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Warpage and countermeasure for injection‐molded in‐mold labeling parts
Author(s) -
Larpsuriyakul Patcharee,
Fritz HansGerhard
Publication year - 2011
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.21849
Subject(s) - mold , materials science , composite material , molding (decorative) , shrinkage , thermal , fabrication , medicine , physics , alternative medicine , pathology , meteorology
Decades ago, the production of packaging with the injection in‐mold labeling (IML) has been established. With this manufacturing technique, label and packaging, both are of the same polymeric material, become inseparably connected during the injection molding process. Because thermal conductivity of the polymeric label material is clearly smaller than that of the metal mold wall, thermal‐induced warpage of injected IML parts or part surface deformation could occur. In this study, structure and warpage behavior of IML parts, which are different from those of conventional molded parts without labels were intensively investigated. It was found that it is the volume contraction difference between label and substrate that forces IML parts to warp to the opposite side of the label. In addition, IML part warpage problem can be coped by varying the mold temperature on the stationary and moving mold platen. By increasing the mold temperature on the label side, the degree of IML part warpage can be reduced with acceptable reduction in mechanical properties. The optimum mold temperature range for particular substrate material, however, was found to be more decisive in maintaining the modulus of elasticity of IML parts than the magnitude of mold temperature difference. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers