Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
6~
~ his invention relates to pressure sensitive
information transfcr and duplicating systems and parti-
eularly to improvcd chemical type transfer and reproduc-
tion media for effecting duplicative image transfer
on sheet material in response to selectively applied
pressure and to processes for forming the same.
.
Pressure sensitive imagè transer media o~
diverse character are widely employed in the information
r~cordin~ and duplicating ar~s. Chemical type or so-called
"earbonlessl' pressure sensitive trans~er and duplicating
systems, wherein a visable image is formed by the selective
chemical reaction of two essentially colorless reagents,
have been long recognized as a viable expedient for the
formation of duplicate copy material. Such systems normally
broadly comprise a substrate supported coa~ing that con-
tains a ~irst normally inactive chemical reagent material
that is selectively transferable ;n response to applied
pressure into a reaction providing and color producing
relationship with a second normally inactive chemical
reagent material contained within or comprising a sccond
coating disposed on the surface of an interfacially
eontiguous sccond substra~e. Conventionally illustrative
G~ SUC~ ctlemical type reproduction systcms are trans~er
and duplicating systems where;n the rear surfaco on ono
paper sheet substrate is provi~ed wi~ll a coating anct
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which sheet is then termed a "CB" ~i.e. coated back)
sheet and the front side of that same and/or a separate
papcr sheet substrate is provided with a coating which
is then termed a "CFB" (i.e. coated front and back) or
"CF" (i.e. coated front) sheet, respectively. When the
coatin~s on a CB and a CF sheet are placed in in~erfacially
contiguous relation and subjected to selec~ively applied
pressure, as by the pressure of a stylus or the impact
of a typewriter key on the obverse surface of the CB
sheet, the operative and usually colorless chemical
reagents in such coatings are brought into co-reactive
relationship, as for example on the surface of the CF
sheet, to produce a colored image conforming to the contour
of the selectively applied pressure member. c
Such chemical type pressure sensitive transfer
and duplicating systems are in widespread and expanding
use at the present time for the making of multiple copies
of selectively recordable duplicative information on
sheet m~terial, such as paper and the like, due, at least
in part, to the~r basic cleanliness and to the fact that
the color producing reagents are inactive until placed
into operative co-reactive relationship in response to
selective application of pressure.
Although it was early recognized, as for e~ample
in the Gill U.S. Patent 1,781,902, that many colorless
chemical reagents were capable of pro~ucing a visab].c
colorcd i~age upon interreaction therebetwecn, most of
the syste~s in wide co~mercial usage at the prcsen~ time
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employ a colorless organic dyestuff as a dye precursor
in encapsulated liquid form distributed within the CB
sheet coating and àn electron accepting material in
the CF sheet coating. ~hen such CB and CF sheet coatings
are placed in contiguous interfacial relation, the
application of pressure effects a rupture of the liquid
dyestuff confining capsular elements in the area of
applied pressure to effect a release of the dye precursor
material and selective transfer of at least a portion
thereof into co-reacting and color producing relationship
with the electron accepting material in the contiguous
coating on the CF sheet wi~h the resulting forma~ion of
a duplicative image thereon.
Some early and relatively recent patents that
illustratively disclose chemical type or so-called
"carbonless" transfer media employing encapsulated dye
precursor materials as the chromogenic reagent in the CB
coating and electron accepting materials as the c~romo-
genic reagent in the CF coating are USP 2,712,507 (1955)
to Green; USP 2,730,456 (1956) to Green et al.; and
USP 3,455,721 (1969) to Phillips et al.
. Other more recent patents that illustratively
dis~lose the disposition o~ the dye precursor material
in the CF coating and encapsulated electron accepting
mat~rial in th~ CB coating include USP 3,787,325 (1974)
to Roover and USP 3,98~,168 (1975) to Brockett et al.
Such "carbonless" ~ransEer media as presently
commercially employed and particularly those that con-
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ventionally employ an encapsulated type vehicle for one
of the reactive constituents, mos~ usually an organic
dyestuff, a~e not without disadvantage. Amollg the recognized
di~advantages of such media are the fact that they are not
only relatively expensive, requiring speciali~cd fabricating
techniques, but are also unduly pressure sensitive. Such
unduc sensitivity often results in undesired premature
transfer occasioned by inadvertent dye precursor release
and ~ransfer resulting from pressures normally attendant
packaging, handling and processing operations, spot coating
delineation, printing operations and the like, particularly
where multicopy manifolding operations are involved. In
addition, such media are inherently subject to a progressive-
ly increasing laclc of copy definition as the number of
desired copies increases as well as by a fading of the
copied image with time~
The recently issued Shackle and Young U.S. Patent
No. 4,063,754 discloses the utilization of non-aqueous
"hot mel~" coating compositions for CF sheets in a carbon-
less transfer system incorporating acid reacting color
developing reagent materials. Such patent describes, a~
considerable length, numerous disadvantages attendant
employing solvent or water based compositions for effecting
the deposition of such carbonless coatings on substrates.
Among such enumerated disadvantag~ are ~he health and
fire hazards attendant the release of generally volatile
solvent vapors and the expen~iture oE significant amoun~s
of energy for the evapo~ation of the water from aqueous
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solvent systems. In addition, the practical necessities
of solvent recovery and the drying of aqueous coating
compositions requires relatively complex and expensive
apparatus as well as the attendant problcm of solvent
safety hazards and disposal of polluted wa~er attendant
preparation and clean-up of such aqueous coating com-
positions.
A further recently issued paten~ to Shackle and
Young's assignee, i.e. U.S. Patent No. 4,112,138j Davis
and Shackle for Manifold Carbonless Form and Process for
the Production Thereof discloses the utilization of
non-aqueous, solvent free "hot melt" coating composltions
for CB sheets. The specification of this patent similarly
describes, at considerable length, the nurnerous dis-
advantages attendant employing solvent or water based
compositions for efecting the deposition of carbonless
coatings on substrates.
The Shackle and Young patent and the Davis and
Shackle patent stress the "non-aqueous" and "solvent ree"
character of the assertedly novel hot melt coating com-
positions, apparently based upon the asserted disadvantages
flowing from the presence of water both in the fabrication
process and in the finished product. The Davis and Shackle
patent discloses the preferred use of microcapsular chro~o-
genic reagent m~terials in the CB coating although the
process clairns are not expressly limited thereto. Although
the Shackle and Young patent is expressly directed to a hot
melt CF coating, the vehicular form of the acidic electron
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accepting type of color developer, i.e. whether micro-
encapsulated, capsulated, dispersed or other form, is
not particularly specified. It is relatively clear, how-
ever, that the described CF product is intend~d for use ~ith
CB sheets incorporating an organic dyestuff dye precursor
in encapsulated form and, as such, represents an asserted
impro~ement for the capsular type systems presently in
widespread commcrcial use.
The present day widespread commercial employrnent
of CB sheets incorporating encapsulated organic dyestuff
dye precursor materials, is, as mentioned above, not
without disadvantage, such as undue expense, premature
activation, limited reproduction fidelity in multiple
CQpies and detrim.ental fading of the reproduced images.
Such disadvantages have been largely tolerated hecause of
the absence of a viable commercially acceptable alternative.
As pointed out abo~e, it was early recognized that many
chemical reagents were capable of producing visable
duplicative images in chcmical trans~er payer usage. The
aforementioned Gill U.S. Patent, for example, employed a
member of the gallo-tannic acid series as the chromogenic
reagent in the CB sheet coating in association ~ith a
ferrous or ferric salt as the chromogenic reagent in the
CF sheet coating. In contradistinction to the later Shackle
and Young and Davis and Shackle's disclosures, this system
requires thc presence of solvent aC or in the CF sheet
coating ~or the color producing reaction to go fo~ard
and hence Gill teaches Che inclusion o~ "a small percentage
of glycerine or other non-drying substance, or a hygro-
scopic ingredient" in 'the CF shee~ coating. The need for
the presence of moisture and the deleterious effects of
such moisture on the paper substrate was early recognized
in the Gookin et al. U.S. Patent No. 1,950,g82, who
provided a water impervious film intermediate the substrate
and the CB and CF sheet coatings and included in the latter
both ~agnesium chloride as chromogenic reagent material
and ~lue or gelatine as moisture retaining material. A
somewhat different approach was followed in Groak U.S.
Patent No. 2,168,098, who disclosed a CB sheet coating com-
posed of a hard waxy substance having dispersed therein an
admixture of starch, a hydroscopic material, such as
glycerine, and a color producing reactive substance. In
neithe~ of these approaches, ho~Jever', was water included
as a necessary ingredient in the coating composition and
thus basically confor~ed in such disclosure and teaching
to the later issued Shackle patents.
Some of the aspects of the approach that was early
suggested by the Gill, Gookin and Groak patents have
recently reappeared in Austrian Patent 3319825 which issued
March 25, 1976 ~and apparent counterpart Canadian Patelt
993,656 and West German publication 2,342,596 of April ll,
1974). In these disclosures, an organic dyestuff dye pre-
cursor is dispersed in a binder on the CF sheet and used
in conjunction with an essentially fulLy transferable C~
~heet coating which incorporates clay materials as the
~lectron acccpting chromogenic reagent material, ~ither
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alone or in associa~ion with phenolic material and in-
organic salts of multival~nt metals. Solvent, water based
and hot melt systems are specifically disclosed for the
CB sheet coatings. Significantly, however, the hot melt
CB sheet coatin~s are all wa~er free, again in conformity
with the Shackle teachings.
:A later issued West German patent application
Z4 56 083.2 of September 2, 1976 (based on Austrian appli-
cation ~1405/75 of February 25, 1974 and its apparent
counterpart abandoned U.S. application Serial No. 655,019
cf February 4, 1976 as referenced in U.S. Patent No. 4,096,314)
discloses the uti~ization of metal chlorides, preferably
in combination with urea or urea deri~atives, as CF sheet
..
coatings in both solvent and aqueous sys~ems. In association
therewith, there is disclosed the utilization of organic
dyestuff dye precursors dispersed in a hot melt coating
medium as the CB coatin~. The preerred CF sheet coatings
are identified as those, for a water based coating, that
contain zinc chloride and urea and further include a metal
stearate.
This invention may be briefly described, in its broad
aspects, as an improved chemical type transEer and duplicating
sys~em comprising a hot melt type o CB sheet coatin~ con-
taining and retaining discrete and selectively constituted
liquid electron accepting chromogenic reagen~ material and
to methods for ~ormi!~g the same. In its narrower aspects,
the subject invention includca a novel hot melt CB coating
ccnstituted o~ an inte~ixturc o~ natural and synthetic
,
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., ., . ~ .,r
waxes containing and recaining discrete microscopic drop-
lets of a selectively constituted solution of a metallic
ehloride, pre~erably zinc chloride in water suitably
buffered to minimize, if not effectively neutralize, thc
available acidic chloride content thereo~ uniformly
distributed therewithin as a color producing reagent. In
a still further aspect, the invention includes a com-
patible improved CF sheet coating havin~ a plurality of
water insoluble dye precursors in solid orm selectively
dispersed and distributed throughout an alkaline biased
carrier film.
Among the manifold advantages atkendant the practice
of the subject invention is the provision of improved low
eost carbonless transfer media that serve to provide mark-
edly increased numbers of duplicative copies with sharper,
more intense and highly smear resistant transferred images.
Additional advantages include compatability with "one time"
earbon papers and standard printing inks; a permitted re-
duction in basis weights and the provision of an odorless
CB sheet coating that can be reused one or more times,
thus permitting retyping on the obverse surface thereof.
Ot~er advantages include the provision of a CB sheet coat-
ing that can be readily striped and spot coated and which
is recyclable. Still other advantages include the pro-
vision o~ a C~ sheçt coa~ing that can be fabricated with
minimal energy rcquiremen~s on conventional coating equip-
ment requiring minimal capital investmen~. Further ad-
vantages includc the provision of transferred images
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that are effcctively stable in character and a system
which is operablc at temperatures as low as -30F. Still
further advantages include the provision of coa~ings of
extended shclf life ~hat are markedly resistant to un-
. desired premature activation under conditions of high
.temperature. andlor high humidity; that are character-
ized by-reduced potential to irritate sensitive sklns and
to eorrode iron rollers and other componènts of coating,
printing and collating apparatus; coatings that are
essentially uncritical as to substrate c~laracter and
which are highly resistant to undesired transfer on print-
ing-presses, collators and other equipment normally in-
eident to manifolding, printing and packaging operations~
A principal object of this invention is the pro-
~ Yision o~ improved chemical type pressure sensitive trans-
fer and reproduction media, to processes for fabricating
the.same and to improved systems employing such media.
. A further principal object o~ this invention is the
provision oE an improved hot melt chromogenic reagent con-
taining coating composition for CB transfer sheets.
Anothêr object of this invention is the provision
of an improved composite ~ax base hot melt type of CB
sheet coating containing discrete drop1ets of a selec~ively
constitutcd water solution of a ~etallic chloride suitably
buffered to minimize, if not e~fectively neutralize, the
available acidic chloride content ~hereof uni~ormly dis-
tributed t~iere~ithill as a color producing reagcnt.
A further object o~ thi~ invention i5 the provigion
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of an improved water base metallic chloride solution for
use as electron accepting chromogenic reagent material in
carbonless transfer systems that is efectively non-corrosive
and non-irritating and which is highly resistive, when
dispersed in a hot melt carrier vehicle, to undesired
premature image actuation under conditions of high temper-
ature and/or high humidity.
A still further object of this in~ention is the pro-
vision of an improved wacer base metallic chloride soluLion
for use as electron accepting chromogenic reagent material
in carbonless transfer systems.
Other objects and advantages of ~he subiect in-
vention ~ill become apparent from the following portions
of this specification which describe, in accord with the
mandate of the patent statutes, the principles of the in-
vention and best mode presently contemplated by the invent-
ors for carrying out said inventions.
Figure 1 is a schematic representation of chemical
type pressure sensitive transfer and reproduction media
incorporating the principles of this invention; and
Figures 2a and 2b are photomicrographs (4200X and
14000X) of an imp`roved hot melt CB coating formed and
constituted in accordance with the principles of this
invention.
Referring to the drawings and initially to Figure 1,
there is provided ~n illustrative set o~ chemical type or
carbonless transfer and reproduction media fabricated in
accord with t~e principles of the inven~ion. As there shown,
such set includes a CB sheet comprising a first planar
substrate 10, suitably a paper sheet or web, having a
thin solidified hot melt CB coating 12, constituted as
hereinafter described, disposed on the undersurface there-
of. Adapted to be positioned in interfacially contiguous
relation-with the CB coating 1~ on the underside of
substrate 10 is a CF sheet coating 16 disposed on the
upper surface of a second paper sheet substrate 14.
Such substrate 14 may have its undersurface coated with a
CB coating 12 and thus constitute a CFB sheet, or may have
an uncoated undersurface and thus constitute a CF sheet.
A~ternatively, and illus~ra~ively adapted to be disposed
in interfacially contivuous relation with either a CB
coating 12 on the underside of the "CF,Bi' sheet 14 or with
a CB coating 12 on the underside of the "CB" sheet 10, is
a separately illustrated "CF" sheet havin~ a CF coating 16
disposed on the upper surface of a third substrate 18. As
will be apparent to those skilled in the art, any number
of intermediate CFB sheets or webs l~ may be interposed
in stacked relation to form a multilamina transfer and
reproduction system. Likewise, such multilamina set may
include one time carbon transfer sheets interposed with
uncoated or CB coated sheets or webs in a manifold arrange-
ment in accord with the dictates of the user thereof.
The novel and improved hot melt CB shee~ coa~ing
broadly comprises tho resulting set or solidi.fied film
from an applied and su~sequontly cooled emulsi~ied liquid
inter~ixture o a meltod lo~ oil content wax carrier vehicle,
12
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pre~erably of composite character, a melted synthetic flow
wax and dispersant and a chromgenic reagent solution of
a metallic chloride, pre~erably æinc ch~oride, dissolved
in water and suitably buffered to minimize, i not effect-
ively neutrali~e the available acidic chloride content there-
of; said emulsified intermi~ture also desirably having
uniforTnly dispersed therein small but critically limited
amounts of a resinous film forming agent to promote film
hardness and toughness, an isolating agent to minimize,
if not effectively preclude, undesired transfer of the
coating or portions thereof in response to unintentional
pressure application and an opacifier-filler to reduce
the gloss of the finished copy and preserve the appearance
of the substrate.
In its narrower aspects, the subject inventiOTI
iTlcludes a hot melt CB sheet coating composition formed
of about 35 to 75 percent of a meltable low oil content
synthetic or naturally derived hard wax vehicle; at least
1 to about 15 percent of a chemicaLly modi~ied wax-like
material having properties of a fl.ow agent, dispersant
and emulsifier; and at least 10 to about 35 percent oE
a chromogenic reagent component in the form of a Lewis
acid, desirably an electron accepting hygroscopic, if not
actually deliquescent, metalLic salt together with an
amount of water neccssary to desirably Eorm a relatively
concentrated solution thereo.
Optionally but desirably included in such CB
8heet coa~ing composition ~or provision of an cnhanced
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co~nercially attractive prodtlct are one or more of the
following additional constituents. One such optional
constituent comprises a film forming agent to encourage
the formation of a harder and tou~her surface film after
setting and to thus minimi~e pre~ature actuation of the
color producing reaction. This film forming agent must
be non:reactive with the chromogenic reagent and may
vary in amount from a minimum of about 2~o up to an amount
that deleteriously effects ~he Elow characteristics of
the mix. Another such optional but yet desirable con-
stituent comprises an isolating agent that is essentially
incompatible with the wax vehicle when solidified and
which serves to provide desirable surface characteristics
to the resultant film, s~lch as ~o minimize, if not effect-
i~ely preclude, undesired transfer of the coating or
portions thereof in response to unintentional pressure
application. The isolating agent may vary in amount ~rom
a desirable minimum of about 2% up to a maximum of about
20%. A .still further optional but desirable constituent
is an opacifier-filler to enhance the appearance of the
coated surface of the CB sheet, such as by reducing the
gloss thereof. As is well known in this art, such opacifier-
filler may vary in amount required to provide a desired
appearance, typically about 5%, and m~yincludc titanium
dioxide, various non-acidic high brightness clays, litho-
pone or other recognized matcrials.
The meltable wax véhicle may s~litably comprise any
o~ the low oi.l content paraffin waxe5, microcrystalline
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waxes, carnauba, Montan or other conventionally employed
low oil content vegetablc, synthetic or mineral derived
hot melt wax type carrier vehicles. The presently pre-
fexred meltable wax vehiclc, a composite made up of about
3 ~o 4 parts of a low oil content paraffin wax, intermIxed
with abouc 1 part or less of carnauba wax. A presently
preferred paraffin wax is a low oil content, high melting
point, fully refined paraffin wa~, suitably Pacemaker 53
. .
as manufactured and sold by Cities Service Oil Co. of
Tulsa, Oklahoma. Such wax has the follo~ing properties:
- Melting point, ASTM, F 143-150
Melting point, AMP 146-153
Oil Content, Wt. % max 0.25
Odorless
Viscosityr cs at 210F 5.5
Needle penetration at 77F 13
Flash point F 485
Other suitable low oil content hot melt ~7ax carrier
vehicles include alpha ole~inic waxes, suitably ~6317
Synthetic Wax as available from Moore & Munger Inc. of
Fairfield, Connecticut; microcrystalline ~ax, suitably 195
Be Square l~hite, available from Petrolite Corporations
Bareco Division; carnauba wax, suitably Brazilian Re-
fined available from Baldini & Company of Milburn, New
Jersey.
Moore & ~unger's ~6817 Synthetic Wax has the followlng
propertics:
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~ /r~ V~r k
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Con~calin~ Point, F.,
ASTM D 938 162
Needle penetration, mm/10,
ASTM D 1321 77F. 14
Viscosity, Saybolt (a) 210F.
(SUS), ASTM D 2161 52
Viscosity, Kinematic (a~ 210F.
(Cs.~. ASTM D 445 8
C~lor, Saybolt, ASTM D 156 +4
. Flash Point, F. (COC) 510
Barecois 195 Be Square White microcrystalline wax
has the iollowin~ properties:
Mel~ing Point, F. ASTM D 127 193/198
Penetration (a) 77F. ASTM 6~'7
. Color ASI~I D 1500 0.5/0.5+
A preferred carnauba wax is Baldini's Brazilian
Refined Carnauba wax that is possessed of the following
properties:
Melting Point, min., F. 180.5
Acid Number
minimum 4.0
maximum .10.0
Saponiication Number
minimum 78.0
. maximum 88.0
The meltable chemically modified wax-like material
having the desired properties o a flow agent, dispersant
and emulsifier most suitably comprises a material of the
type di.sclosed i~ U.S. Patent No. 3,941,608. Other
suitably chemically modiEied wax materials havin~ ~he
- somewha~ similar propcrties include modiEied synthetic
waxes as discolsed in U.S. Patent Nos. 2,890,124, 2,890,125
16-
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snd 3,163,548. ~ pre~erred commercially available wax-lilce
material formulated in accord with U.S. Patent No. 3,941,608
i~ #731S wax as so~d by Moore & Munger, Inc., of Fairfield,
Connecticut. Such #7315 wax has the following general
proper~ies:
Penetration Hardness
(FLP~I-225 Typical
Melting Point
~Fisher Johns)144Typical
Acid Nu~ber
(AST~ D 974)Z Typical
Another suitable wax-like material having somewhat
similar properties as the foregoing suitably comprises an
amide of a fatty acid, such as Armid HT as available from
Axmour Industrial Chemical Company. Such Armid HT is
possessed of the following properties-
Amide /O ~min.)90
lodine value
minimum
maximum 5
Free fatty acid %
minimum
maximum S
Melting Point, C.
minimum 98
maximum 103
The resinous film forming agent serves to enhance
the formation of a relatively hard and tou~h coating to
minimize undesired transEer oE reagent material across
the CBtCF interEace in the absence of intentional posi.tive
pressure application. A suitable film Eorming agent, which
~ust be non-reactive with the chromogenic reagen~ component,
f
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desirably comprises a relatively low melting point
ethylene-vinyl acetate copolymer, such as AC-400~ as
manufactured and sold by Allied Chemical Corporation.
Such resinous film forming agent has the following
properties:
Softening Point (~SI~ E-28) 204F.
Harc~ess dmm (ASTM D- 5) 9.5
Density 8/cc (ASTM D-1505) 0.92
Viscosity (284F - Brookfield) 550
Another suitable film Xorming agent comprises
oxidized polyethylene, suitably AC-629~as manufactured
and sold by Allied Chemical Company. Such film for~ing
agent has the following properties:
... . .. . . . . .
Softening Point 214hF.
Hardness 5.5
Density g/cc 0.93
Average Viscosity CPS 284F. 160
Acid Number 15
The isolating agent cooperatively functions as
blooming agent to provide a lubricating and barrier sur-
face to the solidified coating. Such isolating agent,
which should be essentially incompatible with the wax
carrier vehicle when solidi~ied, so as to be selectively
effective at the exposed surface, sui~ably comprises a
small amount of stearic acid, desirably ~YSTRENE 9718 as
manuactured and 301cl by the Humko Chemical Company. Zinc
stearate may al~.o be employecl.
~ he opacifler-~iller, which cosme~ically scrves
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.
both to reduce the gloss o the finished coating and to
preserve ~he appearance of the substrate, suitably com-
prises iinely~ divided titaniu~ dioxide such as UNITAN ~0-110
as manufactured and sold by American Cyanamid Company. This
material has a specific gravity of about 3~9 and is so fin21y
divided as~to leave only about a 0.10% residue on a 325
mesh screen.
The chromogenic reagent component prcferclbly com-
prises a concentrated water base solution of zinc chloride
as the electron accepting metallic chloride, suitably
buffered to minimize, if not effectively neutralize, the
available acidic chloride content thereof. Such solution
is preferably made up o about 2 to 4 parts o zinc chloride
with about l part of wa~er and which approaches a saturated
solution.
Other chromogenic reagent components comprise
concentrated water base solutions of metallic halogen salts
such as stannous chloride, ferric chloride, lithium bro-
mide and nickel chloride.
While unbuffered solutions of zinc chloride as the
chromogenic reagent have provided highly effective image
formation in transfer coatings as formulated in accord
with the foregoing disclosed formulations, such have been
subject, under extreme climatic conditions of high
temperatures and/or high humidity, to tlle apparent genera-
tion and emanation of hydrogen chloride. Although the
qu~ntities o~ h~drogen chloride so generated, appear to be
minimal, even under such ex~reme climatic conditions,
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the apparent emanation ~hereof ~rom the applied coating
has resultcd in varying degrees of premature actuation of
the dye precursors over the entire surface of an inter-
facially contiguous CF coating and, depending on the
ambient climatic conditions, in varying degrees of actuation
of such CF sheet. Such premature ac~uation is, of course,
highly undesirable, as is the generation of hydrogen
chloride with its potential to irritate sensitive skins
and to corrode iron rollers and other components o~
the processing equipment under any set of ciimatic con-
ditions.
In order to neutralize, if not actually prevent, the
generation and emanation of such hydrogen chloride, a
s~all amount of a neutralizing ammonium salt, suitably
ammonium carbonate or ammonium bicarbonate, is dissolved
in the zinc chloride solution. For à concentrated solution
of about 2 parts of zinc chloride to 1 part of water, about
.1 part of such neutralizing ammonium salt is generally
satisfactory. Experience to datc has generally indicated
that the addition of about 2 to 4% of a~monium carbonate to
~inc chloride solutions oE the type herein disclosed results
ir. effective avoidance o~ the above problems in an improved
prod~lct .
~ hile the mechanics o~ the reaction process are
not fully understood it is surmised that the ammonium salt
operates to neutralixe or othe~ise reduce the available
act~ve or acid chloride ion content and to thus preclude
its association with available hydro~en ions. Also the
possible availability oE a~nonia in both the liquid ~md
gaa~ous phase may also contribute to thc ncutrali~.ation
oE hydro~en chloride in both such phases.
- 2
Apart from the foregoing, the additions of such
neutralizing ammonium salt has provided some totally un-
expected and,-as yet, unexplainable advan~ages and results.
Such unexpected results are a bleaching and a marked in-
crease in the hardness of the solidified CB hot melt coat-
ing. Such increase in hardness not only functions to
minimize pick oif on processing components, reduces the
tendency to smear and provides sharper copy, but also per-
mits of significant reduction in the quantity of carnauba
wax that is otherwise desirably included ~herein. Carnauba
wax is not only one of the more cost significan~ components
of the coating bu~ is also only obtainable from a foreign
source of supply who controls the ever increasing price
thereof. .
The unexpected bleaching action also enhances the
appearance oE the product through an enhancemerlt of the
"whiteness" of the coating.
A presently preferred hot melt CB sheet coating
broadly comprises the resulting set or solidified film
from an applied and subsequently cooled emulsified liquid
intermixture of about 50-60% of a melted low oil content
composite wax carrier vehicle, made up of about 3 to 4
parts of a low oil content para~fin wax intermixed with
about 1 part of carnauba wax; about 2 ~o 5% of a chemi-
cally modified synthetic 1OW wax and dispersan~ and about
~5-35% of a chromo~enic rea~ent solution of at least 2
parts of zinc chloride dissolved in about 1 part oE water
buffered by a small amount of ammonium carbonate as out-
. -21-
.
,
lined above; said emulsified intermixture also desirably
having uniformly dispersed therein about 3 to 10% of a
resinous film forming agent to promote film hardness and
toughness, about 3-10% of an isolating agent to minimize,
if not effectively preclude, undesired transfer of the
coating or portions thereof in response to unintentional
pressure application and about 5% of an opacifier-fil.ler
to reduce the gloss of the finished copy and preserve the
appearance of the substrate.
In the production of the above described preferred
CB sheet coating composition in accord with the principles
of this invention, the requisite amounts of the electron
accepting metallic chloride, preferably ZnC12, and water
are int`ermixed in a reaction vessel, suitably a stea~
Jacketed ke~tle having a 210F temperature settin~, to
form a hot concentrated solution thereof. To such solu-
tion is then added the neutralizing ammonium salt,
preferably ammonium carbonate. To such elcvated tempera-
ture and now neutralized chromogenic reagent solution, the
requisite amounts of melted low oil content paraEin wax
and carnauba wax components of the composite wax carrier
vehicle are added and thoroughly intermixed as by use of
a high speed dispersing blade for about 10 Minutes or longer.
To the intermixture as so constituted, the flow wax and
dispersant constituent and the polyethylcne filming agent
and stearic acid isolating agent constituents are added in
~olid form with continual mixing uncil such constituents
are completely melted and dissolvcd in the coN~osite wax
carrier vehicle. When so melted and dissolved the opa-
ci~ier-filler, pre~erably titanium dioxide is added and
the entire mass thoroughly mi-~ed at high speed for 30 to
40 minutes to form a selectively constituted liquid hot
melt emulsion.
The resulting liquid hot melt emulsion is readily
and selectively applied in the form of a thin film, as
fo~ example at a coating weight of as low as 2 grarms/square
meter, by conventional means to the surface of a substrate,
such as a sheet or web of paper or resinous film. The
conventional coating means may comprise a print type
coater, a roll coater or the like. The so coated substrate
is then passed over a chill roll or the like to rapidly
solidify or set the applied emulsified coating composition.
In contradistinction to the systems of the prior
art which were operatively dependent upon an external water
source (often humid air) to provide the necessary ionized
zinc chloride to react with the dye precursor, the system
of the present invention contains and retains water as an
operative element in discrete droplet liquid form within
thP solidified CB film and thus effects the selective trans-
fer of ionized zinc chloride as the operative entity.
Photomicrographs of coakings formulated in accord
with the principles of this invention are shown in Figures
2a and 2b at magnifications o 4200X and 14000X respectively.
These photomicrographs clearly depict the presence of dis-
crete, microscopLcally sized zinc chloride an~oni~n salt
solution globules distributcd throughou~. the coating. Most
,
-23
'~ f.
. of such globules arc less than 1 micron in diameter with
the grcat majority thereof falling between .25 and .75 mi-
crons. Such photomicrographs further show that such zinc-
chloride solution globules peripherally incorporate..an interface
layer or the like that differs, at least in some physical
respects from both the 7inc chloride solution globules and
from the surrounding solidified wax material as evidenced
by the clearly different refractive indices involved.
To the above ends, the foregoing described method
of formulation provides a selectively constituted emulsion
in which zinc chloride solution entities are thoroughly
dispersed within the film. The basic hygroscopic, if not
actual deliquescent, properties of 7inC chloride and the
nature of the resultant film serve to minimize, if not
. effectively prevent, water loss in storage with enhanced
operating life for the product.
Another factor which contributes to the retention
of the dispersed zinc chloride solution in discrete liquid
globular form within the C~ film is the enhanced emuls-
ification obtained through the use of an essentially
alkaline and amino containing dispersant - flow wax con-
stituent in association with the relatively high acid
number wax and film forming components.
. .By way of further examples the following formula-
tions have provi(led CB sheet coating having in varying
degree, the manifold advantages earlier set forth.
. . EXAMPLE I
%
,
Paraffin Wax . 45.0
7315 Wax 2.0
AC-400 Polyethylene 5.0
Stearic Acid 3.0
Titanium Dioxide 5.0
Zinc Chloride 30.0
Water 10.0
EXAMPLE II
.
Paraffin Wax 41.0
7315 Wax 2.0
AC-629 Polyethylene 7.0
Titanium~Dioxide 5.0
Zinc Stearate 10.0
Zinc Chloride 30.0
Water 5,0
EXl~PLE III
Parafin Wax . 35,0
AC-400 Polyethylene lO.0
Zinc Chloride. 20.0
Nater 10.0
7315 Wax 10.0
Stearic Acid 10.0
Titanium Dioxide s,o
.
EXAMPLE IV
Paraffin Wax 55.0
Carnauba Wa`x , 20.0
~inc Chloride l5.0
Water 5.0
7315 Wax . 2.0
Stearic Acid 3 0
EXAMP~E V
Paraffin Wax lO.0
~icrocrystalline Wax . 3b.0
Stannous Chloride 30.0
Water lO.0
7315 Wax 3,0
Stearic Acid . 7.0
Titanium Dioxide lO.0
EXA~IPLE Vl
Carnau~a Wax lO.0
Alpha Olefin Wax 40.0
AC-629 Polyethylene . 7.0
Ferric Chloride 20.0
Water lO.0
73~5 Wax j 3,0
Stearic Acid 5.0
T.~tan~um Dioxidc 5.0
,
. -2~- .
By way of further preferential example, the above
formulations, when buffcred to minimize, if not effecLively
neutralize, the available acidic chloride content thereof,
are modified as follows:
. EXAMPLE IA
%
Paraffin Wax 42.G
7315 Wax 2.0
AC-400 Polyethylene 5.0
Stearic Acid 3.0
Titanium Dioxide 5.0
Zinc Chloride 30.0
Ammonium Carbonate 3.0
Nater - 10.0
EXAMPLE IIA
Paraffin Wax 38.0
7315 Wax 2.0
AC-629 Polyethylene 7.0
Titanium Dioxide 5.0
Zinc Stearate lO.0
Zinc Chioride 30.0
Ammonlum Bicarbonate 3.0
~J~ter 5-
27
~17~6~ `
EXAMPLE IIIA .
X
Paraffin Wax 33.0
AC-400 Polyethylene . lO.0
Zinc Chloride 20.0
Al~nonium Carbonate 2.0
`Uater 10.0
7315 Wax 10.0
5tearic Acid 10.0
~itanium Dioxide 5.0
i, ~
1~76~
E~MPLE IVA
X
Paraffin Wax 51.0
Carnauba Wax 20.0
Zinc Chloride 15.0
Ammoniu~ Carbonate 4.0
Water 5-0
7315 Wax 2.0
Stearic Acid 3.0
~X~PLE VA
Paraffin Wax 9.0
Microcrystalline Wax 28.0
Stanno`us Chloride 30.0
Ammoniu~ Bicarbonate 3,0
Water 10.0
7315 Wax 3.0
Stearic Acid 7.0
Titanium Dioxide 10.0
: EX~MPLE VIA
Carnauba Wax . 8.0
Alpha Olefin Wax 38.0
AC-629 Polyethylene 7.0
Ferric Chloride 20.0
Ammonium Carbonate 4.0
~ater 10.0
7315 Wax \ 3.0
Stearic Acid 5.0
Titanium Dioxide 5.0
~ .
The follo~ing formulations h.ave providcd highly
preferred CB sheet coatings: ~
EXAMPLE VII
Paraffin ~ax 39.0
C~rnauba llax 14.~
Zinc Chloride . 20.0
Water . . 10.0
7315 Wa~ 2.0
AC-400 Polyethylene 5.0
Stearic Acid 5.0
Titanium Dioxide 5.0
EXAMPLE VIIA
Paraffin Wax 36.0
Carnauba Wax 14.0
Zinc Chloride 20.0
Water lO.0
Ammoniu~ Carbonate 3.0
7315 Wax 2.0
AC-400 Polyethylene 5.0
Stearic ~cid 5.0
Titanium Dioxide 5.0
The foregoing hot melt CB coatings may be employed
with efectively all CF coatin~s that incorporate an organie
~yestuf or other chromo~enic reagent color precursor that
will react with ~.he ionizcd electron accepting metallic salt
when the latter is introduced into operative relation there-
with. By way of urther example, satisEac~ory results have
been obtained when such CB sheets are used with CE coating
compositions consti~uted as hereinafter dlsclosed.
-30-
f
7~
In its broad aspects, suitable CF coa~ings com-
prise the solid residue of an applied alkaline homgeneous
mixture of an evaporable liquid carrier, a chemically
neutral or alkaline resinous binder, an o~ganic color
precursor and an opacifier-filler. Such solidified CF
coatings are further characterized by the presence oE
the organic color precursor in solid form and which is in-
soluble in the liquid electron accepting chromogenic
reagent soiution contained in the CB coating. Optionally
but desirably included therein is a dispersant to assure
the uniform dispersion of the color precursor throughout
the mix and a thickener to provide the requisite viscosity
properties to facilitate the coating of the mix in accord
with the particular requirements of the ~oating equipment
employed.
The evaporable liquid vehicle may comprise water
or numerous organic solvents or mixtures thereof such as
ethyl alcohol, meth~yl ethyl ketone, toluene and the like.
Likewise, the opacifier-fiLler may constitute titanium
dioxide, ~inc oxide, lithopone, calcium carbonate or neutral
clays or intermixtures thereof.
. A preferred CF coating employs water as the evapor-
able liquid vehicle and generally comprises the solid
residue of an applied water based intermicture, such inter-
mixture comprising about 3 to 20 parts of a chemically
neutral or allcaline resinous binder, sui~ably polyvi.nyl
acetate; about 10 to 40 parts of an opacifier-filler; abou~
.5 to 5 parts oE a water insoluble acid reactable orgallic
,
.
6~
color precursor ~ixture and about 30 to 70 parts of water.
Althou~h ~lany acid reactable organic color pre-
cursors can be employed, the presently preEerred color
precursor comprises a mixture of water insoluble, alka-
line stable and acid sensitive organic dyes~uffs to pro-
duce a dark light stable and lasting image. Desirably
included in such preferred mi~ture is crystal violet lac-
tone, suitably about 0.7 parts thereof, which provides
for rapid reaction and image production, together with
about an equal amount of a blue/black dye precursor, and
lesser amounts of a red color dye precursor, suitably
about 0. 2 parts thereof and a blue dye precursor, suitably
about 0.4 par~s thereof to provide for desired image color
and a high degree of light stability and increased use~ul
life.
A suitable crystal violet lactone comprises
Brilliant Violet Leuco (CVL) as ~anufactured by Hilton
Davis Chemical Co. This dye precursor is believed to be
6-dimethylamino-3,3-bis(p-dimethyla~inophenyl)phthalide
having a molecular formula oi C26H29N302 and a molecular
weight of about 415.5. The blue/black dye precursor
suitably comprises CopykeM VI as manufactured by Hilton
Davis Chemical Co. and the blue dye precursor suitably
coMprises Reacto Blue B as manufactured by BASF.
~ he naturc of the binder is not attended with any
par~icular degree oE criticality as long as it E~mctions
as a blnding agcnt for the opacifier-~iller and the color
precursor, with both of the latter being in solid fonm.
,
.
,
~7~
.. . .
A preferred ~esinous binder material comprises polyvinyl
aeetate emulsion, suitably Airflex~456 as manufaetured by
Air Produets & Chemieals Company. Another suitable binder
material comprises an acrylie emulsion, for example Rhople~
P-376 as manufactured by Rohm & Haas Corp.
The opaeifier-filler, whieh serves both to enhance
th2 appearanee of the coating and to eooperate in the
uniform distribution and spaeed separation of the solid
color precursor in the CF eoating ~ust also be of neut~al
or alkaline eharacter. Such filler may suitably comprise
calcium carbonate such as Albaglos~as manufactured by
Chas. Pfizer & Co. This material has a pH o 9.4, a
spPeifie gravity of 2.7 and an average partiele size of
about .75 microns. Another suitable opaeifier-filler is
~NITANE 0-110 titanium dioxide as manufactured by the
Ameriean Cyanamid Company. This material has a ~inimum
TiO2 content of 99%, a pH of about 7.7 and a specific
gravity of about 3.9.
A presently preferre~ dispersant comprises sodium
salt of polymerie earboxylic aeid,-sueh as Tamol 850 as
manufactured by Rohm & Haas Company of Philadelphia, Pa.
This material has a pH of about 9.8 and a specifie gravity
at 25 of 1.19.
In the production of the above described receptor
coating for the CF sheets, a wa~er base intermixture of
preemulslEied polyvinyl aeetate, the dispersant and ~he
opaeifier-filler, suitably TiO2, is Eonned with eontinuous
agitation to e~eet a thorough dispersion o the filler and
-33-
~ 7~r~7J~ h7~Yr/<
.
,
~'7~
binder constituents therin. Into this mixture is intro-
duced the organic dyestuff dye prccursor chromogenic re-
agent component, again with continuous agitation to effect
a complete and uniform dispersion of the dye precursor
particles within the liquid intermixture.
The resultant e~ulsion-dispersion is readily and
selectively applied by conventional coating equipment in
the form of a thin film to the surface of a substrate,
such as a sheet or web of paper or of resinous film.
I~hen so applied, the water is then evaporated from the
mixture and residuP constitutes the improved CF coating.
By way of specific example, the following fo{mula-
tions have provided a CF sheet coating possessing the
~arked advantages hereinbefore set forth~
EXA~IP~E VIII
Wa~er 46.3
Dispersant (Ta~ol 850) 0.2
Titanium dioxide 5.5
Calcium carbonate 26.8
PolyvinyLacetate emulsion 19.2 (52% solids)
Crystal violet lactone 0.7
Red dye precursor 0.2
Blue/black dye precursor 0.7
Blue dye yrecursor 0.4
,
t~-a~ irk
.
~76~
EXA~IPLE IX
Water ~9.0
Disporsant (Tamol~850~ - 0.3
Calciu~ carbonate 17.0
Acrylic emulsion - 13.0 (50% solids)
Crystal violet lactone 0.5
Red dye precursor 0.2
Such CF shee~ coating may also comprise the solid
residue of an applied intermix of an evaporable solvent
earrier, suitably 35 to 75 parts of 95% ethyl alcohol and
at least about 3 parts of methyl ethyl ke~one, having dis-
solved therein at least about 5 parts of a binder, suitably
polyvinyl acetate. Added thereto is about O.Z parts of a
dispersant and about O~la/o oE dry potassium hydroxide to
pro~ide an alkaline cast to the mix and to minimize in-
advertcnt color reactions on the CF coated sheet. Also
included in the mix is about 5 parts of an opaci~ier-
filler, suitably finely divided titanium dioxide and about
~5 parts of calciu~ carbonate. Starch, such as corn starch,
may also be included, in lieu of or in addition to, portions
of opacifier-filler to serve as a spacin~ agent. While any
suitable chromogenic reagent material ~ay be employed,
satisfactory results have been obtained throu~h the i~-
eorporation therein o~ small but critical quantities of a
primary organic dyestuff dye precursor, such as about .5
to 2 parts of crystal violet lactone. Prcferably, additional
organic dyestuEE dyo precursor materials serving as color
modifier~ ancl inLenslficrs may al50 be includecl in the
.
-3~-
;~ tr 4~ rk
.
~ r
764~
ehromogenie reagent material, sui~ably red and blue/blaek
eolor organic dyestuff dye precursors.
A preferred binder material which is readily soluble
in the above described composite evaporable solvent
earrier comprises polyvinylacetate, suitably Vinae~B-15,
as manufaetured by Air Products & Chemieals Company.
A presently preEerred dispersant comprises sodium
salt of polymerie earboxylic acid sueh as Tamol 731 as
~anufactured by Rohm & Haas Company of Philadelphia, Pa.
The ehromogenic material may be of conventional
eharacter and a presently preferred material comprises
"Brilliant Violet Leuco" (CVL) as manufactured by the
~ilton Davis Chemieal Company of Cineinnati, Ohio.
In the produetion of the above described receptor
eoating for CF sheets, a liquid mixture is first formed
by (a) intermixing the ethyl alcohol and ~ethylethylketone
solvents; then (b) the polyvinyl aeetate binder material,
the dispersant, the potassium hydroxide (to cast the pH
of the solution to the alkaline side) are added with
eontinuous agitation until completely dissolved after ~hich
(c) the organic dyestuff dye precursor ~aterials are added
with continued stirring until dissolved. To the above
liquid mixture is then added the requisite amounts o~
ealeium earbonate and the titanium dioxide opacirier-
filler. Such addition should be aceompnnied by eontinuo~ls
~tirring of sueh eonstituents in the liquid vehicle to
obtain a uniform dispersion thereoE.
The above deseribed organic dyestuEf color preeursor
~36-
t, ~ ? ~ ~r l~
mat~rials are stable in alkaline media and, within theabove formul~tion ranges, such coating composition can
be used to coat most all paper substrates without any
effect on the reaction time or thc density of the image
produced when using -~he CB sheet coatin~s described above.
By way of specific example, the following formula-
tion ha~ provided a satisfactory CF sheet coating.
, '
EXAMPLE X
. Raw Materials .
Ethyl Alcohol (95Zo) 5~-3
Polyvinyl Acetate Beads 15.0
Potassium ~ydroxide Flakes 0.1
Tamo ~731S.D. Dispersant 0.2
Titanium Dioxide . 5.0
Cal~ium Carbonate 15.0
~ethyl Ethyl Ketone 10.0
Crystal Violet Lactone (CVL3 1.2
Red Color Precursor 0.6
Blue/Black Precursor 0.6
A further example of a satisfactory GF coating is
,
EXAMPLE XI
~et Bases /0
Ethyl Alcohol (95%) 40.0
Polyvinylacetatc 10.0
Tamol~?31 ~ispcrs~nt 0.
Potassium Hydroxide ~o.5
-37-
-~-t~ V~ k
7~
Titanium Dioxidc 17.0
Calcium Carbonate ~ 7.0
Corn Starch . 10.0
Methyl Ethyl Kctone 15S~
Crystal Violct l.actone (CVL) ~.2
Secondary Dye Precursors (mixed~ 0.1
Eaeh of the foregoing CF coating formulations
results in a CF coa~ing layer of neutral or alkaline
character, of acceptable appearance and having the color
precursor chromogenic reagen-t homogeneously distribu~ed
.. . . . .
there throughout. Such coatings are singularly abrasion
and odor free and have been formed of coating weights as
low as .2 grams/square meter. When used wi~h CB coatings
of the type herein described the image fontting reaction
proceeds ~ithout the color precursor chromogenic reagent
material in the CF coating being solubilized and ionized
the liquid electron accepting chromogenic r~agent materîal
emitted from the CB coating.
Having thus desribed our invention, we claim:
,
.
