part, and hindered phenol 0.5 part. BS-02 comprises, by mass fraction: Kuraray PVA2488 70 parts, PEG4000 5 parts, glycerol 5 parts, nano-montmorillonite particles 10 parts, epoxy crosslinking agent 1.5 parts, and hindered phenol 0.5 part.

[0047] The melting temperature of BS-01 is 207℃, the 0.45 MPa heat distortion temperature HDT is 155℃, the shrinkage rate in the longitudinal direction MD is 1.1%, and the shrinkage rate in the transverse direction TD is 0.03%. The melting temperature of BS-02 is 201℃, the 0.45 MPa heat distortion temperature HDT is 138℃, the shrinkage rate in the longitudinal direction MD is 1.1%, and the shrinkage rate in the transverse direction TD is 0.03%. These meet the characteristic requirements of the water-soluble thermoplastic polyvinyl alcohol.

[0048] The following is the performance of the core insert corresponding to the injection molding parameter table: Grade AP-001 AP-002 AP-003 H 15 BS-01 BS-02 Mechanical strength (heat deflection temperature, HDT) °C 100 125 160 None 155 138 Shrinkage % MD: 1.3 TD: 0.05 MD: 1.3 TD: 0.05 MD: 1.3 TD: 0.05 None MD: 1.1 TD: 0.03 MD: 1.1 TD: 0.03 Melting temperature (Tm) °C 204 202 204 215 207 201 Drying temperature before molding °C 80 80 80 80 80 80 Dissolution recommended conditions °C 85 85 85 85 85 85 Injection molding temperature °C 210 210 210 225 215 215 Mold temperature °C 160 160 160 175 160 160 Back pressure MPa 10 10 10 15 15 15 Injection pressure MPa 140 210 210 160 160 200 Holding pressure MPa 30 40 50 40 40 55 Screw recovery time (sec) 2.08 2.08 2.08 2.08 2.08 2.08 Resin residence time (min) 5.29 5.29 5.29 5.29 5.29 4.96

[0049] Using AP-001, AP-002, AP-003, H 15, BS-01, BS-02, the core insert is completed by injection molding, and the outer surface is flawless. The core insert molding qualified rate is more than 99.8%.

[0050] During the experimental stage, the recycled polycarbonate composite material is compounded with BS-PC1, which includes polycarbonate 55 parts, glass fiber 20 parts, diphenyl phosphate 10 parts, polysiloxane 2 parts, hindered phenol antioxidant 0.2 parts, silicone oil 0.5 parts, organic tin stabilizer 0.1 parts, and carbon powder 1 parts by mass fraction.

[0051] Using LNP™ ELCRIN™ DX2341RC1 and BS-PC1, the core insert molded by AP-001, AP-002, AP-003, H 15, BS-01, BS-02 is used to make a plastic structure. The injection molding parameters are: the maximum moisture content of the raw material is less than 0.02%, the temperature of the rear area is 260~280℃, the temperature of the middle area is 270~290℃, the temperature of the front area is 280~310℃, the nozzle temperature is 285~305℃, the mold temperature is 80℃~110℃, and the screw rotation speed is 50~90rpm.

[0052] Core missing cover detection, warpage detection, melting trace detection, gate detection, and dissolution residue detection are performed: LNP™ ELCRIN™ DX2341RC1 plastic packaging experiment results: LNP™ ELCRIN™ DX2341RC1 and AP001, no missing, warpage reaches 0.08mm; there are obvious melting traces along the plastic filling path, especially in the local damage of the geometric shape at the gate. The qualified rate is 77.2%. The dissolution rate of 80℃ water circulation dissolution for 30min is 36.5%, the dissolution rate of 80℃ water circulation dissolution for 240min is 97.9%, the dissolution rate of 90℃ water circulation dissolution for 30min is 36.6%, and the dissolution rate of 90℃ water circulation dissolution for 240min is 97.4%.

[0053] LNP™ ELCRIN™ DX2341 RC1 with AP002, no defects, warpage reached 0.12 mm; there were clear traces of melting along the plastic filling path, especially at the gate. Thin films of core material were found due to erosion by high temperature and injection force. The percentage of acceptance was 82.1 %. The dissolution rate was 28.2% at 80°C for 30 minutes, 89.4% at 80°C for 240 minutes, 28.7% at 90°C for 30 minutes, and 91.9% at 90°C for 240 minutes.

[0054] LNP™ ELCRIN™ DX2341 RC1 with AP003, no defects, warpage reached 0.11 mm; there were clear traces of melting along the plastic filling path, especially at the gate. Even though this material could not fully resist high temperatures, there were no major deformations and traces of melting at the end of filling. The percentage of acceptance was 91.5 %. The dissolution rate was 18.4% at 80°C for 30 minutes, 89.5% at 80°C for 240 minutes, 18.7% at 90°C for 30 minutes, and 90.2% at 90°C for 240 minutes.

[0055] LNP™ ELCRIN™ DX2341 RC1 with H15, no defects, warpage reached 0.11 mm; there were clear traces of melting along the plastic filling path, especially at the gate, the geometry was severely damaged, and the percentage of acceptance was 30.3 %. The dissolution rate was 85.2% at 80°C for 30 minutes, 98.0% at 80°C for 240 minutes, 86.7% at 90°C for 30 minutes, and 97.3% at 90°C for 240 minutes.

[0056] LNP™ ELCRIN™ DX2341 RC1 with BS-01, no defects, warpage reached 0.09 mm; there were traces of melting along the plastic filling path, and the traces were clearly visible at the gate. There were no major deformations and traces of melting at the end of filling. The percentage of acceptance was 95.5 %. The dissolution rate was 75.7% at 80°C for 30 minutes, 98.2% at 80°C for 240 minutes, 79.3% at 90°C for 30 minutes, and 97.9% at 90°C for 240 minutes.

[0057] LNP™ ELCRIN™ DX2341 RC1 with BS-02, no missing, warpage reached 0.11 mm; there were melting marks along the plastic filling path, and traces were present at the gate. There was no large deformation and melting marks at the end of filling. The qualified rate was 96.2%. The dissolution rate was 66.2% after 30 min of water circulation at 80°C, 97.8% after 240 min of water circulation at 80°C, 68.7% after 30 min of water circulation at 90°C, and 98.1% after 240 min of water circulation at 90°C.

[0058] BS-PC1 plastic packaging experiment results, which is similar to LNP™ ELCRIN™ DX2341 RC1, but from the plastic packaging contact surface melting state part detection, its melting marks are improved to some extent.

[0059] BS-PC1 with AP001, no missing, warpage reached 0.09 mm; there were melting marks along the plastic filling path, and local deformation of the geometric shape was present at the gate. The qualified rate was 80.2%.

[0060] BS-PC1 with AP002, no missing, warpage reached 0.12 mm; there were melting marks along the plastic filling path, especially at the gate. Thin films of core material were found due to erosion by high temperature and injection force. The qualified rate was 85.5%.

[0061] BS-PC1 with AP003, no missing, warpage reached 0.1 mm; there were melting marks at the gate. The qualified rate was 96.5%.

[0062] BS-PC1 with H15, no missing, warpage reached 0.11 mm; there were obvious melting marks along the plastic filling path, especially at the gate geometry which was severely damaged, and the qualified rate was 29.2%.

[0063] BS-PC1 with BS-01, no missing, warpage reached 0.11 mm; there were melting marks along the plastic filling path, and traces were present at the gate. There was no large deformation and melting marks at the end of filling. The qualified rate was 96.9%.

[0064] BS-PC1 with BS-02, no missing, warpage reached 0.1 mm; there were melting marks along the plastic filling path, and traces were present at the gate. There was no large deformation and melting marks at the end of filling. The qualified rate was 95.8%.

[0065] Thus, the molding integrity and deformation degree are controlled to some extent, and the product qualified rate is basically guaranteed.

[0066] In one specific embodiment, as Figures 2 to 6As shown, the over-molding mold 100 comprises a first injection mold base 1 and a second injection mold base 2 with relative mold closing displacement.

[0067] The first injection mold base 1 is provided with a first mold cavity 10 for limiting and adsorbing the core insert, and the second injection mold base 2 is provided with a jacking limiting table 20 with jacking displacement towards the core insert.

[0068] Specifically, after the core insert is molded and cooled, the core insert is positioned and placed in the first mold cavity 10 for adsorption and fixation, and is pre-heated after being clamped and fixed by the jacking limiting table 20.

[0069] During the over-molding mold extrusion operation, the jacking limiting table 20 is retracted to reserve an over-molding space, which can improve the pre-heating temperature, so that the core insert is rapidly heated to the required temperature, and after the peripheral wall is over-molded, the jacking limiting table is retracted to provide an over-molding bottom sealing space, ensuring reliable over-molding, and reducing the melting marks and deformation to a certain extent, especially the gate part, so that the product qualification rate is improved.

[0070] In a specific embodiment, the first injection mold base is provided with a jacking drive mechanism for driving the jacking displacement of the jacking limiting table, and the jacking limiting table and the first injection mold base are provided with an elastic floating part, the jacking drive mechanism comprises a drive sliding table with linear displacement, the drive sliding table and the jacking limiting table are provided with a mortise and tenon structure with relative misalignment, and the linear displacement direction of the drive sliding table is perpendicular to the jacking displacement direction of the jacking limiting table.

[0071] In this way, the displacement driving requirement of the jacking limiting table 20 is met, and the stroke has the characteristics of reliable response and high efficiency.

[0072] In a preferred embodiment, after the core insert is formed, a milk wax type water wax coating layer is coated on the outer surface of the core insert, and the melting point of the milk wax type water wax coating layer is greater than 200℃. Polypropylene wax emulsion can be used.

[0073] Experiments were conducted using the milk wax type water wax coating layer before over-molding: BS-PC1, AP001, AP002, AP003, BS-01 and BS-02, the over-molding structure has no missing, the warpage is not more than 0.08mm, and only a slight melting mark exists at the gate. The qualification rate is more than 96%.

[0074] From the above description, it can be found that,

[0075] The term "comprising" or any other similar word is intended to encompass non-exclusive inclusion, so that the process, method, article or equipment / device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes the elements inherent to the process, method, article or equipment / device.

[0076] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will all fall within the protection scope of the present application.

Claims

1. A process for encasing a cored structural member, comprising an encased structural member and a core insert positioned within the encased structural member, characterized by The process comprises the following steps: S1: core insert injection molding, selecting water-soluble thermoplastic polyvinyl alcohol, forming a core insert in an injection mold, the water-soluble thermoplastic polyvinyl alcohol has a melting temperature of 190-225℃, a 0.45MPa heat distortion temperature HDT greater than 100℃, a shrinkage rate MD less than 1.5%, and a shrinkage rate TD less than 0.1%, the melt temperature of the injection mold is 5-15℃ higher than the melting temperature, and the mold temperature is 40-65℃ lower than the melting temperature; S2: plastic-encased structural part injection molding, selecting recycled polycarbonate composite material, forming a plastic-encased structural part on the core insert through a plastic-encased mold, the recycled polycarbonate composite material has a 0.45MPa heat distortion temperature HDT greater than 100℃, the melt temperature of the plastic-encased mold is 260-310℃, and the mold temperature is 80-110℃; S3: core removal, water-soluble removal of the core insert, the water temperature is higher than the dissolution temperature of the water-soluble thermoplastic polyvinyl alcohol.

2. The plastic-encased core removal process of claim 1, wherein: in the step S1, the back pressure of the injection mold is 10±5MPa, the injection pressure is 140-210MPa, and the holding pressure is 30-55MPa.

3. The plastic-encased core removal process of claim 1, wherein: in the step S1, the water-soluble thermoplastic polyvinyl alcohol comprises, by mass fraction, polyvinyl alcohol base material 60-70 parts, composite plasticizer 10-20 parts, reinforcing filler 10-15 parts, crosslinking agent 1-1.5 parts, and antioxidant 0.5-1 part.

4. The plastic-encased core removal process of claim 1, wherein: in the step S2, the back pressure of the plastic-encased mold is 0.1-0.3MPa.

5. The plastic-encased core removal process of claim 1, wherein: in the step S2, the recycled polycarbonate composite material comprises, by mass fraction, polycarbonate 40-60 parts, glass fiber 15-25 parts, halogen-free phosphate ester flame retardant 8-12 parts, synergist 1-3 parts, antioxidant 0.1-0.5 parts, lubricant 0.3-1 parts, heat stabilizer 0.1-0.3 parts, and color master batch 1-3 parts, and the mass fraction of post-consumer recycled polycarbonate in the polycarbonate is not less than 80%.

6. The plastic-encased core removal process of claim 1, wherein: in the step S2, the plastic-encased mold comprises a first injection mold base and a second injection mold base with relative mold closing displacement, the first injection mold base is provided with a first mold cavity for limiting and adsorbing the core insert, and the second injection mold base is provided with a jacking limiting table with jacking displacement towards the core insert.

7. The plastic-encased core removal process of claim 6, wherein: The first injection mold base is provided with a jacking driving mechanism for driving the jacking displacement of the jacking limiting table, an elastic floating part is arranged between the jacking limiting table and the first injection mold base, the jacking driving mechanism comprises a driving sliding table with linear displacement, a mortise and tenon structure with relative misalignment is arranged between the driving sliding table and the jacking limiting table, and the linear displacement direction of the driving sliding table is perpendicular to the jacking displacement direction of the jacking limiting table.

8. The plastic-coated core-removed structural member packaging and core-removing process according to claim 1, characterized in that: In the step S3, the core insert is removed by water circulation and / or ultrasonic dissolution, and the water temperature is 80-95 DEG C.

9. The plastic-coated core-removed structural member packaging and core-removing process according to any one of claims 1-8, characterized in that: In the step S1, after the core insert is formed, a milk wax type water wax coating layer is coated on the outer surface of the core insert, and the melting point of the milk wax type water wax coating layer is greater than 200 DEG C.

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