Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
.
The safety inks and documents disclosed herein are
improvements over those shown in the United States Patents to
Guertin No. 3,088,841 (granted 7 ~ay, 1963) and No. 3,400,003
(granted 3 September, 1968) both of which are assigned to the
assignee of the present application. Guertin U.S. Patent No.
3,088,841 discloses a printed document having adjacent background
areas printed in different inks of the same color. One of the
inks is bleachable and soluble in water and inso~uble in the
lower alcohols and lower ketones. The other ink is soluble only
in the lower alcohols and lower ketones and is insoluble in water
and unbleachable. Hence, the two areas react differently to
alteration attempts involving either bleaching or solution in
water or in the lower alcohols and lower ketones. However,
any such alteration attempt produces a color contrast between the
two areas, which makes the attempted alteration readily detect-
able visually.
Guertin U.S. Patent No. 3,400,003, shows a document
which is printed with two superimposed background patterns, of
different colors, each composed of fine lines or dots. One of
the patterns is printed in ink whose coloring matter contains a
component which is bleachable, and soluble in water and in the
lower alcohols and ketones. The other pattern is printed in an
ink which is nonbleachable and not soluble in water and the lower
alcohols and lower ketones. Again, any attempt to alter the
document by bleaching or solution produces a color contrast.
BRIEF SUMMARY OF THE INVENTION
. . . _ _
The present invention is an improvement on the
safety inks and documents described in the Guertin patents
mentioned above. According to khe present invention, the back-
ground, which may be either an even color or an array of elements
such as lines or dots, is printed in an ink whose coloring matter
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~3~4S6
includes a dye which is bleachable and soluble in water and the
lower alcohols and ketones, and a fluorescent pigment which is
not bleachable, insoluble in water, and no more than very slightly
soluble in the lower alcohols and ketones, but which is at least
partly removed by an attempted erasure.
A document in accordance with the present invention
may include two sets of background elements printed in adjacent
areas in the same color. Alternatively, the document may include
two superimposed sets of background elements printed in different
colors.
However, the present invention does not require more
than a single set of background elements, or a single even back-
ground color, printed in a single in}c.
DETAILED DESCRIPTION
This invention relates to safety papers, ie., printed
documents, such as negotiable instruments, which are adapted for
the insertion of names, amounts, etc., either by hand, by type-
writer or other mechanical devices and which are sensitive to
attempts to alter inserted names, amounts, etc. The invention
includes both inks designed to give the required sensitivity and
having the characteristics necessary for such documents, and the
documents printed with such inks. By sensitivity to attempted
alteration is meant that an attempt to alter the printed document
results in an observable change in the appearance of the document
so as to alert a person receiving it to the fact that the document
has been altered.
Documents of value are most commonly written upon in
ink. The inks which are commonly used to write on documents of
value may be classified either as conventional inks, ball point
pen inks, or transfer sheet inks. Conventional inks are water
solutions of either a dye, typically an aniline dye, or a ferrous
salt which oxidizes to a ferric salt after writing, or combina-
-2-
~39~S~i
tions of both a salt and a dye.
~ The techniques of eradication of conventional inks
were established many years ago. Where the dried ink was water
soluble, such techniques simply involved the use of water as a
solvent (so-called washable ink). Where the dried ink was not
water soluble, the eradication techniques employed some type of
bleaching reaction. The bleaching solutions (ink eradicators)
for such inks are commonly sold.
A ball point pen ink is typically relatively stiff
and heavy and may consist of one of the higher glycols as a
vehicle, with an aniline dye for coloring material. ~lany of the
ball point pen inks cannot be eradicated either by the use of
water as a solvent or by the bleaching method.
While the details of all processes which might eradi-
cate ball point pen inks are unknown, it has been determined that
all proces~es so far known involve the use, at some stage of the
process, of a solvent selected from the lower alcohols or lower
- ketones. By "lower" is meant that the number of carbon atoms in
the particular alcohol or ketone is not greater than eight.
There have been recognized in the past two general
techniques of eradication which may be classified as l'line"
eradication and "sheet" eradication. Line eradication involves
the application of eradicating solution only to the particular
line or lines to be eradicated. In sheet eradication, the
entire sheet or document is immersed in the solvent or other
agent used. The line eradication technique is the one most
frequently employed in connection with conventional inks. It has
been determined that the ball point pen inks require, in all the
known processes, the sheet eradication technique.
It is also known that time is very important in the
ball point ink eradication techniques. To be successful, the
eradication must be completed within a relatively short time,
31~394~i6
of the order of thirty seconds. If the eradication has not
been completed in that time, then the solvent may start to spread
the ball point ink into the paper, thereby frustratlng the
attempted eradication.
Transfer sheet ink is used herein as a generic term
to describe the materials employed on transfer sheets to produce
a mark on an underlying sheet when the overlying sheet is written
or typewritten upon. The term transfer sheet includes type-
writer ribbons, carbon paper, "carbonless" carbon paper and any
other sheet, usually employing a coated under surface, which is
sensitive to localized pressure on the top of the overlying
sheet to make a mark on the underlying sheet. The term transfer
sheet ink is intended to include those materials which are latent
in that there is no observable color on the sheet or on the
underlying sheet until after the writing is applied.
Most transfer sheet inks may be described as either
solvent types, in which the coloring matter is dissolved in
material analogous to those used in the ball point pen inks, or
wax types, in which the coloring material is carried by a wax
vehicle, whether in solution or by simply mixing it with the
wax vehicle.
Transfer sheet inks and the techniques for eradicating
them, are of many different types. Some such inks are water
soluble. Some are soluble in the lower alcohols or in the lower
ketones or both. Some are bleachable. Some can be removed only
by mechanical erasure.
The inks of the present invention produce an observable
indication that an attempt has been made to alter written material
on a document, whether that attempt was made by a solution tech-
nique, by bleaching, or by mechanical erasure.
Safety papers prepared in accordance with the inventionhave printed matter thereon, which is changed in color and in its
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1~39~56
fluorescent intensity by the techniques presently known for
eradicating ball point pen ink. Typically, the printed matter
so changed consists of a background of closely spaced fine lines,
which may appear in any suitable configuration of characters,
words, geometric figures, etc. The ink in which at least some of
the printed patterns of the background appear should be soluble
in organic solvents selected from the class having not more than
eight carbon atoms and consisting of the lower alcohols and
lower ketones. There are two principal reasons for so limiting
the class of organic solvents. One reason is that th~ alcohol
and ketones as defined above are the ones most available commer-
cially, and hence most likely to be used by a person attempting
to alter a document. Another reason is that the higher ketones
and alcohols do not act rapidly enou~h as solvents, and spread
the ink into the paper instead of carrying it away. Consequently,
a person seeking to alter such a document is frustrated if he
attempts to use any of the higher alcohols or ketones.
Where more than one ink is used, the two inks must
be compatible if a single impression printing process is to be
employed. At least one of the inks must include a coloring matter
component soluble in the lower alcohols and lower ketones, and a
fluorescent pigment which is insoluble in water and has only a
very low solubility in the lower ketones and lower alcohols.
The ink components may or may not be soluble in water,
as desired. Typically, it is desired that the ink components
which are soluble in the lower alcohols and lower ketones be also
sol~ble in water. However, in some cases, printed documents may
be exposed for long periods of time to the air in humid climates.
In those cases, it is essential that the ink components employed
should not be so water soluble that high humidity will make it
start to run and destroy the pattern.
VEHICLE
The vehicle is the one described in U.S. patent No.
-5-
~39456
3,400,003, which is suitable from the standpoint of being
miscible with the various coloring matters employed in inks
manufactured according to the invention and which is also
soluble in water and in the lower alcohols and ketones. This
vehicle consists essentially of about 20% glycerine, about 64~
sorbitol and about 16% water. These percentages are by weight.
The proportion of glycerine employed in this vehicle may vary
from about 10~ to about 30~. If the proportion of glycerine is
reduced below about 10%, tendencies to crystallize are observed.
If the proportion of glycerine is increased above about 30%,
~he consistency of the vehicle becomes too thin for proper opera-
tion on conventional printing presses. The relative proportions
of sorbitol and water should remain abou~ the same (i.e. about
80% by weight of the material other than glycerine should be
sorbitol and about 20% water).
Printing inks containing this vehicle perform satis-
factorily on the printing press and are stable during pr~nting
and after being applied to the paper by the printing press. The
resulting printed lines support writing by all the usual writing
media without noticeable "bleed" and "feather" of the written line.
Additionally, the resulting printed material is stable to handling
during use and does not tend to change in color and effectively
responds in the intended manner to fraudulent manipulation of the
written material to create a noticeable change in the appearance
of the document.
The documents printed with the inks and in accordance
with the techniques of the Guertin patents mentioned above depend
solely upon changes in color of the background elements to show
that an attempt has been made to alter the writing material placed
on the document. It has been discovered that in some cases, as
for example, where an alteration is carefully performed and new
writing is placed on the document in wide lines which cover the
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alteration, it may be difficult to observe the attempted altera-
tion by observing change in color alone.
COLORING ~ATTER
It is therefore now proposed to use a fluorescent
pigment in the ink, in such a manner that a document which has
been subject to an attempted alteration will show a change in
intensity of the fluorescence, in addition to the change in color
under normal light. The change may be either an increase or
decrease in fluorescent intensity in those areas where the
alteration technique has been applied. In either event, when
the document is viewed in ultraviolet light, the generally even
tone of the pattern of background elements will be interrupted,
in each location where an alteration has been attempted, by either
intensified fluorescence or lessened fluorescence, depending upon
the particular type of alteration technique which has been
employed. The pigment selected should be non-bleachable, insol-
uble in water, and no more than very sl7 ghtly soluble in the
lower alcohols and lower ketones. A substance is defined as
"very slightly soluble" by Hackh's Chemical Dictionary, if it
requires from 1,000 to 10,000 parts of solvent to dissolve one
part of the substance. A substance is defined by the same autho-
rity as "insoluble'l if it requires more than 10,000 parts of
solvent to dissolve one part of the substance.
If the technique employed has been one involving a
solution or bleaching, then a part of the solution sensitive dye
or bleaching sensitive dye will have been removed, but the fluo-
rescent pigment will not have been removed. Since the dye tends
to mask the pigment, there will be a resulting increase in fluo-
rescent intensity in any area where a solution or bleaching
technique has been applied. This intensified fluorescence will
be readily visible if the document in question is viewed under
an ultraviolet light.
3945q6
If a line eradication technique has been employed,
then the areas which were subjected to the eradicating solution
will present a contrast to the other areas of the background.
This contrast will be observable in visible light as a color
contrast and will also be observable in ultraviolet light as a
contrast between two areas of different ~luorescent intensity,
i.e., the eradicated areas will be brighter than the areas where
no eradicating solution has been used.
If a sheet eradicating technique has been employed,
then there will be no areas of contrast in the background
visible on the face of the document, either in natural light or
ultraviolet light. On the other hand, the entire background of
the document will be changed in color. This color change should
be readily noticeable under natural light. Under ultraviolet
light, the entire document will fluoresce more intensely than
would be the case if no eradication had been attempted.
The foregoing statements about the appearance of
documents subjected to sheet eradication techniques are applic-
able to documents where backgrounds are printed in a single ink.
~here the background is printed in different ink on different
areas, as in the Guertin U.S. patent No. 3,088,841, the sheet
eradication technique will bring out the color differences in
those areas and will readily appear as an observable color
contrast under natural light.
If an attempt is made to alter the writing on a
document by erasure, i.e., by mechanically removing the deposit
of ink left by the writing, then some of the fluorescent pigment
is also necessarily remov~d by.the same operation, so that the
fluorescence in the altered area is reduced~
Ultraviolet viewers are in common use by bank tellers,
cashiers, and the like, so that a person accepting such a document
can readily make a check of its validity by placing it under an
~3945~i
ultraviolet light. This test can confirm a suspicion that a
particular document has been altered, in those instances where a
visual inspec-tion gives only borderline results. Furthermore,
it can detect some alterations which are not observable by a
visual test.
EXAMPLE
The ink may consist essentially of the vehicle
described above and coloring matter including a fluorescent
pigment such as Resoform Fluorescent Yellow (Pigment Yellow
No. 101, C.I. #48052, GAF Corp.) which may be 70.6 by weight
of the coloring matter and a mixture of dyes including:
%of coloring matter by
weight
Acid Blue, C;I. #42755 6.0
Croceine Acid Red, E.I~ ~27290, 9.3
Tartrazine C Acid Yellow #23, C.I.
~19140 12.0
Fuschine S.B.P. Basic Violet ~14, C.I.
#42510 2.1
All of these dyes are soluble in water and soluble
; in lower alcohols and ketones.
The C.I. numbers above are Color Index numbers of
the American Association of Textile Chemists and Colorists,
P.O. Box 12215, Research Triangle Park, N.C. 27709. The Colour
Index containing these numbers is published by Society of Dyeists
and Colourists, P.O. Box 244, 82 Grattan Road, Bradford, Yorkshire,
England.
The particular pigment described above is not bleach-
able and is insoluble in water and in the lower alcohols and ketones.
* Trade Mark
",~ g_
