Integrated injection molding method for transparent and opaque materials of automobile lampshade

Abstract

The invention discloses an integrated injection molding method for transparent and opaque materials of an automobile lampshade, and aims to solve the problems of infirm interface bonding, low production efficiency and unstable product quality in the prior art. The method comprises the steps of material pretreatment, staged injection molding, interface fusion enhancement, gradient cooling and the like. By optimizing temperature control, viscosity matching and compatilizer adding, efficient fusion of a transparent material and an opaque material is achieved, and the mechanical performance and optical quality of a product are improved. The method is simple in process, high in production efficiency and suitable for large-scale production of automobile lampshades, and has wide application prospects.

Description

Technical Field

[0001] The invention relates to a method for integrally injecting transparent and opaque materials of an automobile lampshade. Background Art

[0002] In the field of automobile manufacturing, lampshades, as an important part of the automobile lighting system, need to meet the requirements of high transparency to ensure optical performance, and also need to have a certain opaque area to achieve functions such as aesthetics, anti-glare and structural support. Traditional automobile lampshade production usually adopts two methods:

[0003] Independent injection molding + bonding process: The transparent and opaque parts are separately injected, and then assembled by bonding or welding. This method easily leads to weak interface bonding, poor weather resistance, and a long process flow, which increases production costs.

[0004] Two-color injection molding: Two-color injection molding machines are used to mold two materials in the same mold. However, due to the different physical and chemical properties of transparent and opaque materials, direct two-color injection molding may lead to insufficient interface bonding, delamination, peeling and other problems, affecting the service life and appearance quality of the product.

[0005] Therefore, there is an urgent need for an improved injection molding method that can efficiently mold transparent materials and opaque materials in the same mold, ensure the interface fusion quality between the two, and improve the mechanical strength and optical properties of the product. Summary of the invention

[0006] The purpose of the present invention is to solve the above deficiencies in the prior art and to provide a method for integrally injecting transparent and opaque materials into a car lampshade.

[0007] A method for integrally injecting transparent and opaque materials into a car lampshade, comprising the following steps:

[0008] Step 1: Material pretreatment

[0009] Transparent Materials:

[0010] Pre-drying treatment: 100-120℃ hot air circulation drying for 4-6 hours, so that the moisture content of the material is ≤0.02%;

[0011] Melting temperature: 240-300°C, screw speed 40-60rpm;

[0012] Opaque Materials:

[0013] Pre-drying treatment: 80℃ vacuum drying or 80℃ hot air drying;

[0014] Melting temperature: 220-280°C, screw speed 50-70rpm;

[0015] Step 2: Injection molding in stages

[0016] The first stage is the injection molding of transparent materials;

[0017] Injection temperature: 245~295℃;

[0018] Injection pressure: 60-80MPa, injection speed 30%-50%, according to the percentage of the maximum speed of the injection molding machine;

[0019] Holding pressure: 40-50 MPa, holding time 3-5 seconds;

[0020] Cooling control: The mold temperature is maintained at 80-90°C by the mold temperature controller, and the cooling time is 5-8 seconds, so that the surface of the transparent material is solidified, the hardness reaches Shore D60-65, and the inside remains molten;

[0021] The second stage is the injection molding of opaque materials:

[0022] After the transparent material is injected, switch to the opaque material injection immediately after 1 to 3 seconds to avoid complete cooling of the interface.

[0023] Injection temperature: 225~275℃;

[0024] Injection pressure: 80-100 MPa, injection speed 60%-80%, as a percentage of the maximum speed of the injection molding machine;

[0025] Holding pressure: 50-60MPa, holding time 8-10 seconds;

[0026] Dynamic temperature control: During the injection molding process, the surface temperature of the transparent material is monitored in real time through infrared temperature measurement and controlled at 120-140°C to ensure fusion; the mold temperature rises to 100-110°C in the second stage to promote interface molecular diffusion;

[0027] Step 3: Interface fusion enhancement

[0028] Thermal synergistic effect: When the surface layer of the transparent material is semi-solidified, the high-temperature melt of the opaque material contacts the interface, causing the surface layer of the transparent material to soften again, forming a mutual melting layer of 0.1 to 0.3 mm;

[0029] Molecular diffusion control: by adjusting the viscosity ratio of the two-stage materials, transparent material viscosity / opaque material viscosity = 0.8-1.2, to ensure that the melt front is fully interwoven;

[0030] Compatibilizer injection: Add 1% to 3% of maleic anhydride grafted compatibilizer to the opaque material to promote chemical bonding with the material;

[0031] Step 4: Gradient cooling and stress release

[0032] Segmented cooling strategy:

[0033] The first stage: the transparent area is cooled first, and 15-20℃ cold water is introduced into the mold temperature controller at a cooling rate of 5℃ / s;

[0034] The second stage: the overall mold temperature is switched to 40-50°C, and the cooling rate is 2°C / s to reduce the warpage caused by shrinkage differences;

[0035] Post-processing: After demoulding, immediately place it in a 60-80℃ constant temperature box for slow cooling for 2-4 hours to release residual stress.

[0036] As a further improvement, the transparent material is PC or PMMA.

[0037] As a further improvement, the melting temperature described in Step 1 is 280-300°C for PC and 240-260°C for PMMA.

[0038] As a further improvement, the opaque material is a mixed material of PA and GF or ABS plastic.

[0039] As a further improvement, the pre-drying treatment method described in Step 1 is that the mixed material of PA and GF needs to be vacuum dried at 80°C for 6 to 8 hours, and the ABS plastic needs to be hot air dried at 80°C for 3 to 4 hours. The melting temperature described in Step 1 is 260 to 280°C for the mixed material of PA and GF, and 220 to 240°C for ABS plastic.

[0040] As a further improvement, the injection molding temperature described in Step 2 is 290±5℃ for PC and 250±5℃ for PMMA.

[0041] As a further improvement, the injection molding temperature described in Step 2 is 270±5℃ for the mixed material of PA and GF, and 230±5℃ for ABS plastic.

[0042] Beneficial effects:

[0043] Improve interface bonding strength: Through thermal synergy, molecular diffusion control and compatibilizer injection, a mutual melting layer is formed at the interface between transparent materials and opaque materials to improve interface bonding strength and avoid delamination or peeling problems.

[0044] Optimize process parameters and improve product quality: By precisely controlling the injection temperature, pressure and cooling process, the transparent material part and the opaque material part are fused within the appropriate temperature range, reducing stress concentration and deformation, and improving the dimensional stability and optical properties of the product.

[0045] Shorten the production cycle and improve production efficiency: Compared with traditional bonding or two-color injection molding, this method reduces the extra assembly steps and can complete the integrated molding of transparent and opaque materials in a single mold, thereby improving production efficiency.

[0046] Reduce material costs and improve economic benefits: Due to the improved interface fusion quality, this method can use a lower-cost combination of transparent and opaque materials without affecting product performance, thereby reducing production costs.

[0047] Enhanced weather resistance and durability: By optimizing the interface fusion technology, the product is less likely to crack, discolor or peel during long-term use, thereby increasing the service life of the lampshade and meeting the automotive industry's demand for high-reliability products. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flow chart of a method for integrally injecting transparent and opaque materials into a car lampshade; DETAILED DESCRIPTION

[0049] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0050] like Figure 1 As shown, a method for integrally injecting transparent and opaque materials of an automobile lamp cover comprises the following steps:

[0051] 1. Material pretreatment

[0052] Transparent material (PC / PMMA):

[0053] Pre-drying treatment: 100-120℃ hot air circulation drying for 4-6 hours, moisture content ≤0.02%.

[0054] Melting temperature: PC is 280-300°C, PMMA is 240-260°C, screw speed is 40-60rpm.

[0055] Opaque material (PA+GF / ABS):

[0056] Pre-drying treatment: PA+GF needs vacuum drying at 80℃ for 6 to 8 hours, ABS needs hot air drying at 80℃ for 3 to 4 hours.

[0057] Melting temperature: PA+GF is 260-280℃, ABS is 220-240℃, screw speed is 50-70rpm.

[0058] 2. Staged injection molding

[0059] Stage 1 (transparent material):

[0060] Injection temperature: PC 290±5℃, PMMA 250±5℃;

[0061] Injection pressure: 60-80MPa, injection speed 30%-50% (percentage of the maximum speed of the injection molding machine);

[0062] Holding pressure: 40-50 MPa, holding time 3-5 seconds;

[0063] Cooling control: The mold temperature is maintained at 80-90°C by a mold temperature controller, and the cooling time is 5-8 seconds, so that the surface of the transparent material is solidified (hardness reaches Shore D60-65) and the inside remains molten.

[0064] Stage 2 (Opaque Materials):

[0065] Seamless switching timing: After the transparent material injection is completed, delay 1 to 3 seconds and immediately switch to opaque material injection to avoid complete cooling of the interface.

[0066] Injection temperature: PA+GF 270±5℃, ABS 230±5℃;

[0067] Injection pressure: 80-100MPa, injection speed 60%-80%;

[0068] Holding pressure: 50-60MPa, holding time 8-10 seconds;

[0069] Dynamic temperature control:

[0070] During the injection molding process, the surface temperature of the transparent material is monitored in real time by infrared temperature measurement and controlled at 120-140°C (to ensure fusibility);

[0071] The mold temperature rises to 100-110°C in the second stage to promote interface molecular diffusion.

[0072] 3. Interface fusion enhancement technology

[0073] Thermal synergy effect:

[0074] When the surface layer of the transparent material is semi-solidified, the high-temperature melt (270-280°C) of the opaque material contacts the interface, causing the surface layer of the transparent material to soften again (locally heated to 180-200°C), forming a 0.1-0.3mm mutual melting layer.

[0075] Molecular Diffusion Control:

[0076] By adjusting the viscosity ratio of the two-stage materials (viscosity of transparent material / viscosity of opaque material

[0077] =0.8~1.2), ensuring that the melt fronts are fully interwoven.

[0078] Compatibilizer injection:

[0079] Add 1% to 3% of maleic anhydride grafted compatibilizer (such as PP-g-MAH) to the opaque material to promote chemical bonding with PC / PMMA.

[0080] Gradient cooling and stress relief

[0081] 4. Segmented cooling strategy:

[0082] The first stage: the transparent area is cooled first, and 15-20℃ cold water is introduced into the mold temperature controller at a cooling rate of 5℃ / s;

[0083] The second stage: the overall mold temperature is switched to 40-50°C, with a cooling rate of 2°C / s to reduce warpage caused by shrinkage differences.

[0084] Post-processing: After demoulding, immediately place it in a 60-80℃ constant temperature box for slow cooling for 2-4 hours to release residual stress.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for integrally injecting transparent and opaque materials into a car lampshade, characterized in that: The following steps are involved: Step 1: Material pretreatment Transparent Materials: Pre-drying treatment: 100-120℃ hot air circulation drying for 4-6 hours, so that the moisture content of the material is ≤0.02%; Melting temperature: 240-300°C, screw speed 40-60rpm; Opaque Materials: Pre-drying treatment: 80℃ vacuum drying or 80℃ hot air drying; Melting temperature: 220-280°C, screw speed 50-70rpm; Step 2: Injection molding in stages The first stage is the injection molding of transparent materials; Injection temperature: 245~295℃; Injection pressure: 60-80MPa, injection speed 30%-50%, according to the percentage of the maximum speed of the injection molding machine; Holding pressure: 40-50 MPa, holding time 3-5 seconds; Cooling control: The mold temperature is maintained at 80-90°C by the mold temperature controller, and the cooling time is 5-8 seconds, so that the surface of the transparent material is solidified, the hardness reaches Shore D60-65, and the inside remains molten; The second stage is the injection molding of opaque materials: After the transparent material is injected, switch to the opaque material injection immediately after 1 to 3 seconds to avoid complete cooling of the interface. Injection temperature: 225~275℃; Injection pressure: 80-100 MPa, injection speed 60%-80%, as a percentage of the maximum speed of the injection molding machine; Holding pressure: 50-60MPa, holding time 8-10 seconds; Dynamic temperature control: During the injection molding process, the surface temperature of the transparent material is monitored in real time through infrared temperature measurement and controlled at 120-140°C to ensure fusion; The mold temperature rises to 100-110°C in the second stage to promote interface molecular diffusion; Step 3: Interface fusion enhancement Thermal synergistic effect: When the surface layer of the transparent material is semi-solidified, the high-temperature melt of the opaque material contacts the interface, causing the surface layer of the transparent material to soften again, forming a mutual melting layer of 0.1 to 0.3 mm; Molecular diffusion control: by adjusting the viscosity ratio of the two-stage materials, transparent material viscosity / opaque material viscosity = 0.8-1.2, to ensure that the melt front is fully interwoven; Compatibilizer injection: Add 1% to 3% of maleic anhydride grafted compatibilizer to the opaque material to promote chemical bonding with the material; Step 4: Gradient cooling and stress release Segmented cooling strategy: The first stage: the transparent area is cooled first, and 15-20℃ cold water is introduced into the mold temperature controller at a cooling rate of 5℃ / s; The second stage: the overall mold temperature is switched to 40-50°C, and the cooling rate is 2°C / s to reduce the warpage caused by shrinkage differences; Post-processing: After demoulding, immediately place it in a 60-80℃ constant temperature box for slow cooling for 2-4 hours to release residual stress.

2. The method for integrally injecting transparent and opaque materials into a car lampshade according to claim 1, characterized in that: The transparent material is PC or PMMA.

3. The method for integrally injecting transparent and opaque materials into a car lampshade according to claim 2, characterized in that: The melting temperature described in Step 1 is 280-300°C for PC and 240-260°C for PMMA.

4. The method for integrally injecting transparent and opaque materials into a car lampshade according to claim 1, characterized in that: The opaque material is a mixed material of PA and GF or ABS plastic.

5. The method for integrally injecting transparent and opaque materials into a car lampshade according to claim 4, characterized in that: The pre-drying treatment method described in Step 1 is that the mixed material of PA and GF needs to be vacuum dried at 80°C for 6 to 8 hours, and the ABS plastic needs to be hot air dried at 80°C for 3 to 4 hours. The melting temperature described in Step 1 is 260 to 280°C for the mixed material of PA and GF, and 220 to 240°C for ABS plastic.

6. The method for integrally injecting transparent and opaque materials into a car lampshade according to claim 2, characterized in that: The injection molding temperature described in Step 2 is 290±5℃ for PC and 250±5℃ for PMMA.

7. The method for integrally injecting transparent and opaque materials into a car lampshade according to claim 4, characterized in that: The injection molding temperature described in Step 2 is 270±5℃ for the mixed material of PA and GF, and 230±5℃ for ABS plastic.

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