Skip to content
Licensed Unlicensed Requires Authentication Published by De Gruyter August 1, 2019

Influence of the Mold Temperature and Part Thickness on the Replication Quality and Molecular Orientation in Compression Injection Molding of Polystyrene

  • B. Roth , M.-Y. Zhou and D. Drummer

Abstract

It is well known that the process of injection molding with dynamic mold temperature control leads to a good replication quality of high aspect ratio microstructures. However, the inhomogeneous pressure distribution during the holding pressure phase results in an anisotropy of the component properties, low dimensional accuracy and, especially with optical polymers, in undesired stress birefringence. The anisotropy is based on the orientation of the molecular chains in the flow direction, which can be reduced by an injection-compression molding (ICM) process. In order to use the synergy from both processes, an injection-compression molding process with dynamic mold temperature control can be utilized. Within the scope of this investigation, the new process was reproduced by an ICM process at elevated mold temperature (ICM_EMT) and compared with injection molding (IM) with regard to molding accuracy and optical properties in dependence of component thickness and mold temperature. In order to evaluate the molding accuracy, the roughness of a wire-eroded microstructure on the cavity surface was measured. To determine the degree of orientation, the optical properties considered were the transmission and the path difference. It was shown that the adapted ICM process was able to achieve a high degree of replication accuracy with a low degree of orientation, especially for thin-walled components. ICM at elevated mold temperature reduced the path difference in the components with the lowest wall thickness by a factor of two while at the same time optimizing the replication of the microstructure. This could also be confirmed by transmission measurements.


*Correspondence address, Mail address: Benedikt Roth, Institute of Polymer Technology, Friedrich-Alexander-Universität Erlangen-Nuremberg, Erlangen, Germany, E-mail:

References

Ackermann, J., Juda, M. and Hirsch, D., “Polymethylmethacrylat (PMMA) – Vom Markt zum Produkt”, Kunststoffe.de, 10, 95100 (2013)Search in Google Scholar

Berger, G. R., Gruber, D. P., Friesenbichler, W., Teichert, C. and Burgsteiner, M., “Replication of Stochastic and Geometric Micro Structures – Aspects of Visual Appearance”, Int. Polym. Proc., 26, 313322 (2011) 10.3139/217.2451Search in Google Scholar

Burr, A., Hetschel, M. and Müller, A., “Die Motte als Vorbild”, Plastverarbeiter, 54, 6667 (2003)Search in Google Scholar

Burri, C., “Zur Theorie und Praxis der Drehkompensatoren nach Berek und Ehringhaus”, Z. Angew. Math. Phys., 4, 418424 (1953) 10.1007/BF02067899Search in Google Scholar

Chen, B. C., Cheng, Y. S., Gau, C. and Lee, Y. C., “Enhanced Performance of Polymer Solar Cells with Imprinted Nanostructures on the Active Layer”, Thin Solid Films, 564, 384389 (2014) 10.1016/j.tsf.2014.05.039Search in Google Scholar

Chen, S. C., Jong, W. R., Chang, Y. J., Chang, J. A. and Cin, J. C., “Rapid Mold Temperature Variation for Assisting the Micro Injection of High Aspect Ratio Micro-Feature Parts Using Induction Heating Technology”, J. Micromech. Microeng., 16, 17831791 (2006) 10.1088/0960-1317/16/9/005Search in Google Scholar

Christiansen, A. B., Clausen, J. S., Mortensen, N. A. and Kristensen, A., “Injection Moulding Antireflective Nanostructures”, Microelectron. Eng., 121, 4750 (2014) 10.1016/j.mee.2014.03.027Search in Google Scholar

Clausen, J. S., Christiansen, A. B., Kristensen, A. and Mortensen, N. A., “Enhancing the Chroma of Pigmented Polymers Using Antireflective Surface Structures”, Appl. Opt., 52, 78327837 (2013) PMid:24216745; 10.1364/AO.52.007832Search in Google Scholar

Föppl, L., Mönch, E.: Praktische Spannungsoptik, Springer, Heidelberg (2013)Search in Google Scholar

Gale, M. T., “Replication Techniques for Diffractive Optical Elements”, Microelectron. Eng., 34, 321339 (1997) 10.1016/S0167-9317(97)00189-5Search in Google Scholar

Hattori, S., Nagato, K., Hamaguchi, T. and Nakao, M., “Rapid Injection Molding of High-Aspect-Ratio Nanostructures”, Microelectron. Eng., 87, 15461549 (2010) 10.1016/j.mee.2009.11.028Search in Google Scholar

Heckele, M., Schomburg, W. K., “Review on Micro Molding of Thermoplastic Polymers”, J. Micromech. Microeng., 14, 114 (2004) 10.1088/0960-1317/14/3/R01Search in Google Scholar

Heim, H. P., PotenteH.: Specialized Molding Techniques, William Andrew Publishing, Norwich (2001)Search in Google Scholar

Holzer, C., Gobrecht, J., Schift, H. and Solak, H., “Replication of Micro- and Nanostructures on Polymer Surfaces”, Macromol. Symp., 296, 316323 (2010) 10.1002/masy.201051044Search in Google Scholar

Huang, M. S., Tai, N. S., “Experimental Rapid Surface Heating by Induction for Micro-Injection Molding of Light-Guided Plates”, J. Appl. Polym. Sci., 113, 13451354 (2009) 10.1002/app.30053Search in Google Scholar

Kalima, V., Pietarinen, J., Siitonen, S., Immonen, J., Suvanto, M., Kuittinen, M., Mönkkönen, K. and Pakkanena, T. T., “Transparent Thermoplastics”, Opt. Mater., 30, 285291 (2007) 10.1016/j.optmat.2006.11.046Search in Google Scholar

Khanarian, G., “Optical Properties of Cyclic Olefin Copolymers”, Opt. Eng., 40, 10241029 (2001) 10.1117/1.1369411Search in Google Scholar

Kim, S., Shiau, C. S., Kim, B. H. and Yao, D., “Injection Molding Nanoscale Features with the Aid of Induction Heating”, Polym. Plast. Technol. Eng., 46, 10311037 (2007) 10.1080/03602550701522344Search in Google Scholar

Klammt, S., Neyer, A. and Müller, H. F. O., “Redirection of Sunlight by Microstructured Components – Simulation, Fabrication and Experimental Results”, Solar Energy, 86, 16601666 (2012) 10.1016/j.solener.2012.02.034Search in Google Scholar

Lee, Y. B., Kwon, T. H. and Yoon, K., “Numerical Prediction of Residual Stresses and Birefringence in Injection/Compression Molded Center-Gated Disk. Part I”, Polym. Eng. Sci., 42, 22462272 (2004) 10.1002/pen.11114Search in Google Scholar

Lu, X., Kim, L. S., “A Statistical Experimental Study of the Injection Molding of Optical Lenses”, J. Mater. Process. Technol., 113, 189195 (2001) 10.1016/S0924-0136(01)00606-9Search in Google Scholar

Lucchetta, G., Fiorotto, M., “Influence of Rapid Mould Temperature Variation on the Appearance of Injection-Moulded Parts”, Strojniški Vestnik-Journal of Mechanical Engineering, 59, 683688 (2013) 10.5545/sv-jme.2013.1001Search in Google Scholar

Lucchetta, G., Sorgato, M., Carmignato, S. and Savio, E., “Investigating the Technological Limits of Micro-Injection Molding in Replicating High Aspect Ratio Micro-Structured Surfaces”, CIRP Ann., 63, 521524 (2014) 10.1016/j.cirp.2014.03.049Search in Google Scholar

Michaeli, W., Heßner, S., Klaiber, F. and Forster, J., “Geometrical Accuracy and Optical Performance of Injection Moulded and Injection-Compression Moulded Plastic Parts”, CIRP Ann., 56, 545548 (2007) 10.1016/j.cirp.2007.05.130Search in Google Scholar

New Media Publisher GmbH, Rohstoffpreise Plasticker (2018)Search in Google Scholar

Pranov, H., Rasmussen, H. K., Larsen, N. B. and Gadegaard, N., “On the Injection Molding of Nanostructured Polymer Surfaces”, Polym. Eng. Sci., 46, 160171 (2005) 10.1002/pen.20459Search in Google Scholar

Reed Business Information, icis: Outlook 18: Europe PMMA Concerns Mount on Shortage, Robust Demand (2018)Search in Google Scholar

Rytka, C., Kristiansen, P. M. and Neyer, A., “Iso- and Variothermal Injection Compression Moulding of Polymer Micro- and Nanostructures for Optical and Medical Applications”, J. Micromech. Microeng., 25, 116 (2015) 10.1088/0960-1317/25/6/065008Search in Google Scholar

Schift, H., David, C., Gobrecht, J., D’ Amore, A., Simoneta, D., Kaiser, W. and Gabriel, M., “Quantitative Analysis of the Molding of Nanostructures”, J. Vac. Sci. Technol. B, 18, 35643568 (2000) 10.1116/1.1324622Search in Google Scholar

Seokkwan, H., Inki, M., Kyunghwan, Y. and Jeongjin, K., “Effects of Adding Injection–Compression to Rapid Heat Cycle Molding on the Structure of a Light Guide Plate”, J. Micromech. Microeng., 24, 115 (2014) 10.1088/0960-1317/24/1/015009Search in Google Scholar

Siitonen, S., Laakkonen, P., Vahimaa, P., Jefimovs, K., Kuittinen, M., Parikka, M., Mönkkönen, K. and Orpana, A., “Coupling of Light from an LED into a Thin Light Guide by Diffractive Gratings”, Appl. Opt., 43, 56315636 (2004) PMid:15534994; 10.1364/AO.43.005631Search in Google Scholar

Stormonth-Darling, J. M., Pedersen, R. H., How, C. and Gadegaard, N., “Injection Moulding of Ultra High Aspect Ratio Nanostructures Using Coated Polymer Tooling”, J. Micromech. Microeng., 24, 112 (2014) 10.1088/0960-1317/24/7/075019Search in Google Scholar

Su, Y. C., Shah, J. and Lin, L., “Implementation and Analysis of Polymeric Microstructure Replication by Micro Injection Molding”, J. Micromech. Microeng., 14, 415 (2004) 10.1088/0960-1317/14/3/015Search in Google Scholar

Suzuki, H., Takayama, T. and Ito, H., “Replication Behaviour for Micro Surface Features with High Aspect Ratio and Structure Development in Injection Compression Molding”, International Journal of Modern Physics: Conference Series06, 563569 (2012) 10.1142/S2010194512003789Search in Google Scholar

Walther, T., Müller, R. U.: “For True Insight”, Kunststoffe International, 10, 7276 (2009)Search in Google Scholar

Wimberger-Friedl, R.: Molding of Optical Components, Encyclopedia of Optical Engineering, CRC Press, London, p. 13681379 (2003)Search in Google Scholar

Wimberger-Friedl, R., Bruin, J. G. de and Schoo, H. F. M., “Residual Birefringence in Modified Polycarbonates”, Polym. Eng. Sci., 43, 6270 (2004) 10.1002/pen.10005Search in Google Scholar

Wu, C. H., Chen, W. S., “Injection Molding and Injection Compression Molding of Three-Beam Grating of DVD Pickup Lens”, Sens. Actuators A, 125, 367375 (2006) 10.1016/j.sna.2005.07.025Search in Google Scholar

Xu, G., Yu, L., Lee, L. J. and Koelling, K. W., “Experimental and Numerical Studies of Injection Molding with Microfeatures”, Polym. Eng. Sci., 45, 866875 (2005) 10.1002/pen.20341Search in Google Scholar

Yang, C., Huang, H. X., Castro, J. M. and Yi, A. Y., “Replication Characterization in Injection Molding of Microfeatures with High Aspect Ratio”, Polym. Eng. Sci., 51, 959968 (2011) 10.1002/pen.21914Search in Google Scholar

Yao, D., “Injection Molding High Aspect Ratio Microfeatures”, Journal of Injection Molding Technology, 6, 1117 (2002)Search in Google Scholar

Yu, M. C., Young, W. B. and Hsu, P. M., “Micro-Injection Molding with the Infrared Assisted Mold Heating System”, Mater. Sci. Eng., A, 460–461, 288295 (2007) 10.1016/j.msea.2007.02.036Search in Google Scholar

Zeppenfeld, P., Hohage, M., “Oberflächenphysik: Nanostrukturierte Oberflächen: Anwendungen von Nanostrukturen setzen einfache, reproduzierbare Herstellungsverfahren voraus”, Phys. Bl., 56, 3338 (2013) 10.1002/phbl.20000561110Search in Google Scholar

Received: 2019-01-31
Accepted: 2019-03-29
Published Online: 2019-08-01
Published in Print: 2019-08-13

© 2019, Carl Hanser Verlag, Munich

Downloaded on 8.2.2023 from https://www.degruyter.com/document/doi/10.3139/217.3802/html
Scroll Up Arrow