Note: Descriptions are shown in the official language in which they were submitted.
SPECIFICATION
This invention rela-tes to pressure sensitive
information transfer and duplicating systems and
particularly to improved chemical type transfer and
reproduction media for effecting duplicative image
transfer on sheet ma-terial in response to selectively
applied pressure and to processes for forming the same
Pressure sensitive image transfer media of
di`verse character are widely employed in the information
recording and duplîcating arts. Chemical type or so-
called "carbonless" pressure sensitive transfer and
duplicating systems, wherein a visable image ls ~ormed
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 no.rmally broadly comprise a substrate
supported coating that contains a first normally inactive
chemical reage:nt material that is selec-tively transferable
in response to applied pressure into a reaction provid~ng
and color producing relationship with a second normally
inactive chemical reagent material contained within or
comprising a second coa-ting disposed on the surface of
an interfacially contiguous second substrate. Conven-
tionally illustrative of such chemical type reproduction
systems
`.~, '~
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are transfer and duplicating systems wherein the rear surface on
one paper sheet substrate is provided ~ith a coating and which
sheet is then termed a "CB" (i.e. coated bacl;) sheet and the
front side of tbat same andlor a separate paper shee~ substrate
is provided with a coating which is then termed a "CFB" (i.e.
coated front and back) or "CF" (i.e. coated fr~nt) sheet, respect-
ively. When the coatings on a CB and a CF sheet are place~l in
interfacially contiguous relation and s-ubjecred to selectively
applied pressure, as by the pressure of a stylus or the impact
of a typewriter key on the obverse sur~ace of the CB sheet, the
operative and usually colorless chemical reagents i~ such coatings
are brought in~o 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.
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 material, such as
paper and the like due, at least in part, to their basic clean-
liness and to the fact that the color producing reagents are
inaeti~e until placed into operative co-reactive relationship in
response to selective application of pressure.
Although it was early recognized, as for example in
the Gill U.S. Patent 1,781,902, that many colorless chemical
reagents ~ere capable of producing a visable colored image upon
interreaction therebetween, most of the systems in wide commercial
usage at the present time employ a colorless organic dyestuff
as a dye precursor in encapsulated liquid form distributed
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within the CB sheet coating and an electron accepting material in
the CF sheet coating. I~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-reac~ing and color producing
relationship with the electron accepting material in the con-
tiguous coating on ~he CF sheet wi~h the resulting formation of
a duplicative ima~e thereon.
Some early and relatively recent patents that illus-
tratively disclose chemical type or so-called "car~onless"
transfer media employing encapsulated dye precursor materials
as the chromogen;c reagent in the CB coating and electron accepting
materials as the chromogenic 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 disclose
the dispositi~n of the dye precursor material in the CF coating
and encapsulated electron accepting material in the CB coating
include USP 3,787,325 (1974) to Hoover and USP 3,984,168 (1975)
to Brockett et al.
Such "carbonless" transfer media as presently commer-
cially employed and par~icularly those that conventionally
e~ploy an encapsulated type vehicle for one of the reactive
constitucnts, most usually an organic dyestuff, are not without
disadvantage. Among the recognized disadvantages of such media
are the fact that they are not only relatively expensive, re-
quiring specialized fabrica~in~ techniques, but are also undulypressure sensitive. Such undue sensitivity often results in
undesired premature transfer occasioned by inadvertent dye pre-
ursor release and transfer resulting from pressures normally
attendant packaging, handling and processing operations, spot
coating delineation, printing operations and t~te like, particu-
larly where multicopy manifoldlng operations are involved. In
addition,-such media are inherently subject to a progressively
increasing lack of copy definition as the number of desired
copies increases as well as by a fading of the copied image with
~inte.
The recently issued Shackle and Young U.S. Patent
No. 4,063,754 discloses the utilization of non-aqueous "hot
melt" coating compositions for CF sheets in a carbonless
transfer system incorporating acid reacting color developin~
reagent materials. Such patent describes, at considerable
length, numerous dlsadvantages attendant employing solvent or
water based compositions for effecting the deposition of such
carbonless coatings on substrates. Among such entlmerated
disadvantages are the health and fire hazards attendant the
release of generally volatile solvent vapors and the expenditure
of significant amounts of energy for the evaporation of the water
from aqueous 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 pro~lem of solvent safety hazards and
disposal of polluted water attendant preparation and clean-up
of such aq~teous coating compositions.
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A further recently issued paten~ to Shackle and
Young's assignee, i.e. U.S. Patent No. 4,I12,138, Davis and
Shackle for Mani~old Carbonless Fo~n and Process for the
Production Tnereof discloses the utilization of non-aqueOus,
solvent free "hot melt" coating compositions for CB sheets.
The specification of this patent similarly describes, at consider-
ablc length, the numerous disadvantages attendant employing solven~
or water based compositions for effecting the deposition of
carbonless coatings on substrates.
The Shackle and Young patent and the Davis and Shackle
patent stress the "non-aqueous" and "solvent free" character
of the assertedly novel hot melt coating compositions, 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 chromogenic reagent materials in ~he CB coating
although the process claims 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
accepting type of colGr developer, i.e. whether microencapsulated.
capsulated, dispersed or other form, is not particularly speci~ied.
It is relatively clear, however, that the described CF product
is intended for use with CB sheets incorporating an organic
dyestuff dye precursor in encapsulated form and, as such, repre-
sents an asserted improvement for the capsular type systems
presently in widespread commercial use.
The present day widespread commercial employ~ent o CB '`
sheets incorporating encapsulated or~anic dyestuff dye precursor
.
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materials, is, as mentioned above, not without disadvantage,
such as undue expense, premature activa~ion, limited reproduc-
tion fidelity in multiple copies and detrimental fading of the
reproduced images. Such disadvantages have been largely tolera-
ted because of thc absence of a viable commercially acceptable
alternative. As pointed out above, it was early recognized
that many chemical reagents were capable of producing visable
~uplicative images in chemical transfer paper usage. The afore-
mentioned Gill U.S. patent, for example, employed a member of
the gallo-tannic acid series as the chromogenic reagen~ in the
CB sheet coating in association ~ith a ferrous or ferric salt as
the chromogenic reagent in the CF sheet coating. In contxa-
distinctlon to the later Shackle and Young and Davis and Shackle's
disclosures, this system requires the presence of solvent at or
in the CF sheet coating for the color producing reaction to go
fo~ard and hence Gill teaches the inclusion of "a small percent-
age of glycerine or other non-drying substance, or a hygroscopic
ingredient" in the CF sheet coating. The need for the presence
of moisture ~nd the deleterious effects of such moisture on the
paper substrate was early recognized in the Gookin et al.
U.S. Patent No. 1,950,982, who provided a water impervious
film intermediate the substrate and the CB and C~ sheet coatings
and included in the :latter both magnesium chloride as chromogenic
reagent material and glua or gelatine as moîsture retaining
material. A somewhat different approach was followed in Groak
U.S. Patent No. 2,168,098, who disclosed a CB sheet coating
composed of a hard waxy substance having dispersed therein an
admixture of starch, a hydroscopic material, such as glycerine,
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and a color producing reac-tive subs-tance. In neither
of these approaches, however, was water included as a
necessary ingredient in -the coating composition and thus
basically conformed in such disclosure and teaching to
the later issued Shackle pa-~ents.
Some of -the aspects of the approach that was
early suggested by the Gill, Gookin and Groak patents
have recently reappeared in Austrian Patent No. 331,825
which issued March 25, 1976. In these disclosures, an
organic dyestuff dye precursor is dispersed in a binder
on the CF sheet and used in conjunction with an
essentially fully transferable CB sheet coating which
incorporates cla~ materials as the electron accepting
chromogenic reagent material, either alone or in
association with phenolic material and inorganic salts
of multivalent metals. Sol~ent, water based and hot melt
systems are specifically disclosed for the CB sheet
coatings. Significantly, howe~er, the hot melt CB sheet
coatings are all water free, again in conformity with
the Shac~cle teachings.
A later issued West German published patent
application 24 56 083.2 of September 2, 1976, as
referenced in U.S. Patent No. 4,096,314, discloses the
utilization of me-tal chlorides, preferably in combination
with urea or urea derivatives, as CF sheet coatings in
both solvent and aqueous systems. In association
therewith, there is disclosed the u-tilization of
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organic dyestuff dye precursors dispersed in a hot mel~ co~tir.g
medium as the CB coatin~. The preferred CF sheet coatings are
identified as those, for a water based coating, that contain zinc
chloride and urea and further include a metal stearate.
- While considerable effort has also been directed over
the past years to the improvement of encapsulation techniques
and to the provision of improved CB type coatings, a further
problem faced in this art is the ever increasi.ng expense of
co~ventionally employed dye precursor materials such as crystal
violet lactone and the like and the degradable sensi~ivi.ty there-
of to both light and water. These latter pose con~inuing and as
yet unsolved problems in the search for improved and lower cost
chemical carbonless transfer systems.
This invention may be briefly described, in its broad
aspects, as an improved chemical type transfer and duplicating
system comprising a hot melt type o CB sheet coating containing
and retaining discrete and selectively constituted liquid electron
accepting chromogenic reagerlt material and to methods for forming
the same. ~n its narrower aspects, the subject invention includes
a novel hot melt CB coating constituted of an intermiY.tUre of
natural and synthetic waxes containing and retaining discrete
microscopic droplets of a selectively constituted solution of a
metallic chloride, preferably zinc chloride in ~Jater suitably
buffered to minimize, if not effectively neutraliæe, the avail-
able acidic chloride content thereof uniformly distributed
therewithin as a color producing reagent. In operative association
therewith the invention includes a compatible and improved sol-
ven~ sy-tem type CF sheec coat Dg employing ~i (p-ph~nyl~mino)
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phenyl methanol as a dye precursor ~ype chromogenic reagent material
s~lcctively dispersed throughout an alkaline biased carrier film.
~ mong the manifold advantages attendant the practice
of the subject invention is the provision of improved low cost
carbonless transfer media that serve to provide markedly increased
numbers of duplicative copies with sharper, more intense and
highly smear resistant transferred images. Additional advantages
include compatability wi~h "one time" carbon papers and standard
printing inks; a permitted reduction 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 there-
of. Other advantages include the provision of a CB sheet coating
that can be readily striped and spot coated and which is recyclable.
Still other advantages include the provision of a CB sheet coating
that can be fabricated with minimal energy requirements on
conventional coating equipment requiring minimal capital investment.
Additional advantages attendant the practice of the subject
invention include the permitted use of a broadly acid responsive,
inexpensive and readily available pigment type product as a
dye precursor; the provision of an image receptor coating that is
effectively water and light stable and, absent interreaction ~ith
available acidic material, is highly resistant to premature
actuation normally resulting from extreme climatic conditions.
Further advantages of the disclosed combination of coa~.ings
include the provision of transferred images that are effectively
stable in character and a system which is operable at tempera-
turcs as lo~ as -30F. Still further advantages include the
provision of transfer and image receptor coatings of extencled
_g_ .
shel life that are markedly resistant ~e undesired premature
aetivation under conditions of high temperature and/or high humid-
;ty; that are characterized by reduced potential to irritate
sensitive skins and to corrode iron rollers and other components
of coating, printing and cullating apparatus; coatings that are
essentiaLly uncritical as to substrate character and which are
highly resi:stant to undesired transfer on printing presses,
collators and other equipment normally inciden~ to manifolding,
printing and packaging operations.
The principal object of this invention is the provision
of impro~red chemical type pressure sensitive transfer and re-
production system and to processes for abricating the same.
A furcher principal object of this invention is the
provision of an impro~ed hot melt chromogenic reagent containinO
eoating composition for CB transfer sheets in association with
an ine~pensive, light and water stable dye precursor containing
image receptor coating for chemical carbonless copy systems.
Another object of this invention is the provision
of an improved composite wa~ base hot melt type of CB sheet
eoating containing discrete droplets of a selectively con-
stituted water solution of a zinc chloride suitably buffered to
minimize, if not effectively neutralize, the available acidic
ehloride content thereof uniformly distributed therewithin as
a color producing reagent in association with an image receptor
eoating that employs tri (p-phenylamino) phenyl methanol as a
dye precursor type chromogenic reagent material thcrein.
A further object oE this invencion i5 the provision
of a water base zinc chloride solution for use as eleccron
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accepting chromogenic reagent material in carbonless transfer
systems that is effectively non-corrosive and non-irritating
and which is hig~ly resistive, when dispersed in a hot melt
carrier vehicle, to undesired premature image actua~ion under
conditions of high temperature and/or high h~midity in association
with a light and water stable receptor coating that employs
tri (p-phenylamino) phenyl methanol dispersed throughout an
alkaline biased carrier film as the chromogenic reagent therein.
Other objects and advantages of the subject invention
will become apparent from the following portions of this specifica-
tion which describe, in accord with the mandate of the patent
statutes, the principles of the invention and best mode presently
contemplated by the inventors 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 (4200~ and
14000X) of an improved hot melt CB coating formed and constituted
in accordance with the principles of this invention.
~ eferring to the drawings and initially to Figure 1,
there is provided an illustrative set of chemical type or carbon-
less transfer and reproduction media fabricated in accord with
the principles of the invention. As there shown9 suc~ sct includes
a CB sheet comprising a first planar substrate 10, suitably a paper
sheet or ~Jeb, having a thin solidified hot melt CB coating 12,
constituted as hereinafter described, disposed on the under-
surface thereof. Atlapted to be positioncd in interfacially con-
tiguous relation with the CB coating 12 on thc undersitle of
substrate 10 is a CF sheet coating 16 dîsposed on the upper
surface oE a second paper sheet substrate 14. Such subs~rate
14 may have its undersurface coated with a CB coating 12 and
thus constitute a CFB sheet, or may have an uncoated under-
surface and thus constitute a CF sheet. Alternatively, and
illustratively adapted to be disposed in interfacially contiguous
relation with either a CB coating 12 on the underside o~ the
"CFB" sheet 14 or with a CB coating 12 on the underside of the
"CB" sheet 10, is a separately illustrated "CF" sheet having a
CF coating 16 disposed on the upper surface of a third substrate
18. As will be apparent ~o those skilled in the art, any number
of intermediate CFB sheets or webs 14 rnay be interposed in
stacked relation to form a multilamina transfer and reproduction
system. Likewise, such multilamina se~ may include one time
carbon transfer sheets interposed with uncoated or CB coated sheets
or webs in a manifold arrangement in accord with the dictates
of the user thereof.
The novel and improved hot melt CB sheet coating
broa~ly comprises the resulting set or solidi,ied film from an j
applied and subsequently cooled emulsified liquid intermi~ture
of a melted low oil content wax carrier vehicle, preferably of
composite character, a melted synthetic flow wax and dispersant
and a chromogenic reagent solution oE zinc chloride dissolved
in water and suitably buffered to minimize, if not effectively
neutralize the available acidic chl.oride content thereof; said
emulsified intermixture also desirably having uniformly dispersed
therein small but critically limited amounts of a resinous film
forming a~cnt to promote film hardness and toughness, an isolating
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Agent to minimize, if not effectively preclude, undesired
transfer of the coating or portions thereof in response to un-
intentional pressure application and an opaciEier-filler to reduce
the gloss of the finished copy and preserve t~le appearance of the
substrate.
In its narrower aspects, the subject invention includes
a hot melt~CB sheet coating composition formed o 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
ehemically modified wax-like material having properties of a flow
agent, dispersant and emulsifier; and at least 10 to about 35
percent of a chromogenic reagent component in the form of a Lewis
aeid, desirably zinc chloride dissolved in an appropriate amount
o water necessary to form a relatively concentrated solution
thereof.
Optionally but desirably included in such CB sheet coating
composition for provision of an enhanced commercially attractive
product are one or more of the following additional constituents.
One sueh optional constituent comprises a film orming agent to
encourage the formation of a harder and tougher surface film after
setting and to thus minimize premature 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 mini~1~m
of about 2% up to an amount that deleteriously effects the flow
eharaeteristics of the mix. Another sueh optional but yet
desirable constituent comprises an isolating agent that is
essentially inco~.patible with the wa~ vehicle when solidified and
which serves to provide desirable surface characteristics to the
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resultan~ ~ilm, such as to minimize, if not effec~ively preclude,
undesired transfer of the coating or portions thereof in response
to unintentiona:l pressure application. The isola~ing agent may
vary in amount from a desira~le minimu~ of about 2% up to a ma-~i
mum of about 20%. A still fur~her optional but desirable con~
sti~uen~ is an opacifier-filler to enhance the appearance o~ ~he
coated surface of t~e CB sheet, such as by reducing the-gloss
thereof. As is well kno~n in this art, such opacifier-filler
may vary in amount required to provide a desired appearance,
typically about 5%, and may include titani~m dioxide, various
non-acidic high brightness clays, lithopone or other recognized
materi.als.
The mel~able wa~ vehicle may suitably comprise any of
the low oil oontent paraffin wa~es, microcrys~alline waxes,
carnauba, Montan or other conventionally emp]oyed low oil con-
tent vegetable, synthetic or mineral derived hot melt ~ax type
carrier vehicles. The presently preferred meltable wax vehicle is
a composi~e made up of abou~ 3 to 4 p2rts of a 101J oil con~en~
paraffin wax, intermixed with about 1 part or less o~ carnauba
wax. A prèsently preferred para~fin ~Jax is a low oil content,
hig~ melting point, fully re~ined paraffin ~ax, sui~ably Pace-
maker*53 as manufactured and sold by Cities Service Oil Co. of
Tulsa, Oklahoma. Suc~ wax has the following properties:
~elting point, AST~I, F 143-150
Melting point, ~ 146-153
Oil Content, Wt. % ma~ 0.25
Odorless
Viscosity, cs at 210F 5.5
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~eedle penetration a~ 77~F 13
Flash point F 485
O~ller suitable low oil conten~ hot melt ~7ax carrier
vehicles include alpha olefinic waxes, suitably ~6817 Synthetic
l~ax as ~vailable from Moore & Munger Inc. of Fairfield, Conne~ti-
cut; microcrystalline wax, suitably 195 Be Square ~ite*, available
from Pe~roli~e Corporations Bareco ~ivision or c ~ auba wax,
suitably Brazilian Refined available ~rom Baldini & Company of
Milburn, New Jersey.
Moore ~ Munger's ~6817 Synthetic Wa~ has the foll.owing
properties:
Congealing Point, F.,
AST~ D 938 162
Needle penetra~ion, mrn/10,
AST~ D 1321 77F. 14
Viscosity, Saybolt (a) ~10~.
(SVS), ~SI~l D 2161 52
~iscosity, Kinematic ~a) 210~F.
(Cs ). ASl~ D 445 8
Color, Saybolt, ASTM ~ 156 +~
Flash Poin~, F. (COC) 510
Bareco's 195 Be Square l~ite microcr~s~alline wax
has the Eollowing propertîes:
Melting Poin~, F. ASTM D 127 193/198
Penetration (a) 77F. ASI~I 6/7
Color AST~I D 1500 0.5/0.5
A pre:Eerred carnauba wax is Baldini's Brazilian Reflned
Carnauba wax that is possessed o the ollowlng properties:
Melting point, min., F. 180.5
~cid Number
minimurn 4~0
maY~imulrl 10 . O
*~rade mark
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Saponification Number
minim~n 78.0
maximum 88. n
The mel~able chemically modified ~ax-like material
having the desired properties of a flow agent, dispersant
and emulsifier most suitably comprises a material of the - .
type disclosed in U.S. Patent No. 3,941,608. Other sui~ably
chemically modi~ied wax materials having the somewhat similar
properties include modified synthetic waxes as disclosed in
U.S. Patent Nos. 2,890,124, 2,890,125 and 39163,548. ~ preferred
con~erciall.y available wax-lik~ ma~.erial ~ormulated in accord with
U.S~ Patent No~ 3,941~608 is ~7315 wax as sold by Moore & ~lunger,
Inc., o Fairfield, Connecticut. Such #7315 wax has the following
general properties:
Penetration Hardness
(FLP)I-22 5 Typical
Melting Point
(Fisher Johns) 144~ypical
Acid N~ber
(AST~I D 97~) 2 Typical
~ no~her suitable wa~-like material having somewhat
si.mi.lar properties as the foregoing suitably comprises an amide
of a fatty acid, such as Armid*HT as available from ~rmour
Industrial Chemical Company. Such Armi~*HT is possessed of the
following properties:
~mide % (min.~ 90
Iodine value
minimum
maximum 5
Free fatty acid ~/~
minimu~ -
maximum 5
-16-
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minimu~ . 9~
~.a~imum 103
r~he resinous film forming agent serves to enhance the
formati.on of a relatively hard and tough coating ~o minimize
undesired transfer of reagent material across t~ CB/CF inter-
face in the absence of intentional positive pressure application.
A suitable film for~ing agen~, which must be non~reactive with
chromogenic reagent component, desirably comprises a relatively
low ~elting point ethylene-vinyl acetate copolymer,.such as ~C-~0~*
as manufactured and sold by ALlied Chemical Corporat~on. Such
resin.ous ~ilm forming agent has the following properties:
Softening Point (AS~I E-28~ 20~F.
Hardness dmm (ASTM D-5) 9.5
Density ~/cc (ASI~I D-1505) ~.92
Viscosity (284F - Brookfield~ 55~ ~
~ nother suitable filTl formi.ng agent comprises oxidized
polyethylene, suitably AC-629 as manufactured and sold by Allied
Chemical Company. Such ~ilm forming agent has ~h~ following prop-
er~ies:
Softening Point 2~4F.
Hardness 5.5
Density g/cc 0.93
A~erage Viscosity CPS 284F lGO
Acid Number 15
The isolating agent cooperatively functions as b]ooming
agent to provide a lubricating and barrier surface to ~he
solidifi.ed coating. Such isolating agent, which should be
essentially incompatible with the wa~ carrier veh~cle when solidi-
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fied, so as to be selec~ively effective at the exposed sur~ace,
suitably comprises a small amount of stearic acid, desirably
HYSYRE~E 9718 as manu~actured and sold by the H~m~o Chem;cal
Company. Zinc stearate may also be employed.
The opacifier-filler, ~lich co.smetically serves bo~h
to reduce the gloss of the ~inished coa~ing and to preserve the
appearance of the substrate, suitably comprises inely divided
titanil~n dioxide such as UNIT~N~ 0-110 as manufac~ured and sold by
~merican Cyanamid Company. This material has a speci~ic gravity
of about 3.9 and is so finely divided 2S to leave only about a
0.10% residue on a 325 mesh screen.
The chromogenic reagent component comprises a con- -
centrated water base solution of ~inc chloride, suita~ly buffered
to minimize, if not e~Eectively neutralizeJ the a~ailab~e acidic
chloride conten~ thereof. Such solution is preferably made up
of about 2 to 4 parts of zinc chloride with about 1 part of -~.Jater
and which appxoaches a saturated solu~ion.
~ hile unbu~fered solutions of zinc chloride as the
chromogenic reagent have provided highly efEective image Lormation
in transfer coatings as formulated in accord -.~it~ the foregoing
disclosed ~ormulaLions, such have been subject, undèr extreme
climatic conditions o~ high temperatures and/or high humidity,
to the apparent genera~lon and emanation of hydrogen chloride.
~lthou~l the quantities of hydrogen chloride so generated, appear
to be minimal~ even ~mder such e~treme climatic conditions, the
apparent emanation thereo~ from the applied coating has resul~ed
in varying degrees o:E premature actuation of dye precursors over
the entire sur~ace oE an interfacially contiguous CF coating and,
18-
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depending on the ambient climatic condicions, in varying degrees
of actuation of such CF sheet. Such premature actuation is, of
course, highly undesirable as is thc generation of hydro~en
chloride with its potential to irritate sensitive skins and to
corrode iron rollers and other components of the processing equip-
ment under any set of climatic conditions.
In order eo neutralize, if not actually prevent, the
generation and emanation of such hydrogen chloride, a small amount
of a neutralizinO ammonium salt, suitably ammonium carbonate or
am~onium bicarbonate, is dissolved in the zinc chloride solution.
For a 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 date has generally
indicated that the addition of about 2 to 4% of ammonium carbonate
to zinc chloride solutions of the type herein disclosed results
in effective avoidance of the above problems in an improved
product.
While the mechanics of the reaction process are not
fully understood it is surmised that the ammonium salt operates
to neutralize or otherwise reduce the available active or
acid chloride ion content and to thus preclude its association
with avail~ble hydrogen ions. Also the possible availability
of ammonia in both the liquid and gaseous phase ~ay also contribute
to the neutralization of hydrogen chloride in both such phases.
Apart from the fore~oing, the additions of such
neutralizing ammoni~m salt has provided some totally unexpected
and, as yet, unexplai~able advantages and results. Such unexpected
results are a bleaching and a marked increase in the h~rdness of
,
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tbe solidified CB hot melt coating. Such increase in hardness
not Gnly functions to minimize pick off on processing components,
reduces the tendency to smear and provides sharper copy, but also
permits of significant reduction in the quantity of carnauba wax
that is otherwise desirably included therein. Carnauba wax is
not only one of the more cost significant components of the
coating but is also only obtainable from a foreign source of supply
who controls the ever increasing price thereof.
The unexpected bleaching action also enhances the appear-
ance of the product through an enhancement of the "whiteness" of
the coating.
A presently preferred ho~ melt CB sheet coating broadly
comprises the rPsulting set or solidified film from an applied
and subsequently cooled emulsified liquid întermixture 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 paraffin wax
intermixed ~Jith about 1 part of carnauba wax; about 2 to 5% of a
chemically modified synthetic flo~J wax and dispersant and about
25-35% of a chromogenic reagent solution of at least 2 parts of
zinc chloride dissolved in about 1 part of water buffered by
a small amount of ammonium carbonate as outlined above; said
emulsified intermixture also desirably having uniformly dispersed
therein abou~ 3 to 10% of a resinous film forming agent to promote
fil~ hardness and toughness, about 3-10% of an isolating agent to
minimize, if noe effectively yreclude, undesired transfer of the
coating or portions thereof in response to unintentional pressure
applica~ion and about 5% of an opacifier-filler to reduce the
gloss of the finished copy and preserve the appearance of tlle
substrate.
-20-
In the production of ~he above described preferred
CB sheet coating composition in accord with the principles
of this invention, the requisite amounts of ~inc chloride and water
are intermixed in a reaction vessel, suitably a steam jacketed
kettle having a 210F temperature setting, to form a hot con-
centrated solution thereof. To such solution is then added the
~eutralizing ammonium salt, preferably a~onium carbonate. To
such elevated temperature and now neu~ralized chromogenic reagent
solution, the requisite amounts of melted low oil content paraffin
wax and carnauba wax components of the composite ~ax 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 polyethylene filming agent and stearic acid
isolating a~en~ constituents are added in solid form with con-
tinual mixing until such consti~uents arP completely melted and
dissolved in the composite wax carrier vehicle. ~en 50 melted
and dissolved the opacifier-filler, preferably titanium dio~ide
is added and the entire mass thoroughly mixed at high speed for
30 to 40 minutes to form a selectivel~ constituted liquid hot
melt emulsion.
~ he resulting liquid hot melt emulsion is readily and
selectively applied in the form of a thin filml as for e~ample
at a coating weight of as low as 2 grams/square meter, by conven-
tional 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 coatcr or the like. The
so coated substrate is then passed over a chill roll or the like
-21-
to rapidly solidi~y or set the applied emulsified coating composi-
tion.
I~ contradistinction to the systems of the prior art
which were operatively dependent upon an Pxternal water source
(often humid air) to provide the necessary ionized zinc chloride
to react with the dye precursor, the system of the present in-
vention contains and retains water as an operative element in
discrete droplet liquid form within the solidified CB film and
-thus effects the selective transfer of ionized zinc chloride as
the operative entity.
Photomicrographs of coatings formulated in accord
with the principles of this invention are shown in Figures 2a
and 2b at magnifications of 4200X and 14000X respectively. These
photomicrographs clearly depict the presence of discrete, micro-
scopically sized zinc chloride am~onium salt solution globules
distributed throughout the coating. Most of such globules are
less than l micron in diameter with the great majority tnereof
falling between .25 and .75 microns. Such photomicrographs
further show that such zinc chloride solution globules peripherally
incorporate an interface layer or the like that differs, at least
in some ph~sical respects from bo.h the zinc chloride solution
globules and from t~e surrounding solidified wa~ material as
evidenced by the clearly different refractive indices involved.
The the ~bove ends, the foregoing described method of
formulation provides a selectively constituted emulsion in whlch
zinc chloride solution entities are thoroughly dispersed within
the film. The basic hygroscopic, if not actual deliquescent,
properties of zinc chloride and the nature of the resul~ant film
-~2- ~
~erv~ to min:imize, i~ not e~ectively prevent, w~iter loss in
storage with enhanced operating life for the product.
Anothe-r factor which contribu~es to the ~etention of the
dispersed zinc chloride solution in discre~e liquid c~lobular
:~orm within the CB film is the enhanced emulsific~i~n obtained
through the use o~ an essentially alkaline and a~ino containing
dispersa~ - flow wax consti~uen~ in association r~ith t~e relatively
high acid number wax and film forming components.
jBy way of further examples the Eollo~7inv ~ormula~ions
have provided CB sheet coating having in varying ~egree, the mani-
~old advantages earlier set forth.
,
EX~MPLE I
Paraffin Wax
7315 Wax ~.~
- ~C-400 Polyethylene 5 0
Stearic Acid 3 O
Titanium Dioxide 5
Zinc Chloride 30.
Water 10
EX~MPLE II
Paraffin Wax 4~.
7315 Wax 2.~
AC-629*Polyethylene 7.0
Titaniu~ Dio~ide 5 ~
Zinc Stearate lO.O
~inc Chloride 30.0
I~Jater 5-0
-23-
*trade mark
t
EX~IPLE II~ %
Paraffin Wax - 35.0
AC-400*Polyethylene lO.0
Zinc Chloride 20.0
Water - lO.0
~315 Wax lO.0
Stearic Acid lO 0
Ti~anium Di~xide 5 0
E ~IPLE IV %
Paraffin Wax 55.0
Carnauba Wax 20~0
Zinc Chloride 15.0
Water 5i~0
7315 Wax 2~0
Stearic Acid 3 0
EX~MPLE V
%
Par~fin l~ax lO 0
Microcrystalline ~Jax 3G 0
Stannous Chloride 3~ 0
Water lQ 0
7315 Wa~ ~ o
Stearic Acid 7 0
Titanium Dioxide lQ 0
-2~-
*trade mark
EX~`~LE VI
Carnauba ~ax 10 0
Alpha Olefin Wax 4~ ~
~C-629*Polyethylene 7 0
Ferric Chloride 20 ~
Water .lO~O
. 7315 Wax 3.0
Stearic Acid 5
Titanium Dioxide 5 i~
. ~y way of further preferen~ial example, ~.;he above formu-
lations, when buffered to minimizej if not effect~vely neutralize~ ~
the available acidic chloride content thereof, are modified as
j~:ol low5:
EX~IPLE IA
~/
Para~fin Wax ~2.
. 7315 Wax 2.
~C-400*Polyethylene 5.
Stearic Acid 2.
Titanium Dioxide 5.
Zinc Chloride 30.
Ammonium Carbonate 3.
Water lO.
EXA*.PLE II~ %
Paraffin Wax 38
7315 l~a~ 2.
*trade mark
- -
AC 62~ Polyethylene ~ 0
Titanium Dioxide ~.0
Zinc Stearate l~ 0
Zinc Chloride . 3~ 0
Ammonium Bicarbonate ~ 0
Water ~ 0
.
EX~IPLE IIIA
Para~fin Wax ~3~0
AC-40G~ Polyethylene l~ 0
Z;nc Chloride 2~ 0
Am~lonium Carbonate 2 0
Water 1~ 0
7315 Wax ~QI 0
Stearic ~cid lO i~0
Titanium Dioxide 5 ,0
EX~LE IVA
%
PararXin Wax 51 0
Carnauba Wax 20` 0
Zinc Chloride 15 0
Ammonium Carbonate 4 0
Water 5 0
7315 Wax ~ 0
Stearic Acid 3 0
-26-
*trade mark
`t~ r~
EX~r~PL E ~A %
Paraffin Wax ~-
Microcrystalline Wax ~ 0
Stannous Chloride 30~0
Ammonium ~icarbonate - 3 ~
Water . 10 Q
7315 Wax 3-0
Stearic Acid 7 0
Tii-anium Dioxide 1~.0
EX~LE V-.[A
Carnauba Wax 8 0
Alpha Ole~in Wax 38 0
AC-629 Polyethylene 7 ~
Ferric Chloride 2~ O
Ammonium Carbona~e 4 0
l~ater lO 0 -
7315 Wcl~; 3
Stearic Acid 5
T.i-~anium Dioxide 5 ~
The Eollowin~ Eormulations have provided highly preEerred
CB sheet coatings:
EYA~LE VII
/c~
Para~Ein Wax 39.0
Carnauba Wax 14.0
Zinc Chl.oride ~0.0
Water 10
*trade mark
f'
3L~3B~
731S l~a~ 2 0
~C-400 Polyethylene 5 0
~tearic Acid 5.0
Titanium Dioxide 5 0
E ~MPLE VIIA
%
Paraffin l~ax 36 0
Carnauba Wa~ 0
Zinc Chloride 20 0
Water IO O
Ammonium Carbonate 3 0
7315 Wax 2 0
AC-400*Polyethylene 5 0
Stearic Acid 5 ~
Titanium Dioxide S O
The impro~ed CF or image receptor coating comprises the
soli.d residue of an applied alkaline biased homogeneous mixture
o~ an evaporable non-polar hydrocarbon solvent, a chemically
neutral or alkaline resinous binder, an opaci~ier--filler and
tri (p-phen~lamirlo) phenyl methanol as a dye precursor type of
chromogenic reagent material. Such solidified CF coating i5 further
characterized by the presence of such dye precursor in solid form
and which dye precursor is insoluble in water or other polar
solvents. Optionally but desirably included therein is a dis-
persant to assist in the uniform dispersion of su~h dye precursor
throughollt the mix and a thickener to provide the requisite ~is-
cosity properties to facilitate the coatin~ of the mi~ in
accord with the particular requirements of the co~ing equip~ent
employed.
-28W
*trade maL^k
The evaporable liquid vehicle mus~ be of non-polar
character and a solvent for the tri (p-phenyla.tino) phenyl
methanol dye precursor component. Suitable non--po]ar organic
solvents include acetone, toluene, hep,ane ~nd naph~ha, with ~oluene
being presently preferred for use.
A presently preferred CF coating comprises the solid
residue of an applied intermi~ of an evaporable non-polar sol-
ven~, suitably 50 to 80 parts of toluene, having disso:Lved therein
at least about 7 to 20 parts of a chemically ne-ut~al or alkaline
resinous binder, suitably polyvinylacetate. Added thereto is about
.1 to .5 parts of a dispersant and about .1 to 4 parts of dry
potassium hydroxide to provide an alkaline bias to the mi~ and to
minimize inadvertent color reactions in the CF coated sheets. Also
included in the mix is about up to 45 parts of opacifier-~illers~
sui~ably up to abou~ 20 parts finely divided ~;itanium dioxide
and the remainder of calcium carhonate; and about .5 to 5 parts
of tri (p-phenylamino) phenyl methanol as the chromogenic reagent.
The nature of the binder is not attended ~7ith any
particular degree o~ criticality as long as it is of chemically
neutral or of alkaline character and func-tions as a binding
agent for the opacifier-filler and the color precursor, with both
of the latter being in solid form. A pre~erred binder material
hich is readily soluble in the above described evaporable non-
polar solvent carrier comprises polyvinylacetate, suitably Vinac*
B-15, as manufactured by Air Products & Chemicals Company.
A presently preEerred dispersant com?rises sodium salt
of polymeric carboxylic acid such as Tamol*731 as manuEactured
by Rohm & Haas Company of Philadelphia, Penns,lvania.
*trade mark
'3
~i
The opacifier-~iller, which serves both ~o enchance the
appearance of the coating and to cooperate in the uniform dis~
tribution and spaced separation of the solid co~or precursor in
the CF c02ting must also be of neutral or alkaline character.
Such ~iller may suitably comprise calclum carbo~a.te such ~s Alba-
glos as manufactured byr Chas. Pfizer ~ Co. This material has a
pH o~ g.4, a specific gravity o~ 2.7 and an aver~ge par~icle size
of about .75 microns. Another suitable opacifier-~iller employed
in conjunction with the above is Unitane 0-1110 ~itanium dioxide
as manufactuxed by the American Cyanamid Compan~. This ma~erial
has a mini.mum TiO2 content of 99%, a pH ~ about 7.7 and a
speciflc gravity o~ about 3.9. - .
As noted ahove, the chromogenic reagent .~mployed is
tri (p~phenyla~ino) phenyl methanol. Such chromogenic reagent,
as disclosed in the Pig~ent Handbook (Vol I) pu~lished by
John Wiley & Sons (Ed. Temple C. ~atton; 1973~, purportedl~ has
the following chemical structure:
o
~3 .
~3
The depicted incorporation of the hydro~rl group inter-
mediate the methane carbon atom and ~he phenyl gr~up, however, is
incorrcct and the correct structural formula thereof is
-30-
*trade mark
.
T
~ N ~ - c ~ ~
~.
.;~
~ '
Such text further indicates however that in any commer-
cially available supply ~hereof, that some lower phenylated product
having the follo~ing chemical composition is probably also presen~:
0~
~N ~ I ~ H ~3
~,, ' i
~H2
Such material may be described as biphenyl triamino
triphenyl methanol.
The dlscls)sed tri (p-phenylamino) phenyl methanol as
identified above is obtainable from The Sher~7in-WilLiams Company
and from BASF albei.t in an apparently somewhat impure or contaminated
form. As indicated in Sher~in-Williams technical bulletin AB-47,
the tri (p-phenylamino) phenyl methanol ~therein called "Spirit
Blue Carbinol Form") in the presence of an acld pH and a chloride
forms an intensely colored dye stuf~ Icnown as Solvent Blue 23
(CI No. 42760).
Transposition into or from its colorless for~ is solely
pH responsive, with intense color being produced in an acid pll
environment. Alkaline biasing of the coating is main~ained by
the selective utilization of .~lkaline biased constituent~ as set
-31-
.
forth above and by the inclusion of small amounts of potassiu~
hydroxide when necessary or desirable.
In the production of the above described receptor
coating for CF sheets, a liquid mixture is first formed by inter-
mixing the non-polar toluene solvent ~7ith the polyvinylacetate
binder material, the dispersant, the potassium hydroxide (to
cast the pk of the solution to the all~aline side) with continuous
agitation until all solids are completely dissolved after l~7hich
the organic dyestuff dye precursor material is added with continued
stirring until it is dissolved. To the above liquid mixture is
then added the requisite amounts of calcium carbonate and the
titanium dioxide opacifier-filler. Such addition should be
accompanied by continuous stirring of such constituents in the
liq~id vehicle to obtain a uniform dispersion thereof.
The specified dye precursor can be added as a powder,
or it can be added in its acidified colored form. If the latter
colored form is so utiliæed, the requisite alkaline cast of the
other constituents, including any necessary amounts of potassium
hydroxide, will cause the dye to revert to its colorless form
in the mixture.
By ~ay of specific example the following formulation
has provided an improved but yet inexpensive CF sheet coating.
E ~LE I
Toluene ~3.0
Potassium }Iydroxide 1.0
Calcium Carbonate 31.8
Tri (p-phenylamino) phenyl methanol 1.0
Polyvinylacetate 13.0
Dispersant 0.2'
-3~-
EXAMPLE Il
Toluene ~3.0
Potassium l~ydroxide 1.9
Calcium Carbonate 27.0
Titanium Dioxide 4.8
Tri (p-phenylamino) phenyl methanol 1.0
Polyvinylacetate 13.0
Dispersant 0.2
The foregoing CF coating formulation results in a CF
c~ating layer of neutral or alkaline character, of acceptable
appearance and having the color precursor chromogenic reagent
homogeneously distributed there throughout. Such coatings
are singularly inexpensive, abrasion and odor free and have
been formed of coating weights as low as .2 grams/square meter.
Used with the CB coatings herein disclosed the image forming
reaction proceeds without the color precursor chromogenic reagent
material in the CF coating being solubilized and ionized by the
liquid electron accepting chromogenic reagent material emitted
rom the CB coating and in a markedly improved chemical carbon-
less copy paper system.
Having thus described our invention,
-33-
.
.
