Thermal magnetic transfer ribbon

A thermal magnetic transfer ribbon includes a substrate and a coating containing resin, oil and wax in a binder mix which is dispersed with a magnetic pigment in a solvent solution.

BACKGROUND OF THE INVENTION 
In the printing field, the impact type printer has been the predominant 
apparatus for providing increased thruput 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, and 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 requirement 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 
or alternatively, the paper may be of the thermal type which includes 
materials which are responsive to the generated heat. 
Further, it is seen that the use of thermal printing is adaptable for MICR 
encoding of documents wherein magnetic particles are caused to be 
transferred onto the documents for machine reading of the characters. The 
thermal transfer printing approach for use in MICR encoding of documents 
enables reliability in operation at the lower noise levels. 
Representative documentation in the area of magnetic ink for use in 
non-impact printing includes UK patent application No. 2106038A, published 
Apr. 7, 1983, which discloses a heat-sensitive magnetic transfer element 
for printing a magnetic image to be recognized by a magnetic ink character 
reader and which element comprises a heat-resisting foundation and a 
heat-sensitive transfer layer including a magnetic powder in a wax or 
plastic binder and having a melting point of 50 degrees to 120 degrees C. 
so that portions of the layer can be transferred onto a receiving paper in 
the form of a magnetic image by a thermal printer. 
U.S. Pat. No. 3,042,616, issued to R. J. Brown on July 3, 1962, discloses a 
process of preparing magnetic ink by wetting powdered iron with a resinous 
solution and adding an aqueous slurry of carbonate to form droplets 
surrounded by solvent liquid. The solvent is separated by water and the 
particles are then filtered and dried to produce spheres of magnetic ink. 
U.S. Pat. No. 3,117,018, issued to E. Strauss on Jan. 7, 1964, 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. 3,413,183, issued to H. T. Findlay et al. on Nov. 26, 1968, 
discloses a transfer medium provided by a coating process wherein the 
transfer layer is a polycarbonate having voids which hold an imaging 
material. 
U.S. Pat. No. 3,744,611, issued to L. Montanari et al. on July 10, 1973, 
discloses an electrothermal printer for non-impact printing on plain paper 
that uses a ribbon made of a substrate having a thermal-transferable ink 
coated on one surface thereof and a coating of electrically resistive 
material on the other surface. 
U.S. Pat. No. 3,855,448, issued to T. Hanagata et al. on Dec. 17, 1974, 
discloses a print ribbon comprising a heat-resistant support sheet with a 
heat-fusible material layer of thermoplastic resin, carbon black, pigment 
or oleic acid fats, and wax, mineral oils or vegetable oils. 
U.S. Pat. No. 4,022,936, issued to R. E. Miller et al. on May 10, 1977, 
discloses a process for making a sensitized record sheet by providing a 
substrate, coating the substrate with an aqueous composition, and then 
drying the coating. 
U.S. Pat. No. 4,103,066, issued to G. F. Brooks et al. on July 25, 1978, 
discloses a ribbon for non-impact printing comprising a transfer coating 
and a substrate which is a polycarbonate resin containing a percentage by 
weight of electrically-conductive carbon black. 
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-activated ink composition comprising a thermally-stable polymer, 
an oil-gelling agent, and an oil dissolving medium present in a percentage 
by weight of the total nonvolatile components. 
U.S. Pat. No. 4,291,994, issued to T. L. Smith et al. on Sept. 29, 1981, 
discloses a ribbon for non-impact printing which comprises a transfer 
coating and a substrate containing resin which is a mixture of 
polycarbonate, a block copolymer of bisphenol carbonate and dimethyl 
siloxane, and a percentage by weight of electrically conductive carbon 
black. 
And, U.S. Pat. No. 4,309,117, issued to L. S. Chang et al. on Jan. 5, 1982, 
discloses a ribbon configuration for resistive ribbon thermal transfer 
printing comprising a low resistive layer of conductive carbon, a high 
resistive layer of a ceramic metal mixture, a stainless steel conductive 
layer, and an ink transfer layer. 
SUMMARY OF THE INVENTION 
The present invention relates to non-impact printing. More particularly, 
the invention provides a thermal magnetic ribbon or transfer medium for 
use in encoding characters on paper or like record media documents which 
enables machine reading of the encoded characters. The thermal magnetic 
transfer ribbon makes use of the advantages of thermal printing while 
encoding documents with a magnetic signal inducible ink. The ribbon 
comprises a thin, smooth substrate such as tissue-type paper or 
polyester-type plastic on which is applied a coating that generally 
includes a magnetic pigment and a wax mixture dispersed in a binder mix of 
resin. The resin and the solids are mixed into solution along with a 
magnetic filler and the wax mixture is added after wetting the pigment. 
The coating is then put through a setting procedure by drying the coating 
at an elevated temperature. 
In view of the above discussion, the principal object of the present 
invention is to provide a ribbon including a thermal magnetic coating 
thereon. 
Another object of the present invention is to provide a thermal magnetic 
transfer ribbon including a coating thereon for use in encoding 
operations. 
An additional object of the present invention is to provide a magnetic 
coating on a ribbon having ingredients in the coating which are responsive 
to heat for transferring 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 magnetic pigment and a wax 
mixture 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 encoding 
operation in printing manner at precise positions and during the time when 
the thermal elements are activated. 
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 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 magnetic particles 26 as an ingredient therein for use in 
encoding operations to enable machine reading of characters. Each 
character that is imaged on a receiving paper 28 or like record media 
produces a unique magnetic waveform that is recognized and read by the 
reader. 
As alluded to above, it is noted that the use of thermal printer having a 
print head element, as 30, substantially reduces noise levels in the 
printing operation and provides reliability in MICR encoding of paper or 
like documents 28. The thermal magnetic transfer ribbon 20 enables the 
advantages of thermal printing while encoding the document 28 with a 
magnetic signal inducible ink. When the heating elements 30 of a thermal 
print head are activated, the encoding operation requires that the 
magnetic particles or like material 26 on the coated ribbon 20 be 
completely transferred from the ribbon to the document 28 in manner and 
form to produce precisely defined characters 32 for recognition by the 
reader. 
The coating of the present invention basically consists of a heated mixture 
to which is added a solids mixture, the two mixtures having ingredients of 
appropriate amounts making up the formulation. The heated mixture consists 
of the following ingredients in a raw coating sample weight of 100 grams. 
Resin: 0-10 g, 
Oil: 1.5-5 g, 
Wax: 15-50 g, 
Additives: 0-5 g, 
Solvent: 30-60 g. 
In the solvent based coating, the above ingredients are combined in 
appropriate amounts and the solvent coating mixture is stirred while being 
heated to approximately 80 degrees C. for 10 minutes. The heated mixture 
is added along with the solids mixture to the dispersion equipment while 
the temperature is still at approximately 80 degrees C. 
The solvent coating solids mixture composition includes the following 
ingredients: 
Pigment: 12-50 g, 
Wetting agents: 0.5-3 g. 
After the solids mixture and the solvent based heated mixture are added to 
the dispersion unit, the combined mixture is ground for a sufficient 
amount of time to insure good pigment wetting and to reduce size and 
condition of agglomerates. During the dispersion process the temperature 
of the coating is maintained at approximately 55 degrees C. 
In the case of a hot melt coating, the heated mixture consists of the 
following ingredients: 
Resin: 3-15 g, 
Wax: 15-60 g, 
Additives: 0-5 g. 
This mixture is melted and stirred to uniformly distribute all the 
ingredients and is maintained at a temperature of approximately 120 
degrees C. 
The solids mixture for the hot melt coating consists of the following 
ingredients: 
Pigment: 25-50 g, 
Oil: 0-10 g, 
Additives: 0-5 g, 
Solvent: 50-100 g. 
This solids mixture of ingredients is ground in the dispersion equipment 
for a sufficient length of time to wet out the pigment and to reduce the 
size and condition of the agglomerates. The solids mixture is then slowly 
added to the hot melt coating heated mixture and is stirred to insure good 
mixing of all the ingredients. The solvent ingredient of the solids 
mixture evaporates when it is added to the 120 degrees C. heated mixture. 
After the coating 24 has been applied to the substrate 22, the transfer 
ribbon 20 is passed through a dryer at an elevated temperature in a range 
between 93 degrees and 150 degrees C. for approximately five to ten 
seconds to provide good adherence of the coating onto the substrate. 
Having disclosed generally the ingredients which make up the coating of the 
present invention, the following examples teach specific formulations of 
the coating. A preferred formulation and method of making the coating is 
in accordance with the following example. 
EXAMPLE I 
Example I is a composition and method of making a heat sensitive transfer 
layer or coating 24 for the substrate 22 to a coating weight between 7.7 
and 13.5 grams per square meter. The composition, based on a weight of 100 
kilograms of raw coating, includes the following two basic mixtures, 
namely, a heated mix and a solids mix. 
______________________________________ 
Percent 
Material Trade Name Dry Weight 
______________________________________ 
HEATED MIX FORMULATION 
Hydrocarbon Resin 
Picco 6100 10 
Petroleum Wax Altafin 125/130 
10 
Vegetable Wax Carnauba 23 
Ester Wax Hoechst V 4 
Oil Penreco 2251 
5 
Antioxidant Irganox 1076 
1 
Plasticizer Benzoflex 988 
3 
SOLIDS MIX FORMULATION 
Magnetic Pigment 
Oxide MO-8029 
36 
Inorganic Filler 
Gamma Sperse 
4 
Wetting Agent Soya Lecithin 
1.5 
Flow Enhancer Antiterra U 1.5 
______________________________________ 
The ingredients of the heated mix, along with 80 grams (wet weight) of 
Lacolene solvent, are stirred and heated to approximately 80 degrees C. 
for about 10 minutes to enable the waxes to be melted and to be dispersed 
readily throughout the solvent based solution. This 80 degrees C. mixture 
is then placed into dispersion equipment such as a ball mill, a shot mill, 
an attritor or a sand mill along with the ingredients of the solids mix 
and along with 21 grams of a five percent solution of polyvinyl 
pyrrolidone in N-Propanol. The latter solution is made up of one gram of 
polyvinyl pyrrolidone, which added to the combined ingredients of the 
heated mix and of the solids mix totals 100 grams, and 20 grams of 
N-Propanol alcohol. The coating formulation is maintained at a temperature 
of approximately 55 degrees C. while being dispersed to insure proper 
mixture of the pigment and wetting thereof. 
The substrate or base 22, which may be 40 gauge capacitor tissue, 
manufactured by Schweitzer, or 35 gauge polyester film, 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 a Meyer rod or 
like wire-wound doctor bar set up on a typical solvent coating machine to 
provide the coating weight of between 7.7 and 13.5 grams per square meter. 
The coating vessel or apparatus along with the transfer lines and the 
Meyer rod are maintained at a temperature of approximately 50 degrees C. 
to provide a coating viscosity sufficiently low to enable pumping of the 
material. The coating is made up of approximately 50% solid material and 
is maintained at the temperature and viscosity throughout the coating 
process. After the coating is applied to the substrate, the web of ribbon 
is passed through a dryer at the elevated temperature in the range between 
93 and 150 degrees C. for approximately five to ten seconds to insure good 
adherence of the coating 24 onto the substrate 22 in making the transfer 
ribbon 20. The coating is applied by the Meyer rod to a thickness of five 
to fifteen microns. 
EXAMPLE II 
Example II describes the method of coating the substrate 22 to a coating 
weight in the range between 7.7 and 13.5 grams per square meter, and 
utilizing a heat sensitive transfer layer consisting of three basic 
mixtures, namely, a binder mix, a solids mix and a wax mix. A binder mix 
based on a 100 gram weight of raw coating, includes the following 
ingredients in the mixture. 
______________________________________ 
Percent 
Material Trade Name Dry Weight 
______________________________________ 
BINDER MIX FORMULATION 
Hydrocarbon resin 
Picco 6100 10 
Polyethylene resin 
AC-617 5 
Hydrocarbon oil 
Penreco 2251 
7 
SOLIDS MIX FORMULATION 
Magnetic pigment 
Oxide MO-8029 
39 
Inorganic filler 
Gamma Sperse 
4 
Wetting agent Soya Lecithin 
1.5 
Flow Enhancer Antiterra U 1.5 
WAX MIX FORMULATION 
Acid wax Hoechst S 28 
Ester wax Hoechst V 1.5 
Vegetable wax Carnauba 1.5 
______________________________________ 
The binder mix is formulated by adding the hydrocarbon resin and the 
polyethylene resin as a mixture into solution. The solids are added to the 
solution and solubilized by mechanically mixing the ingredients while 
heating the mixture to approximately 80 degrees C. and holding this 
temperature for approximately ten minutes. The binder formulation is then 
allowed to cool to approximately 55 degrees C. 
The binder mix and the solids mix are processed through a dispersion 
operation by use of a ball mill, a shot mill, an attritor or a sand mill 
along with 21 grams of the five percent solution of polyvinyl pyrrolidone 
in N-Propanol. The one gram of polyvinyl pyrrolidone, when added to the 
ingredients of the binder mix, of the solids mix and of the wax mix totals 
100 grams. The mixture of binder mix and solids mix is ground for a period 
of five minutes to reduce the pigment agglomerates and to ensure good 
wetting of the pigment. 
The wax mix formulation is added to and ground by the dispersion equipment 
to reduce the particle size and to cause dispersal of the wax particles 
throughout the coating. The mechanical action of the grinding process 
causes the temperature of the solution to be maintained at approximately 
55 degrees C. during the grinding operation. 
The finished solution or coating 24 is then applied to the substrate 22 in 
the manner as explained above and the setting or drying procedure is the 
last step of producing the coated ribbon 20. The setting or drying 
procedure consists of drying the coating 24 on the base 22 at a 
temperature in the range between 93 and 150 degrees C. for a period of 5 
to 10 seconds. 
EXAMPLE III 
This example is a composition of the heat sensitive transfer layer or 
coating consisting of two basic mixtures, namely, a pigment mix and a hot 
wax mix. The pigment mix includes the following ingredients: 
______________________________________ 
Percent 
Material Trade Name Dry Weight 
______________________________________ 
PIGMENT MIX FORMULATION 
Magnetic Pigment 
MO-4232 38 
Inorganic Filler 
Gamma Sperse 
4 
Hydrocarbon Oil 
Penreco 2251 
4 
Wetting Agent Soya Lecithin 
1 
Flow Enhancer Antiterra U 1 
HEATED MIX FORMULATION 
Vinyl Resin Elvax 210 3 
Polyethylene Resin 
AC-8 5 
Acid Wax Hoechst S 19 
Vegetable Wax Carnauba 7 
Amide Wax Glyconol 3 
Petroleum Wax ALOF 0604 14 
Antioxidant Irganox 1076 
1 
______________________________________ 
Picco 6100 is a low molecular weight, aromatic, non-polar, thermoplastic 
resin produced from petroleum derived monomers. Penreco 2251 is an acid 
treated, oil-like, distillate of petroleum hydrocarbons selected from the 
group having boiling points of 375-500 degrees F. 
Initially, the ingredients of the pigment mix are placed in the dispersal 
unit along with 100 grams of Isopropanol solvent to thorougly wet out the 
pigment. The resin, wax and antioxidant ingredients of the hot wax or 
heated mix are combined and placed in an oven set at 150 degrees C. and 
heated for a period of 30 minutes. While the hot wax or heated mix is 
still being heated and at least maintained at a temperature at 
approximately 120 degrees C., the pigment mix is slowly added at a 
constant rate to the hot wax mix so as not to cool the wax mix below 93 
degrees C. The 120 degrees C. temperature of the mixture causes the 
Isopropanol solvent to evaporate quickly and leaves only the solids of the 
pigment mix dispersed in the hot wax mix. The coating assumes a gel-like 
characteristic and is somewhat thixotropic so as to be fluid in form when 
subjected to shaking motion. It should be noted that the solvents and 
alcohols used in mixing the ingredients into solution are generally 
evaporated at a temperature of 95- 100 degrees C. 
The coating 24 is applied to the substrate 22 by means of the Meyer bar on 
a hot melt coater to the coating weight of between 7.7 and 13.5 grams per 
square meter. In this application, the coating vessel, the transfer lines, 
and the Meyer bar are maintained at a temperature of approximately 120 
degrees C. to keep the viscosity as low as possible. It is noted that the 
web is heated also to provide heat to the coating between the pick-up roll 
and the nip between the surfaces to insure maximum fluidity at the Meyer 
bar. The substrate material and the drying procedure are the same as in 
the previous examples. 
While the above examples provide the best modes for teaching and carrying 
out the invention and provide the highest quality print for the utilized 
technique, there are alternative methods of formulating at thermal 
transfer ribbon by incorporating portions of each example. One alternate 
method uses the binder mix of Example II and melting the wax, as described 
in Example I, and thereby formulating a hybrid coating. Another method 
uses the heated mix of Example I and, instead of melting the wax into the 
mix, grinding the waxes into a functional particle size as done in Example 
II. A third method involves evaporating the solvent from the mixture in 
Example I or II and coating the thixotropic mixture by means of the hot 
melt operation. 
The availability of the various ingredients used in the present invention 
is provided by the following list of companies. 
Magnetic Pigment--Pfizer Inc. 
Inorganic Filler--Georgia Marble Co. 
Wetting Agent--Rohm and Haas Co. 
Flow Enhancer--Byk Mallinckrodt 
Aliphatic Solvent--Ashland Chemical Co. 
Hydrocarbon Oil--Penn. Refining Co. 
Alcohol--Ashland Chemical Co. 
Hydrocarbon Resin--Hercules Inc. 
Polyethylene Resin--Allied Chemical Corp. 
Vinyl Resin--DuPont De Nemours & Co. 
Petroleum Wax--Dura Commodities Corp. 
Vegetable Wax--International Wax Inc. 
Ester Wax--American Hoechst Corp. 
Antioxidant--Ciba-Geigy Ltd. 
Plasticizer--Velsicol Chemical Corp. 
Acid Wax--American Hoechst Corp. 
Amide Wax--Glyco Chemicals Inc. 
It should be noted that while the 35 or 40 gauge substrate is about 9-10 
microns thick, a coating thickness of about 8-12 microns is preferred in 
the practice of the invention. 
It is thus seen that herein shown and described is a ribbon for use in 
thermal printing operations which includes a thermal responsive magnetic 
coating on one surface thereof. The coated ribbon enables transfer of 
coating material onto documents or like record media during the printing 
operation to form characters thereon in an encoded nature, permitting 
machine reading of the characters. 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 modifications not departing from the spirit and scope of 
the invention hereof are to be construed in accordance with the following 
claims.