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Publication numberUS3667954 A
Publication typeGrant
Publication dateJun 6, 1972
Filing dateApr 22, 1970
Priority dateApr 21, 1969
Publication numberUS 3667954 A, US 3667954A, US-A-3667954, US3667954 A, US3667954A
InventorsHashimoto Mitsuru, Itano Kohei, Nakano Masashi
Original AssigneeKeuffel & Esser Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Tribromomethyl sulfonyl pyridazine or phthalazine photoactivators
US 3667954 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

United States Patent US. C]. 96-90 6 Claims ABSTRACT on THE DISCLOSURE A light-sensitive printing material comprising a photo- 3,667,954 Patented June 6, 1972 carbons have been extremely undesirable, like the abovementioned carbon tetrabromide.

DESCRIPTION The present invention is characterized by using as photoactivators free from such drawbacks as mentioned above activator capable of forming a free radical by action of light and a discoloring agent showing a visible color change by action of said free radical, characterized by using as the photo-activator a pyridazine or phthalazine derivative which is represented by the general formula R3 R3 R: l R2 wherein R R and R are individually a hydrogen atom, a hydroxy group, a lower alkyl group, an alkylsulfonyl group, an alkoxy group or an alkoxycarbonyl group, provided that R and R may form a benzene ring and, in the case of an N-oxide type compound, R may be a tribromomethyl sulfonyl group.

BACKGROUND OF THE INVENTION This invention relates to a light-sensitive printing material incorporated with a photo-activator capable of forming a free radical by action of light and a discoloring p 7 carbon tetrabromide. Accordingly, light-sensitive printing tribromomethyl sulfone derivatives having pyridazine or phthalazine nuclei which are represented by the general formula wherein R R and R are individually a hydrogen atom, a hydroxy group, a lower alkyl group, an alkylsulfonyl group, an alkoxy group or an alkoxycarbonyl group, provided that R and R may form a benzene ring and, in the case of an N-oxide type compound, R may be a tribromomethyl sulfonyl group.

All these compounds empolyed in the present invention are crystalline compounds and are not volatile unlike materials prepared by the use of said compounds do not suffer from escape of the photo-activators and are quite stable. Further, the said compounds are non-toxic and odorless, and the vapors thereof are not lachrymatory, so

- that the handling of the compounds is extremely easy and agent showing a visible color change by action of said bromide and aroyl trihalogenated hydrocarbons have been i recommended as efiective photo-activators.

However, carbon tetrabromide is extremely. high in volatility and easily escapes from the light-sensitive printing materials. Accordingly, printing materials prepared by the use thereof have had such serious drawbacks that they are markedly low in stability and becomes unusable in a few days after preparation. Further, it has been known that the vapor of carbon tetrabromide is quite toxic and the toxicity thereof is about 1 ppm. in 3 hours. In handling carbon tetrabromide, therefore, a special attention has been required to be paid so as not to inhale the vapor thereof. Thus, carbon tetrabromide has been extremely undesirable, in practice.

On the other hand, aroyl trihalogenated hydrocarbons are less volatile but are strongly stimulative so that in thermally fixing light-sensitive materials containing said hydrocarbons or in'handling the said hydrocarbons, the skin or 'rnuscosa should have previously been covered with a rubber product or the like protector, e.g. an anti-gas mask or rubber gloves. Thus, aroyl trihalogenated hydrosafe and any special consideration such as aeration or the like is not required to be paid thereto.

Moreover, light-sensitive printing materials in accordance with the present invention have such advantages over those of the prior art that they are higher in light-sensitivity and excellent in gradation and, even when same discoloring agents have been used, the resulting colors are brillant and pure.

" Typical examples of the compounds represented by the aforesaid general formula are as shown below, but it is needless to say that these are examples and do not limit the scope of the compounds usable in the present inven tion.

( 1) 3 (a,a,a-tribromomethylsulfonyl)-6-hydroxypyri dazine Melting point, C.

1 3-(a,a,a-tribromomethylsulfonyl)-6- 267-268 hydroxypyridazine.

@- s 0,0 Bra N no (2) 3-(a,a,a-tribromomethylsulfony1)-6- 200 methoxypyridazine-Z-oxide.

s 02cm N 0 (3) 3-(a,o: a-tribromomethylsnlionyl)-6- 200 methylsulfonyl-pyridazine.

TABLE-Continued Melting point, C.

(bl 4. 'n-Propyl-3-(a,a,a-tribromomethylsulionyl)-pyridazine-6-carboxylate.

- myrsowoo- IN i (5) 3-(a,a,a-tribromomethylsull'onyl)-6- i r methylpyridazine.

(6) 3-(a,a,oz-tribromomethylsulfonyl)-fimethoxypyridazine.

4-(a,oz a-tribromomethylsulfonyl)3,6-dimetlloxypyridazine-Loxide -OCH;

4- (41,0: ,a-tribromometh ylsulfonyl) -3- methoxy-fi-chloropyridazine-l-oxide.


SiOaCBra N Ck N// l-(a,n:,a-tribromomethylsulfonyl)- phthalazine.

SO CBra l-(41,0:,a-tribromomethylsulfouyl)-4- methylphthalazine.

SOgGBrs SOaCBra l OCH;

i Decomposition.

Generally, these compounds can be easily prepared by reacting a corresponding thioglycolic acid derivative in a. sodium hypobromide solution at a temperature of 20? to 45 C. v

When exposed to light, particularly ultraviolet light,

"theabove=mentionedcompounds fornractive free halogen groups which give a visible color change to discoloring agents. As discoloring agents showing a visible color change by action of free radicals formed from photoactivators, thereare two kinds, i.e. those which originally are colorless but can be brought into ancollored state by action of the free radicals and those which originally havean inherent color but the color can be changed to another color or can be decolored to colorless. Lightsens'itive materials prepared by use of the former discoloring agents which are originally colorless but form color by action of light, are used as so-called nega-posi type printing materials, while those prepared by use of the latter discoloring agents are used as posi-posi type printing materials. V v

Typical discoloring agents belonging to the former type are arylamines. Arylamines suitable for this purpose include not only mere arylamines such as primary and secondary arornatic amines but also so-called leuco dyes which are dyes having amino groups or reduced amino groups. 7

Examples of such arylamines are:

diphenylamine, dibenzylaniline, tn'phenylamine, N,N-diethy1aniline, N,N-dimetliylaniline, N-hydroxyethybN ethylaniline, N,N-die'tha'nolaniline, o-arninodiphenylamine, p-hydroxydiphenylamine, N-methyldiphenylamine, p-benzoyloxydiphenylamine, p-methoxydipheny1amine, N-vinylcarbazole, 2-phenylindolizine,

v N,N-diphenyl-p-phenylenediamine,

N',Ndihydroxyethyl-rn toluidine, N,N-dihydroxyethyLo-toluidine, d-phenylnaphthylamine, fi phenylnaphthylamine, 3-aminoquinoline," indolef salicylidene-p-toluidine, salicy'lidene-p-chloroaniline, cyanomethylene 4-quinolyl-2m aphthalene,

a 3-phenylindole,

" 6' a-diethylaminopyridine;

p;p'-methylenebis-aniline, p,p'-methylenebis(N,N-dimethylaniline), p,p '-pentylidenebis (N,N-dimethylaniline) p,p',p"-methylidynetris (N,N-dimethylaniline) p,p'-hydroxymethylenebis(N,N-diethylaniline) p,p'- (dimethylamino) -diphenylam'ine, p,p'-aminomethylenebis(N,N-dimethylaniline) p',p '-(o chloropentylidene)-bis(N,N-dimethylaniline), p,p'- (p"-aminopentylidene)bis-aniline, p,p-(p"-amino-m" methylpentylidene)-bis(N-phenylaniline),- ,1 v i 1, l-bis (p-dimethylaminophenol) -p'-dimetliylarninophthalein,

3,6-bis(diethylamino):spirotphthalein-l ,9'-xarithene),

3,6-bis(diethylamino)-9-(p dimethylaminophenonxanthene, t t o Lil-bis(p-dimethylarninophenol)-p-dimethylaminophthalan, i, r I 7 v l,l-bis(p-arninophenol)-p' aminopheriolphthalan, lO-benzoyl-SJ-di(p-dimethylamino)-pheriothiazine,

and 3 diethylamino-7 aminophenoxazine. 1

In addition to such relatively low molecular weight amines as mentioned above, there may also be used elfectively/forthis-purpose high molecular weight aryl amines such as aip'olymer of N-acryloyloxyethyl-Nethylaniline, a copolymer of N-acryloyloxyethyl-N-ethylaniline and maleic anhydride, and a condensation product of a copolymer of vinyl methyl ether and maleic anhydride (which copolymer is a commercially available product having the trade name of Gantredt) with N-hydroxy-N- ethylaniline.

As discoloring agents effective for use in nega-posi type printing materials, there may be used, in addition to those mentioned above, quaternary salts and N-oxide compounds of nitrogen-containing heterocyclic compounds, and these N-oxide compounds are effective also as the sensitizers mentioned later. Examples of the quaternary salts are Z-methylbenzothiazole-methyl iodide, Z-methylbenzothiazole-ethyl bromide, quinaldine-methyl iodide, 2,5 dimethylbenzothiazole methyl p toluenesulfonate, 2,5,6-trimethylbenzothiazole-butyl iodide, etc., and examples of the N-oxide compounds are 4-methylquinoline-N- oxide, 2,2'-dipyridine-N-oxide disulfide, 4-methylpyridine- N-oxide, quinoline-N-oxide, etc. 7

Further, as the discoloring agents effective for use in posi-posi type printing materials which originally have an inherent color but the color is discolored or decolored by action of free radicals, there are various dyes of the diphenylmethane, triphenylmethane, thiazine, xanthene, anthraquinone, iminonaphthoquinone and azomethine types.

Examples of such dyes include: Auramine (C.I. 41000), Victoria Blue (C.I. 44045), Brilliant Lowdurine Blue R (CI. 42565 Benzoyl Methylene Blue, Cinnamoyl Methylene Blue, p-Anisoyl Methylene Blue (C.I. 51195),

Nile Blue A (C.I. 51180), Ephitenew Blue (C.I. 51185),

Rhodamine B (C.I. 45170), Rhodamine 3B (C.I. 45175), Rhodamine 126M (C.I. 45310), Sudan Brau G (C.I. 61525), Sudan Blue GN (C.I. 61520), Celliton Blue (C.I. 64500),

4-p-diethylaminophenylimino-naphthoquinone, 2-carboxyanilino-4-p-diethylaminophenylimino naphthoquinone, 2-carbostearylamino-4-p-dihydroxyethyl-aminophenylimino-naphthoquinone, p-methoxybenzoyl-p'-diethylamino-o'-methylphenylimino-acetanilide, cyano-p-diethylaminophenylimino-acetanilide, l-phenyl-3-methyl-4-p-diethylaminophenylimino-5- pyrazolone, and 1-fl-naphthyl-4-p-diethylaminophenylimino-5- pyrazolone.

The light-sensitive printing materials of the present invention are obtained by bringing the aforesaid photoactivator and discoloring agent into the'form of a solution together with a suitable high molecular binder having a film-forming ability, coating the solution on a support such as a paper or film base,,followed by drying. As the high molecular binders in the above case, there may be used various substances, e.g. cellulose derivatives such as acetyl cellulose, acetyl-butyril cellulose and ethyl cellulose, vinylic polymers or copolymers of vinyl chloride, vinylidene chloride, vinyl acetate, acrylates and styrol, and synthetic rubbers such as styrene-maleic anhydride copolymer, cyclic rubber, acrylic rubber and butadiene copolymer. I

When the light-sensitive printing material of the present invention is exposed to light, particularly ultraviolet light, the discoloring agent brings about a visible color change by action of a free radical formed from the photoactivator, thereby giving an image. This light-sensitivity to light can further be enhanced by addition of a suitable sensitizer. As such sensitizers, there are two kinds, those belonging to so-called color sensitizers which enhance the light-sensitivity by broadening the light-sensitive wavelength area of printing material to the area of visible light, and those belonging to true sensitizers which enhance the light-sensitivity regardless of the light-sensitive wave length area.

' As the sensitizers belonging to the former, there are effectively used acridine, cyanine, merocyanine, styryl and the like dyes and dye bases which have been used as sensitizing dyes in the prior art photography.

Examples of these include: Acridine Orange, Acridine Red, Rose Bengale, Methylene Blue, pinacyanol, pinakryptol yellow,





l- 3-ethyl-2- 3H) -benzothiazolidene) -4-b utylidenedibenzothiazolyl-methane,

( l-ethyl-4- 1H) -quinolidene) -2-benzothiazoly1- methane,

5 -2 S-ethylbenzoxazolidene) -ethylidene-2-phenylimide- 3-phenyl-4-keto-tetrahydrothiazole,

1,3-diethylthia-4'-carbocyanine iodide,

1,3'-dimethyloxa-2'-carbocyanine-p-toluenesulfonate, and

5- 1 -methyl-2-( 1H -quinolidene-2-butylidene-3- .ethyl-2-thio-2,4-oxazolidenedione.

As the true sensitizers belonging to the latter, there are effectively used the aforesaid heterocyclic N-oxides and such aldehydes and pyrazoline derivatives as exemplified below.

Examples of aldehydes include benzaldehyde, dimethylaminobenzaldehyde, o phthaldialdehyde, salicylaldehyde, thiosalicylaldehyde, anisaldehyde, vanillin, phenyl acetaldehyde, ascorbic acid, and benzaldehydecarboxylic acid, and examples of pyrazoline derivatives include 1,3-diphenyl-5-p methoxy-phenylpyrazoline, 1,3-diphenyl-5-p-dimethylaminophenylpyrazoline, 1-phenyl-3-diphenylyl-5-p-dimethylaminophenylpyrazoline and 1-phenyl-3-diphenylyl-5-p-chlorophenylpyrazoline.

' When these sensitizers are suitably used, the lightsensitivities of printing materials can be increased to 2 to 20 times.

' As components which are preferable to be used in combination with the sensitizers, there are color tonemodifiers.

The light-sensitive printing materials of the present invention are exposed and then fixed by treatment with a solvent or a reducing agent, whereby final images are obtained. However, when the present printing materials have previously been incorporated with certain additives and are then exposed, images markedly different in color tone can be obtained. For example, organic compounds having mercapto groups in the molecules, e.g. 4-phenylmerca'ptotetrazole, 2-methylmercaptobenzothiazole, thioglycolic acid anilide, thiourea, phenylthiourea and diphenylthiourea, are effective for browning the color tones of color images obtained from the arylamines and the photoactivators.

' The light-sensitive printing material of the present invention is obtained by dissolving the aforesaid various components in a binder solution and coating the resulting solution on a suitable support according to a known procedure. In this case, preferable quantitative proportions of the components are as follows:

Parts by weight Solvent 500-1000 Film-forming binder 1 10100 Photo-activator 1-50 Discoloring agent 10-100 Color tone modifier (optional) 1-10 Sensitizer (optional) l-5 Provided that the amount of the binder is at most 10% based on theweiglit of the solvent.

'As the support, there may be used any of papers, plastic film bases, glass plates and metal sheets. Gen- 7 erally, however, the use of photographic papers. and plastic-coated papers makes it possible to obtain high density, clear images with good resolution. Alternatively, the use of a photographic film gives a clear, transparent image.

The optimum thickness of the light-sensitive layer to be coated on the support is about 2 to 3 in general, though high sensitivity and density can 'be attained with increasing thickness of the light-sensitive layer.

When the present light-sensitive printing material obtained in the above manner is superposed on an original and then printed by application of light, a color is immediately formed or the dye is discolored or decolored to give a clear image. The present printing material has several to several ten times the sensitivity of a commercially available diazotype positive light-sensitive paper. If necessary, the printing material may be subjected to a suitable enlarging device to obtain an enlarged image. The image formed by printing is stable but is not storable in a bright place, unless the image is freed from the light-sensitivity of unexposed portion, and hence should be subjected to fixation. This fixation can be accomplished simply by treating the printed material with a suitable solvent to remove residual components or by reducing the active components with a suitable reducing agent, so that the material shows no activity to light any more.

In the solvent fixation, there is used a suitable solvent capable of dissolving off the photo-activator without dissolving a dye formed by exposure or the dye left undiscclored or un-decolored. For example, in the case of a nega-posi type light-sensitive printing material prepared by using the previously exemplified compound (1) as the photo-activator and diphenylamine as the discoloring agent, an equal amount mixture of ethyl acetate and cyclohexane was most preferable, and such a solvent as trichlene, methanol or acetone dissolved out the dye formed and was not usable. Thus, for the solvent fixation, it is essential that a suitable solvent should be selected according to the components of the printing material used.

Alternatively, a reducing agent solution, such as an aqueous solution of sodium sulfite, acid sodium sulfite or a ketone or aldehyde addition product thereof, or an acid solution of starmous chloride, is simply kiss-coated on the light-sensitive printing material after exposure, or the material is immersed in said solution, whereby a sufiiciently stable image storable in a bright place can be obtained with a treating time of about 0.5 to 2 minutes, like in the case of the solvent fixation.

The present invention is illustrated in detail below with reference to examples, but it is needless to say that the invention is not limited only to these examples but various modifications ar possible within the scope of the invention.

PREFERRED EMBODIMENTS Example 1 A photographic paper was subjected to surface treatment by application of 1l.5 g./mm. of polyvinyl alcohol having a polymerization degree of about 600. On this photographic paper was coated under a yellow safety lamp 20 cc./mm. of a light-sensitive liquid of the composition shown below, followed by drying to prepare a light-sensitive printing material.

3-(a,a,a-tribromomethylsulfonyl)-6-methylpyridizine-: S g Diphenylamine: 10 g.

Acetyl'cellulose: 10 g.

Acetone: 30 cc.

Benzene: 70 cc.

The thus prepared printing material was placed on a photographic negative and exposed for 5 seconds to an 800 W. mercury lamp at a distance of 5 cm., whereby a deep blue positive image on a white background was immediately obtained. Subsequently, the printing mate- 8 rial bearing the said image was subjected to solvent fixation by immersing for 1 minute in an equal amount mix? ture of ethyl acetate and cyclohexane, whereby the image could be made stable. This light-sensitive printing material had about 2 times the light-sensitivity of a commercially available dia-zotype positive light-sensitve paper and was excellent in resolution and clear in color tone.

Example 2 A light-sensitive printing material was prepared in the same manner as in Example 1, except that in place of the diphenylamine was used the same amount of Leucocrystal Violet. When treated in the same manner as in Example 1, the thus prepared printing material gave a clear, deep purple-image on a white background. This printing material is nega-posi type, and hence gives a positive image if a negative is used as an original and gives a negative image if a positive is used as an original.

Example 3 l-'(oz,ot,a tribromomethylsulfonyl) 4 methoxyphthalazine: 5 g.

N,N-diethanolaniline: 10 g.

1-phenyl-3-diphenyl-5-chlorophenylpyrazoline: 0.5 g.

Cellulose acetate butyrate: 10 g.

Acetone: 30 cc.

Benzene: 70 cc.

On a 150 g. baryta paper was coated 23 cc./mm. of a light-sensitive liquid of the composition shown below, followed by drying to prepare a light-sensitive printing material.

3-(ot,cz,ct tribromomethylsulfonyl)-6-methoxypyridaziner 2-oxide: 3 g. N,N-diethanolaniline: 10 g. Diphenylthiourea: 0.3 g. Vinyl methyl ether-maleic anhy Acetone: 50 cc. Methyl ethyl ketone: 25 cc. Methanol: 25 cc.

The thus prepared printing material was exposed to the same mercury lamp as in Example 1 to obtain a clear, bluish brown image on a white background. This image was fixed by immersing the material for 5-30 seconds in a fixing. solution of the following composition:

Starmous chloride: 20 g. Hydrochloric acid: 4 cc. Water: cc. Activator (5% aqueous solution): 4 cc.

ride copolymer: 2. g.

As the result, the image became a completely fixed stable image showing no change even when exposed to strong ultraviolet light.

Example 5 In a g. baryta paper was coated 20 cc./mm. of a light-sensitive liquid of the composition shown below to prepare a light-sensitive photographic material.

3-(0t,ot,ot tribromometliylsulfonyl)-6-hydroxypyridazine:

N-vinylcanbazole: 10 g. v

p-(N,N-dimethylamino)-pentylidene-'y-pyridine: 0.5 g.

Vinyl methyl ether-maleic anhydride copolymer: 2 g. p

9 Acetone: 50 cc. Methyl ethyl ketone: 25 cc. Methanol: 25 cc.

.The thus prepared printing material had been incorporated with a dye base and hence was sensitized to a visible light area. Accordingly, the light-sensitivity of this printing material was far more excellent than that of the printing material prepared in Example 1.

This printing material was exposed for 15-20 seconds at a distance of 30 cm. to a slide projector having a tungsten lamp as a light source in which had been inserted a photographic negative, whereby a sufficiently readable blue image was obtained. This image was further heated at 100 C. for -10 seconds to obtain a deep bluish brown, high density image. Subsequently, the image was subjected to fixation by immersing the printing material in gasoline, whereby the image could be made stable.

Example 6 A solution of the composition shown below was coated by means of a rotary coater on a zinc plate, followed by drying to prepare a pre-sensitized plate.

Methacrylic acid N ethyl N phenylaminoethyl methacrylate copolymer (6:4): 0.6 g.

1 (a,oz,u tribromomethylsulfonyl) phthalazine: 0.4 g.

Dioxane: 10 cc.

The thus prepared plate was closely adhered to a negative, set to a printing machine and exposed for 5 minutes to a 500 w. tungsten lamp at a distance of 30 cm. to obtain a blue, clear image. The zinc plate bearing the said image was developed with a 0.05% aqueous caustic soda solution, slightly dried and then etched with a Dow etching machine to obtain a relief printing plate excellent in resolution.

On the other hand, the above-mentioned light-sensitive solution was coated on a grained aluminum plate, exposed and developed in the same manner as above and then coated with rubber to obtain an olfset printing aluminum plate bearing a blue image.

What is claimed:

1. Light-sensitive imaging material comprising a support and a coating thereon of a light-sensitive composition comprising an organic compound reactive in the presence of a free radical to yield a visible color change and a photo-activator capable of forming said free radical upon exposure to light, said photo-activator being selected from the group consisting of:

(a) pyridazine derivatives of the formula:

10 wherein R is hydrogen, hydroxy, lower alkyl, alkylsulfonyl,

alkoxy, or alkoxycarbonyl;

(b) phthalazine derivatives of the formula:

wherein R is hydrogen, hydroxy, lower alkyl, alkylsulfonyl, alkoxy, or alkoxycarbonyl, or tribromomethyl sulfonyl,

R is hydrogen or tribromomethyl sulfonyl, at least one of R and R being tribromomethyl sulfonyl, and

R is hydrogen, hydroxy, lower alkyl, alkylsulfonyl,

alkoxy, or alkoxy carbonyl; and

(c) phthalazine derivatives of the formula:

wherein R is hydrogen, hydroxy, lower alkyl, alkylsulfonyl, alkoxy, alkoxycarbonyl.

2. Material according to claim 1 wherein said photoactivator is 3 (a,a,a tribromomethylsulfonyl) 6- methylpyridazine.

3. Material according to claim 1 wherein said photoactivator is 1 (ot,ot,oc tribromomethylsulfonyl) 4 methoxyphthalazine.

4. Material according to claim 1 wherein said photoactivator is 3 (a,oc,a tribromomethylsulfonyl) 6 methoxypyridazine-Z-oxide.

5. Material according to claim 1 wherein said photoactivator is 3 (a,a,a tribromomethylsulfonyl) 6 hydroxypyridazine. activator is 1 (u, x,ot tribromomethylsulfonyl) phthalactivator is l (oc,ot,a tribromomethylsulfonyl) pthalazine.

References Cited UNITED STATES PATENTS 3,502,476 3/1970 Itano et a1 M 96-90 NORMAN G. TORCHIN, Primary Examiner W. H. LOUIE, 1a., Assistant Examiner U.S. c1. x1e ofi 89; 260-250 23 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 I 667 I 954 Dated 6 T 1972 Inventor(s) Kohei Itano, Masashi Nakano, and Mitsuru Hashimoto It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 10, line 4, (b) phthalazine derivatives" should read -(b) pyridazine derivatives Col. 10, line 43 should read "6. Material according to claim I wherein said photo" Signed and sealed this 12th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GUTTSCHALK Commissioner of Patents Attesting Officer

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3833379 *Jan 11, 1973Sep 3, 1974Konishiroku Photo IndDeveloper composition for lithographic printing plates
US3966928 *Feb 21, 1974Jun 29, 1976Colgate-Palmolive CompanyNovel derivatives of pyridazine-2-oxide
US4263395 *Apr 18, 1979Apr 21, 1981Agfa-Gevaert N.V.High intensity photon-image recording
US5686503 *Jan 22, 1996Nov 11, 1997Kimberly-Clark CorporationPhotoinitiators
US6294698Apr 16, 1999Sep 25, 2001Kimberly-Clark Worldwide, Inc.Photoinitiators and applications therefor
US6486227Jun 19, 2001Nov 26, 2002Kimberly-Clark Worldwide, Inc.Zinc-complex photoinitiators and applications therefor
U.S. Classification430/339, 544/239, 544/237, 430/344, 544/240
International ClassificationG03C1/675
Cooperative ClassificationG03C1/675
European ClassificationG03C1/675
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Effective date: 19820323