Note: Descriptions are shown in the official language in which they were submitted.
=l=
DIFF~SION TRANSFER~IMAGING SYSTEM
Field of the Invention
This invention relates to a method of forming
an image in which a sheet bearing a radiation-
sensitive image-forming layer is image-wise exposed to
record an image in said layer and thereafter the
image-forming components are transferred to a receptor
layer or sheet to form a permanent image. In
10 particular, the invention relates to a diffusion
transfer imaging process employing a
radiation-sensitive sheet comprising one or more
bleachable dyes.
Background of the Invention
Positive working non-silver systems in which
an originally coloured species is decolourised
(bleached) in an imagewise manner upon exposure to
light have received a considerable amount of
at~tention. A large variety of dyes and activators
20 have been disclosed for such systems, see, for
example, J. Kosar, Light Sensitive Systems, page 387,
Wiley, New York 1965.
The reaction relies on the fact that the dye
absorption is sensitising the dyels own destruction or
25 decolourisation, for example a yellow dyes absorbs
blue light; the excited dye thus formed reacts with an
activator which releases the species to bleach the
dye. similarly green light would destroy the magenta
and red light the cyan dyes.
This dye bleach-out process is thus capable of
produciny colour images in a simple way. However t in
spite of its apparent simplicity, the bleach-out
process poses a number of problems. In particular,
; the purity of the whites in the final image leaves
::
,
=2~
much to be desiredl image stability may not be good
and a fixing step may be required to stabilise the
image.
Our copending European Patent Application No.
5 84301156.0 (Serial No. a 120 601) discloses a
radiation-sensitive element capable of recording an
image upon image-wise exposure to radiation of
selected wavelength, the element cornprising, as the
image-forming components, an effective amount of a
10 bleachable dye in reactive association with an
iodonium ion.
The element is capable of recording a positive
image simply upon exposure to radiation of selectecl
wavelength; the radiation absorbed by the dye which is
15 in reactive association with an iodonium ion causes
the dye to bleach. The dyes are believed to sensitise
spectrally the reduction of the iodonium ion through
the radiation absorbed by the dyes associated with the
iodonium ion. Thereafter the element may be
20 stabilised to fix the image by destruction of the
iodonium ion or by separation of the dye relative to
the iodonium ion.
The dyes used may be of any colour and any
chemical class which is capable of bleaching upon
25 exposure to radiation of selected wavelength in the
presence of an iodonium ion.
By a suitable selection of dye an element may
be prepared which is sensitive to radiation of a
selected wavelength band within the general range 300
30to 110~ nm, the particular wavelength and the width of
- the band depending upon the absorption characteristics
of the dye. In generall where a dye has more than one
absorption peak it is the wavelength corresponding to
, :
-~LZ63~
the iongest wavelength peak at which one would choose
to irradiate the element.
Elements intended for the production of images
from radiation in the visible region (400 to 700 nm~
5 will contain dyes which will bleach from a coloured to
a substantially colourless or very pale state. In
practice, such bleachable dyes will undergo a change
such that the transmission optical density at the
~ max will drop from 1.0 or more to less than 0.09,
10 preferably less than 0.05. The dyes will generally be
coated on the support to provide an optical density of
about 3.0 or more.
In the case of elements sensitive to
ultraviolet radiation (300 to 400 nm) the dyes will
15 not normally be coloured to the eye and there may be
no visible chanye upon exposure to ultraviolet
radiation and bleaching. The image-wise exposed
elements may be used as masks for further ultraviolet
exposure after fixing.
Infrared sensitive elements contain dyes
having an absorption peak in the wavelength range 700
to 1100 nm. These dyes may also have absorption peaks
in the visible region before and/or after bleaching.
Thusl as well as providing a means for obtaining ~asks
25 for subsequent infrared exposure in a similar manner
to the ultraviolet masks, infrared sensitive elements
may record a visible image upon image-wise exposure to
infrared radiation.
Exposure may be achieved with a wide variety
30 of sources including incandescent, gas discharge and
laser sources. For laser scanning applications the
laser beam may need to be focussed in order to achieve
sufficient exposure.
, ~ .
The dyes used may be anionic, cationic or
neutral. Anionic dyes give very good photo-
sensitisation which is believed to be due l:o an
intimate reactive association bet~een the negatively
charged dye and the positively charged iodonium ion.
Also anionic dyes may readily be mordanted to cationic
polymer binders and it is relatively simple to remove
surplus iodonium ions in an aqueous bath in a fixing
step if the mordanting polymer is cationic. However,
10 neutral dyes also give good results and are preferred
over cationic dyes for overall photosensitivity.
Cationic dyes are least preferred since it is more
difficult to achieve intimate reactive association
between the positively charged dye and iodonium ion,
15 and selective removal of iodonium ion after imaging is
more difficult.
The bleachable dyes Jnay be generically
referred to as polymethine dyes which term
characterises dyes having at least one electron donor
20 and one electron acceptor group linked by methine
groups or aza analogues. The dyes have an oxidation
potential between 0 and +1 volt, preferably between
-~0.2 and +0.8 volt. The bleachable dyes may be
selected from a wide range of known classes of dyes
25 including allopolar cyanine dye bases, complex
cyanine, hemicyanine, merocyanine, azine, oxonol,
streptocyanine and styryl.
~he dye and iodonium system has its greatest
~; sensitivity at the ~max f the longest wavelength
3D absorbance peak. Generally, it is necessary to
irradiate the system with radiation of wavelength in
the vicinity of this ~ma~ for bleaching to occur.
~ Thus, a combination of coloured dyes may be used, e.g.
:
,, .
yellow, magenta and cyan, in the same or different
layers in an element and these can be selectively
bleached by appropriate visible radiation to form a
full colour imageO Monochromatic or polychromatic
images may be produced using the photosensitive
materials with relatively short exposure times in
daylight or sunlight or even artificial sources of
light ~e.g fluorescent lamps or laser beams). The
exposure time, for adequate results, for example when
10 using an 0.5 kW tungsten lamp at a distance of 0.7 m,
may be between 1 second to 10 minutes.
The iodonium salts used in the imaging system
are compounds consisting of a cation wherein a
positively charged iodine atom bears two covalently
15 bonded carbon atoms, and any anion. Preferably the
acid from which the anion is derlvad has a pKa < 5.
The preferred compounds are diarylr arylJheteroaryl or
diheteroaryl iodonium salts in which the carbon-to-
iodine bonds are from aryl or heteroaryl groups.
20 Aliphatic iodonium salts are not normally thermally
stable at temperatures above 0C. However, stabilised
alkyl phenyl iodvnium salts such as those disclosed in
Chem. Lett. 1982, 65-6 are stable at ambient
temperatures and may be used.
The bleachable dye and iodonium salt are in
reactive association on the support. Reactive
association is defined as such physical proximity
be~tween the compounds as to enable a chemical reaction
to take place between them upon exposure to light. In
30 practice, the dye and iodonium salt are in the same
layer or in adjacent layers on the support.
In general, the weight ratio of bleachable dye
~; ~ to iodonium salt in the element is in the range from
1 to 1:50, preferably in the range ~rom 1:2 to 1:10.
,,:
=6--
The bleachable dye and iodonium salt may be
applied to the support in a binder. Suitable binders
are transparent or translucent~ are generally
colourless and include natural polymers, synthetic
resins/ polymers and copolymers, and other film
forming media. The binders may range from
thermoplastic to highly cross-linked, and may be
coated from aqueous or organic solvents or emulsions.
Suitable supports include transparent film,
10 e.g. polyester, paper e.g. baryta-coated photographic
paper, and metallised film. Opaque vesicular
polyester films are also useful.
The fixiny of the radlation-sensitive elements
may be effected by de~tructlon o~ the iodonium ion by
15 disrupting at least one of the carbon-to-iodine boncls
since the resulting monoaryl iodine compound will not
react with the dyeO The conversion of the iodonium
salt to-its non-radiation sensitive form can be
e$fected in a variety of fashions. Introduction of
20 ammonia and amines in reactive association with the
iodonium ion, or a reaction caused on heating, or UV
irradiation of a nucleophilic anion such as I~, Br0,
Cl~, BAr4~ ~etra-arylboronide), Ar ~ ~e.g.
phenoxide), or 4-NO2C6H4CO2~, with the iodonium ion,
25 will ef~ect the conversion.
An alternative method of achieving
post-imaging stabilisation or fixing is to remove the
iodonium ion from reactive association with the dye by
washing with an appropriate solvent. For example, in
30 the case of elements using mordanted oxonol dyes and
~ water soluble iodonium salts formulated in gelatin,
;~ after imaging, the iodonium salt is simply removed by
~ an a~ueous wash, which leaves the immobilised dye in
. ~
-7=
the binder. The dye stability to light is then
equivalent to that of the dye alone. An element in
which the dye and iodonium salt is formulated in
polyvinylpyridine may be treated with aliphatic
ketones to remove the iodonium salt and le~ve the dye
in the binder.
The elements may be used as transparencies for
use with overhead projectors, for making enlarged or
duplicate copies of colour slides and for related
lD graphics or printing applications, such as pre-press
colour proofing materials.
Dye diffusion transfer systems are known and
are becoming increasingly important in colour
photography (see C.C. Van de Sande in Angew Chem.
15 1983, 22, 191-209). These systems allow ~rapid
access~ colour images without a complicated processing
sequence. The construction of these colour materials
may be donor-receptor type te.g. Ektaflex commercially
available from Kodak) integral peel-apart type (e.g.
20 Polaroid, E.H. Land, H.G. Rogers, V.K. Walworth in J.
Sturge Nebelette's Handbook of Photography and
Reprography, 7th Ed. 1977, Chapter 12), or integral
single sheet type (e.g. Photog. Sci. and Eng., 1976,
20~ 155). Silver halide diffusion transfer systems
2S are also known (e.g. E.H. Land. PhotogO Sci. and Eng.,
1977~, 21, 225). Examples of ~iffusion transfer fixing
in non-silver, dye-forming reactions employing solvent
application to effect the transfer are disclosed in
United States Patent Specification Nos. 3 460 313 and
30 3 598 583. The latter patent also describes a
full-colour imaging element, applicable for
preparation of colour proofs, fixed by transfer of dye
precursors in register to a receptor. Other examples
'rr~le ~ K
(
,, ;
,, .
,,~,
. ;,
=8=
of non-silver diffusion transfer imaging systems are
disclosed in British Patent Specification Nos.
1 057 703, 1 355 618 and 1 371 898.
It has now been found that certain dyes which
are bleachable upon exposure to radiation in the
presence of iodonium ion are susceptible to diffusion
transfer and this property may be utilised to separate
such dyes from the iodonium ion and produce a clean,
stable image by transfer from a radiation-sensitive
10 layer to a receptor layer or separate receptor element.
Brief Summary of the Invention
According to the present invention there is
1~ provided a process for forrning an image which
comprises imaye-wise exposing to radiation of selected
wavelength a carrier element comprising, as image
forming components, in one or more imaging layers
coated on a support a bleachable dye in reactive
20 association with iodonium ion thereby bleaching the
dye in exposed areas to orm a positive image, and
thereafter transferring the positive dye image to a
receptor which is either a receptor layer present on
the carrier or a separate receptor element by
25 providing a liquid medium between the positive dye
image and receptor for a sufficient time to allow
transfer oE the dye image to the receptor.
The process of the invention provides stable
dye images, optio~ally full colour images, of high
30 quality with low background fog. The imaging system
does not require the presence of silver halide.
.,.
=9 -
Descri tion of the Preferred Embodiments
P_ _ . _ __
In accordance with the invention the
bleachable dye is soluble in a diffusion transfer
S liquid and after imaye-wise exposure the positive dye
image is transferred to a separate receptor or a
receptor layer of the element by providing a transfer
liquid between the dye image and receptor thereby
causing diffusion transfer of the image to the
10 receptor~ This semi-dry process allows production of
images withih a few minu.tes and the background fog
levels are substantially reduced giving much cleaner
images. Typically, fog levels are reduced from 0.15
to less than 0.05. This technique may be used to form
15 full colour images of high quality suitable for use in
pre-press colour proofing.
The diEfusion transfer process utilises dyes
which are soluble in a liquid, preferably an aqueous
solvent. It is preferred that the bleached products
zo Of the dye and iodonium ion are non-diffusing. This
may normally be achieved by utilising iodonium
compounds having a ballasting group. The dye-bleach
system comprises a bleachable dye in reactive
association with an iodonium ion is disclosed in our
25 copending European Patent Application No. 84301156.0
(Serial No. 0 120 601).
The process may be used to achieve a
: multi-colour print either by sequentially transferring
~: dyes from separate carrier elements or by utilising a
30 carrier element having two or:more coloured dyes, e.g.
magenta, cyan and yellow, and transferring the dyes
simultaneously.
~::
~ . ,
=10=
Suitable bleachable dyes may be generically
referred to as polymethine dyes which term
characterises dyes having at least one electron donor
and one electron acceptor yroup linked by methine
groups or aza analogues. The dyes have an oxidation
potential between 0 and ~l volt, preferably between
+0.2 and ~0.3 volt. The bleachable dyes may be
selected from a wide range of known classes of dyes
including allopolar cyanine dye bases, complex
10 cyanine, hemicyanine, merocyanine, azine, oxonol,
streptocyanine and styryl.
The dyes useful in the invention are all
bleachable dyes; dyes which bleach on exposure when in
the presence of an iodonium ion. While any
15 polymethine dye may be transferred by difusion
transfer providing it has a suitable solubility in the
diffusion transfer solvent, e.g. more than 10 g/litre
in 60% aqueous ethanol, it has been found that
cationic and anionic dyes are preferable over neutral
20 dyes because of the possibility of mordanting the dye
to a polyanionic or polycationic organic polymer on
the surface of the receptor sheet.
In general, suitable dyes for use in the
invention will have the structure:
R2
R
in which:
n is 0, 1 or ~, and
:
3~
=1~. =
Rl to R4 are selected to provide an electron
donor moiety at one end of the conjugated chain and an
electron acceptor moiety at the other r and may be
selected from substituents including hydrogen,
halogen, cyano, carboxy, alkoxy, hydroxy, nitro,
alkyl, aryl groups or heterocyclic rings any of which
may be substituted. The skeletal structure of the
groups Rl to R4 generally contain up to 14 atoms
selected from C, N, O and S. When the skeletal
10 structure of a Rl to R4 group is in the form of a
linear chain there will usually be no more than 6
carbon atoms in the chain. When the skeletal
structure is cyclic there will be no more than 7 atoms
in any single ring. Cyclic structures may comprise
15 two or more fused rin~s containing up to 14 atoms. If
the skeletal structure of a Rl to R4 group comprises
two unfused cyclic groups there will be no more than 3
atoms in the linear chain between the groups.
Alternatively, Rl and R2 andjor R3 and R4 may
20 represent the necessary atoms to complete optionally
substituted aryl groups or hetreocyclic rings,
generally containing up to 14 atoms selected from C,
N, O and S and having a structure as defined above.
The conjugated chain is preferably composed of
25 carbon atoms but may include one or more nitrogen
atoms providing the conjugation is not disrupted. The
free valences on the chain may be satisfied by
hydrogen or any substituent of the type used in the
cyanine dye art including fused riny systems.
The particular selection of substituents Rl to
R4 effects the light absorbance properties of the dye
which may be varied to provide absorption peaks
ranging from the ultraviolet (300 to 400 nm), near
~ ,
,
'
63~
visible (400 to 500 nm), far visible (500 to 700 nm)
and infrared (700 to 1100 nm).
~ yes of the above formula are well known
particularly in the silver halide photographic art and
are the subject of numerous patents. Exemplary dye
structures are disclosed in ~he Theorgy of the
Photographic Process, T.H. James, Ed. MacMillan,
Editions 3 and 4, and Encyclopaedia o Chemical
Technology, Kirk Othmer, 35d Edition, Vol. 18, 1983.
Within the above general structure of dyes are
various classes of dye including:
1) Cyanine dyes of the general formula:
RS
in which:
p is an integer of 0 to 2~
R5 and R6 are independently hydrogen or
substituents which may be present in conventional
cyanine dyes~ e.g. alkyl (preferably of 1 to 4 ca~rbon
atoms), etc.,
~5 X~ represents an anion, and
the groups A and B, which need not necessarily
complete a cyclic structure with the methine chain,
independently represent alkylr aryl or heterocyclic
groups or the necessary atvms to complete heterocyclic
30 rings which may be the same or different. The
skeletal structure of the groups A and ~ generally
contain up to 14 atoms selected from C, N, O and S.
When the skeletal structure of A or B is in the form
of a linear chain there will usually be no more than 6
. ,
-13=
carbon atoms in the chain. When the slceletal
structure completed by A or B is cyclic there will be
no more than 7 atoms in any single rins~ Cyclic
structures may comprise two or more fu,sed rings
5 containing up to 14 atoms. If the skeletal structure
complete by A or B comprises two unfused cyclic groups
there will be no m~re than 3 atoms in the linear chain
between the groups.
This class of dyes is very well known
10 particularly in the silver halide photographic art and
are the subject of numerous patents. General
references to these dyes include The Chemistry of
Synthetic~es, K. Venkataraman ed., Academic Press,
Vol. 4 (1971) and The Theor ~ lc
15 Processl T.H. James, ed., MacMillian, Editions 3 and 4.
2) Merocyanine dyes of the general formula:
,~0
in which:
q is an integer of 0 to 2,
R5 and A are as defined above, and
B is as defined above or may complete a
carbocyclic ring.
These dyes are also well known in the silver
halide photographic art and are described in The
Theory of the Photo ~aphic_ rocess, referred to above.
3) Oxonols of the general formula:
.
`: '
=14=
~A~ ,B~
y~ o~
in which:
q is an integer of 0 to 2,
A and B may be the same or different and are
as defined above in relation to cyanine and0 merocyanine dyes, and
represents a cation.
Oxonol dyes are similarly well known in the
silver halide photographic art and are disclosed in
the above mentioned reference, ~ the
15 Pbotographic Process, J. Fabian and H. Hartman, Light
Absorption of Organic Colourants, Springer ~erlag 1930
and United States Patent Specifisation No. 2 611 696.
Anionic bleachable dyes, of which oxonol dyes
are a class, are particularly useful because of their
20 ability to associate closely with the iodonium
cations. Anionic dyes in general will possess a
delocalised negative charge.
Anionic dyes may be regarded as being prepared
from a central portion containing delocalisable
25 electronic system and end units which allow
stabilisation of the negative charge.
The central portion may generally be selected
from molecules possessing two active aldehyde or
aldehyde derived groups such as glutaconic aldehyde
~0and its anil salts, 3-methyl glutaconic dialdehyde and
its anil saltsj and 3-anilinoacrolein and its anil
salts. Thes~ central portions may react with end ur.it
compounds contaihing active methylene groups Such as
=15=
malononitrile, NC.CH2 COOR', where Rl is an allcyl
group containing from 1 to 6 carbon atoms, e~g.
methyl, ethyl, propyl, butyl and hexyl groups,
RISO2CH2CN and R'SO2CH2COR' in which R' is as defined
above,
10 in which R~ is H or OH,
~ N~ N- Rl'i R"l - N ~ N - R"'
O ~ and ~ S
in which each Rn' independently represent H or an
alkyl group containing 1 to 6 carbon atoms.
The anionic dyes may have either the same end
20 units or two different units.
It is to be understood that these cyaniner
merocyanine, anionic and oxonol dyes may bear
substi~uents along the polymethine chain composed o
C, N, O and S, and that these substituents Jnay
25 themselves join to form 5, 6 or 7 membered rings, or
may bond with rings A and B to form further ringsl
possibly with aromatic character. Rings A and B may
also be substituted by C, N, H, O and S containing
groups such as alkyl, substituted alkyl, alkoxy, amine
(primary, secondary and tertiary), aryl (e.g. phenyl
and substi~uted phenyl), halo, carboxyl, cyano, nitro,
etc. Exemplary substituents are well known in the
cyanine dye art.
-16=
Other known classes of dyes useful in the
diffusion transfer process which possess an activated
methylene chain include bisquinones,
bisnaphthoquinones, hemicyanine, streptocyanine, anthraquinone, indamine, indoaniline and indophenol.
Preferred dyes for use in the invention are
anionic, more preferably oxonol dyes because
a) they give good sensitisation, believed to
be due to an intimate reactive association
between the negatively charged dye and the
positively charged iodonium ion,
b) they are highly water/alcohol soluble,
thus being readily separable from the iodonium
ion,
c) readily mordanted to cationic polymer
binders conventionally present in receptor
layers (e.g. RD 173033-A39 G.A. Campbell) and
d) readily prepared affording a range of dyes
with absorption in the region 350 to 700 nm.
20 Oxonol dyes which diffuse readily out of gelatin
layers are known, e.g. Japanese Patent Specification
No. 49099620, ~uji. The dyes have an oxidation
potential between 0 and +l volt, preferably between
+0.2 and +0.8 V.
Examples of oxonol dyes include:
Yellow Dye 1
~ C(:)2Et
C~ ~
C OEt
460 nm (EtOH)
.
=17_
Magenta Dye l
S ~ ~ NHEt3
~
560 nm ~EtOH)
Cyan Dye 1 O
15 ~ ~ , Me NHEt3
O N ~ O
Me
The cation of the oxonol dye need not be the
20 iodonium ion ~nd can be any cation including Li~, Na~
and K~ or quaternary ammonium cations, e.g. pyridinium
or as represented by the formula:
.
RlU
Rll _ Rl3
R1 2
; in which Rl0 to Rl3 may be selected from a wide range
of groups including hydrogen, alkyl, preferably of l
30to 4 carbon atoms, aryl, e.g. phenyl, aralkyl o~ up to
12 carbon atoms. Preferably at least one of R10 to
Rl3 is hydrogen and the rest are alkyl or aralkyl
si~ce such amines are readily available and allow easy
~ synthesis of the dyes.
: ::
~:~63~
=18=
The iodonium ions used in the invention are
compounds consisting of a cation wherein a positively
charged iodine atom bears two covalently bonded carbon
atoms, and any anion. The preferred compounds are
diaryl, aryl/heteroaryl or diheteroaryl iodonium salts
in which the carbon-iodine bonds are from aryl or
heteroaryl groups and one of the aryl or heteroaryl
groups is substituted with an alkyloxy group.
Suitable iodonium salts may be represented by the
lO formula:
Ar
I~ A~
Ar2'~
15 in which:
Arl and Ar2 independently represent
carbocyclic or heterocyclic aromatic-type groups
generally having from 4 to 20 carbon atoms, or
together with the iodine atom complete a heterocyclic
20 aromatic ring.
; These groups include substituted and unsubstituted
aromatic hydrocarbon rings, e.g. phenyl or naphthyl,
which may be substituted with alkyl groups, e.g.
methyl, alkoxy groups, e~g. methoxy, chlorine,
25 bromine, iodine, fluorine~ carboxy~ cyano or nitro
groups or any combination thereof. Examples of
hetero-aromatic groups include thienyl, furanyl and
pyrazolyl which may be substituted with similar
substituents as described above. Condensed
30 aromatic/hetero-aromatic groups, e.g. 3-indolinyl, may
also be present,
; A~ represents an anion which may be
incorporated lnto Arl or Ar2.
,,
.. .
Preferably Arl and Ar2 do not have more than
two substituents at the alpha-positions of the aryl
groups. Most preferably Arl and Ar2 are both phenyl
groups.
Preferred iodonium salts for use in the
difusion transfer process incorporate a ballasting
group to prevent transfer of the iodonium ion during
the dye diffusion transfer step. Suitable ballasting
groups may be presant on Arl and/or Ar2, preferably i.n
10 the para-position with respect to the I0 link, and are
of the formula:
-oRl4
in which R14 represents a straight chain or
branched alkyl or alkyl substituted with OH, oR15,
(NR163)~ in which R15 and ~16 reprasent alkyl groups
or a group having a quaternary group at the end of an
alkyl chain, e.g. cH2-cH2-cH2~$he3x~. R14 should
20 preferably have at least 3 carbon atoms and generally
not more than 20 carbon atoms.
The presence of the oR14 ensures transference
of Ar2-OR14 to the bleached dye, thus resulting in
immobilisation of the bleach product and low Dmin
25 values.
The alpha-positions of the Arl and Ar2 yroups
may be linked together to include the iodine atom
within a ring structure, e.g.
~; 3~ ~ ~ Z ~
in which Z is an oxygen or sulphur atom. An example
of such an iodonium salt is:
= 2(~=
N02 I~ N2
PF6~
Other suitable iodonium salts include polymers
containing the unit:
1 () / - CH- CH 2 -
I
\A~ Ph /
in which Ph represents phenyl.
Examples of such polymers are disclosed in Yamada and
Okowara, Makromol. Chemie, 1972, 152, 61-6.
Any anion may be used as the counter~ion A~
20 provided that the anion does not react with the
iodonium cation under ambient temperatures. Suitable
inorganic anions include halide anions, HS04~, and
halogen-containing complex anions, e.g.
tetrafluoroborate, hexafluorophosphate,
2shexafluoroarsenate and hexa1uoroantimonate. Suitable
organic anions include those of the formulae:
R17Cod~ or Rl7So3~
in which R17 is an alkyl or aryl group of up to 20
carbon atoms, e.g. a phenyl group, either of which may
be substituted. ~xamples of such anions include
CH3CO ~ and CF3CO ~.
.. ,
.
=21=
A~ may be present in Arl or Ar2, e.g.
in which A~ represents CO ~r etc.
Furthermore, A~ may be present in a molecule
containing two or more anions, e.g. dicarboxylates
10 containing more than 4 carbon atoms.
The most significant contribution of the anion
is its effect upon the solubility of the iodonium salt
in different solvents or binders
Most of the iodonium salts are known, they may
15 be readily prepared and solne are commercially
available. The synthesis of sultable iodonium salts
is disclosed in F.M. Beringer et al, Journal of the
American Chemical Society, 80, 4279 (1958).
Suitable substrates for the donor (or carrier)
20 for use in both diffusion and sublimation transfer are
plastics film, paper (cellulosic or synthetic fibre),
metallised plastics film and plastic film to film or
plastic film to paper laminates.
The substrate should be unaffected by the
25 processing conditions. For example, the substrate
must possess adequate wet-strength and dimensional
stability for use in diffusion transfer. A preferred
substrate is a plastics film such as polycarbonate
film, cellulose acetate film or most preferably
`:
: : :
:,...................... :
=22=
polyester, e.g. poly(ethyleneterephthcllate~, which may
be biaxially orientated.
The substrates may possess surface modifying
or other coatings to enhance adhesion of imaginy
layers~ to irnprove smoothness, etc. ~esin coated
photographic grade paper is a suitable substrate. The
plastics film may specifically possess a subbing layer
which acts as a priming layer for gelatin and other
hydrophilic coating.
Elements for use in the diffusion tran~fer
process may comprise mixtures of dyes and iodonium
salts dissolved in gelatin or oil-dispersed in
gelatin, which, after image formation by visible light
irradiation, are fixed by dye diffusion transfer to a
15 gelatin and mordant-coated receptor sheet, which may
contain dye stabilisers. The iodonium salt and dye
are coated with a polymeric binder layer on a
substrate.
The quantity of the dye relative to the
20 iodonium salt is within the range of 1 to 50 weight
percent. The quantity of iodonium salt plus dye in
the coated layer falls within the range of 5 to 60%,
assuming the remainder to be binder.
The polymeric binders are generally water-
25 swellable of natural or synthetic origin, such asgelatin, gum arabic, poly~vinyl alcohol), poly(vinyl
pyrrolidone). The polymers may contain cross-linking
or other insolubilisation additives or may themselves
be self-crosslinked to reduce solubility in the
30 diffusion transfer processing solution while still
maintaining difusibility of the dye or dyes.
Preferred in the invention is gelatin which i9
crosslinked via its lysine groups with carbonyl
::
=~3=
compounds (e.g. glyoxal, glutaraldehyde). The binder
must allow the diffusion transfer solvent to enter the
imaged layer and thus allow diffusion of the
unbleached dye or dyes to the receptor sheet. If more
than one dye is to be transferred a general
equivalence of diffusion ratios is desirable.
~ preferred dye, iodonium, polymer system for
use in a diffusion transfer element is oxonol,
diaryliodonium trifluoroacetate and gelatin, since the
lO sensitive components are very soluble in gelatin.
The radiation-sensitive element may have
single layer, multi-dye formulation or multi-layer,
single dye per layer composites. Preferred elements
should have less than lO micron dye layer thickness to
15 allow rapid dye diffusion. Thicker coatings result in
long diffusion transfer times (e~g. 30 micron, 5
minutes for a transferred density of 2.5 reflected~.
The receptor material is generally a sheet
material to which the dyes are transferred during the
20 diffusion process. Although the dyes may be
transerred to untreated plastics film, paper (of
cellulosic or synthetic fibre) or other receptive
substrate material, it is normal for these to have
surface modifying treatments.
The receptor substrate is generally selected
from plastics film; paper (as above), metallised
plastics film, and plastics film-to-film or
film-to-paper laminates. These may be treated with
surface modifying coatings to alter opacity,
re1ectivity, smoothness, adhesion of subsequent
coatings, tint and dye absorptivity. Preferably the
substrate is a pIastics ilm such as biaxially
~6~
=2~=
oriented poly(ethylene terephthalate). Vesicular
substrates, e.g. vesicular polyester, may be
employed. The substrate preferably bears on an outer
surface a polymeric coating which is swellable under
the diffusion transfer conditions, e.g. gelatin
cross-linked with metal ions such as Cr~+ or Ni~.
Additionally, it is highly desirable for a
mordanting agent to be present in the receptor layer
to prevent further diffusion of the dye thus serving
10 to maintain resolution. The mordanting agent is
normally electrically charged polymer, bearing
opposite charge to the dye being transferred. Thus, a
polyanionic polymer would be used for positively
charged cyanine dyes. Cationic mordants are most
15 preferred as they will render substantive oxonol dyes
and will not mordant unreacted iodonium ion The use
of anionic, e.g. oxonol dyes, is therefore highly
advantageous for the above reasons and additionally
because of the enhanced reactivity which these dyes
20 exhibit on exposure with iodon-ium ions. Charged
metallic ions such as Cr3~ and Ni2~ may also be
employed to effect mordanting, as may conventional
mordanting agents. Examples of cationic mordanting
polymers are:
~CH- CE~æ~q
CH 2 ~
N R10 X
~9
in which:
q is an integer, and
R9 and R10 are as defined above.
:,.
=25=
Integral constructions incorporating both the
imageable layer and the receptor layer in a single
construction for diffusion transfer offer certain
advantages in processing ease, in tha~ there is no
separate receptor construction. Integral
constructions consist essentially of a transparent
substrate bearing an imageable layer containing one or
more bleachable dyes in reactive association with an
iodonium ion and a receptor layer.
The substrate material is a transparent
plastics film which is stable to diffusion transfer
processing. A preEerred substrate is biaxially
orientated poly(ethylene terephthalate) film. This
may bear transparent priming or subbing layers.
The components of the imageable layer have
been previously described. The bleachable dyes may be
present in one or more layers.
The receptor layer normally contains a
mordanting aid for the dye such as a poly~4-vinyl
20 pyridinium) polymer. Cationic polymers are preferred
as they will not mordant any diffusing iodonium ion
which may be subsequently washed out. Relative to the
viewing surface of the final image, it may be
necessary to include a backing layer containing a
25 white or coloured pigment in order to provide a
suitable reflective background. This reflective layer
preferabiy contains a white pigment, most preferably
baryta or titanium dioxide. The reflective layer must
allow diffusion of the bleachable dyes and thus
30 diffusion transfer processing solution permeable
binders are required. Preferably, water swellable
binders such as gelatin will be used for aqueous
processing solutions. The reflective layer may
~i3~
-26=
exhibit mordanting properties or may contain a
mordanting agent, although preferably the mordanting
agent is in a separate layer.
Antihalation layers situated between the
imageable layer and the reflective layer may also be
incorporated. Again this antihalation layer must
allow diffusion of the dyes. Carbon black dispersed
in gelatin is a suitable composition for use with
reflective coatings. An example of an integral
construction for use in making a final image which is
to be viewed by reflection is:
(a) a transparent substrate, e.g~ biaxially
orientated polyester Eilm bearing a subbing layer,
(b) a mordanting layer, e.g. poly~4-vinyl pyridinium)
polymer,
(c) a reflective layer, e.g. titanium dioxide in
gelatin,
(d) an antihalation layer, e.g. carbon black in
gelatin,
~e) one or more imageable layers (donor layers),
(f) optional transparent protective coating of a
diffusion transfer liquid permeable binder, e g.
gelatin coated at 0.5 micron wet thickness.
In use the imageable donor layer is exposed in
the normal manner. Thereafter the exposed composite
is contacted with the diffusion transfer liquid for a
sufficient time to allow penetration of the diffusion
transfer liquid thruugh the outer layers to ~he
receiving layers. Unreacted dye diffuses from the
donor layer through the antihalation layer, through
the reflective layer and is rendered substantive in
the mordanting coating. The final image may be viewed
through the transparent substrate and will naturally
possess a white background.
-27=
An alternative preferred construction employs
layers (b) to (e) in reverse order. After exposure
through the transparent base, the difEusion transfer
liquid is applied and this allows the dye(s3 to
migrate back towards the mordanting layer.
Evaporation of the diffusion transfer liquid may aid
this process. The ~inal image is viewed on a white
background. A further construction is as above but
omitting layers (c) and (d). Layers (b) and (e) may
10 be in that position or reversed.
After exposure and diffusion transfer
processing a final image suitable for projection
viewing i~ obtained.
With the integral construction the diffusion
15 transfer solvent may be applied by wiping, spraying,
soaking, or by rollers~ etc., optionally within a
processing bath. Transfer of the dyes is effected
rapidly, typically 30 to 60 seconds.
While diffusion transfer is normally effected
20 at ambient temperature, elevated temperatures, e.g.
30C, may also be employed.
In order to control the rates of diffusion of
the dyes, which may have importance when full colour
images are being formed, diffusion controlling layers
25 may be included between the mordanting layer and the
imaging layer and occasionally between individual dye
layers.
An optional washing stage may be undertaken
with the transferred image to remove residual iodonium
30 ions. Water washing for a short period, eOg. one
minute, may be beneficial although in normal practice
this will not be necessary.
:
-2~=
~ n order to achieve diffusion transfer the
exposed donor sheet is rendered in close contact with
the receptor layer, with the dye donor and dye
receptor layers contacting. Transfer is achieved
through the presence of the diffusion transfer liquid
between the donor and receptor layers. It is
essential that contact be maintained evenly and for a
sufficient time to allow transfer to occur.
The diffusion transfer liquid may be applied
10 in a variety of manners, such as
(a) passing the donor and receptor sheet in
face-to-face disposition through an automatic
processing bath containing diffusion transfer fluid,
excess fluid being expelled when the sheets emerge
through the exit rollers,
(b) releasing the diffusion transfer liquid rom a
pod and arranging this liquid to wet the donor and
receptor layers, an~
~c) wiping or spraying or otherwise wetting either
the donor or the receptor with diffusion transfer
uid and then quickly bringing the other in face to
face contact, thereafter removing excess while keeping
the faces in intimate contact.
In all the above instances the donor and
receptor are kept in face-to-face contact for
sufficient time f;or transfer to occur; thereafter the
sheets are separated to reveal the high quality
transferred image.
The process solution is normally colourless
and may contain water and invisible solvents which
evaporate shortly after the layers are separated.
=29-
The process solution preferably consists of
aqueous alcohol (30 to 80~), with low molecular weight
alcohols being preferred, leading to readily dried
mateeialsO The process solution may be buffered ln
the region p~ 5 to 8, and contain antioxidants such as
ascorbic acid/sodium ascorbate to destroy any
mobilised iodonium salt, or other additives.
In certain instances small quantities of
iodonium salts may also migrate in which case it is
10 desirable to wash the receptor layer with solvent such
as water, to remove the iodonium salts. Generally, it
has been found that the dye is the major transferring
species.
Alternatively to soluhilising the dye in the
15 binder it may be desirable to add an oil, water-
immiscible, phase to the binder and allow the dye and
iodonium salt to react primarily within a finely
dispersed oil droplet. After exposure such a layer is
processed with the dif~usion transfer solvent which
2a allows the unreacted dye to migrate towards the
receptor layer.
The invention will now be illustrated by the
following Examples.
In the following Examples the sensitivity of
25 the element was measured by the following technique.
A 2.5 cm square piece of each sample was exposed over
an area of 2.5 mm2 with focussed light filtered, using
a Kodak narrow band ilter (551.4 nm:power output =
2.36 x 10-3 W/cm2) and the change in the trans~issiQn
30 optical density with time was monitored using a Joyce
Loebl Ltd. microdensitometer. A plot of transmission
optical density versus time was made and the exposure
time ~t) for the optical density to fall from DmaX -to
.
=30=
(DmaX-l) was determined. The energy required (E) was
calculated as the exposure time (t) x power output
(= 2.36 x 10-3 W/cm2): this gives an indication of
the sensitivity of the elements.
In all cases a significant recluction of
backyround density was achieved after transfer which
gave a much cleaner image. Typically the minimum
density beEore transfer and after exposure was
approximately 0.15, this reducing to approximately
10 0.05 or below after transfer.
:
~::
SL~ Dye Diffusion to Rece~
Cyan Dye 2 ll ~max 670 nm
~ ~ NHEt3
o
A solution of the Cyan Dye 2 (0.03 g) in
ethanol (8 ml) and water (2 ml) was added in yellow
light to gelatin (3.6 9) in water (30 ml) containing
~5 Tergitol TMN-10 (Union Carbide, 10% aqueous, 1.5 ml)
at 45C. Aqueous glyoxal (10%, 0.5 ml) and
4-methoxyphenyl phenyliodonium trifluoroacetate
(2.0 g) dissolved in dimethylformamide ~2.5 ml) were
then added in the dark.
2~ The mixture was loop-coated at approximately
20 micron dry thickness onto chilled, subbed polyester
(4 mil) and dried at 25C i.n an air-circulated
cupboard for one hour.
The density of the resulting film was 5.0 at
25 665 nm ~transmitted). The density and time response
of the film on irradiation at 670 nm with a light
~ : output of 2.5 mW/cm2 was measured on a
: microdensitometer, giviny a sensitivity o~ 4 x 105
mJ/m2 for speed point of Dmax-l~
~: ~ 30 A strip was contacted with an UGRA scale (the
UGRA scale was an 1976 UGRA-Gretag-Plate Control Wedge
PCW) in a vacuum frame, emulsion to emulsion, and an
exposure given of 60 s at 0.7 m from a 4 kW metal
~: halide source (Philips HMP 17). The dyes rom the
;~ :
~ Jr~de 1~ rK
, .,
,
-32=
resulting image were transferred to a vesicular
polyester receptor substra~e (75 micron). The
substrate was coated with a gelatin receptor layer as
follows.
A gelatin solution (3.6 g in 30 ml distilled
water) at 40C, containing poly(4-vinylpyridinium)
methosulphate ~0.04 g in 6 ml ethanol and 0.5 ml
acetic acid3, chrome alum (0.05 g), and nickel
chloride (0.05 g~ was loop-coated onto chilled subbed
10 polyester (4 mil) and dried at 25C in an air
cixculated cupboard for one hour. The dried gelatin
layer was ahout 30 micron thick, deposited at
0.4 g/dm2. Ideally a less than 10 micron thick dry
gelatin layer is preferred to achieve the benefit of
15 better resolution.
The diffusion transfer was effected as follows:
1. The receptor was coated with the diffusion
transfer process solution with X-Bar No. 6
(commercially available from R.K. Chemicals Ltd).
on a coating bed. The process solution was made
up o water (40 ml), ethanol (20 ml), sodium
acetate (1.0 y), glacial acetic acid (2.0 ml).
2. The imaged donor was placed on top of the receptor,
emulsion to emulsionr and the composite pressed
together by the K-Bar to ensure that air bubbles
were removed.
fter 5 minutes contact the donor and receptor
sheet were peeled apart, and the receptor given a 30
second water-wash to remove any small amoun~ of the
iodonium salt which also transferred.
The properties of the donor and receptor
, images are reported below.
; ~ The ra~nge of halftone dots retained on using a
120 lines per centimetre screen is also reported
together with the resolution achieved.
le m~
. I :
~,
j:
=33=
Donor Receptor
Resolution 30U lines/mm 83 lines/mm
Dot retention
range 4 to 96% 4 to 96%
Dmax 5.0 (Transmitted) 2.6 tReflected)
Dmin 0.25/400 nm 0.09/400 nm
: (Transmitted) (Reflected)
10 Contrast -3.0 -4.0
_
There are no undercutting efects in the line
patch target, showing that the difusion transferred
dyes travel to the receptor wlthout si.gnificant
15 lateral spread which would result in unsharp images.
Exam~ 2
Three dye, full-colour co~in~
~:
~:~ 20 The following dyes were employed Yellow Dye 1
Magenta Dye l and Cyan Dye 2.
A solution of the yellow, magenta and cyan
dyes (respectively 0.~3 g, 00025 g, 0.03 g) in ethanol
: (6 ml) and water (3 ml) was added in yeIlow light to
25 an aqueous gelatin solution (3.6 g in 30 ml water~ at
. 40C.
:; 30 ~
.. ..
3i~3
=34=
Aqueous Tergitol TMN-10 (Union Carbide, 10~,
2.0 ml) and glyoxal t30%, 0.5 ml) were added to the
resulting solution and then 4-methoxyphenyl phenyl-
iodonium trifluorsacetate (2.0 9) in dimethylformamide
~2.5 ml) was added in the dark. The radiation-
sensitive mixture was coated onto clear subbed
polyester ~4 mil) using a loop-coater at approximately
20 micron dry thickness.
After drying in an air cupboard for one hour
10 at 25C, the following tests were made using a
microdensitometer and the appropriate narrow cut
filters. The film was panchromatic in nature. The
results in the following table were obtained by
measuring the optical density at the wavelength o~
15 maximum absorbance oE the dye. The dyes were
transferred without exposure, as in Example 1, the
transfer time again being 5 minutes. The receptor of
Example 1 was employed.
Dye Initial Transferred ~max Energy
Peak Density Peak Density (nm) Sensitivity
(Transmitted) (Reflected~ Dmax-l
(x105 mJ/m2
Yellow 1 3.3 2.8 454 a 9
Magenta 1 3.5 2.1 562 b 27
Cyan 2 3.4 2.0 673 c 5
a Filter at 461.6 nm, output power 1.79 mW/cm2
~ 30 b Filter at 551.4 nm, output power 2~89 mW/cm2
;~ c Filter at; 670n7 nm, output power 2.52 mW/cm2
,:
, ,. ;
= 3
Colour Proofing Application
A sample of the above Example was exposed in
the following manner, using half-tone colour
separation positives. On top of the sample was placed
the black colour separation positive ( thus the black
information is retained from the start). On top of
this assembly was placed the appropriate colour
separation positive and Wratten filter. White light
10 exposure was given, e.g. from a metal halide lamp.
Exposure 1 : Filter 47B (blue) and Yellow Colour
Separation Positive (CSP)
Exposure 2 : Filter 61 (green) and Magenta CSP
15 Exposure 3 : Filter 29 (red) and Cyan CSP
Exposures were perormed in a vacuum frame with a 4 kW
metal halide source at a distance of 0.5 m.
The resulting half-tone, full-colour proof was
20 fixed by dye diffusion transfer to a vesicular
polyester receptor, coated with gelatin and
poly(4-vinylpyridinium) methosulphate as described in
Example 1. A mirror image ccpy was obtained which
retained the large range of 4 to 96~ halftone dots
25 (utilising a 120 lines per centimetre screen). There
was no observable dot fill-in due to dye spread at the
96g dot level.
Colour proofing in this manner involves a
30 total of four steps, compared to the twelve necessary
in most conventional pre-press prooing materials,
e.g. Dupont Cromalin and 3M Matchprint. The invention
also has ~on-lineR potential~ requiring only three
e m~r~
. . ,
,
-3~
exposures and one fixing step, This manner of
exposure is known for dye forming reactions, as
described in United States Patent Specification No.
3 598 583.
Examples 3 to 5
Effect of iodonium sa.lt on Dmin in rece~
10 Iodonium Salts Sensitivity Dmin
(x105 mJ/m2) transferred
_ _ _ _ _
A ~ ~ ~ OMe 11 0.20
CF3Co2~3 '
B ~ oEt 9 0.15
\~J
CF3CO2~
C ~ n-Bu S
2 5 CF3C02~)
:
3~ :
,. . .
~3~9~
To a solution of Cyan Dye 2 (0.04 g~ in
ethanol ~6 ml) and water ~2.5 ml) in gelatin ~3.6 g in
28 ml water) and Tergitol TMM-10 (10% alqueous, 1.5 ml)
was added one of the above iodonium salts (0.5 g~ in
dimethylformamide (1.5 ml) in the dark. Glyoxal (30%
aqueous solut~on 0.1 ml) was added and the ~ixture
loop-coated onto subbed clear polyester
(100 micron) and dried in air at 25C for one hour. A
30 micron dry layer resulted (0.4 g/dm2 deposition~.
The film was exposed as in Example 1 and dye
transferred as in Example 1 to clear subbed polyester
coated with gelatin and poly(4-vinyl pyridinium)
methosulphate. The process solution used was made up
as followq: water (40 ml), ethanol (20 ml), sodium
15 acetate 1,0 g)j acetic acid (2.0 ml), Tergitol TMN-10
(10% aqueous, 1.0 ml). After exposure and dye
transfer as described in Example 1.
1. The Dmax in each case was measured as 3.8 in
the donor and 1.5 in the receptor
~ 20 (transmittance~.
; 2. The sensitivity at 670.7 nm was determined
from density/time plots on a microdensitometer
as previously describedO
The sensitivity of the donor layer, the
minimum (background) density on the receptor after
transfer and the contrast value after transfer are
recorded in the following table.
"
.. .
.
i' .
=3~
_
IodoniumSensitivity Dmin Gamma
salt(x105 mJJm2) (400 nm) (Contrast)
A 11 0.20 -3.5
B 9 0.15 -4
C 5 0.08 -4
The sensitivity of dye ~ransferred to the
receptor was also investigated. The density/time plot
at 670 nm showed bleaching only for the first S
seconds before levelling out to constant density. The
15 maximum optical density dropped only by about 0.2 over
this period. In the case of a 30 second water-wash
after the diffusion transfer to remove trace iodonium
salt, there was no such small initial loss of density.
The larger the alkyl group on the iodonium
20 salt, the lower are the Dmin values at 400 nm. ~hus,
there can be immobilisation of the bleach product by
transference of the alkoxyphenyl group Erom the
iodonium ion to the dye. The iodonium salt would
normally be selected to provide a low minimum density,
25 e.g. less than 0.1 or preferably much lower.
_~l~tio
A solution of 4-butoxyphenyI phenyliodonium
trifluoroacetate (0.5 g) in DMF ~2.0 ml) was added in
the dark to a solution of Cyan Dye 2 ~0.04 g) in
::
~ ,
~~'
.
i3~
- 3~
gelatin (3.6 g~, water (30 ml), ethanol (6 ml~, and
Tergitol TMN-10 (10% aqueous, 1.5 ml) at 45C.
Glyoxal was added (30% aqueoust 0.5 ml) and the
mixture loop-coated as in Example 1 onto clear, subbed
polyester in the dark. After drying in the dark in an
air-circulated cupboard at 25C for one hour. One
strip of film was exposed to a 250W tungsten iodine
source for 5 minutes. That strip w~re contacted with
the receptor of Example 3. Dye transference was
10 permitted in 5 minutes using Process 501utions A and B
(Dmax). The maximum and minimum density on transfer
was measured. Bleach product transference after 5
minutes using Process Solutions A and B was also
measured by the minimum density figure. Iodonium ion
transference, judged by any variation of the
density/time plot at 670 nm, the maximum sensitivity
peak of the dye was also measured.
The results are reported in the following
Table
2~
Processinq Solution A
water 40 ml
ethanol 20 ml
acetic acid 1 0 g
sodium acetate 2.0 g
Teryitol TMN-10
(10~ aqueous) 005 ml
Process ng Solution B
water 40 ml
ethanol ~ n ml
ascorbic acid 1.0 9
sodium isoa~scorbate 3.0 g
Tergitol TMN-10
~lU% aqueous) 0.5 ml
-.,:
. ~ . i
, . ,
=4o=
Table
Results after transference of dye usin~ Solution A
(5 mins/20C)
_ . _ _ _
Solution Dmax a Dmin a Image density change
_ __ _ _ _
A 1.0 0.05 0.1/5 secs b
B 1. OO . 05 No change
a transmitted
b 0.1 density drop in 5 seconds, stable subsequently.
~ hus, with Solution B, there is essentially no
transference of the iodonium salt to the receptor.
The combination of a long-chain alkyl substituted
iodonium salt and antioxidant anion (e.g. ascorbate)
20 is preferred.
The process solution has the following
functions:
1. it mobilises the dye from the donor to the
receptor (too rapid movement is not required, as this
25 will lead to loss of resolution).
2. it assists in immobilising the iodonium cation.
3. it contains stabilisers to give the dye light
stability after transfer (e.g. antioxidants, oxygen
energy quenchers~.
4. it may also contain oxygen-barrier polymers (e.g.
polyvinyl alcohol).
: '
':
....
,
'.
3~
=~1=
In the process Solution B, sodium isoascorbate
performs two functions: a) immobilises the iodonium
cation, and b~ reacts with oxygen in the receptor
layer leading to oxonol dye stability in the receptor.
Example 7
An enlar~ed print_of a 35 mm slide
The film of Example 2 was exposed to a 5x
linearly expanded image from a 35 mm colour slide.
The light source was a 250 W tin halide lamp. After
20 minutes exposure, the resulting copy was stabilised
b~ contacting with a vesicular polyester receptor,
15 coated as described in Example 2 with gelatin,
poly(4-vinylpyridinium) methosulphate and chrome alum.
Process Solution B was used from Example 1. After 5
minutes, the receptor was separated and 30 second
water-washed, to give an enlarged copy of the colour
20 slide.
Exam~
Integral Donor/Rece~or Construction
The following layers A to D were sequentially
deposited using No. 6 K-bar (R.K. Chemicals Co.) onto
4 mil subbed polyester, with air-drying at 20C for 1
hour between each coating. Layers A to C were
30 deposited in yellow 1Ight and layer D in the dark.
:~ :
.,
3~
-42-
Poly~4-vinylpyridiniUm) methosulphate (0.2 9l
and acetic acid (0.3 ml) was added at 45C to a
gelatin solution (1 g in 10 ml water). ~rergitol
TMN-10 (10~ aqueous, 0.3 ml) and chrome alum (0.05 g
in 1 ml water) were then added, and the mixture coated
and driedO
La~er_B:
Titanium dioxide (1 g) was added at 45C to a
10 gelatin solution (1 g ln 10 ml water). The mixture
was ultrasonically mixed for 0.5 hour to disperse the
TiO2 in the gelatin. Tergitol TMN-10 (10% aqueouQ,
0.3 ml) was added, followed by glyoxal (10%, 0.5 ml).
The white solution was coated over layer A and dried.
15 Layer C:
0.5 ml Rotring ink (india black~, Tergitol
TMN-10 (10~, 0~3 ml) and glyoxal (10%, 0.5 ml) were
added to a gelatin solution at 45C ~1 g in 10 ml
water). The black mixture was coated over layer B and
~0 dried. (At this point, one side of the polyester base
appears black (layer C) and the other white (layer B)~.
Layer D:
A mixture of oxonol dyes, Yellow Dye 1
(0.04 g), Ma~enta Dye 1 (0.04 g) and Cyan Dye 2
25 ~0.05 g) in ethanol (2 ml), water (1 ml) and DMF
(0.05 ml) was added at 45C to a 10% gelatin solution
(10 ml). 4-Butoxyphenyl phenyliodonium
trifluoroacetate (0.3 g in 1 ml DMF), Tergitol TMN-10
(10% aqueous, 0.6 ml~ and glyoxal (10%, 0.5 ml) was
30 added in ~he dark. The sensitive mixture was coated
onto layer C and dried. (Note some yellow dye
migrates to layer A and colours it yellow).
~3q;~
=. ~
The dried cornposite film was imaged in contact
with a colour transparency using a 250 watt xenon
light ~30 seconds at 10 cm). Application of the
process solution described in Example 1 leads to
transferenoe of the dye from layer D to layer A in 10
minutes. A colour print results.
Example 9
An oil dis ersion coatina to achieve im~roved
__ P , _ .,
lO sensitivity
A 10~ gelatin solution at 45C was prepared to
10 ml, In the dark were mixed a solution of oxonol
Cyan Dye 2 (0.~3 g) in 0.~ ml di-n-butylphthalate and
15 } ml butan-2-one and a solution o 4-butoxyphenyl
phenyliodonium trifluoroacetate (0.2 g) in 1 ml
butan-2-one, This sensitive mixture was added
dropwise to the ~elatin solution with vigorous
stirring. ~fter 90 seconds of vigorous agitation,
20 Tergitol TMN-10 (10% aqueous, 0.3 ml) and glyoxal (10%
aqueous, 0.3 ml) were added, The mixture was
knife-coated at 3 mil wet thickness onto subbed
polyester and dried in air at 20C for 1 hour. The
film was analysed as follows:
25 1. The density at 670.7 nm was 4.5. The width at
half-height of the dye absorption had
increased to 70 nm from 45 nm in the
non-dispersed coatingsO
2. ~ The sensitivity of the film was 2 x 105 mJ/m2
measured at the dye peak, using a
microdensitometer,
: ,:
: : . :
=44-
3. Application of the process solution described
in Example 1 leads to a transference of 30% of
the dye ~as deduced by the transmitted density
to the receptor after 5 minutes).
'
'~
~: .
:: ::
.
.
