CA1067330A - Photographic element with agx layers containing colorless cyan forming and yellow colored couplers - Google Patents

Abstract

COLOR CONTRAST RADIOGRAPHIC FILM

Abstract of the Disclosure A photographic element having at least two silver halide emulsion layers, one layer containing a colorless cyan-forming coupler which produces a negative image and the other layer containing a colored coupler which upon color development with a p-phenylene diamine developer produces a positive dye image of contrasting color to cyan, will produce a color contrast radiographic picture after exposure and development.

Description

~0~;73~1 It is normally accepted in the photographic art that a color contrast fllrn is very deslrable 7 especially ln the specirlc area of radlographyO
; A color contrast rilm according to the present invention is capable Or producine upon color development wlth p-phenylene diamine developers an image of the sub-~ect in two opposite scales of distinct colors, one negative and the other positive. Both colors are to be chosen to "create a contrast"O Contrasting colors are those colors sufficiently distinct as to be able to de-fine a distinct border to the eye when viewed next to each other. For example, the best contrasts are comple-mentary colors such as blue and yellow or other specif~c~ , combinations as blue or blue-green (cyan) and red or red-blue tmagenta).
.. ..
One o~ the recent inventions in this fleld has ~-been described in Italian Patent 974,830 of the same . .~
applicant. This system un~ortunately displayed instability -~

in the colloidal silver-imageO

~` 20 Some prior art in this ~eld is U~SO 2,644,096;

-~ 2~593,925, 2,931,904; 2,807,72~, 2,906,881; CH 295,100;

' DT 970,220; 977,204; 1,011,277; 1,046,495; 1,076,490;

;~ 1,135,754; DT-OS 1,946,652 and 2,045,399; FR 1,056,200;
;
1,190,520; 1,283,925 and GB 716,064.

In addition, British Patent 1,286,831 describes a new method based on a materlal which includes (a) at least one colorless color coupler capable of forming an ~ ~
azomethine quinoneimine dyestu~f by coupling with an - ~-oxldized aromatic amino developing agent and tb) at least ~ :
30 one colorless compound whlch is capable of oxidative - ~

. 1 b ~

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~067330 coupling with sai~ colorless coupler t,o form a dye~
Other methods based on "masked'~ color couplers (couplers which have chromogenlc groups as splitting-off subsitutents attached to reactive methylene are knownO
These masked couplers are colored before development and react with p-phenylene diamlne developers to give a dif~erent color, as for example described in U~S. 2,449,966) have been tried, but as stated in British Patent 1,286,831, the secondary or masking image formed in color masking is of very low density in relation to the main image and it would be lncompatible with the obJect of color masklng to make the secondary ima~e otherwise than of such very low density.
Attempts to make color contrast radiographic .
based on a combination of colorless-masked couplers in a single layer, as normally known to the sk~lled in the art of the substractlve process, did not give good results0 A sensitometric analysls on these methods cannot be made because it is not traditionally meaningful to analyze the involved sensitometrlc curves (one negative, the other posltive)O This i5 because of the inter~erence due to the .. silver reduced upon color development (present in the ~inal ~; image in the form of a negative image) and because o~
.~ secondary absorptions o~ the dyes forméd by the couplers 25 upon color development~ It has been believed that the ;~
couplers inter~ere to negatively affect each other's ;
., .,: ~~ reactivity, but the nature of this interference is not well .: understoodO This is true, for example, when the couplers - are lntroduced into the same negative emulsion layer by 30 the dispersion ~echnique~ In dispersion techniques, the ~ -~ ~ '

2 ~`~

. . - , . - , , . , . '~. . .
, .... . . . .

106"9'330 coupler molecules are present in the layer dlssolved ln -~
water-immlscible organic solvents, dlspersed ln the layer --it~elf in the form o~ very small droplets whlch should limit every competitive reaction between different specie~ :
of couplers slnee dispersed separately (see in~ra 3~703,375 Table l).
It has been found that very good results can be ; obtained with associating the colorless coupler to a ; negative silver halide layer ana the colored masking coupler to another negatiYe silver halide layer, said couplers being preferably dlspersed in the layers dissolved in - water immiscible organic solventsO
It has also been found that emulsions havlng ~; more speed, that is gralns blgger than those normally used ;~
:., , ~ , : 15 in high-definition radiographic materials, do not affect `. the quality of the positive image when associated with the ` colored couplers which modulate said positive imageO .

:: It has been found that very good results are : :
, .
achieved when the emulsion associated with the colored coupler is more sensitive than that assoGiated with the .- colorless coupler by at least 3 DIN at a denslty equal to 0O5 measured at a light of color complementary to the color formed upon color development o~ the colored coupler .:
. . . - .
- itselfO For example, when an emulsion is associated with , . :. - .:
25 a colored coupler, e~gO, a yellow-colored ccupler forming : -:~: a magenta dye, then the sensiti.vity is measured by ex~
: posing the emulsion layer coated on a base at a green light, lOeO, the contrasting color to that formed by the dye), processing the expo~ed photographic element in a ;~
30 standard developing bath and fixer bath (compris~ng the .~ . ;
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color development bath and ~ixin~ bath of Example l1) and determining in logE (whsrein E means light energy Or exposure), from a sensitometric curve, the expo~ure neceA~ary to get a dens1ty equal to 0~.5; ln the comparative sensitlvity, every O.l logE of d~r~erence is assumed to correspond to one DIN Or dlfrerence in sensitivity and thus it is clear that less exposure corresponds to higher speed.
The present lnventlon thus rerers to a photo-~raphia element ror u~e in radiography wh1ch includes a base and at least two ~i.lver halide emu1sion layers charac-., .
: terlzed ~y the ~act that one Or said layer~ is reac~lvelyassoclated wlth a colorless cyan ~orming coupler in a way : : as to give a negatlve colored~lmage upon color development wlth p-phenylene~dlamine developers and the other emulsion ~s as~ociated with a colored coupler which constltutes the positive~image whose color i8 chosen to ~rovlde .~ ~ the desired color contrast wlth the other dye r`ormed .
(iOe~ 7 the cyan)~ This oontrasting color coupler has a 20 chromogenic group attàched to~the reactive methylcne :~
ln the ooupling position o~ the co~pler, and the chromo-genl~ group (the group whlch gives a color to the coupler) :
mu~t be what i~ known in the art as a splitting-o~f group. ~ -Tha~ is, a group capable Or being expelled ~rom thé coupling . ~
posltlon during reaation with oxidized p phe~ylene diamine devoloper without requlrlng any silver ion a~ oxidizlng agent. These couplers mu~t be there~ore two-equlvalent .; ~ .
color ¢ouplers. Examples of these well-known splittlng-of~
group8, and ~he prererred groups are ary:lazo, pre~erably ~: 30 phenyl or naphthylazo whlch mag or may not be substituted , .

- 4 -,`
.

:"': . ' ~ , .-' ~;7330 Witll alkyl, alkoxy, halogen, cyano or nitro groups. As these t~o-equivalent couplers are well known in the art, further description is not believed neces-sary. I`his coupler with splitting-off ~ k and chromogenic group, upon color development with p-phenylene diamine developers, generates a colored dye in the layer itself in the form of a positive image whose color is chosen to make a color contrast with the cyan color of the negative image.
An example of this would be a colorless cyan coupler and a yellow colored, magenta forming coupler. The cyan is formed in one layer where .
coupling has taken place, and the yellow is destroyed (and magenta produced) .
in the other layer where coupling has taken place. Thus, a negative cyan, -positive yellow, and negative magenta image is formed. The contrast would be blue against yellow. This qualitative example describes one aspect of the invention.
: The present invention provides a photographic element for use ln radiography which includes a base and at least two silver halide emulsion ` ~-. layers, said element characterized by the fact that ``~ 1) silver halide emulsion layers in the element may contain as couplers only colorless cyan forming couplers and yellow colored couplers, :1 ::,,; - .
2) at least one emulsion layer reactively associated with said colorless cyan forming coupler so as to give a negative colored cyan image upon ~ ~ `
color development with p-phenylene diamine, 3) the other of said at least two emulsion layers being reactively :~
: associated with said yellow colored coupler so as to leave a yellow colored positive image and a magenta colored negative image upon ~ ;
color development with p-phenylene diamine.
The present invention refers to a photographic element as per above : in which said colored coupler is a yellow colored coupler which upon color dev-' elopment with p-phenylene diamine developers forms a magenta dye in the form .- of negative image.
,..................................................................... ~: , The present invention also refers to a photographic element having as a colored coupler a magenta (preferably a magenta-reddish) colored coupler , . , ~ ~

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which upon color development with p-phenylene cli~nine developers forms a ~ .
cyan dye in tlle form of a negative image.
The present invention refers to a photographic element as per above characterized by having the emulsion layer associated with the colored coupler directly coated .,',~'., ~ ; ,, ''' '' .'`, ' ~ ",' . ::: ~ : ~

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1~6'7330 on the base and the emulsion assoclated with the colorle~s coupler coated thereonO
The present invention pre~erably re~ers to a photographic element as per above havlng coated on one slde of the base a negatlve emulslon layer as~ociated with a colored coupler and coated thereon an emulsion layer ~ ~ :
associated with the colorless cyan forming coupler and coated on the other side of the base a negatlve emulsion associated with the colorless cyan forming coupler. ~` -The present lnvention also refers to a photo-graphic element as per above havlng coated on each side o~
the base a silver halide emulsion layer associated with the colored coupler and coated thereon a silver halide emulsion layer associated with the ~olorless cyan forming couplerO .
: 15 The present inventlon more preferably refers to `~
: a photographic element as per above having the silver .
. -: .
; halide emulsion associated wlth the colored coupler mor0 sensitive than the silver halide emulslon associated with the colorless coupler of at least 3 DIN at a denslty ; ~ .
equal to 0.5 measured at a light of color complementary to the color formed upon color development o~ the colored ; coupler itsel~ as described beforeO :
The present invention most pre~erably re~ers ~ ~
to a photographic element as per above having the silver ~ .
halide emulsions associated with a green ~ensitizing dye in order to improve the sensitometric respon~e o~ the - photographic elementO :
The present lnvention further ré~ers to a photo-graphic element as per above including the couplers -colorless and colored one~,- introduced therein by the :.
- 6 - ' , ' ''' :.: :, .... .
... . . .. . .

6733~

dispersion techniqueO
The photographic element Or the present invention may contain acutance dyes pre~erably associated with the emul~ion layer directly coated on the baseO The color of these dyes i5 preferably complementary to the color o~ the llght emitted by an lntensifylng screen used for exposing the element itsel~ as known to the artO Since the color Or the light of pre~erred intensifying ~creens is generally . :
blue or green, when used in combination with photographic ~:
lO elements including blue or green sensltizing dyes, a ~ :
good acutance dye to be used within photographic elements ~ :~
according to pre~erred embodiments of the present inven~
:~ tion would be a ma~enta colored dye.
;; ~ -; The nature of the couplers to be used withln the : . .
15 present invention depends upon the-color contrast we want ~ ~

to get. For example, for having a good blue-yellow color ~ ~:

~; contrast 3 a cyan colorless coupler can be used ln combina-~: tion with a yellow color coupler which forms a magenta dye ~`
, ~ , . : upon color development with p-phenylene dlamine developers. ~ .

- According to the substractive process ~or gettlng :,. . ..
a color image, cyan is ~ormed by the blue plus green, and , mage~ta whlch is ~ormed by blue plus red (equal to minus .
. . , green)O This means that the presence of a ~agenta dye in ~ comblnation with a,cyan dye makes th~ f~nal lmage more blue~ `

.:- 25 improving the color contrast o~ the image itselr.

`.~ A color contrast cyan-magenta turned out to be ` better than a contrast blue-yellow because the magenta .;- color proved to be less brilliant than the yellow colorO

This can be very good for the eyes of a radiologist who .: 30 has to study the radiographs for long periods o~ timeO : :

~ 7 ~
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., :, .'; , ~C)6733~) Additionally, because of lts acutance dye functlon, -the magenta dye distributed in the form o~ a uni~orm fllter before exposure improved the dePinition oP the ~inal image itself, e~peclally when exposed to green emittlng screens.
Couplers which can be use~ully embodied into ~: :
photographic elements Or the present invention in¢lude, Por example, the ~ollowing:

CH30 ~ N-N-CH C-~HC0 C0 ~N .NH , ~`~
10Cl ~ Cl CH
Cl) ' .~ -Cl ~ CSHll ~:~` 15 C5Hll ~:

Cl ~ NHCOCH-0 ~ ~;

Cl :, , CH
C3) ~ NHC~CH2-0 ~ C5H

Cl . . .
,,, : ~, -', , : ~
,~:, ,,"~ '~ .

'.:, ' ' ;, .', ' ~,: ,' ' ,: '' ., - .

~L~)67~3C) ,CH~-0 ~ ~ " ~ C12H25 ; C4) `~N~

Cl GONH

C l,lH 2 3 ,.
C5) ` ln N
''`. ~\ i . .

~ -N
; COOC~3 ;~

:. 15 Couplers of this type have been described in .` ; U.S. 2,600,788; 2~367,531; 2,369,929; 2,423,730; IT `:~
, ` 800,361; 876,084; 883,938. '~
.. . . .
. One very good green sensitizing dye is the ;
: following one~
.:;. C2H5 ' '~
~ \C CH-C CH=C/ ~

~` C H N 6 5 ~ ~;
(CH2)4 , (CH2)4S03H , .. ..
! $O3 '~ ' `
.... .
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, Sensitizing dyes Or thls type have been described in U.S. 2,503,776 and IT 493,530 and 520,746.
The couplers useful to the scope of the present invention are preferably introduced into the photographic elements of the present lnvention by the dispersion tech~
nique as de~cribed for instance in U.S. 2,322,027; 2,801,170;
2,801,171; 2,870,012 and 2,991,177. Briefly, the solvent dispersion technique involves dissolving a coupler in a substantially water immiscible organic solvent and then dispersing the so-prepared solution as extremely fine drop-lets in a hydrophilic colloldal bindsr. Gelatin is the pre~erred colloidal binder, but other polymeric colloidal ~ -binder materials, known to the art3 can also be utilized.
~` Obviously, when the couplers are incorporated into the emulsion by the solvent dispersion technique, the dyes `~ derived therefrom upon color development are also con-~ ~ -tained (dispersed) in the emulsion dissolved in the substantially water-immiscible organic solvent~
It is highly desi~rable that the couplers and the dyes derlved therefrom upon color dévelopment be - hydrophobic and non-diffusing in order to hare the maximum definition quality. To thls purpose, the couplers used . ~ , .
in the present invent~on are prorided with b~ sting aliphatic chains having a total o~ at least ten carbon `~ 25 atoms.
The silver halide emulsions use~ul to the scope ;~ of the present lnvention are those normally known to .,.~ , .
- those skilled in the art~ E~peclally good are bromo- ~
iodide emulsions dispersed in gelatin or other equivalent -.. ;. .
; 30 hydrophilic colloidal binder, natural or synthetic, as . . .
, .

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:

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' 11D6~330 ~;
for instance described in U. S. Patents 2,286,215;
2,328,808; 2,322,085; 2,527,872; 2,541,474; 29563,791;
2,768,154; 2,808,331; 2,852,382.
Said binder will preferably consist of gelatin ~ .

5 possibly containing dispersed particles of hydrophobic , . .; .
polymer, such as for instance, polyethylacrylate, to - ;
improve the physical characteristics of the final layer. ;; ~-The layers, thus obtained, can be hardened with ~ hardeners known to those skilled in the art, such as for ; 10 instance epoxides, formaldehyde, glyoxale, succinic, glutaric and resorcilic aldehyde, mucochloric and muco~
bromic acid, as described in U.S. patent 2,0803019, or .
~ mixtures thereof, as described for instance in U. S.
:; . .
patent 2,591,542. ~ -. . . ~ . .
~ 15 The above emulsions can be chemically sensitized .
~;~ either by addition of sulfur compounds, as described for .......... instance:in U. S. 1~ 574,944; 1,623,469 and 2,410,689 and/or by addition of noble metals, such as rhutenium, rhodium, iridium, platinum and palladium; or by addition of Au salts, ..
20 as described in U. S. 2,399,083. They also can be stabilized ;
:.~ with Au salts, as described in U. S. 2,597,856 and 2,597,915.
.;
.......... The emulsions can contain organic stabilizers and : antifoggants of the cyclic amine type, iminoazoles, such : :
` as mercaptobenzimidazole; triazoles, such as those des- .` ;.
; 25 cribed in U. S. 2,444,608; azaindenes, such as those described in U. S. 2,444,605; 2,444,606i 2,444,609; 2,450,397;
., . .~
~ 2,713,541; 2,716,062; 2,735,769; 2,743,181; 2,756,147; ``

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~673313 2~772,164 and E. J~ Birr ln Z~ Wiss. Phot 472 (1952);
tetrazoles, such as l-phenyl-5-mercapto-tetrazole~
thiazoles and benzothiazoles, such a t l-methyl-benzothiazole and benzothlazole quaternary salts, as de~cribed ln U S.
; 5 2,131,038; mercapto-benzothiazoles, such as l-methyl-.: - .
mer~apto-benzothiazole; oxazoles; thiosemicarbazides;
pyrimidines, iodonium derivatives; benzen~ulfinic acids;
,, . ~ , inorganic stabilizers o~ khe zinc and cadmium salt type, ~ -~ - . , .
such as those described in U. SO 2,839,405~ ~-The emulslon can ~urther contain any suitable -plaskicizer, known to the man skilled in the art 3 such as glycerin or any surfactant which may be useful for coati~g khe layers on the support base or on each other~
The photographic elements of the present in- -15 vention are to be developed in p-phenyléne diamine color ~ -~
development baths as normally in the art of color photcg~
raphy. Particularly good results, however, can be ` obtained by using developing baths as described in Itallan `` Patent 974,830, whlch include a p-phenylene diamine ,~ 20 compound, alkali or ammonium thiosul~ate and phenldone in ;
an aqueous alkaline solution. ~ ~
:. .
Examples of suitable p-phenylene diamine developers, :: ;
which can be employed to develop photographic elements `~ containing the couplers o~ the present lnvention, are the ~ollowing developers and thelr salks such as the sul~ites, the hydrochlorides and the sul~ates o~:
,~'t a) N,N--diethyl-phenylene diamine; -~ b) N-ethyl,N-~-methansulfonamido-ethyl-3~methyl-4-- aminoaniline;
t,:
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~ 733(~ :
c) N-ethyl,N-hydroxyethyl-2-methyl-p-phenglene dlamine;
d) N-ethyl,N-hydroxyethyl-p-phenylene diamlne, : e) N,N-dlethyl-2-methyl-p-phenylene diamine.
The development step is generally followed by a fixing acid bath including thiosulfate ions which have :
the function of stopping the development and carrying away silver ions in non~exposure areas in the form of soluble silver-thiosulfate complexes. A washlng step can follow as a stabilizing bathO

EXAMPLE 1 ~ ~ -:: A color contrast X-ray film was prepared.by : .. . .
.~ coating on each side of a colorless polyester base two photosensitive layérs and a protective layer following the sequence given below (corresponding to the following ` structure: p-c-m-b-m~c-p, wherein p = protective layer, .
c = cyan containing layer, m = magenta containing layer, b = base~

m) A gelatin silver halide photosensitive layer in-. 20 cluding a bromo-iodide emulsion (3% lodide), hardeners and stabiIlzers, havlng a silver coating weight of 0O5 g/m2. The layer also contained 00 23 g/m2 Or yellow masked coupler Cl described beforeO (Such coupler was introduced into the layer by the solvent ` 25 dispersion technique, according to the follow~ng method: 6 g~ of the coupler were dissolved in 5 cc. ~ ~ -of dibutylphthalate, 5 ccO of triphenylphosphate, and ~6 cc. of ethyl acetate~ This solution was then ~ :
:: :

. - 13 ~ ~

. :

~ , ~ . . . . .
'',',: "', . -'" "'' ~' ''' . ' '' ' ' , "~, . .... .

6733~) dispersed in 60 CCD Or a 4% water solutlon of gelatin ~ - ;
; and 5 cc. Or a 10% water solutlon of a surfactant agent). ~ -c) A sllver halide photosensitive layer consisting of a bromo-iodide emulsion (3% iodide) lncluding hardeners and stabilizers, having a silver coating weight of 2O5 g/m2. The layer contained also 3.15 g/m2 of the ; coupler C2 described above (Such ooupler was lntro-duced into the layer by the solvent dispersion ;
technique, according to the following method: 10 g of the coupler were dissolved in 1~25 ccO of dibutyl~
phthalate, 1.25 cc. of dibutylformamide, 0O5 gO of surfactant and 10 ccO of ethyl acetateO This solution was then dispersed in 32 ccO of a 10% water solution of gelatin and 10 cc. of a 5~ water solution of sur-factant).

-~ p) Protective layer ~f hardened gelatin.having a gelatln ~ coating welght of lolO g~m : 20 A color contrast X-ray f`llm was coated as des-cribed in Example 1, with the difference ~hat in thi~
case the layers m~ and c) were optically sensitized to the green reglon of the spectrum by adding the sensi-;~ tizing dye Sl described above (about 100 ~moles dye per . .
~ 25 g-atom of silver)~ ~

., . .

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. . .
. ~

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~6~330 _ A color contrast X-ray film was coated a~ des-cribed ln Example 2. In thls exarnple, a~ogeranine as a : magenta acutance dye was added to the layer m) in a quantity glvlng a den~ity of about 0~10 when read with a green llght on a Westrex Densitometer proYided with a filter ~tatus A, A color contrast X-ray ~llm was prepared by coating .
on each slde of a colorless polye ter base ~wo photosensitlve layers and a protective layer ln the following sequence:

,~ m~ A gelatin ~ilver halide photosensitlve layer including a bromo-iodide emulsion~(2~ iodide having a sensltlvlty 3 DIN hl~her than the emulsi.on described in Example 1, : mea ured~as previously~described), hardeners and 3tabl11sers and a sllver coating welght~: o~ 0.4 g/m2.
The layer contained also O,Z3 g~m2 of the yellow ma~ked .-~: coupler Clo In addition, the layer also contained a .:.~ . :
magenta acutance dye as descrlbsd in Example 3 c) A layer as descri~ed in~Example l, :.:
20 The abo~e-described layers m) and ~) were optically sen~l-:~ tized to the ~reen reglon Or the spectrum by addlng ~ensi-tizing dye Sl a3 ln prev~ous Example 2.

~ . . . .
,.... ~ p) A protective coatlng as ln Example l~ :
. ~ ~
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. .
':

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6733(~ :
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EXAMPLE 5 ~
,.
A color contrast X-ray materlal wa~ coated as described ln Example 4, with the difference that both layers m) and c) were prepared including photosensitive bromo-iodide high speed emulsions simllar to that used for layer m) of Example 4 .~ .' '.' '.

A color contrast X-ray fllm was coated according : to the followlng scheme: p-m-c-b-c-m-p, wherein m was a :

photosensitlve emulsion layer assbclated with yellow : magenta forming coupler and green sensitizing dye as layer ::
.. . ... m) of Example 2; c) was a photosensltive emulslon layer as ociated with colorless cyan forming coupler and green sensitizing dye as layer c) of Example 2; p) was the same .: , protective layer of Example l; and b) was the same poly~

ester base of Example 1D
,. ' ' ~' '~ EXAMPLE 7 . ; ~
.
~:~ A color contrast X-ray film coated accordlng to the following scheme p-m-c-b~c-p, wherein m) was a photo-sensitive emulsion layer as described in Example 2, associated with oO46 g/m2 of the ~ame yellow magenta forming coupler, and having a silver coating welght of ; ~ :

`'.. lo O g/m of æilverO The silver halide gralns were . ~ . . .
:~ rendered green sensitive by means of the same green ~ 25 sensitizing dye described in Example 2; c) was a photo-.. , ~ . .
sensitive emulsion layer similar to layer c) of Example 2, p) was a protective layer as described ln Example l;
.,.

~" ' ' ' -:

- , :,: .
, . ~ , . , ~a~6,7330 and b) was the same polyester ba~e o~ Example lo :
A color contrast X~;ray materlal was coated accordlng to the following scheme: p-c-m-b-c'-p, wherein 5 m) was a photosensitive emulslon layer as described ln .~ :
Example 2, with a silver coating weight of 0 8 g/m2 and ; ~ :
a yellow masked coupler coating weight o~ 0.37 g/m2;
c) was a photosensitive emulslon layer as described ln Example 2, with a silver coating welghk of 2.1 g/m2 and a coupler coating weight o~ 2.65 g/m2; c') was a photo-sensitlve emulsion layer as described in Example~2, with ~ a silver coating we~ght of 2.9 g/m2 and a coupler coati~g : 2 -~ weight of 3.65 g/m ; p) was a protective layer as described ~-in Example l; and b) was the base o~ Example lo A color oontrast X-ray film was coated according ~ : to the following scheme: p-c-m-b-c'-p, wherein m) was a : photosensitive emulsion layer as described in Example 4, with a silver coating weight of 008 g/m2 and a yellow masked coupler coating weight o~ 0046 g/m2, c~ was a . photosensitivé emulsion layer as describéd in Example 2, .
.:` with a silver coating weight o~ 1.7 g/m2 and a coupler :~

, ~. ,, ~ .
. coating welght of 2 15 g/m'; c~) was a photosensitive ~ emulsion layer as described in Example 2, w~th a silver ~, , , ~ .
- 25 coating weight of 2~5 g/m' and a coupler coating weight .
of 3015 g/m2; p) was a protective layer as descrlbed in Example l; b) was the baseO :

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~C~673~0 EXAMPL~ 10 A color contrast X~ray fllm wa~ coated according : to the following scheme: p-c-m-b, wherein m) was a photo- ;
sensitive emulslon layer as described in Example 9; c) ;~
was a photosensitlve emulslon layer as described in Example 2, having a silver coating weight of 4,7 g/m2 and a coupler coating weight of 5~9 g/m2; p) was a protective layer as described in Example l; and b) was the base~ ~

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, ~ , . , l~6733a The image quality and the ~en~itometric character- .:
istics of the materlals prepared according to Examples 1 to 10 were compared with those obtained ~ith the materials pre- :
pared as descrlbed in the following examples outside the scope of the present lnventlon EXAMPLE _ A color contrast X-ray film was prepared by coatlng on each side of a colorless polyester base a photo-sensitive layer and a protective layer following the sequence - 10 given below (corresponding to the scheme p-m~c-b-m+c-p)~
m+c) a sil~er halide photosensitive layer consisting of a ;bromo-iodide emulsion (3% iodide moles), including hardeners and stabilizers and having a silver coating weight of 3O0 g/m2. The layer contalned also 0.23 g/m2 i~
: 15 of a yellow masked ~oupler Cl and 3O2 g/m2 of the : cyan coupler C2, Suc.h couplers were introduced by the solvent dispersion technique as respectively des~
. crlbed in E~ample l-m and 1 c. Thé layer was optically ~ :
. ,, sensitized to the green region of the spectrum by . 20 adding the dye Sl (about 100 ~ M dye per g-a~om :~ .

of silver)O ~
p) A protective layer as described in Example l-p. ..
, ~:
EXAMPLE B

:~ A black and whlte 3M X-ray film type R commonly ~ -~

available on the market.

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1al6733() EXAMPLE C

A color contrast X~ray fllm prepared according to Italian Patent 974,830 of the same applicant. The materials described ln Examples 1 to 10 and Examples A, 5 B and C were exposed, in a flrst case, with two beams of blue light (one beam for each side), obtalned by filtering a white light with a 39 Wratten and grey filter having an optical density of 0.400 In a second case, the same materials 9 with the exception of that descrlbed in Example ~ ~ .
B, were exposed with a beam of blue light (obtained as previously described) on one s1de, and with a beam of green light (obtained by filtering a white light with a 57 : Wratten filter) on the other sideO
Blue and blue-green lights obtained as said -.~ 15 above are strictly comparable with the emissions of .~, , ~ normally used CaW04 screen and of a Gadolinium Oxysulfide -I screen. : -, .
~ EXAMPLE 11 .-~ ~ . .
: The materials of Examples 1 to lO, A and C were processed, after exposure, in a rapld automatic processor as described in Italian Patent 965,8049 with a total processing time of 138 seconds from dry to dryO The .,., , : , ~ processing sequence is shown below:
.:
l) Color development bath working at 40Co and having the following formula.

.~ Water 800 c~O ~-Ethylene glycol 3.5 ccO

* Tra~ ~Y]ar~
~ - 20 .' .

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Diethylenetrlamine penta-acetic acid 2O5 gO
Sodium sulfite, anhydrous2 ~ 0 g~
Phenidone 0.7 g.
N-ethyl-N-hydroxyethyl-p-phenylene diamine sulfate lO g.
Potassium hydroxide (35% solution) lO cc Potasslum carbonate 80 g.
Sodium bromide l g.

6-nitro-benzimidazole nitrate ;: (lg solution) 20 cc Sodium thiosulfate 0.3 gO
.~ Water to make l,000 cc .,i , ~:.. . .
pH a~ 20Co ~ lOo70 + 0~05 ~, ,.... ; - l, `. 2 ) Fixing bath having the following formula~
;,. :.~
'~ Water 800 cc Ammonium thiosulfate anhydrous 150 g.
; Sodium sulfite anhydrous 19O5 gO
~- 20 Sodium tetraborate crystals 14.9 g, Sodium acetate crystals 3O5 gO
~ Acetic acid glacial170 l gO
.~ Aluminum sulfate8098 g ~: Sulfuric acid concentrate4.1 g.
r . .
Water to make 1,000 cc ~` pH~at 20C~ 4~ 05 .
3) Final wa~hing~
4) Drying by means of a processor described in Itallan .~ Pat^ent No. 965,804 of the applicant.
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The materlal described in Example B was proce3sed in a process includlng a 3M XAD 90 rapid automatic developer . .
with a total processing time Or 9o~
Sensitometrlc results were obtalned and the most 5 slgniflcant of these are given below in Tables 1 and 2. : -' : -, . : ~
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The materials described in Examples 1, 2, 4, Ag ;~
B and C were radiographically exposed through standard blue emitting medium speed intensifying screens. All the ex-posed samples were processed in the rapid process described in Example 11. The materials of Examples 1, 2 and 4 exhibited a better definition over the materials of Examples A, B and C. Particularly, when compared to the material of Example A, said materials appeared to have greater speed and higher contrast of the yellow positive curve.
This fact resulted also in pure colors and very pleasant images. This was emphasiæed wlth the material of Example ;~
4g in which the yellow masked coupler was introduced in a silver halide emulsion of greater speed with respect to the emulsion used for the cyan forming layer.
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:~ -The materlals of Examples 2, 3, 4~ A and C were radiographlcally exposed through green emltting intensify- -ing screens. A11 the samples exposed were processed ln the rapid process described in Example 11. As already happened in the case of blue emitting intensifying screen exposure, the materials 2, 3 and especially 4, showed more pleasant images and purer colors, due to higher speed and greater contrast of the yellow positive curve with respect to material A.
Example 12 A color contast X-ray film was coated according to the scheme given in Example 8 (p-c-m-b-c'-p), wherein m) was a photosensitive emulsion layer as described in -,.~ .
Example 2-m, with a silver coating weight o~ 0.8 g/mC, ~ -15 The layer contained 0.47 g/m2 of a magenta masked coupler, ~
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C5 described before. (Such coupler was introduced into the layer by the solvent dispersion technique as described -~
! :
in Example l-m); c) was a photosensitive emulsion layer ., .
~` as described in Example 8-c; c') was a photosensitive emulsion layer as described in Example 8 c'; p) was a protective layer as described in Example l-p; b) was a ; colorless polyester base.
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~6'733~

ExamDle D
A color contast X-ray film was coated as described in Example A, with the dlfference that in this case the layer c~ contained 0.43 g/m2 of a magenta masked coupler (C5), instead of the yellow ma~ked coupler Cl.
The materials of Example 12 and Example D were : radiographically exposed and processed as described in ~ ;
Example ll to obtain the following results: ;

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Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A photographic element for use in radiography which includes a base and at least two silver halide emulsion layers, said element characterized by the fact that 1) silver halide emulsion layers in the element may contain as couplers only colorless cyan forming couplers and yellow colored couplers, 2) at least one emulsion layer reactively associated with said colorless cyan forming coupler so as to give a negative colored cyan image upon color development with p-phenylene diamine, 3) the other of said at least two emulsion layers being reactively associated with said yellow colored coupler so as to leave a yellow colored positive image and a magenta colored negative image upon color development with p-phenylene diamine.

2. Photographic element of claim 1 characterized by having the emulsion layer associated with the colored coupler directly coated on the base and the emulsion associated with the colorless coupler coated thereon.

3. Photographic element of claim 2 characterized by having coated on the other side of the base a further emulsion layer associated with a cyan forming colorless coupler.

4. Photographic element of claim 3 characterized by having coated between the base and the cyan-colorless-coupler-containing emulsion an emulsion layer associated with a colored coupler.

5. Photographic element of claim 1 characterized by the fact that the sensitivity of the emulsion associated with the colored coupler is higher than the sensitivity of the emulsion associated with the colorless coupler by at least 2 DIN.

6. Photographic element of claim 1 characterized by the fact that the emulsion associated with the colorless coupler includes a green sensitizing dye.

7. Photographic element of claim 6 characterized by the fact that the sensitizing dye is a symmetric carbo-cyanine including a 5-phenyl-benzoxazole group having an alkylsulfonic acid group attached to the nitrogen atom in 3-position thereof.

8. Photographic element of claim 1 characterized by the fact that the cyan forming coupler is a phenolic or naphtholic coupler.

9. Photographic element of claim 1 characterized by the fact that the magenta forming coupler is a pyrazolone coupler.

10. Photographic element of claim 1 characterized by having a masked naphtholic coupler as a magenta colored coupler capable of forming a cyan dye upon color development with p-phenylene diamine developers.

11. Photographic element of claim 1 characterized by having said colorless and colored couplers dispersed in their respective layers, dissolved in water-immiscible organic solvents.

12. Photographic element of claim 1 characterized by having a magenta acutance dye included in the emulsion layer coated directly on the base of the element itself.