【発明の詳細な説明】[Detailed description of the invention]
本発明はハロゲン化銀乳剤の製造法に関し、詳
しくは有機ゼラチン凝集剤を用いるハロゲン化銀
乳剤の脱塩・水洗工程の改良に関する。
一般に写真用ハロゲン化銀乳剤はその製造工程
中に、物理熟成終了後、過剰のハロゲン化物、副
生された硝酸塩、アンモニヤ等を除き、更にハロ
ゲン化銀乳剤を濃縮するための脱塩・水洗工程が
含まれる。
この脱塩・水洗工程の方法としては、種々の方
法があるがゼラチンを凝析する薬品を添加してハ
ロゲン化銀粒子を包含して凝析沈降させて上澄液
を捨て、デカンテーシヨンで２〜３回水洗して脱
塩する凝析沈降法が広く用いられている。凝析沈
降法には、硫酸塩法、有機溶媒法、有機ゼラチン
凝集剤法、ゼラチン誘導体法があるが、近年有機
ゼラチン凝集剤法がその操作が容易なことから広
く実用されている。脱塩方法については写真工学
の基礎（日本写真学会編・コロナ社）に詳しく述
べられている。
有機ゼラチン凝集剤法というのは、スルホン酸
基またはカルボン酸基を持つ水溶性高分子化合物
あるいは比較的分子量の大きい界面活性剤をゼラ
チン−ハロゲン化銀乳剤に添加し、PHを下げ（通
常PH５以下）凝析沈降させ、上澄液を捨て、デカ
ンテーシヨンで水洗し脱塩する方法である。
この方法においては、ハロゲン化銀粒子を包含
して凝析されるゼラチン凝集物粒子（以下、凝集
物と言う）の粗さと、凝集物が沈降した時の嵩の
高さが重要なポイントとなる。凝集物が細かすぎ
ると、凝析時あるいはデカンテーシヨンによる水
洗時の凝集物の沈降速度が遅くなり沈降時間が長
くなる。又凝集物が固まり状になつてしまうと沈
降速度は速いが、デカンテーシヨンによる水洗で
の水洗効率が悪くなる。
凝集物の沈降時の嵩も重要で、嵩が高ければ凝
析時あるいは水洗時に捨てる上澄液の量が少なく
なり、水洗効率及びハロゲン化銀乳剤の濃縮率が
低くなる。したがつて脱塩・水洗工程は凝集物の
粗さが適当で沈降速度が速く、かつ凝集物の沈降
時の嵩ができるだけ低いということが要求され
る。これらの要求を満たすために通常は凝析時の
ゼラチン濃度、PH、有機凝集剤の量、攪拌速度等
の条件を適度に選び凝析が行なわれるが、その効
果は不安定で理論的な解析もされていなく、経験
的あるいは試行錯誤によつて凝析条件が決められ
ていた。又、脱塩・水洗工程時の温度は重要な条
件であるが、硫酸塩法や有機溶媒法に於いては、
水洗工程中に乳剤の凝集物の溶解をさけるため通
常20℃以下で水洗が行なわれるのが常法で、水洗
工程中は塩類又は溶媒の濃度が極度に低くなるた
め、ゼラチンの溶解される温度以上で水洗を行う
と凝集物が溶解してしまい水洗は不可能になる。
有機ゼラチン凝集法ではゼラチンと有機ゼラチン
凝集剤をPH５以下で結合させることにより、乳剤
を凝集させる方法であるため、ゼラチンの溶解温
度より高い温度で水洗を行つても凝集物の溶解は
起らない。しかし従来の方法では乳剤の凝集物の
溶解を恐れ硫酸塩法や有機溶媒法と同様にゼラチ
ンの溶解温度以下で水洗工程を行うのが常法であ
つた。
本発明の目的はハロゲン化銀乳剤の脱塩・水洗
工程を効果的に行う方法を提供することである。
本発明者は、脱塩・水洗工程での凝集物の沈降
時間の短い、かつ沈降した凝集物の嵩の低くなる
即ち乳剤の濃縮率の高くなる条件を種々検討した
結果、脱塩・水洗工程の凝析時及びデカンテーシ
ヨンによる水洗時の温度が、非常に重要な因子
で、低温では凝集物が細かくて沈降速度が遅く、
かつ凝集物の沈降時の嵩が高くなり、高温ではそ
の逆の効果があり、さらにその効果的な限界の温
度が28℃であること見いだした。すなわちハロゲ
ン化銀乳剤の脱塩・水洗工程を有機ゼラチン凝集
剤法で行う場合、有機ゼラチン凝集剤でゼラチン
を凝集させ上澄液を捨て、デカンテーシヨンによ
つて水洗する操作を28℃以上で行うことにより、
凝析時及びデカンテーシヨンによる水洗時の凝集
物粒子を適度に粗くして沈降速度を速くし、かつ
沈降した凝集物の嵩を低くすることができ本発明
の目的を達成することができた。
本発明の効果の第１は脱塩・水洗工程時間を短
縮することができ、第２はハロゲン化銀乳剤の濃
縮率をより高くすることができることである。
本発明の凝集時及びデカンテーシヨンによる水
洗時の温度は28℃以上であれば沈殿速度を速く、
凝集物及び沈降した凝集物の嵩を低くすることが
できるが、温度が高ければ高いほどその効果は大
きい。しかし45℃以上になると凝集物が粘着性を
帯びるため望ましくなく、好ましくは28℃〜40℃
の範囲で目的とする沈降時間と濃縮率に合わせ温
度を選択すればよい。また凝析時の温度を28℃以
下（例えば20℃）で行つた場合（この時には凝集
物は細かく、嵩も高い）でも水洗時の温度を28℃
以上に上げることにより凝集物を粗く、嵩を低く
することができる。
本発明の温度の効果は、その効果的な限界温度
（28℃）がほぼゼラチンゼリーの融点と一致する
ことから、凝析時及び水洗時に凝集物粒子の回り
のゼラチンがわずかに溶解して、凝集物同志が融
着し、粒子が粗くなるものと本発明者は考えてい
る。
本発明に用いられるゼラチンは通常ハロゲン化
銀乳剤に用いられるゼラチン（例えばアルカリ法
ゼラチン、酸性法ゼラチン、脱塩、低カルシウム
ゼラチン等）であればよく、要するに有機ゼラチ
ン凝集剤で凝析されるゼラチンであれば特に限定
されない。
本発明で用いられる有機ゼラチン凝集剤として
は、スルホン酸基またはカルボン酸基を持つ水溶
性高分子化合物あるいは比較的分子量の大きい界
面活性剤で、特開昭58−140322に多く記載されて
いる。特に代表的なものとして下記に示される如
き重合体を上げることができる。
ｍは重合度で又ａ〜ｄは組成比でこれらの有機
ゼラチン凝集剤は分子量1000〜100000の範囲のも
のである。
市販品としてVersaTL（カネボウ・エヌエスシ
ー株式会社）Scripset（米国モンサント社）EMA
（米国モンサント社）等の市販品がある。
本発明に用いられる有機ゼラチン凝集剤は他の
凝集剤例えば硫酸塩（硫酸マグネシウム、硫酸ソ
ーダ等）と併用してもよく、併用しても本発明の
効果は損なわれない。
本発明に用いられる有機ゼラチン凝集剤の使用
量はハロゲン化銀乳剤中のゼラチン固形重量に対
し３〜50重量％用いられるが、再溶解性を考慮す
ると３〜20重量％が望ましい。又凝析させるPHは
５以下、望ましくは３〜4.5が良好である。
本発明の適用されるハロゲン化銀乳剤はゼラチ
ンを主体としたハロゲン化銀乳剤で白黒乳剤、か
ぶらされた直接ポジ用乳剤、カラー乳剤、塩化銀
乳剤、臭化銀乳剤、塩臭化銀乳剤、沃臭化銀乳
剤、シングルジエツト乳剤、ダブルジエツト乳剤
等で乳剤の種類やハロゲン化銀粒子の大きさに限
定されない。又ハロゲン化銀乳剤の銀量とゼラチ
ンの比及び過剰ハロゲン量にも特に限定されな
く、銀とゼラチンの比及び過剰ハロゲン量によつ
て本発明の効果は損なわれない。
本発明に用いられるハロゲン化銀乳剤の凝析時
のゼラチン濃度は0.3〜３重量％で好結果を与え
るが、それ以上の濃度であつても有機ゼラチン凝
集剤、PH等を、適度に調節することに本発明の効
果を得ることができる。
本発明の適用されるハロゲン化銀乳剤はゼラチ
ンを主体としたハロゲン化銀乳剤であるが、他の
水溶性の高分子化合物（例えば、ヒドロキシメチ
ルセルロース、カルボキシメチルセルロース、ア
クリル酸、ポリアクリルアミド、ポリビニルアル
コール、等）を有機ゼラチン凝集剤による凝析に
支障のない範囲でゼラチンと併用することができ
る。
実施例 １
ハロゲン化銀乳剤中のゼラチン濃度２重量％、
銀（硝酸銀に換算して）とゼラチンの比が５：
１、pAg6.5の塩化銀ダブルジエツト乳剤80gを目
盛付の100mlビーカに採り、ゼラチン固形量に対
し、明細書記載のNo.１有機ゼラチン凝集剤（５重
量％水溶液）を10重量％になるように攪拌しなが
ら添加し、PHを1N硫酸で3.0〜3.4に調製し、表・
１の条件に従つてハロゲン化銀乳剤を凝析する。
さらに凝集物がビーカの底に完全に沈降（上澄液
が透明になる）するまで静止した後、上澄液を沈
降した凝集物表面ぎりぎりまで捨て、純水80mlを
加え３分間攪拌し水洗する。浮き上がつた凝集物
がビーカの底に完全に沈降するまで静止した後、
上澄液を捨てる。このデカンテーシヨンによる水
洗を２回くりかえす。各温度における凝析時及び
水洗時の凝集物の沈降時間、沈降した凝集物の嵩
及び形状を測つた結果を表・１にまとめる。
The present invention relates to a method for producing a silver halide emulsion, and more particularly to an improvement in the desalting and water washing process of a silver halide emulsion using an organic gelatin flocculant. Generally, during the manufacturing process of photographic silver halide emulsions, after physical ripening, excess halides, by-produced nitrates, ammonia, etc. are removed, and the silver halide emulsion is further concentrated through a desalting and water washing process. is included. There are various methods for this desalting and water washing process, but a chemical that coagulates the gelatin is added to cause the silver halide grains to be included and coagulate, and the supernatant liquid is discarded, followed by decantation. The coagulation-sedimentation method, which involves washing with water two to three times and desalting, is widely used. Coagulation-sedimentation methods include a sulfate method, an organic solvent method, an organic gelatin flocculant method, and a gelatin derivative method, and in recent years, the organic gelatin flocculant method has been widely put into practice because of its ease of operation. Desalination methods are described in detail in Basics of Photographic Engineering (edited by the Photographic Society of Japan, published by Corona Publishing). The organic gelatin flocculant method involves adding a water-soluble polymer compound with a sulfonic acid group or a carboxylic acid group or a surfactant with a relatively large molecular weight to a gelatin-silver halide emulsion to lower the pH (usually PH5 or less). ) This method involves coagulation and sedimentation, discarding the supernatant liquid, and washing with water using decantation to desalt. In this method, the important points are the roughness of the gelatin aggregate particles (hereinafter referred to as aggregates) that are coagulated and include silver halide grains, and the bulk of the aggregates when they settle. . If the aggregates are too fine, the settling speed of the aggregates during coagulation or washing with water by decantation will be slow and the settling time will be long. Furthermore, if the aggregate becomes a lump, the sedimentation speed is high, but the washing efficiency in water washing by decantation becomes poor. The volume of the flocculates during settling is also important; if the volume is high, the amount of supernatant liquid to be discarded during coagulation or washing with water will be reduced, resulting in lower washing efficiency and concentration ratio of the silver halide emulsion. Therefore, in the desalting and water washing process, it is required that the coarseness of the aggregates be appropriate, that the sedimentation rate be high, and that the bulk of the aggregates when settling is as low as possible. In order to meet these requirements, coagulation is usually performed by appropriately selecting conditions such as gelatin concentration, pH, amount of organic flocculant, and stirring speed during coagulation, but the effect is unstable and requires theoretical analysis. Coagulation conditions were determined empirically or by trial and error. In addition, the temperature during the desalting and water washing process is an important condition, but in the sulfate method and organic solvent method,
In order to avoid the dissolution of emulsion aggregates during the water washing process, water washing is usually carried out at a temperature below 20°C.During the water washing process, the concentration of salts or solvents is extremely low, so the temperature at which gelatin is dissolved is If water washing is performed in the above condition, the aggregates will dissolve and water washing will become impossible.
In the organic gelatin flocculation method, the emulsion is flocculated by combining gelatin and organic gelatin flocculant at a pH of 5 or less, so even if washing is performed at a temperature higher than the dissolution temperature of gelatin, the aggregates will not dissolve. . However, in conventional methods, fearing the dissolution of emulsion aggregates, it has been common practice to carry out the water washing step at a temperature below the melting temperature of gelatin, similar to the sulfate method and organic solvent method. An object of the present invention is to provide a method for effectively carrying out desalting and water washing steps of silver halide emulsions. As a result of various studies on conditions that would shorten the sedimentation time of the aggregates in the desalting/washing process and reduce the bulk of the sedimented aggregates, that is, increase the concentration ratio of the emulsion, the inventors found that the desalting/washing process The temperature during coagulation and washing with water during decantation is a very important factor; at low temperatures, the aggregates are fine and the sedimentation rate is slow;
It was also found that the bulk of the aggregates increases when they settle, and that the opposite effect occurs at high temperatures, and that the effective limit temperature is 28°C. In other words, when desalting and washing the silver halide emulsion with water using the organic gelatin flocculant method, the gelatin is flocculated with the organic gelatin flocculant, the supernatant liquid is discarded, and the process of washing with water by decantation is carried out at 28°C or above. By doing
The purpose of the present invention was achieved by making the aggregate particles moderately coarse during coagulation and washing with water by decantation, thereby increasing the settling speed and reducing the volume of the settled aggregates. . The first effect of the present invention is that the desalting and water washing process time can be shortened, and the second effect is that the concentration ratio of the silver halide emulsion can be further increased. If the temperature during coagulation and water washing by decantation of the present invention is 28°C or higher, the precipitation rate will be increased;
The bulk of the aggregates and settled aggregates can be lowered, but the higher the temperature, the greater the effect. However, temperatures above 45°C are undesirable because the aggregates become sticky, and preferably 28°C to 40°C.
The temperature may be selected within the range according to the desired sedimentation time and concentration rate. In addition, even if the temperature during coagulation is 28℃ or lower (for example, 20℃) (at this time, the aggregates are fine and bulky), the temperature during washing with water should be 28℃ or lower (for example, 20℃).
By increasing the amount above, it is possible to make the aggregate coarser and lower the bulk. The temperature effect of the present invention is that the effective limit temperature (28°C) almost matches the melting point of gelatin jelly, so gelatin around the aggregate particles is slightly dissolved during coagulation and washing with water. The present inventor believes that the aggregates fuse together and the particles become coarse. The gelatin used in the present invention may be any gelatin normally used in silver halide emulsions (for example, alkaline method gelatin, acid method gelatin, desalted gelatin, low calcium gelatin, etc.), and in short, gelatin coagulated with an organic gelatin flocculant. If so, there are no particular limitations. The organic gelatin flocculant used in the present invention is a water-soluble polymer compound having a sulfonic acid group or a carboxylic acid group, or a surfactant having a relatively large molecular weight, and many are described in JP-A No. 140322/1983. In particular, the following polymers can be cited as typical examples. m is the degree of polymerization, and a to d are the composition ratios, and these organic gelatin flocculants have a molecular weight in the range of 1,000 to 100,000. Commercially available products include VersaTL (Kanebo NSC Corporation), Scripset (Monsanto Corporation, USA), and EMA.
There are commercially available products such as (Monsanto Company, USA). The organic gelatin flocculant used in the present invention may be used in combination with other flocculants such as sulfates (magnesium sulfate, sodium sulfate, etc.), and the effects of the present invention will not be impaired even if they are used in combination. The amount of the organic gelatin flocculant used in the present invention is 3 to 50% by weight based on the solid weight of gelatin in the silver halide emulsion, and preferably 3 to 20% by weight in consideration of resolubility. Further, the pH for coagulation is preferably 5 or less, preferably 3 to 4.5. The silver halide emulsions to which the present invention is applied include gelatin-based silver halide emulsions such as black and white emulsions, fogged direct positive emulsions, color emulsions, silver chloride emulsions, silver bromide emulsions, silver chlorobromide emulsions, The emulsion may be a silver iodobromide emulsion, a single jet emulsion, a double jet emulsion, etc., and is not limited by the type of emulsion or the size of the silver halide grains. The ratio of silver to gelatin and the amount of excess halogen in the silver halide emulsion are not particularly limited either, and the effects of the present invention are not impaired by the ratio of silver to gelatin and the amount of excess halogen. Good results are obtained when the gelatin concentration during coagulation of the silver halide emulsion used in the present invention is 0.3 to 3% by weight, but even if the concentration is higher than that, the organic gelatin flocculant, pH, etc. must be appropriately adjusted. In particular, the effects of the present invention can be obtained. The silver halide emulsion to which the present invention is applied is a silver halide emulsion mainly composed of gelatin, but other water-soluble polymer compounds (for example, hydroxymethyl cellulose, carboxymethyl cellulose, acrylic acid, polyacrylamide, polyvinyl alcohol, etc.) can be used in combination with gelatin to the extent that it does not interfere with coagulation with an organic gelatin flocculant. Example 1 Gelatin concentration in silver halide emulsion 2% by weight,
The ratio of silver (in terms of silver nitrate) to gelatin is 5:
1. Put 80g of silver chloride double jet emulsion with pAg6.5 into a 100ml beaker with a scale, and add No. 1 organic gelatin flocculant (5% by weight aqueous solution) described in the specification to 10% by weight based on the solid amount of gelatin. with stirring, adjust the pH to 3.0 to 3.4 with 1N sulfuric acid, and
The silver halide emulsion is coagulated according to the conditions of 1.
Furthermore, after standing still until the aggregates have completely settled to the bottom of the beaker (the supernatant liquid becomes transparent), discard the supernatant liquid until it reaches the surface of the settled aggregates, add 80 ml of pure water, stir for 3 minutes, and wash with water. . After the flocs have settled until they have completely settled to the bottom of the beaker,
Discard the supernatant. Repeat this decantation process twice. Table 1 summarizes the results of measuring the sedimentation time of the aggregates during coagulation and washing with water at each temperature, and the volume and shape of the sedimented aggregates.
【表】【table】
【表】
表・１に示されるように20℃、26℃に比べ28
℃、35℃では凝集物の沈降速度が速く、嵩も低く
なる。
実施例 ２
ハロゲン化銀乳剤中のゼラチン濃度1.7重量％、
銀とゼラチンの比が９：１、pAg7.6の臭化銀ダ
ブルジエツト乳剤70gを目盛付の100mlビーカに
採り、ゼラチン固形量に対し明細書記載のNo.２有
機ゼラチン凝集剤（５重量％水溶液）を20重量％
になるように攪拌しながら添加し、PHをIN硫酸
で3.0〜3.4に調製した後、次いで硫酸マグネシウ
ム水溶液（MgSO4・7H2Ｏ 50重量％）を乳剤
全量に対し15重量％を添加し表・２の条件に従つ
て、ハロゲン化銀乳剤を凝析する。以下実施例１
と同様の方法で凝集物を沈降させ、上澄液を捨
て、純水を70ml加え水洗を２回行う。各温度にお
ける凝析時及水洗時の凝集物の沈降時間、沈降し
た凝集物の嵩及び形状を測つた結果を表・２に示
す。[Table] As shown in Table 1, 28℃ compared to 20℃ and 26℃
At 35°C and 35°C, the sedimentation rate of the aggregates is fast and the bulk is low. Example 2 Gelatin concentration in silver halide emulsion 1.7% by weight,
Place 70 g of silver bromide double-jet emulsion with a silver to gelatin ratio of 9:1 and a pAg of 7.6 in a 100 ml beaker with a scale. ) 20% by weight
After adjusting the pH to 3.0 to 3.4 with IN sulfuric acid, an aqueous solution of magnesium sulfate (MgSO 4 7H 2 O 50% by weight) was added in an amount of 15% by weight based on the total amount of the emulsion. - Coagulate the silver halide emulsion according to the conditions in 2. Example 1 below
Sediment the aggregates in the same manner as above, discard the supernatant liquid, add 70 ml of pure water, and wash twice with water. Table 2 shows the results of measuring the settling time of the aggregates during coagulation and washing with water at each temperature, as well as the volume and shape of the settled aggregates.
【表】
表・２に示すように、凝析・水洗時の温度が20
℃と28℃以上では沈降速度及び嵩に明らかに差が
あり、20℃では水洗することにより嵩は高くなる
が、28℃以上では嵩は低くなつていく。又20℃で
凝析を行つても水洗時の温度を高く（37℃）する
ことにより沈降速度は速くなり、嵩も低くなる。[Table] As shown in Table 2, the temperature during coagulation and water washing is 20
There is a clear difference in sedimentation rate and bulk at temperatures above 28°C and 28°C; at 20°C, the bulk increases when washed with water, but above 28°C, the bulk decreases. Furthermore, even if coagulation is carried out at 20°C, increasing the water washing temperature (37°C) will increase the sedimentation rate and reduce the bulk.