U.S. patent number 3,911,171 [Application Number 05/428,781] was granted by the patent office on 1975-10-07 for thermographic recording process.
This patent grant is currently assigned to Agfa-Gevaert, a naamloze vennootschap. Invention is credited to Daniel Alois Claeys, Jozef Aime Dierckx, Wilhelmus Janssens, Raymond Gerard Lemahieu.
United States Patent |
3,911,171 |
Janssens , et al. |
October 7, 1975 |
Thermographic recording process
Abstract
A thermographic recording process in which a dye is produced by
bringing image-wise into reactive contact with the aid of heat a
dye precursor compound and a compound with acid reaction
corresponding to the following general formula: ##EQU1## wherein: Z
represents the necessary atoms to close an unsubstituted benzene
nucleus, a halogen-substituted benzene nucleus or a
nitro-substituted benzene nucleus, and R represents an
unsubstituted aliphatic group containing at least 4 carbon atoms, a
cycloaliphatic group or an aliphatic group substituted with
hydroxyl, with an etherified hydroxyl group or with an acyloxy
group.
Inventors: |
Janssens; Wilhelmus (Aarschot,
BE), Claeys; Daniel Alois (Mortsel, BE),
Lemahieu; Raymond Gerard (Mortsel, BE), Dierckx;
Jozef Aime (Hove, BE) |
Assignee: |
Agfa-Gevaert, a naamloze
vennootschap (Mortsel, BE)
|
Family
ID: |
26265115 |
Appl.
No.: |
05/428,781 |
Filed: |
December 27, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Sep 14, 1973 [GB] |
|
|
43336/73 |
Nov 30, 1973 [GB] |
|
|
55687/73 |
|
Current U.S.
Class: |
430/200;
250/317.1; 427/145; 250/330; 427/148; 427/150; 430/348 |
Current CPC
Class: |
C07C
205/57 (20130101); B41M 5/3335 (20130101) |
Current International
Class: |
B41M
5/30 (20060101); B41M 5/333 (20060101); C07C
205/00 (20060101); C07C 205/57 (20060101); B41M
005/18 () |
Field of
Search: |
;117/36.7,36.8,36.2
;250/317,330 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Herbert, Jr.; Thomas J.
Claims
We claim:
1. A thermographic recording process comprising producing a dye
image by bringing into image-wise reactive contact with the aid of
heat a dye precursor compound and a generally non-crystallizing
compound with acid reaction corresponding to the following general
formula: ##EQU11## wherein: Z represents the necessary atoms to
close an unsubstituted benzene nucleus, a halogen-substituted
benzene nucleus or a nitro-substituted benzene nucleus, and
R represents an unsubstituted aliphatic group containing at least 4
carbon atoms, a cycloaliphatic group or an aliphatic group
substituted with hydroxyl, with an etherified hydroxyl group or
with an acyloxy group.
2. A thermographic recording process according to claim 1, wherein
Z represents the necessary atoms to close a chlorine-substituted
benzene nucleus.
3. A thermographic recording process according to claim 1, wherein
R represents an alkyl group of at least 4 carbon atoms and
hydroxyl.
4. A thermographic recording process according to claim 1, wherein
the dye precursor compound and the compound with acid reaction are
carried on separate support sheets, one of said compounds being
transferred imagewise by heat from its support into reactive
contact with the compound on the other support sheet.
5. A thermographic recording process according to claim 1, wherein
the dye precursor compound and the compound with acid reaction are
carried on a common support with the compound with acid reaction
out of direct chemical contact from the dye precursor compound but
in such condition that reactive contact can be effected through
heating at a temperature above 60.degree.C.
6. A thermographic recording process according to claim 4, wherein
the dye precursor compound and the compound with acid reaction are
carried on separate support sheets and the latter compound at the
temperature reached in the image-wise heating is transferred from a
transfer sheet to a receptor sheet, which contains the dye
precursor compound to form a dye therewith.
7. A thermographic recording process according to claim 6, wherein
the dye precursor compound is applied in a coating containing a
non-acidic vinyl chloride homopolymer or copolymer.
8. A thermographic recording process according to claim 6, wherein
the dye precursor compound is contained in a binder coating in the
ratio of 1 part by weight to 1 to 20 parts by weight of binder.
9. A thermographic recording process according to claim 5, wherein
at least one of said compound with acid reaction and said dye
precursor compound is kept out of direct chemical contact by
enveloping the same in capsules or droplets from which the reactant
is set free by image-wise heating of the copy-sheet.
10. A thermographic recording process according to claim 5, wherein
the dye precursor compound and the compound with acid reaction are
kept out of chemical reactive contact at least below 60.degree.C in
separate binder layers.
11. A thermographic recording process according to claim 10,
wherein the top layer of the binder layers has been applied from a
solution in a volatile liquid, which is a non-solvent for the
binder of the subjacent layer.
12. A thermographic recording process according to claim 11,
wherein the dye precursor compound has been incorporated into a
first layer on the support of the copy-sheet in a vinyl chloride
homopolymer or copolymer binder and the compound with acid reaction
has been applied on top of said first layer from a solution of a
polymer in ethanol or methanol.
13. A thermographic recording process according to claim 10,
wherein the integral copy sheet is a clear transparent
heat-sensitive sheet material useful in the preparation of a colour
projection transparency by thermographic copying procedures and
includes a first layer containing the dye precursor compound in a
vinyl chloride polymer binder and a second coating bonded to said
first layer containing the compound with acid reaction in a binder
mainly containing cellulose nitrate.
Description
The present invention relates to heat-sensitive materials suited
for the recording and/or reproduction of information and to
recording processes wherein such materials are used.
In common thermography a heat-sensitive sheet is brought into face
to face contact with a graphic original that carries an image
formed of infrared radiation absorbing material. When the original
is exposed to infrared radiation, the image portions thereof are
heated selectively and cause by means of dye forming components
development in the adjacent heat-sensitive sheet of a colour
pattern corresponding to the original.
Transfer by heat of reactant material to a receptor sheet has been
described e.g. in the United Kingdom patent specification No.
973,965 and in the U.S. Pat. No. 2,770,534 and 3,476,578.
Heat-sensitive copy sheets in which the dye-forming compounds are
present in separate layers on the same support are described e.g.
in the U.S. Pat. No. 3,241,997.
Heat-sensitive copy sheets in which the dye forming reaction is
based on the reaction of an acid-reacting compound with a dye
precursor compound have been described in the United Kingdom patent
specification No. 962,545 and the U.S. Pat. No. 2,855,266.
From the U.S. Pat. No. 3,594,208 heat-sensitive film recording
materials are known in which premature reaction between a dye
precursor compound and a proton-producing compound is prevented by
applying the dye precursor compound in a binder layer different
from the binder layer containing an acid. In practice the
acid-containing coating contains cellulose nitrate as binder and is
applied as an outermost layer from a solution in a volatile liquid
vehicle which is a non-solvent for the vinyl chloride polymer
acting as binder for the dye precursor, the layer comprising the
dye precursor being applied as the first coating to the
support.
From the latter Specification can be learned that organic acid
reactants such as salicylic acid tend to crystallize from the
cellulose nitrate binder and form light-diffusing crystalline
deposits within the film. Hereby the clarity of the product is
reduced and image projection e.g. with overhead projector impaired.
A solution to that problem has been found by using the organic acid
and a plasticizer for the cellulose nitrate in a special percent by
weight ratio to the cellulose nitrate.
It has now been found that organic acids which are monoesters of
aromatic orthocarboxylic acids corresponding to the following
general formula: ##EQU2## wherein: Z represents the necessary atoms
to close an aromatic nucleus or ring system including such nucleus
or ring system in substituted form e.g. a benzene nucleus a
halogen-substituted benzene nucleus or a nitro-substituted aromatic
nucleus
e.g. a nitro-substituted benzene nucleus and represents an
unsubstituted aliphatic group containing at least 4 carbon atoms or
a cycloaliphatic group e.g. cyclohexyl or a straight line or
branched alkyl group containing at least 4 carbon atoms or an
unsaturated aliphatic group containing at least 4 carbon atoms or
an aliphatic group substituted with hydroxyl, with an etherified
hydroxyl group or with an acyloxy group e.g. an acetyloxy
group,
are particularly suited for use in thermographic recording
materials in which the thermographic image formation is based on
the production of a dye by the reaction of an acid with a dye
precursor compound.
Said acidic mono-esters have a sufficiently high acidity to cause
dye formation with dye precursors described in the Dutch Pat. No.
6,402,618 e.g. dye progenitors of the
N-bis(p-dialkylaminoaryl)methane type
N-(bis(4-dimethyl-aminophenyl) methyl)pyrrolidine spiropyran
compounds, Michler's hydrol and dye precursor compounds forming a
methine dye as described e.g. in the United Kingdom patent
application No. 59842/72 and No. 43337/73, which correspond to U.S.
applications Ser. No. 428,688, filed Dec. 17, 1974, and Ser. No.
428,805, filed Dec. 27, 1973, respectively.
The dye precursor compounds of these Applications are preferably
used for they yield highly fade-resistant dye images. Said dye
precursor compounds correspond to one of the following general
formulae: ##EQU3## wherein:
R.sub.1 represents a substituted aryl group e.g. a substituted
phenyl, tolyl, xylyl, naphthyl, biphenyl, or indenyl group at least
one substituent of said aryl group being an ether group R.sub.6
--O-- in which R.sub.6 represents a hydrocarbon group including a
substituted hydrocarbon group, e.g. an alkyl group including a
substituted alkyl group, e.g. a methyl, ethyl, propyl, hexyl,
dodecyl, or octadecyl group, a cycloalkyl group including a
substituted cycloalkyl group e.g. a cyclopentyl, cyclohexyl, or
methylcyclohexyl group, an aralkyl group including a substituted
aralkyl group e.g. a benzyl or phenethyl group, an aryl group
including a substituted aryl group e.g. a phenyl group or tolyl
group or a heterocyclic group including a substituted heterocyclic
group e.g. an indolyl, pyrryl, thienyl, furyl, carbazolyl or
indolizinyl group,
R.sub.2 represents a substituted aryl group e.g. a substituted
phenyl, tolyl, xylyl, naphthyl, biphenyl or indenyl group, at least
one substituent of said groups being an ether group R.sub.6 --O--,
in which R.sub.6 represents a hydrocarbon group including a
substituted hydrocarbon group, e.g. an alkyl group including a
substituted alkyl group, e.g. a methyl, ethyl, propyl, hexyl,
dodecyl, or octadecyl group, a cycloalkyl group including a
substituted cycloalkyl group e.g. a cyclopentyl, cyclohexyl, or
methylcyclohexyl group, an aralkyl group including a substituted
aralkyl group e.g. a benzyl or phenethyl group, an aryl group
including a substituted aryl group e.g. a phenyl group or tolyl
group or a heterocyclic group including a substituted heterocyclic
group e.g. an indolyl, pyrryl, thienyl, furyl, carbazolyl, or
indolizinyl group, or a ##EQU4## group in which Z represents the
necessary atoms to close a heterocyclic nucleus including a
substituted heterocyclic nucleus e.g. a nitrogen-containing
heterocyclic nucleus, the indolylidene-(2) group being an example
thereof,
R.sub.3 represents (1) a --XH or --X--R.sub.7 group, in which X is
oxygen or sulphur and R.sub.7 is an organic group e.g. an alkyl
group including a substituted alkyl group e.g. methyl, a cycloalkyl
group including a substituted cycloalkyl group e.g. a cyclohexyl
group, an aralkyl group including a substituted aralkyl group e.g.
a benzyl group, an aryl group including a substituted aryl group
e.g. a phenyl group, or an heterocyclic group including a
substituted heterocyclic group, (2) a ##EQU5## group wherein each
of R.sub.8 and R.sub.9 (same or different) represents an alkyl
group e.g. a C.sub.1 -C.sub.5 alkyl group, a cycloalkyl group, an
aralkyl group, or an aryl group or R.sub.8 and R.sub.9 together
represent the necessary atoms to close a nitrogen-containing
heterocyclic nucleus e.g. a piperidine, pyrrolidine, or morpholine
nucleus, or (3) a ##EQU6## group in which R.sub.10 represents an
alkyl group including a substituted alkyl group e.g. methyl,
propyl, hexyl, dodecyl, or octadecyl, or a cycloalkyl group
including a substituted cycloalkyl group e.g. cyclopentyl,
cyclohexyl, or methylcyclohexyl an aralkyl group including a
substituted aralkyl group e.g. benzyl or phenethyl, an aryl group
including a substituted aryl group e.g. a phenyl, tolyl, xylyl,
naphthyl, biphenyl or indenyl group, a heterocyclic group including
a substituted heterocyclic group e.g. a pyridyl, quinolyl,
benzothiazolyl, or phenothiazolyl group; the substituents being
e.g. alkoxy, fluoro, chloro, bromo, dialkylamino, acylamino, or
sulphamyl and in which R.sub.11 represents hydrogen or represents a
group enumerated in the definition of R.sub.10, or R.sub.11 and
R.sub.10 together represent a sultam group,
each of R.sub.4 and R.sub.5 (same or different) represents
hydrogen, a C.sub.1 -C.sub.5 alkyl group, a cycloalkyl group, an
aralkyl group e.g. benzyl or an aryl group e.g. a phenyl group,
and
each of m and n is 0 or 1, or
Y -- Ar -- CH = N -- R.sub.1
wherein:
Ar represents a bivalent aromatic nucleus e.g. phenylene,
R.sub.1 represents an aryl group including a substituted aryl group
e.g. a phenyl, naphthyl or biphenyl group, substituents of the aryl
group being e.g. an alkyl group, an alkoxy group, an alkoxycarbonyl
substituted alkoxy group, a carboxyl substituted alkoxy group, an
aryl sulphonyl substituted alkoxy group, a phenyl carbamoyl
substituted alkoxy group, an alkyl mercapto group, an alkylamido
group, or a halogen atom e.g. bromine, and
X represents an a ##EQU7## group wherein each of R.sub.2 and
R.sub.3 (same or different)represents an alkyl group e.g. a C.sub.1
-C.sub.5 alkyl group, a cycloalkyl group, an aralkyl group, or an
aryl group including said groups in substituted form or R.sub.2 and
R.sub.3 together represent the necessary atoms to close a
nitrogen-containing heterocyclic nucleus e.g. a piperidine,
pyrrolidine, or morpholine nucleus.
The diffusion mobility of said acidic monoesters in cellulose
nitrate is very low at room temperature (20.degree.C) but is
sufficiently high at copying temperature (80.degree.-150.degree.C)
so that its rapid transfer by heat into a dye precursor containing
layer is easily performed.
The acidic mono-esters that contain an aliphatic or cycloaliphatic
group of at least 4 carbon atoms do not or practically do not show
the unwanted crystallization in a cellulose nitrate binder and
yield therefore highly transparent thermographic colour-forming
film materials.
Preferred are the nitro-substituted mono-ester acids in which R
represents an aliphatic or cycloaliphatic group of at least 4
carbon atoms and those in which R represents an aliphatic or
cycloaliphatic group preferably of at least 4 carbon atoms and
substituted with an hydroxyl group. They do not or practically do
not show an unwanted crystallization in a cellulose nitrate binder
and yield therefore highly transparent thermographic colour-forming
film materials. The acidic mono-esters containing an R group
representing an alkyl group substituted with an hydroxyl group show
the highest resistance to premature dye formation.
Representatives of acidic mono-ester compounds suited for use
according to the present invention are given in the following
table.
__________________________________________________________________________
1 128 Cl-- COOH Cl-- COOCH--C.sub.2 H.sub.5 .vertline. CH.sub.3 2
Cl-- COOH oil at 20.degree.C Cl-- COOCH.sub.2 --CH.sub.2 --OH 3
Cl-- COOH resinous Cl-- COO--CH.sub.2 --CH.sub.2 --CH--CH.sub.3
.vertline. OH 4 Cl-- COOHCH.sub.3 125 .vertline. Cl-- COOCH.sub.2
--C--CH.sub.2 --OH .vertline. CH.sub.3 5 Cl-- COOH 48 Cl--
COO--(CH.sub.2).sub.5 --CH.sub.3 6 Cl-- COOH 122 Cl-- COOCH.sub.2
--CH--CH.sub.2 --CH.sub.3 .vertline. C.sub.2 H.sub.5 7 Cl-- COOH
104 Cl-- COOCH.sub.2 --CH--CH.sub.2 --CH.sub.2 --CH.sub.3
.vertline. CH.sub.3 8 Cl-- COOH 144 Cl-- COOCH.sub.2 --CH.sub.2
--OCH.sub.3 9 Cl-- COOH 165 CH.sub.2 --H.sub.2 C Cl--
COO--HC.angle..angle.CH.sub.2 CH.sub.2 --H.sub.2 C 10 Cl-- COOH
.+-.40 Cl-- COOCH--(CH.sub.2).sub.5 --CH.sub.3 .vertline. CH.sub.3
11 Cl-- COOH oil at 20.degree.C Cl-- COO--(CH.sub.2).sub.9
--CH.sub.3 12 Cl-- COOH oil at 20.degree.C Cl-- COOCH.sub.2
--(CH.sub.2).sub.8 --CH=CH.sub.2 13 COOH 128 C.sub.2 H.sub.5
COOCH.angle. CH.sub.3 14 COOH 134 CO--O--(CH.sub.2).sub.4
--CH.sub.3 .vertline. NO.sub.2 15 COOH 172 COO--(CH.sub.2).sub.5
--CH.sub.3 .vertline. NO.sub.2 16 COOH 162 COO--CH.sub.2 --CH.sub.2
--CH--CH.sub.3 .vertline..vertline. NO.sub.2 CH.sub.3 17 COOH oil
CO--O--CH--(CH.sub.2).sub.5 --CH.sub.3 .vertline..vertline.
NO.sub.2 CH.sub.3 18 COOH 122 CO--O--CH.sub.2 --CH.sub.2
--O--C.sub.4 H.sub.9 .vertline. NO.sub.2 19 COOH 133 COO-- CH.sub.2
--CH.sub.2 --OH .vertline. NO.sub.2 20 COOHCH.sub.3 170 .vertline.
CO--O--CH.sub.2 --C--CH.sub.2 --OH .vertline..vertline. NO.sub.2
CH.sub.3 21 COOHC.sub.2 H.sub.5 210 .vertline. CO--O--CH.sub.2
--C--CH.sub.2 --OH .vertline..vertline. NO.sub.2 C.sub.2 H.sub.5 22
COOH 90-100 CO--O--CH.sub.2 --CH.sub.2 --O--CH.sub.2 --CH.sub.2
--O--CH.sub.2 --CH.sub.2 --OH .vertline. NO.sub.2 23 COOH oil
CO--O--CH--CH.sub.2 --O--CH.sub.2 --CH--CH.sub.3
.vertline..vertline..vertline. NO.sub.2 CH.sub.3 OH 24
COO--(CH.sub.2).sub.5 --CH.sub.3 52 COOH .vertline. NO.sub.2
CH.sub.3 .vertline. 25 CO--O--CH.sub.2 --CH.sub.2 --CH--CH.sub.3 76
COOH .vertline. NO.sub.2 CH.sub.3 .vertline. 26 COO--CH.sub.2
--C--CH.sub.2 --OH oil .vertline. COOHCH.sub.3 .vertline. NO.sub.2
27 COOH oil O.sub.2 N-- COO--(CH.sub.2).sub.3 --CH.sub.3 28
COOHCH.sub.3 oil .vertline. COO--CH.sub.2 --C--CH.sub.2 --OH
.vertline. CH.sub.3 29 COOH oil COO--(CH.sub.2).sub.6 --OH
__________________________________________________________________________
The preparation of said acidic mono-ester compounds is illustrated
by the following two reaction schemes: ##EQU8## and preparation
receipts A, B, C and D.
Preparation receipt A
1 mole of nitrophthalic anhydride and 3 moles of the elected
alcohol, e.g. butanol, hexanol, isoamyl alcohol, are heated and
refluxed on an oilbath for 3 h. The anhydride dissolves upon
reaction. Thereupon the mixture is concentrated in vacuum.
Preparation receipt B
1 mole of tetrachlorophthalic acid, 3 mole of the selected alcohol
and 10 ml of strong sulphuric acid refluxed for 3 h. The acid
dissolves upon reaction. Thereupon the mixture is concentrated in
vacuum.
Preparation receipt C
1 mole of phthalic anhydride and 3 moles of the elected alcohol,
e.g. methanol, ethanol, isopropanol, iso-butanol, are heated and
refluxed on an oilbath for 3 h. The anhydride dissolves upon
reaction. Thereupon the pixture is concentrated under vacuum.
Preparation receipt D
1 mole of tetrachlorophthalic anhydride and 1 mole of acetic
anhydride are heated for 2 h at 150.degree.C on an oilbath. The
mixture is concentrated with a rotatory vacuum evaporating device
and thereupon 3.5 mole of the selected alcohol are added.
For the preparation of compounds 14 to 23 of the Table particularly
reference is made to J. Amer. Chem. Soc. (1937) 59, 1094.
The preparation of compound 25 is described in more details in Ber.
34, 486. Compounds 24 and 26 are prepared analogously.
The purification of the obtained mono-ester may proceed according
to different embodiments A, B, C or D.
Purification embodiment A
The reaction mixture is poured into water and extracted with
dichloromethane. The extract is washed several times with water and
thereupon dried with anhydrous calcium chloride. The solvent is
removed by evaporation under reduced pressure on a hot waterbath
and the residual product is used as such.
Purification embodiment B
The reaction mixture is concentrated in a rotatory evaporating
device under reduced pressure and thereupon poured into n-hexane.
The obtained precipitate is sucked off and used after washing with
n-hexane.
Purification embodiment C
The reaction mixture is concentrated by passing 3 times through a
high vacuum evaporating device type SAMBAY (trade name) whilst
heating proceeds on an oilbath at 100.degree.C and at a pressure
below 0.5 mm of mercury.
Purification embodiment D
The reaction mixture is poured into a mixture of 600 ml of methanol
and 60 g of potassium hydroxide. The little precipitate formed is
removed by filtration and the filtrate is concentrated in a high
vacuum evaporating device at 150.degree.C. The residue is treated
with dichloromethane and an aqueous 5N solution of hydrogen
chloride. The dichloromethane layer is separated and washed with
water till a neutral reaction of the wash water. After drying on
anhydrous calcium chloride the solvent of the extract is evaporated
under reduced pressure and the obtained residue is used as
such.
The acidic mono-ester compounds are suited for use in twosheet
thermographic recording systems as well as for use in an integral
copy-sheet containing on a same support the acid out of direct
chemical contact from the dye precursor at room temperature
(20.degree.-30.degree.C) but in such condition that reactive
contact can be effected through heating at a temperature above
60.degree.C.
According to one embodiment of a two-sheet thermographic recording
system the dye precursor compound is applied in such a condition to
or into a receptor sheet that the acid transferred from a
contacting image-wise heated transfer sheet can reach this compound
and react therewith to form the desired dye. The dye precursor
compound is preferably applied to a receptor sheet in a binder
coating, to which the acid, when heated, can be transferred from
the transfer sheet.
Suitable binders for the receptor sheet are non-acidic vinyl
chloride homopolymers and copolymers e.g. vinyl chloride copolymer
including from 75 to 95 % of vinyl chloride. Copolymers of vinyl
chloride and vinyl acetate are preferred copolymers. Other
copolymers of vinyl chloride e.g. with acrylonitrile are useful
likewise.
Polymers and copolymers, which as a result of their molecular
weight or composition become sticky on heating, have to be avoided
since they prevent the easy separation of the transfer sheet from
the receptor sheet.
The receptor coating or an adjacent coating may contain pigments
that give an overall colour to the receptor sheet e.g. for
obtaining more image contrast. For example, white pigments or
coloured pigments contrasting in colour with the dye image produced
may be incorporated too in the receptor sheet. Suitable pigments
for that purposes are, e.g. titanium dioxide particles. The
receptor coating may contain different kinds of fillers or grainy
material such as silica particles that, e.g., improve the
capability of being written on with pencil.
Further it may contain gloss-improving substances and anti-sticking
agents, e.g. metal soaps, aluminium stearate being an example
thereof.
The binder of the transfer sheet containing the acid is e.g.
ethylcellulose. It is, however, not absolutely necessary that the
transfer sheet contains a binder; the transfer sheet may e.g. be a
porous paper impregnated with the acid.
In the two sheet system good results have been obtained with an
amount of dye precursor compound in a ratio of 1 part by weight to
1 to 20 parts by weight of binder in the receptor sheet. The amount
of acid in the transfer sheet is preferably at least 0.1 g per
sq.m.
The supports of the receptor sheet and transfer sheet are
preferably flexible. Any kind of paper or resin support may be
used. However, if the adherence of the coatings is too low, a
suitable subbing layer or layers may be applied to the support. The
support of the receptor sheet has to be transparent for visible
light, when the copies obtained with the recording material have to
be used for projection e.g. in an overhead projector.
In the mono-sheet system different techniques of keeping the acid
reactant and the dye precursor compound out of reactive chemical
contact below 60.degree.C may be applied. For example, the
reactants are kept out of direct chemical contact by enveloping at
least one of the reactants in a capsule or droplet that contains a
shell or envelope of a material, normally a polymeric material or
wax that prevents the direct contact with the other reactant. The
capsule shell or droplet envelope is ruptured or softened by
heating, as a result of which the reactants come into reactive
contact.
The capsules or droplets containing a first reactant may be
dispersed in the paper mass of a paper sheet or in a binder or
binder system containing the second reactant in dispersed or
dissolved form.
The inner part of the capsule may be of organic nonwater-miscible
nature and the shell or envelope may contain or consist of a
hydrophilic material e.g. hydrophilic polymer or colloid that is
hardened optionally. Capsules of this type have been described e.g.
in the United Kingdom patent specification Nos. 1,281,492,
1,276,598, and 1,034,437.
According to another embodiment the contents of the capsule are
hydrophilic. For example the capsule contains water and a first
reactant dissolved or dispersed therein. The capsule shell has a
hydrophobic nature. The preparation of the latter type of capsules
has been described in the United Kingdom patent specification Nos.
1,048,696, 1,048,697, and 1,298,194 and in the published German
patent application No. 2,262,676.
Preferred integral copy sheets applied in the mono-sheet system
contain the dye precursor compound and acid reactant out of
chemical reactive contact at least below 60.degree.C in apart
binder layers, the top layer having been applied from a solution in
a volatile liquid, which is a non-solvent for the binder of the
subjacent other layer. Premature reaction is avoided effectively
when in a first layer on the support of the recording material a
vinyl chloride homopolymer or copolymer binder containing the dye
precursor compound and being insoluble or poorly soluble in ethanol
or methanol is coated, and the acid reactant and a polymer that is
highly soluble in ethanol, e.g. cellulose nitrate or polyvinyl
acetate, are incorporated into a layer bonded to the first layer.
The second coating preferably contains as binder medium cellulose
nitrate and a copolymer of methyl methacrylate and methacrylic
acid, the methacrylic acid content being preferably from 10 to 60 %
by weight.
If coated on a removable carrier, 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. The ratio of vinyl polymer to dye precursor
compound in the single sheet system material may be in the range of
about 20 to 3 parts by weight of dye precursor compound.
The amount of acidic monoester in the single sheet system material
is e.g. from about 0.1 to about 0.8 parts by weight with respect to
1 part of the binder.
Particularly preferred acid reactants are the compounds 24 and 28
of the Table.
If plasticizers are used in the layer 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 binder
e.g. cellulose nitrate. The plasticizers should therefore be
soluble in the same solvent as the binder. It should be essentially
non-volatile in normal storage conditions. Suitable plasticizers
for cellulose nitrate are "Butvar B-76" a polyvinyl butyral,
polyalkylene glycol, and camphor.
The following examples illustrate the present invention. The
percentages and ratios are by weight, unless otherwise
indicated.
EXAMPLE 1
A polyethylene terephthalate support of a thickness of 0.10 mm was
coated in the ratio of 33 ml per sq.m with the following
composition: ##EQU9##
After drying of the second layer at 50.degree.C the resulting
transparent recording material was exposed reflectographically to
infrared radiation, the second layer being held in direct contact
with the infrared-absorbing image markings of a printed text paper
original. In accordance with the infrared absorbing image markings
a blue dye has formed in the recording material.
In order to check the keepability of the recording material with
regard to crystallization of the acid, the material was stored for
5 days at 35.degree.C and 80 % of relative humidity and inspected
for crystallization. No trace of crystallization could be detected.
In a same material prepared, however, with 55 ml of a 10 % solution
of phthalic acid in methanol instead of 70 ml of said 10 % solution
of the acidic monoester crystallization has been very pronounced
already after 4 h of storage.
EXAMPLE 2
A polyethylene terephthalate support having a thickness of 0.075 mm
was coated in the ratio of 30 ml per sq.m from the following
composition:
5 % solution of copolymer of vinyl chloride and vinyl acetate
(85/15) in methyl ethyl ketone 800 ml 3 % solution of dye precursor
compound having the following structural formula: OCH.sub.3
OCH.sub.3 .vertline..vertline. H.sub.3 CO----CH----OCH.sub.3
.vertline. .vertline.OCH.sub.3 .vertline. OCH.sub.3 OCH.sub.3 in
methyl ethyl ketone 200 ml After drying at 50.degree.C a second
coating was applied in the ratio of 60 ml per sq.m from the
following composition : 5 % solution of cellulose nitrate in
methanol 300 ml 10 % solution of acidic compound 6 in methanol 100
ml methanol 150 ml isopropanol 450 ml
After drying of the second coating at 45.degree.C a transparent
recording material was obtained.
The recording material was exposed reflectographically to infrared
radiation, the second coating being held in direct contact with the
infrared-absorbing image markings of a graphic original.
A magenta image corresponding to these markings was formed.
No crystallization could be detected after a 10 days storage of the
recording material at 35.degree.C and 80 % relative humidity.
EXAMPLE 3
A polyethylene terephthalate support having a thickness of 0.075 mm
was coated in the ratio of 30 ml per sq.m from the following
composition:
10% solution of copolymer of vinyl chloride and vinyl acetate
(85/15) in methyl ethyl ketone 400 ml 1% solution of a dye
precursor compound having the following structural formula:
OCH.sub.3 H.sub.3 C.vertline. N----CH=N----OCH.sub.3 H.sub.3 C in
methyl ethyl ketone 100 ml 2.5% solution of a dye precursor
compound having the following structural formula: CH.sub.3 CH.sub.3
.vertline..vertline. NN .angle.C----C.angle. .parallel..parallel.
C--C=CH--CH--C .vertline. H.sub.2 C.angle. CH.sub.3
.vertline..vertline. H.sub.2 C.angle.CH.sub.2 C H.sub.2 in methyl
ethyl ketone 300 ml methyl ethyl ketone 200 ml
After drying at 80.degree.C a second coating was appllied in the
ratio of 60 ml per sq.m from the following composition:
5 % solution of cellulose nitrate in methanol 300 ml 10 % solution
of the acidic compound 13 of the Table in ethanol 90 ml methanol
150 ml isopropanol 460 ml
After drying of the second coating at 45.degree.C a transparent
recording material was obtained.
The recording material was exposed reflectographically to infrared
radiation, the second coating being held in direct contact with the
infrared-absorbing image markings of a graphic original.
A green image corresponding to those markings was formed.
EXAMPLE 4
A polyethylene terephthalate support of a thickness of 0.10 mm was
coated in the ratio of 33 ml per sq.m with the following
composition:
5 % solution of copolymer of vinyl chloride and vinyl acetate
(85/15) in methyl ethyl ketone 700 ml 3 % solution of a dye
precursor compound having the following structural formula :
CH.sub.3 CH.sub.3 .vertline. NN .angle..angle. C----C
.parallel..parallel. C--CH=CH--CH--C .vertline. N .angle. H.sub.2
CCH.sub.2 .vertline..vertline. H.sub.2 CCH.sub.2 .angle. C H.sub.2
in methyl ethyl ketone 300 ml
After drying a second layer was applied in the ratio of 70 ml per
sq.m from the following composition:
5 % solution of cellulose nitrate in methanol 500 ml 10 % solution
of the acidic mono-ester compound 24 of the Table in methanol 70 ml
methanol 430 ml
After drying of the second layer at 50.degree.C the resulting
transparent recording material was exposed reflectographically to
infrared radiation, the second layer being held in direct contact
with the infrared-absorbing image markings of a printed text paper
original. In accordance with those markings a blue dye has been
formed in the recording material.
In order to check the keepability of the recording material with
regard to crystallization of the acid, the material was stored for
15 days at 35.degree.C and 80 % of relative humidity and inspected
for crystallization. No trace of crystallization could be detected.
In a same material prepared, however, with 55 ml of a 10 % solution
of phthalic acid in methanol instead of 70 ml of said 10 % solution
of the acidic mono-ester crystallization has been very pronounced
already after 15 days of storage.
EXAMPLE 5
A polyethylene terephthalate support having a thickness of 0.075 mm
was coated in the ratio of 30 ml per sq.m from the following
composition:
5 % solution of copolymer of vinyl chloride and vinyl acetate
(85/15) in methyl ethyl ketone 800 ml 3 % solution of dye precursor
compound having the following structural formula : OCH.sub.3
OCH.sub.3 .vertline..vertline. H.sub.3 CO----CH----OCH.sub.3
.vertline..vertline..vertline. OCH.sub.3 OCH.sub.3 OCH.sub.3 in
methyl ethyl ketone 200 ml
After drying at 50.degree.C a second coating was applied in the
ratio of 60 ml per sq.m from the following composition:
5 % solution of cellulose nitrate in methanol 300 ml 10 % solution
of the acidic mono-ester compound 28 of the Table in methanol 100
ml methanol 150 ml isopropanol 450 ml
After drying of the second coating at 45.degree.C a transparent
recording material was obtained.
The recording material was exposed reflectographically to infrared
radiation, the second coating being held in direct contact with the
infrared-absorbing image markings of a graphic original.
A magenta image corresponding to those markings was formed.
No crystallization could be detected after a 10 days storage of the
recording material at 35.degree.C and 80 % relative humidity.
EXAMPLE 6
A polyethylene terephthalate support having a thickness of 0.075 mm
was coated in the ratio of 30 ml per sq.m from the following
composition: ##EQU10##
After drying at 80.degree.C a second coating was applied in the
ratio of 60 ml per sq.m from the following composition:
5 % solution of cellulose nitrate in methanol 300 ml 10 % solution
of the acidic mono-ester compound 23 of the Table in ethanol 90 ml
methanol 150 ml isopropanol 460 ml
After drying of the second coating at 45.degree.C a transparent
recording material was obtained.
The recording material was exposed reflectographically to infrared
radiation, the second coating being held in direct contact with the
infrared-absorbing image markings of a graphic original.
A green image corresponding to those markings was formed.
* * * * *