Note: Descriptions are shown in the official language in which they were submitted.
CA 02149946 2000-OS-04
29945
Fatent Application
for
HIDDEN ENTRY SYSTEM AND IMAGE-DEVELOPING DEVICE THEREFOR
by
John C.H. Chang
and
Donald Hoffmann
Field of the Invention
The present invention is directed to a hidden entry
system for maintaining information hidden until utilized
and a device used to reveal the hidden entry. More
CA 02149946 2000-OS-04
-. _', _ 2 _
particularly, this invention relates to documents having
a localized latent image which is developed to form a
visible image using a device which can be easily packaged
with such document.
Background of the Invention
Various methods have been proposed for preparation
of sweepstakes contest awards, lottery tickets,
promotional game cards, premium cards, and the like,
containing hidden entries, such as numerals, messages,
symbols, or the like, which can be revealed to the
recipient by various means.
For example, U.S. Patent N4. 4,726,608 to Walton
discloses use of an opaque coating over hidden indicia.
The image of the indicia is later made visible by
scratching off the opaque coating or by applying a
solvent to disperse the coating. This system has the
disadvantage of requiri,~ag ~.traneous solvent~.,_
U.S. Patent No. 5,344,191, entitled
"Hidden Entry System and Use Thereof" to John C.H. Chang
and Peter A. Walter issued September 6, 1994
discloses a heat sensitive, autogenous chromogenic hidden
system on sweepstakes documents or the like, and requires
application of heat to develop the latent image, such as
by use of friction resulting by scratching the latent
image with the human fingernail. Since the latent image
is heat sensitive, it can prematurely develop when the
document is utilized with a laser printer to provide
addressee information or the like on the sweepstakes
document.
Summary of the Invention
A hidden entry system including a device for
developing the latent image has now been discovered which
2~4994~
- - 3 -
can be used to provide and develop hidden indicia on a
document used, for example, in a contest or promotion,
such as sweepstakes contest awards, lottery tickets,
premium cards, promotional game cards, or the like, to
hide indicia without premature development of the hidden
indicia by heat from a laser printer or from
manufacturing, handling or storage.
The hidden entry system of the present invention
comprises a first substrate bearing~a localized latent
image, which is formed of an image-forming reactant, and
an image-developing device for developing the latent
image comprising a second substrate having a first
surface and a second surface, the first surface of the
second substrate bearing a chromogenic composition
comprising an image-developing co-reactant, the second
surface of the second substrate bearing a pressure-
sensitive adhesive.
The image-developing device is superposed on and
releasably attached to the first substrate while being
spaced apart from the localized latent image. The
expression "releasably attached" as used in this
application includes direct contact between the pressure-
sensitive adhesive and the first substrate, and indirect
attachment of the pressure-sensitive adhesive to the
first substrate by means of a release liner which is
permanently secured to the first substrate or a release
substance or film coated on the first substrate.
The image-forming reactant may be a chromogen or a
color developer. The image-developing co-reactant may
also be a chromogen or a color developer. A chromogen
and a color developer react together to form colored
images. Thus, when a chromogen is used as the image-
forming reactant, a color developer should be used as the
image-developing co-reactant. Similarly, when a color
- - 4 -
developer is used as the reactant, a chromogen should be
used as the image-developing co-reactant. Thus, as used
in the present application, the term "reactant" is used
to denote material forming the latent image, while the
term "co-reactant" is used to denote the material on the
image-developing device which reacts with the reactant to
convert the latent image to a visible image. However, as
indicated, a chromogen or color developer may be used
interchangeably, for reaction with one another to form
the visible image.
According to a preferred embodiment of the present
invention, the image-developing device for developing the
latent image in a hidden entry system comprises a
substrate having a first surface and a second surface,
the first surface of the substrate bearing a chromogenic
composition, the chromogenic composition comprises a
mixture of a wax and an image-developing co-reactant, the
image-developing co-reactant being a chromogen or a color
developer, the second surface of the substrate bearing a
pressure-sensitive adhesive. The substrate is configured
such that the device may be gripped by the pressure-
sensitive adhesive to rub the latent image with the
image-developing co-reactant, the latent image being
formed from a reactant capable of forming a visible image
upon contact with the image-developing co-reactant
chromogenic composition.
The pressure-sensitive adhesive of the image-
developing device of the present invention is "dual-
functional", since it serves to removably adhere the
image-developing device to the release coating on the
document, such as the sweepstakes award, and also serves
to adhere the image-developing device to the human finger
to enable one to grip the image-developing device while
- - 5 -
rubbing it across the latent image to form a visible
image.
Since the image-developing device containing the co-
reactant and latent image formed of the reactant are not
juxtaposed until use to develop a visible image, for
example, on a sweepstakes award, premature development of
the hidden indicia during manufacturing, handling and
storage is avoided.
According to another embodiment of the present
invention, chromogenic composition of the image-
developing device comprises a polar wax as the vehicle
for the chromogenic composition thereby providing
improved image-development. Surprisingly, it has been
discovered that polar waxes can be used as a vehicle for
color developers in the present hidden entry system,
while the Lewis base polyethylene glycol (Carbowax),
which has been used in prior hidden entry systems,
desensitizes color developers of the present invention.
According to still another embodiment of the present
invention, the chromogenic composition of the image-
developing device comprises a metallic powder which
assists in breaking the coating barrier between the color
developer and chromogen to promote color development.
According to still another embodiment of the present
invention, the image-developing device is formed in a
desired shape or configuration, such as a coin, tool,
toy, book, disc, logo, regular geometric shape, or the
like for the purpose of improving the commercial
attractiveness of the system or for improving the ability
to grip the image-developing device when rubbing it
across the latent image to form a visible image. For
example, by adding a gold metallic powder to the
chromogenic composition, an image-developing device in
the form of a gold coin can be provided.
2~~~~~~
- - 6 -
According to still another embodiment of the present
invention, a device for developing the latent image in a
hidden entry system is provided, which comprises a
substrate having a first surface and a second surface,
the first surface of the substrate bearing a chromogenic
composition comprising an image-developing co-reactant,
the image-developing co-reactant being a chromogen or a
color developer, the second surface of the substrate
bearing a pressure-sensitive adhesive, the substrate
being configured such that the device may be gripped by
the pressure-sensitive adhesive to rub the chromogenic
composition across a latent image formed from a reactant
capable of forming a visible image upon contact with the
image-developing co-reactant.
According to another embodiment of the present
invention, the image-developing device has a very slight
thickness, such what when it is applied to the document,
such as sweepstakes letter, it adds little thickness to
the document and enables the document to be processed by
computer printers as a multi-ply business form.
According to a still further embodiment of the
present invention, a method for developing a hidden entry
is provided which comprises providing a hidden entry
system comprising a first substrate having a first
surface bearing a localized latent image formed of an
image-forming reactant, which is either a chromogen or a
color developer, on a first portion of the first surface
and a localized release coating on a second portion of
the first surface of the first substrate,
the hidden entry system additionally comprising a device
which comprises a second substrate having a first surface
and a second surface, the first surface of the second
substrate bearing a chromogenic composition, the
chromogenic composition comprising a mixture of a wax
_ _ 7
and an image-developing co-reactant, the image-developing
co-reactant being a chromogen or a color developer
capable of reacting with the image-forming reactant, the
second surface of the second substrate bearing a
pressure-sensitive adhesive, the image-developing device
being in superposed relation to said first substrate such
that the release coating is in contact with the pressure
sensitive coating of the second substrate, separating the
device from the first substrate of the second surface.
The image-developing device is separated from the first
substrate to manually contact the chromogenic.composition
portion of the device with the localized latent image to
form a visible image from the latent image, the pressure-
sensitive adhesive providing an anchor for the manually
contacting.
The expression "gripped" as used in the present
application is in the sense that one can manually grasp
the image-developing device with one or more fingers, as
well as by placing one or more fingers on the pressure-
sensitive adhesive portion of image-developing device and
by applying radial pressure to the image-developing
device, move it transversely across the latent image
coating of the document with the chromogenic composition
in contact with the latent image such that a visible
image is formed. Thus, the expression "gripped" as used
in this application includes placing a single human
finger on the pressure-sensitive portion of the image-
developing device to adhesively engage the device and
apply pressure to the device while moving it in a
transverse direction to frictionally engage the latent
image with the chromogenic composition portion of the
image-developing device.
2~49~4~
_8_
As used in the present application, the term
"indicia" is used to include any number, letter or symbol
in a general sense.
Other advantages and salient features of the present
invention will become apparent from the following
detailed description, which, taken in conjunction with
the annexed drawings, discloses preferred embodiments of
the invention.
Brief Description of the Drawings
Referring now to the drawings which form a part of
this original disclosure:
Figure 1 is a front elevational view of a
sweepstakes document showing the image-developing device
attached adjacent the hidden entry area on the front face
of the document;
Figure 2A is an enlarged, diagrammatic cross-
sectional view taken on line 2-2 of Figure 1 showing
attachment of the image-developing device to the
sweepstakes document;
Figures 2B and 2C are modified versions of laminate
constructions of Figure 2A;
Figure 3 is a cross-sectional view of the image-
developing device of Figures 2A, 2B and 2C;
Figure 4 is a schematic view of the sweepstakes
document of Figure 1 using the image-developing device to
develop a portion of the hidden entry area;
Figure 5 is a front elevational view of the
sweepstakes document of Figure 4 having the previously
hidden image completely displayed to reveal the
participant's number; and
Figure 6 is a multi-ply sweepstakes form with an
image-developing device of the present invention.
2.~4~94~
_ _ 9 _
Detailed Description of the Invention
Referring to the drawings, Figure 1 illustrates a
hidden entry system in combination with document 10.
The term "document" as used herein is intended to
include any type of document or paper used to hide
indicia until it is desired to reveal such indicia,
including lottery tickets, sweepstakes, raffles, prizes
and awards.
In the embodiment illustrated in Figure 1, document
is a sweepstakes award having an information area 12.
A chromogenic compound or color developer is formed into
a colorless ink and printed to form, as combination 14,
numerals "1234", as latent image-forming indicia on
information area 12. Of course, any indicia, including
alphanumeric indicia, symbols or design indicia may be
imprinted in lieu of the numerals 14. Although color
developer may be printed to form the latent image, it is
generally preferred to produce the latent image from the
chromogenic compound.
The chromogenic compound in preferred embodiments is
colorless before reacting with the color developer..to
produce the colored image. Suitable chromogenic
compounds include diarylmethanes, triarylmethanes,
indolylphthalides, azaphthalides, fluorans, and
spiropyrans. Exemplary diarylmethanes include 4,4'-
bis(dimethylaminobenzhydrylbenzyl)ether, N-halophenyl
leuco auramine, and N-2,4,5-trichlorophenyl leuco
auramine. Examples of triarylmethanes include 3,3-bis(p-
dimethylaminophenyl)-6-dimethylaminophthalide and 3,3-
bis(p-dimethylaminophenyl)phthalide. Examples of
indolylphthalides include 3-(p-dimethylaminophenyl)-3-
(1,2-dimethylindole-3-yl)phthalide and 3-(p-
dimethylaminophenyl)-3-(2-methylindole-3-yl)phthalide.
Examples of azaphthalides include 3-(2-ethoxy-4-
CA 02149946 2000-OS-04
- to _
diethylaminophenyl)-3-(1-octyl-2-methylindole-3-yl)-4-
azaphthalide and 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-
ethyl-2-methylindole-3-yl)-4-azaphthalide. Examples of
fluorans include 2-dibenzylamino-6-diethylaminofluoran,
2-anilino-6-diethylaminofluoran, 3-methyl-2-anilino-6-
diethylaminofluoran, 2-anilino-3-methyl-6-(ethyl-iso-
pentylamino)fluoran, 2-anilino-3-methyl-6-dibutylamino-
fluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 3,6-
dimethoxyfluoran, and 7,7'-bis(3-diethylaminofluoran).
Examples of spiropyrans include 3-methylspiro-
dinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-
dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran,
and 3-methylnaphtho-(3-methoxybenzo)spiropyran. Other
suitable chromogenic compounds are disclosed in U.S.
Patent Nos. 3,821,010; 3,954,803; and 4,104,437 to
Vincent and Chang.,
The chromogen utilized to form the latent image may
be dissolved in a solvent, such as benzyl xylenes, diaryl
alkanes, monobutylbiphenyls, monoisopropylbiphenyls,
dibutylbiphenyls, di-isopropylbiphenyls,
monoisopropylnaphthalenes, di-isopropylnaphthalenes, and
hydrogenated terphenyls along with wax and oil for use in
the image-developing device, or the chromogen solution
may be printed on the document to form the latent image.
Likewise, the chromogen solution may be microencapsulated
for incorporation into the wax or printed on the document
to form the latent image.
Pressure-rupturable microcapsules useful in the
present invention may be formed in any suitable manner
conventionally employed. For example, capsules formed
from coacervation of gelatin, polycondensation of urea-
formaldehyde, interfacial cross-linking, or hydrolysis of
isoclyanatoamidine products may be used. Preferably, the
CA 02149946 2000-OS-04
- 11 -
microcapsules are formed by a microencapsulation process
described in U.S. Patent No. 4,317,743 to Chancy,
Attached to document 10 is latent image-developing
device 16 configured in the form of a coin.
Alternatively, device 16 may be formed in other shapes,
such as an automobile, boat or company logo, for example.
Figure 2 is an enlarged, sectional view of the
construction of image-developing device or coin 16 as
attached to document 10. The laminate construction 20
includes a top layer of chromogenic composition 22
comprising a color developer or chromogenic compound co-
reactant for the reactant forming latent image indicia
14. Although a chromogen or color developer may be
utilized in chromogenic composition 22, preferably,
chromogenic composition 22 utilizes a color developer.
Suitable color developers are electron acceptor
materials, such as Lewis acids. Preferred electron-
acceptor materials for inclusion in chromogenic
composition 22 are the Lewis acids conventionally used to
prepare carbonless copy papers. Preferred Lewis acids
include, for example, zincated alkylphenol-formaldehyde
novolac resins, zinc salts of alkylsalicylic acids,
polymeric zinc salycilates, and the like.
Preferably, the color developer of chromogenic
composition 22 is dispersed in a wax, which is preferably
a polar wax. Suitable polar waxes are those natural and
synthetic waxes characterized by the presence of
functional groups selected from the group consisting of
carboxyl, carbonyl, hydroxyl, ester, amide, amine,
heterocyclic groups and combinations thereof. Examples
of polar waxes include carnauba wax, rosin, modified
rosins, fatty acids, fatty acid derivatives, oxazoline
waxes, montan wax, montan wax derivatives, and the like.
CA 02149946 2000-OS-04
- 12 -
Polar waxes are disclosed, for example, in U.S.
Patent Nos. 4,139,218 and 4,336,067,
Chromogenic composition 22 may also include a
metallic powder which assists in breaking the coating
barrier to promote color development between the
chromogen and color developer, and may provide color and
texture to coin 16.
Any metallic powder can be used in the wax portion
of the image-developing device of the present invention,
including the finely divided colored pigments.
conventionally used in surface coatings, which provide
color and preferably a rough or coarse surface
characteristic to the surface of the image-developing
device contacting the latent image. Suitable pigments
include red pigments, such as the iron oxides, e.g.,
Indian red, Spanish red; gold powder, such as that formed
from a gold/bronze alloy; orange pigment, such as Chrome
orange (basic lead chromate); brown pigment, derived from
iron oxides; green pigment, such a chrome green (a
mixture of chrome yellow and Prussian blue), chromium
oxide; blue pigment, such as Prussian blue (ferric
ferrocyanide), ultramarine (fused soda and sulfur),
purple pigment, such as manganese phosphate; black
pigment, such as carbon black and black iron oxide. A
combination of one of the foregoing pigments and a coarse
material, such as pumice in powder form, or pumice powder
alone, may be added to the chromogenic composition
forming the outer surface of the image-developing device.
Suitable amounts of the pigment include from about 1 to
about 20 weight percent, preferably from about 3 to about
weight percent based on the chromogenic composition
containing wax.
CA 02149946 2000-OS-04
-.., - 13 -
Chromogenic composition 22 is supported by paper or
paper-like sheet 24 which is secured by pressure-
sensitive adhesive 26 to release liner 28, which, in
turn, is secured by permanent laminating or non-pressure
sensitive adhesive 30 to document 10. Suitable permanent
laminating adhesives include, for example, water-based
emulsions, such as ethylene-vinyl acetate co-polymer and
styrene-butadiene latex. Examples are Nacor 33- 6079*
commercially available from National Starch and Chemical
Company and Adhesive 3993-C commercially available from
H. B. Fuller Company. Likewise, hot-melt adhesives, such
as ethylene-vinyl acetate co-polymer adhesives may be
employed as permanent laminating adhesive 30, for
example, Nacor 34-2925*commercially available from
National Starch and Chemical Companx. Polyurethane may
also be used, such as Nacor 70-9860*, commercially
available from National Starch and Chemical Company.
Laminate construction 20 shown in Figure 2A
comprises a plurality of layers in superposed relation
and may be produced in any suitable manner. For example,
a color developer may be dissolved in a molten polar wax
or a blend of polar waxes. Metallic powder, such as a
gold powder, may be mixed into the wax as well. The hot
wax liquid composition is then coated to form a layer 22
on the upper surface of a paper or paper-like substrate
24 having pressure sensitive adhesive 26 and release
liner 28 previously affixed to the opposite side of
substrate 24. Suitable pressure-sensitive adhesives
include, for example, water-based emulsions, such as
synthetic acrylic polymer emulsions in water, including
Nacor 4551*commercially available f~.om National Starch
and Chemical Company, Flexcryl 1685*commercially
available from Air Products and Chemicals Inc., and 3-
40518-O1F commercially available from Swift Adhesives
*Trade-mark
CA 02149946 2000-OS-04
- 14 -
Division of Reichold Chemicals, Inc. Likewise, hot melt
adhesives may be employed as pressure-sensitive adhesive
26. For example, such adhesives may be compounded
mixtures of an elastomer such as styrene-isoprene
triblock co-polymer, a tackifier such as rosin esters or
terpenes, and a plasticizer such as low molecular weight
phthalate, benzoate esters, and petroleum hydrocarbon
oils. Examples are Durotak 4144*commercially available
from National Starch and Chemical Company and Swift 84441*
commercially available from Swift Adhesives Division of
Reichold Chemicals, Inc.
Release liner 28 may be any suitable form of release
liner. For example, release liner 28 may be a paper
substrate having a non-sticking surface on one side
formed of silicone-containing polymers, petroleum-based
waxes, carbamates of polyvinyl alcohol, or polyvinyl
ethers of alkyl alcohol.
The surface of release liner 28 opposite that in
contact with pressure sensitive adhesive 26 is then
coated with a permanent laminating or non-pressure
sensitive adhesive 30, and the resulting assembly is
affixed to document 10 to provide the assembly 20 shown
in Figure 2A.
Alternatively, laminate construction 20 in Figure 2A
may be formed by coating the hot wax liquid onto
substrate 24, then coating the reverse side of substrate
24 with pressure-sensitive adhesive 26 and thereafter
laminated with release liner 28. The assembly is die-cut
and affixed onto the document 10 with permanent adhesive
30.
According to another embodiment of the present
invention, laminate construction 20 of Figure 2A may be
formed by coating the hot melt chromogenic composition
onto the top surface of substrate 24. A pressure-
*Trade-mark
CA 02149946 2000-OS-04
- 15 -
sensitive adhesive is coated over the release coating of
a release liner stock. The opposite side of substrate 24
is then laminated with the pressure-sensitive adhesive
coated release liner stock to form an assembly. The
resulting assembly is die-cut into the desired size and
shape, such as a coin, tool, toy, disc, logo, or the
like. The shaped assembly is fastened to the document at
a designated area with permanent laminate adhesive to
provide the image-developing device 16.
As shown in Figure 2B, release liner 28 may be
eliminated and the wax and pressure-sensitive. adhesive
coated substrate 24 may be directly laminated onto
release surface 29 provided on document 10. Release
surface 29 may be formed directly on document 10 by a
printing of silicone oil, a coating of a W-curable
silicone-containing polymer, a coating of hard petroleum-
based wax, a coating of silicone-containing polymer,
carbamates of polyvinyl alcohol, polyvinyl ethers of
alkyl alcohol, a printing of silicone wax or may be
formed by a patch of plastic film adhered to document 10.
As shown in Figure 2C, the release surface 29 may be
eliminated by using as adhesive 26 a pressure-sensitive
adhesive that will easily release from the surface of
document 10, but will adhere sufficiently to human skin
to enable use of laminate construction 16 of Figure 3 to
rub and convert the latent image 14 into a visible image.
A suitable pressure sensitive adhesive having such
characteristics is, for example, a pressure-sensitive
adhesive including acrylate copolymer microspheres, such
as the adhesives disclosed in U.S. Patent No. 3,691,140
to Silver and U.S. Patent No. 3,857,731 to Merrill et
al. Also useful is the removable or repositional
water-based, pressure-sensitive adhesive known as Stik-
CA 02149946 2000-OS-04
- 16 -
Withit SW 101 J*, commercially available from Paper
Conversions, Inc. of Syracuse, New York, which has the
properties of low tack and clean removability. Other
useful adhesives having such characteristics are Aroset
2551-W-52*,Aroset 2532-W-50*,and Aroset 2556-W-54*
commerciall~r available from Ashland Chemical, Inc. and
Nacor 4536*from National Starch and Chemical Company.
As shown in Figure 1, the image-developing device 16
is in the shape of a coin, and since gold.powder has been
mixed into the polar wax composition, the congealed wax
layer 22 will provide device 16 with the appearance of a
gold coin.
Alternatively, layer 22 may comprise micro-
encapsulated chromogen dispersed in the wax medium, while
hidden entries 14 of Figure 1 are printed with an ink-
based color developer of the type previously described.
Likewise, the hidden entries may be printed with the
chromogenic compound dissolved in an organic vehicle,
such as dibutylbiphenyl, while layer 22 is formed by
dissolving the color developer in a solution of polar wax
in oil normally used in the microcapsules. Optionally,
the chromogen and color developer may be interchanged.
According to another embodiment of the present
invention, the wax may be eliminated from layer 22 by
coating the upper surface of substrate 24 with water-
based microcapsules containing chromogen, and the lower
surface of substrate 24 with pressure-sensitive adhesive
26 as shown in Figure 3. Since the microcapsular coating
on substrate 24 is colorless, printing in the form of
instructions, a special message, logo, symbol, solid
color, metallic printing or the like, may be printed on
substrate 24 either under the microcapsular coating or
over it.
*Trade-mark
- - 17 -
The microcapsules may be of any suitable size, for
example, and have an average diameter of between about 1
to about 20 microns, preferably, between about 3 to about
7 microns to avoid premature rupture. Likewise, a load
bearing agent such as starch may be added to the coating
to help prevent premature rupture of the microcapsules.
Pressure-sensitive adhesive 26 in combination with
release liner 28, or release coating 29, or use of an
easy release pressure-sensitive adhesive as in Figure 2C,
permits easy separation of coated sheet 24 from document
to provide image-developing device or coin. l6 as shown
in Figure 3, which comprises chromogenic composition
layer 22, sheet 24 and pressure-sensitive adhesive layer
26.
Pressure-sensitive adhesive 26 is "dual-functional"
in that it not only secures image-developing device or
coin 16 to the release liner adhered to document 10, as
shown in Figure 2A, but is used to secure coin 16 to the
user's finger when using coin 16 to develop the latent or
hidden image 14 of Figure 1.
Referring to Figure 4, coin 16 has been peeled apart , '
from document 10 leaving behind release liner or release
material 32 on document 10, and coin 16 is placed on a
fingertip such that the pressure-sensitive adhesive
secures or anchors coin 16 firmly to the user's
fingertip. Using repetitive strokes in a reciprocating
or oscillating motion while pressing and rubbing
chromogenic composition 22 of coin 16 across latent image
numbers 14 causes color developer in the chromogenic
composition of coin 16 to contact the chromogenic
compound comprising latent image numbers 14, and results
in reaction between the color developer and chromogen to
convert latent image 14, such as numeral 1, to visible
colored image 17 until all such numerals, 1, 2, 3 and 4
2~4~~~~~
- - 18 -
are converted to visible colored numerals 34 as shown in
Figure 5. The aware recipient then compares the visible
numerals in information area 12 with those in area 15 to
see if there is a match. If so, the recipient qualifies
to continue in the sweepstakes contest.
In the embodiment of Figure 1, information area 12
is positioned in the lower center of the front face of
the sweepstakes document with image-developing device 16
spaced apart from information area 12. It is to be
understood that information area 12 comprising hidden
images 14 and image-developing device 16 may be located
in any position or area on the document, and that
multiple localized coatings of latent images formed of
such chromogenic compositions may be present on the front
of the document and on both the front and back of the
document, as desired.
The amount of chromogen used in the hidden entry
system of the present invention is generally the amount
needed to react with the color developer or Lewis acid ,
and may be present in amount of, for example, from about
1 part by weight to about 30 parts by weight chromogen,
preferably, from about 5 parts by weight to about 20
parts by weight chromogen per 100 parts by weight Lewis
acid.
A suitable binder material is needed to adhere the
chromogen-containing pressure-rupturable microcapsules
onto the surface of document 10 or substrate 24 when wax
is omitted from layer 22. The amount of binder generally
used is about 10~ to about 50~ by weight, and preferably
about 15~ to about 35~ by weight, based on the total
weight of the solids of the coating composition.
Examples of useful binders include starch, hydroxyethyl
cellulose, methyl cellulose, carboxymethyl cellulose,
gelatin, casein, gum arabic, polyvinyl alcohol, styrene-
CA 02149946 2000-OS-04
- 19 -
malefic anhydride copolymers, ethylene-acrylic acid
copolymers, styrene-butadiene copolymers, acrylonitrile-
butadiene copolymers, vinyl acetate emulsions, ethylene-
vinyl acetate emulsions.
The microcapsular coating composition of the present
invention may optionally additionally contain a color
suppressant to prevent premature coloration. The color
suppressant must be so chosen that it will not inhibit or
adversely affect the color formation in the final
product. Examples are ammonium hydroxide, alkanolamines,
such as monoethanol amine, diethanolamine, N,,N-
dimethylethanolamine, and the like, condensates of amine-
formaldehyde, such as urea-formaldehyde, melamine-
formaldehyde, and the like. Suitable amounts of such
color suppressants include from about 0.1 to about 10,
preferably from about 0.5 to about 4 percent by weight
based on the total dry weight of the coating composition.
Other suitable color suppressants are disclosed, for
example, in U.S. Patent Nos. 4,010,292 and 4,170,483,
The microcapsular coating composition may be applied
to the substrate, for example, paper, plastic, or the
like, which forms the document by any suitable technique
as known in the art to provide a localized, spot or band
coating. In a preferred embodiment of the invention, the
chromogenic coating composition is prepared as a slurry
comprising the chromogen-containing pressure-rupturable
microcapsules. Any suitable method may be employed for
providing the latent image. A preferred method of
coating is by off-set gravure coating as disclosed in
U.S. Patent No. B1 4,425,386 to Chang. Alternative preferred
coating methods include flexographic, screen printing, nozzle
extrusion and ink jet printing.
2.~~9~4~
- - 20 -
An ultraviolet light absorbing compound may
incorporated into the pressure-rupturable microcapsules
along with the chromogenic compound when the pressure-
rupturable microcapsules are printed to form a latent
image on a document or incorporated in the coating on the
image-developing device. Surprisingly, it was found that
if prior to use, a document of the present invention,
such as a sweepstakes award letter, is left uncovered,
for example, near a window in an automobile or near a
window in a house, and the latent image area printed with
chromogen becomes exposed to natural light, such as from
sunlight or other source of ultraviolet light, the
chromogenic material becomes inactive and the hidden
entry function of the document is destroyed in a day or
so. However, it has been found that by incorporating an
ultraviolet light absorbing compound in the pressure-
rupturable microcapsules along with the chromogenic
compound, even after exposure to sunlight, the
chromogenic compound can react with the color developer
upon rupture of the microcapsules containing the
chromogenic compound.
Although an ultraviolet light absorbing compound has
been incorporated in microcapsules used in the pressure-
sensitive recording paper system disclosed in U.S. Patent
No. 3,554,781, such compound is used for a purpose
different from that of the present invention. In
particular, such recording paper system is concerned with
preserving the visible image after it is formed by
reaction of the chromogenic compound and color developer
on the record sheet, since such sheets are not normally
exposed to outside light, if at all, until after a
colored image has been formed. Prior to use, such
recording paper is stored in boxes or cabinets and is not
exposed to sunlight. In contrast, the latent image area
CA 02149946 2000-OS-04
- 21 -
' on the documents of the present invention may well be
exposed to daylight, since such document might be left by
an open window after the sweepstakes award letter is
received.
Any suitable ultraviolet light absorbing compound
may be encapsulated along with the chromogenic compound
of. the present invention. Preferred ultraviolet light
absorbing compounds for use in the present invention
include, for example, the substituted benzotriazoles
available from Ciba-Geigy under the tradename "Tinuvin",
such as Tinuvin P disclosed in U.S. Patents Nos.
3,004,896 and 3,189,615, having the general formula
2-(5'-methyl-2'-hydroxyphenyl)benzotriazole; Tinuvin 326,
which has the general formula 2-(5'-methyl-3'-tert-butyl-2'-
hydroxylphenyl)-5-chlorobenzotriazole; Tinuvin 327,
having the general formula 2-(3',5'-di-tert-butyl-2'-
hydroxyphenyl)-5-chlorobenzotriazole; Tinuvin 328, which
has the formula 2-(3',5'-di-tert-pentyl-2'-
hydroxyphenyl)benzotriazole, and Tinuvin 900, disclosed
in U.S. Patent No. 4,278,589, which is hereby
incorporated by reference, which has the formula 2-[2-
hydroxy-3,5-di(1,1-dimethylbenzyl)phenyl]-2-H-
benzotriazole.
The ultraviolet light absorbing compound is used in
any suitable amount, for example, from about 5 to about
150 weight percent, based upon the weight of the
chromogenic compound, with a preferred amount being from
about 20 to about 80 weight percent, based on the weight
of the chromogenic compound.
According to another embodiment of the present
invention, it has been found that hindered phenols
normally used as antioxidants to hinder thermally-induced
oxidation of polymers in coatings for high temperature
- 22 -
2~4~~4~
applications, for example, to prevent yellowing caused by
heat, act as stabilizers for the chromogen in the
capsules. The hindered phenols can be used in place of
the benzotriazole ultraviolet light absorbing compounds.
Surprisingly, it has been found that hindered phenols
stabilize chromogen in the microcapsules when exposed to
sunlight even at ambient temperatures.
Suitable hindered phenols include, but are not
limited to, for example, 2,6-di-tert-butyl-p-cresol;
4,4'-methylene bis(2,6-di-tert-butylphenol); 4-methyl-
2,6-bis(2'-hydroxy-3'-tert-butyl-5'-methylbenzyl)phenol;
the Irganox hindered phenols, such as Irganox.~129,
Irganox 245, Irganox 1010, Irganox 1076, Irganox 1035 and
Irganox Nm 1024 commercially available from Ciba-Geigy
Corporation. Such hindered phenols have the general
structural formula
O
HO- ~ - ( CH2 ) ZC- -R
n
..wherein R is an alkoxy, a substituted alkoxy,_or -NH-NH-
group and n is an integer from 1 to 4. For example, R is
C ( CH20- ) 4 when n = 4 , R i s -O-C18H3~ when n = 1, R i s -O-
( CHZ ) 2-S- ( CHZ ) Z-O- when n = 2 , and R i s -NH-NH- when n =
2.
Irganox 129 is 2,2'-ethylidene-bis(4,6-di-tert-
butylphenol); Irganox 245 is ethylene bis(oxyethylene)-
bis(3-tert-butyl-4-hydroxy-5-methylhydrocinnamate);
Irganox 1010, which is identified as tetrakis(methylene-
3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]-
methane; Irganox 1076 is octadecyi 3,5-di-tert-butyl-4-
219
- 23 -
hydroxyhydrocinnamate; Irganox 1035 has the general
formula
O O
HO- ~ II II
-( CHz ) zC0 ( CH2 ) 2-S-( CHZ ) ZOC ( CH2 ) 2- ~ -pH
while Irganox MD 1024 has the general formula
O
1
HO- ~ -CHZCHzCNH
2
Any hindered phenol useful as an antioxidant is
useful as a stabilizer for the chromogen in the capsules
of the present invention. The hindered phenol stabilizer
is used in any suitable amount, for example, from about 5
to about 150 weight percent, based upon the weight of the
chromogenic compound, with a preferred amount being from
about 20 to about 80 weight percent based on the weight
of the chromogenic compound. Surprisingly, it was found
that the hindered phenol can be used in place of a
benzotriazole and still provide effective stability for
the chromogen in the capsules.
When the present invention is used to provide
lottery tickets or sweepstakes awards, for example, the
latent image indicia of the hidden entry system of the
present invention will normally be a numerical sequence
on each ticket or form which varies from form to form
depending upon the number of winners in each category,
for example.
_ - 24 -
Referring now to Figure 6, form 110 comprises a
plurality of sweepstakes award forms 112, 114, 116
separated by perforated lines 118. Each individual form
has sequences of predetermined indicia printed thereon
with the latent images 122 of indicia on information area
124 formed from a color developer, in which at least a
portion of the forms have sequences of latent image
numbers which may differ or repeat from form to form or
ticket to ticket for comparison to visible numerals in
match area 130.
Each form is provided with image-developing device
128 having the laminate structure shown in Figure 2A for
coin 16, except that the chromogenic composition 22
comprises a coating of water-based, chromogen-containing
microcapsules and no wax matrix is used. Since the
capsular coating is colorless, it reveals instructional
printing 127 on the paper substrate of coin 128, which
instructs the user to "LIFT, STICR AND RUB" coin 128 over
the hidden entry in information area 124. Latent image
122 may be formed from, for example, either a color
producing chromogen or a color developer with the ~o-
reactant, respectively, being microencapsulated.
Coins 126 are sufficiently thin, that when attached
to forms 112, 114 and 116 they, too, can pass through a
computer printer. Thus, structure 20 including image-
developing device 16 as shown in Figure 2A has a cross-
sectional thickness, t, of from about 4 to about 20 mils,
preferably from about 6 to about 12 mils. Likewise,
structure 21 of Figure 2B has a thickness t' and
structure 23 of Figure 2C has a thickness of t" within
such range. Substrate 10 upon which structure 20 is
supported has the thickness of a normal paper substrate.
The forms are then separated and mailed or otherwise
distributed as desired.
21~9~~~
- 25 -
The invention will be further illustrated by the
following examples. It should be understood that the
examples are not intended to limit the scope of this
invention. Percentages are by weight unless otherwise
indicated.
Example 1
Three hundred grams of capsule slurry were formed
containing 4.5 grams of crystal violet lactone and 8.9
grams of polyvinyl alcohol. One hundred twenty grams of
Keestar starch particles (commercially available from
Ogilvie Mills, Inc.) were added to the slurry and the
total solids adjusted to 40% by the addition of 180 grams
of water. The resulting slurry was used to print latent
images.
A mixture of 90 grams of carnauba wax and 10 grams
of alkylphenol-formaldehyde novolac resin HRJ-2346 (from
Schenectady Chemicals, Inc.) was heated at about 100°C
until a clear solution was obtained. Ten grams of MD-
RICH 110P gold bronze powder (from MD-BOTH Industries)
were added to the solution and well-dispersed. The hot
wax liquid was coated on a paper substrate which-has a
pressure-sensitive adhesive and release liner on its
opposite side. The assembly was die-cut into the shape
of a coin and glued onto a document by applying a
permanent adhesive on the back side of the release liner.
The color developer-coated coin-shaped substrate was
peeled off the release liner. It firmly adhered onto the
finger and was rubbed over the latent images. A visible
blue colored image appeared instantly.
Example 2
A group of numerals was printed on paper having a
basis weight of 6.4 grams per square meter with an ink-
2~~9~4
- - 26 -
based zincated alkylphenol-formaldehyde novolac resin.
The numerals were invisible to the human eye.
A mixture of 100 grams of chromogen-containing
microcapsules dispersed in waxes (OPAS Activator from
Mead Corporation) and 5 grams of gold powder (grade RG
9825 from United States Bronze Powders Inc.) was heated
to about 90°C and thoroughly mixed. The hot wax liquid
was coated on a paper substrate which has a pressure-
sensitive adhesive and release liner on its opposite
side. The assembly was die-cut into the outline shape of
a football and glued onto a document by applying a
permanent adhesive on the back side of the release liner.
The capsule-coated football-shaped substrate was
peeled off the release liner. It firmly adhered to the
finger. A visible black colored image appeared instantly
when the coated was rubbed over the hidden entries.
Example 3
This experiment was performed according to the
procedure of Example 6 described in U.S. Patent No.
3,823,022 except that an alkylphenol-formaldehyde novolac ..
resin (a Lewis acid) similar to that used in Example 1,
above, was used instead of 2,4-dihydroxyacetophenone (a
Lewis acid).
A solid marking crayon was proposed by mixing 13
grams of polyethylene glycol (Carbowax 4000 manufactured
by Union Carbide) with one gram of alkylphenol-
formaldehyde novolac resin HRJ-2346. The mixture was
heated to about 100°C until a clear solution was
obtained. The molten material was molded to form a
crayon. Rubbing this crayon over the latent images
prepared in Example 1 of this invention failed to produce
visible colored images. Apparently, alkylphenol-
formaldehyde novolac resin was desensitized by the
- 27 -
polyethylene glycol (Carbowax), since it is a known
desensitizer, as disclosed in U.S. Patent No. 4,199,618
to Golden.
Example 4
This experiment was conducted to demonstrate that
polar waxes preferred in the present invention are
superior to the Lewis base wax, polyethylene glycol
(Carbowax), used in U.S. Patent No. 3,823,618 to Thomas.
Thirteen grams of a polar wax, HOECHST WAX KSL (a
hard ester wax derived from montan wax by Hoechst
Celanese Corporation), were mixed in one gram of
alkylphenol-formaldehyde novolac resin HRJ-2346 (from
Schenectady Chemicals, Inc.). The mixture was heated to
about 100'C until a clear solution was obtained. The hot
liquid was molded to form a crayon. Rubbing this crayon
over the hidden entries prepared in Example 1 instantly
developed a visible colored image.
Although the invention has been described with a
certain degree of particularity, it is understood that
the present disclosure has been made only by way of
example and that numerous changes in the details of
construction and the combination and arrangement of parts
may be resorted to without departing from the spirit and
scope of the invention. Thus, the scope of the invention
should not be limited by the foregoing specification.
