EP0366418A2

EP0366418A2 - Ultrarapidly processable silver halide photographic light sensitive material

Info

Publication number: EP0366418A2
Application number: EP89310961A
Authority: EP
Inventors: Haruhiko Konica Corporation Sakuma
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 1988-10-25
Filing date: 1989-10-24
Publication date: 1990-05-02
Also published as: JP2835344B2; JPH02262645A; EP0366418A3

Abstract

A silver halide photographic material for the use of taking a CRT picture is disclosed. The photographic material has an orthochromatically spectrally sensitized silver halide emulsion layer on one side of the support, and an amount of the silver in the emulsion layer is not more than 3.60 g/m² and a specific characteristic curve is obtained by an exposure with a CRT of RMA No. P. 45 for 1 second and developed within 16 sec.

Description

FIELD OF THE INVENTION

The present invention relates to a silver halide photographic light-sensitive material for CRT picture taking, specifically of an ultrarapidly processable silver halide photographic light-sensitive material for CRT picture taking with good image contrast.

BACKGROUND OF THE INVENTION

Silver halide photographic light-sensitive materials for CRT picture taking used to obtain hard copy films of CRT images and for other purposes.
None of this kind of conventional light-sensitive materials for CRT picture taking which have been developed so far is suitable for ultrarapid processing such that the developing time is less than 16 seconds. With the trend toward rapider processing in the field of light-sensitive materials, suitability to such ultrarapid processing has become more desired in light-sensitive materials for CRT picture taking as well.
Any light-sensitive material for CRT picture taking needs to show only a small variance of photographic properties due to changes in processing conditions, as well as to permit ultrarapid processing as described above.
Improvement in such rapid processability and processing stability may be achievable by reducing the amount of silver in the light-sensitive silver halide. However, if the amount of silver is reduced for this purpose, for example below 3.60 g/m², it becomes necessary to reduce the grain size of silver halide grains or take other measures to obtain a sufficiently high maximum density, which in turn may lead to significant decrease in sensitivity. Sensitivity reduction necessitates the lengthening of taking time or increase in the luminance of CRT, causing image quality degradation.
For this reason, in conventional methods, it has been inevitable to use a large amount of silver halide grains of large grain size (thus having weak covering power) such that the amount of silver used exceeds 3.60 g/m² to maintain high sensitivity to ensure the desired maximum density. It has therefore been impossible to constantly obtain satisfactory processing stability; for example, the range of variance of gamma values broadens due to changes in processing conditions, fogging increases and fixability is degraded.

SUMMARY OF THE INVENTION

The object of the present invention is to solve these problems and provide and ultrarapidly processable silver halide photographic light-sensitive material for CRT picture taking having good processing stability and satisfactory levels of sensitivity and maximum density.
The silver halide photographic light-sensitive material for CRT picture taking of the present invention has at least one orthochromatically spectrally sensitized light-sensitive silver halide emulsion layer on one side of the support. The silver content in the light-sensitive emulsion layer side of the silver halide photographic light-sensitive material is not more than 3.60 g/m², and the characteristic curve obtained by 1 seconds of exposure with a CRT of RMA No. P. 45 has a G_A/G_B value of not less than 0.69 and not more than 0.88, wherein G_A represents the gamma value of the linear line between densities 0.5 and 1.5 G_B represents the gamma value of the linear line between densities 1.5 and 2.5, with a G_C value of not less than 2.4, wherein G_C represents the gamma value of the linear line between densities 1.0 and 2.0.
In the present invention, the characteristic curve is defined as a photographic characteristic curve showing the relationship between the logarithmic amount of exposure logE plotted on the abscissa and image density D plotted on the ordinate. Gamma value is defined as the gradient of the linear line between two points on the characteristic curve (tan ϑ, if the angle of the linear line and the abscissa is represented by ϑ). Also, the characteristic curve to specify the gamma values G_A, G_B and G_C in the present invention is obtained by exposing the silver halide photographic light-sensitive material using a CRT of RMA No. P. 45 for 1 second. The light-sensitive material of the present invention satisfies the above-mentioned requirements as to gamma values when the developing time is less than 16 seconds, wherein developing time is defined as the time for the light-sensitive material sample to become in contact with the surface of the fixer from its contact with the surface of the developer. The gamma value G_A, G_B and G_C in the characteristic curve in the present specification represent figures obtained by processing the light-sensitive material after exposure for 1 second using the above-mentioned CRT in the Konica automatic developing machine SRX-501 with a total processing time of 45 seconds (corresponding to 14.8 seconds of developing), using the developer XD-SR at developing temperature of 35°C (a starter was used), and the fixer XF-SR at a fixing temperature of 33°C. The CRT used for exposure had the RMA number mentioned above, by which the phosphor emitting the exposure light and its emission spectrum are specified.
Any mode can be employed to make the gamma values fall in the above ranges; the gamma values can be kept in the ranges according to the present invention by controlling the average grain size, grain size distribution and other parameters of the emulsion.
The silver halide grains should contain silver iodide at not less than 0.2 mol% and not more than 3.80 mol%; the silver iodide should be AgBrI, AgClBrI or AgClI, and AgBrI is preferable. Also it is preferable that the silver iodide content be not less than 0.5 mol% and not more than 3.0 mol%.

DETAILED EXPLANATION OF THE INVENTION

Particularly preferable is the mode using a monodispersed emulsion as described below.
Various modes of embodiment of the present invention are possible; a preferred mode of embodiment of the present invention is to use a monodispersed emulsion for the light-sensitive silver halide emulsion layer. The use of a monodispersed emulsion yields high gamma values and good linearity in the characteristic curve, and is advantageous as to sensitivity. Also, the effect of the present invention is enhanced, since the variance of the G_A/G_B ratio is small even when processing conditions have changed.
Moreover, the use of a monodispersed emulsion makes it easy to keep the G_A/G_B and GC values in the ranges according to the present invention.
In the present invention, monodispersed emulsion has the following relationship:
where r represents the number-average grain size and S represents the standard deviation.
Grain size may be calculated from the diameter of a circle converted from the projection area of the silver halide grain in electron micrograph. Grain size may also be calculated by Stokes diameter measurement based on the centrifugal precipitation liquid phase method. Grain size distribution may also be determined from electron micrograph and other means.
The light-sensitive material of the present invention may comprise two or more emulsions with different average grain sizes (it is preferable that all constituent emulsions be monodispersed).
The silver halide photographic light-sensitive material of the present invention has at least one orthochromatically spectrally sensitized light-sensitive silver halide emulsion layer on one side of the support. This emulsion layer may have a single-layer structure or multilayer structure. It is preferable to form a protective layer on the emulsion layer (opposite side to the support). On the side opposite to the light-sensitive silver halide emulsion layer of the support, a hydrophilic colloidal layer may be formed for a backing layer. This backing layer may have a single-layer structure of multilayer structure. Any orthochromatically spectrally sensitizing dye can be used to orthochromatically spectrally sensitizing the silver halide emulsion layer. For example, the spectrally sensitizing dyes described in Research Disclosure Vol.176, No. 17643 (1978) and Vol.187, No. 18716 (1976).
In the embodiment of the present invention, there is no particular limitation posed on the grain shape, structure or other feature of the silver halide grains used in the light-sensitive silver halide emulsion layer, but it is preferable to use the grains described in Japanese Patent Publication Open to Public Inspection No. 23154/1988 and Japanese Patent Application No. 6890/1987 and it is possible to use tabular grains as disclosed in Japanese Patent Publication Open to Public Inspection Nos. 113927/1983, 113928/1983, 105636/1984 and 147727/1985.
Although it is preferable to use monodispersed silver halide grains as stated above, ordinary polydispersible grains and the above-mentioned tabular grains can be used in combination at any ratio.
It is preferable that the support for the present invention be a flexible support which is normally used for photographic light-sensitive materials. The support may be colored with dyes or pigments. It may be colored black for the purpose of shading.
The surface of these supports may be subbed as usual to ensure good adhesion to the photographic emulsion layer etc.
In the embodiment of the present invention, the light-sensitive silver halide etc. used in the light-sensitive emulsion layer of the light-sensitive material may be present in dispersion in an appropriate binder in the photographic structural layer. Various hydrophilic colloids can be used as binders; typically, gelatin is preferably used. Gelatins which can be used include lime-treated gelatin, acid-treated gelatin, enzyme-treated gelatin, gelatin hydrolyzates, gelatin enzymolyzates and other gelatin derivatives. It is also possible to use gelatins comprising synthetic polymers such as polyvinyl alcohol.
The same applies to the hydrophilic colloid used to form the backing layer.
When using a hardener, the amount of water absorption can be adjusted to the desired level by controlling the amount of the hardener, as stated above.
The silver halide photographic light-sensitive material of the present invention may contain a hardener in any layer.
The hardener is normally used as needed in combination with other various film property improving agents to improve the physical properties of the coated film prepared in the presence of a hydrophilic colloid as binder.
When using a hardener, the amount of water absorption can be adjusted to the desired level by controlling the amount of the hardener.
The use of a vinyl sulfone hardener as described below in the silver halide photographic light-sensitive material of the present invention enhances the effect of the present invention, i.e., the effect in which the variance of photographic characteristics due to changes in processing conditions is lessened.
Here, the vinyl sulfone hardener means a compound having a vinyl group bound to a sulfonyl group or a group capable of forming a vinyl group. It is preferable that the vinyl sulfone hardener have at least two vinyl groups each bound to a sulfonyl group or two groups each capable of forming a vinyl group. For example, the compound represented by the following formula is preferably used in the light-sensitive material of the present invention.
L-(SO₂-X)_m
In the above formula [VS-I], L represents a m-valent group; X represents -CH=CH₂ or -CH₂CH₂Y; Y represents a group capable of splitting off in the form of HY in the presence of a base, e.g. a halogen atom, sulfonyloxy group, sulfoxy group (including salts) and tertiary amine.
The examples of preferable groups for X include -CH=CH₂ and -CH₂CH₂Cl.
m represents an integer of 2 to 10; when m is 2 or more, the -SO₂-X units may be identical or not.
The m-valent binding group L is formed with one or more of aliphatic hydrocarbon groups (e.g. alkylene, alkylidine, alkylidine groups and groups formed by their binding), aromatic hydrocarbon groups (e.g. arylene and other groups and groups formed by their binding), and bonds represented by -0-, NR′- (R′ represents a hydrogen atom or alkyl group preferably having 1 to 15 carbon atoms), -S-, -N-, -CO-, -SO-, -SO₂- or -SO₃-; when two or more NR′- units are contained, their R′ moieties may bind together to form a ring. The binding group L also include those having a hydroxy group, alkoxy group, carbamoyl group, sulfamoyl group, alkyl group, aryl group or other substituent.
Representative examples of vinyl sulfone hardeners which can preferably be used in the embodiment of the present invention are given below. VS - 1 H₂C=CHSO₂CH₂SO₂CH=CH₂
VS - 2 H₂C=CHSO₂(CH₂)₂SO₂CH=CH₂
VS - 3 H₂C=CHSO₂(CH₂)₃SO₂CH=CH₂
VS - 4 H₂C=CHSO₂CH₂OCH₂SO₂CH=CH₂
VS - 5 H₂C=CHSO₂(CH₂)₂O(CH₂)₂SO₂CH=CH₂
VS - 6 H₂C=CHSO₂CH₂
CH₂SO₂CH=CH₂

VS - 7 H₂C=CHSO₂CH₂
CH₂
CH₂SO₂CH=CH₂

VS - 8 H₂C=CHSO₂CH₂CONHCH₂NHCOCH₂SO₂CH=CH₂
VS - 9 H₂C=CHSO₂CH₂CONH(CH₂)₂NHCOCH₂SO₂CH=CH₂
VS - 10 H₂C=CHSO₂CH₂CONHCH₂CH₂CH₂NHCOCH₂SO₂CH=CH₂

VS - 20 [(H₂C=CHSO₂)₃CCH₂SO₂(CH₂)₂SCH₂]₂CO
VS - 22 (H₂C=CHSO₂CH₂)₄C
VS - 24 (H₂C=CHSO₂CH₂)₃CC₂H₅
VS - 30 H₂C=CHSO₂(CH₂)₂SO₂(CH₂)₂SO₂CH=CH₂
VS - 31 H₂C=CHSO₂(CH₂)₂O(CH₂)₂NHONH(CH₂)₂O(CH₂)₂SO₂CH=CH₂
VS - 35 (H₂C=CHSO₂NH)₂CH₂
VS - 36 H₂C=CHSO₂(CH₂)₂NH(CH₂)₂NH(CH₂)₂SO₂CH=CH₂

VS - 41 C₈H₁₇C(CH₂SO₂CH=CH₂)₃
VS - 44 CH₂(CONHCH₂SO₂CH=CH₂)₂
VS - 46 C[CO(CH₂)₂SO₂CH=CH₂]₄
VS - 48 NH[(CH₂)₂SO₂CH=CH₂]₂
VS - 49 CH₃C(CH₂OCH₂SO₂CH=CH₂)₃
VS - 50 C(CH₂OCH₂SO₂CH=CH₂)₄
VS - 51 N[(CH₂)₂OCH₂SO₂CH=CH₂]₃
VS - 52 (CH₂=CHSO₂CH₂)₃CCHSO₂(CH₂)₂Cℓ
VS - 53 H₂C=CHSO₂CH=CH₂
VS - 54 H₂C=CHSO₂CH₂C(CH₂SO₂CH₂CH₂OSO₃^⊖Na^⊕)₃
VS - 55 CH₃SO₃(CH₂)₂SO₂(CH₂)₂OSO₂CH₃
The examples of vinyl sulfone hardeners which can be used for the present invention include the aromatic compounds described in West German Patent No. 1,100,942 and US Patent No. 3,490,911 the alkyl compounds bound via hetero atom described in Japanese Patent Examined Publication Nos. 29622/1969, 25373/1972 and 24259/1972, the sulfonamide ester compounds described in Japanese Patent Examined Publication No. 3736/1972, the 1,3,5-tris (β-(vinylsulfonyl)-propionyl]-hexahydro-s-triazine described in Japanese Patent Publication Open to Public Inspection No. 24435/1974, the alkyl compounds described in Japanese Patent Examined Publication No. 35807/1975 and Japanese Patent Publication Open to Public Inspection No. 44164/1979 and the compounds described in Japanese Patent Publication Open to Public Inspection No. 19844/1984.
It is preferable to use the vinyl sulfone hardener in solution in water or organic solvent at 0.005 to 20% by weight relative to the binder (e.g. gelatin), more preferably 0.02 to 10% by weight.
Its addition to the photographic structural layer is achieved by the batch method, in-line addition method and other methods.
There is no particular limitation posed on the choice of the layer to which the hardener is added; for example, the hardener may be added to the uppermost layer, lowermost layer, at least one other layer, or all layers.
The light-sensitive material of the present invention may contain other additives as needed.
The light-sensitive material of the present invention has a light-sensitive silver halide emulsion layer on only one side of the support. It is preferable that the thickness of the structural layer on the emulsion layer side be not more than 3.9 µm. It is also preferable that the dissolution time of the light-sensitive emulsion layer in an aqueous solution of sodium hydroxide at 50°C be between 12 minutes and 130 minutes. Here, the dissolution time is defined as the time for a 1 cm wide emulsion layer sample being vertically immersed and kept standing in a 1.5 wt% aqueous solution of sodium hydroxide to become dissolved.
The light-sensitive material of the present invention may contain other additives as needed, which are described in Research Disclosure Vol. 176, No. 17643 (December 1978) and Vol.187, No. 18716 (November 1976).
Any method can be used as appropriate to process the light-sensitive material of the present invention according to the specific light-sensitive material.
The processing solutions such as developers and fixers used to process the light-sensitive material can also be chosen as appropriate according to the light-sensitive material.
It is preferable, from the viewpoint of the balance of developability, fixability and dryability, to process the light-sensitive material of the present invention under conditions to which the following relationship applies.
1^0.75 x T = 50 to 124
0.7 < ℓ < 4.0
where 1 represents the processing length (unit: m) in the processing of the silver halide photographic light-sensitive material, and T represents the time (unit: seconds) for the light-sensitive material to pass through the above length 1.
Also, it is preferable to process the light-sensitive material of the present invention using an automatic developing machine. In this case, it is particularly preferable to use a roller transportation type automatic developing machine under conditions to which the following relationship applies.
1^0.75 x T = 50 to 124
0.7 < ℓ < 4.0
where 1 represents the length (unit: m) between the core of the first roller at the insertion port of the roller transportation type automatic developing machine and the core of the final roller at the drying exit; and T represents the time (unit: seconds) for the light-sensitive material to pass through the above length 1.
When using an automatic developing machine for processing, it is preferable that the automatic developing machine be of the roller transportation type. In this case, it is preferable that the number of transportation rollers by such that the quotient obtained by dividing the processing length 1 by the number of rollers falls in the range of from 0.01 to 0.04. It is also preferable that the time for each processing procedure be in the following range:

Insertion + development + transition 25 to 40%

Fixation + transition 12 to 25%

Washing + transition 10 to 25%

Squeezing + drying 25 to 45%

Total 100%

Examples

The present invention is hereinafter described in more detail by means of the following examples.

Example 1

Grain preparation ①

Monodispersed emulsion silver iodobromide grains of 0.395 µm in average grain size having an average silver iodide content of 2.2 mols were prepared by growing silver iodobromide containing 30 mol% silver iodide at pH 9.8 and pAg 7.8 in the presence of monodispersed silver iodobromide grains of 0.2 µm in average grain size containing 0.2 mol% silver iodide as core grains, and subsequently adding equal mols of potassium bromide and silver nitrate at pH 8.2 and pAg 9.1.
The emulsion was desalted to remove excess salts by an ordinary coagulation method. Accordingly, coagulation was conducted by adding a formalin condensation product of sodium naphthalenesulfonate and an aqueous solution of magnesium sulfate while maintaining the emulsion at 40°C. After supernatant removal, pure water below 40°C was added, and this was followed by the addition of an aqueous solution of magnesium sulfate to coagulate the emulsion. The resulting supernatant was removed.
The dispersibility of the grain size of the silver halide grains thus obtained was found to be S/r = 0.15, showing good monodispersibility.

Grain preparation ②

A polydispersible emulsion was prepared by the normal mixing method as follows:

Solution A

Silver nitrare 100 g

Aqueous ammonia (28%) 60 cc

Add water to reach 240 cc.

Solution B

Ossein gelatin 8 g

Potassium bromide 80 g

Potassium iodide 2.2 g

Add water to reach 550 cc.

Solution C

Aqueous ammonia 6 cc

Glacial acetic acid 10 cc

Water 34 cc

Solution D

Glacial acetic acid 226 cc

Add water to reach 400 cc.
These four solutions (Solutions A through D) were first prepared.
Next, Solutions B and C were fed into a reaction vessel for emulsion preparation and agitated using a propeller type agitator at 300 rpm, while maintaining a reaction temperature of 48°C. Then, Solution A was divided into two portions in a volume ratio of 1 to 2. The one-volume portion (100 ml) was added to the mixture of Solutions B and C over a period of 55 seconds. After agitation for 10 seconds, the two-volume portion (200 ml) was added over a period of 2 minutes, and agitation was continued for 20 minutes. To the resulting mixture of Solutions A, B and C, was added Solution D; the mixed solution in the reaction vessel was adjusted to pH 6 and the reaction was stopped. A polydispersied emulsion of 0.390 µm in average grain size having an average iodide content of 2.2 mol% was thus obtained. The dispersibility of the grain size of these silver halide grains was found to be 5/r = 0.34.

Sample preparation, processing and evaluation

To the silver ahlide grains ① and ② thus obtained, pure water was added so that the water volume per mol silver halide became 500 ml. After heating this mixture to 55°C, the following spectrally sensitizing dyes A and B, in a weight ratio of 200 to 1, were added at 300 mg in total per mol silver halide. Ten minutes after, ammonium thiocyanate at 2.6 x 10⁻³ mol per mol silver and appropriate amounts of chloroauric acid and hypo were added to initiate chemical ripening at pH 6.15 and silver potential of 50 mV.
Fifteen minutes before completion of the chemical ripening (70 minutes after initiation of the chemical ripening), potassium iodide was added at 200 mg per mol silver; after 5 minutes, 10% (W/V) acetic acid was added to reduce the pH value to 5.6 and this pH value was maintained for 5 minutes. Then, a 0.5% (W/V) potassium hydroxide solution was added to increase the pH value to 6.15, and this was followed by the addition of 4-hydroxy-6-methyl-1, 3,3a,7-tetraazaindene to stop the chemical ripening to yield a photographic emulsion for coating.
The photographic emulsion for coating had a pH of 6.10 and a silver potential of 81 mV at 35°C immediately after preparation.
This coating emulsion was used to prepare samples as follows: Samples were prepared by coating the emulsion so that the photographic emulsion layer had a gelatin content of 2.0 g/m² and a silver content of 2.8 to 4.2 g/m² as shown in Table 1 having a thickness of 3.8 µm in case of silver content is 4.2 g/m² and the protective layer as prepared with the additives listed below had a gelatin content of 1.15 g/m², and coating the lower and upper backing layer solutions shown below on the back of the photographic emulsion layer so that the lower backing layer had a gelatin content of 3.0 g/m² and the upper backing layer had a gelatin content of 1.2 g/m². Coating was conducted simultaneously on both faces of a polyethylene terephthalate film base of 175 µm in thickness coated with an aqueous copolymer dispersion for subbing obtained by diluting a copolymer comprising three monomers of 50 wt% glycidyl methacrylate, 10 wt% methyl acrylate and 40 wt% butyl methacrylate to a copolymer concentration of 10 wt%, using two units of slide hopper type coater at a speed of 80 m per minute, and this was followed by drying for 2 minutes and 20 seconds. The resulted samples had an emulsion layer having a dissolution time of 47-51 min in an aqueous solution of 1.5 wt% sodium hydroxide.
The obtained samples were exposed to gray scale light for 1 second using a Konica imaging camera M.M (P. 45 phosphor), and then processed using a Konica automatic developing machine SRX-501, developer XD-SR and fixer XF-SR in the 45-second mode (developing temperature 35°C and 32°C) or the 90-second mode (developing temperature 32°C) to yield samples 1 through 30. The 45-second mode corresponded to 14.8 seconds of development, and the 90-second mode corresponded to 25.5 seconds of development.
In the automatic developing machine used for processing, the fixing temperature was 33°C and washing water was supplied at 18°C at a flow rate of 1.5 1 per minute.
The maximum density, G_A, G_B G_A/G_B and G_C of each sample were measured. The results are given in Table 1.
Sensitivity is expressed by relative values to the reciprocal of the exposure amount by which a blackening density of +1.0 fogging is obtained in Sample No. 1, taken as 100.
The following spectrally sensitizing dyes were used for sample preparation.

Spectrally sensitizing dye A

Spectrally sensitizing dye B

The following additives were used in the emulsion (light-sensitive silver halide coating solution). The amount of addition is expressed per mol silver halide.
The following additives were used in the protective layer solution. The amount of addition is expressed per 1 coating solution.
In addition to these additives, the following compound (1) was added to the coating emulsion in accordance with the method described in Example 1 (3) of Japanese Patent Publication Open to Public Inspection No. 285448/1986. Specifically, the compound (1) was dissolved in an oil comprising the compound (2) and then dispersed in a hydrophilic colloidal solution; the resulting dispersion was added so that the compound (1) and (2) were contained at the following contents per mol silver ahlide.
The following solutions were prepared and used for the backing layer.

Backing dye A

Backing dye B

As seen in Table 1, the samples in accordance with the present invention show a small variance of gamma values G_A, G_B and G_C and sensitivity due to changes in processing temperature and processing time, having stable performance. It is also evident that the performance is not easily affected by changes in the amount of silver adhesion during the production process.
Also, stabler performance was obtained in the samples using a monodispersed emulsion comprising Grain 1.
Sample Nos. 1 through 30 were rated as to post-processing residual silver in the fogged portion by dripping an aqueous solution of sodium sulfide to determine the degree of coloring; it was found that significant deterioration occurs and the preservability is questionable in the samples processed by the 45-second mode with silver coating ratio of 3.7 g/m² or more.
As stated above, the present invention provides an ultrarapidly processable silver halide photographic light-sensitive material for CRT picture taking having good processing stability and satisfactory levels of sensitivity and maximum density.

Example 2

Preparation of silver halide grain 3

To 5.5 ℓ of a 1.5% gelatin solution containing 0.17 M potassium bromide were added 2.1 M potassium bromide and 2.0 M silver nitrate in solution by the double jet method over a period of 2 minutes while agitating the solution at 80°C and pH 5.9. The pBr value was maintained at 0.8 (0.53% of the total amount of silver nitrate used was consumed). The addition of the potassium bromide solution was stopped and a silver nitrate solution was added over a period of 46 minutes (8.6% of the total amount of silver nitrate used was consumed). A potassium bromide solution and a silver nitrate solution were concurrently added over a period of 13 minutes, while maintaining a pBr value of 1.2 and accelerating the addition so that the addition flow rate at completion of the addition was 2.5 times that at initiation of the addition (43.6% of the total amount of silver nitrate used was consumed). The addition of the potassium bromide solution was stopped and a silver nitrate solution was added over a period of 1 minute (4.7% of the total amount of silver nitrate used was consumed).
A 2.0 M potassium bromide solution containing 0.55 M potassium iodide, together with a silver nitrate solution, was added over a period of 133 minutes, while maintaining a pBr value of 1.7 and accelerating the addition so that the flow rate at completion of the addition was 1.5 times that at initiation of the addition (35.9% of the total amount of silver nitrate used was consumed). To this emulsion was added 1.5 g/mol Ag sodium thiocyanate; this mixture was kept standing for 25 minutes. A 0.60 M potassium iodide solution and silver nitrate were added at constant flow rate by the double jet method over a period of about 5 minutes until the pBr value reached 3.0 (about 6.6% of the total amount of silver nitrate used was consumed). The total amount of silver nitrate consumed was about 11 mols. An emulsion containing tabular silver iodobromide grains of 1.62 µm in average grain size having an aspect ratio of about 16 to 1 was thus obtained. These grains occupied over 80% of the total projection area of silver iodobromide grains, though the above-mentioned spectrally sensitizing dyes A and B, in a weight ratio of 200 to 1, were added thereto at 1000 mg in total per mol silver halide before desalting.
The spectrally sensitizing dyes were added at pH 7.60; 15 minutes after, phenylcarbamylated gelatin was added and the pH value was reduced with acetic acid to cause coagulation, and this was followed by supernatant removal.

Sample preparation, processing and evaluation

Samples were prepared by chemical ripening in the same manner as in Example 1 and subsequent coating and drying in the same manner as in Example 1 using the same emulsion additives and protective layer solutions as those in Example 1.
Other samples were prepared in the same manner as in Example 1 except that the vinyl sulfone hardeners listed in Table 2 were used in place of the hardeners used in the protective layer solutions in Example 1, i.e., sodium salt of 2,4-dichloro-6-hydroxy-1,3,5-triazine, formalin and glyoxal, and were rated in the same manner as in Example 1. The each resulted sumples had an emulsion layer having the dissolution time of 38-44 min.
The results are given in Table 2.

Claims

1. A silver halide photographic material having a silver halide emulsion layer comprising at least one orthochromatically spectrally sensitized silver halide emulsion layer on one side of the support, wherein the amount of silver in the emulsion layer is not more than 3.60 g/m² and the characteristic curve obtained by developing within 16 sec the silver halide material exposed to a cathode ray tube of RMA (EIA - Electronics Industries Association) No. P. 45 for 1 second has a G_A/G_B value of not less than 0.69 and not more than 0.88, wherein G_A represents the gamma value of the linear line for densities of 0.5 to 1.5 and G_B represents the gamma value of linear line for densities of 1.5 to 2.5 and a G_C value of not less than 2.4, wherein G_C represents the gamma value of the linear line for densities of 1.0 to 2.0.

2. A silver halide photographic material as claimed in claim 1 wherein the silver halide emulsion layer comprises a monodispersed emulsion.

3. A silver halide photographic material as claimed in claim 1 or 2 wherein the silver halide grains of the silver halide emulsion contain not less than 0.2 mol% silver iodide.

4. A silver halide photographic material as claimed in claim 3 wherein the silver halide grains of the silver halide emulsion contain not less than 0.5 mol% silver iodide.

5. A silver halide photographic material as claimed in any one of claims 1 to 4 wherein the silver halide grains of the silver halide emulsion contain not more than 3.8 mol% silver iodide.

6. A silver halide photographic material as claimed in claim 5 wherein the silver halide grains of the silver halide emulsion contain not more than 3.0 mol% silver iodide.

7. A silver halide photographic material as claimed in any one of claims 1 to 6 wherein the silver halide emulsion layer comprises a vinyl sulfone hardener.

8. A silver halide photographic material as claimed in any one of claims 1 to 7 wherein the dissolution time of the silver halide emulsion layer in a 1.5 wt% aqueous solution of sodium hydroxide at 50°C is from 12 to 130 minutes.

9. A silver halide photographic material as claimed in claim 8 wherein the dissolution time of the silver halide emulsion layer in a 1.5 wt% aqueous solution of sodium hydroxide at 50°C is from 40 to 60 minutes.

10. A silver halide photographic material as claimed in any one of claims 1 to 9 wherein the total thickness of the layers on the silver halide emulsion layer side on the support is not more than 3.9 µm.