U.S. patent number 3,663,278 [Application Number 05/093,800] was granted by the patent office on 1972-05-16 for thermal transfer medium for producing scratch and smudge resistant marks.
This patent grant is currently assigned to The National Cash Register Company. Invention is credited to James H. Blose, William F. Pinell, Shashikant G. Talvalkar.
United States Patent |
3,663,278 |
Blose , et al. |
May 16, 1972 |
THERMAL TRANSFER MEDIUM FOR PRODUCING SCRATCH AND SMUDGE RESISTANT
MARKS
Abstract
A thermal transfer medium comprising a base having a
transferable coating composition thereon. The coating composition
comprises about 3 to 40 percent by weight of a cellulosic polymer;
about 15 to 70 percent by weight of a thermoplastic
aminotriazine-sulfonamidealdehyde resin; about 3 to 40 percent by
weight of a plasticizer; and about 1 to 45 percent by weight of a
sensible material.
Inventors: |
Blose; James H. (Xenia, OH),
Pinell; William F. (Lebanon, OH), Talvalkar; Shashikant
G. (Dayton, OH) |
Assignee: |
The National Cash Register
Company (Dayton, OH)
|
Family
ID: |
22240801 |
Appl.
No.: |
05/093,800 |
Filed: |
November 30, 1970 |
Current U.S.
Class: |
428/480; 427/146;
428/535; 524/33; 524/42; 524/44; 428/530; 428/900; 524/39;
524/43 |
Current CPC
Class: |
C08L
61/30 (20130101); B41M 5/10 (20130101); B41J
31/00 (20130101); Y10T 428/31982 (20150401); Y10T
428/31786 (20150401); Y10T 428/31964 (20150401); Y10S
428/90 (20130101) |
Current International
Class: |
B41J
31/00 (20060101); B41M 5/10 (20060101); C08L
61/00 (20060101); C08L 61/30 (20060101); B41m
005/10 () |
Field of
Search: |
;117/36.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Katz; Murray
Claims
It is claimed:
1. A thermal transfer medium comprising a base having a
transferable coating composition thereon said coating composition
comprising about 3 to 40 percent by weight of a cellulosic polymer;
about 15 to 70 percent by weight of a thermoplastic
aminotriazine-sulfonamide-aldehyde resin, said resin comprising the
condensation product of at least one aldehyde selected from the
group consisting of formaldehyde and paraformaldehyde, at least one
aromatic monosulfonamide having two reactive amide hydrogens where
the sulfonamido group is attached directly to the aromatic nucleus
through the sulfur atom, and at least one aminotriazine having at
least two amino groups, the amount of said aminotriazine being
between about 17 and 50 mole percent of said monosulfonamide and
the total amount of said aldehyde constituent being at least in
excess of the total amount of said sulfonamide and aminotriazine
constituents on a molar basis; about 3 to 40 percent by weight of a
plasticizer; and about 1 to 45 percent by weight of a sensible
material.
2. The transfer medium of claim 1 wherein the cellulosic polymer
comprises cellulose acetate butyrate and is present in the coating
composition in an amount of about 15 to 25 percent by weight.
3. The transfer medium of claim 1 wherein the aminotriazine
component of the thermoplastic resin is melamine and said resin is
present in the coating composition in an amount of about 50 to 65
percent by weight.
4. The transfer medium of claim 1 wherein the plasticizer is
present in the coating composition in an amount of about 15 to 25
percent by weight.
5. The transfer medium of claim 1 wherein the plasticizer is
N-ethyl-p-toluenesulfonamide.
6. The transfer medium of claim 1 wherein said sensible material
comprises a green dye or pigment.
7. The transfer medium of claim 1 wherein said sensible material
comprises a red dye or pigment.
8. The transfer medium of claim 1 wherein said sensible material
comprises a black dye or pigment.
9. The transfer medium of claim 1 wherein said sensible material
comprises a magnetic metal or oxide thereof.
10. The transfer medium of claim 1 wherein said sensible material
is invisible to the naked eye under ordinary light.
11. The transfer medium of claim 1 wherein the sensible material is
present in the coating composition in an amount of about 2 to 20
percent by weight.
12. The transfer medium of claim 1 wherein said base is a thin
material.
13. The transfer medium of claim 12 wherein said base is a
polymeric material.
14. The transfer medium of claim 13 wherein said base is a film of
polyethylene terephthalate.
15. The transfer medium of claim 12 wherein said base is a paper
tissue.
Description
BACKGROUND OF THE INVENTION
This invention relates to thermal transfer media and to a process
for making the same. More particularly, this invention relates to
thermal transfer media, having transferable coating compositions
thereon, which are suitable for applications requiring transfer of
the coating composition from the transfer medium to a recording
medium. Transfer pressure is applied by means of pressure and heat
such as the impact of heated type or pressure from other heated
marking instruments in selected areas, either to the back of a
transfer medium which has a transferable coating composition
thereon or to the back of a recording medium to cause break-away of
the coating composition from the transfer medium and adherence of
such broken-away coating composition to the recording medium.
Transfer media such as carbon paper and typewriter ribbons have, of
course, been known and used for many years. Lately, however, the
placing of various types of thermally printed marks on recording
media to be handled and sensed by data processing equipment has
become a matter of increasing interest and special thermal transfer
sheets and printed ribbons have been developed to meet the
requirements of such data processing equipment.
One of the greatest problems encountered with marks thermally
printed on recording media is the great tendency for the printed
marks to scratch or smudge. The marks thermally printed on the
recording medium usually become scratched or smudged when the
printed medium is passed through ordinary commercial transactions
and when the printed medium is passed through data processing
equipment. This problem of scratching and smudging is encountered
even with some of the most recently developed transfer media. When
this scratching or smudging occurs, the reliability with which the
true mark can be automatically sensed is severely impaired even
though the impairment may sometimes be comparatively slight by
visual standards.
The present invention provides a thermal transfer medium which is
capable of producing suitable thermally printed marks on a
recording medium which have sufficient resistance to scratching and
smudging when the printed medium is passed through ordinary
commercial transactions and when the printed medium is processed
through data processing equipment so that the printed marks do not
sustain any change sufficient to affect the accuracy of the sensing
operation.
The present invention provides thermal transfer media, having
colored transferable coating compositions thereon, which may be
used in the printing of colored code bars on recording media such
as paperboard marking tags used by merchandising institutions to
identify inventory. Such color-coded tags have resulted in a major
breakthrough in machine readable media technology. In a typical
system, white paperboard tags are printed with font which is
readable by humans and are encoded or printed with different
colored bars by a color-coded tag printer which are readable by an
optical scanning device known as a color-coded tag reader. The
colored printed bars may be separated thereby allowing the white
background of the paper to form a third colored bar. The tag itself
offers many business system advantages which include attachment
methods, base stock variety, information capacity and flexibility.
The color-coded tag serves as a medium to transfer data between the
color-coded tag printer, which encodes data contained in a source
document onto the tag, and the color-coded tag reader which enters
the color-coded data into the business system usually at the point
of sale. The color-coded tag reader utilizes optical scanning to
sense and distinguish the different colored bars which have been
encoded on the tag by the tag printer in a binary pattern and to
convey the encoded information contained in the bars to the
business system.
In a color-coded tag system as described above, it is very
important that the different colored bars which are encoded on the
tag have a high resistance to scratching and smudging so that the
information contained in the bars can be correctly read by the
optical scanning device of the color-coded tag reader.
The present invention also provides thermal transfer media, having
improved transferable coating compositions, which may be used in
the encoding or printing of paper records such as checks, bank
deposit slips, credit charge slips and the like with magnetic
symbols which can be recognized by electronic accounting equipment
or which may be used as one-time carbon ribbons or papers.
It will be readily apparent that the principles of the present
invention can be applied whether the thermal transfer medium is
designed to deposit marks suitable for sensing visually, by optical
means, by photo-electric means, by magnetic means, by
electroconductive means, or by any other means sensitive to a
special material in the coating.
PRIOR ART
The present invention comprises a transfer medium having a
transferable coating composition thereon. The coating composition
comprises a cellulosic polymer, an
aminotriazine-sulfonamide-formaldehyde resin, a plasticizer and a
sensible material.
The thermal transfer medium of the present invention produces
thermally encoded or printed marks on a recording medium which
possess excellent scratch and smudge resistant properties.
The most pertinent prior art is found in the following patents
which disclose transfer media which produce printed marks on
recording media by means of pressure such as the impact of type or
pressure from other marking instruments. U.S. Pat. No. 2,984,582
discloses a transfer medium having a porous, thermoplastic resin
layer containing a transferable ink. The ink is released by the
resin layer onto a recording medium without transfer of the resin
layer onto the recording medium. U.S. Pats. Nos. 2,671,734;
2,822,288; 3,337,361 and 3,340,086 disclose transfer media which
produce encoded or printed marks on a recording medium. None of
these patents disclose the thermal transfer medium having the
transferable coating composition of the present invention. U.S.
Pat. No. 3,062,676 discloses a transfer medium having a coating
composition which is formed of a plurality of coatings. The
coatings are transferred to a recording medium thereby producing
encoded or printed marks on the medium which possess good smudge
resistant properties. U.S. Pat. No. 3,087,832 discloses a transfer
medium having a coating composition which comprises a magnetic
pigment mixed in a silicone resin and a silicone rubber binder
system. The coating composition has a top coating of wax which aids
in the adherence of the magnetic transfer coating to a recording
medium upon transfer thereto. U.S. Pat. No. 3,375,125 discloses a
transfer medium having a coating composition which comprises ethyl
cellulose, a resin binder, mineral oil, a wax and a pigment. The
coating composition is transferred to a recording medium thereby
producing encoded or printed marks on the recording medium which
possess good smudge resistant properties.
The prior art does not disclose the novel thermal transfer medium
of the present invention which produces thermally encoded or
printed marks on a recording medium possessing excellent scratch
and smudge resistant properties.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a
thermal transfer medium comprising a base having a transferable
coating composition thereon, said coating composition comprising
about 3 to 40, preferably about 15 to 25, percent by weight of a
cellulosic polymer; about 15 to 70, preferably about 50 to 65,
percent by weight of a thermoplastic
aminotriazine-sulfonamide-aldehyde resin; about 3 to 40, preferably
about 15 to 25, percent by weight of a plasticizer; and about 1 to
45, preferably about 2 to 20, percent by weight of a sensible
material. The above percents by weight are based on the total
weight of the transferable coating composition.
In further accordance with the present invention, the thermal
transfer medium of the present invention is produced by a process
which comprises applying the above named components of the coating
composition to a suitable base by means of a volatile organic
solvent carrier. The solvented coating composition is spread
uniformly over the base and the volatile organic solvent carrier is
then allowed to evaporate thereby leaving a transferable coating
composition deposited on the base.
DETAILED DESCRIPTION OF THE INVENTION
The cellulosic polymer can be any of the well known polymers such
as cellulose acetate, cellulose acetate butyrate, cellulose acetate
propionate, cellulose methyl ether, cellulose ethyl ether,
cellulose nitrate and the like and mixtures thereof.
The thermoplastic aminotriazine-sulfonamide-aldehyde resin used in
the present invention is a co-condensation product of a cyclic
aminotriazine, an aromatic monosulfonamide and an aldehyde such as
formaldehyde. The thermoplastic resin should preferably be
completely condensed.
The thermoplastic aminotriazine-sulfonamide-aldehyde resin may be
prepared from an aromatic monosulfonamide having two reactive amide
hydrogens, a cyclic aminotriazine having at least two primary amino
groups and an aldehyde such as formaldehyde or paraformaldehyde. If
desired, either or both of the first-mentioned components may be
separated reacted with the aldehyde to form a thermoplastic
sulfonamide-aldehyde resin or a B-stage partially condensed
aminotriazine-aldehyde resin, respectively, before being
co-condensed. The aromatic sulfonamide may comprise toluene
sulfonamide, for example, ortho- or para-toluene sulfonamide or
mixtures thereof, benzene sulfonamides, or the alkyl derivatives of
such sulfonamides, and the like, in which the sulfonamido group is
attached directly to the aromatic nucleus through the sulfur
atom.
The cyclic aminotriazine compound may comprise a compound having at
least two amino groups as represented by the following formula:
wherein R is hydrogen, alkyl containing 1 to about 8 carbon atoms,
aryl, aralkyl, amino, and the like.
The following are typical aminotriazine compounds within the above
formula:
2,4-diamino-1,3,5-triazine
2-methyl-4,6-diamino-1,3,5-triazine
2(3-hydroxy butyl)-4,6-diamino-1,3,5-triazine
2-heptyl- 4,6-diamino- 1,3,5-triazine
2-phenyl- 4,6-diamino- 1,3,5-triazine
2-benzyl- 4,6-diamino-1,3,5-triazine
2,4,6-triamino-1,3,5-triazine (melamine)
In place of melamine as the aminotriazine compound, one can use
methyl melamine or other alkyl derivatives of melamine, that is,
n-alkyl melamines, such as the mono- or dialkyl derivatives where
the alkyl group may be methyl, ethyl, propyl, butyl, and the like,
up to about 8 carbon atoms.
Also, the B-state methylol aminotriazine resin can be modified by
forming the alkyl ether of the methylol aminotriazine. For example,
this can be done by taking an A-stage methylol aminotriazine, that
is, the tri-, tetra- or pentamethylol aminotriazine, and then
converting to the B-stage resin in the presence of an alkanol such
as methanol, ethanol, propanol, butanol, and similar alkanols
containing up to about eight carbon atoms. When using methanol, the
resin would be the mono- or dimethyl ether of tri-, tetra- or
pentamethylol aminotriazine, in partially condensed form. Also,
alkanol derivatives of the aminotriazine in which the alkyl group
contains more than about three carbon atoms may be formed during
the course of the co-condensation reaction by introducing the
aminotriazine in a solution of an alcohol such as butanol. It will
be noted that the aminotriazine reacts as an amide rather than as
an amine.
The relative quantities of the materials to be co-condensed are
critical only to the extent that sufficient aldehyde should be used
to produce a completely condensed product; if too large a quantity
of the aminotriazine is used, the final product will be a
thermosetting product, which is not desired; and if too small a
quantity of the aminotriazine is used, the softening point of the
product will differ only slightly from the softening point of the
sulfonamide-formaldehyde resin and may not have insolubility in the
desired solvents. Also, the amount of the sulfonamide is dependent
upon the number of primary amino groups in the aminotriazine. For
example, it is preferred to use about three times (on a molar
basis) as much of the sulfonamide as the aminotriazine when the
aminotriazine contains two amino groups, and about five times (on a
molar basis) as much sulfonamide when the aminotriazine contains
three amino groups. In other words, the aminotriazine or B-stage
aldehyde-aminotriazine resin is preferably from about 20 to 33 mol
percent of the amount of the monosulfonamide or the
aldehyde-monosulfonamide resin, although the former may be as great
as about 5 mol percent and as little as about 17 mol percent of the
latter.
Generally, when preparing the alkanol modified resin, it is
necessary to use additional quantities of formaldehyde over and
above that required for the alkanol modification so as to provide
for subsequent co-condensation with the sulfonamide-formaldehyde
resin. The B-stage aminotriazine-formaldehyde resin, that is, the
methylol aminotriazine, must have at least two methylol groups and
preferably three such groups in order to successfully carry out the
subsequent co-condensation with the sulfonamide resin.
The thermoplastic resin may be prepared using as reactants either
formaldehyde or its polymer, paraformaldehyde, which polymer has
the general formula
(CH.sub.2).sub.n .sup.. H.sub.2 O
where n is 6 or greater. This monomer and its polymer should be
distinguished from polyaldehydes such as glyoxal containing a
plurality of aldehyde groups in a stable molecule.
Typical modes of preparation of the thermoplastic
aminotriazine-sulfonamide-aldehyde resin used in the present
invention are found in U.S. Pat. No. 2,938,873 in Examples 1
through 25. These Examples are incorporated herein as a part of
this specification.
In a preferred embodiment, the thermoplastic
aminotriazine-sulfonamide-aldehyde resin is a co-condensation
product of a melamine, an aromatic sulfonamide and an aldehyde such
as formaldehyde. The thermoplastic resin should preferably be
completely condensed. The thermoplastic
melamine-sulfonamide-aldehyde resin may be prepared from an
aromatic mono-sulfonamide having two reactive hydrogens, that is,
two reactive amide hydrogens, a melamine or a melamine derivative
having at least two functional amide groups and formaldehyde or
paraformaldehyde. If desired, either or both of the first-mentioned
components may be separately reacted with formaldehyde to form a
thermoplastic sulfonamide-aldehyde resin or a B-stage partially
condensed melamine-aldehyde resin, respectively, before being
co-condensed. The aromatic sulfonamide may comprise a mixture of
ortho- and para-toluene sulfonamides, benzene sulfonamide or the
alkyl derivative thereof or a toluene sulfonamide wherein the
sulfonamido group is attached directly to the aromatic nucleus
through the sulfur atom.
The B-stage partially condensed melamine-aldehyde resin (methylol
melamine resin) is the water soluble, thermofusible reaction
product of melamine and formaldehyde or paraformaldehyde. In place
of melamine, one can use the methyl melamine or other alkyl
derivatives of melamine such as the mono- or dialkyl derivatives
where the alkyl group may be methyl, ethyl, propyl, butyl or the
like.
Also, the B-stage melamine-aldehyde resin can be modified by
forming the alkyl ether of the melamine-aldehyde resin. This can be
done by taking an A-stage melamine-aldehyde resin, that is, the
tri-, tetra- or pentamethylol melamine resin, and then converting
it to the B-stage resin in the presence of an alkanol such as
methanol, ethanol, propanol, butanol or the like. When using
methanol, the modified B-stage resin would be the mono-, di- or
trimethyl ether of tri-, tetra- or pentamethylol melamine in
partially condensed form.
The relative quantities of the materials to be co-condensed are
critical only to the extent that more than about 20 percent by
weight of the unmodified melamine-aldehyde B-stage resin in the
final product will produce a thermosetting product, which is not
desired, and, if too small a quantity of the melamine resin is
used, the softening point of the product will differ only slightly
from the softening point of the aromatic sulfonamide-aldehyde
resin. In other words, the amount by weight of the
sulfonamide-aldehyde resin should be at least four times the amount
of the unmodified B-stage melamine-aldehyde resin. When the
unmodified melamine-aldehyde B-stage resin is employed, it is
preferred to use about 16 percent thereof based on the weight of
the final co-condensed resin, that is, about five times as much of
the sulfonamide-aldehyde resin as the unmodified B-stage
melamine-aldehyde resin. When the melamine derivatives or the
modified B-stage melamine resins are used, greater relative
quantities can be employed up to about 25 to 35 percent by weight
of the final product, that is, up to about 50 percent by weight of
the sulfonamide-aldehyde resin. Generally, when employing a
melamine derivative to form the B-stage partially condensed resin
or when preparing the alkanol modified melamine resin, it is
desirable to use greater quantities of the aldehyde so as to
provide additional methylol groups for subsequent co-condensation
with the sulfonamide-aldehyde resin. The B-stage melamine-aldehyde
resin, that is, the methylol melamine resin, must have at least two
methylol groups and preferably three or four such groups in order
to successfully carry out the subsequent co-condensation with the
sulfonamide resin.
The various melamine derivatives having at least two functional
amide groups, which are useful substitutes for melamine for the
purposes of the present invention, include all of such derivatives
mentioned in the foregoing discussion. Stated most simply, by way
of summary, they include alkyl melamines having preferably no more
than one alkyl substituted amido nitrogen and monohydric alkanol
modified methylol and alkyl methylol melamines.
The melamine-sulfonamide-aldehyde resin can be prepared using
either formaldehyde or its polymer, paraformaldehyde, as reactants.
This monomer and its polymer, wherein the same atoms are present in
the same proportion, should be distinguished from isomerides of
formaldehyde such diformaldehyde which contains a plurality of
aldehyde groups in a stable molecule.
Typical modes of preparation of the thermoplastic
melamine-sulfonamide-aldehyde resin used in the present invention
are found in U.S. Pat. No. 2,809,954, in Examples 1 through 15.
These Examples are incorporated herein as a part of this
specification.
The aminotriazine-sulfonamide-aldehyde resin has a higher softening
point than the well-known sulfonamide-aldehyde resins and has some
characteristics which are in no way similar to the completely
condensed aminotriazine-aldehyde resins and other characteristics
which are in no way similar to the thermoplastic
sulfonamide-aldehyde resins. The aminotriazine-sulfonamide-aldehyde
resin not only has a higher melting point than the
sulfonamide-aldehyde resins, but it will release solvents more
rapidly than such resins and does not exhibit cold flow at room
temperature as do the sulfonamide-aldehyde resins. On the other
hand, the aminotriazine-sulfonamide-aldehyde resin, unlike the
aminotriazine-aldehyde resin, is soluble in certain solvents and is
thermoplastic. The overall character of the
aminotriazine-sulfonamide-aldehyde resin makes it especially
suitable for the manufacture of pigments. For example, the
aminotriazine-sulfonamide-aldehyde resin can be highly colored and,
even though thermoplastic, can be readily ground to a finely
divided condition at temperatures below about 100.degree. C. Most
thermoplastic resins will either soften at the temperature
encountered during grinding or will tend to ball up or agglomerate,
even at temperatures below the softening point, probably due to
cold flow under the pressure of the grinding elements. The
aminotriazine-sulfonamide-aldehyde resin is brittle and friable
below its softening point and is not hornlike and tough as are most
thermoplastic resins. The aminotriazine-sulfonamide-aldehyde resin
is insoluble in many common vehicles and can therefore be suspended
in such vehicles without coalescence or agglomeration.
The plasticizer used in the present invention is employed to modify
the properties of the thermoplastic polymeric material and the
aminotriazine-sulfonamide-aldehyde resin to produce a flexible and
non-brittle thermal transfer medium. Suitable plasticizers include
adipic acid esters, phthalic acid esters, ricinoleic acid esters,
sebacic acid esters, succinic acid esters, chlorinated diphenyls,
citrates, epoxides, glycerols, glycols, hydrocarbons, chlorinated
hydrocarbons, phosphates, toluenesulfonamides and the like and
mixtures thereof. The plasticizer should be compatible with the
thermoplastic polymeric material and preferably is a solid at room
temperature.
The sensible material used in the present invention can be any
material which is capable of being sensed visually, by optical
means, by photoelectric means, by magnetic means by
electroconductive means or by any other means sensitive to the
sensible material. The sensible material can be an inorganic or
organic material such as a coloring material, namely, a dye or a
pigment, a magnetic material or any other material capable of being
sensed and which is compatible with the coating composition.
Suitable sensible materials include phthalocyanine dyes such as
Monastral Green B (color index No. 74260), Monastral Green G (color
index No. 74260), Sherwood Green (color index No. 42000) and
Tropical Brilliant Green (color index No. 42040); fluorescent
rhodamine or xanthene dyes such as rhodamine B Extra (color index
No. 45170), rhodamine GDN Extra (color index No. 45160), xylene red
(color index No. 45100), rhodamine 5 G (color index No. 45105),
rhodamine G (color index No. 45150), and rhodamine 2B (color index
No. 45151); fluorescent naphthalimide dyes such as brilliant yellow
6G (color index No. 29000) which has the formula 4 amino 1,8
naphthal 2',4' dimethyl phenylimide, other fluorescent
naphthalimide dyes such as (4n-butyl-amino) 1,8 naphthal n-butyl
imide and 4 amino 1,8 naphthal p-xenyl imide; other dyes or
pigments such as malachite green (color index No. 42000); cadmium
primrose (color index No. 77199), chrome yellow (color index No.
77600), Ultramarine Blue (color index No. 77007), Phthalocyanine
Blue (color index No. 74160), Lake Red C (color index No. 15585),
Sodium Lithol Red (color index No. 15630), titanium dioxide and
zinc oxide; magnetic metal oxides such as iron oxide, cobalt oxide
and nickel oxide; finely divided metals and alloys such as bronze,
stainless steel, iron, cobalt, nickel and chrome; and miscellaneous
coloring materials such as carbon black, conductive carbon and
charcoal.
As an example of a sensible material which is not normally visible,
but can be detected, a small amount of a material such as
4-methyl-7-diethylamino coumarin will not color a coating
composition when it is exposed to ordinary light but will produce a
bright blue color when the coating composition is exposed to
ultraviolet light.
The sensible material can include any luminescent, fluorescent or
phosphorescent material, either organic or inorganic, or any
materials which are partially visible or substantially invisible,
in normal or ordinary light, and which become visible or emit
energy when exposed to light or energy differing in kind or wave
length from that emitted by the luminescent material. The term
luminescent material is intended to include and denote both
fluorescent materials, which are activated by energy of shorter
wave length and emit energy of longer wave length, and
phosphorescent materials which continue to emit light or energy
after excitation is discontinued.
The above-named sensible materials constitute only a fraction of
the many different sensible materials that can be used in the
present invention and are not to be construed as limiting the scope
of the suitable sensible materials that can be used in the present
invention. Any of the above-named sensible materials can be used
alone or in combination with each other or in combination with
other suitable sensible materials not specifically named above. The
sensible material need only be suitable for the sensing required,
have a high resistance to scratching and smudging when the coating
composition is transferred onto the recording medium and be
compatible with the coating composition.
The sensible material can be chosen so that the transferred coating
composition will reflect a certain amount of light within a
particular wave length. For example, a black sensible material can
be chosen so that the transferred coating composition has a
diffused reflectance of less than 15 percent of light between a
wave length of 600 and 1200 nanometers and a green sensible
material can be chosen so that the transferred coating composition
has a diffused reflectance of less than 15 percent of light between
a wave length of 600 and 750 nanometers, 50 percent of light
between a wave length of about 820 and 870 nanometers, and greater
than 80 percent of light between a wave length of 900 and 1200
nanometers. The wave length of light between 600 and 1200
nanometers is within the visible and the near infra-red spectrum.
The choosing of a sensible material for such optical properties is
useful in an optical sensing device.
The base to which the transferable coating composition is applied
can be a thin material such as a film, web, sheet, ribbon, fabric
or the like. The preferred base is a film of polyethylene
terephthalate, however, other bases can be used. For example,
cellulosic materials, paper, cellophane, nylon, rubber
hydrochloride, polyethylene, polypropylene and the like are
acceptable bases when used in the form of a film, web, sheet,
ribbon, fabric or the like. The base should have a thickness of
about 0.2 to 2, preferably of about 0.3 to 0.8, mils. The base
should be such that the transferable coating composition adheres to
the base in a proper manner prior to transfer of the coating
composition to the recording medium and the transferable coating
composition is released from the base in a proper manner upon
transfer. The base should be limited in thickness to permit a full
realization of the capability of the transferable coating
composition to deposit marks having sharp, clear edge definition on
a recording medium. The base should also possess uniform tensile
and other physical properties to insure uniform transfer of the
coating composition onto a recording medium.
At times it may be desirable to enhance the transfer of the
transferable coating composition from the base to the receiving
medium. This can be achieved by using a release coating composition
between the transferable coating composition and the base. The
release coating composition can be applied to the base prior to the
application of the transferable coating composition. A number of
release coating compositions can be used. Among these coating
compositions are waxes and waxes containing polymeric additives
such as polyvinyl alcohol and carboxy methyl cellulose.
The wax used in the present invention can be a wax having a melting
point ranging between about 140 to 220, preferably about 155 to
200, .degree.F. as determined by ASTM D-127. Suitable waxes include
natural waxes such as carnauba, montan and the like and mixtures
thereof; synthetic waxes such as hydrogenated, amide, chlorinated,
alkene or olefinic, miscellaneous and the like and mixtures
thereof; and petroleum waxes such as microcrystalline, paraffin and
the like and mixtures thereof.
The term wax, as used herein, defines a class of waxes which is
characterized by a particular degree of hardness as determined by a
needle penetration test ASTM D-1321. The needle penetration test
measures the depth to which a weighted needle penetrates a sample
of wax. In the needle penetration test, a wax sample is melted by
heating it to about 30.degree. F. above its melting point and is
then solidified by cooling to 77.degree. F. The hardness of the wax
is measured with a penetrometer whereby a standard needle, under a
load of 100 grams, is applied to the wax sample for 5 seconds. The
depth to which the needle penetrates the wax during the 5 second
time interval is measured in tenths of a millimeter. If the needle
penetrates the wax to a depth of 0.2 millimeter, the hardness
rating of the wax is 2. If the needle penetrates the wax to a depth
of 0.8 millimeter, the rating of the wax is 8, and so forth. The
waxes which can be used according to this invention are those which
have a rating from about 0.5 to 10, preferably about 1 to 9. The
wax can be an animal, mineral, petroleum, synthetic or vegetable
wax or a mixture thereof so long as the wax is stable, can be
meltable, emulsifiable or solvent dispersible, has the required
degree of hardness and has the above indicated melting point range.
The release coating can be applied to the base by roll coating,
knife coating or by a similar means from a hot melt, emulsion or
solvent dispersion of the wax.
The transferable coating composition containing the sensible
material can be applied to the base in the following manner to
produce the transfer medium of the present invention.
The aminotriazine-sulfonamide-aldehyde resin and the sensible
material can be added to the volatile organic solvent with constant
stirring until a composition having a uniform consistency is
obtained. The cellulosic polymer and the plasticizer can then be
added to the volatile organic solvent with constant stirring until
a composition having a uniform consistency is obtained. About 500
to 100, preferably about 300 to 150, parts of organic solvent is
usually used per 100 parts of cellulosic polymer,
aminotriazine-sulfonamide-aldehyde resin, plasticizer and sensible
material used. However, the ratio of solvent to the aforementioned
components is usually not particularly critical. The
aminotriazine-sulfonamide-aldehyde resin can be soluble, partially
soluble or insoluble in the volatile organic solvent so that the
aminotriazine-sulfonamide-aldehyde resin is dissolved or dispersed
in the solvented coating composition. The solvented coating
composition can then be milled until a uniform composition is
obtained. The sensible material can be added separately to the
coating composition or the sensible material can be mixed,
dispersed or dissolved in the aminotriazine-sulfonamide-aldehyde
resin and then added to the coating composition. The sensible
material can be added to the aminotriazine-sulfonamide-aldehyde
resin during its production or after its production. Specific
details for adding the sensible material to the resin are contained
in U.S. Pat. No. 2,809,954 in Examples 6 through 15 and in U.S.
Pat. No. 2,938,873 in Examples 9 through 25. These Examples are
incorporated herein as a part of this specification.
The transferable coating composition can be applied to the base by
roll coating, knife coating or by a similar means. The volatile
organic solvent can be evaporated at ambient temperature or can be
evaporated by the application of gentle heat thereby leaving a
transferable coating composition having a thickness of about 0.1 to
0.4, preferably about 0.15 to 0.3, mils deposited on the base.
Suitable volatile organic solvent carriers for the coating
composition include aliphatic and aromatic hydrocarbon solvents
such as mineral spirits, naphtha, xylene, toluene and mixtures
thereof. Other suitable organic solvents include isopropyl alcohol,
isobutyl alcohol, 2-heptanol, isoamyl acetate, ethyl amyl ketone,
diisobutyl ketone, carbon tetrachloride, carbon disulfide, methyl
alcohol, ethyl alcohol, ethyl acetate, butyl acetate, acetone,
methyl isobutyl ketone, methyl cellosolve, butyl cellosolve,
methylene chloride, trichlorethylene and the like and mixtures
thereof. The thermoplastic polymeric material and the plasticizer
should be soluble or at least partially soluble in the volatile
organic solvent so that there is a co-mingling of the thermoplastic
polymeric material and the plasticizer. One of the above suggested
solvents or a mixture thereof can be selected with this criteria in
mind.
The above process for producing the transfer medium of the present
invention is only illustrative and can be varied within reasonable
limits to produce the transfer medium of the present invention.
PREFERRED EMBODIMENTS
The following Examples illustrate the present invention and modes
of carrying out the invention.
EXAMPLE 1
A typical thermoplastic aminotriazine-sulfonamide-aldehyde resin is
prepared in the following manner. 360 parts by weight of a mixture
of ortho- and para-toluene sulfonamide-formaldehyde resins are
melted at a temperature of 60.degree. to 70.degree. C. and are then
heated to a temperature of 125.degree. C. At this temperature, 78.4
parts by weight of B-stage unmodified melamine-formaldehyde resin
are added and dissolved therein and heating is continued. The
reaction mixture becomes clear at a temperature of about
150.degree. C. and heating is continued up to a temperature of
170.degree. C. and held there for about 10 minutes. Upon cooling,
the co-condensed resin begins to solidify at a temperature of about
115.degree. C. The completely condensed product is a clear
water-white resin which, below a temperature of about 100.degree.
C., is brittle, friable and is easily ground in a micropulverizer
or by wet ball milling into a finely divided powder having a
particle size of about 4 microns. The completely condensed resin
has a softening point at a temperature of about 115.degree. C.
Thermoplastic aminotriazine-sulfonamide-aldehyde resins having
substantially the same physical properties as the above prepared
resin are prepared in accordance with Examples 2 through 6 of U.S.
Pat. No. 2,809,954 and Examples 2 through 9 of U.S. Pat. No.
2,938,873. These Examples are incorporated herein as a part of this
specification.
A sensible material is incorporated in any of the foregoing clear
resins having substantially the same physical properties when the
reaction mixture reaches a temperature of between 150.degree. and
160.degree. C. while the reaction mixture is heated up to a
temperature of between 170.degree. to 180.degree. C. or by melting
the finished resin at a temperature between 130.degree. to
160.degree. C. and adding the sensible material to the melt,
solidifying and regrinding the resin. Where applicable, the
solidified resin and the sensible material may be dissolved in a
ketone or an ester solvent, the solvent evaporated and the
composition of sensible material and resin then ground to a fine
powder. About 1 to 50 parts by weight of the sensible material is
added to 100 parts by weight of the resin depending upon the
properties desired in the coating composition of the transfer
medium.
EXAMPLE 2
A green transfer medium, that is, a printing ribbon, was prepared
in the following manner using the solvented coating composition
described below:
Solvented Coating Composition
Component Parts By Weight
__________________________________________________________________________
Cellulose Acetate Butyrate-One-Half Second Viscosity Grade (1) 4.5
Melamine-Sulfonamide-Formaldehyde Resin Containing a Fluorescent
Green Dye and a Phthalocyanine Green Toner-- A-18 (2) 18.4
N-ethyl-p-toluenesulfonamide (3) 6.1 Monastral Green B
phthalocyanine Polychloro Copper Toner- Color Index No. 74260 (4)
1.0 Methyl Ethyl Ketone 70.0 Total: 100.0
__________________________________________________________________________
The above solvented coating composition was prepared by mixing the
melamine-sulfonamide-formaldehyde resin containing the sensible
material and the methyl ethyl ketone in a 500 ml. Erlenmeyer flask
with constant stirring thereby forming a composition having a
uniform consistency. The cellulose acetate butyrate and the
plasticizer were then added to the composition with constant
stirring thereby forming a coating composition having a uniform
consistency.
The solvented coating composition was then coated onto 5 pound
Jupiter paper tissue (20 in. x 30 in. x 480 sheets) and was
uniformly spread over the tissue using a Meyer rod to a coverage of
about 18 milligrams of solvented coating composition per square
inch of tissue. Jupiter paper tissue is a trademark for a 100
percent sulfite, fine parchment type tissue marketed by the Peter
J. Schweitzer Division of Kimberly-Clark Corporation, Elizabeth,
New Jersey, U.S.A. The methyl ethyl ketone was allowed to evaporate
at room temperature thereby leaving a dried transferable coating
composition having a thickness of about 0.2 to 0.3 mil on the
tissue. The coated tissue was then cut into printing ribbons.
A green printing ribbon was then placed in a NCR Engineering Model
Thermal Printer manufactured by The National Cash Register Company,
Dayton, Ohio, U.S.A. The thermal printer printed a sequence of
green marks on white bond paper. The print head of the thermal
printer was operating at a temperature of about 250 to 300.degree.
C. and had a heated contact time with the transfer medium of about
10 milliseconds. The transferable coating composition was
transferred to the white bond paper at a temperature of about 250
to 300.degree. F.
The green marks printed on the white bond paper were tested for
resistance to scratching and smudging by subjecting them to a thumb
nail scratch and smudge test. In this test, a thumb nail was
applied to the marks under pressure and was passed over the marks
several times. The printed marks possessed excellent resistance to
scratching and smudging upon visual examination.
In another test for thermal printability, a green printing ribbon
was placed on white bond paper. A steel bar having a width of 1.5
inches and a thickness of 0.05 inch was heated to 300.degree. F.
and then applied by hand pressure to the backside of the transfer
medium. The heated steel bar produced excellent marks on the white
bond paper.
The green marks printed on the white bond paper were tested for
resistance to scratching and smudging in the same manner as
described above and the printed marks possessed excellent
resistance to scratching and smudging upon visual examination.
* * * * *