DE1166618B - Silver halide photographic material - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: G 03 c

German class: 57 b -8/02

Number: 1166 618

File number: G33183IXa / 57b

Filing date: September 22, 1961

Opening day: March 26, 1964

It is known that light-sensitive photographic emulsions are made at high temperature and relative humidity or in a room in which these emulsions with certain substances come into contact, e.g. B. with hydrogen sulfide, hydrogen peroxide vapor or reducing agents Compounds, stored, show a tendency to decrease in their sensitivity and without preceding Exposure can be developed by itself. This phenomenon is called a "chemical veil" to distinguish it from the haze of light, that of unwanted exposure originates. The formation of fog depends on the type of emulsion and the age, temperature and temperature relative humidity in storage proportional.

It is also known that the silver image formed on exposure during its conversion a degradation to a visible image, d. H. a shift and a decrease in the intensity of the Image tones, among other things under the influence of the constituents used in the developing bath, fixing bath and dye bath, learns. This degradation is particularly noticeable during the drying of the developed Images, where in addition to a decrease in density and gradation also an undesirable color or Metallic appearance of the developed silver, the so-called »bronzing«, is determined. This Phenomenon occurs when mirroring the photographic Pictures stand out very strongly.

Various compounds are already used as stabilizers, anti-fogging agents or anti-bronzing agents has been proposed. However, the majority of these compounds have the disadvantage of only within to be active within certain limits and usually a strong desensitizing effect on the emulsion exercise.

It has now been found that the compounds of the class of 4,5-substituted oxazoline-2-thiones following general formula:

.0. Silver halide photographic material

Applicant:

Gevaert Photo-Producten N.V.,

Mortsel, Antwerp (Belgium)

Representative:

Dr. W. Müller-Bore and Dipl.-Ing. H. Gralfs,

Patent attorneys, Braunschweig, Am Bürgerpark

Named as inventor:
Dr.-Chem. Jozef Frans Willems,
Dr.-Chem. Gerard Michiel Sevens,
Wilrijk, Antwerp (Belgium)

Claimed priority:

Belgium 23 September 1960 (595 325)

-NH

R ₂

in which R ₁ and R _{2 are} identical or different and each represent an alkyl radical, a substituted alkyl radical, an aryl radical, a substituted aryl radical, an alkaryl radical or a substituted alkaryl radical or together are those required to close a saturated homocyclic ring or a substituted saturated homocyclic ring Are atoms, are effective anti-bronzing agents in copy emulsions and at the same time have a stabilizing and anti-fogging effect on the light-sensitive photographic emulsions without impairing the sensitivity.

Connections of this type are for example:
4,5-dimethyloxazolin-2-thione,
4,5-dipropyloxazoline-2-thione,
4,5-diphenyloxazolin-2-thione,
4- (p-DimethyIamino) -5-phenyloxazolin-2-thione,
4- (p-methoxyphenyl) -5-phenyloxazolin-2-thione,
Tetrahydrobenzoxazoline-2-thione.

According to R. Gompper, Ber. 89 (1956), p. 1762, or in a simpler manner by the following methods.

Manufacturing 1
4,5-diphenyloxazoline-2-thione

A solution of 145.5 g (1.5 mol) of potassium thiocyanate in 2 l of ethanol is introduced into a three-liter flask equipped with a reflux condenser and dropping funnel. After adding 150 cm ^{3 of} hydrochloric acid (D. = 1.19), the precipitated potassium chloride is filtered off. 212 g (1 mol) of benzoylphenylcarbinol (benzoin) are added to the filtrate, and this mixture is refluxed for 24 hours. After cooling, the filtrate obtained is washed with 4 l of water

409 540/445

added, which results in a new precipitate. After filtering off and rinsing, this second precipitate is added to the first one obtained. The combined precipitates are dissolved in 1 normal aqueous sodium hydroxide. The undissolved, unreacted benzoin crystals are filtered off and purified by recrystallization from ethanol. Yield: 23 g. Melting point: 135 to 136 ^C C.

The filtrate is acidified with acetic acid. The precipitate formed is filtered off, watered, dried and recrystallized from ethylene glycol monomethyl ether. Yield: 217 g (86%) Melting point: 260 ° C.

Manufacturing 2
4- (p-methoxyphenyl) -5-phenyloxazolin-2-thione

^{A solution of 24.2 g of p-methoxybenzoin in 200 cm 3 of} ethanol is placed in a half-liter flask equipped with a reflux condenser. A solution of 15 g of potassium thiocyanate in 20 cm ^{3 of} water and 14 cm ^{3 of} concentrated hydrochloric acid (D. = 1.19) is then added one after the other. This reaction mixture is refluxed for 6 hours.

After cooling, the precipitate formed is filtered off with suction and watered. The precipitate is out a mixture of ethanol and water (50:50) recrystallized.

Hey tellune,

4,5-dimethyloxazolin-2-thione

A solution of 17.6 g of 3-oxy-2-butanone (acetoin) in 200 cm ^{3 of} ethanol and a solution of 29.1 g of potassium thiocyanate in 40 cm ^{3 of} water are placed in a half-liter flask equipped with a reflux condenser. After adding 60 cm ^{3 of} concentrated hydrochloric acid (D. = 1.19), the reaction mixture is heated under reflux for 6 hours.

After cooling, the potassium chloride formed is filtered off and washed with ethanol. The filtrate is concentrated and the resulting crystals are filtered off with suction. The product obtained is recrystallized from water. Melting point: 137 ⁰ C.

Manufacturing 4
4,5-dipropyloxazole m-2-thione

A solution of 84 g of 5-oxy-4-octanone (butyroin) in 1.21 of ethanol and a solution of 175 g of potassium thiocyanate in 240 cm ^{3 of} water are placed in a three-liter flask equipped with a reflux condenser. After adding 360 cm ^{3 of} concentrated hydrochloric acid (D. = 1.19), the reaction mixture is heated under reflux for 6 hours. After cooling, the potassium chloride formed is filtered off. The filtrate is concentrated and the residue is distilled in vacuo. The fraction with the boiling range 128 to 140 ^° C. at 0.003 to 0.006 mm Hg pressure is a yellow oil which solidifies on cooling.

Manufacturing 5
Tetrahydrobenzoxazohn-2-thione

In a half-liter flask equipped with a reflux condenser, 1.4 g Λ-oxycyclohexanone is dissolved in 200 cm ^{3 of} methanol. A solution of 29 g of potassium thiocyanate in 40 cm ^{3 of} water and 60 cm ^{3 of} concentrated hydrochloric acid (D. = I, 19) are successively added to this solution. The reaction mixture is refluxed for 6 hours. After cooling, the potassium chloride formed is filtered off with suction and the filtrate is evaporated. The precipitate formed is filtered off and recrystallized from a mixture of 'water and ethanol (50:50). Melting point: 154 ^C C.

The compounds to be used according to the invention are preferably used after chemical ripening or added immediately before the coating of the emulsion.

Instead of the halogen silver emulsion, the compounds can also have a water-permeable layer, such as a gelatin top layer or an intermediate layer in contact with the emulsion layer,

* 5 can be added. The emulsions used can be _{sensitized to the extent that} they are used. They can be chemically sensitized by small amounts of sulfur-containing compounds, for example allyl isothiocyanate, allyl thiourea, sodium thiosulphate, etc.

They can also by reducing agents, for example the tin compounds described in Belgian patents 493 464 and 568 687, the iminoaminomethanesulfinic acid compounds described in the accompanying patent 547 323, or by small amounts of noble metal compounds such as compounds of gold, platinum, palladium, iridium, ruthenium and rhodium , be made aware. It is also possible to sensitize the emulsions with polyalkylene oxide derivatives, e.g. B. polyethylene oxide of _Mo i _eku iargewichts 1000-20000, with condensation products of alkylene oxides and aliphatic alcohols, glycols, cyclic dehydration products of hexitols, alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides. The condensation products have a molecular weight of at least 700, preferably more than 1000. To achieve special effects, these sensitizers can of course be used in combination, as is described in Belgian patent 537 278 and British patent 727 982.

Furthermore, these compounds can be optically sensitized as well as non-optically sensitized emulsions can be used.

_The compounds according to the invention can be used with advantage as anti-bronzing agents in all emulsions for photographic silver halide copying materials; especially in photographic copy emulsions which are glossy after development.

The amount of stabilizer can vary depending on the type of halogen silver or mixture used, the degree of ripening, the presence or absence of other emulsion additives, such as dye formers, optical bleaching agents, antioxidants, compounds which affect the image tone, etc .; in general, however, the stabilizers are added in an amount of from 0.001 to 0.35 g per mole of halosilver, if also, e.g. B. to achieve special effects, larger amounts can _{be added}

The following example illustrates the invention without restricting it in any way.

.

example

A silver chloride emulsion is poured onto a paper support (0.6% iodide) for reproductive

purposes that are sensitized for the spectral range from 500 to 570 πψ and that were produced with 45 g of silver nitrate per kilogram of emulsion. A strip of this material is exposed behind a step wedge and, after a visible image has been obtained, the material is subjected to accelerated drying by passing it over a glossy drum in such a way that the reverse side is pressed against the glossy drum. This stripe shows a disturbing rust-brown color (so-called bronzing) in the exposed parts, especially in the pointed lights. A strip of material which is coated with the same emulsion, but to which 20 cm ^{3 of} a 0.5% strength alcoholic solution of 4,5-diphenyloxazoline-2-thione was added per kilogram of emulsion, is treated in a similar manner. After a visible image is obtained, no trace of rust-brown color can be seen. The measurement of the maximum densities by reflected incident light gives the following results:

Emulsion without stabilizer 1.28

Emulsion with stabilizer 1.37

Claims (1)

Claim: Photographic silver halide printing material characterized in that at least one of the colloid layers of this material is a compound of the general formula R ₁ - - = S NH contains, in which R ₁ and R _{2 are the} same or different and each represent an alkyl radical, a substituted alkyl radical, an aryl radical, a substituted aryl radical, an alkaryl radical or a substituted alkaryl radical, or together are those for closing a saturated homocyclic ring or a substituted saturated homocyclic Ringes are required atoms. Considered publications:
"Journal for Scientific Photographic", 1952, Vol. 47, Issue 1 to 3, pp. 3, 6, 19.