Note: Descriptions are shown in the official language in which they were submitted.
Docket 2444 CIP
33~
. SENSITIZED RECORD SHEET
Background_of the Invent~on
This invention is related to an acid-colorable sensitize
record sheet for use in chemical copy systems. The record sheet
of this invention bears on at least one sur:Eace thereof a film of :~
. a low-~ack ink which is substantially color~less but is acid
: ~ colorable. In use, acidic materi~l is applied to the record
~!0 sheet in a mark-f~rming pattern, thereby causing color to appear
. when and where the acidic materi~l is applied thereto.
The colorless, acid-colorable~ low-tac~ ink of this
invention comprises a basic, colorless, chromogen;c dye-precursor,
;: capable of developing a distinctive color by chemical reaction
with an acid.
Exemplary of the colorless, chromogen;c dye-precursors
useful herein are Crystal Violet ~actone (CVL), p-~oluenesul~inate
~ salt of Michlerl~ Hydrol or 4,4i-bis (diethylaminoj benzhydrol,
:~ ¦ben~oyl leuco methylene blue (BLMB), Indolyl Red (3,3-
phthalidylidene-bis-~(N-ethyl-2~methylindole), Malachlte Green ;:
¦Lactone, 8'-methoxybenzoindolinospiro-pyran, Rhodamine L~c~one, . .
¦and mixtures thereof.
¦ Exemplary o~ the acids useful in coloring ~he colorless, :
::: ¦chromogenic dye-precursors of this invention are acidic clays such
.i ¦as attapulgite, kaolin, and acid-treated Silton clay, and organi
: ¦acids such as carbo~ylic acids and phenols, particularly phenolic
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Docket 2444 CIP ~ 5~
resins such as the novalak resins and certain metal salts thereof,
such as zinc novolaks.
In use, the sensitized record sheet of this invention
is colored by application thereto of an acid material, containing
one or more of the acids of the type described above. The acid
can be applied to the sensitized record sheet of this invention
in the form of a liquid solu~ion or suspension, or in dry form
as a loose powder or as a powder suspended in a matrix material
such as a wax. To make a primary record, the acid material can
be applied in the form of an ink from a pen, brush~ spray or type
font, or by use of an acidic crayon. Either a primary record
or a copy can be made on the sensitized record sheet of this
; inv~ntion by application of acidic material to a sensitized
surface of the record sheet, for instance, by markin~-pressure-
release of the acidic material from the under-side of an
; oversheet. Such oversheets~may have an acidic coa~ing on the
underside, which coating may contain acidic powder in a wax
base oran acidic solution, present as droplets, isolated in a
dried emu1si film or s the core mater~l1 in microcapsules.
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Preferably the sensi~ized record sheet of this
invention is used as a receiving sheet, mated with a pressure-
responsive transfer oversheet. Such receiving sheets are known
in ~he art as CF sheets (coated face); and such trans~er sheets
are known as CB sheets (coated back).
The combination of an acidic CB transfer sheet and a
basic chromogenic CF receiving sheet is the reverse o~ the
conventional commercial carbonless copy paper record system. The
- transfer coating of commercial CB sheets offers a protective
structure (such as microcapsules, dried emulsion films or wax
films) to isolate the colorless~ chromogenic dye-precursor
compounds from the efects of light and air which may induce
undesired colora~ion o~ the dye-precursor. The use of
chromogenic dyerprecursors on CF receiving sheet surfaces o~fers
many advantages, but has been avoided in commercial practice
because it is dif~icult, and has been previously impractical, to
stabilize such a chromogenic CF surface against accidental
coloration, particularly by ultraviolet light. The low-tack ink
and r~ecord sheet of this invention overcomes the problem of
unintended coloration of the dye-precursor.
The advantages of the sensitized record sheet of this
invention over the conventional aqueous-coated CB sheet, having
the chromogenic dye-precursor present as microencapsulated
solution droplets, include the following: more efficient use of
costly chromogenic dye-precursors; selective application of
reactant~ only in required ar~as, aqueous coating methods
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Docket 2444 CIP 1~48356
un-needed, thus saving the energy necessary to dry the aqueous
coats; wider range of su~strate papers available particularly
low-weight papers which cannot be aqueous coated; rapid
stabilization of the ink coat on the paper surface, giving a
polymer film which is available for immediate reactivity;
produces no dusting, which is a common problem in aqueous coated
systems; and the ink film can be applied by press-printing
methods, thus avoiding the expense of a separate coating step.
This Invention
The sensitiæed record sheet of this invention bears a
low-tack ink on a surface thereof. The low-tack ink contains a
solvent, (including a plasticizer), a resin and a colorless
chromogenic dye-precursor. Preferably,the solvent further contains
a bodying agent, and the ink further contains a zinc salt catalyst.
lS The solvent is an organic solvent, pre~erably being
largely an aromatic hydrocarbon solvent. The 901vent must be a
solvent for the colorless, chromogenic dye-precursor. The solvent
must be a mixe~d solvent, being volatile in part and relatively
non-volatile in part. The solvent must have sufficiently low
vapor pressure to permit use of the ink on multiple roll ink feed
devices with little loss of liquid volume by evaporation so as to
avoid premature setting of the ink within the ink train. When the
lnk is spread in a thin film as on a paper sheet substrate, the
solvent should evaporate in part to give a more rigid, low-tack
film. But the solvent must be relatively non-volatile in part so
as to not completely evaporate from the substrate but rather remain
thereon to serve as a plasticizer for the applied resin film. The
solvent, and indeed all o~ the other comp~nents of the ink, must
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be compatible with the colorless chromogenic dye-precursor, that
is, not react with the dye-precursor to generate color. Exemplar
of the more volatile fraction of the solvents of use herein is
the preferred mixed aromatic solvent: 70-80% monoisopropyl
S biphenyl and 20-30% diisopropyl biphenyl. Other relatively
volatile solvents, which may be used alone or mixed or as diluents
with the preferred relatively volatile solvent, are high boiling
kerosene, butyl ben20ate, benzylbenzoate, dimethylphthala~e,
isophorone, cyclohexanone, and alkylated naphthalene.
The relatively non-volatile or plasticizing fraction
of the solvent must be sufficien~ly high boiling to not substan-
tially evaporate under ambient conditions and to thus become
a permanent part of the applied ink film. Exemplary of ~he
relat~vely non-volatile or plasticizing fraction solvents of use
herein is the preerred mixed aromat~c liquid; 5-20% diisopropyl
; biphenyl, 30-60% triisopropyl biphenyl, and 10-40% tetraisopropyl
biphenyl. Other useful plastici~ing fraction solvents which may
~; be used alone or mixed or as diluents wlth ~he preferred
plasticizing ~raction solvents are dioctylphth31ate,
dibutylphthalate, butylbenzylphthalate, halogenated terphenyl,
tricresylphosphate, benzophenone, and dicyclohexlphthalate. A
particularly useful plasticizing fraction is a 1:1 mixture of
benzophenone and dicyclohexlphthalate.
The preferred solvent combination o~ relatively high
boiling and low boiling fractions described above is preferred
as giving good dye æolvency and being non-migrating, non-toxic,
and compati~le with printing press materials.
~ Resins, use~ul as the base o~ the ink of this invention,
; ¦ should have a low acid number (preferably less than 1.0~ and
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a softening point in the range of about 80 C. to about 105 C.
Preferred are hydrocarbon resins such as poly-alpha-methlstyrene
and polyalkyl resin. Useful poly-alpha-methylstyrene resins are
the Kris~alex resins such as Kristalex 1085 and 3100 (Hercules
Inc.). Useful polyalkyl resins include Wingtac 95 (Goodyear
Chemical Company). Rosin esters may also be used as the resin
herein.
The combination of resin and solvent [and plasticize~
here described generally lacks sufficient viscosity to be used
convPniently on a printing press, such as a le~ter press~ without
~he addition of a viscos ity regulator or bodying agent as part of
the solvent. Fatty alcohols have been found to be partic:ularly
useful as the bodying fraction of the solvent. Preferred is a
mixture of ~b~ut 65%-75% stearyl alcohol and about 25%-35% cetyl
alcohol.
As the artisan will appreciate 9 less viscous inks are ~r
particularly useful for flexographic and gravure pri~ting. The
reduced viscosity can be achieved by using less bodying agent
and[or more volatile diluent for flexo and gravure inks than is
~- 0 used for letterpress inks.
It has been found that various catalys~s or activators
can be added to the ink of this invention to enhance the reactivit
o~ the colorless, chromogenic dye-precursors and give more rapid
; ~ and intense color development in use, without destabilizing the
,; ink to premature and undesired color developments during storage
and handling. Preferred are zinc aliphatic carboxylic acid salts r
or zinc cycloaliphatic carboxylic acid salts such as zinc octoate
and zinc neo-decanoate. The selected zin^ salt may also be a zinc
resinate, having a zinc content of about 8 tO about 1(~/~ an acid:
O number of about -15 to about -l9,-and a softening point in
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the range of about 82C. to about 100C. The use of the zinc
ca~alyst in the ink of this invention is preferred, although
~he ink and sensitized record sheets of this invention perform
quite satisfactorily wi~hout the zinc catalyst.
The ink of this invention may be formulated as follows:
Solvent 33-70%
Dye-precursor 2-11%
Resin 30-50%
Zinc salt 0.2-5%
The 33_70V/o solvent of the above formulation is 20-35% of a more
volatile fraction, 10-25% o a relatively non-volatile fraction
and 3-10% of a atty alcohol bodying agent, based Oll the weigh~
of the total formulation. As noted above, the fatty alcohol is
not essential to the perEormance of the ink and sensitized record
material o this invention and can be omitted. All percents used
herein are percents by weight.
Useful and preferred embodiments of this invention are
set out in the following Examples:
,~ Example l
A preferred ink was made by mixing the following:
28.19 parts of mixed 70-80% monoisopropyl biphenyl and
20-30% diisopropyl biphenyl volatile solvent fraction
13.89 parts of plastici~ing solvent fraction~ which is 5-20%
diisopropyl biphenyl,
:30 60% triisoprophyl biphenyl and 10-40%
; tetraisopropylbiphenyl
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; 6.62 parts of a 30:70 cetyl alcohol-stearyl alcohol mixture which
is the bodying fraction of the solvent
5.38 parts of CVL
0.30 parts of Indolyl. ~ed
; 43.62 parts of poly-alpha-methylstyrene resin (Kristalex 1085)
;~ 2,00 parts of zinc oc~oate
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EXAMPLE 2
A similar ink to that of Example l was prepared by
substituting the same amount of polyalkyl resin (Wingtac 95)
for the poly-alpha-methylstyrene resin of that Example. Mix-
tures of the two resins were also quite satisfactory.
EXAMPLE 3
A similar ink to that of Example 1 was prepared by
substituting the same amount of zinc neo-decanoate for the
zinc octoate of that Example.
EXAMPLE 4
Another preferred ink was made by mixing the following:
30.0 parts of the volatile solvent fraction of Example l
14.2 parts of a 1:1 mixture of benzophenone and dicyclohexyl-
phthalate as the plasticizing solvent fraction,
5.9 parts of the fatty alcohol bodying fraction of the sol-
vent of Example l.
4.8 parts of ~-toluenesulfinate salt of Michler's Hydrol
45.0 parts of poly-alpha-methyl strene resin (Kristalex 3100).
In addition to serving as a bodying agent in this Ex-
ample, the mixture of cetyl alcohol and stearyl alcohols in-
; hibits heat-induced color deve]opment in the dyestuff of this
Example, which dyestuff tends to develop a blue color on
heating in the absence of the bodying agent.
~; The inks of this invention were applied to various
base paper stocks to give a "dry" ink weight in the range of
about 0.1 to 0.5 lb./ream of 500 sheets (17 x 22 inches).
For most common paper stocks, application in the range of 0.2
to 0.3 lb./ream was found to be dry to the touch, non-off-
~; setting and satisfactory for acid-activated print production.
Paper stocks
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~ Docket 24 4CIP 1~48356
of about lO to 20 lb./ream were generally used as the base stock.
Although much heavier papers could also be used.
Application of the exemplified inks to the paper stock
¦ was preferably made by letterpress printing, including rubber
5 , plate printing and dry-offset.
It will be appreciated that by these means a sheet
may be evenly printed in its entirety, to ~ive over-all
sensitivityj or be spot printed to give sensitivity only in
desired areas. The latte-r method is economical of materials
and is particularly useful in the manufacture of business forms.
The sensitized record sheets of this invention
instantly produced permanent dark blue to blue-black marks
when and where treated with an acidi.c marker.
; Subst,ràte stocks, for preparation of the sensitized
record sheets of this invention by appl1cation thereto of the
low-tack ink of this invention, are preferably paper, but may
include other ~iber, such as glass fibers and polyethylene fibers
~nown in the synthetic "paper" art. Acidic pigments and clay
. filler may produce a low order coloration on contact with the
ink of this invention~ and should therefore be avoided in choosing
¦ a suitable aper subscrate for usF herein.
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