U.S. patent number 3,642,475 [Application Number 04/764,622] was granted by the patent office on 1972-02-15 for method of recording and reproducing information.
This patent grant is currently assigned to Gevaert-Agfa N.V.. Invention is credited to Daniel Alois Claeys, Marcel Nicolas Vrancken.
United States Patent |
3,642,475 |
Vrancken , et al. |
February 15, 1972 |
METHOD OF RECORDING AND REPRODUCING INFORMATION
Abstract
A heat-sensitive recording material of the type covered by U.S.
Pat. No. 3,476,937 and including a recording layer formed of a
dispersion of solid hydrophobic thermoplastic polymer particles in
a water-soluble hydrophilic binder is modified to include a
diffusion-resistant colorant material and a visible finely divided
material absorbing radiation and converting the same into heat,
such material being either chemically bleachable or soluble in an
aqueous liquid. The resultant heat-sensitive material is exposed to
radiation pattern and then contacted with at least one liquid to
bleach or dissolve the radiation absorbing and converting material
and to remove by washing the water-soluble portions of the
recording layer, the portions corresponding to the radiation
pattern having been rendered water-insoluble by the exposure step
but remain water-permeable to permit the radiation absorbing and
converting material to be bleached or dissolved by penetration of
the liquid.
Inventors: |
Vrancken; Marcel Nicolas (Hove,
BE), Claeys; Daniel Alois (Mortsel both of,
BE) |
Assignee: |
Gevaert-Agfa N.V. (Mortsel,
BE)
|
Family
ID: |
10434652 |
Appl.
No.: |
04/764,622 |
Filed: |
October 2, 1968 |
Foreign Application Priority Data
|
|
|
|
|
Oct 2, 1967 [GB] |
|
|
44,765/67 |
|
Current U.S.
Class: |
430/294; 101/467;
430/330; 250/318 |
Current CPC
Class: |
B41M
5/366 (20130101); G03F 3/10 (20130101) |
Current International
Class: |
B41M
5/36 (20060101); G03F 3/10 (20060101); G03f
007/10 (); G03c 005/00 () |
Field of
Search: |
;96/27,60,114.1,35
;250/65.1 ;117/36.1,36.2,63 ;101/467,470 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Martin; William D.
Assistant Examiner: Cabic; Edward J.
Claims
We claim:
1. A method of reproducing information comprising exposing to an
electromagnetic radiation pattern according to said information a
heat-sensitive recording material including a water-permeable
recording layer formed by a dispersion of hydrophobic thermoplastic
polymer particles in a continuous phase of a water-soluble
hydrophilic binder in a ratio by weight of at least 1:1, said
hydrophilic binder continuous phase also having distributed
therethrough a water-insoluble colorant material resistant to
diffusion from said continuous phase and a water-soluble visible
finely divided material absorbing radiation and converting the same
into heat, said recording layer after said exposure being
water-insoluble but permeable to aqueous liquids, and after said
exposure contacting said exposed recording layer with at least one
aqueous liquid to dissolve said water-soluble radiation absorbing
and converting material and to remove by washing the water-soluble
portions of said layer, whereby the remaining portions form a
colored relief image corresponding to said radiation pattern.
2. A method of reproducing information according to claim 1,
wherein the dispersion consisting of hydrophobic polymer particles
in the hydrophilic binder medium i present in the recording layer
for at least 50 percent by volume.
3. A method of reproducing information according to claim 1,
wherein the hydrophobic polymer particles are latex particles solid
at room temperature and are present in said continuous hydrophilic
binder medium in an amount by weight of at least 3:2.
4. A method of reproducing information according to claim 1,
wherein said water-soluble colorant material is a diffusible
anionic or cationic organic dye containing water-solubilizing salt
or acid groups.
5. A method of reproducing information according to claim 1,
wherein the exposure is a short-duration high-intensity imagewise
exposure.
6. A method of reproducing information according to claim 5,
wherein the exposure lasts no longer than 10.sup.-.sup.1 sec.
7. A method of producing information as a multicolor print
according to claim 1, wherein said recording material includes four
of said heat-sensitive recording layers applied thereon separately,
said layers respectively contain a black, a cyan, a magenta, a
yellow pigment, each layer containing a water-soluble dark colored
substance which absorbs at least a part of the copying light and
transforms it into heat and each layer is separately exposed in
turn to light through a proper black-and-white screened selection
negative of the color original to be reproduced and each layer
following its exposure and before application to the next layer is
treated with an aqueous liquid to remove the nonexposed portions
and dissolve out the dark colored substance.
8. The process of claim 1 wherein the same aqueous liquid serves to
dissolve said water-soluble radiation absorbing and converting
material and to remove said water-soluble portions of said
layer.
9. The process of claim 1 wherein the water-soluble portions of
said exposed recording layer are first washed away with water and
said water-soluble radiation absorbing and converting material in
the remaining water-insoluble portions of said layer is then
dissolved by contact with an aqueous solution.
10. The process of claim 1 wherein said colorant material is a
diffusion-resistant colored or black pigment or dye.
11. A method of reproducing information comprising exposing to an
electromagnetic radiation pattern according to said information a
heat-sensitive recording material including a water-permeable
recording layer formed by a dispersion of hydrophobic thermoplastic
polymer particles in a continuous phase of a water-soluble
hydrophilic binder in a ratio by weight of at least 1:1, said
hydrophilic binder continuous phase also having distributed
therethrough a colorant material resistant to diffusion from said
continuous phase and a finely divided particles of visible silver
metal absorbing said radiation and converting the same into heat,
said recording layer after said exposure being water-insoluble but
permeable to aqueous liquids, and after said exposure contacting
said exposed recording layer with an bleaching solution for said
silver converting the same to a water-soluble form and with a
liquid to remove by washing the water-soluble portions of said
layer, whereby the remaining portions form a colored relief image
corresponding to said radiation pattern.
Description
The present invention relates to methods for recording and
reproducing information and to materials for use in said methods.
The invention more particularly but not exclusively relates to a
method for recording imagewise or recordwise modulated light
energy, which is transformed into heat in a heat-sensitive
recording material.
It has been proposed to record information by informationwise
heating a recording layer composed so that under the action of such
heating it undergoes a change in water-permeability. In consequence
of the informationwise heating the information is therefore
recorded in terms of a difference in the water-permeabilities of
different areas of the recording layer.
Certain recording materials for use in that way, and recording
processes using such materials, are described and claimed, inter
alia, in Belgian Pat. specification No. 656,713 and in the
published Dutch Pat. application No. 6,606,719 corresponding to
U.S. Pat. No. 3,476,937. Such recording materials have recording
layers comprising a network of hydrophobic thermoplastic polymer
particles, solid, at room temperature, or comprising hydrophobic
thermoplastic polymer particles dispersed in a continuous phase
hydrophilic binder medium.
Other recording materials in which information can be recorded in
terms of a differential water-permeability by informationwise
heating a recording layer are described and claimed in Belgian Pat.
specification Nos. 682,767 and 683,054. In such recording materials
the recording layer is composed wholly or mainly of gelatin which
becomes more water-soluble and consequently more water-permeable,
when sufficiently heated.
An interesting development of this principle of recording
information is the use of a recording material which contains one
or more distributed substances capable of absorbing electromagnetic
radiation, e.g., infrared radiation and/or visible light, and in
which the recording layer becomes heated by virtue of radiation
absorption by such substance(s) when the recording material is
irradiated. The aforesaid earlier patent specifications include
descriptions of recording materials useful in that way, and further
such materials are described in Belgian Pat. specification No.
681,138. When a radiation-absorbing substance is distributed in the
recording layer, the informationwise heating of the recording layer
which brings about the water-permeability or water-solubility
differentiation can be achieved by informationwise exposing the
recording material to sufficient radiation of the appropriate
type.
The presence of the radiation-absorbing substance(s) in the
aforesaid recording materials makes the record visible, provided
the recording material is treated, following the informationwise
heating, to remove the recording layer selectively in dependence on
the water-permeability pattern. It will be apparent however that
the result of forming a visible record in that way is that the
color and optical density of the record is determined by the
substance(s) used for absorbing the electromagnetic radiation. It
is also possible, following the informationwise heating of the
layer to allow a colored substance to penetrate differentially into
the layer according to the water-permeability pattern, but the
still present radiation absorbing substance(s) impair the color and
contrast of the developed record.
The present invention provides an improved process, according to
which radiation-absorbing substance(s) used for heat generation in
the recording layer is or are entirely or substantially entirely
removed from the recording layer after a record in terms of a
water-permeability differentiation has been formed.
The present invention includes any information recording process
wherein a recording layer which is composed so that it undergoes a
change of water-permeability under the action of heat and which
contains a substance or substances which can absorb certain
electromagnetic radiation, is informationwise heated by irradiation
of such layer with electromagnetic radiation which is absorbed by
said substance(s) so that said information is recorded in terms of
a difference in the water-permeabilities of different areas of such
layer, and the said radiation-absorbing substance(s) is or are then
bleached in or leached out of said layer without destroying the
water-permeability differentiation.
The invention also includes, by way of modification, any
information-recording process as above defined but wherein
following the informationwise heating which establishes the record
in terms of a water-permeability differentiation, selected parts of
the recording layer are removed depending on their
water-permeability, and the radiation-absorbing substance(s) in the
remaining portions of the layer is or are bleached in or leached
out from such remaining portions.
The composition of the recording layer may be such that after the
bleaching or leaching operation the recording layer is
substantially colorless. The latent record can be subsequently
developed by allowing a colored developer, e.g., a dye solution, to
penetrate into the layer or the remaining portions thereof.
Obviously a wide choice of developer is available since the only
function of the developer is to provide the required color in the
developed record.
According to preferred embodiments however the recording layer
initially contains not only the necessary radiation-absorbing
substance(s) but also a colored ingredient or ingredients providing
the final record color or colors, the nature of such ingredient(s)
being such that the radiation-absorbing substance(s) can be
bleached in or leached out of the recording layer without affecting
the said colored ingredient(s).
The present invention also includes any recording material having a
recording layer which is composed so that it undergoes a change of
water-permeability under the action of heat and which contains (a)
at least one distributed substance capable of absorbing certain
electromagnetic radiation and thereby yielding heat to bring about
a said change in water-permeability, and (b) at least one coloring
ingredient or color-former of such nature that it can remain in the
layer substantially unaffected if the latter is treated with an
appropriately selected liquid composition which bleaches or leaches
said radiation-absorbing substance in or from the layer. The
expression "color former" includes a mixture of components capable
of entering into a color-forming reaction in the layer when heated
or subjected to other conditions.
Heat-sensitive recording materials useful in carrying out the
present invention include materials containing a hydrophilic
colloid and which in itself or by the action of substances
dispersed or dissolved therein become less water-permeable, as
described e.g., in the Belgian Pat. specification Nos. 656,713,
676,329, 674,218, 681,138, 683,053 and 705,529 and in the published
Dutch Pat. application No. 6,705,963.
Other heat-sensitive recording materials useful in carrying out the
present invention include materials containing a hydrophilic
colloid, more particularly gelatin and preferably gelatin of the
type described in the United Kingdom Pat. specification No.
985,933, which by the action of heat becomes more water-soluble and
consequently more water-permeable, as described in the Belgian Pat.
specification No. 682,767.
According to a preferred embodiment a recording material is used
comprising at least one heat-sensitive layer undergoing a decrease
in permeability to water when heated, and incorporating particles
composed wholly or mainly of a hydrophobic thermoplastic polymer.
Said layer contains preferably a major part by volume of a
dispersion of said particles in a hydrophilic binder in a weight
ratio greater than 1:1 as well as an amount of a colored substance
which absorbs infrared radiation and/or visible light and converts
a substantial part thereof into heat, said substance being capable
of being bleached or leached out from the portions of the recording
layer having a reduced permeability to an aqueous liquid
penetrating the imagewise heated recording layer all over its
surface.
Suitable hydrophilic binders and thermoplastic polymers for
preparing such a recording material are described in the Belgian
Pat. specification Nos. 656,713 and 681,138.
Preferably, the heat-sensitive layer used in the present invention,
at room temperature incorporates solid particles of hydrophobic
thermoplastic polymeric material, which has been dispersed in an
aqueous medium by means of a dispersing agent. The sensitivity of
the recording layers depends on the concentration of the said
thermoplastic hydrophobic polymer particles in the hydrophilic
binder and preferred compositions contain these particles in a
weight ratio of at least 3:2. The said recording layer for reason
of sensitivity preferably consists for at least 50 percent by
volume of the dispersion of said hydrophobic polymer particles in
the hydrophilic binder. As a matter of course the sensitivity of
the recording layer also depends on the concentration of the
light-absorbing heat-generating substance(s) and its (their)
absorption spectrum. Preference is given to dark substances, which
absorb electromagnetic radiation in a visible part of the
electromagnetic spectrum as large as possible, and preferably in
the infrared region (wavelength beyond 700 nm.). If the recording
material is to be used in a reflex exposure, the concentration of
heat-generating substances should be such that the optical density
to applying light preferably is comprised between 0.2 and 0.8.
Recording materials applied in direct exposure preferably possess
an optical density of at least 1. The sensitivity of the preferred
heat-sensitive layers is such that an exposure energy of only 0.3
watt.sec./sq.cm. is required for producing a practical useful
differentiation in water-permeability.
The light-absorbing substances wherein by exposure to visible
and/or infrared light heat is generated are preferably bleachable
substances e.g., bleachable metals or dyes or dyes of the
water-soluble type, e.g., dyestuff salts, or are easily soluble in
aqueous compositions containing a certain amount of a
water-miscible organic solvent, e.g., ethanol, an acid which
improves the removal of basic dyestuffs, or a base which can
improve the removal of acid dyes.
Light-absorbing heat-generating substances which are suited to be
used according to the present invention are preferably colored
ionic substances with a high rate of diffusion in gelatin coatings
swollen in water. The measurement of dye diffusion rates in swollen
gelatin coatings has been described by R. B. Pontius and I. A.
Wenrich in Phot. Sci. and Eng., Vol. 2, No. 3, Oct. 1958, p.
131-135. Preferably anionic or cationic nondiffusion resistant
organic dyes containing water-solubilizing salt or acid groups are
used, e.g., acid or neutralized acid dyes used in the hydrotype
printing process for the production of imbibition prints. Examples
of such dyes can be found in the U.S. Pat. specification No.
2,892,822. It is to be understood that mixtures of such dyes can be
used too.
In the recording, preference is given to a short-duration
high-intensity imagewise exposure. An advantage of this type of
exposure is that it yields a reproduction with great image
sharpness, since the lateral diffusion of heat is limited here to a
minimum value. Thus, it i preferred in carrying out the exposure
step to apply an imagewise or informationwise exposure lasting no
longer than 10.sup.-.sup.1 sec. The exposure must be sufficiently
intense in order to effect the desired decrease in
water-permeability in the exposed areas.
Suitable radiation sources for producing copying light of high
intensity in a rather short period of time are so-called
flash-lamps. Good results are obtained with xenon gas discharge
lamps with an exposure time of 10.sup.-.sup.5 to 10.sup.-.sup.2.
These flash lamps emit a larger part of visible light than of
infrared radiation. Details on a copying device containing such a
discharge lamp can be found in the Belgian Patent Specification
664,868 and in the published Dutch Pat. application No.
6,808,648.
If the emitted energy is focused onto a relatively small
heat-sensitive area, e.g., of the size of one picture of a motion
picture film a gas discharge lamp with a relatively low energy
output can be used. E.g., for copying on an area of 19 mm. .times.
35 mm. a flash lamp with an energy output of 40 watt.sec. will
suffice.
Self-evidently, the heat-sensitive surface layer before or during
the imagewise exposure to heat-generating radiation can be
subjected to an overall heating to a certain temperature below the
temperature at which a substantial decrease in permeability to
water takes place. In this way, less imagewise supplied
heat-generating electromagnetic radiation is required to produce
the desired reduction in water-permeability.
The technique of the integral removal by bleaching or leaching out
of colored heat-generating substances from the heat-exposed
recording layer opens up the possibility to produce colored or
black prints without having to selectively remove the nonheated
portions of the recording layer.
According to a particular embodiment the light absorbing heat
generating substances are integrally removed after the imagewise
light exposure and relying on the difference in water-permeability
between the exposed and nonexposed portions of the recording layer
a positive color print i obtained by differential penetration of a
dye solution. The density of the color print is directly
proportional to the degree of water-permeability of the nonheated
portions of the recording layer. The disturbing effect of a dark
image background which would have been present if the
heat-generating substances had not been removed is completely
excluded here.
In this connection reference is made to the published Dutch Pat.
application No. 6,806,658, wherein the production of positive
images by imagewise water-permeability differentiation is
described. According to an embodiment of the invention described
therein the heat-sensitive layer containing light absorbing
pigments has to be removed integrally from an image containing
layer. The present method is especially interesting in such a case
wherein it is interesting to maintain the heat-sensitive layer on
top of the image containing layer avoiding damaging of the
underlying layer.
According to an important embodiment pigments that are fast to
light, e.g., yellow, cyan or magenta diffusion-resistant pigment
dyes, are incorporated into the heat-sensitive layer together with
the light-absorbing and heat-generating substances which can be
washed away. After imagewise exposure the heat-generating
substances are integrally leached out, e.g., by means of tap water,
and the heat-sensitive layer is washed away in accordance with the
nonexposed areas, so that a spectrally pure pigment dye image of
high fastness to light is left. By applying the latter embodiment
of the present invention it is possible to obtain yellow dye images
by heat-generating exposure e.g., infrared exposure and subsequent
selective removal of the recording layer by washing away. In order
to understand the advantage associated with said technique, it has
to be noted that by means of yellow dyes as the sole
light-absorbing colored component in the heat-sensitive layer this
was practically impossible so far, as yellow dyes absorb only a
minor part of the visible light and none of infrared light so that
by exposure little or no heat is generated in said dyes.
The use of removable heat-generating substances thus makes it
possible according to the present invention to record an image of
any color in a photothermographic way of combining said removable
heat-generating dyes with one or more colored substances which are
fast to diffusion, e.g., pigments conferring the desired color to
the image.
By means of this technique it is possible to produce color images
for color proofing. Color-proofing materials serve to form a proof
for submission to the printer to give an idea of a multicolor
reproduction as will be produced by imagewise overprinting with
four inks (yellow, magenta, cyan and black) printed at the strength
normally used in practice. The proof obtained wit a color proofing
material enables to determine the necessary corrections of the
intermediate negatives used in preparing the etching resists and to
adapt the exposure conditions. In an already existing method for
preparing such a colorproof use is made of a multicolor silver
halide photographic material which is exposed through the screened
black-and-white selection negatives corresponding respectively with
the yellow, magenta, cyan and black separation images of a
multicolor original. The difficulty associated with said method
resides in finding the right color couplers for forming dyes having
an absorption spectrum practically identical t that of the printing
dyes or pigments used. The method of the present invention provides
a solution of that problem in that previously prepared dyestuffs or
pigments with the right absorption spectrum can be applied in
nonmigratory state.
According to one technique a multicolor proof is obtained by
successively coating, exposing and developing four heat-sensitive
hydrophilic water-permeability differentiable layers which contain
a black, a cyan, a magenta and a yellow pigment dye respectively
through the corresponding black-and-white selection negatives of
the multicolor original to be reproduced by printing. The said
heat-sensitive layers are separately coated on one and the same
support. Following its coating, each of the four heat-sensitive
layers is exposed to light through the proper black-and-white
selection negative, and the development carried out by washing away
the nonexposed portions of the exposed recording layer removing at
the same time the nondiffusion resistant light-absorbing
heat-generating dyes in the exposed portions.
According to another technique the pigment coatings are applied to
four separate transparent supports. After exposure and processing
the images were brought in register and examined by means of
transmitted light, e.g., in a diascope, or overhead projector.
According to said techniques the colored heat-sensitive layers
contain in addition to dark heat-generating bleachable or removable
substances, a dye, a pigment or a mixture of both, which resists
diffusion and which dye or pigment has an absorption spectrum as
conform as possible to that of the color of the printing dye for
each printing step (cyan, magenta, yellow).
As is known the magenta ink pigments have unwanted absorptions in
the blue region of the spectrum, and to a much less extent in the
red one, the magenta ink prints as if it were a true magenta ink
containing some yellow and a little cyan. Normally sufficient
correction is obtained by reducing the amount of yellow in
proportion t the amount of magenta printed.
The cyan ink pigments have unwanted absorptions in the blue and
green regions of the spectrum; the cyan ink prints as if it were a
true cyan ink containing magenta and yellow.
The yellow ink pigments normally approaches the ideal way of
absorbing blue light and no correction is necessary unless it is a
special "warm-ink" (orange-yellow) in which case it may be
desirable to reduce the strength of the magenta printed in the
yellow areas.
The black toner being preferably present in the first exposed layer
can be a black or grey pigment, e.g., carbon black or dark metal
particles, their sulphides and oxides, e.g., nickel, lead, silver,
bismuth, lead(IV) oxide, copper(II) oxide and copper(II) sulphide.
The black-toned material preferably contains carbon black in the
heat-sensitive layer, which preferably is applied to a subbing or
interlayer of the type described in the Belgian Pat. specification
No. 692,422.
Nonmigratory pigments suitable for use in the "color proofing"
system of the invention are known under the trade name "Pigmosol"
dyes. "Pigmosol" is a registered trademark of Badische Anilin-
& Soda-Fabrik A.G., Ludwigshafen/Rh., W.-Germany, for organic
pigment dyes which are mixed with a dispersing agent for aqueous
medium. These pigment dyes are very resistant to light, heat, acids
and bases. They are insoluble in hydrophilic colloids, e.g.,
gelatin and poly-N-vinylpyrrolidone which colloids are preferably
used in heat-sensitive layers intended for use in the washing away
technique.
The following examples illustrate the present invention.
EXAMPLE 1
A polyethylene terephthalate support of 0.1 mm. thickness was
coated with the following composition pro rata of 17 g. per
sq.m.:
20% aqueous dispersion of copoly
(vinylidene-chloride/N-butylmaleimide/ itaconic acid) (88/10/2)
with an average particle size of 0.1.mu. 40 g.
40% aqueous dispersion of polyethylene having a particle size of
less than 0.1.mu. and an average molecular weight comprises between
15,000 and 30,000 40 g.
30% aqueous dispersion of silica with an average particle size of
0.025.mu. 40 ml. water 780 ml.
ethanol 100 ml.
The subbing layer thus obtained was dried at 30.degree. C. A
heat-sensitive layer, for use in a washing-away-development by
rubbing with a cotton pad soaked with water at 20.degree. C., was
coated on this subbing layer pro rata of 15 g. per sq.m. from the
following composition:
10% aqueous solution of poly-N- vinyl pyrrolidone 170 ml. 40%
aqueous dispersion of polyethylene as described above 195 g.
water 120 ml. aqueous carbon dispersion containing per 100 g. 16 g.
of carbon (average particle size 0.1.mu. ) and 2 g. of poly-N-vinyl
pyrro- lidone 450 ml.
3% aqueous dispersion of the sodium salt of tetradecyl sulphate 65
ml.
The heat-sensitive layer was dried at 30.degree. C. While in
contact with a black-and-white selection negative corresponding
with those parts of an original that had to be printed in black,
the heat-sensitive material was exposed for 1/2000 sec. through
said selection negative by means of a xenon gas discharge lamp of
1,000 watt.sec. Subsequently, the unexposed portions of the
recording layer were washed away with water so that a positive
image was obtained in accordance with those parts of the original
that have to be printed in black.
The layer comprising the black image was then coated with a second
thermosensitive layer comprising a cyan pigment for the formation
of the cyan image areas. The black image layer was therefor mounted
horizontally in a centrifuge rotating at 100 revolutions per min.
at a temperature of 43.degree. C. The following composition was
poured onto the black image layer to form a coating which, on
drying comprises 30 g. per sq.m.
40% aqueous dispersion of polyethylene as described above 100 g.
20% aqueous dispersion of poly-N-vinyl pyrrolidone 20 ml.
Heliogen blau B Colanyl Teig (a cyan pigment insoluble in water,
sold by Badische Anilin- & Soda-Fabrik A.G., Ludwigshafen/Rh.,
W-Germany) 22 g.
10% aqueous solution of a compound corresponding to the following
struc- tural formula: ##SPC1## 7% aqueous solution of a compound
corresponding to the following structural formula: ##SPC2## 3%
aqueous solution of sodium tetradecylsulphate 20 ml.
After having been dried the material obtained was exposed, while in
register contact with a black-and-white selection negative
corresponding with those parts of the original that had to be
printed in cyan, the exposure being effected through the said
selection negative by means of a xenon gas discharge lamp of 1,000
watt.sec. for 1/2000 sec.
Subsequently the unexposed portions of the recording layer were
washed away with water, the water-soluble dyes in the exposed areas
being rinsed away immediately. The black image already present
remained intact. The image obtained consisted of black and cyan
parts. The material was then coated again with a thermosensitive
layer comprising a yellow pigment for the formation of a yellow
image. The composition was analogous to that of the preceding
thermosensitive layer, but instead of 22 g. of Heliogen Blau B
Colanyl Teig use was made of 15 g. of Permanent Gelb HR Colanyl
Teig (a yellow pigment insoluble in water, sold by Farbwerke Hochst
A.G. Frankfurt(M) - Hochst, W.-Germany).
The resulting material was then exposed through a black-and-white
negative corresponding with those parts of the original that had to
be printed in yellow.
After having been washed the material was coated again with a
composition analogous to that of the preceding layer, with the
exception, however, that 20 g. of Permanentcarmin FBB Colanyl Teig
(a magenta pigment insoluble in water, sold by Farbwerke Hochst
A.G. Frankfurt(M) - Hochst, W-Germany) was used therein instead of
the 22 g. of Heliogen Blau B Colanyl Teig.
After having been dried the resulting material was exposed now
through a black-and-white selection negative corresponding with
those parts of the original that had to be printed in magenta.
Thus, a four-color image suitable for color proofing was obtained.
By means of this four-color image the quality of the selection
negatives and the future print was judged of easily.
EXAMPLE 2
A polyethylene terephthalate support having a thickness of 0.075
mm. was coated with a subbing layer as described in Example 1. The
subbing layer itself was coated pro rata of 18 g./sq.m. with a
black heat-sensitive layer comprising:
an aqueous dispersion of polyethylene comprising per 100 g. 18 g.
of poly- ethylene (the polyethylene dispersion was prepared by
dispersing polyethylene in water at 160.degree. C.) with 2.5 g. of
nonyl- phenyl poly(ethyleneoxyde)n (the average value of n= 9-10),
2.5 g. of nonylphenyl- poly(ethyleneoxyde).sub.m ethanol (the
average value of m= 7) and 0.4 g. of potassium hydroxide 175
ml.
water 465 ml. an aqueous carbon dispersion comprising per 100 g. 16
g. of carbon particles having a size of 0.1.mu. and 2 g. of poly-
N-vinyl pyrrolidone 400 ml.
3% aqueous solution of sodium tetra- decyl sulphate 50 ml. 10%
aqueous solution of animal glue 120 ml.
After having been dried the resulting material was exposed as
described in Example 1, while in contact with a black-and-white
selection negative corresponding with those parts of the original
that had to be printed in black. The further treatments were
analogous to those described in Example 1, with the proviso,
however, that the following three differently colored
heat-sensitive layers were coated successively pro rata of 40
g./sq.m.:
1. A thermosensitive layer comprising a cyan pigment:
aqueous dispersion of polyethylene comprising 18% of polyethylene
prepared as described above 200 ml.
water 300 ml. 20% aqueous dispersion of poly-N-vinyl pyrrolidone 20
ml. Heliogen blau B Colanyl Teig (see Example 1) 50 g.
5% aqueous solution of a diffusible dye corresponding to the
structural formula: ##SPC3## 7% aqueous solution of a diffusible
dye corresponding to the structural formula: ##SPC4## ethanol 75
ml.
2. A thermosensitive layer comprising a yellow pigment, the
composition of the layer being analogous to that of the preceding
one, wit the proviso, however, that the 50 g. of Heliogen blau B
Colanyl Teig were replaced by 100 g. of Paliogengelb RT Colanyl
Teig (a pigment paste) sold by Badische Anilin- & Soda-Fabrik
A.G. Ludwigshafen/Rh., W-Germany).
3. A thermosensitive layer comprising a magenta pigment, said layer
having a composition analogous to that of the preceding one, but
wherein the 50 g. of Heliogen Blau B Colanyl Teig were replaced by
100 g. of Helioechtrot ITR Feinteig (a pigment dispersion sold by
Farbenfabriken Bayer A.G., Leverkusen, W.-Germany).
EXAMPLE 3
A heat-sensitive material consisting of a polyethylene
terephthalate support, a subbing layer, and a black heat-sensitive
layer as described in Example 1, was exposed through a selection
negative while in contact therewith, said selection negative
corresponding with those parts of the original that had to be
printed in black, and the exposure being effected with the aid of a
xenon gas discharge lamp of 1,000 watt.sec. in 2/1000 sec. After
washing away of the unexposed areas with water, the material
mounted horizontally in a centrifuge rotating at 100 revolutions
per min. was coated therein at a temperature of 45.degree. C. pro
rata of 40 g./sq.m. with a composition comprising the following
ingredients:
40% aqueous dispersion of polyethylene (see Example 1) 100 ml.
water 200 ml.
Heliogen blau B Colanyl Teig (see Example 1) 25 g. 20% aqueous
dispersion of poly-N- vinyl pyrrolidone 20 ml.
10% aqueous dispersion of black silver particles 400 ml. 3% aqueous
solution of sodium tetradecyl sulphate 20 ml.
After having been dried the material was exposed through a
black-and-white selection negative corresponding with those parts
of an original that had to be printed in cyan, the selection
negative being brought in register contact with said material.
After washing away of the unexposed portions of the recording
layer, the material was coated again with a composition analogous
to that of the preceding layer, with the proviso, however, that the
25 g. of Heliogen Blau B Colanyl Teig were replaced by 15 g. of
Permanent Gelb HR Colanyl Teig sold by Hochst.
The resulting material was exposed through a black-and-white
selection negative corresponding with those parts of the original
that had to be printed in yellow. After washing away of the
unexposed areas, the material was again coated with a solution
analogous to the first described, with the exception, however, that
the 25 g. of Heliogen Blau B Colanyl Teig were replaced by 20 g. of
Permanentcarmin FBB Colanyl Teig (see Example 1).
After exposure through a black-and-white selection negative
corresponding with those parts of the original that had to be
printed in magenta and after washing away the nonexposed portions
the material was immersed for 60 sec. in a common bleaching bath
(Farmer's reducer), whereby the black residual silver in the
three-color layer material was bleached away. The material was then
rinsed and dried. A three-color transparency was obtained finally.
The said transparency was used in a projection technique known as
"overhead projection."
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