HU182602B - Process for matting photographic materials - Google Patents

Abstract

Dulled, black and white and colour photographic materials include in at least one layer, for example a silver halide, protective, filter or NC layer, from 5 to 50%, preferably from 7.5 to 20%, by weight, calculated on the dry weight of the binding agent in the layer, of a dispersion of a polyvinyl chloride or vinyl chloride copolymer produced by micro-suspension or seed polymerisation.

Description

The invention relates to a process for polishing photographic materials.

It is known that the surfaces of photographic layers can be polished by the addition of inorganic or organic pigments or synthetic polymers. In this way, surface roughness can be achieved which provides good retouchability and prevents the formation of Newtonian rings when copying. An opacifier should be selected which is photically inactive and has a refractive index similar to that of dry gelatin to avoid clouding and sharpness loss due to diffused light. In addition, polished surfaces should be less abrasive and fingerprint resistant.

US Patent Specification 1,547,639 proposes the addition of an amorphous silica polish.

However, this agent has the disadvantage that it tends to agglomerate at higher temperatures and is therefore difficult to filter. Alkaline earth metal salts, such as those disclosed in U.S. Patent No. 2,823,136, are also unsatisfactory. These salts have a high density and opacity, which greatly influences photographic properties. There are additional polishing options other than those mentioned. Thus, wax (U.S. Patent No. 35,234), hardened gelatin (U.S. Patent No. 2,522,692), cellulose derivatives (German Patent No. 725,698), or synthetic polymer-based dispersions are suggested as additives. These known methods have a number of disadvantages. Thus, the wax-opaque layers have an unsatisfactory roughness, as this is partially lost during drying.

Starches, cellulose derivatives and hardened gelatin are hardly available in the desired particle size range and partially lose their de-gloss effect at high humidity. Synthetic polymer dispersions have the advantage that they do not diminish their de-glue effect during casting due to rapid settling. Known polymer dispersions are polystyrene dispersions (British Patent No. 645,954), dispersions based on copolymer of polymethyl methacrylate and styrene (Belgian Patent 634,174 and German Patent Publication No. 2,628.64.3).

However, with polystyrene resins, it is only very difficult to obtain stable dispersions having a uniform particle size distribution.

Because the refractive index of polystyrene, as well as that of polymethyl methacrylate, is significantly different from the refractive index of gelatin, there is a high degree of turbidity and loss of sharpness in photographic materials made with these dispersions. In addition, their production is very expensive and difficult to reproduce.

It is an object of the present invention to provide an improved process for polishing photographic materials to achieve uniform polishing, in addition to completely eliminating clouding phenomena and scattered light with the use of a de-icing agent and to produce the polishing agent in a cost-effective and reproducible manner.

The object of the invention is to make it necessary to increase the turbidity and sharpness caused by the disadvantages of the known processes, such as the unfavorable refractive index of the polishing agent, the lack of stability due to the casting process, and the lack of gloss caused by unfavorable particle distribution. elimination of molding disturbances by applying new polymer dispersions to polish photographic materials.

The object is achieved according to the invention is that fénvtelenítő agent is polivinilklorid- polymer dispersion or by a mixture of vinyl chloride-based polimerizátnm, microsuspension or polimerizáeió radical polimerizáeió weight was 5-50 ° _0, preferably from 7.5 to 20 weight ¹ ',, amount based on the dry weight of the binder of the layer to be polished. These polymer dispersions have a narrow particle size distribution and can be prepared in the range of 0.1 to 5 μηι as disclosed in German Patent Publication No. 1,301,529 and English Patent Application No. is written down.

These dispersions tend to settle in the aqueous phase without the addition of additional protective colloids without agglomeration. Based on the polymer weight of 20 to 500 weight ',, ^one protective colloid, preferably 100-200 weight ,, gelatin, obtained by the addition of very stable dispersions. According to the invention, they can be used in liquid form, without premature hardening, as polishing dispersions. However, it is also possible to freeze the dispersion by adding a gelatin solution and to store the gel. After storage at 278 K ° for several months, no changes in particle size and particle size distribution occur. However, it is also possible to dry the gel. The novel polishing process of the present invention allows both silver halide layers, protective layers, filter layers, and NC layers to be polished.

The novel polishing process is characterized in that the polishing dispersions used can be prepared in a simple manner, without the need for high speed dispersants, at the desired particle size and narrow particle size distribution. This results in effective roughening even at low light concentration at 0.1-5 μηι particle size.

Since the vinyl chloride polyesterate has a refractive index of L, 538, which almost corresponds to the refractive index of gelatin, we avoid clouding phenomena and sharpness losses.

The particles in the form of dispersions are very stable against agglomeration and dimensionally resistant even at high humidity. Stabilized with gelatin and dried after freezing can be stored for long periods without additional cooling and water as needed3

-2182602 or re-dispersible in aqueous protective colloidal solution. The process according to the invention makes it possible, in particular, to produce de-gelatinised gelatin layers.

The invention is further illustrated by the following examples.

Example 1

Preparation of sufficient metal dispersions

In a liter of water, 1 kg of gelatin is swollen and melted in a polish dispersion. To this was added 2 kg of polymethyl methacrylate dissolved in 11.4 L of methylene chloride at 318 K and dispersed using a high speed stirrer. Upon completion of the dispersion, the methylene chloride was removed and the dispersion was allowed to solidify at 283 K. The average particle diameter of the polymer particles is 0.478 μηι. The refractive index of the polymer particles is 1.492.

B polish dispersion dispersion

9.5 L of water are swollen and melted with 1 kg of gelatin. To this, 0.45 kg of a 31 wt.% Polyvinyl chloride dispersion prepared by microsuspension polymerization, and having an average particle size of 0.481 μηι, are added at 328 K ^c with conventional low speed agitation. After the addition was complete, the mixture was allowed to solidify at 283 K °. The resulting polymer particles have a refractive index of 1.538.

C-E polishing dispersions

The polishing agents C to K are prepared in a manner similar to the polishing agent B, using polyvinyl chloride dispersions of different particle sizes.

Illuminating Dispersion Average particle diameter

C 0.789 μηι

I) 0.948 μηι

E 1,312 μηι

The polishing gel dispersion dispersion B, denaturing gel, is poured into a freezing mold and cured at 283 K °. The resulting gel was cut into cubes of about 2 cm ³ and air dried at 308 K for 48 hours. These cubes are again crushed using a granulating structure. In this way, a slightly cloudy granulate is obtained, hereinafter referred to as a de-gelling gel.

Example 2

In 100 liters of 2 (1, - 08) aqueous gelatin solution was dissolved 1.2 kg of a polish dispersion A, which was poured onto a halogen silver emulsion as a protective layer.

The dried protective layer can be retouched well, roughening! has a depth of 1.1 nm and shows little Newton ring when copied.

Example 3

The procedure described in Example 2 was repeated, using 1.2 kg of a B polish dispersion. The dried protective layer has the following characteristics:

retouchability: very good roughness depth: 1,2 μηι

Newton's rings: none

Example 4

The procedure described in Example 2 is repeated, using 4.8 kg of the anti-glare dispersion A and B. The dried protective layer has the following characteristics:

A B retouchability: very good very good roughness depth: 1.6 μηι 1.7 μηι

Newton's Rings: None None

The material with the anti-glare dispersion based coating A is very cloudy and has a very high loss of sharpness.

5-7. examples

The procedure described in Example 2 was repeated, using 4.8 kg of a polish dispersion C, 1), E. Dried protective layers have the following characteristics:

-3182602

dulling dispersion C D E retouched roughness very good very good very good depth 2.8 μιη 3.1 μηι 3.0 to 3.2 Newton's μιη gvűrűk There are no There are no There are no

Example 8

The procedure of Example 2 is repeated, whereby 0.45 kg of de-gelling gelatine is swollen in 31 liters of 100% 1.5% gelatin solution for 20 minutes and then redispersed with stirring.

The dried protective layer has the following characteristics:

retouchability: very good roughening! depth: 1.4 μηι

Newton's rings: none

Example 0

For a multilayer colored material containing a green-sensitive halogen silver-color switch emulsion containing 5 stabilizers, a starch, a wetting agent, Z 169 purple zinc switch (Bios Final Rep. 721, 21, 1946), and conventional additives, e.gv

The protective layer of Example 3 was poured. Bleaching with a B polish dispersion does not affect photographic properties. When stored at 90% humidity, no adhesion of the backing layer to the protective layer is observed.

Comparatives without a B polish dispersion dispersion, that is to say, which did not contain glaze B polish dispersion in the protective layer, are, however, highly prone to sticking which, when subjected to mechanical stress, results in damage to the backing layer and protective layer.

Claims (1)

Claim: A process for light-saturating polymeric dispersions of photographic materials, in particular silver halide layers, protective layers or NC layers, by using a polymer dispersion obtained by microsuspension or by radical polymerization based on a polyvinyl chloride or vinyl chloride blend based on microsuspension or by radical polymerization. 5- 30 20 by weight, in the amount to be polished, based on the dry weight of g of binder.