Thermal transfer ribbon

A thermal transfer ribbon includes a substrate and a layer thereon comprising a mixture of an emulsion essentially consisting of hydrocarbon, paraffin and carnauba waxes and an acetate copolymer, and a fluorescent color coating essentially containing a fluorescent pigment, a color toner and a filler.

BACKGROUND OF THE INVENTION 
In the printing field, the impact type printer has been the predominant 
apparatus for providing increased throughput of printed information. The 
impact printers have included the dot matrix type wherein individual print 
wires are driven from a home position to a printing position by individual 
and separate drivers. The impact printers also have included the full 
character type wherein individual type elements are caused to be driven 
against a ribbon and paper or like record media adjacent and in contact 
with a platen. 
The typical and well-known arrangement in a printing operation provides for 
transfer of a portion of the ink from the ribbon to result in a mark or 
image on the paper. Another arrangement includes the use of carbonless 
paper wherein the impact from a print wire or a type element causes 
rupture of encapsulated material for marking the paper. Also known are 
printing inks which contain magnetic particles wherein certain of the 
particles are transferred to the record media for encoding characters in 
manner and fashion so as to be machine readable in a subsequent operation. 
One of the known encoding systems is MICR (Magnetic Ink Character 
Recognition) utilizing the manner of operation as just mentioned. 
While the impact printing method has dominated the industry, one 
disadvantage of this type printing is the noise level which is attained 
during printing operation. Many efforts have been made to reduce the high 
noise levels by use of sound absorbing or cushioning materials or by 
isolating the printing apparatus. 
More recently, the advent of thermal printing which effectively and 
significantly reduces the noise levels has brought about the requirements 
for heating of extremely precise areas of the record media by use of 
relatively high currents. The intense heating of the localized areas 
causes transfer of ink from a ribbon onto the paper. Alternatively, the 
paper may be of the thermal type which includes materials that are 
responsive to the generated heat. 
The use of thermal printing with different color inks has also been 
proposed and applied in certain technologies. An application for thermal 
printing has included the postal system which makes use of one or more 
fluorescent pigments. 
Representative documentation in the area of nonimpact printing includes 
U.S. Pat. No. 3,117,018, issued to E. Strauss on Jan. 7, 1964, which 
discloses a color transfer medium and method of producing the same by 
applying a coating consisting of a polycarbonate, a solvent, a plasticizer 
and a pigment, and then drying the coating to form a solid transfer layer. 
U.S. Pat. No. 4,663,278, issued to J. H. Blose et al. on May 16, 1972, 
discloses a thermal transfer medium having a base with a transferable 
coating composition of a cellulosic polymer, a thermoplastic resin, a 
plasticizer, and a sensible dye or oxide pigment material. 
U.S. Pat. No. 4,251,276, issued to W. I. Ferree et al. on Feb. 17, 1981, 
discloses a transfer ribbon having a substrate coated with a 
thermally-active ink composition comprising a thermally-stable polymer, an 
oil-gelling agent, and an oil-dissolving medium or plasticizer present in 
a percentage by weight of the total nonvolatile components. 
U.S. Pat. No. 4,272,292, issued to S. Mizuno et al. on June 9, 1981, 
discloses an ink composition comprising at least one of the carbinol bases 
of the basic dyes, a strong base, a binder and a solvent. 
U.S. Pat. No. 4,461,586, issued to T. Kawanishi et al. on July 24, 1984, 
discloses an ink ribbon having an electroconductive base layer comprising 
a binder resin and an electroconductive material, and an electroconductive 
ink layer comprising a thermoplastic material and an electroconductive 
material. 
U.S. Pat. No. 4,474,844, issued to T. Omori et al. on October 1984, 
discloses a heat transfer recording medium comprising tissue paper with a 
thermal-responsive ink layer. The paper thickness, density and smoothness 
are set out by measurement and water content is a percentage of the ink 
layer. 
U.S. Pat. No. 4,614,682, issued to A. Suzuki et al. on Sept. 30, 1986, 
discloses a thermo-sensitive image transfer recording medium comprising a 
support and an ink layer consisting of a dye, a binder and a pigment of 
needle-like crystal form. 
U.S. Pat. No. 4,624,891, issued to H. Sato et al. on Nov. 25, 1986, 
discloses heat transfer material comprising a micro-network porous resin 
of thermoplastic resin and heat fusible gel ink which comprises a 
colorant, an oil and a gelatin agent. 
And, U.S. Pat. No. 4,627,997, issued to Y. Ide on Dec. 9, 1986, discloses a 
thermal transfer recording medium comprising an inking layer of a 
fluorescent substance, a coloring agent, waxes, and a binder on a 
substrate. 
SUMMARY OF THE INVENTION 
The present invention relates to nonimpact printing. More particularly, the 
invention provides a coating formulation or composition and a thermal 
ribbon or transfer medium for use in imaging or encoding characters on 
paper or like record media documents which enable machine, human, or 
reflectance reading of the imaged or encoded characters. The thermal 
transfer ribbon enables printing in quiet and efficient manner and makes 
use of the advantages of thermal printing on documents with a signal 
inducible ink. 
The ribbon comprises a thin, smooth substrate such as tissue-type paper or 
polyester-type plastic on which is applied a thermal-responsive layer or 
coating that generally includes a wax mixture dispersed in a binding mix 
of an ethylene copolymer and/or a hydrocarbon resin to form the wax 
emulsion. The hydrocarbon resin and the solids of the wax emulsion are 
mixed or dispersed into solution with dyes and fluorescent pigments in an 
attritor or other conventional dispersing equipment. The 
thermal-responsive layer or coating ingredients include a red-orange base, 
a red toning pigment, a filler, and a yellow fluorescent pigment. The 
coating is then applied to the substrate by well-known or conventional 
coating techniques. 
In view of the above discussion, a principal object of the present 
invention is to provide a ribbon including a thermal-responsive coating 
thereon. 
Another object of the present invention is to provide a thermal transfer 
ribbon substrate including a coating thereon for use in imaging or 
encoding operations. 
An additional object of the present invention is to provide a coating on a 
ribbon substrate having ingredients in the coating which are responsive to 
heat for transferring a portion of the coating to paper or like record 
media. 
A further object of the present invention is to provide a coating on a 
ribbon substrate, which coating includes a pigment material and a wax 
emulsion dispersed in a binder mix and which is responsive to heat for 
transferring the coating in precise printing manner to paper or like 
record media. 
Still another object of the present invention is to provide a 
thermally-activated coating on a ribbon that is completely transferred 
from the base of the ribbon onto the paper or document in an imaging 
operation in printing manner at precise positions and during the time when 
the thermal elements are activated to produce a well-defined and precise 
or sharp image. 
Still an additional object of the present invention is to provide a coating 
consisting essentially of a wax emulsion and fluorescent pigments and 
which coating is applied to a substrate. 
Still a further object of the present invention is to provide a two stage 
process which includes the preparation of a specific wax emulsion and the 
preparation of a transfer coating for use in thermal printing. 
Still another object of the present invention is to provide a heat 
sensitive, fluorescent type, transfer ribbon created by use of fluorescent 
pigments, waxes, resins, dyes and plasticizers to transfer a sharp image 
from a tissue or a polyester base substrate in a temperature range of 
50.degree. C. to 125.degree. C. 
Additional advantages and features of the present invention will become 
apparent and fully understood from a reading of the following description 
taken together with the annexed drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The thermal transfer coating of the present invention is specifically 
designed and formulated to provide a transfer mark or image which meets 
specific criteria or requirements for a fluorescent red thermal transfer 
ribbon which is suitable and acceptable for postal applications. 
Fluorescence of the ribbon should be greater than 10 pmu (postage meter 
unit). The peak wavelength of the fluorescence is at 625.+-.25 nm 
(nanometers). 
The color of the transferred image is controlled to be within the coloring 
of a reddish-orange hue similar to the color of the postage meter indicia. 
And, the color of the transferred image, as determinated on a 7/8 inch 
square, will have values of L=45, a=62 and b=20 on the Hunter Color Meter. 
L is defined as a measure of lightness, a is a measure on the red-green 
axis, and b is a measure on the blue-yellow axis. A variance of .+-.5 is 
allowed for the value of L with total color difference (.DELTA.) not to 
exceed 10 when using the formula: 
EQU .DELTA.=.sqroot.(.DELTA.L).sup.2 +(.DELTA.a).sup.2 +(.DELTA.b).sup.2 
The transfer ribbon 20, as illustrated in FIGS. 1 and 2, comprises a base 
or substrate 22 of thin, smooth, tissue-type paper or polyester-type 
plastic or like material having a coating 24 which is thermally activated 
and includes nonmagnetic pigment or particles 26 as an ingredient therein 
for use in imaging or encoding operations to enable human or reflectance 
reading of characters. Each character that is imaged on a receiving paper 
28 or like record media produces a unique waveform that is recognized and 
read by the reader. In the case of thermal transfer ribbons relying solely 
on the nonmagnetic thermal printing concept, the pigment or particles 26 
include coloring materials such as pigments, fillers and dyes. 
As alluded to above, it is noted that the use of a thermal printer having a 
print head element, as 30, substantially reduces noise levels in the 
printing operation and provides reliability in imaging or encoding of 
paper or like documents 28. The thermal transfer ribbon 20 provides the 
advantages of thermal printing while encoding or imaging the document 28 
with a nonmagnetic signal inducible ink. When the heating elements 30 of a 
thermal print head are activated, the imaging or encoding operation 
requires that the pigment or particles of material 26 on the coated ribbon 
20 be completely transferred from the ribbon to the document 28 in manner 
and form to produce the precisely defined characters 32 for recognition by 
the reader. In the case of nonmagnetic thermal printing, the imaging or 
encoding material 26 is completely transferred to the document 28 to 
produce the precisely defined characters 32 for recognition and machine, 
human, or reflectance reading thereof. 
FIG. 3 is a diagrammatic view of a substrate 34 having a width occupied by 
a fluorescent thermal transfer coating 36 on approximately one half of the 
substrate and a thermal transfer coating 40 of another color on the other 
half of the substrate. The coating 36 includes pigment or particles 38 and 
the coating 40 includes pigment or particles 42. The width of the 
substrate 34 or of the printed area of the transfer coatings 36 and 40 is 
dependent upon the configuration of the thermal printer or like apparatus 
that is used for causing transfer of the image from the base or substrate 
to the paper or other document. FIG. 3 shows a distinct line of 
demarcation 35 between the fluorescent coating 36 and the coating 40 of 
another color. It is understood, of course, that minor variations of 
either an uncoated or clear strip along the line 35 or an overlapping of 
the coatings 36 and 40 may unintentionally occur. 
FIG. 4 is a diagrammatic view of a substrate 44 having a portion thereof 
coated with a fluorescent thermal transfer coating 46 and an adjacent 
portion coated with a thermal transfer coating 48 of another color. The 
coatings 46 and 48 are repeated along the length of the substrate 44. The 
coating 46 has pigment or particles 50 and the coating 48 has pigment or 
particles 52. 
FIG. 5 is a diagrammatic view of a wider substrate 54 having a narrow 
portion thereof coated with a fluorescent thermal transfer coating 56 and 
an adjacent narrow portion coated with a thermal transfer coating 58 of 
another color. The coatings 56 and 58 are repeated along the length of the 
substrate. The coating 56 contains pigment or particles 60 and the coating 
58 contains pigment or particles 62. The arrows 64 indicate the direction 
in which the transfer ribbon is advanced or transported in a printing or 
imaging operation. 
The thermal transfer ribbon of the present invention is produced in a two 
stage process wherein the first stage includes preparation of a specific 
wax emulsion or formulation, and the second stage includes preparation of 
the transfer coating or layer. 
Generally, a wax adhesive emulsion uses hydrocarbon, paraffin or ozocerite, 
carnauba, microcrystalline waxes and an ethylene vinyl acetate copolymer 
and/or a hydrocarbon resin soluble in aliphatic solvents. The wax emulsion 
uses waxes plus the acetate copolymer plus the hydrocarbon resin in one 
formulation. In another formulation, the wax emulsion uses waxes plus the 
acetate copolymer or the hydrocarbon resin. 
A preferred wax adhesive emulsion or formulation at 20% to 50% solids to 
satisfy the requirements of the first stage of the process includes the 
specific ingredients in appropriate amounts as set forth in Table 1 of 
Example I. 
EXAMPLE I 
TABLE 1 
______________________________________ 
% Dry 
Wax Emulsion 
Percent Dry Wet Amt. Range 
______________________________________ 
WB-7 Wax 27 169.6 20-45% 
Paraffin 162 Wax 
46 289.3 35-65% 
Carnauba #3 Wax 
20 125.8 5-30% 
Elvax 4310 7 44.3 3-15% 
Mineral Spirits 1361.3 
100 1990.3 
(31.6% Solids) 
______________________________________ 
The nonvolatile materials in the above formulation equate from 20% to 50%, 
and it is here noted that Lacolene, or VM and P Naptha, can be substituted 
in place of the mineral spirits. The wax emulsion is heated to 60.degree. 
C. while mixing the above solution and then is allowed to cool to room 
temperature at the end of the first stage. 
The second stage of the process includes preparation of a preferred 
fluorescent color, thermal transfer coating wherein the above wax emulsion 
is heated to a range within 40.degree.-45.degree. C. and the following 
ingredients in appropriate amounts, as set forth in Table 2, are placed 
into dispersion equipment such as a ball mill, a shot mill, a sand mill, 
or an attritor, and then ground for a period of approximately 20-40 
minutes, or for a sufficient period of time to provide a uniform fine (3-5 
microns size) dispersion. 
TABLE 2 
______________________________________ 
% Dry 
Coating Percent Dry Wet Amt. Range 
______________________________________ 
Wax Emulsion 79.9 1990.3 50-90% 
(From Table 1) 
Red-Orange PM Base 
6.3 49.9 5-20% 
(47% Solids) 
Lithol Scarlet K-3700 
12.5 98.1 5-20% 
Paliogen 3911HD 
1.3 10.0 0-10% 
100.0 2148.3 
Percent Solids 25-50% 
______________________________________ 
Example II provides the specific ingredients in appropriate amounts for 
another fluorescent coating which uses different pigments. 
EXAMPLE II 
TABLE 1 
______________________________________ 
% Dry 
Wax Emulsion 
Percent Dry Wet Amt. Range 
______________________________________ 
Paraffin 162 Wax 
50 277.4 35-65% 
WB-17 Wax 30 166.4 20-45% 
Carnauba #3 Wax 
13 72.1 5-20% 
Elvax 40W 7 38.8 3-15% 
Mineral Spirits 
-- 1313.2 
100.0 1867.9 
(29.7% Solids) 
______________________________________ 
TABLE 2 
______________________________________ 
% Dry 
Coating Percent Dry 
Wet Amt. Range 
______________________________________ 
Wax Emulsion 72.7 1867.9 50-90% 
(From Table 1) 
Red-Orange PM Base 
9.8 159.0 5-20% 
(47% Solids) 
Red Toner #8197 
7.0 53.4 5-10% 
Calcium Carbonate 
8.4 64.1 3-10% 
ARC Yellow A16N 
2.1 16.0 1-4% 
100.0 2160.5 
(35.3% Solids) 
______________________________________ 
Example III provides the specific ingredients in appropriate amounts for 
yet another fluorescent coating which uses different pigments. 
EXAMPLE III 
TABLE 1 
______________________________________ 
% Dry 
Wax Emulsion 
Percent Dry Wet Amt. Range 
______________________________________ 
WB-7 Wax 30 187.6 20-45% 
Paraffin 162 Wax 
50 311.8 35-65% 
Carnauba #3 Wax 
13 80.9 5-30% 
Elvax 4310 7 44.0 3-15% 
Mineral Spirits 
-- 1838.5 
100 2462.8 
(25.3% Solids) 
______________________________________ 
TABLE 2 
______________________________________ 
% Dry 
Coating Percent Dry Wet Amt. Range 
______________________________________ 
Wax Emulsion 
64.9 2462.8 50-90% 
(From Table 1) 
10-5C-35-A102 
23.1 247.5 15-30% 
White Pigment 
4.6 49.5 0-10% 
Fire Orange 
9.2 99.0 5-15% 
100.0 2858.8 
(35.7% Solids) 
______________________________________ 
Example IV provides the specific ingredients in appropriate amounts for 
still another fluorescent coating which uses a hydrocarbon resin and a 
different arrangement of pigments. 
TABLE 1 
______________________________________ 
% Dry 
Wax Emulsion 
Percent Dry Wet Amt. Range 
______________________________________ 
WB-7 Wax 30 158.1 20-45% 
Paraffin 162 Wax 
40 210.5 35-65% 
Carnauba #3 Wax 
13 68.2 5-20% 
Elvax 40W 7 37.1 3-15% 
Piccotex-75 
10 52.9 0-25% 
Mineral Spirits 
-- 1397.0 -- 
100 1923.8 
______________________________________ 
TABLE 2 
______________________________________ 
% Dry 
Coating Percent Dry 
Wet Amt. Range 
______________________________________ 
Wax Emulsion 69.9 1923.8 50-90% 
(From Table 1) 
Red-Orange PM Base 
6.3 47.3 3-10% 
Paliogen 3911 HD 
1.3 9.7 0-10% 
Lithol Scarlet L-3700 
12.5 94.1 5-20% 
Fire Orange 10.0 75.1 5-20% 
100 2150.0 
Percent Solids 20-50% 
______________________________________ 
Paraffin 162 wax is a mixture of solid crystalline hydrocarbons chiefly of 
the methane series derived from the paraffin distillate portion of crude 
petroleum and is soluble in benzene, ligroine, warm alcohol, chloroform, 
turpentine, carbon disulfide and olive oil. WB-7 and WB-17 are oxidized, 
isocyanated hydrocarbon waxes. Carnauba #3 is a hard, amorphous wax 
derived by exudation from leaves of the wax palm and is soluble in ether, 
boiling alcohol and alkalies. Ozocerite is a natural paraffin wax 
occurring in irregular veins, consists principally of hydrocarbons, is 
soluble in water and has a variable melting point. Elvax 40W and 4310 are 
ethylene vinyl acetate copolymers. Piccotex-75 is one of the series of 
hydrocarbon resins and defined as a hard, color stable, substituted 
styrene copolymer resin. 
The class or group of microcrystalline waxes may also be used in the wax 
emulsion and essentially consist of petroleum waxes having a higher 
molecular weight, a higher melting point, and a higher viscosity than 
paraffin wax. 
In the fluorescent color coating portion of the invention, the Lithol 
Scarlet K-3700 and L-3700, the Paliogen 3911 HD and 10-5C-35-A102 
ingredients are toning pigments, and the White Pigment and the Fire Orange 
are fluorescent pigments. The Red-Orange PM Base is a fluorescent pigment, 
Red Toner #8197 is a toning pigment, and ARC Yellow A16N is a fluorescent 
pigment. It is noted that a pigment is defined as a solid that reflects 
light of certain wavelengths while absorbing light of other wavelengths, 
without producing appreciable luminescence; in effect, pigments are used 
to impart color to other materials. 
The nonvolatile materials of the fluorescent dispersion are controlled at 
25% to 55% for proper viscosity. It should be noted that all ingredients 
are carefully weighed and solubilized in the mineral spirits using 
appropriate heat and agitation. After the solution is complete, it is 
slowly cooled to form a viscous wax dispersion to prepare a thermally 
active, transfer coating. 
The substrate or base 22, which may be 30-40 gauge capacitor tissue, 
manufactured by Glatz, or 14-35 gauge polyester film as manufactured by 
duPont under the trademark Mylar, should have a high tensile strength to 
provide for ease in handling and coating of the substrate. Additionally, 
the substrate should have properties of minimum thickness and low heat 
resistance to prolong the life of the heating elements 30 of the thermal 
print head by reason of reduced print head actuating voltage and the 
resultant reduction in burn time. 
The coating 24 is applied to the substrate 22 by means of conventional 
coating techniques such as a Meyer rod or like wire-wound doctor bar set 
up on a typical solvent coating machine to provide a coating thickness in 
a range of 0.0001 to 0.0004 inches. This coating thickness equates to a 
coating weight of between 9 and 16 milligrams per four square inches. The 
coating is made up of approximately 25% to 55% nonvolatile material and is 
maintained at a desired temperature and viscosity throughout the coating 
process. A temperature of approximately 40.degree.-45.degree. C. is 
maintained during the entire coating process. After the coating is applied 
to the substrate, the web of ribbon is passed through a dryer at an 
elevated temperature in the range between 93.degree. and 120.degree. C. 
for approximately 5-10 seconds to ensure good drying and adherence of the 
coating 24 onto the substrate 22 in making the transfer ribbon 20. The 
above-mentioned coating weight, as applied by the Meyer rod onto a 
preferred 9-12 microns thick substrate, overall translates to a total 
thickness of 12-15 microns. The coating 24 can be fully transferred onto 
the receiving substrate or paper 28 in the range of 50.degree.-120.degree. 
C. by changing the ranges of the waxes used in the first step of the 
process. 
The availability of the various ingredients used in the present invention 
is provided by the following list of companies. 
______________________________________ 
Material Supplier 
______________________________________ 
WB-7 and WB-17 Bareco 
Paraffin 162 Wax Boler 
Carnauba #3 Wax Baldini & Co., Inc. 
Elvax 40W and 4310 Wax 
E. I. duPont 
Piccotex-75 Hercules 
Mineral Spirits Ashland Chemical Co. 
Red Orange PM Base Day-Glo 
Red Toner #8197 Paul Uhlich 
Calcium Carbonate Omya 
ARC Yellow A16N Day-Glo 
Lithol Scarlet K-3700 
BASF 
Paliogen 3911 HD BASF 
10-5C-35-A102 Hilton-Davis 
White Pigment Day-Glo 
Fire Orange Day-Glo 
______________________________________ 
The method of thermal transfer of the images by use of a dry ribbon enables 
the creation of the fluorescent mark or image which is recognized for 
postage recognition applications. The fluorescent mark or image is 
produced by suitable software control of a thermal transfer printer to 
create a bar code or other postal indicia which can be recognized by 
reading of the mark. 
In the case where a dual color ribbon is desired, the arrangement of FIG. 3 
can be used wherein a portion of the ribbon width comprises the 
fluorescent color and the other portion of the ribbon comprises a red, 
black, blue, yellow color or a mixture of colors. FIGS. 4 and 5 illustrate 
a sequential arrangement of the fluorescent color and any other color or 
mixture of colors in repeated manner. 
It is thus seen that herein shown and described is a thermal transfer 
ribbon for use in thermal printing operations which includes a 
thermal-responsive coating on one surface of the ribbon. The coated ribbon 
enables transfer of coating material onto documents or like record media 
during the printing operation to form characters on the media in an 
imaging or in an encoding nature, permitting machine, or human, or 
reflectance reading of the characters. Using the above formulations, a 
ribbon can be produced to meet specific thermal transfer printing 
mechanism that provides a sharp and scratch-resistant mark. The present 
invention enables the accomplishment of the objects and advantages 
mentioned above, and while a preferred embodiment has been disclosed 
herein, variations thereof may occur to those skilled in the art. It is 
contemplated that all such variations and any modifications not departing 
from the spirit and scope of the invention hereof are to be construed in 
accordance with the following claims.