scholarly journals An Experimental Study on Color Shift of Injection-Molded Mobile LGP Depending on Surface Micropattern

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2610
Author(s):  
Mooyeon Kim ◽  
Junhan Lee ◽  
Kyunghwan Yoon
Keyword(s):  
Optical Properties ◽  
High Speed ◽  
Process Conditions ◽  
Molding Process ◽  
Injection Process ◽  
Color Shift ◽  
Surface Patterns ◽  
Injection Molded ◽  
Injection Compression Molding ◽  
Total Transmittance

In the display industry, the LCD backlight unit (BLU) module is variously used in mobile phones, notebook computers, monitors, and TVs. The light guide plate (LGP), which is one of the core parts of a BLU, is getting bigger and thinner consistently. Conventional injection methods and injection processes like injection compression molding (ICM) are becoming more complex and harsher with high-speed injection at high mold and melt temperatures. These approaches lead to a change in physical properties and a decrease in optical properties such as yellowing and color shift in injection-molded parts. In the present study, an injection molding experiment was conducted to understand the effect of surface patterns and major injection process conditions like mold and melt temperatures on the color shift in injection-molded mobile LGP. Optical properties obtained by the direct and total transmittance and CIE xy chromaticity diagram for injection-molded mobile LGP were measured with a UV–visible spectrophotometer. From the measurement of patternless LGP, it was found that total or direct transmittance was not affected by molding process variables. It was also found that yellow shift, ΔE(xy), occurred as much as 0.00111 ± 0.00014, and a color shift angle, Θ(xy), of 43.05 ± 2.44° was recorded in CIE coordinates for all nine experimental cases. From the measurement of total transmittance of patterned LGP, ΔE(xy) and Θ(xx) were found to be almost the same as those of patternless LGP for the locations of low and medium density of the pattern for the LGP, T1 and T2. The measured data of direct transmittance of patterned LGP showed that additional yellow shift due to scattering caused by surface micropattern. Interestingly, Θ(xy) of patterned data remained 43.05 ± 2.44°, which was almost the same as that found in the case of patternless LGP.

Injection Compression Molding Process and Mould Design of Plastic Optical Lens

2012 ◽  
Vol 501 ◽  
pp. 321-324 ◽  
Author(s):  
Qiu Xiang Bu ◽  
Jian Yi Zhu ◽  
Qing Zhen Yin
Keyword(s):  
Dimensional Accuracy ◽  
Compression Molding ◽  
Molding Process ◽  
Optical Lens ◽  
Stress Problem ◽  
Injection Process ◽  
Deformation Problem ◽  
Mould Design ◽  
Injection Compression Molding

The characteristic of injection compression molding technology and the application of the technology in mould for the plastic optical lens were introduced. The structure and the work principle of the mould for optical lens were designed and described, The stress problem in the injection process was resolved, the deformation problem and dimensional accuracy of product were improved.

Application of a multilayer injection molding process for thick-walled optical components

2016 ◽  
Vol 36 (6) ◽  
pp. 557-562 ◽  
Author(s):  
Christian Hopmann ◽  
Malte Röbig
Keyword(s):  
Optical Properties ◽  
Injection Molding ◽  
Mold Temperature ◽  
Injection Molding Process ◽  
Molding Process ◽  
Optical Components ◽  
Considerable Potential ◽  
Cycle Times ◽  
Molded Part ◽  
Injection Molded

Abstract Nowadays, the injection molding of optical components is becoming more and more important. A process which constructs the injection-molded part in layers offers considerable potential for productivity increases in the manufacturing of thick-walled optical components. The so-called multilayer injection molding, also known as overmolding technology enables a considerable reduction of the normally long cycle times and improves the optical properties. It is even possible to increase the molding accuracy due to the lower shrinkage potential of the single layers. Contrary to experience, the influence of the mold temperature on the bonding strength is very low. So, the temperature control of the mold can be adapted to the process consideration in regard to optical characteristics.

Influence of Process Parameters on Plastic Injection Molding of Automobile Interior Trim

2011 ◽  
Vol 189-193 ◽  
pp. 1675-1680
Author(s):  
Qing Qing Liu ◽  
Lin Hua ◽  
Wei Guo
Keyword(s):  
Mold Temperature ◽  
Process Conditions ◽  
Injection Time ◽  
Molding Process ◽  
Melt Temperature ◽  
Influence Of Process Parameters ◽  
Packing Pressure ◽  
Optimal Setting ◽  
Injection Molded ◽  
Packing Time

The influence of process conditions on the formability of injection-molded PX0034 (9% talc-filled PP) automobile B column mounting trim applied as a model has been studied in current work. This study has been focused on the interactive influence of melt temperature and mold temperature, the interactive influences of injection time and packing time and the influences of packing pressure. Weighting the effect of optimization is by formability including the values of pressure at V/P switchover, volumetric shrinkage differential at ejection, and maximum warpage. Aforementioned values were obtained by numerical simulation of the whole molding process using commercial dedicated code Moldflow. Results indicate that the combination of mold temperature at 25 °C, melt temperature at 220 °C, injection time at 2.2 s, packing time at 16 s and packing pressure at 90% of the filling pressure is the optimal setting for formability of this trim. The simulation results obtained under the optimized parameters are that the pressure at V/P switchover is 27.29 Mpa, the shrinkage differential at ejection is 6.55 %, and maximum warpage is 3.072 mm. Good correlation is highlighted between the experiments and the simulations by comparing effects of the global optimization in formability, which verifies the validity of the optimal combination.

A Study on the Birefringence Measurement in Injection Molded Parts Using Two Different Laser Sources and R-G-B Separation of White Light

2006 ◽  
Vol 326-328 ◽  
pp. 187-190
Author(s):  
Jong Sun Kim ◽  
Chul Jin Hwang ◽  
Kyung Hwan Yoon
Keyword(s):  
White Light ◽  
Low Cost ◽  
Main Idea ◽  
Injection Molding Process ◽  
Molding Process ◽  
Laser Method ◽  
High Productivity ◽  
Molded Parts ◽  
Injection Molded ◽  
Plastic Parts

Recently, injection molded plastic optical products are widely used in many fields, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique to measure the birefringence in transparent injection-molded optical plastic parts using two methods as follows: (i) the two colored laser method, (ii) the R-G-B separation method of white light. The main idea of both methods came from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. The comparison between two methods is demonstrated for the same sample of which retardation is up to 850 nm.

Micro-Injection Molding of Polymer Nanocomposites Composition-Process-Properties Relationship

2021 ◽  
Vol 36 (3) ◽  
pp. 276-286
Author(s):  
Z. Dekel ◽  
S. Kenig
Keyword(s):  
Mechanical Properties ◽  
Plug Flow ◽  
Volume Resistivity ◽  
Process Conditions ◽  
Polyamide 66 ◽  
Fountain Flow ◽  
Microinjection Molding ◽  
Injection Molded ◽  
Composition Process ◽  
Rheological Percolation

Abstract The mechanical, electrical, thermal, and rheological properties of micro injection molded nanocomposites comprising 2% and 5% carbon nanotubes (CNTs) incorporated in polycarbonate (PC), and polyamide 66 (PA) were studied. The design of experiments method was used to investigate the composition-process – properties relationship. Results indicated that the process variables significantly affected the flow patterns and resulting morphology during the filling stage of the microinjection molding (lIM) process, using 0.45 mm diameter lIM samples. Two distinct flow regimes have been identified in lIM using the low cross-section samples. The first was a conventional “fountain flow,” which resulted in a skin/core structure and reduced volume resistivity up to 10 X cm in the case of 5% CNTs and up to 100 X cm in 2% CNTs, in both polymers, respectively. In addition, inferior mechanical properties were obtained, attributed to polymer degradation under high shear rate conditions, when practicing high injection speeds, high mold temperatures, and high screw rotation velocities. The second was a “plug flow” due to wall slippage, obtained under low injection speeds, low mold temperatures, and low rotation velocities, leading to a substantial increase in modulus of elasticity (60%) with increased electrical resistivity up to 103 X cm for 5% CNTs and 105 X cm for 2% CNTs, respectively. The rheological percolation threshold was obtained at 2% CNTs while the electrical threshold was attained at 0.4% CNTs, in both polymers. It was concluded that in lIM, the process conditions should be closely monitored. In the case of high viscous heating, degradation of mechanical properties was obtained, while skin- core morphology formation enhanced electrical conductivity.

scholarly journals A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2092
Author(s):  
Xiansong He ◽  
Wangqing Wu
Keyword(s):  
Injection Molding ◽  
High Speed ◽  
Numerical Approach ◽  
Linear Shrinkage ◽  
Influential Factor ◽  
Dimensional Deviation ◽  
Non Linear ◽  
Injection Molded ◽  
Plastic Gears ◽  
Circle Diameter

This paper was aimed at finding out the solution to the problem of insufficient dimensional accuracy caused by non-linear shrinkage deformation during injection molding of small module plastic gears. A practical numerical approach was proposed to characterize the non-linear shrinkage and optimize the dimensional deviation of the small module plastic gears. Specifically, Moldflow analysis was applied to visually simulate the shrinkage process of small module plastic gears during injection molding. A 3D shrinkage gear model was obtained and exported to compare with the designed gear model. After analyzing the non-linear shrinkage characteristics, the dimensional deviation of the addendum circle diameter and root circle diameter was investigated by orthogonal experiments. In the end, a high-speed cooling concept for the mold plate and the gear cavity was proposed to optimize the dimensional deviation. It was confirmed that the cooling rate is the most influential factor on the non-linear shrinkage of the injection-molded small module plastic gears. The dimensional deviation of the addendum circle diameter and the root circle diameter can be reduced by 22.79% and 22.99% with the proposed high-speed cooling concept, respectively.

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