[0001] This invention relates to a dye-donor element used in thermal dye transfer, and more
particularly to the use of a magnetic recording layer underneath a slipping layer
on the back side thereof.
[0002] 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 the cyan, magenta and yellow signals.
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. Patent No. 4,621,271
by Brownstein entitled "Apparatus and Method for Controlling A Thermal Printer Apparatus,"
issued November 4, 1986.
[0003] A slipping layer is usually provided on the backside of the dye-donor element to
prevent sticking to the thermal head during printing. A subbing layer is also usually
needed to promote adhesion between the support and the slipping layer.
[0004] In many instances during thermal dye transfer printing, it would be advantageous
to have certain information recorded directly on the thermal dye-transfer element.
Examples for potentially useful information would be specific product identification,
sensitometric information, recording of the number of print areas remaining on the
spool, dye patch position relative to the printer heat line, and so forth.
[0005] U.S. Patent 5,342,671 discloses the use of a transparent magnetic layer on a dye-receiver
element. However, there is no disclosure in this patent of the use of magnetic layers
in a dye-donor element.
[0006] In JP 02/054798, a donor element is described for thermal wax transfer which has
a magnetic ink layer or patch contiguous to a nonmagnetic thermal transfer layer or
patch near the end position for the purpose of detecting the end position. In this
element, the magnetic ink layer is coated on the ink side of the donor element and
has the same color as the nonmagnetic ink layer next to it. A portion of the magnetic
ink may also transfer to the receiving element during the printing process.
[0007] There is a problem with the format in this Japanese reference in that the magnetic
layer or patch is limited to being located adjacent to an ink layer or patch. For
certain types of information, it would be desirable to record information on other
areas of a donor material, for example, in the same area as a dye patch. Also, in
a thermal dye diffusion transfer process where only the dye is transferred, it would
be desirable to not have any magnetic material be transferred to the receiving layer
which would affect the density and color balance obtained.
[0008] It is an object of this invention to provide a dye-donor element for thermal dye
transfer processing which contains a magnetic layer which can be in the same area
as the dye layer. It is another object of the invention to provide a dye-donor element
for thermal dye transfer processing which contains magnetic material but which is
not transferred to the dye-receiving layer which would affect the density and color
balance obtained.
[0009] These and other objects are achieved in accordance with the invention which relates
to a dye-donor element for thermal dye transfer comprising a support having on one
side thereof a dye layer and on the other side thereof in the direct opposite area
to at least a portion of the dye layer, a magnetic recording layer and a slipping
layer, in that order.
[0010] The magnetic recording layer used in this invention can comprise a ferromagnetic
oxide such as gamma Fe
2O
3, gamma Fe
2O
3 having a cobalt surface treatment, magnetite, magnetite having a cobalt surface treatment,
barium ferrite, chromium dioxide, or a ferromagnetic metal particle such as metallic
iron or metallic iron alloys with cobalt, nickel, chromium, etc. All of the above
particles may also have a surface treatment with silica, alumina or an aluminosilicate
to improve dispersability, corrosion and abrasion resistance. In a preferred embodiment
of the invention, gamma Fe
2O
3 having a cobalt surface treatment is used.
[0011] The above particles may have a coercivity of from about 300 Oersted to about 1500
Oersted, preferably from about 600 Oersted to about 900 Oersted.
[0012] The magnetic recording layer of the invention may be present in any concentration
which is effective for the intended purpose. In general, good results have been attained
using a laydown of from 0.01 g/m
2 to 4 g/m
2, preferably 0.04 g/m
2 to 0.1 g/m
2.
[0013] Any dye can be used in the dye layer of the dye-donor element of 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

or any of the dyes disclosed in U.S. Patent 4,541,830. 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
2 and are preferably hydrophobic.
[0014] A dye-barrier layer may be employed in the dye-donor elements of the invention to
improve the density of the transferred dye. Such dye-barrier layer materials include
hydrophilic materials such as those described and claimed in U.S. Patent No. 4,716,144.
[0015] 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.
[0016] Any slipping layer may be used in the dye-donor element of the invention to prevent
the printing head from sticking to the dye-donor element. Such a slipping layer would
comprise either a solid or liquid lubricating material or mixtures thereof, with or
without a polymeric binder or a surface-active agent. Preferred lubricating materials
include oils or semi-crystalline organic solids that melt below 100°C such as poly(vinyl
stearate), beeswax, perfluorinated alkyl ester polyethers, poly(caprolactone), silicone
oil, poly(tetrafluoroethylene), carbowax, poly(ethylene glycols), or any of those
materials disclosed in U. S. Patents 4,717,711; 4,717,712; 4,737,485; and 4,738,950.
Suitable polymeric binders for the slipping layer include poly(vinyl alcohol-co-butyral),
poly(vinyl alcohol-co-acetal), poly(styrene), poly(vinyl acetate), cellulose acetate
butyrate, cellulose acetate propionate, cellulose acetate or ethyl cellulose.
[0017] 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
2. If a polymeric binder is employed, the lubricating material is present in the range
of 0.05 to 50 weight %, preferably 0.5 to 40 weight %, of the polymeric binder employed.
[0018] Any material can be used as the support for the dye-donor element of the invention
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 methylpentene polymers; and polyimides such as polyimide
amides and polyetherimides. The support generally has a thickness of from about 2
to about 30 µm.
[0019] The dye-receiving element that is used with the dye-donor element of the invention
usually comprises a support having thereon a dye image receiving layer. The support
may be a transparent film such as a poly(ether sulfone), a polyimide, a cellulose
ester such as cellulose acetate, a poly(vinyl alcohol-co-acetal) or a poly(ethylene
terephthalate). The support for the dye-receiving element may also be reflective such
as baryta-coated paper, polyethylene-coated paper, white polyester (polyester with
white pigment incorporated therein), an ivory paper, a condenser paper or a synthetic
paper such as DuPont Tyvek®.
[0020] The dye image-receiving layer may comprise, for example, a polycarbonate, a polyurethane,
a polyester, poly(vinyl chloride), poly(styrene-co-acrylonitrile), polycaprolactone
or mixtures thereof. The dye image-receiving layer may be present in any amount which
is effective for the intended purpose. In general, good results have been obtained
at a concentration of from about 1 to about 5 g/m
2.
[0021] As noted above, the dye-donor elements of the invention are used to form a dye transfer
image. Such a process comprises imagewise heating a dye-donor element as described
above and transferring a dye image to a dye receiving element to form the dye transfer
image.
[0022] The dye-donor element 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
or may have alternating areas of other different dyes, such as sublimable cyan and/or
magenta and/or yellow and/or black or other dyes. Such dyes are disclosed in U.S.
Patent Nos. 4,541,830; 4,698,651; 4,695,287; 4,701,439; 4,757,046; 4,743,582; 4,769,360
and 4,753,922. Thus, one-, two-, three- or four-color elements (or higher numbers
also) are included within the scope of the invention.
[0023] In a preferred embodiment of the invention, the dye-donor element comprises a poly(ethylene
terephthalate) support coated with sequential repeating areas of yellow, cyan and
magenta 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.
[0024] Thermal printing heads which can be used to transfer dye from the dye-donor elements
of the invention are available commercially.
[0025] 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.
[0026] The above assemblage comprising these two elements may be preassembled as an integral
unit when a monochrome image is to be obtained. This may be done by temporarily adhering
the two elements together at their margins. After transfer, the dye-receiving element
is then peeled apart to reveal the dye transfer image.
[0027] 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 is repeated. The third color
is obtained in the same manner.
[0028] The following examples are provided to illustrate the invention.
Example 1
[0029] A dye-donor element was prepared by coating on each side of a 6 µm poly(ethylene
terephthalate) support a subbing layer of titanium alkoxide (DuPont Tyzor TBT)® (0.13
g/m
2) from a n-propyl acetate and n-butyl alcohol solvent mixture.
[0030] The dye formulations listed below were than patch-coated on one side of the above
support:
Yellow layer
[0031]
- 0.26
- g/m2 Y-1 (see above)
- 0.27
- g/m2 CAP-1 (20 s viscosity cellulose acetate propionate, Eastman Chemical Co.)
- 0.07
- g/m2 CAP-2 (5 s viscosity cellulose acetate propionate, Eastman Chemical Co.)
- 0.01
- g/m2 S363 N-1 (a micronized blend of polyethylene, polypropylene, and oxidized polyethylene
particles, Shamrock Technologies, Inc.)
- 0.002
- g/m2 FC-430 (a fluorocarbon surfactant from 3M Co.)
- solvent:
- toluene/methanol/cyclopentanone (66.5:28.5:5)
Magenta layer
[0032]
- 0.15 g/m2
- M-1 (see above)
- 0.14 g/m2
- M-2 (see above)
- 0.24 g/m2
- CAP-1
- 0.08 g/m2
- CAP-2
- 0.01 g/m2
- S363 N-1
- 0.002 g/m2
- FC-430
same solvent as used for coating yellow layer
Cyan layer
[0033]
- 0.38 g/m2
- C-1
- 0.11 g/m2
- C-2
- 0.34 g/m2
- CAP-1
- 0.01 g/m2
- S363 N-1
- 0.002 g/m2
- FC-430
same solvent as used for coating yellow layer
[0034] Two test samples E-1 and E-2 were prepared by coating a magnetic layer on the back
side (opposite to the dye side) of the above donor support. The magnetic coatings
were prepared by blending a dispersion of magnetic particles and a dispersion of an
abrasive or polishing powder. The procedures for making these dispersions are described
below.
Preparation of Magnetic Dispersion
[0035]
1) A high solids grind was obtained by milling CSF-4085V2, cobalt surface-treated
γ-Fe2O3 particles obtained from Toda Kogyo Corp., having a nominal coercivity of 850 Oersted,
in a low-boiling solvent, di-n-butyl phthalate, and a wetting aid or dispersant (GAFAC®
PE-510 organic phosphate surfactant from GAF Corp.) in a 250 cc capacity Eiger mill.
The grind was at 35% solids (33.3% magnetic particles CSF 4085V2, 1.67% GAFAC® PE510)
and 65% di-n-butyl phthalate. The mill was loaded with 90% V/V 1.0 mm Chromanite steel
media, run at 4,000 rev/min with 10°C coolant for 5 hrs.
2) The high solids grind from 1) above was then diluted as follows:
- 2.0%
- cellulose triacetate
- 2.0%
- magnetic dispersion
- 0.1%
- GAFAC® PE-510
- 4.0%
- di-n-butyl phthalate
- 91.9%
- methylene chloride
using a 4% cellulose triacetate solution in methylene chloride and blending in the
remaining material.
Preparation of Abrasive Dispersion
[0036] In a 1-gallon glass jar with seal cap, approximately 2,200 g Zr silicate 1.0-1.2
mm diameter mill media was added. Over a hot water bath, 7.5g Solsperse® 2400 (a dispersant
available from Zeneca, Ltd.) was dissolved in 75g of methyl acetoacetate. This was
added to the jar containing the mill media together with 367.5g methyl acetoacetate,
150g of AKP-50 (α-alumina, particle size ∼ 0.25 µm, obtained from Sumitomo Chemical
Corp.) and the jar sealed and placed on a roller mill at 100 rev/min for 24 hrs. The
median particle size of the abrasive alumina was in the range of 0.2 to 0.3 µm and
the material had an equivalent specific surface area of 9-11 g/m
2. The dispersion was separated from the mill media by screening.
[0037] Coating formulations prepared with the above dispersions were as follows:
E-1 |
MATERIAL |
% SOLIDS |
AIM COVERAGE (g/m2) |
cellulose diacetate |
2.90 |
0.94 |
magnetic dispersion |
0.18 |
0.06 |
cellulose triacetate |
0.18 |
0.06 |
FC-431* |
0.015 |
0.05 |
Solsperse® 24000 |
0.0234 |
0.08 |
* FC-431 (a fluorocarbon surfactant from 3M Corp.) |
[0038]
E-2 |
MATERIAL |
% SOLIDS |
AIM COVERAGE (g/m2) |
cellulose diacetate |
2.90 |
0.94 |
magnetic dispersion |
0.18 |
0.06 |
cellulose triacetate |
0.18 |
0.06 |
dibutyl phthalate |
0.349 |
0.12 |
GAFAC® PE-510 |
0.009 |
0.003 |
FC-431 |
0.015 |
0.05 |
Solsperse® 24000 |
0.0025 |
0.07 |
abrasive dispersion |
0.050 |
0.02 |
[0039] Test sample E-1 was then provided with a slipping layer of the following composition
(coated over the magnetic layer):
- 0.48
- g/m2 KS-1 poly(vinyl acetal) from Sekisui Chemical Corp.
- 0.0003
- g/m2 p-toluenesulfonic acid
- 0.01
- g/m2 PS513® aminopropyl-dimethyl-terminated polydimethylsiloxane, (Petrarch Systems, Inc.)
- 0.07
- g/m2 of a copolymer of poly(propylene oxide) and poly(methyl octyl siloxane), BYK-S732®
(98 % in Stoddard solvent) (Byk Chemie) from an 80:20 3-butanone/methanol solvent
mixture.
[0040] Test sample E-2 was not provided with a slipping layer.
[0041] A comparative control sample C-1 was prepared by coating the same support, dye and
slipping layers of test sample E-1, but omitting the magnetic backcoat.
Example 2
[0042] Writeability/readability tests of the magnetic layers of test samples E-1 and E-2
were performed on a Honeywell 7600 reel-to-reel transport at a speed of 4.8 cm/sec.
Spin Physics Instrumentation heads were used with trackwidths of 1.25 mm and 2.5 µm
gaps. The recording head was wound with 90 turns and the reading head with 480 turns.
The output signal from the reading head was amplified by a 70 dB gain low-noise preamplifier
and filtered by a 4-pole Butterworth filter with a bandwidth of 7.5 kHz. Characterization
of the output signal was performed using a LeCroy 9314L digital oscilloscope. The
magnetic recording results are shown as follows:
TABLE 1
Parameter |
E-1 with slipping layer |
E-2 without slipping layer |
Optimum record current @ density of 80 flux transitions/mm |
29 mA |
24 mA |
Isolated Pulse Width |
5.43 µm |
4.93 µm |
Output Voltage |
48.1 µvolt |
51.4 µvolt |
[0043] The above results show that even though the slipping layer degrades the magnetic
recording performance to some extent, the medium is still capable of supporting low-density
(20-30 bits/mm or >600 bits/inch) information.
Example 3
[0044] To evaluate printing performance of donor elements according to the present invention,
polycarbonate dye receivers were prepared using the following materials:

[0045] LEXAN® 141 (a bisphenol A polycarbonate available from General Electric Co.)

[0046] K-polycarbonate, a random terpolymer made in-house from bisphenol A, diethylene glycol,
and PS510 (a polydimethylsiloxane available from Huels America)

[0047] KL3-1013 a polyether-modified bisphenol A polycarbonate available from Bayer AG)
[0048] A receiver element was prepared by applying a subbing layer of 0.11 g/m
2 of Dow Z-6020 (a water-soluble aminoalkyl-alkoxysilane available from Dow Chemical
Co.) in 3A alcohol to a support of a microvoided polypropylene layer laminated onto
a white reflective support of titanium dioxide-pigmented polyethylene-overcoated paper
stock. A receiving layer of the following composition was coated onto the subbing
layer:
- 1.46 g/m2
- Lexan® 141
- 1.78 g/m2
- KL3-1013
- 0.01 g/m2
- FC-431
- 0.32 g/m2
- dibutyl phthalate
- 0.32 g/m2
- methylene chloride
[0049] Subsequently, the following overcoat layer was applied to the receiving layer:
- 0.22 g/m2
- K-polycarbonate
- 0.008 g/m2
- DC-510 (a silicone fluid surfactant from Dow-Corning
- 0.02 g/m2
- FC-431
from methylene chloride solvent.
[0050] For printing evaluation of E-1 and C-1, the dye side of the dye-donor element strip
approximately 10 cm x 13 cm in area was placed in contact with the dye image-receiving
element of the same area. The assemblage was clamped to a stepper-motor driven 60
mm diameter rubber roller, and a TDK Thermal Head (no. L-231) (thermostated at 26°C)
was pressed with a force of 36 newtons against the dye-donor element side of the assemblage
pushing it against the rubber roller.
[0051] The imaging electronics were activated causing the donor/receiver assemblage to be
drawn between the printing head and roller at 6.9 mm/s. Coincidentally, the resistive
elements in the thermal print head were pulsed for 29 µs/pulse at 128 µs intervals
during the 33 msec/dot printing time. An image was generated with regions of varying
density by setting the number of pulses/dot for a particular density at a set value
between 0 to 255. The voltage supplied to the print head was approximately 23.5 volts,
resulting in an instantaneous peak power of 1.3 watts/dot and a maximum total energy
of 9.6 mjoules/dot.
[0052] The dye transfer element was separated from the receiving element immediately after
passing the thermal head. The receiver element was then backed up and the position
reinitialized under the head and printed again with the next color. In this way a
full color (YMC) image was obtained. The print quality was good in all cases and there
were no sticking problems at the donor/thermal head interface.
[0053] The Status A densities of the images were measured on an X-Rite densitometer (X-Rite
Corp., Grandville, MI) and are as follows:
Table 2
Energy (mJ/dot) |
Yellow |
Magenta |
Cyan |
|
C-1 |
E-1 |
C-1 |
E-1 |
C-1 |
E-1 |
0 |
0.11 |
0.10 |
0.12 |
0.11 |
0.11 |
0.10 |
1.1 |
0.11 |
0.10 |
0.12 |
0.11 |
0.11 |
0.11 |
2.1 |
0.11 |
0.10 |
0.12 |
0.11 |
0.11 |
0.11 |
3 |
0.14 |
0.12 |
0.15 |
0.12 |
0.14 |
0.12 |
4 |
0.36 |
0.31 |
0.34 |
0.30 |
0.32 |
0.30 |
4.9 |
0.55 |
0.50 |
0.50 |
0.47 |
0.46 |
0.42 |
5.8 |
0.3 |
0.69 |
0.67 |
0.64 |
0.61 |
0.58 |
6.8 |
0.96 |
0.91 |
0.87 |
0.84 |
0.81 |
0.79 |
7.7 |
1.23 |
1.20 |
1.16 |
1.12 |
1.07 |
1.05 |
8.7 |
1.58 |
1.57 |
1.54 |
1.49 |
1.40 |
1.35 |
9.6 |
1.99 |
1.97 |
2.40 |
1.96 |
1.80 |
1.74 |
[0054] The above results indicate that the addition of a magnetic layer to the opposite
side of the dye-donor element in accordance with the invention does not have any appreciable
effect on the density of the transferred image.
1. A dye-donor element for thermal dye transfer comprising a support having on one side
thereof a dye layer and on the other side thereof in the direct opposite area to at
least a portion of said dye layer, a magnetic recording layer and a slipping layer,
in that order.
2. The element of Claim 1 wherein said magnetic recording layer is present at a concentration
of from 0.01 to 4 g/m2.
3. The element of Claim 1 wherein said magnetic material is a ferromagnetic oxide or
a ferromagnetic metal particle.
4. The element of Claim 1 wherein said magnetic material is gamma Fe2O3 having a cobalt surface treatment.
5. A process of forming a dye transfer image comprising:
(a) imagewise-heating a dye-donor element comprising a support having on one side
thereof a dye layer and on the other side thereof in the direct opposite area to at
least a portion of said dye layer, a magnetic recording layer and a slipping layer,
in that order, and
(b) transferring a dye image to a dye-receiving element to form said dye transfer
image.
6. The process of Claim 5 wherein said magnetic recording layer is present at a concentration
of from 0.01 to 4 g/m2.
7. The process of Claim 5 wherein said magnetic material is a ferromagnetic oxide or
a ferromagnetic metal particle.
8. The process of Claim 5 wherein said magnetic material is gamma Fe2O3 having a cobalt surface treatment.
9. A thermal dye transfer assemblage comprising
(a) a dye-donor element comprising a support having on one side thereof a dye layer
and on the other side thereof in the direct opposite area to at least a portion of
said dye layer, a magnetic recording layer and a slipping layer, in that order, and
(b) a dye-receiving element comprising a support having thereon a dye image-receiving
layer,
said dye-receiving element being in a superposed relationship with said dye-donor
element so that said dye layer is in contact with said dye image-receiving layer.
10. The assemblage of Claim 9 wherein said magnetic recording layer is present at a concentration
of from 0.01 to 4 g/m2.