With the development of IMD (IMS) application materials, the production and manufacture of IMD (IMS) for photocurable inks has become more convenient and faster, with a higher level of quality. Now we are decorating IMDs (IMS) with photocurable inks on formable surfaces. The technical application provides an introduction for everyone.
I. Composition of IMD material
Including sheet, resin, ink three parts.
2. design
(1) Design of graphic framework. (2) Structural design of injection molding molds. (3) The design of the position and shape of the injection mold injection port.
When designing the position of the injection port of the injection mold, it should be considered that during the injection molding, the PC injection molding plastic can not directly impact the imprint of the printing ink, thereby ensuring the complete clarity and crisp performance of the ink imprint after the injection molding. If, after injection molding, water marks, dispersion, diffusion, flying oil, etc., appear on the ink blots, the position and shape of the injection port and the overall structure of the injection mold should be considered. In addition, the temperature of the injection molding plastic needs to be adjusted so that it can withstand the printing ink, and at the same time, it can ensure that the PC material, the PC sheet, and the printing ink have the best adhesion state. This point, not only for UV inks, but also for solvent inks should be considered in order to achieve the best results.
3. production process
Including printing, molding, injection three parts.
Second, IMD printing and production process 1. Screen printing, film coating, molding and injection molding
Production process: Printed solvent-based or photo-curable IMD special ink on the back of PC sheet → Dry-solid → Ink-printed surface overall thermal composite film → High-pressure cold (hot) press molding → Die cutting waste edge → Preheating treatment of injection molding → Injection → Complete the part.
2. Screen printing grant molding injection molding
Supplement: AQUATEX SC water-based screen printing adhesive produced by Ke Tu Tai Company.
Role: It can increase the binding force between PC sheet, ink and injection molding plastic (resin).
Method: PC screen printing IMD special ink on the back screen → dry solid → PC printing ink surface overall screen printing water agent → high pressure cold (heat) pressure forming → die cutting waste edge → injection plastic preheat treatment → injection → complete parts .
3. Process flow
Screen printing IMD (IMS) ink → dry solid → composite PC film → molding → trimming → injection molding → complete.
Third, solvent-based ink and photo-curable ink in the IMD screen printing difference 1. Solvent type ink
After solvent-based ink printing of IMD PC sheets, it must be dried in a three-stage dryer with a ducted and well ventilated air. The last level of the third grade is dry, it is recommended to dry at a constant temperature of 90 °C for 3-5h. Therefore, the solvent-based ink has a long production cycle, and once the degree of dryness of the ink is poorly grasped or poor, it will have a great influence on the final injection yield. Because the solvent-based ink is not completely or completely dried after printing, residual solvent is left in the ink. Under the condition that the solvent is heated in the injection mold, the solvent cannot run off, and it will be emitted to the inside and outside of the ink, under the condition of high solvent vapor pressure. The ink will spread around and cause the "flying oil" phenomenon, which will blur the surrounding image. In severe cases, the printed graphic will spread and splash to form a "pattern" that scatters to the surrounding area. (For details, please refer to "Wire Mesh." Printing, No. 4, 2000, "Application of IMD Technology and IMD Technology-specific Inks".
2. Application of Light Curable Ink on IMD Technology
1) Automated printing can be performed with high production efficiency; 2) UV ink curing only takes a few seconds or more than ten seconds, the curing speed is very fast; 3) Finer lines can be screen printed, the resolution is high, and the ink layer is thin , Printing area is large; 4) Before injection molding, UV ink imprinting will not produce imprinted ink “flipping oil†phenomenon if it is not covered with film; 5) The entire operating system is easy to control, and UV ink is not required due to the small amount of solvent. Evaporate or dry the solvent process for a long time. Therefore, during the injection molding, the ink will not generate “fly oil†phenomenon when it is heated.
Fourth, the use of Novo IMD special light-curing ink 1. Selection of printing parameters
The number of screen meshes is 120-165 mesh/cm monofilament polyester screen, which can be determined according to the specifics of the text and the amount of ink.
The tension of the screen is greater than about 20N/cm.
The hardness of the squeegee is 70-80°.
Use a solvent-resistant capillary film 18 or photographic plate.
2. UV light curing requirements
1) The PC sheet is flexed and deformed by IR heat radiation in a UV curing machine with IR radiation. For this reason, there is a higher demand for UV curing equipment.
2) The wavelengths of the spectra that are compatible with the IMOD photocurable inks are generally between 300-400nm, and the peak value of the lightwave is 365nm, because the initiator in the photocurable ink is the most active at 365nm. Its UV lamp power is 120W/cm or two 80W/cm UV medium pressure mercury or metal halide lamps. If the PC chip is high temperature resistant or the PC chip passes faster in the high efficiency UV machine, the IR pair can be reduced. PC chip impact deformation.
Why does the PC slice be deformed by IR radiation in the UV machine?
The reason for this is that, in a commercially available UV machine lighting system, the current medium-pressure mercury lamp and reflector have two kinds of focusing type and non-focusing type. For the two types of reflection masks, while reflecting the required wavelength of ultraviolet light, , also reflects the IR heat radiation on the PC chip, especially when the speed of the UV machine is slow, and the white printing (total light reflection) and black (total light absorption) ink, the PC chip is more easily scratched Deformation.
The structural characteristics of these two types of reflectors are: the energy concentration of the UV light reflected by the focusing reflector is high, and the efficiency of the light curing is high, which is conducive to the solidification of the ink of the thick ink layer, and the deep layer of the ink can be solidified. Such a focusing reflector In particular, the reflective white ink and the black absorbing ink have better adaptability. Under the same power and under the same conditions, the focusing performance is stronger than that of the non-focusing type. However, the reflectors of both structures will generate high heat energy, which will easily deform the PC sheet by heat.
How to avoid and reduce deflection distortion caused by IR heat radiation during UV curing of PC sheet?
There are two ways.
In the first method, a layer of paint is coated on the surface of the UV reflector. The function of the paint layer is to absorb IR thermal radiation waves. During the entire UV curing process of the PC chip, IR is absorbed and only UV light is irradiated on the PC chip. Therefore, the PC chip is no longer subject to IR heat radiation, so it will not be heated and flexed. Reflectors of this structure are applicable not only to the IMD (IMS) PC sheet but also to other plastic sheets and labels printed with UV ink.
In the second method, in the UV machine, the two lamps are separated slightly and a device capable of reversing is set between the two lamps. After the PC sheet is printed with the ink, after passing the previous UV lamp, the workpiece comes to the middle. The PC chip is reversed 180° and then the other UV lamp. In this way, two low-energy, low-radiation UV lamps are used to cure the ink on both sides of the transparent PC sheet, allowing the PC sheet to be cured. Heat decreases, temperature decreases, reaches full cure, and does not deform.
Fifth, ink light curing and injection molding applications Note 1. UV lamp life
The new UV lamp (medium pressure mercury lamp) should be replaced after 1000 hours from the time of use. At the same time, the surface of the UV lamp and the reflector should be cleaned with absolute ethanol within 1000 hours. The UV lamp should be rotated after each cleaning. 90°, is conducive to UV rays all effectively radiate on the UV ink, to ensure a certain penetration of energy, so that UV energy penetrates the bottom of the ink, so that the ink is completely cured.
2. UV lamp radiation energy
UV lamps with insufficient energy (power), UV inks can not fully cure the deep ink layer more times than the UV ink, and on the contrary will also make the surface of the UV ink closed, aging, brittle and so on. At the same time, the poor adhesion of the ink will result in poor adhesion between the superimposed layers. Therefore, the power of UV lamps generally requires 120 W/cm or two 80 W/cm medium pressure mercury lamps or better metal halide lamps.
3. The effect of ink layer thickness and ink color on UV light curing
The UV curing inks of different colors and different thicknesses have slightly different curing effects. Under normal circumstances, when producing UV inks, suppliers use the characteristics of photoinitiators to reduce the color density by selecting the type of photoinitiator, so that different colors can be used. The UV inks achieve the same curing parameters under the same curing conditions. The thickness of the UV ink should be adjusted by changing the screen parameters, the hardness of the squeegee, and the squeegee speed, so as to ensure rapid curing of the ink.
4. Injection molding
(1) Simple Comparison of Several Forms
Thermoforming can be used for deep molding due to sheet heating.
Mechanical forming allows the ink to withstand higher pressures due to cold sheets.
High-pressure forming Because the sheet is slightly heated, it can tolerate higher pressure, and can be deep-formed, with accurate nesting and high dimensional stability.
(2) Key points worth noting
Pre-heat treatment of PC materials before injection molding.
The pretreatment is to preheat the PC granules, which is a drying process that removes moisture. Generally, it takes 3-4 hours to remove the moisture from the PC material, thereby ensuring that the ink splashes are reduced during injection molding. Injection of plastic and PC sheets to prevent air bubbles between the injection molding and the PC sheet and affect the transparency. As for the temperature of the preheating treatment, it should be different according to the injection molding.
Avoid cracking of inks or sheets.
To have a certain ink thickness, can not significantly reduce the color density or hiding.
When molding, select the largest molding radius.
A high temperature will reduce the area where the ink is washed away.
Increasing the temperature of injection molding resin can increase adhesion.
5. Injection plastic (resin) and injection temperature
Injection molding can be used for PC, ABS, PC+ABS, PS and PMMA. Refer to Table 1 for the reference injection temperature of various injection plastics.
The emergence of IMD (IMS) technology will greatly promote the development of screen printing technology for instrumentation, computers, keyboards, panels, and car dials. In the near future, the outer shells of a large variety of home appliances, automobiles and other products will also be completed using IMD (IMS) technology, which will completely automate production and improve efficiency. Therefore, IMD (IMS) technology is a comprehensive technology for the design, manufacture, and injection molding of special PC sheets, injection molding resins, temperature-resistant inks, color screen printing, and stamping injection molds. Therefore, the technical content of IMD (IMS) is relatively low. High, involving a wide range of technologies, it requires a reasonable structure design, coupled with advanced equipment and reasonable technology, IMD (IMS) will be widely used.
Table 1 reference injection temperature of various injection plastics
Injection Plastic PC ABS PC+ABS PS PMMA
Temperature >290°C >270°C >260°C >220°C >240°C
I. Composition of IMD material
Including sheet, resin, ink three parts.
2. design
(1) Design of graphic framework. (2) Structural design of injection molding molds. (3) The design of the position and shape of the injection mold injection port.
When designing the position of the injection port of the injection mold, it should be considered that during the injection molding, the PC injection molding plastic can not directly impact the imprint of the printing ink, thereby ensuring the complete clarity and crisp performance of the ink imprint after the injection molding. If, after injection molding, water marks, dispersion, diffusion, flying oil, etc., appear on the ink blots, the position and shape of the injection port and the overall structure of the injection mold should be considered. In addition, the temperature of the injection molding plastic needs to be adjusted so that it can withstand the printing ink, and at the same time, it can ensure that the PC material, the PC sheet, and the printing ink have the best adhesion state. This point, not only for UV inks, but also for solvent inks should be considered in order to achieve the best results.
3. production process
Including printing, molding, injection three parts.
Second, IMD printing and production process 1. Screen printing, film coating, molding and injection molding
Production process: Printed solvent-based or photo-curable IMD special ink on the back of PC sheet → Dry-solid → Ink-printed surface overall thermal composite film → High-pressure cold (hot) press molding → Die cutting waste edge → Preheating treatment of injection molding → Injection → Complete the part.
2. Screen printing grant molding injection molding
Supplement: AQUATEX SC water-based screen printing adhesive produced by Ke Tu Tai Company.
Role: It can increase the binding force between PC sheet, ink and injection molding plastic (resin).
Method: PC screen printing IMD special ink on the back screen → dry solid → PC printing ink surface overall screen printing water agent → high pressure cold (heat) pressure forming → die cutting waste edge → injection plastic preheat treatment → injection → complete parts .
3. Process flow
Screen printing IMD (IMS) ink → dry solid → composite PC film → molding → trimming → injection molding → complete.
Third, solvent-based ink and photo-curable ink in the IMD screen printing difference 1. Solvent type ink
After solvent-based ink printing of IMD PC sheets, it must be dried in a three-stage dryer with a ducted and well ventilated air. The last level of the third grade is dry, it is recommended to dry at a constant temperature of 90 °C for 3-5h. Therefore, the solvent-based ink has a long production cycle, and once the degree of dryness of the ink is poorly grasped or poor, it will have a great influence on the final injection yield. Because the solvent-based ink is not completely or completely dried after printing, residual solvent is left in the ink. Under the condition that the solvent is heated in the injection mold, the solvent cannot run off, and it will be emitted to the inside and outside of the ink, under the condition of high solvent vapor pressure. The ink will spread around and cause the "flying oil" phenomenon, which will blur the surrounding image. In severe cases, the printed graphic will spread and splash to form a "pattern" that scatters to the surrounding area. (For details, please refer to "Wire Mesh." Printing, No. 4, 2000, "Application of IMD Technology and IMD Technology-specific Inks".
2. Application of Light Curable Ink on IMD Technology
1) Automated printing can be performed with high production efficiency; 2) UV ink curing only takes a few seconds or more than ten seconds, the curing speed is very fast; 3) Finer lines can be screen printed, the resolution is high, and the ink layer is thin , Printing area is large; 4) Before injection molding, UV ink imprinting will not produce imprinted ink “flipping oil†phenomenon if it is not covered with film; 5) The entire operating system is easy to control, and UV ink is not required due to the small amount of solvent. Evaporate or dry the solvent process for a long time. Therefore, during the injection molding, the ink will not generate “fly oil†phenomenon when it is heated.
Fourth, the use of Novo IMD special light-curing ink 1. Selection of printing parameters
The number of screen meshes is 120-165 mesh/cm monofilament polyester screen, which can be determined according to the specifics of the text and the amount of ink.
The tension of the screen is greater than about 20N/cm.
The hardness of the squeegee is 70-80°.
Use a solvent-resistant capillary film 18 or photographic plate.
2. UV light curing requirements
1) The PC sheet is flexed and deformed by IR heat radiation in a UV curing machine with IR radiation. For this reason, there is a higher demand for UV curing equipment.
2) The wavelengths of the spectra that are compatible with the IMOD photocurable inks are generally between 300-400nm, and the peak value of the lightwave is 365nm, because the initiator in the photocurable ink is the most active at 365nm. Its UV lamp power is 120W/cm or two 80W/cm UV medium pressure mercury or metal halide lamps. If the PC chip is high temperature resistant or the PC chip passes faster in the high efficiency UV machine, the IR pair can be reduced. PC chip impact deformation.
Why does the PC slice be deformed by IR radiation in the UV machine?
The reason for this is that, in a commercially available UV machine lighting system, the current medium-pressure mercury lamp and reflector have two kinds of focusing type and non-focusing type. For the two types of reflection masks, while reflecting the required wavelength of ultraviolet light, , also reflects the IR heat radiation on the PC chip, especially when the speed of the UV machine is slow, and the white printing (total light reflection) and black (total light absorption) ink, the PC chip is more easily scratched Deformation.
The structural characteristics of these two types of reflectors are: the energy concentration of the UV light reflected by the focusing reflector is high, and the efficiency of the light curing is high, which is conducive to the solidification of the ink of the thick ink layer, and the deep layer of the ink can be solidified. Such a focusing reflector In particular, the reflective white ink and the black absorbing ink have better adaptability. Under the same power and under the same conditions, the focusing performance is stronger than that of the non-focusing type. However, the reflectors of both structures will generate high heat energy, which will easily deform the PC sheet by heat.
How to avoid and reduce deflection distortion caused by IR heat radiation during UV curing of PC sheet?
There are two ways.
In the first method, a layer of paint is coated on the surface of the UV reflector. The function of the paint layer is to absorb IR thermal radiation waves. During the entire UV curing process of the PC chip, IR is absorbed and only UV light is irradiated on the PC chip. Therefore, the PC chip is no longer subject to IR heat radiation, so it will not be heated and flexed. Reflectors of this structure are applicable not only to the IMD (IMS) PC sheet but also to other plastic sheets and labels printed with UV ink.
In the second method, in the UV machine, the two lamps are separated slightly and a device capable of reversing is set between the two lamps. After the PC sheet is printed with the ink, after passing the previous UV lamp, the workpiece comes to the middle. The PC chip is reversed 180° and then the other UV lamp. In this way, two low-energy, low-radiation UV lamps are used to cure the ink on both sides of the transparent PC sheet, allowing the PC sheet to be cured. Heat decreases, temperature decreases, reaches full cure, and does not deform.
Fifth, ink light curing and injection molding applications Note 1. UV lamp life
The new UV lamp (medium pressure mercury lamp) should be replaced after 1000 hours from the time of use. At the same time, the surface of the UV lamp and the reflector should be cleaned with absolute ethanol within 1000 hours. The UV lamp should be rotated after each cleaning. 90°, is conducive to UV rays all effectively radiate on the UV ink, to ensure a certain penetration of energy, so that UV energy penetrates the bottom of the ink, so that the ink is completely cured.
2. UV lamp radiation energy
UV lamps with insufficient energy (power), UV inks can not fully cure the deep ink layer more times than the UV ink, and on the contrary will also make the surface of the UV ink closed, aging, brittle and so on. At the same time, the poor adhesion of the ink will result in poor adhesion between the superimposed layers. Therefore, the power of UV lamps generally requires 120 W/cm or two 80 W/cm medium pressure mercury lamps or better metal halide lamps.
3. The effect of ink layer thickness and ink color on UV light curing
The UV curing inks of different colors and different thicknesses have slightly different curing effects. Under normal circumstances, when producing UV inks, suppliers use the characteristics of photoinitiators to reduce the color density by selecting the type of photoinitiator, so that different colors can be used. The UV inks achieve the same curing parameters under the same curing conditions. The thickness of the UV ink should be adjusted by changing the screen parameters, the hardness of the squeegee, and the squeegee speed, so as to ensure rapid curing of the ink.
4. Injection molding
(1) Simple Comparison of Several Forms
Thermoforming can be used for deep molding due to sheet heating.
Mechanical forming allows the ink to withstand higher pressures due to cold sheets.
High-pressure forming Because the sheet is slightly heated, it can tolerate higher pressure, and can be deep-formed, with accurate nesting and high dimensional stability.
(2) Key points worth noting
Pre-heat treatment of PC materials before injection molding.
The pretreatment is to preheat the PC granules, which is a drying process that removes moisture. Generally, it takes 3-4 hours to remove the moisture from the PC material, thereby ensuring that the ink splashes are reduced during injection molding. Injection of plastic and PC sheets to prevent air bubbles between the injection molding and the PC sheet and affect the transparency. As for the temperature of the preheating treatment, it should be different according to the injection molding.
Avoid cracking of inks or sheets.
To have a certain ink thickness, can not significantly reduce the color density or hiding.
When molding, select the largest molding radius.
A high temperature will reduce the area where the ink is washed away.
Increasing the temperature of injection molding resin can increase adhesion.
5. Injection plastic (resin) and injection temperature
Injection molding can be used for PC, ABS, PC+ABS, PS and PMMA. Refer to Table 1 for the reference injection temperature of various injection plastics.
The emergence of IMD (IMS) technology will greatly promote the development of screen printing technology for instrumentation, computers, keyboards, panels, and car dials. In the near future, the outer shells of a large variety of home appliances, automobiles and other products will also be completed using IMD (IMS) technology, which will completely automate production and improve efficiency. Therefore, IMD (IMS) technology is a comprehensive technology for the design, manufacture, and injection molding of special PC sheets, injection molding resins, temperature-resistant inks, color screen printing, and stamping injection molds. Therefore, the technical content of IMD (IMS) is relatively low. High, involving a wide range of technologies, it requires a reasonable structure design, coupled with advanced equipment and reasonable technology, IMD (IMS) will be widely used.
Table 1 reference injection temperature of various injection plastics
Injection Plastic PC ABS PC+ABS PS PMMA
Temperature >290°C >270°C >260°C >220°C >240°C
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