Thermal transfer printing dye sheet
AssigneeImperial Chemical Industries PLC
InventorsAndrew Trevithick Slark, Richard Anthony Hann
Life of this patent
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Abstract
A dye sheet for thermal transfer printing comprising a substrate having on one surface thereof a dye coat which comprises a dye capable of thermal transfer dispersed in a polymer binder, characterized in that R-1 is a minimum where R=K.sub.sl /K.sub.tt, wherein K.sub.sl =AD.sub.sl /AP.sub.sl where AD.sub.sl is the absorption due to the dye and AP.sub.sl is the absorption due to the polymer over the surface layer; K.sub.tt =AD.sub.tt /AP.sub.tt where AD.sub.tt is the absorption due to the dye and AP.sub.tt is the absorption due to the polymer for the total thickness of the coating; and the values for AD.sub.sl, AP.sub.sl, AD.sub.tt and AP.sub.tt being measured by Attenuated Total Reflection Spectroscopy.
Claims11
A dye sheet for thermal transfer priming comprising a substrate having on one surface thereof a dye coat which comprises a dye capable of thermal transfer dispersed in a polymer binder, characterized in that R-1 is a minimum where
- R=K.sub.sl /K.sub.tt, wherein
- K.sub.sl =AD.sub.sl /AP.sub.sl where AD.sub.sl is the absorption due to the dye and AP.sub.sl is the absorption due to the polymer over the surface layer;
- K.sub.tt =AD.sub.tt /AP.sub.tt where AD.sub.tt is the absorption due to the dye and AP.sub.tt is the absorption due to the polymer for the total thickness of the coating;
- and the values for AD.sub.sl, AP.sub.sl, AD.sub.tt and AP.sub.tt being measured by Attenuated Total Reflection Spectroscopy.
A method of manufacturing a dye sheet for thermal transfer printing comprising coating a homogeneous solution of a dye and a polymer binder on to a substrate and drying the resulting coating at a temperature greater than 85.degree. C. and under conditions such that R-1 is a minimum where
- R=K.sub.sl /K.sub.tt, wherein
- K.sub.sl =AD.sub.sl /AP.sub.sl where AD.sub.sl is the absorption due to the dye and AP.sub.sl, is the absorption due to the polymer over the surface layer;
- K.sub.tt =AD.sub.tt /AP.sub.tt where AD.sub.tt is the absorption due to the dye and AP.sub.tt is the absorption due to the polymer for the total thickness of the coating;
- and the values for AD.sub.sl, AP.sub.sl, AD.sub.tt and AP.sub.tt being measured by Attenuated Total Reflection Spectroscopy.
A method of manufacturing a dye sheet for thermal transfer priming comprising coating a homogeneous solution of a dye and a polymer binder on to a substrate so as to form a series of parallel panels, drying at least one of said panels, measuring the value of R, where
- R=K.sub.sl /K.sub.tt, wherein
- K.sub.sl =AD.sub.sl /AP.sub.sl where AD.sub.sl is the absorption due to the dye and AP.sub.sl is the absorption due to the polymer over the surface layer;
- K.sub.tt =AD.sub.tt /AP.sub.tt where AD.sub.tt is the absorption due to the dye and AP.sub.tt is the absorption due to the polymer for the total thickness of the coating;
- and the values for AD.sub.sl, AP.sub.sl, AD.sub.tt and AP.sub.tt being measured using Attenuated Total Reflection Spectroscopy, generating a control signal dependent on said value of R and using the control signal to alter the drying conditions.
A dye sheet for thermal transfer printing comprising a substrate having on one surface thereof a dye coat which comprises a dye capable of thermal transfer dispersed in a polymer binder, characterized in that the dye coat is applied as a solution of dye and polymer in a solvent and in that the solvent is removed at a temperature greater than 85.degree. C. under conditions such that R-1 is a minimum where
- R=K.sub.sl /K.sub.tt ;
- K.sub.tt =AD.sub.tt /AP.sub.tt where AD.sub.tt is the absorption due to the dye and AP.sub.tt is the absorption due to the polymer for the total thickness of the coating;
- and the values for AD.sub.sl, AP.sub.sl, AD.sub.tt and AP.sub.tt being measured by Attenuated Total Reflection Spectroscopy.
A method of measuring in a dye sheet for thermal transfer printing comprising a substrate having on one surface thereof a dye coat which comprises a dye capable of thermal transfer dispersed in a polymer binder, the vertical distribution of the dye within the polymer, comprising the steps of:
- a) placing the dye sheet in contact with an Attenuated Total Reflection Spectroscopy prism;
- b) projecting into the prism at an angle of incidence of 60.degree. first and second beams of ir radiation having respectively wavelengths at which the dye and polymer have strong absorbance characteristics;
- c) measuring the degree of attenuation of said beams of radiation;
- d) repeating steps(a) to (c) at an angle of incidence of 35.degree., and
- e) calculating the value of R-1 where
- R=K.sub.sl /K.sub.tt, wherein
- K.sub.sl =AD.sub.sl /AP.sub.sl where AD.sub.sl is the absorption due to the dye and AP.sub.sl is the absorption due to the polymer over the surface layer, and
- K.sub.tt =AD.sub.tt /AP.sub.tt where AD.sub.tt is the absorption due to the dye and AP.sub.tt is the absorption due to the polymer for the total thickness of the coating.
Dependencies are inferred from the claim text.