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Title: Digital decoration of polymers : innovations in the dye sublimation process
Author: Makenji, Kylash
ISNI:       0000 0004 2725 5679
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2011
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There are numerous techniques that can be used for the decoration of polymeric substrates, dye sublimation, self-colouring, paint spraying, granular injection paint technology, pad printing, in-mould decoration and hot foil stamping. Dye sublimation was selected for this research as it was found to be both the most relevant technology area for IDT Systems Limited and the least understood. It is a customisable digital process which uses specialist Cyan, Magenta, Yellow and Black (CMYK) inkjet-able dyes that are transferred into a substrate via a carrier. During the process heat is applied which transforms the dyes from a solid into a gas phase. Analysis of literature identified a number of knowledge gaps, which are addressed during this research and detailed in this report. Initial experimentation concluded that the sublimation dyes can penetrate a range of commercially available amorphous polymers, comparably to semi-crystalline types. These findings dispute previously published work, but these also lacked rigorously recorded methodologies to confirm comparable data. All of the materials, equipment and methodologies used throughout this research were therefore developed in this report. Further detailed experimentation was completed, using amorphous polycarbonate, (PC) and semi-crystalline polybutylene terephthalate, (PBT) focusing on the process time and temperature to understand their influence on the level of dye penetration. The results revealed that increasing the process temperature and time improves the level of dye penetration and that comparable penetration levels were noted at 140-180 oC. Further research identified the importance of free volume in the polymer, this increases in size and connectivity as temperature increases above the glass transition points. Additional experimentation confirms that the free volume enables the dyes to penetrate into the polymer. Characterisation of the CMYK sublimation dyes was completed using Differential Scanning Calorimetry enabling the thermal transitions to be identified. Visual experimentation confirmed that the dyes start and finish sublimation between 145-210 oC. As no software tool existed to visualise the dye penetration, one was developed using MatLab. The tool imports and then interpolates the data and graphically outputs it for the user. This allows a quicker set up time of the process and reduces the number of samples to be destroyed. As a direct result of the innovations described in this report, the industrial sponsor has benefited with an increase in commercial exploitation. Aspects of this research have been published, presented and a patent has been published, details are provided within.
Supervisor: Not available Sponsor: IDT Systems Ltd. ; Engineering and Physical Sciences Research Council (EPSRC)
Qualification Name: Thesis (D.Eng.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TP Chemical technology