FR2478837A1 - Diazo imaging process using hydroxy substd. benzophenone coupler - gives UV-stable image - Google Patents

Abstract

Diazo imaging process comprises selective reaction between a diazonium salt and a phenolic type coupler of formula (I). (I) is claimed where R3 is H or COR'', R'' is OH, OCH3, OC2H5, 1-15C opt. branched alkyl which is opt. substd. by one or more benzene rings, or NHR7 where R7 is alkyl or aryl. R4 is H, OH, opt. branched 1-15C alkoxy or COR''; R5 is H, SO3H, SO3Na, Cl, or COR''; R6 is H, OH, 1-15C alkoxy; at least one of R3, R4, R5, R6 is H; R'2 is H or OH; R'4 and R'6 are H, OH or 1-15C alkoxy gp.; R'5 is H, SO3H, SO3Na or Cl; with the proviso that if R4 and R'4 are OH, at least one of R3, R5, R6, R'5 and R'6 is other than H; or if R4 and R6 are OH, at least one of R3, R5, R'2, R'4, R'5 or R'6 is other than H. The couplers are used, alone or in combination, in known diazotype imaging systems including (a) systems in which the diazonium salt is exposed imagewise and then contacted with a developer contg. the coupler; (b) systems in which the diazonium salt and coupler are present in the imaging compsns. together with stabilisers, etc., in which development is accomplished by contact with alkaline vapours after imagewise exposure; and (c) heat-developing systems in which coupling is promoted by heat. The couplers (I) give dye images with improved resistance to UV exposure compared with prior art materials.

Description

Diazo reproduction method using benzophenones as coupling agents and corresponding materials
The present invention relates to a diazo copying method for obtaining stable reproductions of ultraviolet radiation, comprising selectively reacting a diazonium salt and a phenolic type coupler to obtain a color reaction.

The diazo copying process is based on the decomposition under the action of ultraviolet light of photosensitive diazonium salts: the non-destroyed parts, protected from ultraviolet light by the opaque areas of the original to be reproduced, then react with the Phenolic couplers, generally in the presence of an alkaline or neutral medium.

There are generally three types of processes to which the invention is applicable - the one-component diazotype method in which
the diazonium salt is alone present in the sen layer
deposited on the support (apart from adjuvants
usual). After exposure to ultraviolet light
through an original to reproduce, the material is put
in contact with a liquid developer containing the coupler
(and the usual adjuvants and stabilizers) that reacts
with the diazonium salt not destroyed to generate
colored traces.

the two-component diazotype method, in which
the diazonium salt and the coupler are mixed together
presence of stabilizers and adjuvants avoiding preco
lation.

After insolation through a semi-transparent original,
the photosensitive layer is brought into contact with vapors
alkalis that allow undestroyed diazonium salt
and the coupler, to react and form a colored trace.

the thermal diazotype method in which the medium
favorable reaction to the copulation reaction is
created by the action of heat: the sensitive layer usually contains the diazonium salt, the coupler and the stabilizing additives while an overlayer or undercoat or layer on the back of the support contains the ingredients necessary to generate alkaline vapors , generally ammoniacal, creating a favorable environment for the copulation reaction.

In all these processes, the phenolic couplers react with the diazonium salt to generate an azo dye whose color generally depends on the coupler used.

A significant disadvantage of all these processes is the low ultraviolet stability of the azo dyes so formed and the phenolic couplers located in the background areas of the image. Azolac dyes fade quickly under the action of ultraviolet rays (eg ultraviolet rays of daylight) while unreacted phenolic couplers oxidize and background areas of the image become yellow .

Such a disadvantage is particularly noticeable in counter-shots made on a transparent support, for which a large number of prints are made on diazo paper. To obtain sufficiently high-contrast prints, it is then necessary to gradually reduce the print speed and correspondingly increase the power of the ultraviolet illumination means.

It has been proposed, in particular in French Patent No. 2,000,342, to improve the ultraviolet stability of disazo reproductions by incorporating ultraviolet radiation absorbing products in the disazo layers.

Such products have however proved to be inefficient and impractical to implement and have not given rise to any commercial realization to date.

The method according to the invention makes it possible to avoid these disadvantages.

avec R3 = H ou COR" avec R" = OH, OCH3, OC2H5, une chaine alkyle linéaire ou ramifiée comportant de I à I5 atomes de carbone .Cette chaine alkyle étant éventuellement substituée par un ou plusieurs noyaux benzéniques, NHR'",
R"' étant une chaîne alkyle ou aryle,
R4 = H, OH, un radical alkoxy ayant une chaîne linéaire ou ramifiée comportant de I à 15 atomes de carbone, COR",
R5 = H, S03H, S03Na, Cl, COR", l'un au plus de R3,R4 et R5 étant égal à COR",
R6 =H, O H, un radical alkoxy comportant de I à I5 atomes de carbone, l'un au moins de R3, R4, R5 et R6 étant égal à H
R'2 = H,OH
R'4, R'6 = H, OH, un radical alkoxy comportant de I à 15 atomes de carbone,
R'5 = H, S03H, S03Na, Cl
On a en effet constaté que, de manière surprenante, les benzophénones citées#ci-dessus qui sont des produits bien connus comme absorbeurs de rayonnement ultraviolet (Encyclopedia of Chemical Technology - vol. 21 - p. 115 à I22) possédaient également la propriété de copuler avec les sels de diazonium et former des colorants azoïques très stables à la lumière ultraviolette. On ne constate aucune décoloration des colorants formés après des épreuves de vieillissement accéléré (voir résultats ci-après). De plus, ces produits, dans les régions où le sel de diazonium a été détruit par la lumière ultraviolette avant la réaction de copulation, permettent à ces régions de conserver leur aspect d'origine, sans aucune montée de fond.On constate de plus, que ces produits sont incolores ou peu colorés, qu'ils permettent l'obtention après développement de matériaux ayant un pouvoir couvrant élevé (c'est-à-dire un matériau dont les parties colorées ontune forte opacité dans l'ultraviolet et le proche visible - de 200 à 500 nm).For this purpose, it is characterized in that the phenolic coupler is chosen from benzophenones of general formula

with R3 = H or COR "with R" = OH, OCH3, OC2H5, a linear or branched alkyl chain containing from 1 to 15 carbon atoms. This alkyl chain being optionally substituted with one or more benzene rings, NHR '",
R "'being an alkyl or aryl chain,
R4 = H, OH, an alkoxy radical having a linear or branched chain containing from 1 to 15 carbon atoms, COR ",
R5 = H, SO3H, SO3Na, Cl, COR ", at most one of R3, R4 and R5 being equal to COR",
R6 = H, OH, an alkoxy radical having from 1 to 15 carbon atoms, at least one of R3, R4, R5 and R6 being equal to H
R'2 = H, OH
R'4, R'6 = H, OH, an alkoxy radical having from 1 to 15 carbon atoms,
R'5 = H, SO3H, SO3Na, Cl
Surprisingly, it has been found that the above-mentioned benzophenones which are well-known ultraviolet light absorbers (Encyclopedia of Chemical Technology Vol 21 - pp. 115 to I22) also possess the property of copulate with the diazonium salts and form azo dyes very stable to ultraviolet light. There is no discoloration of the dyes formed after accelerated aging tests (see results below). In addition, these products, in regions where the diazonium salt was destroyed by ultraviolet light before the copulation reaction, allow these regions to retain their original appearance, without any bottom rise. that these products are colorless or not very colored, that they make it possible to obtain, after development, materials having a high covering power (that is to say a material whose colored parts have a high opacity in the ultraviolet and the visible near from 200 to 500 nm).

In addition, since each dye molecule is partially formed of an ultraviolet absorber molecule, said dyes are extremely daylight resistant.

Preferably, the benzophenones selected from the following list will be used 2,4-dihydroxy benzophenone 2-hydroxy 4-methoxy benzophenone 4-decyloxy 2-hydroxy benzophenone 4-dodecyloxy 2-hydroxy benzophenone 2,2'-dihydroxy 4-methoxy benzophenone 2 4-methoxy 2'-carboxy benzophenone 2,2'-dihydroxy 4,4'-dimethoxy benzophenone 2,2 '4,4'-Tetrahydroxy benzophenone 2-hydroxy 4-methoxy 5-sulfobenzophenone sodium 2,2'-dihydroxy 4,4'-Dimethoxy 5-sulfobenzophenone 5-chloro-2-hydroxy benzophenone 2-hydroxy-4-octyloxy benzophenone 2,4,6-trihydroxy benzophenone
All these products are generally soluble in organic solvents, which implies in this case to choose soluble diazonium salts also in said solvents, said salts being well known to those skilled in the art.

However, when the substituent R5 is equal to SO3H or
S03Na, the corresponding benzophenones are water-soluble and make it possible to produce diazotype materials in aqueous medium: then use the water-soluble diazonium salts (and adjuvants) well known to those skilled in the art.

In order to obtain the various dyes required for diazotyping, it may be necessary to mix several couplers according to the invention and / or several diazonium salts in proprotions which are well known to those skilled in the art, said hues being obtained by simple routine manipulations.

In general, all the diazonium salts of the type
ArN2X, wherein Ar is a substituted or unsubstituted aryl radical, may be used in the context of the present invention. The diazonium salt may, for example, be selected from chlorozincates, borofluorides, chlorostannates, sulphates, hexafluorophosphates, paratoluenefulfonates, etc. while the aryldiazonium radical may be chosen from substituted benzenesediazonas, p.aminobenzenediazoniums and o -amines. benzene diazonium, m-amino benzene diazonium, mercaptobenzene diazonium, etc.

In general, reference can be made to the choice of diazonium salt in J. KOSAR's book "Light sensitive systems". Preferably, however, the diazonium salts well known to those skilled in the art having a high coupling activity and an absorption maximum greater than or equal to 400 nm will be used. Indeed, the couplers used in the context of the present invention being also ultraviolet absorbers, it is preferable to use diazonium salts copulating rapidly to obtain high speed printing materials.

Non-limiting examples include 4-dialkylamino 2-chloro-5- (4'-chlorophenoxybenzene diazonium), the alkyl radical being preferably a methyl or ethyl radical, 4-diazo 2,5-dialkoxy I- ( 4'-tolyl) mercapto benzene, the alkoxy radicals being preferably chosen from methoxy and ethoxy radicals.

The proportions between the diazonium salt and the coupler will be chosen within the usual limits well known to those skilled in the art, that is to say between 0.3 and the process used, the usual adjuvants for good preservation of the diazo layer.

The invention also relates to two-component diazo copying materials comprising a support coated with a photosensitive layer comprising in particular a diazonium salt and a coupler derived from benzophenone as described above.

According to a preferred embodiment, the material according to the invention is a counter-plate, characterized in that the support is hydrophobic while the diazonium salt and benzophenone used are soluble in organic solvents, the R5 radical of said benzophenone being selected from radicals H, Cl and COR ".

The invention will be better understood with the aid of the following non-limiting examples of embodiment.
EXAMPLE I
The following solution is coated at a rate of 2 g / m 2 on a matte polyester film.
Isopropanol 900 g
100 g water
Sulfosalicylic acid 20 g 2,4-dihydroxy benzophenone IO g
N-methyl N-benzyl amino-4
3-Ethoxy benzenediazonium
chlorozincate I5 g
Formic acid I5 g
After drying, the material is insolated through a semi-transparent positive and developed in a machine generating ammonia vapors. The resulting image is yellow-brown in color.

EXAMPLE 2
Is coated on the same support and under the same conditions as in Example I, the following solution
Ethanol 860 g
Methylglycol I40 g
Tartaric acid 25 g
Thiourea 20 g 2,4,6-trihydroxy benzophenone I2 g 4-diazo 2,5-diethoxy I- (4'-tolyl)
mercapto benzene, chlorozincate 20 g
The print obtained in the same conditions as in Example I is purple-black in color.

EXAMPLE 3
The coating is carried out under the same conditions as in Example I, a lacquered layer as described in Patent No. 1552166 in the name of the company LA CELLOPHANE with the following solution
Ethanol 900 g
Methylglycol acetate IOO g
Sulfosalicylic acid 20 g 2-hydroxy 4-methoxy benzophenone 10 g 1-diazo 2-chloro 4-diethylamino 5-p
chloro phenoxy benzene, chlorozincate I5 g
The resulting image is yellow-sepia.

EXAMPLE 4
A matt polyester support is coated under the same conditions as in Example I with a solution identical to that of Example 3, replacing the diazonium salt with the same amount of 1-diazo 2-chloro-4-dimethylamino. p-chlorophenoxy benzene, chlorozincate
We get a counter-shot with an image of the same sepia yellow tint.

In both Examples 3 and 4, it should be noted that the diazotype material thus produced has a very high sensitivity to ultraviolet radiation and excellent hiding power.

EXAMPLE 5
A matt polyester support is coated under the same conditions as in Example I, with the following solution
Methanol 1000 g
Sulfosalicylic acid 10 g
Acetic acid I5 g 2,2 ', 4,4'-tetrahydroxy benzophenone 7 g 2,4,6-trihydroxy benzophenone 5 g 4-diazo 2,5-diethoxy I- (4'-totyl) mercaptoben
zen, chlorozincate 20 g
After printing, a counter-shot of black color having the same advantages as those of Examples 3 and 4 is obtained.

EXAMPLE 6
A counter-cliché identical to Example 5 is produced using the following solution
Acetone 600 g
400 g methanol
Paratoluene sulphonic acid 30 g 2-hydroxy 4-octyloxy benzophenone I4 g 4-diazo 2,5-dimethoxy I - (4'-tolyl) mercapto
benzene, chlorozincate I6 g 4-diazo 2-chloro N-methyl, N-cyclohexyl
aniline, chlorozincate I2 g
The print obtained after development is yellow-orange.

EXAMPLE 7
A counter-cliché is made on a matt polyester support as known from the prior art (without benzophenone type coupler) with the aid of the following solution, coated at a rate of 2 g / m 2
Sisorbyl sulfide 35 g m-hydroxy phenylurea I4 g 4-diazo-2-methyl I-pyrrolidino benzene,
chlorozincate 36 g
Methylglycol acetate 50 cm3
1,950 cm3 methanol
Tartaric acid 25 g
Thiourea 20 g
Zinc chloride IO cm3
With the counter-shot obtained, we measure the whiteness of the background with a Photovolt device, before the first draw, then after 500 prints of this counter-shot using a machine drawing plans.

The same measurements are made with the counter-cliche of Example 4. The following results are obtained:

<tb><SEP> Before <SEP><SEP> I <SEP> print <SEP> After <SEP> 500 <SEP> prints
<tb> Whiteness <SEP> of
<tb> material <SEP> of <SEP> 62 <SEP> 58
<tb> the example <SEP> 4
<tb> Whiteness <SEP> of
<tb> material <SEP> from <SEP> 59 <SEP> I8 <SEP>
<tb> the example <SEP> 7
<Tb>
It is therefore clear that a material according to the invention has a bottom that does not yellow while the material of Example 7 (which corresponds substantially to commercially available materials) has a background that becomes very yellow.

Under the same conditions as above, a measurement of the optical density of the dye measured by transmission to the blue filter using a Mac Beth densitometer is carried out.

We obtain the following results

<tb><SEP> Before <SEP><SEP> I <SEP> print <SEP> After <SEP> 500 <SEP> prints
<tb> Density
<tb> optics <SEP> of
<tb> material <SEP> of <SEP> 2,7,0 <SEP><SEP> 2,60
<tb> the example <SEP> 4
<tb> Density
<tb> Optical <SEP> of <SEP> 2.35 <SEP> I, 50
<tb> material <SEP> of
<tb> the example <SEP> 7
<Tb>
These two comparative measurements show how much the invention makes it possible to improve the whiteness of the background and the optical density of the dye compared with materials using the usual couplers.

Moreover, the material according to the invention makes it possible to carry out 500 successive prints without modifying the machine settings, contrary to the material of example 7 with which a continuous adjustment, with reduction of the insolation speed, must be carried out to obtain visible prints.

Claims (21)

R E V # N D I C A T L O N S 1 - Method of diazo production to obtain re-production  stable productions with ultraviolet radiation, consisting of  selectively reacting a diazonium salt and a coupler  of phenolic type, in order to obtain a colored reaction, carac  terisé in that the phenolic coupler is chosen  among benzophenones of general formula

 with R3 = H or COR "with R" = OH, OCH3, OC2H5, a linear or branched alkyl chain having 1 to 15 carbon atoms, this alkyl chain being optionally substituted by one or more benzene rings, NHR '' ', R # 11 being an alkyl or aryl chain, R4 = H, OH, an alkoxy radical having a straight or branched chain having 1 to 15 carbon atoms, COR ", R5 = H, SO3H, SO3Na, Cl, COR" at most one of R3, R4 and R5 being equal to COR ", R6 = H, OH, an alkoxy radical having 1 to 15 carbon atoms, at least one of R3, R4, R5 and R6 being equal to H, R '= H, OH  2 R'4, R'6 = H, OH, an alkoxy radical having 1 to 15 carbon atoms, R'5 = H, SO3H, SO3Na, CL, and with as conditions that  if R4 = R'4 = OH, at least one of R3, R5, R6, R'5, R6 is  different from H,  or if R4 = R6 = OH, at least one of R3, R5, R'2, R'4, R'5, K6 is  different from H,  said benzophenones being used alone or in mixtures between  they. 2 - The diazo reproduction method according to claim 1,  characterized in that the coupler is selected from the products  following, used alone or in mixtures  2,4-dihydroxy benzophenone  2-hydroxy 4-methoxy benzophenone  4-decyloxy 2-hydroxy benzophenone  4-dodecyloxy 2-hydroxy benzophenone  2,2'-dihydroxy-4-methoxy benzophenone  2-hydroxy 4-methoxy 2'-carboxybenzophenone  2,2'-dihydroxy 4,4'-dimethoxy benzophenone  2-hydroxy-4-methoxy-5-sulfobenzophenone  Sodium 2,2'-dihydroxy 4,4-dimethoxy-5-sulfobenzophenone  5-chloro-2-hydroxybenzophenone  2-hydroxy-4-octyloxy benzophenone 3 - diazo reproduction method according to claim 1 or  2, characterized in that one or more salts of  diazonium, one or more couplers and adjuvants and / or  soluble stabilizers in organic solvents, the radical  Wherein R 5 is selected from hydrogen, chlorine and COR ". 4 - A diazo reproduction process according to claim 1 or 2,  characterized in that one or more salts of  diazonium, one or more couplers and adjuvants and / or  stabilizers soluble in water, radical R5 being chosen  among SO3H and SO3Na. 5 - Reprographic material of the two-component type, comprising  a support coated with a photosensitive layer including  a diazonium salt and a phenolic type coupler capable of reacting locally with the diazonium salt and generating colored traces in the presence of a favorable reaction agent, characterized in that the phenolic coupler is chosen from among the beuzophenones of general formula ::

 with R3 = H or COR "with R" = OH, OCH3, OC2H5, a linear or branched alkyl chain having from 1 to 15 carbon atoms, this alkyl chain being optionally substituted with one or more benzene rings, NHR "', R '' 'being an alkyl or aryl chain, R4 = H, OH, an alkoxy radical having a linear or refined chain having from 1 to 15 carbon atoms, COR ", R5 = H, SO3H, SO3Na, Cl, COR", at most one of R3, R4 and R5 being equal to COR ", R6 = H, OH, an alkoxy radical having 1 to 15 carbon atoms, at least one of R3, R4, R5 and R6 being equal to H R'2 = H, OH, R'4, R'6 = H, OH, an alkoxy radical having from 1 to 15 carbon atoms, R'5 = H, SO3H, SO3Na, Cl, and with the provisos that if R4 = R'4 = OH, at least one of R3, R5, R6, R'5, R'6 is different from H,  or if R4 = R6, OH, at least one of R3, R5, R'2, R'4, R'5, R'6  is different from H. 6 - Reprographic material according to claim 5, characterized  in that the coupler is selected from the products  following, used alone or in mixtures  2,4-dihydroxy benzophenone  2-hydroxy 4-methoxy benzophenone  4-decyloxy 2-hydroxy benzophenone  4-dodecyloxy 2-hydroxy benzophenone  2,2'-Dihydroxy 4'-methoxy benzophenone  2-hydroxy 4-methoxy 2'-carboxybenzophenone  2,2'-dihydroxy 4,4'-dimethoxy benzophenone  2-hydroxy 4-metboxy 5-sulfobenzophenone  Sodium 2,2'-dihydroxy 4,4'-dimethoxy-5-sulfobenzophenone  5-chloro-2-hydroxybenzophenone  2-hydroxy 4-octyloxy benzophenone 7 - Material according to claim 5 or 6, characterized in that  the constituents of the layer are chosen from the products  soluble in organic solvents, the radical R5 being  then selected from H, CL and COR ".  3 - Material according to claim 5 or 6, characterized in that  the constituents of the layer are chosen from the products  soluble in water, the radical R5 being then chosen from  S03H and S03Na. 9 - Reprographic material according to claim 7, characterized  in that the support is selected from the matt polyester, the  lacquered layer or cellulose acetate. 10- Material according to claim 9, characterized in that the  support is transparent or translucent in order to achieve  cons-shots.