CA1092134A - Methine 4-nitrobenzylidene dyes - Google Patents

Abstract

ABSTRACT

Certain members of the class of odd-numbered methine arylidene dye bases are round to be of use in thermally-developable photosensitive compositions and thermally-developable photosensitive elements containing such agents. These compounds are acutance agents which are relatively stable against photo-bleaching but under-go thermochemical bleaching on heating in silver salt-containing thermally-developable photosensitive compositions.

Description

Ji~,N. 912,873 ~@~

This invention relates to dry silve~ shee~ materials including as acutance agents methine p-nitro aryl~dene dyes having an odd number o~ methine groups which are further substituted on the aryl group attached ~o the methine chain by a substituent having a Hammett (para) sigma parameter from about 0.45 to about 0.63. These dry silver sheet material~
are valuable thermally developable photographic and reproduc-tion materials.

Description of the Prior Art Prior art teaches the use of acutance tand antihalat~on) agents in photographic ma~er~als to enhance the sharpness o~ images in photographic materials. They function by absorbing light which is reflected or refracted either at surrace interfaoes Or the photographic materials or in the body of the photographiG materials~
Unab~sorbed reflected or refracted light de~rades the image and thereby causes reduced resolutlon capability. Generally, an antihalation agent is coated on either or both sides o~ the support ~or the photographic material or between layers of photoemuls~on. Acutance agents are gener~lly incorporated into one or more of the photosen~itive layers.
Such acutance and antihalation agenks are discharged from wet-processed photographi~ materials in processing baths such as alkaline photographic developin~ baths.
One important method of reproduction o~ images is by thermal development. This method uses no processing liquids and there~ore precludes the use of antihalation or acutance agents which have been produred for use in wet-process photo~raphic materials. One such thermal develop-ment process ~s sometimes known as the "dry silver" process, Various aspects o~ the preparation and use o~ such materials are described in U.S. Patents 3,152,904 and 3,457,075.
Acutance ag~nts ror use in thermally-developable photographic materials have been described. In U~S. Patent 3,745,009 ~here are described acutance agents which are energy-decolor$zable and suitable ~or use ln thermally-developable photo~raphic materials but are, however, excessively sensitive to heat during production and coating and may decompose prematurely due to ambient heat.
In U.S. Patent 3,769,019 (3M) there are dlsclosed acutance agents which are thermally-decolorizable protonic d,yes although color may return spontaneously a~ter a period o~ time.
In British Patenk 1,399,751, correspondin~ al90 ~o DOS 2,242,761 and U.S. Paten$s 33984~248, 3,9~8,154 and 3,988,156, there are disclosed thermally stable, photo-bleachable o-nitro-substituted aryliden~ dyesturfs o~ the general ~ormula z~
R-N~L~ ~ =CH~CH-CH ~ Y

2 wherein k - 0~ 1 or 2; m = 0 or 1; L is a methine or su~stituted methine group; R is an alkyl, substituted alkyl, alkenyl, aryl or substltuted aryi group; Y repr~sents the atoms nece~sary to complete mono- or polycyclic aryl group which may be ~urther substituted; and Z`represents the atoms necessary to complete a mono- or polycycllc heterocyclic nucleus which may be substituted, the heterocyclic ring con~aining the nitrogen atom ~hown being 5 or 6 membered.
These dyestuf~s may be lncorporated ln heat d~velopable , -2-~3;2~

photographlc elements as part of antihalation layer. Such elemenks may be exposed to a light pattern, thermally developed to provide a sharp image in the element, and then the ele-ment fully exposed to light to decolorize the antihalation compounds. Alternatively (U.SO 39984,248, Column 12, line 27 f~., U.S. 3,988,154, Column 12, line 30 ~r., u.s. 3,988,156, Column 12, line 41 ~f. 3 DOS, page 21, line 8 ~), the com-pounds may be incorporaSed as desensitiz~rs in photosensi-tive compositions for wet processing.
~t is an ob~ect and aim of this invention to provide acutance agents ~or use in dry procossing silver reproduction materials and particularly acutance agents which do not tend to desensitize ~he photosensitive compounds in said reproduction materials. A further ob~ect o~ the ~nvenSion is to produce acutance agents which bleach thermally under dry pr~cessing conditlonsO Other alms and ob~ects will become apparent hereinelsewhere.
In accordance with these and other alms and obJects of the inventlon, there are provided acutance agents ~or use in thermally developable, photosensltive compositions. These agents are relatively stable against photobleaching but undergo bleaching on heating in silver salt-con~aining thermally-developable photosensitive compositions. Furthermore, the acutance agen~s of the invention do not desensitize thermally~developable photosensitive compositions in the 350 to 450 nm. range of the spectrum. There are also provided storage-~Sable, thermally developable, photosensitive compositions containing su~h acutance agents.

The present invention provides a me~hine arylidene dye base represented by t~e ~ormula ~ Z~ R2 R3 R -N~ CH=CH~ C=CH~ CH=C}~ ~ ~ T2 T

wherein: Z represents the atoms necessary to complete a mono- or polycyclic dihydroheterocyclic nucleus having 5 to 6 atoms in the ring including ~he N of the formula; Rl is a lower alkyl group; m = O or l; k = O, 1 or 2;
Tl is CF3 or CN; T2 is NO2; and R2 and R3 are hydrogen or together con-stitute a condensed carbocyclic aromatic ring.
The term para as used herein refers to the Hammett (para) sigma parameter, sometimes herein referred to as Hammett value, as defined by Shepard, J. Am. Chem. Soc., Vol. ~5, pg. 1314 et seq. ~1963).
It will be seen that the acutance agents invention are similar formally in many respects to those described in British 1,399,751 and DOS
2`:~242,761 and are obtained by replacing o-nitro-substituent by electron withdrawing groups having lower Hammett para sigma, i.e., r ~J, ~ 4 -(~para) values; of from about 0.45 to about 0.63.
The Hammett para sigma parameter of the nitro group is much higher, 0.778, and it is considered surpri~ing that a much better balance of thermal and photosensitive properties can be obtained together with substantially complete loss of desensitizin~ properties by such a relati~ely simple ~ormal change in structure. The presence o~ nitro groups in the 4-position is, however, not detrimental to the desired properties.
It is ~ound that suitable T~ groups are aprot1c electron withdrawing groups having a apara value of 0.45 to 0.63, CF3 (~para ~ 0 55) and CN (~para ' 0.63). Such values are readily ascer~ained by reference to report~d tables, ~or example, in Shepard, supra.
Groups having a ~para value less than about 0O45 become increasingly resistant to thermal decolorization and groups have a ~para value above about 0~63 become increasingly more light unstable.
The acutance agents of Formula I are of the class o~ odd-numbered arylidene dye bases. The preparation of the acutance agents is by methods similar to the generally known methods for preparakion o~ odd-number~d methine cyanine dye bases such as are described in, among other re~erences, Chapter XI, Compounds by Hamer~ Interscience Publishers (1964).
The monomethine dye baæes, i.e. dye bases where k of Formula I above is zero, can be prepared by condenæation in the presence of an ac~d acceptor, e.g., tertiary amine, Or a halogenated aromatic compound of the rormula:

2.1L~

R2~R3 Y~ T~ II
T ~
wherein R29 R3, Tl and TZ are de~ined a~ above, and Y is ~luorine, chlorine or bromine with a heterocyclic quaternary ammonium compound of the ~ormula:
z ~
R~ CH-CH ~-CH3 ~ III
wherein Rl, Z and m are de~ined above, and X is an anion such as; for example, a halogen ion, a p-toluenesul~onate ion, a rluorosul~o~ate ion or the like. &enerally, the condensation is carried out in an aprotic solvent such as, for example, acetonitrile, benzene or dlmethyl~ormamide.
Reaction conditions may be ~rom about 50-150~C ~or 1 to 3 hours, or as little as a few minutes when unwanted side reactions may occur. The produ¢t may be isolated by well known procedures such as crystalllzation or removal of sol~entO
The monomethine dye bases can be prepared by reac~ion in the presence of an acid acoeptor o~ quaternized heterocyclic compounds having a phenyl- or alkyl-thio substituent in place of the methyl, i.e., Or the structure:

__ z ~
R~ CH-CH~=mC-SRs IV
here Rs is phenyl or alkyl of 1-4 carbon atoms~ with aromat~c compounds of the ~ormula:
R2 R~
H3C ~ T~ V

wherein R~; R~, T~ and T are de~ined as above.

The trlmethine dye bases, i.e. those dye bases where k-l in Formula I above, can be prepared by reaction of a heterocyclic guaternary ammonium compound, e.g.j of Formula III above, with diphenyl~ormamidine or an equimolar mixture o~ diphenylformamldine and triethylorthoformate to give the corresponding ~-anilinovinyl derivative:
z ~
R'-N~CH-CH ~mC-CH=CH-NH ~ ~ VI

where Rl, Z, L, X and m are de~ined above. The ~-anilinovinyl derivatives are then caused to condense with an aromatic compound such as the aromatlc compounds of Formula V to give the trimethine dye bases. Reaction conditions are similar to those ued for the preparation of the monometh$ne dye bases.
The pentamethine dye bases can be prepared in a manner similar to that used ~or the preparation of the trimethine dye bases using ~-an~linoacrolein anil hydrocloride in place o~ diphenylformamldine to give the corresponding ~-anilinobutadienyl derivative z ~
R~ CM-CH~C-CH~CH-CH-CH-NH-CcH5 ~ VII
., ~ .
wherein Rl~ Z, X and m are as de~ined above. The compo~nd of Formula VII is then condensed, under the conditions used for reaction o~ Compound III, with an aromatic compound o~ Formula V ko yield the pentamethine dye base.
Examples of acutance agents o~ Formula I
include the follow~ng compounds.

~Z~14 Compound 1. 4-(2-cyano-4-nitrobenzylidene)-1-methyl-1~4-di-hydropyridine 2. 4-(2-tr~fluoromethyl 4-nitrobenzylidene)-1-methyl-1,4-dlhydropyridine

3. 4-(2-cyano-4-nitrobenzylidene)-1-methyl-1,4-di-hydroquinoline

4- 4-t2-tri~luoromethyl-4-nitrobenæylidene)-l~methyl-1,4-dihydroquinoline

5. 2-(2-cyano-4--nitrobenzylidene)-1-methyl-19 2-di-hydroquinoline

6. 2-t2-cyano-4-nitrobenzylldene)-1-ethyl-1,2-di-hydroquinoline

7. 2-t2-cyano-4-nitrobenzylidene)-1-methyl-6-ethoxy-1,4-dihydroquinoline

8. 2-(2-cyano~4-n~troben~ylidene)~l ethylbenzoth~azoline

9. 4-t2-cYano-4-nitrobenzylidene)-l-t2--nitrobenzy~ 4 dihydropyridine

10. 2-t2,4-dicyanobenzylidene)-1-ethylbenzoxazoline

11. 2-(2-cyano-4-nitrobenzylidene) l-ethylbenzoxazoline

12. 2-~3-(2-cyano-4-nitrophenyl)allylidene]-1-methyl-1~2-dihydropyridine 130 2-C3-(2 cyano-4-nitrophenyl)allylidene]-1-methyl-1,2-dihydroquinoline 14. 2-~3-t2-cyano-4-nitrophenyl)allylidene] 1-ethyl-1,2-- dihydroquinoline 15. 4-~3-(2-cyano-4-nitrophenyl)allylideneJ-l-methyl~
1,2-dihydroquinoline 16. 2-~3-(2-cyano-4-nitrophenyl)allylidene~-1-ethyl-benzothiazoline Com~
17~ 2- r 3-(2,4-di¢yanonaphthyl-l)allylidene]-1,3-dimethyl-5-ethoxybenzimidazoline 18. 2-[5-t2-cyano-4-nitrophenyl)pentadiene-2,4-ylidene]-1-methyl-1,2-dihydropyridine 19. 2-C5-(2-cyano-4-nl'crophenyl)pentadien-2,4-ylidene~-l-ethyl-5-methylbenzoth$azoline 20. 2-C5-(2-cyano-4-nitrophenyl)pentadien-2,4-ylidene]
l-methyl-1~2-dihydroquinol~ne 1021. 4-~2-cyano- 4-nitro~ en zylidene)l-phenyl-1,4-dlhydro-pyridine 22. 2-(2-cyano-4-nitrobenzylidene)-1-phenylbenzoxazoline 23. 4-(2-cyano-4-nitrobenzylidene)-1-(4-methoxyphenyl)-1,4-dihydropyridine 1524. 4-~3~ cyano-4-nitrophenyl)allylidene]-1-(2-ethoxyethyl)-1,4-dihydropyridine ~5. 4~~3-(2-cyano-4-nitrophenyl)allylidene~-1-allyl-1,4-dihydropyrldine 26. 2-(2-cyano 4-nitrobenzylidene)-1-ethyl-6-methoxy-1,2-dihydroqulnoline The acutance agents o~ Formula I are use~ul in thermally-developable photosensitive co~posikions such as those described in U.S. Patents 3,457,075, 3,589,901 and 3,589,0g3. They are optimally used in concentrations of about 0.01 to about 0.1 par~s by weigh~ (30 to 300 m~cromoles) of acutance agent having a molecular weight of about 300 per 100 parts by weight o~ photosensitive dispersion. The use o~
more acutance agents in coating an emulslon produces an increase in fog le~el and increase in residual stain.
Lesser amounts are generally ~ound to be ine~fective.

Com~ound 17. 2-[3~(2,4-dicyanonaphthyl-l)allylidene]-1,3-dimethyl-5-ethoxybenzimidazoline 18. 2-C5-(2-cyano-4-nitrophenyl)pentadiene-2,4-ylidene]-1-methyl-1,2-dihydropyridine 19. 2-[5-(2-cyano-4-nitrophenyl)pentadien-2,4-ylldene~-l-ethyl-5-methyPben~oth~azol$ne 20. 2-C5-(2-cyano-4-nitrophenyl)pen~adien-2~4-ylidene~-l-methyl-1~2-dihydroquinoline 10 21. 4-(2-cyano-4-nitrobenzylidene) 1-phenyl-1,4-dihydro-pyridine 22. 2-(2-cyano-4-nitrobenzylidene)~l-phenylbenzoxazoline 23. 4-(2-cyano-4-nitrobenzylidene)-1-(4-methoxyphenyl)-1,4-dlhydropyridine 15 24. 4-c3-(2-cYano~4wnitrophenyl~a:Llylidene]-l-(2 ethoxyethyl)-1,4-dihydropyridine 25. 4-r3-(2 cyano-4-nitrophenyl)allylidene]-1-allyl-1,4-dihydropyridine 26. 2-(2-cyano-4-nitrobenzylidene)-l~ethyl-6-methoxy-1,2-dihydroquinol1ne The acutance agents o~ Formula I are useful in thermally-developable photosensitive compositions such as those described in U.S. Patents 3,457,075, 3,589,901 and . 3,589,093. They are optimally used in concentrations of about 0.01 to about 0.1 parts by weight (30 to 300 micromoles) o~ acutance agent having a molecular weight o~ about 300 per 100 parts by weight o~ photosensitive dispersion, The use o~
more acutance agents in coating an emulslon produces an increase in fog level and increase in residual stain.
Lesser amounts are generally ~ound to b~ ineffective.

_g_ Prer~rably about OfO2 to 0.05 parts and more (50 to 150 micromoles) pre~erably about 0.02 to Q.035 parts (50 to 120 micromoles) o~ acutance agent having a molecular weight of about 300 is used per 100 parts o~ photosensitive dispersion.
Amounts expressed as micromoles are applicable to acutance agents o~ ~he invention in general.
The invention is now further explained ~y examples showing the preparation and use o~ acutance agents of Formula I. It will be recognized that with complex molecules melting points may be a~fected by rate of heating, atmosphere and also crystalline ~orms as well as tendency o~ the compounds to decompose.

Preparation o~ 4-~2-cyano-4-nitrobenzylidene)-l~methyl-1,4-di~ydroquinoline.
Lepidine methyl fluorosulronat;e ~51.4 g., 0.2 moles and 2-chloro-5-nitrobenzonitrile (36.5 g., 0.2 moles) were d~ssolved in 350 ml. o~ dry acetonitrll~. The solution was hea~ed to reflux and, whlle stirring v~orously, trlethyl-amine (40.4 g., 0.4 moles) was added during about ~our minukes.
An intense deep purple color developed immediately. ~he mixture was held at rerlux for about on~ hour and cooled in an ice water bath. The green iridescent crystalline product was oollected, washed successively with a small amount o~
acetonitrile, water, and diethyl ether, and drled at 60C.
There was obtained 35.8 g. (59% of theory) Or product hav~ng a melting po~nt Or 220-222C, recrystallized from acetonitrile for analysis:
Calcd. for C~uHl3N~o2: %C, 71.3; %H, 4.32; ~N, 13.8 Found: %C9 71.3; gH, ~.3; %N, 14.2 l~Z~

1,4-dih~dropyridine.
The procedure of Example 1 was repeated using an equlvalen~, i.e. equimolar, amount o~ 1 (2-nitrobenzyl)-4-methylpyridinium chloride in place o~ lepidlne methyl ~luorosulfonate. A deep blue dye base h~ving m.p. 193-201C.
was obtalned in 47% o~ theory.
Calcd. ror C20H~N404: %C, 64.2; %H, 3.77; %N1 15.0 Found: %C, 63.6; %H, 3.~0; %N, 15.3 IR spectra were consistent with the structur~ of Compound 9.
NMR peaks (~ units in parts per million are found at 8.30, .20, 7.6-8.1, 7.49, 6.90, 5.70, and 5.47.

Preparation of ll-(2-trir~ ~ trobenzylidene)-l-methyl-l ? 4-dihydroquinoline.
The procedure o~ Example 1 was repeated using an equivalent amount o~ 2-chloro-5-nitrobenzotri~luorlde in place of 2-chloro-5-nitrobenzonitrile. The product obtained had a melt~ng point of 173-5C. On recrystallization ~rom carbon tetrachloride and then methanol, a deep purple crystalline produc~ was obtalned.
Calcd. for CldHl-dF~N20a: %C, 62.4; %H, 3.78; gN, 8.08; %F, 16.46 Found: %C, 62.4; %H, 3.7; %N, 8.8; %F, 16.3 IR spectra were consistent with the structure o~ Compound 4.
NMR peaks (expressed in ~ units in parts per million are found at 8.33, 8.29, 8.02~ 7.90~ 7.1-7.7, 6.66, 6.39 and 3,60.

~ ~z ~3~

Preparation o~ ?-E3-(2-cYa o-4-nitrophenyl)allylid-ene~
ethyl-l z-~b~e5YYn99Ine.
The condensa~ion of 4.02 g. (0.01 mole) of 2_(2-anilinovinyl)-l-ethylquinollnium iodide (prepared as described in British Patent 344,40~ m.p. 263-5C (dec.)) with 2-cyano-4-nitrotoluene (1.67 g., 0.01 mole) was e~fected in 15 ml.
o~ dimethylformamide containing 2 ml. of acetlc anhydrlde by heating the react~n mixture to re~lux, addin~ 1.01 g.
(O.01 mole) Or triethylamlne, heatin~ at re~lux ~or 1 to 2 minutes and cooling rapidly, The precipitate was collected, washed successlvely with dimethyl~ormamide 9 water and ether and ~hen dried to y~eld 47% of theory o~ blue dye base m.p. 250-252C.
Calcd. ~or C~IHl7N302: %C, 73.4, %H, 4.98; %N, 12.23 ~ound: %C, 72.4; %H, 4.9; %N, 12.2 IR spectrum was consistent with the structure o~ Compound 14 but also ~ndicated the sample to be contaminated with dimethylformamide.
When 2-(2-anilinovinyl)-1-ethylquinolinium iodide used above is replaced by 4-(4-anilinobutadien-1,3-yl)-1-methyl~uinolinium iodide there is obtained 4-C5-(2-cYano-4-nitrophenyl)pen~adien-2,4-ylidene]-1-methyl-1,4-dihydropyridine.
This arylidene dye base is chloro~orm is bright gre~nish.
blue having an absorption maximum o~ 645 to 660 nm.
The procedure of this example was repeated usin~ equivalent quantities o~ the necessary quaternary compounds and 2-cyano-4-nltrotoluene to give the following compounds.

Table 1 Structure o~ Dye Com~ounds . Meltin~ Point C

13 240-~ (dec.)

14 250-2 235-40 (dec.) 16 221-2 dec. (235) EXAM
A thermally de-velopable photosen~itlve composition was prepared by blending in a m~xing apparatus 5 ~. o~ poly-vinyl butyral and 500 æ. o~ a dispersion o~ 13.8 ~arts by weight silver behenate in 86.2 part~ by weight o~ a mixture in parts b~ volume Or 68 parts methylethyl ketone, 25 parts toluene, and 7 parts methylisobutyl ke~one. After the mixture had beoome homogeneous, it was placed under "safe" light condi~ions as known to those of skill in the art and 20 ml.
o~ a solution o~ lM hydrobromlc acid ln methanol (48g HBr diluted with methanol) was added dropwise to the vl~orously 20 stirring mixture. After stirring ~or 20 minutes at 25C, 2.5 ml. o~ 0.15M mercuric bromide in methanol was added followed by 25 g. polyvinyl butyral and stirring was continued for 10 minutes, avoiding heat build-up as the v~scosity o~ the mixture increased. There then was added 10 mg. o~
25 the optlcal sensitizer ~dispersed ln 10 ml. of methanol)~
3-ethyl-5[(1-ethyl-i,2-dihydroquinolinylidene-2~ethylidene]-2-~3-carboxymekhyl-4-oxo-2-thio-5 thiazolidinylidene)-4-~hiazolidone available from Example 2 oP U.S. Patent 3,719,495.
Okher sensitizers can be used a~ desired. The mixture was 3 stirred 20 minutes and 100 g. was withdrawn ~or preparation 2~1~3~

of a control thermally-developable material (designated A).
To the remainder was added 150 mg. o~ the acutance dye base of Example 1 and the composition (designated B) containing acutance a~ent was stirred for another 30 minutes.
Bo~h compositions, A and B, were knife coated at 125 microns onto polyester film and dried 5 minutes at 90C
in a forced dra~t oven. Both dried films were ~hen topcoated at 75 microns with a dèveloper layer composition of 81 parts methylethyl ketone, 5 parts methanol, 1.5 parts phthalazinone, 7.5 parts o~ bis(2,2'-dihydroxy-3,3',5~5'-ketramethyldiphenyl)-(2,4,4-trimethylpentyl)methane (available as NONOX WSO from I.C.~., Lkd.) and 5 parts of vinyl chloride/v~nyl acetate copolymer (available as VYNS rrom Union Carbide~. Films of this type are of relatively high contrast values. The topcoated ~ilms were dr~ed five mlnutes at 90C.
Portions of each of the ~ilms 9 Film A (the control not containing acutance agent) and Film B (containing acutance agent), were contact exposed through a mask overlaid with a 0~4 continuous density wedge to tungstlen illumination modulated by a 560 nm. narrow band ~llter. The mask had a rectangular aper~ure with a width of about 5.5 mm. and a length of 120 mm. The coated films were then dev~oped by heating for 16 seconds at 125C and the width of the image that formed measured in millimeters (believed to be - 0.01 mm) at optlcal densities of 2 and 3 tabulated in Table 2. The comparative values obtain~d are indicative of the effective-ness of acutance agents.

Table 2 O~tical Densit~ - 2.0 Width of Width o~ Peraent M~ . Image Flare Film A 5.544 mm. 5.557 mm. 0.23 Film B 5.546 mm. 5~546 mm. 0.O
O~ cal Densit~ ~ 3.0 _ Width of Width o~ Percent Mask_Aperture ~3~ Flare Film A 50660 mm. 6.737 mm. 19.0 Film B 5.664 mm. 5.664 mm. 0.O

From the above daka, it is apparent that incorporat~on of t~e acutance agent o~ the inventlon eliminated lmage ~lare whlch without the agent would amoun~ to 0.23% o~ the image width at a densi~y Or 2~0 and 1~% at an lmage density o~ 3Ø

A series Or low contrast filrns are pr2pared both wlth and without an extensive æeries o~ the acutance dyes enumerated above. This procedure plac~d the developer and toner ln the lma~e layer rather than in a separate layer as in Example 6.
A suitable vessel is charged with 750 g of a dispersion as in Exam~le 6 of sllver behenate, 45 g methyl ethyl ketone and 0.75 g polyvinylbutyral and the su~penslon mixed at about 22 for 15 minutes at which time a mlxture of 36 ml o~ 1.0 M HBr in methanol and 9.5 ml of 0.1 M HI
in methanol is added and stirr~ng is continued ~or 1 hour.
To the mixture is added 5.18 ml Or 0.5 M Hg Br2 in methanol ~ollowed by a further 85 g Or polyvinylbutyral and stirring is con~inued ~or 20 minutes. A dispersion of 0.022 ~ o~ the same sensitizer used in Example 6 in 20 ml o~ methyl a3~

ethylketone is added to the total mixture which is then stlrred ror 75 minutes before adding 24 g of the "NONOX WS0" used in Example 6 and 7.5 g o~ phthalazinone and stirring is continued for 10 minutes to provide the basic emulsion.
Several such batches are used in subsequent tests. Controls are prepared containing 3 ml. chloroform but no acutance dye and coated at a wet level o~ 125~ on 75~ polyester ~ilm and after drying 3 0 5 minutes at 90C overcoated with a non-functlonal protective wet coat of 75~ vinyl acetate/vinyl chloride (39%) in 80:20 methyl ethyl ketone: methanol dried in the same wa~. The controls exposed are at s~veral dirrerent wavelengths o~ light through a mask as described in Example 6 developed 15 seconds at 127C and measured at density o~ 3.0 for mask aperture and image width in millimeters (believed accurate to about 0.01 mm~ as shown in Table 3.

Table 3 Width o~ Width o~ Percent (nm) Mask Aperture ~E~ __ Flare 510 5 D 538 7.027 27 560 5.559 7 9 26 620 5.550 6.766 2~
6~0 5.562 7.021 26 Samples for testing acutance dyes are prepared by dispersin~ 40 micromoles of the dye to be tested in 3 ml chloroform in a vessel and adding 50 g aliquots of the emulsion prepared above. The vessels are shaken well three times at intervals Or 10 minutes and coated as described above for the controls. Exposure is er~ected at varlous wavelengths as controlled by ~ilters usin~ masks as above.
Table 4 shows the acutance dyes by re~erence to the figures ~ 3 ~

toge~her with molecular weight, weight o~ dyestu~f (mgm per aliquot), wavelength, mask width (mm), image width at D - 3.0 and percent flare.

Tabl~ 4 Acutance Weight Width Width Dye Mole¢ular o~ A o~ Mask o~ P~rcent F~æure Wei~ht~ Q nm~ Aperture Image Flare 1 253 10.2 560 5.549 6.609 19 2 346 13.9 540 5.567 6.128 10 3 303 12.2 560 5.542 6.214 12 303 12.2 540 5.569 6.043 ~.5 6 317 12.7 540 ~.569 6.190 11 7 347 13.9 560 5.558 5.989 7.8 9 347 15.0 540 5.567 6.563 18 12 ~77 11.1 640 5.570 6.749 21 14 343 13.8 640 l~.550 6.028 8~6 14 343 13.8 620 '~5~ 5.935 7.0 329 13.2 640 5.570 6.~88 9.3 16 349 1~ 620 5.548 6.208 12 ~3

Claims (3)

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

1. A methine arylidene dye base represented by the formula wherein:
Z represents the atoms necessary to complete a mono- or polycyclic dihydroheterocyclic nucleus having 5 to 6 atoms in the ring including the N of the formula;
R1 is a lower alkyl group;
m = 0 or 1;
k = 0, 1 or 2;
T1 is CF3 or CN;
T2 is NO2 ; and R2 and R3 are hydrogen or together constitute a condensed carbocyclic aromatic ring.

2. A methine arylidene dye base according to claim 1 characterized by being an acutance agent wherein Z is a member of the group;
-CH=CH-, -CH=CH-CH=CH-, or where R4 is H, alkyl of 1-2 carbon atoms or alkoxy or 1-2 carbon atoms.

3. An acutance agent according to claim 1 or 2 wherein R1 is alkyl of 1 to 4 carbon atoms.