JPH05502306A - Formation of tabular silver halide emulsions using high pH ripening - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a method for producing photographic emulsions containing tabular silver halide grains.

More particularly, the present invention relates to a method of making photographic emulsions at high pH.

Background technology Platy silver halide grains, their preparation and use in photographic emulsions are widely known. child Photographic emulsions containing these grains may be round or spherical. ar) grains (e.g. in splash-producing form) It has been extensively studied in the literature as it is thought to offer significant advantages for the species. . Generally, platelet particles are produced by using long aging times or by equilibrium double dilution. accelerated flow precipitation method (BDJ) A large flat halo manufactured by the ``ecipitation method'' They are silver germide grains. Industrial emulsions using plate-like grains conventionally use the BDJ method. It is manufactured by Plate grains are usually triangular or hexagonal parallel crystals. each of which is typically larger than any other crystallographic face of the particle. , traditionally defined by the aspect ratio (AR), which is the ratio of particle diameter to thickness. has been done. It was discovered that plate-shaped particles with varying thickness and AR are useful in photographic systems. has been done. Large diameter, high aspect ratio particles, e.g. at least 8:1, are less Both have a diameter of 0.6 μm and a thickness of less than 0.3 μm. These large It is currently clear to those of ordinary skill in the art that large plate-like particles are Yes, it has certain industrial advantages. For example, these have a large surface area. and therefore can accept more sensitizing dyes. These plate-like particles When emulsions using platelet grains such as Since the image is sensitized, the sharpness can be increased. Furthermore, platelet particles are usually supported When the emulsion is coated on the carrier, it is flat, so the covering power is usually large. Therefore, these emulsions can be coated with small coating weights, thereby reducing cost and .

You don't have to do it.

Platy grains have found wide use in full color, black and white and X-ray film. Ru. However, for successful use in X-ray films, X It is necessary that the X-ray film has the same image gradation as conventional X-ray film.

This is done in order for the radiographer to successfully read the radiograph in the same way as he or she has done in the past. X This is necessary for line technicians. To form 7 grains satisfactory for X-ray film It is necessary that these have a certain thickness and equidistant diameter range. preferable Use long formation times and difficult-to-control substances to form particles within a range It requires that.

U.S. Pat. No. 4,722,886 - Nottorf describes The formation of silver halide materials suitable for use in the production of silver halide materials is disclosed.

As disclosed in this patent, this method uses ammonium hydroxide as the solvent. The pH of the aging solution is increased by adding . However, When ammonium hydroxide is used as an agent, it sometimes causes an R-type problem (fogging). R-typing problem). Furthermore, ammonium hydroxide is used Then, the material is volatile and evaporates, making it difficult to control. Furthermore, hydroxyl When using ammonium chloride, a large amount is required to raise the pH. Yes, ammonium hydroxide is difficult to dispose of without special treatment. However, there is a problem with the release of waste liquid.

Platy halogens without the problems of base volatility or difficulty in disposing of waste liquids. There remains a need for methods of producing silver generide emulsions at increased rates. Ru.

Disclosure of invention The aim of the invention is to overcome the drawbacks of the prior art.

Another object is to provide improved photographic emulsions.

Yet another object is to provide reduced time for forming gelatin emulsions. It is.

These and other objects of the present invention generally relate to post-nucleation and ripening Adjust the pH to greater than 9 by adding an alkali base before A method for forming a plate-like silver halide emulsion is proposed, in which nucleated silver bromide grains are formed in the first place. This is achieved by providing In a particularly preferred method, the emulsion is made of sodium hydroxide. The pH was adjusted to higher than 9 by using chlorine and aged for 3 to 7 minutes. , without the use of ammonium hydroxide and in less than 100 minutes. complete it. The emulsion formed is suitable for X-ray film and is produces the required image gradation.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has a number of advantages over the prior art. The present invention is based on ammonium hydroxide. There is no need to raise the pH using umum. With ammonium hydroxide, water Ammonium oxide tends to be difficult to control because it evaporates and changes the pH rapidly. Ru. Furthermore, ammonium hydroxide, which is not a strong base like sodium hydroxide, is requires a large amount of addition, increases cost, and Waste liquid requires additional treatment beyond that of alkali hydroxide waste, increasing waste liquid costs. bring about. The alkaline base of the present invention is easier to construct and produces silver halide nuclei. The action is faster during formation, thereby making the formation time shorter. Sodium hydroxide Since thorium is not volatile, it keeps the pH constant and also reduces changes in the emulsion grains. , increasing monodispersity.

Prior to this invention, it was believed that high pH for emulsion formation tended to fog the grains. It was However, surprisingly high bromide solution concentrations (approximately 0.01 mole (concentration), precipitated at high bromide content and formed at high pH using alkali hydroxide. It was found that the 7 particles produced showed no fog. Thick suitable for X-ray film A ripening process that allows plate crystals to form rapidly and without the presence of ammonium ions. The use of high pH to achieve this is not recognized in the art. Ta.

In carrying out the method of the invention, a bromide emulsion containing silver halide is formed. Ru. The bromide may be silver bromide or silver chlorobromide and/or silver iodobromide. nucleated The emulsion is treated with an alkali base, preferably sodium hydroxide, and further treated with silver or halogen. Aging without adding ions. During ripening, the substance dissolves the edges of the particles and deposit on the surface, making the platelet particles somewhat thicker. Furthermore, it is usually said to be ``mature J.'' In this method, fine particulate components are lost by migration to larger components. .

The pH of the silver halide emulsion during ripening may be clearly any pH greater than about 9. good. A suitable range has been found to be from about 9 to about 13. have the desired thickness For most uniform particle formation, the preferred range is a pH of about 9 to about 11. Admitted.

The aging time at high pH after nucleation can be any length that produces the desired particles. good. Typically, the aging time is about 0.5 minutes to about 40 minutes. desired thickness and In order to produce dispersions having a large percentage of particles of It was observed that the duration was about 1 minute to about 20 minutes. The highest desired thickness and diameter range For production of small percentage particles, the most preferred range is from about 60°C to about 80'C. It is confirmed that the heating time is about 3 minutes to about 7 minutes at a temperature of 30°C.

Percentage of silver added to the nucleation phase prior to pH adjustment in the emulsion during ripening at high pH The amount of gold typically ranges from about 0.1% to about 20% of the gold and silver to be formed. grains with desired properties The preferred range of silver is about 0.3% of the gold and silver to be added to effectively form the gold and silver particles. ~12% was observed. The most preferred % of silver is about 0.6 weight of silver % to about 2.7 times Ji96. This results in the desired This is because a large percentage of particles in a range of thicknesses and diameters are obtained.

The weight percent of gelatin present in the reaction vessel during ripening at high pH will yield the desired particles. It may be manufactured in such quantity.

Typical percentages of suitable gelatin range from about 0.5% to about 20% by weight of the total solution. %. The preferred amount of gelatin is about 1.5% to about 12% by weight. desired size The most preferred amount of gelatin is about 2.5-7% to form particles with a I found out that it was a volume %.

The base used to create a pH higher than 9 is any suitable alkaline base. There may be. Typical such bases are lithium hydroxide, metasilicic acid Sodium, trisodium phosphate, sodium carbonate and beryllium hydroxide.

Sodium hydroxide and potassium hydroxide introduce undesirable salts into the emulsion solution. The preferred alkali base is the hydroxylated base because it is not volatile, is not volatile, and has low cost. It was recognized that it was sodium and potassium hydroxide.

The platelet grain emulsion formed according to the present invention has at least 80% of the projected area of 0.1 It appears to be composed of plate-like crystals with a thickness greater than μm. of emulsion A crystal in which at least 80% of its projected area has a thickness of about 0.1 μm to about 0.5 μm It is appropriate to consist of For the desired X-ray gradation, the projected area of the emulsion is At least 80% have a preferred thickness in the range of about 0.1 μm to about 0.3 μm It is desirable that it be composed of crystals.

The platelet emulsions of the present invention generally have a diameter of about 0.3 to 10 μm for the platelet grains of the present invention. It has plate-like particles with an equivalent circular diameter of . Preferred equivalent circular diameter is thicker than 0.1 μm 80% of the emulsions have a thickness of about 0.5-5 μm. Equivalent circle diameter and thickness The measurements are made using shadowed electron micrographs of emulsion samples.

After ripening, an acid such as nitric acid is added to the solution containing the nucleated silver halide. Adjust to acidic pH. After adjusting to acidic pH, silver nitrate and halides Begin adding salt until particles of desired size are achieved. Generally halides and silver are added in an accelerated flow. Preferably, about the last 10% of the silver at the end, Add at a slowed flow and reduced bromide solution content.

After forming a silver halide emulsion, remove excess salts and sodium ions. for coagulation, ion exchange, ultrafiltration or noodling. This may be washed by a known method such as. To remove undesirable ions After washing, the gelatin emulsion of silver halide grains is prepared for use in film. Are suitable. The silver halide formed according to the present invention can be Used in X-ray film because it produces somewhat thicker grains that give preferred image gradation Particularly suitable for The method of the invention also applies to color transparent negative films and white In producing platelet silver halide grains for other photographic processing applications including black negative films. suitable for use.

During the ripening and growth stages, the pBr of the emulsion is significantly greater than the pBr of the reaction vessel during nucleation. It is preferable that it is expensive.

Modifying compounds may be present during silver bromide and silver bromoiodide precipitation. This way The compounds may be initially placed in a reaction vessel according to conventional methods, or one or It can be added with more salt. sulfur, selenium and gold and other Modifying compounds, such as modified compounds, can be found in Research Disclosure +- (Resea rch Disclosure) 22534.Disclosed in January 1983 Ru.

Vehicles containing both a binder and a peptizer are conventionally used in silver halide emulsions. You can choose from those available. The preferred peptizer is a hydrophilic colloid; These can be used alone or together with hydrophobic substances. Suitable hydrophilic substances include proteins. , protein derivatives, cellulose derivatives and preferred materials derived from bovine bone, animal skin or pig skin. Contains a gelatin-like substance.

Such vehicles are well known and are subject to the Research Disclosure above. - Disclosed in

Silver bromide grains of the present invention are preferably washed to remove soluble salts. research de Disclosure 17643, Volume 176, December 1978, Conventional cleaning methods such as those disclosed in .

For photographic emulsion, Item 17643, paragraphs 5.6.7.8 ．． Brighteners, antifoggants, as described in 10.11.12 and 16; Contains stabilizers, scattering agents, absorbers, hardeners, coating aids, plasticizers, lubricants and matting agents. It may be You can also use the conventional photo support holiday, Hem 14643 It is described in paragraph 17 of the section.

Example The invention can be better appreciated by reference to the following specific examples.

In each example, the contents of the reaction vessel were mixed during silver and halide addition and during aging. Stir vigorously for a while. The term "r%" means % by weight unless otherwise specified.

Example 1 0.6% gelatin containing 0.10M sodium bromide at 60'C, pH 4.0 Aqueous solution 0.5! ! Add 25 rnl of 0.25M silver nitrate solution to the solution and stir vigorously for 5 minutes. Added with stirring (consumed 0.63% of total silver used). Next, Zera While adding 0.5β of Chin aqueous solution (2.5% by weight), the temperature was increased to 70°C for 3 minutes. °C.

Then, 8.75 mj of 2.5M sodium hydroxide was added and held for 7 minutes. profit The pH obtained was 10.5. Then, 4°0M nitric acid was added to adjust the pH to 4.0. It was lowered to . Then add 2.5M sodium bromide solution and 2.5M silver nitrate solution. Accelerated flow (flow from start to finish) at 70°C at pBrl, 42 for 70 min. 27.5 times faster) and consumes 89.37% of the total amount of silver used. It was added by lujet addition. Next, the deceleration flow (flow velocity from start to finish? 0.18-fold decrease) to increase the pBr from 1.42 to 2.41 in 5 minutes. A single diluted solution of 2.5M silver nitrate at 70°C consumes 10.00% of the total silver. A wet addition was used. Approximately 1.0 mole of silver was used to make this emulsion. .

2.5M sodium hydroxide during a 7 minute hold period. (Other than adding 7) This emulsion was prepared in the same manner as in Example 1. The resulting pH was 5.2.

Example 3 17. 2.5M sodium hydroxide during a 7 minute hold period. Except for adding W This emulsion was prepared in the same manner as in Example 1. The resulting pH was 1098.

Example 4 except that 2.5 M sodium hydroxide was added during the 7 minute hold period. This emulsion was prepared in the same manner as in Example 1. The resulting pH was 10.0.

Example 5 except that 2.5 M sodium hydroxide was added during the 7 minute hold period. This emulsion was prepared in the same manner as in Example 1. The resulting pH was 9.5.

Example”- 0.6% gelatin containing 0.10M sodium bromide at 60°C, pH 4.0 Solution 0.5! Add a 0.69M silver nitrate solution 25- to 5 minutes with vigorous stirring. (1.73% of the total amount of silver used was consumed). Then gelatin and Ammonium sulfate aqueous solution (ceratin 4.7% by weight and ammonium sulfate 0.42% %) 0.51, the temperature was increased to 70'C over 3 minutes. Next Then, 16.5 mj of 2.5M sodium hydroxide was added and held for 5 minutes. Obtained The pH was 9.5. Then 4.0M nitric acid was added to lower the pH to 4.0. I let it go down. Then, add 2.5M sodium bromide solution and 2.5M silver nitrate solution to 60% ．． Accelerated flow (start to finish) at pBrl, 42 and 70°C for 3 min. 17.4 times faster) and consumes 88.27% of the total amount of silver used. It was added by lujet addition. Then, the deceleration flow (flow velocity from start to finish is (0.18-fold decrease) to increase pBr from 1.42 to 2.41 in 5 minutes. A single gel of 2.5M silver nitrate consumes io, oo% of the total silver at 70°C. Addition number was used. Approximately 1.0 mole of silver was used to make this emulsion.

Example 7 except that 2.5 M sodium hydroxide was added during the 5 minute hold period. This emulsion was prepared in the same manner as in Example 6. The resulting pH was 11.0.

Example 8 (control) except that 2.5 M sodium hydroxide 7.6− was added during the 5 minute hold period. This emulsion was prepared in the same manner as in Example 6. The resulting pH was 8.0.

The properties of the emulsions of Examples 1-8 are summarized in Table I below. Comparative examples 2 and 8 are compared with the examples of the present invention. Taken together, the present invention can be used to create the desired type of thick platelet particles for X-ray applications. The high pH of light is proof of success. Examples 6.7 and 8 further include ammonia The high pH method of the present invention produces desirable thick silver halide grains even in the presence of It indicates that it is manufactured. In contrast, the control of Example 8 in ammonia produced thick particles. There wasn't.

Table 1 Although the invention has been described in detail with particular reference to preferred embodiments thereof, variations and modifications thereof It is to be understood that the invention is valid within the spirit and scope of the invention.

abstract Generally speaking, the present invention provides p A plate-shaped halo that controls H higher than 9 to form uniformly nucleated silver bromide grains. This is accomplished by providing a method for forming a silver germide emulsion. In a particularly preferred method and adjust the emulsion to a pH above 9 by using sodium hydroxide. , ripening for 3 to 7 minutes, and using ammonium hydroxide to make the emulsion. It can be completed in less than 100 minutes. The emulsion formed is suitable for X-ray film. It creates the image gradation required by radiology technicians.

Submission of translation of written amendment (Patent Law Article 184-8) June 17, 1992

Claims (14)

[Claims] 1. Nucleation of silver halide containing bromide, addition of alkali base and from 9 A method of forming a tabular silver halide emulsion comprising ripening at high pH. 2. 2. The method of claim 1, wherein the alkali base comprises sodium hydroxide. 3. 2. The method of claim 1, wherein the ripened emulsion does not contain ammonium hydroxide. 4. 2. The method of claim 1, wherein said pH is between 9 and about 11. 5. 2. The method of claim 1, wherein aging is carried out for about 0.5 minutes to about 40 minutes. 6. 2. The method of claim 1, wherein aging is for about 3 minutes to about 7 minutes. 7. The method according to claim 1, wherein the pH is lowered by adding an acid after ripening. 8. Claims that from about 0.1% to about 20% of the total amount of silver to be used is present during ripening. The method described in paragraph 1. 9. The person according to claim 1, wherein the silver halide is silver chlorobromide or silver iodobromide. Law. 10. Nucleate silver bromide particles by combining silver nitrate and sodium bromide in gelatin solution. nucleate by adding sodium hydroxide to adjust the pH above about 9. The particles were aged, the pH was adjusted below 7 by the addition of acid, and silver nitrate and comprising adding sodium halide to grow the nucleated particles. , a method for forming silver halide emulsions. 11. 11. The method of claim 10, wherein aging is carried out for about 1 minute to about 20 minutes. 12. The particles produced have a thickness of greater than 0.1 um and a thickness of about 0.3 to 10 um. 2. The method of claim 1, having an equivalent circular diameter. 13. Claim 12, wherein the method is completed in less than 100 minutes. Method described. 14. Claim 10: Aging is carried out for about 3 minutes to about 7 minutes at a pH of about 9 to about 11. Method described.