EP0167081A2 - Silver halide photographic recording material - Google Patents

Abstract

The photographic silver halide recording material contains, in at least one of its outer layers, dispersed in a hydrophilic colloid, particles of a hydroxyalkyl-alkyl cellulose dicarboxylic acid semi-ester having a particle size of 0.5 to 8 μm and a particle size distribution of up to ± 2 μm.

Description

The invention relates to a photographic silver halide recording material which, in an outer transparent layer attached to the front and / or back, dispersed in a hydrophilic colloid, contains particles of cellulose ether dicarboxylic acid semiesters with a particle size of less than 10 μm which are soluble in alkaline processing liquids.

The hydrophilic colloids, for example gelatin, usually contained in the outer layers of silver halide photographic recording materials lead to an increase in the stickiness of the recording materials at high atmospheric humidity and higher temperatures, so that such recording materials easily stick to one another, for example after being packaged in a stack. This tendency to stick between different parts of the recording material or between the recording material and other materials which come into contact with it leads to the Camera, in the production, processing, projection or storage of the recording material to numerous difficulties.

To overcome these difficulties, it is known to matt the outer layers of recording materials by incorporating finely powdered inorganic compounds, such as silicon dioxide, magnesium oxide, titanium dioxide or calcium carbonate, or organic compounds, such as polymethyl methacrylate or cellulose acetate propionate, and thus reducing their stickiness. However, this "matting" has several disadvantages. For example, do not make the outer layer homogeneous, since the fine powder components mentioned aggregate easily in the coating solution. In addition, recording materials with an outer layer containing the fine powdery materials are more easily damaged and are more difficult to transport in a camera or a projector because their surface is not sufficiently slippery. The presence of the fine powdery materials in the outer layer further reduces the transparency of the recording material after processing and increases the graininess of the image.

DE-OS 2 758 767 discloses a photographic light-sensitive material which has an outer light-insensitive gelatin layer which contains colloidal silica particles with a size of 7 to 120 nm and a polymeric latex, the particles of which are 30 to 80 nm in size. This gelatin layer gives the photographic material increased fracture and dimensional stability.

However, a disadvantage of such a photographic material is that the additives reduce the transparency of the layers and, particularly at higher humidities (for example more than 85% RH) and temperatures around 35 to 40 ° C., it is unavoidable to avoid sensitive contact spots when rolling up the materials .

Various processes are known for producing fine-grained materials with a matting effect. Thus, polymer particles with a particle diameter of about 5 to about 0.01 μm can be produced by emulsion polymerization if the amount of the emulsifier (surface-active agent), the polymerization temperature and the stirring conditions are suitably controlled. The procedure is e.g. by H. Reinhard, "Dispersions of Synthetic High Polymers", Part II, page 3 ff., Springer Verlag or by F. Hölscher in the corresponding Part I, page 31 ff. In this way, however, only particles can be produced whose average size differs by at least 2 pm, that is to say which have a relatively non-uniform particle size. Mechanical pulverization, which is followed by classification according to particle sizes, gives polymer particles with a broad particle size distribution, the shape of which is not spherical but rather completely irregular.

Spherical polymer particles can be prepared by dissolving a polymer in a water-immiscible organic solvent and spraying the solution from a fine nozzle into an aqueous Medium under high pressure. So far, there is generally no usable, economical process for producing uniform polymer particles with a particle size within the range from 1 to 10 μm.

Fine-particle polymer particles can also be produced by dispersing. To this end, one or more polymers are dissolved in a solvent which is insoluble or essentially immiscible in water and has a lower boiling point than water or forms an azeotropic mixture with water having a lower boiling point than water. The polymer solution is dispersed in an aqueous medium as a dispersing agent in the form of droplets, the viscosity and surface tension being adjusted in a suitable manner and the solvent being removed from the droplets to form fine polymer particles. Can this partial c _h by subsequent centrifugation and drying are separated (DE-OS 2522692) in the form of a powder.

_P räformierte water-insoluble polymer particles having a relatively narrow particle size distribution which are suitable as a matting agent for photographic layers are obtainable by suspension copolymerization of maleic anhydride and 1-olefins (DE-Open Nos 2,501,124, 2,919,822 and 3,144,793). The process leads to particles which occur in sufficient uniformity with regard to the particle size, the particles are each but insoluble in alkali. They therefore remain on the surface after the processing of the photographic material and thus increase the granularity of the light-sensitive material.

There has been no shortage of attempts to find alkali-soluble polymer particles which are removed from the surface during processing in alkaline processing liquids. For this purpose, reference is made to the publications US Pat. No. 2,322,037, GB Pat. No. 878,520, US Pat. No. 4,094,848, US Pat. No. 4,142,894, GB Pat. No. 2,012,978 and GB Pat. No. 1,055,713, and to DE OS 3 331 542.

The known graft polymers soluble in alkaline medium, based on methacrylic acid and methyl methacrylate based on copolymers of styrene-maleic acid, as the graft base, have the disadvantage that, in the absence of gelatin, they partially dissolve at pH values around 6.2-6.5 in the absence of gelatin . Since the small particles in particular dissolve, the entire size distribution of the particles changes and forces them to use larger quantities. The viscosity of the casting solution increases and must therefore be continuously monitored. The premature dissolution of the particles is particularly disadvantageous if additives, such as silica sols, are added to the casting solution which are alkaline due to their preparation and for the purpose of stabilizing the solutions. The use of the known alkali-soluble matting particles therefore leads to difficulties during pouring and drying, because the matting particles can already be dissolved at the pH of the emulsion layers. In solutions with a low buffer capacity, the alkali-soluble matting particles are generally protected by the fact that the pH value decreases continuously when the particles are dissolved. Then a certain pH value can be set that is favorable for the particles. However, if the casting solutions or the layer structure have a pH value above 6.5 and the buffer capacity is large, then the particles dissolve increasingly without the aforementioned favorable pH value being reached, ie the desired matting effect is lost.

The invention has for its object to develop a photographic material whose outer layers have no tendency to stickiness, which have a high gloss and high transparency after processing of the photographic material, and whose casting solutions are stable at pH values up to 7.

The invention relates to a photographic silver halide recording material which, in an outer transparent layer attached to the front and / or back, dispersed in a hydrophilic colloid in alkaline processing liquids, contains soluble particles with a particle size of less than 10 μm, and which is characterized in that the layer 10-500 mg / m ² spherical transparent particles of a hydroxyalkyl-alkylcellulose-dicarboxylic acid half-ester with a particle size of 0.5-8 pm and one Contains particle size distribution of up to + 2 _j dispersed.

The hydroxyalkyl-alkyl cellulose dicarboxylic acid esters used in the outer layer of the recording material of the invention - hereinafter called "cellulose derivatives" for short - are insoluble in gelatin-containing casting solutions at pH values below 7, but dissolve slightly above pH 8. The solubility increases within a small pH interval above pH 7.2.

beschreiben, in der bedeuten

• A einen Glucoserest der Cellulosestruktur
• _R ¹ einen Hydroxyalkylrest mit 2 bis 4 Kohlenstoffatomen,
• _R ² einen Alkylrest mit 1 bis 3 Kohlenstoffatomen,
• _R ³ den Monoacylrest einer Benzoldicarbonsäure oder einer solchen Säure in partiell oder voll hydrierter Form,
• m 0,2 - 1
• n 0,8 - 2,0 und
• p 0,5 - 1,5

wobei m # n ; p und die Summe m + n + p höchstens 3 ist. (Die Zahlen bedeuten Mol.)The cellulose derivatives used according to the invention can be represented by the general formula

describe in the mean

• A a glucose residue of the cellulose structure
• _R ^{1 is} a hydroxyalkyl radical with 2 to 4 carbon atoms,
• _R ^{2 is} an alkyl radical with 1 to 3 carbon atoms,
• _R ^{3 is} the monoacyl radical of a benzenedicarboxylic acid or such an acid in partially or fully hydrogenated form,
• m 0.2 - 1
• n 0.8 - 2.0 and
• p 0.5 - 1.5

where m # n; p and the sum m + n + p is at most 3. (The numbers mean moles.)

Examples of the above-mentioned dicarboxylic acid monoesters are esters of phthalic acid, tetrahydrophthalic acid or hexahydrophthalic acid. In the cellulose derivatives of the invention, these dicarboxylic acid monoesters are mixed via one of their carboxyl groups with mixed ethers of cellulose, e.g. B. hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl ethyl cellulose or hydroxypropyl ethyl cellulose, esterified. The content of dicarboxylic acid monoester in the cellulose derivatives should be adjusted in accordance with the hydrophobizing effect of the cellulose ether so that the desired solubility is achieved in alkaline solution. The compounds can be produced in a simple manner by the process given in DE-OS 2 841 164.

The cellulose derivatives are used in an amount of 10 to 500 mg / m ² , preferably 80 to 150 mg / m ² , per layer.

• Verbindung
  • A. 17,4 Gew.-% Methoxy-Gruppen 7,2 Gew.-% Hydroxypropoxy-Gruppen 35,0 Gew.-% Hexahydrophthaloyl-Gruppen.

Particularly suitable cellulose derivatives have e.g. B. The following composition:

• connection
  • A. 17.4% by weight methoxy groups 7.2% by weight hydroxypropoxy groups 35.0% by weight hexahydrophthaloyl groups.

• Verbindung
  • B. 18,0 Gew.-% Methoxy-Gruppen 9,0 Gew.-% Hydroxypropoxy-Gruppen 35,0 Gew.-% Phthaloyl-Gruppen.

The term "phthaloyl" is used here and below for the grouping -CO-C ₆ H ₅ -COOH.

• connection
  • B. 18.0 wt% methoxy groups 9.0 wt% hydroxypropoxy groups 35.0 wt% phthaloyl groups.

So-called stabilizers can be added to the cellulose derivatives introduced into the outer layers of the photographic material.

Compounds which counteract dissolving of the cellulose derivatives during digestion are suitable as stabilizers. The known oil formers with free carboxyl groups used in the production of silver halide emulsions have proven to be usable in principle for this purpose.

With an amount of 1 to 30 wt .-% of stabilizing compound, based on the cellulose derivative, the desired effect is achieved in any case.

Compounds from the group mentioned which are suitable as stabilizers are e.g. described in DE-PS 1 772 192. The preparation of the compounds is well known and can e.g. by reacting monoalkylated cyclic carboxylic acid anhydrides with alcohols or amines.

The following compounds may be mentioned as examples of very suitable stabilizers:

In the following formulas, R represents one of the monounsaturated aliphatic radicals -C ₁₂ H ₂₃ , -C ₁₅ H ₂₉ or -C ₁₈ H ₃₅ , the formation of which can be explained by multiple addition of propylene.

The stabilizers can be added to the casting solutions of the outer layers before the dispersing process, in amounts of 1 to 30% by weight and preferably 2.5 to 10% by weight, based on the solids content of cellulose derivative.

The following describes the preparation of dispersions of the cellulose derivatives in gelatin:

Dispersion 1

Particles of hydroxypropylmethyl cellulose hexahydrophthalic acid half ester in gelatin.

1000 ml of water are placed in a 5 liter beaker. 100 g of gelatin are added with stirring. The gelatin is left to swell for 30 minutes and melted.

100 g of hydroxypropylmethyl cellulose hexahydrophthalic acid half-ester (compound A) are dissolved in 900 ml of methylene chloride and 30 ml of a 10% strength by weight solution of a fluorosurfactant in ethanol are stirred in. After filtration, this solution is added to the gelatin solution. The mixture is then intensively dispersed for 2 minutes using a mixer.

The particle size obtained is 1-4 pm. The excess methylene chloride is now removed at 40 ° C. with slow stirring. Then the dispersion is filtered through a filter with a pore size of 10 pm and solidified in a cooling dish. Contain 1200 g of dispersion 100 g cellulose derivative. The particle size varies between 1 and 4 pm. The distribution of the particle size is shown in Figure 1.

FIGS. 1, 2, 4 and 5 show the frequency distribution of the particle diameters of the cellulose derivatives indicated as the frequency density (1 / μ) corresponding to the individual particle diameters (pm). Each of the representations also contains the associated cumulative frequency curve (integral distribution).

Dispersion 2

Hydroxypropylmethyl cellulose hexahydrophthalic acid half ester and stabilizer No. 12 dispersed in gelatin.

• 985 ml Wasser
• 15 g Gelatine und
• 3,2 g Phenol.

A solution I is made from

• 985 ml of water
• 15 g gelatin and
• 3.2 g phenol.

• 25 g Hydroxypropylmethylcellulosephthalsäurehalbester (Verbindung B)
• 250 g Essigsäureethylester
• 2,5 g Stabilisator Nr. 12 (50 gew.-%ig in Ethanol)
• 0,8 g Dibutylnaphthalinsulfonat (75 gew.-%ig in Wasser)

A solution II of the following composition is prepared separately:

• 25 g hydroxypropylmethyl cellulose phthalic acid half-ester (compound B)
• 250 g of ethyl acetate
• 2.5 g stabilizer No. 12 (50% by weight in ethanol)
• 0.8 g dibutylnaphthalenesulfonate (75% by weight in water)

Solution II is emulsified in solution I. The ethyl acetate is then evaporated off under reduced pressure. Then 367 g of a 15% by weight aqueous gelatin solution are added. After mixing, the dispersate is solidified at 5 ° C.

The particle size is between 1 and 4 µm.

The particle size distribution is shown in FIG. 2.

FIG. 3 shows an electron microscopic image of the cellulose derivative particles in a magnification of 10,000 times.

Dispersion 3

_H ydroxypropylmethylcellulosehexahydrophthalat (Compound A) and stabilizer no. 12 in gelatin.

• 9,85 1 Wasser
• 0,15 kg Gelatine
• 0,032 kg Phenol

In a solution from

• 9.85 1 water
• 0.15 kg gelatin
• 0.032 kg phenol

• 0,25 kg Cellulosederivat Verbindung A
• 0,025 kg Stabilisator Nr. 12
• 2,5 kg Essigsäureethylester und

Will be a mix of

• 0.25 kg cellulose derivative compound A
• 0.025 kg stabilizer No. 12
• 2.5 kg of ethyl acetate and

(75 Gew.-% in Wasser) als Netzmittel0.008 kg of compound

(75% by weight in water) as a wetting agent

emulsified at 35 ° C with an emulsifying device. After evaporating off the volatile organic matter

Obtained 10.3 kg of dispersion, in addition to 3.67 kg of 15 wt .-% aqueous gelatin solution

be added. The finished dispersion contains 0.25 kg of cellulose derivative. The particle size is between 1 and 6 _Nm . The particle size distribution is shown in FIG. 4.

Dispersion 4-9

Particles of hydroxypropylmethyl cellulose hexahydrophthalate (compound A) and various stabilizers.

Corresponding information for dispersion 3, further dispersions are produced, the stabilizers indicated in the table below being used instead of stabilizer 12.

The particle size distributions and the particle sizes of the cellulose derivative of the dispersions mentioned correspond to the illustration in FIG. 5.

₅ The cellulose derivative particles of the dispersions have a spherical shape and are transparent. They are obtained in particle sizes of 1-7 pm and preferably 1-5 µm.

Since an essential prerequisite for the usability of these particles is their insolubility in the acidic environment, in particular in the pH range between 6 and 7, on the one hand and their rapid and good solubility in the alkaline environment of photographic developer solutions (pH greater than 8), this is necessary Build up particles 15 both in terms of their molecular weight and their content of carboxyl groups in such a way that they meet the criteria mentioned.

In no event-linked or cross-linking process ₂₀ are suitable-products, in other words, the cellulose derivatives must be free of microgels. This can be done detect by dissolving the particles in 1% aqueous Na ₂ CO ₃ solution and determining the microgel content in the solution using an ultracentrifuge.

The dispersions obtained in the manner described can be distributed in aqueous solutions of hydrophilic colloids with any wetting agents. As hydrophilic colloids, e.g. the following compounds are used: proteins, such as gelatin, gelatin derivatives, e.g. acetylated gelatin, phthaloyl gelatin or succinyl gelatin, albumin, casein, gum arabic, agar agar, alginic acid, cellulose derivatives e.g. Alkyl esters of carboxymethyl cellulose, preferably the methyl or ethyl esters, hydroxyethyl cellulose, carboxymethyl cellulose, synthetic polymers e.g. Polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, salts of polyacrylic acid, salts of polymethacrylic acid, salts of polymaleic acid, salts of polystyrene sulfonic acid, preferably the sodium or potassium salts and copolymers which contain at least one of the monomers of the polymers mentioned above. Among these hydrophilic colloids, amphoteric polymeric electrolytes, such as gelatin, gelatin derivatives, casein and other protein compounds, have a particularly pronounced effect. The hydrophilic colloids can also be used individually or in combination. Preferred colloids include gelatin, gelatin derivatives, casein and other protein compounds. The colloid is advantageously used in an amount of about 1 to about 15% by weight, preferably in an amount of 5 to 10% by weight, in each case based on the weight of the dispersion.

A further 0.1 to 1% by weight of surface-active agents, based on the weight of the water present, can be added to the aqueous solutions containing the dispersion. Examples of suitable surfactants are saponin and other compounds of natural origin, nonionic surfactants such as polyalkylene oxides, glycerol compounds such as monoglycerides or glycidol compounds, anionic surfactants with one or more acid groups, such as one or more carboxylic acid, sulfonic acid, phosphoric acid, sulfonic acid esters - or phosphoric acid ester groups. Particularly suitable surface-active agents are described in US Pat. Nos. 2,271,623, 2,240,472, 2,288,226, 2,676,122, 2,676,924, 2,676,975, 2,691,566.2 721,860, 2,730,498, 2,742,379, 2 739 891, 3 068 101, 3 158 484, 3 201 253, 3 210 191, 3 294 540, 3 415 649, 3 441 413, 3 442 654, 3 475 174 and 3 545 974, in DE-OS 1 942 665 and in the G _B -Psen 1 077 317 and 1 198 450 as well as in "Kaimen Kassi Zai no Gosei to Sono Ohyo" (Synthesis and Application of Surface Active Agent) by Ryohei Oda et al (published by Maki Publishing Co, 1964 ), "Surface Active Agents" by JW Perry and AM Schwartz (published by Interscience Publications Inc., 1958), "Encyclopedia of Surface Active Agents", Volume 2, by JP Sisley (published by Chemical Publishing Co., 1964) "Kaimen Checkouti Zai Binran (Surfactants Encyclopedia) ", 6th edition (published by Sangyo Tosho Co., Dec. 20, 1966) and the like. Fluorine-containing wetting agents as described, for example, in DE-OS 1 961 638 can also be used.

worin R' Wasserstoff oder eine Alkylgruppe mit 1 bis 18 Kohlenstoffatomen, R" eine Alkylgruppe mit 1 bis 18 Kohlenstoffatomen, M eine Alkalimetall- oder Ammoniumion, m eine positive ganze Zahl von 0 bis 20 und n die Zahl 3 oder 4 bedeuten.These surface-active agents can also be used alone or in the form of combinations, and particularly suitable compounds are those with an OSO ₃ M group, such as, for example, sulfonate esters of common alcohols of the general formula RO-S0 ₃ M or R- (OCH ₂ CH ₂ ) _n -OS0 ₃ M (wherein R is an alkyl group having 8 to 30 carbon atoms, M is an alkali metal or ammonium ion and n is a positive integer of up to 20) and alkylbenzenesulfonic acid compounds having the general formula

wherein R 'is hydrogen or an alkyl group having 1 to 18 carbon atoms, R "is an alkyl group having 1 to 18 carbon atoms, M is an alkali metal or ammonium ion, m is a positive integer from 0 to 20 and n is 3 or 4.

The dispersions containing the cellulose derivatives can either be added directly to the photographic casting solutions for the outer layer or the cellulose derivative particles can be isolated in the form of pastes as a solid residue by centrifugation. The cellulose derivatives are photographically inert and do not change the granularity of the recording material if they are added to the layers in the appropriate amount of 10 to 500 mg / m ² .

The advantageous surface roughening achieved with the cellulose derivatives of the invention can be further improved by adding colloidal silica in the form of a hydrosol to the casting composition containing the cellulose derivatives before it is applied to the surface of the photographic material. Good results are obtained with commercially available hydrosols with a particle size of 50 to 150 nm, which are added to the casting composition in amounts of 0.5 to 2 parts by weight, based on 1 part by weight of the hydrophilic colloid. The silica particles introduced with the hydrosol differ by orders of magnitude from the cellulose derivatives of the invention and are therefore not involved in their specific action. The proportion of the silica particles in the overall effect is merely that they further suppress the already slight tendency of the surface layers produced by the process of the invention to form gloss spots or color spots.

If desired, the casting compositions used to produce the outer layers according to the invention may contain further additives which have no influence on the desired surface quality. Examples include: very fine-grained (Ø <0.1 µm) latices of hard polymers such as polystyrene, polymethyl methacrylate. Furthermore, very fine-grained (particle diameter <0.1 _Nm ) latices of soft homopolymers and copolymers, such as polyethyl acrylate, butyl acrylate of polyacrylate, or latices of polyethers or polyester polyurethanes, as described in the journal Research Dischlosure, Dec. 1978, Industrial Opportunities Ltd. Hampshire, UK, page 27 (XII A), also conductivity-increasing compounds as described in "Research Disclosure", December 1978, page 27 (XIII A), and finally curing agents as described in "Research Disclosure", December 1978, page 26 under (X) and pouring aids as described under (XI), further lubricity-increasing agents, such as silicone oil dispersions and substances that increase the viscosity of the casting solution.

Good results are obtained with homopolymers or copolymers whose particles are smaller than 0.1 pm and whose glass transition temperature is at least 40 ° C. The polymers can be added to the layers in amounts of up to 50% by weight, based on the dry content of hydrophilic colloid.

The outer layers of the invention can be used to add the hardener to the gelatin layers of the photographic material. In this known hardening process by overlaying a hardening agent, the hardening agent reaches the deeper layers by diffusion. It is possible, for. B. harden a color photographic multilayer material in one step. The so-called fast-acting hardening agents are particularly common for this method of working. Examples of such curing agents are N-carbamoyl and N-carbamoyloxypyidinium compounds (US Pat. No. 3,880,665), sulfo group-containing N-carbamoylpyridinium compounds in the form of the free betaines or their metal salts (US Pat. No. 4,036,952), 2-alkoxy-N-carboxydihydroquinoline esters (DS-PS 4 013 468), _I soxazoliumsalze (US-PS 3 321 313) or carbodiimides ( _DE -PS 1 148 446 and DE-OS 2 439 553).

The cellulose derivatives used according to the invention can advantageously be used in the protective or surface layers of black and white photographic materials, in color materials and in the so-called non-curling layers of roll and small picture films or flat films.

example 1

• 400 g Gelatinelösung 15 %ig
• 2.800 g Wasser (entsalzt)
• 80 g Netzmittel der Formel
  
• 4 %ig in Wasser

The following casting compositions are produced for the production of a surface protective layer (percentages in the following mean percentages by weight, unless stated otherwise):

• 400 g of 15% gelatin solution
• 2,800 g water (desalinated)
• 80 g wetting agent of the formula
  
• 4% in water

The cellulose derivatives in the form of their dispersions are stirred into this composition.

zugesetzt. Naßauftrag der Gießzusammensetzungen: 50 g/m²; pH 6,5-7,0Shortly before the coating composition is applied, 2,000 g of a 10% strength by weight aqueous solution of the curing agent of the formula

added. Wet application of the casting compositions: 50 g / m ² ; pH 6.5-7.0

• 1-A Vergleichsprobe, ohne erfindungsgemäßes Cellulosederivat,
• 1-B Gießlösung enthaltend 50 g der Dispersion 1
• 1-C Gießlösung enthaltend 225 g der Dispersion 2
• 1-D Gießlösung enthaltend 225 g der Dispersion 3
• 1-E Gießlösung enthaltend 225 g der Dispersion 4

The following casting compositions are produced in accordance with the above recipe:

• 1-A comparative sample, without a cellulose derivative according to the invention,
• 1-B casting solution containing 50 g of dispersion 1
• 1-C casting solution containing 225 g of dispersion 2
• 1-D casting solution containing 225 g of dispersion 3
• 1-E casting solution containing 225 g of dispersion 4

In addition, casting compositions are produced as comparative samples which, instead of the cellulose derivatives according to the invention, contain the following known matting agents, not according to the invention, in an amount of 4 g each:

The casting compositions are applied with a casting machine to an uncured color negative film as the top cover layer (wet application 50 g composition per m ² ) and the layer at 25 ° C and 60% rel. Humidity dried. The cover layers form a dry layer of 0.6 - 0.7 g / m ² .

The color negative film used has a conventional structure. A red-sensitized silver halide layer with emulsified cyan color coupler, an intermediate layer, a green-sensitized silver halide layer with a magenta coupler, a yellow filter layer and a blue-sensitized yellow coupler-containing silver halide layer are applied in succession to a cellulose triacet substrate.

The intermediate layers are made of gelatin and a _G ießhilfsmittel, the yellow filter layer contains yellow colloidal silver also. The layer thicknesses of the layers containing silver halide are between 5 and 6 µm, those of the intermediate layer between 1 and 2 µm. The film is cast without curing agent and cured by overlaying the top layer composition.

The color couplers and casting aids are listed in the following table.

Samples A to I are tested after drying in the following way:

Test 1: shiny spots

The samples are cut into 5 cm ² large pieces and conditioned for 2 days at 30 ° C and 90% humidity. The samples are then stored under pressure on the layer side against the back for one day. Then the samples are torn apart and the size of the bonded surface is estimated (bare spots in the surface).

Test 2: cartridge extract

A film 35 mm wide and 125 cm long is wound into a film cartridge and 7 days at 90% RH. F. and 35 ° C stored. The pulling force (g) is then determined and registered when the film is pulled out of the cartridge. The maximum value is shown in the table below. In practice, the pull-out force should not exceed 300 g.

Test 3: yellow spot test

The film stored according to test 2 is developed photographically and checked for visible defects which have arisen as a result of storage, pressure and moisture. The number and size of the differently sized colored spots is evaluated in%, based on the area tested. A film with a suitable protective layer should show less than 5% yellow spots.

Test 4: Graininess

The graininess of a photographic image is caused by the color grain developed and by dispersions and matting agents, especially in the top layers. It is determined by determining the d-D value with a 29 pm pinhole as described by J.H. Altmann in Appl. Optics, Volume 3, (1964) pages 35-38. The graininess of 1.8 is a value sought in photography.

Test 5: surface gloss

The reflection (in%) of a light beam on the layer surface is determined. A gelatin layer containing no dispersed particles shows 100% reflection.

The results summarized in the previous table show the overall advantageous properties of the cellulose derivatives of the invention. While some of the comparative samples in individual tests achieve results comparable to those of the samples of the invention, the samples of the invention alone provide consistently favorable results throughout all tests, including, and this is noteworthy, the granularity test. The surface gloss of the layers which contain the alkali-soluble cellulose derivatives according to the invention is very high after processing and the granularity is correspondingly low, which can obviously not be explained solely by the fact that the cellulose derivatives are removed in the course of the alkaline processing. The proportion of larger particles in dispersions with a wide size distribution spectrum is particularly noticeable in test 4. All comparative dispersions with insoluble particles and usual size distribution spectrum (about + 5pm) show a higher granularity in this investigation. This has a very disruptive effect in photographic practice, especially with medium-sensitive color films.

Example 2

zugesetzt.The effect of the cellulose derivatives according to the invention can be increased by adding colloidal silica in the form of SiO ₂ hydrosols or by adding a latex of a hard polymer or copolymer with a glass transition temperature of over 40 ° C. and a particle size of less than 0.5 μm, such as polymethyl methacrylate , to increase the protective layer composition. Sodium polystyrene sulfonic acid or a copolymer of the structure is added as a viscosity-increasing agent

added.

The following top layer compositions are produced:

The pH of the solutions is 6.5 - 7; the wet application 50 g / m ² .

The hardening agent corresponds to the formula

The top layer solution is poured onto an uncured color negative film and dried.

The test is then carried out as indicated in Example 1.

Glossy spots and color spots can practically be completely avoided by combining the cellulose derivatives according to the invention with silica sol or latex such as samples B and C.

Example 3 Comparative dispersion (3-A):

• For comparison, a dispersion of a porous alkali-soluble substance (corresponding to US Pat. No. 4,094,848) is prepared in an aqueous gelatin solution:
• 20 g of gelatin are swollen in 160 g of water and dissolved at 40 ° C.
• 0.75 g of the sodium salt of dodecylbenzene sulfonic acid dissolved in 40 g of water is added as a wetting agent.
• The mixture is cooled to 35 ° C., then a solution of is dispersed by means of a mixing device at 1,500 rpm
• 20 g copolymer of 63% methyl methacrylate and 37% methacrylic acid
• 70 g tert. Butanol and
• 70 g of ethyl acetate
• into the gelatin solution.

_M an evaporates the solvent mixture slowly over 2 hours with gentle stirring. After filtering through a filter cloth, particles with a particle size mixture of 1-5 _N m are obtained. The largest particles have a size of 10 to 15 _Nm . The particles have a grained porous surface and are opaque.

Comparison of the cellulose derivatives used according to the invention with the particles of the comparison dispersion 3-A.

In contrast to the comparative particles, the cellulose derivatives do not dissolve at a pH below 7. This is particularly advantageous for casting solutions which have to be digested for a long time and have a pH of 6.5-7 because certain components contribute pH values less than 6.5 are not stable. The particles according to the invention differ from the comparison particles further in that they are clear and have a smooth surface.

• 400 g Wasser
• 70 g 4 %ige wäßrige Lösung des Netzmittels C₇F₁₅COO^⊖(NH₄)^⊕,
• 40 g der Dispersion 3-A (10 Gew.-% Copolymerisat) und 500 g einer 10 gew.-%igen wäßrigen Härterlösung

Comparative dispersion 3-A is incorporated into the following casting solution:

• 400 g water
• 70 g 4% aqueous solution of the wetting agent C ₇ F ₁₅ COO ^⊖ (NH ₄ ) ^⊕ ,
• 40 g of dispersion 3-A (10% by weight of copolymer) and 500 g of a 10% by weight aqueous hardener solution

1:1 Molar.a reaction product of taurine with the compound

1: 1 molar.

• 175 g Wasser
• 70 g 4 Gew.-%ige wäßrige Lösung des Netzmittels C₇F₁₅COO^⊖(NH₄)^⊕
• 225 g der Dispersion 3 (1,8 Gew.-% Teilchen; 4 g)
• 500 g des obengenannten Härtungsmittel.

The dispersion 3 according to the invention is added to the following composition:

• 175 g water
• 70 g 4% by weight aqueous solution of the wetting agent C ₇ F ₁₅ COO ^⊖ (NH ₄ ) ^⊕
• 225 g of dispersion 3 (1.8% by weight of particles; 4 g)
• 500 g of the above curing agent.

The casting compositions are applied to the layer side of an uncured color negative film. Sample 3-A contains the comparative dispersion 3-A. Sample 3-B contains the dispersion 3 according to the invention. Sample 3-C contains no matting particles. The pH of all casting solutions is in the range 5-6.

Samples 3-A to 3-C are tested as described in Example 1:

It can be seen that the particles of sample 3-B are more resistant to the formation of glossy spots than the particles of the comparative sample. The cartridge pull-out force is the lowest with sample 3-B. The granularity of sample 3-B is as low as that of sample 3-C without a matting agent. The properties of sample 3-B are thus clearly superior to those of the comparative sample.

Example 4

Stability test at different pH values.

Dispersion 3-A and Dispersion 3 are diluted 1: 100 with buffer solutions. The transparency of the solutions at different pH values is measured with a laser measuring arrangement (UNI-PHASE HE-Ne laser, cuvette thickness: 1 cm; comparative sample: distilled water = 100% transparency).

The buffer solutions have pH values of 5.5, 6.0, 6.5, 7.0, 7.5 and 8.0.

The transparency values obtained in% are shown in FIG. 6 as a function of the pH.

The particles of dispersion 3-A are already dissolved at pH 6.2 and have therefore lost their effect as matting and anti-adhesive agents. The particles of dispersion 3 according to the invention are completely stable up to pH 7 and do not dissolve. Your application will be greatly favored. The particles according to the invention are therefore insensitive to pH settings in the casting solution, which represents a considerable advantage.

Claims (5)

1. Photographic silver halide recording material which contains, in an outer transparent layer attached to the front and / or back, dispersed in a hydrophilic colloid in alkaline processing liquids, soluble particles having a particle size of less than 10 μm, characterized in that the layer 10-500 mg / m Contains ² spherical transparent particles of a hydroxyalkyl-alkylcellulose dicarboxylic acid semi-ester with a particle size of 0.5-8 μm and a particle size distribution of up to + 2 _/ um dispersed. 2. Material according to claim 1, characterized in that it is a hydroxyalkyl-alkylcellulose dicarboxylic acid with the grouping

contains in which mean A a glucose residue of cellulose, R ^{1 is} a hydroxyalkyl radical with 2 to 4 carbon atoms, _R ^{2 is} an alkyl radical with 1 to 3 carbon atoms, _R ^{3 is} the monoacyl radical of a benzenedicarboxylic acid or such an acid in partially or fully hydrogenated form, m = 0.2 - 1.0 n = 0.8 - 2.0 and p = 0.5 - 1.5
where m # n # p and the sum m + n + p is at most 3. 3. Material according to claim 1, characterized in that the hydroxyalkyl-alkylcellulose dicarboxylic acid half-ester is a hydroxypropyl-methylcellulose-hexahydrophthalic acid half-ester or a hydroxypropylmethylcellulose-phthalic acid half-ester. 4. Material according to claims 1 and 2, characterized in that the layer additionally contains colloidal silica having a particle size smaller than 0.15 µm in an amount of 0.5 to 2 parts by weight, based on 1 part by weight of the hydrophilic colloid. 5. Material according to claims 1 to 3, characterized in that the layer additionally particles of a homo- or copolymer with a glass transition temperature of at least 40 ° C and a particle size smaller than 0.1 µm in an amount of up to 50 wt .-% , based on the hydrophilic colloid.

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