Makenji, Kylash (2011) Digital decoration of polymers : innovations in the dye sublimation process. EngD thesis, University of Warwick.

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Abstract

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.

Item Type:	Thesis or Dissertation (EngD)
Subjects:	T Technology > TP Chemical technology
Library of Congress Subject Headings (LCSH):	Digital printing, Dyes and dyeing, Manufacturing processes
Official Date:	December 2011
Dates:	Date Event December 2011 Submitted
Institution:	University of Warwick
Theses Department:	Warwick Manufacturing Group
Thesis Type:	EngD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Smith, Gordon ; Goodship, Vannessa
Sponsors:	IDT Systems Ltd. ; Engineering and Physical Sciences Research Council (EPSRC)
Extent:	ix, 86 leaves : illustrations, charts
Language:	eng

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