Thermal dye transfer receiving element

A dye-receiving element for thermal dye transfer includes a support having on one side thereof a dye image-receiving layer. Receiving elements of the invention are characterized in that the dye image-receiving layer or an overcoat layer thereon comprises a linear condensation copolymer containing block polysiloxane units copolymerized into a linear polymer chain.

This invention relates to dye-receiving elements used in thermal dye 
transfer, and more particularly to polymeric dye image-receiving or 
overcoat layers for such elements. 
In recent years, thermal transfer systems have been developed to obtain 
prints from pictures which have been generated electronically from a color 
video camera. According to one way of obtaining such prints, an electronic 
picture is first subjected to color separation by color filters. The 
respective color-separated images are then converted into electrical 
signals. These signals are then operated on to produce cyan, magenta and 
yellow electrical signals. These signals are then transmitted to a thermal 
printer. To obtain the print, a cyan, magenta or yellow dye-donor element 
is placed face-to-face with a dye-receiving element. The two are then 
inserted between a thermal printing head and a platen roller. A line-type 
thermal printing head is used to apply heat from the back of the dye-donor 
sheet. The thermal printing head has many heating elements and is heated 
up sequentially in response to one of the cyan, magenta or yellow signals, 
and the process is then repeated for the other two colors. A color hard 
copy is thus obtained which corresponds to the original picture viewed on 
a screen. Further details of this process and an apparatus for carrying it 
out are contained in U.S. Pat. No. 4,621,271 by Brownstein entitled 
"Apparatus and Method For Controlling A Thermal Printer Apparatus," issued 
Nov. 4, 1986, the disclosure of which is hereby incorporated by reference. 
Dye donor elements used in thermal dye transfer generally include a support 
bearing a dye layer comprising heat transferable dye and a polymeric 
binder. Dye receiving elements generally include a support bearing on one 
side thereof a dye image-receiving layer. The dye image-receiving layer 
conventionally comprises a polymeric material chosen for its compatibility 
and receptivity for the dyes to be transferred from the dye donor element. 
When the dye donor and receiving elements are brought into contact and the 
donor element is imagewise heated in order to transfer a dye image to the 
receiving element, there is a problem in that the dye layer of the donor 
element and the dye-receiving layer of the receiver element tend to fuse 
or stick together due to the intense local heating required to transfer 
the dye. This problem is especially evident at higher density regions of 
the transferred image, as the higher density requires higher heating in 
order to transfer a greater amount of dye. Such sticking or fusing may 
result in donor dye layer transfer to the receiver or in the worst case 
tearing of the dye donor element, which results in unacceptable image 
prints. 
In an effort to overcome the problems associated with sticking between the 
donor and receiver elements, the prior art has made use of release agents. 
EP-A-0133012, for example, discloses a receiver element comprising a 
support having an image-receiving layer thereon, wherein a dye-permeable 
release agent such as silicone oil is present either in the 
image-receiving layer or in a separate release layer on at least part of 
the image receiving layer. Free silicones can be depleted from the 
receiver by diffusion into the dye donor during dye transfer, however, and 
when multiple printings are made on a single receiving element as is 
required in order to obtain a full color image, dye layer to receiving 
layer sticking may still occur. 
Linear polymers have been used as dye-receiving polymers, and such polymers 
having excellent image stability and dye uptake are disclosed in U.S. Pat. 
No. 4,927,803. Linear polymers such as these, however, may still suffer 
from dye donor to receiver sticking problems. 
Polymers having a Tg lower than that of the main receiver layer have been 
used for receiver overcoat layers which improve transferred dye image 
stability, and such overcoats are disclosed in U.S. Pat. No. 4,775,657. 
Even dual layer receivers such as these, however, may also still suffer 
from dye donor to receiver sticking problems. 
Attempts to increase the compatibility of silicone release agents to 
receiver polymers and decrease silicone depletion upon multiple printing 
have included grafting or cross-linking polysiloxane units to the backbone 
of a preformed receiver polymer. Japanese Kokai 61/199997-A (Dai Nippon) 
discloses receiving layers comprising a thermoplastic polyester resin, an 
isocyanate having at least two isocyanate groups, and modified silicone 
oil having a functional group which reacts with an isocyanate group. 
EP-A-368320 (Dai Nippon) discloses receiving layers comprising graft 
copolymers comprising releasing segments (e.g. polysiloxane segments) 
graft bonded to the main chain of a receiver polymer backbone. Japanese 
Kokai 63/134239-A (Mitsubishi Chem.) discloses a receiver comprising a 
thermoplastic resin and a silicone compound prepared by reacting an 
amino-modified silicone compound with carboxylic or sulfonic acid or their 
derivatives, wherein the silicone compound is blended into the receiver 
layer resin or coated on top thereof. 
While cross-linking silicone into a receiver polymer network reduces 
silicone depletion upon multiple printing, the formulations required are 
difficult to manufacture due to short coating solution lifetimes and the 
requirement of additional post coating curing steps to achieve sufficient 
cross-linking. Additionally, while the use of release media is desired to 
prevent donor to receiver sticking, substantially cross-linked media may 
act as an undesirable barrier to dye diffusion into the receiving layer. 
Grafted polymers also require that the main polymer backbone contain 
active grafting sites, and an additional grafting reaction after formation 
of the main polymer. 
Accordingly, it would be highly desirable to provide an easily 
manufacturable receiver element for thermal dye transfer processes having 
excellent dye uptake and image stability and which would not stick to dye 
donor elements. 
These and other objects are achieved in accordance with this invention 
which comprises a dye-receiving element for thermal dye transfer 
comprising a support having on one side thereof a dye image-receiving 
layer, wherein the dye image-receiving layer or an overcoat layer thereon 
comprises a linear condensation copolymer containing block polysiloxane 
units copolymerized into the main polymer chain. 
In accordance with this invention, it has been found that copolymerizing 
polysiloxane block units into linear receiver polymers results in linear 
receiver polymers which maintain excellent image stability and dye uptake 
properties while the polymers themselves become much more resistant to dye 
donor sticking. These properties make such linear copolymers ideally 
suited for use in a receiver overcoat, or alternatively for use as a sole 
dye image-receiving layer polymer or blended with other receiver polymers 
in a single image-receiving layer. The copolymers are readily 
manufacturable, and do not require any post coating curing steps to bond 
siloxanes to a main polymer chain. Further, the receiver polymer units 
need not have additional functional groups for grafting of the siloxanes 
after formation of the receiver main polymer chain. 
To obtain linear receiver copolymers of the invention, monomer units which 
form, for example, polycarbonates, polyurethanes, or polyesters upon 
condensation may be copolymerized with functional group terminated 
polysiloxanes of the general formula (I): 
##STR1## 
wherein: R.sup.1 and R.sup.2 are each independently substituted or 
unsubstituted alkyl of from about 1 to 6 carbon atoms (preferably a methyl 
group or a fluoro substituted alkyl group), or substituted or 
unsubstituted phenyl, with the proviso that R.sup.1 and R.sup.2 are not 
both phenyl; 
J is a bivalent linking group (preferably --(CH.sub.2).sub.p -- where p is 
1 to 10); 
D is amino, hydroxyl, or thiol; 
E represents optional second siloxane units which may be diphenyl 
substituted, or oxyalkylene containing units; 
b represents 50 to 100 mole percent; and 
n is chosen such as to provide a molecular weight of from about 1,000 to 
30,000 (preferably 1,000 to 15,000) for the polysiloxane block unit. 
Preferred linear copolymers of the invention are of the following general 
structure (II): 
##STR2## 
wherein: Q represents linkage units which together with units X, Y and Z 
form ester type linkage units (including, for example, carbonate and 
thiocarbonate) or amide type linkage units (including, for example, 
urethane, urea, and thiocarbamate); 
X is derived from one or more non-phenolic diol units, present at x=0 to 
99.9 mole %; 
Y is derived from an aromatic diphenolic unit, present at y=0 to 99.9 mole 
%; 
Z is derived from a functional group terminated polysiloxane as described 
above present at z=0.1 to 10.0 mole %, preferably 0.2 to 4.0 mole %; and 
EQU x+y+z=100. 
Ester units may be formed by condensing an aliphatic or aromatic dibasic 
acid (such as Q5 through Q8 illustrated below) with diol (such as X1 
through X10 illustrated below) or diphenolic (such as bisphenols Y1 
through Y7 illustrated below) units to form a polyester. Amide units may 
similarly be formed by condensing a diisocyanate (such as Q2 through Q4 
illustrated below) with diol or diphenolic units to form a polyurethane. 
Carbonate units may be formed by condensing a chloroformate or phosgene 
with diol or diphenolic units to form a polycarbonate. The term 
"polycarbonate" as used herein means a polyester of carbonic acid and a 
diol or diphenol. 
When Q is carbonate, X and Y are preferred at a molar ratio of from about 
3:1 to about 1:3. When Q is a urethane, X is preferred at 90 to 99.9 mole 
%. When Q is an ester derived from a dibasic aliphatic acid, Y is 
preferred at at least 75 mole %. When Q is an ester derived from an 
aromatic dibasic acid, X is preferred at at least 75 mole %. 
Carbonates are represented within Q as being derived from Q1, carbonic 
acid: 
##STR3## 
Amides are represented within Q as being derived from, for example, 
diisocyanates Q2, Q3, or Q4: 
##STR4## 
Esters are represented within Q as being derived from, for example, 
aliphatic or aromatic dibasic acids Q5 through Q8: 
##STR5## 
Specific examples of aliphatic or aromatic non-phenolic glycols that may be 
copolymerized include X1 through X10: 
##STR6## 
Specific examples of aromatic bisphenols that may be copolymerized include 
Y1 through Y7: 
##STR7## 
Specific examples of siloxanes that may be copolymerized include Z1 through 
Z8: 
##STR8## 
Wherein m and n are each 20 to 200, and b is 50 to 100 mole %. Specific 
values for m, n, and b are set forth in the polymer listings below. 
These siloxane block units should represent 0.1 to 10.0 mole %, preferably 
0.2 to 4.0 mole %, of the final polymer. The mole percentage of the 
siloxane block unit in the final polymer should be selected based upon the 
molecular weight of the siloxane block in order to generate a copolymer 
comprising from about 1 to about 40 wt % of siloxane block units, 
preferably from about 3 to about 30 wt %. Above about 40 wt % siloxane, 
problems occur with incorporation of the siloxane blocks into the linear 
polymer chain, while below 1 wt % siloxane, release between the dye donor 
and receiver is not as facilitated as desired. 
Preferred polymers of the invention are polycarbonates E-1 through E-9 
below, represented by the following structure (III): 
##STR9## 
__________________________________________________________________________ 
ALIPHATIC 
CARBONATE 
DIOL BISPHENOL 
SILICONE 
Polymer 
Mole % Q 
Mole % X 
Mole % Y 
Mole % Z 
n 
__________________________________________________________________________ 
E-1 100% Q1 49.5% X6 
49.5% Y1 
1.0% Z1 
21 
E-2 100% Q1 49.8% X6 
49.8% Y1 
0.4% Z1 
21 
E-3 100% Q1 49.9% X6 
49.9% Y1 
0.2% Z1 
50 
E-4 100% Q1 49.7% X6 
49.8% Y1 
0.5% Z1 
50 
E-5 100% Q1 49.7% X6 
49.8% Y1 
0.5% Z1 
187 
E-6 100% Q1 49.5% X6 
49.5% Y1 
1.0% Z1 
187 
E-7 100% Q1 49.0% X6 
49.0% Y1 
2.0% Z1 
187 
E-8 100% Q1 48.5% X6 
48.5% Y1 
3.0% Z1 
187 
E-9 100% Q1 48.0% X6 
48.0% Y1 
4.0% Z1 
187 
__________________________________________________________________________ 
__________________________________________________________________________ 
ALIPHATIC 
CARBONATE 
DIOL BISPHENOL 
SILICONE 
Polymer 
Mole % Q 
Mole % X 
Mole % Y 
Mole % Z 
n 
__________________________________________________________________________ 
E-10 100% Q1 25.0% X1 
65.0% Y1 
10.0% Z1 
187 
E-11 100% Q1 90.9% X1 
7.5% Y2 
2.5% Z1 
187 
E-12 100% Q1 50.0% X1 
47.5% Y3 
2.5% Z1 
50 
E-13 100% Q1 35.0% X1 
60.0% Y4 
5.0% Z1 
50 
E-14 100% Q1 75.0% X1 
24.2% Y5 
0.8% Z7* 
50 
E-15 100% Q1 50.0% X1 
48.5% Y6 
1.5% Z8** 
50 
E-16 100% Q1 20.0% X2 
79.2% Y1 
0.8% Z5 
50 
E-17 100% Q1 75.0% X3 
24.2% Y7 
0.8% Z8** 
50 
E-18 100% Q1 48.0% X3 
50.0% Y1 
2.0% Z1 
21 
E-19 100% Q1 48.0% X3 
50.0% Y1 
2.0% Z1 
50 
E-20 100% Q1 20.0% X4 
77.5% Y1 
2.5% Z1 
187 
E-21 100% Q1 80.0% X4 
19.7% Y2 
0.3% Z5 
21 
E-22 100% Q1 30.0% X4 
69.9% Y2 
0.1% Z6*** 
50 
E-23 100% Q1 70.0% X5 
29.2% Y1 
0.8% Z1 
187 
E-24 100% Q1 50.0% X5 
45.0% Y6 
5.0% Z2 
50 
E-25 100% Q1 70.0% X5 
29.7% Y7 
0.3% Z3 
50 
E-26 100% Q1 30.0% X7 
69.7% Y2 
0.3% Z1 
187 
E-27 100% Q1 97.5% X7 
-- 2.5% Z1 
50 
E-28 100% Q1 59.7% X5 
-- 0.3% Z1 
187 
40.0% X7 
E-29 100% Q1 59.7% X10 
40.0% Y3 
0.3% Z6*** 
187 
__________________________________________________________________________ 
*b = 99 mole % 
**b = 90 mole %, m = 50 
***b = 95 mole % 
__________________________________________________________________________ 
ALIPHATIC 
ISOCYANATE 
DIOL BISPHENOL 
SILICONE 
Polymer 
Mole % Q Mole % X 
Mole % Y 
Mole % Z 
n 
__________________________________________________________________________ 
E-30 100% Q2 50.0% X5 
49.2% Y1 
0.8% Z1 
50 
E-31 100% Q2 98.0% X5 
-- 2.0% Z1 
21 
E-32 100% Q2 98.0% X6 
-- 2.0% Z1 
21 
E-33 100% Q2 29.7% X2 
-- 0.3% Z1 
21 
70.0% X3 
E-34 100% Q2 40.0% X4 
-- 2.5% Z1 
50 
57.5% X8 
E-35 100% Q2 20.0% X5 
-- 5.0% Z1 
50 
75.0% X6 
E-36 100% Q3 99.7% X2 
-- 0.3% Z2 
187 
E-37 100% Q3 99.7% X9 
-- 0.3% Z8* 
50 
E-38 100% Q4 79.2% X2 
20.0% Y1 
0.8% Z1 
21 
E-39 100% Q4 92.0% X5 
-- 8.0% Z1 
50 
__________________________________________________________________________ 
*b = 80 mole %, m = 50 
__________________________________________________________________________ 
ALIPHATIC 
DIACID 
DIOL BISPHENOL 
SILICONE 
Polymer 
Mole % Q 
Mole % X 
Mole % Y Mole % Z 
n 
__________________________________________________________________________ 
E-40 100% Q5 
-- 99.7% Y1 0.3% Z1 
50 
E-41 100% Q5 
-- 98.0% Y1 2.0% Z1 
50 
E-42 100% Q5 
40.0% X1 
57.5% Y1 2.5% Z1 
21 
E-43 100% Q5 
25.0% X6 
72.5% Y1 2.5% Z1 
187 
E-44 100% Q5 
30.0% X7 
65.0% Y2 5.0% Z2 
21 
E-45 100% Q6 
10.0% X4 
89.2% Y6 0.8% Z5 
50 
E-46 100% Q7 
75.0% X6 
24.7% Y7 0.3% Z1 
50 
E-47 100% Q7 
99.2% X2 
-- 0.8% Z6* 
50 
E-48 100% Q8 
89.2% X4 
10.0% Y6 0.8% Z1 
50 
E-49 100% Q8 
97.5% X10 
-- 2.5% Z3 
21 
E-50 50% Q5 
50.0% X4 
47.5% Y6 2.5% Z1 
50 
50% Q7 
E-51 90% Q5 
10.0% X5 
89.7% Y7 0.3% Z5 
50 
10% Q8 
__________________________________________________________________________ 
*b = 99 mole % 
The support for the dye-receiving element of the invention may be a 
polymeric, a synthetic paper, or a cellulosic paper support, or laminates 
thereof. In a preferred embodiment, a paper support is used. In a further 
preferred embodiment, a polymeric layer is present between the paper 
support and the dye image-receiving layer. For example, there may be 
employed a polyolefin such as polyethylene or polypropylene. In a further 
preferred embodiment, white pigments such as titanium dioxide, zinc oxide, 
etc., may be added to the polymeric layer to provide reflectivity. In 
addition, a subbing layer may be used over this polymeric layer in order 
to improve adhesion to the dye image-receiving layer. Such subbing layers 
are disclosed in U.S. Pat. Nos. 4,748,150, 4,965,238, 4,965,239, and 
4,965,241, the disclosures of which are incorporated by reference. The 
receiver element may also include a backing layer such as those disclosed 
in U.S. Ser. No. 07/485,676 of Harrison and U.S. Ser. No. 07/547,580 of 
Martin, the disclosures of which are incorporated by reference. 
As set forth above, the invention polymers may be used in a receiving layer 
alone or in combination with other receiving layer polymers. In a 
preferred embodiment, the linear siloxane block copolymers of the 
invention are used in an overcoat layer over a main receiving layer. The 
use of overcoat layers is described in U.S. Pat. No. 4,775,657 of Harrison 
et al., the disclosure of which is incorporated by reference. Receiving 
layer polymers which may be overcoated with the polymers of the invention 
include polycarbonates, polyurethanes, polyesters, polyvinyl chlorides, 
poly(styrene-co-acrylonitrile), poly(caprolactone) or any other receiver 
polymer and mixtures thereof. 
In a preferred embodiment, the polymers of the invention are used as an 
overcoat on a dye image-receiving layer which comprises a polycarbonate. 
Preferred polycarbonates include bisphenol-A polycarbonates having a 
number average molecular weight of at least about 25,000. Examples of such 
polycarbonates include General Electric LEXAN.RTM. Polycarbonate Resin, 
Bayer AG MACROLON 5700.RTM., and the polycarbonates disclosed in U.S. Pat. 
No. 4,927,803 of Bailey et al., the disclosure of which is incorporated by 
reference. 
The dye image-receiving and overcoat layers may be present in any amount 
which is effective for their intended purposes. In general, good results 
have been obtained at a receiver layer concentration of from about 1 to 
about 10 g/m.sup.2 and an overcoat layer concentration of from about 0.01 
to about 3.0 g/m.sup.2, preferably from about 0.1 to about 1 g/m.sup.2. 
A dye-donor element that is used with the dye-receiving element of the 
invention comprises a support having thereon a dye containing layer. Any 
dye can be used in the dye-donor employed in the invention provided it is 
transferable to the dye-receiving layer by the action of heat. Especially 
good results have been obtained with sublimable dyes such as anthraquinone 
dyes, e.g., Sumikalon Violet RS.RTM. (product of Sumitomo Chemical Co., 
Ltd.), Dianix Fast Violet 3-R-FS.RTM. (product of Mitsubishi Chemical 
Industries, Ltd.), and Kayalon Polyol Brilliant Blue N-BGM.RTM. and KST 
Black 146.RTM. (products of Nippon Kayaku Co., Ltd.); azo dyes such as 
Kayalon Polyol Brilliant Blue BM.RTM., Kayalon Polyol Dark Blue 2BM.RTM., 
and KST Black KR.RTM. (products of Nippon Kayaku Co., Ltd.), Sumickaron 
Diazo Black 5G.RTM. (product of Sumitomo Chemical Co., Ltd.), and Miktazol 
Black 5GH.RTM. (product of Mitsui Toatsu Chemicals, Inc.); direct dyes 
such as Direct Dark Green B.RTM. (product of Mitsubishi Chemical 
Industries, Ltd.) and Direct Brown M.RTM. and Direct Fast Black D.RTM. 
(products of Nippon Kayaku Co. Ltd.); acid dyes such as Kayanol Milling 
Cyanine 5R.RTM. (product of Nippon Kayaku Co. Ltd.); basic dyes such as 
Sumicacryl Blue 6G.RTM. (product of Sumitomo Chemical Co., Ltd.), and 
Aizen Malachite Green.RTM. (product of Hodogaya Chemical Co., Ltd.); 
##STR10## 
or any of the dyes disclosed in U.S. Pat. No. 4,541,830, the disclosure of 
which is hereby incorporated by reference. The above dyes may be employed 
singly or in combination to obtain a monochrome. The dyes may be used at a 
coverage of from about 0.05 to about 1 g/m.sup.2 and are preferably 
hydrophobic. 
The dye in the dye-donor element is dispersed in a polymeric binder such as 
a cellulose derivative, e.g., cellulose acetate hydrogen phthalate, 
cellulose acetate, cellulose acetate propionate, cellulose acetate 
butyrate, cellulose triacetate; a polycarbonate; 
poly(styrene-co-acrylonitrile), a poly(sulfone) or a poly(phenylene 
oxide). The binder may be used at a coverage of from about 0.1 to about 5 
g/m.sup.2. 
The dye layer of the dye-donor element may be coated on the support or 
printed thereon by a printing technique such as a gravure process. 
Any material can be used as the support for the dye-donor element provided 
it is dimensionally stable and can withstand the heat of the thermal 
printing heads. Such materials include polyesters such as poly(ethylene 
terephthalate); polyamides; polycarbonates; glassine paper; condenser 
paper; cellulose esters such as cellulose acetate; fluorine polymers such 
as polyvinylidene fluoride or 
poly(tetrafluoroethylene-co-hexafluoropropylene); polyethers such as 
polyoxymethylene; polyacetals; polyolefins such as polystyrene, 
polyethylene, polypropylene or methylpentane polymers; and polyimides such 
as polyimide-amides and polyether-imides. The support generally has a 
thickness of from about 2 to about 30 um. It may also be coated with a 
subbing layer, if desired. 
A dye-barrier layer comprising a hydrophilic polymer may also be employed 
in the dye-donor element between its support and the dye layer which 
provides improved dye transfer densities. Such dye-barrier layer materials 
include those described and claimed in U.S. Pat. No. 4,700,208 of Vanier 
et al, issued Oct. 13, 1987. 
The reverse side of the dye-donor element may be coated with a slipping 
layer to prevent the printing head from sticking to the dye-donor element. 
Such a slipping layer would comprise a lubricating material such as a 
surface active agent, a liquid lubricant, a solid lubricant or mixtures 
thereof, with or without a polymeric binder. Examples of such lubricating 
materials include oils or semi-crystalline organic solids that melt below 
100.degree. C. such as poly(vinyl stearate), beeswax, perfluorinated alkyl 
ester polyethers, phosphoric acid esters, silicone oils, 
poly(caprolactone), carbowax or poly(ethylene glycols). Suitable polymeric 
binders for the slipping layer include poly (vinyl alcohol-co-butyral ) , 
poly (vinyl alcohol-co-acetal) , poly (styrene), poly 
(styrene-co-acrylonitrile), poly (vinyl acetate), cellulose acetate 
butyrate, cellulose acetate or ethyl cellulose. 
The amount of the lubricating material to be used in the slipping layer 
depends largely on the type of lubricating material, but is generally in 
the range of about 0.001 to about 2 g/m.sup.2. If a polymeric binder is 
employed, the lubricating material is present in the range of 0.1 to 50 wt 
%, preferably 0.5 to 40 wt %, of the polymeric binder employed. 
As noted above, dye-donor elements are used to form a dye transfer image. 
Such a process comprises imagewise-heating a dye-donor element and 
transferring a dye image to a dye-receiving element as described above to 
form the dye transfer image. 
The dye-donor element employed in certain embodiments of the invention may 
be used in sheet form or in a continuous roll or ribbon. If a continuous 
roll or ribbon is employed, it may have only one dye thereon or may have 
alternating areas of different dyes such as cyan, magenta, yellow, black, 
etc., as disclosed in U.S. Pat. 4,541,830. 
In a preferred embodiment of the invention, a dye-donor element is employed 
which comprises a poly(ethylene terephthalate) support coated with 
sequential repeating areas of cyan, magenta and yellow dye, and the above 
process steps are sequentially performed for each color to obtain a 
three-color dye transfer image. Of course, when the process is only 
performed for a single color, then a monochrome dye transfer image is 
obtained. 
Thermal printing heads which can be used to transfer dye from dye-donor 
elements to the receiving elements of the invention are available 
commercially. There can be employed, for example, a Fujitsu Thermal Head 
(FTP-040 MCS001), a TDK Thermal Head F415 HH7-1089 or a Rohm Thermal Head 
KE 2008-F3. Alternatively, other known sources of energy for thermal dye 
transfer may be used, such as lasers as described in, for example, GB No. 
2,083,726A. 
A thermal dye transfer assemblage of the invention comprises (a) a 
dye-donor element as described above, and (b) a dye-receiving element as 
described above, the dye-receiving element being in a superposed 
relationship with the dye-donor element so that the dye layer of the donor 
element is in contact with the dye image-receiving layer of the receiving 
element. 
When a three-color image is to be obtained, the above assemblage is formed 
on three occasions during the time when heat is applied by the thermal 
printing head. After the first dye is transferred, the elements are peeled 
apart. A second dye-donor element (or another area of the donor element 
with a different dye area) is then brought in register with the 
dye-receiving element and the process repeated. The third color is 
obtained in the same manner.

The following examples are provided to further illustrate the invention. 
The synthesis examples are representative, and other polymers of the 
invention may be prepared analogously or by other methods know in the art. 
Preparation 1 (Polymer E-D) 
A polycarbonate of diethylene glycol (49.7 mole %), bisphenol-A (49.8 mole 
%) and a bis (aminopropyl-terminated) polydimethyl siloxane (0.50 mole %). 
To a 3-neck round bottom flask equipped with a stirrer, dropping funnel and 
condenser were added bisphenol-A bischloroformate (35.3 g, 0.10 mol), 
diethylene glycol (10.6 g, 0.10 mol), 14,000 molecular weight 
aminopropyl-terminated polydimethylsiloxane (4.3 g, 0.0003 mol) and 
dichloromethane (150 ml). The solution was cooled to 0.degree.-5.degree. 
C. and with vigorous stirring pyridine (25 ml) was added. The ice bath was 
removed and the reaction was allowed to come to room temperature. Polymer 
molecular weight was maximized by addition with stirring of bisphenol-A 
bischloroformate (0.35 g, 0,001 mol) dissolved in 3 ml of dichloromethane 
(3 ml). After 4 hours the solution was washed with 2% hydrochloric acid 
(2.times.200 ml) and water (3.times.300 ml) followed by a methanol 
precipitation to yield a white polymer. This was then isolated and dried 
in a vacuum oven overnight at 50.degree. C. The polymer had a molecular 
weight of approx. 300,000 and a Tg of 70.degree. C. 
Preparation 2 (Polymer E-32) 
A polyurethane of isophorone diisocyanate, diethylene glycol(99 mole %), 
and a bis (aminopropyl-terminated) polydimethylsiloxane (1 mole %). 
To a 3 neck round bottom flask equipped with a stirrer, dropping funnel and 
condenser were added diethyleneglycol (10.5 g, 0,099 mol), 14,000 
molecular weight aminopropyl-terminated polydimethylsiloxane (1.7 g, 0,001 
mol), tetrahydrofuran (150 g) and dibutyltin dilaurate (5 drops). The 
flask was placed in a constant temperature bath at 40.degree. C. and while 
stirring isophorone diisoycanate (22.2 g, 0.10 mol) was added. The 
dropping funnel was then removed and the mixture was swept under nitrogen. 
The temperature was increased to 70.degree. C. and the reaction was 
stirred overnight. At that time when no free isocyanate was found to be 
present, the solution was cooled, poured into water and the polymer was 
isolated. The polymer was then placed in a vacuum oven at 70.degree. C. 
for 3 days to remove all the tetrahydrofuran. The polymer had a molecular 
weight of approx. 27,500 and a Tg of 81.degree. C. 
Preparation 3 (Polymer E-41) 
A polyester of azelaic acid, bisphenol-A (99 mole %) and a bis 
(aminopropyl-terminated) polydimethyl siloxane (1 mole %). 
To a 3 neck round bottom flask equipped with a stirrer, dropping funnel and 
condenser were added bisphenol-A, (22.6 g, 0.099 mol), 3,900 molecular 
weight aminopropyl terminated polydimethyl siloxane (3.9 g, 0.001 mol), 
dichloromethane (150 ml) and triethylamine (22.3 g, 0.22 mol). This 
solution was cooled to 0.degree.-5.degree. C. and with vigorous stirring 
azelaoyl chloride (22.51 g, 0.10 mol) was added. The solution was then 
allowed to come to room temperature. Polymer molecular weight was 
maximized by addition with stirring of portions of azelaoyl chloride (0.23 
g, 0.001 mol) dissolved in dichloromethane (3 ml). After 4 hours the 
mixture was washed with 2% hydrochloric acid (2.times.200 ml) and water 
(3.times.300 ml) followed by precipitation with methanol to yield a white 
polymer. The polymer was then isolated and dried at 20.degree. C. 
overnight. The polymer had a molecular weight of approx. 300,000 with a Tg 
of 35.degree. C. 
EXAMPLE 1 
Use of Polymers of the Invention in Receiver Overcoats 
Dye-receiving elements were prepared by coating the following layers in 
order on white-reflective supports of titanium dioxide pigmented 
polyethylene overcoated paper stock: 
(1) subbing layer of poly(acrylonitrile-co-vinylidene chloride-co-acrylic 
acid) (14:79:7 wt. ratio) (0.08 g/m.sup.2) coated from butanone. 
(2) dye-receiving layer of diphenyl phthalate (0.32 g/m.sup.2), di-n-butyl 
phthalate (0.32 g/m.sup.2), and Fluorad FC-431.RTM. (a surfactant of 3M 
Corp.) (0.01 g/m.sup.2), in a mixture of Makrolon 5700.RTM. (a bisphenol-A 
polycarbonate) (Bayer AG) (1.6 g/m.sup.2) and a linear condensation 
polymer derived from carbonic acid, bisphenol-A, and diethylene glycol 
(bisphenol:glycol mol ratio 50:50, molecular weight approx. 200,000) (1.6 
g/m.sup.2) coated from dichloromethane. 
(3) overcoat layer of the indicated linear condensation siloxane block 
copolymer of the invention (0.22 g/m.sup.2) coated from dichloromethane. 
Each overcoat layer also contained Fluorad FC-431.RTM. (a surfactant of 3M 
Corp.) (0.02 g/m.sup.2) and Dow Corning 510.RTM. Silicone Fluid (0.02 
g/m.sup.2). 
On the reverse side of each dye-receiving element a backing layer (not 
critical to the invention) was coated as described in Example 1 of U.S. 
Ser. No. 07/547580 of Martin. 
The following polymers were coated in place of the linear condensation 
siloxane block copolymers of the invention as control overcoat layers over 
the same subbing layer and main dye-receiving layer: 
C-1: No overcoat layer (control) 
C-2: Like polycarbonates E-1 to E-9 (1:1 mole ratio of bisphenol to glycol) 
but z=0 (no amino-terminated polydimethylsiloxane or z component) 
C-3: Like polycarbonates E-18 and E-19 but z=0 (no amino-terminated 
polydimethylsiloxane or Z component) 
C-4: Like polyurethane E-31 but z=0 (no amino-terminated 
polydimethylsiloxane or Z component) 
C-5: Like polyurethane E-32 but z=0 (no amino-terminated 
polydimethylsiloxane or Z component) 
C-6: Like polyester E-41 but z=0 (no amino-terminated polydimethylsiloxane 
or Z component) 
Neutral (black) dye-donor elements were prepared by coating the following 
layers in order on a 6 .mu.m poly(ethylene terephathalate) support: 
(1) subbing layer of Tyzor TBT.RTM. (a titanium isobutoxide) (duPont Co.) 
(0.12 g/m.sup.2) coated from a n-propyl acetate and 1-butanol solvent 
mixture. 
(2) dye layer of the following yellow dye (0.16 g/m.sup.2), major magenta 
dye (0.24 g/m.sup.2) minor magenta dye (0.04 g/m.sup.2), cyan dye (0.54 
g/m.sup.2), and S-363N1 (micronized blend of polyethylene, polypropylene 
and oxidized polyethylene particles) (Shamrock Technologies, Inc.) (0.023 
g/m.sup.2) in a cellulose acetate propionate binder (2.5% acetate, 46% 
propionyl) (0.54 g/m.sup.2) from a toluene, methanol, and cyclopentanone 
solvent mixture. 
On the reverse side of the support was coated a subbing layer as described 
above on top of which was coated a backing (slipping) layer of PS-513 (an 
aminopropyl-terminated polydimethylsiloxane) (Petrarch Systems, Inc.) 
(0.011 g/m.sup.2), Montan wax (F. B. Ross Co.) (0.032 g/m.sup.2), 
p-toluene sulfonic acid (0.003 g/m.sup.2), in a cellulose acetate 
propionate binder (2.5% acetyl, 46% propionyl) (0.53 g/m.sup.2) coated 
from a toluene, methanol, and cyclopentanone solvent mixture. 
##STR11## 
The dye side of the dye-donor element approximately 10 cm.times.15 cm in 
area was placed in contact with the polymeric receiving layer side of the 
dye-receiver element of the same area. The assemblage was fastened to the 
top of a motor-driven 60 mm diameter rubber roller and a TDK Thermal Head 
L-232 (300 DPI), thermostatted at 26.degree. C., was pressed with a spring 
at a force of 36 Newtons against the dye-donor element side of the 
assemblage pushing it against the rubber roller. 
The imaging electronics were activated and the assemblage was drawn between 
the printing head and roller at 31 mm/sec. Coincidentally, the resistive 
elements in the thermal print head were pulsed at 156 .mu.sec intervals 
(127 .mu.sec/pulse) during the 5 msec/dot printing time. The voltage 
supplied to the print head was approximately 20 v resulting in an 
instantaneous peak power of approximately 0.27 watts/dot and a maximum 
total energy of 8.1 mjoules/dot. A stepped density image was generated by 
incrementally increasing the pulses/dot through a defined range to a 
maximum of 32. 
After one stepped density image was generated, the printing cycle was 
repeated a second time with a new area of dye-donor onto the same area of 
dye-receiver. Dye-donor sticking was characterized as: 
None-No sticking observed, donor element separated cleanly from receiver. 
Slight-Partial sticking in one step (usually one of higher density). 
Moderate-Partial sticking in two steps. 
Severe-Partial sticking in three or more steps. 
______________________________________ 
Overcoat Sticking Observed 
______________________________________ 
C-1 (none) (control) Moderate 
C-2 (polycarbonate) Moderate 
E-1 (siloxane block polycarbonate) 
Slight 
E-2 (siloxane block polycarbonate) 
None 
E-3 (siloxane block polycarbonate) 
Slight 
E-4 (siloxane block polycarbonate) 
None 
E-5 (siloxane block polycarbonate) 
None 
C-3 (polycarbonate) Moderate 
E-18 (siloxane block polycarbonate) 
None 
E-19 (siloxane block polycarbonate) 
None 
C-4 (polyurethane) Severe 
E-31 (siloxane block polyurethane) 
Moderate 
C-5 (polyurethane) Severe 
E-32 (siloxane block polyurethane) 
None 
C-6 (polyester) Slight 
E-41 (siloxane block polyester) 
None 
______________________________________ 
The data above show that receiver overcoats of polymers of the invention 
containing a block polysiloxane unit linearly condensed into 
polycarbonates, polyurethanes and polyesters provide lessened donor to 
receiver sticking compared to otherwise equivalent overcoats of 
polycarbonates, polyurethanes, and polyesters without the siloxane block 
unit. The transferred dye-density for the invention and control receivers 
in each case was greater than 2.0. 
EXAMPLE 2 
Use of Polymers of the Invention in Receiver Overcoats 
This example is similar to Example 1, providing additional data for 
dye-donor to receiver sticking with receiver overcoats of polymers of the 
invention containing polysiloxane block units, and illustrates comparable 
results are not obtained merely with mixtures of polydimethylsiloxanes and 
a polycarbonate in a receiver overcoat. 
Dye-receiving elements were prepared by coating the following layers in 
order on a white-reflective support of titanium dioxide pigmented 
polyethylene overcoated paper stock: 
(1) subbing layer of poly(acrylonitrile-co-vinylidene chloride-co-acrylic 
acid) (14:79:7 wt. ratio) (0.08 g/m.sup.2) coated from butanone solvent. 
(2) dye-receiving layer of diphenyl phthalate (0.32 g/m.sup.2), and 
di-n-butyl phthalate (0.32 g/m.sup.2), in a linear condensation polymer 
derived from carbonic acid, bisphenol-A, and diethylene glycol 
(bisphenol:glycol mol ratio 50:50, molecular weight approx. 200,000) (5.4 
g/m.sup.2) coated from dichloromethane. 
(3) overcoat layer of the indicated poly(dimethyl siloxane) block copolymer 
of the invention (0.22 g/m.sup.2) plus indicated quantity of 
amino-terminated polydimethyl siloxane coated from dichloromethane. Each 
overcoat layer also contained Fluorad FC-431.RTM. (a surfactant of 3M 
Corp.) (0.02 g/m.sup.2) and Dow Corning 510.RTM. Silicone Fluid (0.02 
g/m.sup.2). 
No layer was coated on the reverse side. 
The following quantities of an amino-terminated polydimethylsiloxane 
(illustrated below) were coated mixed with the polycarbonate (illustrated 
below) over the dye-receiver layer as comparison overcoats. 
______________________________________ 
Coating Polysiloxane 
______________________________________ 
C-2 (control) 0 g/m.sup.2 
(polycarbonate only) 
C-7 (comparison) 
0.0011 g/m.sup.2 
(0.5 wt % of polymer) 
C-8 (comparison) 
0.0055 g/m.sup.2 
(2.5 wt % of polymer) 
C-9 (comparison) 
0.0011 g/m.sup.2 
(5.0 wt % of polymer) 
C-10 (comparison) 
0.055 g/m.sup.2 
(25.0 wt % of polymer) 
______________________________________ 
The polycarbonate and polydimethylsiloxane are of the following structures: 
##STR12## 
Neutral (black) dye-donor elements were prepared as described in Example 1. 
The same evaluation procedure was used as in Example 1 except the printing 
cycle was repeated three times onto the same area of dye-receiver rather 
than just twice. The same criteria for sticking were used as in Example 1. 
______________________________________ 
Overcoat Sticking Observed 
______________________________________ 
C-2 (polycarbonate) Moderate 
C-7 (polycarbonate + siloxane mix) 
Moderate 
C-8 (polycarbonate + siloxane mix) 
Moderate 
C-9 (polycarbonate + siloxane mix) 
Moderate 
C-10 (polycarbonate + siloxane mix) 
Slight 
E-2 (siloxane block polycarbonate) 
None 
E-5 (siloxane block polycarbonate) 
None 
E-6 (siloxane block polycarbonate) 
None 
E-7 (siloxane block polycarbonate) 
None 
E-9 (siloxane block polycarbonate) 
None 
______________________________________ 
The data above show that mixtures of polydimethylsiloxanes with linear 
polycarbonates do not provide as satisfactory performance with regard to 
dye-donor to receiver sticking as do the linear polymers of the invention 
containing a block polysiloxane unit. The transferred dye-density for the 
invention and control receivers in each case was greater than 2.0. 
Example 3 
Use of Polymers of the Invention in Receiving Layers 
This example is similar to Example 1 but provides data for dye-donor to 
receiver sticking when a polycarbonate containing a polysiloxane block 
unit is used as a receiving layer itself rather than as an overcoat on 
another polymeric receiving layer. 
Dye-receiving elements were prepared by coating the following layers in 
order on a white-reflective support of titanium dioxide pigmented 
polyethylene overcoated paper stock: 
(1) Subbing layer of poly(acrylonitrile-co-vinylidene chloride-co-acrylic 
acid) (14:79:7 wt. ratio) (0.08 g/m.sup.2) coated from butanone solvent. 
(2) Dye-receiving layer of the polycarbonate block copolymerized with a 
polydimethyl siloxane (E-5 described above) (5.4 g/m.sup.2) coated from 
dichloromethane. Each layer also contained Dow Corning 510.RTM. Silicone 
Fluid (0.03 g/m.sup.2) and Fluorad FC-431.RTM. (a surfactant of 3M Corp.) 
(0.016 g/m.sup.2). Before use each coating was dried at room temperature 
for six days. 
A control coating was prepared as described above, except the dye-receiving 
layer polymer was a linear condensation polymer derived from carbonic 
acid, bisphenol-A, and diethylene glycol (bisphenol:glycol mol ratio 
50:50, molecular weight approx. 200,000) (5.4 g/m.sup.2) coated from 
dichloromethane. 
Neutral (black) dye-donor elements were prepared as described in Example 1. 
The same evaluation procedure was used as in Example 1 except only one 
printing cycle was used. The same criteria for sticking were used as in 
Example 1. The following results were obtained: 
______________________________________ 
Receiver Sticking Observed 
______________________________________ 
E-5 Siloxane block containing 
None 
polycarbonate 
C-2 Polycarbonate Moderate 
______________________________________ 
The data above show that the polymers of the invention containing a block 
polysiloxane unit give no sticking when used alone as a dye-receiving 
layer compared to a polycarbonate receiving layer without the polysiloxane 
block unit. Dye transfer densities (considering the one-cycle printing) 
were equivalent to the polycarbonate control and to the overcoat 
containing receivers of Example 1. 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.