Note: Descriptions are shown in the official language in which they were submitted.
1~)63348
:~ ,
~ he present invention relates to heat-sensitive mate-
rials suited for the recording and/or reproduction of infor-
mation and to recording processes wherein such materials are
used.
In common thermography a heat-sensitive sheet is
brought into face to face contact wi-th a graphic original
that carries an, image formed of infrared radiation absorbing
material. ~heu the original is exposed to infrared radia-
tion, the i~age portions thereof are heated selectively and
cause development in the adjacent heat-sensitive sheet of
a colour pattern corresponding to the original.
~ ransfer by heat of reactant materials to a receptor
sheet has been desoribed,e.g.,in the United Kingdom Patent
Specification 973,965 filed Saptember 29, 1960 by Minnesota
Mining Manufacturing ~nd in the United ~tes Patents 2,770,534
.
of Walter S.Marx, Jr. issued ~ovember 13, 1956 and 3,476,578
of Erio Maria Brinckman issued November 4, 1969
Heat-sensitive copy sheets that change colour when heated
and in whioh the d~e-~orming reac~io~ is based on the reaction
20 of an acid-reacting compound with a dye precursor compound, have
been described in the Canadian Patent No. 787,326 filed }~y Allied .
Chem. Corp.
From the United States Patent 3,594,208 of Joseph A.Wiese,
Jr. and Donald J.Williams issued July 20, 1971 it is further
known to prevent premature reaction between a dye precursor and
a proton-producing compound by applying the dye precursor
GV.767C _ 1 ~ ~ ;
, - .
10~i334~3 ~
compound in a binder layer different ~rom the binder layer
containing an acid. In practice, the acid-ca~taining coating
is applied as an outermost layer from a solution in a volatile
liquid vehicle, which is a non-solvent ~or the vinyl chloride
polymer acting as binder for the dye precursor, the layer com-
prising the dye precur~or being applied as the first coating
to the support.
The dye precursorslu~ed in ~uch integral copy sheet
having a dual coating are N-bis(p-dialkylaminoary~methane -~
derivat~es. Ma~y of these derivatives are not completely co-
lOUrleS9 80 that images having a slightly coloured image back-
ground are obtained therewith.
An importa~t dema~d for copying materials in~ended for
projectio~ purposes is the production of highly fade-resistant
dye images, i.e. dye images, the dyes of which withstand con-
ti~uous exposure to light as applied e.g. ln a~ overhead pro-
jector.
In the pro~ection of multicolour images there is a
special ~eed for light resistant yella~d~es.
~here has now been found a thermographic recording pro-
cess in which essentially yellow azom~hine d~e salt~ o~ good
fade resistance are produ¢ed by bri~gin~ image-wise into
reaotive co~taot with the aid of heat a~ aoid-reacting compound
with a dye precur~or oompound oorre~ponding bo the ~ollowing
gener~l formula : -
~ - ~r - CE . N -
GV.767a - 2 -
;.,.- : ., . ... . ., . , ~. .. -, .; - ,. .: . . . . . . ... ..
~06334~3
wherein :
Ar represent~ a bivalent aromatic ~ucleus e.g. phenylene,
R1 represènbs an aryl group including a substituted aryl
group e.g. a phenyl, naphthyl or biphenyl group, substitu-
ents of the aryl group being e.g. an alkyl group, an alkoxy
group, an alkoxycarbonyl substituted alkoxy group, a car-
box~l substituted alkoæy group, an aryl sulphonyl substituted
alkoxy group, a phenyl carbamoyl substi~uted alkoxy group,
an alkyl mercapto group, an alkylamido group, or halogen
e.g. bromine, and
X represents an a ~fR2 group
wherein each of R2 and R3 (same or different) represents
an alkyI group e.g. a C1-C5 alkyl group, a cycloalXyl group,
an aralkyl group, or an aryl group including said groups
in substituted form or R2 and R3 together represen~ the
necessary atoms to close a nitrogen-co~nLng heterocyclic
nucleus e.g. a piperidine, pyrrolidine~ or morpholine nucleus.
Representatives of particularly suitable d~e precursor
compounds are given in the following table.
able
_ _ ~ _ ~ _ ~_ __ ____ ~lti
~o. Dye precursor compound point
- ~ - OC~3 - ~ i
H ~ C~ o-aH2-a~2-o- ~ 152
~ ~ l
Cl-aH2-aH22~ ~ ~ -~H=~- ~ _o-~cH2)1o-cooc2H566
2 _________________________ _________
(,V.767C ~ ~ - 3 -
.. . , : , .
~, , .
~63348
_ ~ . ,
___ _ _ ___
3 ~3- ~-N=HC- ~-~CH3 208
4 H3CC~- ~ -CH=l 1- ~ -S- ( CH2) 1 5_CH3 99 . ~ ;
XE3Cc~ -CH=~- ~ -O- ( CH2) 1 5-CX3 98
. ' '~' ' ''
~CH~ ~CH3 112 : . .
~ : ~
! OCE3 :
7 E3C~~ ~-CH=l~- ~-OCH3 145
. , .~
8 ~-so2-cH2-cx2-o- ~-~-CH~ CH3 154
9 Br-g~-~=CE-~-N~c~33 160
10 H3CO- ~-N-CE- ~-~CcHH3 ,140
~ E7= -e~-~O~E3 ¦ 122
_ ,X5C2 . .
______ ___ ________________________________________ ,_______
~V ~ 767 C - 4
' i
1C~63348
___________ ___ ___ _ _____ __ __ __ .. ._ _ __ _
12 ~ -~H-aO-CH2~0- ~ -~=CH~ C~ . 205
13 H3C- ~ -~=HC- ~ -N~CH33 120
CH~
4 H33C ~- ~ -CX=~ CH3 102 . . .
CX3 : .
15 ~ _~=XC~ o ~ ~7
. .;
16 CCl aCHH ~ 2C ~- ~ -CX=N- ~ -SCH3 114
: 17 HH3CC ~_ ~ -CH=~- ~ -0-(cH2)1o-cooH 140
. . .
: 20 18 ~ -N-XC~ a~2-coocE3 112
~aE ~ C~ ~2 . :~
'19 ~_~,~C- e~-~CH22_cH22_cN
L20 ~ _~aEa~ ~ -~CH33 ___________ L . . ~ .
______---- , . .
GV.767C - 5 - :
:,. ~
~ 6334~3 ~
___ ________ _____ _______ ________ _ _ __ _ _ ~_ __ __ ~ : .
~21 01-0~22-~20~ a~=~- ~ oa~ ¦ 83 ~
. ''',,'' ~ '
. 22 ~,CH- ~ -~`CE2~CH3 98
~ ;.-
23 ~=CH~ CH22-CE22-0~ 148
24 H3CO- ~ -CH=~ 'C2HH5 9o .
. . .,
25 ~C-aH2-cE2~ OH-N~ a~5 150
~ ~ " . ' "
~ ~20 26 HH30~ ~ -GE=~ a ~5 140
. . . .
27 H3C-OC-H~ HC- ~ -N~CCH3 215
. .
28 X30S- ~ _~=EC- ~ -~H33 i 150 ~
__ ___________________~ ______________________ ________ ____
GV.767a -- 6 -
: . :'. .
,!
~`
;3348
r~ -------
29~=CH- ~ ~ ~ CH22-CH22-Cl 104
~ .
3~- ~ -C~ C~3 1 1C7
1C ~ 312 ~_ ~ -CE=~- ~ -cc~3 ¦ 14C
-C~=~- ~ ~ - =C~ CX33 1 2 ~
~he preparation of the dye precur~or compounds is illustra-
ted by the following reaction scheme :
ethanol
X-Ar-CH0 + H2~-R1 ~ X-Ar-c~ R
and preparation receipt.
1 mole of the aldehyde a~d 1 ~le of the amine are dissol-
ved whilst heabing i~ 1200 ml to 2800 ml of etha~ol. 1 mole
of acetic a¢id is added dropwi~e to the obtained mixture o~er
a period o~ 10 min. ~he rea¢tion mi~ture i5 then allowed to `~
boil with reflux for 20 to 60 min. ~ter cooling the precipi-
tate is sucked off and washed with cold ethanol. Wh~lnecessary
the obtaine ~ roduct is recrystallized frcmmetha~ol or a higher
GV.767C - 7 -
1~633~ ~
al cohol .
~ or the preparation ~ co~p~unds 24 and 26 the acetic acid
has been replaced by 3 moles of triethylami~e.
~he reaction of acid with the above dye precursor com- -
pounds results in the production of protonated azomethine dyes
with light-absorptlon maxima that are more bathochromic than
in the non-protonated structures.
~ he above colour precursors are suited for use in a
thermographic two-sheet system using a transfer a~a receptor
sheet or for use in an integral copy-sheet co~taining on
a same support the proto~ donor or acid-supplying ~actant
out of direct chemical contact ~rom the dye precursor at room
temperature (20-30C) but i~ such a condition that reactive
contact can be effected through heati~ig at a temperature
above 60C.
Preferably acid reactants are used that evolve a volatile
acid or melt at the temperature applied in the thermogra~ic
proce~s. In this respect the following reactants are pre-
ferred : benzoic acid, succinic acid, citric acid, cyanoacetic
2C acid, gallic acid, salic~lic acid, 5-bromosaliaylic acid, a
sulfamic acid (i.e~ an organi¢ a¢id of bhe typc (R1.R2)-~-S020H
in which R'1 a~d R'2 are organi¢ groups), malei¢ a¢id~
2~4-dichloromaleio aoid~ pht~li¢ a¢id~ and th~ a~hydrides of
~hese a¢id~i. Further use can be made of the half-osters of
~ bivalent carboxylic acids. ~hese half esters may be formed
j in situ in the coating composition by dissolving the correspo~d-
GV.767a - 8 -
,
.. .. .
106334~
ing anhydrides in an alcohol, e.g. ethanol. ~xamples of such
half-esters are the monomethyl-, monoethyl- or monoisopropyl
esters of tetrachloroph-thalic acid.
Particularly suited are mono-esters of aromatic ortho-
carboxylic acids described i~ the Canadic~n Patent 1,034,379
issued July 11, 1978 to Agfa-Gevaer-t N.V. corresponding to
the following general formula :
1~ .
~ C - OH
Z ~L C - OR
wherein :
Z represents the ~ecessary atoms -to close an aromatic nucleus
or ring system including such nucleus or ring system in
substituted form, e.g. a benzene nucleus and a halogen- `
substituted benzene nucleus, and
R represents an aliphati~c or cycloaliphatic group of at least
4 carbon atoms or an aliphatic group substituted with
hydroxyl, an~eth-rified hydroxyl or a~ acyloxy group.
;Acids having a pKa value between 2 and 5 are generally e~fect-
ive.
Examples of salts that are reacting as an acid are mono-
sodium citrate, potassium aluminium sul~ate, aluminium sulfate,
potassium hydrogen tartrate, sodium hydro~en phosphate, ammo
' nium gallate, ammonium benzoate and dichlorobenzidinedihydro-
chloride.
i ` ` GV. 767C _ g
0 6 3 3 4 8
~ he anh~dride co~pound~ of succinic acid an~ o~ maleic
acid and some o~ t~ ammonium salt~ show little proton acti-
vity at room temperature~ but obtai~ i~creased activity at
elevated temperatures. Examples ~ solid prototropic compounds
that are useful for the~thermographic dye format'ion of the
present invention are saccharine, barbituric acid, and uric
acid. The~e co~pounds have the property of not bei~g a~
active proton-donor at room temperature, 80 that premature
colour formatio~ therewith i~ avoided. In thermographic -
heating conditions above 60C the~'become actively proton-
donating.
According to o~e embodiment of a two-sheet thermographic
recordin~ system the dye'precursor compound is applied in
such a condition to or into a receptor sheet that an æid
transferred from a contacting image-wise heated transfer
sheet can reach this compound and react therewith to form
the desired dye. ~he dye precur~or compound i9 preferably
applied to a support in a binder ¢oating, to which the acid,
when heated, can be tran~iferred from the transfer sheet.
Suitable binde~s for that purpose are vinyl chloride
homopolymer and copolym~rs e.g. vinyl chloride copolymer
including from 75 to 95 % of vin~l chloride~ Copolymers of
vin~l ohloride~m~omer and of vinyl acetate monomer are pre-
ferred copolymer~.
Gther copolymers of vinyl chloride e.g. with acrylonitrile
ar~ useful llkewise. Polymers and copolymers~ which as a re-
' .
~ GV.767C - 10 - ;
'1
~ ~ ' , . . . . .
~ 0 6 33 4 ~
sult of their molecular weight or composition become sticky
on heatin6 have to be avoided ~ince they prevent the easy
separation of the transfer sheet from the receptor sheet.
~he composition of the receptor sheet coating will
usually consist exclusively of non-acidic vinyl chloride
polymer or copol~mer and tke dye precursor co~pound, though
this is not absolutely necessary. Indeed, the receptor
coating or an adjacent coating may contain pig~e~ts that
give an overall colour to the receptor ~heet e.g. for obtain- ;
.
~ ing more ima~e contrast.
~or example, white pigments or coloured pi~menbs con-
trasting in colour with the dye image produced may be incor-
porated too i~ the receptor sheet~ Suitable pigments for that
purpose are e.g~ tita~ium dioxide particles. ~he receptor
coating may contain dif~erent kinds o~ fillers or grainy
material such as silica particles that e.g. improve the capa-
i bility of being written on with pe~cil.
~urther it may contain gloss-improving substance a~d
~ anti-sticking agents, e.g. metal soaps, aluminium stearate
3 20 being an example th~reo~.
In the two ~heet sysbem good results have been obtalned
with an amou~t of d~e pracursor compou~d in a ratio o~ 1 part
by wei~lt with re~pect to 1 to 20 parts by wei~ht o~ binder.
~he support of the re¢eptor!sheet is preferabl~ ~lexible.
Any kind o~ paper or resin support may be used. However~
i~ the adharence o~ the receptor coating is too low, a sui-
"I . , .
table subbing layer or layèrs ma~ be applied to the suppo~.
GV.767C - 11 -
, I .
~ 633~8
~he support has to be tran~p~rent ~or visible lightg when the
~opie~i obtai~ed with the recordin~ material have to be used
for projection e.g. in an overhead projector.
In the mono-sheet sy~tem different techniques of keeping
the acid ~a¢tant and the d~e procursor compound out of
reactive chemical contact beow 60C may be applied. ~or
example, the reactants are kept out of direct chemical con-
tact by e~veloping at least oi~e of the reactants i~ a capsule
or droplet that contains a shell or en~elope of a materlal,
~ normally a polymeric material or wax that preven~s the direct
~j ., .
contact with the other reactant. ~he capsule shell or droplet
en~elope is ruptured or softened by,heating, as a result of
whioh t~ reac~ants come into reactive contact.
~ he capsules or droplets containing a first reactant may
be dispersed in the paper mabs of a paper sheet or in a
~inder or binder system containing the second reacta~t in
dispersed or dissolved form.
~ he inner part of the capsule may be of organic non-
water-miscible ~ature and the shell or envelope may contain
or oonsist o~ a hydrophilic material e.g. hydrophilic polymer
or colloid that is hardened optio~ally. aapsules of this type
have ~en de~cribed e.g. in the U~ited Kin~dom Patent Specifi-
oatio~s 1~281,492 ~iled April 19, 1971 bg l~at.Ca~h Re~ister,
1,276,598 îiled ~ugust 3, 197~ by ~u~i Photo ~ilm and
1,034,437 flled ~ebruary 20, 1963 by Gevaert Photo-Producten
N .V .
GV . 767C _ 12
. . .
! ~
'`'I ~ .
~ 633~L~
Accordi~g to another embodiment the conte~ts of the capsule
are hydrophilic. ~or example the capsule co~tai æ water and a
first reàctant dissolved or dispersed therein. lhe capsule
shell has a hydrophobic nature. he preparation of the latter
,.
type of capsules has been described in the United Eingdom
Patents 1,048,696~ 1,048,697 both filed July 10, 1963 by
Ge~aert Photo Producten ~.V. and 1,29i~,194 filed ~ovember 20,
1968 by Gevaert-Ag~a ~.V. and in the Belgian Patent 792,550
~iled December 11, 1972 by Agfa-Gevaert ~.V.
Pre~erred integral copy sheets applied in the mono-sheet
system co~-tain the dye preourso~ compound i~nd acid reacti~nt
`, out of chemical reactive co~tact at least below 6~oa in apart
;I binder layers, thetop layer ha~ing been applied ~rom a solu-
tion in a volatile liquid, which i~ a non-solverLt for the
binder of the subjaoe~t other la~er. Premature reaotio~ is
~¦ avoided e~feotively when in a first layer on the ~upport
o~ the reoording material a vinyl ohloride homopol~mer or
oopolymer bi~der co~taining the dye precursor compound and
bel~g i~isoluble or poorl~ ~oluble in ethi~nol or methanol is
coated a~d the acid reactant a~d a pol~mer that is highly
~?l soluble in etha~ol e.g. oellulo~e ~itri~te or pol~vi~yl-
acetate axe i~oorporated i~ a layer bonded to the ~ixist
layer. aellulo~q nitrate conb~ g a small amou~t e~g.
2 % by weight o~ the oopolymer o~ methyl methaorylate and
methacrylic aoid is a preferred bi~der oompositio~ for the
la~er oo~ininS the a¢id rea¢ta~t. ~he methaor~lic açid content
I of the aopolymer is pre~erably ~rom 10 to 60 % by weight.
:: 1 .
GV.767C - 13 - ` `
, i ~ .
b
~ i33~ /
.;
~ .~ I . . ' .
~ rystallization of the acid reactant in said~ethanol-
solubIe binders may be avoided by incorporation therein of a
suitable amount of plasticizer e.g. as described i~ the
United States Patent Specification 3,~9~,208 as mentioned above.
If coated on a removable carrierj the very vinyl polymer
film containing the dye precursor compound may serve as the
backing but preferably it is permanently supported on a
separate heat-resistant`film e.g. a polyester resin film,
preferably a polyethylene terephthalate film. ~he ratio of
vi~yl polymer to d~e precursor compound in the sin~le sheet
system material may be in the range of about 20 to 3 parts
by weight of polymer to 1 part by weight of dye precursor
compound . i -
A'preferred acid ~aotant is phthallc anhydride.
If plasticizers are used in the lay~ containing the
acid reactant preference is given to those that do not
opacify the recording material, in other words those that
are compatible with the bi~der e.g. cellulose nitrate. ~he
plasticizer should there~ore be 801uble in phe same solvent
as the binder. It should be esse~ially non-volatile in
normal storage conditions. Suitable plasticizers for cellulose
nitrate are "Butvar B--76" ~rade Mark) a polyvinyl butyral, poly-
alkylene ~lycol, ~nd camphor.
~ he following examples illustrate the present inventionwithout, however, limiting it thereto. The percentages and
ratios are by weight, unless otherwise indicated.
GV.767~ - 14 -
,:j,
IFA~ `:
10633~8 :
Exam~l e . 1
A polyethylene terephthalate suppo~t o~ a thicknes~ of
0.10 ~m wa~ coated at a ratio of 33 ml per ~q.m with the
~ollowing compositio~ :
7 % solutio~ in methyl ethyl keto~o
of copolymer of vinyl ¢hloride and
vi~yl acetate (85/15) 700 ml
2 % solution i~ methyl eth~l ketone
of the dye preour~or compound 1 of the 300 ml
~fter dr~i~g a seco~d layer was applied at a ratio of
70 ml per sq.m from the following compo~ition :
5 % soluffDn in ethanol of polyvinyl
acetate 500 ml
10 % ~olution in ethanol of phthalic ~nhydride
(actually the ethyl half ester af ortho- 50~1
phthalic acid is formed in ~i~u)
ethanol 450 ml
~fter drying of the second layer at 50G the re~ulting
~ansparent recording material was exposed relecbographically -~
to infrared radiation? the second layer being held in direct
contact with the infrared absorbing image markings of a printed
tex~ paper origlnal. I~ accordance with the infrared absorbing
lm~ge markings a yelbw dye h~s been formed in the recording
material.
~he resulting copy was particularly ~uited ~or projection
with an overhead projector.
Example 2
.
A polyethylene tereph~halate support having a thickne~
of 0.10 mm wa~ coated at a ratio of 30 ~ per ~q.m from the
GV.767C ~ - 15-
.~ ~;''.
...
~633~
followi~g compositio~:
5 a/o sol~on in methyl eth~l keto~e
of copolymer of vinyl chloride and
vinyl acet~æ (85/15) 400 ml
2.5 % solution~nmethyl ethyl keto~e
of dye precursor compound Nr. 7 100 ml
After dr~i~g at 70C a second coating was applied at a
ratio of 20 ml per sq.m from the followi~g compositio~ :
5 ~ solution ln methanol of cellulose400 ml
10 % solution in ~ethanol of polyvi~yl
butyral 20 ml
10 % solution i~ ethanol o~ salicylic acid~2 ml ~ `
~ethanol ~ 118 ml
~ he recording material was dried and exposed re~lecto-
graphicall~ as de~cribed i~ Example 1.
A yellow image correspo~ding to the image marki~Bs of
the origi~al was formed.
~ he image was particularly suited for use i~ the projec-
tlo~ with overhead projector.
.
G~ . 767a - 1.6
