Method of transferring a toner image to a substrate

The process involves photocopying a black-and-white or color image on a sheet of ordinary paper (2), appearing as the reverse of the image ultimately to be produced, then placing the copy side of the sheet in direct contact with the suface of the fabric (1) and applying pressure and heat in such a way as causes the toner, from which the copy image is constructed, to transfer to the fabric. Solvent is applied to the exposed surface of the sheet to facilitate separation of toner from the sheet.

BACKGROUND OF THE INVENTION 
The present invention relates to a printing process suitable in particular 
for fabrics, leathers and similar materials. 
The prior art in this field, and especially the field of quality print 
finishing, embraces methods which by their very nature and constitution 
are unsuited to cost-efffective exploitation for limited and dissimilar 
production runs. As a general rule, in fact, the not inconsiderable cost 
of special print equipment needed for the particular operation 
(silkscreens etc.) must be spread directly over the unit cost. 
To this cost must be added that of setting up the equipment, which is 
reflected in the time required, and the necessity of using specialized 
personnel. The object of the present invention is to provide a printing 
process, in particular for fabrics, that can be implemented easily using 
simple means and requires no preparation of special equipment as in the 
case, for example, of silkscreen processes. 
SUMMARY OF THE INVENTION 
The stated object is comprehensively realized in the process disclosed, 
which is ideally suited to short production runs and offers great 
flexibility of use. Briefly, the process consists in making an initial 
photocopy of the image in reverse, then offering the photocopy to the 
material, fabric, leather or whatever, sandwiching these two layers 
between further layers of a flexible heat-resistant cushioning material, 
and applying heat and pressure for a duration sufficient to melt the copy 
toner and thus cause the image to transfer to the surface of the fabric. 
This accomplished, solvents can be applied to assist full separation of 
the toner from the copy paper, and the transferred image will then appear; 
the image can also be fixed chemically, if necessary.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
According to the invention, a black-and-white or color image is reproduced 
on one surface 11 of a fabric 1, or rather, printed, by transferring a 
previously prepared reverse image, made from copy toner or any other 
suitable toner solution, to a surface 22 of a sheet of paper 2. 
The monochrome or color reverse image that is made from the copy toner is 
produced on the surface 22 of the sheet 2 by conventional photocopying, 
using ordinary paper. This operation need present no problems whatever, 
even in the case of a color reproduction, as the state of the art now 
embraces machines that will photocopy in color from prints or even from 
transparencies. 
The paper sheet 2 is positioned with the surface 22 bearing the reverse 
image offered in uniform and flush contact to the surface 11 of the fabric 
1, and with its opposite surface 21 covered by a thin backing layer of 
flexible material 3, a silicone elastomer for example, of uniform 
thickness. 
A further uniform layer of flexible material 33 is laid beneath and in 
flush contact with the back surface 12 of the fabric 1. 
The multilayer sandwich formed in this manner is compressed hot between two 
parallel plates 4 and 44 operated by a conventional press (not 
illustrated), as indicated by the arrows 5 and 6; at least the top plate 4 
will be heated and maintained for the duration of the pressing operation 
at a prescribed temperature, generally no higher than 200.degree. C., but 
at all events such as to ensure partial fusion of the toner from which the 
reverse image presented by the surface 22 of the sheet 2 is constructed. 
The pressing force will depend on the type of fabric 1 and is tied to the 
temperature and duration of the press stroke, which are both variable 
parameters. The two flexible backing layers 3 and 33 will be fashioned 
from an elastically deformable material able to withstand the thermal 
stresses generated in pressing without undergoing change. 
On completion of the pressing operation, the fused transfer sheet 2 and 
fabric 1 are separated from the backing layers 3 and 33, whereupon a 
solvent, for example a nitro based thinner such as those suitable for 
paints and varnishes, is applied to the exposed surface 21 of the transfer 
sheet 2 using light pressure in order to facilitate the separation of the 
toner, hence transfer of the image from the relative surface 22 of the 
sheet; thereafter, when the sheet 2 is lifted, the toner will be seen to 
have attached itself permanently to the surface 11 of the fabric 1, which 
thus bears the printed image. 
With the transfer process complete, the printed image can be chemically 
fixed. The image produced in this manner is of optimum quality; moreover, 
the process according to the invention is characterized by great 
flexibility, inasmuch as it permits of reproducing any given image without 
the need to set up costly equipment such as dies, silkscreens etc., 
neither of which can generate more than one image at one time; what is 
more, color silkscreen processes require one screen for each of the single 
colors.