U.S. patent number 3,642,480 [Application Number 04/819,086] was granted by the patent office on 1972-02-15 for photographic process and materials used therein.
This patent grant is currently assigned to Gevaert-Agfa N.V.. Invention is credited to Marcel Nicolas Vrancken.
United States Patent |
3,642,480 |
Vrancken |
February 15, 1972 |
PHOTOGRAPHIC PROCESS AND MATERIALS USED THEREIN
Abstract
A method of and material for recording information using a
recording material having a water-permeable recording layer
consisting essentially in one embodiment of a continuous phase of
film-forming hydrophilic colloid binder having uniformly
distributed therethrough finely divided particles of a hydrophobic
oil, wax, or thermoplastic polymer, together with finely divided
particles of an inorganic photoconductive compound, and in another
embodiment of a continuous phase of a film-forming hydrophilic
colloid binder having uniformly distributed therethrough finely
divided particles of a hydrophobic oil, wax, or thermoplastic
polymer, together with a water-soluble organic photoconductive dye,
wherein such recording layer is imagewise exposed to active
electromagnetic radiation to render the exposed areas substantially
impermeable to water, while the unexposed areas remain permeable
but without significantly increasing the temperature of such layer
and is thereafter developed by contacting the same with an aqueous
liquid to produce a visible change by penetration or removal of the
unexposed regions of the layer by such liquid. The binder should be
present in a ratio of about 1:1 to 1:10 relative to the hydrophobic
particles, while the photoconductor is present in a ratio of 1:3 to
5:3 in the case of an inorganic photoconductor and at least about
0.05 percent by weight in the case of the organic photoconductive
dye, both relative to the hydrophobic particles.
Inventors: |
Vrancken; Marcel Nicolas (Hove,
BE) |
Assignee: |
Gevaert-Agfa N.V. (Mortsel,
BE)
|
Family
ID: |
27448454 |
Appl.
No.: |
04/819,086 |
Filed: |
April 24, 1969 |
Foreign Application Priority Data
|
|
|
|
|
Apr 24, 1968 [GB] |
|
|
19,457/68 |
|
Current U.S.
Class: |
430/294;
250/475.2 |
Current CPC
Class: |
G03F
7/038 (20130101); B41M 5/366 (20130101); G03C
1/705 (20130101); B41C 2210/24 (20130101); B41C
2210/20 (20130101); B41C 2210/22 (20130101); B41C
2201/14 (20130101); B41C 2210/04 (20130101); B41C
1/1025 (20130101); B41C 2201/04 (20130101) |
Current International
Class: |
B41M
5/36 (20060101); G03C 1/705 (20060101); G03F
7/038 (20060101); B41C 1/10 (20060101); G03c
005/24 () |
Field of
Search: |
;96/1,1.5,1.8,33,27,35,48PD ;250/65 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lesmes; George F.
Assistant Examiner: Brammer; J. P.
Claims
We claim:
1. A method of recording information comprising
1. Imagewise exposing to active electromagnetic radiation a
recording material including a water-permeable recording layer
consisting essentially of a continuous phase of a film-forming
hydrophilic colloid binder having uniformly distributed
therethrough finely divided particles of a hydrophobic oil, wax, or
thermoplastic polymer together with finely divided particles of an
inorganic photoconductive compound, said binder being present in a
ratio by weight of about 1:1 to 1:10 and said inorganic
photoconductive compound being present in a ratio by weight of
about 1:3 to 5:3 both relative to the hydrophobic particles, said
exposure being for an intensity and duration sufficient to render
said layer substantially impermeable to water in the exposed
regions thereof while said unexposed regions remain permeable but
insufficient to produce a substantial increase in the temperature
of said recording layer, and
2. Developing the exposed recording layer by contacting the layer
with an aqueous liquid to produce a visible change by penetration
of or removal by such liquid of the unexposed regions of said
layer, said inorganic photoconductive compound being
photoconductive zinc oxide, titanium(IV) oxide, lead(II) oxide, red
lead oxide (Pb.sub.3 O.sub.4), chromium(III) oxide, cadmium sulfide
or cadmium sulfide selenide, or cadmium selenide.
2. A method according to claim 1, wherein said hydrophobic
particles substantially consist of a hydrophobic thermoplastic
polymer solid at room temperature.
3. The method of claim 2 wherein said thermoplastic polymer has a
molecular weight of about 5,000-1,000,000.
4. The method of claim 1 wherein the particles of said inorganic
photoconductive compound having a grain size not greater than about
10 .mu..
5. The method of claim 1 wherein said recording layer contains a
water-attracting polyol or hygroscopic ionic compound.
6. A method according to claim 1, wherein said hydrophobic
particles are substantially composed of at least one hydrophobic
thermoplastic compound solid at room temperature.
7. A method according to claim 1, wherein said hydrophobic
particles are dispersed in said continuous phase by a dispersing
agent for aqueous media.
8. A method according to claim 2, wherein the polymer particles are
latex particles.
9. A method according to claim 1, wherein the hydrophilic binder
consists of at least one proteinaceous binding agent.
10. A method of recording information comprising
1. Imagewise exposing to active electromagnetic radiation a
recording material including a water-permeable recording layer
consisting essentially of a continuous phase of a film-forming
hydrophilic colloid binder having uniformly distributed
therethrough finely divided particles of a hydrophobic oil, wax, or
thermoplastic polymer together with a water-soluble organic
photoconductive xanthene, thiazine, acridine or porphyrin dye
dissolved in said continuous phase, said binder being present in a
ratio by weight of about 1:1 to 1:10 and said photoconductive dye
being present in an amount by weight of at least about 0.05 percent
both relative to the hydrophobic particles, said exposure being for
a time and to radiation of a type and intensity sufficient to
render said layer substantially impermeable to water in the exposed
regions thereof while said unexposed regions remain permeable but
insufficient to produce a substantial increase in the temperature
of said recording layer, and
2. Developing the exposed recording layer by contacting the layer
with an aqueous liquid to produce a visible change by penetration
of or removal by such liquid of the unexposed regions of said
layer.
11. A method according to claim 10, wherein the said organic
photoconductive dye has spectral sensitizing properties with
respect to photoconductive zinc oxide.
12. A method according to claim 10, wherein the organic
photoconductive dye is a photoreducible dye.
13. A method according to claim 12, wherein as photoreducible dye a
fluorescein dye is used.
14. A method according to claim 10, wherein the recording layer
and/or an adjacent water-permeable layer contains a substance
selected from the group consisting of pigments, metal particles,
dyes, and dye-forming compounds.
15. A method according to claim 10, wherein the recording layer
contains a water-attracting polyol or hygroscopic ionic
compound.
16. A method according to claim 10, wherein the exposed recording
layer is treated with an aqueous solution of a dyestuff or, a
dye-forming component.
17. A method according to claim 10, wherein the recording layer
contains particles of a metal and after exposure is treated with a
solution of an etching agent for said metal.
Description
The present invention relates to photographic recording and
reproduction of information and to recording and reproduction
materials suited therefor.
More particularly this invention relates to a process for producing
an irreversible change in physical behavior in the areas where a
photosensitive material is subjected to a sufficient degree of
electromagnetic radiation. The photosensitive element, which will
be described more in detail hereinafter, by the action of active
electromagnetic radiation undergoes a decrease of permeability and
removability by water. This means that in said element an image or
signal in the form of electromagnetic radiation is recorded as a
pattern of differences in permeability for and removability by
water.
It is one of the objects of the present invention to produce
photographic copies of line work, halftone and continuous tone
originals by means of a simple aqueous processing.
It is another object of the present invention to produce polymer
patterns which make part of a printing master, e.g., a planographic
printing master, and a screen printing master such as a
stencil.
Other objects will become apparent of the description and examples
which are not limiting the invention to the embodiments covered
thereby.
The present invention resides in a method for recording
respectively reproducing information, which method comprises (1)
informationwise exposing to active electromagnetic radiation a
recording material comprising at least one water-permeable
recording layer essentially consisting of one or more
photoconductive compounds and dispersed finely divided material
comprising hydrophobic particles consisting of or comprising a
hydrophobic substance, said photoconductive compounds and dispersed
hydrophobic particles being present in the recording layer in such
an amount that without a substantial informationwise increase of
the temperature of the recording layer, the latter undergoes a
reduction in water-permeability in the sufficiently irradiated
portions, and (2) developing the so formed latent image by
penetration of a liquid into the nonirradiated or insufficiently
irradiated portions of the recording layer bringing about a visible
change in correspondence in these portions, or by removal of the
nonirradiated or insufficiently irradiated portions of the
recording layer.
The dispersed hydrophobic particles should be for the most part in
very near relationship (only separate from each other over a very
small distance) in order that neighboring particles in any given
area of the recording layer can coagulate when the layer in that
area, which is sensitive to electromagnetic radiation, is
sufficiently irradiated.
A preferred recording material for use according to the present
invention consists of or incorporates a water-permeable recording
layer or sheet containing finely divided hydrophobic substance
dispersed in a hydrophobic binder, preferably in a ratio by weight
of at least 1:1, said recording material further containing in
working relationship to said dispersed hydrophobic substance a
substance the electrical resistivity of which decreases on exposure
to electromagnetic radiation.
With a proper amount of hydrophilic binder it is even possible to
use liquid and semisolid hydrophobic dispersed material, e.g.,
nonpolar organic liquids or soft substances such as paraffinic oil,
soft hydrophobic compounds of aromatic nature, e.g., pyrene and
hydrophobic waxes.
The finely divided hydrophobic substance is preferably composed
wholly or mainly of hydrophobic thermoplastic substance, and this
substance is preferably solid at room temperature (softens
preferably between 30.degree. and 200.degree. C.). The recording
layer preferably contains solid hydrophobic particles dispersed in
a hydrophilic binder in a ratio by weight of at least 1:1, and such
particles preferably consist wholly or mainly of hydrophobic
thermoplastic material, e.g., hydrophobic thermoplastic polymeric
material.
The hydrophobic substance is preferably applied from an aqueous
dispersion wherein a dispersing agent is used for dispersing the
finely divided hydrophobic material and for keeping it in dispersed
state. The hydrophobic material may be chemically treated to make
it more easily dispersible in an aqueous medium. Such is e.g., the
case by partial oxidation of polyethylene.
Substances the electrical resistivity of which one exposure to
electromagnetic radiation decreases are, e.g., inorganic and
organic photoconductive semiconductive compounds. The
photoconductive substances which can be applied in the present
invention may be N-type as well as P-type semiconductors or
combinations of both types.
A change of the conductivity possibly also charging capacity,
electron-accepting or electron-emission power, in other words a
change of the potential level of the photoconductive particles in
respect of the dispersed material in the surrounding medium is
assumed as being the cause that a coagulation of the said dispersed
hydrophobic particles takes place. This assumption is based on the
knowledge that theoretically flocculation and coagulation are the
same phenomena. Indeed, in a suspended solid system both phenomena
are characterized by interparticular surface reactions annihilating
or decreasing the repelling forces between separate dispersed
particles (ref. Ind.Eng.Chem., C. P. Priesing -- Vol. 54, No. 8,
1962, p. 38-45, "A theory of Coagulation useful for Design").
Stability of colloidal particles in aqueous dispersions is
attributed to hydration and electrostatic charge. The dispersed
particles present to the dispersing medium an electronic or
electrostatic capacity, which means that they can lose, gain or
share electrons by forming bonds such as ionic, covalent, hydrogen,
dipolar, or induced dipolar bonds. These bonds can be classified in
terms of bond energies (given as kilocalories per mole). Ionic
crystal bonds are the strongest- viz, more than 150 to 200,
covalent bonds about 50 to 100, hydrogen bonds 1 to 10, and dipolar
bonds less than 5. Similar to dipolar bonds are bonds being the
result of induced polarization (London-van der Waals forces) in
molecules and atoms, which normally are electrically neutral. Such
bonds are also of low energy. In most coagulation processes,
covalent bonds or ordered ionic crystal lattices are neither made
nor broken, although the system is subject to ionic equilibrium in
solution.
The electrical capacity formed around a hydrophobic or lyophobic
dispersed particle is built up by the electrical double layer
surrounding the particle. A fixed layer of electrostatic charges,
e.g., of ions surrounds the dispersed particle, which may originate
from within the colloidal mass itself, or may be formed thereon by
a preferential adsorption thereto of a dispersing agent.
In flocculation four forces act on both the dispersed phase and the
coagulant, viz, Brownian motion, gravity coulombic charge and
agitation.
Colloidal stability depends on several parameters, the most
important being the water-adsorbing character of substances,
valence and concentration of ions surrounding the dispersed
particle having an electrical double layer. It is assumed that at
least one of said parameters is changed by the exposure of the
photoconductive compounds present in working relationship with the
dispersed material, and that a discharge or reduction of charge
present in the double layer, and consequently coagulation resulting
in the direct contacting of the hydrophobic surfaces of the
dispersed hydrophobic particles takes place. Note that the
dispersed hydrophobic particles itself may be photoconductive or
contain a photoconductor e.g., a ionoid photoconductor.
The direct contact of the hydrophobic polymer particles with each
other decreases the permeability for water of the recording layer,
since hydrophobic surfaces stand then in direct contact with each
other without a separating hydrophilic hydration layer.
The binding forces between the directly contacting hydrophobic
particles are adhesion forces. The adhesion of the coagulated
hydrophobic particles may be compared with the attractive forces
that exist between polymer molecule chains. It is possible to
control said adhesion by choosing as hydrophobic dispersed
particles hydrophobic polymer particles of same or different
chemical structure, whereby the possibility is left to create
physical and chemical bonds of more or less firmity between the
coagulated particles.
So, a mixture of polymer particles can be used wherein at least a
part of the polymer particles contains polymer chains having groups
differing in polarity and/or polarizability whereby intermolecular
forces of quantum mechanic structure- e.g., charge transfer
complexes, can be formed. Polymers having groups with different
electron-donating or electron-attracting power are, e.g.,
polyacrylonitrile, polyvinyl chloride, polyethylene polymethyl
methacrylate, and vinyl polymers having a nucleus with aromatic
character, e.g., polystyrene, polyvinyl-naphthalene,
polyvinyl-anthracene, or poly-N-vinyl-carbazole, and nitro-, cyano-
and halogen derivatives of the vinyl polymers having a nucleus with
aromatic character.
Having stated in general the concepts of this invention and having
given a probable explanation of the working mechanism laying on the
basis of the water-permeability-impermeability differentiation in
the recording element by active imagewise or recordwise
electromagnetic radiation, we will give now a more detailed
description of the composition and structure of various
photosensitive elements, which form or make part of recording and
reproduction materials suited for being used according to the
present invention.
According to a preferred embodiment the photosensitive element
contains hydrophobic thermoplastic polymer particles having a
softening point high enough to not coalesce on being coated at
30.degree. C. Said hydrophobic thermoplastic polymer particles are
dispersed in a hydrophilic binding agent (in an amount not
preventing a substantial reduction in water permeability of the
coating on exposure). Said hydrophobic thermoplastic polymer
particles stand in working relationship i.e., in effective contact
with (a) photosensitive substance(s) that on exposure with active
electromagnetic radiation cause(s) coagulation of the dispersed
polymer particles.
Whether a photosensitive substance is suited for that purpose or
not can be readily determined by a routine experimentation with a
mixture of thermoplastic hydrophobic resin particles dispersed
together with the photosensitive substance in a hydrophilic binder,
the volume of binder being preferably not higher than that of the
resin particles.
By the term "active electromagnetic radiation" is understood that
type and degree of radiation effecting the desired reduction of
permeability for water of the recording layer without a substantial
rise in temperature. In case dispersed thermoplastic hydrophobic
substances being solid at room temperature (20.degree. C.) are
used, the temperature should not rise above the softening point of
the hydrophobic thermoplastic particles.
By the term "effective contact" is understood that the
photoconductive substance(s) is (are) so intimately associated
(mixed) with the dispersed hydrophobic material (which itself may
be photoconductive) that a reduction in water permeability of the
recording layer can take place under the described exposure
conditions in the sensitivity range of the applied nonspectrally or
spectrally sensitized photoconductive substance.
An information-recording process, wherein a water-permeable
recording layer is used, at least the greater part by weight of
which is formed by a dispersion of particles composed wholly or
mainly of hydrophobic thermoplastic polymeric material, solid at
room temperature, in a hydrophilic binder, the weight ratio of said
polymer particles to said binder being in excess of 1:1, and said
layer having been formed by forming and drying a layer comprising
said particles in an aqueous medium containing the binding agent,
and being capable of being rendered water-impermeable or less
water-permeable in any given area of the layer by the action of
heat and/or pressure at that area, and wherein such layer is
information-wise heated and/or subjected to pressure to such an
extent that the information is recorded in terms of a difference in
the water permeabilities of different areas of said recording
layer, and parts of said recording layer which remain
water-permeable are removed, is described in the Canadian Pat. No.
787,843 of Gevaert Photo-Producten N.V., issued June 18, 1968.
Preferred hydrophobic thermoplastic polymers which are solid at
room temperature and are applied in latex form are polyethylene and
polyvinylidene chloride having a melting point of 110.degree. and
190.degree. C. respectively, and the following polymers with their
respective glass transition temperatures: polystyrene (100.degree.
C.), polymethyl methacrylate (comprised between 70.degree. and
105.degree. C.), polyethyl methacrylate (50.degree. C.), polyvinyl
chloride (near 70.degree. C.), polyacrylonitrile (near 100.degree.
C.), and poly-N-vinylcarbazole (200.degree. C.).
As is known, the glass transition temperature can be lowered by the
addition of some substances called plasticizers, and by
copolymerization.
The molecular weight of the polymers usable in the process of the
present invention may vary within wide limits. Polymers possessing
a molecular weight between 5,000 and 1 million are preferred. With
polyethylene having a molecular weight of between 15,000 and 50,000
especially good results were obtained. Of course, mixed dispersion
of polymer particles are considered too and the different polymer
particles may contain ingredients, e.g., those which impart to the
polymer particles a color or opacity.
The aqueous dispersion of the polymers (homopolymers or copolymers)
is preferably prepared by polymerization in emulsion of one of more
polymerizable monomers according to known techniques, e.g., those
described by W. Sorenson and T. W. Campbell, Preparative Methods of
Polymer Chemistry, Interscience Publishers, New York (1961). In the
emulsion polymerization use is made of dispersing agents such as
those described by K. Laux, "Die Grenzflachenaktiven Stoffe" in
Winnacker-Kuchler's "Chemische Technologie" Carl Hanser-Verlag
Munich (1960) p. 155-242.
Further polymer dispersions which are appropriate for being applied
in the present invention can be obtained by dispersing in water
mechanically finely divided polymer particles preparably with the
help of surfactants and/or optionally with hydrophilic protective
colloids such as polyvinyl alcohol and gelatin. A preferred latex
of that type contains polyethylene particles. Excellent results are
obtained with latexes prepared by emulsion polymerization. In this
polymerization technique the monomer is dispersed by stirring in
very fine droplets in the presence of water, emulsifyers (soaps,
ammonium oleate, sulfonated fatty alcohols and the like),
protective colloids (carboxymethyl cellulose, polyvinyl alcohol and
the like), e.g., a buffering system, a surfactant and a
water-soluble catalyst, e.g., hydrogen peroxide or a persulphate.
The polymer is obtained as a stable dispersion of polymer particles
in water. In that case the electrical double layer is built up by
the dispersing agent.
The dispersed polymer particles may size from 0.01 .mu. to 50 .mu..
However, the larger the particles, the less the resolving power on
recording. Very good results are obtained with dispersions the
polymer particles of which size from 0.05 to 2 .mu.. Dispersions
wherein the dispersed particles size from 1 .mu. to 1 m.mu. are
considered as colloidal systems. A colloidal system the continuous
phase of which is formed by water (dispersing medium) and the
dispersed phase is formed by particles sizing from 1 .mu. to
0.001.mu. is called a hydrosol. Good results are obtained when
using such hydrosols the polymer particles of which are not greater
than 0.1 .mu.. Good results are further obtained when in the
recording layer an amount of polymer is used comprised between 0.5
g. and 10 g./sq.m. The thickness of recording layers according to
the present invention preferably varies between 0.5 .mu. and 10
.mu..
The support and/or the drying technique of the layer may be chosen
in such a way that a natural adhesion occurs between the layer and
the support, which optionally has been coated with a proper subbing
layer(s).
When a hydrophilic continuous phase is present -- and this is
preferred -- in the photosensitive recording layers applied in the
present invention (a) hydrophilic polymer(s) acting as binding
agen(s) are used, e.g., hydrophilic natural colloids, modified
hydrophilic natural colloids, or synthetic hydrophilic polymers.
MOre particularly they may be selected from such film-forming
water-soluble natural or modified natural hydrophilic colloids as,
e.g., gelatin, glue, casein, zein, hydroxyethyl-cellulose,
carboxymethyl-cellulose, ethyl-cellulose,
carboxymethyl-hydroxyethyl-cellulose, gum arabic, sodium alginate
and hydrophilic derivatives of such colloids. They may also be
selected from such synthetic hydrophilic polymers as, e.g.,
polyvinyl alcohol, polyvinyl-N-pyrrolidone, polyvinyl amine,
polyethylene oxide, polystyrene sulphonic acid, polyacrylic acid
and hydrophilic copolymers and derivatives of such polymers. The
hydrophilic polymers are preferably of such a high molecular weight
that they are film-forming and may be hardened to a certain extent
for obtaining a higher mechanical strength. E.g., a film-forming
hydrophilic binding agent such as gelatin may be hardened with
formaldehyde.
Preferred hydrophilic binding agents are of proteinaceous nature
and in that respect casein and gelatin are most preferred.
The ratio by weight of dispersed hydrophobic material to
hydrophilic binder is one of the features that determines the
photosensitivity of the recording element. The photosensitivity of
the recording layer is measured in terms of a reduction of water
permeability or increase in resistance to removal of the recording
layer from its support by an aqueous treatment (washoff
development) of any photographically exposed area of the recording
layer. It has to be noticed that in the determination of the
photosensitivity the temperature of the irradiated portions of the
recording layer is not raised or not substantially raised in
respect of the nonirradiated portions.
It has been experimentally found that a practical useful
sensitivity for reproduction of informationwise modulated
electromagnetic radiation by a washoff development can be obtained
with a ratio by weight of dispersed hydrophobic substance,
preferably hydrophobic thermoplastic polymer particles solid at
room temperature, to hydrophilic binder from at least 1:1 on.
Preferably the recording layer contains from 35 to 10 percent by
weight of hydrophilic binder in respect to the finely divided
hydrophobic material. Optimal results were obtained with a ratio by
weight of hydrophobic dispersed particles to hydrophilic binder of
4:1.
According to a preferred embodiment of the present invention the
photoconductive substances surround the dispersed hydrophobic
particles in the recording layer.
According to a particular embodiment the aid hydrophobic particles
consist of a hydrophobic photoconductive substance, e.g.,
poly-N-vinylcarbazole or are hydrophobic particles containing
photoconductive substances, e.g., dissolved in a hydrophobic wax or
polymer, or such substances in particulate form surrounded by
hydrophobic material or a capsule shell.
According to a preferred embodiment a photoconductive substance,
which without being heated in electromagnetically irradiated state
causes the coagulation of hydrophobic dispersed material, is
applied in dissolved state and in molecularly divided form
surrounds the hydrophobic particles. Preferably used
photoconductive substances are hydrophilic enough for being
compatible (for forming a solid state solution) with a hydrophilic
polymer. Thus, for example, when the hydrophilic polymer has the
capability of gel-sol transformation, the photoconductive substance
is dissolved in the solution from which the gel is formed and forms
a solid state solution with the continuous hydrophilic binder.
The photoconductive substances may be sensitive to any type of
electromagnetic radiation e.g., X-rays, ultraviolet light, visible
light and/or infrared light. If they are not sensitive for visible
light they can be spectrally sensitized for the part of the
spectrum by means of properly selected spectrally sensitizing
agents.
Photoconductive substances that are inherently sensitive to visible
light are found in the group of photoconductive organic dyes and
inorganic colored photoconductive substance, e.g., cadmium
sulphide, cadmium sulphide selenide and lead(II) oxide.
Preferred organic photosensitive semiconductive compounds changing
their electrical behavior on exposure to active electromagnetic
radiation are found in the group of organic photoconductive dyes.
Particularly those are useful that have also spectral sensitizing
properties with respect to photoconductive zinc oxide. Such dyes
are found in the class of: xanthene dyes preferably fluorescein
dyes, thiazine dyes, and acridine dyes preferably water-soluble
acridine dyes. A large number of these dyes are characterized by
their fluorescence and are described e.g., in the U.S. Pat. No.
2,875,047 of Gerard Oster, issued Feb. 24, 1959.
For the photoconductive properties of fluorescein dyes such as
eosine reference is made e.g., to "Semiconductive properties of
organic dyes" by A. T. Vartanyan, Izvest.Akad.Nauk, S.S.S.R.,
Ser.Fiz. 16 (1952), p. 169-185, cf. C.A. 45, 3709 i).
The dyes are preferably applied in dissolved form. Preferably they
are dissolved in water and added in that state to the dispersion of
hydrophobic particles in a hydrophilic binder.
Depending on the type of organic photoconductive substance the
ratio by weight of said substance in respect to the total amount of
hydrophobic particles, preferably thermoplastic polymer particles
and hydrophilic binder, can be as low as 0.05 percent. Very high
sensitivity is obtained with fluoresceine dyes such as eosine and
erythrosine.
According to the present invention organic photoconductive dyes are
preferably used which are photoreducible dyes incapable of being
reduced by a thiol polymer such as gelatin to which sulfhydryl
groups were added (so-called thiolated gelatins) in the absence of
light, but capable of being reduced by the sulfhydryl groups of the
polymer when photoexcited with visible light. For such type of dyes
reference is made to the U.S. Pat. No. 3,145,104 of Robert G.
Carlson, issued Aug. 18, 1964. These photoreducible dyes include
photoconductive members of the fluorescein class, the thiazine
class, the acridine class, and the porphyrin class. Suitable
photoreducible dyes are, e.g., rose bengal phloxin, erythrosin,
eosin, fluorescein, acriflavin, thionin, riboflavin, chlorophylls,
hematoporphyrin, proflavin and methylene blue. The dyes soluble in
an aqueous medium are prefereed, viz fluorescein dyes, thiazine
dyes and water-soluble acridine dyes that are preferably combined
with a proteinaceous colloid forming the hydrophilic continuous
phase of the recording layer.
Preferred inorganic photoconductive substances are the
photoconductive compounds of inorganic type consisting of a
photoconductive metal or of a photoconductive metal compound
containing an element of the Group 6B of the Periodic Table.
Specific inorganic semiconductor materials having photoconductive
properties and that can be used in the materials of the present
invention are Ge; TiO.sub.2 ; ZnO; ZrO 2; GeO.sub.2 ; In.sub.2
O.sub.3 ; SnO.sub.2 ; Bi.sub.2 O.sub.3 ; PbO; BeO; Sb.sub.2 O.sub.5
; SiO.sub.2 ; BaTiO.sub.3 ; Ta.sub.2 O.sub.5 ; TeO.sub.2 ; B.sub.2
O.sub.3 ; ZnS; MnO.sub.2 ; SnS.sub.2 ; CdS, CdSe; CdS-Se; red lead
oxide (Pb.sub.3 O.sub.4), chromium(III)oxide These semiconductor
materials can be sensitized by a number of techniques known in the
art such as doping with foreign ions, dye sensitization, and
heating.
Preferred members of that group are photoconductive zinc oxide,
titanium(IV) oxide, lead(II) oxide (PbO), preferably the yellow
variety (massicot), red lead oxide (Pb.sub.3 O.sub.4),
chromium(III) oxide and cadmium sulphide.
The preferred type of photoconductive zinc oxide is the type used
in electrophotographic recording materials, more preferably white
photoconductive zinc oxide prepared by the oxidation of zinc vapor
(according to the French process).
In the preparation of a recording layer suited for the production
of continuous tone images lead(II) oxide yields excellent results.
There are two types of lead(II) oxide viz the red lead(II) oxide
having a tetragonal crystal structure and the yellow lead(II) oxide
having an orthorhombic crystal structure, which is preferred in the
present invention for X-ray recording.
Further good results are obtained with photoconductive titanium(IV)
oxide especially with that type of titanium (IV) oxide that is
useful for a recording process as described in United Kingdom Pat.
No. 1,043,250 filed Apr. 23, 1963 by Itek Corp. This Patent
Specification relates to a method of producing a visible image in a
copy medium comprising a radiation-sensitive metal-containing
semiconductor compound that becomes conductive on the impingement
of radiation thereon, which method comprises exposing said medium
to an image pattern of activating radiation thereby reversibly
activating said semiconductor compound to render it capable of
causing chemical reaction at portions of said medium corresponding
to said image pattern of radiation, and then developing reversibly
activated portions of said medium by contacting at least said
portions with a liquid redox system reacting on contact at said
reversibly activated portions to form reaction products defining a
visible image corresponding to said image pattern.
Photoconductive titanium(IV) oxide particles having particularly
good properties for use according to the present invention have an
average particle size not greater than 250 millimicrons. Such
finely divided titanium(IV) oxide is preferably produced by
processes involving the pyrolysis of titanium(IV) chloride (see
United Kingdom Pat. Specification No. 1,101,516 filed Apr. 14, 1965
by Itek Corp.). Titanium(IV) oxides having an average particle size
between 25 and 100 millimicrons are preferred.
By "average particle size" is meant the particle size at the peak
of the frequency distribution graph of a mixture of particles
having decreasingly small numbers of larger particles and of
smaller particles.
The ratios by weight of dispersed nonspectrally sensitized
inorganic photoconductive substance to the total amount of
hydrophobic thermoplastic polymer particles are preferably in the
range of 1:3 to 5:3.
The photoconductive compounds of the inorganic type can be
spectrally sensitized or doped, e.g., photoconductive zinc oxide
and titanium(IV) oxide can be very advantageously spectrally
sensitized by means of fluorescein dyes e.g., with eosin and
erythrosin. Photoconductive lead(II) oxide can be doped e.g., with
bismuth.
Suitable inorganic colored photoconductive substances that are
inherently sensitive for visible light are, e.g., photoconductive
lead(II) oxide, cadmium sulphide, cadmium selenide and mixed
crystals of cadmium sulphide selenide which photoconductors
optionally can be used in a mixture containing a white
photoconductor, e.g., photoconductive zinc oxide.
Dispersed photoconductive substances, which on exposure to active
electromagnetic radiation makes a recording layer used according to
the present invention less water permeable, preferably have a grain
size not substantial greater than that of the dispersed hydrophobic
material. So, the grain size is preferably below 10.mu., and more
preferably in the range of 0.1 to 0.5.mu..
The amount by weight of said photoconductive substance in the
recording layer is preferably high enough to obtain a practically
useful image reproduction quality by a washoff development within
exposure times no longer than 10 minutes with conventional
commercial copying apparatus light sources, e.g., U.V.-emitting
mercury vapor tubes as are used in diazocopying machines,
incandescent tungsten filament lamps such as the iodine filled
tungsten filament lamps used in a Dual Spectrum (trade name)
copier. For example 24 30 v./39 w. lamps are used in the exposing
section of the model 76 Dual Spectrum copier.
From the following table sensitivity values as a function of layer
composition can be learned. The recording layer contained 20
percent by weight of glycerol per 100 g. of polyethylene.
The recording layers were exposed through a grey step wedge
(constant 0.1) with a 1500-watt quartz-iodine lamp held at a
distance of 65 cm of the recording layers, which were not in
thermal contact with the wedge. In order to exclude the influence
of heat possibly produced on exposure the latter was carried out on
a thermostatically controlled (20.degree. C.) vacuum frame.
Under the same circumstances all the exposed materials were
subjected to a washoff development in an automatically operating
washoff apparatus as described in the Belgian Pat. No. 715,932
filed May 31, 1968 by Gevaert-Agfa N.V. The light energy
corresponding with the first nonwashed-off step is a measure for
the sensitivity. ##SPC1##
Practical useful results are obtained with 0.3 to 1.7 parts by
weight of a photoconductive substance such as photoconductive zinc
oxide and 1 part by weight of thermoplastic polymer particles such
as polyethylene particles.
In addition to the dispersed hydrophobic particles and/or
hydrophilic binder, the photosensitive layer applied in the present
invention may contain all kinds of ingredients such as
non-light-sensitive pigments, plasticizing agents for the
hydrophilic binder and/or for the dispersed polymers improving
their sticking contact, electrically conductive particles e.g.,
carbon particles, dyes, e.g., dyes which can be bleached,
water-soluble dyes, reaction components for the formation of dyes,
catalysts for color reactions, developing nuclei, light-sensitive
substances, e.g., silver halide, diazonium salts, developing
substances for silver halide or complexed silver halide, finely
divided metal that e.g., can be etched away, reaction components
that can be distilled preferably below 80.degree. C., and other
image-forming material. Further this layer may comprise hardening
agents for the hydrophilic binder and optionally curing agents,
which harden the hydrophobic thermoplastic polymer at elevated
temperatures.
According to a preferred embodiment a photosensitive recording
material according to the present invention contains substances
that increase the photosensitivity without, however, enlarging the
spectral sensitivity. Such substances are found in the class of
hygroscopic compounds. Preferred substances are hygroscopic
polyols, such as glycerin. Hygroscopic or slightly hygroscopic
ionic compounds can increase the sensitivity, e.g., lithium
chloride and potassium bromide.
According to their purpose the materials comprising a
light-sensitive element according to this invention may be composed
differently. By way of example the photosensitive layer containing
the photocoaguable composition may be applied to a hydrophilic
layer, which occasionally serves as a support. By hydrophilic layer
is understood a layer that is wettable by water or by aqueous
solutions. Such a layer may be porous or water-permeable. By way of
example this hydrophilic layer may be composed mainly of natural or
synthetic colloids that are soluble or dispersible in water.
Examples of such layers are a gelatin layer, a light-sensitive
silver halide emulsion layer, a water-permeable nuclei containing
colloid layer for application of the silver complex diffusion
transfer process, a baryta-coating comprising gelatin and barium
sulphate, a gelatin layer containing pigments or dissolved dyes, or
containing reaction components capable to produce a color reaction,
a gelatin layer containing developing substances for silver halide
or complexed silver halide, or a gelatin layer containing finely
divided metal that can be etched away, e.g., silver.
Further, the recording layer according to the present invention can
be applied between two hydrophilic layers, a hydrophilic and a
hydrophobic layer, between two permeable layers, or between a
permeable and an impermeable layer.
A layer or sheet being in contact or water-permeable relationship
with the photosensitive layer may contain all kinds of ingredients,
e.g., ingredients that can be of practical interest to provide
adherence to the recording layer. In other words such a layer may
act as a subbing layer (suitable subbing layers for use in
combination with recording layers of the present invention are
described in the French Patent No. 1,507,874 filed Jan. 10, 1967 by
Gevaert-Agfa N.V.). Other ingredients may be of interest to develop
the recorded image, e.g., pigments, dyes, reaction components for
the formation of dyes, developing substances, reaction components
or dyes, which can be distilled preferably below 80.degree. C.,
light-sensitive substances, e.g., silver halide or diazonium salts,
developing nuclei suited for use in the silver halide diffusion
transfer process, catalysts for color reactions, and/or conductive
particles, e.g., metal particles.
Depending on the use of the recording material the support of the
recording layer may be rigid or flexible.
When flexibility is preferred a sheet element such as e.g., a paper
sheet, a plastic film, a metal foil or the like is used. When
flexibility is unimportant, plates of metal, glass, plastics, fiber
board, cardboard or the like may be used. The support may be
permeable as well as impermeable e.g., it may be water-permeable
such as a wire screen or a web of textile.
Suitable water-impermeable supports are made of hydrophobic resins,
e.g., of cellulose ester derivatives polyester, polystyrene,
hydrophobic metal, hydrophilic metal coated with a hydrophobic
layer e.g., an oxide layer, glass and the like. In order to improve
the adherence of the recording layer to its support one or more
subbing layers may be applied.
Recording according to the present invention can proceed in
different ways according to the method in which radiation is
supplied to the recording element.
It has to be noted, however, that the present invention is not
based on informationwise melting or softening of dispersed
hydrophobic thermoplastic particles in the recording layer and
consequently no informationwise heat absorption in the recording
layer has to taken place.
A short-duration high-intensity electromagnetic exposure producing
a substantial internal heating of the recording layer is not within
the scope of the present invention, about this reference is made to
the Canadian Pat. No. 806,124 of Gevaert-Agfa N.V., issued Feb. 11,
1969. Taking into account the sensitivity of up till now
manufactured recording layers exposures lasting longer than
10.sup.-.sup.1 sec. using continuously operating (no flash lamps)
common copying apparatus radiation sources are applied.
According to one embodiment, a transparent original bearing
light-absorbing indicia is recorded by bringing the photosensitive
element of a recording material according to the present invention
into contact with said original, and exposing said photosensitive
element while in contact to electromagnetic radiation of such
intensity and for such a time as to record the image in terms of
water permeability differences without a substantial increase in
temperature of the portions of said element corresponding to the
transparent portions of the original.
According to another embodiment an opaque or transparent original
is projected onto the recording material (episcopically or
diascopically projection). Thus, the present invention provides the
possibility to make enlarged photographs by projection
exposure.
Before giving some examples for practising the method of the
present invention, a short survey is given of different systems
that are suited for the manufacture of copies and masters for the
reproduction of originals starting from an
electromagnetic-radiation-imaged recording material according to
the present invention. This survey is intended for illustrating the
possibilities and advantages of the invention without limiting
therefore the scope of this invention. According to a first system,
the imagewise differentiation in permeability is utilized for
applying by imagewise diffusion image-forming substance or
substances in the recording element by a liquid treatment or to
transfer such substances from the recording element to a receiving
material respectively, said imagewise diffusion being possible as a
consequence of the permeability differentiation. By way of example
for the first system a dye diffuses in the recording element (layer
or sheet) only on the areas that remain permeable and sufficiently
hydrophilic. Of course, instead of a dye solution, a solution of a
catalyst for initiating a color reaction between components in the
recording material or a solution of a colorless reaction component
capable of giving a color reaction with a colorless or slightly
colored reaction component in the recording material can be
used.
By way of another example for the first system it is possible to
incorporate into the recording element colored substances which can
be bleached out by a bleaching agent diffusing in the areas of the
recording material that remained permeable. According to an
alternative of that system, a conductive substance, e.g., a metal
that can be etched away such as colloidal silver, and that is
homogeneously dispersed in the recording element, is imagewise
etched away by an etching liquid diffusing into the permeable
areas. The photosensitive layer can be applied to an etchable base
material, e.g., a resin sheet coated with aluminum. When using this
material it is possible by imagewise etching to produce a
planographic letter-type or intaglio printing master.
In a method embodiment of image formation wherein diffusion is
applied, the image-forming substance incorporated into the
recording material is transferred by diffusion from the areas that
remain permeable to an image-receiving material. So, it is
possible, e.g., to incorporate a soluble dye into the recording
element or into a layer being in a liquid-permeable relationship
therewith, said dye being capable of diffusing therefrom imagewise
to a receiving material when the photographically exposed recording
element is wetted.
Self-evidently, instead of a dye a colorless reaction component or
catalyst for the formation of a color reaction with a reaction
component in the receiving material can be incorporated into the
recording element.
So, it is Imagewise possible to incorporate into the recording
material silver salts that can be complexated and that in their
dissolved form can diffuse to a receiving material containing
reduction nuclei or development nuclei, whereupon according to the
areas of the recording material that remained permeable, silver is
deposited imagewise.
In these diffusion methods the image-forming substances such as a
dye, a metal that can be etched away, or reaction components need
not be present in the recording element itself; they can also be
incorporated into a layer or support being in a water-permeable
relationship therewith.
According to a second system the portions of the informationwise
electromagnetically irradiated recording material that remained
sufficiently water-permeable are eliminated e.g., by washing out or
degrading of the hydrophilic binder, and by removing the
hydrophobic particles that were not coagulated by exposure. By that
technique a direct visible copy of the information is obtained when
the recording element comprises a dye, e.g., a (colored) pigment
and/or a dissolved dyestuff before exposure.
By applying said second system, a gravure master can be produced by
starting from the imaged recording layer, which is applied to a
metal support that can be etched. After elimination of the portions
of the recording layer that remained permeable and hydrophilic,
e.g., by washing out and after making the portions of the recording
layer left sufficiently resistant to the etching solution the
uncovered metal can be etched away imagewise. In this way e.g.,
printed circuits can be produced. After the elimination, e.g., by
means of an organic solvent, of the portions of the recording layer
left after the washoff development, the etched metal plate
according to the depth and manner of etching can be used as a
planographic printing master, a gravure master or a letterpress
master.
By applying said second system also a stencil or screen-printing
master can be manufactured by starting from an informationwise
electromagnetically irradiated recording material according to the
invention. For this technique either one or both sides of a screen
material are coated with a recording layer, or the screening
material makes part of a self-supporting sheet as described
hereinbefore. As screen material Japan paper (Yoshino paper), nylon
fabrics with a size of mesh of 0.2 to 0.08 mm. and woven bronze
wire are especially suited.
For the screen-printing technique it is known that only on the open
(permeable) areas of the fabric (screen material) ink can pass and
deposit on the material to be printed corresponding to these areas.
The imagewise open areas are obtained according to the present
invention by washing out or degrading the recording layer
composition in the areas where this layer or sheet remained
permeable and hydrophilic.
According to a third system the image portions that remained
permeable and hydrophilic are transferred onto a receiving material
by squeegeeing and tearing out.
This type of transfer is possible if the cohesion of the matter of
the receiving material is larger than that of the matter in the
permeable portions of the recording layer, and if the adhesion
between said permeable portions and the receiving material is
larger than the cohesion of the matter of said permeable areas.
This transfer successfully occurs when separating after pressing
together a wetted informationwise electromagnetically irradiated
recording element according to the present invention from a
receiving material preferably having a hydrophilic and/orporous
surface, e.g., a paper sheet. In that embodiment the recording
layer preferably comprises a hydrophilic binder wherein hydrophobic
thermoplastic polymer particles are dispersed.
The contrary type of transfer is possible if the cohesion of the
matter of the receiving material is less than that of the matter in
the permeable portions of the recording layer, and if the adhesion
between said permeable portions and the receiving material is
larger than that of the matter of said receiving material. E.g. a
dye layer of a carbon paper being little hydrophobic on its
surface, such as is used in the process according to the French
Pat. No. 1,466,223 filed July 30, 1963 by Gevaert Photo-Producten
N.V., after being pressed onto the moistened heat- or
pressure-imaged material, can be transferred imagewise to the
permeable and hydrophilic areas of the recording material on
separating it therefrom. Before pressing the recording layer into
contact with the dye layer, the hydrophilic binder of the recording
layer can be swollen so that a relief image is formed that makes
possible a closer contact with the dye layer.
According to this third system it is thus possible to manufacture
hectographic masters since the pulled out material can contain a
hectographic dye that is soluble in the transfer liquid or can
contain a reaction component forming a dye with a reaction
component present, e.g., in the transfer liquid or transfer
material.
According to a fourth system it is possible by using a low melting
dye in the recording element, to transfer this dye by heating the
imagewise washed-off recording element in contact with a transfer
material.
The following examples illustrate the invention.
The percent ratios are "by weight" if not otherwise indicated.
EXAMPLE 1
A poly(ethylene terephthalate) support of 0.1 mm. thickness was
coated with the following composition in a proportion of 18
g./sq.m.:
20% aqueous dispersion of co(vinylidene chloride/n-tert.-butyl
acrylamide/itaconic acid) (molar ratio 88/10/2) 12 g. 40% aqueous
dispersion of polyethylene having a particle size less than 0.1.mu.
and an average molecular weight comprised between 15,000 and 30,000
12 g. 30% aqueous dispersion of colloidal silica 12 g. ethyl
alcohol 100 g. water 864 g.
This subbing layer was dried at 30.degree. C. On this layer a
light-sensitive layer from the following composition was coated in
a proportion of 50 g./sq.m.:
10% aqueous gelatin solution (Bloom gel strength number: 260 200 g.
40% aqueous dispersion of colloidal polyethylene having a particle
size less than 0.1.mu. and an average molecular weight comprised
between 15,000 and 30,000 200g. 50% aqueous dispersion of
photoconductive zinc oxide (average particle size 0.17.mu.) 320 g.
glycerol 15g. ethyl alcohol 90 g. water 140 g.
The light-sensitive layer was dried at 25.degree. C.
The light-sensitive material thus obtained was vacuum-contact
exposed for 10 minutes through a developed silver halide emulsion
layer containing a negative screen print by using a 1,500-watt
quartz-iodine lamp mounted in a reflector at a distance of 30 cm.
above the vacuum frame.
After exposure the material was rubbed with a soft sponge whilst
abundantly moistening with water of 20.degree. C. The nonexposed
parts were thus whiped off and a relief image was obtained.
Instead of using plain water a 5 percent solution of potassium
thiocyanate or sodium salicylate may be used.
When in the composition of the light-sensitive layer the gelatin
was replaced by polyvinylpyrrolidone, analogous results were
obtained although the differentiation in solubility between exposed
and nonexposed parts was not as high as when gelatin was used.
EXAMPLE 2
A poly(ethylene terephthalate) support of 0.1 mm. thickness
provided with a subbing layer for gelatin was coated with the
following composition at a rate of 30 g./sq.m.:
10 % aqueous gelatin solution 400 g. 40 % aqueous dispersion of
polyethylene having a particle size of less than 0.1 .mu. and an
average molecular weight comprised between 15,000 and 30,000 320 g.
10 % aqueous saponine 40 g. 3 % aqueous solution of the sodium salt
of the condensation product of oleic acid and methyl taurine 40 g.
4 % aqueous formaldehyde 20 g.
The interlayer was dried at 30.degree. C.
On this layer a light-sensitive layer was coated at a rate of 50
g./sq.m. from the following composition:
10 % aqueous gelatin solution 138 g. 40 % aqueous dispersion of
polyethylene having a particle size of less than 0.1 .mu. and an
average molecular weight comprised between 15,000 and 30,000 138 g.
10 % aqueous dispersion of colloidal silver 250 g. 50 % aqueous
photoconductive zinc oxide dispersion (average particle size 0.17
.mu.) 220 g. ethyl alcohol 90 g.
This layer was dried at 25.degree. C.
The material was exposed in a diazo printer Buroza 600 sold by
Atlas, Delft, Holland, at a setting 3, through a developed silver
halide emulsion layer containing a negative halftone print.
After exposure the material was dipped in a conventional bleaching
bath. Only the areas corresponding with the nontransparent parts of
the original were bleached out so that a positive print of the
photographic negative was obtained.
EXAMPLE 3
On a poly(ethylene terephthalate) support provided with the same
subbing layer as described in example 1 was coated a
light-sensitive layer from the following composition at a rate of
50 g./sq.m.:
10 % aqueous gelatin solution 200 g. 40 % dispersion of colloidal
polyethylene described in example 1 200 g. 50 % aqueous dispersion
of photoconductive zinc oxide (average particle size 0.17 .mu.) 320
g. 60 % aqueous dispersion of a green pigment sold under the name
Heliogengrun C.N. Colanyl Teig by Farbwerke Hoechst, AG, West
Germany 40 g. glycerol 15 g. ethyl alcohol 90 g. water 100 g.
The light-sensitive layer was dried at 25.degree. C.
On this layer a line-image was projected by making use of a
conventional transparency projector with a 250-watt lamp positioned
on 1 meter distance from the light-sensitive material and giving a
tenfold linear enlargement of the original. After an exposure time
of 90 minutes the material was treated as in example 1, and a
positive enlarged image of the original was obtained. The same
material was contact-exposed for 3 minutes through a developed
silver halide negative halftone print by making use of a carbon arc
working at 60 a. and 3.times.42 v. (three phase-current) The
diameter of the carbon rods was 20 mm., producing a stable arc of 4
kw. power and placed at a distance of 1 meter. After exposure the
material was treated as described in example 1 and a positive image
of the original was obtained. The same material was contact-exposed
for 10 minutes by using a 900-watt mercury vapor lamp placed at a
distance of 25 cm. After exposure it was treated as the foregoing
one and a same result was obtained. This last exposure was carried
out in a vacuum frame wherein the light-sensitive material was
cooled on a hollow metal plate having cold water (15.degree. C.)
streaming through.
EXAMPLE 4
To a paper support coated with polyethylene and weighing 120
g./sq.m. a subbing layer was applied from the following composition
at a rate of 30 g./sq.m.:
10 % aqueous gelatin solution 200 g. 40 % aqueous dispersion of
polyethylene (see example 1) 160 g. 10 % aqueous saponine 20 g. 50
% aqueous solution of the sodium salt of the condensation product
of oleic acid and methyl taurine 20 g. 4 % aqueous formaldehyde 10
g. polyethylene glycol having an average molecular weight of 20,000
10 g.
This layer was dried at 25.degree. C.
On this layer a heat-sensitive layer was coated at a rate of 40
g./sq.m. from the following composition:
10 % aqueous gelatin solution 200 g. 40 % aqueous dispersion of
polyethylene (see example 1) 200 g. 50 % aqueous photoconductive
zinc oxide dispersion (average particle size 0.17.mu. ) 300 g.
glycerol 15 g. ethyl alcohol 90 g. 16 % aqueous dispersion of
carbon (average particle diameter = 0.1 .mu.) with 2 %
poly-N-vinylpyrrolidone 50 g.
This layer was dried at 25.degree. C., exposed and treated as in
example 1. A positive image of the silver halide original was
obtained.
EXAMPLE 5
A poly(ethylene terephthalate) base of thickness 0.1 mm. provided
with a subbing layer described in example 1 was coated with the
following composition at a rate of 50 g./sq.m.:
10 % aqueous solution of gelatin 200 g. 40 % aqueous dispersion of
polymethyl methacrylate particles sizing on the average 0.12 .mu.
and having an average molecular weight of 1,300,000 200 g. 50 %
aqueous dispersion of photoconductive zinc oxide (average particle
size 0.17 .mu.) 320 g. glycerol 15 g. ethyl alcohol 90 g.
This coating was dried at 30.degree. C.
Exposure and development were done as described in example 1 and
analogous results were obtained.
Same results were obtained when the 200 g. polymethyl methacrylate
were replaced by 374 g. of a 22 percent dispersion of polystyrene
with an average particle size 0.13 .mu. and an average molecular
weight 50,000.
EXAMPLE 6
A poly(ethylene terephthalate) base of thickness 0.1 mm. provided
with a matted layer consisting mainly of an urea formaldehyde resin
and crystalline silica was coated with a subbing layer of the
following composition at a rate of 15 g./sq.m.:
aqueous polyethylene dispersion (as described in example 1) 19 g.
aqueous dispersion of a copolymer of butadiene and methyl
methacrylate (50/50) 20 g. 10 % aqueous colloidal dispersion of
silica 50 g. ethyl alcohol 50 g. water 361 g.
This layer was dried at 35.degree. C.
Onto the layer a photosensitive layer was coated at a rate of 50
g./sq.m. from the following composition:
10 % aqueous solution of gelatin 200 g. mixture of aqueous
dispersion of colored pigments: 4 parts of Per- manent Gelb HR
Colanyl Teig (a yellow pigment insoluble in water, sold by
Farbwerke Hoechst AG, Frankfurt (M)-Hochst, West Germany), 20 parts
of Permanent Carmin FBB Colanyl Teig (a magenta pigment insoluble
in water, sold by Farbwerke Hoechst AG) and 26 parts of
Heliogengrun CN Colanyl Teig (a green pigment insoluble in water,
sold by Farbwerke Hoechst AG 50 g. 50 % aqueous dispersion of
photoconductive zinc oxide (average particle size 0.15 .mu.) 300 g.
20 % aqueous dispersion of polyethylene prepared as described
hereinafter 400 g. ethyl alcohol 90 g. glycerol 15 g.
The material thus obtained was exposed for 5 minutes through a
developed silver halide emulsion layer containing a negative silver
print by using a 1,500-watt quartz-iodine lamp, placed at a
distance of 30 cm.
After exposure the material was treated as described in example 1
and a sharp positive print was obtained.
Same results were obtained when the photosensitive composition was
coated on a thin aluminum sheet.
Preparation of the latex
In a 4,000 cc. steel pressure tube were placed
a partly oxidized polyethylene prepared according to United Kingdom
Patent 997,135 filed Oct. 25, 1963 by Grace & Co., W.R., having
the following characteristics: average molecular weight:
7,000-crystalline melting point: 125-130.degree. C.--acid number:
26-30 40 g. n-hexadecyloxydecaoxyethylene 12.4 g. water 150 g.
The pressure tube was sealed and rotated at 30-40 r.p.m. at
190.degree.-200.degree. C. for 1 hour in order to disperse the
mixture. Then the tube was allowed to cool slowly to room
temperature. The obtained dispersion was ready for use as such.
EXAMPLE 7
A transparent non-heat-conductive poly(ethylene terephthalate)
support of 0.1 mm. thickness was provided with a subbing layer of
the following composition at a rate of 18 g./sq.m.:
20 % aqueous dispersion of copolymer of vinylidenechloride, N-tert.
butylacrylamide and itaconic acid (molar ratio 88/10/2) 12 g. 40 %
aqueous dispersion of polyethylene having a particle size of less
than 0.1 .mu. and an average molecular weight comprised between
15,000 and 30,000 12 g. 30 % aqueous dispersion of colloidal silica
12 g. ethyl alcohol 100 g. water 864 g.
This subbing layer was dried at 30.degree. C. To this subbing layer
a light-sensitive layer was applied from the following composition
at a rate of 40 g./sq.m.:
10 % aqueous solution of gelatin 100 g. 20 % aqueous dispersion of
polyethylene prepared as described hereinafter 50 g. 50 % aqueous
dispersion of photoconductive zinc oxide prepared by oxidation of
zinc vapor and having an average particle size of 0.17 .mu. 13 g.
glycerol 4 g. eosine 0.5 g. water 233 g.
The coating was dried at 45.degree. C.
The material thus obtained was contact-exposed for 1 minute through
a developed photographic silver halide emulsion layer containing a
negative halftone silver image on a transparent cellulose
triacetate support. In the exposure a 500-watt incandescent lamp
was used placed at a distance of 30 cm.
After the exposure the light-sensitive layer was gently rubbed with
a soft sponge while being wetted abundantly with water of
50.degree. C.
A positive halftone copy of the original was obtained.
Preparation of the polyethylene latex
In a 400 cc. steel pressure tube were placed:
a partly oxidized polyethylene prepared according to United Kingdom
Patent 997,135 mentioned above, by the oxidation of polyethylene
(average molecular weight: 7,000-- crystalline melting point:
125.degree.-130.degree. C.-- acid number: 26-30) 40 g.
n-hexadecyloxy decaoxyethylene 12.4 g. water 150 g.
The pressure tube was sealed and rotated at 30-40 r.p.m. at
190.degree.-200.degree. C. for 1 hour in order to disperse the
mixture. Then the tube was allowed to cool slowly to room
temperature. The obtained dispersion was ready for use as such.
EXAMPLE 8
On the light-sensitive material described in example 7, a negative
line transparency was projected by means of a conventional
projector with a 250-watt lamp positioned at 1 meter from the
light-sensitive layer and enlarging the original tenfold. After an
exposure time of 10 minutes the material was treated as described
in example 7. A positive enlarged copy of the transparency was
obtained.
EXAMPLE 9
The light-sensitive material as described in example 7 was placed
with its light-sensitive layer into contact with the printed side
of a graphic original on a paper base.
The material was exposed for 2 minutes through its transparent
support in a flat contact-exposure apparatus containing 8 white
fluorescent light tubes of 200 watt each placed under a glass plate
of 45 cm. .times. 65 cm. and yielding a 20,000 lux light
output.
After exposure, the material was rubbed with a soft sponge wetted
with water of 35.degree. C. The parts of the light-sensitive
material corresponding with the image parts of the original were
washed off. A negative copy of the original was obtained.
EXAMPLE 10
A poly(ethylene terephthalate) support of 0.1 mm. thickness
provided with a subbing layer described in example 7 was coated
with the following composition at a rate of 60 g./sq.m.:
10 % aqueous solution of gelatin 100 g. 20 % aqueous dispersion of
polyethylene prepared as described in example 7 50 g. glycerol 5 g.
aqueous dispersion of carbon black containing 36 g. of carbon black
(average particle size: 0.1 .mu.), 23 g. of water, 30 g. of
ethylene glycol and 6 g. of nonylphenyl (diethylene oxide) 9-10 50
g. water 350 g. lead(II) oxide (yellow type) powder doped with 30
p.p.m. of bismuth (specific surface: 1.56 sq.m./g. 40 g.
The lead(II) oxide powder was dispersed with vigorous stirring. The
coating was dried at 30.degree. C.
The light-sensitive material thus obtained was vacuum-contact
exposed for 10 minutes through a developed silver halide emulsion
layer containing a negative halftone print by means of a 1,500-watt
quartz-iodine lamp mounted in a reflector at a distance of 30 cm.
above the vacuum frame.
After exposure, the material was rubbed with a soft sponge
abundantly moistened with water of 20.degree. C. so that the
nonexposed parts were whiped off. A sharp black positive relief
image was obtained.
Analogous results were obtained by replacing lead(II) oxide by a
same amount of cadmium sulphide powder, red lead oxide (Pb.sub.3
O.sub.4) powder, mercury(II) oxide powder, manganese(IV) oxide
powder or chrominum(III) oxide powder. The average particle size of
the powder particles was between 1 and 5 .mu..
EXAMPLE 11
A poly(ethylene terephthalate) support of 0.1 mm. thickness
provided with a subbing layer as described in example 7 was coated
with the following composition at a rate of 45 g./sq.m.:
10 % aqueous solution of gelatin 200 g. 20 % aqueous dispersion of
polyethylene (prepared as described in example 7) 150 g. eosine
0.25 g. glycerol 8 g. 5 % aqueous solution of isononyphenyl phenyl
deca-ethoxanol 20 g. water 72 g.
The coating was dried at 30.degree. C. The material thus obtained
was exposed for 3 min. through a developed silver halide emulsion
layer containing a negative halftone (silver) print by using a
1,500-watt quartz-iodine lamp placed at a distance of 70 cm. After
exposure the material was treated as described in example 7. A
sharp positive print was obtained. Analogous results were obtained
when eosine was replaced by a same amount of Acridine Orange R
known as Basic Orange 14 (C.I. 46,005) ##SPC2##
EXAMPLE 12
On a subbed cellulose triacetate support were coated the following
dispersions containing respectively: ##SPC3##
These compositions were coated at such a rate that after drying
recording layers of 40 .mu. thickness were obtained.
The recording materials were now laid with their supports onto a
transparent line original and exposed through the latter for 30
minutes by means of a Philips HPR 125 lamp placed at a distance of
30 cm. Thereupon the exposed light-sensitive layers were treated
with water of 35.degree. C. resulting in the removal of the
nonexposed portions of the recording layers.
The sensitivity of the recording layers formed with said
compositions A, B, C and D respectively was in the following order:
A<B<C<D.
EXAMPLE 13
Example 12 was repeated with the difference, however, that in the
recording layer the 2 g. of eosine were replaced by 12 g. of yellow
lead(II) oxide and the sodium hexametaphosphate and the lead(II)
oxide were ball-milled in demineralized water, for 1 hour, before
the other ingredients were added.
After imagewise exposure for 5 minutes by means of a Philips HPR
125 lamp and a treatment with water of 35.degree. C., only the
nonexposed portions of the different recording layers were
removed.
The sensitivity of the recording layers formed with said
compositions A, B, C and D respectively was in the following order:
A<B<C<D.
EXAMPLE 14
A transparent non-heat-conductive poly(ethylene terephthalate)
support of 0.1 mm. thickness was provided with a subbing layer of
the following composition at a rate of 18 g./sq.m.:
20 % aqueous dispersion of copolymer of vinylidene chloride,
N-tert.-butyl acrylamide and itaconic acid (molar ratio 88/10/2) 12
g. 40 % aqueous dispersion of polyethylene having a particle size
of less than 0.1 .mu. and an average molecular weight comprised
between 15,000 and 30,000 12 g. 30 % aqueous dispersion of
colloidal silica 12 g. ethyl alcohol 100 g. water 864 g.
This subbing layer was dried at 30.degree. C. To this subbing layer
a light-sensitive layer was applied from the following composition
at a rate of 100 g./sq.m.:
10 % aqueous solution of gelatin 200 g. 20 % aqueous dispersion of
polyethylene prepared as described hereinafter 100 g. 50 % aqueous
dispersion of photoconductive zinc oxide prepared by the oxidation
of zinc vapor (the zinc oxide grains have an average particle size
of 0.17 .mu.) 50 g. glycerol 4 g. 5 % aqueous solution of isooctyl-
phenyl-poly(ethylene oxide).sub.n (n=9) 10 g. carbon black
dispersion containing 36 g. of carbon black, 23 g. of water, 30 g.
of ethylene glycol and 6 g. of nonylphenyl-poly(ethylene
oxide).sub.n (n=9) 10 g.
The coating was dried at 35.degree. C. The material thus obtained
was contact-exposed for 10 minutes through a developed photographic
silver halide emulsion layer containing a negative continuous tone
silver image on a transparent cellulose triacetate support. In the
exposure a flat contact-exposure apparatus was used containing
eight white fluorescent light tubes of 20 watt each placed below a
glass plate of 45 cm. .times. 60 cm. and yielding a light-output of
20,000 lux. During said exposure the layer containing the silver
image was held in intimate contact with the polyethylene
terephthalate support of the light-sensitive layer.
After exposure the light-sensitive layer was gently rubbed with a
soft sponge while being wetted abundantly with water of 50.degree.
C.
A positive continuous tone copy of the original was obtained.
Preparation of the polyethylene latex
In a 4,000 cc. steel pressure tube were placed:
a partly oxidized polyethylene prepared according to United Kingdom
Patent 997,135 mentioned above, by the oxidation of polyethylene
(average molecular weight: 7,000-- crystalline melting point:
125.degree.-130.degree. C.-- acid number: 26-30) 40 g.
n-hexadecyloxy decaoxyethylene 12.4 g. water 150 g.
The pressure tube was sealed and rotated at 30-40 r.p.m. at
190.degree.-200.degree. C. for 1 hour in order to disperse the
mixture. Then the tube was allowed to cool slowly to room
temperature. The obtained dispersion was ready for use as such.
EXAMPLE 15
A poly(ethylene terephthalate) support of 0.1 mm. thickness
provided with a subbing layer as described in example 14 was coated
with the following composition at a rate of 40 g./sq.m.:
1018 % aqueous solution of gelatin 100 g. 20 % aqueous dispersion
of polyethylene prepared as described in example 14 50 g. 50 %
aqueous dispersion of photoconductive zinc oxide prepared by
oxidation of zinc vapor and having an average particle size of
0.17.mu. 13 g. glycerol 4 g. eosine 0.5 g. water 233 g.
The coating was dried at 45.degree. C. The material thus obtained
was contact-exposed for one minute through a developed photographic
silver halide emulsion layer containing a negative halftone silver
image on a transparent cellulose triacetate support. For exposing a
500-watt incandescent lamp was used placed at a distance of 30
cm.
After exposure the material was treated as described in example 14.
A sharp positive print was obtained.
EXAMPLE 16
On the light-sensitive material described in example 15, a line
transparency was projected by means of a conventional projector
with a 250-watt lamp positioned at 1 meter from the light-sensitive
layer and enlarging the original tenfold. After an exposure time of
10 minutes the material was treated as described in example 14. A
positive enlarged copy of the transparency was obtained.
EXAMPLE 17
The light-sensitive material as described in example 15 with its
light-sensitive layer was placed into contact with the printed side
of a graphic original on a paper base.
The material was exposed for 2 minutes through its rear side in a
flat contact-exposure apparatus containing eight white fluorescent
light tubes of 20 watt each placed under a glass plate of 45 cm.
.times. 65 cm. and yielding a 20,000 lux light output.
After exposure, the material was rubbed with a soft sponge wetted
with water at 35.degree. C. The parts of the light-sensitive
material corresponding with the image parts of the original were
washed away. A negative copy of the original was obtained.
EXAMPLE 18
A poly(ethylene terephthalate) support of 0.1 mm. thickness was
provided with a subbing layer of the following composition in a
proportion of 18 g./sq.m.:
20% aqueous dispersion of copolymer of vinylidene chloride,
N-tert.-butyl acrylamide and itaconic acid (molar ratio 88/10/2) 12
g. 40 % aqueous dispersion of polyethylene having a particle size
of less than 0.1.mu. and an average molecular weight comprised
between 15,000 and 30,000 12 g. 30 % aqueous dispersion of
colloidal silica 12 g. ethyl alcohol 100 g. water 864 g.
This subbing layer was dried at 30.degree. C. To this subbing layer
a light-sensitive layer of the following composition was applied in
a proportion of 40 g./sq.m.:
20% aqueous dispersion of polyethylene prepared as described
hereinafter 50 g. 50% aqueous dispersion of photoconductive zinc
oxide prepared by the oxidation of zinc vapor (the zinc oxide
grains have an average particle size of 0.17 .mu.) 50 g. aqueous
dispersion of carbon black containing 36 g. of carbon, 23 g. of
water, 30 g. of ethylene glycol and 6 g. of
nonylphenylpoly(ethylene oxide).sub.n (n=9) 50 g. glycerol 4 g.
water 240 g.
The coating was dried at 35.degree. C.
The light-sensitive material thus obtained was vacuum contact
exposed for 10 minutes through a developed silver halide emulsion
layer containing a negative screen print by using a 1,500-watt
quartz-iodine lamp mounted in a reflector at a distance of 30 cm.
above the vacuum frame.
After exposure the material was rubbed with a soft sponge while it
was kept moist with water of 20.degree. C. The nonexposed parts
were thus wiped off and a black relief image was obtained.
Preparation of the Polyethylene Latex
In a 4,000 cc. steel pressure tube were placed:
a partly oxidized polyethylene prepared according to United Kingdom
Patent 997,135 mentioned above (average molecular weight: 7,000--
crystalline melting point: 125.degree.-130.degree. C.-- acid
number: 26-30) 40 g. n-hexadecyloxydecaoxyethylene 12.4 g. water
150 g.
The pressure tube was sealed and rotated at 30-40 r.p.m. at
190.degree.-200.degree. C. for 1 hour in order to disperse the
mixture. Then the tube was allowed to cool slowly to room
temperature. The obtained dispersion was ready for use as such.
EXAMPLE 19
Subbed cellulose triacetate base strips of 0.1 mm. thickness were
separately coated with one of the following compositions pro rata
of 50 g./sq.m.:
The amounts by weight are in grams.
10 % aqueous solution Polymer of caseine adjusted dispersion to pH9
with Na.sub.2 CO.sub.3 A Water
__________________________________________________________________________
A1 340 85 0 A2 250 125 7 A3 170 170 42 A4 100 200 82 A5 70 215 97
A6 50 225 107 Polymer dispersion B B1 340 85 0 B2 250 125 7 B3 170
170 42 B4 100 200 82 B5 70 215 97 B6 50 225 107 Polymer dispersion
C C1 340 85 0 C2 250 125 7 C3 170 170 42 C4 100 200 82 C5 70 215 97
C6 50 225 107
__________________________________________________________________________
polymer dispersion A is a 20 percent colloidal dispersion of
polyethylene having a particle size less than 0.1 .mu. and an
average molecular weight comprised between 15,000 and 30,000 and
made by emulsion polymerization.
Polymer dispersion B is a 20 percent colloidal dispersion of a
polyethylene prepared as follows: in a 4,000 cc. steel pressure
tube were placed a mixture containing a partly oxidized
polyethylene mass prepared according to a method described in the
United Kingdom Pat. No. 997,135 mentioned above by the oxidation of
polyethylene together with a dispersing agent and having the
following composition:
polyethylene (average molecular weight 7,000 -crystalline melting
point 125.degree.-130.degree. C.-acid number 26- 30) 40 g.
n-hexadecyldecaoxyethylene 12.4 g. water 150 g.
The pressure tube was sealed and rotated at 30-40 r.p.m. at
190.degree.-200.degree. C. for 1 hour in order to disperse the
polyethylene. Then the tube was allowed to cool slowly to room
temperature and the obtained dispersion was ready for use as
such.
Polymer dispersion C is a 40 percent by weight aqueous dispersion
of polymethylmethacrylate sold under the name Neocryl A 400 by
Polyvinyl Chem. Inc., Wilmington, Mass., U.S.A. which dispersion
was diluted to 20 percent by weight solid content.
To each of the compositions A1, A2, etc. 4 g. of glycerol, 4 g. of
potassium bromide and 100 g. of a 0.25 percent aqueous solution of
erythrosine was added.
The light-sensitive layers were dried at 25.degree. C.
The light-sensitive material thus obtained was vacuum-contact
exposed through a developed silver halide emulsion layer containing
a negative halftone print using a 1,500-watt quartz-iodine lamp
mounted at a distance of 65 cm. above the vacuum frame and
supplying 24,000 lux on the recording layer involved.
After exposure the respective recording layers were rubbed with a
soft sponge while abundantly moistening with water of 20.degree. C.
The unexposed or underexposed parts are thus wiped off and a relief
image was obtained.
The following table represents the energy required for obtaining
image differentiation in each of the recording layers. ##SPC4##
25
EXAMPLE 20
A subbed triacetate base of 0.1 mm. thickness was coated with the
following composition pro rata of 50 g./sq.m. :
10 % aqueous solution of caseine 100 g. 20 % aqueous dispersion of
dibutylphthalate 200 g. glycerol 4 g. potassium bromide 4 g. water
64 g. 0.20 % aqueous solution of eosine 100 g.
The layer was dried at 20.degree. C., exposed as described in
example 1 and developed by a washoff treatment. Practical useful
results were obtained. The dispersion of dibutylphthalate was
prepared by mixing for 10 minutes in an Ultra-Turrax mixer sold by
Janke & Kunkel K.G., West Germany at a speed of 6,000
r.p.m.:
dibutylphthalate 40 g. water 160 g. isooctylphenyl poly(ethylene
oxide).sub.9.sup.-10 3 g. nonylphenyl poly(ethylene
oxide).sub.9.sup.-10 3 g.
Same results were obtained when the dibutylphthalate was replaced
by paraffin oil or carnauba wax.
EXAMPLE 21
A Japan paper weighing 14 g./sq.m. was soaked with a dispersion
consisting of:
10 % aqueous solution of caseine 100 g. 20 % aqueous polymer
dispersion B of Example 19 200 g. glycerol 4 g. potassium bromide 4
g. 0.25 % aqueous solution of erythrosine 100 g.
Upon drying this Japan paper comprised 12 g. solid substance per
sq.m. The thus treated paper was contact exposed for 5 minutes
through a developed silver halide emulsion containing a positive
line-image with a quartz-iodine lamp of 1,500-watt placed at a
distance of 65 cm.
After exposure the paper was dipped in water of 20.degree. C. while
being rubbed with a soft sponge. By this treatment the nonexposed
parts were washed away and after drying a positive stencil master
of the original was obtained.
* * * * *