DE1572177C3 - Process for preparing a gelatin-silver halide photographic emulsion - Google Patents

Description

-CH ₂ -CH-

in which R ¹ denotes a hydrogen atom or a methyl group and R ² denotes a hydrogen or halogen atom or an alkyl, nitro, —COCH ₃ or COOC ₂ H ₅ group or a fused aromatic ring

2. The method according to claim 1, characterized in that the intrinsic viscosity of the copolymer, measured at 30 ⁰ C in aqueous 1 η NaNO 3 solution, is between 0.15 and 0.60 dl / g.

An indication of how to improve the hiding power of the silver image obtained from the silver halide emulsions can not be found in the patent specifications mentioned. Indeed, by modifying it becomes Amino groups exerted no influence on the opacity.

The invention is based on the object

To provide a method for preparing a gelatin-silver halide photographic emulsion which Part of the gelatine was replaced by water-soluble polymers of acrylamide, and modified gelatine-silver halide emulsions makes accessible, which through an improved opacity of the developed silver, an increased contrast effect and increased sensitivity are excellent.

This object is achieved in that, after the precipitation of the silver halide, the water-soluble polymer of the acrylamide, a copolymer in an amount of 2 to 75% by weight, based on the gelatin, added, which is derived from 78.5 to 90% by weight from units of acrylamide and the remainder from units the general formula

The invention relates to a process for the preparation of a gelatin-silver halide photographic emulsion using water-soluble polymers of acrylamide as a partial replacement for gelatin.

It is known to add certain compounds, such as salts of heavy or noble metals, to improve the sensitivity properties of photographic emulsions. By adding polyvinyl lactams containing 4 to 5 carbon atoms in the heterocyclic ring, e.g. B. polyvinylpiperidone or polyvinylpyrrolidone, favorable results have been achieved with regard to increasing the γ and M £ YD _ma *) values of the developed image (FR-PS 12 34 882); Photographic emulsions modified in this way, however, show a strong tendency to fog over time. This disadvantage has hitherto been partially remedied by adding small amounts of phenolic compounds which counteract the formation of fog (FR-PS 12 33 875). However, these modifying emulsions become unstable in sensitivity characteristics when stored under various conditions of temperature and relative humidity.

In the already known use of polyacrylamide as an emulsion additive, it was found that the Silver halide in a medium consisting essentially of polyacrylamide that of the photographic From the point of view of the desired crystal form of the silver halide consisting of flat, tabular platelets cannot be achieved. Therefore it is also known from DE-AS 11 61 759, a partial Use modified acrylamide polymer in which 2 to 20% of the amide groups are in amino groups have been converted.

-CH ₂ -CH-CO

R ²

in which R ¹ denotes a hydrogen atom or a methyl group and R ² denotes a hydrogen or halogen atom or an alkyl, nitro, —COCH ₃ or COOC ₂ H ₅ group or a fused aromatic ring.

The process of the invention provides modified silver halide emulsions with improved sensitometric Properties accessible; draws the exposed and developed image from these emulsions is characterized by increased opacity and allows a strong increase in maximum density, contrast and the sensitivity compared to emulsions using gelatin only. The addition of the Copolymers according to the invention to form an emulsion do not require any special operations and can be used with Can be carried out using conventional devices. Solvent recovery problems do not exist, since aqueous solutions can be used and the application of the modified emulsions with conventional application and drying techniques and devices can be carried out.

The opacity is defined as the numerical ratio of the optical density to the number of grams of silver per dm ² in the developed emulsion layer.
The copolymers according to the invention are added to the light-sensitive emulsion after precipitation of the silver halide, e.g. B. during physical or chemical ripening or before it is applied. The amounts to be used are in the specified range, but depend in detail on the type of polymer, the type of emulsion and the desired effect.

The copolymers according to the invention can be prepared by free radical polymerization, for. B. with the help of peroxides and azo derivatives, preferably be prepared in solution. The intrinsichen viscosities (η NaNO ₃ as measured at 30 ⁰ C in 1), with the preferred values from .15 to 0.60 / g dl lie in the range of 0.04 to 2 dl / g.

Suitable monomers besides arylamide are

N-phenylacrylamide,

N-methyl-N-phenylacrylamide,

N-p-chlorophenylacrylamide,

N-p-tolylacrylamide,

N-methyl-N-m-tolylacrylamide,

N-p-acetylphenylacrylamide,

N-p-carbethoxyphenylacrylamide,

N-jS-naphthylacrylamide and

N-p-nitrophenylacrylamide.

The polymers are particularly useful in the preparation of emulsions for X-ray films, especially for medical X-ray diagnosis, as well as for the production of emulsions on the graphic area. However, their use is not limited to any particular type of emulsion or emulsion The type of silver halide is limited because it can be used very well in silver bromide, boromide iodide, -chlorobromide and -chloride emulsions, in emulsions for black and white and color photography.

These emulsions can be chemically sensitized with precious metal compounds, ζ. B. ammonium aurothiocyanate, with sulfur compounds, ζ. Β. AUyIthiourea, or polyoxyethylene compounds. They can also be one or more spectral Sensitizing dyes, couplers, antifoggants, stabilizers, plasticizers, hardeners and others contain usual additives.

The following preparations and examples are intended to explain the above statements, but not restrict.

Preparation 1

In a 250 ml three-necked flask equipped with Stirrer and reflux condenser, the 90 ml of a mixture of acetone and methanol in a volume ratio of 3: 1 contains 9 g of acrylamide and 1 g of N-phenylacrylamide.

The solution is refluxed for 5 minutes, 0.1 g of azo-bis-isobutyronitrile are added and the mixture is refluxed again for 5 hours and then cooled in an ice bath.

The polymer that has separated is filtered off, washed with a little acetone and washed under Vacuum dried.

Polymer yield: 10 g
[■ //] = 0.51 dl / gin 1 η NaNO _{3 at} 30 ° C
... N = 19.09%.

Preparation 2

Following the procedure of preparation 1, a solution of 8 g of acrylamide and 2 g of N-phenylacrylamide is added in 90 ml of a mixture of acetone and methanol in a volume ratio of 3: 1.0.1 g of azo-bisisobutyronitrile added and the mixture is refluxed for 5 hours.

Polymer yield: 9.3 g

[η] = 0.39 dl / g in 1 η NaOH ₃ at 30 ° C

N = 17.60%.

Preparation 3

To a solution of 223.2 g of acrylamide and 24.8 g of N-phenylacrylamide in 4000 ml of a mixture of Acetone and methanol in a volume ratio of 3: 1

2.4 g of azo-bis-isobutyronitrile are added and the mixture is refluxed for 5 hours.

Polymer yield: 245 g

[η] = 0.55dl / g in 1N NaNO _{3 at} 30 ° C N = 19.09%

Preparation 4

To a solution of 63.97 g of acrylamide and 14.71 g of N-phenylacrylamide in 1230 ml of a mixture of Acetone and methanol in a volume ratio of 3: 1 are added and 3.14 g of azo-bis-isobutyronitrile the mixture is refluxed for 5 hours.

Polymer yield: 78 g

[η] = 0.27 dl / g in 1N NaNO ₃ at 30 ° C

N = 17.60% ■■ ■ ■ ■ -; .-.

Preparation 5

To a solution of 9g acrylamide and Ig N-methyl-N-phenylacrylamide in 90 ml of a mixture of acetone and methanol in a volume ratio of 3: 1 0.1 g of azo-bis-isobutyronitrile are added and the mixture is refluxed for 5 hours heated.

Polymer yield: 9.6 g

[η] = 0.41 dl / g in 1N NaNO _{3 at} 30 ° C N = 18.65%.

Preparation 6

To a solution of 8 g of acrylamide and 2 g of N-methyl-N-phenylacrylamide in 80 ml of a mixture of acetone and methanol in a volume ratio of 3: 1 is added 0.1 g of azo-bis-isobutyronitrile and the mixture is left for 5 hours heated to reflux. ^:

Polymer yield: 8.9 g

[η] = 0.29 dl / gin 1 n NaNO ₃ at 30 ⁰ C N = 18.10%

Preparation 7

To a solution of 9g acrylamide and Ig N-p-chlorophenylacrylamide in 90 ml of a mixture of acetone and methanol in a volume ratio of 3: 1 0.1 g of azo-bis-isobutyronitrile are added and the mixture is refluxed for 5 hours heated.

Polymer yield: 9.9 g

[η] = 0.55 dl / g in 1N NaNO ₃ at 30 ° C N = 18.47%

Preparation 8

To a solution of 9g acrylamide and Ig p-Tolylacrylamide in 90 ml of a mixture of acetone and methanol in a volume ratio of 3: 1 0.1 g of azo-bis-isobutyronitrile is added and the mixture is refluxed for 5 hours. "'■'"

Polymer yield: 9.8 g; ... ·;

[η] = 0.59 dl / g in 1N NaNO ₃ at 30 ° C. ·· ■ · ■■ N = 18.40%

Preparation 9

To a solution of 8 g of acrylamide and 2 g of p-tolylacrylamide in 90 ml of a mixture of acetone

and methanol in a volume ratio of 3: 1, 0.1 g of azo-bis-butyronitrile are added and the mixture Heated to reflux for 5 hours.

Polymer yield: 9.4 g

[η] = 0.31 dl / g in 1 η NaNOj at 30 ⁰ C N = 18.06%

Preparation 10

To a solution of 16 g of acrylamide and 4.38 g of N-methyl-N-m-tolylacrylamide in 487 ml of a mixture of acetone and methanol in a volume ratio of 3: 1, 0.81 g of azo-bis-isobutyronitrile are added and the mixture is refluxed for 21 hours.

Polymer yield: 14.9 g

[η] = 0.14 dl / g in 1 η NaNO _{3 at} 30 ° C N = 17.58%

The specified nitrogen contents were determined after careful drying of the products by means of the Kjeldahl method determined.

The structure of the polymers was determined by infrared examination.

example 1

A highly sensitive ammoniacal gelatin silver iodobromide emulsion with about 2 mol% silver iodide and a silver / gelatin ratio of about 0.63 for X-ray recording by means of an intensifying screen and provided with the usual additives divided into 7 parts.

The first portion was applied directly to a standard cellulose triacetate base, with after Drying the emulsion a layer density of about 13 μ was obtained.

The polymers according to preparations 1, 2, 6, 7, 8 and 9 were added to the remaining 6 portions

Table 1

Amounts added that they had a ratio of gelatin to polymer of 100 to 25 and corresponded to the following scheme:

For the second part

the polymer according to preparation 1.

For the third part

the polymer according to preparation 2

For the fourth part

the polymer according to preparation 6

For the fifth share

the polymer according to preparation 7

For the sixth share

the polymer according to the preparations

For the seventh share

the polymer according to preparation 9

The various emulsions thus obtained were then likewise applied to a conventional cellulose triacetate support applied, a layer thickness was obtained which was about the same as that of the pattern.

After storage for two days at 50 ^° C. and a relative humidity of 65%, the samples were exposed to constant 0.3 mog E units through a gray wedge and then developed for 4 minutes at 20 ^° C. in a bath of the following composition:

anhydrous sodium carbonate 50 g

anhydrous sodium sulfite 50 g

Hydroquinone 9 g

N-methyl-p-aminophenol sulfate 3 g

Potassium bromide 3 g

made up to 1000 ml with water

After the 8 samples have been developed, fixed and dried as usual, they show them in the table 1 specified properties:

Pattern no.

Polymer

according to

preparation

Ag / m ² *) (g)

Opacity **) Veil

Sensitivity***)

1 - 8.92 37.5 0.27 0.15 1.35 3.00 2 1 6.91 44 0.26 0.15 1.35 3.00 3 2 7.11 45.7 0.25 0.25 1.35 2.90 4th 6th 6.98 41.6 0.28 0.18 1.32 . 2.90 5 7th 6.34 44 0.29 0.16 1.35 2.90 6th 8th 6.29 43 0.28 0.15 1.35 2.80 7th 9 6.50 45 0.26 0.15 1.30 2.90

*) On unexposed! Material.
**) After 15 days of storage.
■ ***) At D = 1.0 + veil.

For ease of comparison, the numerical values given are expressed as differences from log E with respect to an arbitrarily chosen reference mark on the gray wedge. The positive values indicate greater sensitivity.

Example 2

An ammoniacal emulsion similar to that described in Example 1 was divided into 3 portions. Of the

The first portion was placed directly on a standard cellulose triacetate pad applied, with a layer thickness of about 13.5 μ obtained after the emulsion has dried became.

The polymer according to preparation 1 was added to the second portion in such amounts that a The ratio of gelatin to polymer was 100/20.

Then he was also put on a cellulose triacetate

underlay, but applied in two different thicknesses, after which the emulsion has dried Layer thicknesses of about 11.5 and 12.5 μ were obtained. The polymer according to preparation 2 was added to the third portion in such amounts that a Gelatin to polymer ratio of 100/20

Table 2

revealed. Then the procedure was the same as for the second part.

After five days of storage at 50 ° C and 65% relative humidity, the swatches became exposed and then treated as described in Example 1; they showed after stopping treatment the properties given in table 2:

Pattern no. Polymer Layer thickness Ag / m ² *) Opacity veil Sensitive y '-'Max according to ability **) preparation (μ) (G) 1 - 13.5 5.93 39.6 0.18 -0.05 1.10 1.97 2 1 11.8 4.65 51 0.17 +0.15 1.35 2.00 3 1 12.8 5.35 50 0.17 +0.15 1.40 2.20 4th 2 11.6 4.72 56.7 0.17 +0.25 1.60 2.27 5 2 12.4 5.33 52 0.17 +0.15 1.40 2.23

*) On unexposed! Material.
**) At D = 1.0+ veil.

Example 3

A highly sensitive ammoniacal gelatin silver iodobromide emulsion with about 1.28 mole percent silver iodide and a silver / gelatin ratio of about 1 for X-ray recording without an intensifying screen and with the usual additions was split into two Shares divided.

The first portion was applied directly to a standard cellulose triacetate base, with after Drying the emulsion a layer thickness of about 19.8 μ was obtained.

The polymer became according to the second portion

Table 3

Preparation 3 was added in such amounts that a ratio of gelatin to polymer of 100/30 revealed. Then it was also applied to a cellulose triacetate base, after drying the Emulsion a layer thickness of about 20 μ was obtained.

After five days of storage at 50 ^° C. and a relative humidity of 65%, the samples were exposed and then treated as described in Example 1; After complete termination of the treatment, they showed the properties given in Table 3:

Pattern no. strength
(μ) Ag / m ² *)
(G) Opacity veil Sensitive
ability **) Y • Jrnax 1
2 19.8
20th 16.67
13.55 37.2
.44.5 0.14
0.14 -0.25
-0.10 1.70
2.10 4.70
4.80

si - ¹ *) On unexposed material.
**) At D = 1.0+ veil.

Example 4

An ammoniacal emulsion similar to that described in Example 1 was divided into 3 portions.

The first portion was applied directly to a standard cellulose triacetate pad, with after drying the emulsion a layer thickness of about

13.2 μ was obtained.

The polymer according to preparation 3 was added to the second portion in such amounts that one Gelatin to polymer ratio of 100/25 was obtained. Then he was on one too Cellulose triacetate base applied, after drying the emulsion a layer thickness of about

13.3 μ was obtained.

The polymer according to preparation 4 was added to the third portion in such amounts that a The ratio of gelatin to polymer was 100/25 and then the proportion was also reduced to one Cellulose triacetate base applied, after drying the emulsion a layer thickness of about 13.5 µ was obtained.

After five days of storage at 50 ° C and a relative humidity of 65%, the samples were through a Gray wedge exposed with constant 0.3 log Ε units and then exposed for 2 minutes and 30 seconds at 27 ° C in a bath of the following composition:

N-methyl-p-aminophenol sulfate 3 g

anhydrous sodium sulfite 50 g

Hydroquinone 9 g

anhydrous sodium carbonate 50 g

Potassium bromide 3 g

Glutaraldehyde bisulfite 13 g

5-methylbenzenetriazole 0.15 g

made up to 1000 ml with water

After the 3 samples were developed, fixed, washed and dried as usual, they showed the in Properties given in table 4:

909 548/7

Table 4

ίο

Sample no. Polymer layer thickness Ag / m *)
according to
Preparation (μ) (g)

Opacity **) Veil

Sensitivity***)

1 - 13.2 7.09 34.5 0.26 +0.05 1.15 2.40 2 3 13.3 5.75 41 0.20 +0.30 1.30 2.37 3 4th 13.5 5.70 42.2 0.25 +0.20 1.20 2.27

*) On unexposed! Material.
**) At D = 2.0.
***) At D = 1.0 + veil.

example

An ammoniacal emulsion similar to that in Example 1 was divided into 3 portions.

The first portion was applied directly to a standard cellulose triacetate pad, as shown Drying the emulsion a layer thickness of about 13.4 μ was obtained.

For the second portion, the polymer according to preparation 4 was added in such amounts that a 2 ^r > ratio of gelatin to polymer of 100/25 resulted. The portion was then also applied to a cellulose triacetate base, with a layer thickness of about 14.6 μ being obtained after the emulsion had dried. jo

The polymer according to preparation 10 was added to the third portion in such amounts that a The ratio of gelatin to polymer was 100/25. Then it was also placed on a cellulose triacetate pad applied, with a layer thickness of about 14.5 μ obtained after drying the emulsion became.

After five days of storage at 50 ^° C. and 65% relative humidity, the samples were exposed and then treated as described in example 4; after the end of the treatment they showed the properties given in Table 5:

Table 5 Polymer
according to
preparation strength
(μ) Ag / m ² *)
(G) Opacity **) veil Sensitive
ability ***) y U max Pattern no. 4th
10 13.4
14.6
14.5 6.41
5.79
5.59 33.3
. 39.6
36.5 0.17
0.18
0.17 +0.05
+0.20
+0.25 1.10
1.30
1.35 2.15
2.27
2.27 1
2
3

*) On unexposed material.
**) At D = 2.0.
***) At D = 1.0 + veil.

Claims (1)

Patent claims: 1. A method for preparing a gelatin-silver halide photographic emulsion using water-soluble polymers of acrylamide as a partial replacement for gelatin, thereby characterized in that after the precipitation of the silver halide as a water-soluble polymer of the acrylamide is a copolymer in an amount of 2 to 75% by weight, based on the Gelatin, which is derived from 78.5 to 90% by weight from units of the acrylamide and the remainder from units of the general formula