DE1772534B - Light-sensitive mixture that can be inactivated by light - Google Patents

Description

It is known that conventional photographic processes are usually expensive, cumbersome and time consuming are. The classic silver halide photography for example, uses expensive chemicals and papers, is a multi-step process and is in demand staff trained to achieve good results. Thermography requires less experience of the Operating personnel and less expensive parry, but produces images of inferior quality.

It is also known for the production of photographic copies to be photosensitive by the dry route Layers to use the photolytic organic halogen compounds as radical formers and color formers contain, which produce dyes during the radical formation initiated by the exposure (British U.S. Patent 917,919, U.S. Patent 3,042,517).

The disadvantage is that the photolytic radical formers used in this process because of the Volatility and toxicity are difficult to manage.

It is also known to be light-sensitive for the production of photographic copies by the dry route Use layers that contain one or more color formers and hexaarylbisimidazoles as photolytic Free radical formers included (British Patent 1,047,569).

The object of the invention is to provide a photosensitive mixture for generating visible images upon exposure to light of a given wavelength A ₁ , in which the recordings can be easily and effectively permanently inactivated against further color formation and thus fixed by exposure to light of a second wavelength A and in which the creation and fixing of the images is achieved with a dry, quick and easily controllable procedure.

The subject matter of the invention is based on a photosensitive mixture which is _{activated for color formation by light of a wavelength A 1} and since exposure to light of a second wavelength A makes it insensitive to light and that

(a) a colorless nitrogen-containing dye which is stable under normal conditions and forms a dye and forms a dye organic compound as color former,

(b) a hexaarylbisimidazole which, when exposed to light with a wavelength A ₁ of 250 to 370 nm, is able to oxidize the color former to form the dye as a photooxidant and

(C) a redox couple initiatable with light of wavelength A ₂ , which prevents the photo-oxidative dye formation of the color former _{with light of wavelength A 1} , and

(d) optionally contains an inert solvent

and is characterized in that it is a color former (a) a salt of an acid and a practical colorless, oxidizable, substituted aminotriaryl methane and a redox couple (c), which from (1) one oxidizing component from the Pyrenchinoi group

and phenanthrenequinone and (2) a compound which unlike xerography it produces images in

general formula of a multitude of intermediate tones, which over the entire

Nf (CHn) COOR] ^th density range and does not require any

² "complicated image developing apparatus.

in which η denotes the integer 1 or 2 and R denotes an even 5 unlike in commercial thermography a chain alkyl group of 1 to 4 carbon atoms, the image can be inactivated so that it does not exist as a reducing agent. is disturbed when it passes the activating radiation

The invention also encompasses methods of exposure to producers. The method of the present invention for producing an image with a light-stable background also gives images of high sharpness in a variety of colors with excellent gradation of hues by stepwise irradiating the photosensitive io.
Mixture according to claim 1 with light from two different- Unlike the diazo method, the dry-

Different wavelength ranges between 250 and working methods according to the invention no volatile 500 nnr where an image-wise exposure to light gos, enteiner causing a strong odor nuisance Wavelength and total exposure to a light developing agent, such as ammonia, gives high images other wavelength is provided. 15 sharpness with higher photographic sensitivity

According to one embodiment of the invention, this is and generates either negatives or positives Process for producing fixed, light-insensitive negatives.

Licher, negative images, characterized in that a preferred light-sensitive mixture contains

a photosensitive mixture, which is given a substituted aminotriarylmethane, which is at least nenfalls on a layer support, first with 20 two p-dialkylamino-substituted phenyl groups-light with a wavelength A ₁ from 250 to 370 nm, which is in the ortho position exposed a master copy to the methane charcoal and then totally exposed it to light of a material atom, an alkyl, alkoxy or halogen other wavelength A _2. wear substitution, as hexaarylbisimidazole

According to a further embodiment of the invention, 2,2 '- (o-substit.-phenyl) -4,4', 5,5'-tetraphenylbisimide is the process for producing fixed, light-az.ol, as an oxidizing component Mixture of insensitive, positive images characterized by 1,6- and 1,8-pyrenquinone and as a reducing one draws that a light-sensitive mixture, the constituent of the trimethyl ester of 3,3 ', 3 "-Nitrilotrisich optionally ¹ ■ · on a In a further preferred embodiment, first with light with a wavelength A ₂ of 380 to 500 nm formea, 9,10-phenanthrenequinone or mixed imperfections are exposed through a master copy and then with light from the same with the pyrenquinones as the oxidizing agent of a different wavelength A ₁ from 250 to 370 nm total component of the redox couple is used,
exposed. The photosensitive compositions according to the invention

When irradiated with a light pattern of the waves, _{the color former and the photographic material can react as photosensitive recording material length A 1} by layering them on an oxidant with image-wise dye formation. After 35 layers are applied,
subsequent exposure to light of a second wave.

length A ₂ causes the redox couple in the pictorial w ^{The rarbbikAär}

Image parts unexposed with light of wavelength A ₁ The color-producing component of the invention quickly forms a hydroquinone, which prevents a further color-sensitive light-sensitive mixture from developing by reacting with the photo of an acid and a practically colorless amino oxidant to form a colorless product . The triarylmethane, the light-sensitive mixture on the amino and aryl groups, thus quickly and effectively carries substituents. Such a compound represents a sam _{inactivated by light of wavelength A 2} , and a strong acid salt and the leuco form of the image appears against a stable background, triarylmethane dye, which compound which has the color of the unexposed layer. If 45 is oxidized with color development, if the photosensitive mixture is first _{image-wise irradiated with a mixture of the compound and a hexaarylbisimide light pattern of wavelength A 2} azole photooxidant in the presence of a solvent, is irradiated by inactivation in the irradiated. Light with a wavelength of about 250 regions creates a latent image. The latent image up to about 370 nm conducts in the irradiated area is then developed by subsequent irradiation with light 50 redox reaction between the salt of the acid and that of the wavelength A ₁ , the color formation of the substituted aminotriarylmethane and the bisimidine occurring in those image parts that occur in the advance azole. If the first exposure, which has been exposed through a master copy, is made with light of the wavelength, a corresponding, colored image is produced against A _{2 that} remained unexposed. Thus, this provides a background which consists of non-irradiated and the photosensitive mixture according to the invention depending on the layer parts unchanged. Because of the order in which the light wavelengths A _{1 of} their superior resistance to color and A ₂ positive or development by air oxidation are applied, such species are negative copies. In any case, the picture of aminotriarylmethanes appears preferred, which are at least sharp and clear against a stable background. at least two of the aryl groups in the ortho position to the

By the invention, a photographic 60 methane carbon atom is an alkyl, alkoxy or Process accessible, which carry halogen substituents easily and at the same time quickly.

in a single apparatus or machine through representative aminotriaryl methanes that

can be performed. In one embodiment, the following are effective as required:
does not change it for the generation of a visible image

Stage of development. Since it can be carried out dry 65 bis - ^ - chloM-diethylaminophenylMp-chlorine, it does not do any wet treatment or compli-phenyl) methane

adorned additional device required. It can directly bis (2-chloro-4-diethylaminophenyl) - (p-diethyl-

tslbar produce either positive or negative copies. aminophenyl) methane

Bis (2-chloro-4-diethylaminophenyl) phenylmethane

Bis (4-diethylamino-2-methoxyphenyl) - (4-nirrophenyl) methane

Bis- (p-diethyIaminophenyl) - (4-diethyIamino-otoly!) - methane

Bis (4-diethylamino-o-tolyl) - (4-benzylthiophenyl) methane

Bis- (4-diethylamino-o-toyl) - [p- (p-chlorobenzylthio) phenyl] methane

Bis- (4-diethyIamino-o-toyl) - (p-chlorophenyl) methane

Bis- (4-diethylamino-o-tolyl) - (p-diethylaminophenyl) methane

Bis- (4-diethylamino-o-tolyI) - (2,3-dimethoxyphenyl) methane

Bis (4-diethyIamino-o-toiyl) - (2,4-dimethoxyphenyl) methane

Bis (4-diethylamino-o-tolyl) - (3,4-dimethoxyphenyl) methane

Bis- (4-diethyIamino-o-toyl) - (o-fluorophenyl) methane

Bis (4-diethylamino-o-tolyl) - (p-hydroxyphenyl) methane

Bis- (4-diethyIamino-o-tolyl) - (4-isopentylthio-intolyD-methane

Bis- (4-diethylamino-o-tolyi) - (4-isopropylthio-mtolyl) methane

Bis (4-diethylamino-o-toyl) - (p-methoxyphenyl) methane

Bis (4-diethyIamino-o-toyl) - (3,4-methylenedioxyphenyl) methane

Bis- (4-diethylamino-o-toyl) - (p-nitrophenyI) methafl

Bis (4-diethylamino-o-toyl) phenylmethane Bis (4-diethylamino-o-toyl) -2-thienylmethane bis (4-dimethyIamino-o-tolyl) - (o-bromophenyl) methane

Bis (4-dimethylamino-o-tolyl) -o-chlorophenyl) methane

(P-ChloM-diethylaminophenyO-O-diethylaminoo-tolyl ) -phenylmethane

(p-DiethyIaminophenyl) - (4-diethylamino-o-tolyl) -o-tolylmethane

Tris (p-diethyfominophenyl) methane Tris (4-diethylamino-o-tolyl) methane T, -is- (2-chloro-5-diethylaminophenyl) methane, tris (4-dimethylamino-o-tolyl) methane

An acid which forms a salt with an amine, such as a mineral acid, organic acid or an acid from an acid-donating compound, is used together with the above-mentioned compounds which form dyes of the triaryl methane type with substituted amino groups and are referred to as cationic dyes. The total amount of acid can vary between 1 and 20 moles per mole of leuco dye, a molar ratio of about 4: 1 to 10: 1 being preferred. For a light-sensitive mixture which contains the constituents in given amounts, the range in which the amount of acid between an excess, which tends to reduce the reactivity of the light-activated bisimidazole and thus makes the mixture less light-sensitive, and an excess must be determined by preliminary tests The deficiency, which in the presence of the basic ester reductant, delays the conversion of the leuku form of the dye into the dye, is balanced. Representative acids which form the required salts with the amine are hydrochloric, hydrobromic, sulfuric, nitric, phosphoric, acetic, oxalic and p-toluenesulphonic acids. Other acids, such as the "Lewis" acids, that can be used in the presence of water or moisture include zinc chloride, zinc bromide, and ferrous chloride.

(b) The photooxidant

The photooxidant component according to the invention is a hexaarylbisimidazole, which when exposed to light a wavelength of about 250 to about 370 nm is irradiated, absorbs the activating light and dissociated into free radicals. These radicals bind the active oxidizing agent, which is produced by an oxidation-reduction mechanism reacts with the salt of the acid urd of the aminotriaryl methane and the Leuco dye compounds into the triaryl methane

ao dyes transferred. Representative hexaarylbisimidazoles, which are suitable for the mass according to the invention are:

2,2'-bis (o-bromophenyl) -4,4 ', 5,5'-tetraphenyl-

bisimidazole
«5 2,2'-bis (o-chlorophenyl) -4,4'-di-1 -naphthyl-

5,5'-aiphenylbisimidazole

2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenyl-

bisimiriazole

2,2'-bis (o-chlorophenyI) -4,4 ', 5,5'-tetrakis- (p-methoxyphRnyl) -bisimidazole

2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetrakis-

(m-methoxyphenyl) bisimidazole

2,2'-bis (2,4-dichlorophen>!) - 4,4 ', 5,5'-tetraphenyl-

bisimidazole
'2 ₎ 2'-bis (2,3-dimethoxyphenyl) -4,4', 5,5'-tetra-

phenylbisimidazole

2,2'-bis (2,4-dimethoxyphenyl) -4,4 ', 5,5'-tetra-

phenylbisimidazole

^ '- Bis-io-ethoxyphenylM.O.S'-tetraphenylbisimidazole

2,2'-bis (o-fluorophenyl) -4,4 ', 5,5'-tetraphenyl-

bisimidazole

2,2'-bis (o-methoxyphenyl) -4,4'-bis (p-methoxy-

phenyl) -5,5'-diphenylbisimidazole
2,2'-bis (o-methoxyphenyl) -4,4'-5,5'-tetraphenyl-

bisimidajol

2,2'-bis (o-methoxyphenyl-4,4 ', 5,5'-tetrakis-

(p-met hoxyphenyO-bisimidazole

2,2'-bis (2,4,6-trimethylphenyl) -4,4 ', 5,5'-tetraphenylbisimidazole

2,2'-Di-1-naphthyi-4,4'-5,5'-tetraphenyIbisimid-

azole

2,2'-D ^; 1-naphthyl1,4 '-, 5,5'-tetrakis- (p-methoAy-

ohenyl) -bis-imidazole
2,2'-di-9-phenanthryl-4,4 ', 5,5'-tetraphenyl-

bisimidazole

2,2'-Di-9-phenanthryl-4,4 ', 5,5'-ietrakis- (p-metho-

xyphenyl) bisimidazole

2,2 ', 4,4'-retra-1-naphthyl-5,5'-diphenylbisimidazole

2,2'-4,4'-tetrakis- (o-methoxyphenyl) -5,5'-di-

phenylbisimidazole

2,2'-di-o-tolyl-4,4 ', 5,5'-tetraphenylbisimidazole

2,2'-4,4 ', 5,5'-hexa-1-naphthylbisimidazole
2,2 ', 4,4', 5,5'-hexaphenylbisimidazole

2,2 ', 4,4'-5,5'-hexa-o-tolylbisimidazole

2,2 ', 4,4', 5,5'-hexakis- (o-methoxyphenyl) -

bisimidazole

The bisimidazoles are made from the corresponding triarylimidazole, as described by H a y a s h i et al., In Bull. Chem. Soc. Japan, 33, No. 565 (1960).

(c) The redox couple

A photosensitive mixture, which consists only of a hexaarylbisimidazole as photooxidant and a salt of an acid and an aminotriarylmethane as color former, produces an image when it is _{irradiated with light of wavelength A 1} through a master copy. However, this image is not stable because the non-irradiated areas of the image are colored when the surrounding light contains light of wavelength X _1. Means must therefore be provided for inactivating the photosensitive mixture, since otherwise the surrounding light changes or destroys the image. According to the present invention, a method for rapid and complete inactivation is that a redox couple is added to the light-sensitive ao mixture which consists of a pyrenquinone and / or a 9.10-phenanthrenequinone as oxidant and a C _{1 -C 4} -alkyl ester of nitrilotriacetic acid - Or 3,3 ', 3 "-Nitrilotripropion-Acid exists as a reductant. When irradiated with light of wavelength λ, the ester reductant increases the reduction of the quinone oxidane to a hydroquinone so much that the hydroquinone for a quick and complete inactivation of the Bisimidazole ensures that the latter is no longer available for color formation. The hydroquinone formed is a stronger reducing agent than the color-forming salt of the acid and of aminotriaryl methane. During storage and until such inactivation is necessary, reacts the basic ester reductant does not and has no adverse effect on any of the components of the photosensitive mass.

solvent

40

Solvents against the color-producing triphenylmethane, the hexaarylbisimidazole and the Quinone-nitrilotrialkanoic acid alkyl ester redox couple are inert, are usually used to make them To dissolve constituents and thereby mix them with one another and to create a liquid medium for application to enable the photosensitive mixture on the support.

To obtain coated recording materials, one usually removes the solvent, e.g. B. by evaporation. It is often beneficial to have a low Leave residual solvent in the dried layer. Layers that are exhaustively dry tend to be to produce less flawless images. A loss of photosensitivity by complete Drying, but can be made up for by adding a small amount of solvent, z. B. by spraying, brushing or dipping, is introduced. Either in the dried layer remaining, small residue of solvent does not mean that the support, ζ. Β. made of paper, necessarily wet, dampened or otherwise specially "treated. Numerous solvents, such as N.N-dimethylformamide, N, N-diethylacetamide, dimethyl sulfoxide, are cellulose and plastic substrates so strongly adsorbed that it takes longer to completely remove the solvent Heating under vacuum is necessary. Ordinary drying, as it is in papermaking or during Pouring is applied leads to the retention of copious amounts of solvent, so that a layer with it good photosensitivity. The layers produced in this way are quite dry to the touch and stable during storage at room temperature. Of course, many of these layers, in particular those using a salt of an acid and an amino-leuco form of a dye on cellulosic substrates contain air moisture adsorbed, which serves as a suitable solvent.

in general, a suitable solvent has a boiling point of at least 40X under atmospheric pressure. Solvents with low vapor pressures and consequently high boiling points can be used. That they cannot be easily removed by evaporation is not a problem if the amount used is limited, as can easily be done in mixtures of solvents with relatively high vapor pressures. Preferably, at least 0.5 percent by weight of solvent should be retained by the substrate, such as paper, to ensure image development upon irradiation 'St. Have been applies to the solvents that w {, and can be used include amides such as formamide, N ₁ N-dimethylformamide, Ν, Ν-Dimehtylacetamid, Hexanamide, stearamide alcohols and ether alcohols, such as methanol. Ethanol. 1-propanol, 2-propanol, butanol. Ethylene glycol. Polyethylene glycol; Esters, such as ethyl acetate. Ethyl benzoate; aromatic compounds such as benzene. o-dichlorobenzene, toluene; Ketones such as acetone and methyl ethyl ketone. 3-pentanone: aliphatic hydrocarbons such as methylene chloride, chloroform, 1.1.2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,1,2-trichlorethylene; various solvents such as dimethyl sulfoxide, pyridine, tetrahydrofuran, dioxane, dicyanocyclobutane, 1-methyl-2-oxohexamethyleneimine; and mixtures of these solvents in the various proportions as may be required to cause the ingredients specifically selected for use in the photosensitive compositions to go into solution.

Usually, a relatively low molecular weight polyalkylene glycol is used as a non-volatile one Solvent used in the photosensitive compositions according to the invention. The reducing one Part of the redox couple. the alkyl ester of nitrilotriacetic or nitrilotripropionic acid. also works as a solvent that is a medium for the reaction between the color-forming ingredients and the deactivating constituents of the mixture; can be. The basicity which this basic Estei imparts to the mixture when it is used as a solvent in larger quantities than it is for its « reducing effect on the quinone needed tends to reduce the saturation of the image color; to belittle.

Polymeric binders can also be present in the photosensitive compositions so that the Mixtures are thickened and adhere to the layers. Translucent and film-forming polymer are favored. Examples are ethyl cellulose, polyvinyl alcohol, polyvinyl chloride, polystyrene, poly vinyl acetate, poly (methyl methacrylate), cellulose acetate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, chlorinated rubber, copolymers of the above called vinyl monomers and gelatin. The amount

9 10

the binder vary from about 0.5 to about clay; Plastic films and polymeric substances, such as regenerative

200 parts by weight per part of the combined weight of cellulose, cellulose acetate, cellulose nitrate, poly-

of leuco dye. Bisimidazole and redox couple. In the ester of glycol and terephthalic acid. Vinyl polymers

in general, 0.5 to 10 parts of binders are mixed and mixed polymers, polyethylene, polyvinyl acetate,

uses, while higher quantities in the production 5 Polymethyl methacrylate, polyvinyl chloride: textile

the self-supporting light-sensitive layers. Glass, wood and metals. Layer carrier, in

be turned. In the case of certain polymeric binders in which the photosensitive components are dissolved

it may be desirable to add a plasticizer or what the light-sensitive components are

set to give flexibility to the layer. To those as a layer on the back, i.e. H. on that

Plasticizers include the polyethylene glycols, like the io side, that of the one used for image development

Commercially available carbowaxe, and allied ultraviolet light source averted, must carry

Substances such as substituted phenol-ethylene oxide adducts. for radiation of both the wavelength A ₁ and the

For example, those made of o-, m- and p-cresol, o-, m- and wavelength A _{2 can be} permeable.

p-phenylphenol and p-nonylphenol obtained poly- The novel, light-sensitivity described here

ether. Other plasticizers are the acetates, propylene mixtures are borrowed for a wide range of applications

nate. Butyrates and other carboxylate esters from ethylene regions are of considerable use. Such appli-

Glycol, diethylene glycol, glycerine, pentaerythritol and fields of application are for example:
other polyhydric alcohols and alkyl phthalates

and phosphates, such as dimethyl phthalate, diallyl phthalate, _{ χ ) applications in letterpress printing

Dioctyl phthalate, tributyl phosphate, trihexyl phosphate, 20

Trioctyl phosphate, triphenyl phosphate, tricresyl phosphate- Very soft paper, for example silk paper, phat and cresyl diphenyl phosphate. can, if it is with the inventive. light-All components of the light-sensitive mixture according to the invention has been treated. Slightly sensitive mixtures should, in order to avoid being provided with images, by projecting an image onto the foreign constituents in the photoactivating, dyed surface using light-forming and photoinactivating reactions of interfering wavelength A _1. The paper provided with rend intervening, used in a high purity state of the illustration can then easily become. be inactivated by light of wavelength A _4.

The wavelength of light A ₁ is usually between

»Chen 250 and 370 nm and that of light A ₄ 30 ₍₂₎ Sample designs for metalworking
r between 380 and 500 nm. in general this will be

Light of wavelength A ₂ from the oxidizing The photosensitive mixture can be applied to a

Component (quinone) of the redox couple absorbed. The metal surface will be applied when it is in

Light of wavelength A ₁ is appropriately applied by the hexaaryl as a paint or varnish

bisimidazole photooxidant absorbed. The light of 35 turns. The metal surface can then be marked wf'-

Wavelengths A, and A ₂ need not be monochromatic by using a suitable template

do be. Light of a first wavelength several hundred angstrom units wide is irradiated, and that

Gangs are even desirable. Appropriate light- image generated in this way can be achieved by irradiation with light

bands will be easily fixed by using filters of a second wavelength. The picture

receive. Separation filters that remove all light beyond a 40 can, for example, the holes that are drilled

let through a certain length of time, and frequency or other work processes of metalworking

Area filters, which only designate a special band of light processing and production. This technique

let through are suitable. is especially valuable when that is to be marked

Useful means of providing the light A ₁ metal has an irregular shape.

and A ₂ include suitable filters and light sources such as 45

Sunlight, electronic flash lamps, germicidal (3) technical drawings
Lamps, ultraviolet lamps, incandescent lamps, and sunlight. If the photosensitive The molar ratio of bisimidazole photo mixtures according to the invention are applied to paper, they allow in oxydans to aminotriarylmethane color former, 50 diazo copier images can be produced that vary slightly from about 0.1: 1 to about 100: 1 . The range that can be produced in various color gradations is from 1: 1 to 2: 1. The images are then fixed by irradiating with light from a second The quinone component of the redox couple is in the wavelength. Measured at many proportions to the photooxidant. Approaches, this inactivation can be effected by usual useful molar ratios ranging from 0.01: 1 to 55 room light during normal use to 2: 1: a ratio of 0.2: 1 to 0.5: 1. In this case, no particular inactivity is preferred. The reducing component (e.g. tri-ration stage required.
methyl-3.3 ', 3 "-nitrilotripropionate) of the redox couple

is used in a molar ratio of approximately 1: 1 to _{(4) microfiIm and} micro-index cards

about 40: 1 based on the oxidizing component. 60

used. From the mixtures according to the invention can

When used, the mixtures are usually produced recording materials that

I applied as layers on a substrate. Which shines and without heating or treatment with annoying

Supports can be rigid or flexible; solid, porous chemicals can be inactivated. Essence of

or even liquid; either opaque or through- 65 excellent image resolution, strong distortions

be casual to ultraviolet or visible light. reductions are made. These micrographs

Normally, the carrier materials are Pa- enable an expedient and space-saving

pier, any type of tissue paper to heavy card- Method of storing important records.

209 8

_n r

(5) Reflex copying

Reflex exposure methods can be different from that of the invention Make use of the mixture. By means of reflex exposure, copies of information carriers, which have messages on both sides of a sheet or made of impervious material, e.g. B. made of paper, cardboard, metal, or have poorly light-permeable surfaces ♦ earth.

B e i s ρ i e 1 1

The following ingredients became a photosensitive Mixture made:

46 e acetone

3 g polypropylene glycol (molecular weight about 425)
30.2 mg of a mixture of 1,6- and 1,8-pyrenquinone

ok

¹⁵ aceta? was used in place of trimethyl nitrilotripropionate in the mixture described above, and comparable results were obtained.

Example 2

In the photosensitive mixture of Example 1, the color-forming tris (4-diethylamino-otolyl) methane was replaced by bis (4-diethylamino-o-lo! Yl) - (3,4-dimethoxyphenyl) methane, and the p -Toluo isulfonic acid monohydrate amount was reduced to 180 mg. Paper which was treated with this mixture and, as described in Example 1, first through the filter 7-54 and a stencil and then through the filter 0-51, produced a ⁵ ^ ⁸¹ * ⁶⁸ 'gray-colored image against a stable background .

Example 3 ^{In the} mixture of Example 1, the 1,6 and

50 mg p-toluenesulfonic acid monohydrate (1 millimole) tive images 8 ^and 8 in ^{order to obtain a stable} background. ♦ 00 mg trimethyl 3,3'.3 "-nitrilotripropionate ⁵

(2.2 MillimoM example 4

Bleached sulphite paper was coated with about 3 ml of the mixture specified per 1000 cm ^{J and} dried in the air. Through a filter that allows light with wavelengths between 250 and 390 nm to pass (7-54 filter) and through a stencil *, part of the treated paper is irradiated with a flash fcus from a low-pressure xenon flash tube, the energy consumption of which is 200 watt-seconds which emits light distributed between the wavelengths 350 and 650 nm. After the stencil and the filter had been removed, the paper was irradiated through a further filter which transmits light with wavelengths above 390 nm (O-51 filter). Against a stable, white background, a clear, sharp image was visible. Repeated irradiation of the paper on which the image had been created through the second filter showed no visible effect on the quality of the image or any coloring of the background Ip-and. It can thus be seen that in about 10 milliseconds, the duration of a single flash of the flash tube, a complete inactivation of the photosensitive mixture according to the invention is effected by light of a wavelength range above 390 nm. "

If part of the above described photosensitive Paper on which a copy has been produced by exposure through the stencil and the 7-54 filter was exposed to fluorescent light from the environment in the room for about 8 hours a complete inactivation of the background against discoloration by further exposure to ultra-violet Light causes.

Another portion of the paper treated with the photosensitive composition described above became first through the O-51 filter and the template a single flash of light and then only irradiated through the 7-54 filter. In this case it became a stable one negative image generated: i.e. the letters on the stencil appeared colorless against a strongly colored, blue background.

In another experiment, triethyl-nitrilotri- ^The following mass was produced:

30th

35

4 ° ^ _g

3 g polypropylene glycol (molecular weight about 425)

30.2 mg of a mixture of 1,6- and 1,8-pyrenquinone ( ₀₁₃ MiHi ₁₁₁₀ I)

_{6 grams of} cellulose acetate butyrate
_{132 mg} 2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenyl-

bisimidazole (0.2 millimoles) _{120 mg} bis (4-diethyIamino-o-tolyl) - (p-benzylthio-

phenyl) methane (0.23 millimoles) _{130 mg} p-toluenesulfonic acid monohydrate (0.65 millimoles)

_{mg t} rimethyl-3,3 ', 3 "-nitrilotripropionat _(2, 2 millimole)

Paper was coated with this mixture and, as described in Example 1, irradiated. It became a creates a clear, sharp, light gray positive image against a white background.

Example 5

The light-sensitive mixture of Example I was ^{a 's} layer coated on a polyester substrate and irradiated through the filter 7-54 and a template, as previously described. Then there was; imagewise exposed recording material irradiated through the O-51 filter to inactivate the imagewise unexposed parts of the layer. A sharp, blue image became visible on a colorless, transparent background. The background bliet ^De> subsequent exposure to the short-wave light of the flash tube colorless.

B e 1 s ρ 1 e 1 6

65 A photosensitive mixture was made from foleender

Components manufactured:
5

23 g acetone

86 mg of 2,2'-bis (o-chloropher.yl) -4,4 ', 5,5'-tetrapbenylbisimidazole (0.13 millimoles)

Ϊ3

22.5 mg of tris (4-diethylamino-o-toiyl) -metiian

(0.045 millimoles)
100 mg of p-toluenesulfonic acid monohydric acid

(0.5 millimoles)
300 mg trimethyl 3,3 ', 3 "-nitrilotripropionate

(1.1 millimoles)

18.6 mg of a mixture of 1,6- and 1,8-pyrenquinone

(0.08 millimoles).

Bleached sulfite paper was prepared as described in Example 1 with the photosensitive mentioned above Coated mixture. The paper was then dried under an ultra-red lamp until it was • I felt dry and no acetone odor was detected could be. After exposure to a single flash of light through a 7-54 filter and a Template according to the procedure described in Example 1, a blue image was visible. the Trimethyl ester of nitrilotripropionic acid acted as the solvent medium for the image developing reaction. Another part of the treated paper, dried under the ultra-red lamp, was briefly exposed heated on a hot plate and then irradiated as before. There was only a faint, indistinctly visible one Image. The trimethyl ester contained in the mass was completed either by damaging or by decomposition. »Constantly removed. When the paper was moistened with acetone and irradiated again, a sharp, clear picture. From this it can be seen that (1) the trimethyl ester acts as a solvent, (2) one of Solvent relatively free mass fails in image development and does not respond and (3) Photosensitivity is restored by introducing a solvent.

Example 7

A mass was made from the following components:

60 ml of acetone

0.4180 g of 2,2'-bis (o-chlorophenyl) -4,4 ', 5 _: 5'-tetri' is- (m-methoxyphenyl) -bisimidazo!
(5.36 x 10- 'moles)

0.0900 g tris (4-diethyiamino-o-tolyl) methane
(1.8 × 10 ^-5 mol)

0.400 g of p-toluenesulfonic acid monohydrate

(2.1 x 10 ^-3 mol)
1.0 ml trimethyl-3,3 ', 3 "-nitrilotripropionLt

(4.2 · ΙΟ " ³ mol)

0.054 g of 9,10-phenanthrenequinone (2.6 x 10 " ⁴ mol)
6.0 g of cellulose acetate butyrate

3.0 g of a polyethylene oxide adduct of o-phenylphenol, which had been prepared from 2.25 mol of ethylene oxide per mol of phenol and the average formula

C ₆ H ₅ - C ₆ H ₄ - 0 (CH ₂ CH ₂ O) ₂₁₂₅ H
corresponded.

A very tough calendered, bleached sulfite paper was made with the above Coated mixture. The paper was dried under a stream of hot air until the surface was no longer sticky. After exposure to a single flash of light through a 7-54 filter and a stencil according to the procedure described in Example 1, a blue image became visible. The picture was then completely stable against visible light. The background areas could be exposed to radiation can be bleached white with daylight.

2098

Claims (3)

Patent claims: 1. Photosensitive mixture which is activated to form color by light of a wavelength A ₁ and which is made insensitive to light by exposure to light of a second wavelength A _{2 and that} (a) a colorless, stable under normal conditions, which forms a dye on oxidation nitrogen-containing organic compounds as color former, (b) a hexarylbisimidazole which, when exposed to light with a wavelength A ₁ of 250 to 370 nm, is capable of oxidizing the color former to form the dye, as a photo-oxidizing agent and (c) a redox couple which can be initiated with light of wavelength A ₂ and which prevents the photo-oxidative dye formation of the color former with light of wavelength A ₁ , and (d) optionally contains an inert solvent, characterized in that it is a color former (a) a salt of an acid and a practically colorless, oxidizable, substituted aminotriarylmethane and a redox couple (c), the from (1) an oxidizing component from the group of pyrenquinone and phenanthrenequinone and (2; a compound of the general formula N [(CH ₂ ) "COOR] ₃ , in which η is the integer 1 or 2 and R is a straight-chain alkyl group of 1 to 4 carbon atoms, as a reducing agent, contains. 2. A method for producing fixed, light-insensitive, negative images, characterized in that a light-sensitive mixture according to claim 1, which is optionally located on a layer support, is first _{exposed to light with a wavelength A 1} of 250 to 370 nm through a master copy and then totally exposed to light of a different wavelength A _2. 3. A method for producing fixed, light-insensitive, positive images, characterized in that a light-sensitive mixture according to claim 1, which is optionally located on a layer support, is first _{exposed to light with a wavelength A 2} of 380 to 500 nm through an original and then totally exposed to light of a different wavelength A, from 250 to 370 nm. 55 The invention relates to a photosensitive mixture which is _{activated to form color by light of a wavelength A 1} and which becomes light-insensitive by exposure to light of a second wavelength A _{2 and that} (a) a colorless, stable under normal conditions, Nitrogen-containing organic compounds that form a dye in the event of oxidation as a color former, (b) a hexarylbisimidazole which, when exposed to light with a wavelength A ₁ of 250 to 370 nm, is capable of oxidizing the color former to form the dye, as a photo-oxidizing agent and (c) a redox couple which can be initiated with light of wavelength A _{1 and which} prevents the photo-oxidative dye formation of the color former with light of wavelength A 1, and (d) optionally contains an inert solvent.