U.S. patent number 3,847,611 [Application Number 05/334,246] was granted by the patent office on 1974-11-12 for photographic process for forming a positive color image utilizing a photochromic composition containing a spiropyran compound, a photoactivator and poly-n-vinyl- carbazole.
This patent grant is currently assigned to AGFA-Gevaert. Invention is credited to Jozef Willy Van Den Houte, Freddy Ghisleen Van Royen.
United States Patent |
3,847,611 |
Van Royen , et al. |
November 12, 1974 |
PHOTOGRAPHIC PROCESS FOR FORMING A POSITIVE COLOR IMAGE UTILIZING A
PHOTOCHROMIC COMPOSITION CONTAINING A SPIROPYRAN COMPOUND, A
PHOTOACTIVATOR AND POLY-N-VINYL- CARBAZOLE
Abstract
A photographic process in which a positive colour image is
produced by the steps of: Providing a recording material which
comprises in intimate admixture: 1. at least one spiropyran
compound, 2. at least one organic polyhalogen compound sensitive to
ultraviolet radiation and capable of producing on exposure with
ultraviolet radiation with the spiropyran compound a dye salt and
in working relationship with said mixture a compound containing
N-vinylcarbazole units, Image-wise exposing the recording material
to activating electromagnetic radiation to such a degree that a
latent dye image or faintly coloured visible dye image is obtained,
Overall heating the image-wise exposed recording material to such a
degree that by a subsequent overall exposure of the heated
recording material with infrared radiation optionally mixed with
white light a positive colour image is formed, and Overall exposing
the thus overall heated recording material with infrared radiation
optionally mixed with white light producing thereby a positive
colour image.
Inventors: |
Van Royen; Freddy Ghisleen
(Wommelgem, BE), Van Den Houte; Jozef Willy (Berchem,
BE) |
Assignee: |
AGFA-Gevaert (Mortsel,
BE)
|
Family
ID: |
26260154 |
Appl.
No.: |
05/334,246 |
Filed: |
February 21, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Jun 26, 1972 [GB] |
|
|
29917/72 |
|
Current U.S.
Class: |
430/334; 430/336;
430/962 |
Current CPC
Class: |
G03C
1/685 (20130101); G03C 5/56 (20130101); G03C
1/675 (20130101); Y10S 430/163 (20130101) |
Current International
Class: |
G03C
5/56 (20060101); G03C 1/685 (20060101); G03C
1/675 (20060101); G03c 005/24 (); G03c
001/52 () |
Field of
Search: |
;96/48R,48HD,9PC,9R |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
3607266 |
September 1971 |
Yamada et al. |
3697276 |
October 1972 |
Lewis et al. |
|
Foreign Patent Documents
Primary Examiner: Klein; David
Assistant Examiner: Louie, Jr.; Won H.
Attorney, Agent or Firm: Daniel; William J.
Claims
We claim:
1. A photographic process for producing a positive color image in a
recording material which comprises in intimate admixture:
1. at least one spiropyran compound which is a spirobenzopyran, a
spirodinaphthopyran, a spirobenzonaphthopyran, a
1,3,3-trimethylindolinobenzospiropyran, a
1,3,3-trimethylindolinonaphtospiran or a spiropyran containing a
condensed anthracene or phenanthrene nucleus; and
2. at least one organic polyhalogen compound that is sensitive to
ultraviolet radiation and corresponds to the general formula:
##SPC7##
in which:
each of A, B, X and Y is a chlorine, bromine or iodine atom, or
one of A, B, X or Y represents an alkyl group, an aryl group, or an
aroyl group, and the remainder chlorine, bromine or iodine, or at
least two of A, B, X or Y represent an aromatic acyl group, and the
remainder chlorine, bromine or iodine; and
3. within said recording material in working contact with said
mixture a polymer of N-vinylcarbazole,
which comprises the steps of:
imagewise exposing said recording material to activating
electromagnetic radiation to an extent forming a latent dye image
or faintly colored visible dye image,
overall heating the imagewise exposed recording material to such an
extent that upon subsequent overall exposure of the heated
recording material to infrared radiation optionally mixed with
white light a positive color image is formed, and
overall exposing the thus overall heated recording material with
infrared radiation optionally mixed with white light producing
thereby a positive color image.
2. The process of claim 1 wherein said polymer is of
N-vinylcarbazole and up to 80 mol % of a different vinyl
monomer.
3. A photographic process according to claim 1 wherein said
spiropyran compound corresponds to one of the following general
formulae: ##SPC8##
wherein:
R, r.sub.1, r'.sub.1, r.sub.2, r'.sub.2, r.sub.3 and R'.sub.3 each
represent hydrogen, alkyl, alkyl substituted with halogen, alkyl
substituted with an ester group, alkyl substituted with a carboxyl
group, alkyl substituted with a N-phenylcarbamyl group, a hydroxy
group, an alkoxy group, an aryloxy group, a phenyl group,
piperidyl, acetyl, halogen, nitro, or R.sub.1 and R'.sub.1 together
represent a --(CH.sub.2).sub.n -- chain wherein n = 2 or 3 to link
the carbon atoms in the 3 and 3' positions together.
4. A photographic process according to claim 1, wherein the overall
heating of the recording material is continued during the overall
infrared exposure at a reduced temperature.
5. A photographic process according to claim 1, in which the
spiropyran compound and the organic polyhalogen compound that is
sensitive to ultraviolet radiation are incorporated into a
recording layer containing as binding agent a polymer comprising
N-vinylcarbazole units.
6. A photographic process according to claim 5, wherein the binding
agent consists of poly-N-vinylcarbazole.
7. A photographic process according to claim 1, wherein the
polyhalogen compound is carbon tetrabromide and/or iodoform.
8. A photographic process according to claim 1, wherein the
recording material contains triphenylstibine as fog-inhibiting
compound.
9. A photographic process according to claim 1, wherein such
spiropyran compound is used in admixture with a 1- to 20-fold
amount by weight of the organic polyhalogen compound that is
sensitive to ultraviolet radiation.
10. A photographic process according to claim 9, wherein as
fog-inhibiting compound triphenylstibine is used in a weight ratio
range of 1:1 to 1:10 with respect to the spiropyran compound.
11. A photographic process according to claim 1, wherein the
image-wise exposure is to ultraviolet radiation and/or visible
light.
12. A photographic process according to claim 1, wherein the
overall heating is at a temperature in the range of 120.degree. to
150.degree.C for a period of 5 to 20 sec.
13. A photographic process according to claim 12, wherein the
overall heating is continued during the overall exposure to
infrared radiation but at a temperature below 120.degree.C.
Description
This invention relates to the production of positive colour images
with recording materials containing a mixture of a photosensitive
polyhalogen compound and a dye precursor compound and to recording
materials containing such mxiture.
Non-silver free-radical photography by means of recording materials
containing a mixture of a photosensitive polyhalogen compound such
as carbon tetrabromide and a dye precursor compound such as leuco
crystal violet have been described already in the United Kingdom
Pat. Specification No. 1,180,883.
These recording materials are suited for the production of
print-out colour images i.e. colour images having reversed image
values with respect to the original.
It is an object of the present invention to provide a photographic
colour-forming process of the free-radical type resulting in the
production of positive colour images i.e. images having the same
image values as the original.
The process of the present invention includes the steps of:
PROVIDING A RECORDING MATERIAL, WHICH COMPRISES IN INTIMATE
ADMIXTURE:
1. at least one spiropyran compound,
2. at least one organic polyhalogen compound sensitive to
uiltraviolet radiation and capable of producing on exposure with
ultraviolet radiation with the spiropyran compound a dye salt and
in working relationship with said mixture a compound containing
N-vinylcarbazole units,
IMAGE-WISE EXPOSING THE RECORDING MATERIAL TO ACTIVATING
ELECTRO-MAGNETIC RADIATION, PREFERABLY U.V. radiation, to such a
degree that a latent dye image or faintly coloured visible dye
image is obtained,
OVERALL HEATING THE IMAGE-WISE EXPOSED RECORDING MATERIAL TO SUCH A
DEGREE THAT BY A SUBSEQUENT OVERALL EXPOSURE OF THE HEATED
RECORDING MATERIAL WITH INFRARED RADIATION OPTIONALLY MIXED WITH
WHITE LIGHT A POSITIVE COLOUR IMAGE IS FORMED, AND
OVERALL EXPOSING THE THUS OVERALL HEATED RECORDING MATERIAL WITH
INFRARED RADIATION OPTIONALLY MIXED WITH WHITE LIGHT PRODUCING
THEREBY A POSITIVE COLOUR IMAGE.
Preferred spiropyran compounds for use according to the present
invention contain at least one pyran ring having in the ortho- and
meta-positions with respect to the oxygen atom a condensed benzo or
naphtho ring or other aromatic polycyclic ring system including
these condensed rings or ring systems in substituted state, e.g. an
anthraceno or a phenanthreno ring system e.g. as present in a
spirodibenzopyran, a spirodinaphthopyran, a spirobenzonaphthopyran,
a 1,3,3-trimethylindolinobenzospiropyran, a
1,3,3-trimethylindolinonaphthospiropyran or such spiropyrans
containing condensed aromatic nuclei of the anthracene or
phenanthrene type.
In said spiropyrans the pyran rings, the condensed benzo, the
condensed higher atomatic rings as well as the
1,3,3-trimethylindolino ring may be substituted.
Suitable substituents therefor are, e.g., hydrocarbon groups such
as alkyl groups, e.g. lower alkyl groups such as methyl,
substituted alkyl groups e.g. substituted with halogen, or
phenyl-substituted alkyl groups, alkylene ester groups e.g. a
--CH.sub.2 --COOC.sub.2 H.sub.5 group, alkylene carboxyl groups
e.g. a --CH.sub.2 --COOH group, alkylene carbonamide groups or such
groups in which the carbonamide group is substituted e.g. a
##SPC1##
group, an acyl group e.g. acetyl, halogen, nitro, hydroxy, an
alkoxy or aryloxy group or a substituent linking together the
carbon atoms in 3,3'-position in the spiropyran system e.g. a
(CH.sub.2).sub.n -chain wherein n is 2 or 3.
General formulae covering particularly suited spiropyrans are the
following: ##SPC2##
wherein:
each of R, R.sub.1, R'.sub.1, R.sub.2, R'.sub.2, R.sub.3 and
R'.sub.3 represents hydrogen, an aliphatic group including a
substituted aliphatic group e.g. a (C.sub.1 -C.sub.20) alkyl group
including such an alkyl group in substituted form, e.g. methyl,
ethyl, propyl, amyl or hexadecyl, an halogen-substituted alkyl
group, an alkylene ester group e.g. --CH.sub.2 --COOC.sub.2
H.sub.5, an alkylene carboxyl group e.g. --CH.sub.2 --COOH, an
alkylene carbonamide group or such a group in which the carbonamide
group is substituted e.g. ##SPC3##
an acyl group, halogen, nitro, hydroxy, an alkoxy or aryloxy group,
a phenyl group or a substituted phenyl group, piperidyl, or R.sub.1
and R'.sub.1 together represent a --(CH.sub.2).sub.n -- chain
wherein n = 2, or 3 to link the carbon atoms in the 3- and
3'-positions together.
Suited spiropyran compounds and their preparation are described in
the published German patent application Nos. 1,274,655 filed Dec.
15, 1965 by Telefunken Patentverwertungs G.m.b.H., 1,269,665;
1,286,110; 1,286,111 and 1,286,112 all filed Sept. 30, 1966 by
Telefunken Patentverwertungs G.m.b.H., and by W. Dilthey, Berres,
Holterkoff, Wubken, J. Prakt. Ch.[2]114, 187 (1926), by C. F.
Koelsch and W. R. Workman in J. Amer. Chem. Soc. 74, 6288 (1952)
and by I. M. Heilbron and G. F. Howard in J. Chem. Soc. (1934),
1571.
Preferred spiropyran compounds are spirodinaphthopyrans and
spirobenzonaphthopyrans including such compounds wherein the
naptho- and/or benzo ring(s) is (are) substituted.
An illustrative list of particularly useful spiropyran compounds is
given in the following Table 1. ##SPC4##
In order to illustrate in more details the preparation of the
spirobi(arylopyran)-compounds and the sprio(indolino,
arylopyran)-compounds the following preparation receipts are
given:
Preparation 1
Preparation of 3-methyldi-.beta.-naphthospiropyran (compound 2 of
Table 1)
In a 2 litre three-necked flask, fitted with a reflux condenser and
a gas inlet tube reaching nearly the bottom of the flask are
introduced:
ethanol 1 litre butanone 22 ml (0.25 mole)
2-hydroxy-1-naphthaldehyde 86 g (0.5 mole)
The flask shaken until partial dissolution of the ingredients. Dry
hydrogen chloride gas is introduced at a rate, which allows
complete absorption and the start of ethanol reflux. Thereupon the
already strongly blue coloured mixture is cooled in a mixture of
ice and sodium chloride and the introduction of hydrogen chloride
gas is continued until saturation. In the reaction mixture green
crystals of pyrylium salt form and the crystallization is allowed
to proceed overnight in a refrigerator.
The pyrylium salt formed is separated by suction, washed with
ethanol and thereupon brought into suspension in 300 ml of
ethanol.
Whilst stirring, a 10 percent by weight aqueous solution of
ammonium hydroxide is added until the mixture is definitely
alkaline. During that operation the mixture turns colourless.
The obtained crystalline product is separated by suction, washed
with water and dried.
Finally the spiropyran compound is recrystallized from 600 ml of
benzene and again separated and dried under reduced pressure at
50.degree.-60.degree.C.
Yield: 45 g. Melting point: 204.degree.C.
PREPARATION 2
Preparation of 1,3,3-trimethylindolinobenzopyrylospiran (compound
22 of Table 1)
In a 100 ml flask fitted with a reflux condenser are introduced the
following ingredients:
salicylaldehyde 3.7 g (0.03 mole)
1,3,3-trimethyl-2-methylene-indolenine 5.1 g (0.03 mole) ethanol 90
ml
The solution is refluxed for 2 h whereupon it is cooled and
filtered.
To the filtrate water is added for separation of a solid product.
The solid is separated by suction, washed with water and dried
under vacuum conditions.
The spiran compound is recrystallized from 15 ml of hexane.
Yield: 5 g. Melting point: 93.degree.-94.degree.C.
It is assumed that during the photoexposure a dyestuff salt having
the pyrylium structure forms when a spirobi(arylopyran) compound is
used and a dyestuff salt having the indolinium salt structure forms
when a spiro(indolino-arylopyran) compound is used.
Suited organic polyhalogen compounds sensitive to ultraviolet
radiation and capable of photolytically separating a
halogen-containing free radical and of forming a dye salt with the
spiropyran compound are within the scope of the following general
formula: ##SPC5##
wherein:
each of A, B, X and Y is a halogen atom of the group of chlorine,
bromine or iodine, or
wherein one of said symbols A, B, X or Y represents an alkyl group,
including a substituted alkyl group e.g. a halogen-substituted
alkyl group, a hydroxyalkyl group or an aralkyl group e.g. benzyl,
an aryl group, a substituted aryl group or an aroyl group, and the
other symbols chlorine, bromine or iodine, or wherein at least two
of said symbols A, B, X or Y represent an aromatic acyl group, e.g.
benzoyl, and the other symbols chlorine, bromine or iodine.
Suitable representatives falling within the scope of that general
formula are organic halides such as carbon tetrabromide, bromoform,
iodoform, hexachloroethane, hexabromoethane, pentabromoethane,
1,1,2,2-tetrabromoethane,
.alpha.,.alpha.,.alpha.-tribromoacetophenone and
tribromoethanol.
The colour-forming spiropyran compound(s) are preferably used in
admixture with a 1- to 20-fold amount by weight of photosensitive
organic polyhalogen compound such as carbon tetrabromide.
This ratio, however, is not limitative since useful results can be
obtained with the colour-forming compound and photosensitive
polyhalogen compound in a ratio by weight in the range of e.g. 1:1
to 1:50.
The recording material for forming a positive dye image according
to the present invention is characterized by the presence in the
recording layer of a compound containing N-vinylcarbazole
units.
Preferably a N-vinylcarbazole homopolymer or copolymer is used in
an amount large enough to serve as binder for the spiropyran
compound and the organic polyhalogen compound sensitive to
ultraviolet radiation.
Suitable N-vinylpolymers and copolymers can be prepared by
application of one of the various known polymerization procedures,
e.g., by pearl- or emulsion polymerization or by polymerization in
solution, whereby the initiation of the polymerization can occur by
free radicals, by ion formation, or by radiation, e.g., with
actinic light. It is to be noted that the polymerization degree is
not critical and can vary between wide limits. As far as the
copolymers are concerned it is further to be noted that the content
of N-vinylcarbazole units can vary between wide limits, say, e.g.
between 20 and 95 %. In general, the best results are attained with
copolymers having a content of vinylcarbazole units between 40 and
90 %.
The preparation of suitable poly-N-vinylcarbazoles is described,
e.g., in the German Pat. Specification Nos. 931,731 filed Mar. 4,
1953; 936,421 filed Feb. 20, 1953; 1,097,680 filed Oct. 15, 1959
all three by Badische Anilin- & Soda-Fabriken A.G., and
1,158,367 filed July 18, 1962 by Gevaert Photo-Production N.V. and
the U.S. Pat. No. 2,072,465 of W. Reppe, E. Keyssner and E. Dorrer,
issued Mar. 2, 1937.
The preparation of suitable N-vinylcarbazole copolymers is
described in the United Kingdom Pat. Specification No. 964,875
filed Apr. 21, 1960 by Gevaert Photo-Production N.V.
Halogen-substituted poly-N-vinylcarbazoles are described in the
published Japanese patent application Nos. 21,875/67 filed June 18,
1964; 25,230/67 filed Oct. 13, 1964; 7,592/68 filed Nov. 27, 1964;
19,751/67 filed June 18, 1964 and 7,591/68 filed Nov. 18, 1964 all
by Matsushita Electric Industrial Co. Ltd.
For illustrative purposes suitable vinyl copolymers containing
N-vinylcarbazole units are enumerated in the following Table 2.
Table 2 ______________________________________ Copolymer mole % of
N-vinyl carbazole ______________________________________ copolymer
of N-vinylcarbazole and vinylidene chloride 85.4 copolymer of
N-vinylcarbazole and 3,3',5-trimethyl isononyl 93her copolymer of
N-vinylcarbazole and vinyl acetate 88.6 copolymer of
N-vinylcarbazole and isopropenyl acetate 94.5 copolymer of
N-vinylcarbazole and vinylstearate 37.5 copolymer of
N-vinylcarbazole and methyl acrylate 67.6 copolymer of
N-vinylcarbazole and ethyl acrylate 41 graft copolymer of
N-vinylcarbazole and ethyl acrylate 90.3 emulsion polymer of
N-vinylcarbazole and polyethyl acrylate 94.5 copolymer of
N-vinylcarbazole and n-butyl acrylate 58.3 copolymer of
N-vinylcarbazole and 2-ethyl hexyl acrylate 51.6 copolymer of
N-vinylcarbazole and acryloxyethyldiethylamine 76.6 copolymer of
N-vinylcarbazole and vinylcinnamate 92.5 copolymer of
N-vinylcarbazole and methyl methacrylate 62.7 copolymer of
N-vinylcarbazole and isobutyl methacrylate 51.8 copolymer of
N-vinylcarbazole and lauryl methacrylate 77.4 copolymer of
N-vinylcarbazole and methylacryloxyethyldiethylamine 9.7 copolymer
of N-vinylcarbazole and acrylonitrile 88 graft copolymer of
N-vinylcarbazole and butylaldehyde acetal of polyvinyl alcohol 30
copolymer of N-vinylcarbazole and
di(2-dichloroethyl)-vinylphosphonate 82.4 copolymer of
N-vinylcarbazole and styrene 49 graft copolymer of N-vinylcarbazole
and polystyrene 27.3 copolymer of N-vinylcarbazole and
vinylnaphthalene 47.1 copolymer of N-vinylcarbazole and
anthracene-(9,10) 91.5 copolymer of N-vinylcarbazole and
2-vinylpyridine 31.8 copolymer of N-vinylcarbazole and
4-vinylpyridine 32.4 copolymer of N-vinylcarbazole and
N-vinylpyrrolidine 69.1 terpolymer of N-vinylcarbazole,
acrylonitrile and styrene 20 graft polymer of a terpolymer of vinyl
chloride, vinyl acetate, and vinyl alcohol with N-vinylcarbazole
29.4 graft polymer of a terpolymer of vinyl chloride, vinyl
acetate, and maleic anhydride with N-vinylcarbazole 55.1
______________________________________
The recording material of the present invention preferably contains
the photosensitive polyhalogen compound and spiropyran compound in
a layer whose binder is solely poly-N-vinylcarbazole. However,
minor amounts of other binding agents are not excluded and so
recording layers of the present invention may contain also
hydrophobic polymers and copolymers e.g. on the basis of styrene,
vinyl acetate, acrylonitrile, acrylic acid ester, methacrylic acid
ester or butadiene units, hydrophobic cellulose derivatives,
phenoxy resins or polycondensates of the polyester type, e.g.
polycarbonates.
The recording layers of the present invention can obtain an
improved sensitivity to ultraviolet radiation and/or visible light
by incorporating therein the sensitizing agents described in the
United Kingdom patent application No. 41,749/70 corresponding with
published Dutch patent application No. 71/12021.
Particular useful sensitizing agents are organic compounds
containing a carbonyl group linked through a conjugated system to a
dialkylamino group, e.g. Michler's ketone and
1-methyl-3-phenyl-7-dimethylamino-2(1H)-quinolone.
A particularly good sensitivity to visible light is obtained with
merocyanine dyes, the following dye being an example thereof:
##SPC6##
The recording materials of the present invention preferably contain
a fog-inhibiting compound such as triphenylstibine and/or analogous
compounds described for that purpose in the published Dutch patent
application No. 71/12021.
The fog-inhibiting compound is present in the recording layer
preferably in a weight ratio range of 1:1 to 1:10 with respect to
the spiropyran compound.
The amount of spiropyran compound in the recording layer amounts
preferably to at least 0.05 g per sq. m.
The recording composition of the present invention can be coated on
any kind of support on which colour images have to be produced.
Preferred supports are paper and resin sheets, e.g. those known in
silver halide photography. The thickness of the recording layer may
vary within relatively broad limits. Dry coatings have preferably a
thickness in the range of 3 to 20 microns.
In order to produce a positive colour image according to the
present invention the above described recording material in a first
step is image-wise exposed to ultraviolet radiation and/or to
visible light.
In the step following the formation of the latent or only faintly
coloured visible dye image the recording material is heated
preferably in the range of 120.degree. to 150.degree.C for a period
of time of 5 to 20 sec. This heating may proceed, e.g., with hot
rollers or in a drying stove with a hot air stream.
Thereupon an overall exposure with infrared radiation optionally
mixed with visible light produces a colouration in the areas of the
recording material that not had been exposed image-wise
previously.
During the overall infrared exposure overall heating may be
continued but preferably at a lower degree, e.g. at
100.degree.C.
The stabilization of the obtained positive prints may proceed by
washing out the residual photosensitive organic polyhalogen
compound e.g. carbon tetrabromide with a suitable solvent or
solvent mixture, e.g. a hydrocarbon liquid such as petroleum ether
optionally mixed with acetone, or by simply evaporating it by
raising the temperature if the compound involved is sufficiently
volatile.
According to a special embodiment the stabilization of the image
proceeds with increased speed by first overall heating the
recording layer at about 80.degree.C in the absence of visible
light for at least 5 sec. and then treating it with a chlorinated
solvent, e.g. perchloroethylene at room temperature (20.degree.C)
for at least 15 sec. in order to extract the photosensitive
polyhalogen compound.
Stabilization may proceed very fast by dipping the exposed
recording material in a heated organic liquid that has a relatively
high boiling point, preferably above 200.degree.C and that does not
affect the recording layer. The organic liquid is preferably heated
in the range of 145.degree. to 165.degree.C and the dipping time
is, e.g., 5 to 20 sec. Suitable liquids are mineral oil of
aliphatic or naphthenic nature, e.g. motor oil, and ISOPAR G (trade
name). A post-treatment with a solvent, e.g. a chlorinated
hydrocarbon solvent may be necessary to remove the residual oil
film.
The following examples further illustrate the present invention.
The percentages are by weight unless otherwise indicated.
EXAMPLE 1
A photosensitive material was prepared by coating the following
composition:
0.5 g of carbon tetrabromide
0.04 g of di-.beta.-naphthospiropyran
0.5 g of poly-N-vinylcarbazole
0.02 g of triphenylstibine
10 ml of methylene chloride,
at a wet coating thickness of 0.12 mm to a non-subbed polyethylene
terephthalate support.
The dried coating was image-wise contact-exposed through a line
original and a grey filter of spectral density 1.00. The exposure
lasting 8 sec. was effected in an ACTINA S (trade name) diazotype
copying apparatus operating with an ultraviolet lamp of 1000 W. A
faintly visible print-out image was obtained.
The exposed recording material was then overall heated for 30 sec.
at 150.degree.C.
Thereupon the heated material was overall exposed with infrared
radiation while being in contact with a metal plate at a
temperature of about 100.degree.C.
The faintly visible print-out image disappeared and an intense blue
colouration took place in the areas that had not been exposed
image-wise.
The obtained positive image was stabilized by dipping the recording
layer for 2 min. in perchloroethylene.
EXAMPLE 2
A photosensitive material was prepared by coating the following
composition:
0.120 g of carbon tetrabromide
0.120 g of iodoform
0.120 g of 3-methyl-di-.beta.-naphthospiropyran
0.020 g of triphenylstibine
0.500 g of poly-N-vinylcarbazole
10 ml of methylene chloride
at a wet coating thickness of 0.12 mm to a non-subbed polyethylene
terephthalate support.
The iamge-wise exposure and processing including stabilization were
carried out as described in Example 1 with the difference, however,
that the overall heating at 150.degree.C lasted from 15 to 45 sec
and the duration of the infrared exposure was from 5 sec. to 1
minute.
EXAMPLE 3
A photosensitive material was prepared and exposed image-wise as
described in Example 2. In the processing the overall heating
proceeded at 120.degree.C for a period of 30 to 75 sec. The other
steps of the processing and stabilization were the same as in
Example 1. A positive dye image of good quality was obtained.
EXAMPLE 4
A photosensitive material was prepared as described in Example
2.
The image-wise contact exposure proceeded with visible light by
means of an incandescent lamp of 300 W placed at a distance of 10
cm.
The overall heating proceeded for 15 sec. at 150.degree.C.
The other steps of the processing and stabilization were the same
as described in Example 1.
A positive dye image of good quality was obtained.
* * * * *